Effects of cold-induced dysfunction of vacuoles upon homeostasis in intracellular ionic environment.

寒冷诱导的液泡功能障碍对细胞内离子环境稳态的影响。

基本信息

批准号：
03454005
负责人：
YOSHIDA Shizuo
金额：
$ 4.16万
依托单位：
The Institute of Low Temperature Science, Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

Chilling sensitivity of mung bean cultured cells varied markedly depending on the growth phases. At the initial stages after subculture, cells were relatively insensitive to chilling, but chilling sensitivity increased abruptly thereafter and reached a maximum at the early stage of exponential growth. Upon further culturing, cell become chilling-tolerant, becoming most tolerant at the stage of stationary growth. We observed that cold sensitivity of the tonoplast H^+-ATPase in vivo changed markedly as a function of growth cycle. the enzyme was very sensitive to cold at the early stage of exponential growth and less sensitive at the late stage of exponential growth. Therefore, there exists an intimate correlation between sensitivities of cells to cold and the coldinsability of the H^+-ATPase. Biochemical studies on the cold-induced inactivation of the tonoplast H^+-ATPase indicated that a selective release of the peripheral subunits as a whole from the membrane sectors (16 kDa subunit).Changes in cytoplasmic pH in mung bean cultured cells were observed utilizing a cryomicroscope and a fluorescence ratio imaging system with special reference to the variations in chilling sensitivity during cell growth. In the extremely chilling-sensitive cells at the early stage of exponential growth, cytoplasmic pH was reduced abruptly upon cold incubation at 0ﾟC. However, in chilling- tolerant cells at the late stage of exponential growth, no change in the cytoplasmic pH was detected even after protracted chilling for up to 72 h.From the results, it is suggested that vacuolar proton translocating systems has an important role for maintaining of cell homeostasis, especially under such a cold environment.

绿豆培养细胞的低温敏感性随生长阶段的不同而显着变化，在继代培养后的初始阶段，细胞对低温不敏感，但此后低温敏感性急剧增加，并在指数生长期达到最大值。，细胞变得耐冷，在静止生长阶段最耐受。我们观察到体内液泡膜H^+-ATP酶的冷敏感性随着生长周期的变化而显着变化。指数生长早期对寒冷较敏感，而在指数生长后期则较不敏感，因此，细胞对寒冷的敏感性与H^+-ATP酶的冷不耐受性之间存在密切的相关性。诱导液泡膜 H^+-ATP 酶失活表明外周亚基作为一个整体从膜部分（16 kDa 亚基）选择性释放。培养绿豆中细胞质 pH 值的变化利用冷冻显微镜和荧光比率成像系统观察细胞，特别参考细胞生长过程中冷冻敏感性的变化，在指数生长早期对冷冻极度敏感的细胞中，在0℃冷孵育时细胞质pH值突然降低。然而，在指数生长后期的耐冷细胞中，即使长时间冷藏72小时也没有检测到细胞质pH值的变化。从结果来看，液泡质子易位系统对于维持细胞稳态具有重要作用，特别是在如此寒冷的环境下。