COPPER AND ZINC EXPOSURE OF ZEBRAFISH, BRACHYDANIO-RERIO (HAMILTON-BUCHAMAN) - EFFECTS IN EXPERIMENTAL LISTERIA INFECTION

To investigate the effects of heavy metals on susceptibility of fish t o Listeriosis, normal zebrafish, Brachydanio rerio (Hamilton-Buchanan) , were exposed to varying concentrations of zinc (0.05, 0.15, and 0.25 mg/liter) and copper (0.05, 0.10, and 0.15 mg/liter). During copper e xposure, this heavy metal did not accumulate in zebrafish kidney. Unli ke copper, a small amount of zinc accumulated in kidneys of fish expos ed at 0.25 mg/liter, To estimate the effects of this heavy metal on li sterial infection, the mortality of fish and the number of viable bact eria in fish kidney were determined at various times (1, 4, 7, and 10 days) after ip challenge with Listeria monocytogenes (strain 31386, se rotype 4b), The results indicate that the number of colony-forming uni ts in zinc-exposed fish decreased at 4, 7, and 10 days after challenge with 0.2 x LD(50) of viable bacteria. In contrast, copper-exposed fis h indicated both decreases and increases in the number of colony-formi ng units depending on the concentration of L. monocytogenes used. (C) 1996 Academic Press, Inc.