State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Environ Pollut. 2012 Jun;165:18-24. doi: 10.1016/j.envpol.2012.02.009. Epub 2012 Mar 5.
The rootless duckweed Wolffia globosa can accumulate and tolerate relatively large amounts of arsenic (As); however, the underlying mechanisms were unknown. W. globosa was exposed to different concentrations of arsenate with or without l-buthionine sulphoximine (BSO), a specific inhibitor of γ-glutamylcysteine synthetase. Free thiol compounds and As(III)-thiol complexes were identified and quantified using HPLC - high resolution ICP-MS - accurate mass ESI-MS. Without BSO, 74% of the As accumulated in the duckweed was complexed with phytochelatins (PCs), with As(III)-PC(4) and As(III)-PC(3) being the main species. BSO was taken up by the duckweed and partly deaminated. The BSO treatment completely suppressed the synthesis of PCs and the formation of As(III)-PC complexes, and also inhibited the reduction of arsenate to arsenite. BSO markedly decreased both As accumulation and As tolerance in W. globosa. The results demonstrate an important role of PCs in detoxifying As and enabling As accumulation in W. globosa.
无根浮萍 Wolffia globosa 可以积累并耐受相对大量的砷 (As)；然而，其潜在的机制尚不清楚。W. globosa 暴露于不同浓度的砷酸盐，有无 l-丁硫氨酸亚砜 (BSO)，一种γ-谷氨酰半胱氨酸合成酶的特异性抑制剂。使用 HPLC - 高分辨率 ICP-MS - 精确质量 ESI-MS 鉴定和定量了游离巯基化合物和 As(III)-巯基复合物。没有 BSO，浮萍中积累的 74%的砷与植物螯合肽 (PCs) 结合，主要的物种是 As(III)-PC(4) 和 As(III)-PC(3)。BSO 被浮萍吸收并部分脱氨。BSO 处理完全抑制了 PCs 的合成和 As(III)-PC 复合物的形成，同时也抑制了砷酸盐向亚砷酸盐的还原。BSO 显著降低了 W. globosa 中砷的积累和砷的耐受性。结果表明，PCs 在解毒 As 和使 W. globosa 积累 As 方面发挥了重要作用。
