Stress responses to rapid temperature changes of the juvenile sea cucumber (Apostichopus japonicus Selenka)

Activities of hexokinase (HK), pyruvate kinase (PK), superoxide dismutase (SOD) and catalase (CAT) and Hsp70 level were measured to evaluate the response of the commercially important sea cucumber (Apostichopus japonicus Selenka) to rapid temperature changes in laboratory. Animals were subjected to a higher temperature (from 10 to 20°C) (Tinc treatment) or to a lower temperature (from 20 to 10°C) (Tdec treatment) for 72h. At 1, 3, 12, 24, 72h of exposure, animals were removed and prepared for further analysis. Results showed that the effect of acute temperature changes on enzyme activities was significant. In Tinc treatment, activities of SOD and CAT increased immediately. The significant enhancement of SOD and CAT activities suggested that oxidative stress increases significantly when ambient temperature increasing from 10 to 20°C. The up-regulation of Hsp70 in Tinc and Tdec treatments indicated that Hsp70 was a bioindicator of thermal stress in the sea cucumber, and the expression pattern depended on the thermal treatment.