WO2006003638A2 - Novel method for labeling nucleic acid in a sequence-specific manner, and method for detecting nucleic acid using the same - Google Patents

Novel method for labeling nucleic acid in a sequence-specific manner, and method for detecting nucleic acid using the same Download PDF

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Publication number
WO2006003638A2
WO2006003638A2 PCT/IB2005/052245 IB2005052245W WO2006003638A2 WO 2006003638 A2 WO2006003638 A2 WO 2006003638A2 IB 2005052245 W IB2005052245 W IB 2005052245W WO 2006003638 A2 WO2006003638 A2 WO 2006003638A2
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nucleic acid
labeled
template nucleic
template
nucleotide
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PCT/IB2005/052245
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French (fr)
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WO2006003638A3 (en
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Ichiro Mitsuhara
Yuko Ohashi
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National Institute Of Agrobiological Sciences
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Priority to JP2007519959A priority Critical patent/JP4729677B2/en
Publication of WO2006003638A2 publication Critical patent/WO2006003638A2/en
Publication of WO2006003638A3 publication Critical patent/WO2006003638A3/en

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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/68—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
    • C12Q1/6813—Hybridisation assays
    • C12Q1/6816—Hybridisation assays characterised by the detection means
    • C12Q1/682—Signal amplification

Definitions

  • Thepresentinvention relatestoamethodforlabeling a nucleic acid and a method for producing a labeled nucleic acid, and a method for detecting a nucleic acid using these methods, and a kit and a system using these methods.
  • RNAs such as siRNA, miRNA, and the like.
  • siRNA small RNAs
  • miRNA small RNAs
  • the important in vivo functions of these RNAs have recently been revealed. Therefore, the development of a technique for detecting such RNAs would lead to further elucidation of their functions .
  • a technique for simply detecting a nucleic acid such as various RNAs or the like.
  • An object of the present invention is to provide a technique capable of simply detecting a nucleic acid (particularly, small RNAs, etc.) .
  • the present inventors unexpectedly found that small RNAs can be labeled and/or detected by utilizing a hybridization technique in a sequence specific manner, and completed the present invention. As a result, the above-described problem was solved.
  • Small RNAs play an important role in gene regulation including transcription, translation and mRNA stability as well as maintenance of chromosome structure. Further, they contribute to the defense of host cells by degrading invading viralRNAandsilencingselfishtransposons.
  • the small RNA world is now a technological field in the research of the animal and plant kingdoms.
  • detection methods for the small RNAs are complicated and inefficient.
  • the present invention provides a method for detecting small RNAs by sequence specific labeling by dideoxy nucleotide using DNA template and DNA polymerase.
  • Small RNA are hybridized with template DNA substantially complementary to the target small RNA and thentheDNA-RNAhybridare incubatedwiththeKlenowfragment of DNA polymerase I and 32 P-labeled dideoxy nucleotide or deoxy nucleotide.
  • the small RNAs act as primers for DNA synthesis and the reaction is directly terminated by incorporation of dideoxy nucleotide. Thus, this is called "Primer Halt".
  • the labeled RNAs can be detected after separation by denaturing gel electrophoresis followed by autoradiography. The labeling is sequence specific and fully dependent on the presence of DNA polymerase.
  • RNA e.g., miRNA frommouse and siRNA fromtransgenicplants, etc.
  • native RNA e.g., miRNA frommouse and siRNA fromtransgenicplants, etc.
  • the GFP gene, luciferase gene, miR16, miR171, or the like may be used.
  • Amethod forproducing a nucleic acidhaving an introduced label comprising the steps of: A) providing a nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acidhaving a nucleotide sequence of at least one nucleotide extending from at least oneendofthenucleicacidtobelabeledwhenthecomplementary- portion of the nucleic acid to be labeled hybridizes with the template nucleic acid;
  • nucleic acid to be labeled is DNA, RNA, or a combination thereof. 3. A method according to item 1, wherein the nucleic acid to be labeled is RNA.
  • RNA selected from the group consisting of siRNA and miRNA.
  • Amethodaccordingto item 1 wherein the template nucleic acid has a nucleotide sequence of at least one nucleotide extending from both ends of the nucleic acid to be labeled.
  • the template nucleic acid has a nucleotide sequence extending by at least about 10 nucleotides from the at least one end of the nucleic acid to be labeled.
  • a method according to item 1 wherein the extending nucleotide sequence of the template nucleic acid is located on the 5 ⁇ terminal side of the template nucleic acid, and a 5' terminalportion ofthe nucleicacidtobe labeledextends from the 3' end of the template nucleic acid.
  • a method according to item 6 wherein the extending nucleotide sequence of the template nucleic acid on the 3' terminal side of the template nucleic acid is longer by a distinguishable length than that of the extendingnucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
  • a method according to item 13, wherein the nucleic acid synthesizing enzyme is DNA-dependent DNA polymerase or RNA-dependent DNA polymerase.
  • the labeled nucleotide includes a nucleotide labeled with a label selected from the group consisting of fluorescence, radioactivity, phosphorescence, biotin, digoxigenin (DIG) , an enzyme, and chemiluminescence.
  • a label selected from the group consisting of fluorescence, radioactivity, phosphorescence, biotin, digoxigenin (DIG) , an enzyme, and chemiluminescence.
  • a method according to item 30, wherein the modification is selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , • thiolation, and rhodamination.
  • FITC fluoresceinisothiocyanatation
  • TAMRA tetramethylrhodamination
  • FITC fluoresceinisothiocyanatation
  • TAMRA tetramethylrhodamination
  • thiolation thiolation
  • rhodamination 35.
  • nucleic acid to be labeled-template nucleic acid complex subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid.
  • Amethod for detecting a target nucleic acid comprising the steps of:
  • a method according to item 36 further comprising separating unreacted matter of the labeled nucleotide and the extension product from the resultant mixture, after the extension reaction.
  • Amethodaccordingto item 36, wherein the targetnucleic acid is DNA, RNA, or a combination thereof.
  • RNA selected from the group consisting of siRNA andmiRNA is RNA selected from the group consisting of siRNA andmiRNA.
  • a method according to item 36, wherein the extending nucleotide sequence of the template nucleic acid is located on the 5' terminal side of the template nucleic acid.
  • a method according to item 42 wherein the extending nucleotide sequence of the template nucleic acid on the 3' terminal side of the template nucleic acid has a different length than that of the extending nucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
  • a method according to item 42 wherein the extending nucleotide sequence of the template nucleic acid on the 3' terminal side of the template nucleic acid is longer by a distinguishable length than that of the extendingnucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
  • a method according to item 36, wherein the nucleic acid synthesizing enzyme is DNA-dependent DNA polymerase or RNA-dependent DNA polymerase.
  • the labeled nucleotide includes a nucleotide labeled with a label selected from the group consisting of fluorescence, radioactivity, phosphorescence, biotin, digoxigenin (DIG) , an enzyme, and chemiluminescence.
  • a label selected from the group consisting of fluorescence, radioactivity, phosphorescence, biotin, digoxigenin (DIG) , an enzyme, and chemiluminescence.
  • a method according to item 36 further comprising recovering the extensionproduct corresponding to the target nucleic acid.
  • the separating and detecting steps are achieved by autoradiography.
  • a method according to item 66, wherein the modification is selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
  • FITC fluoresceinisothiocyanatation
  • TAMRA tetramethylrhodamination
  • thiolation thiolation
  • rhodamination tetramethylrhodamination
  • modification selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
  • a kit for producing a nucleic acid having an introduced label comprising:
  • a kit according to item 72 further comprising: ameans forseparatingunreactedmatterofthelabeled nucleotide and an extension product from the resultant mixture.
  • kits according to item 71 further comprising: a reference target nucleic acid as a control.
  • kits according to item 75 wherein the standard nucleic acid includes a nucleic acid selected from the group consisting of a nucleic acid for identifying the template nucleic acid and a nucleic acid for identifying the target nucleic acid.
  • a kit according to item 71 further comprising: a support, wherein the template nucleic acid is immobilized on the support. 80. A kit according to item 79, wherein the support is made of glass or membrane.
  • a kit according to item 82, wherein the modification is selected from the group consisting of , fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA), thiolation, and rhodamination.
  • FITC fluoresceinisothiocyanatation
  • TAMRA tetramethylrhodamination
  • thiolation thiolation
  • rhodamination tetramethylrhodamination
  • FITC tetramethylrhodamination
  • TAMRA tetramethylrhodamination
  • a method for producing a support having a label-introduced nucleic acid immobilized thereon comprising the steps of:
  • a kit for detecting a target nucleic acid comprising:
  • a kit according to item 90 further comprising: ameans forseparatingunreactedmatterofthe labeled nucleotide and an extension product from the resultant mixture.
  • a kit accordingto item 90 wherein a terminal nucleotide of the template nucleic acid is modified.
  • Amethod for detecting a target nucleic acid on a support having a nucleic acid immobilized thereon comprising the steps of:
  • nucleic acid to be labeled hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex
  • a method according to item 93, wherein the nucleic acid to be labeled is siRNA.
  • Amethod for detecting a target nucleic acid on a support having a nucleic acid immobilized thereon comprising the steps of:
  • a nucleic acid that is being labeled e.g., DNA, RNA
  • a template nucleic acid e.g., template DNA in a primer halt method; a target nucleic acid in a primer array method
  • DNA synthesis is conducted where the nucleic acid being labeled is used as a primer.
  • a labelled chemical compound is used as a nucleotide which is to be newly added in the DNA synthesis.
  • the target nucleic acid is either RNA or DNA.
  • the present invention is highly useful as a method for labeling short-strandedRNA.
  • the label maybe a radioactive isotope, a fluorescent dye, or the like. Amethodusing a radioactive isotope was demonstrated herein.
  • the labeled nucleic acid can be detected using the labelled chemical compound as an indicator. In the case of a radioactive label, autoradiography or the like may be used.
  • DNA synthesis reactions for labeling can be terminated by a dideoxylation method. This method is called a primer halt method.
  • Template DNA needs to have a sequence portion complementary to a target nucleic acid.
  • a target nucleic acid is a small RNA, such as miRNA, having a known sequence
  • the length and sequence of a portion of the template nucleic acid extending before or after the target nucleic acid can be arbitrarily selected.
  • DNA synthesis using the target nucleic acid as a primer can be limited to a predetermined length (limited DNA synthesis) . This technique is called primer run-off method.
  • the labeledtargetnucleic acid canbe detectedafter separation using gel electrophoresis.
  • a combinationoflimitedDNAsynthesisandgelelectrophoresis the length (base pairs) of the target nucleic acid can be known.
  • This technique may be applied to a detecting method using a fluorescent label and a capillary sequencer.
  • the technique can be applied to a method for detecting siRNA andmiRNAirrespective oftheir origin, i.e. plants, animals, and fungi.
  • the technique can be applied to a method for specifically labelingthe sequence of ageneral nucleic acid, but is not limited to short-stranded RNA.
  • an end of ssDNA can be labeled in a sequence specific manner. In situ labeling is possible. Other various applications are possible.
  • a fluorescent dye can be incorporated into a nucleotide by, for example, but not limited to, using an amino group introducing reagent (e.g., 2- (4-monomethoxytritylamino) ethyl- (2-cyanoethyl) - (N,N-d iisopropyl) -phosphoramidite, etc.), a thiol group introducing ⁇ reagent
  • an amino group introducing reagent e.g., 2- (4-monomethoxytritylamino) ethyl- (2-cyanoethyl) - (N,N-d iisopropyl) -phosphoramidite, etc.
  • a thiol group introducing ⁇ reagent
  • the present invention also provides a novel nucleic acid detecting method, which has novelty andutility because it can directly label a nucleic acid in a sequence-specific manner. Inaddition, byselectinganucleotideoratemplate, the length of a label can be regulated, i.e., limited to 1 to several bases.
  • the present invention is also effective as a method for detecting short-stranded RNA, such as siRNA involved in RNA silencing which has recently attracted attention, miRNA which has attracted attention as a part of a gene expression regulating mechanism after transcription.
  • the present invention has, for example, the following advantages and effects:
  • nucleic acid to be labeled can be directly labeled, unlike Northern blotting or the like;
  • the detection sensitivity is comparable with or higher than conventional techniques which are considered to have high sensitivity.
  • (atto (ICT 18 ) molar level This is equal to the detection limit of a commercially available kit based on RNase protection, i.e., champion data. Note that since RNase protection uses RNase, it is disadvantageously difficult to eliminate the possibility that the detected RNA is an artifact. Manipulation in the method of the present invention is faster and simpler than conventional techniques.); and
  • siRNA or miRNA cannot be detected unless small RNA fractions are purified.
  • total RNA can be used.
  • Figure 1 is an explanation of the primer haltmethod.
  • small RNA a short-stranded RNA which is a target of the detection
  • template DNA DNA which is a template for the detection.
  • synthetic ssDNA was used, however the present invention is not limited thereto.
  • DNA pol. DNA polymerase.
  • Klenow fragment was used, but the present invention is not limited thereto.
  • a reverse transcriptation enzyme is alsopossible.
  • DideoxyNTPs were labeledwithalabelingagent such as 32 P or the like.
  • DNA polymerase is used to label a short-stranded RNA, with the short-stranded RNA hybridized to the DNA, by a DNA synthesis reaction, using a primer.
  • dideoxyNTP was incorporated therein and the reaction terminated.
  • Figure 2 dipicts sequences of synthetic DNA and RNA used in a model experiment as demonstrated in the Examples.
  • DNA 1 and 2 are part of an ORF in the sense direction of the GFP gene.
  • the RNA has a sequence of 21 nucleotides in length, complementary to a part of the DNA.
  • the Figure shows the conditions in which hybridization has occurred. During the reaction with RNA as a primer, one base is added to the 3' terminus of the RNA, a dATP is incorporated into the combination of DNAl-RNAl, and a dTTP is incorporated into the combination of DNA2-RNA2. No homology is found between DNAl and RNA2, and DNA2 and RNAl.
  • Figure 3 dipicts model experiments of the primer halt methodandtheprimer run-offmethod.
  • pol. Klenow fragment;
  • sRNA (synthetic RNA) synthetic RNAl or RNA 2.
  • DNAandRNAare respectivelymixedwith 1 pmol 33 P-dideoxy NTP in a Klenow reaction solution, denatured at 95 °C and hybridized by letting the temperature return to room temperature. Klenow enzyme was added thereto, and the DNA synthesis reaction was conducted by using sRNA as a primer. No nucleotides other than dideoxyNTP labeled with 33 P were added thereto. Labeled RNA was electrophoresed in a denaturing acrylamide gel, and detected by autoradiogram. The combinations of DNAl-RNAl, DNA2-RNA2 were found to incorporate 33 P in a polymerase dependent manner, indicating that the present method can label a short-stranded RNA in a sequence-specific manner.
  • Figure 4 dipicts the measurement of the detection limit of the primer halt method and detection of miRNA from an organism by the primer halt method. Small RNA was serially dilutedby one tenth to calculate the detection sensitivity.
  • the left lanes are as follows:
  • Detection of a dilution series of synthetic RNA as in (a) the right-most two lanes show detection of miRNA contained in the total RNA prepared from a plant.
  • Luc reaction in which a part of the luciferase gene, luc, not encoded by a plant, was used as a template for the negative control.
  • MiR171 a primer halt method using a sequence complementary to miR171, which is a plant endogenous micro RNA (miRNA) , plus a sequence comprising a single base of T. As such, a plant endogenous miRNA may be detected.
  • miRNA plant endogenous micro RNA
  • Figure 4B depicts confirmation of miRNA in a mouse by the primer run-off method of the present invention.
  • Figure 5 dipicts the rationale of the primer halt method.
  • Figure 6 dipicts the rationale of the primer run-off method.
  • Figure 7 dipicts the rationale of the primer array method.
  • SEQ ID NO. : 3 DNAl (m-GFP5-ER-S 725-812)
  • SEQ ID NO. : 4 DNA2 (m-GFP5-ER-S 572-670)
  • SEQ ID NO. : 7 Ntab miRl67
  • SEQ ID NO. : 8 Mmus miRl ⁇ l T
  • SEQ ID NO. : 9 Mmus miRl6 T
  • SEQ ID NO. : 16 RNA 1-ClO (amplified product using DNA 1-GlO (SEQ ID NO.: 14))
  • polynucleotide oligonucleotide
  • nucleic acid oligonucleotide
  • nucleic acid molecule oligonucleotide molecule
  • examples of suchanucleicacidmolecule include, but are not limited to, cDNA, mRNA, and genomic DNA. These terms also include an "oligonucleotide derivative” or a “polynucleotide derivative”.
  • oligonucleotide derivative or a “polynucleotide derivative” includes a nucleotide derivative, or refers to an oligonucleotide or a polynucleotide having different linkages between nucleotides fromtypical linkages, whichare interchangeably used.
  • Examples of such an oligonucleotide specifically include 2' -O-methyl-ribonucleotide, an oligonucleotide derivative in which a phosphodiester bond in an oligonucleotide is converted to a phosphorothioate bond, an oligonucleotide derivative in which aphosphodiesterbond in an oligonucleotide is converted to a N3'-P5' phosphoroamidate bond, an oligonucleotide derivative in whichariboseandaphosphodiesterbondinanoligonucleotide are converted to a peptide-nucleic acid bond, an oligonucleotide derivative in which uracil in an oligonucleotide is substituted with C-5 propynyl uracil, an oligonucleotide derivative in which uracil in an oligonucleotide is substituted with C-5 thiazole uracil, an
  • nucleic acid sequence also implicitly encompasses conservatively-modified variants thereof (e.g. degenerate codon substitutions) , complementary sequences, and corresponding sequences (e.g., mouse sequences corresponding to human sequences, etc.) as well as the sequence explicitly indicated.
  • small RNA refers to RNA having a small size, specifically about 50 nucleotides or less in length, more preferably about 30 nucleotides or less in length. Examples of smallRNAinclude, but arenot limited to, miRNA, siRNA, and the like. Recently, small RNA has attracted attention and is said to play an important role in gene regulation, including transcription, translation, and mRNA stability. As used herein, the term “nucleotide” may be either naturally-occurring or nonnaturally-occurring.
  • nucleotide derivative or “nucleotide analog” refers to a nucleotide which is different from naturally-occurring nucleotides andhas a function similar to that of the original nucleotide.
  • nucleotide derivatives and nucleotide analogs are well known in the art. Examples of such nucleotide derivatives and nucleotide analogs include, but are not limited to, phosphorothioate, phosphoramidate, methylphosphonate, chiral-methylphosphonate, 2-0-methyl ribonucleotide, and peptide-nucleic acid (PNA) .
  • a nucleotide When used in an extension reaction, a nucleotide can be in the formof triphosphoric acid.
  • examples ofnucleoside triphosphoric acid include, but are not limited to, deoxyadenosine triphosphoric acid (dATP) , deoxyguanosine triphosphoric acid (dGTP) , deoxycytidine triphosphoric acid (dCTP) , deoxythymidine triphosphoric acid (dTTP) , which are DNA components, deoxyuridine triphosphoric acid (dUTP) , deoxyinosine triphosphoric acid (dITP) , and the like.
  • dATP deoxyadenosine triphosphoric acid
  • dGTP deoxyguanosine triphosphoric acid
  • dCTP deoxycytidine triphosphoric acid
  • dTTP deoxythymidine triphosphoric acid
  • dUTP deoxyuridine triphosphoric acid
  • dITP deoxyinosine triphosphoric acid
  • nucleotide for terminating an extension reaction examples include, but are not limited to, dideoxyadenosine triphosphoric acid (ddATP) , dideoxyguanosine triphosphoric acid (ddGTP) , dideoxycytidine triphosphoric acid (ddCTP) , dideoxythymidine triphosphoric acid (ddTTP) , dideoxyuridine triphosphoric acid (ddUTP) , dideoxyinosine triphosphoric acid (ddITP) , which are used in a dideoxy chain terminator technique, and the like.
  • ddATP dideoxyadenosine triphosphoric acid
  • ddGTP dideoxyguanosine triphosphoric acid
  • ddCTP dideoxycytidine triphosphoric acid
  • ddTTP dideoxythymidine triphosphoric acid
  • ddUTP dideoxyuridine triphosphoric acid
  • ddITP dideoxyinosine triphosphoric acid
  • a nucleotide may be labeled herein.
  • a label include, but are not limited to, any labels using fluorescence, radioactivity, phosphorescence, biotin, DIG, an enzyme, and chemiluminescence.
  • label refers to a factor which distinguishes a molecule or substance of interest from others (e.g., substances, energy, electromagnetic waves, etc.) .
  • labeling methods include, but are not limitedto, RI (radioisotope) methods, fluorescencemethods, biotinylationmethods, chemoluminancemethods, andthe like.
  • Any fluorescent substance which can bind to a base portion of a nucleic acid maybe used, preferably including a cyanine dye (e.g., Cy3 andCy5 intheCyDyeTMseries, etc. ) , arhodamine 6G reagent, N-acetoxy-N2-acetyl amino fluorene (AAF) , AAIF (iodine derivative of AAF), and the like.
  • a cyanine dye e.g., Cy3 andCy5 intheCyDyeTMseries, etc.
  • arhodamine 6G reagent e.g., N-acetoxy-N2-acetyl amino fluorene (AAF)
  • AAF N-acetoxy-N2-acetyl amino fluorene
  • AAIF iodine derivative of AAF
  • fluorescent substances having a difference in fluorescence emission maximum wavelength of 10 nm or more include a combination of Cy5 and a rhodamine 6G reagent, a combination ofCy3andfluorescein, acombinationofarhodamine 6Greagent and fluorescein, and the like.
  • a label can be used to alter a sample of interest so that the sample can be detected by detecting means. Such alteration is known in the art. Those skilled in the art can perform such alteration using a method appropriate for a label and a sample of interest.
  • a label is a radioactive label.
  • a terminal nucleotide of a template nucleic acid may be "modified" herein.
  • a terminal nucleotide of a template nucleic acid is modified so that other nucleotides
  • the end may be either the
  • the term "denaturation" in relation to a nucleic acid refers to a phenomenon that a native three-dimensional structure is lost without cutting a covalent bond.
  • the separation of a nucleic acid is acceleratedbyincludingadenaturingstep, sothatitbecomes easier to recover an elongated nucleic acid to be labeled.
  • the term "remove unreacted matter" in relation to a nucleic acid synthesis reaction refers to removal of an unreacted material (e.g., a labeled nucleotide, etc.) .
  • Unreacted matter to be removed advantageously includes, particularly, a labelednucleotide.
  • the present invention is not limited to this .
  • detection can be performed using only the label of anelongatedproduct as a clue.
  • Unreactedmatter can be removedby, for example, alcohol precipitation (e.g.,
  • the term "separation of a nucleic acid” indicates that a group of certain nucleic acids is separated from a group of nucleic acids having a different property. Such separation can be performed based on a molecular weight, a label, an affinity, or the like as a clue. When separation is performedusing amolecular weight as a clue, the separation can be achievedby electrophoresis. A molecular sieve can be used to achieve separation based on a molecular weight.
  • the removal of a nucleic acid may be simultaneously performed with detection of a label.
  • the detection of a label canbeperformeddirectlyorindirectly.
  • alabel can be directly detected by using a Geiger counter to measure radioactivity; observing fluorescence with a naked eye or a camera; and the like.
  • a label can be indirectly detected by, for example, binding the label with another labeled material and detecting the other labeled material; using an agent for activating the label (biotin, streptoavidin,
  • autoradiography refers nationally or regionally-related medical images.
  • autoradiography refers nationally or regional autoradiography.
  • macro-autoradiography visible autoradiography
  • micro-autoradiography microscopic autoradiography
  • Various detection methods and means can be used in the method of the present invention as long as information of a biological molecule or information attributed to a material interacting with the biological molecule can be detected.
  • theterm X ⁇ specificallyinteractwith" inrelationto abiologicalmolecule indicates that an affinity to the biological molecule is representatively equal to, or higher than, an affinity to other irrelevant polynucleotides or polypeptides (particularly when the biological molecule is a polynucleotide, a polypeptide, or the like, for example, the identity has a homology of less than 30%) .
  • the affinity can be measured by, for example, a hybridization assay, a binding assay, or the like.
  • target nucleic acid refers to a nucleic acidto be subjected to a reaction (e.g, labeling or detection) . Therefore, when labeling is intended, a target nucleic acid and a nucleic acid to be labeled may overlap each other.
  • nucleic acid to be labeled refers to any nucleic acid to be subjected to a labeling method of the present invention.
  • a nucleic acid any arbitrary nucleic acid, may be used.
  • examples of such a nucleic acid to be labeled include, but are not limited to, DNA, RNA, and PNA which allows an extension reaction using a nucleic acid synthesizing enzyme, and the like.
  • Particularly interesting examples of a nucleic acid to be labeled include small RNAs, such as miRNA, siRNA, and the like.
  • Anucleic acid to be labeled is a targetbeing detected in a primer halt method and a primer run-off method, while it is a probe in a primer array method.
  • template nucleic acid refers to any nucleic acid which is used as a template when a nucleic acid to be labeled is labeled in the method of the present invention.
  • the template nucleic acid itself is not labeled.
  • a template nucleic acid is a probe in a primer halt method and a primer run-off method, while it is a target inaprimerarraymethod.
  • Atemplatenucleic acidusedherein is typically complementary to at least a portion (or preferably the entirety) of a nucleic acid to be labeled, and having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid. Therefore, typically, a template nucleic acid is longer than a nucleic acid to be labeled. The present invention is not limited to this. A template nucleic acid may be longer in theextensiondirection (mostlytowardthe 5' end) .
  • a template nucleic acid examples include, but are not limited to, DNA, RNA, andPNAcapableofbecomingatemplateofanextension reaction due to a nucleic acid synthesizing enzyme, and the like.
  • Adifference in lengthbetween a template nucleic acid and a nucleic acid to be labeled may be preferably about 5 nucleotides or more, about 10 nucleotides or more, or about 15 nucleotides or more.
  • the term "distinguishable level" in relation to a difference in length refers to a length with which a difference can be easily recognized in detection.
  • a difference is, for example, at least about 5 nucleotides, preferably about 10 nucleotides.
  • theterm"complementary inrelation to a nucleic acid, refers to the base sequence of the nucleic acid whose bases are replaced with corresponding bases in
  • G are complementary to each other.
  • GIx glutamine or glutamic acid Xaa unknown or other amino acids are known or other amino acids.
  • theterm ⁇ atleastoneend" inrelation to a nucleic acid refers to at least one of the 3' and 5' ends of the nucleic acid.
  • hybridize under stringent conditions refers to conditions commonlyusedandwell known in the art.
  • a polynucleotide can be obtained by conducting colony hybridization, plaque hybridization, Southern blot hybridization, or the like using a polynucleotide selected from the polynucleotides of the present invention. Specifically, a filter on which DNA derived from a colony or plaque is immobilized is used to conduct hybridization at 65°C in the presence of 0.7 to 1.0 M NaCl.
  • a 0.1 to 2-fold concentration SSC (saline-sodium citrate) solution (1-fold concentration SSC solution is composed of 150 mM sodium chloride and 15 mM sodium citrate) is used to wash the filter at 65°C.
  • SSC saline-sodium citrate
  • Polynucleotides identified by this method are referred to as "polynucleotides hybridizingunder stringent conditions". Hybridization can be conducted in accordance with a method describedin, for example, Molecular Cloning2nded. , Current Protocols inMolecularBiology, Supplement 1-38, DNA Cloning 1: Core Techniques, A Practical Approach, Second Edition, Oxford University Press (1995), and the like.
  • hybridizable in relation to a nucleic acid or a polynucleotide refers to a nucleic acid or a polynucleotide which can hybridize other nucleic acids or polynucleotides under the above-described hybridization conditions.
  • the hybridizable nucleicacid includes atleastanucleicacidhavingahomology of at least 60% to the base sequence of DNA encoding a polypeptide having an amino acid sequence as set forth in the Sequence Listing, preferably a nucleic acid having a homology of at least 80%, and more preferably a nucleic acid having a homology of at least 95%.
  • the homology of a nucleic acid sequence may be represented by similarity evaluated with a score using, for example, a search programBLAST using an algorithm developed by Altschul et al. , J. MoI. Biol., 215, 403-410(1990)) .
  • highly stringent conditions refers to those conditions that are designed to permit hybridization of DNA strands whose sequences are highly complementary, and to exclude hybridization of significantly mismatched DNAs.
  • Hybridization stringency is principally determined by temperature, ionic strength, and the concentration of denaturing agents such as formamide.
  • Examples of "highly stringent conditions” for hybridization and washing are 0.0015 M sodium chloride, 0.0015 M sodium citrate at 65-68°C or 0.015 M sodium chloride, 0.0015 M sodium citrate, and 50% formamide at 42 0 C.
  • Examples are 0.1% bovine serum albumin, 0.1% polyvinylpyrrolidone, 0.1% sodium pyrophosphate, 0.1% sodiumdodecyl sulfate (NaDodSCUor SDS) , Ficoll, Denhardt' s solution, and dextran sulfate, although other suitable agents can also be used.
