Generation of genetically modified mice by spermatozoa transfection in vivo: preliminary results

Mouse vas deferens were injected with a plasmid DNA encoding the GFP (Green Fluorescent Protein). The night after injection males were mated with normal oestrus females, and the offspring were analyzed. From 53 newborns, 4 were found positive by PCR for the GFP gene. In these positive animals, some tissues showed expression for GFP as evidenced by a strong green cytoplasmic fluorescence. GFP expression was particularly patent in the liver (hepatocytes), kidney (renal corpuscle and tubules), abdominal wall, and lung. These preliminary results indicate the possibility to use this method as a simple alternative procedure to create transgenic animals, and it could be especially helpful in species in which the microinjection procedure is not feasible.