Molecular identification,differential expression and protective roles of iron/manganese superoxide dismutases in the green algae Closterium ehrenbergii against metal stress |
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| Institution: | 1. Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan 94300, Sarawak, Malaysia;2. Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok 16310, Kelantan, Malaysia;3. The University of Tokyo, Yayoi 1-1-1, Bunkyo-Ku, Tokyo 113-8657, Japan;4. Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia;1. Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2. Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China;3. University of Chinese Academy of Sciences, Beijing 100049, China;4. Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China;1. National Centre for Aquatic Animal Health, Cochin University of Science and Technology, Cochin-16, Kerala, India;2. School of Environmental Studies, Cochin University of Science and Technology, Cochin-22, Kerala, India;3. Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea |
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| Abstract: | 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. |
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| Keywords: | Fe/MnSOD Gene expression Metals ROS Toxicogenomics |
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