Membrane structure of Golgi apparatus, chloroplasts and mitochondria observed by freeze-substitution

用冷冻替代法研究了尖生栅藻高尔基体、叶绿体和线粒体的膜结构。这些膜中的大多数明显地具有三层结构。解释说，这三层是通过分解膜上剩余的电子致密膜蛋白中的脂类成分而可视化的。远端高尔基体池的上膜和下膜在池中央紧密接触。在类囊体中也观察到两种膜的相似接触。转移小泡、分泌小泡和脑池边缘的电子密度很高。这些发现与传统的化学固定有很大不同，表明冷冻取代法在保存结构不变形和防止组分溶解方面优于化学固定法。

The membrane structure of Golgi apparatus, chloroplasts and mitochondria in Scenedesmus acuminatus was studied by the freeze-substitution method. Most of these membranes clearly exhibited three-layered structures. It was interpreted that the three layers were visualized by resolving the lipid component from membranes remaining electron dense membrane proteins. The upper and lower membranes of the distal Golgi cisternae were in close contact with each other at the cisternal centre. Similar contact of two membranes was also observed in thylakoids. The electron density of transfer vesicles, secretory vesicles, and cisternal margins was very high. These findings differ considerably from those obtained by conventional chemical fixation, and suggest that freeze-substitution is superior to chemical fixation for preserving structures without distortion and preventing dissolution of constituent substances.