Impact of municipal wastewater effluent exposure on the transcriptome of fathead minnows
Date
2019-09-19
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Abstract
Municipal wastewater effluent (MWWE) is a mixture of nutrients and contaminants, including pharmaceuticals and personal care products (PPCPs), released into our waterways affecting non-target animals such as fishes. The objective of this thesis was to examine the impact of MWWE exposure on a native fish species in the Bow River. The hypothesis was that MWWE exposure disrupts molecular responses, potentially altering organismal physiology and fitness in the fathead minnow (FHM: Pimephales promales). Caging of FHM at the site closest to the wastewater treatment plant (WWTP) in the Bow River resulted in altered liver transcripts of genes involved in xenobiotic metabolism, cholesterol metabolism, and oxidative stress. Also, the livers of fish caged at the site near the WWTP showed altered methylation patterns compared to the upstream site suggesting epigenome modifications in response to MWWE exposure. Offspring of the MWWE exposed fish bred and reared in clean water also showed modulation of gene expression in the liver, similar to that of their parents, suggesting heritable effects due to parental exposure to MWWE. Exposure of FHM larvae to MWWE at dilutions similar to that reported in the Bow River disrupted the transcript abundance of genes involved in metabolism and oxidative stress, and this corresponded with diminished cortisol stress performance and altered larval behaviour. Overall, MWWE exposure disrupts the molecular responses essential for stress, growth and xenobiotic metabolism in the FHM, and some of these changes are evident even in the next generation. The results indicate that MWWE exposure affects genome methylation patterns, and suggest that epigenome modification may be playing a role in the multigenerational effects seen due to parental exposure in the FHM.
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Keywords
Transcriptomics, RNA-Seq, Fathead minnow liver, Fathead minnow larvae, Methylomics, Epigenetics
Citation
Hooey, C. J. (2019). Impact of municipal wastewater effluent exposure on the transcriptome of fathead minnows (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.