INDUCED THERMOTOLERANCE IN THE PACIFIC OYSTER, CRASSOSTREA-GIGAS

Pacific oysters, Crassostrea gigas, were subjected to heat shock at va rious temperatures under controlled laboratory conditions. These exper iments demonstrated that exposure to sublethal temperatures dramatical ly enhances thermotolerance. Oysters exposed to a single nonlethal hea t shock (37 degrees C for 1 h) acquired a transient tolerance to a sub sequent exposure previously determined to be lethal (43 degrees C for 1 h). The induced thermotolerance (''thermal memory'') existed for at least 10 days after sublethal heat shock. Preliminary studies indicate d that thermotolerance induction was correlated with the appearance of heat shock proteins in the 70-kD family (hsp-70), based on electropho retic analysis of proteins from three different tissues, followed by i mmunoblot analysis with antibodies against hsp-70.