scholarly journals Transfer of zymosan (yeast cell walls) to the parasitophorous vacuoles of macrophages infected with Leishmania amazonensis.

1992 ◽  
Vol 176 (3) ◽  
pp. 639-646 ◽  
Author(s):  
P S Veras ◽  
C de Chastellier ◽  
M Rabinovitch
Keyword(s):  
Cell Walls ◽  
Present Report ◽  
Leishmania Amazonensis ◽  
Protozoan Parasites ◽  
Beta Glucan ◽  
Environmental Signals ◽  
Particle Transfer ◽  
Latex Beads ◽  
Particle Recognition ◽  
Carbohydrate Ligands

Leishmania are flagellated protozoan parasites which, in their amastigote stages, survive and multiply within phagolysosome-like parasitophorous vacuoles (PV) of mammalian macrophages (MO). This study develops an earlier ultrastructural, incidental observation that zymosan particles (Z) were transferred to the PV of macrophages infected with Leishmania amazonensis. In the present report, a pulse-chase light microscopic assay was used to delineate several features of the Z transfer. The assay reflects both the movement of internalized particles to a position adjoining a PV, and their delivery to the vacuoles. Transfer was selective, in the sense that Z, beta-glucan or heat-killed yeast particles were transferred, whereas latex beads, aldehyde-fixed, or immunoglobulin G-coated erythrocytes were not. This selectivity may be related to the high density of carbohydrate ligands displayed on the surface of yeast-derived particles, to ligand resistance to lysosomal degradation or to signals encoded in the cytosolic tails of the receptors involved in particle recognition. A few Z particles could be found within PV after 1 h of incubation with infected MO, but chase periods of several hours at 34 degrees C were required for particle transfer to the PV in a substantial proportion of the MO. Ammonium chloride, chloroquine, or monensin, compounds which increase the pH in acidified compartments, substantially enhanced the transfer of Z particles. Finally, transfer was inhibited by cytochalasin D, but was unaffected by the antitubulin nocodazole. Although it is not yet known if particle transfer occurs by fusion of donor vesicles with PV or by interiorization of the former into the latter, the model described should be useful in the study of the interactions between large phagocytic vesicles and the modulation of those interactions by cellular, parasitic, and environmental signals.

Fusion between large phagocytic vesicles: targeting of yeast and other particulates to phagolysosomes that shelter the bacterium Coxiella burnetii or the protozoan Leishmania amazonensis in Chinese hamster ovary cells

1994 ◽  
Vol 107 (11) ◽  
pp. 3065-3076 ◽  
Author(s):  
P.S. Veras ◽  
C. de Chastellier ◽  
M.F. Moreau ◽  
V. Villiers ◽  
M. Thibon ◽  
...  
Keyword(s):  
Concanavalin A ◽  
Chinese Hamster Ovary ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Leishmania Amazonensis ◽  
Laser Fluorescence ◽  
Host Cells ◽  
Beta Glucan ◽  
Ovary Cells ◽  
Latex Beads

This report examines the fusion of phagocytic vesicles with the large phagolysosome-like vacuoles induced in Chinese hamster ovary cells by the bacterium Coxiella burnetti or the Protozoan flagellate Leishmania amazonensis. Infection by these organisms is compatible with cell survival and multiplication. Fusion was inferred from the transfer of microscopically identifiable particles from donor to target vesicles. Donor vesicles contained heat-killed yeast, zymosan, beta-glucan or latex beads taken up by the host cells. Yeast and zymosan were also coated with Concanavalin A to increase their uptake by the cells (Goldman, R., Exp. Cell Res. 104, 325–334, 1977). Particle localization, routinely ascertained by phase-contrast microscopy, was confirmed by confocal laser fluorescence and by transmission electron microscopy. Coxiella vacuoles admitted all the particles tested and transfer took place whether the particles were given to the cells prior to or after infection. Transfer of uncoated or Concanavalin-A-coated yeast or zymosan was dependent on the number of particles ingested and on the incubation period (between 2 and 24 hours). Furthermore, the transfer step was quite efficient, since over 85% of the particles ingested entered Coxiella vacuoles at all particle to cell ratios examined. The fraction of uncoated or Concanavalin-A-coated yeast or zymosan transferred to Leishmania vacuoles was consistently lower and diminished at higher particle loads. In addition, only rarely did latex beads enter these vacuoles. The models proposed may be useful for the delineation of biochemical and molecular mechanisms involved in the fusion of large phagocytic vesicles and the modulation of the latter by cellular and pathogen-derived signals.

