Relevant bibliographies by topics / Chitin Fungal cell walls

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Academic literature on the topic 'Chitin Fungal cell walls'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Chitin Fungal cell walls"

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Ouellette, G. B., H. Chamberland, A. Goulet, M. Lachapelle, and J. G. Lafontaine. "Fine structure of the extracellular sheath and cell walls inOphiostoma novo-ulmigrowing on various substrates." Canadian Journal of Microbiology 45, no. 7 (August 1, 1999): 582–97. http://dx.doi.org/10.1139/w99-045.

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The presence of microfilamentous-like structures of tubular appearance (MFS) in cell walls and extracellular sheath material (ES) in a number of isolates of Ophiostoma novo-ulmi Brasier grown on various substrates and following various treatments is reported. Standard fixation or high-pressure freezing methods were used, and cytochemical tests were carried out to detect fungal and host wall components and, in some cases, fungal DNA. In some cases, serial 0.2-μm-thick sections were examined at 120 kV and tilted to obtain stereoscopic images. Whether the fungal cell walls were thick and composed of an outer opaque and inner more electron-lucent layers, or thin and barely perceptible, MFS were observed to extend from the cell cytoplasm as parallel structures across the walls into the surrounding medium, including host cell components in infected elm tissues. MFS were associated (in samples from inoculated trees) with cleavage and desquamation of fungal walls. ES and MFS did not label for cellulose or chitin, but generally labelled slightly for β-(1-3)-glucan and mannose, and strongly for galactose. Only the lucent, inner fungal wall layer labelled for chitin and cellulose. DNA labelling was confined to nuclei and mitochondria in fungal cells from cultures on agar medium; in cells from cultures on millipore membranes, it was pronounced over imprecisely delimited cell regions. The possible ontogeny of MFS components and their importance are discussed. Key words: chitin, Dutch elm disease, fungal fimbriae, fungal walls, gold-complexed probes, microfilamentous structures (MFS).
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Benhamou, Nicole, Karen Broglie, Richard Broglie, and Ilan Chet. "Antifungal effect of bean endochitinase on Rhizoctonia solani: ultrastructural changes and cytochemical aspects of chitin breakdown." Canadian Journal of Microbiology 39, no. 3 (March 1, 1993): 318–28. http://dx.doi.org/10.1139/m93-045.

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A chitinase, purified to homogeneity from ethylene-treated bean leaves, was applied to actively growing mycelial cells of Rhizoctonia solani to evaluate a potential antifungal activity. Light microscopic investigations at 30-min intervals following enzyme exposure revealed the induction of morphological changes such as swelling of hyphal tips and hyphal distortions. More precise information concerning fungal cell alteration was obtained by ultrastructural observation and cytochemical detection of chitin distribution in fungal cell walls. Chitin breakdown was found to be an early event preceding wall disruption and cytoplasm leakage. The large amounts of chitin present in the walls of control R. solani cells and the rapid chitin hydrolysis upon chitinase treatment lead us to suggest that this polysaccharide is one of the main components of this fungal cell wall and is readily accessible to chitinase, especially in the apical zone. By 60 min after enzyme treatment, labeled molecules were observed in the vicinity of some fungal cells, suggesting the release of chitin oligosaccharides from fungal cell walls. The antifungal activity of the bean chitinase on cells of R. solani grown in culture is discussed in relation to the potential of genetically modified transgenic plants to resist attack by R. solani through an antimicrobial activity in planta.Key words: gold labeling, wheat germ agglutinin, cytochemistry, Rhizoctonia solani, bean endochitinase.
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Plaza, Verónica, Evelyn Silva-Moreno, and Luis Castillo. "Breakpoint: Cell Wall and Glycoproteins and their Crucial Role in the Phytopathogenic Fungi Infection." Current Protein & Peptide Science 21, no. 3 (March 26, 2020): 227–44. http://dx.doi.org/10.2174/1389203720666190906165111.

