继代核移植能成倍提高来自奶山羊卵胞质体的异种间核移植重构胚的发育率

为了提高异种间核移植重构胚的发育率，本研究以体内排放的奶山羊成熟卵为供胞质的受体细胞，以人、兔、波尔山羊等的异种或亚种体细胞的原代核移植（Primary Somatic Cell Nuclear Transfer，PSCNT）重构早胚（8-16细胞期）的卵裂球作供核体，观察经亚种或异种卵胞质体短期“修饰”的核再移植产生的继代（Secondary SCNT，SSCNT）重构胚的着床前发育潜能。结果：人、兔、波尔山羊的继代桑椹／囊胚发育率均显著地高于其PSCNT胚胎（人，14．81％VS．7．79％；兔，23．53％VS．12．50％；波尔羊，55．35％VS．24．53％）；这些早胚的各阶段发育时程仍遵循供核体动物正常受精卵的发育时程。结果启示：奶山羊成熟卵胞质对异种体细胞核亦具一定的去分化能力，能支持重构胚发育到囊胚；异种重构胚的发育特征是由供体核所决定的；继代核移植几乎能够成倍提高异种间重构胚的着床前发育率，提示核的去分化完全是在母型信息主导的调控之下完成的，而进一步发育的时序似乎是由核决定的：成倍延长在含母型信息主导调控环境中的时间能成倍提高SCNT重构胚的着床前发育率。

SECONDARY SCNT DOUBLES THE PRE-IMPLANTATION DEVELOPMENT RATE OF RECONSTRUCTED INTERSPECIES EMBRYOS BY USING CYTOPLASTS OF SANNEN DAIRY GOAT OVA

The aim of this study was to investigate whether ova of Sannen goat could support the pre-implantation development of interspecies embryos constructed through somatic cell nucleus transfer (SCNT) embryos and whether secondary SCNT (SSCNT) could improve the pre-implantation development of those embryos. The primary SCNT (PSCNT) embryos were produced by using Sannen goat ovum cytoplasts as recipients and fibroblast cells, derived from human, rabbit and Boer goat skins, as nucleus donors. The blastomeres of 8 to 16 cells stage of PSCNT embryos were subsequently used as nucleus donor cells and Sannen goat ovum cytoplasts as recipients to evaluate the effect of SSCNT on the pre-implantation development rate of these reconstructed interspecies embryos. Our results indicate that the pre-implantation development rates of SSCNT embryos reconstructed using these three different blastomeres are almost twice of that of corresponding PSCNT embryos (human, 15.8% vs. 7.8%; rabbit, 27.9% vs. 12.5%; Boer goat 55.3% vs. 24.5%; P < 0.05 in all three cases). The time durations that embryos need for the serial events of remodeling and reprogramming to take place vary, depending on the animal species of nucleus donors. These data suggest that remodeling and reprogramming of donor nucleus may be enhanced by prolonged exposure of donor nucleus to maternal cytoplast. We conclude that Sannen goat cytoplast can support the pre-implantation development of embryos constructed with nuclei from various donors, including fibroblasts of human, rabbit and Boer goat; and the somatic nucleus derived from different species requires more time to achieve its reprogramming necessary for pre-implantation development.