Systemic Induction of the Defensin and Phytoalexin Pisatin Pathways in Pea (Pisum sativum) against Aphanomyces euteiches by Acetylated and Nonacetylated Oligogalacturonides.

Oligogalacturonides (OGs) are known for their powerful ability to stimulate the plant immune system but little is known about their mode of action in pea (). In the present study, we investigated the elicitor activity of two fractions of OGs, with polymerization degrees (DPs) of 2-25, in pea against . One fraction was nonacetylated (OGs - Ac) whereas the second one was 30% acetylated (OGs + Ac).

Oligogalacturonic Acid Inhibits Vascular Calcification by Two Mechanisms: Inhibition of Vascular Smooth Muscle Cell Osteogenic Conversion and Interaction With Collagen.

Objective: Cardiovascular diseases constitute the leading cause of mortality worldwide. Calcification of the vessel wall is associated with cardiovascular morbidity and mortality in patients having many diseases, including diabetes mellitus, atherosclerosis, and chronic kidney disease. Vascular calcification is actively regulated by inductive and inhibitory mechanisms (including vascular smooth muscle cell adaptation) and results from an active osteogenic process.

Highly dynamic genomic loci drive the synthesis of two types of capsular or secreted polysaccharides within the Mycoplasma mycoides cluster.

Mycoplasmas of the Mycoplasma mycoides cluster are all ruminant pathogens. Mycoplasma mycoides subsp. mycoides is responsible for contagious bovine pleuropneumonia and is known to produce capsular polysaccharide (CPS) and exopolysaccharide (EPS).

Osmotic stress alters the balance between organic and inorganic solutes in flax (Linum usitatissimum).

Flax (Linum usitatissimum) is grown for its oil and its fiber. This crop, cultivated in temperate regions, has seen a renewed interest due to the presence of abundant molecules of interest for many applications. Little information is available about the behavior of flax during osmotic stress; yet this is considered a major stress that causes significant yield losses in most crops.

Characterization of free exopolysaccharides secreted by Mycoplasma mycoides subsp. mycoides.

Contagious bovine pleuropneumonia is a severe respiratory disease of cattle that is caused by a bacterium of the Mycoplasma genus, namely Mycoplasma mycoides subsp. mycoides (Mmm). In the absence of classical virulence determinants, the pathogenicity of Mmm is thought to rely on intrinsic metabolic functions and specific components of the outer cell surface.

Structural features and bioremediation activity of an exopolysaccharide produced by a strain of Enterobacter ludwigii isolated in the Chernobyl exclusion zone.

The bacterium Enterobacter ludwigii Ez-185-17, member of the family Enterobacteriaceae, was isolated from the root nodules of plants harvested in the nuclear power region of Chernobyl. Under batch culture conditions, the bacteria produce a high-molecular-mass exopolysaccharide (EPS). After purification, the structure of this EPS was determined using a combinatory approach including monosaccharide composition (GC-FID, HPAEC-PAD) and branching structure determination (GC-MS), as well as 1D/2D NMR ((1)H, (13)C) and ESI-MS (HR, MS/MS) studies of oligosaccharides obtained from mild acid hydrolysis.

Trehalose determination in linseed subjected to osmotic stress. HPAEC-PAD analysis: an inappropriate method.

Trehalose is a non-reducing disaccharide involved in stress tolerance in plants. To understand better the role of trehalose in the osmotic stress response in linseed (Linum usitatissimum), trehalose content in leaves was studied. First, the method commonly used for sugar determination, high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), gave unsatisfactory results and the separation efficiency could not be improved by varying the elution conditions.

Synthesis of new glycosaminoglycans-like families by regioselective oxidation followed by sulphation of glucoglucuronan from Rhizobium sp. T1.

Glycosaminoglycan-like polysaccharides were prepared from Rhizobium sp. T1 polysaccharide using the TEMPO (nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl radical) mediated oxidation. The structure of this new polyglucuronic acid sodium salt was analyzed by (13)C NMR spectra and HPAEC-PAD chromatography.

Evaluation of antioxidant capacity of ulvan-like polymer obtained by regioselective oxidation of gellan exopolysaccharide.

Gellan is an exopolysaccharide produced in high yield by the non-pathogenic bacterium Sphingomonas elodea ATCC 31461. In this study, four carboxylated derivatives of gellan (OG-1, OG-2, OG-3 and OG-4) with different uronics acid content were prepared using the TEMPO (nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl radical) mediated oxidation and their antioxidant activities were investigated including scavenging activity of hydroxyl, superoxide anion and 1,1-diphenyl-2-picryl-hydrazyl radicals. The results of chemical analysis and (13)C NMR spectrums indicated that the modification was successful.

Distinct defenses induced in wheat against powdery mildew by acetylated and nonacetylated oligogalacturonides.

In wheat, little is known about disease resistance inducers and, more specifically, about the biological activities from those derived from endogenous elicitors, such as oligogalacturonides (OGAs). Therefore, we tested the ability of two fractions of OGAs, with polymerization degrees (DPs) of 2-25, to induce resistance to Blumeria graminis f. sp.

Exopolysaccharide production by nitrogen-fixing bacteria within nodules of Medicago plants exposed to chronic radiation in the Chernobyl exclusion zone.

