LUNAM, IMMM, UMR 6283 CNRS, Faculté des Sciences, 72085, Le MANS Cedex 09, France.
European Synchrotron Radiation Facility, 71, avenue des Martyrs, 38000, Grenoble, France.
Nat Commun. 2019 Feb 14;10(1):751. doi: 10.1038/s41467-019-08635-x.
Coccolithophores of the Noëlaerhabdaceae family are covered by imbricated coccoliths, each composed of multiple calcite crystals radially distributed around the periphery of a grid. The factors that determine coccolith size remain obscure. Here, we used synchrotron-based three-dimensional Coherent X-ray Diffraction Imaging to study coccoliths of 7 species of Gephyrocapsa, Emiliania and Reticulofenestra with a resolution close to 30 nm. Segmentation of 45 coccoliths revealed remarkable size, mass and segment number variations, even within single coccospheres. In particular, we observed that coccolith mass correlates with grid perimeter which scales linearly with crystal number. Our results indirectly support the idea that coccolith mass is determined in the coccolith vesicle by the size of the organic base plate scale (OBPS) around which R-unit nucleation occurs every 110-120 nm. The curvation of coccoliths allows inference of a positive correlation between cell nucleus, OBPS and coccolith sizes.
颗石藻科的颗石藻由叠瓦状的颗石组成，每个颗石由多个方解石晶体围绕网格的外围呈放射状分布而成。决定颗石大小的因素尚不清楚。在这里，我们使用基于同步加速器的三维相干 X 射线衍射成像技术，以接近 30nm 的分辨率研究了 7 种 Gephyrocapsa、Emiliania 和 Reticulofenestra 属的颗石。对 45 个颗石的分割显示出显著的大小、质量和段数变化，即使在单个球腔中也是如此。特别是，我们观察到颗石的质量与网格周长相关，网格周长与晶体数量呈线性比例。我们的结果间接支持了这样一种观点，即颗石的质量是由发生在每 110-120nm 的 R 单元成核周围的有机基板尺度（OBPS）的大小决定的。颗石的弯曲可以推断出细胞核、OBPS 和颗石大小之间存在正相关关系。
