A COMPARISON OF PROGESTERONE RECEPTOR GENE EXPRESSION IN THE OLFACTORY EPITHELIUM OF REPRODUCTIVE AND NON-REPRODUCTIVE FATHEAD MINNOWS, PIMEPHALES PROMELAS

Abstract

Fish have a specialized organ called the olfactory epithelium that enables them to detect chemical cues in water. Among these cues are progestogens excreted by females that function as pheromones and stimulate male reproductive behavior and spermiogenesis. The olfactory epithelium is hypothesized to contain receptors that are activated by these pheromones. In this study, I compared the expression of nuclear and membrane progesterone receptors in reproductive and non-reproductive fathead minnows and in male versus female fish. I found changes in mPR expression over time in both comparisons of reproductive adults to juveniles, and reproductive adults to non-reproductive adults, and no differences between sexes. This is the second study to examine gene expression in the olfactory epithelia of fish and is novel in the experimental approach taken. Results from this research will inform future studies aiming to make the functional linkage between pheromones and the regulation of teleost fish reproduction.