Search results for "Chitin"
showing 10 items of 69 documents
Identification et caractérisation du récepteur à la flagelline (VvFLS2) et recherche du récepteur aux chito-oligosaccharides chez la vigne
2014
Pattern-recognition receptors (PRRs) play a key role in plant immunity by assuring recognition of microbe-associated molecular patterns (MAMPs), signature of microbial presence. MAMP perception constitutes the first layer of pathogen detection and activates defense mechanisms that aim to block the intruder. This study brings an insight into how grapevine (Vitis vinifera) perceives two MAMPs: the flagellin-derived flg22 peptide and chitin, which are conserved motifs occurring over the whole bacterial and fungal classes, respectively. This study analyzed MAMP-triggered early signaling events, defense gene expression and also the efficiency of elicited defense against gray mold and downy milde…
Comparative analysis of PR gene expression in tomato inoculated with virulent Fusarium oxysporum f. sp. lycopersici and the biocontrol strain F. oxys…
2008
Non-pathogenic strains of Fusarium oxysporum have the capacity to protect plants against wilt induced by pathogenic strains of F. oxysporum. Among the mechanisms involved in this protection, induced systemic resistance has been demonstrated by using a split-root method. The aim of this study was to follow the accumulation kinetics of transcripts encoding 5 PR proteins in roots and leaves of tomato inoculated with a pathogenic or a protective strain in comparison to non-inoculated control. Moreover quantification of transcripts was assessed by real-time RT-PCR in cell cultures inoculated with the pathogenic or the protective strain. Results showed a lower expression of PR encoding genes in t…
Isolation and characterization of yeast monomorphic mutants of Candida albicans.
1994
A method was devised for the isolation of yeast monomorphic (LEV) mutants of Candida albicans. By this procedure, about 20 stable yeast-like mutants were isolated after mutagenesis with ethyl methane sulfonate. The growth rate of the mutants in different carbon sources, both fermentable and not, was indistinguishable from that of the parental strain, but they were unable to grow as mycelial forms after application of any of the common effective inducers, i.e., heat shock, pH alterations, proline addition, or use of GlcNAc as the carbon source. Studies performed with one selected strain demonstrated that it had severe alterations in the chemical composition of the cell wall, mainly in the le…
Role of Surface Chemistry in the Superhydrophobicity of the Springtail Orchesella cincta (Insecta:Collembola)
2020
Collembola are ancient arthropods living in soil with extensive exposure to dirt, bacteria, and fungi. To protect from the harsh environmental conditions and to retain a layer of air for breathing when submerged in water, they have evolved a superhydrophobic, liquid-repelling cuticle surface. The nonfouling and self-cleaning properties of springtail cuticle make it an interesting target of biomimetic materials design. Recent research has mainly focused on the intricate microstructures at the cuticle surface. Here we study the role of the cuticle chemistry for the Collembola species Orchesella cincta (Collembola, Entomobryidae). O. cincta uses a relatively simple cuticle structure with prima…
Nautilin-63, a novel acidic glycoprotein from the shell nacre of Nautilus macromphalus
2011
In molluscs, and more generally in metazoan organisms, the production of a calcified skeleton is a complex molecular process that is regulated by the secretion of an extracellular organic matrix. This matrix constitutes a cohesive and functional macromolecular assemblage, containing mainly proteins, glycoproteins and polysaccharides that, together, control the biomineral formation. These macromolecules interact with the extruded precursor mineral ions, mainly calcium and bicarbonate, to form complex organo-mineral composites of well-defined microstructures. For several reasons related to its remarkable mechanical properties and to its high value in jewelry, nacre is by far the most studied …
Regulation of chitin synthase activity inSaccharomyces cerevisiae: Effect of the inhibition of cell division and of synthesis of RNA and protein
1980
The effect of pronase and trypsin on the activation or deactivation (degradation?) of chitin synthase ofSaccharomyces cerevisiae occurs faster in membranous preparations than in toluene-treated cells. When the temperature is raised, the former preparation is deactivated earlier than the latter one. The activity found in growing cells is not modified after inhibition of protein synthesis by cycloheximide or amino acid starvation or by the inhibition of RNA synthesis. It was possible to activate the chitin synthase ofS. cerevisiae cdc 25 grown at 23°C by means of pronase, whereas trypsin had no effect. After the cells were grown at 37°C, chitin synthase could not be activated either with tryp…
Synthesis and Assembly of Wall Polymers on Regenerating Yeast Protoplasts
1983
Accumulation of chitin and glucan on S. cerevisiae and C. albicans protoplasts begins shortly after resuspension in the regeneration medium, and mannoprotein molecules also appear retained by the regenerating wall after 30–60 minutes in S. cerevisiae or after a longer lag period in C. albicans. Nevertheless, a considerable fraction of the synthesized mannoproteins, which in SDS-acrylamide gels exhibit a different pattern from that of wall mannoproteins of cells, are still released to the growth medium during at least eight hours. De novo synthesis of chitin synthase, but not of glucan synthase, is observed in S. cerevisiae from about 30 minutes after initiation of the regeneration process. …
Chitin: A Structural Biopolysaccharide
2009
Chitin is a naturally occurring fibre-forming polymer that plays a protective role in many lower eukaryotes similar to that of cellulose in plants. Chemically it is a long-chain unbranched polysaccharide made of N-acetylglucosamine residues; it is the second most abundant organic compound in nature, after cellulose. Taking into account the structural role played by chitin, its metabolism (synthesis and degradation) is essential for different morphogenetic events. Absent in vertebrates and plants, chitin represents a parasite-specific target for chemotherapeutic attack and also plays a role in host immune responses. Because of its abundance in nature and its properties, biotechnological appl…
Structural mannoproteins released by β-elimination fromCandida albicanscell walls
1994
Abstract Mild alkaline solutions (β-elimination), after removing the non-covalently bonded wall materials by hot SDS, released 13% and 26% of remaining wall proteins from mycelial and yeast cells of Candida albicans, respectively. When the β-elimination was carried out after digestion of the walls with chitinase, four-fold more proteinaceous materials were released from mycelium and a similar amount in yeast walls. The solubilized materials were shown to be highly polydisperse, and endo-glycosidase H reduced their polydispersity and molecular masses, revealing different electrophoretic patterns in yeast and mycelial cell walls. The solubilized mycelial proteins carried N-glycosidic sugar ch…
Evidence for the involvement of acylglycerides on chitin synthetase activity inCandida albicans
1991
The effect of a lipase activity (EC 3.1.1.3) on the chitin synthetase from Candida albicans has been studied, both on the active and the trypsin activated enzyme. Removal of fatty acids from acylglycerides by lipase has an inhibitory effect on the activity as well as on the ‘in vitro’ activation process by trypsin in the membrane-bound enzyme and in the chitosomes. This would indicate that an adequate lipid environment is required for both the activation process and proper function of the synthetase activity.