During Arabidopsis seed coat development, copious amounts of mucilage polysaccharides are produced in the epidermal cells. When hydrated on imbibition, these polysaccharides expand and are released ...to encapsulate the seed as a two-layered hydrogel. Polysaccharides are synthesized from UDP-sugars by glycosyltransferases (GTs) and several GTs, with differing activities, have been identified that contribute to mucilage polysaccharide synthesis. How these GTs orchestrate production of the complex polysaccharides found in mucilage remains to be determined. In this study, we generated a range of multiple GT mutants using either CRISPR/Cas9 targeted mutation or genetic crosses of existing T-DNA insertion mutants. Four traits for mucilage amounts or macromolecular properties were examined for four replicate seed lots from 31 different GT mutant combinations. This data provides a valuable resource for future genetic, biochemical, structural, and functional studies of the roles and properties of polysaccharides present in Arabidopsis mucilage and the relative contributions of different GTs to mucilage production.
The FT-IR fingerprint of wheat endosperm arabinoxylan (AX) was investigated using a set of polysaccharides exhibiting variation of their degree of substitution and xylo-oligosaccharides comprising ...xylose units mono- or disubstituted by arabinose residues. Substitution of the xylose backbone by arabinose side units was more particularly studied in the 1000−800 cm-1 spectral region, by taking advantage of second-derivative enhancement. The 920−1020 cm-1 spectral region revealed two absorption bands at 984 and 958 cm-1, the intensities of which varied according to the degree of substitution. Whereas the intensity of the band at 958 cm-1 increased with the degree of substitution, that at 984 cm-1 decreased. The second-derivative spectral data of xylo-oligosaccharides indicated that these changes could be attributed to substitution of the xylan backbone by arabinose residues, and the band at 958 cm-1 was ascribed to the presence of disubstituted xylose residues. Principal component analysis of FT-IR spectra of model mixtures of AX, β-glucans, and arabinogalactans suggested that it is possible to evaluate the relative proportions of the polymers and degree of substitution of AX in complex mixtures such as the cell wall of cereal grains. Keywords: Hemicellulose; β-glucan; arabinogalactan; pentosan; wheat; principal component analysis
Tracking enzyme localization and following the local biochemical modification of the substrate should help explain the recalcitrance of lignocellulosic plant cell walls to enzymatic degradation. ...Time-lapse studies using conventional imaging require enzyme labeling and following the biochemical modifications of biopolymers found in plant cell walls, which cannot be easily achieved. In the present work, synchrotron facilities have been used to image the enzymatic degradation of lignocellulosic biomass without labeling the enzyme or the cell walls. Multichannel autofluorescence imaging of the protein and phenolic compounds after excitation at 275 nm highlighted the presence or absence of enzymes on cell walls and made it possible to track them during the reaction. Image analysis was used to quantify the fluorescence intensity variations. Consistent variations in the enzyme concentration were found locally for cell cavities and their surrounding cell walls. Microfluidic FT-IR microspectroscopy allowed for time-lapse tracking of local changes in the polysaccharides in cell walls during degradation. Hemicellulose degradation was found to occur prior to cellulose degradation using a Celluclast® preparation. Combining the fluorescence and FT-IR information yielded the conclusion that enzymes did not bind to lignified cell walls, which were consequently not degraded. Fluorescence multiscale imaging and FT-IR microspectroscopy showed an unexpected variability both in the initial biochemical composition and the degradation pattern, highlighting micro-domains in the cell wall of a given cell. Fluorescence intensity quantification showed that the enzymes were not evenly distributed, and their amount increased progressively on degradable cell walls. During degradation, adjacent cells were separated and the cell wall fragmented until complete degradation.
Introduction
Information and Communication Technologies (ICT) are the most popular medium for social communication amongst adolescents and young adults. However, there is growing concern surrounding ...heightened ICT use and the activation of influential social constructs such as moral identity and moral disengagement. The importance of moral ideals to oneself (i.e., moral identity) and the distancing of oneself from these moral ideals (i.e., moral disengagement) are often contextual and were tested for differences in online domains compared to face‐to‐face interactions.
Methods
Three hundred and ninety‐two early adolescent to young adult participants (Mage = 19.54 years, SD = 4.48) completed self‐report questionnaires that assessed online and face‐to‐face behavior in this cross‐sectional study.
