Digestive system membranes: freeze-fracture evidence for differentiation and flow in Paramecium.
Digestive system membranes: freeze-fracture evidence for differentiation and flow in Paramecium.
复制标题
消化系统膜：冻结裂纹证据，证明了甲虫的分化和流动。
DOI：
10.1083/jcb.89.1.9
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发表时间：
1981-04
影响因子：
7.8
通讯作者：
Staehelin, L A
中科院分区：
文献类型：
--
作者：
Allen, R D;Staehelin, L A
随机饲养的尾草履虫（草履虫）的消化液泡冷冻破裂膜在E面和p面破裂膜内颗粒（IMP）的数量和分布都有显著差异。通过脉冲喂养乳胶球细胞，我们已经证明这些差异与消化液泡的年龄有关，并且这些液泡的膜在消化周期中经历了特定的变化序列。年轻的消化液泡（DV-I，小于或等于6分钟），仍与细胞咽相连的新生液泡，以及液泡膜形成的盘状小泡，均具有高颗粒性的E面和低颗粒性的P面。早在进食后3分钟，就可以识别出第二类消化液泡（DV-II），其直径相当小，E面缺乏颗粒。这些发现表明，与DV-II液泡形成相关的DV-I膜材料的内吞去除包括伴随的和选择性的e面颗粒的去除，因为两种液泡上p面颗粒的密度基本上没有变化。从10分钟开始，第一个DV-III液泡出现。它们都比DV-II型液泡大，具有非常突出的E面颗粒，类似于与消化液泡接壤的许多溶酶体的E面颗粒。d - iii型液泡中p面颗粒也显著增加。这些膜的变化与液泡腔内发生的生理事件密切相关，并可能与之相关：食物的浓缩、猎物的捕杀和消化。通过计算从DV-I中去除形成DV-II的膜的量以及从DV-II到DV-III转变过程中膜表面积的增加表明，在消化开始之前，多达90%的初始吞噬体（DV-I）膜可以被去除。DV- ii的扩大一定是由于与邻近溶酶体的融合引起的，溶酶体也为DV- III膜提供了新的imp群体。在较老的DV-III型液泡上出现大量内吞结构，表明排便前从DV-III型液泡中回收了膜。
Freeze-fractured membranes of digestive vacuoles of randomly feeding Paramecium caudatum exhibit dramatic differences in intramembrane particle (IMP) number and distribution on both E- and P-fracture faces. By pulse-feeding latex spheres to cells we have demonstrated that these differences are related to the age of the digestive vacuoles, and that the membranes of such vacuoles undergo a specific sequence of changes during the digestive cycle. Young digestive vacuoles (DV-I; less than or equal to 6 min), nascent vacuoles still connected to the cytopharynx, and discoidal vesicles, from which vacuole membrane is derived, all have a highly particulate E face and a less particulate P face. As early as 3 min after feeding, a second category of digestive vacuoles (DV-II) can be recognized, which are both considerably smaller in diameter and lack particles on their E face. These findings suggest that the endocytic removal of DV-I membrane material associated with the formation of DV-II vacuoles involves a concomitant and selective removal of E-face particles, as essentially no changes are seen in the density of P-face particles on the two types of vacuoles. Beginning at 10 min the first DV-III vacuoles are encountered. These are both larger than the DV-II vacuoles and possess very prominent E-face particles, which resemble those on the E face of the numerous lysosomes bordering the digestive vacuoles. DV-III vacuoles also exhibit a substantial increase in P-face particles. These membrane changes closely parallel, and are probably correlated with, the physiological events occurring within the vacuole lumen: concentration of food, killing of prey, and digestion. Calculations of the amount of membrane removed from DV-I to form DV-II and of the increase in membrane surface area during the transition from DV-II to DV-III indicate that as much as 90% of the initial phagosome (DV-I) membrane can be removed before digestion begins. The enlargment of DV-II must be caused by fusion with adjacent lysosomes which also contribute the new populations of IMPs to the DV- III membrane. The appearance of numerous endocytic structures on older DV-III vacuoles suggests that membrane is retrieved from DV-III before defecation.