Generation of transgenic mice and germline transmission of a mammalian artificial chromosome introduced into embryos by pronuclear microinjection

We have generated transgenic mice by pronuclear microinjection of a murine satellite DNA-based artificial chromosome (SATAC). As 50% of the founder pr ogeny were SATAC-positive, this demonstrates that SATAC transmission throug h the germline had occurred. FISH analyses of metaphase chromosomes from mi togen-activated peripheral blood lymphocytes from both the founder and prog eny revealed that the SATAC was maintained as a discrete chromosome and tha t it had not integrated into an endogenous chromosome. To our knowledge, th is is the first report of the germline transmission of a genetically engine ered mammalian artificial chromosome within transgenic animals generated th rough pronuclear microinjection. We have also shown that murine SATACs can be similarly introduced into bovine embryos. The use of embryo microinjecti on to generate transgenic mammals carrying genetically engineered chromosom es provides a novel method by which the unique advantages of chromosome-bas ed gene delivery systems can be exploited.