Abstract

Urbanization and industrial activity introduce a variety of pollutants into freshwater ecosystems, including polycyclic aromatic hydrocarbons (PAHs), which are known to cause physiological stress in aquatic organisms. One common response to PAH exposure in fish is the induction of the detoxification enzyme cytochrome P450 1A (CYP1A), which is frequently used as a biomarker for contaminant exposure. This study examined the effects of contaminated sediments on fish by evaluating both gill histology and CYP1A protein expression. Fish collected from a clean site were exposed to sediments collected from multiple urban waterways in the Toronto region. Following exposure, gill tissues were analyzed for structural changes and protein expression was evaluated using SDS-PAGE and Western blot techniques. Histological analysis revealed structural differences between control and exposed fish, including epithelial hyperplasia and lamellar damage in fish exposed to contaminated sediments, suggesting physiological stress in gill tissues. Rhodamine actin imaging confirmed successful protein transfer across most samples and was used as a loading control to normalize CYP1A signal. Although technical challenges limited final CYP1A detection, faint CYP1A bands were observed during troubleshooting experiments in several samples. Notably, this study represents the first detection of CYP1A protein expression in Redside Dace tissues. Together, these findings provide preliminary insight into how contaminated sediments may influence both tissue structure and detoxification pathways in freshwater fish and contribute to understanding pollutant impacts on sensitive species.

Advisor

Williams, Rebecca

Department

Biology

Disciplines

Biochemistry | Cell Biology

Publication Date

2026

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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Available for download on Thursday, May 15, 2031

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© Copyright 2026 Emma L. Longenecker