title: Thiol compounds induction kinetics in marine phytoplankton during and after mercury exposure.
abstract: 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.
authors.affiliation: Division of Life Science, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Yun
authors.initials: Y
authors.lastname: Wu
authors.forename: Wen-Xiong
authors.initials: WX
authors.lastname: Wang
mesh_terms: D007700:Kinetics; D008628:Mercury / Q000633:toxicity*; D010839:Phytoplankton / Q000187:drug effects / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D013438:Sulfhydryl Compounds; D008628:Mercury