title: Towards elucidation of the toxic mechanism of copper on the model green alga Chlamydomonas reinhardtii.
abstract: Toxic effects of copper on aquatic organisms in polluted water bodies have garnered particular attention in recent years. Microalgae play an important role in aquatic ecosystems, and they are sensitive to heavy metal pollution. Thus, it is important to clarify the mechanism of copper toxicity first for ecotoxicology studies. In this study, the physiological, biochemical and gene expression characteristics of a model green microalga, Chlamydomonas reinhardtii, with 0, 50, 150 and 250 μM copper treatments were investigated. The response of C. reinhardtii to copper stress was significantly shown at a dose dependent manner. Inhibition of cell growth and variation of total chlorophyll content were observed with copper treatments. The maximum photochemical efficiency of PSII, actual photochemical efficiency of PSII and photochemical quenching value decreased in the 250 μM copper treatment with minimum values equal to 28, 24 and 60 % of the control values respectively. The content of lipid peroxidation biomarker malondialdehyde with copper treatments increased with a maximum value sevenfold higher than the control value. Inhibition of cell growth and photosynthesis was ascribed to peroxidation of membrane lipids. The glutathione content and activities of antioxidant enzymes, glutathione S-transferase, glutathione peroxidase, superoxide dismutase and peroxidase were induced by copper. Interestingly, the expression of antioxidant genes and the photosynthetic gene decreased in most copper treatments. In conclusion, oxidative stress caused by production of excess reactive oxidative species might be the major mechanism of copper toxicity on C. reinhardtii.
authors.affiliation: Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Shenzhen, People's Republic of China.
authors.forename: Yongguang
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Shenzhen, People's Republic of China.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Shenzhen, People's Republic of China.
authors.forename: Zhangli
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Shenzhen, People's Republic of China. bioaplei@szu.edu.cn.
authors.forename: Anping
authors.initials: A
authors.lastname: Lei
authors.affiliation: Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Shenzhen, People's Republic of China. jxwang@szu.edu.cn.|Shenzhen Engineering Laboratory for Marine Algal Biotechnology, Shenzhen, People's Republic of China. jxwang@szu.edu.cn.|College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, People's Republic of China. jxwang@szu.edu.cn.|Nanshan District Key Lab for Biopolymers and Safety Evaluation, Shenzhen University, Shenzhen, 518060, People's Republic of China. jxwang@szu.edu.cn.
authors.forename: Jiangxin
authors.initials: J
authors.lastname: Wang
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D003300:Copper / Q000633:toxicity*; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress; D009195:Peroxidase / Q000378:metabolism; D010788:Photosynthesis; D013482:Superoxide Dismutase / Q000378:metabolism; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D008315:Malondialdehyde; D003300:Copper; D009195:Peroxidase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005982:Glutathione Transferase; D005978:Glutathione
keywords: Antioxidant; Chlorophyll fluorescence; Copper toxicity; Gene expression; Microalgae