14 results on '"S. Le Gall"'
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2. CALPHAD-aided synthesis and characterization of an Al–Co–Cr–Fe–Ni–W high-entropy alloy prepared by arc melting and spark plasma sintering
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L. Fenocchio, A. Saviot, S. Gambaro, S. Le Gallet, F. Valenza, M.R. Ardigo-Besnard, and G. Cacciamani
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High-entropy alloys ,Spark plasma sintering ,Arc melting ,CALPHAD modelling ,Mining engineering. Metallurgy ,TN1-997 - Abstract
In the present work, the novel Al0.15CoCrFeNiW0.15 High-Entropy Alloy (HEA) has been designed by CALPHAD (CALculation of PHAse Diagrams) computations with the in-house built Genova High-Entropy Alloys (GHEA) database, aiming to a mostly monophasic face-centered cubic (FCC) alloy strengthened by the precipitation of secondary μ phase. To explore different preparation routes, alloy samples have been synthesized by both arc melting (AM) and spark plasma sintering (SPS). Samples were characterized by low optical microscopy (LOM), scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), and microhardness measurements. Long-term annealing at 1100 °C has been performed, followed by quenching or furnace cooling. AM as-cast sample showed a monophasic FCC microstructure, characterized by large grains. Precipitation of μ phase was observed in the equilibrated and quenched sample, in good agreement with the thermodynamic calculations. On the other hand, SPS samples resulted in a finer microstructure, characterized by the presence of small particles of Al2O3 and μ phase, already present before annealing. Contrary to the thermodynamic predictions, after equilibration and quenching, the dissolution of the μ phase was observed due to the Gibbs-Thomson effect, which enhanced W solubility in the FCC solid solution. Annealing of the SPSed alloy followed by furnace cooling, however, allowed the precipitation of μ, thanks to the slower cooling rate. Overall, this study highlighted CALPHAD's utility for composition selection in complex multicomponent systems and demonstrated how AM and SPS lead to significantly different microstructures and properties, with grain size playing a key role in determining the alloy performances.
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- 2025
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3. Development and calibration of the FSPM CPlantBox to represent the interactions between water and carbon fluxes in the soil-plant-atmosphere continuum
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M. Giraud, S. Le Gall, M. Harings, M. Javaux, D. Leitner, F. Meunier, Y. Rothfuss, D. van Dusschoten, J. Vanderborght, H. Vereecken, G. Lobet, and A. Schnepf
- Abstract
A plant’s development is strongly linked to the water and carbon flows in the soil-plant-atmosphere continuum. Expected climate shifts will alter the water and carbon cycles and will affect plant phenotypes. Comprehensive models which simulate mechanistically and dynamically the feedback loops between a plant’s three-dimensional development and the water and carbon flows are useful tools to evaluate the sustainability of genotype-environment-management combinations which do not yet exist. In this study, we present the latest version of the open-source three-dimensional Functional-Structural Plant Model CPlantBox with PiafMunch and DuMuxcoupling. We simulated semi-mechanistically the development of generic C3 monocots from 10 to 25 days after sowing and undergoing an atmospheric dry spell of one week (no precipitation). We compared the results for dry spells starting on different days (day 11 or 18) and with different climates (wetter and colder against drier and warmer atmospheric and initial soil conditions). Compared with the wetter and colder climate, the dry spell with the drier and warmer climate led to a lower instantaneous water use efficiency. Moreover, the lower symplasm turgor for the drier and warmer climate limited the growth, which made the sucrose available for other processes, such as maintenance respiration. Both of these effects were stronger for the later dry spell compared with the early dry spell under the drier and warmer climate. We could thus use CPlantBox to simulate diverging emerging processes (like carbon partitioning) defining the plants’ phenotypic plasticity response to their environment.
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- 2023
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4. Lead-vanadate sorbents for iodine trapping and their conversion into an iodoapatite-based conditioning matrix
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R. Pénélope, L. Campayo, M. Fournier, S. Le Gallet, A. Gossard, and A. Grandjean
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filter ,iodine ,off-gas ,apatite ,waste disposal ,Chemistry ,QD1-999 - Abstract
New lead-vanadate based sorbents were synthesized with the aim to entrap and confine gaseous iodine in off-gas streams coming from reprocessing facilities of spent nuclear fuel. Their synthesis relies on the shaping of a lead-vanadate, lead sulfide and alginic acid mix as millimetric beads. These beads were calcined between 220°C and 500°C to remove organic alginic compounds template. However, according to the calcination temperature, lead sulfide could be partially oxidized, limiting iodine loading capacity. A compromise temperature between 290°C and 350°C was found to remove most of the alginic acid template and avoiding lead sulfide oxidation. These sorbents were tested for iodine trapping in static conditions at 60°C. They performed well with a sorption capacity up to 155 mg.g−1 by forming PbI2. Furthermore, these iodine-loaded sorbents could be easily converted into an iodine-containing lead-vanadate apatite matrix by spark plasma sintering. A dense sample was produced for a sintering temperature of 500°C under 70 MPa. Such a material could be suitable for radioactive iodine conditioning in deep geological disposal. Finally, lead-vanadate sorbents could provide an easy way to entrap and confine radioactive iodine from off-gas streams into a durable material within a few steps.
