American National Red Cross Blood Research Laboratory, Bethesda, Maryland 20014.
Plant Physiol. 1976 Sep;58(3):243-7. doi: 10.1104/pp.58.3.243.
The killing temperature for cortical cells from the flowering dogwood changes abruptly from -25 C to -15 C during dehardening. Cell sap concentration, minimum critical cell volume, and osmotically inactive cell volume show a progressive change during dehardening, but only cell sap concentration is correlated directly with the killing temperature, showing the same step change. There is a limit to the extent to which hardy dogwood cells can be osmotically reduced in volume. Beyond this limiting volume, the extracellular osmotically can be increased without further volume reduction. Ultimately the cell succumbs, presumably to an osmotic pressure gradient. Nonhardy cells do not exhibit this resistance to shrinkage. The ability to resist volume reduction is probably a crucial factor in the freezing resistance of dogwood cortical cells.
在去驯化过程中，山茱萸皮质细胞的致死温度从-25°C 急剧下降到-15°C。细胞液浓度、最小临界细胞体积和非渗透细胞体积在去驯化过程中逐渐发生变化，但只有细胞液浓度与致死温度直接相关，呈相同的阶跃变化。山茱萸韧皮细胞的渗透压降低幅度是有限的。超过这个极限体积，细胞外渗透压可以在不进一步降低体积的情况下增加。最终，细胞可能会因渗透压梯度而死亡。非韧皮细胞没有表现出这种对收缩的抵抗力。抵抗体积减小的能力可能是山茱萸皮质细胞抗冻性的关键因素。
