Observing changes in ora expression in the olfactory epithelium of juvenile zebrafish (Danio rerio) post-androgen treatment

Barajas, Ana L., Montasir Rahman, Steven Chang, and Rachelle M. Belanger

Steroid-induced central neural effects that influence olfactory sensitivity, sex partner preferences, and chemoinvestigative behaviours are well known in vertebrates. However, with the data currently available, it is difficult to speculate on which specific component(s) of the neural pathway that processes olfactory signals are targeted for differentiation by steroid hormones in the developing nervous system. Previous work shows that when juvenile zebrafish (Danio rerio) demonstrate differential electro-olfactogram responses to putative sex pheromones post-androgen treatment. Additionally, treated juveniles performed more courtship-like behaviors in response to a stimulus fish. In this study, we investigated the mode of action of androgens on the expression of the six olfactory receptors (ora’s). We treated juvenile zebrafish with 11-ketotestosterone (11-KT; 10-8 M) or ethanol vehicle (control) and removed the olfactory epithelium and extracted the RNA from fish 7 and 14 days treatment. RNA was pooled, sequenced and bioinformatics was performed. We found that there were no changes in expression of ora 1 through 5 post-11-KT treatment. This may be due to variability in the data or post translational effects on ora expression. Future work will repeat the treatments, increase sample size and examine protein production using Western blotting techniques.