Formation and mosaicity of coccolith segment calcite of the marine algae Emiliania huxleyi
Formation and mosaicity of coccolith segment calcite of the marine algae Emiliania huxleyi
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海藻艾米利亚赫胥黎石石段方解石的形成和镶嵌性
DOI：
10.1111/jpy.12604
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发表时间：
2017
影响因子：
2.9
通讯作者：
Schmahl
中科院分区：
文献类型：
--
作者：
Ziegler;Hoffmann;Watermeyer;Villinger;Schlüter;Reusch;Griesshaber;Walther;Schmahl
颗石藻属于最丰富的碳酸钙矿化生物。颗石藻生物矿化是一个复杂的和高度调节的过程，导致产品，其复杂的形态从无机产生的矿物等价物有很大的不同。此外，与细胞外形成的生物碳酸盐硬组织不同，颗石方解石既不是混合复合材料，也不是由分级显微结构区分的。这是值得注意的，因为优化结晶生物材料的机械强度和韧性的关键在于生物硬组织的复合性质和特定微观结构的利用。为了深入了解Emiliania huxleyicocoliths的生物矿化途径，我们研究了颗石方解石的晶内纳米结构特征，并结合与方解石形成相关的细胞超微结构观察，细胞内的颗石囊泡。通过TEM衍射和环形暗场成像，我们证明了方解石晶体中存在平面缺陷，例如平面镶嵌块边界。由于只有轻微的取向错误发生，我们将其归因于位错网络产生小角度边界。未观察到晶内包藏的生物聚合物。因此，在E. huxleyicalcite镶嵌性不是由封闭的生物聚合物引起的，因为它是在海洋无脊椎动物的细胞外形成的硬组织的情况下，而是由平面缺陷和位错引起的，这是典型的晶体形成的经典离子-离子生长机制。使用SEM和TEM的冷冻制备技术，我们发现球石囊泡的膜和核膜的外膜紧密靠近，它们之间具有良好控制的恒定间隙约4 nm。我们将这种明显的连接描述为尚未描述的细胞器间连接，即“核膜连接”。这个交界处的狭窄间隙可能有利于Ca 2+离子从核膜运输到颗石囊泡。根据我们的观察，我们提出，球石的形成利用细胞的核浆-内质网Ca 2 +-储存将Ca 2+离子从外部介质运输到球石囊泡，并且E. huxleyicalcite通过离子-离子生长而不是通过纳米颗粒吸积机制形成。
Coccolithophores belong to the most abundant calcium carbonate mineralizing organisms. Coccolithophore biomineralization is a complex and highly regulated process, resulting in a product that strongly differs in its intricate morphology from the abiogenically produced mineral equivalent. Moreover, unlike extracellularly formed biological carbonate hard tissues, coccolith calcite is neither a hybrid composite, nor is it distinguished by a hierarchical microstructure. This is remarkable as the key to optimizing crystalline biomaterials for mechanical strength and toughness lies in the composite nature of the biological hard tissue and the utilization of specific microstructures.To obtain insight into the pathway of biomineralization ofEmiliania huxleyicoccoliths, we examine intracrystalline nanostructural features of the coccolith calcite in combination with cell ultrastructural observations related to the formation of the calcite in the coccolith vesicle within the cell. With TEM diffraction and annular dark‐field imaging, we prove the presence of planar imperfections in the calcite crystals such as planar mosaic block boundaries. As only minor misorientations occur, we attribute them to dislocation networks creating small‐angle boundaries. Intracrystalline occluded biopolymers are not observed. Hence, inE. huxleyicalcite mosaicity is not caused by occluded biopolymers, as it is the case in extracellularly formed hard tissues of marine invertebrates, but by planar defects and dislocations which are typical for crystals formed by classical ion‐by‐ion growth mechanisms. Using cryo‐preparation techniques for SEM and TEM, we found that the membrane of the coccolith vesicle and the outer membrane of the nuclear envelope are in tight proximity, with a well‐controlled constant gap of ~4 nm between them. We describe this conspicuous connection as a not yet described interorganelle junction, the “nuclear envelope junction”. The narrow gap of this junction likely facilitates transport of Ca2+ions from the nuclear envelope to the coccolith vesicle. On the basis of our observations, we propose that formation of the coccolith utilizes the nuclear envelope–endoplasmic reticulum Ca2+‐store of the cell for the transport of Ca2+ions from the external medium to the coccolith vesicle and thatE. huxleyicalcite forms by ion‐by‐ion growth rather than by a nanoparticle accretion mechanism.
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影响因子：
1.6
作者：
Phillips, P. J.;Mills, M. J.;De Graef, M.
通讯作者：
De Graef, M.
海洋贝壳生物材料的层次结构：腕足动物对方解石的生物力学功能化
DOI：
10.1524/zkri.2012.1542
发表时间：
2012
期刊：
影响因子：
--
作者：
Schmahl WW;Griesshaber E;Kelm K;Goetz A;Jordan G;Ball A;Merkel C;Brand U
通讯作者：
Brand U
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影响因子：
2.9
作者：
A. Hallam;K. Perch
通讯作者：
K. Perch
影响因子：
2.4
作者：
Hoffmann, Ramona;Wochnik, Angela S.;Scheu, Christina
通讯作者：
Scheu, Christina
影响因子：
4.9
作者：
Hoffmann, R.;Kirchlechner, C.;Scheu, C.
通讯作者：
Scheu, C.