The Effect Of Spirotetramat Exposure On Oxidative Stress Response And Embryo Development In Zebrafish (Danio Rerio)

Spirotetramat is a modern tetramic acid pesticide developed by Bayer CropScience. It acts asan inhibitor of lipid biosynthesis in insects and affects juvenile stages with additional effects onadult fecundity. Currently, the major research interests was lied in this compound as follows:synthesis technology, efficacy and toxic effects, et al. Its aquatic toxicity, however, had beenrarely mentioned in literature. In recent study, zebrafish was chosen to evaluate the toxicity ofspirotetramat. The study investigated:1) the acute toxicity of spirotetramat to female zebrafish;2)the developmental toxicity of spirotetramat to zebrafish embryos;3) the effect on oxidative stressand ovary cellular morphology after exposing to spirotetramat for28d. The result was lookedforward to provide for access to evaluate the aquatic toxicity of spirotetramat.The results of acute toxicity assay indicated the72h-LC50and96h-LC50value ofspirotetramat were9.61,7.21mg/L, respectively, suggesting a moderate toxicity to femalezebrafish. The abnormal behaviors of zebrafish after spirotetramat exposure included disorderbalance, high frequency of tail swing, and freeze response.The mortality, malformation, hatching rate and heart beats were detected for assessing thedevelopmental toxicity of spirotetramat to zebrafish embryos in the study. The results combiningto the analysis of ovary paraffin section were used to evaluate the toxicity of spirotetramat toembryo development. The results were indicated that most of embryos were survived whenexposing to either36μg/L or360μg/L spirotetramat, but1800μg/L spirotetramat inducedsignificant mortality. However, there was a dose-response relationship between heart beats orhatching rate and spirotetramat concentration. Besides, spirotetramat was found to effect thematurity of oocytes in ovary. There were no phase V mature oocytes but only phase I, II and IIIoocytes existing in1800μg/L spirotetramat treatment after28d exposure.Oxidative stress was induced in female zebrafish muscle after exposing to spirotetramat for28d. Two responsors of oxidative stress that activities of CAT and GSH-Px in muscle werealtered significantly by various concentrations of spirotetramat. In addition, the MDA contentincreased obviously. The mRNA levels of Cat, Mn-sod and Gpx mRNA were significantlyup-regulated when exposed to some concentration of spirotetramat. However, neither Cu/Zn-Sodexpression nor activity of Cu/Zn-SOD was changed after treating with spirotetramat in this study. In summary, the results of assays in this study indicated the effect of spirotetramat reflectedin developmental toxicity on zebrafish embryos and oxidative stress in zebrafish muscle.