RESUMEN
We have transferred a gene coding for rabbit beta-globin into the male pronucleus of mouse zygotes by direct microinjection. Some of these zygotes developed into mature mice which contained this gene and appeared to be producing a rabbit globin. Evidence for the presence of the gene in these animals was provided by Southern blot hybridization analysis. Evidence for the expression of the rabbit gene in these transformed mice and their offspring was provided by hemoglobin isoelectric focusing analysis and specific serological reactivity between mouse anti-rabbit hemoglobin antiserum and a hemolysate from the mice that developed from the microinjected zygotes. The use of this zygote transformation may allow the introduction and expression of a broad range of genetic elements in mammals.