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Epigenetic and transcriptomic changes resulting from long-term exposure to contaminant mixture associated with agricultural land use
Citation:
See, Mary Jean, W. Huang, N. Cipoletti, H. Schoenfuss, D. Sullivan, AND A. Biales. Epigenetic and transcriptomic changes resulting from long-term exposure to contaminant mixture associated with agricultural land use. SETAC North America, Pittsburgh, PA, November 13 - 17, 2022. https://doi.org/10.23645/epacomptox.22183819
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Description:
Epigenetics, the interface between the environment and genome, can change quickly in response to environmental stressors. Epigenetic modifications may cause changes in gene expression leading to potential adverse biological outcomes. Here, we present differential DNA methylation and mRNA expression from liver tissue of Pimphales promelas (fathead minnows, FHM) exposed to a mixture of eight chemicals for two generations. The mixture of eight contaminants (alkyl phenols, atrazine, BPA, bromacil, DEET, estrone, metolachlor, and TBEP) was developed from a watershed survey around the Laurentian Great Lakes performed by USGS from 2010 to 2014. The mixture represents chemicals found in waters receiving inputs from agricultural land use. Adult FHM were exposed to the mixture in a flow-through system for three months at a concentration approximately the same as (medium), ten times greater than (high), and ten times lower than (low) the highest measured environmental concentration along with a solvent control. Fish were allowed to breed during this period, then sacrificed for the measurement of apical endpoints and collection of tissues. Offspring of initial exposed adults were reared to adulthood in the flow-through system and continuously exposed to the same treatments. They were allowed to breed, then sacrificed for measurement of apical endpoints and collection of tissues. DNA and RNA were isolated from liver tissue then sequenced using reduced representation bisulfite sequencing (RRBS) and global mRNA sequencing. Differential DNA methylation patterns along with gene expression results suggest a response to a weakly estrogenic treatment. Males in both exposed generations displayed an increasing trend in vitellogenin expression while females in both generations showed little or no response to the exposure. Effects of the complex mixture representing agricultural land use were weakly estrogenic and we found offspring males showed a decreasing trend in secondary sex characteristics in response weak estrogenic exposure. Our findings demonstrate epigenetic modifications occur concurrently with gene expression changes related to reproductive end points along an adverse outcome pathway and demonstrate the relevance of evaluating biological effects of environmental mixtures.
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DOI: Epigenetic and transcriptomic changes resulting from long-term exposure to contaminant mixture associated with agricultural land use