Zn2+和Cd2+对斑马鱼早期胚胎发育阶段的单一与联合毒性

研究了重金属Zn2+和Cd2+对斑马鱼(Danio rerio)早期胚胎发育阶段的单一与联合毒性效应。分别用不同质量浓度的Zn2+和Cd2+对受精后24 h(24 hpf)的受精卵进行染毒实验,统计了斑马鱼胚胎48 hpf的卵凝结和心律,72hpf的卵凝结、孵化率和畸形率等指标。结果显示,Zn2+和Cd2+对斑马鱼胚胎各不同发育阶段的影响不同,镉的毒性比锌大。斑马鱼胚胎对Zn2+和Cd2+最敏感的毒理学终点均为72 hpf。Zn2+和Cd2+对斑马鱼胚胎72 hpf的发育毒性比48 hpf的发育毒性大。Zn2+和Cd2+在毒性单位配比为1︰1时,对斑马鱼胚胎的联合毒性趋向于毒性剧增的协同作用。Zn2+和Cd2+在毒性单位配比为1:2时,对斑马鱼的联合毒性由48 hpf的协同作用转为72 hpf的拮抗作用。Zn2+和Cd2+在毒性单位配比为2︰1时,对斑马鱼的联合毒性在凝结时为协同作用,在孵化时为拮抗作用。结果表明,Zn2+和Cd2+在不同毒性单位配比下,对斑马鱼胚胎的联合毒性不完全相同。即使在同一毒性单位配比下,Zn2+和Cd2+对斑马鱼胚胎不同毒理学终点的联合毒性也不完全相同。此外还发现,联合作用不仅与化合物的剂量有关,还与染毒时间相关。

Individual and joint toxicity of Zn2+ and Cd2+ during the early embryonic development of zebrafish (Danio rerio)

We evaluated the individual and joint toxicity of zinc and cadmium during the early embryonic devel-opment of the zebrafish(Danio rerio).Embryos were exposed to various concentrations of Zn2+ and Cd2+ 24 h post-fertilization(24 hpf).We monitored the number of embryonic coagulated eggs and the rhythm of the heart at 48 hpf and the number of embryonic coagulated eggs,hatching rate,and malfomation rate at 72 hpf.The effects of Zn2+ and Cd2+ differed among the stages of development.In general,Zn2+ was more toxic than Cd2+.The embryos were most sensitive to Zn2+ and Cd2+ toxicity at 72 hpf.Regardless of the ratio of Zn2+ and Cd2+ during joint ex-posure(1﹕1,1﹕2 or 2﹕1),the two chemicals tended to act synergistically.However,the joint toxicity was de-fendant on the endpoints and the ratio of each metal.For example,at equal concentrations of Zn2+ and Cd2+(1﹕1),the effect tended to be synergistic.However,at a ratio of 1﹕2(Zn2+:Cd2+) the effect was synergistic at 48 hpf but antagonistic at 72 hpf.Furthermore,at a ratio of 2﹕1(Zn2+:Cd2+) the effect on egg coagulation was synergistic whereas the effect on the rate of hatching was antagonistic.Thus,our results suggest that joint toxicity is affected by both the concentration of each chemical and the exposure time.