Results
Moral identity in an online context was significantly lower when compared to family and friend contexts. Further, moral disengagement was significantly higher in an online context when compared to face‐to‐face contexts and online moral disengagement significantly mediated the relationship between online moral identity and antisocial online behaviors (i.e., pirating, trolling, and hacking, etc.,). Both of these contextual differences remained stable across early adolescence to young adulthood.
Conclusion
Moral identity and moral disengagement exhibit sociocognitive effects within online contexts across ages of early developmental importance. These results may account for high prevalence rates of antisocial online behavior such as trolling, pirating, and hacking within this sample. As social interaction for younger demographics continues to gravitate online, these results highlight that online contexts can influence important personality constructs.
Minor compounds of cereal grains such as lipids and cell wall polysaccharides play an important role in their milling properties, their transformation into baked cereal products and their nutritional ...properties. These effects are mainly due to their interactive properties, such as their ability to absorb large amounts of water for polysaccharides or to interact with starch polymers and proteins for lipids. Environmental stress induced by climate change and regulations for environmentally friendly agriculture can interfere with the biosynthesis of these minor grain compounds as well as the main compounds starch and protein. Indeed, the metabolic networks of all components of the endosperm of grains are closely associated. Therefore, in the context of climate change and agricultural sustainability, lipids and cell wall polysaccharides may be affected. Contrasting with a plethora of studies reporting the impact of environment and fertilizer on cereal proteins, there is a real lack of information on this particular topic for these minor compounds. However, our knowledge of the physico-chemical properties and biosynthesis of these minor compounds allows us to assess the likely strong impact of environmental and agronomic constraints on the relationships between cell wall polysaccharides, lipids and cereal quality.
•Cereal grains lipids and cell wall polysaccharides impact cereal products quality.•Lipids and cell walls are heterogeneously distributed in cereal grains.•Lipids & cell wall polymers content and proportion are affected by climate change.
Arabinoxylans (AX) are cell wall polysaccharides of complex structure involved in many aspects of wheat flour end uses. The study of the variations of AX structure can lead to the identification of ...genes involved in their biosynthesis, and thus in the control of the various aspects of grain quality related to their presence. A method is proposed to identify AX variations directly in whole grain by enzymatic degradation. An endoxylanase from Trichoderma viride was used to extract AX from a collection of 20 wheat cultivars (Triticum aestivum L.). Enzymatic degradation products were analyzed by HPAEC and multivariate analysis techniques (principal component analysis, canonical correlation analysis, and cluster analysis) were applied to analyze chromatographic data. The method evidenced variations in the proportion of mono- and disubstitution of the xylan backbone by arabinose side chains, allowing classification of the different varieties according to the structural features of AX. A similar classification was obtained starting from flour or whole grain, indicating that the method was specific of AX from endosperm tissues. In conclusion, the method combining endoxylanase treatment of wheat grain and the analysis of degradation products, e.g., enzymatic fingerprinting, can be applied to collections of wheat cultivars, and possibly other cereals in order to establish quantitative trait loci related to the biosynthesis of AX. Keywords: Enzymatic fingerprinting; multivariate analysis; cereal; cell wall; HPAEC
Mannose-based polysaccharides are widespread in the living world. From one organism to another, the length of the mannose backbone, the typeof linkages between sugars, composition and the length of ...the ramifications are extremely variable and give these polymers different biologicalproperties. Beyond their structural role or as water keeper molecules in plants, they participate in the glycosylation of proteins and are involvedin ligand-receptor interaction. Some highly preserved viral or bacterial mannose polymers are thus, in higher animals, recognized very quickly bythe host, which defends itself by initiating a non-specific response, known as “innate immune response”. Rather connected by a-bonds in viruses,bacteria and yeasts, mannose units are connected by β-bonds in higher plants. These β-mannans are found in all plant products, in particularlyhigh level in some families (palm kernel, guar, coprah) and derived by-products used in animal feeds. Their anti-nutritional properties observed inpigs and poultry are mainly explained by the appearance of intestinal inflammation inducing performance declines, reduced food efficiency andincreased energy expenditure on maintenance related to the immune system activity.
