Hierarchical assembly of the eggshell and permeability barrier in C. elegans.
Hierarchical assembly of the eggshell and permeability barrier in C. elegans.
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DOI：
10.1083/jcb.201206008
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发表时间：
2012-08-20
期刊：
影响因子：
--
通讯作者：
Oegema K
中科院分区：
文献类型：
--
作者：
Olson SK;Greenan G;Desai A;Müller-Reichert T;Oegema K
秀丽隐杆线虫受精后三层蛋壳的组装和渗透屏障的发育在时间和机制上是不同的。在后生动物中，受精触发细胞外膜的组装，该细胞外膜构成胚胎与其环境之间的界面。在线虫中，这层外壳是蛋壳，它提供机械刚性，防止多精受精，并且小分子无法渗透。利用免疫电子显微镜，我们发现秀丽隐杆线虫蛋壳由外层卵黄层、中层几丁质层和含有软骨素蛋白聚糖的内层组成。几丁质层和蛋白多糖层之间的转换是通过几丁质合酶的内化与含有蛋白多糖的皮质颗粒的胞吐作用同时实现的。内层组装并没有像之前提出的那样使受精卵不可渗透。相反，相关光学和电子显微镜表明，渗透性屏障是一个独特的包膜，是在需要脂肪酸合成、糖修饰酶 PERM-1 和酰基链转移酶 DGTR-1 的单独步骤中形成的。这些发现描绘了蛋壳组装的层次结构，并定义了每个步骤的关键分子机制。
Assembly of the trilaminar eggshell and development of the permeability barrier after fertilization in C. elegans are distinct in their timing and mechanism. In metazoans, fertilization triggers the assembly of an extracellular coat that constitutes the interface between the embryo and its environment. In nematodes, this coat is the eggshell, which provides mechanical rigidity, prevents polyspermy, and is impermeable to small molecules. Using immunoelectron microscopy, we found that the Caenorhabditis elegans eggshell was composed of an outer vitelline layer, a middle chitin layer, and an inner layer containing chondroitin proteoglycans. The switch between the chitin and proteoglycan layers was achieved by internalization of chitin synthase coincident with exocytosis of proteoglycan-containing cortical granules. Inner layer assembly did not make the zygote impermeable as previously proposed. Instead, correlative light and electron microscopy demonstrated that the permeability barrier was a distinct envelope that formed in a separate step that required fatty acid synthesis, the sugar-modifying enzyme PERM-1, and the acyl chain transfer enzyme DGTR-1. These findings delineate the hierarchy of eggshell assembly and define key molecular mechanisms at each step.
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影响因子：
9.2
作者：
Maruyama, Rika;Velarde, Nathalie V.;Singson, Andrew
通讯作者：
Singson, Andrew
DOI：
10.1016/0014-4894(57)90037-1
发表时间：
1957-01-01
期刊：
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影响因子：
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作者：
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通讯作者：
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作者：
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影响因子：
4.6
作者：
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影响因子：
4.6
作者：
Lee, JY;Goldstein, B
通讯作者：
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