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Novel approaches for integrating chemistry, transcriptomics and physiology of caged fish to examine the impacts of contaminants of emerging concern.
Citation:
Perkins, E., T. Habib, B. Escalon, K. Jensen, M. Kahl, G. Ankley, Dan Villeneuve, AND N. Garcia-Reyero. Novel approaches for integrating chemistry, transcriptomics and physiology of caged fish to examine the impacts of contaminants of emerging concern. SETAC North America, Minneapolis, MN, November 12 - 16, 2017.
Impact/Purpose:
With improvements in analytical chemistry, more and more chemicals are being detected in the Great Lakes watershed. Conventional toxicity data are lacking for many of these, making it difficult to assess the potential hazards these chemicals, and their mixtures, may pose to Great Lakes aquatic life. This case study analyzed changes in the transcriptome of fish caged in a Great Lakes tributary stream to help link potential biological effects to chemical exposure in this complex system. It illustrates one approach that Region 5, and other regions across the country may employ to better link exposure to contaminants of emerging concern and their potential effects as a means to prioritize monitoring and management. This work directly supports Great Lakes Restoration Initiative Action Plan II.
Description:
Product Description:Many chemicals are being detected in the Great Lakes watershed, but it is not always clear which of these may be of concern and should be prioritized for monitoring or management. The current study investigates the use of novel biologically-based monitoring methods that can be used to identify potential effects associated with exposure to complex mixtures of chemicals in the environment. Biological responses can be statistically linked to chemical concentration information to identify chemicals and sources that may be of higher priority. The Great Lakes are impacted by the introduction of a large number of chemical of emerging concern at low concentrations in surface waters by wastewater treatment plants (WWTP). Here we present novel approaches for understanding the potential impacts of the individual components of complex mixtures using effects based monitoring and transcriptomics. We applied these approaches to assess the hypothesis that the discharge of chemicals by WWTP into Saint Louis Bay, Duluth, MN would cause estrogenic effects on fish exposed in the bay. To test the hypothesis, Fathead minnows were deployed in cages for 2, 4 or 8 days at three locations near two different WWTP plant discharge sites in the Saint Louis Bay, Duluth, MN and one upstream reference site. Surface water chemistry was determined from grab samples of water near deployed fish on days 2, 4 and 8. The biological impact of 51 chemicals detected in the surface water was determined using biochemical endpoints, in vivo and in vitro exposure activity ratios for biological and estrogenic responses, transcriptional pathway analysis, ovaryfunction gene set enrichment analysis, known chemical:gene interactions from Ingenuity Pathway Analysis (IPA) and Comparative Toxicogenomics knowledge bases, and analysis of the co-variance of ovary gene expression with surface water chemistry. Thirty-two chemicals were significantly linked by co-variance with expressed genes. While no significant impact on estrogenic endpoints was observed in male or female minnows, bisphenol A was identified by chemical:gene co-variation as the most impactful estrogenic chemical across all exposure sites. This was consistent with identification of estrogenic effects on gene expression, high bisphenol A exposure activity ratios across all test sites and historical analysis of the study area. Analysis of ovary transcriptomics also indicated that fish were exposed to chemotherapeutics, immunosuppressants and other therapeutics at WWTP discharge site consistent with treatment of a hospital waste stream at the WWTP. Overall, this approach appears useful in examining the impacts of complex mixtures on fish and offers a potential route in linking chemical exposure to estrogenic effects that may reduce population sustainability. The contents of this abstract neither constitute nor necessarily reflect US EPA or US ACE policy.