WO2006018316A1 - Procedes pour la production de betail ameliore et modeles de maladie pour la recherche therapeutique - Google Patents

Procedes pour la production de betail ameliore et modeles de maladie pour la recherche therapeutique Download PDF

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WO2006018316A1
WO2006018316A1 PCT/EP2005/009003 EP2005009003W WO2006018316A1 WO 2006018316 A1 WO2006018316 A1 WO 2006018316A1 EP 2005009003 W EP2005009003 W EP 2005009003W WO 2006018316 A1 WO2006018316 A1 WO 2006018316A1
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cell
cells
somatic
oocyte
clonal
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PCT/EP2005/009003
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Sigrid Wattler
Ulrike Huffstadt
Reinhard Sedlmeier
Michael Christian Nehls
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Ingenium Pharmaceuticals Ag
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Priority to EP05781897A priority Critical patent/EP1778835A1/fr
Publication of WO2006018316A1 publication Critical patent/WO2006018316A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
    • C12N15/01—Preparation of mutants without inserting foreign genetic material therein; Screening processes therefor
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K67/00—Rearing or breeding animals, not otherwise provided for; New or modified breeds of animals
    • A01K67/027—New or modified breeds of vertebrates
    • A01K67/0273—Cloned vertebrates
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
    • C12N15/09—Recombinant DNA-technology
    • C12N15/87—Introduction of foreign genetic material using processes not otherwise provided for, e.g. co-transformation
    • C12N15/873—Techniques for producing new embryos, e.g. nuclear transfer, manipulation of totipotent cells or production of chimeric embryos
    • C12N15/877—Techniques for producing new mammalian cloned embryos
    • C12N15/8775—Murine embryos
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K2227/00—Animals characterised by species
    • A01K2227/10—Mammal
    • A01K2227/105—Murine

Definitions

  • the pig has proven to be a good model for pancreatic cancer (Kurahashi et al., 2004) and kidney stone disease (Mandel et al., 2004). Furthermore, the pig is a good ischemia model (Hughes GC et al., 2004).
  • larger domestic animals may provide transplant organs like heart, liver, and kidney. Due to the problem of donor rejection, those animals need to be modified to overcome immunological problems prior to their use to generate organs.
  • donor rejection is due to sugar-based molecules called alpha- 1,3-galactosylated moieties located at the surface of pig cells.
  • Lai et al. (2002) described a knockout in pig of one allele of the gene GGTAl, which encodes the enzyme alpha-l,3-galactosyl transferase. This transferase is involved in transferring the sugar molecules onto the pig cell surface. Phelps et al.
  • mice (Mighty mouse) and cattle (“Belgium Blue cattle”) with inactivating mutations of myostatin have marked muscle hypertrophy.
  • US Patent 5,994,618 discloses transgenic mice carrying a disrupted endogenous myostatin gene. Transgenic mice were significantly larger than wild-type animals and displayed a large and widespread increase in skeletal muscle mass.
  • US Patent 6,103,466 discloses, e.g., cattle myostatin polynucleotide sequences with an 11 bp deletion, resulting in a non-functional myostatin protein.
  • a well-known chemical mutagen in this respect is, e.g., N-ethyl-N- nitrosourea (ENU).
  • mice In mice, the introduction of point mutations in male germ cell DNA is currently performed by intraperitoneal ENU-injection.
  • the mutagenized mouse or its offspring is analyzed for an aberrant phenotype, e.g., mutation identification may be performed with a screen of phenotypic alterations prior to mutation identification in a gene of interest.
  • the injected animal or its offspring is analyzed for a mutation in a gene of interest on a molecular basis without prior observation of any phenotype (see US
  • Embryonic stem (ES) cells may also be subjected to ENU mutagenesis, as described in US Patent 6,015,670, WO 97/44485, and WO 99/67361.
  • ENU mutagenesis has also been described for other species, e.g., Drosophila melanogaster (Vogel and Natarajan, 1995), ascidians (Moody et al., 1999), or zebrafish (Grunewald and Streisinger, 1992).
  • Drosophila melanogaster Vogel and Natarajan, 1995
  • ascidians Moody et al., 1999
  • zebrafish Grunewald and Streisinger, 1992
  • ascidians and zebraf ⁇ sh have been treated with ENU by direct incubation of the organism in ENU (e.g., Moody et al., 1999).
  • Grunewald and Streisinger (1992) reported in vitro ENU mutagenesis of freshly isolated zebrafish sperm and subsequent mixing with freshly collected eggs for fertilization.
  • ENU mutagenesis Compared to known transgenic methods, e.g., ES-cell mediated gene transfer (Bradley et al., 1984; Capecchi et al., 1989), DNA microinjection (Betsch et al., 1995), nucleus transfer in combination with an initial manipulation of the donor nucleus by a transgene insertion (Schnieke et al., 1998) or Lenti- virus induced gene transfer (Hofman et al., 2004), ENU mutagenesis has the advantage of introducing particular point mutations, i.e., subtle DNA modifications without introducing foreign DNA (for example antibiotic selection marker gene or viral genetic material) into the recipient's genome - like in transgenic animals.
  • ES-cell mediated gene transfer Bradley et al., 1984; Capecchi et al., 1989
  • DNA microinjection Betsch et al., 1995
  • transgenic farm animals are classified as genetically modified organisms (GMO) with subsequent restrictions.
  • GMO genetically modified organisms
  • ENU mutagenesis is useful for the generation of hypomorphic, hypermorphic and neomorphic alleles of a gene in a model organism, e.g., by single amino acid substitutions. This may be desirable to create a model organism for, e.g., a human trait or disease in which gene function is modified rather than destroyed.
  • the ENU method also allows for the identification of an allelic series of mutations in a gene of interest.
  • These mutations might be desirable mutations that merely modify gene function (e.g. hypomorphic or hypermorphic alleles that express the gene with reduced or increased efficiency) or that give rise to a new trait in the animal (e.g. by generating dominant neomorphic alleles which result in a gain-of-function or loss-of function).
  • the usefulness of identifying an allelic series of alterations in a gene of interest was illustrated in the human peroxisome proliferator-activated receptor gamma (PP AR ⁇ ) gene (Barroso et al., 1999).
  • a dominant-negative V290M mutation and a dominant- negative P467L mutation in the receptor's ligand-binding domain, respectively, is associated with an unusual syndrome of severe insulin resistance, early onset diabetes and hypertension. Therefore, a new subtype of dominantly inherited type 2 diabetes was described, due to defective transcription factor function of PP AR ⁇ .
  • the underlying point mutations provided the first time evidence for the direct involvement of PP AR ⁇ in the control of insulin sensitivity, glucose homeostasis and blood pressure in man (Barroso et al., 1999).
  • ENU mutagenesis in mice is performed as intraperitoneal injection of ENU into male mice (see Example 1 of WO 2004/020619), using defined mg/kg dosages of ENU, which are injected once or several times. Due to ENU-induced sterility, the earliest date at which male mice can be mated to females is fifty days after the final ENU injection, when fertility starts to overcome the ENU-induced sterility. The subsequent Gl offspring represents a "living archive", which is subject to phenotypic and nucleic acid analyses, in order to identify a mutation in a gene of interest.
  • Intraperitoneal application of ENU to larger farm/domestic animal for example male cattle will, however, be associated with relatively high costs and low efficiency. For cattle with a reproduction cycle of 12 month and on average 1 offspring per pregnancy, it would require much time and space to generate the above-mentioned living archive. In addition, dosage testing and optimization may take some time, since intraperitoneal ENU injection may imply lethality of the ENU recipient at certain doses. Furthermore, large amounts of ENU would be required. For a bull with up to 700 kg body weight approximately 63 g of ENU need to be injected in a single dosage. If it survived injection, the period of sterility of a bull may last up to several months.
