Production of fertile salamanders by transfer of germ cell nuclei into eggs

ABSTRACT In amphibians, the ability of somatic cell nuclei to give rise to embryos in nuclear transplantation experiments has been thoroughly investigated and shown to be limited, except in Xenopus laevis. Similar experiments have been performed with primordial germ cells from genital ridges and spermatogonia. In the present paper, we have studied the capacity of germ cell nuclei to promote development of complete and fertile adults in the urodele amphibian Pleurodeles waltl. Germ cell nuclei were taken from larvae at progressive stages of larval development up to meta-morphosis and transplanted into enucleated eggs. Two nonlethal chromosomal mutations were used as nuclear markers in two control series. Nuclei from all developmental stages tested were able to initiate larval development. Furthermore, nine individuals underwent metamorphosis (representing 3 % of normal blastulae) and six of these animals are now adults. When two of these six animals, a male and a female, were mated to each other, the offspring were normal. These results show conclusively, for the first time in amphibians, that germ cell nuclei remain totipotent at least during the larval period.