单 位：
上海应用技术学院化学与环境工程学院;浙江大学环境与资源学院
摘 要：
以铜绿微囊藻(Microsystis aeruginosa)作为生物模型,通过测定藻细胞氧化损伤程度与藻细胞内外藻毒素LR(microcystin-LR,MC-LR)的含量,研究除草剂禾草灵的生态毒性。结果表明,禾草灵在实验室处理质量浓度1,2,5mg/L下,能诱导铜绿微囊藻细胞活性氧(reactive oxygen species,ROS)的产生,引起细胞脂质过氧化水平丙二醛(malondialdehyde,MDA)的提高和超氧化物歧化酶(superoxide dismutase,SOD)的活性增强。说明禾草灵对铜绿微囊藻产生了氧化胁迫。5mg/L禾草灵使铜绿微囊藻释放到细胞外的微囊藻毒素MC-LR显著增加,为空白对照的68.5,2.11,2.50,123.67倍(第2,3,4,5天);细胞内MC-LR含量与空白对照相比有一定的降低,为空白对照的0.34,0.82,2.76,0.11倍(第2,3,4,5天)。说明禾草灵在一定质量浓度下能对铜绿微囊藻产生氧化胁迫,引起藻细胞脂质过氧化,从而引起细胞膜损伤,导致微囊藻毒素MC-LR更多的释放到水体中,对水环境造成一定的影响。实验结果可对禾草灵的环境安全评价提供一定的参考。
译 名：
Effects of herbicide diclofop-methyl on oxidative stress and microcystin release in cyanobacterium Microsystis aeruginosa
作 者：
Ye Jing;Liu Chaonan;Liu Weiping;School of Chemical and Environmental Engineering,Shanghai Institute of Technology;College of Environmental and Resource Sciences,Zhejiang University;
关键词：
herbicide;;cyanobacteria;;oxidative stress;;microcystin-LR
摘 要：
Diclofop-methyl is a postemergence herbicide introduced in the 1960 s.It is widely used on wheat,barley,and golf courses(turf)all over the world.Residues of diclofop-methyl may pollute the water system and affect the physiological processes in cyanobacteria.Causative cyanobacteria can often cause serious environmental,aesthetic,and economic problems;besides,it can produce microcystins(MCs)which are toxic to domestic livestock and wildlife.Certain environmental factors such as pH,temperature,and the amount of nitrogen and phosphorus in the water have been found to affect the production of MCs.But other factors,such as the concentration of environmental pollutants including pesticide residues which may be prevalent in aquatic ecosystems,have not been studied in sufficient detail. In the current study,oxidative damage and toxin release from Microsystis aeruginosacaused by diclofop-methyl were investigated.Diclofop-methyl was proposed to induce oxidative stress in susceptible plant tissues and tocollapse the transmembrane proton gradient.Cells can develop a set of cellular defense systems via enzymatic and non-enzymatic antioxidants to counteract the toxicity of reactive oxygen species(ROS)like H2O2,O2·and·HO.In the enzymatic pathways,superoxide dismutase(SOD)is important to scavenge ROS. The results showed that diclofop-methyl induced the generation of ROS,increased the concentration of malondialdehyde(MDA),enhanced the activity of SOD and triggered toxin release in M.aeruginosa to varying degrees.After 4hof treatment,diclofop-methyl induced ROS generation by 3%,4%and 4%under 1,2and 5mg/L,respectively.After 8dof treatment,1mg/L and 5mg/L diclofop-methyl induced ROS generation by 12%and43%,respectively.After 9 dtreatment,5 mg/L diclofop-methyl induced ROS generation by 11%.The concentrations of MDA were 3.47,1.86 and 10.61 folds compared to the control after 24 htreatment of 1,2and 5mg/L diclofop-methyl.After 48 htreatment,the MDA concentrations were 4.89,1.48,and 0.17 folds compared to the control for 1,2and 5mg/L diclofop-methyl,respectively.The activities of SOD were 1.64,1.25 and 2.26 folds compared to the control after 24 htreatment of 1,2and 5mg/L diclofop-methyl,and after 48 htreatment,the folds were 2.36,4.02 and 2.52 for 1,2and 5mg/L diclofop-methyl,respectively. At the concentration of 5mg/L diclofop-methyl the extracellular MC-LR contents in M.aeruginosa were 68.5,2.11,2.50 and 123.67 folds compared to the control from the second day to the fifth day,respectively.However,the intracellular MC-LR contents in 5mg/mL diclofop-methyl treated samples were lower than the control,which were 0.34,0.82,2.76 and 0.11 folds from the second day to the fifth day,respectively. In conclusion,diclofop-methyl may collapse the transmembrane proton gradient and destroy the cell membrane through lipid peroxidation and free radical oxidation,which results in more MC-LR release from cyanobacteria to the water body.The results are helpful in understanding the effects of diclofop-methyl on cyanobacteria,which is important for environmental assessment and protection.It is also helpful for guiding the application of diclofopmethyl in agricultural settings.
