Functional Transcriptomics of Native Canadian Fish Species

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The studies will focus on the characterization of biological pathways that regulate reproduction in fish native to Canadian freshwater ecosystems, and alterations of which can be used as indicators of potential health risks. The aim of the proposed research is to compare differences in sensitivity of fishes to a model environmental stressor of relevance to Canadian water bodies, and to elucidate the molecular basis for these differences. Target fish species are the northern pike (Esox lucius) and the fathead minnow (Pimephales promelas, FHM). The stressor to be investigated is exposure to estrogenic chemicals. Estrogens are considered reproductive toxicants of concern in Canadian ecosystems, and estrogenic potentials are associated with numerous anthropogenic activities including sewage treatment plant effluents, and more recently with oil sands process water. This work will study transcriptome-wide gene expression patterns and associated further upstream physiological functions (vitellogenin; sex steroids; steroid synthesis/metabolism; gonad and liver histology and somatic indices; condition; gross morphology; fertility; fecundity) in both test species under field and laboratory conditions, and after exposure to a model estrogen (ethinylestradiol) using mutual information based biological network analyses. This will allow for comparison of molecular regulation of reproduction between species and its disruption by estrogenic chemicals, and will enable assessment of species-specific sensitivity and identification of biological targets in response to exposure to estrogens. This will represent an important step towards better understanding of the basic biology of fishes native to Canada, and how it can be influenced by changes in their environment. The data will serve as a foundation for the assessment of the impacts of environmental estrogens to Canadian freshwater fish species. Finally, this work will develop specific biological markers to elucidate the mechanism by which estrogens interfere with processes relevant to the long-term fitness of fish. While focusing on only two species and one model chemical, the approaches to be developed will be applicable to other species and stressors, and thus, will be of general relevance to the field.