Meeting Abstract
Female birds can skew the sex ratio of their offspring in response to environmental and social conditions. However, the mechanism by which sex ratio adjustment occurs is unknown. In multiple avian species, including chickens, testosterone (T) treatment results in male-biased sex ratios, with previous work suggesting that T may be acting on the germinal disk (GD) to determine which sex chromosome is retained in the oocyte. Recently, it has been shown that androgen receptors (ARs) are located in the GD region of the F1 follicles, which presents a pathway that T may act on to influence offspring sex. We hypothesized that, if testosterone acts directly on the GD to influence offspring sex, then AR expression in the GD should be highest at the time of meiotic segregation (3-5h prior to ovulation) relative to other times during the ovulatory cycle. To test this, oviposition times for 400 hens were monitored 5 times per day for five weeks, which allowed us to determine which hens were laying the most consistently. Then, F1 follicles were collected from 40 hens at the time of meiotic segregation and from another 40 hens at a point well before meiotic segregation for quantification of AR expression via quantitative real-time PCR. This allowed us to determine whether AR expression is highest on the GD just prior to meiotic segregation. This study may provide critical insight into the potential hormonal mechanisms that underlie sex ratio adjustment in birds.
