@article{parks_eisen_parker_hester_murray_2000, title={Correlated responses to selection for large body size in oMt1a-oGH transgenic mice: reproductive traits}, volume={75}, ISSN={["0016-6723"]}, DOI={10.1017/S001667239900436X}, abstractNote={Correlated responses in female reproductive performance were evaluated following short-term 
selection within full-sib families for increased 8-week body weight in two replicates of four lines of 
mice: two ovine metallothionein–ovine growth hormone (oMt1a-oGH) transgene-carrier lines, one 
from a high-growth background (TM) and one from a control background (TC), and two non-transgenic lines, one from each of these genetic backgrounds (NM and NC, respectively). A fifth 
line (CC), not containing the transgene, served as a randomly selected control. The initial 
frequency of the oMt1a-oGH transgene construct in the TM and TC lines was 0·5. The frequency 
of transgenic females sampled at generations 7 and 8 of selection was 84·0% and 6·1% in the TC 
and TM lines, respectively. No significant female infertility differences were detected between 
transgene-carrier and non-transgenic lines or between transgenic and non-transgenic mice within 
carrier lines, whereas high-growth background lines had a higher infertility than control 
background lines (P < 0·05). Correlated responses in the TC transgene-carrier line were suggestive 
of reduced reproductive performance as indicated by increased post-implantation mortality 
(P < 0·05), number of dead fetuses plus implants (P < 0·05), and loss of fetuses from day 16 to 
parturition (P < 0·001). For the first two traits, the negative correlated responses were accounted 
for by the reduced performance of transgenic compared with non-transgenic females. Embryos 
carrying the transgene may also have a lower viability. In contrast, the NC non-transgenic line did 
not exhibit reduced reproductive performance for these traits. The low frequency of the transgene 
in the high-growth background TM line was associated with reduced fitness and a lower additive 
effect for 8-week body weight compared with the control background TC line.}, number={2}, journal={GENETICAL RESEARCH}, author={Parks, KR and Eisen, EJ and Parker, IJ and Hester, LG and Murray, JD}, year={2000}, month={Apr}, pages={199–208} }
 @article{siewerdt_eisen_murray_parker_2000, title={Response to 13 generations of selection for increased 8-week body weight in lines of mice carrying a sheep growth hormone-based transgene}, volume={78}, DOI={10.2527/2000.784832x}, abstractNote={The purpose of this study was to evaluate selection in lines of transgenic mice. Two replicates of lines that either carried or did not carry the sheep metallothionein-1a sheep growth hormone transgene (oMt1a-oGH) were established. The host lines had been previously selected for rapid growth or selected randomly. Within-litter selection for increased 8-wk body weight was carried out for 13 generations. The frequency of oMt1a-oGH was monitored in all generations in the transgenic lines, but no genotypic information regarding the transgene was used as an aid to selection. The oMt1a-oGH was activated from weaning, at 3 wk, until 8 wk of age by adding ZnSO4 to the drinking water. Zinc stimulation of the transgene was not done during mating, gestation, or lactation. Data on body weights and weight gains were analyzed with a conventional mixed model and with an animal model. Genetic progress was achieved in all lines subjected to directional selection. In the control background, response to selection for 8-wk body weight was larger in the nontransgenic lines than in the transgenic lines, whereas no difference was found in the selected background. The frequency of the transgene was increased from the initial .5 to .62 in the randomly selected background but decreased to .04 in lines from a selected background. The REML estimates of variance components and genetic gain estimates varied greatly between the two methods. In general, there was better agreement between the realized heritability estimates and the heritability estimates obtained from the conventional mixed model analysis than between realized heritability estimates and results obtained using the animal model. Favorable correlated responses were obtained for 3- and 6-wk body weights and on 3- to 6- and 6- to 8-wk weight gains. Correlated responses to selection were larger in the selected than in the nonselected background but were not affected by the presence of the transgene. Results suggest that constructs similar to the oMt1a-oGH, which allow tight regulation, may be successfully incorporated into commercial livestock and should have larger effects in populations that have not been subject to selection.}, number={4}, journal={Journal of Animal Science}, author={Siewerdt, F. and Eisen, E. J. and Murray, J. D. and Parker, I. J.}, year={2000}, pages={832–845} }
 @article{eisen_peterson_parker_murray_1998, title={Effects of zinc ion concentration on growth, fat content and reproduction in oMT1a-oGH transgenic mice}, volume={62}, number={4}, journal={Growth, Development, & Aging}, author={Eisen, E. J. and Peterson, C. B. and Parker, I. J. and Murray, J. D.}, year={1998}, pages={173–186} }