Comparing the use of qPCR on isolated smallmouth bass (Micropterus dolomieu) and rainbow trout (Oncorhynchus mykiss) hepatocytes for estrogen screening
Exposure of fish to estrogenic endocrine disrupting chemicals (EEDCs) is believed to be a contributing factor of intersex (the presence of immature oocytes in the testes) and fish kills in the Potomac and Shenandoah Rivers. EEDCs are often seen in the effluent of wastewater treatment plants. A simple and common way to look at the estrogenicity of water samples is to deploy Passive Organic Chemical Integrative Samplers (POCIS) and extract the hydrophilic compounds from the filters with methanol. Samplers were deployed upstream and downstream of two wastewater treatment plants, one on the Conococheague River and one on the Monocacy River, both of which are in Maryland. For comparison purposes, one POCIS was deployed in Blue Plains, just outside of Washington, D.C. and one POCIS was deployed at a control site in a closed pond at the National Fish Health Research Laboratory in Kearneysville, WV. Primary hepatocytes from rainbow trout (Oncorhynchus mykiss) and smallmouth bass (Micropterus dolomieu) were isolated to compare vitellogenin induction upon exposure to 17-beta estradiol. Smallmouth bass hepatocytes yielded low concentrations of RNA and qPCR was unsuccessful. Male rainbow trout showed low vitellogenin induction levels at high concentrations of 17-beta estradiol and no induction at low concentrations. Female rainbow trout hepatocytes showed vitellogenin induction during exposure to 17-beta estradiol at high and low concentrations. Rainbow trout hepatocytes were used to screen for estrogenic compounds from the extracts of the deployed water samplers also using vitellogenin induction as an endpoint. Male rainbow trout hepatocytes showed no vitellogenin induction. Female rainbow trout hepatocytes exposed to samples showed no statistically significant differences in vitellogenin induction
