Effects of copper, cadmium, and zinc on the production and exudation of thiols by Emiliania huxleyi
Effects of copper, cadmium, and zinc on the production and exudation of thiols by Emiliania huxleyi
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DOI：
10.4319/lo.2005.50.2.0508
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发表时间：
2005-03-01
影响因子：
4.5
通讯作者：
Ahner, BA
中科院分区：
文献类型：
--
作者：
Dupont, CL;Ahner, BA
无处不在的球石藻Emiliania huxleyi在现场相关的固定的自由离子浓度的铜，镉，锌的培养物散发出广泛的硫醇，其中一些随着金属离子浓度的增加而增加。释放的伯硫醇取决于添加到培养基中的特定金属或金属组合。暴露于Cu导致精氨酸-半胱氨酸、谷氨酰胺-半胱氨酸和半胱氨酸的释放; Cd导致这些硫醇和谷胱甘肽的释放;高Zn导致主要γ-谷氨酸-半胱氨酸（γ-Glu-Cys）的合成和渗出。由于这些实验中使用的铜和镉的自由离子浓度与现场观察到的浓度相似，因此活性渗出物可能是表层海水中硫醇的重要来源，从而可能影响公海中的微量金属形态。细胞内巯基浓度也明显受到金属浓度的影响，γ-Glu-Cys特别动态。此外，在分批培养中从指数增长到稳定增长的转变导致几乎所有细胞内硫醇的浓度下降约2 - 4倍。
Cultures of the ubiquitous coccolithophore Emiliania huxleyi grown at field-relevant fixed free ion concentrations of Cu, Cd, and Zn exude a broad array of thiols, some of which increase with increasing metal ion concentration. The primary thiols released are contingent on the particular metal or combination of metals added to the culture media. Exposure to Cu results in the release of arginine-cysteine, glutamine-cysteine, and cysteine; Cd causes these thiols and glutathione to be released; and high Zn results in the synthesis and exudation of predominantly gamma-glutamate-cysteine (gamma-Glu-Cys). Because the free ion concentrations of Cu and Cd used in these experiments are similar to those observed in the field, active exudation could be an important source of thiols to surface seawater and thus might affect trace metal speciation in the open ocean. Intracellular thiol concentrations were also clearly affected by metal concentrations, with gamma-Glu-Cys being particularly dynamic. Additionally, the shift from exponential to stationary growth in batch cultures caused approximately two- to fourfold declines in the concentrations of nearly all intracellular thiols.