Bivalve mollusks are frequently subjected to fluctuations of dissolved oxygen concentration in the environment which can represent a significant threat to bivalve antioxidant status. In this work the effects of hypoxia on hemocyte reactive oxygen species (ROS) production and level of mitochondrial potential as well as the activity and expression level of catalase (CAT) and superoxide dismutase (SOD) in gills of Crassostrea gigas were investigated after 24 h and 72 h exposure. 24 h hypoxia promoted an increase of mitochondrial membrane potential in agranulocytes and induced ROS accumulation in granulocytes. 72 h exposure substantially decreased hemocyte mitochondrial potential and intracellular ROS level in all hemocyte types. No significant changes in the activity of CAT in gills were observed following both 24 h and 72 h exposure periods compared to control. SOD activity in gills decreased after 72 h exposure to hypoxia but did not change under 24 h hypoxia. Significant up-regulation of SOD gene and no changes in expression level of CAT were observed in all experimental groups. The results indicate an overall shift in antioxidant status in gills and hemocytes of the Pacific oyster that may act as compensatory mechanisms to maintain redox homeostasis after a short-term (24 h) exposure and represent the occurrence of oxidative stress conditions at the end of 72 h hypoxia.

双壳类软体动物经常受到环境中溶解氧浓度波动的影响，这可能对双壳类抗氧化状态构成重大威胁。在这项工作中，缺氧对巨牡蛎（Crassostrea gigas）鳃中血细胞活性氧（ROS）产生和线粒体电位水平以及过氧化氢酶（CAT）和超氧化物歧化酶（SOD）的活性和表达水平的影响在暴露 24 小时和 72 小时后进行调查。24 h 缺氧促进粒细胞线粒体膜电位的增加并诱导粒细胞中的 ROS 积累。72 小时暴露显着降低了所有血细胞类型的血细胞线粒体电位和细胞内 ROS 水平。与对照相比，在暴露 24 小时和 72 小时后，未观察到鳃中 CAT 的活性发生显着变化。暴露于缺氧 72 小时后鳃中的 SOD 活性下降，但在 24 小时缺氧下没有变化。在所有实验组中均未观察到 SOD 基因的显着上调和 CAT 表达水平的变化。