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The cell wall that surrounds fungal cells is essential for their survival, provides protection against physical and chemical stresses, and plays relevant roles during infection. In general, the fungal cell wall is composed of an outer layer of glycoprotein and an inner skeletal layer of β-glucans or α- glucans and chitin. Chitin synthase genes have been shown to be important for septum formation, cell division and virulence. In the same way, chitin can act as a potent elicitor to activate defense response in several plant species; however, the fungi can convert chitin to chitosan during plant infection to evade plant defense mechanisms. Moreover, α-1,3-Glucan, a non-degradable polysaccharide in plants, represents a key feature in fungal cell walls formed in plants and plays a protective role for this fungus against plant lytic enzymes. A similar case is with β-1,3- and β-1,6-glucan which are essential for infection, structure rigidity and pathogenicity during fungal infection. Cell wall glycoproteins are also vital to fungi. They have been associated with conidial separation, the increase of chitin in conidial cell walls, germination, appressorium formation, as well as osmotic and cell wall stress and virulence; however, the specific roles of glycoproteins in filamentous fungi remain unknown. Fungi that can respond to environmental stimuli distinguish these signals and relay them through intracellular signaling pathways to change the cell wall composition. They play a crucial role in appressorium formation and penetration, and release cell wall degrading enzymes, which determine the outcome of the interaction with the host. In this review, we highlight the interaction of phypatophogen cell wall and signaling pathways with its host and their contribution to fungal pathogenesis.
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Mora-Montes, Héctor M., Mihai G. Netea, Gerben Ferwerda, Megan D. Lenardon, Gordon D. Brown, Anita R. Mistry, Bart Jan Kullberg, et al. "Recognition and Blocking of Innate Immunity Cells by Candida albicans Chitin." Infection and Immunity 79, no. 5 (February 28, 2011): 1961–70. http://dx.doi.org/10.1128/iai.01282-10.

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ABSTRACTChitin is a skeletal cell wall polysaccharide of the inner cell wall of fungal pathogens. As yet, little about its role during fungus-host immune cell interactions is known. We show here that ultrapurified chitin fromCandida albicanscell walls did not stimulate cytokine production directly but blocked the recognition ofC. albicansby human peripheral blood mononuclear cells (PBMCs) and murine macrophages, leading to significant reductions in cytokine production. Chitin did not affect the induction of cytokines stimulated by bacterial cells or lipopolysaccharide (LPS), indicating that blocking was not due to steric masking of specific receptors. Toll-like receptor 2 (TLR2), TLR4, and Mincle (the macrophage-inducible C-type lectin) were not required for interactions with chitin. Dectin-1 was required for immune blocking but did not bind chitin directly. Cytokine stimulation was significantly reduced upon stimulation of PBMCs with heat-killed chitin-deficientC. albicanscells but not with live cells. Therefore, chitin is normally not exposed to cells of the innate immune system but is capable of influencing immune recognition by blocking dectin-1-mediated engagement with fungal cell walls.
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Chrissian, Christine, Coney Pei-Chen Lin, Emma Camacho, Arturo Casadevall, Aaron M. Neiman, and Ruth E. Stark. "Unconventional Constituents and Shared Molecular Architecture of the Melanized Cell Wall of C. neoformans and Spore Wall of S. cerevisiae." Journal of Fungi 6, no. 4 (December 1, 2020): 329. http://dx.doi.org/10.3390/jof6040329.

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The fungal cell wall serves as the interface between the cell and the environment. Fungal cell walls are composed largely of polysaccharides, primarily glucans and chitin, though in many fungi stress-resistant cell types elaborate additional cell wall structures. Here, we use solid-state nuclear magnetic resonance spectroscopy to compare the architecture of cell wall fractions isolated from Saccharomyces cerevisiae spores and Cryptococcus neoformans melanized cells. The specialized cell walls of these two divergent fungi are highly similar in composition. Both use chitosan, the deacetylated derivative of chitin, as a scaffold on which a polyaromatic polymer, dityrosine and melanin, respectively, is assembled. Additionally, we demonstrate that a previously identified but uncharacterized component of the S. cerevisiae spore wall is composed of triglycerides, which are also present in the C. neoformans melanized cell wall. Moreover, we identify a tyrosine-derived constituent in the C. neoformans wall that, although it is not dityrosine, is a non-pigment constituent of the cell wall. The similar composition of the walls of these two phylogenetically distant species suggests that triglycerides, polyaromatics, and chitosan are basic building blocks used to assemble highly stress-resistant cell walls and the use of these constituents may be broadly conserved in other fungal species.
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Vogt, Stephan, Marco Kelkenberg, Tanja Nöll, Benedikt Steinhoff, Holger Schönherr, Hans Merzendorfer, and Gilbert Nöll. "Rapid determination of binding parameters of chitin binding domains using chitin-coated quartz crystal microbalance sensor chips." Analyst 143, no. 21 (2018): 5255–63. http://dx.doi.org/10.1039/c8an01453a.

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Lopez-Moya, Federico, Marta Suarez-Fernandez, and Luis Lopez-Llorca. "Molecular Mechanisms of Chitosan Interactions with Fungi and Plants." International Journal of Molecular Sciences 20, no. 2 (January 15, 2019): 332. http://dx.doi.org/10.3390/ijms20020332.