  • concentration and types of these additives can be changed without substantially affecting the stringency of the hybridization conditions.
  • Hybridization experiments are ordinarily carried out atpH 6.8-7.4; however, at typical ionic strength conditions, the rate of hybridization is nearly independent of pH. See Anderson et al., Nucleic Acid Hybridization: A Practical Approach Ch. 4 (IRL Press Limited, Oxford UK) .
  • Agents affecting the stability of the DNA duplex include base composition, length, and degree of base pair mismatch. Hybridization conditions canbe adjustedbythose skilled in the art in order to accommodate these variables and allow DNAs of different sequence relatedness to form hybrids.
  • the melting temperature of a perfectlymatched DNA duplex can be estimated by the following equation:
  • Tm ( 0 C) 81.5 + 16.6 (log[Na + ]) + 0.41 (% G+C) - 600/N - 0.72 (% formamide)
  • N is the length of the duplex formed
  • [Na + ] is the molar concentration of the sodium ion in the hybridization or washing solution
  • % G+C is the percentage of (guanine+cytosine) bases in the hybrid.
  • the melting temperature is reduced by approximately 1°C for each 1% mismatch.
  • the "percentageofsequence identity, homologyor similarity (amino acid, nucleotide, or the like)" can be determined by comparing two optimally aligned sequences over a window of comparison.
  • theterm ⁇ probe refers to a substance forusein searching, whichisusedinabiological experiment, suchas invitroand/orinvivoscreeningorthelike, including, but notbeing limitedto, forexample, anucleic acidmolecule having a specific base sequence or a peptide containing a specific amino acid sequence.
  • nucleic acidmolecule as a common probe include one having a nucleic acid sequence having a length of at least 8 contiguous nucleotides, which is homologous or complementary to the nucleic acid sequence of a gene of interest.
  • a nucleic acid sequence may be preferably anucleicacidsequencehavingalengthofatleast 9contiguous nucleotides, more preferably a length of at least 10 contiguous nucleotides, and even more preferably a length of at least 11 contiguous nucleotides, a length of at least 12 contiguous nucleotides, a length of at least 13 contiguous nucleotides, a length of at least 14 contiguous nucleotides, a length of at least 15 contiguous nucleotides, a length of at least 20 contiguous nucleotides, a length of at least 25 contiguous nucleotides, a length of at least 30 contiguous nucleotides, a
  • the term "primer” refers to a substance required for initiation of a reaction of a macromolecule compoundtobe synthesized, in amacromolecule synthesis enzymatic reaction.
  • anucleic acidmolecule In a reaction for synthesizinganucleic acidmolecule, anucleic acidmolecule
  • RNA complementary to part of a macromolecule compound to be synthesized
  • a nucleic acid molecule which is ordinarily used as a primer includes one that has a nucleic acid sequence having a length of at least 8 contiguous nucleotides, which is complementary to the nucleic acid sequence of a gene of interest.
  • Such a nucleic acid sequence preferably has a length of at least 9 contiguous nucleotides, more preferably a length of at least 10 contiguous nucleotides, even more preferably a length of at least 11 contiguous nucleotides, a length of at least 12 contiguous nucleotides, a length of at least 13 contiguous nucleotides, a length of at least 14 contiguous nucleotides, a length of at least 15 contiguous nucleotides, a length of at least 16 contiguous nucleotides, a length of at least 17 contiguous nucleotides, a length of at least 18 contiguous nucleotides, a length of at least 19 contiguous nucle
  • a nucleic acid sequence used as a primer includes a nucleic acid sequence having at least 70% homology to the above-described sequence, more preferably at least 80%, even more preferably at least 90%, and most preferably at least 95%.
  • An appropriate sequence as aprimer mayvarydepending on the property of the sequence to be synthesized (amplified) .
  • Those skilled in the art can design an appropriate primer depending on the sequence of interest. Such primer design is well known in the art and may be performedmanually or using a computer program (e.g. , LASERGENE, Primer Select, DNAStar) .
  • substitution, addition or deletion for a polypeptide or a polynucleotide refers to the substitution, addition or deletion of an amino acid or its substitute, or a nucleotide or its substitute, with respect to the original polypeptide or polynucleotide, respectively. This is achieved by techniques well known in the art, including a site-specific mutagenesis technique and the like.
  • a polypeptide or a polynucleotide may have any number (>0) of substitutions, additions, or deletions.
  • the number can be as large as a variant having such a number of substitutions, additions or deletions which maintains anintendedfunction (e.g., theinformationtransferfunction of hormones and cytokines, etc.) .
  • a number may be one or several, and preferably within 20% or 10% of the full length, or no more than 100, no more than 50, no more than 25, or the like.
  • DNA synthesis techniques and nucleic acid chemistry for preparing artificially synthesized genes are described in, for example, Gait, M.J. (1985), Oligonucleotide Synthesis: APracticalApproach, IRL Press; Gait, M.J. (1990), Oligonucleotide Synthesis: A Practical Approach, IRL Press; Eckstein, F. (1991), Oligonucleotides and Analogues: A Practical Approach, IRL Press; Adams, R.L. et al. (1992), The Biochemistry of the Nucleic Acids, Chapman & Hall; Shabarova, Z. et al. (1994), Advanced Organic Chemistry of Nucleic Acids, Weinheim; Blackburn, G.M. et al. (1996), Nucleic Acids in Chemistry and Biology, Oxford University Press; Hermanson, G.T. (1996), Bioconjugate Techniques, Academic Press; and the like, related portions of which are herein incorporated by reference.
  • the presence of a nucleic acid can be confirmed by using a molecular biological measuring technique, such as a radioactivity method, a fluorescence method, a Northern blotting method, a dot blotting method, a PCR method, or the like.
  • a molecular biological measuring technique such as a radioactivity method, a fluorescence method, a Northern blotting method, a dot blotting method, a PCR method, or the like.
  • screening refers to selection of a target, such as an organism, a substance, or the like, a given specific property of interest from a population containing a number of elements using a specific operation/evaluation method.
  • a target such as an organism, a substance, or the like
  • the detection/labeling technique of the present invention can be used.
  • hybrid indicates that two or more molecules interact with one another and are assembledas iftheybehavedas a singlemolecule. Therefore, a hybridized nucleic acid-nucleic acid is a complex.
  • nucleic acid synthesizing enzyme refers to any enzyme which has the ability to synthesize a nucleic acid.
  • a nucleic acid synthesizing enzyme is also referred to as polymerase. It is a generic term for enzymes which catalize a reaction which polymerizes nucleotides into a polynucleotide. Examples of such a nucleic acidsynthesizingenzyme include, but are not limited to, DNA polymerase (e.g., DNA-dependent DNA polymerase, RNA-dependent DNApolymerase), RNApolymerase, andthe like.
  • polymerases include, but are not limited to, DNA-dependent DNApolymerase, RNA-dependent DNApolymerase, and the like. For either of the polymerases, either DNA or RNA can be detected. A difference is only which is used as atemplate, DNAorRNA (orboth) (RNA-dependentDNApolymerase also uses DNA as a template; some commercially available DNA-dependent DNApolymerases haveRNA-dependent activity) .
  • Examples of such a polymerase include, but are not limited to, Escherichiacoli-derivedDNApolymerase I, DNApolymerase I Klenow fragment, Taq polymerase, KLA-Taq polymerase, KOD polymerase, Vent polymerase, AMV reverse transcription enzyme, Pfu polymerase, T4 DNA polymerase, and the like.
  • extension reaction in relation to a nucleic acid refers to any reaction which elongates the nucleic acid by at least one nucleotide.
  • a polymerase used for an extension reaction, nucleotides are typically introduced based on a template. Therefore, a specific sequence is elongated for a nucleic acid to be elongated, such as a nucleic acid to be labeled or the like.
  • An extension reaction comprises (i) ahybridization
  • a primer extension product can be denaturated by subjecting a solution containing a primer strand extension product obtained by the above-described extension reaction to heating treatment, for example, at 94 to 95°C for 0.5 to 1 minute.
  • the amplification of a target nucleic acid may be repeatedlyperformedapluralityof times, for example, until a desired amount of the target nucleic acid (nucleic acid to be labeled) is produced. That is, the above-described extensionreactionanddenaturationarerepeatedlyperformed a plurality of times under similar conditions. When the above-describedstep isperformedn times, the initial amount of a target nucleic acid is theoretically amplified by a factor of 2 n"x .
  • the above-describedextension reaction canbe simply and efficiently performed by using a commercially available PCR (polymerase chain reaction) apparatus (e.g., available from Applied Biosystems) .
  • PCR polymerase chain reaction
  • a nucleic acid can be recovered from a mixture by using any method in the art.
  • a recovering method include, but are not limited to, electrophoresis, chromatography, denaturation, alcohol precipitation, affinity purification, antibodies, and the like.
  • a method for producing a nucleic acid having an introduced label comprising the steps of: A) providing the nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid; B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex; C) subjecting the nucleic acid to be labeled-template nucleic acid complex toanextensionreaction, inwhichanucleicacidsynthesizing enzyme and labeled nucleotides are used, so that at least one of the
  • amethodforintroducingalabel intoanucleicacidisprovided comprising the steps of: A) providing the nucleic acid to be labeled and a template nucleic acid, the template nucleic acidbeing complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid; B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid tobe labeled-template nucleic acid complex; and C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the
  • a method for detecting a target nucleic acid comprising the steps of: A) providing the target nucleic acid and a template nucleic acid, the template nucleic acid beingcomplementarytoatleastaportionofthetargetnucleic acid, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid; B) hybridizing the target nucleic acidwiththetemplatenucleicacidtoproduceatargetnucleic acid-templatenucleicacidcomplex; C) subjectingthetarget nucleic acid-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used; and D) detecting when an extension product corresponding to the target nucleic acid is present, the presence of the extension product being an indicator
  • the present invention makes it significantly easier to detect a nucleic acid of interest whose sequence may be partially or totally known orpartiallyortotallyunknown, or the like. This isbecause the unknown nucleic acid itself is labeled. Therefore, it will be understood that methods using a labeled probe are conventionally different from one another in terms of the detection sensitivity, easiness, and the like.
  • the detecting step may further comprise separatingunreacted matter of the labeled nucleotide and the extension product from the resultant mixture, after the extension reaction. This is because the detecting step is made easier.
  • the step of providing a nucleic acid in the method of thepresent invention canbeperformedusing any technique well known in the art (e.g., chemical synthesis, genetic engineering, extraction from organisms, etc.) .
  • a complex for use in the method of the present invention can be obtained by using any well known technique in the art. For example, it will be understoodthat a complex can be generated under commonly used conditions for hybridication as described elsewhere herein.
  • An extension reaction in the method of the present invention can be performed using any method well known in the art.
  • a catalyst for the extensionreaction e.g., anucleicacidsynthesizingenzyme
  • a material for providing conditions for the reaction of the catalyst e.g., a buffer solution, etc.
  • a nucleotide e.g., a label, a non-label, etc.
  • an apparatus for regulating temperature e.g., a constant temperaturebath, etc.
  • the step of recoveing a nucleic acid having an introduced label from the mixture after the extension reaction can be performed using any technique well known in the art.
  • any technique commonly used for purification or separation of a nucleic acid can be used.
  • the step of detectingwhenan extensionproduct correspondingto a target nucleic acid is present can be performed by using any method well known in the art. It shouldbe understood that labeling may be diretly or indirectly carried out.
  • the presence of an extension product is considered to be an indicator for the presence of the above-described target nucleic acid.
  • the extension product cannot be detected unless nucleicacids ofinterest arepresentbefore extension. It is considered that there are a plurality of nucleic acids of interest before extension. Amore detailed detection can be achieved by sequencing the extension product.
  • the extension product can be sequenced by using any technique well known in the art.
  • a nucleic acid to be labeled used in the present invention may be DNA or RNA, or a combination thereof, andmay be preferably small RNA (e.g., siRNA and miRNA) .
  • the complementarity between a template nucleic acid and a nucleic acid to be labeled is preferably so sufficient that an extension reaction can proceed. Such a level of complementarity varies depending on the length, the conditions for an extension reaction, or the like.
  • the vicinity of the 3' end of the nucleic acid to be labeled is preferably suitable for an extension reaction. Particularly, 1 to 2 nucleotides of the 3' end of the nucleic acid to be labeled is preferably completely complementary to the template nucleic acid.
  • the nucleic acid to be labeled when the nucleic acid to be labeled is regarded as a reference, the nucleic acidtobe labeledtypicallyhas at least 50%homology to the template nucleic acid, preferably at least 60%, more preferably at least 70%, even more preferably at least 80%, still more preferably at least 90%, and still even more preferably at least 95%.
  • the entirety of the nucleicacidtobelabeled maybe complementarytothetemplate nucleic acid.
  • the template nucleic acid used in the present invention may have a nucleotide sequence of at least one nucleotide extending from each of both ends of the nucleic acid to be labeled.
  • the extending nucleotide sequence preferably has a length of at least about 2 nucleotides, more preferably at least about 3 nucleotides, even more preferably at least about
  • the template nucleic acid may be modified.
  • the 3' end of the template nucleic acid may be preferably modified. This is because it is possible to prevent an external nucleotide (e.g., a label nucleotide) from being accidentaly incorporated to the 3' end. Therefore, preferably, the terminal nucleotide of the template nucleic acid is modified to prevent the incorporation of a label nucleotide.
  • such modification is selected from the group consisting of dideoxylation, fluoresceinisothiocyanation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
  • FITC fluoresceinisothiocyanation
  • TAMRA tetramethylrhodamination
  • the 3' end of the template nucleic acid is subjected to modification selected from the group consisting of dideoxylation, fluoresceinisothiocyanation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA), thiolation, and rhodamination.
  • modification selected from the group consisting of dideoxylation, fluoresceinisothiocyanation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA), thiolation, and rhodamination.
  • the template nucleic acid and the nucleic acid to be labeled are preferably designed to have different length expected after the extension reaction. It will be understood that such a design varies depending on a detecting method (e.g., a primer halt method, a primer run-off method, a primer array method, etc.) .
  • a primer halt method e.g., dideoxynucleotide or the like is used to stop the extension activity of the polymerase, so that the design can be vaired by controlling a site at which the dideoxynucleotide is incorporated.
  • the nucleotide sequence of at least one nucleotide is added to at least the 5' terminal side of the template nucleic acid.
  • An extension reaction typically occurs at the
  • the present invention is not limited to this.
  • the nucleotide sequence of at least one nucleotide added to the template nucleic acid extending from the portion thereof complementary to the nucleic acid to be labeled may have a different length between the 3' terminal side and the 5' terminal side. This is because it is easier to distinguish the nucleic acid to be labeled from the template nucleic acid.
  • the nucleotide sequence ofat least onenucleotide ofthetemplate nucleic acid extends from the portion thereof complementary to the nucleic acid to be labeled toward the 5' end thereof, while the template nucleic acid is shorter than the nucleic acid to be labeled in the 3' terminal side of the template nucleic acid, i.e., the 5' terminal portion of the nucleic acid to be labeled extends from the 3' end of the template nucleic acid.
  • the template nucleic acid is shorterthanthenucleicacidtobe labeled.
  • an extension product can be distinguished from the template nucleic acidwiththe nakedeye whenelectrophoresis is performed.
  • the distinguishable length varies depending on the detectionmethod. In the case of visual inspection, the distinguishable length may be 1 to 5 nucleotides, preferably at least about 10 nucleotides.
  • the nucleic acid synthesizing enzyme may be a DNA-dependent DNA polymerase or an RNA-dependent DNA polymerase. It will be understood that any synthesizing enzyme can be used as long as an extension reaction is achieved.
  • Examples of a label used in the labeling method of the present invention include, but are not limited to, fluorescence, radioactivity, phosphorescence, biotin, DIG (digoxigenin) , an enzyme, chemiluminescence, and the like.
  • One or a plurality of labels may be used. A plurality of colors can be used in the case of dyes, fluorescence, or the like.
  • radioactivity is used as a label. Ratioactivity allows an atto molar level of detection. The present invention is not limited to this.
  • the step of recovering the elongated nucleic acid to be labeled may comprise a denaturing step.
  • the denaturing step the elongated nucleic acid to be labeled becomes more distinguishable and easier to recover.
  • the method may further comprise removing unreacted matter.
  • the unreacted matter may be noise when a labeled nucleic acid is subsequently used.
  • the unreacted matter may be removed with any available technique, preferably ethanol precipitation (2-propanol precipitation or ethanol precipitation) and filtration. This method is simple.
  • the step of removing unreacted matter may comprise "separating" the elongated nucleic acid to be labeled.
  • the separating step the purityof the elongated nucleic acid to be labeled can be increased.
  • the separating step can be achieved by any technique in the art, preferably electrophoresis or chromatography.
  • the step of recovering the elongated nucleic acid to be labeled may comprise detecting the label.
  • the detecting step may comprise detecting the label directly or indirectly.
  • the method may further comprise separating the elongatednucleic acid to be labeled.
  • separation can be achieved by any technique in the art, preferably electrophoresis or chromatography. These technologies are well known in the art and any suitable embodiment may be used in the present invention as described elsewhere herein.
  • the detecting step may be performed "in the separating step".
  • the separating and detecting steps maybe achieved by autoradiography. In this case, the separating and detecting steps can be performed automatically.
  • the method may further comprise terminating the extension reaction.
  • the terminating step can be achieved by a primer haltmethodoraprimerrun-offmethod.
  • Thepresentinvention is not limited to these. Such a terminating step cannot be conceived by conventional methods. It will be understood that the present invention can provide a highly specific label.
  • the nucleic acid to be labeled may be a nucleic acid of interest whose sequence may be partially or totally known or unknown.
  • the present invention is not limited to this.
  • the nucleic acid to be labeled may be used as a probe.
  • the present invention exhibits a significant effect of detecting a nucleic acid of interest even if the sequence thereof is partially or totally unknown.
  • a nucleic acid to be labeled and a template are hybridized with each other.
  • DNA polymerase and freenucleotides areaddedsothataDNAsynthesis (extension) reaction is performed using the nucleic acid to be labeled as a primer (a probe in some cases) .
  • the nucleic acid can be labeled in a sequence-specific manner.
  • sequence-specific nucleic acid detecting methods such as Southernblotting, Northernblotting, primer extension, RNase protection, microarray, macroarray, and the like, a label is introduced into a probe before hybridization.
  • a nucleic acid to be labeled is hybridized with a nucleic acid (probe) , and thereafter, one of them is used as a primer to perform a DNA synthesis reaction, so that a label is introduced into only the hybridized nucleic acid.
  • a label is typically introduced into a nucleic acid which is used as a target nucleic acid.
  • the present invention is not limited to this. Therefore, a label may be introduced into a nucleic acid which is used as a probe. In the method of the present invention, only the hybridized nucleic acid is labeled.
  • a label is introduced into a nucleic acid to be labeled in a sequence-specific manner.
  • a template nucleic acid plays the role of a probe of conventional techniques. Therefore, a label is introduced into a nucleic acid to be labeled rather than a template nucleic acid.
  • a nucleic acid to be labeled may be used as a probe.
  • the present invention includes a technique for introducing a lable into a probe. Such a technique is required when the method of the present invention is applied to a microarray using mRNA.
  • This method utilizes a template-dependent DNA polymerase, for which either DNA or RNA is used as a primer.
  • a preferable template dependent DNA polymerase is a DNA-dependent DNA polymerase (Klenow fragment, DNA polymerase I, etc.) .
  • AnRNA-dependent DNApolymerase e.g., a reverse transcription enzyme can also be used.
  • either DNA or RNA is used as a primer as described above.
  • These polymerases catalyze a reaction which adds bases complementary to a hybridized nucleic acid at the 3' side of the probe.
  • the reaction typicallyoccursonlyatthe3' "depressionterminus” .
  • the reaction typically does not occur at the 3' "protruding terminus", since a template is not present.
  • the "reverse reaction” can also be performed.
  • Terminate in relation to anextension reaction indicates that anucleic acid synthesis reaction is terminated.
  • tworepresentativetechniques (aprimerhaltmethod and a primer run-off method) can be used. With these techniques, the present invention is also characterized in that the number of label nucleotides incorporated into a nucleic acid can be regulated (limited) .
  • the term "primer halt method” refers to a method for terminating a DNA synthesis (extension) reaction after 1 to several bases or several tens of bases are incorporated into a nucleic acid. Specifically, a nucleotide triphophoric acid, which is incorporated into a nucleic acid but does not allow a subsequent extension reaction caused by a nucleic acid synthesizing enzyme, is added with respect to a DNA synthesis (extension) reaction instead of deoxyribonucleotide which is typically used in DNA synthesis (of cource, instead of ribonucleotide) .
  • Such a nucleotide triphophoric acid includes dideoxyribonucleotides (a mixture or one of ddATP, ddCTP, ddTTP, and ddGTP) .
  • dideoxyribonucleotides a mixture or one of ddATP, ddCTP, ddTTP, and ddGTP.
  • the same principle as that of the dideoxy method used for a DNA sequencing reaction can be used. See Figures 1 and 5 for the principle of the primer halt method.
  • primer run-off method refers to a method for terminating a DNA synthesis reaction, in which a template nucleic acid (probe) is longer by 1 to several bases than a nucleic acid to be labeled at the 3' side of the nucleic acid to be labeled (the 5' side of the probe), i.e., a portion having a length of 1 to several bases of the template nucleic acid extends from the 3' end of the nucleic acid to be labeled, and the synthesis reaction proceeds over the length of the extending portion of the template nucleic acid. See Figure 6 for the principle of the primer run-off method.
  • the primer halt method maybe used in any cases .
  • the primer run-off method is effective when the nucleic acid to be labeled is miRNA (microRNA) having a known sequence.
  • miRNA miRNA
  • siRNA is a mixture of the inactivated gene and complementary small RNA and thus contains various molecules, and therefore, the primer halt method is preferable.
  • the length of a template is not important, and a template of any length can be used.
  • all four label nucleotides ddATP, ddCTP, ddTTP, and ddGTP
  • siRNA contains various molecules, and therefore, the next base cannot be regulated.
  • the present invention is not limited to this. It will be understood by those skilled in the art that only- one label nucleotide can be used, though the sensitivity- is reduced to 1/4.
  • the 5' portion of the template (the 3' side of the target nucleic acid) preferably has a predetermined length (typically, one base) .
  • a portion of the template hybridizing a target is preferably complementary to the target, the sequence of the projecting portion can be arbitrarily selected. Therefore, the template may be designed so that only one of four label nucleotides, i.e., dATP, dCTP, dTTP, and dGTP, is incorporated into the target.
  • the term "primer arraymethod" refers to a method for detecting and quantifying a number of nucleic acids simultaneously.
  • a probe nucleic acid is immobilized on a support, and a complex of the immobilized probe and a nucleic acid to be detected is used to perform a DNA synthesis reaction, so that a label nucleotide is incorporated into the nucleic acid which is thus labeled.
  • a number of nucleic acids can be simultaneously quantified.
  • the nucleic acid to be detected may be either mRNA or small RNA, or in some cases, DNA. Comparing with conventional microarray techniques, a specific label reaction is performed on the support, and therefore, detection can be more efficiently achieved. To date no method capable of analyzing small RNAs comprehensively has been known. See Figure 7 for the principle of the primer array method.
  • the primer halt method is representatively suitable for the detection of siRNA.
  • the primer run-off method is representatively suitable for the detection of miRNA and
  • the primer array method is suitable for the detection of mRNA.
  • the nucleic acid to be labeled is a target nucleic acid (a subject to be detected; e.g., siRNA) , and corresponds to a primer in a polymerase reaction. Therefore, a subject to be detected itself is labeled.
  • a template nucleic acid is a "provision" nucleic acid, such as synthetic DNA or the like, whichcorresponds toaprobe.
  • ssDNA, dsDNA, or the like can be used. Therefore, the template nucleic acid is not labeled.
  • an extension reaction may be terminated by using a nucleotide triphosphoric acid which has a function of terminating an extension reaction of dideoxynucleotide or the like.
  • the nucleic acid to be labeled is a target nucleic acid (a subject to be detected; e.g., miRNA, SnRNA), and corresponds to a primer in a polymerase reaction. Therefore, a subject to be detected itself is labeled.
  • a template nucleic acid is a "provision" nucleic acid, such as synthetic DNA orthe like, which corresponds to aprobe.
  • ssDNA, dsDNA, or the like can be used. Therefore, the template nucleic acid is not labeled.
  • an extension reaction is terminated when there is no longer a nucleotide sequence of the template nucleic acid for extension, so that no more extension occurs.
  • the nucleic acid to be labeled is immobilized on a solid-phase support, and thus serves as a primer.
  • nucleic acids such as labeled synthetic DNA andthe like, canbe used.
  • the template nucleic acid corresponds to mRNA, and is not labeled.
  • the termination of the extension reaction is not necessarily required.
  • a method for specifically labeling a nucleic acid to be labeled using a DNA synthesis reaction in which the nucleic acid to be labeled serves as a primer of thepresent invention and "amethod for limitingthe number of bases in extension using the primer halt method or the primer run-off method in a DNA synthesis reaction” of the present invention, a novel method for detecting a nucleic acid (particularly effective for small RNA) is derived.
  • the ⁇ method for labeling a nucleic acid, in which the number of bases can be regulated in a sequence specific manner" of the present invention can be carried out using known techniques as described herein. Note that some applications can be achieved by using various combinations . Inoneembodimentofthepresentinvention, detection canbe achievedby investigating the sequence of an elongated portion.
  • a pharmaceutical agent capable of specifically binding to an elongated target nucleic acid may be used.
  • Such a pharmaceutical agent includes, but is not limited to, another nucleic acid having a sequence specifically interacting with the elongated target nucleic acid, antibodies, and the like.
  • a pharmaceutical agent capable of specifically binding to an elongated target nucleic acid does not bind to the non-elongatedtarget nucleic acidor the labelednucleotide.
  • a label attributedtoa labelednucleotide or alabel attributed to the pharmaceutical agent may be detected.
  • detection maybe achievedbased on the length of an elongated target nucleic acid.
  • the present invention can be applied to labeling and detection on a device, such as an array or the like.
  • the term "device” refers to a portion which can constitute a part or the whole of an apparatus .
  • the device comprises a support (preferably, a solid-phase support) and a target material to be carried on the support.
  • a support preferably, a solid-phase support
  • a target material to be carried on the support.
  • Examples of such a device include, but are not limited to, a chip, an array, a microtiter plate, a cell culture plate, a Petri dish, a film, beads, and the like.
  • a nucleic acid is bound to the support. There are roughly two applications of such an array.
  • a template nucleic acid for small RNA (siRNA, miRNA) is immobilized on a glass, a membrane, or the like. On this support, hybridization, labeling, and detection are performed. It is expected that the quantity of small RNA can be comprehensively analyzed. There has been no other known method for comprehensively analyzing small RNA.
  • a nucleic acid having a sequence complementary to mRNA is immobilized on a support. On this support, hybridization, labeling, and detection are performed. Similar to conventional microarrays, the quantity of mRNA can be comprehensively analyzed. Compared to conventional techniques, the reaction system is simple.
  • small RNA may serve as a template.
  • labeling can be performed on both the 5' and 3' ends.
  • One-base projection on the 3' side of a nucleic acid to be labeled (the 5' side of a template) is most common.
  • Thepresent invention isnot limitedtothis.
  • the template is preferably longer by about 10 bases on the 5' side.
  • onebase is addedtothe target.
  • the template extends on the 5' side is that the target can be distinguished from the template based on their lengths even if a label is non-specifically incorporated into the template.
  • the term "support” refers to a material which can fix a substance, such as a biological molecule. Sucha supportmaybemade fromany fixingmaterial which has a capability of binding to a biological molecule as used herein via covalent or noncovalent bond, or which may be induced to have such a capability.
  • Examples of materials used for supports include any material capable of forming a solid surface, such as, without limitation, glass, silica, silicon, ceramics, silicon dioxide, plastics, metals (including alloys) , naturally-occurring and synthetic polymers (e.g., polystyrene, cellulose, chitosan, dextran, and nylon) , and the like.
  • Asupport maybe formedoflayersmade ofaplurality of materials.
  • a support may be made of an inorganic insulating material, such as glass, quartz glass, alumina, sapphire, forsterite, silicon oxide, silicon carbide, silicon nitride, or the like.
  • a support maybe made of an organic material, such as polyethylene, ethylene, polypropylene, polyisobutylene, polyethyleneterephthalate, unsaturated polyester, fluorine-containing resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, acrylic resin, polyacrylonitrile, polystyrene, acetal resin, polycarbonate, polyamide, phenol resin, urea resin, epoxy resin, melamine resin, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, siliconeresin, polyphenylene oxide, polysulfone, and the like.
  • organic material such as polyethylene, ethylene, polypropylene, polyisobutylene, polyethyleneterephthalate, unsaturated polyester, fluorine-containing resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl a
  • nitrocellulose film, nylon film, PVDF film, or the like which are used in blotting, may be used as a material for a support.
