Vijver Martina G, van Gestel Cornelis A M, van Straalen Nico M, Lanno Roman P, Peijnenburg Willie J G M
Institute of Ecological Science, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
Environ Toxicol Chem. 2006 Mar;25(3):807-14. doi: 10.1897/05-128r.1.
Metal ions in excess of metabolic requirements are potentially toxic and must be removed from the vicinity of important biological molecules to protect organisms from adverse effects. Correspondingly, metals are sequestrated in various forms, defining the accumulation pattern and the magnitude of steady-state levels reached. To investigate the subcellular fractions over which Ca, Mg, Fe, Cu, Zn, Cd, Pb, Ni, and As are distributed, earthworms (Aporrectodea caliginosa) collected from the field were analyzed by isolating metal-rich granules and tissue fragments from intracellular microsomal and cytosolic fractions (i.e., heat-stable proteins and heat-denatured proteins). The fractions showed metal-specific binding capacity. Cadmium was mainly retrieved from the protein fractions. Copper was equally distributed over the protein fraction and the fraction comprising tissue fragments, cell membranes, and intact cells. Zinc, Ca, Mg, and As were mainly found in this fraction as well. Lead, Fe, and Ni were mainly isolated from the granular fraction. To study accumulation kinetics in the different fractions, three experiments were conducted in which earthworms were exposed to metal-spiked soil and a soil contaminated by anthropogenic inputs and, indigenous earthworms were exposed to field soils. Although kinetics showed variation, linear uptake and steady-state types of accumulation patterns could be understood according to subcellular compartmentalization. For risk assessment purposes, subcellular distribution of metals might allow for a more precise estimate of effects than total body burden. Identification of subcellular partitioning appears useful in determining the biological significance of steady-state levels reached in animals.
超过代谢需求的金属离子具有潜在毒性，必须从重要生物分子附近清除，以保护生物体免受不良影响。相应地，金属以各种形式被螯合，这决定了其积累模式和达到的稳态水平的大小。为了研究钙、镁、铁、铜、锌、镉、铅、镍和砷在哪些亚细胞组分中分布，对从野外采集的蚯蚓（暗色异唇蚓）进行了分析，通过从细胞内微粒体和胞质组分（即热稳定蛋白和热变性蛋白）中分离富含金属的颗粒和组织碎片。这些组分显示出金属特异性结合能力。镉主要从蛋白质组分中回收。铜在蛋白质组分以及包含组织碎片、细胞膜和完整细胞的组分中均匀分布。锌、钙、镁和砷也主要存在于该组分中。铅、铁和镍主要从颗粒组分中分离出来。为了研究不同组分中的积累动力学，进行了三个实验，其中蚯蚓暴露于添加金属的土壤和受人为输入污染的土壤，以及本地蚯蚓暴露于田间土壤。尽管动力学表现出差异，但根据亚细胞区室化可以理解线性摄取和稳态类型的积累模式。出于风险评估目的，金属的亚细胞分布可能比总体负担更能精确估计影响。确定亚细胞分配在确定动物体内达到的稳态水平的生物学意义方面似乎很有用。
