Study On The BDE-47 And Its 4 Derival OH-PBDEs On The Toxicity Effect Of Zebrafish Embryos

In this paper,the autors selected 2,2',4,4'-tetrabromodiphenyl ether?BDE-47?and its 4 hydroxylated derivatives,including 2'-Hydroxy-2,3',4,5'-tetrabromodiphenylether?2'-OH-BDE-68?,3-hydroxy-2,2',4,4'-tetrabromodiphenyl ether?3-OH-BDE-47?,5-hydroxy-2,2',4,4'-tetrabromodiphenyl ether?5-OH-BDE-47?,6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether?6-OH-BDE-47?as the test substance witch have been detected in water commonly and possessed high solubility with zebrafish embryos as model organisms in this paper.The toxic effects of BDE-47 and its 4 derivatives on zebrafish embryos were studied in zebrafish from multiple perspectives?morphology,molecular biology?and multiple levels?cell level,protein level,gene level?to elucidate the ecological risk assessment of PBDEs and OH-PBDEs and provide data basis and theoretical basis for the environmental management decisions.The main studies and results are as follows:?1?In this study,the acute toxicity tests were carried out to analyze the Correlation of median lethal concentration?LC50?of BDE-47 and its derival OH-PBDEs toxicity effect on embryos and adult zebrafish at exposure for 24,48,72 and 96 h,showed that the linear equation of 96 h LC50 was: y=-0.64511+0.94256x?R²=0.9787?,indicating a significant linear correlation between the toxicity on embryos and adult zebrafish.The results showed that 6-OH-BDE-47 had the highest toxicity,followed by 5-OH-BDE-47,2'-OH-BDE-68,3-OH-BDE-47 and BDE-47 was the weakest toxicity compared to its 4 derivatives.?2?Zebrafish embryos exposed different concentrations of 5 tested-substances could lead to the hatching rate,heart rate,survival rate decreased,while the deformity rate increased and even inhibited growth and development on zebrafish embryos.The results showed that 5 test-substances all caused different degrees of thyroxine?T₄?and triiodothyronine?T₃?levels changed on zebrafish larvaes after 144 hours fertilization?hpf?,resulting in the toxicity of growth and development in early life stages of zebrafish embryos.The no observable effect concentrations?NOEC?were 0.08?0.08?0.16?0.04?0.02 mg·L-1,respectively.?3?The bioconcentration of 5 test-substances in early stage life of zebrafish embryos showed that BDE-47 and OH-PBDEs all have certain bioaccumulation ability and the values of 45 d-BCF were 969,588,424,244 and 144,respectively.?4?The activities of CAT?catalase?and Cu/Zn-SOD?Cu/Zn-superoxide dismutase?showed a significant upward trend,while GPx?glutathione peroxidase?activity was significantly inhibited,showing an opposite downward trend by 4 OH-PBDEs on zebrafish embryos after short-term?120 h?exposure,which destroyed the self-defense function of zebrafish larvaes and significantly enhanced the toxicity of 4 OH-PBDEs to zebrafish embryos.Histopathological studies showed that 120 hpf zebrafish larvaes gills structure disorders,cheek epithelial thicken,tissue damaged,and even necrosis,as well as spinal curvature compared with the control.?5?With the exposure of 4 test-substances treatments showed different degrees of apoptosis signal in brain,tail,yolk sac site on 96 hpf zebrafish larvaes,while the control group did not appear or appeared a little apoptosis signal.The apoptosis-related?caspase 2,caspase 8,caspase 9?and oxidative stress-related?Cu/Zn-Sod,cat,Gpx1a?genes expression of 4 OH-PBDEs in 144 hpf zebrafish was detected by q RT-PCR.,which could induce Cu/Zn-Sod,cat and Gpx1 a genes had siginificant changed?p<0.05 or p<0.01?,but the same genes have different regulatory mechanisms for different test substances.Changes in genes disrupted the oxidative stress system in zebrafish and also affected the tissue structure in zebrafish larvaes.