Meeting Abstract
Estrogens play critical roles in differentiation and growth of the reproductive system via the estrogen receptor (ESR) as well as temperature-dependent sex determination (TSD) in some turtles and all crocodilians. In TSD, egg-incubation temperatures determine sex of the embryo during a thermosensitive period (TSP). An exposure to exogenous estrogen during TSP leads to sex reversal or skewed sex ratios by inducing ovarian development at a male-producing temperature. Due to this sensitivity to estrogen, reptiles that exhibit TSD, including the American alligator (Alligator mississippiensis) and diamondback terrapin (Malaclemys terrapin), can be used as sentinel species to investigate chronic exposure to estrogenic environmental contaminants. During the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, COREXIT® EC9500A (COREXIT) was applied to the surface water and at the wellhead to disperse the oil. Using luciferase transactivation assays, we found that COREXIT demonstrates estrogenic activity by inducing transcription via alligator estrogen receptor 1 (ESR1) in vitro. Thus, the estrogenic potential of COREXIT needs to be investigated further in both A. mississippiensis and M. terrapin. ESR1 and ESR2 were cloned and sequenced from diamondback terrapins. Both terrapin ESRs were highly homologous to painted turtle ESRs and will be characterized using transactivation assays with 17β-estradiol, bisphenol A (BPA), and COREXIT. These results will help to understand the potential effects of COREXIT exposure on the reproductive health of coastal aquatic reptiles.
