CRUSTACEANS AS MODELS FOR METAL METABOLISM .1. EFFECTS OF THE MOLT CYCLE ON BLUE-CRAB METAL METABOLISM AND METALLOTHIONEIN

The discontinuous-growth process (i.e. the molt cycle) of crustaceans and their ability to accumulate and regulate metals provide a unique system to study how alterations of specific metabolic processes can affect metal metabolism. We have shown that the extensive physiological and biochemical changes that take place during the molt cycle, particularly after ecdysis, affect metal metabolism in the blue crab, Callinectes sapidus. For example, there are significant changes in the concentrations of copper and zinc in both the hemolymph and the digestive gland Some of these occur quite rapidly. It has been possible to demonstrate shifts in the cytosolic distribution of copper and zinc in the digestive gland within 90 min of ecdysis that are correlated positively with the degadation of hemocyanin and the liberation of copper. A descriptive model has been developed that describes fluxes of copper and zinc during the molting process.