scholarly journals Methods Used to Investigate the Plasmodium falciparum Digestive Vacuole

2022 ◽  
Vol 11 ◽  
Author(s):  
Rebecca C. S. Edgar ◽  
Natalie A. Counihan ◽  
Sheena McGowan ◽  
Tania F. de Koning-Ward
Keyword(s):  
Plasmodium Falciparum ◽  
Blood Cells ◽  
Biochemical Analysis ◽  
Clinical Symptoms ◽  
Mechanisms Of Action ◽  
Main Constituent ◽  
Digestive Vacuole ◽  
Erythrocytic Stage ◽  
Acidic Compartment ◽  
Global Health Problem

Plasmodium falciparum malaria remains a global health problem as parasites continue to develop resistance to all antimalarials in use. Infection causes clinical symptoms during the intra-erythrocytic stage of the lifecycle where the parasite infects and replicates within red blood cells (RBC). During this stage, P. falciparum digests the main constituent of the RBC, hemoglobin, in a specialized acidic compartment termed the digestive vacuole (DV), a process essential for survival. Many therapeutics in use target one or multiple aspects of the DV, with chloroquine and its derivatives, as well as artemisinin, having mechanisms of action within this organelle. In order to better understand how current therapeutics and those under development target DV processes, techniques used to investigate the DV are paramount. This review outlines the involvement of the DV in therapeutics currently in use and focuses on the range of techniques that are currently utilized to study this organelle including microscopy, biochemical analysis, genetic approaches and metabolomic studies. Importantly, continued development and application of these techniques will aid in our understanding of the DV and in the development of new therapeutics or therapeutic partners for the future.

Effect of ketotifen on the ultrastructure of the Erythrocytic stage of Plasmodium Yoelii in mice

1990 ◽  
Vol 48 (3) ◽  
pp. 316-317
Author(s):  
Cao Han-min ◽  
Pan xing-qing
Keyword(s):  
Body Weight ◽  
Blood Cells ◽  
Biochemical Analysis ◽  
Plasmodium Yoelii ◽  
Ultrastructural Changes ◽  
Erythrocytic Stage ◽  
Blood Samples ◽  
Technical Report Series ◽  
Technical Report ◽  
The World

Since plasmodia have developed resistance to many of the drugs widely used as anti-malarials throughout the world, there is thus an urgency in the search for new types of anti-malarials (WHO technical report series 711; Liu et al. 1984). The search is going on worldwide. Several reports of the efficiency of ketotifen have been published in China. Base on biochemical analysis, Pan et al. reported that ketotifen showed strong anti-malarial effects on both a chloroquine sensitive strain of P. yoelii and a chloroquine resistant strain of P. berghei. In this paper we study the ultrastructural changes in plasmodia exposed to ketotifen.Experimental mice were inoculated intraperitoneally with 1 × 10 P.yoelii infected red blood cells. After four days, the parasitemia reach approximately 20-30%. 20mg ketotifen base per kg body weight was given to the mice orally. Blood samples were collected at 1,2,3,6,12,24,36,and 48 hours after drug administration.

scholarly journals Mode of action of quinoline antimalarial drugs in red blood cells infected by Plasmodium falciparum revealed in vivo

2019 ◽  
Vol 116 (46) ◽  
pp. 22946-22952 ◽  
Author(s):  
Sergey Kapishnikov ◽  
Trine Staalsø ◽  
Yang Yang ◽  
Jiwoong Lee ◽  
Ana J. Pérez-Berná ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Mode Of Action ◽  
Culture Medium ◽  
Crystal Surface ◽  
Membrane Surface ◽  
Antimalarial Drugs ◽  
Digestive Vacuole

The most widely used antimalarial drugs belong to the quinoline family. Their mode of action has not been characterized at the molecular level in vivo. We report the in vivo mode of action of a bromo analog of the drug chloroquine in rapidly frozen Plasmodium falciparum-infected red blood cells. The Plasmodium parasite digests hemoglobin, liberating the heme as a byproduct, toxic to the parasite. It is detoxified by crystallization into inert hemozoin within the parasitic digestive vacuole. By mapping such infected red blood cells with nondestructive X-ray microscopy, we observe that bromoquine caps hemozoin crystals. The measured crystal surface coverage is sufficient to inhibit further hemozoin crystal growth, thereby sabotaging heme detoxification. Moreover, we find that bromoquine accumulates in the digestive vacuole, reaching submillimolar concentration, 1,000-fold more than that of the drug in the culture medium. Such a dramatic increase in bromoquine concentration enhances the drug’s efficiency in depriving heme from docking onto the hemozoin crystal surface. Based on direct observation of bromoquine distribution in the digestive vacuole and at its membrane surface, we deduce that the excess bromoquine forms a complex with the remaining heme deprived from crystallization. This complex is driven toward the digestive vacuole membrane, increasing the chances of membrane puncture and spillage of heme into the interior of the parasite.

