Search

Cell-associated lipopolysaccharides (LPS) were extracted by the phenol-chloroform-petroleum ether extraction method (PCP) from a nopaline strain of Agrobacterium vitis, purified by treatment with DNase/RNase, proteinase K and dialysis, characterized by polyacrylamide gel electrophoresis (SDS-PAGE), and bioassayed on grapevine shoot nodal segments. LPS preparation used for the experiments in planta was a mixture of rough-type LPS, obtained from precipitation with water after PCP-extraction, and some smooth- and rough-type LPS from the remaining phenol phase. Infiltration of an aqueous dispersion of the mixture in concentrations of 25-1000 µ g.ml-1 did not cause grapevine tissue necrosis, and callus formed within one month. When the LPS dispersions were infiltrated in the grapevine nodal segments, 24 h before challenge inoculation with A. vitis (5x102 cells per 5 µ l droplet), they prevented tumorgenesis and tissue necrosis; but, when the pathogen was inoculated at a higher concentration (5x105 cells per 5 CII droplet), these LS applications were active in protecting plant tissue from necrosis and did not prevent tumor induction. The potential role of LPS as candidate molecules in the protection of grapevine from A. vitis infection is discussed., VITIS - Journal of Grapevine Research, Vol. 39 No. 2 (2000): Vitis

Background: Increased neutrophilic infiltration of the airways is a key feature of acute asthma exacerbation, which may lead to prolonged hospital admissions and an enhanced rate of decline of lung function. The increase in asthma severity in this subpobulation of patients is thought to be partially mediated by neutrophil granulocytes secreting active proteases that degrade the surrounding extracellular matrix (ECM) and contribute to remodeling. We have reported an ECM fragment of the non-collagenous domain of collagen IV α3 (tumstatin) is significantly decreased in the airways of asthmatics (vs. non-asthmatics). This study sought to elucidate the effects of an active fragment of tumstatin (CP17), in the regulation of neutrophilic airway inflammation. Methods: Neutrophils were prepared from non-asthmatics via density gradient centrifugation (controlled for viability, activity and eosinophil contamination), before pre-incubation for 1h with CP17, scrambled peptide or vehicle and then exposure to a gradient of IL-8 in 3D μSlides (IBIDI, Germany). Time-lapse analysis of migration trajectories was performed using a specialized algorithm for cell detection. The Forward Migration Index (FMI) was calculated as published previously (IBIDI, Germany). The FMI (arbitrary units) represents the distance neutrophils migrated towards the IL-8 in parallel to the linear gradient. Mice were sensitized to OVA i.p. on day 1, 14 and 21 and challenged with 1% OVA aerosol on days 26, 27 and 28. Acute exacerbation was induced by instilling polyI:C i.t. 12h after last challenge. Prior to polyI:C challenge on days 27 and 28, 1 nmol CP17 or scrambled peptide was applied i.t.. BAL, lung histology (mucus producing cells (number PAS+ cells) and mRNA expression (CXCL1, CCL20) were analyzed. Results: In vitro: CP17 significantly reduced the mean FMI towards IL-8 from 0.27 (vehicle) to 0.12 and 0.10 respectively (5 and 50μM CP17, p

Ralstonia solanacearum is one of the most devastating phytopathogenic bacteria, in particular its race 3. This microorganism is the causal agent of destructive diseases of different crops including tomato and potato. An important aspect of the interaction between this pathogen, and the host and non-host plants was its biochemical and molecular basis. Thus, the lipopolysaccharides (LPS) were extracted from the R. solanacearum cell wall, purified, and the O-specific polysaccharide (OPS) was isolated and chemically characterized by compositional analyses and NMR spectroscopy. The OPS was constituted of two linear polymers of an approximate ratio of 3 : 1, both of which were built up from three rhamnose and one N-acetylglucosamine residues and differed only in the substitution of one rhamnose residue. The LPS inhibited the hypersensitivity reaction (HR) in non-host tobacco plants and induced localized resistance in host potato plants, both of which were pre-treated with the LPS before being inoculated with the pathogen. A cDNA-AFLP approach was used to study transcriptome variation during the resistant and susceptible interactions. This revealed the presence of metabolites specifically expressed in the S. commersonii-resistant genotypes, which could be involved in the plant–pathogen incompatible reaction. Furthermore, a specific EST collection of the Ralstonia–potato interaction has been built up.

Complex cell walls distinguish fungi from animals, and the roles of these walls include osmotic support, selective permeability and interaction with the environment. Fungal walls consist of covalently cross-linked complexes of polysaccharides (usually β-glucans and chitin) with glycoproteins. Several different polysaccharides are covalently cross-linked through glycosidic bonds. They are also cross-linked to two types of glycoproteins (CWPs). The Pir-CWPs are multiply cross-linked through ester bonds between deamidated glutamine residues and hydroxyl groups in the major β-(1→3)-glucan. The GPI(-t)-CWPs are defined by their linkage through transglycosylation of the truncated glycosylphosphatidylinositol (GPI) glycan to β-(1→6)-glucan. These GPI(-t)-CWPs are highly N- and O-mannosylated and may also have ester-glucan cross-links like the Pir-CWPs. GPI(-t)-CWPs have a common modular structure, with an N-terminal secretion signal, then a well-folded functional enzymatic or ligand binding domain, a middle region of tandem repeats, a C-terminal serine- and threonine-rich highly glycosylated "stalk" and a C-terminal GPI addition signal. Their functional regions include enzymes active in cell wall biogenesis and maintenance and nutrient acquisition; transport functions; and cell adhesion proteins that mediate interactions between fungal cells, pathogen and host and in biofilms. Therefore, fungal walls have functions including those assumed by membrane, cytoskeleton and extracellular matrix in other organisms.

Enterococci are a major cause of urinary tract infections, endocarditis and bacteriaemia. As many Streptococcus spp., Enterococcus faecalis expresses a complex carbohydrate known as the cell wall polysaccharide or type antigen. The cell wall polysaccharide is known to be involved in epithelial translocation,[for full text, please go to the a.m. URL], 10. Kongress für Infektionskrankheiten und Tropenmedizin (KIT 2010)