The assembly of cellulose microfibrils in Valonia macrophysa Kütz
The assembly of cellulose microfibrils in Valonia macrophysa Kütz
复制标题
Valonia macrophysa Kütz 中纤维素微纤维的组装
作者：
T. Itoh;Richard M Brown
研究了大囊瓦藻（Valonia macrophysa）原生质体在人工诱导下纤维素微纤丝的组装。原生质体诱导72小时内形成的初生壁微纤丝是随机取向的。原生质体诱导后96 h内产生的次生壁片层具有三个以上的高度有序的微纤丝方向。最里面的，最近沉积的微原纤维是不平行的皮质微管，从而表明一个更间接的作用微管的微原纤维的方向。在质膜附近观察到周期性为5.0-5.5 nm的细丝状结构和肌动蛋白的尺寸。纤维素末端合成复合物（TC）由三排组成，每排30-40个颗粒，不仅在E断裂（EF）上观察到，而且在P断裂（PF）面的质膜。TC似乎跨越双分子小叶的两面。TC的平均长度为350 nm，并且在初级壁合成期间每单位面积的TC的数量为1个/μm2。既没有成对的TC，也没有观察到卵囊藻的颗粒带特征。在TC结构和分布的变化过程中的转换，从初级到次级壁的形成已被描述。纤维素微纤丝组装在Valonia讨论在其他真核系统的过程中。
The assembly of cellulose microfibrils was investigated in artificially induced protoplasts of the alga, Valonia macrophysa (Siphonocladales). Primary-wall microfibrills, formed within 72 h of protoplast induction, are randomly oriented. Secondary-wall lamellae, which are produced within 96 h after protoplast induction, have more than three orientations of highly ordered microfibrils. The innermost, recently deposited micofibrils are not parallel with the cortical microtubules, thus indicating a more indirect role of microtubules in the orientation of microfibrils. Fine filamentous structures with a periodicity of 5.0–5.5 nm and the dimensions of actin were observed adjacent to the plasma membrane. Linear cellulose-terminal synthesizing complexes (TCs) consisting of three rows, each with 30–40 particles, were observed not only on the E fracture (EF) but also on P fracture (PF) faces of the plasma membrane. The TC appears to span both faces of the bimolecular leaflet. The average length of the TC is 350 nm, and the number of TCs per unit area during primary-wall synthesis is 1 per μm2. Neither paired TCs nor granule bands characteristic of Oocystis were observed. Changes in TC structure and distribution during the conversion from primary- to secondary-wall formation have been described. Cellulose microfibril assembly in Valonia is discussed in relation to the process among other eukaryotic systems.