title: Enantioselective oxidative stress and oxidative damage caused by Rac- and S-metolachlor to Scenedesmus obliquus.
abstract: The rational use and environmental security of chiral pesticides has gained the interest of many researchers. The enantioselective effects of Rac- and S-metolachlor on oxidative stress in Scenedesmus obliquus were determined in this study. Stronger green fluorescence was observed in response to S-metolachlor treatment than to Rac-metolachlor treatment, suggesting that more reactive oxygen species (ROS) were stimulated by S-metolachlor. ROS levels following S-metolachlor treatment were 1.92-, 8.31-, and 1.08-times higher than those observed following Rac-metolachlor treatment at 0.1, 0.2, and 0.3 mg/L, respectively. Superoxide dismutase (SOD) and catalase (CAT) were stimulated with increasing herbicide concentrations, with S-metolachlor exhibiting a greater effect. Oxidative damage in terms of chlorophyll (Chl) content, cellular membrane permeability, and cellular ultrastructures of S. obliquus were investigated. Chla and Chlb contents in algae treated with Rac-metolachlor were 2-6-fold higher than those in algae treated with S-metolachlor at 0.1, 0.2, and 0.3 mg/L. The cellular membrane permeability of algae exposed to 0.3 mg/L Rac- and S-metolachlor was 6.19- and 42.5-times that of the control. Correlation analysis implied that ROS are the major factor responsible for the oxidative damage caused by Rac- and S-metolachlor. Damage to the chloroplasts and cell membrane of S. obliquus, low production of starch granules, and an increased number of vacuoles were observed upon ultrastructural morphology analysis by transmission electron microscope. These results indicate that S-metolachlor has a greater effect on S. obliquus than Rac-metolachlor.
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China. Electronic address: lhj@zjgsu.edu.cn.
authors.forename: Huijun
authors.initials: H
authors.lastname: Liu
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China.
authors.forename: YiLu
authors.initials: Y
authors.lastname: Xia
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China; Environmental Science Research & Design Institute of Taizhou City, China.
authors.forename: Weidan
authors.initials: W
authors.lastname: Cai
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China.
authors.forename: Yina
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China.
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China. Electronic address: Dushaoting@zjgsu.edu.cn.
authors.forename: Shaoting
authors.initials: S
authors.lastname: Du
mesh_terms: D000081:Acetamides / Q000737:chemistry / Q000494:pharmacology*; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D006540:Herbicides / Q000737:chemistry / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D044444:Scenedesmus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D013237:Stereoisomerism; D013482:Superoxide Dismutase / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000494:pharmacology*
chemical_list: D000081:Acetamides; D006540:Herbicides; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D002374:Catalase; D013482:Superoxide Dismutase; C051786:metolachlor
keywords: Antioxidant enzyme; Cell ultrastructures; Cellular membrane permeability; Chlorophyll content; Enantioselectivity; ROS