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Genome-wide Assessment of CpG-methylation Changes in Male Fathead Minnows after Exposure to 17α-ethynylestradiol (EE2)
Citation:
Huang, W., D. Bencic, R. Flick, AND A. Biales. Genome-wide Assessment of CpG-methylation Changes in Male Fathead Minnows after Exposure to 17α-ethynylestradiol (EE2). 2018 SETAC North America Meeting, Sacramento, CA, November 04 - 08, 2018.
Impact/Purpose:
Poster presented at SETAC 2018 North America
Description:
17α-ethynylestradiol (EE2) is one of widely-used estrogenic chemicals present almost ubiquitous in aquatic environments throughout the United States and some other countries. EE2, acting as an endocrine disrupting compound, can disrupt hormonal homeostasis, leading to developmental disorders, cancer and other diseases. Exposure to EE2 is known to induce expression of vitellogenin, a precursor protein of egg yolk normally only expressed in female fish, in male fish. However, the underlying epigenomic changes associated with vitellogenin induction and phenotypic changes (e.g. feminization), are not well understood. This study was designed to gain insights into such underlying epigenetic regulation mechanisms by assessing genome-wide DNA methylation changes in CpG sites using the reduced representation bisulfite sequencing (RRBS) technology. Taking advantage of the newly improved assembled fathead minnow genome and annotation in house, we used fathead minnow as the model organism to study DNA methylation changes before and after exposure to EE2. In this study, two groups of male fathead minnow fish, each with 16, were exposed 2.5ng/L and 10ng/L EE2 for 48 hours, respectively. Two additional groups not exposed to EE2 were used control groups: one male group for negative control and the other female group for positive control. We assessed and compared DNA CpG methylation changes immediately after EE2 exposure in both male liver and brain tissues. To address question about whether these methylation changes are temporary or potentially long-term, we also identified and compared methylation CpG patterns of two groups of male fish after 7-day and 14-day depuration of EE2, respectively. This was done separately for liver and brain tissues. Overall, we found that a few of CpG regions were subjected to significant methylation changes immediately after EE2 exposures in male liver tissue, and both number of affected CpG sites and magnitude of changes were smaller in male brain tissue. In addition, our results also suggest that CpG-sites methylation changed quickly after exposure to EE2 while most such methylation changes were reversible after depuration of EE2.
