Poster 11
Presenter: Reinmar Hager
Wednesday, 3:00 – 5:00pm
Reinmar Hager, James M. Cheverud, Jason B. Wolf
Epigenetic effects are increasingly recognized as an important source of phenotypic variation in addition to genetic and environmental factors. Among epigenetic effects, genomic imprinting, resulting in parent-of-origin-dependent gene expression, is among the best studied of epigenetic effects. While interactions between environment and genetic variation have been amply demonstrated very little is known about the degree to which genomic imprinting effects can be modulated by the environment, in particular the social environment given by siblings and mothers. Is it possible that patterns of imprinted gene expression depend on the number of siblings and on the type of mother? To address this question, we studied an intercross between the Large and Small mouse strains using a cross-fostering design in which mouse pups were nursed by either their own or an unrelated mother. We scanned the entire genome to search for imprinted quantitative trait loci whose effects on body weight depend on cross-fostering and detected four of such loci. Further, we demonstrate that effects of sibling number on body weight depend on individual genotype at seven loci, over and above the general negative litter size effect. Overall, these litter size by genotype interactions considerably modified the degree to which increasing litter size caused reduced weight but only one imprinted locus showed an interaction effect. Our results demonstrate that genomic imprinting effects may often be modified by the maternal environment and that such interactions can impact key fitness-related traits suggesting a greater plasticity of genomic imprinting than previously assumed. However, imprinting effects on weight that depend on the number of competitors are small. Thus, we conclude that part of the way in which offspring development is affected by maternal environment may be through modification of imprinted gene expression but the social environment provided by siblings does not have effects of similar magnitude.