Division of Life Science, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong.
Environ Sci Technol. 2012 Oct 2;46(19):10765-71. doi: 10.1021/es302040g. Epub 2012 Sep 12.
Oyster Crassostrea hongkongensis, a widely cultivated oyster species in Southern China, can accumulate metals (especially for Cu and Zn) to extraordinarily high concentrations (up to 3% of body dry weight). It remains unknown how they were acclimated to contaminated environment and built up such high metal concentrations in their bodies. A seven month transplantation experiment was conducted to rebuild the physiological process of acclimation in oysters to illustrate how they cope with increasing metal bioavailability. The metal concentrations increased substantially in the transplanted oysters from a reference site to a contaminated site. Our results showed that metal biokinetics in the oysters changed dramatically after suffering from metal stress. The clearance rate, dissolved uptake rate (for Cd and Zn), and metal assimilation efficiency (for Zn) was depressed, while the metal efflux rate (for Zn) was enhanced in the contaminated oysters. Beside the change of metal homeostasis, the oysters were able to sequester metals into subcellular nontoxic forms and maintain a low portion of metals distributing in the metal-sensitive fraction. This comparative bioaccumulation study of C. hongkongensis suggested that adjustment of metal biokinetics played an important role in the survival of oysters in metal contaminated environment.
中国南方广泛养殖的牡蛎物种——蚝（Crassostrea hongkongensis），能够积累极高浓度的金属（尤其是 Cu 和 Zn），浓度高达其体重的 3%。目前尚不清楚它们是如何适应受污染的环境，并在体内积累如此高浓度的金属。我们进行了为期七个月的移植实验，以重建牡蛎适应环境的生理过程，阐明它们如何应对金属生物利用度的增加。结果显示，从参照点移植到污染点的牡蛎体内金属浓度显著增加。我们的研究结果表明，金属胁迫后牡蛎体内的金属生物动力学发生了显著变化。在污染牡蛎中，清除率、溶解吸收率（Cd 和 Zn）和金属同化效率（Zn）降低，而 Zn 的金属外排率增加。除了金属稳态的变化外，牡蛎还能够将金属蓄积到亚细胞无毒形式，并维持金属在金属敏感部分的低分布比例。这项关于蚝的生物累积比较研究表明，金属生物动力学的调节在牡蛎适应金属污染环境的生存中起着重要作用。
