Dvorin, Jeffrey DAli, Ilzat2026-03-0420252026-02-272026Ali, Ilzat. 2026. Genes required for maintaining fidelity of Plasmodium daughter cell formation. Doctoral Dissertation, Harvard University Graduate School of Arts and Sciences.32283484https://dash.harvard.edu/handle/1/42731172Apicomplexan parasites utilize a divergent set of cell division mechanisms to replicate and form daughter cells that are morphologically distinct between different genera and even between different lifecycle stages within a species. Within a specific lifecycle stage, the parasites usually generate many daughter cells at once from a single parent. This, coupled with the complexity of the parasite life cycle across different hosts, presents a unique challenge for the parasite to ensure the successful inheritance of the replicated organelles and genetic material for each individual daughter cell. One such parasite that contributes to severe global health burden is Plasmodium falciparum, the causative agent of the deadliest form of malaria. This thesis aims to advance our understanding of the divergent cell division modes of Plasmodium using advanced microscopy techniques, focusing specifically on proteins involved in nuclear inheritance and their profound impact on the overall fidelity of daughter cells. The mode of asexual replication in the vertebrate host red blood cells (RBCs) is known as schizogony, and the mode of replication at the mosquito host midgut is called sporogony. In both cases, the daughter cell building materials including the nucleus, other organelles, and critical cytoskeletal components are replicated several times before a single round of cytokinesis forms many daughter cells. In Chapter 2, we demonstrate the importance of the two Plasmodium striated fiber assemblin (SFA) homologs, SFA1 and SFA2, and the rootlet fiber they form in these processes using super-resolution light microscopy and electron microscopy, filling a critical knowledge gap of Plasmodium cell biology. In Chapter 3, we use co-immunoprecipitation with an SFA protein as bait followed by mass spectrometry to discover potential interacting or associated proteins of the SFA rootlet fiber. We discuss the hits with known function or characterized orthologs and provide the list of proteins for future characterization. Then, we characterize three hits of unknown function from the list, PF3D7_1339700/PfPEARL, PF3D7_1307900/PfBBx, and PF3D7_0703600. Using immunofluorescence and ultrastructure expansion microscopy, we illustrate their localization relative to the SFA rootlet fiber and elucidate and/or hypothesize their roles during the erythrocytic asexual cycle. We find that all three proteins are important for asexual replication in RBCs and discuss future directions for deeper probing into their functions. Overall, our studies paint a more detailed picture of Plasmodium cell division, providing novel insights into the mediators of high-fidelity daughter cell formation. Characterizing the functions of SFAs and associated proteins has allowed us to delineate the structural and molecular framework that underpins nuclear inheritance and apical organelle formation in Plasmodium. These findings not only enhance our understanding of the fundamental biology of this deadly parasite but also open avenues for targeting parasite-specific division mechanisms in future antimalarial development.application/pdfencentriolar plaquePlasmodiumschizogonySFAsporogonyParasitologyCellular biologyBiologyThesis or Dissertation2026-03-040000-0003-2019-5645