Oxidative Stress And DNA Damage Induced By Pyraclostrobin And Fluoxastrobin Exposure In Earthworm

Strobilurin fungicide is a sort of fungicide used the natural antibiotics strobilurin A as lead compounds. It is a new type of bactericide had been finally developed after more than 20 years of structural optimization. It has good activity for almost all of the fungi diseases, on the fungicide development history has set a new milestone after triazole fungicide. Strobilurin fungicides are widely used in the word. At present, we have more then ten kinds of the commercialization of Strobilurin fungicides. Among them, there are six varieties global sales of more than one hundred million dollars in 2011. As two varieties of them, pyraclostrobin and fluoxastrobin are widely used in recent years and broad prospects for application.However, because people use pesticidies not science which Lead a lower utilization rate in the process of application and most of the pesticides residues in soil ecosystems or the water ecosystem and bring potential damage to ecological environment security.In order to evaluate the influencement to the soil ecological environment security of pyraclostrobin and fluoxastrobin. In this study, the eisenia fetida was selected as the model organism. The earthworm was exposed to a control and four concentrations of pyraclostrobin and fluoxastrobin(0, 0.1, 1, and 2.5 mg?kg^-1 soil) respectively and were studied on days of 7,14, 21, and 28 days. The soil selects the artificial soil ruled by OECD?2004?. The present study was conducted to investigate the influence of Reactive Oxygen Species?ROS? content,Superoxide Dismutase,?SOD?, Catalase?CAT?, peroxidase?POD?, Glutathione Stransferases?GST? activity,Malondialdehyde?MDA? content and the body cavity cell DNA damage of the earthworm.The results will be useful to evaluate the effects of pyraclostrobin and fluoxastrobin on the oxidative damage and genetic toxicity of earthworm.which is also important to comprehensive understanding and evaluation of pyraclostrobin and fluoxastrobin potential toxic harm on the soil ecosystem to provide basic data.Main results were summarized as follows:?1? Pyraclostrobin and fluoxastrobin can produce obvious effects of oxidative stresst on earthworms. Under the exposure of pyraclostrobin and fluoxastrobin, all the ROS level increased substantially with increasing concentration. With the passage of time, under the action of biological antioxidant enzymes in the earthworm, under the exposure of pyraclostrobin, the ROS content on the 28^th day lower than 21 th day and 0.1 mg?kg^-1 treatment group returned to the control level; Under the exposure of fluoxastrobin, the ROS content isslightly lower on the 28^th day.?2?Under the exposure of pyraclostrobin and fluoxastrobin, the SOD, CAT and POD activity in the earthworm are affected more or less. Pyraclostrobin-exposed treatments most Presents the activation state for the first 21 days.Every enzyme activity was lower and SOD and POD activity even in the suppressed phenomenon on the 28^th day; Fluoxastrobin-exposed treatment group, the SOD activity was in the activated state. On the other side, the CAT activity was suppressed in the beginning and then activated gradually. Enzyme activity anomalies show that the earthworm suffered some degree of damage.?3?The GST activity was influenced after the exposure to pyraclostrobin and fluoxastrobin, Under the exposure of pyraclostrobin, the GST activity was activated on the 7th,14 st and 21 th days.Nonetheless, the GST activity was suppressed on the 28^th day; During the exposure period of fluoxastrobin, GST activity of the treatment group were received a degree of activation.in addition, the GST activity the 0.1 mg kg^-1 treatment's group was similar with the control after 21 days.?4? In general, the MDA content increased firstly and decreased subsequently during the exposure period of both two fungicides. Under the exposure of pyraclostrobin, the MDA content increased on the 7th, 14 th and 21 th days and returned to control levels on the 28^th day;Under the exposure of pyraclostrobin, the MDA content most increased after exposed by 14 days, and a slight decreased on the 28^th day.?5?Under the exposure of both two fungicides, the DNA damage increased greatly with the increase of the concentration and time.In the present study, there was an obvious doseeffect relationship. Meanwhile, the comet assay was the most sensitive indicators in the present study. But from the time range, we can see that the low concentration(0.1mg?kg^-1)treatment's degree of DNA damage was declined on the 28^th day.