Santarius K A, Giersch C
Biophys J. 1984 Aug;46(2):129-39. doi: 10.1016/S0006-3495(84)84006-0.
During freezing of isolated spinach thylakoids in sugar/salt solutions, the two solutes affected membrane survival in opposite ways: membrane damage due to increased electrolyte concentration can be prevented by sugar. Calculation of the final concentrations of NaCl or glucose reached in the residual unfrozen portion of the system revealed that the effects of the solutes on membrane activity can be explained in part by colligative action. In addition, the fraction of the residual liquid in the frozen system contributes to membrane injury. During severe freezing in the presence of very low initial solute concentrations, membrane damage drastically increased with a decrease in the volume of the unfrozen solution. Freezing injury under these conditions is likely to be due to mechanical damage by the ice crystals that occupy a very high fraction of the frozen system. At higher starting concentrations of sugar plus salt, membrane damage increased with an increase in the amount of the residual unfrozen liquid. Thylakoid inactivation at these higher initial solute concentrations can be largely attributed to dilution of the membrane fraction, as freezing damage at a given sugar/salt ratio decreased with increasing the thylakoid concentration in the sample. Moreover, membrane survival in the absence of freezing decreased with lowering the temperature, indicating that the temperature affected membrane damage not only via alterations related to the ice formation. From the data it was evident that damage of thylakoid membranes was determined by various individual factors, such as the amount of ice formed, the final concentrations of solutes and membranes in the residual unfrozen solution, the final volume of this fraction, the temperature and the freezing time. The relative contribution of these factors depended on the experimental conditions, mainly the sugar/salt ratio, the initial solute concentrations, and the freezing temperature.
在将分离的菠菜类囊体置于糖/盐溶液中冷冻的过程中，这两种溶质对膜存活的影响方式相反：糖可以防止因电解质浓度增加而导致的膜损伤。计算系统中残留未冷冻部分所达到的NaCl或葡萄糖的最终浓度表明，溶质对膜活性的影响部分可以用依数性作用来解释。此外，冷冻系统中残留液体的比例也会导致膜损伤。在初始溶质浓度非常低的情况下进行剧烈冷冻时，膜损伤会随着未冷冻溶液体积的减少而急剧增加。在这些条件下的冷冻损伤可能是由于冰晶的机械损伤，冰晶在冷冻系统中所占比例非常高。在糖加盐的起始浓度较高时，膜损伤随着残留未冷冻液体量的增加而增加。在这些较高的初始溶质浓度下，类囊体失活很大程度上可归因于膜部分的稀释，因为在给定的糖/盐比例下，冷冻损伤会随着样品中类囊体浓度的增加而降低。此外，在不冷冻的情况下，膜存活会随着温度降低而下降，这表明温度不仅通过与冰形成相关的变化来影响膜损伤。从数据中可以明显看出，类囊体膜的损伤是由多种个体因素决定的，例如形成的冰量、残留未冷冻溶液中溶质和膜的最终浓度、该部分的最终体积、温度和冷冻时间。这些因素的相对贡献取决于实验条件，主要是糖/盐比例（初始溶质浓度）和冷冻温度。
