HEAVY METALS IN HYPERACUMULATOR PLANTS

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。植物对重金属的吸收不仅是一个重要的基础研究领域，而且对人类的营养及其在污染土壤的植物修复以及从天然富含金属的土壤中商业提取金属的应用也有影响，否则不适合常规的采矿作业。这些植物能够在其地上部分的干块中积累百分之几的金属。这些植物的不同寻常的生理是世界范围内深入研究的主题，植物中金属的形态是目前最有趣的研究主题之一。在最近的一项研究中(Képper等人，2004年)，在表皮包含最大组织体积的组织(例如叶片)中，发现了主要是弱氧配体。在其他组织中，相当大比例的配体是强配体(镉的硫配体和锌的组氨酸)。计划中的项目将通过直接测量冷冻水合样品中不同功能的单个选定细胞的EXAFF，阐明组织之间的这些差异是否真的源于特定细胞类型中金属的不同形态。这一知识将揭示不同的组织或同一组织中具有不同功能的细胞是否需要不同的保护策略来抵御重金属毒性。这样的差异已经被假定，但到目前为止从未被调查过。2004年7月的初步研究指出了今后成功完成这些实验所需解决办法方面的问题和解决办法。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Heavy metal uptake in plants is not only an important basic research area, but also has an impact on human nutrition and its application for the phytoremediation of contaminated soils as well as for the commercial extraction of metals from naturally metal-rich soils otherwise unsuitable for conventional mining operations. These plants are able to accumulate several percent of metals in the dry mass of their above-ground parts. The unusual physiology of these plants is a topic of intensive worldwide research efforts, being the speciation of the metals inside the plant one of the presently most interesting research topics. In a recent study (K¿pper et al., 2004) in tissues where the epidermis comprises the largest tissue volume (e.g. leaves), mainly weak oxygen ligands were found. In other tissues, a significant proportion of the ligands were strong ligands (sulphur ligands for cadmium and histidine for zinc). The planned project shall elucidate, by directly measuring EXAFS of individual selected cells of various functions, in frozen-hydrated samples, whether these differences between tissues really originate from a different speciation of the metal in specific cell types. This knowledge would reveal if different tissues, or cells with different function in the same tissue, may need a different strategy of protection from heavy metal toxicity. Such differences have been assumed but so far were never investigated. Preliminary studies in July 2004 pointed out problems and solutions regarding the resolution needed for a future successful completion of these experiments.