title: The combined effects of UV-B radiation and herbicides on photosynthesis, antioxidant enzymes and DNA damage in two bloom-forming cyanobacteria.
abstract: In this study, we investigated the combined effects of UV-B irradiation and herbicides (glyphosate, GPS; 2-Methyl-4-chlorophenoxyacetic acid, MCPA-Na; 3-(3,4-dichlorophenyl)-1,1-dimethylurea, DCMU) and the antioxidant (ascorbic acid, ASC) on photosynthesis, antioxidant enzymes and DNA damage in two bloom-forming cyanobacteria, Anabaena sp. and Microcystis viridis. UV-B irradiance increased reactive oxygen species (ROS) production, which decreased chlorophyll a fluorescence yield, pigment content and superoxide dismutase (SOD) activity, and increased malondialdehyde (MDA) content and caused serious DNA damage. The degree of these damages was aggravated by the addition of DCMU, GPS and MCPA, and was partially mitigated by the addition of ASC. During the recovery process, the degree and mechanism in restoring DNA damage and photosynthesis inhibition were different by the removal of UV-B and herbicides (DCMU, GPS and MCPA) in both cyanobacteria. These results suggest that the combination of UV-B and exogenous herbicides have detrimental effects on cyanobacterial metabolism through either a ROS-mediated process or by affecting the electron transport chain, and may cause the shifts in the phytoplankton community.
authors.affiliation: School of Resource & Environmental Sciences, Hubei Key Laboratory of Biomass-Resources Chemistry and Environmantal Biotechnology, Wuhan University, Wuhan 430079, PR China. chenlanzhou@yahoo.com.cn
authors.forename: Lanzhou
authors.initials: L
authors.lastname: Chen
authors.forename: Mu
authors.initials: M
authors.lastname: Xie
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Bi
authors.forename: Gaohong
authors.initials: G
authors.lastname: Wang
authors.forename: Songqiang
authors.initials: S
authors.lastname: Deng
authors.forename: Yongding
authors.initials: Y
authors.lastname: Liu
mesh_terms: D008456:2-Methyl-4-chlorophenoxyacetic Acid / Q000633:toxicity; D001205:Ascorbic Acid / Q000378:metabolism; D000458:Cyanobacteria / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects*; D004249:DNA Damage; D004237:Diuron / Q000633:toxicity; D005998:Glycine / Q000031:analogs & derivatives / Q000633:toxicity; D006540:Herbicides / Q000633:toxicity*; D008315:Malondialdehyde / Q000378:metabolism; D010084:Oxidation-Reduction; D010788:Photosynthesis / Q000187:drug effects / Q000528:radiation effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014874:Water Pollutants, Chemical / Q000633:toxicity; D000097797:Glyphosate
chemical_list: D008456:2-Methyl-4-chlorophenoxyacetic Acid; D001205:Ascorbic Acid; D004237:Diuron; D005998:Glycine; D006540:Herbicides; D008315:Malondialdehyde; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D000097797:Glyphosate