Melanin deposition in the hyphae of a species of Phomopsis

1975 ◽  
Vol 21 (4) ◽  
pp. 442-452 ◽  
Author(s):  
D. H. Ellis ◽  
D. A. Griffiths
Keyword(s):  
Cell Wall ◽  
Surface Analysis ◽  
Cell Walls ◽  
Lytic Enzymes ◽  
Fungal Cell ◽  
Ionizing Radiations ◽  
Dopa Melanin ◽  
Fungal Cell Walls ◽  
Cellular Organelles

Hyaline hyphae of Phomopsis become pigmented when exposed to short periods of light. Pigment was deposited in the form of melanin granules both within the cell wall and within mucilaginous excrescences that were developed irregularly over the hyphal surface. Analysis of the pigment showed it to have properties similar to that of "Dopa" melanin and to pigments previously isolated from fungal cell walls. Lysis of both hyaline and pigmented hyphal walls by means of lytic enzymes was minimal. It is suggested that the major role of melanin in this fungus is the protection of cellular organelles from harmful ionizing radiations.

scholarly journals Screening and Antifungal Activity of a β-Carboline Derivative against Cryptococcus neoformans and C. gattii

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Kátia Santana Cruz ◽  
Emerson Silva Lima ◽  
Marcia de Jesus Amazonas da Silva ◽  
Erica Simplício de Souza ◽  
Andreia Montoia ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Antifungal Activity ◽  
Cryptococcus Neoformans ◽  
Active Compound ◽  
Cell Walls ◽  
Human Fibroblasts ◽  
Lead Compound ◽  
Fungal Cell ◽  
Fungal Cell Walls

Background. Cryptococcosis is a fungal disease of bad prognosis due to its pathogenicity and the toxicity of the drugs used for its treatment. The aim of this study was to investigate the medicinal potential of carbazole and β-carboline alkaloids and derivatives against Cryptococcus neoformans and C. gattii. Methods. MICs were established in accordance with the recommendations of the Clinical and Laboratory Standards Institute for alkaloids and derivatives against C. neoformans and C. gattii genotypes VNI and VGI, respectively. A single active compound was further evaluated against C. neoformans genotypes VNII, VNIII, and VNIV, C. gattii genotypes VGI, VGIII, and VGIV, Candida albicans ATCC 36232, for cytotoxicity against the MRC-5 lineage of human fibroblasts and for effects on fungal cells (cell wall, ergosterol, and leakage of nucleic acids). Results. Screening of 11 compounds revealed 8-nitroharmane as a significant inhibitor (MIC 40 μg/mL) of several C. neoformans and C. gattii genotypes. It was not toxic to fibroblasts (IC50 > 50 µg/mL) nor did it alter fungal cell walls or the concentration of ergosterol in C. albicans or C. neoformans. It increased leakage of substances that absorb at 260 nm. Conclusions. The synthetic β-carboline 8-nitroharmane significantly inhibits pathogenic Cryptococcus species and is interesting as a lead compound towards new therapy for Cryptococcus infections.

scholarly journals Localization of chitin in algal and fungal cell walls by light and electron microscopy.

1978 ◽  
Vol 26 (10) ◽  
pp. 782-791 ◽  
Author(s):  
N L Pearlmutter ◽  
C A Lembi
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Acetic Acid ◽  
Electron Microscope ◽  
Cell Walls ◽  
Potassium Hydroxide ◽  
Light And Electron Microscopy ◽  
Fungal Cell ◽  
Blastocladiella Emersonii ◽  
Fungal Cell Walls

Chitin was visualized in cell walls after hydrolysis with potassium hydroxide and subsequent postfixation of the deacetylated polysaccharide (chitosan) in OsO4. Areas of chitin deposition appeared dark borwn by light microscopy and electron dense in the electron microscope. With this method, the presence of chitin was demonstrated in the cell walls of the green alga Pithophora oedogonia (Montagne) Wittrock and two fungi, Ceratocystis ulmi Buism. (C. Moreau) and Blastocladiella emersonii Cantino and Hyatt. Most of the chitin in P. oedogonia ws found in the crosswall disk and small amounts occurred in the outer longitudinal walls. The septal disk of C. ulmi also contained chitin, but significant amounts were present in the inner and outer regions of longitudinal walls as well. Chitin was present throughout the walls of B. emersonii. Small amounts of chitin were not easily demonstrated by this technique, but removal of chitosan by exposure to dilute acetic acid before osmium fixation disrupted cell wall integrity, suggesting that small amounts of the structural polysaccharide had been removed.

scholarly journals Chitinases Are Essential for Sexual Development but Not Vegetative Growth in Cryptococcus neoformans

2009 ◽  
Vol 8 (11) ◽  
pp. 1692-1705 ◽  
Author(s):  
Lorina G. Baker ◽  
Charles A. Specht ◽  
Jennifer K. Lodge
Keyword(s):  
Cell Wall ◽  
Sexual Reproduction ◽  
Cryptococcus Neoformans ◽  
Vegetative Growth ◽  
Cell Walls ◽  
Cell Structure ◽  
Complex Structure ◽  
Hydrolytic Enzymes ◽  
Fungal Cell ◽  
Fungal Cell Walls

