title: Metal accumulation and toxicity: the critical accumulated concentration of metabolically available zinc in an oyster model.
abstract: Invertebrates typically carry out detoxification of accumulated metals. There is, therefore, no threshold total body concentration of accumulated metal initiating toxicity, the onset of toxic effects rather being related to a critical concentration of metabolically available (MA) accumulated metal. The challenge remains as to whether any particular combination of subcellular fractions of accumulated metal can be identified to represent this theoretical MA component. One candidate combined fraction is the so-termed metal sensitive fraction (MSF), consisting of metal bound to organelles and non-detoxificatory soluble proteins. In this study, we used laboratory zinc accumulation and toxicity data for four populations of the oyster Crassostrea hongkongensis with different histories of zinc exposure in the field to address the challenge. We conclude that in a 'control' population of the oyster, the MSF does approximate to the theoretical metabolically available zinc concentration. In populations with a history of field exposure to raised zinc bioavailabilities, however, the MSF would include more zinc detoxified in the lysosome component of organelle-bound metal, and the MSF in such populations would deviate more from the theoretical MA metal concentration.
authors: Department of Life Sciences, Natural History Museum, Cromwell Rd., London SW7 5BD, United Kingdom. Electronic address: philipstephenrainbow@gmail.com.
authors: Philip S
authors: PS
authors: Rainbow
authors: Division of Life Science, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay Kowloon, Hong Kong.
authors: Fengjie
authors: F
authors: Liu
authors: Division of Life Science, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay Kowloon, Hong Kong.
authors: Wen-Xiong
authors: WX
authors: Wang
mesh_terms: D000818:Animals; D001682:Biological Availability; D049896:Crassostrea / Q000187:drug effects* / Q000378:metabolism; D000075322:Heavy Metal Poisoning; D008658:Inactivation, Metabolic; D019216:Metals, Heavy / Q000378:metabolism / Q000493:pharmacokinetics / Q000633:toxicity; D011041:Poisoning / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000493:pharmacokinetics* / Q000633:toxicity; D015032:Zinc / Q000378:metabolism / Q000493:pharmacokinetics* / Q000633:toxicity
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; D015032:Zinc
keywords: Metabolically available metal; Metal sensitive fraction; Subcellular fractionation; Trace metal toxicity