Stress proteins in the polychaete annelid Nereis diversicolor induced by heat shock or cadmium exposure

We have exposed the polychaete annelid Nereis diversicolor to heat shock or cadmium. Two-dimensional electrophoresis and fluorography techniques indicated the synthesis by the worms of at least 15 stress proteins including the universal one referred to as 'stress 70' and a lot of low molecular weight (LMW) proteins. 'Stress 70', synthesized by Nereis diversicolor in response to both stressors, appeared on fluorograms as an array of three charge isomers. We observed that most of the LMW stress proteins built up in response to heat shock were different from those observed after cadmium exposure. Furthermore, Nereis, which resists high levels of cadmium, did not appear to synthesize metallothioneins, small proteins known to prevent cellular damage by sequestering toxic metal ions. As no cadmium-binding proteins were visualized on fluorograms, the mechanism by which Nereis resists cadmium injury remains to be disclosed.