Cell wall structure and deposition in Glaucocystis
Cell wall structure and deposition in Glaucocystis
复制标题
青囊藻的细胞壁结构和沉积
作者：
J. Willison;R. Malcolm Brown;Jr
事件导致细胞壁形成的椭圆形单细胞藻蓝囊藻。壁沉积在三个阶段：（a）薄的非原纤层，（B）纤维素微纤维排列在螺旋交叉多片层的方式，和（c）基质物质。在细胞的两极，微纤维不终止，但通过周围三个等距排列的点，导致微纤维连续性之间的12个螺旋缠绕的壁层。这些研究结果表明，在母亲的细胞和冷冻断裂生长的细胞壁，和模型的壁结构。细胞伸展导致微纤维的散开和破裂。在冷冻断裂的质膜上，存在与微纤维末端相关的35 nm X 550 nm结构。这些被解释为代表微纤维合成中心（终端复合物）在运输上的膜。这些末端复合物位于一个或多个区域中。质膜被扁平囊包着，称为盾牌，在壁沉积完成后与质膜交联。在细胞壁沉积过程中，微管位于细胞盾之下，而极化丝位于细胞盾和质膜之间。这些研究结果的意义，了解纤维素沉积的过程中进行了讨论，并进行了比较，与卵囊藻。
Events leading to cell wall formation in the ellipsoidal unicellular alga Glaucocystis are described. The wall is deposited in three phases: (a) a thin nonfibrillar layer, (b) cellulosic microfibrils arranged in helically crossed polylamellate fashion, and (c) matrix substances. At poles of cells, microfibrils do not terminate but pass around three equilaterally arranged points, resulting in microfibril continuity between the twelve helically wound wall layers. These findings were demonstrated in walls of both mother cells and freeze-fractured growing cells, and models of the wall structure are presented. Cellular extension results in spreading apart, and in rupture, of microfibrils. On freeze-fractured plasma membranes, there were 35 nm X 550 nm structures associated with the ends of microfibrils. These are interpreted as representing microfibril-synthesizing centers (terminal complexes) in transit upon the membrane. These terminal complexes are localized in a zone, or zones. The plasma membrane is subtended by flattened sacs, termed shields, which become cross-linked to the plasma membrane after completion of wall deposition. During wall deposition, microtubules lie beneath the shields, and polarized filaments lie between shields and plasma membrane. The significance of these findings in relation to understanding the process of cellulose deposition is discussed, and comparisons are made with the alga Oocystis.