重金属Pb^(2+)、Cd^(2+)、Cr^(6+)对洞庭青鲫仔鱼急性毒性、细胞凋亡及组织损伤的影响

Effects of heavy metals Pb^(2+),Cd^(2+)and Cr^(6+)on acute toxicity,apoptosis and tissue damage of larvae Carassius auratus indigentiaus

研究重金属Pb^(2+)、Cd^(2+)、Cr^(6+)对洞庭青鲫(Carassius auratus indigentiaus)仔鱼的毒性效应。选择不同浓度的Pb^(2+)、Cd^(2+)、Cr^(6+)处理洞庭青鲫仔鱼,分别在实验的0、24、48、72、96 h观察重金属离子对仔鱼死亡率的影响。选择96 h低死亡率重金属浓度处理组(2 mg·L^(-1)Pb^(2+)、0.125 mg·L^(-1)Cd^(2+)、5 mg·L^(-1)Cr6+),观察各重金属对洞庭青鲫仔鱼鳃组织损伤及细胞凋亡的影响。结果表明:(1)Pb^(2+)、Cd^(2+)、Cr^(6+)对洞庭青鲫仔鱼的96-LC_(50)分别为39.5、0.39、16.38 mg⋅L^(-1),安全浓度分别为3.945、0.039、1.638 mg·L^(-1)。急性毒性由强至弱依次为Cd^(2+)>Pb^(2+)>Cr^(6+);(2)5 mg·L^(-1)Cr^(6+)处理组洞庭青鲫仔鱼96 h死亡率为37%,仔鱼鳃组织产生严重损伤,包括细胞纹理变得疏松,色素细胞大量增加,纤毛脱落,大量细胞空泡化,巨噬细胞增多,结缔组织发生糜烂坏死等。2 mg⋅L^(-1)Pb^(2+)和0.125 mg⋅L^(-1)Cd^(2+)处理组洞庭青鲫仔鱼96 h死亡率分别为16%和58%,仔鱼鳃组织出现轻微损伤,色素细胞少量增加,少量细胞出现空泡化;(3)2 mg⋅L^(-1)Pb^(2+)、0.125 mg⋅L^(-1)Cd^(2+)、5 mg⋅L^(-1)Cr^(6+)三个处理组的洞庭青鲫仔鱼鳃部发生细胞凋亡,并且Pb^(2+)处理组鳃部细胞凋亡最严重。综上所述,Pb^(2+)、Cd^(2+)、Cr^(6+)对洞庭青鲫仔鱼具有较强的毒性,但是各重金属处理组死亡率与组织损伤、细胞凋亡无显著的相关性,不同重金属导致洞庭青鲫死亡的机制可能不一样。

The toxic effects of heavy metals Pb^(2+),Cd^(2+)and Cr^(6+) on the larvae of Carassius auratus indigentiaus were studied.Different concentrations of Pb^(2+),Cd^(2+)and Cr6+were used to treat larvae Carassius auratus indigentiaus,and the effects of heavy metal ions on juvenile mortality were observed at 0,24,48,72,96 h respectively.Effects of low mortality concentration treatments(2 mg⋅L^(-1)Pb^(2+),0.125 mg⋅L^(-1)Cd^(2+),5 mg⋅L^(-1)Cr^(6+))on gill tissue damage and cell apoptosis of larvae Carassius auratus indigentiaus were observed.The results showed that:(1)The 96-LC_(50) of Pb^(2+),Cd^(2+)and Cr^(6+) to larvae Carassius auratus indigentiaus were 39.5,0.39 and 16.38 mg⋅L^(-1),respectively,and the safe concentrations were 3.945,0.039 and 1.638 mg⋅L^(-1),respectively.The acute toxicity from strong to weak was Cd^(2+)>Pb^(2+)>Cr^(6+).(2)The 96-h mortality of larvae Carassius auratus indigentiaus treated with 5 mg⋅L^(-1)Cr^(6+)was about 37%,which caused serious damage to gill tissue of larvae Carassius auratus indigentiaus,including loose cell texture,a large number of pigment cells,cilia shedding,a large number of cells vacuolating,macrophages increasing,erosion and necrosis of connective tissue.The 96-h mortality rate of larvae Carassius auratus indigentiaus treated with 2 mg⋅L^(-1)Pb^(2+)and 0.125 mg⋅L^(-1)Cd^(2+)was about 16%and 58%,which caused slight damage in the gill tissue of larvae Carassius auratus indigentiaus,a slight increase of pigment cells,and vacuolation in a few cells.(3)2 mg⋅L^(-1)Pb^(2+),0.125 mg⋅L^(-1)Cd^(2+)and 5 mg⋅L^(-1)Cr^(6+) induced cell apoptosis in larvae Carassius auratus indigentiaus gill,and the cell apoptosis was the most serious in Pb^(2+)treatment group.To sum up,Pb^(2+),Cd^(2+)and Cr^(6+)have strong toxicity to larvae Carassius auratus indigentiaus,and there is no correlation between the death rate of each heavy metal treatment group of larvae Carassius auratus indigentiaus and tissue damage and cell apoptosis,which indicates that different heavy metals cause different death mechanisms of larvae Carassius auratus indigentiaus.