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Chitosan is a versatile compound with multiple biotechnological applications. This polymer inhibits clinically important human fungal pathogens under the same carbon and nitrogen status as in blood. Chitosan permeabilises their high-fluidity plasma membrane and increases production of intracellular oxygen species (ROS). Conversely, chitosan is compatible with mammalian cell lines as well as with biocontrol fungi (BCF). BCF resistant to chitosan have low-fluidity membranes and high glucan/chitin ratios in their cell walls. Recent studies illustrate molecular and physiological basis of chitosan-root interactions. Chitosan induces auxin accumulation in Arabidopsis roots. This polymer causes overexpression of tryptophan-dependent auxin biosynthesis pathway. It also blocks auxin translocation in roots. Chitosan is a plant defense modulator. Endophytes and fungal pathogens evade plant immunity converting chitin into chitosan. LysM effectors shield chitin and protect fungal cell walls from plant chitinases. These enzymes together with fungal chitin deacetylases, chitosanases and effectors play determinant roles during fungal colonization of plants. This review describes chitosan mode of action (cell and gene targets) in fungi and plants. This knowledge will help to develop chitosan for agrobiotechnological and medical applications.
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van den Burg, Harrold A., Stuart J. Harrison, Matthieu H. A. J. Joosten, Jacques Vervoort, and Pierre J. G. M. de Wit. "Cladosporium fulvum Avr4 Protects Fungal Cell Walls Against Hydrolysis by Plant Chitinases Accumulating During Infection." Molecular Plant-Microbe Interactions® 19, no. 12 (December 2006): 1420–30. http://dx.doi.org/10.1094/mpmi-19-1420.

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Resistance against the leaf mold fungus Cladosporium fulvum is mediated by the tomato Cf proteins which belong to the class of receptor-like proteins and indirectly recognize extracellular avirulence proteins (Avrs) of the fungus. Apart from triggering disease resistance, Avrs are believed to play a role in pathogenicity or virulence of C. fulvum. Here, we report on the avirulence protein Avr4, which is a chitin-binding lectin containing an invertebrate chitin-binding domain (CBM14). This domain is found in many eukaryotes, but has not yet been described in fungal or plant genomes. We found that interaction of Avr4 with chitin is specific, because it does not interact with other cell wall polysaccharides. Avr4 binds to chitin oligomers with a minimal length of three N-acetyl glucosamine residues. In vitro, Avr4 protects chitin against hydrolysis by plant chitinases. Avr4 also binds to chitin in cell walls of the fungi Trichoderma viride and Fusarium solani f. sp. phaseoli and protects these fungi against normally deleterious concentrations of plant chitinases. In situ fluorescence studies showed that Avr4 also binds to cell walls of C. fulvum during infection of tomato, where it most likely protects the fungus against tomato chitinases, suggesting that Avr4 is a counter-defensive virulence factor.
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COUSIN, M. A. "Chitin as a Measure of Mold Contamination of Agricultural Commodities and Foods†." Journal of Food Protection 59, no. 1 (January 1, 1996): 73–81. http://dx.doi.org/10.4315/0362-028x-59.1.73.

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Chitin is a polysaccharide of β-(1→4)-linked 2-acetamido-2-deoxy-d-glucose (N-acetyl-d-glucosamine) that is found in the cell walls of fungi. In an effort to develop new methods to detect fungi in plant and animal tissues, chemical analyses based on fungal cell wall components have been evaluated. Chitin is not present in plant or most food animal tissues; therefore, the entire sample can be hydrolyzed and analyzed for fungal chitin. Acid, alkaline, and enzymatic hydrolysis have been used to cleave the β-(1→4)-glycosidic bond to produce glucosamine, chitosan, or N-acetylglucosamine. The major methods used to analyze these degradation products have included colorimetry; chromatography (gas chromatography, high performance liquid chromatography, amino acid analysis); microscopy, using fluorescent, nonfluorescent or immunofluorescent dyes; near-infrared spectroscopy; and titrametric assays. Chitin has been used to estimate and quantify fungal growth in plants, wood, grains, hay, and foods. There was an increase in the chitin content as the mold increased; however, the chitin assay showed more variability than other assays for detecting fungal contamination. The future use of the chitin assay will depend upon improvements in sensitivity, assay time, simplified methodology and equipment, and development of reliable conversion factors for converting chitin to fungal dry weight.
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Volk, Helena, Kristina Marton, Marko Flajšman, Sebastjan Radišek, Hui Tian, Ingo Hein, Črtomir Podlipnik, et al. "Chitin-Binding Protein of Verticillium nonalfalfae Disguises Fungus from Plant Chitinases and Suppresses Chitin-Triggered Host Immunity." Molecular Plant-Microbe Interactions® 32, no. 10 (October 2019): 1378–90. http://dx.doi.org/10.1094/mpmi-03-19-0079-r.