ABSTRACT Cryptococcus neoformans is an opportunistic pathogen that mainly infects immunocompromised individuals. The fungal cell wall of C. neoformans is an excellent target for antifungal therapies since it is an essential organelle that provides cell structure and integrity. Importantly, it is needed for localization or attachment of known virulence factors, including melanin, phospholipase, and the polysaccharide capsule. The polysaccharide fraction of the cryptococcal cell wall is a complex structure composed of chitin, chitosan, and glucans. Chitin is an indispensable component of many fungal cell walls that contributes significantly to cell wall strength and integrity. Fungal cell walls are very dynamic, constantly changing during cell division and morphogenesis. Hydrolytic enzymes, such as chitinases, have been implicated in the maintenance of cell wall plasticity and separation of the mother and daughter cells at the bud neck during vegetative growth in yeast. In C. neoformans we identified four predicted endochitinases, CHI2, CHI21, CHI22, and CHI4, and a predicted exochitinase, hexosaminidase, HEX1. Enzymatic analysis indicated that Chi2, Chi22, and Hex1 actively degraded chitinoligomeric substrates. Chi2 and Hex1 activity was associated mostly with the cellular fraction, and Chi22 activity was more prominent in the supernatant. The enzymatic activity of Hex1 increased when grown in media containing only N-acetylglucosamine as a carbon source, suggesting that its activity may be inducible by chitin degradation products. Using a quadruple endochitinase deletion strain, we determined that the endochitinases do not affect the growth or morphology of C. neoformans during asexual reproduction. However, mating assays indicated that Chi2, Chi21, and Chi4 are each involved in sexual reproduction. In summary, the endochitinases were found to be dispensable for routine vegetative growth but not sexual reproduction.

scholarly journals A Report on Fungal (1→3)-α-d-glucans: Properties, Functions and Application

Molecules ◽  
2019 ◽  
Vol 24 (21) ◽  
pp. 3972 ◽  
Author(s):  
Katarzyna Złotko ◽  
Adrian Wiater ◽  
Adam Waśko ◽  
Małgorzata Pleszczyńska ◽  
Roman Paduch ◽  
...  
Keyword(s):  
Cell Wall ◽  
Immune System ◽  
Physicochemical Properties ◽  
Aspergillus Fumigatus ◽  
Cell Walls ◽  
Practical Application ◽  
Fungal Cell ◽  
Plant Infection ◽  
Potential Use

The cell walls of fungi are composed of glycoproteins, chitin, and α- and β-glucans. Although there are many reports on β-glucans, α-glucan polysaccharides are not yet fully understood. This review characterizes the physicochemical properties and functions of (1→3)-α-d-glucans. Particular attention has been paid to practical application and the effect of glucans in various respects, taking into account unfavourable effects and potential use. The role of α-glucans in plant infection has been proven, and collected facts have confirmed the characteristics of Aspergillus fumigatus infection associated with the presence of glucan in fungal cell wall. Like β-glucans, there are now evidence that α-glucans can also stimulate the immune system. Moreover, α-d-glucans have the ability to induce mutanases and can thus decompose plaque.

scholarly journals An Assessment of Infrared Spectra as Indicators of Fungal Cell Wall Composition

1970 ◽  
Vol 23 (2) ◽  
pp. 345 ◽  
Author(s):  
A JMichell ◽  
G Sourfield
Keyword(s):  
Cell Wall ◽  
Infrared Spectroscopy ◽  
Infrared Spectra ◽  
Cell Walls ◽  
Cell Wall Composition ◽  
Fungal Cell Wall ◽  
Fungal Cell ◽  
Chemical Treatments ◽  
Wall Components ◽  
Fungal Cell Walls

Infrared spectroscopy is assessed as a technique for identifying polymers derived from fungal cell walls, both as isolated materials and in mixtures with one another. The technique is then applied to a study of the composition of fungal cell walls and the conclusion reached that infrared spectra provide a rapid and valuable indication of the major components of such walls. They can also be used to follow the effect of chemical treatments designed to separate major wall components.

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.

Breakpoint: Cell Wall and Glycoproteins and their Crucial Role in the Phytopathogenic Fungi Infection

2020 ◽  
Vol 21 (3) ◽  
pp. 227-244 ◽  
Author(s):  
Verónica Plaza ◽  
Evelyn Silva-Moreno ◽  
Luis Castillo
Keyword(s):  
Cell Wall ◽  
Signaling Pathways ◽  
Crucial Role ◽  
Intracellular Signaling ◽  
Cell Walls ◽  
Wall Stress ◽  
Appressorium Formation ◽  
Cell Wall Degrading Enzymes ◽  
Lytic Enzymes ◽  
Fungal Cell

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.

scholarly journals Protein Glycosylation inAspergillus fumigatusIs Essential for Cell Wall Synthesis and Serves as a Promising Model of Multicellular Eukaryotic Development

2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Cheng Jin
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Posttranslational Modification ◽  
Mammalian Cells ◽  
Protein Glycosylation ◽  
Cell Wall Synthesis ◽  
Fungal Cell ◽  
Multiple Functions ◽  
Significant Attention

Glycosylation is a conserved posttranslational modification that is found in all eukaryotes, which helps generate proteins with multiple functions. Our knowledge of glycosylation mainly comes from the investigation of the yeastSaccharomyces cerevisiaeand mammalian cells. However, during the last decade, glycosylation in the human pathogenic moldAspergillus fumigatushas drawn significant attention. It has been revealed that glycosylation inA. fumigatusis crucial for its growth, cell wall synthesis, and development and that the process is more complicated than that found in the budding yeastS. cerevisiae. The present paper implies that the investigation of glycosylation inA. fumigatusis not only vital for elucidating the mechanism of fungal cell wall synthesis, which will benefit the design of new antifungal therapies, but also helps to understand the role of protein glycosylation in the development of multicellular eukaryotes. This paper describes the advances in functional analysis of protein glycosylation inA. fumigatus.

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