The requirement for external carbonic anhydrase in diatoms is influenced by the supply and demand for dissolved inorganic carbon
The requirement for external carbonic anhydrase in diatoms is influenced by the supply and demand for dissolved inorganic carbon
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DOI：
10.1111/jpy.13416
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发表时间：
2023-12-21
影响因子：
2.9
通讯作者：
Wheeler，Glen L.
中科院分区：
文献类型：
--
作者：
Keys，Matthew;Hopkinson，Brian;Wheeler，Glen L.
海洋硅藻的光合作用对全球碳循环有重要贡献。由于海水中CO2浓度较低，许多硅藻利用胞外碳酸酐酶（eCA）来增加细胞表面CO2的供应。虽然许多研究已经调查了eCA的需求如何受到CO2可用性变化的影响，但对eCA如何在碳需求变化后对CO2供应做出贡献知之甚少。因此，我们研究了光合速率的变化如何影响三个中心硅藻的eCA的要求。细胞表面碳酸盐化学建模表明，扩散CO2供应到细胞表面大大减少在大硅藻在较高的光合速率。实验室实验表明，随着光合速率的增加，对eCA的需求量也在增加，这在较大的物种中最为明显，这支持了细胞建模的结果。细胞表面pH和O2的微电极测量表明，个别细胞表现出增加的贡献eCA光合作用在较高的辐照度。我们的数据表明，碳需求的变化强烈影响硅藻对eCA的需求。因此，细胞大小和光合速率将是溶解无机碳吸收模式的关键决定因素。
Photosynthesis by marine diatoms contributes significantly to the global carbon cycle. Due to the low concentration of CO2in seawater, many diatoms use extracellular carbonic anhydrase (eCA) to enhance the supply of CO2to the cell surface. While much research has investigated how the requirement for eCA is influenced by changes in CO2availability, little is known about how eCA contributes to CO2supply following changes in the demand for carbon. We therefore examined how changes in photosynthetic rate influence the requirement for eCA in three centric diatoms. Modeling of cell surface carbonate chemistry indicated that diffusive CO2supply to the cell surface was greatly reduced in large diatoms at higher photosynthetic rates. Laboratory experiments demonstrated a trend of an increasing requirement for eCA with increasing photosynthetic rate that was most pronounced in the larger species, supporting the findings of the cellular modeling. Microelectrode measurements of cell surface pH and O2demonstrated that individual cells exhibited an increased contribution of eCA to photosynthesis at higher irradiances. Our data demonstrate that changes in carbon demand strongly influence the requirement for eCA in diatoms. Cell size and photosynthetic rate will therefore be key determinants of the mode of dissolved inorganic carbon uptake.