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.
