Cai Yong, Su Jinhui, Ma Lena Q
Department of Chemistry and Biochemistry and Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA.
Environ Pollut. 2004 May;129(1):69-78. doi: 10.1016/j.envpol.2003.09.020.
Low molecular weight thiol-containing compounds have been reported to play an important role in metal detoxification and accumulation in some higher plants. The formation of these low molecular weight thiols in the recently discovered arsenic hyperaccumulator, Chinese Brake fern (Pteris vittata) upon exposure to arsenic and other trace metals was investigated. In addition to cysteine and glutathione, an unidentified thiol was observed in the plants exposed to arsenic, which was not found in the control. The concentration of the unidentified thiol showed a very strong and positive correlation with arsenic concentration in the leaflets. The unidentified thiol was low in rachises and undetectable in the roots for As-treated plants. Total and acid-soluble thiols were also measured and the results indicated that arsenic mainly stimulated the synthesis of acid-soluble thiol in Chinese Brake. The investigations of other trace elements (Cd, Cu, Cr, Zn, Pb, Hg, and Se) showed that these elements were not accumulated in Chinese Brake to high levels and the synthesis of the unidentified thiol in the plant was not observed. Our study suggests that the unidentified thiol was induced specifically by arsenic and the distribution patterns of the unidentified thiol and arsenic in the plant were consistent, indicating that the synthesis of this compound was related to As exposure.
据报道，低分子量含硫醇化合物在一些高等植物的金属解毒和积累过程中发挥着重要作用。我们研究了最近发现的砷超富集植物蜈蚣草（Pteris vittata）在暴露于砷和其他痕量金属时这些低分子量硫醇的形成情况。除了半胱氨酸和谷胱甘肽外，在暴露于砷的植物中还观察到一种未鉴定的硫醇，而在对照植物中未发现这种硫醇。未鉴定硫醇的浓度与小叶中的砷浓度呈现出非常强的正相关。对于经砷处理的植物，未鉴定硫醇在叶轴中的含量较低，在根中无法检测到。我们还测量了总硫醇和酸溶性硫醇，结果表明砷主要刺激了蜈蚣草中酸溶性硫醇的合成。对其他微量元素（镉、铜、铬、锌、铅、汞和硒）的研究表明，这些元素在蜈蚣草中不会大量积累，并且在植物中未观察到未鉴定硫醇的合成。我们的研究表明，未鉴定硫醇是由砷特异性诱导的，并且该未鉴定硫醇和砷在植物中的分布模式是一致的，这表明该化合物的合成与砷暴露有关。
