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RESEARCH PRODUCT

Quantification of cadmium-induced metallothionein in crustaceans by the silver-saturation method

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Metallothionein (MT) has been proposed as a specific biochemical probe for metal exposure of aquatic organisms. It is recognized that its usefulness as a monitoring tool depends on the full understanding of its function and on the possibility of measuring its concentration in tissues. Therefore the study of MT in crustaceans is interesting from two different points of view: the need to understand mechanisms associated with the toxicology of metals, and the potential use of this protein for monitoring metal-contamined environments. Several methods have been developed for quantitative measurements of MT in biological samples. Immunochemical and electrochemical procedures are reliable techniques but they require sophisticated equipment and highly trained staff. In the present work, modifications to the silver-saturation method have been developed for the quantitative determination of MT in crustacean tissues, estimating silver concentrations by flame in an atomic absorption spectrophotometer. Cadmium and MT were measured both in Artemia and Procambarus clarkii after sublethal exposure to cadmium. An increase in MT content was recorded in crustacean tissues after 12 h of cadmium exposure. A high responsiveness was found in MT induction by cadmium in the two crustaceans and there was a clear relationship between cadmium concentration in water and MT levels in tissues. The silver-saturation assay may be a rapid assay technnique for biomonitoring purposes.