Teratogenic Effect And Molecular Mechanism Of Low-dose Typical Pesticide-lead Complex Pollution On Xenopus Tropicalis Embryo

The application of pesticide in paddy field is one of the sources of water pollution in the southern agricultural area.Chlorpyrifos and acetochlor are one of the most widely used pesticides and herbicides in China.Lead(Pb)is one of the important sources of heavy metal pollution in the ecological environment.Acute toxicity and frog embryo teratogenicity assay-Xenopus(FETAX)were used to study the toxic effects of single and mixed pollutant.The results showed that teratogenic effects have observed on the embryo of Xenopus tropicalis exposed to chlorpyrifos,acetochlor and Pb,and the mortality and the teratogenic rate increased significantly with the increase of concentration(P < 0.05).First of all,the typical teratogenic phenotypes are including(1)head malformation: the head becomes smaller,the eyes become larger or smaller,and the displaced cement gland;(2)abdominal malformation: abdominal edema,enlarged or elongated trunk;(3)malformation of cloacal cavity: edema or elongation of cloacal cavity;(4)Tail and body axis deformities: tail short,curved,and body axis bent.Secondly,the survival rate of Xenopus tropicalis’ embryo exposed to chlorpyrifos-acetochlor-Pb mixture was significantly lower than that of single pollutant and binary compound pollutant.The teratogenic rate of embryo exposed to chlorpyrifos-acetochlor was higher than that ofchlorpyrifos-Acetochlor-Pb,and that of acetochlor > that of acetochlor-Pb;the teratogenic fractions of chlorpyrifos,acetochlor and Pb groups were higher than those of corresponding compound pollution.The deformity rate of typical phenotypic head deformity was higher in chlorpyrifos treatment than in chlorpyrifos treatment,and the deformity rate of cardiac edema was higher in acetochlor treatment than that in compound mixed acetochlor treatment.It was concluded that the combination of chlorpyrifos,acetochlor and lead in the binary and ternary complex decrease the toxicity of the single pollutant.The effect of single pollutant and mixtures on bone morphogenic protein(Bmp2,Bmp4)genotoxicity was studied by real-time fluorescence quantitative PCR at the molecular level.The results showed that the expression of Bmp2 and Bmp4 genes was significantly inhibited in most of the treatment,and the expression level of Bmp2 gene in 0.8 mg/L chlorpyrifos treatment was lower than that of the same concentration of mixture treatment.The expression level of Bmp2 gene in Pb treatment group Bmp4 gene expression in the chlorpyrifos-treated group was lower than that in the mixture treated with 0.8 mg/L chlorpyrifos,and the Bmp4 gene expression in the acetochlor single-dose treatment was lower than that of the mixed treatment.