Pan Ke, Wang Wen-Xiong
Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
Aquat Toxicol. 2008 Dec 11;90(4):253-60. doi: 10.1016/j.aquatox.2008.09.010. Epub 2008 Oct 1.
Subcellular metal distribution has received increasing attention in aquatic toxicology studies, but the relationship between metal distribution and metal biokinetics remains largely unexplored. A series of short-term experiments on different concentrations of dissolved and dietary metals and on metal elimination were conducted to investigate the dynamics of subcellular distribution of Cd and Zn in the scallop Chlamys nobilis, a bivalve species that is known to accumulate very high concentrations of Cd and Zn in its tissues. Our results showed that, in general, both Cd and Zn were sequestered in insoluble forms (organelles, metal-rich granules, and cellular debris). The main binding pool for the newly acquired metals was organelles for Cd and cellular debris for Zn. Metallothionein-like protein (MTLP) was the most important storage pool for Cd in the scallops. Storage in the non-toxic form both in organelles and MTLP instead of through exocytosis was the major detoxification strategy to control Cd and accounted for the low efflux rate of Cd from scallops. In contrast to Cd, the main binding pool for Zn was cellular debris. Significant changes were found in the scallops when they were challenged with different concentrations of metals in the aqueous and food phases. Such changes provide important information on how scallops handle metals when there is increasing metal uptake. The redistribution of Zn among each subcellular compartment was much faster than the redistribution of Cd, suggesting an effective regulation mechanism for Zn in scallops. Thus, knowing subcellular metal distribution helps in studying the toxicity of both waterborne and dietborne metals.
亚细胞金属分布在水生毒理学研究中受到越来越多的关注，但金属分布与金属生物动力学之间的关系在很大程度上仍未得到探索。进行了一系列关于不同浓度溶解态和膳食态金属以及金属消除的短期实验，以研究华贵栉孔扇贝（一种已知在其组织中积累非常高浓度镉和锌的双壳类物种）中镉和锌的亚细胞分布动态。我们的结果表明，一般来说，镉和锌都以不溶性形式（细胞器、富含金属的颗粒和细胞碎片）被隔离。新获取金属的主要结合库对于镉是细胞器，对于锌是细胞碎片。金属硫蛋白样蛋白（MTLP）是扇贝中镉最重要的储存库。以无毒形式储存在细胞器和MTLP中而非通过胞吐作用是控制镉的主要解毒策略，这也解释了镉从扇贝中流出率较低的原因。与镉不同，锌的主要结合库是细胞碎片。当华贵栉孔扇贝在水相和食物相中受到不同浓度金属挑战时，发现了显著变化。这些变化为了解扇贝在金属摄取增加时如何处理金属提供了重要信息。锌在各亚细胞区室之间的重新分布比镉快得多，这表明扇贝对锌有有效的调节机制。因此，了解亚细胞金属分布有助于研究水相和膳食来源金属的毒性。
