硒预暴露对夹杂带丝蚓铜累积及毒性的影响

Effects of pre-exposure to selenium on the accumulation and toxicity of copper in Lumbriculus variegatus

为研究不同摄入途径下不同形态的硒(Se)预暴露对铜(Cu)在夹杂带丝蚓(Lumbriculus variegatus)体内的累积及Cu暴露导致的脂质过氧化的影响,本实验将夹杂带丝蚓分别预暴露在含亚硒酸盐(Se(Ⅳ))、硒酸盐(Se(Ⅵ))、L-硒甲硫氨酸(Se-L-Met)的沉积物(食物相,20μg·g^(-1)干重)和水溶液(15μg·L^(-1))中,再将Se预暴露的带丝蚓暴露于15μg·L^(-1)的Cu 7天,检测其体内Cu累积及硫代巴比妥酸反应产物水平。结果显示:除水相Se(Ⅵ)预暴露组外,食物相及水相预暴露摄入的Se均显著降低了Cu在带丝蚓体内的累积;Se预暴露降低了Cu对带丝蚓造成的过氧化损伤,但不同暴露途径可能对不同形态Se的这种保护能力也有影响。结果表明,环境相关浓度的Se预暴露能够降低Cu的累积及对Cu暴露在夹杂带丝蚓所产生的毒性提供保护作用,但这种保护作用的机制有待进一步的研究。

The present study assessed the effects of preexposure to Se on the accumulation and toxicity of copper （Cu） in Lumbriculus variegatus. Furthermore, the effects of exposure routes and the Se species were also evaluated. L. variegatus were preexposed to environmentally relevant concentration of Se in sediment （dietary at 20 μg·g-1 dry wt） or in solution （dissolved at 15 μg·L-1） for 2 weeks. The Se species included selenite （Se（Ⅳ））, selenate （Se（Ⅵ）） and selenoLmethionine （Se-L-Met）. The Se preexposed L. variegatus were subsequently exposed to 15 μg·L-1 of Cu for 7 days. The accumulation of Cu and the levels of thiobarbituric acid reactive substances （TBARS） were determined. The results showed that mortality did not occur in all the treatments except for the Se-L-Met sediment treatment during the 2 week exposures. Preexposure to all the three forms of Se from both the dietary and dissolved routes significantly decreased the accumulation of Cu in the worms except for preexposure to dissolved Se（Ⅵ）. The Se preexposed worms had significantly lower levels of TBARS than the control worms. The protective potential of pre-exposure to Se against Cu toxicity was in the order as Se（Ⅵ） 〉 Se（Ⅳ） ≈ Se-L-Met in the dissolved exposure, while in the dietary exposure, the protective potential of the three species was comparable. The results suggested that preexposure to Se at environmentally realistic concentrations can offer protection against Cu toxicity in L. variegatus. Future research on the interaction of Se and Cu is warranted to better understand the mechanisms underlying this protection in the worm in particular and possibly in other aquatic organisms in general.