Les polysaccharides à base de mannose sont très largement répandus dans le monde vivant. D’un organisme à un autre, la longueur dusquelette de mannose, le type de liaison entre les sucres, la composition et la longueur des ramifications sont extrêmement variables etconfèrent à ces polymères des propriétés fonctionnelles et biologiques différentes. Au-delà de leur rôle structural ou encore de capteurde molécules d’eau dans les plantes, ils participent en particulier à la glycosylation des protéines et sont clairement impliqués dans lesphénomènes d’interaction ligand-récepteur. Certains polymères de mannose viraux ou bactériens hautement conservés sont ainsi, chez lesanimaux supérieurs, reconnus très rapidement par l’hôte qui se défend en initiant une réponse non spécifique, dite « réaction immunitaireinnée ». Plutôt reliées par les liaisons α chez les virus, les bactéries et les levures, les unités de mannose sont reliées par des liaisons β chezles végétaux supérieurs. Les β-mannanes sont présents dans tous les produits d’origine végétale, et à des teneurs particulièrement élevéesdans certaines familles (palme, guar, coprah) et certains tourteaux utilisés en alimentation animale. Leurs propriétés anti-nutritionnellesobservées chez les porcs et les volailles s’expliqueraient principalement par l’apparition d’inflammation intestinale induisant des baissesde performances, des baisses d’efficacité alimentaire et une augmentation des dépenses énergétiques associées à la mise en œuvre dusystème immunitaire.
Background： The filamentous fungus Talaromyces versatifis is known to improve the metabolizable energy of wheat- based poultry diets thanks to its ability to produce a pool of CAZymes and ...particularly endo-β（1,4）-xylanases. In order to appreciate their in vivo mode of action, the supplementation effect of two of its xylanases, XynD and XynB from families GH10 and GHll respectively, have been evaluated on two different wheat cultivars Caphorn and Isengrain, which were chosen amongst 6 varieties for their difference in non starch polysaccharides content and arabinoxylan composition. Results： Polysaccharides digestion was followed during 6 h along the digestive tract using the TNO gastrointestinal model-1, to mimic monogastric metabolism. Polysaccharide degradation appeared to occur mainly at the jejunal level and was higher with Isengrain than with Caphorn. For both cultivars, XynD and XynB supplementation increased notably the amount of reducing end sugars into the jejuno-ileal dialysates, which has been confirmed by a valuable increase of the soluble glucose into the jejunal dialysates. Conclusions： The amounts of arabinose and xylose into the dialysates and ileal deliveries increased consequently mainly for Caphorn, suggesting that XynD and XynB supplementation in wheat-based diet could alleviate the anti-nutritional effects of arabinoxylans by limiting the physical entrapment of starch and could increase the available metabolizable energy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To investigate the incubation conditions encountered by enzymes in cereal-based product transformation processes, this study aims to provide comprehensive information on the effect of low (18 %) to ...high (72 %) solid loading on the behavior of bacterial and fungal xylanases towards wheat grain fractions, i.e. white flour, ground whole grain and bran. Both enzymes are effective from 30 % water content. A water content of 50 % appears as the threshold for optimal arabinoxylan solubilisation. The specificity of enzymes was influenced by low hydration conditions, particularly in wheat bran, which contains arabinoxylan with diverse structures. Especially the bacterial xylanase became more tolerant to arabinose substitution as the water content decreased. Time Domain-NMR measurements revealed four water mobility domains in all the fractions. The water populations corresponding to 7.5 nm to 15 nm pores were found to be the most restrictive for enzyme activity. These results define the water content limits for the optimal xylanase action in cereal products.
Various arabino-xylo-oligosaccharides with known substitution patterns were assessed by negative ESI-Q-TOFMS and ESI-ITMS. The CID spectra of linear xylo-oligosaccharides and of nine isomeric mono- ...and disubstituted arabino-xylo-oligosaccharides established that structures differing in their substitution pattern can be differentiated by this approach. The negative-ion fragmentation spectra of the deprotonated quasi-molecular ions are mainly characterized by glycosidic cleavage ions from the C-series, which provide sequence informations, and by cross-ring cleavage
0,2A
i
ions, which provide partial linkage information. When the collision energy increased, the cross-ring cleavage
0,2A
i
ions underwent consecutive loss of water to produce
0,2A
i
−
18 fragment ions and glycosidic cleavage ions of the B-series are also produced besides the C
i
ions. Contrary to linear xylo-oligosaccharides, C
i
ions, which originate from C-3 monosubstituted xylosyl residues never produce the related cross-ring cleavage
0,2A
i
ions. Disubstitution at O-2 and O-3 of xylosyl residues appears to enhance the production of the
0,2A
i
ions compared to monosubstitution. For the differentiation of the mono- and disubstitution patterns of the penultimate xylosyl residue, the relative abundance of the glycosidic cleavage ions at
m/
z 263 and 299 found on Q-TOF CID spectra plays a relevant role and appears to be more informative than MS
n
spectra obtained on a ion trap instrument.
PDF
