Meeting Abstract
Estrogens, common contaminants in wastewater effluent, are endocrine disrupting compounds found to be potentially problematic for vertebrates. One of the more potent synthetic estrogens present in water systems is 17α-ethynylestradiol (EE2), an active ingredient found in many types of birth control. Estrogens stimulate the synthesis of vitellogenin (vtg), a precursor egg yolk protein, produced in egg laying vertebrates including fish. Additionally, estrogens are involved in the activation of intracellular estrogen receptors (ERs). ERs interact with estrogen response elements involved in the regulation of estrogen-responsive genes, such as vtg. Because of the inducibility of vtg expression upon exposure to estrogenic compounds, the vtg gene functions as a biomarker for exposure to environmental estrogens. This study characterizes the expression profile of two genes known to be responsive to estrogens, estrogen receptor alpha (ERa) and vitellogenin (vtg), in fathead minnows (Pimephales promelas) for both immediate and depurated time points. Fish were exposed to EE2 at concentrations of 0, 2.5, and 10 ng/L for 48 h. Gene expression was quantified across two tissue types: liver, where both genes are expressed, and brain, where ERa expression occurs but vtg expression does not. In liver, mean gene expression values for both ERa and vtg increased with exposure to higher EE2 concentration while their variances decreased. With increasing dosage, correlation between ERa and vtg expression increased.
