Effect of genetic background on growth of mice hemizygous for wild-type or dwarf mutated bovine growth hormone transgenes
1993
Eisen, E.J. (North Carolina State Univ., Raleigh (USA). Dept. of Animal Science) | Fortman, M. | Chen, W.Y. | Kopchick, J.J.
The effects of a high-growth genetic background on the growth of mice hemizygous for one of two growth hormone transgenes were examined. Male mice hemizygous for wild-type (W) and dwarf mutant (M) bovine growth hormone (bGH) transgenes were crossed with females of a high-growth selected (S) and control (C) line as follows: W x S, W x C, M x S and M x C. Body weights of progeny were recorded weekly from 2 to 10 weeks of age. F1 progeny were classified as carriers (P) or non-carriers (N) of the transgene by assaying tail DNA for bGH using the polymerase chain reaction and agarose gel electrophoresis. A deficiency in the number of F1 progeny carrying the W (P below 0.05) and M (P below 0.01) bGH transgene was most likely due to differential prenatal and early postnatal mortality. Bodyweight means of wild-type transgenic mice were larger (P below 0.05) than those of non-transgenic littermates by 3 weeks of age in a C background in contrast to 5 weeks in S. The wild-type bGH transgene increased adult body weights more in the C (155%) than in the S (136%) background, indicating transgene expression by selection background interaction (P below 0.05). However, the growth response to the wild-type transgene in the S background was still large. The dwarf mutant transgene had a greater effect on growth reduction in the S (70%) than in the C (84%) background, thus causing transgene expression by selection background interaction (P below 0.05). Gender by wild-type transgene effect interactions (P below 0.001) for adult body weight were caused by the transgene reducing the gender difference for body weight in C and eliminating it in S
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