Novel ultrastructural systems in eukaryotic cells: predators, parasites and plastids

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For over 3 billion years, microbes have dominated the planet in terms of pure abundance and diversity, yet the fundamental and innovative properties of microbes are the least understood of all extant organisms. Micro-eukaryotes are morphologically and genetically complex, having nuclei, endomembrane systems, symbiotically acquired organelles and elaborate cytoskeletons supporting a vast array of specialized cell extensions and behaviors. Despite being composed of only a single cell, each micro-eukaryote is a universe in itself, and recent advances in our understanding of these organisms have dramatically altered long-held views about the diversity of cells. Accordingly, the proposed research program is designed to explore this foreign world in order to help unravel the total composition, interrelationships and history of life on earth. Individual projects will span an extremely broad sampling of eukaryotic diversity in order to resolve large-scale patterns of cell character evolution. The research program will continue to study, in parallel, four main groups of micro-eukaryotes that encompass what are arguably the three most dissimilar modes of eukaryotic life on the planet: predation, photoautotrophy, and parasitism. The independent but corresponding patterns of morphological change in marine predatory flagellates, such as euglenids, dinoflagellates and cryomonads, represent an ideal comparative system for investigating the constraints and reoccurring innovations in cell evolution. The fourth group of micro-eukaryotes offers compelling insights into one of the most enigmatic evolutionary transformations in the history of life: the origin of obligate intracellular (apicomplexan) parasites from free-living, photoautotrophic ancestors. Despite being infamous as pathogens of humans and livestock (e.g. Plasmodium and Toxoplasma), most of apicomplexan diversity is thriving in the world's oceans. The origin and early evolution of apicomplexans will be addressed by exploring the diversity and molecular phylogeny of marine gregarines, which are large and dynamic parasites that inhabit the extracellular spaces of marine invertebrates and insects.