Study On Embryo Developmental Toxicity Ofheavy Metal Copper On Zebrafish

With the rapid development of Industry and Agriculture and the rapid growth of population,the problem of environmental pollution becomes more and more serious.The discharge of heavy metals is increasing gradually,and heavy metal pollution has become one of the important problems of water environment pollution in China.Heavy metals exceeding water quality standards can be detected in coastal waters and along estuaries.As one of the essential nutrients for aquatic organisms,copper is not only a kind of transition metal element widely existed in nature,but also the main component of enzymes involved in important life activities.Because copper can not be broken down in biological systems,it can only be enriched along the food chain to the top of the organism.With the extensive use of copper sulfate as an important medicine and feed additive in aquaculture,the pollution of heavy metal copper in water is becoming more and more serious The toxicity range of dissolved copper is also wider,therefore,the toxicity of dissolved copper to Aquatic animal is studied in this paper.In order to study the acute toxicity of copper to zebrafish embryos,96 h acute exposure test was used to study the developmental toxicity of copper to zebrafish embryos.The results showed that copper had significant lethal teratogenic and hatching inhibition effects.The LC50 of zebrafish embryos treated with copper at 96 h was 4.122 mg/L,which showed developmental retardation,slow deposition of pigment and slow development of nervous system.Higher concentration than 0.20 mg/L could result in zero embryo hatching rate.In the study of toxicological mechanism,apoptosis,mitochondrial biogenesis and gene expression were detected by Flow cytometry,long PCR and RT-PCR.According to the results of cell apoptosis measured by Flow cytometry,the apoptosis rate of embryos treated with 4.122 mg/L copper ion was 25%,the total ROS level and mitochondrial source ROS were also significantly increased,the mitochondrial membrane potential was decreased,and the mitochondrial mass was decreased This suggests that the heavy metal copper ion can catalyze redox and thus produce large amounts of ROS,which can lead to organelle damage.ROS can also induce mitochondrial DNA damage and mitochondrial DNA damage.The result of PCR showed that the oxidative damage of mtDNA was time-dose dependence.In Fish,as in other organisms,oxidative stress is normally impaired by the scavenging of ROS by antioxidant enzymes such as Superoxide dismutase and Catalase.The activity of its antioxidant enzyme system is related to the concentration of heavy metals.Malondialdehyde(MDA)is widely used as an indicator of the content of Lipid peroxidation.The result of RT-PCR was consistent with the result of enzyme activity,which indicated that the level of ROS was decreased by up-regulating the expression of SOD and CAT Genes.