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During fungal infections, plant cells secrete chitinases, which digest chitin in the fungal cell walls. The recognition of released chitin oligomers via lysin motif (LysM)-containing immune host receptors results in the activation of defense signaling pathways. We report here that Verticillium nonalfalfae, a hemibiotrophic xylem-invading fungus, prevents these digestion and recognition processes by secreting a carbohydrate-binding motif 18 (CBM18)-chitin-binding protein, VnaChtBP, which is transcriptionally activated specifically during the parasitic life stages. VnaChtBP is encoded by the Vna8.213 gene, which is highly conserved within the species, suggesting high evolutionary stability and importance for the fungal lifestyle. In a pathogenicity assay, however, Vna8.213 knockout mutants exhibited wilting symptoms similar to the wild-type fungus, suggesting that Vna8.213 activity is functionally redundant during fungal infection of hop. In a binding assay, recombinant VnaChtBP bound chitin and chitin oligomers in vitro with submicromolar affinity and protected fungal hyphae from degradation by plant chitinases. Moreover, the chitin-triggered production of reactive oxygen species from hop suspension cells was abolished in the presence of VnaChtBP, indicating that VnaChtBP also acts as a suppressor of chitin-triggered immunity. Using a yeast-two-hybrid assay, circular dichroism, homology modeling, and molecular docking, we demonstrated that VnaChtBP forms dimers in the absence of ligands and that this interaction is stabilized by the binding of chitin hexamers with a similar preference in the two binding sites. Our data suggest that, in addition to chitin-binding LysM (CBM50) and Avr4 (CBM14) fungal effectors, structurally unrelated CBM18 effectors have convergently evolved to prevent hydrolysis of the fungal cell wall against plant chitinases and to interfere with chitin-triggered host immunity.
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Dissertations / Theses on the topic "Chitin Fungal cell walls"

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Lee, Keunsook Kathy. "Echinocandin resistance of Candida albicans due to elevated cell wall chitin." Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=210190.

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Walker, Louise. "Dynamic responses of the fungal cell wall to stress and antifungal treatment." Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=136783.

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The main aim of this project was to determine the potential of increased chitin content as a mechanism of resistance to caspofungin in different fungal pathogens. C. albicans wild-type cells were pre-grown with a combination of CaCl2 and CFW prior to caspofungin treatment. This result sin a three-fold increase in cell wall chitin. Wild-type cells, which had elevated chitin content, were less susceptible to caspofungin. Priming cells to activated chitin synthesis was also able to compensate for the loss of the normally essential CaCHS1, through formation of three novel forms of salvage septa. In the absence of both CaChs1 and CaChs3, which are typically involved in septum formation, the class I chitin synthases, CaChs2 and CaChs8, could be stimulated to synthesise a proximally offset salvage septum. When CaChs3 was the only remaining chitin synthase, treatment with CaCl2 and CFW, led to the formation of thick chitin-rich salvage septa. CaChs2 and CaChs3 could be stimulated by treatment with CaCl2 and CFW to synthesise a thin salvage septum similar to the septum of wild-type cells. All three salvage septa were capable of restoring viability and cell division in C. albicans. The compensatory increase in chitin content in response to caspofungin treatment was not specific to C. albicans because clinical isolates of C. tropicalis, C. parapsilosis and C. guilliermondii and the filamentous fungus, A. fumigatus, also demonstrated an increase in chitin content after treatment with caspofungin. Isolates of C. glabrata and C. krusei showed no change in chitin content when exposed to caspofungin. The results of this thesis highlight the potential for using chitin synthase inhibitors in combination therapy with the echinocandins.
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Köhnlein, Maximilian. "Preparation of films and nonwoven composites from fungal microfibers grown in bread waste." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-23820.

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Unsold bread makes up a signification fraction of waste occurring in Swedish supermarkets. This thesis seeks to address the problem of food waste, by cultivating filamentous fungi on bread waste and producing chitinous films and nonwovens from them. Rhizopus delemar was cultivated on bread waste in liquid-state fermentation in order to obtain mycelia biomass. The biomass was processed by alkali or protease treatments to disrupt the fungal cells and remove proteins and fats. Afterwards it was subjected to a bleaching treatment to remove lignin fractions of bread residues. The treated biomass was then subjected to a grinding treatment for a homogeneous dispersion of mycelial fibers, where the dispersion was confirmed by microscopic images. The chemically and mechanically processed biomass was used for the preparation of films and nonwoven composites by employing a wet-laid papermaking process. The films exhibited plastic-like features, due to their brittleness and their smooth upper surface. Films and nonwoven composites were characterized on their tensile properties, surface water contact angle and their surface morphology by scanning electron microscopy. Treating fungal biomass by alkali and then bleaching resulted in films with atensile modulus of 3.38 GPa and an ultimate tensile strength of 71.50 MPa. These are the highest reported tensile properties for mycelia derived films to date. Water contact angle measurements confirmed a hydrophobic quality of mycelial films. Scanning electron microscopy showed a very dense and even surface without an obvious fibrous morphology. Fungal biomass and viscose fibers together form a rigid nonwoven composite, in which fungal biomass takes over the role of a natural eco-friendly binding matrix. Flexural rigidity measurements were out of bounds and need to be confirmed by future studies. Additionally, a second strain of fungi, Fusarium venenatum, was cultivated on bread particles in water suspension in order to determine optimum growth conditions for future scale-up investigations.
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Mackenzie, Ashleigh. "The role of Rhynchosporium commune cell wall components in cell wall integrity and pathogenicity." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=225718.

