| Pesticide and insecticide residues are common in the aquatic environment,including lakes,rivers,streams,and other surface water.Among them,diflubenzuron is a pesticide that inhibits the growth of many harmful larvae of chitin.Isoprocarb is a carbamate insecticide widely used in agriculture and aquaculture,and these two insecticides are often detected in aquaculture.The agricultural use of pesticides is increasing worldwide,and a large number of studies have demonstrated that they pose a threat to non-target organisms.However,research on their potential toxicity mechanisms is still insufficient.In addition,zebrafish(Danio rerio)has been widely used for toxicity risk assessment of pesticides due to its optical transparency and rapid development,which allow visualization of the circulatory system in individual animals.Therefore,this study made zebrafish embryos as experimental objects and exposed them to different concentrations of diflubenzuron and isoprocarb solutions to study the cardiotoxicity of diflubenzuron and the neurotoxicity of isoprocarb,and study their toxicity mechanisms.In order to provide reference for the rational use of this insecticide and its environmental risk assessment in the future.The results of exposure experiments with diflubenzuron showed that high concentrations of diflubenzuron(over 3.5 mg/L)increased the mortality,decreased the fetal heart rate,and decreased the hatchability in a concentration dependent manner;the distance between the venous sinus and the bulbar artery(SV-BA)of zebrafish embryos increased,resulting in impaired cardiomyocyte proliferation and vascular development;excessive production of reactive oxygen species(ROS)in zebrafish embryos,increased the malondialdehyde(MDA)content,and inhibited the antioxidant activity,including SOD(superoxide dismutase)and CAT(catalase).Fluorescence quantitative PCR results showed that diflubenzuron promoted the expression of apoptosis-related genes and inhibited some genes related to heart development.Based on the above experimental results,diflubenzuron exposure induced severe cardiotoxicity in zebrafish embryos,which may be due to the inhibition of gene expression related to cardiac development signaling pathways,and excessive oxidative stress leading to cell apoptosis,ultimately leading to cardiotoxicity.The results of isoprocarb exposure experiments showed that isoprocarb could reduce the hatching rate and average heart rate of zebrafish embryos,and increased the area of yolk sac.Isoprocarb exposure caused developmental defects in the hindbrain of zebrafish embryos,significantly inhibited zebrafish embryos’ motor ability,and reduced acetylcholinesterase(ACh E)activity;promoted the upregulation of apoptotic genes Bax and p53,significantly downregulated the anti-apoptotic gene Bcl2,and increased the expression levels of TNFα,IL-6,IL-8,caspase3 and caspase9;inhibited the expression of neurodevelopmental related genes foxo3 a,gfap,sny2 a,elavl3 and sox19b;Significantly increased the level of reactive oxygen species(ROS)and reduced the activity of antioxidant enzymes(SOD).Based on the above experimental results,isoprocarb exposure could cause severe neurotoxicity to zebrafish embryos,which may be due to oxidative stress-induced apoptosis that damaged the brain and affected the neural development of zebrafish embryos. |
