Introduction of exogenous DNA into somatic and germ cells of chickens by microinjection into the germinal disc of fertilized ova.

The plasmid DNA, pAcZ, containing Escherichia coli beta-galactosidase (lacZ) gene under the control of chicken beta-actin gene promoter was injected in a linearized form into the germinal disc of fertilized chick ova at the single-cell stage. The manipulated embryos were cultured by the method of Naito et al. (1990) until hatching. The rate of hatching was 11.8% (31/263), and 19 males and 6 females were matured. DNA from blood and semen samples of the 25 matured chickens was analyzed for the presence of the injected DNA by Southern blot hybridization. The injected DNA was detected in the blood DNA of one male and in the sperm DNA of another male up to 13 months after hatching, indicating that the injected DNA was stably maintained in these chickens. Restriction digestion analysis of the injected DNA suggested that it was not rearranged and was organized as head-to-tail multimers. The copy numbers of the DNA were 0.07-0.02 in the blood DNA of one male per diploid genome, and 0.02-0.015 in the sperm DNA of another male, indicating that the exogenous DNA was present in limited populations of blood and sperm cells.