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首页> 外文期刊>Protoplasma: An International Journal of Cell Biology >FREEZE-FRACTURE STUDIES IN THE BROWN ALGA ASTERONEMA RHODOCHORTONOIDES
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FREEZE-FRACTURE STUDIES IN THE BROWN ALGA ASTERONEMA RHODOCHORTONOIDES

机译：褐藻紫杉七丁香的冷冻断裂研究

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摘要

The gross structure of the cell wall and the organization of the plasmalemma of the filamentous brown alga Asteronema rhodochortonoides were examined in replicas of freeze-fractured cells. The protoplasmic fracture face (PF) of the plasmalemma, apart from the single particles, exhibits two particular particle complexes, i.e., single linear arrays of closely packed particles, and well defined particle pentads. The former display a consistent relationship with the ends of microfibril imprints and therefore are considered as terminal complexes (TCs). They seem to be composed of subunits, each one consisting of two particles. The average diameter of the particles is 7 nm. The number of the subunits forming the TCs varies between 2 and 40. Short TCs, consisting of 3-5 subunits were also found on the PF of dictyosome vesicles, a fact suggesting the involvement of the Golgi apparatus in exocytosis of preformed TC portions. The occurrence, distribution and size of the TCs appear to be related to the developmental stage of the cell. A large number of TCs occur in actively growing cells, while a few or no TCs are found in differentiated cells. The pentads are rectangular structures consisting of five particles, four in the corners and one in the centre. Their dimensions are very constant, but their occurrence and distribution varies. They occur in young developing cells where TCs are few or absent, but were also observed in areas showing many TCs. In differentiated cells no pentads were found. Pentad-like structures were rarely observed on the PF of dictyosome vesicles or cisternae. The observations support the hypothesis that pentads are involved in the synthesis of matrix polysaccharides, which are the major components of brown algal cell wall and their synthesis begins before that of cellulose. [References: 40]
机译：在冷冻破裂的细胞的复制物中检查了细胞壁的总体结构和丝状褐藻Asteronema rhodochortonoides的质膜组织。除单颗粒外，质膜的原质破裂面（PF）还表现出两种特殊的颗粒复合物，即紧密堆积的颗粒的单个线性阵列和定义明确的颗粒五单元组。前者与微纤维印迹的末端显示出一致的关系，因此被认为是末端复合物（TCs）。它们似乎由亚基组成，每个亚基由两个颗粒组成。颗粒的平均直径为7nm。形成TC的亚基数量在2到40之间变化。在单核小泡的PF上还发现了由3-5个亚基组成的短TC，这一事实表明高尔基体参与了预先形成的TC部分的胞吐作用。 TC的出现，分布和大小似乎与细胞的发育阶段有关。在活跃生长的细胞中会发生大量TC，而在分化的细胞中则只会发现很少或没有TC。五单元组是由五个粒子组成的矩形结构，四个在角落，一个在中心。它们的尺寸非常恒定，但是它们的出现和分布却有所不同。它们发生在很少或不存在TC的年轻发育细胞中，但在显示许多TC的区域也观察到。在分化的细胞中未发现五单元组。在单核小泡或水箱的PF上很少观察到五角状的结构。这些观察结果支持五单元组参与基质多糖的合成这一假设，基质多糖是棕色藻细胞壁的主要成分，其合成要早于纤维素。 [参考：40]

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