Shi Dalin, Wang Wen-Xiong
Department of Biology, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong.
Environ Pollut. 2004 Nov;132(2):265-77. doi: 10.1016/j.envpol.2004.04.023.
To examine the Cd, Hg, Ag, and Zn accumulation in the green mussel Perna viridis affected by previous exposure to Cu, Ag, or Zn, the dietary metal assimilation efficiency (AE) and the uptake rate from the dissolved phase were quantified. The mussel's filtration rate, metallothionein (MT) concentration, and metal tissue burden as well as the metal subcellular partitioning were also determined to illustrate the potential mechanisms underlying the influences caused by one metal pre-exposure on the bioaccumulation of the other metals. The green mussels were pre-exposed to Cu, Ag, or Zn for different periods (1-5 weeks) and the bioaccumulation of Cd, Hg, Ag, and Zn were concurrently determined. Pre-exposure to the three metals did not result in any significant increase in MT concentration in the green mussels. Ag concentration in the insoluble fraction increased with increasing Ag exposure period and Ag ambient concentration. Our data indicated that Cd assimilation were not influenced by the mussel's pre-exposure to the three metals (Cu, Ag, and Zn), but its dissolved uptake was depressed by Ag and Zn exposure. Although Hg assimilation from food was not affected by the metal pre-exposure, its influx rate from solution was generally inhibited by the exposure to Cu, Ag, and Zn. Ag bioaccumulation was affected the most obviously, in which its AE increased with increasing Ag tissue concentration, and its dissolved uptake decreased with increasing tissue concentrations of Ag and Cu. As an essential metal, Zn bioaccumulation remained relatively stable following the metal pre-exposure, suggesting the regulatory ability of Zn uptake in the mussels. Zn AE was not affected by metal pre-exposure, but its dissolved uptake was depressed by Ag and Zn pre-exposure. All these results indicated that the influences of one metal pre-exposure on the bioaccumulation of other metals were metal-specific due to the differential binding and toxicity of metals to the mussels. Such factors should be considered in using metal concentrations in mussel's soft tissues to evaluate the metal pollution in coastal waters.
为研究先前暴露于铜、银或锌对翡翠贻贝中镉、汞、银和锌积累的影响，对膳食中金属的同化效率（AE）以及溶解相中金属的摄取率进行了量化。还测定了贻贝的滤食率、金属硫蛋白（MT）浓度、金属组织负荷以及金属的亚细胞分配情况，以阐明一种金属预暴露对其他金属生物积累产生影响的潜在机制。将翡翠贻贝预先暴露于铜、银或锌不同时间段（1 - 5周），并同时测定镉、汞、银和锌的生物积累情况。预先暴露于这三种金属并未导致翡翠贻贝中MT浓度有任何显著增加。不溶性部分中的银浓度随银暴露时间和银环境浓度的增加而增加。我们的数据表明，镉的同化不受贻贝预先暴露于这三种金属（铜、银和锌）的影响，但其从溶解相的摄取受到银和锌暴露的抑制。尽管食物中汞的同化不受金属预暴露的影响，但其从溶液中的流入速率通常受到铜、银和锌暴露的抑制。银的生物积累受到的影响最为明显，其中其AE随银组织浓度的增加而增加，其从溶解相的摄取随银和铜组织浓度的增加而减少。作为一种必需金属，锌的生物积累在金属预暴露后保持相对稳定，表明贻贝对锌摄取具有调节能力。锌的AE不受金属预暴露的影响，但其从溶解相的摄取受到银和锌预暴露的抑制。所有这些结果表明，一种金属预暴露对其他金属生物积累的影响因金属与贻贝的结合和毒性差异而具有金属特异性。在利用贻贝软组织中的金属浓度评估沿海水域的金属污染时，应考虑这些因素。
