Development of measuring device of the hydraulic conductivity of cell membrane and the control of membrane water permeability under stress

了解水分动态和膜透性将为防治叶菜水分流失提供依据。因此，测定了菠菜细胞膜的质子核磁共振弛豫时间T_1和渗透透水性Lp。菠菜叶片水分T1由长、短组分组成。长T_1的增加表明细胞膜在贮藏过程中发生了变质。这与调节水跨膜运动的Lp的增加相对应。这一发现表明，随着Lp的增加，水的位置从液泡改变到细胞质，可以通过长T_1检测到。在20℃下贮藏，菠菜叶细胞的Lp直到24h才有明显变化。48h后Lp升高。在20℃贮藏前期，菠菜叶片在2℃条件下暴露24h， Lp的增加比20℃贮藏延迟。这意味着前24h暴露于2℃对抑制细胞膜退化有影响。另一方面，在2℃贮藏条件下，菠菜叶片的Lp在贮藏期间没有明显变化。这说明在2℃的贮藏条件下，细胞膜的劣化得到了抑制。样品的失重受到抑制的原因之一可能是低温使Lp维持在初始水平。本研究开发的测量装置几乎是自动化的。

Knowledge of dynamic state of water and membrane permeability will provide a measure against water loss of leafy vegetables. Therefore, the proton NMR relaxation time T_1 and the osmotic water permeability Lp of spinach cell membrane were measured. T1 of water in spinach leaf was composed of long and short components. The increase in long T_1 suggested the deterioration of cell membrane during storage. This corresponded to the increase in Lp that regulates the water movement across membrane. This finding implies that water changes its site from vacuole to cytoplasm as Lp increases and it can be detected through long T_1.As to the storage at 20℃, Lp of spinach leaf cell did not show any obvious change until 24h. But the Lp increased 48h later. For the Lp of spinach leaf exposed to 2℃ for 24h preliminary to the 20℃ storage, the increase in Lp delayed in comparison with the 20℃ storage. This means the exposure to 2℃ for the first 24h affected on suppression of cell membrance deterioration. On the other hand, the Lp of the spinach leaf stored at 2℃ did not show any obvious change over the storage period. This indicated that the deterioration of the cell membrance was suppressed at 2℃ storage. One of the reason why the weitht loss of samples was suppressed might be due to the maintenance of Lp at the initial level induced by exposure to low temperature. The measuring device developed in this study was almost automated.