HSP70 levels in physiologically stressed Baltic Sea mussels

Mussels, Mytilus edulis L., front the Baltic Sea Mere exposed to stressful cadmium and temperature environments. The expression of the 70 000 kD heat shock protein family (HSP70) and of several organismal responses was observed in two phases. Mussels exposed to 20 degrees C for one day had higher levels of HSP70 than controls at 4 degrees C, with 20 mu g litre(-1) cadmium or without cadmium. The higher temperature increased respiration and ammonia excretion and decreased clearance rare and scope for growth. In the second phase, mussels pretreated at 20 degrees C for 5 days and reacclimated to 4 degrees Cfor 5 days still showed significantly elevated HSP70, with 20 mu g litre(-1) cadmium and without cadmium. The organismal responses in the second phase Mere much less affected by treatment, although scope for growth declined in pretreated animals exposed to cadmium. HSP70 seems to be a suitable indicator of both present and recent stress. A functional relationship between HSP70 levels and adaptation to heat and cadmium is suggested but not established. (C) 1998 Elsevier Science Ltd. All rights reserved.