Induced Thermotolerance in the Pacific Oyster, Crassostrea Gigas

Pacific oysters, Crassostrea gigas, were subjected to heat shock at various temperatures under controlled laboratory conditions. These experiments demonstrated that exposure to sublethal temperatures dramatically enhances thermotolerance. Oysters exposed to a single nonlethal heat shock (37 degrees Celsius for 1 hour) acquired a transient tolerance to a subsequent exposure previously determined to be lethal (43 degrees Celsius for 1 hour). The induced thermotolerance (“thermal memory”) existed for at least 10 days after sublethal heat shock. Preliminary studies indicated that thermotolerance induction was correlated with the appearance of heat shock proteins in the 70-kD family (hsp-70), based on electrophoretic analysis of proteins from three different tissues, followed by immunoblot analysis with antibodies against hsp-70.