Triccas Alexander, Chevrier Daniel M, Verezhak Mariana, Ihli Johannes, Guizar-Sicairos Manuel, Holler Mirko, Scheffel André, Ozaki Noriaki, Chamard Virginie, Wood Rachel, Grünewald Tilman A, Nudelman Fabio
School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, UK.
Université Aix-Marseille, CNRS, CEA, BIAM, UMR7265 Institut de Biosciences and Biotechnologies d'Aix-Marseille, F-13115 Saint-Paul-lez-Durance, France.
Sci Adv. 2025 Jul 25;11(30):eadv0618. doi: 10.1126/sciadv.adv0618. Epub 2025 Jul 23.
Coccolithophores are abundant marine phytoplankton that produce biomineralized calcite scales, called coccoliths, which sequester substantial amounts of carbon and play a substantial role in biogeochemical cycles. However, mechanisms underlying the storage and transport of ions essential for calcification remain unresolved. We used ptychographic x-ray computed tomography under cryogenic conditions to visualize intracellular calcium-rich structures involved in the storage of calcium ions in the coccolithophore species . During calcification, we observed a range of structures, from small electron-dense bodies within larger compartments to denser and distributed globular compartments, before returning to small bodies once scale formation is complete. Nanobeam-scanning x-ray fluorescence measurements further revealed that these electron-dense bodies are rich in phosphorus and calcium (molar ratio of ~4:1). The dynamic nature of structures suggests that these bodies are part of the required cellular calcium ion transport pathways, a fundamental process critical for understanding the response of coccolithophores to climate change.
颗石藻是丰富的海洋浮游植物，它们产生生物矿化的方解石鳞片，称为颗石，这些颗石封存了大量的碳，并在生物地球化学循环中发挥着重要作用。然而，钙化所必需的离子的储存和运输机制仍未得到解决。我们在低温条件下使用叠层成像X射线计算机断层扫描来可视化参与颗石藻物种中钙离子储存的细胞内富含钙的结构。在钙化过程中，我们观察到一系列结构，从较大隔室内的小电子致密体到更致密且分布的球状隔室，一旦鳞片形成完成，又恢复为小体。纳米束扫描X射线荧光测量进一步揭示，这些电子致密体富含磷和钙（摩尔比约为4:1）。结构的动态性质表明，这些小体是所需的细胞钙离子运输途径的一部分，这是一个对于理解颗石藻对气候变化的响应至关重要的基本过程。
