The green microalgae Closterium ehrenbergii is an ideal organism for ecotoxicology assessments; however, its toxicogenomics has been insufficiently examined. Here, we identified three iron/manganese superoxide dismutase (SOD) genes (designated as CeFeSOD1, CeFeSOD2, and CeMnSOD) from C. ehrenbergii and examined their expressional patterns for four metals (iron, manganese, copper, and nickel). These genes encoded 362, 224, and 245 amino acids, respectively; signal-peptide analysis showed that they were differentially located in chloroplasts, cytosol, or mitochondria. Real-time PCRs revealed differential expression patterns according to metal and doses. Interestingly, CeSODs displayed no noticeable changes to treatment with their corresponding cofactor metals, iron or manganese, even at high doses. However, they were obviously up-regulated under toxic metal (copper and nickel) exposure, exhibiting approximately 10.8- and 4.4-fold increases, respectively. Copper (0.2 mg/L) dramatically stimulated intracellular reactive oxygen species (ROS) formation, increased SOD activity, and reduced photosynthetic efficiency in C. ehrenbergii. These results suggest that CeFeSODs and CeMnSOD might be involved in protecting cells against damage and oxidative stress caused by non-cofactor metals, such as copper and nickel. These genes were sensitively responsive at levels well below the EC₅₀, showing that they can be used as molecular biomarkers to assess the toxicity of specific metal contaminants.

绿色微藻梭状芽胞杆菌是进行生态毒理学评估的理想生物。然而，其毒理基因组学尚未得到充分检查。在这里，我们从C. ehrenbergii中鉴定了三个铁/锰超氧化物歧化酶（SOD）基因（分别称为CeFeSOD1，CeFeSOD2和CeMnSOD），并检查了它们在四种金属（铁，锰，铜和镍）中的表达模式。这些基因分别编码362、224和245个氨基酸。信号肽分析表明它们位于叶绿体，胞质溶胶或线粒体中的位置不同。实时PCR显示根据金属和剂量的差异表达模式。有趣的是CeSOD即使使用高剂量的辅因子金属，铁或锰，也无明显变化。但是，它们在有毒金属（铜和镍）的暴露下明显上调，分别增加约10.8和4.4倍。铜（0.2 mg / L）极大地刺激了C. ehrenbergii中的细胞内活性氧（ROS）形成，SOD活性增加和光合效率降低。这些结果表明，CeFeSOD和CeMnSOD可能参与保护细胞免受非辅助因子金属（例如铜和镍）引起的损害和氧化应激。这些基因对远低于EC _50的水平敏感，表明它们可用作分子生物标记物，以评估特定金属污染物的毒性。