Baba M, Baba N, Ohsumi Y, Kanaya K, Osumi M
Department of Biology, Japan Women's University, Tokyo.
J Cell Sci. 1989 Oct;94 ( Pt 2):207-16. doi: 10.1242/jcs.94.2.207.
Ultrastructural analyses of cytoplasmic changes in Saccharomyces cerevisiae X2180-1A (MATa) that had been treated with alpha factor were performed by using the freeze-substitution fixation method. After alpha factor treatment, cells exhibited a pointed projection, which is a unique pattern of oriented cell surface growth. The relationship between projection formation and intracellular organelles was examined using serial thin sections and computer-aided three-dimensional reconstructions. Using these analyses membrane vesicles and other organelles were detected, and studies on their dynamic structural reorganization became feasible. Production of membrane vesicles (average 65 nm in diameter) was induced upon exposure of the cells to alpha factor before projection emergence. The total number of membrane vesicles increased at the early stage and decreased at the late stage of projection formation. Three-dimensional analysis indicated that the vesicles were at first dispersed throughout the cell, then accumulated at the site where the projection formed. Morphological changes and multiplication of the Golgi body were seen during the process of projection formation. Other intracellular organelles (nucleus, vacuole, rough endoplasmic reticulum and mitochondria) were also rearranged, showing a polar organization of the cytoplasm during projection formation.
采用冷冻置换固定法对经α因子处理的酿酒酵母X2180 - 1A（MATa）细胞质变化进行超微结构分析。经α因子处理后，细胞呈现出一个尖状突起，这是一种独特的定向细胞表面生长模式。利用连续超薄切片和计算机辅助三维重建技术研究了突起形成与细胞内细胞器之间的关系。通过这些分析检测到了膜泡和其他细胞器，并且对它们的动态结构重组研究变得可行。在突起出现之前，细胞暴露于α因子时诱导产生了膜泡（平均直径65纳米）。膜泡总数在突起形成的早期增加，在后期减少。三维分析表明，这些膜泡最初分散在整个细胞中，然后在突起形成的部位聚集。在突起形成过程中观察到高尔基体的形态变化和增殖。其他细胞内细胞器（细胞核、液泡、粗面内质网和线粒体）也发生了重排，在突起形成过程中显示出细胞质的极性组织。
