CHIMERIC CHICKENS AND THEIR USE IN MANIPULATION OF THE CHICKEN GENOME

Germline chimeric chickens can be made by injecting dispersed cells fr om Stage X blastoderms into recipient embryos at an equivalent stage o f development. Colonization of the chimera by donor-derived cells is f acilitated when the recipient embryo is compromised by exposure to irr adiation prior to injection of the donor cells. Donor cells can be gen etically manipulated by lipofection-mediated gene transfer before they are introduced into the recipient. The genetic modification is expres sed in the ectoderm, mesoderm, and endoderm of the chimera after incub ation for 96 h. Donor cells can also be cultured as dispersed cells in a monolayer or as whole-embryo explants for at least 48 h before tran sfer into recipients and retain the ability to enter both somatic and germline tissues in the resulting chimera. A strategy is proposed for the production of transgenic chickens using lipofection-mediated gene transfer to blastoderm cells isolated from Stage X embryos, which are subsequently injected into compromised recipients to yield a germline chimera.