Development of transgenic chickens expressing bacterial beta-galactosidase

Replication-defective retroviral vectors are efficient vehicles for the delivery of exogenous genes, and they may be used in the generation of transgenic animals. The replication-defective retroviral SNTZ vector carrying the lacZ gene with a nuclear localized signal was injected into the subgerminal cavity of freshly laid eggs. Subsequently, the eggs were allowed to hatch, and the chickens were screened for the lacZ gene by using the polymerase chain reaction. Eight of 15 male chickens that survived to sexual maturity contained the lacZ gene in their semen. Subsequently, these males were mated with wild-type female chickens. From one of the eight lacZ-positive G(0) males, two lacZ-positive male chickens were produced from a total of 224 G(1) progeny for a germline transmission rate of 0.89%. Both G(1) male chickens carrying the lacZ gene were mated with wild-type female chickens and 46.5% of the G(2) progeny contained the lacZ gene, which is consistent with the expected Mendelian 50% ratio for a heterozygous dominant allele. The product of the lacZ gene, nuclear localized beta-galactosidase, was expressed in primary myoblast cultures derived from G(2) chickens, and it was also expressed in whole G(2) chicken embryos.