title: Returning to normal? Assessing transcriptome recovery over time in male rainbow darter (Etheostoma caeruleum) liver in response to wastewater-treatment plant upgrades.
abstract: The present study measured hepatic transcriptome responses in male rainbow darter (Etheostoma caeruleum) exposed to 2 municipal wastewater-treatment plants (MWWTPs; Kitchener and Waterloo) over 4 fall seasons (2011-2014) in the Grand River (Ontario, Canada). The overall goal was to determine if upgrades at the Kitchener MWWTP (in 2012) resulted in transcriptome responses indicative of improved effluent quality. The number of differentially expressed probes in fish downstream of the Kitchener outfall (904-1223) remained comparable to that downstream of Waterloo (767-3867). Noteworthy was that year and the interaction of year and site explained variability in more than twice the number of transcripts than site alone, suggesting that year and the interaction of year and site had a greater effect on the transcriptome than site alone. Gene set enrichment analysis revealed a gradual reduction in the number of gene ontologies over time at exposure sites, which corresponded with lower contaminant load. Subnetwork enrichment analysis revealed that there were noticeable shifts in the cell pathways differently expressed in the liver preupgrade and postupgrade. The dominant pathways altered preupgrade were related to genetic modifications and cell division, whereas postupgrade they were associated with the immune system, reproduction, and biochemical responses. Molecular pathways were dynamic over time, and following the upgrades, there was little evidence that gene expression profiles in fish collected from high-impact sites postupgrade were more similar to those in fish collected from reference site. Environ Toxicol Chem 2017;36:2108-2122. © 2017 SETAC.
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Patricija
authors.initials: P
authors.lastname: Marjan
authors.affiliation: Center for Environmental and Human Toxicology and Department of Physiological Science, Genetics Institute, College of Medicine, University of Florida, Gainesville, Florida.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Martyniuk
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Meghan L M
authors.initials: MLM
authors.lastname: Fuzzen
authors.affiliation: Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada.
authors.forename: Deborah L
authors.initials: DL
authors.lastname: MacLatchy
authors.affiliation: Canada Center Inland Waters, National Water Research Institute, Aquatic Contaminant Research Division, Environment Canada, Burlington, Ontario, Canada.
authors.forename: Mark E
authors.initials: ME
authors.lastname: McMaster
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Servos
mesh_terms: D000818:Animals; D004784:Environmental Monitoring / Q000379:methods*; D063990:Gene Ontology; D008099:Liver / Q000737:chemistry / Q000187:drug effects*; D008297:Male; D009864:Ontario; D010471:Perches / Q000235:genetics / Q000502:physiology*; D012098:Reproduction / Q000187:drug effects; D045483:Rivers / Q000737:chemistry; D012621:Seasons; D059467:Transcriptome / Q000187:drug effects*; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*; D018508:Water Purification / Q000379:methods*
chemical_list: D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Aquatic toxicology; Ecotoxicogenomics; Rainbow darter; Temporal variability; Transcriptomics; Wastewater effluent upgrade