小麦根对镉离子的吸收机制及镉的亚细胞分布  

Uptake and Subcellular Distribution of Cadmium in Wheat(Triticum aestivum)Roots

作　　者：李丹丹[1,2] 周东美[1] 汪鹏[1,2] 翁南燕[1,2] 

机构地区：[1]中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室,南京210008 [2]中国科学院研究生院,北京100049

出　　处：《生态毒理学报》2010年第6期857-861,共5页Asian Journal of Ecotoxicology

基　　金：国家重点基础发展规划项目(No.2007CB936604)

摘　　要：小麦作为毒性实验推荐的标准物种之一,了解其对Cd的吸收过程及其致毒机理具有重要意义.应用Ca离子通道抑制剂LaCl3、巯基抑制剂N-乙烷基顺丁烯二酰亚胺(NEM)及能量代谢抑制剂2,4-二硝基苯酚(DNP),研究了小麦根对Cd的吸收;借鉴水生动物的亚细胞分离方法,在原有植物亚细胞分离方法上进行了改进,考察了Cd在小麦根中的亚细胞分布.8h的暴露吸收实验结果表明,LaCl3作为Ca离子通道抑制剂抑制小麦根对Cd的吸收高达30%;巯基抑制剂NEM没有表现出抑制效应,关于Cd与巯基的结合没有明确证据;在低浓度Cd条件下(0.25、1.0μM),DNP抑制其吸收,表明Cd是需要消耗能量进入细胞内,而在高浓度Cd条件下(5.0μM)则提高了Cd的吸收.Cd进入细胞内依次分布于胞液、细胞残渣、细胞器、微粒体,分布比例:胞液>细胞残渣、细胞器>微粒体;3种抑制剂均通过降低细胞器、提高胞液和微粒体中Cd分布来维持细胞的正常功能,降低Cd的毒性.The uptake of cadmium by wheat root was determined at varied Cd concentrations affected by different metabolic inhibiters（LaCl3：Ca-channel blocker;N-ethylmaleimide（NEM）：sulfhydryl inhibiter;2,4-dinitrophenol（DNP）：enzyme carrier inhibitor）over an 8h exposure.Results showed that the pre-exposure to Ca-channel blocker（Lanthanum）significantly inhibited Cd uptake,suggesting that Ca-channel was involved in the uptake of Cd.N-ethylmaleimide did not inhibit Cd uptake which suggested that no specific binding of Cd to sulfhydryl groups occurred.DNP as an enzyme carrier inhibitor decreased Cd uptake at Cd=0.25 and 1.0μM,implying that Cd uptake was partly to be active.The subcellular distribution of Cd was determined after different centrifugations.The result showed that Cd was mainly accumulated to the cytosol,and the three inhibitors via increasing the cytosol or granule and reducing the organelles fractions initiated the cellular detoxification mechanism.

关 键 词：重金属 生物有效性 亚细胞 

分 类 号：X171.5[环境科学与工程—环境科学] X173