GENE-ACTION OF THE OMT1A-OGH TRANSGENE IN 2 LINES OF MICE WITH DISTINCT SELECTION BACKGROUNDS

Ten transgenic (sheep metallothionein a-sheep growth hormone transgene , oMt1a-oGH) homozygous male mice were mated to females of two lines w ith distinct selection backgrounds. Inter se matings yielded F-2 mice in each line: selected background and control background. Genotypes wi th respect to the transgene insert were obtained in ail mice. Weekly b ody weights were taken. Males were dissected at 8 weeks of age and fat pads and organs were weighed. Females were mated at 10 weeks; reprodu ctive data were collected on the 16th day alter detection of a copulat ory plug. Gene action on body, fat pads and organs weights showed domi nance effects. The oMt1a-oGH transgene caused body and organ weights t o increase and fat pad weights to reduce. No unfavourable effects of t he transgene insert were found on reproductive traits. Results indicat e that incorporation of the oMtla-oGH in populations of mice should be successful.