The importance of zinc (Zn) as a nutrient and its ability to be substituted for by cobalt (Co) have been characterized in model marine diatoms. However, the extent to which this substitution capability is distributed among diatom taxa is unknown. Zn/Co metabolic substitution was assayed in four diatom species as measured by the effect of free ion concentrations of Zn²⁺ and Co²⁺ on specific growth rate. Analysis of growth responses found substitution of these metals can occur within the northwest Atlantic isolate Thalassiosira pseudonana CCMP1335, the northeast Atlantic isolate Phaeodactylum tricornutum CCMP632, and within the northeast Pacific isolates Pseudo‐nitzschia delicatissima UNC1205 and Thalassiosira sp. UNC1203. Metabolic substitution of Co in place of Zn in the Atlantic diatoms supports their growth in media lacking added Zn, but at the cost of reduced growth rates. In contrast, highly efficient Zn/Co substitution that supported growth even in media lacking added Zn was observed in the northeast Pacific diatoms. We also present new data from the northeast Pacific Line P transect that revealed dissolved Co and Zn ratios (dCo : dZn) as high as 3.52 : 1 at surface (0–100 m) depths. We posit that the enhanced ability of the NE Pacific diatoms to grow using Co is an adaptation to these high surface dCo : dZn ratios. Particulate metal data and single‐cell metal quotas also suggest a high Zn demand in diatoms that may be partially compensated for by Co.

中文翻译：

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东北太平洋硅藻中有效的锌/钴相互置换及其与高表面溶解Co：Zn比的关系

在模型海洋硅藻中已表征了锌（Zn）作为营养物的重要性及其被钴（Co）替代的能力。但是，这种替代能力在硅藻类群中分布的程度尚不清楚。通过自由离子浓度Zn ²⁺和Co ²⁺对特定生长速率的影响，在四种硅藻物种中测定了Zn / Co代谢取代。发现这些金属的替代生长反应分析可以在大西洋西北部分离内发生海链pseudonana CCMP1335，大西洋东北部分离三角褐指藻CCMP632，与东北太平洋内隔离拟菱形藻柔弱UNC1205和Thalassiosira sp。UNC1203。在大西洋硅藻中，Co代替Zn的代谢替代作用支持了它们在缺乏添加Zn的培养基中的生长，但以降低的生长速率为代价。相反，在东北太平洋硅藻中观察到高效的Zn / Co替代，即使在缺乏添加Zn的培养基中也支持生长。我们还提供了来自东北太平洋线P断面的新数据，该数据揭示了在表面（0-100 m）深度处溶解的Co和Zn之比（dCo：dZn）高达3.52：1。我们认为，使用Co增强NE太平洋硅藻生长的能力是对这些高表面dCo：dZn比的适应。颗粒金属数据和单细胞金属配额也表明，硅藻对锌的需求很高，这可能会被钴部分弥补。