Meeting Abstract

P1.85  Wednesday, Jan. 4  Effects of Exposure to 4-tert-Octylphenol on Sexual Differentiation and Gene Expression in African Clawed Frogs WOLFF, SE*; COSTON, JM; VELDHOEN, N; HELBING, CC; PROPPER, CR; Northern Arizona University; Northern Arizona University; University of Victoria; University of Victoria; Northern Arizona University stephanie.wolff@nau.edu

The chemicals released into the environment, known as endocrine disrupting compounds (EDCs), pose threats to wildlife and human health. Contact with EDCs is possible through contaminated water, food, air, and soil. One group of particular concern is the alkylphenols, such as 4-tert-octylphenol (OP), with estrogen-like activity that contributes to numerous detrimental physiological impairments. The purpose of this study was to determine the effects of OP on gene expression of two genes essential in sexual differentiation, forkhead box L2 (Foxl2) and steroidogenic factor 1 (SF-1). African clawed frog (Xenopus laevis) tadpoles were exposed for two weeks during critical stages of sexual differentiation to three levels of OP (10-7M, 10-8M, and 10-9M), a positive estradiol (E2 control (10-9M)) and a negative ethanol vehicle control. After two weeks of exposure, gonads were collected for qPCR and animals were sexed genomically. At the stage of development analyzed, there was no sexual dimorphism in expression of either gene. However, animals exposed to E2 and OP had significantly lower levels of Foxl2 mRNA compared to controls, while animals exposed to either compound had significantly higher levels of SF-1. Our results demonstrate that OP sets up a pattern of gene expression disruption similar to E2 during the very earliest stages of gonadal differentiation. Our results suggest that these compounds effect gonadal differentiation and functional outcomes by disrupting expression of genes critical to development.