Nitrogen-fixing bacteria isolated from root nodules of Medicago plants growing in the 10 km zone around the Chernobyl nuclear power plant were screened for the production of new water-soluble acidic exopolysaccharides (EPSs). The different strains belonged to the Enteriobacteriaceae family (Enterobacter ludwigii, Raoultella terrigena, Klebsiella oxytoca), except for one which belonged to the Rhizobiaceae family (Sinorhizobium meliloti). All of the bacteria produced highly viscous EPS with an average molecular weight comprised between 1 x 10(6) and 3 x 10(6) Da.

Production of arabinoxylan-oligosaccharides from flaxseed (Linum usitatissimum).

Flaxseed mucilage from Linum usitatissimum L. species was constituted by arabinoxylan (about 75%) and pectin (about 25%). A new procedure was developed to obtain only arabinoxylans which implicated treatment of the pectin fraction by enzymatic hydrolysis with pectinase.

Oligogalacturonic acid inhibit bone resorption and collagen degradation through its interaction with type I collagen.

In this study, we showed that oligogalacturonic acid (OGA) purified from flax pectin inhibit in vitro osteoclastic bone resorption in a dose-dependent manner. The OGA inhibitory effect was neither linked to an effect on osteoclast apoptosis, nor to an inhibition of cathepsin K activity. By means of an in vitro collagen degradation assay we demonstrated that OGA prevented triple-helical type I collagen cleavage by cathepsin K in a dose and chain length dependent manner.

Improved isolation of glucuronan from algae and the production of glucuronic acid oligosaccharides using a glucuronan lyase.

A new source for the production of bioactive glucuronic acid oligosaccharides (GlcUAOs) from the depolymerization of green seaweed Ulva lactuca glucuronan (Algal glucuronan) has been investigated. Algal glucuronan purification was optimized by the acidic precipitation method which allowed us to separate the polysaccharide mixture extracted from the cell wall of Ulvalactuca using hot water containing sodium oxalate. A series of the GlcUAOs were obtained by enzyme degradation of algal glucuronan with a glucuronan lyase (GL) isolated from Trichoderma strain.

Oligosaccharides from land plants and algae: production and applications in therapeutics and biotechnology.

Since the past decades, oligosaccharides are considered for their potential biological activities. To exploit them, it was essential to obtain pure molecules in large amounts. Several strategies were developed to produce specific sugar sequences with specific substitution patterns from land plants and algae polysaccharides.

Inhibition of Blumeria graminis f. sp. tritici Germination and Partial Enhancement of Wheat Defenses by Milsana.

ABSTRACT The prophylactic efficiency of Milsana against powdery mildew was evaluated on wheat (Triticum aestivum). A single short spraying on 10-day-old plantlets reduced the infection level by 85% and two long sprayings led to the total restriction of the disease. Although microscopic studies showed that Milsana treatments enhance hydrogen peroxide accumulation at the fungal penetration site, biochemical analysis did not allow us to correlate this accumulation with the activation of several enzyme activities involved in active oxygen species (AOS) metabolism.

Efficient purification of small unsaturated oligoglucuronides by reversed-phase chromatography.

Ion-exchange chromatography has been applied to purification of unsaturated oligoglucuronans. After an isocratic elution on a strong anion-exchange column, the collected fractions were desalted by low pressure size exclusion chromatography. However, this efficient separation was limited by the time required to desalt.

Production of oligoglucuronans by enzymatic depolymerization of nascent glucuronan.

An original bioreactor process for production of oligoglucuronans was developed using the Sinorhizobium meliloti M5N1CS strain that produces glucuronan. This anionic homopolysaccharide was composed of beta-D-(1,4)-glucopyranosyluronic residues variably O-acetylated at C-3 and/or C-2 positions according to culture conditions. It was depolymerized during its biosynthesis by addition of a fungal glucuronan lyase activity in broths.

Controlled sulfatation of natural anionic bacterial polysaccharides can yield agents with specific regenerating activity in vivo.

The regenerating activities of chemically modified anionic bacterial polysaccharides by O-sulfonation were investigated using a in vivo model of rat injured muscle regeneration. Glucuronan (GA), a linear homopolysaccharide of -->4)-beta-D-GlcpA-(1--> residues partially acetylated at the C-3 and/or the C-2 position, and glucoglucuronan (GGA), a linear heteropolysaccharide of -->3)-beta-D-GlcpA-(1-->4)-beta-D-Glcp-(1--> residues were sulfated. SO3-DMF sulfatation complex provided polysaccharides with different sulfur contents, however, a depolymerization occurred because we did not use large excess of pyridine to obtain pure modified polysaccharides.

Rapid quantification of O-acetyl and O-methyl residues in pectin extracts.

A rapid method for the determination of the degrees of methylation (DM) and acetylation (DA) of pectins was developed. The polymer substitution degree as determined after saponification at 80 degrees C with NaOD during 1H NMR analysis. Under alkaline conditions, the cleavage of O-acetyl and O-methyl linkages allows the detection and the integration of the H-4 signal from galacturonic acid residues in the newly unesterified pectins.

Studies of low molecular weight samples of glucuronans with various acetylation degree.

Partially acetylated, high molecular weight glucuronans were produced by a Sinorhizobium meliloti mutant strain. Two native glucuronan samples with various degrees of acetylation were sonicated to obtain lower molecular weight samples and with low viscosity suitable for chemical modification and (13)C NMR experiments. The average degree of substitution (DS) of the polymer was estimated by Fourier transform infrared (FTIR) and NMR.