Ultrastructural observations on the in vitro cytoadherence of Plasmodium falciparum infected red blood cells

1990 ◽  
Vol 48 (3) ◽  
pp. 914-915
Author(s):  
D.J.P. Ferguson ◽  
A.R. Berendt ◽  
J. Tansey ◽  
K. Marsh ◽  
C.I. Newbold
Keyword(s):  
Plasmodium Falciparum ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Umbilical Vein ◽  
Cell Types ◽  
Amelanotic Melanoma ◽  
Cytoplasmic Process ◽  
Umbilical Vein Endothelial Cells

In human malaria, the most serious clinical manifestation is cerebral malaria (CM) due to infection with Plasmodium falciparum. The pathology of CM is thought to relate to the fact that red blood cells containing mature forms of the parasite (PRBC) cytoadhere or sequester to post capillary venules of various tissues including the brain. This in vivo phenomenon has been studied in vitro by examining the cytoadherence of PRBCs to various cell types and purified proteins. To date, three Ijiost receptor molecules have been identified; CD36, ICAM-1 and thrombospondin. The specific changes in the PRBC membrane which mediate cytoadherence are less well understood, but they include the sub-membranous deposition of electron-dense material resulting in surface deformations called knobs. Knobs were thought to be essential for cytoadherence, lput recent work has shown that certain knob-negative (K-) lines can cytoadhere. In the present study, we have used electron microscopy to re-examine the interactions between K+ PRBCs and both C32 amelanotic melanoma cells and human umbilical vein endothelial cells (HUVEC).We confirm previous data demonstrating that C32 cells possess numerous microvilli which adhere to the PRBC, mainly via the knobs (Fig. 1). In contrast, the HUVEC were relatively smooth and the PRBCs appeared partially flattened onto the cell surface (Fig. 2). Furthermore, many of the PRBCs exhibited an invagination of the limiting membrane in the attachment zone, often containing a cytoplasmic process from the endothelial cell (Fig. 2).

scholarly journals Molecular characterization of Polychromophilus parasites of Scotophilus kuhlii bats in Thailand

Parasitology ◽  
2020 ◽  
pp. 1-5
Author(s):  
Chatree Chumnandee ◽  
Nawarat Pha-obnga ◽  
Oskar Werb ◽  
Kai Matuschewski ◽  
Juliane Schaer
Keyword(s):  
Blood Cells ◽  
Clinical Symptoms ◽  
Temperate Climate ◽  
Diverse Group ◽  
Malaria Parasites ◽  
Climate Zones ◽  
Haemosporidian Parasites ◽  
South And Southeast Asia ◽  
Molecular Investigation

Abstract Parasites of the haemosporidian genus Polychromophilus have exclusively been described in bats. These parasites belong to the diverse group of malaria parasites, and Polychromophilus presents the only haemosporidian taxon that infects mammalian hosts in tropical as well as in temperate climate zones. This study provides the first information of Polychromophilus parasites in the lesser Asiatic yellow bat (Scotophilus kuhlii) in Thailand, a common vespertilionid bat species distributed in South and Southeast Asia. The gametocyte blood stages of the parasites could not be assigned to a described morphospecies and molecular analysis revealed that these parasites might represent a distinct Polychromophilus species. In contrast to Plasmodium species, Polychromophilus parasites do not multiply in red blood cells and, thus, do not cause the clinical symptoms of malaria. Parasitological and molecular investigation of haemosporidian parasites of wildlife, such as the neglected genus Polychromophilus, will contribute to a better understanding of the evolution of malaria parasites.

Endothelin-1 production by a microvascular endothelial cell line treated with Plasmodium falciparum parasitized red blood cells

2002 ◽  
Vol 103 (s2002) ◽  
pp. 464S-466S ◽  
Author(s):  
Nicoletta BASILICO ◽  
Livianna SPECIALE ◽  
Silvia PARAPINI ◽  
Pasquale FERRANTE ◽  
Donatella TARAMELLI
Keyword(s):  
Plasmodium Falciparum ◽  
Endothelial Cell ◽  
Red Blood Cells ◽  
Cell Line ◽  
Blood Cells ◽  
Microvascular Endothelial Cell ◽  
Microvascular Endothelium ◽  
Endothelial Cell Line ◽  
Endothelin 1 ◽  
Microvascular Endothelial

In this study, we investigated the production of endothelin 1 (ET-1) by a human microvascular endothelial cell line, HMEC-1, co-cultured with Plasmodium falciparum-parasitized red blood cells (pRBCs). The results indicate that hypoxia increased the basal level of ET-1 production by HMEC-1 cells after 24 or 48h of treatment. However, the co-incubation of HMEC-1 cells with pRBCs, but not with uninfected RBCs, induced a dose-dependent decrease of both constitutive and hypoxia-induced ET-1 production. The inhibition was not due to a decrease in cell viability, as lactate dehydrogenase release remained constant. These results indicate that pRBCs are able to interfere with both the constitutive and stimulated ET-1 release from the microvascular endothelium, thus inducing local modifications of the vascular tone and of the inflammatory response. This could be of relevance in the pathogenesis of the most severe forms of P. falciparum infections, such as cerebral malaria or malaria during pregnancy.

scholarly journals Multiple Antibiotics Exert Delayed Effects against the Plasmodium falciparum Apicoplast

