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Abstract：
Living organisms control the formation of mineral skeletons and other structures through biomineralization. Major phylogenetic groups usually consistently follow a single biomineralization pathway. Foraminifera, which are very efficient marine calcifiers, making a substantial contribution to global carbonate production and global carbon sequestration, are regarded as an exception. This phylum has been commonly thought to follow two contrasting models of either in situ \'mineralization of extracellular matrix\' attributed to hyaline rotaliid shells, or \'mineralization within intracellular vesicles\' attributed to porcelaneous miliolid shells. Our previous results on rotaliids along with those on miliolids in this paper question such a wide divergence of biomineralization pathways within the same phylum of Foraminifera. We have found under a high-resolution scanning electron microscopy (SEM) that precipitation of high-Mg calcitic mesocrystals in porcelaneous shells takes place in situ and form a dense, chaotic meshwork of needle-like crystallites. We have not observed calcified needles that already precipitated in the transported vesicles, what challenges the previous model of miliolid mineralization. Hence, Foraminifera probably utilize less divergent calcification pathways, following the recently discovered biomineralization principles. Mesocrystalline chamber walls in both models are therefore most likely created by intravesicular accumulation of pre-formed liquid amorphous mineral phase deposited and crystallized within the extracellular organic matrix enclosed in a biologically controlled privileged space by active pseudopodial structures. Both calcification pathways evolved independently in the Paleozoic and are well conserved in two clades that represent different chamber formation modes.
摘要：
活生物体通过生物矿化控制矿物骨架和其他结构的形成。主要的系统发育群体通常始终遵循单个生物矿化途径。有孔虫,它们是非常有效的海洋钙化剂，为全球碳酸盐生产和全球碳固存做出重大贡献，被视为例外。通常认为该门遵循两种相反的模型，即归因于透明罗氏壳的细胞外基质的原位矿化，或“细胞内囊泡内的矿化”归因于孔皮miliolid壳。在本文中，我们先前关于Rotalids和miliolids的结果质疑同一有孔虫门内生物矿化途径的广泛差异。我们在高分辨率扫描电子显微镜（SEM）下发现，高Mg钙质介晶在多孔壳中的沉淀原位发生并形成致密的，针状微晶的混沌网格。我们还没有观察到已经在运输的囊泡中沉淀的钙化针，是什么挑战了以前的米利德矿化模型。因此，有孔虫可能利用较少分歧的钙化途径，遵循最近发现的生物矿化原理。因此，两种模型中的介晶室壁很可能是由预先形成的液态无定形矿物相的囊内积聚而形成的，这些矿物相沉积并结晶在细胞外有机基质中，这些基质通过活性伪足结构封闭在生物学控制的特权空间中。两种钙化途径都在古生代独立进化，并且在代表不同腔室形成模式的两个进化枝中都很保守。