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Rhynchosporium commune is one of the most destructive pathogens of barley worldwide. It can cause crop yield losses of up to 40% in the UK and decrease in grain quality. Populations of R. commune can change rapidly, defeating new barley resistance (R) genes and fungicides after just a few seasons of their use. Fungicide use is one of the major modes of management of Rhynchosporium and is heavily relied on the agricultural industry. Fungicides that were effective in the past are no longer effective in controlling the disease and many are only effective when used in mixtures. Beyond the currently effective fungicides there is limited new chemistry available so there is a very real need for development in this area. In pathogenic fungi, the cell wall components play a key role in the establishment of pathogenesis. The cell wall forms the outer structure protecting the fungus from the host defence mechanisms. It is involved in initiating the direct contact with the host cells by adhering to their surface. The fungal cell wall also contains important antigens and other compounds modulating host immune responses. R. commune germinated conidia and interaction transcriptome sequencing generated a list of over 30 different cell wall proteins (CWPs) potentially involved in pathogenicity. R. commune genome and interaction transcriptome sequencing provided further information about the extent of CWP families as well as a subset of genes expressed during barley colonisation by R. commune. The use of bioinformatic techniques allowed for the analysis of gene sequences. Putative cell wall associated genes were compared to the sequences from the fungal database via sequence similarity, sequence alignments 15 and conserved domain searches to better understand their function. Phylogenetic analysis also allowed us to understand the evolutionary relationship between R. commune genes and related genes in other organisms. Transcription profiling of R. commune CWPs during the development of infection helped to prioritise them for functional characterisation. Targeted gene disruption unfortunately did not yield mutants but has furthered our understanding of this technique in R. commune for future attempts. Functional complementation was successful however and allowed the uncovering of the function of RSA9. The results show that R. commune RSA9 functions as an allantoicase, an enzyme which breaks down purines as a source of nitrogen when conditions are nitrogen limited. The use of chemical cell wall inhibitors allowed us to better understand the role of carbohydrate cell wall components in R. commune fitness and virulence. Inhibition of cellulose production by DCB showed reduced growth, germination and pathogenicity of R. commune. Similar results were observed when beta-glucan synthesis was impaired; as inhibitor concentration increased, growth and germination of the fungus decreased. The composition of R. commune cell wall was also uncovered during this research. Techniques such as HPLC and FTIR eluded the composition of monosaccharides and polysaccharides respectively. In addition the structure of R. commune cell wall was observed by microscopy, namely TEM. This project revealed some much needed information on the R. commune cell wall and the relation of its components to fitness and virulence during infection of barley.
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Lamon, Gaëlle. "Structural characterization of fungal cell walls architecture by solid-state NMR." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0314.