  • "living archive” of Gl ENU-mutagenized mice another method for identifying a mutation in a gene of interest comprises the parallel isolation of a tissue sample (for the further isolation of nucleic acid samples) and of sperm cells from all Gl male offspring.
  • the tissue sample and sperm cells are subjected to freezing, representing a "frozen archive”.
  • the step of replacing a "living archive” of up to several thousand Gl offspring with a "frozen archive” reduces costs and increases the speed in analysis and generation of mutant animals: nucleic acid samples are used for the analysis of a mutation in a gene of interest by industrial HTS screening of the nucleic acids.
  • the corresponding sperm cells are thawed and subsequently used for in vitro fertilization.
  • the resulting embryos are implanted into a foster mother's uterus to generate offspring.
  • the offspring is carrying the previously identified mutation in a gene of interest, according to Mendelian rules.
  • sperms of certain animal species especially those that do not fertilize ex vivo, do not always tolerate a freezing procedure well, which may make it difficult to establish an archive that is representative of a large number of mutations.
  • somatic cell nuclear transfer is performed by fusion of a somatic donor cell with an enucleated recipient cell.
  • an isolated somatic cell nucleus is transferred into an enucleated recipient cell by microinjection to generate an embryo (Wakayama et al., 1998).
  • a resulting embryo is subject to embryo transfer into the uterus of a pseudopregnant mother animal in order to generate a living animal offspring.
  • nuclear transfer was proven to be a cloning method suitable for many different species, e.g., cattle (Kato et al., 1998), goat (Ohkoshi et al., 2003), pig (Polejaeva et al., 2000), mouse (Ono et al. 2001; Wakayama et al., 1998), rabbit (Chesne et al., 2002), rat (Iannaccone et al., 2001), cat (Shin et al., 2002), and zebrafish (Lee et al., 2002).
  • this technique is capable of rendering many species a potential target for genetic modification and subsequently a source for valuable genetic models.
  • somatic cells In order to successfully manipulate an organism it is mandatory to manipulate isolated somatic cells from the donor animal in tissue culture first. Of significant importance is the issue that somatic cells keep competence for nuclear transfer after manipulation. Many researchers concentrated on that particular issue when performing somatic cell nuclear transfer techniques at different species, e.g., bovine (Roh et al., 2000, Kubota et al., 1999, and Cibelli et al., 1998), sheep (McGreath et al., 2000 and Schnieke et al., 1997), pig (Bandioli et al., 2001, and Lai et al., 2002), and zebrafish (Lee et al., 2002).
  • bovine Roh et al., 2000, Kubota et al., 1999, and Cibelli et al., 1998)
  • sheep McGreath et al., 2000 and Schnieke et al., 1997)
  • pig Bandioli et
  • the invention is inter alia directed to a method of generating mutated non- human animals and embryos capable of producing such mutated non-human animals.
  • the method of the present invention is applicable to many species.
  • the method of the present invention of mutagenizing somatic cells provides the possibility to efficiently mutate every gene in an organism. With this method, it is, e.g., possible to efficiently determine the appropriate dosage regime regarding a particular mutagen in vitro, resulting in a substantial saving of time, costs and animals.
  • the present invention provides in a first aspect a method of providing an embryo capable of producing a mutated non-human animal comprising:
  • step (b) generating a cell clone or a clonal cell line from the somatic cell treated according to step (a);
  • step (c) introducing the nucleus of a cell of the cell clone or the clonal cell line of step (b) into an enucleated oocyte to form a 1 cell-stage embryo; or
  • step (d) introducing the nucleus of a cell of the cell clone or the clonal cell line of step (b) into an enucleated oocyte and transferring the subsequently formed pronucleus or nucleus into a second enucleated oocyte to form a 1 cell-stage embryo; or
  • step (e) introducing the nucleus of a cell of the cell clone or the clonal cell line of step (b) into an enucleated oocyte and consecutively transferring the subsequently formed pronucleus or nucleus into a second and further enucleated oocytes, e.g., into a second and subsequently a third enucleated oocyte, to form a 1 cell-stage embryo.
  • step (b) comprises
  • the somatic cell treated in step (a) is derived from a non-human embryo. It may, however, also be derived from an adult non-human animal, hi a preferred embodiment, the somatic cell treated in step (a) is a fetal fibroblast cell, or an adult fibroblast cell, including, but not limited to, a skin fibroblast cell. Other suitable and preferred cells are granulosa cells, cumulus cells, or oviduct cells.
  • the method of the invention may additionally comprise the screening of a nucleic acid sample derived from one or more cells of the cell clone or cell line obtained in step (b) for the presence of a mutation in a gene of interest.
  • the method may further comprise the step of assigning said mutation to a corresponding cell clone or clonal cell line or the corresponding cell clone or clonal cell line generated according to step (b).
  • the invention provides a method of producing a mutated non-human animal, which method comprises the use of a cell or cells of a cell clone or clonal cell line prepared according to steps (a) and (b) of the method of the invention.
  • the method comprises the introduction of the nucleus of a cell from said cell clone or clonal cell line into the cytoplasm of an enucleated non-human oocyte, preferably of the same species from which said clonal cell is derived, and subsequently reimplanting the embryo thus formed into a suitable non-human animal pseudopregnant mother.
  • the invention further provides an archive comprising stored clonal cells and cell lines generated according to steps (a) and (b) or derived from one or more cells of the non-human animals.
  • the invention also provides a method of producing a non-human animal, wherein said method further comprises breeding of the non-human animal(s) produced by the method as described herein to produce a plurality of offspring.
  • Figure 1 depicts a flow chart, describing in an exemplary manner the method of the invention for generating non-human animals from mutagenized somatic cells.
  • a somatic cell derived from embryonic or adult tissue is subjected to mutagenesis.
  • single cells are isolated and expanded to clonal cell lines to be kept in a culture repository for short-term storage ("short-term archive”), or in a frozen repository (“frozen archive”) for long-term storage.
  • Cells from each clonal cell line are subjected to DNA isolation for subsequent mutation screening in respect of a gene of interest.
  • a single cell (or single cells) from this clonal cell line is (are) used for somatic cell nuclear transfer to generate (a) mutant embryo(s).
  • Heterozygous Gl offspring is used for breeding with wild type animals (het x wt) to produce a G2 generation with a plurality of heterozygous offspring. Breeding of selected heterozygotes from G2 (het x het) is performed to obtain homozygous offspring in G3. A plurality of homozygous offspring is obtained by inter-breeding of homozygous G3 offspring (horn x hom) to generate Gn offspring. Gn refers to any offspring generation following G3 offspring and may be used to expand the number of homozygous offspring.
  • organs refer to multicellular eukaryotes that undergo development from an embryonic stage to an adult stage. Accordingly, this includes vertebrates and invertebrates, which fall within the term “animal”, as well as plants and fungi.
  • the invention is useful with respect to animals, such as insects, nematodes, fish, such as salmon; or mammals, for example ungulates, such as pig, cattle, goat, or sheep; or odd-toed ungulates, such as horse; or rodents, such as mouse or rat.
  • treating a cell with a mutagen refers to contacting the cell with, or exposing it to, a mutagen of choice. This is preferably done under in vitro conditions.
