Phylogeny and Systematics of Coccoid Prasinophytes

9707262福利绿藻被称为绿藻纲，包括与所有绿色植物的祖先相似的有机体。一些Prasinophyceae是有鞭毛的，但另一些是非鞭毛(球状)单细胞。一些与陆地植物和其他绿藻不同的不寻常的色素和细胞特征出现在原生植物中。然而，一些研究表明，Prasinophyceae不是一个ONatural alO纲，而是可能由几个不同的进化线组成。在特定种类的原生植物藻类中共有的细胞结构和色素组成的变化可能表明存在共享单一共同祖先的谱系。在这项研究中，Marvin Fawley将专注于一组特殊的原生植物，即那些拥有类胡萝卜素的植物。有几条证据表明，这些生物来自单一的进化谱系。然而，目前的分类系统将拥有Prasinoxanin的生物体分为两个独立的目。这个项目将检验这样一种假设，即拥有藻类的普拉辛黄质形成了单一的谱系。将使用18S核糖体RNA基因序列分析以及色素和生化数据。大多数被检查的生物体将是球形藻，因为这些生物体中几乎没有得到很好的研究。然而，球形藻对于我们理解海洋浮游植物的多样性是至关重要的。更好地了解这些生物的系统发育将大大有助于正在进行的这种多样性的研究，以及我们对绿色植物进化的理解。

9707262 FAWLEY The class of green algae called the Prasinophyceae includes organisms similar to the ancestors of all green plants. Some Prasinophyceae are flagellates, but others are nonflagellate (coccoid) unicells. Some unusual pigments and cellular features that are distinct from land plants and other green algae occur in prasinophytes. However, several studies have revealed that the Prasinophyceae is not a OnaturalO class, but may instead be composed of several different evolutionary lines. Variations in cell structure and pigment composition that are shared among particular species of prasinophyte algae may indicate the presence of lineages that share a single common ancestor. In thsi research, Marvin Fawley will focus on a particular group of prasinophytes, those that possess the carotenoid prasinoxanthin. Several lines of evidence suggest that these organisms are from a single evolutionary lineage. However, current classification systems place the prasinoxanthin possessing organisms in two separate orders. This project will test the hypothesis that the prasinoxanthin possessing algae form a single lineage. 18S ribosomal RNA gene sequence analysis as well as pigment and biochemical data will be used. Most of the organisms examined will be coccoid prasinophytes, because few of these organisms have been well studied. However, the coccoid prasinophytes are critical to our understanding of the diversity of oceanic phytoplankton. Better knowledge of the phylogeny of these organisms will contribute greatly to ongoing research on this diversity, as well as to our understanding of green plant evolution.