Takeda Kumiko, Kaneyama Kanako, Tasai Mariko, Akagi Satoshi, Takahashi Seiya, Yonai Miharu, Kojima Toshiyuki, Onishi Akira, Tagami Takahiro, Nirasawa Keijiro, Hanada Hirofumi
National Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan.
Mol Reprod Dev. 2008 May;75(5):759-65. doi: 10.1002/mrd.20837.
In embryos derived by nuclear-transfer (NT), fusion of donor cells with recipient oocytes resulted in varying patterns of mitochondrial DNA (mtDNA) transmission in NT animals. Distribution of donor cell mtDNA (D-mtDNA) found in offspring of NT-derived founders may also vary from donor cell and host embryo heteroplasmy to host embryo homoplasmy. Here we examined the transmission of mtDNA from NT cows to G(1) offspring. Eleven NT founder cows were produced by fusion of enucleated oocytes (Holstein/Japanese Black) with Jersey/ Holstein oviduct epithelial cells, or Holstein/Japanese Black cumulus cells. Transmission of mtDNA was analyzed by PCR mediated single-strand conformation polymorphism of the D-loop region. In six of seven animals sampled postmortem, heteroplasmy were detected in various tissues, while D-mtDNA could not be detected in blood or hair samples from four live animals. The average proportion of D-mtDNA detected in one NT cow was 7.6%, and those in other cows were <5%. Heteroplasmic NT cows (n = 6) generated a total 12 G(1) offspring. Four of 12 G(1) offspring exhibited high percentages of D-mtDNA populations (range 17-51%). The remaining eight G(1) offspring had slightly or undetectable D-mtDNA (<5%). Generally, a genetic bottleneck in the female germ-line should favor a homoplasmic state. However, proportions of some G(1) offspring maintained heteroplasmy with a much higher percentage of D-mtDNA than their NT dams, which may also reflect a segregation distortion caused by the proposed mitochondrial bottleneck. These results demonstrate that D-mtDNA in NT cows is transmitted to G(1) offspring with varying efficiencies.
在通过核移植（NT）获得的胚胎中，供体细胞与受体卵母细胞的融合导致NT动物中线粒体DNA（mtDNA）传递模式各异。在NT衍生的奠基者后代中发现的供体细胞mtDNA（D-mtDNA）分布，也可能从供体细胞与宿主胚胎的异质性到宿主胚胎的同质性有所不同。在此，我们研究了mtDNA从NT奶牛向G(1)代后代的传递情况。通过将去核卵母细胞（荷斯坦/日本黑牛）与泽西/荷斯坦输卵管上皮细胞或荷斯坦/日本黑牛卵丘细胞融合，产生了11头NT奠基奶牛。通过PCR介导的D环区域单链构象多态性分析mtDNA的传递情况。在7只死后取样的动物中，有6只在各种组织中检测到异质性，而在4只活体动物的血液或毛发样本中未检测到D-mtDNA。在一头NT奶牛中检测到的D-mtDNA平均比例为7.6%，其他奶牛中的比例<5%。异质性NT奶牛（n = 6）总共产生了12头G(1)代后代。12头G(1)代后代中有4头表现出高比例的D-mtDNA群体（范围为17 - 51%）。其余8头G(1)代后代的D-mtDNA比例较低或无法检测到（<5%）。一般来说，雌性生殖系中的遗传瓶颈应有利于同质性状态。然而，一些G(1)代后代维持了异质性，其D-mtDNA比例比它们的NT代母本高得多，这也可能反映了由所提出的线粒体瓶颈导致的分离畸变。这些结果表明，NT奶牛中的D-mtDNA以不同效率传递给G(1)代后代。
