ABSTRACT

Bivalve molluscs are widespread in coastal environments, where they are subjected to a wide range of environmental fluctuations, which can represent a significant impact to their antioxidant status. Hypoxia is a global problem affecting the world’s shallow waters, which is forecast to increase in coastal areas due to anthropogenic pressure and global warming. In this work, the effects of 24 h exposure to hypoxia (0.2 mg O₂ l⁻¹) on antioxidant parameters of Mytilus galloprovincialis were investigated. Functional parameters of gill samples (the number of dead cells and intracellular reactive oxygen species concentration) were measured by flow cytometry, and the expression level of antioxidant enzyme genes (CAT, GST, SOD) as well as NADH dehydrogenase subunit 2 were analysed using transcriptome analysis. Gills responded to oxygen depletion by an increased total number of intracellular reactive oxygen species, which was accompanied with high levels of mortality of cells (10 times higher compared with control). Significant increases of Mn-superoxide dismutase, glutathione S-transferase and NADH dehydrogenase subunit 2 gene expression levels were observed. Hypoxia did not cause changes in the expression of CAT. The results indicate an overall shift in antioxidant parameters in gill tissue that may represent a certain level of oxidative stress in mussels and decreased capacity of the antioxidant system to maintain redox homeostasis after exposure to hypoxia.

摘要

双壳类软体动物广泛存在于沿海环境中，在那里它们受到各种环境波动的影响，这可能对其抗氧化状态产生重大影响。缺氧是影响世界浅水区的全球性问题，预计由于人为压力和全球变暖，沿海地区的浅水区会增加。在这项工作中，24 小时暴露于缺氧 (0.2 mg O ₂ l ^-1 ) 对Mytilus galloprovincialis抗氧化参数的影响被调查。通过流式细胞术测量鳃样品的功能参数（死细胞数量和细胞内活性氧浓度），并使用转录组分析抗氧化酶基因（CAT、GST、SOD）以及NADH脱氢酶亚基2的表达水平分析。鳃通过增加细胞内活性氧的总数来响应氧耗竭，这伴随着高水平的细胞死亡率（与对照相比高 10 倍）。观察到Mn-超氧化物歧化酶、谷胱甘肽S-转移酶和NADH脱氢酶亚基2基因表达水平的显着增加。缺氧不会引起CAT表达的变化。