  • phenotype refers to one or more morphological, physiological, behavioral and/or biochemical traits possessed by a cell or organism that result from its genotype.
  • alteration of the phenotype refers to a non- human animal of the present invention displaying one or more readily observable abnormalities compared to the wild-type animal.
  • an animal obtained via the methods of the invention shows at least 1, at least 2, at least 3, or at least 4 abnormal phenotypic features selected from any of the above categories.
  • the animal shows a loss of function phenotype.
  • the animal shows a gain of function phenotype.
  • phenotypic alterations that are favorable for medical or economic reasons, such as exhibiting human disease symptoms, disease resistance in farm animals, immunological tolerance, or modulation of gene function.
  • Gl offspring mean the first (Gl, generation 1), second (G2, generation 2), and third generation (G3; generation 3) of offspring generated by somatic cell nuclear transfer techniques. Gl offspring is heterozygous for a mutation in a gene of interest.
  • nucleic acid refers to DNA, such as genomic DNA, or cDNA, but also RNA.
  • RNA refers to a segment of DNA which may be transcribed into RNA, and which may comprise an open reading frame, intronic sequences, and also includes the regulatory elements which control expression of the transcribed region. Therefore, a mutation in a gene may occur within any region of the DNA, which is transcribed into RNA, or outside of the open reading frame and within a region of DNA which regulates expression of the gene (i.e., within a regulatory element). In diploid organisms, a gene is composed of two alleles.
  • mutation refers to a difference in the nucleotide sequence of a given gene or regulatory sequence from the naturally occurring or normal nucleotide sequence, e.g., a single nucleotide alteration (deletion, insertion, substitution), or a deletion, insertion, or substitution of a number of nucleotides.
  • mutation also includes chromosomal rearrangements.
  • Insertid mutation as used herein means a mutation introduced by chemical or physical mutagens.
  • archive refers to a collection of samples from different sources stored under conditions suitable to preserve the integrity of the material.
  • the collection can encompass nucleic acids of tissues, tissue or cell samples of a non-human organism, including somatic cells or clonal somatic cell lines thereof.
  • non-transgenic refers to an organism that does not carry in its genome a heterologous nucleic acid segment that is artificial or derived from (an)other organism(s) in respect of its sequence.
  • SCNT sematic cell nuclear transfer
  • enucleated oocytes typically prepared by removal of the nucleus from an unfertilized oocyte, and the introduction of the nucleus of a somatic cell into the enucleated oocyte to form a 1 cell-stage embryo.
  • introduction may be achieved, e.g., via fusion of a somatic donor cell with an enucleated recipient oocyte, or via transfer by microinjection of an isolated somatic cell nucleus into an enucleated recipient oocyte.
  • SCNT may further comprise an additional step of transferring the pronucleus, which is generated by the initial step of transferring the nucleus of a somatic cell into the enucleated oocyte, into a second or further enucleated oocytes.
  • the second oocyte or the further oocytes are preferably oocytes obtained by enucleation of fertilized oocytes.
  • the transfer of the pronucleus occurs into said further enucleated oocytes, the transfer is performed consecutively, i.e., the pronucleus is transferred from the first to a second enucleated oocyte, then from the second to a third enucleated oocyte, then optionally from the third to a fourth enucleated oocyte, and so on, depending on how many transfer steps are intended.
  • the transfer of the pronucleus into a second or further enucleated oocyte may be useful to improve synchronisation of the donor nuclei with the recipient oocyte cytoplasm.
  • the serial transfer mentioned above in connection with SCNT may also include the transfer of a nucleus into which a pronucleus has developed, into a second oocyte, or into further enucleated oocytes.
  • the term "cell clone” or “cellular clone” as used herein refers to a cell population derived from a single cell isolated, e.g., from a somatic cell population of a non-human organism. This single cell is expanded in tissue culture, typically under low density conditions.
  • the term “cell clone” or “cellular clone” as used herein is intended to encompass clones formed by two cells derived from a single cell via a mitotic cell division. Typically, however, a "cell clone” or “cellular clone” will be formed by more than two cells derived from a single cell via mitotic cell divisions.
  • clonal cell line refers to a cell population, which represents, or is derived from, a cellular clone, e.g., from a somatic cellular clone of a non- human organism. This cellular clone is expanded by one or more cell divisions in tissue culture, thus generating a clonal cell line. A clonal cell line is capable of being further expanded via further cell divisions in culture, or of being stored under appropriate conditions and subsequently further expanded via further cell divisions in culture.
  • clonal cell refers to an individual cell derived from a cell clone or a clonal cell line.
  • DNA archive refers to nucleic acids, isolated, e.g., from one or several cells of a cell clone or clonal cell line, and stored as a frozen repository.
  • cell passage refers to the process of transferring cells stored or maintained in tissue culture from one storage or culture compartment (e.g., a tissue culture flask, a Petri dish, or a multi-well tissue culture plate) to another.
  • Cell passage or passaging may involve individualization of the cells, e.g., via treatment with trypsin, particularly in the case of cells that adhere to the substrate they are cultured on, followed, e.g., by subsequent pipetting of the cells.
  • the cells, or an aliquot or several aliquots thereof are seeded into one or several new compartments such as a fresh flask or a fresh Petri dish, typically at a cell density lower than the cell density displayed by the cell culture in the previous compartment.
  • new compartments such as a fresh flask or a fresh Petri dish
  • the term "morula” as used herein refers to a developmental stage of an embryo, where it consists of approx. 4 to 16 cells.
  • blastocyst refers to a developmental stage of an embryo, where it consists of 16 to approx. 300 cells. It is covered in a layer of trophoblast cells, which eventually form the placenta.
  • the method of the invention involves the use of a somatic cell derived from a non-transgenic or a transgenic non-human animal, which may be either an adult animal or an animal in an embryonic stage.
  • the somatic cell may be derived from a transgenic non-human animal which has a selected phenotype compared to the wild-type animal and is intended to be subjected to further mutagenesis to alter, e.g., improve said phenotype.
  • the method of the invention is, of course, also valuable for generating mutated non-human animals from somatic cells derived from wild-type non- human animals. In both scenarios, the method of the invention inter alia offers the possibility to provide disease models useful for developing novel therapeutic approaches, or animals with improved traits that are useful for farming purposes.
  • the somatic cell used in the context of the method described and claimed herein is derived from the non-human animal in the sense that it has been isolated directly from the non-human animal. Also suitable and encompassed by this concept is, however, a somatic cell that has been cultured and/or stored for a longer period of time -after its actual isolation from said non-human animal. Furthermore, it may be a cell from a cell line, which is derived, e.g., by cell passaging, optionally including genetic manipulation, from a somatic cell that was initially isolated from any of the non-human animals to be used as a source of somatic cells in accordance with the invention.
  • the method of the invention comprises the treatment of the somatic cell with a mutagen, e.g., a chemical or physical mutagen, preferably ENU. Additionally, the method comprises the expansion of the mutagenized (e.g. ENU treated) somatic cell into a cell clone of at least 2 cells or a clonal cell line. This is preferably done by isolating the somatic cell as a single cell from a plurality of cells treated with said mutagen and subsequently expanding said single somatic cell to provide said cell clone or clonal cell line.
  • a mutagen e.g., a chemical or physical mutagen, preferably ENU.
  • the method comprises the expansion of the mutagenized (e.g. ENU treated) somatic cell into a cell clone of at least 2 cells or a clonal cell line. This is preferably done by isolating the somatic cell as a single cell from a plurality of cells treated with said mutagen and subsequently expanding said single somatic cell to
  • a 1 cell-stage or multicell- stage embryo is formed by a method comprising introducing the nucleus of a cell of the cell clone or clonal cell line into an oocyte, which has previously been enucleated, e.g., via micro-manipulation.
