More Efficient Cloning
Scientists at the University of Connecticut have made a conceptual breakthrough in cloning by culturing nuclear donor cells for up to three months. Cloning had previously been successful only with fresh or short-term cultured cells. "It is shocking to us that we found long-term cultured cells not only can support development of offspring, but their efficiency for cloning is actually better than short-term culturing," comments Xiangzhong Yang, head of the University of Connecticut's transgenic animal facility. Yang and colleagues from Kagoshima Prefectural Cattle Breeding Development Institute, Japan, report in an upcoming issue of Proceedings of the National Academy of Sciences (PNAS) the generation of six genetically identical calves using skin fibroblast cells taken from the ear of a 17-year-old prize bull. This finding is pivotal to combining cloning technology with site-specific genetic manipulations, which are currently used to create new strains of mice with mutations in virtually ...
