“Second extrinsic organizational mechanism” for orienting cellulose: modeling a role for the plasmalemmal reticulum
“Second extrinsic organizational mechanism” for orienting cellulose: modeling a role for the plasmalemmal reticulum
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用于定向纤维素的“第二外在组织机制”：模拟质膜网的作用
作者：
B. Pickard
纤维素合成复合物对纤维素纤维的定向沉积通常发生在微管束穿过质膜的过程中，并受微管束的引导。然而，即使在应用安磺灵解聚微管后，也可以显示复合物的对齐运动。此外，有人声称，当（1）微管用安磺灵解聚，（2）暂时施加微管定向刺激，和（3）冲洗掉安磺灵时，新形成的纤维素纤维相对于刺激定向。考虑到这一点，本文件收集证据，从不同的文献表明，质膜网，一个主要的和结构上重要的形式的细胞骨架连接皮层细胞质与壁，是一个候选人，既独立又合作参与定向微管和路由运动的纤维素合成复合物。质膜网的粘附位点与动物细胞粘附位点在形态学和分子学上具有相似性，已知其发挥多种整合作用，这对上述功能至关重要。网织膜本身可能是所谓的脂筏的形态学表现，以前只知道生化特性的基础上。根据工作模型，桁架互连的粘附网站形状的网状成明显的情况依赖的几何形状。例如，在非生长或非极化的细胞中，纤维素沉积在刷状的网格中，它们形成非极性或弱极性的网;然而，在具有倾斜或其他极化微管和新形成的纤维素纤维的伸长细胞中，有暗示性证据表明，网的形成是由以相应的偏向取向组织的桁架主导的。考虑到这种几何形状和作用的网建议几个测试，可以肯定，否定，或取代这一建议的关键方面，以扩大外周细胞骨架的理论。
Summary.Oriented deposition of cellulose fibers by cellulose-synthesizing complexes typically occurs across the plasma membrane from microtubule bundles and is guided by them. However, aligned movement of the complexes can be shown even after applied oryzalin has depolymerized microtubules. Further, there is a claim that when (1) microtubules are depolymerized with oryzalin, (2) a microtubule-orienting stimulus is applied temporarily, and (3) oryzalin is washed out, the newly forming cellulose fibers are oriented with respect to the stimulus. With this in mind, the present paper gathers evidence from a diverse literature to suggest that the plasmalemmal reticulum, a major and structurally important form of cytoskeleton which connects cortical cytoplasm with wall, is a candidate to both independently and cooperatively participate in orienting microtubules and routing movements of cellulose-synthesizing complexes. Critical to this proposed function, the adhesion sites of the plasmalemmal reticulum have some morphological and molecular similarities to animal cell adhesion sites, known to play numerous integrative roles. The reticulum itself may be the morphological manifestation of the so-called lipid raft, previously known only on the basis of biochemical properties. According to the working model, the trusses interconnecting the adhesion sites shape the reticulum into apparently situation-dependent geometries. For example, in nongrowing or nonpolarized cells in which cellulose is deposited in brushy meshes, they form a nonpolar or weakly polar net; however, in elongating cells with oblique or otherwise polarized microtubules and newly forming cellulose fibers, there is suggestive evidence that net formation is dominated by trusses organized with correspondingly biased orientation. Consideration of such geometries and roles of the reticulum suggests several tests that could affirm, deny, or replace key aspects of this proposal to expand the theory of the peripheral cytoskeleton.