SITE-SPECIFIC TRANSGENE INSERTION - AN APPROACH

Methods to improve the production of transgenic animals are being deve loped. Conventional transgenesis, involving microinjection of DNA into fertilized eggs, has a number of limitations. These result from the i nability to control both the site of transgene insertion and the numbe r of gene copies inserted. The approach described seeks to overcome th ese problems and to allow single copy insertion of transgenes into a d efined site in animal genomes. The method involves the use of embryoni c stem cells, gene targeting and the FLP recombinase system.