| Antimony(Sb)is a toxic heavy metal element.Danio rerio is recognized as a model organism.Through the subacute toxicity Sb stress experiment,in this paper,the enrichment regularity of antimony,the activity and content changes of antioxidants,the m RNA expression of oxidative stress and apoptosis genes,and the morphology and ultrastructure of zebrafish were studied.Through the above research,we can further study the toxic effects of Sb on fish,and provide a theoretical basis for the environmental risk assessment of Sb pollution,which is of great significance for the realization of the research on the biological toxicity of heavy metals.The main conclusions obtained in this paper are as follows:(1)The accumulation and distribution of antimony in zebrafish liver,brain,gills,muscle and other tissues were studied after subacute toxic concentration of Sb stress for 18 days.It was found that Sb was accumulated in all tissues of zebrafish,and the maximum content was 184.93±11.0,15.31±2.91,54.25±2.65,33.68±1.44 mg/g.And the accumulation of Sb in each tissue showed an increasing trend with the increase of Sb stress concentration.(2)The activities of superoxide dismutase(SOD)and catalase(CAT)in liver,brain and gill of zebrafish were promoted at low concentration and inhibited at high concentration with the change of concentration,showing a trend of increasing at first and then decreasing.The activity of SOD in muscle decreased,and the activity of CAT increased first,then decreased and then increased.In addition,the activity of glutathione peroxidase(GSH-Px)decreased compared with the control group.The contents of glutathione(GSH)and malondialdehyde(MDA)in liver,brain,gill and muscle of zebrafish could be induced significantly,and increased with the increase of concentration.Exposure to Sb can induce ROS production in the fish body,and induce the activation of antioxidant defense system to resist ROS toxicity.However,due to the failure of ROS elimination,lipid peroxidation occurs in the fish body and the body is damaged to a certain extent.(3)The m RNA expression levels of Nrf2,Cu/Zn-SOD,Mn-SOD,CAT,GPX,Bcl-2 and p53 genes in liver,brain,gills and muscles were significantly expressed under Sb exposure,but the gene expression was inhibited and showed a downward trend under heavy metal stress in high concentration group.It is suggested that the antioxidant defense system is activated to resist oxidative damage,but because the accumulation of ROS in the body affects the normal physiological functions of the body,gene transcription is inhibited.(4)The pathological and ultrastructure of the liver,brain,gills and muscle tissues of zebrafish under the stress of high concentration of Sb were observed and studied.Under microscopic observation,there were cytoplasmic vacuoles,eosinophils infiltration and nuclear swelling in hepatocytes.There was swelling and hyperplasia of the epithelial cells in the gill lamellae.The gill lamellae were sticky,curled and partially broken.The epithelial cells around the gill filament fell off.There were microthrombosis and focal proliferation of glial cells in the molecular layer of brain,and proliferation and disorderly arrangement of cells in the molecular layer.The muscle fibers were atrophied and the space was obviously widened,and the muscle fibers dissolved and the cells aggregated.Ultramicro observation showed that the chromatin of the liver nucleus was condensed,accompanied by mitochondria swelling,cristae blurred or even disappeared,the number of mitochondria decreased,a large amount of glycogen aggregation,cytoplasmic vacuolation,lipid droplets,and rupture of rough endoplasmic reticulum.The gill epithelial cells were swollen,mucous cells secreted exuberant,and a large number of vacuolar structures appeared.The mitochondria in the chlorine secreting cells were swollen and the crest was fuzzy.In the brain treatment group,some mitochondria were found to be swollen and cristae blurred or even disappeared.The muscle fiber space was widened in the muscle treatment group. |
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