Meeting Abstract
Estrogens present in the environment interfere with endocrine function and cause decreased fecundity, fitness, and sperm production in fish, as well as feminization of male fish. Physiological effects and alterations of gene expression resulting from estrogen exposure have been thoroughly described in fish. Despite this, little is known about epigenetic alterations, although these changes are believed to provide the critical linkage of gene expression with the development of adverse effects at higher biological levels. This study investigates alterations of DNA methylation of estrogen receptor alpha (ER&αlpha;) in brain and liver tissue in fathead minnows (Pimephales promelas) exposed to either 2.5 ng/L or 10 ng/L of the synthetic exogenous estrogen, 17α-ethynylestradiol (EE2). Methylation differences were assessed across all CpG sites in a 2.5KB region encompassing exon 2 and 1.5KB upstream of the start site of the ER&αlpha; gene by targeted deep sequencing of bisulfite treated DNA isolated from liver and brain tissue. Additionally, DNA methylation was assessed from fish depurated for 7 and 14 days to determine the kinetics of methylation. Finally, relationships between ER&αlpha; methylation status and gene expression for individual fish were evaluated. Results from this work will provide information regarding the drivers of response to estrogens and the linkage between alterations in methylation status and gene expression.