  • preferred enucleated oocytes are those obtained by removal of the nucleus of an unfertilized oocyte.
  • the introduction of the nucleus into the enucleated oocyte may be followed by transferring, or consecutively transferring the pronucleus (or nucleus) formed in the course of such initial introduction into a second enucleated oocyte, or a second and yet further enucleated oocytes, and allowing the second or further recipient oocyte to form a 1 cell-stage or multicell-stage embryo.
  • the 1 cell-stage or multicell-stage embryos formed in the course of the methods of the invention are preferably embryos capable of producing (or maturing into) a mutated non-human animal upon the implementation of suitable measures, e.g., the application of suitable culture conditions and the reimplantation into suitable foster mothers.
  • the introduction of the nucleus of the somatic cell into the enucleated oocyte may be conveniently performed by fusing said cell with the enucleated oocyte. It is, however, also possible, e.g., to introduce the nucleus into the enucleated oocyte by direct transfer from the somatic cell into the enucleated oocyte via micro-injection.
  • the method of the invention may comprise generating a plurality of cell clones or clonal cell lines from a plurality of somatic cells derived from a non-human animal. It will also be appreciated that the method may further comprise introducing the nuclei of a plurality of such cells (either derived from a single cell clone or clonal cell line, or from a plurality of cell clones or clonal cell lines obtained as described herein) into enucleated oocytes, and in case subsequent pronucleus transfer is involved, transferring a plurality of the resulting pronuclei into second or further enucleated embryos.
  • a plurality of such cells either derived from a single cell clone or clonal cell line, or from a plurality of cell clones or clonal cell lines obtained as described herein
  • the method of the invention comprises the isolation of one or more cells of the cell clone or clonal cell line generated in accordance with the method of the invention after the mutagenesis step.
  • the cells may be isolated prior to, or after the step of introducing the nucleus of a cell of said cell clone or clonal cell line into an enucleated oocyte.
  • a nucleic acid sample is prepared from said one or more isolated cells, which in turn is then screened for the presence of a mutation in a gene of interest.
  • the mutation may be assigned to the corresponding cell clone or clonal cells line from which the cell or cells that served as the source for the nucleic acid sample were derived.
  • the corresponding cell clone or clonal cells line from which the cell or cells that served as the source for the nucleic acid sample were derived.
  • the non-human animal generated from the implanted embryo and carrying the mutation in the gene of interest may be further bread to produce a plurality of offspring generations carrying said mutation.
  • the resulting non-human animal as described herein is non-transgenic.
  • said non-human animal is a vertebrate, e.g., a mammal, a fish, or a bird.
  • said mammal is a mammal selected from the group of mouse, rat, hamster, rabbit, cattle, pig, guinea pig, sheep, goat, horse, camel, dog, cat, monkey, e.g., rhesus macaque, baboon, orang-utan, and chimpanzee.
  • Said fish is preferably selected from the group of fish consisting of salmon, trout, tilapia, carp, catfish, medaka, zebrafish, loaches, goldfish, and pikes.
  • Said bird is preferably selected from the group of poultry, most preferably chicken, duck, turkey, and pigeon, and goose and Japanese quail.
  • Another embodiment of the invention is an archive comprising nucleic acid samples isolated from the above-mentioned one or more somatic cells.
  • a further embodiment of the invention is an archive comprising cells of cell clones or clonal cell lines obtained or obtainable as described herein.
  • the cells in the archive may, for example, be frozen (“frozen archive”) or kept under culturing conditions allowing further expansion (“short-term archive”).
  • the methods of the invention encompass mutagenesis of somatic cells, preferably in vitro. Suitable mutations and mutagens are described below.
  • Mutations in the DNA may comprise large lesion mutations, e.g., chromosomal breaks, rearrangements, and large insertions or deletions (in the order of kilobases); small lesion mutations, e.g., cytogenetically visible deletions within a chromosome; and/or subtle mutations, e.g., point mutations, such as conservative or non- conservative substitutions, insertions, and small deletions (in the order of several-tens of bases).
  • large lesion mutations e.g., chromosomal breaks, rearrangements, and large insertions or deletions (in the order of kilobases)
  • small lesion mutations e.g., cytogenetically visible deletions within a chromosome
  • subtle mutations e.g., point mutations, such as conservative or non- conservative substitutions, insertions, and small deletions (in the order of several-tens of bases).
  • mutations are preferred in the present invention. Also preferred are substitution mutations, e.g., non-conservative substitutions. Moreover, mutations that do not result in the complete deletion of the gene of interest are preferred, e.g., mutations within the gene or its regulatory sequences.
  • Chemical mutagens may be classified by the chemical modification, which they induce, e.g., alkylation, cross-linking, intercalation, etc.
  • Useful chemical mutagens according to the invention comprise N-ethyl-N- nitrosourea (ENU), Methylnitrosourea (MNU), Procarbazine hydrochloride (PRC), Triethylene melamine (TEM), Acrylamide monomer (AA), Chlorambucil (CHL), Melphalan (MLP), Cyclophosphamide (CRP), Diethyl sulphate (DES), Ethyl methane sulphonate (EMS), Methyl methane sulphonate (MMS), 6-mercaptopurine (6MP), Mitomycin-C (MMC), Procarbazine (PRC), N-methyl-N-nitro-N-nitrosoguanidine (MNNG), N-nitrosodiethylamine (NDEA) 5 Isopropyl methane sulphonate (iPMS), 3 H 2 O, Urethane (UR), Bleomycine, Nitrogen Mustard, Vincristine, Dimeth
  • the chemical mutagens mainly cause single nucleotide alterations.
  • ENU mainly causes adenosine to thymine or thymine to adenosine base changes, these changes representing roughly 45% of all base changes examined in the mouse germ line upon application of ENU (Noverskoe et al., 2000).
  • the induction of mutations with chemical mutagens is dependent on several parameters, e.g., the type, dose, and the mode of delivery of the mutagen or the frequency or type of mutations.
  • the skilled person will be readily able to adjust the mutagenesis conditions for a given mutagen to the desired degree of mutation induction.
  • ENU is a particularly preferred chemical mutagen of the present invention.
  • ENU offers the opportunity of obtaining a very large number of mutations in vivo, which gives tremendous power to ENU mutagenesis.
  • mice it requires 1000 offspring (Gl mice) from a mating of ENU- mutagenized males to wild type females, to obtain one-fold statistical recessive mutation coverage of all mouse genes, which are approximately 30,000 to 35,000 genes (Hitotsumachi et al., 1985). This indicates the presence of 30-35 recessive mutations in each Gl mouse, which equals 1.5 to 1.8 mutations per chromosome.
  • a preferred mutation load of the Gl non- human animal is about 0.2 to 5, about 0.5 to 4, about 1 to 3, about 1.5 to 2, and about 1.5 to 1.8 mutations per chromosome.
  • Another preferred mutation load of the present invention is about one mutation per chromosome.
  • the presence of multiple recessive mutations in each Gl animal frequently led to the concern that a desired phenotype, based on the identified mutation in a gene of interest, may be confounded by the interaction of several mutations. This scenario is rather unlikely, however, based on the following example provided for a Gl mouse.
  • cM centiMorgan
  • 30-35 ENU-induced recessive mutations yield an average genetic distance between two functionally relevant mutations of 42-48 cM, indicating that adjacent mutations are almost certain to segregate in the next generation.
