The Mechanics of Injury to Isolated Protoplasts following Osmotic Contraction and Expansion.
The Mechanics of Injury to Isolated Protoplasts following Osmotic Contraction and Expansion.
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渗透收缩和扩张后分离原生质体损伤的机制。
DOI：
10.1104/pp.83.4.1001
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发表时间：
1987
期刊：
影响因子：
7.4
通讯作者：
P. Steponkus
中科院分区：
文献类型：
--
作者：
M. Dowgert;J. Wolfe;P. Steponkus
以黑麦(Secale graale L.cv Puma)叶片为材料，采用微渗透操作方法研究渗透收缩对单个原生质体扩张势的影响。对于从未驯化的植物叶片中分离的原生质体(NA原生质体)，在足够高渗的溶液(渗透压1.53)中的渗透收缩使原生质体回到等渗条件(0.53渗透压)时容易在渗透膨胀过程中裂解。相反，对于从冷驯化植物叶片中分离出来的原生质体(ACC原生质体)，在2.6或4.0渗透压溶液中渗透收缩很容易逆转。渗透收缩后，NA原生质体的静息张力(γ(R))与在等渗溶液中测定的(即110+/-22微牛顿/米)相似。相反，ACC原生质体的伽马(R)从等渗溶液中的每米164+/-27微牛顿下降到高渗溶液中接近于零的值。在低渗溶液中膨胀后，NA和Acc原生质体的伽马(R)‘S在1.3%到1.6%的面积膨胀范围内是相似的。在NA原生质体渗透收缩和再膨胀后，在伽马(R)与表面积之间的关系中观察到滞后-在给定的表面积处伽马(R)的值更高。相反，在ACC原生质体的这种关系中没有观察到滞后。从高渗溶液(1.53渗透压)对NA原生质体渗透膨胀过程中质膜张力(γ)的直接测量表明，在表面积小幅增加后，伽马迅速增加，裂解发生在1.2-8毫牛顿/米的范围内。在从高渗溶液(2.6渗透压)中渗透扩张ACC原生质体的过程中，在超过等渗表面积之前，伽马含量几乎没有增加。讨论了NA和ACC原生质体在渗透收缩过程中质膜行为的差异(即内吞泡化和胞吐挤出)，并从机理上解释了NA和ACC原生质体对来自高渗溶液的渗透膨胀的不同敏感性。
Micro-osmotic manipulation was used to determine the influence of osmotic contraction on the expansion potential of individual protoplasts isolated from rye (Secale cereale L. cv Puma) leaves. For protoplasts isolated from leaves of nonacclimated plants (NA protoplasts), osmotic contraction in sufficiently hypertonic solutions (>1.53 osmolal) predisposed the protoplasts to lysis during osmotic expansion when they were returned to isotonic conditions (0.53 osmolal). In contrast, for protoplasts isolated from leaves of cold acclimated plants (ACC protoplasts), osmotic contraction in either 2.6 or 4.0 osmolal solutions was readily reversible. Following osmotic contraction, the resting tension (gamma(r)) of NA protoplasts was similar to that determined for protoplasts in isotonic solutions (i.e. 110 +/- 22 micronewtons per meter). In contrast, gamma(r) of ACC protoplasts decreased from 164 +/- 27 micronewtons per meter in isotonic solutions to values close to zero in hypertonic solutions. Following expansion in hypotonic solutions, gamma(r)'s of both NA and ACC protoplasts were similar for area expansions over the range of 1.3 to 1.6. Following osmotic contraction and reexpansion of NA protoplasts, hysteresis was observed in the relationship between gamma(r) and surface area-with higher values of gamma(r) at a given surface area. In contrast, no hysteresis was observed in this relationship for ACC protoplasts. Direct measurements of plasma membrane tension (gamma) during osmotic expansion of NA protoplasts from hypertonic solutions (1.53 osmolal) revealed that gamma increased rapidly after small increments in surface area, and lysis occurred over a range of 1.2 to 8 millinewtons per meter. During osmotic expansion of ACC protoplasts from hypertonic solutions (2.6 osmolal), there was little increase in gamma until after the isotonic surface area was exceeded. These results are discussed in relation to the differences in the behavior of the plasma membrane of NA and ACC protoplasts during osmotic contraction (i.e. endocytotic vesiculation versus exocytotic extrusion) and provide a mechanistic interpretation to account for the differential sensitivity of NA and ACC protoplasts to osmotic expansion from hypertonic solutions.