Fig. 7.

Model of replication foci formation and progression in P. falciparum. P. falciparum ORC may contain fewer subunits than other eukaryotes with confirmed PfORC1, PfORC5 and a putative PfORC2 subunit. During intraerythrocytic developmental cycle (IDC), different proteins are regulated differently. Based on our immunofluorescence and Western blot data and other published data, PfORC1 is expressed during late ring or early trophozoite stage whereas both PfPCNA1 and PfORC5 are present through all stages. At the onset of DNA replication, during early trophozoite stage, these proteins colocalize with each other and form replication foci. These foci continue to replicate nuclear DNA till late trophozoite/early schizont stage. During schizont stage, these proteins follow different pathways. PfORC5 and PfPCNA slowly detach from each other until late schizont stage where the majority of these foci are separated from each other. However, PfORC1 is completely degraded at this late schizont stage. G1, S and G2/M phases are also indicated according to parasitic developmental stages.