  • a material constituting a support is in the solid phase, such as a support is herein particularly referredto as a "solidphase support".
  • a solid phase support maybe herein in the formof aplate, amicrowell plate, a chip, aglass slide, a film, beads, ametal (surface), or the like.
  • a support may not be coated or may be coated.
  • substrate refers to a material (preferably, solid) which is used to construct a chiporarrayaccordingtothepresent invention. Therefore, substrates are included in the concept of plates.
  • a substrate may be made from any solid material which has a capability ofbinding to abiological molecule as usedherein via covalent or noncovalent bonds, or which may be induced to have such a capability.
  • Examples ofmaterials used forplates and substrates include any material capable of forming a solid surface, suchas, withoutlimitation, glass, silica, silicon, ceramics, silicon dioxide, plastics, metals (including alloys) , naturally-occurring and synthetic polymers (e.g., polystyrene, cellulose, chitosan, dextran, and nylon) , and the like.
  • Asupport maybe formedoflayersmadeofaplurality of materials.
  • a support may be made of an inorganic insulating material, such as glass, quartz glass, alumina, sapphire, forsterite, silicon oxide, silicon carbide, silicon nitride, or the like.
  • a support maybe made of an organic material, such as polyethylene, ethylene, polypropylene, polyisobutylene, polyethyleneterephthalate, unsaturated polyester, fluorine-containing resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, acrylic resin, polyacrylonitrile, polystyrene, acetal resin, polycarbonate, polyamide, phenol resin, urea resin, epoxy resin, melamine resin, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrenecopolymer, siliconeresin, polyphenylene oxide, polysulfone, and the like.
  • Amaterial preferable as a substrate varies depending on various parameters such as a measuring device, and can be selected from the above-described various materials as appropriate by those skilled in the art.
  • ⁇ coating in relation to a solidphase support or substrate refers to an act of forming a film of a material on a surface of the solid phase support or substrate, and also refers to a film itself. Coating is performed for various purposes, such as, for example, improvement in the quality of a solid phase support and substrate (e.g., extension of life span, improvement in resistance to hostile environment, such as resistance to acids, etc.), an improvement in affinity to a substance integrated with a solid phase support or substrate, and the like.
  • Various materials may be used for such coating, including, without limitation, biological substances (e.g., DNA, RNA, protein, lipid, etc.), polymers (e.g., poly-L-lysine, andhydrophobic fluorine resin) , silane (APS (e.g., ⁇ -aminopropyl silane, etc.)), metals (e.g., gold, etc. ) , inadditionto the above-described solidphase support and substrate.
  • biological substances e.g., DNA, RNA, protein, lipid, etc.
  • polymers e.g., poly-L-lysine, andhydrophobic fluorine resin
  • silane APS (e.g., ⁇ -aminopropyl silane, etc.)
  • metals e.g., gold, etc.
  • such a coating may be advantageously made of poly-L-lysine, silane (e.g., epoxy silane ormercaptosilane, APS ( ⁇ -aminopropyl silane) , etc. ) , MAS, hydrophobic fluorine resin, a metal (e.g., gold, etc.) .
  • silane e.g., epoxy silane ormercaptosilane, APS ( ⁇ -aminopropyl silane) , etc.
  • MAS ⁇ -aminopropyl silane
  • hydrophobic fluorine resin e.g., gold, etc.
  • metal e.g., gold, etc.
  • the term "array” refers to a substrate (e.g., a chip, etc.) which has a pattern of a composition containing at least one (e.g., 1000 or more, etc.) target substances (e.g., DNA, RNA, etc.), which are arrayed.
  • a substrate e.g., a chip, etc.
  • target substances e.g., DNA, RNA, etc.
  • patterned substrates having a small size e.g., 10X10 mm, etc.
  • microarrays are particularly referredto as microarrays.
  • microarray and “array” are used interchangeably. Therefore, a patterned substrate having a larger size than
  • an array comprises a set of desired nucleic acids fixed to a solid phase surface or a film thereof.
  • An array preferably comprises at least 10 2 nucleic acids of the same or different types, more preferably at least 10 3 , even more preferablyat least 10 4 , and still even more preferably at least 10 5 . These nucleic acids are placed on a surface of up to 125X80 mm, more preferably 10X10 mm.
  • An array includes, but is not limited to, a 96-well microtiter plate, a 384-well microtiter plate, a microtiter plate the size of a glass slide, and the like.
  • a composition to be fixed may contain one or a plurality of types of target substances
  • Such a number of target substance types may be in the range of from one to the number of spots, including, without limitation, about 10, about 100, about 500, and about 1,000.
  • any number of target substances may be provided on a solid phase surface or film, typically including no more than 10 8 biological molecules per substrate, in another embodiment no more than 10 7 biological molecules, no more than 10 6 biological molecules, no more than 10 5 biological molecules, no more than 10 4 biological molecules, no more than 10 3 biologicalmolecules, ornomorethan10 2 biologicalmolecules.
  • a composition containing more than 10 8 biological molecule target substances may be provided on a substrate. In these cases, the size of a substrate is preferably small.
  • the size of a spot of a composition containing target substances may be as small as the size of a single biological molecule (e.g., 1 to 2 nm order) .
  • the minimum area of a substrate may be determined based on the number of biological molecules on a substrate.
  • Acomposition containingtarget substances, which are intended to be introduced into cells are herein typically arrayed on and fixedvia covalent bonds orphysical interaction to a substrate in the form of spots having a size of 0.01 mm to 10 mm.
  • spots of biological molecules may be provided on an array.
  • spot refers to a certain set of compositions containing target substances.
  • spotting refers to an act of preparing a spot of a composition containing a certain target substance on a substrate or plate. Spotting may be performed by any method, for example, pipettingor the like, or alternatively, using an automatic device. These methods are well known in the art.
  • the term "address” refers to a unique position on a substrate, which may be distinguished from other unique positions. Addresses are appropriately- associated with spots. Addresses can have any distinguishable shape such that substances at each address maybe distinguishedfromsubstances at other addresses (e.g., optically) . A shape defining an address maybe, for example, without limitation, a circle, an ellipse, a square, a rectangle, or an irregular shape. Therefore, the term “address” is used to indicate an abstract concept, while the term “spot” is used to indicate a specific concept. Unless it is necessary to distinguish them from each other, the terms “address” and “spot” may be herein used interchangeably.
  • each address particularly depends on the sizeofthesubstrate, thenumberofaddresses onthe substrate, the amount of a composition containing target substances and/or available reagents, the size of microparticles, and the level of resolution required for any method used for the array.
  • the size of each address may be, for example, in the range of from 1-2 nm to several centimeters, though the address may have any size suited to an array.
  • the spatial arrangement and shape which define an address are designed so that the microarray is suited to aparticular application. Addressesmaybe denselyarranged or sparselydistributed, or subgrouped into a desiredpattern appropriate for aparticular type ofmaterial to be analyzed.
  • Microarrays are widely reviewed in, for example, "Genomu Kino Kenkyu Purotokoru [Genomic Function Research
  • data analysis software is important for administration of correspondence between clones and spots, data analysis, and the like.
  • Such software may be attached to various detection systems (e.g., Ermolaeva O. et al. , (1998) Nat. Genet., 20: 19-23) .
  • the format of database includes, for example, GATC (genetic analysis technology consortium) proposed by Affymetrix.
  • detection methods and means can be used as long as they can be used to detect information attributed to a label of a nucleic acid.
  • detection methods and means include, but are not limited to, visual inspection, optical microscopes, confocal microscopes, reading devices using a laser light source, surface plasmon resonance (SPR) imaging, electric signals, chemical or biochemical markers, which may be used singly or in combination.
  • SPR surface plasmon resonance
  • Examples of such a detecting device include, but are not limited to, fluorescence analyzing devices, spectrophotometers, scintillation counters, CCD, luminometers, and the like. Any means capable of detecting a biological molecule may be used.
  • Radioactivity may be detected by using a technique wellknownintheart, suchasaGeigercounter, ascintillation counter, or the like.
  • Fluorescence canbe detectedbymeasuringexcitation wavelength and detection wavelength of polarized fluorescence.
  • Those skilled in the art can select as appropriate depending on the type of the fluorescent label used (e.g., when fluorescein isothiocyanate is used as a fluorescent label, excitation wavelength and detection wavelength are 490 nm and 520 nm, respectively) .
  • kit refers to a unit typically comprising two or more sections which provide portions (e.g., a reagent, an enzyme, a template nucleic acid, a standard, etc.) .
  • portions e.g., a reagent, an enzyme, a template nucleic acid, a standard, etc.
  • Such a kit advantageously comprises instructions which state how to treat the provided portions (e.g., a reagent, an enzyme, a nucleotide, a labeled nucleotide, a nucleotide (and its triphosphoric acid) terminating an extension reaction, a template nucleic acid, a standard, etc.) .
  • kit when a kit isusedas areagent kit, the kittypicallycomprises reagent ingredients, a buffer solution, a salt condensate, an auxiliary means for use, instructions stating the usage, and the like.
  • instructions refers to a description of a usemethod or reactionmethod for a reagent of the present invention for the user. Instructions state a procedure for an enzyme reaction of the present invention. The instructions are prepared in accordance with a format defined by an authority of a country in which the present invention is practiced (e.g., Health, Labor and Welfare Ministry in Japan, Food and Drug Administration (FDA) in the U.S., and the like), explicitly describing that the instructions are approved by the authority.
  • an authority e.g., Health, Labor and Welfare Ministry in Japan, Food and Drug Administration (FDA) in the U.S., and the like
  • the instructions are a so-calledpackage insert andare typically provided inpapermedia.
  • the instructions are not so limited andmaybe provided in the form of a film attached to a bottle, and electronic media (e.g., web sites, electronic mails, and the like provided on the internet) .
  • a kit forproducing a nucleic acidhaving an introducedlabel comprises: A) a template nucleic acid complementary to at least a portion of a target nucleic acid to be labeled, and having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid; B) a nucleic acid synthesizing enzyme; and C) a labeled nucleotide.
  • the kit ofthepresent invention comprises a DNA synthesizingenzyme, a template (control) , a target (primer) , a buffer for a reaction, and the like.
  • the kit may comprise a set of templates for major small RNAs.
  • the kit may comprise an array on which a set of templates or a template is immobilized.
  • the kit may further comprise a means for separating unreacted matter of the labeled nucleotide and an extension product from the resultant mixture.
  • the kit may further comprise a means for detecting the labeled nucleotide.
  • the kit may further comprise a standard referencetarget nucleic acid as a control.
  • the standard nucleic acid control
  • the standard nucleic acid may include a nucleic acid selected from the group consisting of a nucleic acid for identifying the template nucleic acid and a nucleic acid for identifying the target nucleic acid.
  • the kit may further comprise a reagent for reaction of the nucleic acidsynthesizingenzyme.
  • a reagent for reaction of the nucleic acidsynthesizingenzyme examples include, but are not limited to, a buffer solution, a required ion condensate, a salt condensate, a pH adjusting agent, and the like.
  • the kit may further comprise a support.
  • the template nucleic acid is immobilizedonthe support.
  • the support may be, but is not limited to, a glass or a membrane.
  • thetemplatenucleicacidofthekitimmobilizedonthe support may be arranged in an array.
  • Such a support may be called
  • DNA chip or the like A method for producing such an array falls within the scope of the present invention.
  • kits of the present invention it will be understood that the various constitutents of the present invention may be in any form as described in detail in the labeling method and the detecting method of the present invention and the method for producing a nucleic acid having an introduced label of the present invention.
  • the kit for detecting a target nucleic acid comprises A) a template nucleic acidcomplementaryto at least aportion of the target nucleic acid, and having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid B) a nucleic acid synthesizing enzyme; C) a labeled nucleotide; and D) a means for detecting the labeled nucleotide.
  • each constitutent e.g., a template nucleic acid, a nucleic acid synthesizing enzyme, a labeled nucleotide, a detecting means, etc.
  • constitutent e.g., a template nucleic acid, a nucleic acid synthesizing enzyme, a labeled nucleotide, a detecting means, etc.
  • the kit may further comprise ameans for separating unreactedmatter of the labeled nucleotide and an extension product from the resultant mixture.
  • ameans for separating unreactedmatter of the labeled nucleotide and an extension product from the resultant mixture include, but are not limited to, electrophoresis, chromatography, and the like.
  • a method for producing a support having a labeled nucleic acid immobilized thereon comprises the steps of: A) providing a target nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled, when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid; B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex; C) subjectingthenucleicacidtobelabeled-templatenucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides
  • the steps of providing a nucleic acid, generating a complex, an extension reaction, and recovering a support can be achieved by using any techniques described herein elsewhere.
  • any techniques such as chemical synthesis, applications of genetic engineering, extraction from cell components, and the like, can be used.
  • the complex can be generated by placing the above-described two nucleic acids with a space which allows 5 the formation of the complex, and exposing the nucleic acids under conditions which allow the formation of the complex.
  • the extension reaction can be performed by, for example, after the complex is generated, adding a nucleic acid synthesizing enzyme, and exposing a mixture of the complex
  • the support can be recovered by, preferably, separating the support from the other reagents used in the reaction.
  • the support may be optionally washed under
  • Example 1 demonstrated whether or not the labeling technique of the present invention can be applied to RNA and DNA.
  • RNA2 5'-AUC GCC AAU UGG AGU AUU UUG-3' (SEQ ID NO. : 2)
  • GFP5-ER G10+786-812 5'-GGG GGG GGG GGA ACT ATA CAA ACA TGA TGA GCT TTA ATG ATA TTG GCG C-3' (SEQ ID NO.: 10)
  • hybridization buffer solution 150 mM KCl, 10 mM
  • reaction buffer solution 1/10 part of 1OX reaction buffer solution (150 mM KCl, 10 rriM Tris-HCl (pH 7.5), 0.5 mM EDTA), containing Ot- 33 P label dideoxyadenosine triphosphoric acid, cytosine triphosphoric acid, uracil triphosphoric acid, and guanosine triphosphoric acid) .
  • DNA polymerase was added to the mixture for nucleotide extension. Thereafter, the reaction was terminated. The termination was performed by denaturation at 95 0 C for 5 minutes or was spontaneously terminated.
  • a solution (4 ⁇ l) containing small RNA and template DNA (0.05pmol) is mixed with a hybridization buffer solution (15OmMKCl, 1OmM Tris-HCl (pH
  • reaction was terminated by adding formamide/EDTA/BPB (0.05% bromophenol blue (BPB) and 2OmMEDTAwas solubilized into the formamide) or reaction termination/loading staining solution (0.05% (bromophenol blue (BPB), 0.05% xylene cyanol (XC) and 2OmM EDTA was solubilized in the formamide) , and was subjected to denaturing acrylamide electrophoresis. Klenow fragment of
  • Figure 3 (a) shows the results thereof.
  • Figure 3 (a) indicates that the combination of the presence or absence of polymerase and type of synthetic RNA (sRNA) as a target nucleic acid (1 or 2), achieved labeling in a sequence-specific manner.
  • sRNA synthetic RNA
  • the reaction was carried out in a solution with a final volume of a 14.5 ⁇ l containing: 3 ⁇ l of 10 XMbuffer solution (10 X M buffer solution being, 100 mM Tris-HCl (pH 7.5), 500 mM NaCl, 100 mM MgCl 2 , and 10 mM DTT) , 0.5 ⁇ l of primer (0.1 pmol/1) , 0.5 ⁇ l of template (0.1 pmol/1) , and 10.5 ⁇ l of H2O, at 95 °C for 5 minutes, and let it stand for 6 hours atroomtemperature.
  • 10 X M buffer solution being, 100 mM Tris-HCl (pH 7.5), 500 mM NaCl, 100 mM MgCl 2 , and 10 mM DTT
  • signals labeledwith 32 P were located slightly above the location of small RNAs of 21 nucleotides in length, and one nucleotide incorporation was detected on the electrophoresis analysis. Accordingly, the present invention was demonstrated to allow direct labeling of nucleic acid in a sequence-specific manner.
  • Template DNA 1 (mGFP, SEQ ID NOs.: 3 and 4) and small RNA(siRNA 1) were mixed with hybridization buffer solution, anddenaturedat 95 °Cfor5minutes. Then, thiswas incubated at 55-70 °C for 6 hours, or cooled down to room temperature. 4 ⁇ l out of the above mixture were removed, and mixed with dideoxynucleotide, and Klenow enzyme was added thereto and incubated for an hour.
  • FIG. 3 (b) shows an experiment investigating temperature conditions for primer-template complex formation of the present invention. The details are as follows:
  • Radiolabeled oligonucleotides were detected after the separation on a denatured agarose gel. The detection was readily conducted from room temperature to about 75 0 C, and the most intense signal was detected about 64 0 C, and at a temperature outside the above range it was still possible to observe the signal.
  • Figure 3 (c) shows an experiment in which the presence and the absence of radiolabeled ddATP, and the presence and the absence of G+C (dGTP and dTTP) as dNTP were devistgated for optimum conditions in addition to the conditions investigaed in Figure 3 (a) .
  • the detailed description is as follows :
  • reaction was carried out as follows: 1OX hybridizationbuffer solution (0.8 ⁇ l) , primer (0.1 pmol/1;
  • reaction termination/loadingbuffersolution 8.5 ⁇ l of reaction termination/loadingbuffersolution was added. Thereafter, this was let stand at 95°C for 2 minutes to terminate the reaction, and placed on ice, and a portion thereof (e.g.,
  • RNA and the template DNA used.
  • the first nucleotide to be incorporated was adenosine, and thus an intense signal was detectedas aresult.
  • Thefirstnucleotidetobeincorporated in the case of primer 2-template 2 complex was thymine, and thus the primer was not labeled with 32 P labeled dideoxyadenosine.
  • anintense signal appearedat around24 nucleotides inlength, and an additional signal was observed at higher molecular weights.
  • the signal band at the 24 nucleotide length corresponded to a product produced by an extension of 3 nucleotides (addition of deoxy T, deoxy G and deoxy A) to primer 2, and the upper signal band appeared to correspond with a result of incorrect nucleotide incorporation into the primer RNA and the template DNA and the extension. If primingofRNA1 intemplate 1 didnot terminatebydideoxyATP, the reaction continueded in the order of A, T, C, C, G.
  • the present inventors have prepared a reaction mixture comprising deoxyATP, deoxyTTP and deoxyCTP without deoxyGTP.
  • Figure 3 (d) left panel dipicts a diagram showing the effects of experiments with or without polymerase, in the absence of labeled ddATP, and in the presence of labeled dCTP, and dATP and dTTP.
  • the detailed description is as follows: the primer is labeled with 32 P deoxyCTP, and the absence of deoxyGTP should result in termination of the extension in the direction of 5' terminus. However, this reactionresults inapluralityofbandswithhighermolecular weight, showing incorrect incorporation of a nucleotide into the primer RNA and the template DNA.
  • Aportionthereof (4 ⁇ l) was aliquoted and transferred to a fresh reaction tube, and 1OX Klenow buffer solution (1.25 ⁇ l, Klenow fragment (0.5 ⁇ l) , [ ⁇ - 32 P] dCTP (3000 Ci/mmol unless otherwisementioned, this specific activity was used herein; 4 ⁇ l) , dATP, dTTP and H 2 O (2.75 ⁇ l) were added and incubated at 37 0 C for one hour. To thismixture, 5 ⁇ l of reaction termination/loadingbuffer solution was added. This mixture was subjected to isopropanol precipitation, and 10 ⁇ l of reaction termination/loading buffer solution was added to the precipitatedpellet .
  • Figure 3 rightpanel dipicts an experiment confirming the effects of a template DNA wifh an additional single nucleotide or ten nucleotides added thereto. The details thereof are as follows:
  • primer 1 (0.1 pmol/ ⁇ l) , DNAl, a template, (O.lpmol/ ⁇ l) , DNAl-G (O.lpmol/ ⁇ l) or DNAlO-G (0.lpmol/ ⁇ l) were used for the reaction.
  • the reaction was carried out as follows: 1OX hybridization buffer solution (0.8 ⁇ l) , primer (0.1 pmol/1; 2 ⁇ l) , a template (0.1 pmol/1; 2 ⁇ l) and H 2 O (3.2 ⁇ l) were made up to a final volume of 8 ⁇ l, which was then incubated at 95°C for 5 minutes and at 64°C for 30 minutes.
  • a portion thereof (4 ⁇ l) was aliquoted and transferred to a fresh reaction tube, and 1OX Klenow buffer solution (1.25 ⁇ l) , Klenow fragment (0.5 ⁇ l) , [ ⁇ - 32 P] ddATP (3000 Ci/mmol; 4 ⁇ l) and H 2 O (2.75 ⁇ l) were added and incubated at 37 0 C for 1 hour. To this mixture, 8.5 ⁇ l of reaction termination/loading buffer solution was added. A portion thereof (e.g., 10 ⁇ l) was electrophoresed by 15 % denaturing acrylamide gel eletrophoresis (PAGE) to seperate the reactants for analysis.
  • PAGE denaturing acrylamide gel eletrophoresis
  • RNA synthesis primed by the small RNA we were able to label a small RNA by DNA synthesis primed by the small RNA.
  • the reaction was in a sequence-specific manner, and dependent on the existence of labeled dideoxynucleotide and DNA polymerase. Labeled nucleotide was readily detected by the use of denaturing acrylamide gel electrophoresis and autoradiography. DideoxyATP was used to allow the determination of the length of the labeled small RNA.
  • the reaction primedby the small RNA directly terminates by the incorporation of dideoxynucleotide thereinto (herein also called "primer halt” method) .
  • primary halt method
  • theprimerhaltmethod we were able to detect at least 5 x 10 "18 molecule (5 atto mole) of small RNA by over-night exposure. This is significantly higher than conventional methods based on ribonuclease protection assay or Northern blotting.
  • siRNA small interfereing RNA
  • Luciferase gene which becomes silenced after translation, was used to detect the siRNA from a transgenic tobacco plant with the gene. The details are as follows:
  • siRNAis knowntobe foundinorganisms includinganimals and plants in which a transgene is inactivated or silenced by post-transcription-type gene silencing (also called as "RNA silencing") .
  • RNA silencing also called as "RNA silencing" .
  • a tobacco plant (NW7-24-4) in which a luciferase gene was highly expressed, and that (NW7-13-10) in which the luciferase has been silenced as described in Genetics 160: 343-352(2002) was used as a model plant in which a foreign gene has been silenced by RNA silencing.
  • plasmid pT3/T7-luc (Clontech) having the same introduced luciferase gene was used.
  • This plasmid was digested by the restriction enzyme Smal, which digest at one single site thereof, and sujected to ethanol precipitation and the precipitation was used as a template DNA.
  • the plasmid in closed, circular form was made linear byresctrictionenzymeetreatment, andthethermaldenaturing thereof readily dissociated it into a single-stranded form.
  • Total RNA was prepared by means of Trizol reagent
  • RNA was extracted from a wild type tobacco plant (Nicotiana tabacum cv. Sumsun NN) and the afore-mentioned transformed plant. Extraction and preparation of RNA was carried out according to the manufacturer's instructions and manuals.
  • ThetemplateDNA (0.5 pmol) andthepreparedtotalRNA (10 ⁇ g) were mixed with 1OX hybridization buffer solution and distilled water was added to a final volume of 8 ⁇ l. The reaction mixture was thermally denatured at 95°C, and thereafter hybridization was carried out at 64 0 C for 90 minutes.
  • the luc gene is detected from the inactivated/silenced plant as an intense signal at around 21-25 nucleotides in length, whereas none or little signals are found from the wild type plant and the plant intensely expressing the luc gene.
  • miRNA as set forth in SEQ ID NOs: 6-9 were selected as an miRNA, and it was demonstrated whether or not such samples can be detected by primer halt method and primer run-off method.
  • Templated DNAs complementary to a plant miRNA andmurine miRNA have been synthesized. The synthesis was carried out in accordance with the above-mentioned Examples. The DNA contained further T residues at the 5' terminus, thereby allowed labeling by dideoxyATP at the 3 ' terminus .
  • Figure 4 shows the results of the determination of the detection limit for the primer haltmethod, and the detection of an miRNA from an organism by the primer halt method.
  • the left panel shows a series of dilutions of synthetic
  • RNAs similartothose shownin Figure 3 (a) The right-handed two panels show the detection of miRNA contained in the total
  • miRNA171 reaction in which a sequence containingmiR171 as a plant endognenous micro RNA (miRNA) and a single base
  • T in the primer halt method As such, a plant endogenous miRNA can be detected.
  • a method for detecting a tobacco miRNA was carried out as follows :
  • reaction was carried out as follows: 1OX hybridizationbuffer solution (0.8 ⁇ l) , primer (0.1 pmol/1; 2 ⁇ l) , a template (0.1 pmol/1; 2 ⁇ l) andH 2 O to a final volume of 8 ⁇ l, was incubated at 95°C for 5 minutes and at 64°C for 30 minutes.
  • the method of the present invention allows detection of at least the 5 atto mole (5 x 10 "18 ) level.
  • the primer halt method allows us to detect an endogenous miRNA of an organism.
  • mice used were male C57 mice, and RNA isolated from the brain and the heart of these mice was used.
  • RNA isolated by means of Concert RNA extraction reagent was used as an RNA.
  • DNA IG 5 '-GGA ACT ATA CAA ACA TGA TGA GCT TTA ATG ATA TTG GCG CGG CTC AAT CA-3' (SEQ ID NO. : 12) ; negative control of GFP sense DNA
  • reaction was carried out as follows: 1OX hybridizationbuffer solution (0.8 ⁇ l) , primer (0.1 pmol/1; 2 ⁇ l) , a template (0.1 pmol/1; 2 ⁇ l) andH 2 O to a final volume of 8 ⁇ l, which was incubated at 95°C for 5 minutes and at 64°C for 30 minutes. Aportion thereof (4 ⁇ l) was aliquoted and transferred to a fresh reaction tube, and 1OX Klenow buffer solution (1.25 ⁇ l) , Klenow fragment (0.5 ⁇ l) , [ ⁇ - 32 P] ddATP (Amersham, AAOO05, 3000 Ci/mmol; 4 ⁇ l) andH 2 O
  • the present invention provides a novel primer halt method for detecting a small RNA. This is simple, but is very sensitive, and requires little time. Therefore, there are possibilies in which the method of the present invention will become a universal method in lieu of conventional Northern blotting or the like.
  • Synthetic DNA 1 and RNA 1 (1 pmol, respectivly) were denaturedina smallvolume ofhybridizationbuffer solution, then it was maintained at 55-75 0 C or room temperature for hybridization.
  • Klenow buffer solution (1OX solution: 0.5MTris-HCl (pH7.5), 0.IM MgCl2, 1OmM DTT, and 0.5 mg/ml bovine serum albumin were prepared and diluted ten-fold) without any other nucleotides than dideoxyATP was added and the DNA synthesis reaction was carried out.
  • Klenow buffer solution (1OX solution: 0.5MTris-HCl (pH7.5), 0.IM MgCl2, 1OmM DTT, and 0.5 mg/ml bovine serum albumin were prepared and diluted ten-fold) without any other nucleotides than dideoxyATP was added and the DNA synthesis reaction was carried out.
  • RNA2 andRNA2 abase tobe incorpoated following RNA2 is TTP, and thus no incorporation occurred in the case of ddATP only.
  • dCTP and dTTP the DNA synthesis reaction proceeded to A, 4 bases ahead of the terminus, and thus incorporation could be observed.
  • Some non-specific reaction was observed, however, such a non-specific reaction did not affect the detection of the nucleic acid at hand. Non-specific detection can be confirmed by using control indicating the result being dependent on the interaction of the template and the target. Therefore, it was possible to confirm a specific reaction by the use of two types of lengths such as DNAl-G and DNAl-GlO.
  • dCTP was used in lieu of ddATP in the combination of DNA IG-RNAl.
  • DNA IG has a sequence complementary to RNAl plusonebase (G) . Inthis reaction, noextensiontermination occurs by dideoxynucleotide, but when adding C, the template will be exhausted, and thus the reaction by the polymerase was terminated.
  • dCTP was used with the combination of DNA IGlO-RNAl .
  • DNA IGlO has a sequence complementary to RNAl plus 10 bases
  • Protocols exemplified in the above examples are based on a radiolabelled nucleotide based method.
  • the present invention may be conducted using a different labelling method.
  • detection was carriedout using a small RNAlabeledbya fluorescent labeled nucleotide. It is possible to use the present method in related fields such as capillary electrophoresis and the related arts thereto by using a label with such a fluorescent label .
  • the present method can be applied to a sequence detemination method, and further, it is contamplated that a variety of applications using polynucleotides or oligonucleties will be possible as such polynucleotides andoligonucleotides canbedirectlylabeled in a sequence-specific manner.
  • examples with fluorescent labels were demonstrated.
