Toxic Effects Of Three Typical Water Pollutants On Zebrafish Embryos

In recent years,with the development of economy and the acceleration of industrialization,human activities in industry,agriculture,animal husbandry and aquaculture have resulted in the emergence of a large number of new organic pollutants in water.These pollutants will eventually enter the human body through long-distance migration and food chain enrichment,causing potential harm to human health,has become the focus of attention.Therefore,the single and combined toxicity effects of three typical organic pollutants(perfluoroalkylates,Polycyclic aromatic hydrocarbon and triazine herbicides)in water were investigated using zebrafish embryos;metabonomics method was used to screen the biomarkers of mixed pollution during the development of zebrafish embryos,in order to explore its toxicity mechanism and provide scientific basis for toxicological assessment of typical water environment pollutants.The major findings are as follows:First,the acute toxicity of three types of six organic pollutants(perfluorooctanoic acid,perfluorooctane sulfonic acid,naphthalene,fluorene,atrazine,and promethazine)to zebrafish embryos was studied.Based on the results,set a certain concentration to study the development and differences of zebrafish embryos exposed to a single pollutant by phenotypic observation.According to the LC50 of each pollutant(224.61,22.51,16.6,15.07,11.9,9.3mg/L),it can be seen that the 120 h toxicity intensity of the six pollutants to zebrafish embryos is in the order of: prometryne > atrazine > fluorene > naphthalene > perfluorooctane sulfonic acid >perfluorooctanoic acid.In terms of apparent toxicity,abnormal yolk sac,abnormal liver and curvature of the spine are the most easily observed types of zebrafish embryo abnormalities after single exposure to perfluorooctanoic acid,fluorene and atrazine.At the same time,the half-maximum effect concentration(EC50)of each pollutant is calculated,which provides a basis for the concentration of the joint exposure in the next step.Second,the zebrafish embryos were exposed to two binary mixtures of perfluorooctanoic acid,atrazine and fluorene mixed at the EC50 of the three toxicity indicators and the five concentrations diluted in proportion.After 120 hours,the following toxic effects were observed: in the combined exposure treatment group of perfluorooctanoic acid and fluorene,with the increase of the concentration of the binary mixture,the incidence of abnormal yolk sac and spine curvature of zebrafish larvae increased,and the combined action modes were synergistic and antagonistic to synergistic effects;in the perfluorooctanoic acid and atrazine combined exposure treatment group,the incidence of zebrafish larval yolk sac abnormalities,liver abnormalities and spinal curvature increased with the increase of the concentration of the binary mixture.According to model prediction,the combined action mode of the binary mixture causing zebrafish embryo yolk sac abnormality,liver abnormality and spine curvature is changed from antagonism to synergy;in the combined exposure treatment group of fluorene and atrazine,with the increase of the concentration of the binary mixture,the incidence of zebrafish larval yolk sac abnormality and spinal curvature increased.The combined action mode of the binary mixture that caused abnormal zebrafish embryo yolk sac changed from synergy to antagonism,and the combined action mode that caused spinal curvature changed from antagonism to synergy.Third,a metabonomic analysis of 21 targeted amino acids in zebrafish larvae after exposure to pollutants revealed that the single and combined exposure treatments of perfluorooctanoic acid,atrazine,and fluorene all interfered with the amino acid metabolism of zebrafish larvae to some extent,resulting in up-or downregulation of some amino acids.Through the screening of differential metabolites,it was found that the single and combined exposures of perfluorooctanoic acid and fluorene could induce toxicity to zebrafish embryos by interfering with nervous system,affecting liver development,producing oxidative stress and inflammatory reaction.The single and combined exposure of perfluorooctanoic acid and atrazine may not only interfere with the nervous system,cause inflammation and affect the liver development,but also affect the immune and metabolic functions of the body.The joint exposure of fluorene and atrazine produced toxicity mainly by interfering with the development of nervous system and energy metabolism.