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Il existe une grande variété de champignons pathogènes humains qui sont à l’origine de maladies bénignes à mortelles. La plupart du temps, ces infections sont associées à d’autres pathologies ou traitements médicaux comme l’asthmes, les leucémies, les transplantations d’organes, le SIDA ou les traitement immunosuppresseurs à base de corticostéroides. Malgré le nombre important de décès et le nombre grandissant d’occurrence des mycoses sévères à travers le monde, les infections fongiques sont encore négligées par les autorités sanitaires.Parmi ces pathogènes fongiques, le champignon filamenteux Aspergillus fumigatus est un des pathogènes principaux du système respiratoire. L’aspergillose, dont les taux de d’infection et de mortalité demeurent élevés, devient un enjeu de santé publique. Les spores d’A. fumigatus sont entourés d’une paroi, essentielle pour leur croissance et leur permettant de résister face au système immunitaire de l’hôte. Cette paroi est composée d’un réseau de polysaccharides recouvert d’un pigment appelé DHN-mélanine et d’une couche de protéines appelées hydrophobines. Ce projet a pour but d’établir l’architecture structurale de la paroi des spores d’A. fumigatus à l’échelle atomique en utilisant la RMN du solide (ssNMR) en rotation à l’angle magique (MAS).D’un autre côté, Cryptococcus neoformans est l’agent pathogène responsable de la cryptococcose ; une mycose affectant le système nerveux central. Cette maladie fongique est, encore de nos jours, une cause significative de mortalité à travers le monde puisqu’elle entraîne de graves symptômes tels que la méningo-encéphalite ; particulièrement fréquente chez les patients déjà infectés par le VIH. C. neoformans se présente sous la forme d’une cellule encapsulée de 5 à 7 μm de diamètre entourée d’une paroi et d’une capsule. Cette paroi, rigide, est liée à la membrane plasmique et composée de polymères d’α-glucan, de β-glucan, de chitine et de chitosan. De plus, la capsule de C. neoformans est majoritairement composée de carbohydrates tels que le glucuronoxylomannan (GXM) (jusqu’à 90 %) ou le glucuronoxylomannogalactan (GXMGal) mais aussi de mannoprotéines et de lipides. Le but de ce projet de thèse est d’identifier les différents composants de la paroi mais aussi de la capsule de C. neoformans par ssNMR et d’établir l’architecture de ces deux entités. Un des aspects de ce projet est aussi d’explorer les possibilités et les limitations des méthodes de détection proton en RMN couplée à un MAS élevé (100 kHz) comme outil d’analyse des parois fongiques.En résumé, puisque la RMN des solides est une méthode de spectroscopie non invasive, nous avons appliqué ce type d’analyses dans le cadre de l’étude de l’architecture moléculaire de systèmes complexes (parois fongiques, capsules, …) dans des conditions aussi proches que possible de l’état natif des cellules. Pendant ces trois années de thèse, nous avons mis en place une méthodologie robuste et rapide permettant d’étudier la composition complexe des structures externes présentes dans les cellules fongiques ainsi que leur architecture au sein des cellules entières. De plus, puisque dans le cadre des infections microbiennes la pathogénicité du microbe repose souvent sur les structures externes des cellules infectieuses, les résultats obtenus au court de cette thèse, apportant une meilleure compréhension de l’organisation cellulaire d’A. fumigatus et C. neoformans, pourraient ainsi être utilisés dans le cadre du développement et de la mise en place de nouvelles stratégies thérapeutiques afin de combattre plus efficacement ces infections fongiques
There is a broad range of fungal pathogen infecting humans and causing diseases that can be from mild to lethal. Severe fungal infections are due to opportunistic pathogens that infect immunosuppressed individuals and are most of the time associated with other diseases or medical conditions such as asthma, leukemia, organ transplants, AIDS or immunosuppressive corticosteroid therapies. Despite the number of deaths and the increase in severe mycosis, fungal infections remain neglected by public health authorities.Among fungal pathogens, the filamentous fungus Aspergillus fumigatus is one of the major pathogen of the respiratory system. Aspergillosis displaying both high incidence and mortality rates, is becoming a massive public health issue. The spores of Aspergillus fumigatus are surrounded by a cell wall, essential for their growth and allowing them to resist against host defense mechanisms. The cell wall is composed of a set of polysaccharides covered by the DHN-melanin pigment and a layer of proteins called hydrophobins. In this project, we aimed at investigated the structural architecture of Aspergillus fumigatus cell wall at atomic resolution using MAS ssNMR spectroscopy.In another hand, Cryptococcus neoformans is the etiological agent of cryptococcosis; which consists in mycosis affecting the central nervous system. This fungal disease remains a significant cause of mortality worldwide by leading to severe symptoms such as meningoencephalitis - especially for immunocompromised individuals suffering from AIDS. C. neoformans results in encapsulated particles with a size of 5-7μm with a two-layers external structure composed of a cell wall and a capsule. The cell wall, rigid, is bounded to the plasma membrane and composed of polymers of α-glucan, β-glucan, chitin and chitosan45. Then, the capsule of C. neoformans is mainly composed of carbohydrates such as glucuronoxylomannan (GXM) (up to 90%), glucuronoxylomannogalactan (GXMGal), mannoproteins and lipids. During this thesis project, we aimed at identifying the different components of C.neoformans cell wall and capsule by ssNMR and to investigate the architecture of these two layers. Part of this project was also the exploration of possibilities and limits of 1H detection methods at fast MAS regime (100 kHz) as the tool to analyze intact cell walls.To sum up, as the solid-state NMR is a non-destructive spectroscopy, we applied this method to the study of the molecular architecture of complex systems (cell wall, capsule…) in cellular conditions – as close as possible to the native state. During these three years, we set up a methodology allowing studying the complex composition of fungal external structures as well as their architecture in the cell context. Finally, because in microbial infections, the pathogenesis often relies on the external structures of the pathogen, all these results could give a better comprehension of the A. fumigatus and C. neoformans cell organization that may help to find new therapeutic strategies to fight, more efficiently, against fungal infections
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Ball, Lucy Margaret. "Antifungals and the trichophyton rubrum cell wall." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670146.

