Vitellogenin and 11β hydroxylase mRNA expression in male Japanese medaka (Oryzias latipes) exposed in a short term laboratory assay to low levels of t
LAUREN T. MOFFATT, KATERINA D. FAGAN-SOLIS, EVA P. BROWNE, AND KATHLEEN F. ARCARO
Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA, USA
Among those pollutants of our world’s water resources that are currently being studied as “emerging contaminants”, environmental estrogens are of particular concern due to their potential for endocrine disruption of non-target organisms. Measuring the induction of vitellogenin using highly sensitive techniques such as real time RT-PCR is a rapid and sensitive tool for detecting estrogenic activity. It is important to determine the sensitivity of this model to different estrogenic compounds, as environmental samples will typically comprise mixtures of contaminants. In the present study, male Japanese medaka (Oryzias latipes) were exposed to a range of low levels of three estrogens, 17β estradiol (E2), 17α ethynylestradiol (EE2), or bisphenol A (BPA) for either 24, 48, 72, or 96 hours and liver vitellogenin levels measured using real time RT-PCR. Vitellogenin expression was induced in fish exposed to the endogenous hormone E2 at ten-fold lower concentrations than in fish exposed to the environmental estrogen, EE2. In contrast, short-term exposure to low levels of bisphenol A, an environmental estrogenic contaminant, did not result in vitellogenin induction. It was also determined that a gene for the steroidogenic enzyme, 11β hydroxylase, is not significantly differentially regulated in response to E2 exposure, contrary to predictions.
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