藻细胞膜电信号对重金属的快速反应研究

为探讨藻细胞膜电信号对重金属离子的响应特征,运用细胞外表面技术和电化学方法研究了淡水藻——大型轮藻(Nitellaflexilis)藻细胞膜电位和膜电阻对汞、镉、铅的快速反应.结果表明,细胞膜电位和膜电阻对汞、镉响应灵敏且快速,30min内即对1μmol·L-1Hg2+、Cd2+表现出超极化和膜电阻增大反应,而5、10μmol·L-1Hg2+、Cd2+则在15min内引起细胞去极化、膜电阻减小,且剂量效应显著.细胞膜电信号对Pb2+的响应浓度为100μmol·L-1,30min内细胞先去极化后超极化,膜电阻持续增大.重金属作用前后相比,高浓度Hg2+、Cd2+(5、10μmol·L-1)导致藻细胞不可逆损伤,而其低浓度所致的损伤可恢复.Pb2+致藻细胞不可逆损伤的最低浓度为500μmol·L-1.对比膜电信号对3种离子的响应特点,发现藻细胞膜电位和膜电阻对Hg2+和Cd2+的响应灵敏度大于Pb2+.

Study on Rapid Responses of Algae Cell Membrane Electric Signal to Heavy Metals

To discuss the response characteristic of algae cell membrane electric signal to heavy metal ions, rapid reactions of freshwater algae cell(Nitella flexilis)membrane potential(MP)and membrane resistance(MR)to mercury, cadmium and lead were studied by extra-cellular technique and electrochemistry. Results showed that MP and MR were sensitive to mercury and cadmium. Algae cells were quickly hyperpolarized and MR rapidly increased within 30min under the exposure of 1μmol·L-1 Hg2+ or Cd2+, but Hg2+, Cd2+ of 5 and 10μmol·L-1 induced cells depolarization and MR reduction in 15min. The concentration threshold of cell membrane electric signal distinctly responding to Pb2+ was 100μmol·L-1. And in 30min, the cell rapidly depolarized and then hyperpolarized, meanwhile, MR increased continuously. Hg2+ and Cd2+ with high concentration(5?10μmol·L-1)irreversibly damaged algae cells, but damages to cells can be restored in low concentration groups. The lowest effective concentration of Pb2+ which engendered irreversible damage to algae cells was 500μmol·L-1. Comparing response characteristics of membrane electric signal to these three heavy metal ions, we found that algae membrane potential and membrane resistance were more sensitive to Hg2+ or Cd2+ than Pb2+.