  • 1OX hybridization buffer solution 1.5 M KCl, 0.1 M Tris-HCl (pH 7.5), 5mM EDTA; 0.8 ⁇ l
  • primer 1 0.1 pmol/ ⁇ l
  • template DNA Ia 0.1 pmol/ ⁇ l
  • H 2 O 3.2 ⁇ l
  • reaction solution (10 X Klenow buffer solution 1.25 ⁇ l, Klenow fragment 0.5 ⁇ l, 20 mM Cy5-dCTP 1.25 ⁇ l, H 2 O 4 ⁇ l) was added and incubated at 37 0 C for 60 minutes.
  • reaction termination/loading staining solution 0.05% (bromophenol blue (BPB), 0.05% xylene cyanol (XC) and 2OmM EDTA was solubilized in the formamide) were added and incubated at 95 0 C for 2 minutes, and placed on ice. This was electrophoresed on 15 % PAGE, and scanned with FLA-8000 (Fujifilm) .
  • M-MLV reverse transcriptase enzyme M-MLV reverse transcriptase enzyme RNaseH Minus (TOYOBO code number: RTN-101) is used.
  • RNaseH Minus As a plasmid, pT3/T7-LUC (Clonetech) is used. This plasmid produces a linearised product by Smal digestion. This results in a product of blunt ended product having LUC adjacent to T3. Thereafter, the transcription reactionis carriedout invitro.
  • Thetranscriptionreaction is carried out as follows: 5X reactionbuffer solution 10 ⁇ l; rNTP (10 mM for each) ; T3 polymerase (TOYOBO, code number: SC600111) 1 ⁇ l: and DNA 2 ⁇ l were mixed to form 50 ⁇ l, and proceeded at 37 0 C for 30 minutes. Thereafter, ethanol precipitation was carried out, and dissolved in 10 ⁇ l TE (composition: 1 mmol/L EDTA containing 10 mmol/L Tris buffered solution, pH 9.0) . This is used as a template.
  • 1OX hybridization buffer solution 2 ⁇ l of template nucleic acid (LUC RNA) , 5 ⁇ l of tobacco (wild type plant, LUC high expression plant or LUC silincedplant) total RNA were mixed to in a final volume of 8 ⁇ l, and incubated at 95°C for 5 minutes, and thereafter incubated at 64 0 C for 30 minutes.
  • LOC RNA template nucleic acid
  • Example 8 construction of an array
  • DNA is synthesized to contain a specific sequence as a probe at the 3' terminus, and adjusted the concentration thereof to 200 pmol/ ⁇ l. l ⁇ l of this DNA was removed and immobilized onto a nylon membrane.
  • mRNA (2 ⁇ g) or total RNA (40 ⁇ g) is dissolved in sterilized MiIIiQ water (0.48ml) . This RNA solution is injected into a hybridization bag containing the nylon membrane, and annealed at 64 0 C for 30 minutes, and incubated at 42 0 C for 10 minutes.
  • the membrane is washed once with a primary wash solution (0.2% SDS containing IX SSC (15mM sodium citrate, 150 mM NaCl, pH 7.0), 65°C) , and washed twice with secondary wash solution (0.1X SSC containing 0.2% SDS, 65°C) .
  • fluorescence of Cy5 is detected and determined by the use of a fluorescence scanner (FLA-8000, FUJIFILM) .
  • the present invention is useful in a number of fields including general industry, pharmaceutical industry relating to agriculture and biosciences, as it is useful in a number of cases requiring detection of nucleic acid involving a variety of diagnoses, as the present invention allows simple detection of a nucleic acid.

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Abstract

The present invention provides a method for producing a nucleic acid having an introduced label, comprising the steps of: A) providing a nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled; B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex; C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, inwhich a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and D) recovering the elongated nucleic acid to be labeled from the resultant mixture, after the extension reaction.

Description

DESCRIPTION
NOVELMETHODFORLABELINGNUCLEICACID INASEQUENCE-SPECIFIC MANNER, AND METHOD FOR DETECTING NUCLEIC ACID USING THE SAME
TECHNICAL FIELD
Thepresentinventionrelatestoamethodforlabeling a nucleic acid and a method for producing a labeled nucleic acid, and a method for detecting a nucleic acid using these methods, and a kit and a system using these methods.
BACKGROUND ART
Various labels areusedfordetecting a nucleic acid.
Most labels are attached to molecules interacting specifically with a subject molecule that is being detected, but not the subject molecule itself. Therefore, the procedure is complicated.
In addition to the conventionally known rRNA, tRNA, and mRNA, a new class of RNA has been discovered since the 1990' s. Thenewlydiscoveredclass includes small RNAs, such as siRNA, miRNA, and the like. The important in vivo functions of these RNAs have recently been revealed. Therefore, the development of a technique for detecting such RNAs would lead to further elucidation of their functions . There is a large demand for a technique for simply detecting a nucleic acid, such as various RNAs or the like.
An object of the present invention is to provide a technique capable of simply detecting a nucleic acid (particularly, small RNAs, etc.) . DISCLOSURE OF THE INVENTION
The present inventors unexpectedly found that small RNAs can be labeled and/or detected by utilizing a hybridization technique in a sequence specific manner, and completed the present invention. As a result, the above-described problem was solved.
Small RNAs play an important role in gene regulation including transcription, translation and mRNA stability as well as maintenance of chromosome structure. Further, they contribute to the defense of host cells by degrading invading viralRNAandsilencingselfishtransposons. Thus, the small RNA world is now a groundbreaking field in the research of the animal and plant kingdoms. However, because of their small molecular weight, i.e. short length, and their lower abundance, detection methods for the small RNAs are complicated and inefficient. Here, the present invention provides a method for detecting small RNAs by sequence specific labeling by dideoxy nucleotide using DNA template and DNA polymerase. Small RNA are hybridized with template DNA substantially complementary to the target small RNA and thentheDNA-RNAhybridare incubatedwiththeKlenowfragment of DNA polymerase I and 32P-labeled dideoxy nucleotide or deoxy nucleotide. The small RNAs act as primers for DNA synthesis and the reaction is directly terminated by incorporation of dideoxy nucleotide. Thus, this is called "Primer Halt". The labeled RNAs can be detected after separation by denaturing gel electrophoresis followed by autoradiography. The labeling is sequence specific and fully dependent on the presence of DNA polymerase. Using the primer halt, it is possible to detect atto (10~18) molar levels of synthetic RNA as well as native RNA (e.g., miRNA frommouse and siRNA fromtransgenicplants, etc.) . In order to find the detection limit,the GFP gene, luciferase gene, miR16, miR171, or the like may be used.
Therefore, thepresentinventionprovides the following.
1. Amethod forproducing a nucleic acidhaving an introduced label, comprising the steps of: A) providing a nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acidhaving a nucleotide sequence of at least one nucleotide extending from at least oneendofthenucleicacidtobelabeledwhenthecomplementary- portion of the nucleic acid to be labeled hybridizes with the template nucleic acid;
B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex;
C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and
D) recovering (or separating) the elongatednucleic acid to be labeled from the resultant mixture, after the extension reaction.
2. A method according to item 1, wherein the nucleic acid to be labeled is DNA, RNA, or a combination thereof. 3. A method according to item 1, wherein the nucleic acid to be labeled is RNA.
4. A method according to item 1, wherein the nucleic acid to be labeled is RNA selected from the group consisting of siRNA and miRNA.
5. Amethodaccordingto item 1, whereinthe templatenucleic acidcomprises a sequence complementaryto the entire nucleic acid to be labeled.
6. Amethodaccordingto item 1, whereinthe template nucleic acid has a nucleotide sequence of at least one nucleotide extending from both ends of the nucleic acid to be labeled.
7. Amethodaccordingto item 1, whereinthe template nucleic acid has a nucleotide sequence extending by at least about 10 nucleotides from the at least one end of the nucleic acid to be labeled.
8. A method according to item 1, wherein the extending nucleotide sequence of the template nucleic acid is located on the 5' terminal side of the template nucleic acid.
9. A method according to item 6, wherein the extending nucleotide sequence of the template nucleic acid on the 3' terminal side of the template nucleic acid has a different length than that of the extending nucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
10. A method according to item 1, wherein the extending nucleotide sequence of the template nucleic acid is located on the 5Λ terminal side of the template nucleic acid, and a 5' terminalportion ofthe nucleicacidtobe labeledextends from the 3' end of the template nucleic acid.
11. A method according to item 6, wherein the extending nucleotide sequence of the template nucleic acid on the 3' terminal side of the template nucleic acid is longer by a distinguishable length than that of the extendingnucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
12. A method according to item 11, wherein the distinguishable length is at least 10 nucleotides.
13. A method according to item 1, wherein the nucleic acid synthesizing enzyme is DNA-dependent DNA polymerase or RNA-dependent DNA polymerase.
14. A method according to item 1, wherein the labeled nucleotide includes a nucleotide labeled with a label selected from the group consisting of fluorescence, radioactivity, phosphorescence, biotin, digoxigenin (DIG) , an enzyme, and chemiluminescence.
15. A method according to item 1, wherein the labeled nucleotide includes radioactivity.
16. A method according to item 1, wherein the step of recoveringthe elongatednucleic acidtobe labeledcomprises a denaturing step.
17. Amethodaccordingtoitem 1, furthercomprisingremoving unreacted matter. 18. A method according to item 17, wherein the step of removing unreacted matter is achieved by ethanol precipitation or gel filtration chromatography.
19. A method according to item 17, wherein the step of removingunreactedmattercomprises separatingtheelongated nucleic acid to be labeled.
20. A method according to item 17, wherein the separating step is achieved by electrophoresis or chromatography.
21. A method according to item 1, wherein the step of recoveringthe elongatednucleicacidtobe labeledcomprises detecting the label.
22. A method according to item 21, wherein the detecting step comprises detecting the label directly or indirectly.
23. A method according to item 21, further comprising separating the elongated nucleic acid to be labeled.
24. A method according to item 23, wherein the detecting step is performed in the separating step.
25. A method according to item 24, wherein the separating and detecting steps are achieved by autoradiography.
26. A method according to item 1, further comprising terminating the extension reaction.
27. A method according to item 26, wherein the terminating step is achieved by a primer halt method or a primer run-off method .
28. A method according to item 1, wherein the nucleic acid to be labeled is used as a probe.
29. A method according to item 1, wherein the nucleic acid to be labeled is a nucleic acid to be detected.
30. A method according to item 1, wherein a terminal nucleotide of the template nucleic acid is modified.
31. A method according to item 1, wherein the 3' terminal nucleotide of the template nucleic acid is modified.
32. A method according to item 1, wherein a terminal nucleotide of the template nucleic acid is modified not to incorporate a label nucleotide.
33. A method according to item 30, wherein the modification is selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , • thiolation, and rhodamination.
34. A method according to item 1, wherein the 3' terminal nucleotide of the template nucleic acid is subjected to modification selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination. 35. A method for introducing a label into a nucleic acid, comprising the steps of:
A) providing the nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acidhaving a nucleotide sequence of at least one nucleotide extending from at least oneendofthenucleicacidtobelabeledwhenthecomplementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid;
B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex; and
C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid.
36. Amethod for detecting a target nucleic acid, comprising the steps of:
A) providing the target nucleic acid and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the target nucleic acid, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid;
B) hybridizing the target nucleic acid with the template nucleic acid to produce a target nucleic acid-template nucleic acid complex; C) subjecting the target nucleic acid-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used; and D) detecting when an extension product corresponding to the target nucleic acid is present, the presence of the extension product being an indicator of the target nucleic acid.
37. A method according to item 36, further comprising separating unreacted matter of the labeled nucleotide and the extension product from the resultant mixture, after the extension reaction.
38. Amethodaccordingto item 36, wherein the targetnucleic acid is DNA, RNA, or a combination thereof.
39. Amethodaccordingto item 36, wherein the target nucleic acid is RNA.
40. Amethod according to item 36, wherein the nucleic acid is RNA selected from the group consisting of siRNA andmiRNA.
41. A method according to item 36, wherein the template nucleic acidcomprises a sequence complementaryto the entire target nucleic acid.
42. A method according to item 36, wherein the template nucleic acid has a nucleotide sequence of at least one nucleotide extending from both ends of the target nucleic acid.
43. A method according to item 36, wherein the template nucleic acid has a nucleotide sequence extending by at least about 10 nucleotides from the at least one end of the target nucleic acid.
44. A method according to item 36, wherein the extending nucleotide sequence of the template nucleic acid is located on the 5' terminal side of the template nucleic acid.
45. A method according to item 42, wherein the extending nucleotide sequence of the template nucleic acid on the 3' terminal side of the template nucleic acid has a different length than that of the extending nucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
46. A method according to item 36, wherein the extending nucleotide sequence of the nucleic acid to be labeled is located on the 5' terminal side of the template nucleic acid, and a 5' terminal portion of the nucleic acid to be labeled extends from the 3' end of the template nucleic acid.
47. A method according to item 42, wherein the extending nucleotide sequence of the template nucleic acid on the 3' terminal side of the template nucleic acid is longer by a distinguishable length than that of the extendingnucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
48. A method according to item 47, wherein the distinguishable length is at least 10 nucleotides.
49. A method according to item 36, wherein the nucleic acid synthesizing enzyme is DNA-dependent DNA polymerase or RNA-dependent DNA polymerase.
50. A method according to item 36, wherein the labeled nucleotide includes a nucleotide labeled with a label selected from the group consisting of fluorescence, radioactivity, phosphorescence, biotin, digoxigenin (DIG) , an enzyme, and chemiluminescence.
51. A method according to item 36, wherein the labeled nucleotide includes radioactivity.
52. A method according to item 36, wherein the step of separating the extension product and the target nucleic acid-template nucleic acid complex is achieved by a denaturing step.
53. A method according to item 36, wherein the unreacted matter is separated from the extension product by removing the unreacted matter by ethanol precipitation or gel filtration chromatography.
54. A method according to item 36, wherein the detecting step comprises detecting the label directly or indirectly.
55. A method according to item 36, further comprising recovering the extensionproduct corresponding to the target nucleic acid.
56. A method according to item 37, wherein the separating step is achieved by electrophoresis or chromatography.
57. A method according to item 37, wherein the detecting step is performed in the separating step. 58. A method according to item 57, wherein the separating and detecting steps are achieved by autoradiography.
59. A method according to item 36, further comprising terminating the extension reaction.
60. A method according to item 59, wherein the terminating step is achieved by a primer halt method or a primer run-off method.
61. A method according to item 36, wherein the detecting stepisperformedbasedonasequenceoftheelongatedportion.
62. A method according to item 36, wherein the detecting step is performed using a pharmaceutical agent specifically binding to the elongated target nucleic acid.
63. A method according to item 62, wherein the detecting step is performed by detecting a label attributed to the labeled nucleotide and a label attributed to the pharmaceutical agent.
64. Amethodaccordingtoitem 62, whereinthepharmaceutical agent specifically binding to the elongated target nucleic acid does not bind to the target nucleic acid not elongated or the labeled nucleotide.
65. A method according to item 36, wherein the detecting step is performedbased on the length of the elongated target nucleic acid.
66. A method according to item 36, wherein a terminal nucleotide of the template nucleic acid is modified.
67. A method according to item 36, wherein the 3' terminal nucleotide of the template nucleic acid is modified.
68. A method according to item 36, wherein a terminal nucleotide of the template nucleic acid is modified not to incorporate a label nucleotide.
69. A method according to item 66, wherein the modification is selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
70. A method according to item 36, wherein the 3' terminal nucleotide of the template nucleic acid is subjected to modification selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
71. A kit for producing a nucleic acid having an introduced label, comprising:
A) a template nucleic acid complementary to at least a portion of a target nucleic acid to be labeled, and having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid; and
B) a nucleic acid synthesizing enzyme. 72. A kit according to item 71, further comprising: C) a labeled nucleotide.
73. A kit according to item 72, further comprising: ameans forseparatingunreactedmatterofthelabeled nucleotide and an extension product from the resultant mixture.
74. A kit according to item 72, further comprising: a means for detecting the labeled nucleotide.
75. A kit according to item 71, further comprising: a reference target nucleic acid as a control.
76. A kit according to item 75, wherein the standard nucleic acid includes a nucleic acid selected from the group consisting of a nucleic acid for identifying the template nucleic acid and a nucleic acid for identifying the target nucleic acid.
77. A kit according to item 71, further comprising: a reagent for reaction of the nucleic acid synthesizing enzyme.
78. A kit according to item 72, wherein the labeled nucleotide has a function of terminating the reaction of the nucleic acid synthesizing enzyme.
79. A kit according to item 71, further comprising: a support, wherein the template nucleic acid is immobilized on the support. 80. A kit according to item 79, wherein the support is made of glass or membrane.
81. A kit according to item 79, wherein the template nucleic acid immobilized on the support is arranged in an array.
82. Akit accordingto item 71, wherein aterminal nucleotide of the template nucleic acid is modified.
83. A kit according to item 1, wherein the 3' terminal nucleotide of the template nucleic acid is modified.
84. Akit accordingto item 71, wherein a terminal nucleotide of the template nucleic acid is modified not to incorporate a label nucleotide.
85. A kit according to item 82, wherein the modification is selected from the group consisting of , fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA), thiolation, and rhodamination.
86. A kit according to item 71, wherein the 3' terminal nucleotide of the template nucleic acid is subjected to modification selected from the group consisting of dideoxy chain termination method, fluorescein isothiocyanatation
(FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
87. A method for producing a support having a label-introduced nucleic acid immobilized thereon, comprising the steps of:
A) providing a target nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acidhaving a nucleotide sequence of at least one nucleotide extending from at least oneendofthenucleicacidtobelabeledwhenthecomplementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid; B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex;
C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and
D) recovering the support including the elongated nucleic acid to be labeled from the resultant mixture after the extension reaction.
88. A method according to item 87, wherein the recovering step is achievedby removing reactionmatter fromthe support by washing.
89. A method according to item 87, wherein the recovering step is achieved by removing the label from the support.
90. A kit for detecting a target nucleic acid, comprising:
A) a template nucleic acid complementaryto at least a portion of the target nucleic acid, and having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid;
B) a nucleic acid synthesizing enzyme; C) a labeled nucleotide; and
D) a means for detecting the labeled nucleotide.
91. A kit according to item 90, further comprising: ameans forseparatingunreactedmatterofthe labeled nucleotide and an extension product from the resultant mixture.
92. A kit accordingto item 90, wherein a terminal nucleotide of the template nucleic acid is modified.
93. Amethod for detecting a target nucleic acid on a support having a nucleic acid immobilized thereon, comprising the steps of:
A) providing a template nucleic acid immobilized on the support and a nucleic acid to be labeled, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid;
B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex; C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and
D) after the extension reaction, detecting when the elongatednucleic acidto be labeled is present, thepresence of the elongatednucleic acidtobe labeledbeing an indicator of the target nucleic acid.
94. A method according to item 93, wherein the nucleic acid to be labeled is siRNA.
95. A method according to item 93, wherein the support is an array.
96. Amethod for detecting a target nucleic acid on a support having a nucleic acid immobilized thereon, comprising the steps of:
A) providing a nucleic acid to be labeled, which is immobilized on the support, and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid;
B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex;
C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and
D) after the extension reaction, detecting when the elongatednucleic acidtobe labeled is present, thepresence ofthe elongatednucleic acidtobe labeledbeing an indicator of the target nucleic acid.
97. A method according to item 96, wherein the template nucleic acid is mRNA.
98. A method according to item 96, wherein the support is an array.
Hereinafter, thepresent inventionwillbedescribed by way of preferred embodiments. It will be understood by those skilled in the art that the embodiments of the present invention can appropriately be made or carried out based on the description of the present specification and commonly usedtechniquewell known inthe art. The function andeffect of the present invention can be easily recognized by those skilled in the art.
According to the present invention, a nucleic acid that is being labeled (e.g., DNA, RNA) is hybridized with a template nucleic acid (e.g., template DNA in a primer halt method; a target nucleic acid in a primer array method) , and thereafter, DNA synthesis is conducted where the nucleic acid being labeled is used as a primer. In this case, a labelled chemical compound is used as a nucleotide which is to be newly added in the DNA synthesis. Thus, a method for labeling the target nucleic acid can be provided. The target nucleic acid is either RNA or DNA. Particularly, the present invention is highly useful as a method for labeling short-strandedRNA. The label maybe a radioactive isotope, a fluorescent dye, or the like. Amethodusing a radioactive isotope was demonstrated herein. The labeled nucleic acid can be detected using the labelled chemical compound as an indicator. In the case of a radioactive label, autoradiography or the like may be used. DNA synthesis reactions for labeling can be terminated by a dideoxylation method. This method is called a primer halt method. Template DNA needs to have a sequence portion complementary to a target nucleic acid. When a target nucleic acid is a small RNA, such as miRNA, having a known sequence, the length and sequence of a portion of the template nucleic acid extending before or after the target nucleic acid can be arbitrarily selected. Using this, DNA synthesis using the target nucleic acid as a primer can be limited to a predetermined length (limited DNA synthesis) . This technique is called primer run-off method.
The labeledtargetnucleic acidcanbe detectedafter separation using gel electrophoresis. By using a combinationoflimitedDNAsynthesisandgelelectrophoresis, the length (base pairs) of the target nucleic acid can be known. This technique may be applied to a detecting method using a fluorescent label and a capillary sequencer. The technique can be applied to a method for detecting siRNA andmiRNAirrespective oftheir origin, i.e. plants, animals, and fungi. The technique can be applied to a method for specifically labelingthe sequence of ageneral nucleic acid, but is not limited to short-stranded RNA. For example, an end of ssDNA can be labeled in a sequence specific manner. In situ labeling is possible. Other various applications are possible.
A fluorescent dye can be incorporated into a nucleotide by, for example, but not limited to, using an amino group introducing reagent (e.g., 2- (4-monomethoxytritylamino) ethyl- (2-cyanoethyl) - (N,N-d iisopropyl) -phosphoramidite, etc.), a thiol group introducing ■ reagent
( (S-trityl-6-mercaptohexyl) - (2-cyanoethyl) - (N,N-diisopr opyl) -phosphoramidite, (e.g.,
S-trityl-2-mercaptoethyl) - (2-cyanoethyl) - (N,N-diisoprop yl) -phosphoramidite, etc.), or the like, to directly label a nucleotide; introducing a linker by replacing a phosphate bond at a label site of a fluorescent dye in a nucleic acid with a phosphonate bond having a functional group and using this functional group to bind to a fluorescence agent
(Japanese Laid-Open Publication No. 61-44353); or the like.
The present invention also provides a novel nucleic acid detecting method, which has novelty andutility because it can directly label a nucleic acid in a sequence-specific manner. Inaddition, byselectinganucleotideoratemplate, the length of a label can be regulated, i.e., limited to 1 to several bases. The present invention is also effective as a method for detecting short-stranded RNA, such as siRNA involved in RNA silencing which has recently attracted attention, miRNA which has attracted attention as a part of a gene expression regulating mechanism after transcription.
Compared with conventional techniques, the present invention has, for example, the following advantages and effects:
1) it is easy to manipulate the protocol and the time requiredfordetectionis short (anucleicacidcanbedirectly labeled with a protocol similar to probe synthesis using Northern blotting or the like. After being labeled, the nucleic acidcanbe directlydetectedafter electrophoresis . There is no need for further techniques such as electrophoretic transfer, membrane hybridization, washing, and the like) ;
2) a nucleic acid to be labeled can be directly labeled, unlike Northern blotting or the like;
3) the detection sensitivity is comparable with or higher than conventional techniques which are considered to have high sensitivity. (atto (ICT18) molar level; This is equal to the detection limit of a commercially available kit based on RNase protection, i.e., champion data. Note that since RNase protection uses RNase, it is disadvantageously difficult to eliminate the possibility that the detected RNA is an artifact. Manipulation in the method of the present invention is faster and simpler than conventional techniques.); and
4) siRNA or miRNA cannot be detected unless small RNA fractions are purified. In the method of the present invention, total RNA can be used.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an explanation of the primer haltmethod. (small RNA: a short-stranded RNA which is a target of the detection, template DNA: DNA which is a template for the detection.) . In the Examples, synthetic ssDNA was used, however the present invention is not limited thereto. (DNA pol. : DNA polymerase.) . In the Examples, Klenow fragment was used, but the present invention is not limited thereto. Intheory, a reverse transcriptation enzyme is alsopossible.
(1) short-stranded RNA was hybridized to a template DNA.
(2) a DNA polymerase was added, followed by dideoxy NTPs or dideoxy ATP only after the assay system has come to room temperature. DideoxyNTPs were labeledwithalabelingagent such as 32P or the like.
(3) DNA polymerase is used to label a short-stranded RNA, with the short-stranded RNA hybridized to the DNA, by a DNA synthesis reaction, using a primer. In this regard, dideoxyNTP was incorporated therein and the reaction terminated.
(4) Labeled RNA was denatured to be separated from the DNA. (5) Detection was readily made thereafter, by an autoradiogram after gel electrophoresis .
Figure 2 dipicts sequences of synthetic DNA and RNA used in a model experiment as demonstrated in the Examples. DNA 1 and 2 are part of an ORF in the sense direction of the GFP gene. The RNAhas a sequence of 21 nucleotides in length, complementary to a part of the DNA. The Figure shows the conditions in which hybridization has occurred. During the reaction with RNA as a primer, one base is added to the 3' terminus of the RNA, a dATP is incorporated into the combination of DNAl-RNAl, and a dTTP is incorporated into the combination of DNA2-RNA2. No homology is found between DNAl and RNA2, and DNA2 and RNAl.
Figure 3 dipicts model experiments of the primer halt methodandtheprimer run-offmethod. pol. : Klenow fragment; sRNA (synthetic RNA) : synthetic RNAl or RNA 2.
DNAandRNAare respectivelymixedwith 1 pmol 33P-dideoxy NTP in a Klenow reaction solution, denatured at 95 °C and hybridized by letting the temperature return to room temperature. Klenow enzyme was added thereto, and the DNA synthesis reaction was conducted by using sRNA as a primer. No nucleotides other than dideoxyNTP labeled with 33P were added thereto. Labeled RNA was electrophoresed in a denaturing acrylamide gel, and detected by autoradiogram. The combinations of DNAl-RNAl, DNA2-RNA2 were found to incorporate 33P in a polymerase dependent manner, indicating that the present method can label a short-stranded RNA in a sequence-specific manner.
Figure 4 dipicts the measurement of the detection limit of the primer halt method and detection of miRNA from an organism by the primer halt method. Small RNA was serially dilutedby one tenth to calculate the detection sensitivity.
In the method of the present invention, it was demonstrated that at least a 5 atto mole (5 x 10~18) level can be detected.
The left lanes are as follows:
Detection of a dilution series of synthetic RNA as in (a) : the right-most two lanes show detection of miRNA contained in the total RNA prepared from a plant. Luc: reaction in which a part of the luciferase gene, luc, not encoded by a plant, was used as a template for the negative control.
MiR171: a primer halt method using a sequence complementary to miR171, which is a plant endogenous micro RNA (miRNA) , plus a sequence comprising a single base of T. As such, a plant endogenous miRNA may be detected.
Figure 4B depicts confirmation of miRNA in a mouse by the primer run-off method of the present invention.
Figure 5 dipicts the rationale of the primer halt method.
Figure 6 dipicts the rationale of the primer run-off method. Figure 7 dipicts the rationale of the primer array method.
(Description of Sequence Listing)
SEQ ID NO. : 1: RNAl
SEQ ID NO. : 2: RNA2
SEQ ID NO. : 3: DNAl (m-GFP5-ER-S 725-812)
SEQ ID NO. : 4: DNA2 (m-GFP5-ER-S 572-670)
SEQ ID NO. : 5: LUC (2113-LUC 2603-2702) S SEEQQ I IDD N NOO..: : 66:: Ntab miR171
SEQ ID NO. : 7: Ntab miRl67
SEQ ID NO. : 8: Mmus miRlδl T
SEQ ID NO. : 9: Mmus miRl6 T
SEQ ID NO. : 10 : GFP5-ER G10+786-812 S SEEQQ I IDD N NOO..: : 1111: GFP5-ER G+786-812
SEQ ID NO. : 12 DNA 1-G
SEQ ID NO. : 13 Mmus miR16 for detection of mouse miRNA
SEQ ID NO. : 14 DNA 1-GlO SEQIDNO.: 15: RNA 1-C (amplified product using DNA
1-G (SEQ ID NO. : 12) )
SEQ ID NO. : 16: RNA 1-ClO (amplified product using DNA 1-GlO (SEQ ID NO.: 14))
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, thepresent inventionwillbedescribed optionally by way of illustrative examples with reference to the accompanying drawings. The present invention will be described below. It should be understood throughout the present specification that articles for singular forms include the concept of their plurality unless otherwise mentioned. Also, it should also be understood that terms as used herein have definitions ordinarily used in the art unless otherwise mentioned. Therefore, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the relevant art. Otherwise, the present application (including definitions) takes precedence.
The following embodiments are provided for a better understanding of the present invention and the scope of the present invention should not be limited to the following description. Itwillbeclearlyappreciatedbythose skilled in the art that variations and modifications can be made without departing from the scope of the present invention with reference to the specification.
