Genetic analysis of membrane differentiation in Paramecium. Freeze-fracture study of the trichocyst cycle in wild-type and mutant strains.
Genetic analysis of membrane differentiation in Paramecium. Freeze-fracture study of the trichocyst cycle in wild-type and mutant strains.
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DOI：
10.1083/jcb.69.1.126
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发表时间：
1976-04
期刊：
影响因子：
--
通讯作者：
Satir B
中科院分区：
文献类型：
--
作者：
Beisson J;Lefort-Tran M;Pouphile M;Rossignol M;Satir B
使用一系列的草履虫tetraurelia的突变体，我们证明，第一次，细胞膜的内部结构的变化，所揭示的冷冻断裂，对应于特定的单基因突变。在草履虫的质膜上，圆形排列的颗粒标志着细胞内分泌细胞器--囊泡顶端的附着点。在野生型副膜中，其中附着的胞囊可以在各种刺激下通过胞吐作用排出，质膜阵列由颗粒（直径300 nm）的双重外环和环内的颗粒（直径76 nm）的中心玫瑰花结（融合玫瑰花结）组成。突变体nd 9的特征是具有释放胞囊的热敏能力，在允许温度（18摄氏度）下生长的细胞中显示出相同的组织，而在非允许温度（27摄氏度）下生长的细胞中，玫瑰花结缺失。在突变体tam 8中，其特征在于正常但未附着的胞囊，而在突变体t1中，完全没有胞囊，没有形成玫瑰花结，并且外环总是显示称为“括号”的修饰构型，这也在野生型和nd 9（18 ℃）细胞中发现。从野生型和突变体之间的比较中，我们得出结论：（a）括号的形成是质膜的初级分化，独立于胞囊的存在，而括号向圆形阵列的次级转化和玫瑰花结的形成是由胞囊和质膜之间的相互作用触发的;和（B）玫瑰花结的形成是胞吐作用的先决条件。
Using a series of mutants of Paramecium tetraurelia, we demonstrate, for the first time, changes in the internal structure of the cell membrane, as revealed by freeze-fracture, that correspond to specific single gene mutations. On the plasma membrane of Paramecium circular arrays of particles mark the sites of attachment of the tips of the intracellular secretory organelles-trichocysts. In wild-type paramecia, where attached trichocysts can be expelled by exocytosis under various stimuli, the plasma membrane array is composed of a double outer ring of particles (300 nm in diameter) and inside the ring a central rosette (fusion rosette) of particles (76 nm in diameter). Mutant nd9, characterized by a thermosensitive ability to discharge trichocysts, shows the same organization in cells grown at the permissive temperature (18 degrees C), while in cells grown at the nonpermissive temperature (27 degrees C) the rosette is missing. In mutant tam 8, characterized by normal but unattached trichocysts, and in mutant tl, completely devoid of trichocysts, no rosette is formed and the outer rings always show a modified configuration called "parentheses", also found in wild-type and in nd9 (18 degrees C) cells. From this comparison between wild type and mutants, we conclude: (a) that the formation of parentheses is a primary differentiation of the plasma membrane, independent of the presence of trichocysts, while the secondary transformation of parentheses into circular arrays and the formation of the rosette are triggered by interaction between trichocysts and plasma membranes; and (b) that the formation of the rosette is a prerequisite for trichocyst exocytosis.