Vázquez M D, López J, Carballeira A
Ecoloxía, Facultade de Bioloxía, Universidade de Santiago de Compostela, Santiago de Compostela, 15706, Spain.
Ecotoxicol Environ Saf. 1999 Sep;44(1):12-24. doi: 10.1006/eesa.1999.1798.
Shoot tips of Fontinalis antipyretica, Scapania undulata, and Fissidens polyphyllus were maintained for 60 min with solutions containing 0, 1, 10, 50, 100, or 200 ppm of Cd, Co, Cu, Ni, Pb, or Zn. A sequential extraction procedure was then used to estimate the amounts of the corresponding metal, and of K and Mg, in the extracellular compartment (extraction with NiCl(2) or EDTA), the intracellular compartment (subsequent extraction with cold dilute HNO(3)), and the particulate fraction (subsequent extraction with hot concentrated HNO(3)). In most cases more metal was taken up to the extracellular compartment than to the intracellular compartment, while particulate-fraction content was negligible. The relationship between metal concentration in the water and metal content in the extracellular compartment was well modeled with a Michaelis-Menten-type equation. Results suggest that in S. undulata extracellular cation-binding sites have a high metal affinity, while in F. polyphyllus it is relatively low. However, postincubation intracellular contents were highest in the latter species. The ranking of the six metals by amounts taken up into the intracellular compartment was the same for all three bryophyte species. Uptake of heavy metals led to considerable losses of intracellular K (probably due to effects on plasma membrane properties), and of extracellular Mg (probably due to displacement from cation-binding sites). Losses of intracellular K were most marked in S. undulata, followed by F. antipyretica. By contrast, S. undulata was the species from which losses of extracellular Mg were lowest.
将水生藓类、波叶合叶苔和多叶凤尾藓的茎尖分别置于含有0、1、10、50、100或200 ppm镉、钴、铜、镍、铅或锌的溶液中处理60分钟。然后采用连续萃取法来估算细胞外部分（用NiCl₂或EDTA萃取）、细胞内部分（随后用冷稀硝酸萃取）和颗粒部分（随后用热浓硝酸萃取）中相应金属以及钾和镁的含量。在大多数情况下，细胞外部分摄取的金属比细胞内部分多，而颗粒部分的含量可忽略不计。水中金属浓度与细胞外部分金属含量之间的关系可用米氏方程很好地模拟。结果表明，在波叶合叶苔中，细胞外阳离子结合位点对金属的亲和力较高，而在多叶凤尾藓中则相对较低。然而，孵育后多叶凤尾藓细胞内的含量最高。所有三种苔藓植物细胞内摄取的六种金属量的排序相同。重金属的摄取导致细胞内钾（可能是由于对质膜特性的影响）和细胞外镁（可能是由于从阳离子结合位点被取代）大量流失。细胞内钾的流失在波叶合叶苔中最为明显，其次是水生藓类。相比之下，波叶合叶苔细胞外镁的流失量最低。
