Effects of temperature changes on oxidative stress and antioxidant defense system in the Zhikong scallop Chlamys farreri

To understand the effects of temperature changes on the Zhikong scallop Chlamys farreri, we measured antioxidant-related enzymatic activities and oxidative-stress-related biomarkers, including the H2O2 and malondialdehyde (MDA) contents, in response to temperature changes (12 degrees C and 28 degrees C) compared with the control temperature of 20 degrees C, over 72 h. The scallops exposed to different temperature changes showed increased H2O2 levels with activation of antioxidant-related enzymes compared with the control during 12-24 h exposures. Following the temperature change, the MDA concentration was elevated for 24 h; however, after 24 h under low-temperature conditions, it decreased to levels similar to those seen in the control group, possibly owing to the defensive effects of antioxidant enzymes. The detoxification enzyme, glutathione S-transferase, showed a similar activity trend to those of other antioxidant enzymes for times up to 12 h; however, it did show inhibitory action after 24 h in response to the temperature changes relative to the control. These results indicate that C. farreri may experience greater oxidative stress in high-temperature environments. Overall, these findings indicate that temperature changes led to reactive oxygen species-mediated oxidative stress, resulting in cellular damage and activation of the antioxidant defense system in the Zhikong scallop.