A New Model For Hemoglobin ingestion and transport by the Human Intraerythrocytic Malaria Parasite, Plasmodium falciparum
The intraerythrocytic human malaria parasite, Plasmodium falciparum (P. falciparum), degrades up to 80% of host-cell hemoglobin within an acidic, de novo organelle termed the food vacuole (FV) to support parasite growth and survival. While hemoglobin hydrolysis has been intensively investigated, the mechanisms responsible for the internalization and transport of host cell hemoglobin to the FV are poorly understood. The current model for hemoglobin transport shares similarities with endolysosomal pathways. Since actin dynamics play key roles in vesicle formation and transport in endocytosis and P. falciparum actin (Pfactin) is present during each stage of intaerythrocytic development, we investigated the role of Pfactin in hemoglobin transport to the FV utilizing the actin perturbing agents jasplakinolide (JAS) and cytochalasin D (CD). Through analysis of parasitized erythrocytes (PE) by confocal microscopy and Western blots, using a parasite specific anti-actin antibody, we characterize Pfactin organization and distribution in intraerythrocytic P. falciparum, which was not previously investigated. In addition, we test the current hemoglobin transport model through extensive morphological analysis of single thin sections and serial thin sections of parasitized erythrocytes (PE) by electron microscopy. We find that actin dynamics play important, multiple roles in the hemoglobin transport pathway and our results suggest that hemoglobin delivery to the FV is essential for parasite survival. Evidence is provided for a new model in which hemoglobin transport to the FV occurs by a vesicle-independent process.
Lazarus, Michelle Denise, "A New Model For Hemoglobin ingestion and transport by the Human Intraerythrocytic Malaria Parasite, Plasmodium falciparum" (2008). ETD Collection for Thomas Jefferson University. AAI3535988.