Matrix and mineral in the sea urchin larval skeleton.
Matrix and mineral in the sea urchin larval skeleton.
复制标题
DOI：
10.1006/jsbi.1999.4105
复制
发表时间：
1999-06
影响因子：
3
通讯作者：
F. Wilt
中科院分区：
文献类型：
--
作者：
F. Wilt
海胆幼虫的内骨骼骨针由方解石、周围的细胞外基质和少量的闭塞基质蛋白组成。骨针是由胚胎囊胚腔中的初级间充质细胞（PMC）形成的，在那里它们采用刻板的位置，从而指定骨针将形成的位置。PMC也融合形成连接细胞体的细胞质索，并且在索内产生骨针。矿物相含有5%的Mg和Ca，约0.1%的质量是蛋白质。基质和矿物形成同心层，复合材料具有与纯方解石不同的物理性质。方解石衍射为单晶，由有序但不完全有序的微区组成。有证据表明，基质蛋白质吸附到域边界的特定晶面，这可能有助于调节晶体生长和纹理。不成熟的针状体含有大量沉淀的无定形CaCO3，PMC也有含有无定形CaCO3的囊泡。这表明了这样的假设，即针状体的细胞前体实际上是通过蛋白质稳定在细胞中的无定形CaCO3。骨针被PMC索包裹，但在拓扑学上位于细胞外部。PMC质膜紧紧贴在发育中的针状体上，可能除了伸长的尖端。的特点，本地化，和可能的功能的四个确定的基质蛋白进行了讨论。SM50、SM37和PM27都主要包裹矿物，但也有少量被包裹。SM30存在于细胞囊泡中，可能是骨针的主要包埋蛋白。
The endoskeletal spicules of sea urchin larvae are composed of calcite, a surrounding extracellular matrix, and small amounts of occluded matrix proteins. The spicules are formed by primary mesenchyme cells (PMCs) in the blastocoel of the embryo, where they adopt stereotypical locations, thereby specifying where spicules will form. PMCs also fuse to form cytoplasmic cords connecting the cell bodies, and it is within the cords that spicules arise. The mineral phase contains 5% Mg as well as Ca, and about 0.1% of the mass is protein. The matrix and mineral form concentric plies, and the composite has different physical properties than those of pure calcite. The calcite diffracts as a single crystal and is composed of well-ordered, but not perfectly ordered, microdomains. There is evidence for adsorption of matrix proteins to specific crystal faces at domain boundaries, which may help regulate crystal growth and texture. Immature spicules contain considerable precipitated amorphous CaCO3, and PMCs also have vesicles that contain amorphous CaCO3. This suggests the hypothesis that the cellular precursor to the spicules is actually amorphous CaCO3 stabilized in the cell by protein. The spicule s enveloped by the PMC cord, but is topologically exterior to the cell. The PMC plasmalemma is tightly applied to the developing spicules, except perhaps at the elongating tip. The characteristics, localization, and possible function of the four identified matrix proteins are discussed. SM50, SM37, and PM27 all primarily enclose the mineral, though small amounts are occluded. SM30 is found in cellular vesicles and is probably the principal occluded protein of the spicule.