Electron Microscopic Observations on the Effects of Polymixin B Sulfate to Cell Walls of Chlamydia Organisms

1972 ◽  
Vol 30 ◽  
pp. 326-327
Author(s):  
Akira Matsumoto
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Present Report ◽  
Bactericidal Effect ◽  
Chlamydia Psittaci ◽  
Gram Negative Bacteria ◽  
Electron Microscopic ◽  
Cell Content ◽  
Gram Negative ◽  
Reticulate Body

Cell walls of the both types of bodies, mature elementary body(EB) and developmental reticulate body(RB) of Chlamydia psittaci appear the triple layered membrane in thin section. However, in the preparations shadowcast or stained negatively EB cell wall shows hexagonally arrayed structure composed of subunits, 180A in diameter on the inside surface, whereas RB cell wall does not have this structure. Chemical analysis demonstrated that EB cell wall contained a similar amino acid composition with the cell walls of gram-negative bacteria, such as E.coli. The bactericidal effect of polymixin group against gram-negative bacilli is understood that the drug affects to the cell wall and destroys its osmotic regulation. Electron microscopy on the effects of the drug against the gram-negative bacteria revealed the formation of numerous number of projections on the cell wall surface and leakage of cell content through the projections. The present report is concerned with further studies on the fine structure of EB cell walls based on the observation on their response to polymixin B sulfate.

scholarly journals Nutraceutical functions of beta-glucans in human nutrition

2019 ◽  
pp. 315-324 ◽  
Keyword(s):  
Cardiovascular Diseases ◽  
Cell Walls ◽  
Immune Cell ◽  
Antioxidant Properties ◽  
Communicable Diseases ◽  
Yeast Cells ◽  
Beta Glucan ◽  
Antitumor Effects ◽  
Fungal Cell ◽  
Non Communicable Diseases

ABSTRACT Recent studies have shown that naturally occurring substances found in the food of the daily human diet are important for preventing chronic non-communicable diseases. One of them is beta-glucan, which is a natural polysaccharide, occurring in plant cell walls, mainly oats, barley and wheat. It is also present in baker’s yeast cells, fungal cell walls, and some microorganisms. Beta-glucan belongs to one of the dietary fiber fractions, which are attributed a number of beneficial health properties, including the prevention and treatment of certain digestive diseases and supporting the immune system. This compound has biological activity that depends on the size, molecular weight, conformation, frequency of bonds, solubility and changes in structure. Beta-glucan reduces cholesterol and glucose concentrations in the blood, which reduces the risk of cardiovascular disease and diabetes. In addition to its effects on lipid levels and glucose metabolism, beta-glucan also exhibits antioxidant properties by scavenging reactive oxygen species, thereby reducing the risk of diseases, including atherosclerosis, cardiovascular diseases, neurodegenerative diseases, diabetes, and cancer. Immunostimulatory and antitumor effects have also been reported. The immunostimulatory activity of beta-glucan occurs as a result of its attachment to specific receptors present on the immune cell surface. Beta-glucan belongs to the group of prebiotics which stimulate the growth and activity of the desired natural intestinal microbiota, while inhibiting the growth of pathogens. It plays an important role in the proper functioning of the gastrointestinal tract and preventing inflammation as well as colon cancer. Such a number of health benefits resulting from the properties of beta-glucan may play a key role in improving health and preventing chronic non-communicable diseases, such as diabetes, hypercholesterolemia, obesity, cardiovascular diseases, and cancer.

scholarly journals Dectin-1-Targeted Antifungal Liposomes Exhibit Enhanced Efficacy

mSphere ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Suresh Ambati ◽  
Aileen R. Ferarro ◽  
S. Earl Kang ◽  
Jianfeng Lin ◽  
Xiaorong Lin ◽  
...  
Keyword(s):  
Invasive Aspergillosis ◽  
Cell Walls ◽  
Fungal Pathogens ◽  
Antifungal Drugs ◽  
Beta Glucan ◽  
Fungal Cell ◽  
Content Type ◽  
Current Therapies ◽  
Mammalian Protein ◽  
Fungal Cell Walls

