Investigation on diversity in the structure of cellulose-synthesizing terminal complexes among algal groups possessing chlorophyll a and c.

用冷冻断口电子显微镜观察了一些含有叶绿素a和c的藻类，如叶绿藻、叶黄藻和甲藻的纤维素微纤维(CMF)和纤维素合成末端复合体(TCS)的结构。硬球藻属Sphacelaria rigidula(褐藻亚科)和球藻属Botridium sp.(Xanthophyceae)合成带状CMF。然而，Sphacelaria有TCS，其亚基排列成单一的线性行，而Botridium中的TCS由几行斜行的亚基组成。首次发现黄藻科植物中除褐藻科植物外，还存在藻酸盐，表明黄藻科植物与褐藻科植物在系统发育上有较近的亲缘关系。这些结果表明，黄藻亚科和/或褐藻亚科的TCS是在这两个分支分化时获得的。电子衍射法表明，在甲藻中，膜板内含有CMF，形成由多个细小组分组成的束状物。在该藻类中发现了一种新的TC。

The structure of cellulose microfibrils (CMFs) and cellulose-synthesizing terminal complexes (TCs) in some species with chlorophyll a and c such as phaeophycean, xanthophycean and dinophycean algae was examined by freeze fracture electron microscopy. Both of Sphacelaria rigidula (Phaeophyceae) and Botridium sp. (Xanthophyceae) synthesized ribbon-like CMFs. However, Sphacelaria had TCs whose subunits are arranged in a single linear row, whereas TCs in Botridium consisted of several diagonal rows of subunits. It was found first that alginates are present in Xanthophyceae besides in Phaeophyceae, indicating a phylogenetically close relationship between Xanthophyceae and Phaeophyceae. These results suggest that the TCs in both or either of - Xanthophyceae and/or Phaeophyceae had been acquired at divergence of these two clades. It was evident in the dinophycean Scrippsiella hexapraecingra that the thecal plates contain CMFs which form bundles consisting of several fine components by electron diffraction methods. A new TC was found in this alga.