ORGANIZATION OF CELLULOSE-SYNTHESIZING TERMINAL COMPLEXES

摘要

A marine dinoflagellate Scrippsiella hexapraecingula Horiguchi et Chihara produces a cell covering called a pellicle in the non-motile phase. We found cellulose microfibrils present in the pellicle and new cellulose-synthesizing terminal complexes (TCs) that synthesize those microfibrils. Treatment of pellicle with acetic-nitric reagent yielded 2 to 14-nm microfibrils, which were shown to be cellulosic by electron diffraction. Negatively stained preparations revealed these microfibrils to be composed of 2-nm fibrils. The TCs were linear particle arrays that are associated with the tip of microfibril impressions in the PF of the plasma membrane. Five to forty particles, each with a diameter of 5-15 nm, were arranged in two rows, but the positions of the particles were almost random. The length and the width of the TCs ranged 62-290 nm and 15-31 nm, respectively. Several TCs up to 7 were often associated laterally with each other and consolidated as a cluster. Such a TC cluster synthesized bands of microfibrils. Thus, the TCs of Scrippsiella hexapraecingula are quite distinctive from those found so far both in the particle arrangement of TCs and in the structure of microfibrils synthesized.