The effects of cadmium on the olfactory system of larval zebrafish
Matz, Carlyn Janel
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Cadmium (Cd) is a toxic metal known to accumulate in and have adverse effects on the olfactory systems of fish. The objective of this project was to investigate the effect of cadmium on zebrafish larvae, specifically the effects on the olfactory system at cellular and functional levels. Zebrafish larvae (72 hours post fertilization) were exposed to sublethal concentrations of cadmium (0.5, 1, 5, and 10 µM) for 96 h. Whole-body cadmium accumulation during this exposure period as quantified using GFAAS (graphite furnace atomic absorption spectroscopy) was found to increase with both exposure length and concentration. Using a transgenic strain of hsp70/eGFP (heat shock protein 70/enhanced green fluorescent protein reporter gene) zebrafish, dose-dependent induction of the heat shock response was observed in the olfactory epithelium. Expression of hsp70/eGFP in the olfactory epithelium was a highly sensitive biomarker for the effects of cadmium in the olfactory system with a lowest observed effects concentration (LOEC) of 0.5 µM Cd. Strong induction of the transgenic reporter gene correlated closely with cell death (LOEC of 5 µM Cd) and histological alterations (LOEC of 1 µM Cd) in the olfactory epithelium of zebrafish larvae following cadmium exposure. Additionally, loss of sensory cilia from the surface of the olfactory epithelium was observed in larvae exposed to 5 and 10 µM Cd. Furthermore, behaviour tests to assess olfactory function revealed sensory deficits, likely due in part to the cadmium-induced degeneration of the olfactory epithelium (p
DegreeDoctor of Philosophy (Ph.D.)
SupervisorKrone, Patrick H.
CommitteeRawlings, Norman C.; Kulyk, William M.; Hontel, Alice; Blakley, Barry R.; Weber, Lynn P.