Mouse Male Germ Cells in Culture: Toward a New Approach in Transgenesis?

Abstract

To extend and diversify our methods for the manipulation of mammalian genomes, transfer of genes into germ cells might constitute a useful alternative to methods based on the use of fertilized zygotes, early embryos, or ES cells. These powerful techniques are time consuming and costly. Moreover, they are applicable only to a limited number of species. The search for alternative methods appears therefore as a worthwhile long term prospect. Since the function of germ cells is to transmit genes to successive generations, why not transfer DNA molecules directly into germ cells before fertilization? Very little information is available as to the ability of any genetic material, viral or cellular, to enter germ cells under natural conditions. If, during evolution, new genes may have been occasionally introduced into mammalian germ cells by retrovirus infection, this horizontal transfer has probably been a rare event. One experimental model is provided by a strain of laboratory mice (SWR/J), where efficient provirus acquisition in the female germline has been reported (Jenkins et al. 1985; Panthier et al. 1988).