• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.7-8
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• 2003

Since it was first reported in 1997, somatic cell cloning has been demonstrated in several other mammalian species. On the mouse, it can be cloned from embryonic stem (ES) cells, fetus-derived cells, and adult-derived cells, both male and female. While cloning efficiencies range from 0 to 20%, rates of just 1-2% are typical (i.e. one or two live offspring per one hundred initial embryos). Recently, abnormalities in mice cloned from somatic cells have been reported, such as abnormal gene expression in embryo (Boiani et al., 2001, Bortvin et al., 2003), abnormal placenta (Wakayama and Yanagimachi 1999), obesity (Tamashiro et ai, 2000, 2002) or early death (Ogonuki et al., 2002). Such abnormalities notwithstanding, success in generating cloned offspring has opened new avenues of investigation and provides a valuable tool that basic research scientists have employed to study complex processes such as genomic reprogramming, imprinting and embryonic development. On the other hand, mouse ES cell lines can also be generated from adult somatic cells via nuclear transfer. These 'ntES cells' are capable of differentiation into an extensive variety of cell types in vitro, as well assperm and oocytes in vivo. Interestingly, the establish rate of ntES cell line from cloned blastocyst is much higher than the success rate of cloned mouse. It is also possible to make cloned mice from ntES cell nuclei as donor, but this serial nuclear transfer method could not improved the cloning efficiency. Might be ntES cell has both character between ES cell and somatic cell. A number of potential agricultural and clinical applications are also are being explored, including the reproductive cloning of farm animals and therapeutic cloning for human cell, tissue, and organ replacement. This talk seeks to describe both the relationship between nucleus donor cell type and cloning success rate, and methods for establishing ntES cell lines. (중략)

• Development and Reproduction
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• v.14 no.4
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• pp.253-259
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• 2010

DNA methylation is one of the major epigenetic regulations of gene expression. The DNA methylation patterns are dramatically changed during gametogenesis and embryogenesis, and especially, it has been known that embryonic stem cells show a distinct methylation pattern. In this study, we examined the methylation patterns of imprinting genes, H19, Igf2r, and Snrpn, in stem cells induced from fertilized embryo (fES) and somatic cell nuclear transferred embryo (ntES). The methylation pattern of H19 gene in both fES and ntES were similar. However, the methylation patterns of Igf2r and Snrpn in ntES (hypermethylated) were slightly different from fES cells.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.2
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• pp.168-173
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• 2004

The ability of frozen-thawed fetal skin was examined to generate viable cell lines for nuclear transfer. Fetal skin frozen at -20$-20^{\circ}C$, $-30^{\circ}C$ or $-80^{\circ}C$ in the presence of 5% DMSO used as tissue explants to generate somatic cells. The resultant confluent cells were then used as donors for nuclear transfer (NT). Of the bovine NT embryos reconstracted from the somatic cells, 62.3%, 76.6% to 65% showed cleavage 70.5%, 81.9% to 78.5% reached the stage of morula formation and 39.7%, 43.2% or 47.6% reached the blastocyst stage. There was no significant difference in development when the NT embryos were compared with those reconstracted from fresh somatic cell derieved skin tissues (72%, 75.3%, and 45.2%, for cleavage, and development to morula and blastocyst stage, respectively). NT embryos were then placed in a portable $CO_2$ incubator and carried to China from Japan by air. After reaching to farm, two NT embryos were transferred to each of 5 recipients. We obtained 2 NT calves which birth weights is 30kg and 36kg female, and gestation periods is 281 and 284 days, respectively. There were no observation any abnormality from those calves. The results indicated that cell lines derieved from bovine fetal skin cryopreserved by a simple method could be used as donors in nuclear transfer using the portable $CO_2$ incubator.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2006.10a
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• pp.57-57
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• 2006

• Development and Reproduction
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• v.12 no.1
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• pp.1-8
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• 2008

Specific protocols to increase the differentiation of neuronal cells from embryonic stem (ES) cells have been well established, such as retinoic acid induction and lineage selection of neuronal cells. For the neuropathological studies, ES-derived neurons (ES neurons) must show normal physiological characteristics related to cell death and survival and should be maintained in vitro for a sufficient time to show insults-specific cell death without spontaneous death. When mouse ES cells were plated onto astrocytes monolayer after retinoic acid induction, most ES cells differentiated into neuronal cells, which were confirmed by the presence of specific neuronal markers, and the cultures were viable for at least four weeks. When these cultures were examined for vulnerability to glutamate excitotoxicity, ES neurons were vulnerable to excitotoxic insults mediated by agonist-specific receptors. The vulnerability to excitotoxic death increased with developmental age of ES neurons in vitro. Specific receptors for Neurotrophin and GDNF family ligands were present in ES neurons. GDNF and NT-3 could modulate the survival and excitotoxic vulnerability of ES neurons. The vulnerability and resistance to toxic insults, which are essential requirements of model culture systems for neuropathological studies, make ES neurons to a useful model culture system. Especially ES cell are highly amenable to genetic modification unlikely to primary neuronal cells, which will give us a chance to answer more complicated neurophysiological questions. Recently there was an outstanding attempt to explore the cellular toxicity using human ES cells (Schrattenholz & Klemm, 2007) and it suggested that ES cells could be a new model system for neurophysiological studies soon and go further a large-scale screening system for pharmacological compounds in the future.