ジャーナル: Proc Natl Acad Sci U S A / 年: 2021 タイトル: Intracellular nanoscale architecture as a master regulator of calcium carbonate crystallization in marine microalgae. 著者: Yuval Kadan / Fergus Tollervey / Neta Varsano / Julia Mahamid / Assaf Gal / 要旨: Unicellular marine microalgae are responsible for one of the largest carbon sinks on Earth. This is in part due to intracellular formation of calcium carbonate scales termed coccoliths. ...Unicellular marine microalgae are responsible for one of the largest carbon sinks on Earth. This is in part due to intracellular formation of calcium carbonate scales termed coccoliths. Traditionally, the influence of changing environmental conditions on this process has been estimated using poorly constrained analogies to crystallization mechanisms in bulk solution, yielding ambiguous predictions. Here, we elucidated the intracellular nanoscale environment of coccolith formation in the model species using cryoelectron tomography. By visualizing cells at various stages of the crystallization process, we reconstructed a timeline of coccolith development. The three-dimensional data portray the native-state structural details of coccolith formation, uncovering the crystallization mechanism, and how it is spatially and temporally controlled. Most strikingly, the developing crystals are only tens of nanometers away from delimiting membranes, resulting in a highly confined volume for crystal growth. We calculate that the number of soluble ions that can be found in such a minute volume at any given time point is less than the number needed to allow the growth of a single atomic layer of the crystal and that the uptake of single protons can markedly affect nominal pH values. In such extreme confinement, the crystallization process is expected to depend primarily on the regulation of ion fluxes by the living cell, and nominal ion concentrations, such as pH, become the result, rather than a driver, of the crystallization process. These findings call for a new perspective on coccolith formation that does not rely exclusively on solution chemistry.
集束イオンビーム - 装置: OTHER / 集束イオンビーム - イオン: OTHER / 集束イオンビーム - 電圧: 30 kV / 集束イオンビーム - 電流: 0.05 nA / 集束イオンビーム - 時間: 1800 sec. / 集束イオンビーム - 温度: 90 K / 集束イオンビーム - Initial thickness: 5000 nm / 集束イオンビーム - 最終 厚さ: 200 nm 集束イオンビーム - 詳細: For details, see publication. The value given for _emd_sectioning_focused_ion_beam.instrument is FEI Aquilos. This is not in a list of allowed values {'DB235', ...集束イオンビーム - 詳細: For details, see publication. The value given for _emd_sectioning_focused_ion_beam.instrument is FEI Aquilos. This is not in a list of allowed values {'DB235', 'OTHER'} so OTHER is written into the XML file.
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
特殊光学系
位相板: VOLTA PHASE PLATE / エネルギーフィルター - 名称: GIF Quantum LS / エネルギーフィルター - スリット幅: 20 eV