(Terms)
The terms "polynucleotide", "oligonucleotide", "nucleic acid", and "nucleic acid molecule" as used herein have the samemeaningandrefer to a nucleotide polymerhaving anylength. Examples ofsuchanucleicacidmoleculeinclude, but are not limited to, cDNA, mRNA, and genomic DNA. These terms also include an "oligonucleotide derivative" or a "polynucleotide derivative". An "oligonucleotide derivative" or a "polynucleotide derivative" includes a nucleotide derivative, or refers to an oligonucleotide or a polynucleotide having different linkages between nucleotides fromtypical linkages, whichare interchangeably used. Examples of such an oligonucleotide specifically include 2' -O-methyl-ribonucleotide, an oligonucleotide derivative in which a phosphodiester bond in an oligonucleotide is converted to a phosphorothioate bond, an oligonucleotide derivative in which aphosphodiesterbond in an oligonucleotide is converted to a N3'-P5' phosphoroamidate bond, an oligonucleotide derivative in whichariboseandaphosphodiesterbondinanoligonucleotide are converted to a peptide-nucleic acid bond, an oligonucleotide derivative in which uracil in an oligonucleotide is substituted with C-5 propynyl uracil, an oligonucleotide derivative in which uracil in an oligonucleotide is substituted with C-5 thiazole uracil, an oligonucleotide derivative in which cytosine in an oligonucleotide is substituted with C-5 propynyl cytosine, an oligonucleotide derivative in which cytosine in an oligonucleotide is substituted with phenoxazine-modified cytosine, an oligonucleotide derivative in which ribose in DNA is substituted with 2'-0-propyl ribose, and an oligonucleotide derivative in which ribose in an oligonucleotide is substitutedwith 2'-methoxyethoxy ribose. Unless otherwise indicated, a particular nucleic acid sequence also implicitly encompasses conservatively-modified variants thereof (e.g. degenerate codon substitutions) , complementary sequences, and corresponding sequences (e.g., mouse sequences corresponding to human sequences, etc.) as well as the sequence explicitly indicated.
As used herein, the term "small RNA" refers to RNA having a small size, specifically about 50 nucleotides or less in length, more preferably about 30 nucleotides or less in length. Examples of smallRNAinclude, but arenot limited to, miRNA, siRNA, and the like. Recently, small RNA has attracted attention and is said to play an important role in gene regulation, including transcription, translation, and mRNA stability. As used herein, the term "nucleotide" may be either naturally-occurring or nonnaturally-occurring. The term "nucleotide derivative" or "nucleotide analog" refers to a nucleotide which is different from naturally-occurring nucleotides andhas a function similar to that of the original nucleotide. Such nucleotide derivatives and nucleotide analogs are well known in the art. Examples of such nucleotide derivatives and nucleotide analogs include, but are not limited to, phosphorothioate, phosphoramidate, methylphosphonate, chiral-methylphosphonate, 2-0-methyl ribonucleotide, and peptide-nucleic acid (PNA) .
When used in an extension reaction, a nucleotide can be in the formof triphosphoric acid. Examples ofnucleoside triphosphoric acid include, but are not limited to, deoxyadenosine triphosphoric acid (dATP) , deoxyguanosine triphosphoric acid (dGTP) , deoxycytidine triphosphoric acid (dCTP) , deoxythymidine triphosphoric acid (dTTP) , which are DNA components, deoxyuridine triphosphoric acid (dUTP) , deoxyinosine triphosphoric acid (dITP) , and the like. Examples of a nucleotide for terminating an extension reaction include, but are not limited to, dideoxyadenosine triphosphoric acid (ddATP) , dideoxyguanosine triphosphoric acid (ddGTP) , dideoxycytidine triphosphoric acid (ddCTP) , dideoxythymidine triphosphoric acid (ddTTP) , dideoxyuridine triphosphoric acid (ddUTP) , dideoxyinosine triphosphoric acid (ddITP) , which are used in a dideoxy chain terminator technique, and the like. It will be understood that the terms "nucleotide" and "nucleotide triphosphoric acid" are used herein interchangeably unless otherwise mentioned.
A nucleotide may be labeled herein. Examples of a label include, but are not limited to, any labels using fluorescence, radioactivity, phosphorescence, biotin, DIG, an enzyme, and chemiluminescence.
As used herein, the term "label" refers to a factor which distinguishes a molecule or substance of interest from others (e.g., substances, energy, electromagnetic waves, etc.) . Examples of labeling methods include, but are not limitedto, RI (radioisotope) methods, fluorescencemethods, biotinylationmethods, chemoluminancemethods, andthe like. When the above-described nucleic acid fragments and complementary oligonucleotides are labeled by fluorescence methods, fluorescent substances having different fluorescence emission maximum wavelengths are used for labeling. The difference between each fluorescence emission maximumwavelength may be preferably 10 nm or more. Any fluorescent substance which can bind to a base portion of a nucleic acidmaybe used, preferably including a cyanine dye (e.g., Cy3 andCy5 intheCyDye™series, etc. ) , arhodamine 6G reagent, N-acetoxy-N2-acetyl amino fluorene (AAF) , AAIF (iodine derivative of AAF), and the like. Examples of fluorescent substances having a difference in fluorescence emission maximum wavelength of 10 nm or more include a combination of Cy5 and a rhodamine 6G reagent, a combination ofCy3andfluorescein, acombinationofarhodamine 6Greagent and fluorescein, and the like. In the present invention, such a label can be used to alter a sample of interest so that the sample can be detected by detecting means. Such alteration is known in the art. Those skilled in the art can perform such alteration using a method appropriate for a label and a sample of interest. In one preferable embodiment, a label is a radioactive label. A terminal nucleotide of a template nucleic acidmay be "modified" herein. Preferably, a terminal nucleotide of a template nucleic acid is modified so that other nucleotides
(e.g., a label nucleotide) are not incorporated into the end of the template nucleic acid. The end may be either the
5' end or the 3' end, preferably the 3' end. Examples of such modification include, but are not limited to, dideoxylation, fluorescein isothiocyanation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, rhodamination, and the like. The fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination of the 3' end can terminate an extension reaction of polymerase.
As used herein, the term "denaturation" in relation to a nucleic acid refers to a phenomenon that a native three-dimensional structure is lost without cutting a covalent bond. The separation of a nucleic acid is acceleratedbyincludingadenaturingstep, sothatitbecomes easier to recover an elongated nucleic acid to be labeled.
As used herein, the term "remove unreacted matter" in relation to a nucleic acid synthesis reaction, refers to removal of an unreacted material (e.g., a labeled nucleotide, etc.) . Unreacted matter to be removed advantageously includes, particularly, a labelednucleotide.
The present invention is not limited to this . By removing a labeled nucleotide, detection can be performed using only the label of anelongatedproduct as a clue. Unreactedmatter can be removedby, for example, alcohol precipitation (e.g.,
2-propanol, ethanol, or the like) followed by filtration. Unreacted matter can be removed from an array by washing.
As used herein, the term "separation of a nucleic acid" indicates that a group of certain nucleic acids is separated from a group of nucleic acids having a different property. Such separation can be performed based on a molecular weight, a label, an affinity, or the like as a clue. When separation is performedusing amolecular weight as a clue, the separation can be achievedby electrophoresis. A molecular sieve can be used to achieve separation based on a molecular weight.
The removal of a nucleic acid may be simultaneously performed with detection of a label.
In the present invention, the detection of a label canbeperformeddirectlyorindirectly. Forexample, alabel can be directly detected by using a Geiger counter to measure radioactivity; observing fluorescence with a naked eye or a camera; and the like. A label can be indirectly detected by, for example, binding the label with another labeled material and detecting the other labeled material; using an agent for activating the label (biotin, streptoavidin,
■ etc.); and the like.
As used herein, the term "autoradiography" refers toatechniqueforinvestigatingthedistribution, migration, and metabolism of an in vivo material in a cytochemical or histological manner by using an X-ray photograph film or a dry plate to observe the incorporation of a radioactive material (tracer) . Examples of autoradiography include, but are not limited to, macro-autoradiography (visible autoradiography) , micro-autoradiography (microscopic autoradiography) , ultramicro-autoradiography
(electro-microscopic autoradiography), and the like. One of these can be selected herein as appropriate depending on the purpose.
Various detection methods and means can be used in the method of the present invention as long as information of a biological molecule or information attributed to a material interacting with the biological molecule can be detected.
Asusedherein, thetermXλspecificallyinteractwith" inrelationto abiologicalmolecule (e.g., apolynucleotide, a polypeptide, etc.) indicates that an affinity to the biological molecule is representatively equal to, or higher than, an affinity to other irrelevant polynucleotides or polypeptides (particularly when the biological molecule is a polynucleotide, a polypeptide, or the like, for example, the identity has a homology of less than 30%) . The affinity can be measured by, for example, a hybridization assay, a binding assay, or the like.
As usedherein, the term"target nucleic acid" refers to a nucleic acidto be subjected to a reaction (e.g, labeling or detection) . Therefore, when labeling is intended, a target nucleic acid and a nucleic acid to be labeled may overlap each other.
)
As usedherein, the term "nucleic acid to be labeled" refers to any nucleic acid to be subjected to a labeling method of the present invention. As such a nucleic acid, any arbitrary nucleic acid, may be used. Examples of such a nucleic acid to be labeled include, but are not limited to, DNA, RNA, and PNA which allows an extension reaction using a nucleic acid synthesizing enzyme, and the like. Particularly interesting examples of a nucleic acid to be labeled include small RNAs, such as miRNA, siRNA, and the like. Anucleic acid to be labeled is a targetbeing detected in a primer halt method and a primer run-off method, while it is a probe in a primer array method.
As used herein, the term "template nucleic acid" refers to any nucleic acid which is used as a template when a nucleic acid to be labeled is labeled in the method of the present invention. The template nucleic acid itself is not labeled. A template nucleic acid is a probe in a primer halt method and a primer run-off method, while it is a target inaprimerarraymethod. Atemplatenucleic acidusedherein is typically complementary to at least a portion (or preferably the entirety) of a nucleic acid to be labeled, and having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid. Therefore, typically, a template nucleic acid is longer than a nucleic acid to be labeled. The present invention is not limited to this. A template nucleic acid may be longer in theextensiondirection (mostlytowardthe 5' end) . Examples of a template nucleic acid include, but are not limited to, DNA, RNA, andPNAcapableofbecomingatemplateofanextension reaction due to a nucleic acid synthesizing enzyme, and the like. Adifference in lengthbetween a template nucleic acid and a nucleic acid to be labeled may be preferably about 5 nucleotides or more, about 10 nucleotides or more, or about 15 nucleotides or more. As used herein, the term "distinguishable level" in relation to a difference in length, refers to a length with which a difference can be easily recognized in detection. When electrophoresis is used, a difference is, for example, at least about 5 nucleotides, preferably about 10 nucleotides.
Asusedherein, theterm"complementary", inrelation to a nucleic acid, refers to the base sequence of the nucleic acid whose bases are replaced with corresponding bases in
Watson-Crick base pairing. Typically, A and T (U) , and C and
G, are complementary to each other.
Amino acids maybe referred to herein by either their commonly known three letter symbols or by the one-letter symbols recommended by the IUPAC-IUB Biochemical
Nomenclature Commission. Nucleotides, likewise, may be referred to by their commonly accepted single-letter codes.
The symbols are described below.
Amino acids:
Three-letter One-letter Meaning symbol symbol
Ala A alanine
Cys C cysteine
Asp D aspartic acid
GIu E glutamic acid
Phe F phenylalanine
GIy G glycine
His H histidine
He I isoleucine
Lys K lysine Leu L leucine Met M methionine Asn N asparagine Pro P proline GIn Q glutamine Arg R arginine Ser S serine Thr T threonine VaI V valine Trp W tryptophan Tyr Y tyrosine Asx asparagine or asparagic acid
GIx glutamine or glutamic acid Xaa unknown or other amino acids.
Bases:
Symbol Meaning a adenine g guanine c cytosine t thymine u uracil r guanine or adenine purine y thymine/uracil or cytosine pyrimidine m adenine or cytosine amino group k guanine or thymine/uracil keto group s guanine or cytosine w adenine or thymine/uracil b guanine or cytosine or thymine/uracil d adenine or guanine or thymine/uracil h adenine or cytosine or thymine/uracil v adenine or guanine or cytosine n adenine or guanine or cytosine or thymine/uracil, unknown, or other bases.
The similarity, identity and homology of amino acid sequences andbase sequences are herein compared using BLAST (sequence analyzing tool) with the default parameters.
Asusedherein, thetermΛλatleastoneend" inrelation to a nucleic acid refers to at least one of the 3' and 5' ends of the nucleic acid.
As used herein, the term "hybridize under stringent conditions" refers to conditions commonlyusedandwell known in the art. Such a polynucleotide can be obtained by conducting colony hybridization, plaque hybridization, Southern blot hybridization, or the like using a polynucleotide selected from the polynucleotides of the present invention. Specifically, a filter on which DNA derived from a colony or plaque is immobilized is used to conduct hybridization at 65°C in the presence of 0.7 to 1.0 M NaCl. Thereafter, a 0.1 to 2-fold concentration SSC (saline-sodium citrate) solution (1-fold concentration SSC solution is composed of 150 mM sodium chloride and 15 mM sodium citrate) is used to wash the filter at 65°C. Polynucleotides identified by this method are referred to as "polynucleotides hybridizingunder stringent conditions". Hybridization can be conducted in accordance with a method describedin, for example, Molecular Cloning2nded. , Current Protocols inMolecularBiology, Supplement 1-38, DNA Cloning 1: Core Techniques, A Practical Approach, Second Edition, Oxford University Press (1995), and the like. As used herein, the term "hybridizable" in relation to a nucleic acid or a polynucleotide refers to a nucleic acid or a polynucleotide which can hybridize other nucleic acids or polynucleotides under the above-described hybridization conditions. Specifically, the hybridizable nucleicacidincludes atleastanucleicacidhavingahomology of at least 60% to the base sequence of DNA encoding a polypeptide having an amino acid sequence as set forth in the Sequence Listing, preferably a nucleic acid having a homology of at least 80%, and more preferably a nucleic acid having a homology of at least 95%. The homology of a nucleic acid sequence may be represented by similarity evaluated with a score using, for example, a search programBLAST using an algorithm developed by Altschul et al. , J. MoI. Biol., 215, 403-410(1990)) .
The term "highly stringent conditions" refers to those conditions that are designed to permit hybridization of DNA strands whose sequences are highly complementary, and to exclude hybridization of significantly mismatched DNAs. Hybridization stringency is principally determined by temperature, ionic strength, and the concentration of denaturing agents such as formamide. Examples of "highly stringent conditions" for hybridization and washing are 0.0015 M sodium chloride, 0.0015 M sodium citrate at 65-68°C or 0.015 M sodium chloride, 0.0015 M sodium citrate, and 50% formamide at 420C. See Sambrook, Fritsch & Maniatis, Molecular Cloning: A LaboratoryManual (2nded., Cold Spring Harbor Laboratory, N.Y., 1989); Anderson et al., Nucleic Acid Hybridization: A Practical Approach Ch. 4 (IRL Press Limited) (OxfordExpress) . More stringent conditions (such ashighertemperature, lowerionic strength, higherformamide, or other denaturing agents) may be optionally used. Other agents may be included in the hybridization and washing buffers for the purpose of reducing non-specific and/or background hybridization. Examples are 0.1% bovine serum albumin, 0.1% polyvinylpyrrolidone, 0.1% sodium pyrophosphate, 0.1% sodiumdodecyl sulfate (NaDodSCUor SDS) , Ficoll, Denhardt' s solution, and dextran sulfate, although other suitable agents can also be used. The concentration and types of these additives can be changed without substantially affecting the stringency of the hybridization conditions. Hybridization experiments are ordinarily carried out atpH 6.8-7.4; however, at typical ionic strength conditions, the rate of hybridization is nearly independent of pH. See Anderson et al., Nucleic Acid Hybridization: A Practical Approach Ch. 4 (IRL Press Limited, Oxford UK) .
Agents affecting the stability of the DNA duplex include base composition, length, and degree of base pair mismatch. Hybridization conditions canbe adjustedbythose skilled in the art in order to accommodate these variables and allow DNAs of different sequence relatedness to form hybrids. The melting temperature of a perfectlymatched DNA duplex can be estimated by the following equation:
Tm (0C) = 81.5 + 16.6 (log[Na+]) + 0.41 (% G+C) - 600/N - 0.72 (% formamide)
where N is the length of the duplex formed, [Na+] is the molar concentration of the sodium ion in the hybridization or washing solution, % G+C is the percentage of (guanine+cytosine) bases in the hybrid. For imperfectly matched hybrids, the melting temperature is reduced by approximately 1°C for each 1% mismatch. When RNA, PNA, or the like is used, those skilled in the art can use a relationship expression suitable for the nucleotide.
It will be understood that those skilled in the art can find conditions suitable for labeling or detection using the above-described relationship expression.
Asusedherein, the"percentageofsequence identity, homologyor similarity (amino acid, nucleotide, or the like)" can be determined by comparing two optimally aligned sequences over a window of comparison.
Asusedherein, thetermλλprobe" refers to a substance forusein searching, whichisusedinabiological experiment, suchas invitroand/orinvivoscreeningorthelike, including, but notbeing limitedto, forexample, anucleic acidmolecule having a specific base sequence or a peptide containing a specific amino acid sequence.
Examples of a nucleic acidmolecule as a common probe include one having a nucleic acid sequence having a length of at least 8 contiguous nucleotides, which is homologous or complementary to the nucleic acid sequence of a gene of interest. Such a nucleic acid sequence may be preferably anucleicacidsequencehavingalengthofatleast 9contiguous nucleotides, more preferably a length of at least 10 contiguous nucleotides, and even more preferably a length of at least 11 contiguous nucleotides, a length of at least 12 contiguous nucleotides, a length of at least 13 contiguous nucleotides, a length of at least 14 contiguous nucleotides, a length of at least 15 contiguous nucleotides, a length of at least 20 contiguous nucleotides, a length of at least 25 contiguous nucleotides, a length of at least 30 contiguous nucleotides, a length of at least 40 contiguous nucleotides, or a length of at least 50 contiguous nucleotides . A nucleic acidsequence usedas aprobe includes anucleic acidsequence having at least 70% homologyto the above-described sequence, more preferably at least 80%, and even more preferably at least 90% or at least 95%.
As used herein, the term "primer" refers to a substance required for initiation of a reaction of a macromolecule compoundtobe synthesized, in amacromolecule synthesis enzymatic reaction. In a reaction for synthesizinganucleic acidmolecule, anucleic acidmolecule
(e.g., DNA, RNA, or the like) which is complementary to part of a macromolecule compound to be synthesized may be used.
A nucleic acid molecule which is ordinarily used as a primer includes one that has a nucleic acid sequence having a length of at least 8 contiguous nucleotides, which is complementary to the nucleic acid sequence of a gene of interest. Such a nucleic acid sequence preferably has a length of at least 9 contiguous nucleotides, more preferably a length of at least 10 contiguous nucleotides, even more preferably a length of at least 11 contiguous nucleotides, a length of at least 12 contiguous nucleotides, a length of at least 13 contiguous nucleotides, a length of at least 14 contiguous nucleotides, a length of at least 15 contiguous nucleotides, a length of at least 16 contiguous nucleotides, a length of at least 17 contiguous nucleotides, a length of at least 18 contiguous nucleotides, a length of at least 19 contiguous nucleotides, a length of at least 20 contiguous nucleotides, a length of at least 25 contiguous nucleotides, a length of at least 30 contiguous nucleotides, a length of at least 40 contiguous nucleotides, and a length of at least 50 contiguous nucleotides. A nucleic acid sequence used as a primer includes a nucleic acid sequence having at least 70% homology to the above-described sequence, more preferably at least 80%, even more preferably at least 90%, and most preferably at least 95%. An appropriate sequence as aprimermayvarydepending on the property of the sequence to be synthesized (amplified) . Those skilled in the art can design an appropriate primer depending on the sequence of interest. Such primer design is well known in the art and may be performedmanually or using a computer program (e.g. , LASERGENE, Primer Select, DNAStar) .
As used herein, the term "substitution, addition or deletion" for a polypeptide or a polynucleotide refers to the substitution, addition or deletion of an amino acid or its substitute, or a nucleotide or its substitute, with respect to the original polypeptide or polynucleotide, respectively. This is achieved by techniques well known in the art, including a site-specific mutagenesis technique and the like. A polypeptide or a polynucleotide may have any number (>0) of substitutions, additions, or deletions.
The number can be as large as a variant having such a number of substitutions, additions or deletions which maintains anintendedfunction (e.g., theinformationtransferfunction of hormones and cytokines, etc.) . For example, such a number may be one or several, and preferably within 20% or 10% of the full length, or no more than 100, no more than 50, no more than 25, or the like.
Molecular biological techniques, biochemical techniques, and microorganism techniques as used herein are well known in the art and commonly used, and are described in, forexample, SambrookJ. etal. (1989) , MolecularCloning:
ALaboratoryManual, ColdSpringHarborandits 3rdEd. (2001) ;
Ausubel, F.M. (1987) , CurrentProtocols inMolecularBiology,
Greene Pub. Associates andWiley-Interscience; Ausubel, F.M. (1989) , Short Protocols in Molecular Biology: A Compendium of Methods from Current Protocols in Molecular Biology,
Greene Pub. Associates and Wiley-Interscience; Innis, M.A.
(1990) , PCR Protocols: A Guide to Methods and Applications,
Academic Press; Ausubel, F.M. (1992), Short Protocols in Molecular Biology: A Compendium of Methods from Current Protocols in Molecular Biology, Greene Pub. Associates; Ausubel, F.M. (1995), Short Protocols in Molecular Biology: A Compendium of Methods from Current Protocols in Molecular Biology, Greene Pub. Associates; Innis, M.A. et al. (1995), PCR Strategies, Academic Press; Ausubel, F.M. (1999), Short Protocols in Molecular Biology: A Compendium of Methods from Current Protocols in Molecular Biology, Wiley, and annual updates; Sninsky, J.J. et al. (1999), PCR Applications: Protocols for Functional Genomics, Academic Press; Special issue, Jikken Igaku [Experimental Medicine] "Idenshi Donyu & Hatsugenkaiseki Jikkenho [Experimental Method for Gene Introduction & Expression Analysis] ", Yodo-sha, 1997; and the like. Relevant portions (or possibly the entirety) of each of these publications are herein incorporated by reference.
DNA synthesis techniques and nucleic acid chemistry for preparing artificially synthesized genes are described in, for example, Gait, M.J. (1985), Oligonucleotide Synthesis: APracticalApproach, IRL Press; Gait, M.J. (1990), Oligonucleotide Synthesis: A Practical Approach, IRL Press; Eckstein, F. (1991), Oligonucleotides and Analogues: A Practical Approach, IRL Press; Adams, R.L. et al. (1992), The Biochemistry of the Nucleic Acids, Chapman & Hall; Shabarova, Z. et al. (1994), Advanced Organic Chemistry of Nucleic Acids, Weinheim; Blackburn, G.M. et al. (1996), Nucleic Acids in Chemistry and Biology, Oxford University Press; Hermanson, G.T. (1996), Bioconjugate Techniques, Academic Press; and the like, related portions of which are herein incorporated by reference.
As used herein, the presence of a nucleic acid can be confirmed by using a molecular biological measuring technique, such as a radioactivity method, a fluorescence method, a Northern blotting method, a dot blotting method, a PCR method, or the like.
As used herein, the term "screening" refers to selection of a target, such as an organism, a substance, or the like, a given specific property of interest from a population containing a number of elements using a specific operation/evaluation method. For screening, the detection/labeling technique of the present invention can be used.
As used herein, the term "complex" indicates that two or more molecules interact with one another and are assembledas iftheybehavedas a singlemolecule. Therefore, a hybridized nucleic acid-nucleic acid is a complex.
As used herein, the term "nucleic acid synthesizing enzyme" refers to any enzyme which has the ability to synthesize a nucleic acid. A nucleic acid synthesizing enzyme is also referred to as polymerase. It is a generic term for enzymes which catalize a reaction which polymerizes nucleotides into a polynucleotide. Examples of such a nucleic acidsynthesizingenzyme include, but are not limited to, DNA polymerase (e.g., DNA-dependent DNA polymerase, RNA-dependent DNApolymerase), RNApolymerase, andthe like. Examples of polymerases include, but are not limited to, DNA-dependent DNApolymerase, RNA-dependent DNApolymerase, and the like. For either of the polymerases, either DNA or RNA can be detected. A difference is only which is used as atemplate, DNAorRNA (orboth) (RNA-dependentDNApolymerase also uses DNA as a template; some commercially available DNA-dependent DNApolymerases haveRNA-dependent activity) . Examples of such a polymerase include, but are not limited to, Escherichiacoli-derivedDNApolymerase I, DNApolymerase I Klenow fragment, Taq polymerase, KLA-Taq polymerase, KOD polymerase, Vent polymerase, AMV reverse transcription enzyme, Pfu polymerase, T4 DNA polymerase, and the like.
As used herein, the term "extension reaction" in relation to a nucleic acid refers to any reaction which elongates the nucleic acid by at least one nucleotide. When a polymerase is used for an extension reaction, nucleotides are typically introduced based on a template. Therefore, a specific sequence is elongated for a nucleic acid to be elongated, such as a nucleic acid to be labeled or the like.
An extension reaction comprises (i) ahybridization
(annealing) reaction between a target nucleic acid and its complementary strand, and a nucleic acidprimer and a nucleic acid probe, and (ii) an extension reaction of the primer strandbyanucleicacidsynthesizingenzymeandadegradation reaction of the probe. These reactions (i) and (ii) can be performed in aqueous solution containing an appropriate buffer solution, such as Tris-HCl buffer solution or the like. The hybridization reaction can be performed, representatively, at 55 to 75°C. The present invention is not limited to this. The enzyme reaction can be performed, representatively, at 37°C. The present invention is not limited to this.
A primer extension product can be denaturated by subjecting a solution containing a primer strand extension product obtained by the above-described extension reaction to heating treatment, for example, at 94 to 95°C for 0.5 to 1 minute.
The amplification of a target nucleic acid may be repeatedlyperformedapluralityof times, for example, until a desired amount of the target nucleic acid (nucleic acid to be labeled) is produced. That is, the above-described extensionreactionanddenaturationarerepeatedlyperformed a plurality of times under similar conditions. When the above-describedstep isperformedn times, the initial amount of a target nucleic acid is theoretically amplified by a factor of 2n"x.
The above-describedextension reaction canbe simply and efficiently performed by using a commercially available PCR (polymerase chain reaction) apparatus (e.g., available from Applied Biosystems) .
A nucleic acid can be recovered from a mixture by using any method in the art. Examples of such a recovering method include, but are not limited to, electrophoresis, chromatography, denaturation, alcohol precipitation, affinity purification, antibodies, and the like.
(Description of Preferable Embodiments) Hereinafter, thepresentinventionwillbe described by way of examples. Examples described below are provided only for illustrative purposes. Accordingly, the scope of thepresent invention is not limitedexcept as bythe appended claims.
According to an aspect of the present invention, a method for producing a nucleic acid having an introduced label is provided, comprising the steps of: A) providing the nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid; B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex; C) subjecting the nucleic acid to be labeled-template nucleic acid complex toanextensionreaction, inwhichanucleicacidsynthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and D) recovering the elongated nucleic acid to be labeled from the resultant mixture, after the extension reaction. The present invention is thus the first toprovide a method for freely labeling a target nucleic acid, so that such a labeled nucleic acid can be produced.
Accordingtoanotheraspectofthepresentinvention, amethodforintroducingalabel intoanucleicacidisprovided, comprising the steps of: A) providing the nucleic acid to be labeled and a template nucleic acid, the template nucleic acidbeing complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid; B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid tobe labeled-template nucleic acid complex; and C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid tobe labeledbasedonthe templatenucleic acid. Thepresent invention is thus the first to provide a method for freely labeling a target nucleic acid.
Accordingtoanotheraspectofthepresentinvention, a method for detecting a target nucleic acid is provided, comprising the steps of: A) providing the target nucleic acid and a template nucleic acid, the template nucleic acid beingcomplementarytoatleastaportionofthetargetnucleic acid, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid; B) hybridizing the target nucleic acidwiththetemplatenucleicacidtoproduceatargetnucleic acid-templatenucleicacidcomplex; C) subjectingthetarget nucleic acid-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used; and D) detecting when an extension product corresponding to the target nucleic acid is present, the presence of the extension product being an indicator of the target nucleic acid. The present invention makes it significantly easier to detect a nucleic acid of interest whose sequence may be partially or totally known orpartiallyortotallyunknown, or the like. This isbecause the unknown nucleic acid itself is labeled. Therefore, it will be understood that methods using a labeled probe are conventionally different from one another in terms of the detection sensitivity, easiness, and the like. Preferably, the detecting stepmay further comprise separatingunreacted matter of the labeled nucleotide and the extension product from the resultant mixture, after the extension reaction. This is because the detecting step is made easier.
