PRIMARILY CULTURED GILL EPITHELIA AS PROTOTYPES FOR ASSESSING FISH RESPONSE TO HEAVY METAL EXPOSURE

Abstract

The global call to reduce the number of fish used in toxicological evaluations has necessitated the need to develop in vitro systems as viable alternatives. This study investigated the use of primarily cultured gill cells to assess changes in gill physiology in response to heavy metal exposure. Rainbow trout (Oncorhynchus mykiss) gill epithelia were cultured on permeable filter supports using a Double Seeded Insert (DSI) primary culture technique. The cells, which are tolerant to freshwater application on the apical surface, were exposed to a range of concentrations of zinc (Zn) [1-100 μM], lead (Pb) [0.5-50 μM] and cadmium (Cd) [0.01-1.0 μM] for 24 h. The expression of heavy metal responsive genes metallothionein A (mtA) and B (mtB) were quantified using Reverse Transcription quantitative Polymerase Chain Reaction (RT qPCR). Results showed that Zn significantly (P < 0.05) enhanced the expression of mtA and mtB in the cultured gill epithelia while Pb significantly (P < 0.05) inhibited the expression of mtA. This study demonstrated that primarily cultured gill epithelia is capable of detecting bioavailable metals in water and thus shows promise as a surrogate for fish toxicity tests.