Meeting Abstract

56.1  Thursday, Jan. 6  Uptake and consequences of yolk androstenedione in male and female chicks BENOWITZ-FREDERICKS, ZM*; HODGE, M; CHOW, J; HAUSSMANN, M; Bucknell University; Bucknell University; Bucknell University; Bucknell University zmbf001@bucknell.edu

Androstenedione is found in avian egg yolks in large quantities, but its role in development is unclear. One possibility is that males and females use maternal androstenedione differently to deliver estrogens or androgens as needed to different target tissues and at different stages in development. We investigated the sex specific mechanisms of yolk steroid utilization by assessing uptake and metabolism of radiolabeled androstenedione from egg yolk in domestic chickens (Gallus gallus domesticus). We found radiolabeled androstenedione derivative in all egg compartments and tissues in day 7 and day 16 embryos of both sexes. Significant proportions of the radiolabel were water-soluble, indicating active steroid metabolism by embryos. We also looked for sex-specific trade-offs in chicks and found sex differences in physiological and behavioral consequences of elevated yolk androstendione. Males, but not females, showed evidence of metabolic tradeoffs: androstenedione-treated males grew more quickly but had shorter telomeres after 2 weeks post-hatch. Behavior was also different in androstenedione-treated males. However, we found no effect of androstenedione treatment on females. Our results indicate sex differences in utilization of maternal steroids and support growing evidence for embryonic control of maternal effects. The potential costs and benefits of maternally-derived hormones also highlight the complexity associated with understanding fitness trade-offs generated by maternal effects.