Development and Composition of the Basal Complex During Plasmodium Sporogony

Project Summary Malaria parasites quickly amplify their numbers in both the human host and mosquito vector, with a single parasite capable of creating dozens, hundreds, or thousands of daughter parasites. The formation of merozoites (asexual blood stage, liver stage) or sporozoites (mosquito stage) involves the segmentation of these daughter parasites within the bounds of the initial parasite. This segmentation process has best been defined during schizogony in the asexual blood stage, during which the basal complex is assembled to direct the appropriate partitioning of subcellular contents to each daughter cell. Several stable, core members of the basal complex have been defined in both asexual and sexual stage development through complementary experiments, but nothing is known about the composition or functions of the basal complex during the even more complicated segmentation process involved in sporozoite budding. Therefore, in this proposed work, we will investigate the process of sporozoite segmentation that occurs within the Plasmodium yoelii oocyst using ultrastructural expansion microscopy, focused ion beam-scanning electron microscopy (FIB-SEM), and proximity proteomics. This will enable three-dimensional microscopy-based assessments across the process of sporogony that will focus on the involvement of the basal complex. Proximity proteomics approaches will allow a cross-stage and cross-species comparison of the composition of the basal complex, and provide a first view of how it changes over the lengthy process of sporozoite segmentation, which takes up to 10 days in Anopheles mosquitoes. In accomplishing this proposed work, we will advance our understanding of the cell biological processes that underlie sporozoite budding with these complementary microscopy and proteomic approaches. Our focus on the essential basal complex will provide the molecular landscape that is used for effective sporozoite segmentation required to promote parasite transmission.