Meeting Abstract
Female birds skew offspring sex ratios based on environmental and social stimuli, but the mechanism mediating these skews remains unknown. Growing evidence suggests that testosterone and corticosterone may influence sex chromosome segregation, as they skew sex ratios when experimentally elevated immediately before. It is unknown whether the germinal disk (GD) contains receptors for these hormones and whether any receptors present allow the GD to respond genomically to treatment with testosterone and corticosterone. We collected ovarian follicles at 5h pre-ovulation (just before chromosome segregation) and 20h pre-ovulation (when sex chromosomes are arrested), and measured androgen receptor (AR) and mineralocorticoid receptor (MR) protein levels via Western blot. ARs and MRs were present in both the GD and non-GD regions. AR protein levels were higher in the GD region than the non-GD region, but MR protein levels did not differ between regions. Next, we tested whether short-term treatment of hens with these hormones changed expression patterns of genes affecting meiosis. We had 3 treatments (n = 50 hens each): Injection of (1) 1.5mg T in 0.5ml of peanut oil (2) 1.5mg of CORT in 0.5ml of peanut oil, and (3) control oil injection, all at 5h before ovulation. We collected GDs from hens 1.5h after injection and, using RNA-sequencing, we identified 4 genes differentially expressed between the corticosterone and control group that are of interest. This work revealed that ovarian follicles contain receptors that respond to these hormones, and that these hormones may influence gene expression to mediate offspring sex.
