@misc{oai:ir.soken.ac.jp:00001143,
 author = {牧野, 初音 and マキノ, ハツネ and MAKINO, Hatsune},
 month = {2016-02-17, 2016-02-17},
 note = {The mature brain is composed of huge number of diversified and highly organized neural cells. Since majority of these cells are fully differentiated and do not divide, it has been difficult to analyze the genomic infotmation at single cell level. Recent papers have postulated a hypothesis by using nuclear transfer technique that nuclei of neural cells in advanced stages of differentiation lose their developmental totipotency through neurogenesis.<br />　To examine the developmental totipotency in the nuclei of neural cells through their development, she attempted to transfer differentiated neural cell nuclei (DNn) derived from mouse cerebral cortex at postnatal day 0-4 (P0-P4) to unfertilized oocytes without nuclei for generating cloned mice (DNnt mice). When she used NeuN-positive neurons as donor nuclei for mouse cloning, no normal pups were obtained. The DNnt fetuses carried morphological failures and abnormal localization of differentiated neurons. These data supported that nuclei of the differentiated neurons do not have enough information to produce normal neuronal tissues again.<br />　To further examine the developmental totipotency of nuclei of differentiated neurons, she produced aggregation chimeras between DNnt embryos and wild-type embryos. To establish the condition for producing chimeras with the DNnt embryos, she introduced LacZ-positive transgenic mice for getting donor cell nuclei and the technique for cryopreserving embryos. Two chimeras and several chimeric fetuses with DNnt cells were obtained from 73 chimeric embryos. One adult chimeric mouse had agouti coat and the other chimeric pup had LacZ-positive DNnt cells in the proximal renal tubules of the kidney. However, no LacZ-stained cells were observed in the brain of this animal. In the chimeric fetuses, DNnt cells could develop into apparently normal non-neural cells but showed cell-autonomous abnormalities in the neural tissues. These data strongly support that nuclei of the differentiated neurons do not have enough information to differentiate to normal neuronal cells.<br />　To further characterize the nuclear information of differentiated neurons, she tried to establish ES cell lines from blastcysts cloned with nuclei of NeuN-positive neurons in the male cerebral cortex at P0-P3 (DNntES cell lines). She succeeded in generating novel three ES cell lines from these blastcysts and 12 mutant DNntES lines expressing GFP reporter gene for identification of DNnt ES cells in tissues of the chimeras. In the chimeric mice obtained with these DNntES cell lines, cells derived from the DNntES cells differentiated to most tissues including germ cells but not to the brains. In the chimeric fetuses, the DNntES cells had abnormal distribution in their neural tubes. The GFP-positive cells contributed to the neural tubes but did not express markers for either differentiated neurons or neural stem cells. These data indicate that nuclei of the differentiated neurons could not regain enough information to differentiate to normal neuronal cells even after reverting back to ES cell. Interestingly, the lost information for developing neural cells did not influence development of germline cells.<br />　In conclusion, the nuclei of the NeuN-positive neurons in the early postnatal mouse cerebral cortex did not have enough information for developing neural cells again. The lost information in the neural cell nuclei seems to be necessary for developing normal neural cells and could not be rescued in the DNntES cells. Thus, these ES cell lines will be powerful tools to explore the converted nuclear information in the processes of the neural cell differentiation., 総研大甲第779号},
 title = {Analysis for the information of neural cell nuclei in the postnatal cerebral cortex using mouse cloning technique},
 year = {}
}