Effects Of Monosultap And Thiophanate-methyl On Zebrafish Notochord Development And Its Molecular Mechanism

Notochord is the supporting organ of vertebrate embryonic development,which plays a variety of important roles,such as protecting organs,and coordinating the body.Chordal trauma and developmental malformations would lead to neurological disorders,body paralysis,movement limitations and other adverse consequences.Agricultural pollutants enter the human body through soil,water,and the bioaccumulation of plants and animals,and then affect human health.Analyzing the effects of agricultural environmental pollutants on notochord development in nontarget animals has great significance in assessing the biotoxicity of pollutants and their risks to human health.Monosultap and thiophanate-methyl are two broad-spectrum insecticides,which play an important role in improving crop yields.In this study,zebrafish were taken as model organisms,and the acute exposure experiment was conducted to analyze the effects of monosultap and thiophanate-methyl on the notochord development of zebrafish.We analyzed the molecular mechanisms of notochordal toxicity induced by monosultap and thiophanate-methyl,using paraffin sections,hematoxylin and eosin staining,fluorescence quantitative PCR,and in situ hybridization experiments.The results showed that:(1)Malformation of notochord development was induced by monosultap and thiophanatemethyl in zebrafish embryos.Exposure to 0.25 mg/L monosultap and 1.5 mg/L thiophanatemethyl shortened the body axis,increased the rate of notochord deformity,disordered arrangement of sheath cells and ruptured vacuolar structure of zebrafish embryos.In addition,after the exposure to thiophanate-methyl,the number of vertebrae in adult zebrafish reduced,the vertebrae fusion became poor,and the level of mineralization decreased.(2)Oxidative stress is the cause of monosultap-induced abnormal notochord development in zebrafish embryos.Monosultap increased oxidative stress in zebrafish,which induced abnormal expression of notochordal related genes(shha,col2 a and ptch2),resulting in notochordal malformations.(3)PI3K-m TOR signaling pathway was involved in thiophanate-methyl-induced notochord abnormalities.The expression of notochordal related genes(shha,col2 a and tbxta)was significantly increased after thiophanate-methyl exposure.Meanwhile,rapamycin and LY294002(a PI3 K inhibitor)alleviated the notochordal toxicity induced by thiophanate-methyl,including abnormal notochord morphology and up-regulated gene expression(shha,col2 a and tbxta).Therefore,thiophanate-methyl induced notochord toxicity by activating the PI3K-m TOR pathway in zebrafish.