Aborode Fatai Adigun, Raab Andrea, Voigt Matthias, Costa Leticia Malta, Krupp Eva M, Feldmann Joerg
Trace Element Speciation Laboratory, Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, Scotland, UK.
Trace Element Speciation Laboratory, Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, Scotland, UK.
J Environ Sci (China). 2016 Nov;49:150-161. doi: 10.1016/j.jes.2016.08.009. Epub 2016 Sep 18.
We investigated the role of glutathione (GSH) and phytochelatins (PCs) on the detoxification of selenite using Arabidopsis thaliana. The wild-type (WT) of Arabidopsis thaliana and its mutants (glutathione deficient Cad 2-1 and phytochelatins deficient Cad 1-3) were separately exposed to varying concentrations of selenite and arsenate and jointly to both toxicants to determine their sensitivities. The results of the study revealed that, the mutants were about 20-fold more sensitive to arsenate than the WT, an indication that the GSH and PCs affect arsenate detoxification. On the contrary, the WT and both mutants showed a similar level of sensitivity to selenite, an indication that the GSH and PCs do not significantly affect selenite detoxification. However, the WT is about 8 times more sensitive to selenite than to arsenate, and the mutants were more resistant to selenite than arsenate by a factor of 2. This could not be explained by the accumulation of both elements in roots and shoots in exposure experiments. The co-exposure of the WT indicates a synergistic effect with regards to toxicity since selenite did not induce PCs but arsenic and selenium compete in their PC binding as revealed by speciation analysis of the root extracts using HPLC-ICP-MS/ESI-MS. In the absence of PCs an antagonistic effect has been detected which might suggest indirectly that the formation of Se glutathione complex prevent the formation of detrimental selenopeptides. This study, therefore, revealed that PC and GSH have only a subordinate role in the detoxification of selenite.
我们利用拟南芥研究了谷胱甘肽（GSH）和植物螯合肽（PCs）在亚硒酸盐解毒过程中的作用。将拟南芥野生型（WT）及其突变体（谷胱甘肽缺陷型Cad 2-1和植物螯合肽缺陷型Cad 1-3）分别暴露于不同浓度的亚硒酸盐和砷酸盐中，并同时暴露于两种毒物中，以确定它们的敏感性。研究结果表明，突变体对砷酸盐的敏感性比野生型高约20倍，这表明GSH和PCs影响砷酸盐解毒。相反，野生型和两种突变体对亚硒酸盐的敏感性水平相似，这表明GSH和PCs对亚硒酸盐解毒没有显著影响。然而，野生型对亚硒酸盐的敏感性比对砷酸盐高约8倍，而突变体对亚硒酸盐的抗性比对砷酸盐高2倍。这无法通过暴露实验中根和地上部两种元素的积累来解释。野生型的共同暴露表明在毒性方面存在协同效应，因为亚硒酸盐不会诱导PCs，但通过使用HPLC-ICP-MS/ESI-MS对根提取物进行形态分析发现，砷和硒在它们与PC的结合中存在竞争。在没有PCs的情况下检测到一种拮抗作用，这可能间接表明硒谷胱甘肽复合物的形成阻止了有害硒肽的形成。因此，这项研究表明PC和GSH在亚硒酸盐解毒中仅起次要作用。
