| Marsupenaeus japonicus is an important cultured species of marine shrimp in China. Its characteristics include a varied diet, fast growth, and tolerating periods out of water, as well as being suitable for live shrimp marketing and long-distance transportation. The suitable growth temperature of M. japonicus is 23℃~32℃. The culture cycle of M. japonicus is seriously affected by low winter temperatures in northern China, which increases the costs of parent shrimp overwintering. Therefore, it is necessary to breed new varieties with low temperature tolerances. M. japonicus was exposed to water at 10℃, 16℃, and 22℃ for 72 h, with M. japonicus exposed to water at 28℃ used as the control group. The results showed that the total antioxidant capacity (T-AOC), superoxide dismutase (SOD) enzyme activity, and GSH content in the gill and hepatopancreas decreased first, then increased and then decreased, while the MDA content and caspase-3 enzyme activity increased over time. The relative expression of the SOD and Caspase-3 genes decreased first, then increased, then decreased, and continued to increase, which was similar to their corresponding changes in enzyme activity. In order to prove that low temperature stress caused damage to the body of M. japonicus, a TUNEL test was performed. It was found that the apoptosis rate increased significantly with the extension of the stress time. The apoptotic rates of the gill control group, 3 h at 10℃, and 72 h at 10℃ were 2.03%, 6.20%, and 26.27%, respectively. The apoptotic rates of the hepatopancreas cells were 1.06%, 25.65%, and 42.33% for these exposure times, respectively. In conclusion, low temperature stress reduced the antioxidant capacity of M. japonicus, destroyed the original balance of the internal environment, and then led to oxidative damage. In this study, the changes in cell apoptosis and the antioxidant status of M. japonicus under low temperature conditions provided data that support the need to cultivate new varieties with low temperature tolerances. |