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Engle, Joshua Andrew. "Expression of Penicillium marneffei Chitin Synthase Genes in Response to Cell-Wall Stressors." Youngstown State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1442356136.

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Zamani, Akram. "Superabsorbent Polymers from the Cell Wall of Zygomycetes Fungi." Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3556.

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The present thesis presents new renewable, antimicrobial and biodegradable superabsorbent polymers (SAPs), produced from the cell wall of zygomycetes fungi. The cell wall was characterized and chitosan, being one of the most important ingredients, was extracted, purified, and converted to SAP for use in disposable personal care products designed for absorption of different body fluids. The cell wall of zygomycetes fungi was characterized by subsequent hydrolysis with sulfuric and nitrous acids and analyses of the products. The main ingredients of the cell wall were found to be polyphosphates (4-20%) and copolymers of glucosamine and N-acetyl glucosamine, i.e. chitin and chitosan (45-85%). The proportion of each of these components was significantly affected by the fungal strain and also the cultivation conditions. Moreover, dual functions of dilute sulfuric acid in relation to chitosan, i.e. dissolution at high temperatures and precipitation at lowered temperatures, were discovered and thus used as a basis for development of a new method for extraction and purification of the fungal chitosan. Treatment of the cell wall with dilute sulfuric acid at room temperature resulted in considerable dissolution of the cell wall polyphosphates, while chitosan and chitin remained intact in the cell wall residue. Further treatment of this cell wall residue, with fresh acid at 120°C, resulted in dissolution of chitosan and its separation from the remaining chitin/chitosan of the cell wall skeleton which was not soluble in hot acid. Finally, the purified fungal chitosan (0.34 g/g cell wall) was recovered by precipitation at lowered temperatures and pH 8-10. The purity and the yield of fungal chitosan in the new method were significantly higher than that were obtained in the traditional acetic acid extraction method. As a reference to pure chitosan, SAP from shellfish chitosan, was produced by conversion of this biopolymer into water soluble carboxymethyl chitosan (CMCS), gelation of CMCS with glutaraldehyde in aqueous solutions (1-2%), and drying the resultant gel. Effects of carboxymethylation, gelation and drying conditions on the water binding capacity (WBC) of the final products, were investigated. Finally, choosing the best condition, a biological superabsorbent was produced from zygomycetes chitosan. The CMCS-based SAPs were able to absorb up to 200 g water/g SAP. The WBC of the best SAP in urine and saline solutions was 40 and 32 g/g respectively, which is comparable to the WBC of commercially acceptable SAPs under identical conditions (34-57 and 30-37 g/g respectively).

Disputationen sker fredagen den 1 oktober kl. 10.00 i KA-salen, Kemigården 4, Chalmers, Göteborg

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9

Amnuaykanjanasin, Alongkorn. "A class V chitin synthase and its roles in cell wall integrity in the fungus Colletotrichum graminicola /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.

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De, Almeida Nogueira Maria Filomena. "Candida albicans signalling pathways and the regulation of cell wall biosynthesis under stress." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=203748.

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The main aim of this project was to study Candida albicans cell wall biosynthesis in response to stress. The role of the MAPK, Ca2+/calcineurin and cAMP/PKA signal transduction pathways in regulating the C. albicans cell wall stress response was investigated. A library of mutants lacking receptors, signalling elements and transcription factors were screened for alterations in their ability to respond to a range of cell wall stressing agents, including CaCl2, Calcofluor White and caspofungin. Pretreatment of wild-type cells with CaCl2 and CFW, activates the Ca2+/calcineurin and PKC pathways, leading to an increase in chitin content, and reduced susceptibility to caspofungin. Although elevation of cell wall chitin content often resulted in decreased sensitivity to caspofungin, I show here that some strains with increased chitin levels remained sensitive to caspofungin. The results show that elevation of chitin is a common property of a range of mutants that are affected in coordinating cell wall stress pathways, but that multiple mechanisms are likely to operate in maintaining the robustness of the C. albicans cell wall. Some of the mutant strains of the MAPK, Ca2+/calcineurin and cAMP signalling pathways showed evidence of paradoxical growth, whereby less inhibition was achieved by higher concentrations of antifungal drug. The role of chitin-related genes and stress signalling pathways in regulating C. albicans paradoxical growth was also investigated. Based on these results, more detailed analyses were performed to investigate the correlations between sensitivity and resistance to caspofungin, in relation to paradoxical growth. The MAPK-Mkc1 and the calcineurin pathways played major roles in the paradoxical growth effect. There was a proportional relationship between echinocandin concentration and the chitin content of the cell wall although the chitin content did not continue to be upregulated by the highest echinocandin concentration. Different echinocandins, carbon source, cell morphology and medium composition influenced the extent of paradoxical growth effect. The existence of paradoxical growth in resistant strains such as Fks1 also highlights association of paradoxical growth with resistance mechanisms.
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Books on the topic "Chitin Fungal cell walls"

