The Combinatory Effects of 17β-estradiol and Atrazine on Xenopus laevis Development
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The presence of chemical toxicants such as pesticides and estrogens in local watersheds has become an issue of concern in recent years. Environmental reports have shown that amphibian populations have declined, along with the health of the overall ecosystems (Gardner, 2001). Organisms exposed to endocrine disrupting chemicals (EDCs) experience interruption of the natural organogenesis that takes place during development (Lenkowski et al 2008). Amphibians, fish, and other aquatic organisms are the most at-risk because of constant EDC exposure due to water-dependent survival. The model organism Xenopus laevis is a perfect sentinel for studying EDCs because of its short life cycle that is spent entirely in water, hormone-dependent development, and thin epidermis (Cong et al 2005). It is also being tested in multiple laboratories, providing for better optimized techniques and protocols. In the laboratory, EDC experiments are often single-chemical experiments, which are not representative of the natural environment. The purpose of this research is to propose an experimental setup that evaluates two ecologically relevant chemicals in combination. Firstly, I will develop an atlas of gonad malformations to standardize the evaluation process and reproducibly gauge the morphological defects associated with endocrine disruption. Secondly, I aim to asses the internal effects of EDCs on X.laevis using histology, directly observing the intersex and feminization proposed due to EDC exposure. Furthermore, the methods will be extrapolated to a local species of frog, Rana pipiens to test for similar effects found in X.laevis.