Search results for "Arid"
showing 10 items of 1382 documents
Extraction, Structural Characterisation, and Immunomodulatory Properties of Edible Amanita hemibapha subspecies javanica (Corner and Bas) Mucilage Po…
2021
This research aimed to extract mucilage polysaccharides (MP) from Amanita hemibapha subspecies javanica (Corner and Bas), and further fractionate them using anion-exchange chromatography, yielding two fractions (MPF1 and MPF2). The crude extract, and fractions mainly consisted of carbohydrates (83.5–93.2%) with minor amounts of proteins (5.40–7.20%), and sulphates (1.40–9.30%). Determination of the monosaccharide composition revealed that glucose was the major unit, followed by galactose, mannose, rhamnose, and arabinose. The average molecular weight (MW) of the crude extract and fractions was in the range 104.0–479.4 × 103 g/mol. Interestingly, the crude extract, and fractions did not caus…
Phylogenetic Distribution of Polysaccharide-Degrading Enzymes in Marine Bacteria
2021
Deconstruction is an essential step of conversion of polysaccharides, and polysaccharide-degrading enzymes play a key role in this process. Although there is recent progress in the identification of these enzymes, the diversity and phylogenetic distribution of these enzymes in marine microorganisms remain largely unknown, hindering our understanding of the ecological roles of marine microorganisms in the ocean carbon cycle. Here, we studied the phylogenetic distribution of nine types of polysaccharide-degrading enzymes in marine bacterial genomes. First, we manually compiled a reference sequence database containing 961 experimentally verified enzymes. With this reference database, we annota…
Different Modes of Regulation of the Expression of Dextransucrase in Leuconostoc lactis AV1n and Lactobacillus sakei MN1
2019
Leuconostoc lactis AV1 strain isolated from a Tunisian avocado was characterized as a dextran producer. The promoter PdsrLL and the dsrLL gene encoding the DsrLL dextransucrase responsible for the dextran synthesis were transcriptionally fused to the mCherry coding gene generating the pRCR20 plasmid. Upon plasmid transfer, both AV1n and the dextran non-producing Leuconostoc mesenteroides CM70 became red due to expression of the mCherry from the PdsrLL-dsr-mrfp transcriptional fusion. Characterization of the polymers present in cultures supernatants revealed that the DsrLL encoded from pRCR20 in the recombinant bacteria was able to synthesize dextran. The production of dextran by the DsrLL i…
Sulphation and Hydrolysis Improvements of Bioactivities, and Immuno-Modulatory Properties of Edible Amanita hemibapha Subspecies javanica (Corner and…
2021
In this study, the mucilage polysaccharide (MP) from Amanita hemibapha subspecies javanica was prepared by hot water extraction and ethanol precipitation and then fractionated using anion-exchange chromatography equipped with a DEAE Sepharose fast flow column. The most immune-enhancing polysaccharide fraction 2 (MPF2) was subjected to a structural modification such as hydrolysis or over-sulphation. The sulphate and molecular weight (Mw) of over-sulphated (OS1-3) and hydrolysed (HS1-3) derivatives of MPF2 differed between 9.85% and 14.2% and 32.8 and 88.1 × 103 g/mol, respectively. Further, the immune-enhancing properties of MPF2 and its derivatives were tested on RAW264.7 and NK cells throu…
Substitution of carcinogenic solvent dichloromethane for the extraction of volatile compounds in a fat-free model food system
2016
International audience; Dichloromethane is known as a very efficient solvent, but, as other halogenated solvents, is recognized as a hazardous product (CMR substance). The objective of the present work is to propose substitution solvent for the extraction of volatile compounds. The most important physico-chemical parameters in the choice of an appropriate extraction solvent of volatile compounds are reviewed. Various solvents are selected on this basis and on their hazard characteristics. The selected solvents, safer than dichloromethane, are compared using the extraction efficiency of volatile compounds from a model food product able to interact with volatile compounds. Volatile compounds …
Atmospheric Mineral Dust - Properties and Source Markers
1989
Mineral dust particles from arid regions of the earth are a substantial fraction of the atmospheric aerosol. Due to long range transport mineral dust is found in all types of airmasses and thus in remote regions too. Physical and chemical properties allow to distinguish mineral aerosols easily from other types of aerosols. Many characteristic features are similar to those of global average crust. Only major deviations from this mean composition are reflected by the mineral aerosol composition. In order to derive source characteristic features from mineral dust samples advanced statistical methods coupled with various analytical tools from the mineralogy and chemistrymust be applied.
