| The main objective of this dissertation was to create transgenic chickens expressing beta-galactosidase as a genetic marker for cell lineage studies. To generate the transgenic chickens, the replication-defective retroviral-based SNTZ vector carrying the E. coli lacZ gene encoding nuclear-localized beta-galactosidase was injected into subgerminal cavity of stage X (EG & K) White Leghorn embryos. Eight of 15 male chicks that survived to sexual maturity were germline chimeric birds based on PCR screening for the lacZ sequences in their semen. One of the eight IacZ-positive G0 roosters transmitted the lacZ gene to two male chicks from a total of 224 progeny (0.89%). From these two transgenic G1 males, the lacZ gene was stably transmitted through 4 generations in an expected Mendelian pattern for a single dominant allele. The expression of beta-galactosidase was detected in cultured myoblasts derived from 1-d-old chick muscle, entire embryos, and in a variety of examined tissue types from young and adult chickens. In the current study, the generated transgenic lines which stably inherited and expressed the reporter lacZ gene are the first report of transgenic birds that could provide an alternative ideal cell marker for cell lineage studies.; Qualitatively high expression of beta-galactosidase was observed in villi of intestine. Potentially, the transgenic chickens that express beta-galactosidase in the gastrointestinal tract could utilize lactose more efficiently. The second objective of this study was to determine whether the transgenic chickens can improve lactose digestibility and its use as an energy source. Overall, when dietary lactose was increased from 5 to 10%, the transgenic chickens showed lactose digestibility approximately 10% better than those of non-transgenic chickens. This is the first report of using gene transfer technology to manipulate the chicken genome to utilize feed more efficiently for agricultural purposes. |
