Meeting Abstract

P3.35  Monday, Jan. 6 15:30  Effects of maternal hormones on epigenetic state of steroid receptors in Eastern bluebird offspring BENTZ, AB*; SIRMAN, A; WADA, H; HOOD, WR; Auburn University; Auburn University; Auburn University; Auburn University abb0023@auburn.edu

The breeding environment females experience elicits varying hormonal responses and prenatal exposure to these maternal hormones alters the developmental trajectory of offspring, creating potentially adaptive phenotypes for the prevailing environment. In avian species, maternal breeding density influences the number of competitive interactions females experience and, thus, the amount of steroid hormones they produce. Females breeding in higher densities, experiencing more competition for resources, typically allocate more testosterone to their egg yolks. Offspring exposed to higher concentrations of testosterone prenatally tend to be more aggressive throughout life. To date, few studies have examined how maternal steroid hormones exert this long-term influence on offspring phenotype. One possibility is that maternal hormones alter the epigenetic state of pertinent genes in offspring during development causing changes in gene expression and, ultimately, expressed phenotype. In particular, expression levels of the androgen and estrogen receptor in the avian brain have been linked with differences in aggressive phenotypes. Indeed, offspring are exposed to maternal hormones during the period of greatest developmental plasticity when methylation patterns are being established, making this a potential mechanism. Here, we examine the allocation of yolk testosterone in wild Eastern bluebirds (Sialia sialis) breeding in varying densities and compare the methylation status of steroid receptor genes in offspring brain tissue.