Production of HanWoo (Bos taurus coreanae) fetuses following interbreed somatic cell nuclear transfer

The possibility of producing HanWoo (Bos taurus coreanae) calves from trans ferable bovine embryos, obtained by interbreed nuclear transfer using Holst ein cytoplasts and surrogates, was investigated. As donor nuclei, HanWoo fe tal fibroblasts were used. Cells were induced into quiescence by serum depr ivation for 4-7 days before nuclear transfer. In vitro matured Holstein Ooc ytes were enucleated, and single donor cell was placed into the perivitelli ne space of enucleated oocyte. After reconstruction, the embryos were fused , activated and cultured. On day 7, the embryos that developed to the blast ocyst stages were transferred into Holstein recipient cows on day 6 to 7 of estrous cycle (estrus=0). The reconstructed embryos were successfully fuse d 58.8%; 47/80), cleaved (91.5%; 43/47), and developed to blastocysts (29.8 %; 14/47). Eleven blastocysts were transferred into 5 Holstein recipient co ws. Two recipients were pregnant, confirmed by ultrasonography at day 60 of gestation. But, one of them was opened between on day 80 to 100 of pregnan cy, and the other bad a stillbirth on day 255. The stillborn calf was physi cally normal, and we couldn't find any evidence of anomaly. These results s how that cells derived from HanWoo somatic cell lines can be reprogrammed b y interbreed nuclear transfer and develop subsequently in vivo as well as i n vitro.