EFFECT OF ACUTE TEMPERATURE CHANGE ON ANTIOXIDANT ENZYME ACTIVITIES AND LIPID PEROXIDATION IN THE ARK SHELL SCAPHARCA SUBCRENATA (LISCHKE, 1869)

The present study investigated whether an acute temperature change affected hemolymph antioxidant enzyme activities and lipid peroxidation in ark shell Scapharca subcrenata transferred from 22 degrees C to 17 degrees C, 27 degrees C, and 32 degrees C for 72 h and then transferred back quickly to 22 degrees C for a 6-h recovery period. Superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities and malondialdehyde (MDA) contents [in cell-free hemolymph (CFH) and hemocyte lysate (HL)] were chosen as biomarkers of acute temperature stress. The results demonstrated that CFH and HL SOD activities decreased significantly (P < 0.05) after ark shells were exposed to 32 degrees C for 72 h and returned to normal temperature. Glutathione peroxidase activity in CFH of ark shells exposed to 32 degrees C increased significantly (P < 0.01) at 12 h, but then decreased significantly (P < 0.01) at the end of the recovery period. Malondialdehyde contents in the CFH and HL of stressed ark shells, regardless of temperature (17 degrees C, 27 degrees C, or 32 degrees C), were lowest at 1 h of the recovery period, and recovered completely by the end of the experiment. In contrast, no difference was observed in CFH or HLMDA contents between the 17 degrees C and 27 degrees C groups. In conclusion, S. subcrenata had high tolerance to an acute decrease and increase in seawater temperature, but oxidative stress in ark shell hemolymph increased significantly with temperature and time, such as 32 degrees C and greater than 72 h.