DINAMICA DEI NITRATI E MINERALIZZAZIONE DEL CARBONIO IN UN SUOLO A VIGNETO IN AMBIENTE SEMIARIDO
2013
La gestione agronomica del vigneto in ambiente semiarido è spesso caratterizzata sia dalle frequenti lavorazioni del suolo che dall’apporto di fertilizzanti inorganici, in particolare azotati. Tale gestione, congiuntamente alle caratteristiche pedo-climatiche tipiche dell’ambiente semiarido, causa spesso un depauperamento del contenuto in sostanza organica del suolo e, dall’altro lato, incrementa il rischio di dilavamento di nitrati dal suolo. Al fine di controbilanciare tali effetti indesiderati, sono state introdotte nella gestione del suolo a vigneto tecniche di agricoltura conservativa, quali l’introduzione delle cover crops e l’interramento, previa trinciatura, dei residui di potatura,…
Miti mediterranei: un viaggio millenario
2020
Ha osservato Sebastiano Tusa: «Al di là delle immense e svariate risorse materiali che il mare ha offerto ed offre all’uomo, ve ne sono altre che attengono alla sfera sovrastrutturale che hanno nei millenni rifornito ed animato l’immensa enciclopedia dei miti, delle leggende e dei culti ad esso ispirati o, comunque, connessi». Distesa senza confini e abisso insondabile, il mare, con le sue repentine mutazioni di stato, le sue furiose tempeste e le sue mortifere bonacce, si è sempre imposto a chi lo solcava per raggiungere altri luoghi o per ricavarne da vivere come spazio del pericolo e del mistero, generando e sostenendo un ampio e polimorfo immaginario e divenendo attore e scenario al con…
Size- and Structure-Selective Noncovalent Recognition of Saccharides by Tetraethyl and Tetraphenyl Resorcinarenes in the Gas Phase
2008
The noncovalent complexation of tetraethyl and tetraphenyl resorcinarenes with mono-, di-, and oligosaccharides was studied with negative-polarization electrospray ionization quadrupole ion trap and electrospray ionization Fourier-transform ion cyclotron resonance mass-spectrometric analysis. The saccharides formed 1:1 complexes with deprotonated resorcinarenes, which exhibited clear size and structure selectivity in their complexation. In the case of the monosaccharides, hexoses formed much more abundant and kinetically stable complexes than pentoses or deoxyhexoses. A comparison of the mono-, di-, and oligosaccharides revealed that both the relative abundance and stability of the complexe…
Picomolar inhibition of cholera toxin by a pentavalent ganglioside GM1os-calix[5]arene
2013
Cholera toxin (CT), the causative agent of cholera, displays a pentavalent binding domain that targets the oligosaccharide of ganglioside GM1 (GM1os) on the periphery of human abdominal epithelial cells. Here, we report the first GM1os-based CT inhibitor that matches the valency of the CT binding domain (CTB). This pentavalent inhibitor contains five GM1os moieties linked to a calix[5]arene scaffold. When evaluated by an inhibition assay, it achieved a picomolar inhibition potency (IC50 = 450 pM) for CTB. This represents a significant multivalency effect, with a relative inhibitory potency of 100000 compared to a monovalent GM1os derivative, making GM1os-calix[5]arene one of the most potent…