Uterine and postnatal maternal effects in mice selected for differential rate of early development

A series of mouse lines was produced by long-term restricted index selectio n for divergent rate of growth during early and late postnatal development. The selection program was based on the following treatments: E+ and E- lin es were selected to alter birth to 10-day weight gain while holding late ga in for both lines constant and a control line was established via random se lection. Using embryo transfer and crossfostering methodology, we partition ed postnatal growth for E+, E-, and C lines into progeny genetic, uterine m aternal, and nurse maternal components. Selection for differential early gr owth resulted in correlated response in uterine and nurse maternal effects on body weights, with significant genetic-by-environment interactions. Sign ificant uterine effects were also observed in tail length measurements. Dir ect uterine effects on body weight were relatively small and resulted in gr owth rate differences early in development. Nurse effects were large, resul ting in modification of progeny growth trajectory especially during early p ostnatal development. Genetic-by-uterine interactions were large and demons trate progeny-specific effects of the prenatal uterine environment.