Somatic cell bovine cloning:Effect of donor cell and recipients

Adult somatic cell nuclear transfer was con-ducted by using cultured ear fibroblast cells obtained from a Holstein female cow (GN) and a Galoway herd bull (GLV). The percentages of reconstructed eggs developed into blas-tocysts were similar in GN (23.98%, 123 of 513) and in GLV groups (29.55%, 138 of 467). However, the rate of recon-structed female (GN) embryos developed into term was higher than that of male (GLV) (8.02% and 1.82%, respec-tively). Three kinds of cows, Luxi Yellow cows, Holstein heifers and Holstein cows with normal reproductive records were used as recipients. When the reconstructed embryos from GN were transferred, there was no difference in the pregnancy rate among three kinds of recipients, but the abortion rate of Luxi Yellow cows was significantly higher (85.71%) than in the other two groups (14.29% and 0%, respectively; P < 0.05). And the percentages of newborn calves in transferred embryos were significantly different between Luxi Yellow cows and Holstein breed (1.54%, 10.39% and 20.0%, respectively, P < 0.05). However, when reconstructed embryos from GLV were transferred, there was no difference among three kinds of recipients in the pregnancy rate, the abortion rate and the delivery rate.

Effects of different nuclear recipients on developmental potential of mouse somatic nuclear transfer embryos

In order to investigate the effects of different kinds of nuclear recipients from Kunming (KM) mouse on developmental potential of somatic nuclear transfer em- bryos, the enucleated MⅡ oocytes, enucleated zygotes and 2-cell blastomere were used to produce cloned mouse em-bryos. Using fibroblast deriving from C57/BL6 ear tissue as nuclear donor, we produced cloned embryos by transferring the fibroblast nuclei into enucleated KM mouse oocytes (sin-gle nuclear transfer, SNT), transferring pronuclei from the SNT embryos into enucleated KM zygotes (nuclear into zy-gote, NZ), and 2-cell blastomere nuclei from SNT embryos into enucleated KM mouse oocytes (nuclear into oocytes, NO); tetraploid embryos (tetraploid embryos, TE) were ob-tained by fusing two blastomeres, one is from the SNT cloned embryos, and the other from normal 2-cell KM mouse em-bryos. In group SNT, the cloned embryos could not develop beyond 8-cell stage and the rate of 8-cell stage is only 0.3%; in group NO, the reconstructed embryos could develop to morula stage, the rate of 8-cell stage was significantly greater than that of SNT group (P < 0.05); in group NZ, the devel-opment rate was further improved, and the reconstructed embryos could develop into blastocyst stage, the rate of blastocyst was 1.9%; in group TE, as high as 62.3% of the reconstructed embryos could develop into blastocyst. Results suggested that different nuclear recipients could significantly affect the developmental potential of cloned mouse embryos; KM MⅡ oocyte cytoplasm was not so effective as zygotes to reprogram the mouse somatic cell nuclei; serial nuclear transfer could improve the developmental potential of cloned mouse embryos.