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

30多亿年来，微生物在纯粹的丰度和多样性方面统治着地球，但微生物的基本和创新特性是所有现存生物中最不为人所知的。微真核生物在形态和遗传上都很复杂，具有细胞核、内膜系统、共生获得的细胞器和复杂的细胞骨架，支持大量的特化细胞扩展和行为。尽管每一个微真核生物只由一个细胞组成，但它们本身就是一个宇宙。最近我们对这些生物的理解取得了进展，这极大地改变了人们长期以来对细胞多样性的看法。因此，拟议的研究计划旨在探索这个陌生的世界，以帮助解开地球上生命的总体组成、相互关系和历史。个别项目将跨越真核生物多样性的极其广泛的采样，以解决细胞特征进化的大规模模式。该研究项目将同时继续研究四组主要的微真核生物，它们包含了地球上真核生物最不同的三种模式：捕食、光自养和寄生。海洋掠食性鞭毛虫，如真鞭毛虫、甲藻鞭毛虫和冷冻单胞虫，其独立但对应的形态变化模式为研究细胞进化的制约因素和重复创新提供了理想的比较系统。第四组微真核生物为生命史上最神秘的进化转变之一提供了令人信服的见解：专性细胞内（顶复合体）寄生虫来自自由生活的光自养祖先。尽管作为人类和牲畜的病原体（如疟原虫和弓形虫）而臭名昭著，但大多数顶复合体的多样性在世界海洋中蓬勃发展。顶复合体的起源和早期进化将通过探索海洋格林林的多样性和分子系统发育来解决。海洋格林林是一种栖息在海洋无脊椎动物和昆虫的细胞外空间的大型动态寄生虫。

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.