Division of Life Science, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong.
J Hazard Mater. 2012 May 30;217-218:271-8. doi: 10.1016/j.jhazmat.2012.03.024. Epub 2012 Mar 20.
We investigated the kinetics of Hg(II) and MeHg accumulation and the synthesis of phytochelatins (PCs), cysteine (Cys), glutathione (GSH), and γ-glutamylcysteine (γ-EC) in a marine diatom Thalassiosira weissflogii during a 3-h (short-term) and a 96-h (long-term) exposure period, and during a subsequent 96-h recovery period. MeHg induced the synthesis of a significant level of GSH, but it was Hg(II) that gave rise to significant levels of other non-protein thiol compounds. The thiol compounds Cys, γ-EC, and PC(2-3) were induced in T. weissflogii within the first 30 min of exposure, followed by PC(4), but the concentrations of all six compounds returned to the control levels after the 96-h recovery period. The kinetics of these non-protein thiol compounds pointed to a rapid cellular response to environmental mercury pollution. After a first decrease, the molar ratio of PC-SH (sulfhydryl in PCs) to intracellular Hg increased slightly which demonstrated the role of PCs in Hg(II) detoxification. However, PC-SH was bound with Hg(II) at a stoichiometric ratio of 0.1-0.3, indicating the involvement of other detoxification mechanisms. Elucidating the effects of mercury on intracellular non-protein thiol pools may help us better understand the metal detoxification in phytoplankton.
我们研究了海洋硅藻塔玛亚历山大藻在 3 小时（短期）和 96 小时（长期）暴露期以及随后 96 小时恢复期内汞（II）和甲基汞（MeHg）积累的动力学，以及植物螯合肽（PCs）、半胱氨酸（Cys）、谷胱甘肽（GSH）和γ-谷氨酰半胱氨酸（γ-EC）的合成。MeHg 诱导 GSH 大量合成，但只有 Hg（II）才能诱导其他非蛋白巯基化合物大量合成。在暴露的头 30 分钟内，Cys、γ-EC 和 PC（2-3）这三种巯基化合物就在塔玛亚历山大藻中被诱导产生，随后是 PC（4），但在 96 小时恢复期后，所有六种化合物的浓度都恢复到对照水平。这些非蛋白巯基化合物的动力学表明，细胞对环境汞污染有快速的反应。在第一次下降之后，PC-SH（PC 中的巯基）与细胞内 Hg 的摩尔比略有增加，这表明 PC 在 Hg（II）解毒中的作用。然而，PC-SH 与 Hg（II）以 0.1-0.3 的化学计量比结合，表明涉及其他解毒机制。阐明汞对细胞内非蛋白巯基池的影响可能有助于我们更好地理解浮游植物中的金属解毒。
