The induction of Hsp70 synthesis by non-lethal heat shock confers thermotolerance and resistance to lethal ammonia stress in the common carp, Cyprinus carpio (Linn)

Exposure to heat-shock protein (Hsp) stimulating factors induces Hsp accumulation and confers tolerance to lethal ammonia stress on the common carp Cyprinus carpio. This study investigated whether a non-lethal heat shock bestowed similar protective effects against ammonia and induced thermotolerance, both thought to be rendered by increased amounts of Hsps. The 30-min lethal temperature (30 min LHT) and 1-h lethal ammonia concentration (1 h LCT) for this species occurred at 41 degrees C and 14.2 mg/L NH3 respectively. Heating juvenile carp (5 cm) from 28 degrees C to 32, 34 and 38 degrees C, with a subsequent 8-h recovery period augmented tolerance to lethal heat and ammonia perturbation by two to threefold as compared with animals held at 28 degrees C. Protection occurred in conjunction with Hsp70 accumulation in gills, substantiating the role of this Hsp in enhancing the stress tolerance of common carp.