The fungus Aspergillus fumigatus causes pulmonary invasive aspergillosis resulting in nearly 100,000 deaths each year. Patients are often treated with antifungal drugs such as amphotericin B (AmB) loaded into liposomes (AmB-LLs), but all antifungal drugs, including AmB-LLs, have serious limitations due to human toxicity and insufficient fungal cell killing. Even with the best current therapies, 1-year survival among patients with invasive aspergillosis is only 25 to 60%. Hence, there is a critical need for improved antifungal therapeutics. Dectin-1 is a mammalian protein that binds to beta-glucan polysaccharides found in nearly all fungal cell walls. We coated AmB-LLs with Dectin-1 to make DEC-AmB-LLs. DEC-AmB-LLs bound strongly to fungal cells, while AmB-LLs had little affinity. DEC-AmB-LLs killed or inhibited A. fumigatus 10 times more efficiently than untargeted liposomes, decreasing the effective dose of AmB. Dectin-1-coated drug-loaded liposomes targeting fungal pathogens have the potential to greatly enhance antifungal therapeutics.

Three new species of Octosporella (Protozoa: Coccidia) from cyprinid fish in Algonquin Park, Ontario

1985 ◽  
Vol 63 (8) ◽  
pp. 1859-1862 ◽  
Author(s):  
Lianxiang Li ◽  
Sherwin S. Desser
Keyword(s):  
New Species ◽  
Present Report ◽  
Cyprinid Fish ◽  
Swim Bladder ◽  
Protozoan Parasites ◽  
Golden Shiner ◽  
Coccidian Parasites ◽  
The Common ◽  
Three New Species ◽  
First Time

Among the protozoan parasites observed in cyprinid fish from Lake Sasajewun and Lake Opeongo, Algonquin Park, Ontario, were coccidian parasites with oocysts containing eight sporocysts, each of which housed two sporozoites. Three new species of Octosporella Ray and Raghavachari, 1942 are described: Octosporella notropis sp. n. from the intestine, spleen, and swim bladder of the common shiner, Notropis cornutus (Mitchill), and Octosporella opeongoensis sp. n. and Octosporella sasajewunensis sp. n. from the swim bladder of the golden shiner, Notemigonus crysoleucas (Mitchill). The present report represents the first time parasites of this genus have been recorded from fish.

scholarly journals Compounds active against cell walls of medically important fungi.

1993 ◽  
Vol 6 (1) ◽  
pp. 1-21 ◽  
Author(s):  
R F Hector
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Soil Microbes ◽  
Preclinical Models ◽  
Beta Glucan ◽  
Glucan Synthesis ◽  
Secondary Mechanism ◽  
Further Development ◽  
Derivatives Of ◽  
Pharmacokinetic Behavior

A number of substances that directly or indirectly affect the cell walls of fungi have been identified. Those that actively interfere with the synthesis or degradation of polysaccharide components share the property of being produced by soil microbes as secondary metabolites. Compounds specifically interfering with chitin or beta-glucan synthesis have proven effective in studies of preclinical models of mycoses, though they appear to have a restricted spectrum of coverage. Semisynthetic derivatives of some of the natural products have offered improvements in activity, toxicology, or pharmacokinetic behavior. Compounds which act on the cell wall indirectly or by a secondary mechanism of action, such as the azoles, act against diverse fungi but are usually fungistatic in nature. Overall, these compounds are attractive candidates for further development.

scholarly journals Phagocytosis of antigens by Langerhans cells in vitro.

1993 ◽  
Vol 178 (2) ◽  
pp. 509-519 ◽  
Author(s):  
C Reis e Sousa ◽  
P D Stahl ◽  
J M Austyn
Keyword(s):  
Phagocytic Activity ◽  
Langerhans Cells ◽  
Fluorescein Isothiocyanate ◽  
Lymphoid Tissues ◽  
Differential Interference Contrast Microscopy ◽  
Beta Glucan ◽  
Color Flow ◽  
Latex Beads ◽  
Kinetics Of Uptake

