Individual and Synergistic Effects of Heavy-Metal Ions on the Induction of Cyanobacterial Metallothionein Examined by High-Performance Liquid Chromatography/Inductively Coupled Plasma Mass Spectrometry

摘要

The effects of Cu2+, Zn2+and Cd2+ ions on the induction of metallothionein (MT) in a cyanobacterium Anacystis nidulans R-2 have been studied by high-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometric (ICP/MS) detection. After growing the cells in media of systematically varied metal concentrations, the contents of each metal in induced MT were determined by HPLC-ICP/MS. By separate dosing of a metal ion, MT induction was clearly observed with Zn2+and Cd2+, but not with Cu2+ However, Cu2+induced MT in the presence of a high level (0.77μM) of Zn2+ A high level of Zn2+ also significantly promoted MT induction by Cd2+. These synergistic effects have revealed the predominant role of Zn2+in heavy-metal detoxification by the organism. The partition of Cu, Zn and Cd between the cytoplasm and the cell wall was studied for cells grown in a medium fairly enriched in the three heavy-metal ions.