  • Physical mutagens e.g., radiation mutagenesis via gamma-radiation, X-ray radiation, or neutrons, may also be used in accordance with the invention.
  • radiation mutagenesis causes DNA breakage. Due to DNA repair mechanisms, these DNA breaks may lead to regions on the DNA with large lesions, rearrangements, or deletions.
  • mutations induced by UV-light which is likewise a suitable mutagen in connection with the present invention, are largely single nucleotide alterations. UV-light does not penetrate the animal but is generally useful for inducing mutations in cells in culture, e.g., somatic cells as in the present invention.
  • a cell sample e.g., one or more cells of a cell clone or a somatic clonal cell line of the invention, optionally previously stored in a "frozen archive” or in a “short-term archive” under conditions allowing (subsequent) cell expansion, is isolated.
  • the one or more cells are then preferably processed for nucleic acid sample preparation, which may then, e.g., be subjected to Primer Extension Preamplification (PEP).
  • PEP Primer Extension Preamplification
  • the cell sample e.g. the one or more cells isolated from the cell clone or the somatic clonal cell line, is used to prepare nucleic acid samples.
  • nucleic acid samples may be DNA or RNA, preferably genomic DNA. Since the amount of nucleic acid in a single cell sample may be very limited, the nucleic acid, e.g., the genomic DNA of the tissue sample will preferably be subjected to amplification in order to allow extensive genetic testing.
  • Sermon et al. (1996) and Cheung and Nelson (1996) describe a method of PCR-based amplification of isolated genomic DNA using partially or fully degenerated oligonucleotides, where the genomic DNA is isolated from cell biopsies. Equivalent methods are variations of the above protocols where oligonucleotides in combination with DNA polymerases are used without thermal cycling for the amplification of whole genome DNA like the method described by Dean et al. (2002).
  • the cell sample e.g., the one or more cells isolated from the somatic cell clone or clonal cell line derived from the non-human animal, are cultured in vitro under appropriate conditions in order to allow expansion of such cells, thereby increasing the amount of tissue and nucleic acid derivable therefrom (see, e.g., Example 5).
  • Screening for the presence of a mutation in a gene of interest according to the invention maybe performed, e.g., on a single nucleic acid sample derived from the cell sample as described herein, e.g., derived from one or more cells of a cell clone or somatic clonal cell line from a non-human animal obtained in accordance with the invention.
  • screening for the presence of a mutation in a gene of interest may be performed on a mixture or pool of nucleic acid samples derived from a plurality of the cell samples as described herein.
  • Another embodiment of the methods of the invention includes screening for the presence of a mutation according to the invention in at least two genes of interest. This may be performed on a single nucleic acid sample or pools of nucleic acid samples as described above.
  • a mutation in a gene of interest is assigned to a particular phenotype in an individual, e.g., to a disease, after screening for the presence of a mutation in said gene of interest and after generating a non-human animal carrying said mutation and displaying such particular phenotype.
  • the individual is a human.
  • the somatic cell, cell clone or clonal cell line used in accordance with the invention is preferably derived from a mouse; rat; hamster; rabbit; cattle; pig; guinea pig; sheep; goat; horse; camel; dog; cat; monkey, e.g., rhesus macaque, baboon, orang-utan, chimpanzee; salmon; trout; tilapia; carp; catfish; medaka; zebrafish; loaches; goldfish; pikes; poultry, preferably chicken, duck, turkey, goose; pigeon; or Japanese quail.
  • a gene of interest is preferably a gene that is already known from an individual, e.g., a disease gene or an economically valuable gene. This information is then used to screen for a suitably mutated somatic cell clone or clonal cell line of a non-human animal according to the methods of the invention.
  • somatic cell clone or clonal cell line or a plurality of somatic cell clones or clonal cell lines prepared according to the method of the invention are used as a source for one or more cells, on which screening for the presence of a mutation in said gene of interest is performed, hi a preferred embodiment, said individual is a human.
  • Said somatic cell, cell clone, or clonal cell line of a non-human animal is preferably of mouse; rat; hamster; rabbit; cattle; pig; guinea pig; sheep; goat; horse; camel; dog; cat; monkey, e.g., rhesus macaque, baboon, orang-utan, chimpanzee; salmon; trout; tilapia; carp; catfish; medaka; zebrafish; loaches; goldfish; pikes; poultry, preferably chicken, duck, turkey, goose; pigeon; or Japanese quail, hi another preferred embodiment, said individual is a non-human animal that is from the same species as said somatic cell, cell clone, or clonal cell line produced according to the method of the invention.
  • the screening for the presence of a mutation in a gene of interest may be performed by heteroduplex analysis. This analysis is based on detection of a base mismatch or base mismatches in a double-stranded (ds) DNA molecule. Detection can be done either by nondenaturing gel electrophoresis or by using denaturing agents (gradients or constant concentrations) or temperature (gradients or constant temperature) in electrophoretic systems or liquid chromatography. Detection can also be done by chemical cleavage of the mismatch or mismatches using chemical agents as described by Cotton et al. (1988).
  • Detection can further be done by proteins binding to the mismatch with or without subsequent cleavage of the double-stranded (ds) DNA (reviewed in Nollau and Wagener, 1997).
  • Equivalent methods are assays that exploit secondary structures of single stranded DNA or RNA molecules for the electrophoretic separation of nucleic acid strands that exhibit base variations as described by Orita et al. (1989), or assays for allele-specific hybridization to oligonucleotide-coated chips (for a review see Southern, 1996).
  • the amplified nucleic acid sample e.g., the genomic DNA 5 is subject to PCR amplification according to standard methods in the art.
  • Genomic DNA fragments of the gene of interest may be obtained by PCR using BioTherm-DNA- Polymerase (GeneCraft, Germany) according to the manufacturer's protocol.
  • Gene-specific oligonucleotide primers may be designed using a publicly available primer design program (Primer3, www, genome, wo .mit. edu) .
  • dsDNA is electrophoresed through a temporal gradient of increasing temperature (Temperature Gradient Capillary Electrophoresis (TGCE); RevealSystem, SCE9610, by SpectruMedix LLC, State College, PA, USA). Because retardation of dsDNA during electrophoresis is greatest at the temperature of partial denaturation, DNA fragments of the same size can be separated according to their thermodynamic stabilities.
  • TGCE Temporal Gradient Capillary Electrophoresis
  • RevealSystem RevealSystem
  • heteroduplices Base mismatches within dsDNA molecules (heteroduplices) lead to a significant destabilization resulting in significant differences in melting temperatures (T m ) between heteroduplices and perfectly paired dsDNA (homoduplices). Such differences in T m allow the separation of heteroduplices from homoduplices in a temperature gradient electrophoresis and serve as the basis for mutation detection by TGCE (cf. Example 6).
  • SSCP single strand conformation polymorphism
  • fSSCP fluorescent SSCP
  • SSCP Denaturing Gradient Gel Electrophoresis
  • Cleavage of Mismatches Constant Denaturing Capillary Electrophoresis
  • RNAse cleavage Mismatch Repair detection
  • Mismatch Recognition by DNA repair enzyme sequencing by hybridization
  • dot-blots reverse dot blots
  • allele specific PCR Primer-Induced Restriction analysis
  • Oligonucleotide Ligation Direct DNA sequencing; Mini-sequencing; 5' Nuclease Assay; Representational Difference Analysis; or Microarrays, all described or referenced in WO 97/44485.