The step of providing a nucleic acid in the method of thepresent invention canbeperformedusing any technique well known in the art (e.g., chemical synthesis, genetic engineering, extraction from organisms, etc.) .
A complex for use in the method of the present invention can be obtained by using any well known technique in the art. For example, it will be understoodthat a complex can be generated under commonly used conditions for hybridication as described elsewhere herein.
An extension reaction in the method of the present invention can be performed using any method well known in the art. For an extension reaction, a catalyst for the extensionreaction (e.g., anucleicacidsynthesizingenzyme) , a material for providing conditions for the reaction of the catalyst (e.g., a buffer solution, etc.), and a nucleotide (e.g., a label, a non-label, etc.) to be incorporated for extension, can be taken into consideration. In addition, an apparatus for regulating temperature (e.g., a constant temperaturebath, etc.) canbeusedsoas tocontrolconditions for an extension reaction.
The step of recoveing a nucleic acid having an introduced label from the mixture after the extension reaction can be performed using any technique well known in the art. For the recovering step, any technique commonly used for purification or separation of a nucleic acid can be used.
In the method of the present invention, the step of detectingwhenan extensionproduct correspondingto a target nucleic acid is present can be performed by using any method well known in the art. It shouldbe understood that labeling may be diretly or indirectly carried out. In this case, the presence of an extension product is considered to be an indicator for the presence of the above-described target nucleic acid. The extension product cannot be detected unless nucleicacids ofinterest arepresentbefore extension. It is considered that there are a plurality of nucleic acids of interest before extension. Amore detailed detection can be achieved by sequencing the extension product. The extension product can be sequenced by using any technique well known in the art.
In one embodiment ofthepresent invention, a nucleic acid to be labeled used in the present invention may be DNA or RNA, or a combination thereof, andmay be preferably small RNA (e.g., siRNA and miRNA) .
The complementarity between a template nucleic acid and a nucleic acid to be labeled is preferably so sufficient that an extension reaction can proceed. Such a level of complementarity varies depending on the length, the conditions for an extension reaction, or the like. The vicinity of the 3' end of the nucleic acid to be labeled is preferably suitable for an extension reaction. Particularly, 1 to 2 nucleotides of the 3' end of the nucleic acid to be labeled is preferably completely complementary to the template nucleic acid. Alternatively, when the nucleic acid to be labeled is regarded as a reference, the nucleic acidtobe labeledtypicallyhas at least 50%homology to the template nucleic acid, preferably at least 60%, more preferably at least 70%, even more preferably at least 80%, still more preferably at least 90%, and still even more preferably at least 95%. Alternatively, the entirety of the nucleicacidtobelabeledmaybe complementarytothetemplate nucleic acid.
In another embodiment of the present invention, the template nucleic acid used in the present invention may have a nucleotide sequence of at least one nucleotide extending from each of both ends of the nucleic acid to be labeled.
The extending nucleotide sequence preferably has a length of at least about 2 nucleotides, more preferably at least about 3 nucleotides, even more preferably at least about
4 nucleotides, still more preferably at least about 5 nucleotides, still even more preferably at least about 6 nucleotides, still even more preferably at least about 7 nucleotides, still even more preferably at least about 8 nucleotides, still even more preferably at least about 9 nucleotides, and still even more preferably about 10 nucleotides. In another embodiment of the present invention, the template nucleic acid may be modified. The 3' end of the template nucleic acid may be preferably modified. This is because it is possible to prevent an external nucleotide (e.g., a label nucleotide) from being accidentaly incorporated to the 3' end. Therefore, preferably, the terminal nucleotide of the template nucleic acid is modified to prevent the incorporation of a label nucleotide.
In apreferable embodiment of the present invention, such modification is selected from the group consisting of dideoxylation, fluoresceinisothiocyanation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
In such modification, preferably, the 3' end of the template nucleic acid is subjected to modification selected from the group consisting of dideoxylation, fluoresceinisothiocyanation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA), thiolation, and rhodamination.
In another embodiment of the present invention, the template nucleic acid and the nucleic acid to be labeled are preferably designed to have different length expected after the extension reaction. It will be understood that such a design varies depending on a detecting method (e.g., a primer halt method, a primer run-off method, a primer array method, etc.) . In theprimerhaltmethod, dideoxynucleotide or the like is used to stop the extension activity of the polymerase, so that the design can be vaired by controlling a site at which the dideoxynucleotide is incorporated. In another preferable embodiment of the present invention, the nucleotide sequence of at least one nucleotide is added to at least the 5' terminal side of the template nucleic acid. An extension reaction typically occurs at the
3' end. The present invention is not limited to this.
In another embodiment of the present invention, the nucleotide sequence of at least one nucleotide added to the template nucleic acid extending from the portion thereof complementary to the nucleic acid to be labeled may have a different length between the 3' terminal side and the 5' terminal side. This is because it is easier to distinguish the nucleic acid to be labeled from the template nucleic acid.
In another embodiment of the present invention, the nucleotide sequence ofat least onenucleotide ofthetemplate nucleic acid extends from the portion thereof complementary to the nucleic acid to be labeled toward the 5' end thereof, while the template nucleic acid is shorter than the nucleic acid to be labeled in the 3' terminal side of the template nucleic acid, i.e., the 5' terminal portion of the nucleic acid to be labeled extends from the 3' end of the template nucleic acid. In this case, in the primer run-off method, it is particularly guaranteed that the template nucleic acid is shorterthanthenucleicacidtobe labeled. Itispossible todistinguishthenucleicacidtobelabeledfromthetemplate nucleic acid. Also in the primer halt, the shorter template nucleic acid makes it easier to distinguish the nucleic acid to be labeled from the template nucleic acid.
In another embodiment of the present invention, the nucleotide sequence of at least one nucleotide added to the template nucleic acid extending from the portion thereof complementary to the nucleic acid to be labeledmaybe longer in the 3' terminal side than the 5' terminal side. In this case, an extension product can be distinguished from the template nucleic acidwiththe nakedeye whenelectrophoresis is performed.
In another embodiment of the present invention, the nucleotide sequence of at least one nucleotide added to the template nucleic acid extending from the portion thereof complementary to the nucleic acid to be labeledmaybe longer in the 5' terminal side than the 3' terminal side to an extent which makes them distinguishable. The distinguishable lengthvaries depending on the detectionmethod. In the case of visual inspection, the distinguishable length may be 1 to 5 nucleotides, preferably at least about 10 nucleotides.
In another embodiment of the present invention, the nucleic acid synthesizing enzyme may be a DNA-dependent DNA polymerase or an RNA-dependent DNA polymerase. It will be understood that any synthesizing enzyme can be used as long as an extension reaction is achieved.
Examples of a label used in the labeling method of the present invention include, but are not limited to, fluorescence, radioactivity, phosphorescence, biotin, DIG (digoxigenin) , an enzyme, chemiluminescence, and the like. One or a plurality of labels may be used. A plurality of colors can be used in the case of dyes, fluorescence, or the like. Inapreferableembodimentofthepresentinvention, radioactivity is used as a label. Ratioactivity allows an atto molar level of detection. The present invention is not limited to this.
In another embodiment of the present invention, the step of recovering the elongated nucleic acid to be labeled may comprise a denaturing step. By the denaturing step, the elongated nucleic acid to be labeled becomes more distinguishable and easier to recover.
In apreferable embodiment of the present invention, the method may further comprise removing unreacted matter.
The unreacted matter may be noise when a labeled nucleic acid is subsequently used. The unreacted matter may be removed with any available technique, preferably ethanol precipitation (2-propanol precipitation or ethanol precipitation) and filtration. This method is simple.
The step of removing unreacted matter may comprise "separating" the elongated nucleic acid to be labeled. Bythe separating step, the purityof the elongated nucleic acid to be labeled can be increased. The separating step can be achieved by any technique in the art, preferably electrophoresis or chromatography.
In another embodiment of the present invention, the step of recovering the elongated nucleic acid to be labeled may comprise detecting the label. The detecting step may comprise detecting the label directly or indirectly.
In another embodiment of the present invention, the methodmay further comprise separating the elongatednucleic acid to be labeled. Such separation can be achieved by any technique in the art, preferably electrophoresis or chromatography. These technologies are well known in the art and any suitable embodiment may be used in the present invention as described elsewhere herein.
In another embodiment of the present invention, the detecting step may be performed "in the separating step".
By the separation step, detection precision can be improved, sothatdetection andseparation efficiency canbe increased.
In another embodiment, the separating and detecting steps maybe achieved by autoradiography. In this case, the separating and detecting steps can be performed automatically.
In still anotherembodimentofthepresentinvention, the method may further comprise terminating the extension reaction. The terminating step can be achieved by a primer haltmethodoraprimerrun-offmethod. Thepresentinvention is not limited to these. Such a terminating step cannot be conceived by conventional methods. It will be understood that the present invention can provide a highly specific label.
The nucleic acid to be labeled may be a nucleic acid of interest whose sequence may be partially or totally known or unknown. The present invention is not limited to this. The nucleic acid to be labeled may be used as a probe. When the nucleic acid to be labeled is a nucleic acid of interest, the present invention exhibits a significant effect of detecting a nucleic acid of interest even if the sequence thereof is partially or totally unknown.
In an illustrative embodiment of the present invention,, a nucleic acid to be labeled and a template (DNA or RNA) are hybridized with each other. DNA polymerase and freenucleotides areaddedsothataDNAsynthesis (extension) reaction is performed using the nucleic acid to be labeled as a primer (a probe in some cases) . As a result, the nucleic acid can be labeled in a sequence-specific manner. In conventional sequence-specific nucleic acid detecting methods, suchas Southernblotting, Northernblotting, primer extension, RNase protection, microarray, macroarray, and the like, a label is introduced into a probe before hybridization. In contrast, in the method of the present invention, a nucleic acid to be labeled is hybridized with a nucleic acid (probe) , and thereafter, one of them is used as a primer to perform a DNA synthesis reaction, so that a label is introduced into only the hybridized nucleic acid. In the method of the present invention, a label is typically introduced into a nucleic acid which is used as a target nucleic acid. The present invention is not limited to this. Therefore, a label may be introduced into a nucleic acid which is used as a probe. In the method of the present invention, only the hybridized nucleic acid is labeled. In the method of the present invention, a label is introduced into a nucleic acid to be labeled in a sequence-specific manner. This is a significant effect which distinguishes the present invention from conventional techniques in which a probe is labeled, i.e., indirect methods. A template nucleic acid plays the role of a probe of conventional techniques. Therefore, a label is introduced into a nucleic acid to be labeled rather than a template nucleic acid. Note that a nucleic acid to be labeled may be used as a probe. In this case, the present invention includes a technique for introducing a lable into a probe. Such a technique is required when the method of the present invention is applied to a microarray using mRNA. This method utilizes a template-dependent DNA polymerase, for which either DNA or RNA is used as a primer. A preferable template dependent DNA polymerase is a DNA-dependent DNA polymerase (Klenow fragment, DNA polymerase I, etc.) . AnRNA-dependent DNApolymerase (e.g., a reverse transcription enzyme) can also be used.
For both types of polymerases, either DNA or RNA is used as a primer as described above. These polymerases catalyze a reaction which adds bases complementary to a hybridized nucleic acid at the 3' side of the probe. The reactiontypicallyoccursonlyatthe3' "depressionterminus" . The reaction typically does not occur at the 3' "protruding terminus", since a template is not present. When a reaction which adds a base to the 5' end can be catalyzed, the "reverse reaction" can also be performed.
(Terminating a reaction) As used herein, the term "terminate" in relation to anextension reaction indicates that anucleic acid synthesis reaction is terminated. In order to terminate an extension reaction, tworepresentativetechniques (aprimerhaltmethod and a primer run-off method) can be used. With these techniques, the present invention is also characterized in that the number of label nucleotides incorporated into a nucleic acid can be regulated (limited) .
As used herein, the term "primer halt method" refers to a method for terminating a DNA synthesis (extension) reaction after 1 to several bases or several tens of bases are incorporated into a nucleic acid. Specifically, a nucleotide triphophoric acid, which is incorporated into a nucleic acid but does not allow a subsequent extension reaction caused by a nucleic acid synthesizing enzyme, is added with respect to a DNA synthesis (extension) reaction instead of deoxyribonucleotide which is typically used in DNA synthesis (of cource, instead of ribonucleotide) . Such a nucleotide triphophoric acid includes dideoxyribonucleotides (a mixture or one of ddATP, ddCTP, ddTTP, and ddGTP) . In theory, the same principle as that of the dideoxy method used for a DNA sequencing reaction can be used. See Figures 1 and 5 for the principle of the primer halt method.
As used herein, the term "primer run-off method" refers to a method for terminating a DNA synthesis reaction, in which a template nucleic acid (probe) is longer by 1 to several bases than a nucleic acid to be labeled at the 3' side of the nucleic acid to be labeled (the 5' side of the probe), i.e., a portion having a length of 1 to several bases of the template nucleic acid extends from the 3' end of the nucleic acid to be labeled, and the synthesis reaction proceeds over the length of the extending portion of the template nucleic acid. See Figure 6 for the principle of the primer run-off method.
The primer halt methodmaybe used in any cases . The primer run-off method is effective when the nucleic acid to be labeled is miRNA (microRNA) having a known sequence. In the case of siRNA which inactivates a gene, siRNA is a mixture of the inactivated gene and complementary small RNA and thus contains various molecules, and therefore, the primer halt method is preferable.
In the primer halt method, the length of a template is not important, and a template of any length can be used. When siRNA is detected with this method, all four label nucleotides (ddATP, ddCTP, ddTTP, and ddGTP) are preferably contained if possible. This is because siRNA contains various molecules, and therefore, the next base cannot be regulated. The present invention is not limited to this. It will be understood by those skilled in the art that only- one label nucleotide can be used, though the sensitivity- is reduced to 1/4.
When miRNA is detected by the primer run-off method, the 5' portion of the template (the 3' side of the target nucleic acid) preferably has a predetermined length (typically, one base) . Although a portion of the template hybridizing a target is preferably complementary to the target, the sequence of the projecting portion can be arbitrarily selected. Therefore, the template may be designed so that only one of four label nucleotides, i.e., dATP, dCTP, dTTP, and dGTP, is incorporated into the target.
As usedherein, the term"primer arraymethod" refers to a method for detecting and quantifying a number of nucleic acids simultaneously. In the primer array method, a probe nucleic acid is immobilized on a support, and a complex of the immobilized probe and a nucleic acid to be detected is used to perform a DNA synthesis reaction, so that a label nucleotide is incorporated into the nucleic acid which is thus labeled. Byimmobilizinganumberofprobes atdifferent portions of the support, a number of nucleic acids can be simultaneously quantified. The nucleic acid to be detected may be either mRNA or small RNA, or in some cases, DNA. Comparing with conventional microarray techniques, a specific label reaction is performed on the support, and therefore, detection can be more efficiently achieved. To date no method capable of analyzing small RNAs comprehensively has been known. See Figure 7 for the principle of the primer array method.
The primer halt method is representatively suitable for the detection of siRNA. The primer run-off method is representatively suitable for the detection of miRNA and
SnRNA (small nuclear RNA) . The primer array method is suitable for the detection of mRNA.
In the primer halt method, the nucleic acid to be labeled is a target nucleic acid (a subject to be detected; e.g., siRNA) , and corresponds to a primer in a polymerase reaction. Therefore, a subject to be detected itself is labeled. On the other hand, a template nucleic acid is a "provision" nucleic acid, such as synthetic DNA or the like, whichcorresponds toaprobe. Forexample, ssDNA, dsDNA, or the like can be used. Therefore, the template nucleic acid is not labeled. In the primer halt method, an extension reaction may be terminated by using a nucleotide triphosphoric acid which has a function of terminating an extension reaction of dideoxynucleotide or the like.
In the primer run-off method, the nucleic acid to be labeled is a target nucleic acid (a subject to be detected; e.g., miRNA, SnRNA), and corresponds to a primer in a polymerase reaction. Therefore, a subject to be detected itself is labeled. On the other hand, a template nucleic acid is a "provision" nucleic acid, such as synthetic DNA orthe like, which corresponds to aprobe. Forexample, ssDNA, dsDNA, or the like can be used. Therefore, the template nucleic acid is not labeled. In the primer run-off method, an extension reaction is terminated when there is no longer a nucleotide sequence of the template nucleic acid for extension, so that no more extension occurs.
In the primer array method, the nucleic acid to be labeled is immobilized on a solid-phase support, and thus serves as a primer. As the nucleic acid to be labeled serves as a primer, nucleic acids, such as labeled synthetic DNA andthe like, canbe used. In this case, the template nucleic acid corresponds to mRNA, and is not labeled. In the primer array method, the termination of the extension reaction is not necessarily required.
By combining "a method for specifically labeling a nucleic acid to be labeled using a DNA synthesis reaction in which the nucleic acid to be labeled serves as a primer" of thepresent invention and "amethod for limitingthe number of bases in extension using the primer halt method or the primer run-off method in a DNA synthesis reaction" of the present invention, a novel method for detecting a nucleic acid (particularly effective for small RNA) is derived.
Therefore, such a labeling method can be said to have a significant effect which cannot be achieved by conventional techniques. The former itself is a novel nucleic acid labeling/detecting method.
Denaturation, electrophoresis, anddetectionmaybe combined in various manners. The ^method for labeling a nucleic acid, in which the number of bases can be regulated in a sequence specific manner" of the present invention can be carried out using known techniques as described herein. Note that some applications can be achieved by using various combinations . Inoneembodimentofthepresentinvention, detection canbe achievedby investigating the sequence of an elongated portion. In this case, a pharmaceutical agent capable of specifically binding to an elongated target nucleic acid may be used. Such a pharmaceutical agent includes, but is not limited to, another nucleic acid having a sequence specifically interacting with the elongated target nucleic acid, antibodies, and the like. Alternatively, a pharmaceutical agent capable of specifically binding to an elongated target nucleic acid does not bind to the non-elongatedtarget nucleic acidor the labelednucleotide.
In another embodiment of the present invention, a label attributedtoa labelednucleotide or alabel attributed to the pharmaceutical agent may be detected.
In another embodiment of the present invention, detection maybe achievedbased on the length of an elongated target nucleic acid.
(Device)
The present invention can be applied to labeling and detection on a device, such as an array or the like.
As usedherein, the term "device" refers to a portion which can constitute a part or the whole of an apparatus . The device comprises a support (preferably, a solid-phase support) and a target material to be carried on the support. Examples of such a device include, but are not limited to, a chip, an array, a microtiter plate, a cell culture plate, a Petri dish, a film, beads, and the like. In the case of an array, a nucleic acid is bound to the support. There are roughly two applications of such an array.
1) Micro (macro) array for detecting siRNA or miRNA
A template nucleic acid for small RNA (siRNA, miRNA) is immobilized on a glass, a membrane, or the like. On this support, hybridization, labeling, and detection are performed. It is expected that the quantity of small RNA can be comprehensively analyzed. There has been no other known method for comprehensively analyzing small RNA.
2) A nucleic acid having a sequence complementary to mRNA is immobilized on a support. On this support, hybridization, labeling, and detection are performed. Similar to conventional microarrays, the quantity of mRNA can be comprehensively analyzed. Compared to conventional techniques, the reaction system is simple.
In either 1) or 2) , a method, a nucleic acid itself immobilized on a support, and a kit are conceived as embodiments of the present invention.
Conversely, small RNA may serve as a template. Alternatively, labeling can be performed on both the 5' and 3' ends.
One-base projection on the 3' side of a nucleic acid to be labeled (the 5' side of a template) is most common. Thepresent invention isnot limitedtothis. Alternatively, the template is preferably longer by about 10 bases on the 5' side. Thereby, onebaseis addedtothe target. Thereason the template extends on the 5' side is that the target can be distinguished from the template based on their lengths even if a label is non-specifically incorporated into the template.
As used herein, the term "support" refers to a material which can fix a substance, such as a biological molecule. Sucha supportmaybemade fromany fixingmaterial which has a capability of binding to a biological molecule as used herein via covalent or noncovalent bond, or which may be induced to have such a capability.
Examples of materials used for supports include any material capable of forming a solid surface, such as, without limitation, glass, silica, silicon, ceramics, silicon dioxide, plastics, metals (including alloys) , naturally-occurring and synthetic polymers (e.g., polystyrene, cellulose, chitosan, dextran, and nylon) , and the like. Asupportmaybe formedoflayersmade ofaplurality of materials. For example, a support may be made of an inorganic insulating material, such as glass, quartz glass, alumina, sapphire, forsterite, silicon oxide, silicon carbide, silicon nitride, or the like. A support maybe made of an organic material, such as polyethylene, ethylene, polypropylene, polyisobutylene, polyethyleneterephthalate, unsaturated polyester, fluorine-containing resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, acrylic resin, polyacrylonitrile, polystyrene, acetal resin, polycarbonate, polyamide, phenol resin, urea resin, epoxy resin, melamine resin, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, siliconeresin, polyphenylene oxide, polysulfone, and the like. Also in the present invention, nitrocellulose film, nylon film, PVDF film, or the like, which are used in blotting, may be used as a material for a support. When a material constituting a support is in the solid phase, such as a support is herein particularly referredto as a "solidphase support". A solid phase supportmaybe herein in the formof aplate, amicrowell plate, a chip, aglass slide, a film, beads, ametal (surface), or the like. A support may not be coated or may be coated.
As used herein, the term "substrate" refers to a material (preferably, solid) which is used to construct a chiporarrayaccordingtothepresent invention. Therefore, substrates are included in the concept of plates. Such a substrate may be made from any solid material which has a capability ofbinding to abiological molecule as usedherein via covalent or noncovalent bonds, or which may be induced to have such a capability.
Examples ofmaterials used forplates and substrates include any material capable of forming a solid surface, suchas, withoutlimitation, glass, silica, silicon, ceramics, silicon dioxide, plastics, metals (including alloys) , naturally-occurring and synthetic polymers (e.g., polystyrene, cellulose, chitosan, dextran, and nylon) , and the like. Asupportmaybe formedoflayersmadeofaplurality of materials. For example, a support may be made of an inorganic insulating material, such as glass, quartz glass, alumina, sapphire, forsterite, silicon oxide, silicon carbide, silicon nitride, or the like. A support maybe made of an organic material, such as polyethylene, ethylene, polypropylene, polyisobutylene, polyethyleneterephthalate, unsaturated polyester, fluorine-containing resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, acrylic resin, polyacrylonitrile, polystyrene, acetal resin, polycarbonate, polyamide, phenol resin, urea resin, epoxy resin, melamine resin, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrenecopolymer, siliconeresin, polyphenylene oxide, polysulfone, and the like. Amaterial preferable as a substrate varies depending on various parameters such as a measuring device, and can be selected from the above-described various materials as appropriate by those skilled in the art.
As used herein, the term λλcoating" in relation to a solidphase support or substrate refers to an act of forming a film of a material on a surface of the solid phase support or substrate, and also refers to a film itself. Coating is performed for various purposes, such as, for example, improvement in the quality of a solid phase support and substrate (e.g., extension of life span, improvement in resistance to hostile environment, such as resistance to acids, etc.), an improvement in affinity to a substance integrated with a solid phase support or substrate, and the like. Various materials may be used for such coating, including, without limitation, biological substances (e.g., DNA, RNA, protein, lipid, etc.), polymers (e.g., poly-L-lysine, andhydrophobic fluorine resin) , silane (APS (e.g., γ-aminopropyl silane, etc.)), metals (e.g., gold, etc. ) , inadditionto the above-described solidphase support and substrate. The selection of such materials is within the technical scope of those skilled in the art and thus can be performed using techniques well known in the art. In one preferred embodiment, such a coating may be advantageously made of poly-L-lysine, silane (e.g., epoxy silane ormercaptosilane, APS (γ-aminopropyl silane) , etc. ) , MAS, hydrophobic fluorine resin, a metal (e.g., gold, etc.) . As used herein, the terms "chip" or "microchip" are used interchangeably to refer to a micro integrated circuit which has versatile functions and constitutes a portion of a system. Examples of a chip include, but are not limited to, DNA chips, protein chips, and the like.
As usedherein, theterm"array" refers to a substrate (e.g., a chip, etc.) which has a pattern of a composition containing at least one (e.g., 1000 or more, etc.) target substances (e.g., DNA, RNA, etc.), which are arrayed. Among arrays, patterned substrates having a small size (e.g., 10X10 mm, etc.) are particularly referredto as microarrays. The terms "microarray" and "array" are used interchangeably. Therefore, a patterned substrate having a larger size than
-thatwhichisdescribedabovemaybereferredtoasamicroarray.
For example, an array comprises a set of desired nucleic acids fixed to a solid phase surface or a film thereof. An array preferably comprises at least 102 nucleic acids of the same or different types, more preferably at least 103, even more preferablyat least 104, and still even more preferably at least 105. These nucleic acids are placed on a surface of up to 125X80 mm, more preferably 10X10 mm. An array includes, but is not limited to, a 96-well microtiter plate, a 384-well microtiter plate, a microtiter plate the size of a glass slide, and the like. A composition to be fixed may contain one or a plurality of types of target substances
(e.g., a nucleic acid, etc.) . Such a number of target substance types may be in the range of from one to the number of spots, including, without limitation, about 10, about 100, about 500, and about 1,000.
As described above, any number of target substances (e.g., nucleic acids, etc.) may be provided on a solid phase surface or film, typically including no more than 108 biological molecules per substrate, in another embodiment no more than 107 biological molecules, no more than 106 biological molecules, no more than 105 biological molecules, no more than 104 biological molecules, no more than 103 biologicalmolecules, ornomorethan102biologicalmolecules. A composition containing more than 108 biological molecule target substances may be provided on a substrate. In these cases, the size of a substrate is preferably small. Particularly, the size of a spot of a composition containing target substances (e.g., nucleic acids, etc.) maybe as small as the size of a single biological molecule (e.g., 1 to 2 nm order) . In some cases, the minimum area of a substrate may be determined based on the number of biological molecules on a substrate. Acomposition containingtarget substances, which are intended to be introduced into cells, are herein typically arrayed on and fixedvia covalent bonds orphysical interaction to a substrate in the form of spots having a size of 0.01 mm to 10 mm.
"Spots" of biological molecules may be provided on an array. As usedherein, the term "spot" refers to a certain set of compositions containing target substances. As used herein, the term "spotting" refers to an act of preparing a spot of a composition containing a certain target substance on a substrate or plate. Spotting may be performed by any method, for example, pipettingor the like, or alternatively, using an automatic device. These methods are well known in the art.
As usedherein, the term "address" refers to a unique position on a substrate, which may be distinguished from other unique positions. Addresses are appropriately- associated with spots. Addresses can have any distinguishable shape such that substances at each address maybe distinguishedfromsubstances at other addresses (e.g., optically) . A shape defining an address maybe, for example, without limitation, a circle, an ellipse, a square, a rectangle, or an irregular shape. Therefore, the term "address" is used to indicate an abstract concept, while the term "spot" is used to indicate a specific concept. Unless it is necessary to distinguish them from each other, the terms "address" and "spot" may be herein used interchangeably.
The size of each address particularly depends on the sizeofthesubstrate, thenumberofaddresses onthe substrate, the amount of a composition containing target substances and/or available reagents, the size of microparticles, and the level of resolution required for any method used for the array. The size of each address may be, for example, in the range of from 1-2 nm to several centimeters, though the address may have any size suited to an array.
The spatial arrangement and shape which define an address are designed so that the microarray is suited to aparticular application. Addressesmaybe denselyarranged or sparselydistributed, or subgrouped into a desiredpattern appropriate for aparticular type ofmaterial to be analyzed.
Microarrays are widely reviewed in, for example, "Genomu Kino Kenkyu Purotokoru [Genomic Function Research
Protocol] (Jikken Igaku Bessatsu [Special Issue of
Experimental Medicine] , Posuto Genomu Jidai no Jikken Koza
1 [Lecture 1 on Experimentation in Post-genome Era) , "Genomu Ikagaku to korekarano Genomu Iryo [Genome Medical Science and Futuristic Genome Therapy (Jikken Igaku Zokan [Special Issue of Experimental Medicine]), and the like.
Avastamountofdatacanbeobtainedfromamicroarray.
Therefore, data analysis software is important for administration of correspondence between clones and spots, data analysis, and the like. Such software may be attached to various detection systems (e.g., Ermolaeva O. et al. , (1998) Nat. Genet., 20: 19-23) . The format of database includes, for example, GATC (genetic analysis technology consortium) proposed by Affymetrix.
Micromachining for arrays is described in, for example, Campbell, S.A. (1996), "The Science andEngineering of Microelectronic Fabrication", Oxford University Press;
Zaut, P.V. (1996), "MicromicroarrayFabrication: aPractical
Guide to Semiconductor Processing", Semiconductor Services;
Madou, M.J. (1997) , "Fundamentals ofMicrofabrication", CRCl 5 Press; Rai-Choudhury, P. (1997), "Handbook of
Microlithography, Micromachining, & Microfabrication:
Microlithography"; and the like, portions related thereto of which are herein incorporated by reference.
