Genetic and environmental regulation of HSP70 expression

North Sea Mytilis edulis differ genetically from M. edulis from lower salinity in the Baltic Sea. Gammarus duebeni can tolerate a broad range of salinities, while Gammarus oceanicus is more limited in its salinity range. These populations were exposed to cadmium and the level of expression of a stress protein, HSP70, was analysed on Western blots. HSP70 is one of a family of ubiquitous heat shock proteins, about 70 000 Da, that are induced by a wide variety of Stressors. North Sea mussels had high levels and multiple forms of HSP70 and a low tissue concentration of cadmium. Baltic Sea mussels had low levels of HSP70 and accumulated three times the tissue concentration of cadmium as North Sea mussels. G. duebeni had varying levels of HSP70 and twice the tissue concentration of cadmium of G. oceanicus, which had no detectable HSP70 throughout the course of cadmium treatment. The quantity of HSP70 induced correlated well with survival in these four populations.