  • screening methods according to the invention are not limited to the methods specifically described herein. Each method that may be useful in the connection with screening a mutation in a gene of interest may be employed.
  • Storing according to the invention may comprise any form and any duration of maintaining somatic cells or nucleic acids as described herein.
  • Long-term storage comprises storage for, e.g., a week, several weeks, a month, several months, or even a year or several years up to several decades.
  • Short-term storage comprises storage, e.g., for several minutes, hours or days.
  • the cells which are stored in accordance with the invention may, e.g., be one or more cells of a somatic cell clone or clonal cell line, as described herein.
  • cells are preferably kept in a suitable buffer or culture medium.
  • mouse fetal fibroblasts may be appropriately stored in Dulbecco's modified Eagle's medium (DMEM; 50mg/ml penicillin/ streptomycin) at 37°C under 5% CO 2 and >90% humidity in an incubator for several cell passages.
  • DMEM Dulbecco's modified Eagle's medium
  • cells are preferably stored by freezing in a freezing medium, e.g., DMEM containing 20% FCS and 10% DMSO.
  • Certain embodiments of the claimed method also comprise storing of nucleic acids, particularly nucleic acid samples derived from one or more cells of the cell clones or clonal cell lines described herein.
  • such samples are stored prior to being subjected to screening for the presence of a mutation in a gene of interest.
  • they may additionally be stored again for a certain period of time after having been subjected to screening, or both before being and after having been subjected to such screening.
  • Long-term storage of nucleic acids may be conveniently done by freezing the nucleic acids in an appropriate buffer, e.g., TE-buffer (10 mM Tris pH 7.5, 1 mM EDTA), or by lyophilization.
  • Reimplantation comprises the reimplantation or transfer of a mutant embryo at its various developmental stages, e.g. zygotes, morulae, blastocysts.
  • a morula stage embryo can be transferred into the ampulla of an oviduct of a 0.5 days post coitus (dpc) pseudopregnant foster mother, whereas a blastocyst stage embryo is transferred into an uterus horn of a 2.5 dpc pseudopregnant foster mother (see also Example 4).
  • Example 1 ENU Treatment of Non-Human Fetal Fibroblasts
  • Fibroblast cells are prepared from 15.5 days post-coitus (dpc) fetuses derived from murine CD-I x CD-I and CD-I x C57B1/6 breedings.
  • the fetuses are killed by decapitation and sexed by gonadal phentoyping.
  • the internal organs are removed, and the remaining tissue is cut into small pieces (1-2 mm) in preparation for culture.
  • the pieces of tissue are incubated in Dulbecco's modified Eagle's medium (DMEM) (Invitrogen GmbH, Düsseldorf, Germany) containing 0.05% trypsin EDTA (Gibco) for 10 min in a rotator.
  • DMEM Dulbecco's modified Eagle's medium
  • the cell suspension is filtered after adding the same volume of DMEM medium containing 10% fetal calf serum.
  • the filtered cell suspension is seeded into tissue culture dishes at a concentration of 5xlO 5 /ml.
  • the supernatant is removed after Ih at 37°C culturing in an incubator with an atmosphere of 5% CO 2 and fresh DMEM medium is added. Cells adhering to the culture dish are allowed to grow to confluency.
  • ENU is dissolved in Soerenson Buffer, pH 6.0 for preparation of an ENU stock solution.
  • Soerenson buffer 9.078 g of KH 2 PO 4 (Merck KgaA, Darmstadt, Germany), (Stock A) , and 11.976 g Of Na 2 HPO 4 (Merck KgaA, Darmstadt, Germany), (Stock B) is dissolved in each 1000 ml of distilled H 2 O. 121 ml of Stock B solution is added to 879 ml of Stock A solution, mixed by inversion, and autoclaved. 1 g of ENU (Sigma Aldrich Chemie GmbH, Kunststoff, Germany) is dissolved in 200 ml of Soerenson buffer by vigorous shaking for about 10 min. Final concentration is determined photospectrometrically and the ENU stock solution is continuously kept refrigerated. ENU working solutions for in vitro treatment are prepared by mixing PBS with appropiate amounts of the ENU stock solution.
  • fibroblast cells After fibroblast cells reach confluency in cell culture, according to Example 1.1, cells are treated with ENU: DMEM medium is aspirated and the cells are washed one time in phosphate-buffered saline (PBS; Invitrogen GmbH, Düsseldorf, Germany). Cells are then incubated with PBS/ENU (0.01-0.6 mg ENU/ml PBS) for 5-60 min at 37 0 C in an incubator with an atmosphere of 5% CO 2 . After incubation the ENU/PBS solution is replaced with 1 ml of trypsin. After trypsinization cells are suspended in PBS and harvested by centrifugation.
  • PBS phosphate-buffered saline
  • the cell pellet is suspended in 10 ml of DMEM containing 10% fetal calf serum and cells are plated in low density with 2-5 x 10 2 cells per 10 cm (diameter) petri dish to allow individual cells to grow to individual cellular clones.
  • the incubation is performed at 37°C in an incubator with an atmosphere of 5% CO 2 for at least 4h.
  • Single cellular clones are picked and every individual clone is transferred into one well of a 96 well plate for further expansion.
  • each clone is further passaged to each one well of a 24 well plate and incubated at 37°C in an incubator with an atmosphere of 5% CO 2 for further expansion and for generating clonal cell lines.
  • each such clonal cell line is further passaged to one 6 cm (diameter) culture dish each and kept in culture under the conditions described before to further enrich the number of clonal cells of such clonal cell lines.
  • After reaching confluency about half of the clonal cells of each clonal cell line is suspended in medium containing 10% dimethylsulfoxide.
  • These clonal cells are directly frozen in cryotubes to establish a "frozen archive" of mutated fibroblast clonal cell lines.
  • these cells are maintained under culruring conditions to establish a short-term storage archive of mutated fibroblast clonal cell lines (see Example 6).
  • the remaining clonal cells of each clonal cell line are kept under culruring conditions for further 2 to 6 passages before final trypsinization and collection by centrifugation.
  • the cell pellet is suspended in Proteinase K buffer (0.5 M EDTA, 1 M Tris pH 9.5, 30% Sarkosyl, 20% SDS, Proteinase K 50 mg/ml; Sigma Aldrich Chemie GmbH,
  • nucleic acid preparation performed by methods well known in the art.
  • the isolated nucleic acid e.g., genomic DNA
  • TE buffer 10 mM Tris pH 7.5, 1 mM EDTA
  • Nucleic acid of each mutagenized fetal fibroblast clonal cell line is subject to mutation detection in a gene of interest, as described in Example 7.
  • Example 3 Somatic Cell Nuclear Transfer (SCNT) - Serial Nuclear Transfer
  • SCNT Somatic Cell Nuclear Transfer
  • a donor cell arrested at metaphase II is first transferred into an unfertilized enucleated oocyte, and then the resulting pronucleus is again transferred into a fertilized enucleated egg, leading to a 1 cell-stage embryo.
  • This particular SCNT procedure also called serial nuclear transfer
  • clonal cells from the corresponding clonal cell line stored in a "frozen archive” are thawed and cultured for 2h under gentle pipetting in DMEM, supplemented with 10% FCS and 0.4 ⁇ g/ml nocodazole (Sigma Aldrich Chemie GmbH, Kunststoff, Germany), a microtubule polymerization inhibitor, which induces metaphase arrest.
  • DMEM fetal fibroblast clonal cell line stored in a "frozen archive”
  • FCS and 0.4 ⁇ g/ml nocodazole Sigma Aldrich Chemie GmbH, Kunststoff, Germany
  • a microtubule polymerization inhibitor which induces metaphase arrest.
