Phylogenomic analysis of expressed sequence tags from the human parasite blastocystis hominis

Eukaryotes are complex nucleus-bearing cellular organisms (e.g. humans, plants, protozoa) that evolved several billion years ago on Earth. With the advent of full or partial genome sequencing (determining the genetic composition of an organism) and extensive computer based analysis of these data, more and more is being learned about how eukaryotes evolved and are related to one another. In this proposal we will use particular genomic characterization methods and sophisticated computational analyses of these data to learn about how a certain group of single-celled eukaryotes evolved. These are the anaerobic protozoa, many of which are parasites of humans. We know that all parasitic protozoa evolved from free-living ancestors, however our understanding of the how is rather limited. Blastocystis hominis is a common parasite of the human intestinal tract and is restricted to anaerobic environments only (obligate anaerobe). Currently we know little about this parasite. Like other eukaryotes, it has mitochondria that are normally involved in the oxidative metabolism of aerobic cells. However, as a strict anaerobe, it is unable to use oxygen to do this metabolism. Therefore, the function of this organelle in Blastocystis is a mystery. The data that we accumulate during our study will enable us to address this question as well as help us understand more about the biology of this organism. Ultimately our study should contribute to the wider picture of the origin of disease-causing organisms.