Improved efficiency of bovine cloning by autologous somatic cell nuclear transfer

Somatic cell nuclear transfer (SCNT) has been used for the cloning of various mammals. However, the rates of successful, healthy birth are generally poor. To improve cloning efficiency, we report the utilization of an lautologous SCNT' cloning technique in which the somatic nucleus of a female bovine donor is transferred to its own enucleated oocyte recovered by ovum pick up, in contrast to the routine'allogeneic SCNT' procedure using oocytes from unrelated females. Our results showed that embryos derived from autologous SCNT have significantly higher developmental competence than those derived from allogeneic SCNT, especially at the eight-cell (60vs 44%), morula (45 vs 36%), and blastocyst (38 vs 23%) stages. The pregnancy and birth rates were also higher for the autologous (39 and 23%), compared to the allogeneic (22 and 6%) SCNT groups. Genome-wide histone3-lysine9 methylation profiles reveal that autologous SCNT embryos have less epigenetic defects than the allogeneic SCNT embryos. This study indicates that autologous SCNT can improve the efficiency of bovine cloning with less reprogramming deficiency.