title: Solute uptake into B. divergens and P. falciparum infected erythrocytes: same theme but different mechanisms
title: Der Transport von Lösung in von B. divergens und P. falciparum infizierten Erythrozyten
Creators: name: Sharma, Jyotsna
Publisher: name: Philipps-Universität Marburg
Year: 2016
Subjects: red blood cell infection by malaria parasite
Life sciences
Biowissenschaften, Biologie
Infektion, Parasit
Blutzelle

description: Plasmodium falciparum and Babesia
      divergens are parasites of the same phylogeny apicomplexa and
      they invade and replicate in the human erythrocytes. Both the
      parasites differently modify the host cell membrane during
      and after infection, providing an excellent example of
      parallel but distinct adaptations of the parasites to survive
      in the RBC. During invasion of the host erythrocyte, the
      parasite targets specific entry sites on the RBCs membrane,
      which is also the initial step in the biogenesis of the
      parasitophorous vacuole (PV). The parasitophorous vacuolar
      membrane (PVM) surrounds the parasite and thus P. falciparum
      remains surrounded by the vacuolar membrane for most of the
      parasite’s development. On the other hand in B. divergens,
      vacuolar membrane fate is unclear, owing to the lack of
      suitable markers. The electron microscopic studies suggest
      the disintegration of the PVM in the later stages of parasite
      maturation. As the differentiated erythrocyte does not
      endocytose or phagocytose, events leading to the formation of
      the PVM, in particular the contribution of the erythrocyte
      membrane (RBCM) are unknown. In order to understand better
      the internalization of RBCM proteins by parasites, we wanted
      to determine whether the lipid rafts, which are concentrated
      patches of lipids and proteins on the erythrocyte membrane,
      play any such role as specific entry site´ in the biogenesis
      of PV and also determine whether both parasites respectively
      internalize the same type of lipids/proteins or not. Recent
      work has shown that there is no internalization of major RBCM
      proteins, but the proteins which were found internalized are
      comparatively present in low abundance in the RBCM and are
      associated with the lipid rafts. In this work I used B.
      divergens and also P. falciparum infected erythrocytes to do
      a comparative investigation of the host cell lipids/proteins,
      whether they are included or excluded in PV. As a result (i)
      we found that both parasites recruit and exclude the same set
      of proteins. (ii) we used cholera toxin B subunit which binds
      to the ganglioside GM1, to follow the fate of this lipid raft
      associated glycophingolipid during PVM formation and
      disintegration. (iii) we observed that GM1 remains in the
      vicinity of P. falciparum during maturation but disappears
      from the vicinity of B. divergens as the parasite matures,
      consistent with a disintegration of the PVM. In conclusion,
      it appears that there is similarity between the early events
      in the PVM formation in both the parasites. All the
      biochemical pathways are dependent on the balance of the
      transport mechanisms and counteractions like the import of
      extracellular metabolites, export of the intracellular
      metabolites and proper waste disposal of unused metabolites.
      Thus the second part of my work was focused on the increased
      permeability of the host cell membrane after infection and
      appearance of new permeability pathways (NPP) in the infected
      erythrocyte. The erythrocyte which is save heaven´ for the
      parasite have limited resources and metabolism, that the
      parasite can use. The intracellular parasite is far more
      active inside the erythrocyte than outside cell. After
      invasion the small metabolically active merozoite stage of
      each genus (Plasmodium and Babesia) grows rapidly into other
      developmental stages (ring form and trophozoite form) inside
      the erythrocyte and thereby synthesizing DNA, RNA, proteins
      and lipids in large amounts. In order to fulfil all the
      essential requirements, the growing parasite induces changes
      in the membrane permeability of the erythrocyte and takes up
      solutes from the extracellular media via NPP. One among the
      other important amino acids required by the parasite is
      L-glutamate. The main aim of my work was to observe and
      characterize the transport of L- glutamate into B. divergens
      infected erythrocytes, and compare it with P. falciparum
      infected erythrocytes. As it is known that P. falciparum
      infected erythrocytes have both low- and high-affinity
      (EAAT3) glutamate transporter activated. The transport system
      present in B. divergens infected erythrocytes is unclear,
      therefore it is interesting to know the details of transport
      mechanism and see if it is parasite specific mechanism. Like
      P. falciparum, after infection of erythrocytes, B. divergens
      also induces the uptake of several solutes which are not
      taken up by non-infected erythrocytes. We found that B.
      divergens infected erythrocytes show uptake of glutamate via
      a low-affinity transport system. The other important
      characteristics of the glutamate transport observed was
      Na+-independency, non-saturability and non-stereo
      selectivity. There was also enhanced uptake of glutamate in
      the presence of choline. In conclusion, it appears that both
      parasites induce different mechanisms or transport systems
      for glutamate uptake and also the activation of the transport
      system is parasite specific.
description: Plasmodium falciparum und Babesia
      divergens sind Parasiten der selben phylogenetischen
      Apicomplexa, die Erythrozyten befallen und sich replizieren.
      Beide Parasiten modifizieren die Zellmembran während und nach
      der Infektion und geben so ein hervorragendes Beispiel für
      parallele aber unterschiedliche Adaption von Parasiten um im
      RBC zu überleben. In dieser Arbeit werden Aufnahme und
      Transport verschiedener Lösungen durch die veränderte
      Zellmembran untersucht.