THE EGGSHELL OF DROSOPHILA-MELANOGASTER .6. STRUCTURAL-ANALYSIS OF THE WAX LAYER IN LAID EGGS
THE EGGSHELL OF DROSOPHILA-MELANOGASTER .6. STRUCTURAL-ANALYSIS OF THE WAX LAYER IN LAID EGGS
复制标题
DOI：
10.1016/0040-8166(91)90014-k
复制
发表时间：
1991-01-01
期刊：
影响因子：
2.6
通讯作者：
GULIKKRZYWICKI, T
中科院分区：
文献类型：
--
作者：
PAPASSIDERI, I;MARGARITIS, LH;GULIKKRZYWICKI, T
利用冷冻破碎常规电镜和扫描电镜方法，鉴定了一层蜡层，封住了黑腹果蝇的卵母细胞。在成熟的蛋壳中，蜡在卵母细胞周围形成疏水层，位于卵黄膜（内部）和结晶的中间绒毛膜（外部）之间，并与卵黄膜（内部）非常紧密地接触。在交叉裂缝视图中，它的厚度小于50埃，而在纵向裂缝视图中，它显示出多层材料的光滑裂缝面，以疏水区或斑块（直径0.5-1 μ m）的形式出现，这些斑块在卵黄膜和最内层的绒毛膜层之间部分重叠并高度压缩。这一层是蜡的证据是：a)在传统的提取脂肪的电子显微镜方法中，它没有被保存下来；b)在冷冻压裂过程中，它指向裂缝面，并显示出光滑的裂缝面。对不同种类果蝇成熟蛋壳中蜡质结构特征的分析表明，蜡质层呈难以区分的疏水斑块，其大小和厚度与黑腹果蝇相同。这些数据提供了结构性证据，解释了所研究的虫卵在极端环境条件下产卵时对失水或吸水的生理抗性。此外，这些数据还展示了细胞外物质是如何组织起来执行这一功能的。
Utilizing freeze-fracturing conventional electron microscopy and scanning electron microscopy methods, a wax layer was identified, sealing the oocyte of Drosophila melanogaster. In mature egg-shells wax forms a hydrophobic layer surrounding the oocyte and lying between, and in very close contact with the vitelline membrane (interiorly) and the crystalline intermediate chorionic layer (exteriorly). In cross-fractured views it is less than 50 angstrom thick whereas in longitudinal fracturing it reveals smooth fracture faces of a multilayered material in the form of hydrophobic areas or plaques (0.5-1-mu-m in diameter), which are partially overlapping and highly compressed between the vitelline membrane and the innermost chorionic layer.The evidence for this layer being a wax are the facts that a) it is not preserved in conventional fat-extracting electron microscopy methods, b) it directs laterally the fracture planes during freeze-fracturing and reveals smooth fracture faces. Analysis of the structural features of wax in mature egg-shell in various species of Drosophilidae have shown that the wax layer exhibits indistinguishable (among the species) hydrophobic plaques, which have the same size and thickness with Drosophila melanogaster. These data provide structural evidence explaining the physiological resistance of the insect eggs studied, against water loss or water uptake, whenever they are laid on substrates with extreme environmental conditions. In addition, the data demonstrate how an extracellular substance can be organized to perform that function.