2007 ◽  
Vol 51 (10) ◽  
pp. 3485-3490 ◽  
Author(s):  
Erica L. Dahl ◽  
Philip J. Rosenthal
Keyword(s):  
Plasmodium Falciparum ◽  
Cell Division ◽  
Antimalarial Activity ◽  
Mechanisms Of Action ◽  
Malaria Parasites ◽  
Delayed Effects ◽  
Delayed Death ◽  
Antimalarial Action ◽  
Multiple Antibiotics

ABSTRACT Several classes of antibiotics exert antimalarial activity. The mechanisms of action of antibiotics against malaria parasites have been unclear, and prior studies have led to conflicting results, in part because they studied antibiotics at suprapharmacological concentrations. We examined the antimalarial effects of azithromycin, ciprofloxacin, clindamycin, doxycycline, and rifampin against chloroquine-resistant (W2) and chloroquine-sensitive (3D7) Plasmodium falciparum strains. At clinically relevant concentrations, rifampin killed parasites quickly, preventing them from initiating cell division. In contrast, pharmacological concentrations of azithromycin, ciprofloxacin, clindamycin, and doxycycline were relatively inactive against parasites initially but exerted a delayed death effect, in which the progeny of treated parasites failed to complete erythrocytic development. The drugs that caused delayed death did not alter the distribution of apicoplasts into developing progeny. However, the apicoplasts inherited by the progeny of treated parasites were abnormal. The loss of apicoplast function became apparent as the progeny of antibiotic-treated parasites initiated cell division, with the failure of schizonts to fully mature or for erythrocyte rupture to take place. These findings explain the slow antimalarial action of multiple antibiotics.

scholarly journals Effect of Fluorescent Dyes onIn Vitro-Differentiated, Late-Stage Plasmodium falciparum Gametocytes

2014 ◽  
Vol 58 (12) ◽  
pp. 7398-7404 ◽  
Author(s):  
Tamirat Gebru ◽  
Benjamin Mordmüller ◽  
Jana Held
Keyword(s):  
Plasmodium Falciparum ◽  
Late Stage ◽  
Fluorescent Dyes ◽  
Clinical Symptoms ◽  
Laboratory Strain ◽  
Clinical Isolates ◽  
Synthetic Dyes ◽  
Content Type ◽  
Highly Active

ABSTRACTPlasmodium falciparumgametocytes are not associated with clinical symptoms, but they are responsible for transmitting the pathogen to mosquitoes. Therefore, gametocytocidal interventions are important for malaria control and resistance containment. Currently available drugs and vaccines are not well suited for that purpose. Several dyes have potent antimicrobial activity, but their use against gametocytes has not been investigated systematically. The gametocytocidal activity of nine synthetic dyes and four control compounds was tested against stage V gametocytes of the laboratory strain 3D7 and three clinical isolates ofP. falciparumwith a bioluminescence assay. Five of the fluorescent dyes had submicromolar 50% inhibitory concentration (IC50) values against mature gametocytes. Three mitochondrial dyes, MitoRed, dihexyloxacarbocyanine iodide (DiOC6), and rhodamine B, were highly active (IC50s < 200 nM). MitoRed showed the highest activity against gametocytes, with IC50s of 70 nM against 3D7 and 120 to 210 nM against clinical isolates. All compounds were more active against the laboratory strain 3D7 than against clinical isolates. In particular, the endoperoxides artesunate and dihydroartemisinin showed a 10-fold higher activity against 3D7 than against clinical isolates. In contrast to all clinically used antimalarials, several fluorescent dyes had surprisingly highin vitroactivity against late-stage gametocytes. Since they also act against asexual blood stages, they shall be considered starting points for the development of new antimalarial lead compounds.

scholarly journals Dielectric characterization of Plasmodium falciparum -infected red blood cells using microfluidic impedance cytometry

2018 ◽  
Vol 15 (147) ◽  
pp. 20180416 ◽  
Author(s):  
C. Honrado ◽  
L. Ciuffreda ◽  
D. Spencer ◽  
L. Ranford-Cartwright ◽  
H. Morgan
Keyword(s):  
Plasmodium Falciparum ◽  
Dielectric Properties ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Time Course ◽  
Fluorescent Protein ◽  
Clear Understanding ◽  
Infection Cycle ◽  
Dielectric Characterization ◽  
Impedance Cytometry

Although malaria is the world's most life-threatening parasitic disease, there is no clear understanding of how certain biophysical properties of infected cells change during the malaria infection cycle. In this article, we use microfluidic impedance cytometry to measure the dielectric properties of Plasmodium falciparum -infected red blood cells ( i- RBCs) at specific time points during the infection cycle. Individual parasites were identified within i- RBCs using green fluorescent protein (GFP) emission. The dielectric properties of cell sub-populations were determined using the multi-shell model. Analysis showed that the membrane capacitance and cytoplasmic conductivity of i- RBCs increased along the infection time course, due to membrane alterations caused by parasite infection. The volume ratio occupied by the parasite was estimated to vary from less than 10% at earlier stages, to approximately 90% at later stages. This knowledge could be used to develop new label-free cell sorting techniques for sample pre-enrichment, improving diagnosis.

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