Learning And Behavior In Hatchling Trachemys Scripta Exposed To Bisphenol-A During Embryonic Development

Justin E. Dillard, Illinois State University

Imported from ProQuest Dillard_ilstu_0092N_11138.pdf

Abstract

Steroids play an integral role in orchestrating embryonic development, and can affect a suite of phenotypic traits, including learning and memory. Endocrine disrupting compounds (EDCs) can mimic the effects of steroids and can affect the same suites of phenotypic traits during embryonic development. Bisphenol-A (BPA) is an EDC that mimics the action of estrogen, and recent work is beginning to implicate BPA in effects on learning and behavior similar to those caused by estrogen treatment studies. Red-eared slider turtles (Trachemys scripta) are a good system to investigate the effects of BPA on learning and behavior, both because the molecular underpinnings of the mechanistic action of BPA endocrine disruption are generally understood, and because maternal estrogens are limited to egg components allowing for controlled, intra-clutch treatment groups. We exposed T. scripta eggs to BPA during embryonic development, and tested hatchlings for effects on learning and behavior in modified T-mazes. Innate biases in arm choice during the training phase of the experiment limited our ability to assess learning. Time of day and day of experiment both had significant effects on behaviors we investigated, and we found no BPA treatment effects on behaviors. However, we found that hatchling turtles were highly individually repeatable in their behaviors. These repeatable behaviors varied between individual hatchlings, suggesting that there are discrete behavioral types in T. scripta hatchlings. The highly repetitive nature of behaviors might explain the innate biases that prevented us from examining learning with our experimental design.