低游离金属离子浓度下海洋浮游植物产生植物螯合肽的研究：马萨诸塞湾的实验室研究和现场数据
Phytochelatin production by marine phytoplankton at low free metal ion concentrations: laboratory studies and field data from Massachusetts Bay.
作者信息
Ahner B A, Price N M, Morel F M
机构信息
R. M. Parsons Laboratory, Massachusetts Institute of Technology, Cambridge 02139.
出版信息
Proc Natl Acad Sci U S A. 1994 Aug 30;91(18):8433-6. doi: 10.1073/pnas.91.18.8433.
Phytochelatins are small metal-binding polypeptides synthesized by algae in response to high metal concentrations. Using a very sensitive HPLC method, we have quantified phytochelatins from phytoplankton in laboratory cultures at environmentally relevant metal concentrations and in marine field samples. Intracellular concentrations of phytochelatin, in the diatom Thalassiosira weissflogii, exhibit a distinct dose-response relation with free Cd2+ concentration in the medium--not with total Cd(2+)--and are detectable even when the free Cd2+ concentration is less than 1 pM. In Massachusetts Bay, phytochelatin levels (normalized to chlorophyll a) in the particulate fraction are similar to those measured in laboratory cultures exposed to picomolar free Cd2+ concentrations and exhibit a decreasing seaward trend. Incubations of natural samples with added Cd2+ confirmed the induction of the peptides by this metal. Ambient phytochelatin concentrations thus appear to provide a measure of the metal stress resulting from the complex mixture of trace metals and chelators in natural waters.
植物螯合肽是藻类在高金属浓度条件下合成的小型金属结合多肽。我们采用一种非常灵敏的高效液相色谱法，对实验室培养的浮游植物以及海洋野外样本中与环境相关的金属浓度下的植物螯合肽进行了定量分析。在硅藻威氏海链藻中，细胞内植物螯合肽的浓度与培养基中游离Cd2+的浓度呈现出明显的剂量反应关系，而非与总Cd(2+)的浓度，并且即使游离Cd2+浓度低于1 pM时也可检测到。在马萨诸塞湾，颗粒部分中植物螯合肽水平（以叶绿素a进行标准化）与暴露于皮摩尔级游离Cd2+浓度的实验室培养物中测得的水平相似，并且呈现出向海递减的趋势。向天然样本中添加Cd2+进行孵育证实了这种金属可诱导这些肽的产生。因此，环境中植物螯合肽的浓度似乎可衡量天然水体中痕量金属和螯合剂的复杂混合物所导致的金属胁迫程度。
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