9629487 BURRESON The phylum Haplosporidia (three genera, about 31 species) consists of spore-forming parasitic protozoa, found in a wide variety of marine and freshwater invertebrate animals. Some species cause serious disease in commercially important shellfish, including oysters along the east coast of the United States. Accurate knowledge of the biology of Haplosporidia, starting with reliable identification and classification of the species, is essential for disease prevention and control. Classification depends on basic knowledge of how haplosporidian species are related to one another, and how the phylum Haplosporidia is related to other protists. This knowledge currently is inadequate. In this study, Eugene Burreson, Mark Siddall and Kimberly Reece will examine the morphological and molecular characteristics of several species of Haplosporidia, including the type species of each genus, and use this information to infer the phylogenetic relationships among haplosporidian species, and between Haplosporidia and other protist groups. They will conduct detailed observations on morphological features, especially the spores, with the light and electron microscopes, and will sequence small-subunit ribosomal RNA and actin genes. The phylogenetic reconstructions, and the classification schemes resulting from them, will inform pathogen control strategies by permitting more accurate identification of pathogens and, possibly, discovering novel aspects of haplosporidian biology (for example, different spore morphologies may represent stages in the life history of one haplosporidian species, rather than two different species).
