Portland State University. Department of Biology
Kim H. Brown
Term of Graduation
Date of Publication
Doctor of Philosophy (Ph.D.) in Biology
1 online resource (xi, 131 pages)
Endocrine disrupting chemicals (EDCs) pose a threat to biodiversity at the individual, population, and ecosystem level, as they can interfere with processes that are responsible for regulating metabolism, development, behavior, and reproduction in living organisms. 17α-ethynylestradiol (EE2) is a synthetic estrogen and EDC utilized in pharmaceutical and livestock industries, and contaminates waterways worldwide. This research explores the effects of dose-dependent and multi-generational exposure of EE2 in three strains of zebrafish. High dose (10-25 ng/L EE2) exposure led to compete reproductive failure, as well as significantly decreased survival and growth. A period in clean water (depuration) after exposure allowed for some recovery of growth, but zebrafish never regained reproductive abilities. Low dose (1 ng/L EE2) exposure over the course of three generations led to an increase in the number of eggs produced (clutch size) by Generations 1 and 2, but a reduction in embryo hatch success in all generations, and therefore an overall reduction in reproductive capability. Depuration allowed for a return to normal clutch size, but hatch success remained low. When these results were separated by strain of zebrafish (AB, TU, and WIK), the WIK strain experienced the greatest variance in response after exposure and depuration, suggesting greater sensitivity to EE2. The findings from this study show that in a laboratory setting, one generation of exposure to EE2 concentrations above 10 ng/L causes irreversible damage to zebrafish, while multi-generational exposure to low concentrations of EE2 may slowly diminish reproductive capability, most likely caused by alterations to sperm, impact to the quality of the egg, and genetic and/or epigenetic effects that interrupt embryo development.
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Foster, Decatur Mitochondria, "Investigating Dose-Dependent, Multi-Generational, and Strain-Specific Effects of 17α-ethynylestradiol Exposure in Zebrafish (Danio rerio)" (2020). Dissertations and Theses. Paper 5622.