ADVANCES IN THE GENERATION OF TRANSGENIC PIGS VIA EMBRYO-DERIVED AND PRIMORDIAL GERM CELL-DERIVED CELLS

The development of new technologies that would increase the efficiency for generation of transgenic livestock and would overcome some of the problems associated with random insertion of the transgene will great ly benefit animal agriculture. A potential alternative technology to p ronuclear injection for the generation of transgenic pigs involves the isolation, culture and genetic manipulation of cell lines that can be reintroduced into the embryo for participation in the formation of th e germ cells. We have isolated and cultured pig primordial germ cells (PGC) while maintaining them in an undifferentiated state as determine d by morphology and alkaline phosphatase (AP) activity. More important ly, PGC-derived cells were stably transformed with the green fluoresce nt protein marker driven by the cytomegalovirus promoter. After visual identification of transgenic colonies, the pluripotential characteris tics of the transgenic PGC-derived cells were tested by chimaera forma tion and to date we have identified, by genomic Southern blots, two ch imaeric fetuses that contain tissues with the transgene incorporated i nto their chromosomes. To our knowledge, this is the first report of a chimaeric transgenic pig fetus obtained via a cultured cell line.