1

Fungal cell wall: Structure, synthesis, and assembly. Boca Raton: CRC Press, 1992.

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A, Gurevich G., and Fikhte B. A, eds. Mekhanicheskie svoĭstva mikrobnykh obolochek. Pushchino: Nauch. t͡sentr biologicheskikh issledovaniĭ AN SSSR, 1988.

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Ruiz-Herrera, José. Fungal cell wall: Structure, synthesis, and assembly. 2nd ed. Boca Raton, FL: CRC Press, 2012.

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NATO Advanced Research Workshop on Fungal Cell Wall and Immune Response (1990 Eloúnda, Greece). Fungal cell wall and immune response. Berlin: Springer-Verlag, 1991.

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Larsen, Michael J. Mycofibrillar cell wall extensions in the hyphal sheath of Postia placenta. Madison, Wis. (One Gifford Pinchot-Drive, Madison 53705-2398): U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, 1992.

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Biosintez uglevodnykh komponentov kletochnoĭ stenki drozhzheĭ. Pushchino: Nauch. t͡s︡entr biologicheskikh issledovaniĭ AN SSSR, 1988.

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Kasumov, Kh M. Molekuli͡a︡rnyĭ mekhanizm vzaimodeĭstvii͡a︡ polienovykh antibiotikov s lipidnymi membranami. Baku: "Ėlm", 1986.

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The Fungal Cell Wall. Nova Science Pub Inc, 2013.

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1954-, Kuhn P. J., ed. Biochemistry of cell walls and membranes in fungi. Berlin: Springer-Verlag, 1990.

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Nava, Mozes, ed. Microbial cell surface analysis: Structural and physicochemical methods. New York: VCH, 1991.

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Book chapters on the topic "Chitin Fungal cell walls"

1

Beauvais, A., and J. P. Latgé. "Modulation of Glucan and Chitin Synthesis." In Fungal Cell Wall and Immune Response, 97–110. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76074-7_8.

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Gooday, G. W. "Inhibition of Chitin Metabolism." In Biochemistry of Cell Walls and Membranes in Fungi, 61–79. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74215-6_5.

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Cabib, E., S. J. Silverman, A. Sburlati, and M. L. Slater. "Chitin Synthesis in Yeast (Saccharomyces cerevisiae)." In Biochemistry of Cell Walls and Membranes in Fungi, 31–41. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74215-6_3.

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Cabib, E., S. J. Silverman, and J. A. Shaw. "Chitin Synthetases 1 and 2 from Yeast, Two Isoenzymes with Different Functions." In Fungal Cell Wall and Immune Response, 39–48. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76074-7_4.

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Brown, Hannah E., Shannon K. Esher, and J. Andrew Alspaugh. "Chitin: A “Hidden Figure” in the Fungal Cell Wall." In Current Topics in Microbiology and Immunology, 83–111. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/82_2019_184.

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Kubicek, Christian P., Verena Seidl, and Bernhard Seiboth. "Plant Cell Wall and Chitin Degradation." In Cellular and Molecular Biology of Filamentous Fungi, 396–413. Washington, DC, USA: ASM Press, 2014. http://dx.doi.org/10.1128/9781555816636.ch27.

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Peberdy, J. F. "Fungal Cell Walls — A Review." In Biochemistry of Cell Walls and Membranes in Fungi, 5–30. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74215-6_2.

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Roncero, Cesar, Alberto Sanchez-Diaz, and M. Henar Valdivieso. "9 Chitin Synthesis and Fungal Cell Morphogenesis." In Biochemistry and Molecular Biology, 167–90. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-27790-5_9.

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Benhamou, N. "Electron Microscopic Localization of Polysaccharides in Fungal Cell Walls." In Fungal Cell Wall and Immune Response, 205–18. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76074-7_16.

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Wessels, J. G. H., P. C. Mol, J. H. Sietsma, and C. A. Vermeulen. "Wall Structure, Wall Growth, and Fungal Cell Morphogenesis." In Biochemistry of Cell Walls and Membranes in Fungi, 81–95. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74215-6_6.

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