Formation of multiplex lamellae by equilibrium slow freezing of cortical parenchyma cells of mulberry and its possible relationship to freezing tolerance
Formation of multiplex lamellae by equilibrium slow freezing of cortical parenchyma cells of mulberry and its possible relationship to freezing tolerance
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平衡缓冻桑葚皮层薄壁细胞多重片层的形成及其与耐冻性的可能关系
DOI：
10.1007/bf01281318
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发表时间：
1996
期刊：
影响因子：
2.9
通讯作者：
K. Takabe
中科院分区：
文献类型：
--
作者：
S. Fujikawa;K. Takabe
桑葚（Morus bombycisKoidz.）CV. Goroji）在冬季变得非常寒冷哈代，可以忍受零下30 °C的平衡冻结和随后的液氮浸泡。我们在这项超微结构研究中表明，在这些极冷的哈代皮层薄壁组织细胞的桑树在冬季收集，在-5 °C的冷冻开始导致形成的多重层（MPL），完全覆盖质膜下的区域。MPL是由预先存在的囊泡内质网（ER）通过网状ER网络融合而产生的。完整的MPL由平行排列的片状ER池组成。ER的这种结构重组在-5 °C冷冻后10分钟内完成，并在解冻后迅速逆转。在20 °C下，用2.7 μ l山梨醇溶液对皮质组织进行渗透脱水，可产生相同的ER结构重组。因此，冷冻后ER的结构重组实际上是由脱水产生的。在冬季样品中，MPL的形成与冻结的开始完全抑制膜的紧密贴壁后，深度冻结，已被报道为冻害的原因，通过生产的质膜超微结构的变化。在春季和秋季收集的皮层薄壁组织细胞中，通过冷冻或渗透脱水产生了类似但或多或少不完整的MPL，这些MPL部分抑制膜的紧密贴壁。夏季采集的桑葚细胞不产生MPL，低温冷冻时细胞膜紧密贴壁。我们推测，MPL的形成与冻结的启动可能发挥特定的作用，抑制膜的紧密贴壁由于特定性质的池膜，因此，可能是负责冬季细胞的高冷冻耐受性。
Cortical parenchyma cells of mulberry (Morus bombycisKoidz. cv. Goroji) become extremely cold hardy in winter and can tolerate equilibrium freezing below −30 °C and subsequent immersion into liquid nitrogen. We show in this ultrastructural study that, in these extremely cold hardy cortical parenchyma cells of mulberry collected in winter, initiation of freezing at −5 °C resulted in the formation of multiplex lamellae (MPL) that completely covered the area beneath the plasma membrane. The MPL were produced by fusion of pre-existing vesicular endoplasmic reticulum (ER), via a reticular ER network. The completed MPL were composed of a parallel array of sheet-like ER cisternae. This structural reorganization of the ER was completed within 10 min upon freezing at −5 °C and was quickly reversed upon thawing. The same structural reorganization of the ER was produced by osmotic dehydration of the cortical tissues with a 2.7 osmol sorbitol solution at 20 °C. Thus, the structural reorganization of the ER upon freezing was, in fact, produced by dehydration. In winter samples, the formation of MPL with the initiation of freezing completely inhibited close apposition of membranes upon deep freezing that has been reported to be a cause of freezing injury via the production of ultrastructural changes in the plasma membrane. Similar but more or less incomplete MPL were produced by freezing or osmotic dehydration in cortical parenchyma cells collected in spring and autumn, and these MPL partly inhibited close apposition of membranes. MPL were not produced in the cells of mulberry collected in summer and close apposition of membranes occurred upon deep freezing. We speculate that the formation of MPL with the initiation of freezing might play a specific role in inhibiting the close apposition of membranes due to the specific nature of the cisternal membranes and might, consequently, be responsible for the high freezing tolerance of winter cells.
影响因子：
7.4
作者：
M. Uemura;S. Yoshida
通讯作者：
M. Uemura;S. Yoshida