RUI: Flagellar Apparatus Structure and Phylogeny in the Colonial Volvocales

蜂群的鞭毛器结构出人意料地多样化。这一多样性尤其值得注意，因为有证据表明，这个类群的成员是从一个类似衣藻的祖先进化而来的，具有“典型的”叶绿素鞭毛器。鞭毛结构的差异可能是由于：a)从单细胞到群体习性的独立转变，或者b)鞭毛器结构的异常可塑性。我们还不能区分这些假设，因为所研究的物种很少。这个项目将通过在超微结构水平上详细的鞭毛结构重建，以及通过使用识别稳定微管的单抗免疫荧光来调查小根和鞭毛的位置，来研究更多不太确定亲和力的分类群。此外，鞭毛器的结构与鞭毛功能的相关性将继续下去，以更好地了解可能的选择压力对鞭毛器结构的影响。这些研究将有助于理解“volvocene line”中藻类之间的系统发育关系。此外，它们还将提供有关鞭毛器特征进化稳定性的信息；这一点尤其重要，因为鞭毛器的结构正越来越多地被用于各级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.