  • cells are collected and an aliquot of these cells is subjected to staining with Hoechst 33258 (10 ⁇ g/ml).
  • Metaphase II arrest is observable after staining by the absence of a nuclear membrane and by chromosome condensation.
  • several cells arrested in metaphase II are isolated using an O
  • the oocyte donors and zygote donors are female B6CBF1 hybrid mice (C57BL/6 x CBA), superovulated with intraperitoneal injections of 5
  • eCG Pulex; Sankyo Ltd., Tokyo, Japan
  • hCG Pierogen; Sankyo
  • Oocytes at metaphase II are released from the oviduct 14 h after hCG.
  • Oocyte donor females of the B6CBF1 hybrid strain are sacrificed 14 hours after Puberogen injection.
  • each mouse abdomen is opened with surgical scissors from caudal to cranial.
  • the upper end of one uterine horn is grasped with fine forceps and the uterus, oviduct, ovary and the fad pad are removed.
  • a hole is poked with the tip of a fine forceps into the membrane close to the oviduct, for further separation of the whole reproductive tract from the body wall.
  • the oviduct After stretching the whole reproductive tract and cutting between the oviduct and the ovary, the oviduct is finally removed. The whole procedure is repeated at the other uterine horn. Oviducts and the attached segments of the uterus are transferred into a pre-warmed culture dish, filled with lightweight paraffin oil (embryo tested; Sigma Aldrich Chemie GmbH, Kunststoff, Germany). Oviducts from all the female mice are collected in one culture dish. Collected oviducts are transferred to a culture dish filled with 400 ⁇ l of M2 medium, the oviducts still being surrounded with oil. Under oil, the swollen ampullae are opened with the closed tip of fine forceps and the oocyte-cumulus complexes are expelled into the oil.
  • a pre-warmed culture dish filled with lightweight paraffin oil (embryo tested; Sigma Aldrich Chemie GmbH, Kunststoff, Germany). Oviducts from all the female mice are collected in one culture dish. Collected oviducts are transferred to a culture dish filled
  • Oocytes are placed in a micromanipulator chamber in a small drop of M2 medium (see in Quinn et al., 1982) containing cytochalasin B (5 mg/ml).
  • M2 medium see in Quinn et al., 1982
  • cytochalasin B 5 mg/ml
  • oocytes with properly arrested metaphase II chromosomes are selected. Under microscopic examination, the zona pellucidae of selected oocytes is slit with a glass needle along 10-20% of its circumference at a position close to the metaphase II chromosomes and the spindle located in the cortex of the oocyte. All metaphase II chromosomes are removed using an enucleation pipette, which displays an unsharphened beveled tip.
  • Fertilized one-cell stage embryos are generated by in vitro fertilization using oocytes and sperm cells of B6CBF1 hybrid mice.
  • High quality mature sperms i.e., spermatozoa
  • B6CBF1 males which have not been mated for at least 10 days.
  • a male mouse is sacrificed by cervical dislocation, followed by immediate dissection of cauda epididymis and vas deferens. (Marschall et al., 1999).
  • testis structures After removal of fat tissue and blood vessels, both testis structures are washed briefly in 0.9% NaCl at room temperature, transferred into 500 ⁇ l of HTF fertilization medium (Quinn et al., 1985), and cut into 5 pieces allowing the sperms to flush out. Incubation in HTF medium is for 20 min. at 37°C in an incubator with an atmosphere of 5% CO 2 in air.
  • the oocyte cumulus complexes are transferred into fertilization dishes containing capacitated spermatozoa.
  • Oocytes and spermatozoa are incubated for 4 to 6 hours in an incubator (37°C, 5% CO 2 in air), followed by removing from the incubator and subsequent washing of the oocytes of each fertilization dish (with the help of the silicon tube, mouth piece and the glass pipettes) for three times in a separate dish filled with 50 ⁇ l drops of KSOM medium (see in Lawitts and Biggers, 1991).
  • KSOM-medium Washing in drops of KSOM-medium is for removal of dead sperms and residues of the cumulus complex. After washing, the prepared oocytes are transferred into a fresh culture dish filled with 200 ⁇ l of KSOM- medium and are covered with equilibrated lightweight paraffin oil (equilibrated over night with KSOM-medium. Enucleation of the resulting one-cell stage embryos is following, according to the method described in Example 3.3.
  • Embryos are generated by serial nuclear transfer using standard micromanipulation procedures described by Kwon and Kono, 1991. All micromanipulations are performed in a micromanipulation chamber in M2 medium (Quinn et al., 1982), containing 5 ⁇ g/ml cytochalasin B and 0.4 ⁇ g/ml nocozadole.
  • the Sendai virus 2700 used is a virus inactivated with ⁇ -propiolactone (McGrath and Solter, 1983).
  • An assigned metaphase II arrested mutant fibroblast cell is introduced together with a drop of inactivated Sendai virus 2700 (virus concentration: 2000-3000 hemagglutinating activity units/ml) into the perivitelline space of an enucleated oocyte, generated as described in Example 3.3.
  • the virus contacts the oocyte membrane and facilitates the fusion of the donor cell with the recipient cell (McGrath and Solter, 1983).
  • Oocytes that successfully fuse with a donor cell are cultured for 2h in an atmosphere of 5% CO 2 , 5% O 2 and 90% N 2 at 37 0 C, and are then artificially activated with 10 mM strontium for 6h, followed by transfer into CZB medium (see in Chatot et al., 1990). After 9 to 12h of incubation the pronucleus of such a constituted egg is again transferred to a previously enucleated fertilized 1-cell embryo obtained by in vitro fertilization, as described in Example 3.4.
  • An embryo resulting from pronucleus transfer is cultured in CZB medium containing 5.56 mM glucose in an atmosphere of 5% CO 2 , 5% O 2 and 90% N 2 at 37°C.
  • a blastocyst obtained is transferred to the uterine horn of a female on day 3 of pseudopregnancy (2.5 dpc), as described in Example 4.
  • Pseudo-pregnancy is generated by mating mouse CDl females (8-10 weeks of age, at a body weight of approximately 30 g) to vasectomized or genetically sterile males. It is recommended to mate at least 10 females per one scheduled embryo transfer, with each two females mated over night to one vasectomized male. A vaginal plug is visible the next morning after coitus. A female of 2.5 days post coitus (2.5 dpc), which is day 3 of pseudopregnancy is used for uterus transfer. To archive successful embryo transfer in general, it is necessary to transfer more than one embryo into the uterus of one pseudo-pregnant female mouse.
  • Embryos from Example 3.5 are selected for embryo transfer, washed two times in M2 Medium and subsequently stored in one drop of M2 medium covered with lightweight paraffin oil (embryo tested; Sigma Aldrich Chemie GmbH, Kunststoff, Germany) on a warming plate at 37°C.
  • the pseudo-pregnant female mice are anaesthetized by intra-peritoneal injection of 0.25 ml anesthetic (Rompun 2%/Ketamin
  • the mouse is placed onto the lid of a 140 mm (diameter) culture dish, and her back is disinfected with 70% alcohol.
  • a first small transverse incision is made to the skin (approx. 1 cm to the left side of the spinal cord, at the level of the last rib), the peritoneum is opened with fine scissors, the fad pad is picked up, and ovary, oviduct and the uterus horn are pulled out with fine forceps.
  • This tissue complex is fixed on the fad pad with the help of a bullock clamp, located on the back of the mouse.
