KEGG(Kyoto Encyclopedia of Genes and Genomes)〔和文〕 (特集 ゲノム医学の現在と未来--基礎と臨床) -- (データベース)

The presence of galactose alpha-1,3-galactose residues on the surface of pig cells is a major obstacle to successful xenotransplantation. Here, we report the production of four live pigs in which one allele of the alpha-1,3-galactosyltransferase locus has been knocked out. These pigs were produced by nuclear transfer technology; clonal fetal fibroblast cell lines were used as nuclear donors for embryos reconstructed with enucleated pig oocytes.

https://science.sciencemag.org/content/sci/295/5557/1089.full.pdf

Production of α-1,3-Galactosyltransferase Knockout Pigs by Nuclear Transfer Cloning

Sequential Expression of Pluripotency Markers during Direct Reprogramming of Mouse Somatic Cells

Cloning of mammals by nuclear transfer (NT) results in gestational or neonatal failure with at most a few percent of manipulated embryos resulting in live births. Many of those that survive to term succumb to a variety of abnormalities that are likely due to inappropriate epigenetic reprogramming. Cloned embryos derived from donors, such as embryonic stem cells, that may require little or no reprogramming of early developmental genes develop substantially better beyond implantation than NT clones derived from somatic cells. Although recent experiments have demonstrated normal reprogramming of telomere length and X chromosome inactivation, epigenetic information established during gametogenesis, such as gametic imprints, cannot be restored after nuclear transfer. Survival of cloned animals to birth and beyond, despite substantial transcriptional dysregulation, is consistent with mammalian development being rather tolerant to epigenetic abnormalities, with lethality resulting only beyond a threshold of faulty gene reprogramming encompassing multiple loci.

https://science.sciencemag.org/content/sci/293/5532/1093.full.pdf

Nuclear Cloning and Epigenetic Reprogramming of the Genome

Cloning by nuclear transfer (NT) is an inefficient process in which most clones die before birth and survivors often display growth abnormalities. In an effort to correlate gene expression with survival and fetal overgrowth, we have examined imprinted gene expression in both mice cloned by nuclear transfer and in the embryonic stem (ES) cell donor populations from which they were derived. The epigenetic state of the ES cell genome was found to be extremely unstable. Similarly, variation in imprinted gene expression was observed in most cloned mice, even in those derived from ES cells of the same subclone. Many of the animals survived to adulthood despite widespread gene dysregulation, indicating that mammalian development may be rather tolerant to epigenetic aberrations of the genome. These data imply that even apparently normal cloned animals may have subtle abnormalities in gene expression.

https://science.sciencemag.org/content/sci/293/5527/95.full.pdf

Epigenetic Instability in ES Cells and Cloned Mice

Since the first report of live mammals produced by nuclear transfer from a cultured differentiated cell population in 1995 (ref. 1), successful development has been obtained in sheep, cattle, mice and goats using a variety of somatic cell types as nuclear donors. The methodology used for embryo reconstruction in each of these species is essentially similar: diploid donor nuclei have been transplanted into enucleated MII oocytes that are activated on, or after transfer. In sheep and goat pre-activated oocytes have also proved successful as cytoplast recipients. The reconstructed embryos are then cultured and selected embryos transferred to surrogate recipients for development to term. In pigs, nuclear transfer has been significantly less successful; a single piglet was reported after transfer of a blastomere nucleus from a four-cell embryo to an enucleated oocyte; however, no live offspring were obtained in studies using somatic cells such as diploid or mitotic fetal fibroblasts as nuclear donors. The development of embryos reconstructed by nuclear transfer is dependent upon a range of factors. Here we investigate some of these factors and report the successful production of cloned piglets from a cultured adult somatic cell population using a new nuclear transfer procedure.

Cloned pigs produced by nuclear transfer from adult somatic cells

We thank the technical staff of RIKEN GSC, M. Horishima, H. Ishizaki, N. Ota andY. Seki for sequencing; T. Yada for ORF prediction; A. Toyoda for technical supporton the sequence library preparation; C. Kawagoe for computer system support; andT. D. Taylor for discussion. This work was supported by a grant from the Programfor Promotion of Basic Research Activities for Innovation Biosciences (ProBRAIN)of the Bio-oriented Technology Research Advancement Institution, and Grants-in-Aidfor Scientiﬁc Research from the Japanese Ministry of Education, Science, Sports andCulture.Correspondence and requests for materials should be addressed to Y.S.(e-mail: sakaki@ims.u-tokyo.ac.jp) or H.I. (e-mail: iskw@biol.s.u-tokyo.ac.jp). Thecomplete sequence and the annotated data are available on our website(http://buchnera.gsc.riken.go.jp/). The sequence has been deposited with DDBJ underaccession number AP000398, AP001070 and AP001071 for chromosome, the pTrpplasmid and the pLeu plasmid, respectively.

https://revivicor.com/clonedpigspaper.pdf

June Mullins

Papers

Cloned pigs produced by nuclear transfer from adult somatic cells

transfer from adult somatic cells