Nuclear transfer using nonquiescent adult fibroblasts from a bovine ear

The natural reproduction of mammal is sexual reproduction, which needs fert ilization involving sperm and oocyte; Nuclear transfer provided an asexual reproduction method for mammal. Donor cells used in previous experiments of nuclear transfer were mostly from undifferentiated or non-terminally diffe rentiated cells, such as embryonic or fetal cells. However, since Wilmut ef al. obtained a viable lamb by transfer of an adult sheep somatic cell into an enucleated oocyte, nuclear transfer using adult somatic cell has been s uccessful in several species. Wilmut ef al. suggested that it was a key fac tor for the success of somatic nuclear transfer to induce the donor cells i nto G0 phase ("G0-phase hypothesis"). In order to verify the GO-phase hypot hesis, nonquiescent adult fibroblasts from a bovine ear were transferred in to enucleated bovine oocytes. The experiments showed that the rate of elect rofusion after micromanipulation was above 50%, the cleaving rate was 54.5% and 9.1% of those reconstructed embryos developed to 32-cell stage. These results indicate that for cattle, nuclei from nonquiescent adult somatic ce lls introduced into enucleated oocytes are at least capable of supporting e arly development.