Dendritic cells (DC) isolated from lymphoid tissues are generally thought to be nonphagocytic in culture. It has therefore been unclear how these cells could acquire particulate antigens such as microorganisms for initiation of primary immune responses. Lymphoid DC derive in part from cells that have migrated from nonlymphoid tissues, such as Langerhans cells (LC) of skin. The ability of LC to internalize a variety of particles was studied by electron, ultraviolet, phase, and differential interference contrast microscopy, and by two-color flow cytometry. Freshly isolated LC in epidermal cell suspensions phagocytosed the yeast cell wall derivative zymosan, intact Saccharomyces cerevisiae, representatives of two genera of Gram-positive bacteria, Corynebacterium parvum and Staphylococcus aureus, as well as 0.5-3.5-microns latex microspheres. During maturation in culture, the phagocytic activity of these cells was markedly reduced. Likewise, freshly isolated splenic DC were more phagocytic than cultured DC for two types of particle examined, zymosan and latex beads. Unlike macrophages, LC did not bind or internalize sheep erythrocytes before or after opsonization with immunoglobulin G or complement, and did not internalize colloidal carbon. The receptors mediating zymosan uptake by LC were examined. For this particle, C57BL/6 LC were considerably more phagocytic than BALB/c LC and exhibited a reproducible increase in phagocytic activity after 6 h of culture followed by a decline, whereas this initial rise did not occur for BALB/c LC. These differential kinetics of uptake were reflected in the pattern of zymosan binding at 4 degrees C, and endocytosis of the soluble tracer fluorescein isothiocyanate-mannose-bovine serum albumin at 37 degrees C. Zymosan uptake by LC from both strains of mice was inhibited in the presence of mannan or beta-glucan, although to different extents, but not by antibodies specific for CR3 (CD11b/CD18). These data indicate that zymosan uptake by LC can be mediated by a mannose/beta-glucan receptor(s) that is differentially expressed in the two strains of mice and that is downregulated during maturation of LC in culture.

scholarly journals Evolutionary Overview of Molecular Interactions and Enzymatic Activities in the Yeast Cell Walls

2020 ◽  
Vol 21 (23) ◽  
pp. 8996
Author(s):  
Renata Teparić ◽  
Mateja Lozančić ◽  
Vladimir Mrša
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Individual Component ◽  
Building Blocks ◽  
Fungal Cell ◽  
Environmental Signals ◽  
Identification And Characterization ◽  
Wall Components ◽  
Fungal Cell Walls

Fungal cell walls are composed of a polysaccharide network that serves as a scaffold in which different glycoproteins are embedded. Investigation of fungal cell walls, besides simple identification and characterization of the main cell wall building blocks, covers the pathways and regulations of synthesis of each individual component of the wall and biochemical reactions by which they are cross-linked and remodeled in response to different growth phase and environmental signals. In this review, a survey of composition and organization of so far identified and characterized cell wall components of different yeast genera including Saccharomyces, Candida, Kluyveromyces, Yarrowia, and Schizosaccharomyces are presented with the focus on their cell wall proteomes.

scholarly journals Benzyl Farnesyl Amine Mimetics are Potent Inhibitors of the Sterol Biosynthesis Pathway in Leishmania Amazonensis Leading to Oxidative Stress, Growth Arrest, and Ultrastructural Alterations

2022 ◽  
Author(s):  
Sara Teixeira Macedo-Silva ◽  
Gonzalo Visbal ◽  
Gabrielle Frizzo Souza ◽  
Mayara Roncaglia dos Santos ◽  
Simon B. Cämmerer ◽  
...  
Keyword(s):  
Leishmania Amazonensis ◽  
Sterol Biosynthesis ◽  
Biosynthesis Pathway ◽  
Protozoan Parasites ◽  
Stress Growth ◽  
Potent Effect ◽  
Physiological Analysis ◽  
Methyl Sterols ◽  
Ultrastructure And Function ◽  
And Function

Abstract Leishmaniasis is a neglected disease caused by protozoan parasites of the Leishmania genus spread around the world. Benzyl farnesyl amine mimetics are known class of compounds selectively designed to inhibit the squalene synthase (SQS) enzyme that catalyzes the first committed reaction on the sterol biosynthesis pathway. Herein, we studied seven new benzyl farnesyl amine mimetics (SBC 37 - 43) against Leishmania amazonensis. After the first initial screening of cell viability, two inhibitors (SBC 39 and SBC 40) were selected for further studies. Against intracellular amastigotes, SBC 39 and SBC 40 presented selectivity indexes of 117.7 and 180, respectively, indicating that they are highly selective. Analyses of free sterol showed that SBC 39 and SBC 40 inhibit two enzymes, sterol Δ8 → Δ7 isomerase and SQS, resulting in depletion of endogenous 24-methyl sterols. Physiological analysis and electron microscopy revealed three main alterations: 1) in the mitochondrion ultrastructure and function; 2) the presence of lipid bodies and autophagosomes; and 3) the appearance of projections in the plasma membrane and extracellular vesicles inside the flagellar pocket. In conclusion, our results support the notion that benzyl farnesyl amine mimics have a potent effect against Leishmania amazonensis and should be an interesting novel pharmaceutical lead for the development of new chemotherapeutic alternatives to treat leishmaniasis.

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