EAPSI:Characterizing Estrogen-Like Activity of Oil Spill Dispersant COREXIT® EC9500A

Mcnabb Nicole A, Charleston SC

Investigators

Abstract

Steroid hormones are critical for the normal function and maintenance of physiology in vertebrates. Specifically, estrogens play important roles in differentiation and growth of the reproductive system via the estrogen receptor (ER). The proposed project examines estrogen-like activity of COREXIT® EC9500A, the primary dispersant authorized for use in response to the 2010 BP Deepwater Horizon oil spill, in diamondback terrapins and several species of crocodilians. The results will contribute to understanding the sublethal effects of COREXIT and whether it functions as an environmental estrogen. Moreover, the results will help in the development of less toxic, novel dispersants. Investigating the effects of environmental contaminants, including endocrine disrupting contaminants (EDCs), using sentinel species is critical due to the potential alteration of the endocrine system by EDCs in both wildlife species and humans. This research will be conducted in collaboration with Dr. Taisen Iguchi, a renowned expert on endocrine disruption and developmental effects of estrogen-like chemicals, at the National Institute for Basic Biology in Okazaki, Japan. Estrogens play an important role in temperature-dependent sex determination (TSD) in some turtles and all crocodilians in which incubation temperatures during a thermosensitive period (TSP) in embryonic development determine sex of the embryo. A single exposure to exogenous estrogen during TSP overrides the effects of temperature, and leads to sex reversal or skewed sex ratios by inducing ovarian development at a male-producing temperature. Reptile species that exhibit TSD have been used as sentinel species to investigate chronic exposure to environmental contaminants including EDCs. Using luciferase transactivation assays with nuclear hormone receptors, COREXIT demonstrated estrogenic activity in vitro via Alligator mississippiensis estrogen receptor 1. The proposed work aims to clone and characterize ERs from diamondback terrapins and several crocodilian species. Transactivation assays will be performed with these cloned ERs to compare the transactivation among the different reptile species. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.