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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.

绿豆培养细胞的冷冻敏感性根据生长阶段而显着变化。传代培养初期，细胞对低温相对不敏感，但此后低温敏感性急剧增加，并在指数生长期达到最大值。经过进一步培养，细胞变得耐冷，在稳定生长阶段变得最耐受。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发生显着变化。该酶在指数生长初期对寒冷非常敏感，在指数生长后期较不敏感。因此，细胞对冷的敏感性与H^+-ATP酶的耐冷性之间存在着密切的相关性。对寒冷诱导的液泡膜 H^+-ATPase 失活的生化研究表明，外围亚基作为一个整体从膜部分（16 kDa 亚基）选择性释放。利用冷冻显微镜和荧光比成像系统观察绿豆培养细胞中细胞质 pH 的变化，特别是冷冻的变化细胞生长过程中的敏感性。在指数生长早期对低温极度敏感的细胞中，0°C 冷培养后细胞质 pH 值突然降低。然而，在指数生长后期的耐冷细胞中，即使延长冷藏72小时也没有检测到细胞质pH值的变化。结果表明，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。