The Sex Bias: Investigating Sexually Dimorphic Behavior in Socially Stressed Drosophila

Abstract

Stress is widely recognized as a significant factor contributing to mood disorders and neurodegenerative diseases. Thus, identifying the genes that play a role in the link between chronic stress and behavior is important to a complete understanding of the biological manifestations of stress. Preliminary studies in the lab have found anhedonia- like behavior in Drosophila melanogaster to be affected by social stress, with dimorphism in the stress response having been observed between males and females (Tawa and Notterman, unpublished results). Following these observations, this research aims to investigate sexual dimorphism in motivated behavior induced by chronic social stress and to pinpoint potential genetic markers linked to such behavioral differences. In this study, I analyzed the effects of overcrowding and social isolation on food- seeking behavior in Drosophila, stratified by sex. When using yeast paste, there was no sexually dimorphic behavior observed in Drosophila subjected to overcrowding. However, isolated females displayed a decrease in food preference whereas their male counterparts showed an increase when compared to each group’s respective controls. Conversely, when using apple cider vinegar, overcrowded males had no significant difference in feeding behavior while stressed females displayed a decrease in feeding. Knockout flies for candidate genes 5-HT2A, 5-HT2B, and Dop2R displayed differential stress responses compared to wild-type flies, as well as between sexes. In line with my findings, quantification of candidate genes in wild-type flies revealed sex differences in gene expression following social isolation, with overexpression in males and underexpression or no change in females. Taken together, this study presents evidence for candidate genes whose expression may mediate stress-related behavior that manifests differently between sexes.