RUI: Flagellar Apparatus Structure and Phylogeny in the Colonial Volvocales

在殖民地的鞭毛器结构的Volvocales被证明是出乎意料的多样化。这种多样性尤其值得注意，因为有证据表明，这一群体的成员是从具有“典型的”绿藻鞭毛器官的衣藻类祖先进化而来的。鞭毛结构的差异可以假设为：a)从单细胞到群体习性的独立转变，或b)鞭毛器官结构的异常可塑性。由于研究的物种太少，我们还不能区分这些假设。本项目将通过在超微结构水平上对鞭毛器官的详细重建，以及利用识别稳定微管的单克隆抗体对根茎和鞭毛定位的免疫荧光调查，研究其他亲和力不确定性较小的类群。此外，鞭毛结构与鞭毛功能的相关性将继续研究，以更好地了解可能的选择压力对鞭毛结构的影响。这些研究将有助于理解“volvocene线”中藻类之间的系统发育关系。此外，它们将为鞭毛器官特征的进化稳定性提供信息；这一点尤其重要，因为鞭毛器官的结构正越来越多地用于对藻类和原生动物的系统研究。

The flagellar apparatus structure of the colonial Volvocales has turned out to be unexpectedly diverse. This diversity is especially noteworthy in view of the evidence that members of this group have evolved from a Chlamydomonas-like ancestor with a "typical" chlorophycean flagellar apparatus. The differences in flagellar structure can be hypothesized to result from either: a) independent transitions from the unicellular to the colonial habit, or b) unusual plasticity in flagellar apparatus structure. We cannot yet discriminate between these hypotheses because of the paucity of species examined. This project will study additional taxa of less uncertain affinities by detailed flagellar apparatus reconstruction at the ultrastructural level, and by surveys of rootlet and flagellar positioning with immunofluorescence using a monoclonal antibody that recognized stable microtubules. In addition, correlation of structure of the flagellar apparatus with flagellar functioning will be continued to understand better the effects of possible selection pressures on flagellar apparatus structure. These studies will contribute to understanding of the phylogenetic relationships among algae in the "volvocene line." In addition, they will give information on the evolutionary stability of the flagellar apparatus characters; this is especially important because the structure of the flagellar apparatus is being used increasingly in systematic studies of algae and protozoa at all levels.