Various detection methods and means can be used as long as they can be used to detect information attributed to a label of a nucleic acid. Examples of such detection methods and means include, but are not limited to, visual inspection, optical microscopes, confocal microscopes, reading devices using a laser light source, surface plasmon resonance (SPR) imaging, electric signals, chemical or biochemical markers, which may be used singly or in combination. Examples of such a detecting device include, but are not limited to, fluorescence analyzing devices, spectrophotometers, scintillation counters, CCD, luminometers, and the like. Any means capable of detecting a biological molecule may be used.
Radioactivity may be detected by using a technique wellknownintheart, suchasaGeigercounter, ascintillation counter, or the like.
Fluorescence canbe detectedbymeasuringexcitation wavelength and detection wavelength of polarized fluorescence. Those skilled in the art can select as appropriate depending on the type of the fluorescent label used (e.g., when fluorescein isothiocyanate is used as a fluorescent label, excitation wavelength and detection wavelength are 490 nm and 520 nm, respectively) .
(Kit) As used herein, the term "kit" refers to a unit typically comprising two or more sections which provide portions (e.g., a reagent, an enzyme, a template nucleic acid, a standard, etc.) . When components are not provided as a mixture and are preferably mixed immediately before use, this form of the kit is preferable. Such a kit advantageously comprises instructions which state how to treat the provided portions (e.g., a reagent, an enzyme, a nucleotide, a labeled nucleotide, a nucleotide (and its triphosphoric acid) terminating an extension reaction, a template nucleic acid, a standard, etc.) . As used herein, when a kit isusedas areagent kit, the kittypicallycomprises reagent ingredients, a buffer solution, a salt condensate, an auxiliary means for use, instructions stating the usage, and the like. As used herein, the term "instructions" refers to a description of a usemethod or reactionmethod for a reagent of the present invention for the user. Instructions state a procedure for an enzyme reaction of the present invention. The instructions are prepared in accordance with a format defined by an authority of a country in which the present invention is practiced (e.g., Health, Labor and Welfare Ministry in Japan, Food and Drug Administration (FDA) in the U.S., and the like), explicitly describing that the instructions are approved by the authority. The instructions are a so-calledpackage insert andare typically provided inpapermedia. The instructions are not so limited andmaybe provided in the form of a film attached to a bottle, and electronic media (e.g., web sites, electronic mails, and the like provided on the internet) .
According to one aspect of the present invention, a kit forproducing a nucleic acidhaving an introducedlabel, comprises: A) a template nucleic acid complementary to at least a portion of a target nucleic acid to be labeled, and having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid; B) a nucleic acid synthesizing enzyme; and C) a labeled nucleotide.
In one embodiment of the present invention, the kit ofthepresent invention comprises a DNA synthesizingenzyme, a template (control) , a target (primer) , a buffer for a reaction, and the like. An actual template for a target nucleicacidmaybepreparedbyyourselformaybecommercially available as an oligo DNA. Alternatively, the kit may comprise a set of templates for major small RNAs. Alternatively, the kit may comprise an array on which a set of templates or a template is immobilized.
In another embodiment of the present invention, the kit may further comprise a means for separating unreacted matter of the labeled nucleotide and an extension product from the resultant mixture.
In another embodiment of the present invention, the kit may further comprise a means for detecting the labeled nucleotide.
In apreferable embodiment of the present invention, the kit may further comprise a standard referencetarget nucleic acid as a control. The standard nucleic acid (control) can be used as an indicator when detection is performed using electrophoresis or the like.
The standard nucleic acidmay include a nucleic acid selected from the group consisting of a nucleic acid for identifying the template nucleic acid and a nucleic acid for identifying the target nucleic acid.
In another embodiment of the present invention, the kitmay further comprise a reagent for reaction of the nucleic acidsynthesizingenzyme. Examples of suchareagent include, but are not limited to, a buffer solution, a required ion condensate, a salt condensate, a pH adjusting agent, and the like.
In apreferable embodiment of the present invention, the kitmay further comprise a support. The template nucleic acidis immobilizedonthe support. Inthis case, the support may be, but is not limited to, a glass or a membrane.
In apreferable embodiment of the present invention, thetemplatenucleicacidofthekitimmobilizedonthe support may be arranged in an array. Such a support may be called
DNA chip or the like. A method for producing such an array falls within the scope of the present invention.
In the kit of the present invention, it will be understood that the various constitutents of the present invention may be in any form as described in detail in the labeling method and the detecting method of the present invention and the method for producing a nucleic acid having an introduced label of the present invention.
In another aspect of the present invention, the kit for detecting a target nucleic acid comprises A) a template nucleic acidcomplementaryto at least aportion of the target nucleic acid, and having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid B) a nucleic acid synthesizing enzyme; C) a labeled nucleotide; and D) a means for detecting the labeled nucleotide.
It will be understood that each constitutent (e.g., a template nucleic acid, a nucleic acid synthesizing enzyme, a labeled nucleotide, a detecting means, etc.) may be in any form as described herein in detail about the method of the present invention.
In one embodiment of the present invention, the kit may further comprise ameans for separating unreactedmatter of the labeled nucleotide and an extension product from the resultant mixture. Examples of such a means include, but are not limited to, electrophoresis, chromatography, and the like.
(Method for producing an array)
Accordingtoanotheraspectofthepresentinvention, a method for producing a support having a labeled nucleic acid immobilized thereon, comprises the steps of: A) providing a target nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled, when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid; B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex; C) subjectingthenucleicacidtobelabeled-templatenucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, sothatatleastone ofthe labelednucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and D) recovering the support including the elongated nucleic acid to be labeled from the resultant mixture after the extension reaction. In the above-described production method, the steps of providing a nucleic acid, generating a complex, an extension reaction, and recovering a support can be achieved by using any techniques described herein elsewhere. Once information about a nucleic acid of interest is provided, any techniques, such as chemical synthesis, applications of genetic engineering, extraction from cell components, and the like, can be used. The complex can be generated by placing the above-described two nucleic acids with a space which allows 5 the formation of the complex, and exposing the nucleic acids under conditions which allow the formation of the complex. The extension reaction can be performed by, for example, after the complex is generated, adding a nucleic acid synthesizing enzyme, and exposing a mixture of the complex
10 and the nucleic acid synthesizing enzyme under conditions which allow the nucleic acid synthesizing enzyme. After the reaction, the support can be recovered by, preferably, separating the support from the other reagents used in the reaction. The support may be optionally washed under
15 conditions whichdo not destroythe immobilizedlabel nucleic acid using, for example, physiological saline, phosphate buffered saline, or the like.
Reference documents, such as scientific 20. publications, patents, patent applications, and the like, as cited herein are herein incorporated by reference as if set forth fully herein.
Although certain preferred embodiments have been
25 described herein, it is not intended that such embodiments be construed as limitations on the scope of the invention except as set forth in the appended claims . Various other modifications and equivalents will be apparent to and can be readily made by those skilled in the art, after reading
30 the description herein, without departing from the scope and spirit of this invention. All patents, publishedpatent applications and publications cited herein are incorporated by reference as if set forth fully herein. (Examples )
Hereinafter, thepresent inventionwillbedescribed by way of examples. The present invention is not limited to these examples. Unless otherwise specified, reagents used herein were commercially available from Wako Pure Chemical Industries, Sigma, Toyobo, New England Biolabs, Amersham, Invtrogen, Funakoshi, Nippon Gene, and the like. Synthetic DNA was supplied by Hokkaido System Science Kabushiki Kaisha. Synthetic RNA was supplied by Japan Bio Services Co. , LTD. It will be understood that those skilled in the art can synthesize such DNA and RNA using techniques well known in the art.
(Example 1)
Example 1 demonstrated whether or not the labeling technique of the present invention can be applied to RNA and DNA.
(Materials and methods)
(Nucleic acid)
Synthetic small RNA complimentary to the GFP gene and sense strand DNA corresponding to the GFP gene are listed in Table 1 below. Figure 2 shows an overview of complementarity of RNAl, RNA2, DNAl, and DNA2. Figure 3 shows the mutual complementarity between each nucleic acid of Table 1 ( (i) to (v) in the right portion) .
Table 1: Representative synthetic DNA andRNA sequences used in the examples
Small RNA RNAl 5'-CUC AUC AUG UUU GUA UAG UUC-3' (SEQ ID NO.: 1)
RNA2 5'-AUC GCC AAU UGG AGU AUU UUG-3' (SEQ ID NO. : 2)
Template DNA
DNAl (m-GFP5-ER-S 725-812)
5'-GAG AGA CCA CAT GGT CCT TCT TGA GTT TGT AAC AGC TGC TGG GAT TAC ACA TGG CAT GGA TGA ACT ATA CAA ACA TGA TGA GCT TTA A-3' (SEQ ID NO. : 3)
DNA2 (m-GFP5-ER-S 572-670)
5'-CAA CTT CAA GAC CCG CCA CAA CAT CGA AGA CGG CGG CGT GCA ACT CGC TGA TCA TTA TCA ACA AAA TAC TCC AAT TGG CGA TGG CCC TGT CCT TTT ACC-3' (SEQ ID NO. : 4)
LUC (2113-LUC 2603-2702)
5'-TTG TAA TAT TAT ATG CAA ATT GAT GAA TGG TAA TTT TGT AAT TGT GGG TCA CTG TAC TAT TTT AAC GAA TAA TAA AAT CAG GTA TAG GTA ACT AAA AAG-3' (SEQ ID NO. : 5)
Ntab miR171
5'-TGA TAT TGG CGC GGC TCA ATC ATG ATA TTG GCG CGG CTC AAT CA-3' (SEQ ID NO. : 6)
Ntab miR167
5'-TTA GAT CAT GCT GGC AGC TTC ATG ATA TTG GCG CGG CTC AAT CA-3' (SEQ ID NO. : 7)
Mmus miRlδl T 5'-TAC TCA CCG ACA GCG TTG AAT GTT TGA TAT TGG CGC GGC TCA ATC A-3' (SEQ ID NO. : 8)
Mmus miR16 T 5'-TCG CCA ATA TTT ACG TGC TGC TAT GAT ATT GGC GCG GCT CAA TCA-3' (SEQ ID NO. : 9)
GFP5-ER G10+786-812 5'-GGG GGG GGG GGA ACT ATA CAA ACA TGA TGA GCT TTA ATG ATA TTG GCG C-3' (SEQ ID NO.: 10)
GFP5-ER G+786-812
5'-GGA ACT ATA CAA ACA TGA TGA GCT TTA ATG ATA TTG GCG CGG CTC AAT CA-3' (SEQ ID NO.: 11)
Total RNA was extracted from adult female mouse and tobaccoplantsbyusingaConcert reagent (mouse; Invitrogen) or a Trizol reagent accordingtomanufacturer' s instructions (tobacco; Invitrogen) .
(Hybridization and label)
A solution (total amount: 4 μl) containing the above-described small RNA and template DNA (0.05 pmol) was mixed with hybridization buffer solution (150 mM KCl, 10 mM
Tris-HCl (pH 7.5), 0.5 mM EDTA) . Hybridization was conducted in the mixture, followed by denaturation at 950C for 5 minutes. Thereafter, themixturewas incubatedat 64°C for 6 hours , except for special cases . Thereafter, 4 μl of the mixture was mixed with 5 units of a DNA polymerase
1 Klenow fragment, followed by incubation at 370C for 1 to
2 hours. The reaction was terminated by adding formamide solution (20 mMEDTAand 0.05% BPB) , followedbydenaturation at 950C for 5 minutes. Thereafter, themixturewas subjected to electrophoresis for 30 minutes using 15% acrylamide gel. 15% denaturing acrylamide gel was prepared by mixing 15% acrylamide (acrylamide.-bisacrylamide = 19:1), 7 M urea (12.75 g) , 11.25 ml of 40% bisacrylamide, 3 ml of 1OXTBE, 3 InIOfH2O, 30 μlofN' ,N' ,N' ,N' -tetramethylethylenediamine (TEMED) , and 300 μl of 10% APS. TBE was prepared by 5-fold dilution of 0.445 mol/1 Tris-boric acid and 10 itimol/1 EDTA) . The size of a gel plate was 10 cm (effective gel length: about 8 cm) .
As another method, 1 pmol of template DNA and small RNA were denatured, followed by hybridization in reaction buffer solution (1/10 part of 1OX reaction buffer solution (150 mM KCl, 10 rriM Tris-HCl (pH 7.5), 0.5 mM EDTA), containing Ot-33P label dideoxyadenosine triphosphoric acid, cytosine triphosphoric acid, uracil triphosphoric acid, and guanosine triphosphoric acid) . Thereafter, DNA polymerase was added to the mixture for nucleotide extension. Thereafter, the reaction was terminated. The termination was performed by denaturation at 950C for 5 minutes or was spontaneously terminated.
As still anothermethod, a solution (4μl) containing small RNA and template DNA (0.05pmol) is mixed with a hybridization buffer solution (15OmMKCl, 1OmM Tris-HCl (pH
7.5), 0.5mM EDTA) for hybridization and denatured at 95°C for five minutes. Then, the solution was incubated at 640C for six hours, and 4 μl thereof was taken and five units of DNA polymerase (TOYOBO) was added thereto, and it was incubated at 370C for 2 hours. The reaction was terminated by adding formamide/EDTA/BPB (0.05% bromophenol blue (BPB) and 2OmMEDTAwas solubilized into the formamide) or reaction termination/loading staining solution (0.05% (bromophenol blue (BPB), 0.05% xylene cyanol (XC) and 2OmM EDTA was solubilized in the formamide) , and was subjected to denaturing acrylamide electrophoresis. Klenow fragment of
DNApolymeraseIwasusedtoallowthedetectionofanextension of a specific length (here, one nucleotide in length) in a sequence-specific manner.
Figure 3 (a) shows the results thereof. Figure 3 (a) indicates that the combination of the presence or absence of polymerase and type of synthetic RNA (sRNA) as a target nucleic acid (1 or 2), achieved labeling in a sequence-specific manner. As can be seen from the figure, significant signalwas observedinthe case ofthe combination with complementarity and the presence of polymerase. The details are as follows:
First, [33P] ddATP, ddTTP, ddGTP, andddCTP (all available from Amersham AH9539, 55.5 TBq/mmol=l, 500 Ci/mmol) were mixed in a single tube to make ddNTP mixture.
The reaction was carried out in a solution with a final volume of a 14.5 μl containing: 3 μl of 10 XMbuffer solution (10 X M buffer solution being, 100 mM Tris-HCl (pH 7.5), 500 mM NaCl, 100 mM MgCl2, and 10 mM DTT) , 0.5 μl of primer (0.1 pmol/1) , 0.5 μl of template (0.1 pmol/1) , and 10.5 μl of H2O, at 95 °C for 5 minutes, and let it stand for 6 hours atroomtemperature. Tothis solution, 0.5 μlof5ϋ/μlKlenow fragment (available from TOYOBO) was added to initiate the reaction, and 3 μl thereof were taken and 3 μl ddNTP mixture were added thereto, and the reaction was carried out at 37 °C for 30 minutes. To this solution, 4 μl of reaction termination/loading buffer solution or STOP solution were added, and the reaction was terminated 2 minutes later at 95 °C, and the reactionmixture was transfered to ice. This was analysed by separating the content thereof by 15% denatured PAGE (using 10 cm gel plate, and the effective gel length was about 8 cm) . The electrophoresis was carried out at 400 V, for 30 minutes for performing λNPre Run", and thereafter, it ran at 400 V, for 30 minutes. Thereafter, the gel was dried and the detection was carried out by an autoradiogram.
As describedabove, signals labeledwith 32P were located slightly above the location of small RNAs of 21 nucleotides in length, and one nucleotide incorporation was detected on the electrophoresis analysis. Accordingly, the present invention was demonstrated to allow direct labeling of nucleic acid in a sequence-specific manner.
(EXAMPLE 2: Improvement of detection conditions) Next, in order to allow more intense signal detection, the present inventors have investigated different hybridization and reaction conditions. In lieu of the 33P label used in Example 1, 32P labeled dideoxy adenosine triphosphate (Amersham Pharmacia) was used. The other conditions were the same as in Example 1.
Further, the steps of hybridization and reaction were carried out separately, and the efficiency of hybridization was measured.
Template DNA 1 (mGFP, SEQ ID NOs.: 3 and 4) and small RNA(siRNA 1) were mixed with hybridization buffer solution, anddenaturedat 95 °Cfor5minutes. Then, thiswas incubated at 55-70 °C for 6 hours, or cooled down to room temperature. 4 μl out of the above mixture were removed, and mixed with dideoxynucleotide, and Klenow enzyme was added thereto and incubated for an hour.
Figure 3 (b) shows an experiment investigating temperature conditions for primer-template complex formation of the present invention. The details are as follows:
1OX hybridization buffer solution (8 μl) , primer (0.1 pmol/1; 40 μl) , template (0.1 pmol/1; 20 μl) and H2O (12 μl) were added to make the total volume of 80 μl, and this was divided into ten aliquots, and these aliquots were incubated at 95 0C for 5 minutes, and at 55-75 0C or at room temperature for 6 hours. 4μl aliquots were removed from each tube and tranferred to a fresh reaction tube, and 1OX Klenow buffer solution (1.25 μl) , Klenow fragment (0.5 μl), [α-32P] ddATP (3000 Ci/mmol=110
TBq/mmol, Amersham, PB10233, unless otherwise stated, this specific activity was used herein; 4 μl) and H2O (2.75 μl) were addedandincubatedat 37 0C for 1hour. To thismixture, 8.5 μl of reaction termination/loading buffer solution was added. Thereafter, this was let stand at 95 °C for 2 minutes to terminate the reaction, and placed on ice, and a portion thereof (e.g., 10 μl) was electrophoresed by acrylamide gel eletrophoresis (PAGE) toseperatethereactants foranalysis .
Radiolabeled oligonucleotides were detected after the separation on a denatured agarose gel. The detection was readily conducted from room temperature to about 75 0C, and the most intense signal was detected about 64 0C, and at a temperature outside the above range it was still possible to observe the signal.
Accordingly, the thermal denature and slow cooling were sufficient for hybridization, and the longer the incubation at about 64 °C was carried out, the more efficient was the hybridization. Figure 3 (c) shows an experiment in which the presence and the absence of radiolabeled ddATP, and the presence and the absence of G+C (dGTP and dTTP) as dNTP were investitgated for optimum conditions in addition to the conditions investigaed in Figure 3 (a) . The detailed description is as follows :
The reaction was carried out as follows: 1OX hybridizationbuffer solution (0.8 μl) , primer (0.1 pmol/1;
2 μl) , a template (0.1 pmol/1; 2 μl) andH2O in a final volume of 8 μl, and was incubated at 95 0C for 5 minutes and at
64°C for 30 minutes. Aportion thereof (4 μl) was aliquoted and transferred to a fresh reaction tube, and 1OX Klenow buffer solution (1.25 μl) , Klenow fragment (0.5 μl) ,
[(X-32P] ddATP (3000 Ci/mmol unless otherwise mentioned, this specificactivitywasusedherein; 4 μl) andH2O (2.75 μl) were added and incubated at 370C for 1 hour. For Lane 7 only,
5 mM dTTP (1 μl) , 5 mM dCTP (1 μl) and H2O (0.75 μl) were applied. To this mixture, 8.5 μl of reaction termination/loadingbuffersolutionwas added. Thereafter, this was let stand at 95°C for 2 minutes to terminate the reaction, and placed on ice, and a portion thereof (e.g.,
10 μl) was electrophoresed by 15% denaturing acrylamide gel eletrophoresis (PAGE) toseperatethereactants foranalysis. The combination of primer-template and ddNTP and the like actually used are shown in Figure 3 (c) .
It was demonstrated that this reaction is closely dependent on thepolymerase used, the dideoxyadenosine used, the primer used, and the level of homology between the small
RNA and the template DNA used. After the priming of primer 1-template 1 complex, the first nucleotide to be incorporated was adenosine, and thus an intense signal was detectedas aresult. Thefirstnucleotidetobeincorporated in the case of primer 2-template 2 complex was thymine, and thus the primer was not labeled with 32P labeled dideoxyadenosine. However, ifadeoxyTTPandGTPwereadded, anintense signal appearedat around24 nucleotides inlength, and an additional signal was observed at higher molecular weights. The signal band at the 24 nucleotide length corresponded to a product produced by an extension of 3 nucleotides (addition of deoxy T, deoxy G and deoxy A) to primer 2, and the upper signal band appeared to correspond with a result of incorrect nucleotide incorporation into the primer RNA and the template DNA and the extension. If primingofRNA1 intemplate 1 didnot terminatebydideoxyATP, the reaction continuted in the order of A, T, C, C, G.
Next, the present inventors have prepared a reaction mixture comprising deoxyATP, deoxyTTP and deoxyCTP without deoxyGTP.
Figure 3 (d) left panel dipicts a diagram showing the effects of experiments with or without polymerase, in the absence of labeled ddATP, and in the presence of labeled dCTP, and dATP and dTTP. The detailed description is as follows: the primer is labeled with 32P deoxyCTP, and the absence of deoxyGTP should result in termination of the extension in the direction of 5' terminus. However, this reactionresults inapluralityofbandswithhighermolecular weight, showing incorrect incorporation of a nucleotide into the primer RNA and the template DNA.
Detailed experimental procedures of Figure 3 (d) are as follows: The reaction was carried out as follows: 1OX hybridizationbuffer solution (0.8 μl) , primer (0.1 pmol/1; 2 μl) , a template (0.1 pmol/1; 2 μl) andH2O in a final volume of 8 μl, and this was incubated at 95°C for 5 minutes and at 640Cfor30minutes. Aportionthereof (4 μl) was aliquoted and transferred to a fresh reaction tube, and 1OX Klenow buffer solution (1.25 μl, Klenow fragment (0.5 μl) , [α-32P] dCTP (3000 Ci/mmol unless otherwisementioned, this specific activity was used herein; 4 μl) , dATP, dTTP and H2O (2.75 μl) were added and incubated at 370C for one hour. To thismixture, 5 μl of reaction termination/loadingbuffer solution was added. This mixture was subjected to isopropanol precipitation, and 10 μl of reaction termination/loading buffer solution was added to the precipitatedpellet . Thereafter, this was let standat 95°C for 5 minutes to promote the reaction, and placed on ice. A portion thereof (e.g., 10 μl) was electrophoresed by 15 % denaturing acrylamide gel eletrophoresis (PAGE) to seperate the reactants for analysis. Lane 1 shows the result in the presence of Klenow fragment, and Lane 2 shows the result in the absence of Klenow fragment but in the presence of H2O.
Figure 3 (d) rightpanel dipicts an experiment confirming the effects of a template DNA wifh an additional single nucleotide or ten nucleotides added thereto. The details thereof are as follows:
First, primer 1 (0.1 pmol/μl) , DNAl, a template, (O.lpmol/μl) , DNAl-G (O.lpmol/μl) or DNAlO-G (0.lpmol/μl) were used for the reaction. The reaction was carried out as follows: 1OX hybridization buffer solution (0.8 μl) , primer (0.1 pmol/1; 2 μl) , a template (0.1 pmol/1; 2 μl) and H2O (3.2 μl) were made up to a final volume of 8 μl, which was then incubated at 95°C for 5 minutes and at 64°C for 30 minutes. A portion thereof (4 μl) was aliquoted and transferred to a fresh reaction tube, and 1OX Klenow buffer solution (1.25 μl) , Klenow fragment (0.5 μl) , [α-32P] ddATP (3000 Ci/mmol; 4 μl) and H2O (2.75 μl) were added and incubated at 370C for 1 hour. To this mixture, 8.5 μl of reaction termination/loading buffer solution was added. A portion thereof (e.g., 10 μl) was electrophoresed by 15 % denaturing acrylamide gel eletrophoresis (PAGE) to seperate the reactants for analysis.
Accordingly, we were able to label a small RNA by DNA synthesis primed by the small RNA. The reaction was in a sequence-specific manner, and dependent on the existence of labeled dideoxynucleotide and DNA polymerase. Labeled nucleotide was readily detected by the use of denaturing acrylamide gel electrophoresis and autoradiography. DideoxyATP was used to allow the determination of the length of the labeled small RNA.
The reaction primedby the small RNA directly terminates by the incorporation of dideoxynucleotide thereinto (herein also called "primer halt" method) . In order to determine the detectionlimitoftheprimerhaltmethod, ten-foldserial diluted products of the synthesized small RNA were prepared andlabeledasdescribedabove. Inordertoreducebackground dideoxyATPwhichwas not incorporatedthereinto, isopropanol precipitation was carriedout, andthereafter, was subjected to gel electrophoresis. Bytheuse oftheprimerhaltmethod, we were able to detect at least 5 x 10"18 molecule (5 atto mole) of small RNA by over-night exposure. This is significantly higher than conventional methods based on ribonuclease protection assay or Northern blotting.
(Example 3: Verification with siRNA)
In order to further verify the possibility of the primer haltmethod, siRNA (small interfereing RNA) was usedto carry out the experiments similar to those in the above-described examples .
Luciferase gene, which becomes silenced after translation, was used to detect the siRNA from a transgenic tobacco plant with the gene. The details are as follows:
siRNAis knowntobe foundinorganisms (includinganimals and plants) in which a transgene is inactivated or silenced by post-transcription-type gene silencing (also called as "RNA silencing") . A tobacco plant (NW7-24-4) in which a luciferase gene was highly expressed, and that (NW7-13-10) in which the luciferase has been silenced as described in Genetics 160: 343-352(2002) was used as a model plant in which a foreign gene has been silenced by RNA silencing. As a template DNA, plasmid pT3/T7-luc (Clontech) having the same introduced luciferase gene was used. This plasmid was digested by the restriction enzyme Smal, which digest at one single site thereof, and sujected to ethanol precipitation and the precipitation was used as a template DNA. The plasmid in closed, circular form was made linear byresctrictionenzymeetreatment, andthethermaldenaturing thereof readily dissociated it into a single-stranded form.
Total RNA was prepared by means of Trizol reagent
(Invitrogen) from a wild type tobacco plant (Nicotiana tabacum cv. Sumsun NN) and the afore-mentioned transformed plant. Extraction and preparation of RNA was carried out according to the manufacturer's instructions and manuals. ThetemplateDNA (0.5 pmol) andthepreparedtotalRNA (10 μg) were mixed with 1OX hybridization buffer solution and distilled water was added to a final volume of 8 μl. The reaction mixture was thermally denatured at 95°C, and thereafter hybridization was carried out at 640C for 90 minutes. 4 μl thereofis aliquotedtherefrom, and1OXKlenow buffer solution (1.25 μl) , Klenow fragment (5 units/μl, 0.5 μl), [α-32P] ddATP (4 μl) and distilled water (2.75 μl) were added thereto, and the reaction mixture was incubated at 37 0C, for 1 hour. This reactant is precipitated with isopropanol, and 10 μl of reaction termination/loading buffer solution is added to the precipitated pellet. This was subjected to a 15 % denaturing acrylamide gel electrophoresis to separate the reactants for analysis.
The luc gene is detected from the inactivated/silenced plant as an intense signal at around 21-25 nucleotides in length, whereas none or little signals are found from the wild type plant and the plant intensely expressing the luc gene.
(Example 4 : Verification with miRNA)
Further, similar experiments were carried out in the cases of miRNA. In the present Example, miRNA as set forth in SEQ ID NOs: 6-9 were selected as an miRNA, and it was demonstrated whether or not such samples can be detected by primer halt method and primer run-off method.
Templated DNAs complementary to a plant miRNA andmurine miRNA have been synthesized. The synthesis was carried out in accordance with the above-mentioned Examples. The DNA contained further T residues at the 5' terminus, thereby allowed labeling by dideoxyATP at the 3 ' terminus .
Labeling and detection were carried out according to the above-described Examples except for those RNA used as set forth in SEQ ID NO: 6-9, in the primer halt method.
Figure 4 shows the results of the determination of the detection limit for the primer haltmethod, and the detection of an miRNA from an organism by the primer halt method.
Figure 4 dipicts the following in the left panel:
The left panel shows a series of dilutions of synthetic
RNAs similartothose showninFigure 3 (a) . The right-handed two panels show the detection of miRNA contained in the total
RNA prepared above.
Luc: reaction in which the luciferase gene which is not encoded by the plant, is used as a template to serve as a negative control. miRNA171: reaction inwhich a sequence containingmiR171 as a plant endognenous micro RNA (miRNA) and a single base
T in the primer halt method. As such, a plant endogenous miRNA can be detected.
A method for detecting a tobacco miRNA was carried out as follows :
5 μgoftobaccoplanttotalRNAwas extractedbytheTrizol method. miRNA171 or LUC was used as a template.
