A COMPARISON OF RT-PCR AND NORTHERN BLOT ANALYSIS IN QUANTIFYING METALLOTHIONEIN MESSENGER-RNA LEVELS IN KILLIFISH EXPOSED TO WATERBORNE CADMIUM

Reverse transcriptase PCR (RT-PCR) was evaluated as an alternative to Northern blot analysis in quantifying levels of metallothionein (MT) m RNA. Killifish were exposed to water-borne cadmium (Cd) at concentrati ons ranging from 0 ppb to 46 ppb and their levels of hepatic MT mRNA w ere quantitated by both Northern blot analysis and RT-PCR. Both method s provided comparable results in that low constitutive levels of MT mR NA were observed in fish exposed to clean water, dose-responsiveness w as seen in fish exposed to increasing concentrations of Cd, and sensit ivities of both techniques were similar in detecting induced levels of MT mRNA in Cd exposed fish. These results suggest that RT-PCR may pro vide a sensitive and quantitative method to evaluate gene expression i n fish from small, non-invasively sampled tissues.