ANDROGEN AND PROGESTERONE RECEPTORS KNOCKOUTS IN ZEBRAFISH AFFECT AGGRESSION AND SOCIAL DOMINANCE

Abstract

ABSTRACT - There is circumstantial evidence that steroids, such as androgens and progesterone, play roles in aggression and social behaviors in vertebrates. However, the genetic basis for these behaviors needs to be further elucidated. Zebrafish hormone receptor knockouts were created to examine aggression and social hierarchy in male Danio rerio. Wild Type (WT), androgen receptor knockout (ARKO), and progesterone receptor knockout (PGRKO) males were isolated for one week before being paired to match for age. Five pairing types, WT-WT, WT-ARKO, WT-PGRKO, ARKO-ARKO, and PGRKO-PGKRO were observed for two weeks. Each pair was observed for 5 minutes per day during this pairing period, where aggressive behaviors (attacks) and submissive behaviors (retreats) are recorded. Filming of pairs occurred on the first and last day of pairing to determine the divergence of social roles over time and the quality of aggressive encounters. Motion tracking analysis of non-interaction frames was used to generate heat maps of the swimming patterns and localization of each fish independently in the tank. Further analysis of the pair interactions (encounters) shows detail on the quality of attacks that occurred, including average encounter/min, average encounter duration, and average attacks/encounter. This data will give insight to the role of AR and PGR in mediating male aggressive and social behaviors. It is hypothesized that androgens and progesterone can have important opposing effects and that AR and PGR are highly important as biological switches for an individual fish to display proper behavior for his survival.