The reaction was carried out as follows: 1OX hybridizationbuffer solution (0.8 μl) , primer (0.1 pmol/1; 2 μl) , a template (0.1 pmol/1; 2 μl) andH2O to a final volume of 8 μl, was incubated at 95°C for 5 minutes and at 64°C for 30 minutes. A portion thereof (4 μl) was aliquoted and transferred to a fresh reaction tube, and 1OX Klenow buffer solution (1.25 μl) , Klenow fragment (0.5 μl) , [α-32P] ddATP (3000 Ci/mmol unless otherwise mentioned, this specificactivitywasusedherein; 4 μl) andH2O (2.75 μl) were addedandincubatedat 37 0C for1hour. Tothismixture, 8.5 μl of reaction termination/loading buffer solution was added. Thereafter, this was let stand at 95°C for 2 minutes to terminate the reaction, and placed on ice, and a portion thereof (e.g., 10 μl) was electrophoresedby 15 % denaturing acrylamide gel eletrophoresis (PAGE) to seperate the reactants for analysis .
As shown in the figure, as demonsrated by serially diluting the small RNA 1:10 to determine the detection sensitivity, it was demonstrated that the method of the present invention allows detection of at least the 5 atto mole (5 x 10"18) level.
The primer halt method allows us to detect an endogenous miRNA of an organism.
Next, it was verified to demonstrate whether the primer run-off method works.
Mice used were male C57 mice, and RNA isolated from the brain and the heart of these mice was used.
RNA isolated by means of Concert RNA extraction reagent (available from Invitrogen) was used as an RNA. DNA IG (=5 '-GGA ACT ATA CAA ACA TGA TGA GCT TTA ATG ATA TTG GCG CGG CTC AAT CA-3' (SEQ ID NO. : 12) ; negative control of GFP sense DNA) , miR16G (for detecting murine miRNA, Mmus miR16=GCG CCA ATA TTT ACG TGC TGC TAT GAT ATT GGC GCG GCT CAA TCA-3' (SEQ ID NO.: 13)) were used as a template.
The reaction was carried out as follows: 1OX hybridizationbuffer solution (0.8 μl) , primer (0.1 pmol/1; 2 μl) , a template (0.1 pmol/1; 2 μl) andH2O to a final volume of 8 μl, which was incubated at 95°C for 5 minutes and at 64°C for 30 minutes. Aportion thereof (4 μl) was aliquoted and transferred to a fresh reaction tube, and 1OX Klenow buffer solution (1.25 μl) , Klenow fragment (0.5 μl) , [α-32P] ddATP (Amersham, AAOO05, 3000 Ci/mmol; 4 μl) andH2O
(2.75 μl) were added and incubated at 37 °Cforlhour. This reactant is precipitated with ethanol, and 20 μl of reaction termination/loading buffer solution is added to the precipitated pellet . Thereafter, this was analysed by separating the content thereof by 15 % denatured PAGE. The electrophoresis was carried out at 400 V, for 30 minutes for performing "Pre Run", and thereafter, it ran at 400 V, for 30 minutes. Thereafter, the gel was dried and the detection was carried out by an autoradiogram. The results are shown in Figure 4B. Figure 4B demonstrates that murine miRNA can be confirmed with the primer run-off method.
As such, the present invention provides a novel primer halt method for detecting a small RNA. This is simple, but is very sensitive, and requires little time. Therefore, there are possibilies in which the method of the present invention will become a universal method in lieu of conventional Northern blotting or the like.
(Example 5: Investigation for improving other conditions) Inordertoimprove sensitivity, weconductedexperiments to improveme the hybridization reaction systems wherein 32P labeled dideoxy ATP was used. Mainly, hybridization temperature was studied.
Synthetic DNA 1 and RNA 1 (1 pmol, respectivly) were denaturedina smallvolume ofhybridizationbuffer solution, then it was maintained at 55-750C or room temperature for hybridization. To the resulting DNA-RNA hybrids, Klenow buffer solution (1OX solution: 0.5MTris-HCl (pH7.5), 0.IM MgCl2, 1OmM DTT, and 0.5 mg/ml bovine serum albumin were prepared and diluted ten-fold) without any other nucleotides than dideoxyATP was added and the DNA synthesis reaction was carried out. When heated at around 65°C, most intense incorporation was observed, but it was also observed that there is some intense radioactivity incorporated when it was returned to room temperature.
(Control experiments of the primer halt method) After the denaturing and the hybridization steps at 64°C were completed, with a small volume as described above, the DNA synthesis reaction was carried out in accordance with the above-mentioned conditions .
(i) Incorporation of 32P is dependent on the polymerase used, the small RNA used, the template used, ddATP used and the homology between the DNA and RNA used. Bands with slightly lower mobility than the RNA used (that is, having high molecular weight) , confirmed that a single base had been incorporated.
(ii) In the case of DNA2 andRNA2, abase tobe incorpoated following RNA2 is TTP, and thus no incorporation occurred in the case of ddATP only. However, by addition of dCTP and dTTP, the DNA synthesis reaction proceeded to A, 4 bases ahead of the terminus, and thus incorporation could be observed. Inthiscase, abandappearedwithhighermolecular than the template reflecting the incorporation 4 bases ahead of the terminus. Some non-specific reaction was observed, however, such a non-specific reaction did not affect the detection of the nucleic acid at hand. Non-specific detection can be confirmed by using control indicating the result being dependent on the interaction of the template and the target. Therefore, it was possible to confirm a specific reaction by the use of two types of lengths such as DNAl-G and DNAl-GlO.
(RNA labeling reaction with dCTP)
(iii) The combination of DNA 1-RNAl, the following bases are A, T, C, C, A, and T, and the reaction in the presence of 32P-dCTP and dATP, dTTP (all of these are deoxy type rather than dideoxy) , resulted in the incorporation of 32P-dCTP due totheabsenceofdGTP, andthus itwasexpectedthetermination would occur 6 bases ahead of the terminus. However,a band resulting in a relatively higher molecular weight due to non-specific extension of the nucleic acid, was observed.
(Primer halt reaction using ddATP in the combination of DNAl-RNAl)
(iv) dCTP was used in lieu of ddATP in the combination of DNA IG-RNAl. DNA IG has a sequence complementary to RNAl plusonebase (G) . Inthis reaction, noextensiontermination occurs by dideoxynucleotide, but when adding C, the template will be exhausted, and thus the reaction by the polymerase was terminated. (v) dCTP was used with the combination of DNA IGlO-RNAl .
DNA IGlO has a sequence complementary to RNAl plus 10 bases
(G) (5'-GGG GGG GGG GGA ACT ATA CAA ACA TGA TGA GCT TTA ATG
ATA TTG GCG C-3' (SEQ ID NO.: 14)) . In this reaction, no extension termination occurs by dideoxynucleotide, but when adding 10 bases (C) , the template will be exhausted, and thus the reaction by the polymerase was terminated.
As expected, when DNA IG was used as a template, a band which was believed to be a product with one base added as in the primer halt method with ddATP, was detected, and when using DNA 1-GlO , a band with a higher molecular weight was observed. Therefore, by using ssDNA having a sequence complementary to the targeted nucleic acid plus bases with a desired length as a template, it was demonstrated that labeling with limited length by run-off replication rather than run-off transcription, was possible.
(Example 6: Different Labelling methodology) Protocols exemplified in the above examples, are based on a radiolabelled nucleotide based method. However, the present invention may be conducted using a different labelling method. In the subject example, detection was carriedout usinga small RNAlabeledbya fluorescent labeled nucleotide. It is possible to use the present method in related fields such as capillary electrophoresis and the related arts thereto by using a label with such a fluorescent label . Accordingly, the present method can be applied to a sequence detemination method, and further, it is contamplated that a variety of applications using polynucleotides or oligonucleties will be possible as such polynucleotides andoligonucleotides canbedirectlylabeled in a sequence-specific manner. In thepresent example, examples with fluorescent labels were demonstrated.
First, 1OX hybridization buffer solution (1.5 M KCl, 0.1 M Tris-HCl (pH 7.5), 5mM EDTA; 0.8μl); primer 1 (0.1 pmol/μl) 2μl; template DNA Ia (0.1 pmol/μl) 2μl; and H2O (3.2 μl) were added to form a reaction solution (8 μl) . This was incubated at 95°C for 5 minutes, and thereafter the reaction was continued at 640C for 30 minutes. To this mixture, 8.5 μl of reaction solution (10 X Klenow buffer solution 1.25μl, Klenow fragment 0.5 μl, 20 mM Cy5-dCTP 1.25 μl, H2O 4μl) was added and incubated at 370C for 60 minutes. To this mixture, 8.5 μl of reaction termination/loading staining solution (0.05% (bromophenol blue (BPB), 0.05% xylene cyanol (XC) and 2OmM EDTA was solubilized in the formamide) were added and incubated at 950C for 2 minutes, and placed on ice. This was electrophoresed on 15 % PAGE, and scanned with FLA-8000 (Fujifilm) .
This demonstrated that the method of the present invention may be carried out using a fluorescent label.
(Example 7: experiments using reverse transcriptase enzyme)
The above exemplified protocols can be carried out in the case using reverse transcriptase enzyme.
As a reverse transcriptase enzyme, M-MLV reverse transcriptase enzyme RNaseH Minus (TOYOBO code number: RTN-101) is used. As a plasmid, pT3/T7-LUC (Clonetech) is used. This plasmid produces a linearised product by Smal digestion. This results in a product of blunt ended product having LUC adjacent to T3. Thereafter, the transcription reactionis carriedout invitro. Thetranscriptionreaction is carried out as follows: 5X reactionbuffer solution 10 μl; rNTP (10 mM for each) ; T3 polymerase (TOYOBO, code number: SC600111) 1 μl: and DNA 2 μl were mixed to form 50 μl, and proceeded at 370C for 30 minutes. Thereafter, ethanol precipitation was carried out, and dissolved in 10 μl TE (composition: 1 mmol/L EDTA containing 10 mmol/L Tris buffered solution, pH 9.0) . This is used as a template. Thereafter, 1OX hybridization buffer solution, 2 μl of template nucleic acid (LUC RNA) , 5 μl of tobacco (wild type plant, LUC high expression plant or LUC silincedplant) total RNA were mixed to in a final volume of 8 μl, and incubated at 95°C for 5 minutes, and thereafter incubated at 640C for 30 minutes. 4μl of this was added to 1.25 μl of 1OX M-MLV reversetranscriptaseenzymebuffersolution (availablefrom TOYOBO, 5Xreactionbuffer solutionwasappropriatelydiluted in 250 mMTris-HCl (pH 8.3), 375 mMKCl, 15 mMMgCl2 and 5OmM DTT), 0.5 μl of M-MLV reverse transcriptase enzyme (available) , lμl of RNase inhibitor , 4 μl of [α-32P]ddATP , 1.25 μl of H2O and incubated at 370C for 60 minutes. To this mixture, 8.5μl termination loading buffer solution was added, and subjected to isopropanol precipitation, and electrophoresed with 15 % PAGE for analysis. This demonstrates that the present inventioninvention may be applied to cases using reverse transcriptase enzyme.
(Example 8 : construction of an array) DNA is synthesized to contain a specific sequence as a probe at the 3' terminus, and adjusted the concentration thereof to 200 pmol/μl. lμl of this DNA was removed and immobilized onto a nylon membrane. mRNA (2μg) or total RNA (40μg) is dissolved in sterilized MiIIiQ water (0.48ml) . This RNA solution is injected into a hybridization bag containing the nylon membrane, and annealed at 640C for 30 minutes, and incubated at 420C for 10 minutes. 40 μl Superscript II (200 units/μl, GIBCO BRL) , 150 μl 5X Superscript II reaction buffer solution (GIBCO BRL), 80 μl DTT (0.1M, GIBCOBRL), 40 μl dNTP, mixture (dATP, dGTP, dTTP (40 mM for each), dCTP (20 itiM) , Amercham Pharmacia) , and 40 μl Cy5-dCTP (2OmM, Amersham Pharmacia) were mixed, poured into the hybridization bag, and incubated at 420C for 2.5 hours in the dark. The membrane is washed once with a primary wash solution (0.2% SDS containing IX SSC (15mM sodium citrate, 150 mM NaCl, pH 7.0), 65°C) , and washed twice with secondary wash solution (0.1X SSC containing 0.2% SDS, 65°C) . After removal of moisture, fluorescence of Cy5 is detected and determined by the use of a fluorescence scanner (FLA-8000, FUJIFILM) .
It is thus understood that the claimed invention may be applied to the primer array method.
Although certain preferred embodiments have been described herein, it is not intended that such embodiments be construed as limitations on the scope of the invention except as set forth in the appended claims. Various other modifications and equivalents will be apparent to and can be readily made by those skilled in the art, after reading the description herein, without departing from the scope and spirit of this invention. All patents, publishedpatent applications andpublications cited herein are incorporated by reference as if set forth fully herein. INDUSTRIAL APPLICABILITY
The present invention is useful in a number of fields including general industry, pharmaceutical industry relating to agriculture and biosciences, as it is useful in a number of cases requiring detection of nucleic acid involving a variety of diagnoses, as the present invention allows simple detection of a nucleic acid.

Claims

1. Amethod for producing a nucleic acidhaving an introduced label, comprising the steps of: A) providing a nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, andthe template nucleic acidhaving anucleotide sequence of at least one nucleotide extending from at least oneendofthenucleicacidtobe labeledwhenthecomplementary- portion of the nucleic acid to be labeled hybridizes with the template nucleic acid;
B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex;
C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and
D) recovering the elongated nucleic acid to be labeled from the resultant mixture, after the extension reaction.
2. A method according to claim 1, wherein the nucleic acid to be labeled is DNA, RNA, or a combination thereof.
3. A method according to claim 1, wherein the nucleic acid to be labeled is RNA.
4. A method according to claim 1, wherein the nucleic acid to be labeled is RNA selected from the group consisting of siRNA and miRNA.
5. A method according to claim 1, wherein the template nucleic acidcomprises a sequence complementaryto the entire nucleic acid to be labeled.
6. A method according to claim 1, wherein the template nucleic acid has a nucleotide sequence of at least one nucleotide extending from both ends of the nucleic acid to be labeled.
7. A method according to claim 1, wherein the template nucleic acid has a nucleotide sequence extending by at least about 10 nucleotides from the at least one end of the nucleic acid to be labeled.
8. A method according to claim 1, wherein the extending nucleotide sequence of the template nucleic acid is located on the 5' terminal side of the template nucleic acid.
9. A method according to claim 6, wherein the extending nucleotide sequence of the template nucleic acid on the 3' terminal side of the template nucleic acid has a different length than that of the extending nucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
10. A method according to claim 1, wherein the extending nucleotide sequence of the template nucleic acid is located on the 5' terminal side of the template nucleic acid, and a 5' terminalportionof thenucleic acidtobe labeledextends from the 3' end of the template nucleic acid.
11. A method according to claim 6, wherein the extending nucleotide sequence of the template nucleic acid on the 3 ' terminal side of the template nucleic acid is longer by a distinguishable lengththanthat of the extendingnucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
12. A method according to claim 11, wherein the distinguishable length is at least 10 nucleotides.
13. A method according to claim 1, wherein the nucleic acid synthesizing enzyme is DNA-dependent DNA polymerase or RNA-dependent DNA polymerase.
14. A method according to claim 1, wherein the labeled nucleotide includes a nucleotide labeled with a label selected from the group consisting of fluorescence, radioactivity, phosphorescence, biotin, digoxigenin (DIG) , an enzyme, and chemiluminescence.
15. A method according to claim 1, wherein the labeled nucleotide includes radioactivity.
16. A method according to claim 1, wherein the step of recoveringtheelongatednucleicacidtobe labeledcomprises a denaturing step.
17. A method according to claim 1, further comprising removing unreacted matter.
18. A method according to claim 17, wherein the step of removing unreacted matter is achieved by ethanol precipitation or gel filtration chromatography.
19. A method according to claim 17, wherein the step of removingunreactedmattercomprises separatingtheelongated nucleic acid to be labeled.
20. A method according to claim 17, wherein the separating step is achieved by electrophoresis or chromatography.
21. A method according to claim 1, wherein the step of recoveringthe elongatednucleicacidtobe labeledcomprises detecting the label.
22. A method according to claim 21, wherein the detecting step comprises detecting the label directly or indirectly.
23. A method according to claim 21, further comprising separating the elongated nucleic acid to be labeled.
24. A method according to claim 23, wherein the detecting step is performed in the separating step.
25. A method according to claim 24, wherein the separating and detecting steps are achieved by autoradiography.
26. A method according to claim 1, further comprising terminating the extension reaction.
27. A method according to claim 26, wherein the terminating step is achieved by a primer halt method or a primer run-off method.
28. A method according to claim 1, wherein the nucleic acid to be labeled is used as a probe.
29. A method according to claim 1, wherein the nucleic acid to be labeled is a nucleic acid to be detected.
30. A method according to claim 1, wherein a terminal nucleotide of the template nucleic acid is modified.
31. A method according to claim 1, wherein the 3' terminal nucleotide of the template nucleic acid is modified.
32. A method according to claim 1, wherein a terminal nucleotide of the template nucleic acid is modified not to incorporate a label nucleotide.
33. Amethodaccording to claim 30, wherein themodification is selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
34. A method according to claim 1, wherein the 3' terminal nucleotide of the template nucleic acid is subjected to modification selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation
(FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
35. A method for introducing a label into a nucleic acid, comprising the steps of:
A) providing the nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acidhaving a nucleotide sequence of at least one nucleotide extending from at least oneendofthenucleicacidtobelabeledwhenthecomplementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid;
B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex; and C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid.
36. Amethod for detecting a target nucleic acid, comprising the steps of :
A) providing the target nucleic acid and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the target nucleic acid, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid;
B) hybridizing the target nucleic acid with the template nucleic acid to produce a target nucleic acid-template nucleic acid complex; C) subjecting the target nucleic acid-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used; and D) detecting when an extension product corresponding to the target nucleic acid is present, the presence of the extension product being an indicator of the target nucleic acid.
37. A method according to claim 36, further comprising separating unreacted matter of the labeled nucleotide and the extension product from the resultant mixture, after the extension reaction.
38. A method according to claim 36, wherein the target nucleic acid is DNA, RNA, or a combination thereof.
39. A method according to claim 36, wherein the target nucleic acid is RNA.
40. Amethod according to claim 36, wherein the nucleic acid is RNA selected from the group consisting of siRNA andmiRNA.
• 41. A method according to claim 36, wherein the template nucleic acidcomprises a sequence complementaryto the entire target nucleic acid.
42. A method according to claim 36, wherein the template nucleic acid has a nucleotide sequence of at least one nucleotide extending from both ends of the target nucleic acid.
43. A method according to claim 36, wherein the template nucleic acid has a nucleotide sequence extending by at least about 10 nucleotides from the at least one end of the target nucleic acid.
44. A method according to claim 36, wherein the extending nucleotide sequence of the template nucleic acid is located on the 5' terminal side of the template nucleic acid.
45. A method according to claim 42, wherein the extending nucleotide sequence of the template nucleic acid on the 3' terminal side of the template nucleic acid has a different length than that of the extending nucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
46. A method according to claim 36, wherein the extending nucleotide sequence of the nucleic acid to be labeled is locatedon the 5' terminal side of the template nucleic acid, and a 5' terminal portion of the nucleic acid to be labeled extends from the 3' end of the template nucleic acid.
47. A method according to claim 42, wherein the extending nucleotide sequence of the template nucleic acid on the 3' terminal side of the template nucleic acid is longer by a distinguishable lengththanthat of the extendingnucleotide sequence of the template nucleic acid on the 5' terminal side of the template nucleic acid.
48. A method according to claim 47, wherein the distinguishable length is at least 10 nucleotides .
49. Amethod according to claim 36, wherein the nucleic acid synthesizing enzyme is DNA-dependent DNA polymerase or RNA-dependent DNA polymerase.
50. A method according to claim 36, wherein the labeled nucleotide includes a nucleotide labeled with a label selected from the group consisting of fluorescence, radioactivity, phosphorescence, biotin, digoxigenin (DIG) , an enzyme, and chemiluminescence.
51. A method according to claim 36, wherein the labeled nucleotide includes radioactivity.
52. A method according to claim 36, wherein the step of separating the extension product and the target nucleic acid-template nucleic acid complex is achieved by a denaturing step.
53. A method according to claim 36, wherein the unreacted matter is separated from the extension product by removing the unreacted matter by ethanol precipitation or gel filtration chromatography.
54. A method according to claim 36, wherein the detecting step comprises detecting the label directly or indirectly.
55. A method according to claim 36, further comprising recovering the extensionproduct corresponding to the target nucleic acid.
56. A method according to claim 37, wherein the separating step is achieved by electrophoresis or chromatography.
57. A method according to claim 37, wherein the detecting step is performed in the separating step.
58. A method according to claim 57, wherein the separating and detecting steps are achieved by autoradiography.
59. A method according to claim 36, further comprising terminating the extension reaction.
60. Amethod according to claim 59, wherein the terminating step is achieved by a primer halt method or a primer run-off method.
61. A method according to claim 36, wherein the detecting stepisperformedbasedonasequenceoftheelongatedportion.
62. A method according to claim 36, wherein the detecting step is performed using a pharmaceutical agent specifically- binding to the elongated target nucleic acid.
63. A method according to claim 62, wherein the detecting step is performed by detecting a label attributed to the labeled nucleotide and a label attributed to the pharmaceutical agent .
64. A method according to claim 62, wherein the pharmaceutical agent specifically binding to the elongated target nucleic acid does not bind to the target nucleic acid not elongated or the labeled nucleotide.
65. A method according to claim 36, wherein the detecting step is performedbased on the length of the elongated target nucleic acid.
66. A method according to claim 36, wherein a terminal nucleotide of the template nucleic acid is modified.
67. A method according to claim 36, wherein the 3' terminal nucleotide of the template nucleic acid is modified.
68. A method according to claim 36, wherein a terminal nucleotide of the template nucleic acid is modified not to incorporate a label nucleotide.
69. Amethodaccording to claim 66, whereinthemodification is selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
70. A method according to claim 36, wherein the 3' terminal nucleotide of the template nucleic acid is subjected to modification selected from the group consisting of dideoxy chain termination method, fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
71. A kit for producing a nucleic acid having an introduced label, comprising:
A) a template nucleic acidcomplementaryto at least a portion of a target nucleic acid to be labeled, and having a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid; and
B) a nucleic acid synthesizing enzyme.
72. A kit according to claim 71, further comprising:
C) a labeled nucleotide.
73. A kit according to claim 72, further comprising: ameansforseparatingunreactedmatterofthelabeled nucleotide and an extension product from the resultant mixture.
74. A kit according to claim 72, further comprising: a means for detecting the labeled nucleotide.
75. A kit according to claim 71, further comprising: a reference target nucleic acid as a control.
76. Akit accordingtoclaim 75, whereinthe standardnucleic acid includes a nucleic acid selected from the group consisting of a nucleic acid for identifying the template nucleic acid and a nucleic acid for identifying the target nucleic acid.
77. A kit according to claim 71, further comprising: a reagent for reaction of the nucleic acid synthesizing enzyme.
78. A kit according to claim 72, wherein the labeled nucleotide has a function of terminating the reaction of the nucleic acid synthesizing enzyme.
79. A kit according to claim 71, further comprising: a support, wherein the template nucleic acid is immobilized on the support.
80. A kit according to claim 79, wherein the support is made of glass or membrane.
81. Akit accordingtoclaim 79, whereinthe templatenucleic acid immobilized on the support is arranged in an array.
82. A kit according to claim 71, wherein a terminal nucleotide of the template nucleic acid is modified.
83. A kit according to claim 1, wherein the 3' terminal nucleotide of the template nucleic acid is modified.
84. A kit according to claim 71, wherein a terminal nucleotide of the template nucleic acid is modified not to incorporate a label nucleotide.
85. A kit according to claim 82, wherein the modification is selected from the group consisting of , fluoresceinisothiocyanatation (FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA), thiolation, and rhodamination.
86. A kit according to claim 71, wherein the 3' terminal nucleotide of the template nucleic acid is subjected to modification selected from the group consisting of dideoxy chain termination method, fluorescein isothiocyanatation
(FITC) , biotinylation, amination, phosphorylation, tetramethylrhodamination (TAMRA) , thiolation, and rhodamination.
87. A method for producing a support having a label-introduced nucleic acid immobilized thereon, comprising the steps of:
A) providing a target nucleic acid to be labeled and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, andthe template nucleic acidhaving anucleotide sequence of at least one nucleotide extending from at least oneendofthenucleicacidtobelabeledwhenthecomplementary- portion of the nucleic acid to be labeled hybridizes with the template nucleic acid;
B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex;
C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and D) recovering the support including the elongated nucleic acid to be labeled from the resultant mixture after the extension reaction.
88. A method according to claim 87, wherein the recovering step is achievedbyremoving reactionmatter fromthe support by washing.
89. A method according to claim 87, wherein the recovering step is achieved by removing the label from the support.
90. A kit for detecting a target nucleic acid, comprising:
A) a template nucleic acidcomplementaryto at least a portion of the target nucleic acid, andhaving a nucleotide sequence of at least one nucleotide extending from at least one end of the target nucleic acid when the complementary portion of the target nucleic acid hybridizes with the template nucleic acid;
B) a nucleic acid synthesizing enzyme; C) a labeled nucleotide; and
D) a means for detecting the labeled nucleotide.
91. A kit according to claim 90, further comprising: ameansforseparatingunreactedmatterofthelabeled nucleotide and an extension product from the resultant mixture.
92. A kit according to claim 90, wherein a terminal nucleotide of the template nucleic acid is modified.
93. Amethod for detecting a target nucleic acid on a support having a nucleic acid immobilized thereon, comprising the steps of: A) providing a template nucleic acid immobilized on the support and a nucleic acid to be labeled, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid;
B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex;
C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and
D) after the extension reaction, detecting when the elongatednucleic acidtobe labeledispresent, thepresence of the elongatednucleic acidtobe labeledbeing an indicator of the target nucleic acid.
94. Amethod according to claim 93 , wherein the nucleic acid to be labeled is siRNA.
95. A method according to claim 93, wherein the support is an array.
96. Amethod for detecting a target nucleic acid on a support having a nucleic acid immobilized thereon, comprising the steps of :
A) providing a nucleic acid to be labeled, which is immobilized on the support, and a template nucleic acid, the template nucleic acid being complementary to at least a portion of the nucleic acid to be labeled, and the template nucleic acid having a nucleotide sequence of at least one nucleotide extending from at least one end of the nucleic acid to be labeled when the complementary portion of the nucleic acid to be labeled hybridizes with the template nucleic acid;
B) hybridizing the nucleic acid to be labeled with the template nucleic acid to produce a nucleic acid to be labeled-template nucleic acid complex; C) subjecting the nucleic acid to be labeled-template nucleic acid complex to an extension reaction, in which a nucleic acid synthesizing enzyme and labeled nucleotides are used, so that at least one of the labeled nucleotides is incorporated into the nucleic acid to be labeled based on the template nucleic acid; and
D) after the extension reaction, detecting when the elongatednucleic acidtobe labeled is present, the presence of the elongatednucleic acidtobe labeledbeing an indicator of the target nucleic acid.
97. A method according to claim 96, wherein the template nucleic acid is mRNA.
98. A method according to claim 96, wherein the support is an array.
PCT/IB2005/052245 2004-07-07 2005-07-06 Novel method for labeling nucleic acid in a sequence-specific manner, and method for detecting nucleic acid using the same WO2006003638A2 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5571669A (en) * 1993-01-14 1996-11-05 The University Of Pennsylvania Transcription and nucleic acid sequence determination with short primer DNA/RNA molecules and RNA polymerase
US20040146867A1 (en) * 2003-01-24 2004-07-29 Slattum Paul M Compounds and processes for single-pot attachment of a label to siRNA

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5571669A (en) * 1993-01-14 1996-11-05 The University Of Pennsylvania Transcription and nucleic acid sequence determination with short primer DNA/RNA molecules and RNA polymerase
US20040146867A1 (en) * 2003-01-24 2004-07-29 Slattum Paul M Compounds and processes for single-pot attachment of a label to siRNA

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
BEHLKE M A ET AL: "Use of high specific activity StarFireTM oligonucleotide probes to visualize low-abundance pre-mRNA splicing intermediates in S. pombe" BIOTECHNIQUES, vol. 29, no. 4, October 2000 (2000-10), pages 892-897, XP001208234 ISSN: 0736-6205 *
DAUDE NATHALIE ET AL: "Specific inhibition of pathological prion protein accumulation by small interfering RNAs." JOURNAL OF CELL SCIENCE, vol. 116, no. 13, 1 July 2003 (2003-07-01), pages 2775-2779, XP002362880 ISSN: 0021-9533 *
GANDRILLON O ET AL: "A rapid and convenient method to prepare DIG-labelled RNA probes for use in non-radioactive in situ hybridization." MOLECULAR AND CELLULAR PROBES. FEB 1996, vol. 10, no. 1, February 1996 (1996-02), pages 51-55, XP002362879 ISSN: 0890-8508 *
SANGER F ET AL: "DNA SEQUENCING WITH CHAIN-TERMINATING INHIBITORS" PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE USA, NEW YORK, NY, US, vol. 74, no. 12, 1 December 1977 (1977-12-01), pages 5463-5467, XP000603873 *

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