The dynamics of protein and metal metabolism in acclimated and Cd-exposed freshwater crabs (Potamonautes warreni)

Climatic and man-made impacts induced dynamic molecular responses in the South African freshwater crab, Potamonautes warreni. Adult crabs exhibited MT-like protein, binding Cd (0.02 μmol g−1 wet mass±0.02), Cu (0.326 μmol g−1 wet mass±0.15), and Zn (0.534 μmol g−1 wet mass±0.20). The native protein binding Cd, Cu, and Zn showed a respective molecular mass (M) of 9.10 kDa±1.74, 8.95 kDa±1.66, and 9.32 kDa±0.93. With exposure to 0.2 mg Cd2+ l−1 for up to 21 days in 50% of these crabs approximately 90% of Cd was bound to the MT-like protein component (8.54 kDa±1.64), coinciding with a Zn-bound MT-like component (8.2 kDa±1.54). Less than 10% were bound in the high M protein component, suggesting a protective function of the protein. In the remaining crabs metals were bound to protein (6.8 kDa) with a predominant Cu-binding component.