  • the mouse is placed on the stage of a light microscope (head on the left side, tail to the right side).
  • the top of the uterus is gently lifted with blunt fine forceps and a small hole is made into the uterus, a few millimeters down from the utero-tubal junction, using a 26 gauge needle.
  • the prepared transfer pipette containing the blastocyst embryos including an embryo carrying a mutation in a gene of interest and several wildtype embryos, is inserted into the hole and the embryos are expelled into the uterus.
  • the bullock clamp is undipped and ovary and oviduct are carefully returned into the abdomen.
  • the body wall is closed with one stitch, the skin is closed with a wound clip. All steps are repeated for the right side located oviduct of the same mouse. After surgery the mouse is left undisturbed on a warming plate for approx. 10 min. until waking it up.
  • mice are sacrified at 19.5 days of gestation and pubs are recovered from the uterus. Recovering mutant and wildtype mice are visibly distinguishable by their different coat colors.
  • Primer Extension Preamplification is used to amplify low amounts of genomic DNA isolated from e.g. a tissue culture sample or from a single cell biopsy sample (see in Sermon et al. (1996)
  • sample material is resuspended in 5 ⁇ l alkaline lysis buffer (200 niM KOH, 50 mM dithiothreitol), heated to 65°C for 10 min. and neutralized by adding 5 ⁇ l neutralization buffer (900 mM Tris-HCl, pH 8.3; 300 mM KCl, 200 mM HCl).
  • 5 ⁇ l of a 400 ⁇ M solution of random 15-base oligonucleotides are added (MWG Biotech AG, Ebersberg, Germany).
  • any one of the four bases adenine, cytosine, guanine, and thymine could be present at each position.
  • PCR buffer 25 mM MgCl 2 /gelatin (1 mg/ml)/100 mM Tris- HCl, pH 8.3
  • 3 ⁇ l dNTP mixture each 2 mM
  • 1 ⁇ l Taq polymerase GeneCraft, Germany; 5 units
  • the volume is raised to 60 ⁇ l with sterile water and 50 primer extension cycles are carried out in a MJ Research (Cambridge, MA) thermocycler. Each cycle consists of 1 min. denaturation at 94°C, 2 min.
  • Example 6 In Vitro Expansion of Mutagenized Cells
  • Cells in culture as described in example 2 can be stored for short-term storage as living cells. Every individual cell clone is maintained on a 6 cm dish and the medium (DMEM 10 % FCS) of the cells is changed on a daily basis. Every third day the medium is removed, the cells are washed with PBS (phosphate-buffered saline (PBS; Invitrogen GmbH, Düsseldorf, Germany) and subsequently trypsinized. Trypsinized cells are than resuspended in 4 ml medium (DMEM 10 FCS) and 1 ml medium cell suspension is added to a fresh 6 cm dish containing 4 ml medium.
  • PBS phosphate-buffered saline
  • Example 7 Myostatin Mutation Detection by Heteroduplex Analysis Using Temperature Gradient Capillary Electrophoresis (TGCE)
  • genomic DNA is used to PCR amplify DNA fragments of the myostatin gene with myostatin-specific PCR primers.
  • the following murine primer pairs Mst-1 and Mst-2, Mst-3 and Mst-4, and Mst-5 and Mst-6 were designed for the amplification of the individual exons in PCR amplification reactions:
  • genomic DNA is either directly used for PCR; or previously enriched by Primer Extension Pre- amplification (see Example 5) or via previous in vitro culturing for sample material enrichment (see Example 6), or both.
  • each cycle Upon initial denaturation at 94°C for 3 min. each cycle consists of a 30 sec denaturation step at 94°C, a 30 sec annealing step at 56°C and a 45 sec synthesis step at 72°C. 40 cycles are carried out in a MJ Research (Cambridge, MA) thermocycler.
  • a typical temperature profile for denaturation/renaturation is:
  • TGCE TGCE
  • Electrophoresis time 60 min.
  • the applied temperature gradient during electrophoresis depends on the base composition (G+C content) of the analyzed fragment and ranges from 55°C to 7O 0 C.
  • PCR products amplified with primers specific for the myostatin gene are purified using the QIAquick PCR Purification Kit (Qiagen, Hilden, Germany) according to the manufacturer's protocol. PCR products are sequenced using forward/reverse PCR primers and the "Big Dye" thermal cycle sequencing Kit (ABI PRISM, Applied Biosystems, Foster City, CA 5 U.S.A.). The reaction products are analyzed on an ABI 3700 DNA sequencing device.
  • sequences are edited manually and different sequence fragments are assembled into one contiguous myostatin sequence using the software Sequencer version 4.0.5. (Gene Codes Corp., Ann Arbor, MI, U.S.A.).
  • the myostatin gene of an ENU-treated heterozygous somatic cell and of a wild-type somatic cell is sequenced.
  • the sequencing results are used to identify mutations by comparing the sequencing results from somatic cells carrying the ENU mutation with wild-type somatic cells.
  • Cibelli JB Stice SL, Golueke PJ, Kane JJ, Jerry J, Blackwell C, Ponce de Leon FA, Robl JM, 1998. Cloned transgenic calves produced from nonquiescent fetal fibroblasts. Science, May 22;280(5367): 1256-8.
  • Polejaeva IA Chen SH, Vaught TD, Page RL, Mullins J, Ball S, Dai Y, Boone J, Walker S, Ayares DL, Colman A, Campbell KH, 2000. Cloned pigs produced by nuclear transfer from adult somatic cells. Nature Sept.7; 407 (6800):27; 29-30.

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Abstract

L'invention concerne entre autres un procédé de fourniture d'embryon capable de donner un animal non humain sans mutation, par traitement de cellule somatique dérivée d'animal non humain avec un mutagène in vitro. L'invention concerne également des animaux non humains à mutation résultant de la mise en oeuvre du procédé.
PCT/EP2005/009003 2004-08-20 2005-08-19 Procedes pour la production de betail ameliore et modeles de maladie pour la recherche therapeutique WO2006018316A1 (fr)

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CN104789523A (zh) * 2015-05-18 2015-07-22 河南省格林金斯生物科技有限公司 简便、高效、低耗的猪***体外成熟克隆培育方法
CN111690613A (zh) * 2020-07-07 2020-09-22 中国科学院水生生物研究所 一株吉富罗非鱼脑神经细胞系、转染方法、培养方法及其应用

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WO1999067361A1 (fr) * 1998-06-24 1999-12-29 Case Western Reserve University Serie allelique de modifications genomiques dans des cellules
WO2000025578A2 (fr) * 1999-04-26 2000-05-11 Trustees Of Tufts College Procedes de clonage des animaux
WO2001049106A2 (fr) * 2000-01-04 2001-07-12 University Of Connecticut Procede de clonage d'animaux avec modifications genetiques ciblees, par transfert de noyaux cellulaires somatiques males ou femelles a culture a long terme, comprenant des modifications genetiques provoquees artificiellement, dans des cellules receveuses enuclees
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104789523A (zh) * 2015-05-18 2015-07-22 河南省格林金斯生物科技有限公司 简便、高效、低耗的猪***体外成熟克隆培育方法
CN111690613A (zh) * 2020-07-07 2020-09-22 中国科学院水生生物研究所 一株吉富罗非鱼脑神经细胞系、转染方法、培养方法及其应用
CN111690613B (zh) * 2020-07-07 2022-02-22 中国科学院水生生物研究所 一株吉富罗非鱼脑神经细胞系、转染方法、培养方法及其应用

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