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- 2022
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5. Exploration of the extracellular matrix of the red alga Chondrus crispus reveals unprecedented insights into carrageenan structures.
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Ropartz D, Lissarrague A, Jam M, Jouanneau D, Le Gall S, Annic B, Fanuel M, Krueger-Hadfield SA, Valéro M, Czjzek M, Rogniaux H, and Hervé C
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- Glycoside Hydrolases metabolism, Glycoside Hydrolases chemistry, Carrageenan chemistry, Chondrus chemistry, Extracellular Matrix metabolism, Extracellular Matrix chemistry
- Abstract
Carrageenans are major gel forming polysaccharides in the extracellular matrix of the red macroalga Chondrus crispus. These galactans are made of linear chains of repetitive disaccharide motifs based on d-galactose residues alternately linked by β-1,4 and α-1,3 glycosidic bonds. A definite number of disaccharide motifs are known, based on their regular sulfations and the presence of a 3,6-anhydro bridge. While these motifs are variable as a function of species, life cycle phases, or seasons, our understanding of the in vivo regulation of carrageenan fine structures is still limited. Characterized hydrolytic enzymes (κ-, ι- and λ-carrageenases) are powerful tools for identifying glycan structures in extracted ECMs. Their use, combined to chromatography and high-resolution mass spectrometry, allowed us to refine our understanding of carrageenan variability in the phases of C. crispus. We provide the first demonstration that κ/ι carrabiose motifs are not limited to gametophytes, but are also present in tetrasporophytes, together with over- and under-sulfated λ-motifs. Our findings highlight a more complex carrageenan composition than previously described in this model system. These results are further discussed in the light of recent transcriptomic data and suggest that the historical hypotheses on the biosynthetic pathway of carrageenans in red algae may need revision. HYPOTHESIS: Combined characterized hydrolytic enzymes to chromatography and high-resolution mass spectrometry can refine our understanding of carrageenan variability in the phases of C. crispus., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)
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- 2025
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6. The role of wheat flour minor components in predicting water absorption.
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Rezette L, Kansou K, Della Valle G, Le Gall S, and Saulnier L
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- Viscosity, Bread analysis, Plant Proteins analysis, Plant Proteins chemistry, Plant Proteins metabolism, France, Xylans chemistry, Xylans analysis, Flour analysis, Triticum chemistry, Triticum metabolism, Water chemistry, Water analysis, Starch chemistry, Starch metabolism
- Abstract
Water absorption in wheat flour is a crucial parameter for optimizing bread-making processes. The determinants of wheat flour water absorption were investigated through the analysis of 28 compositional and technological properties of 150 wheats grown in France. A multiple linear regression approach was used to predict the water absorption, selecting the best model through successive examination of Bayesian Information Criterion, Variance Inflation Factor and minimizing the total number of variables. A model with protein content, soluble starch, damaged starch and specific viscosity from water extractable arabinoxylans was identified as the best trade-off between the number of variables and the predictive performances among all possible models. Soluble Starch, varying between 1.11 and 6.21 g/100 g flour a new criterion measured alongside water-extractable arabinoxylans content, varying between 0.26 and 0.86 g/100 g flour, shows significant potential to predict water absorption compared to damaged starch., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)
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- 2025
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7. Receptor kinase LecRK-I.9 regulates cell wall remodelling during lateral root formation in Arabidopsis.
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Bellande K, Roujol D, Chourré J, Le Gall S, Martinez Y, Jauneau A, Arico D, Mithöfer A, Burlat V, Jamet E, and Canut H
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Assembling and remodelling the cell wall is essential for plant development. Cell wall dynamics is controlled by cell wall proteins, polysaccharide biosynthesis, and a variety of sensor and receptor systems. LecRK-I.9, an Arabidopsis thaliana plasma membrane-localised lectin receptor kinase, was previously shown to be involved in cell wall-plasma membrane contacts and to play roles in plant-pathogen interactions, but so far, its role in development was unknown. LecRK-I.9 is transcribed at a high level in root tissues including the pericycle. Comparative transcript profiling of a loss-of-function mutant vs wild type identifies LecRK-I.9 as a regulator of cell wall metabolism. Consistently, lecrk-I.9 mutants display an increased pectin methylesterification level correlated with decreased pectin methylesterase and increased polygalacturonase activities. Also, LecRK-I.9 negatively impacts lateral root development through the direct or indirect regulation of genes encoding (i) cell wall remodelling proteins during early events of lateral root initiation, and (ii) cell wall signalling peptides (CLE2, CLE4) repressing lateral root emergence and growth. Besides, low nitrate reduces LecRK-I.9 expression in roots, particularly in the lateral root emergence zone: even in these conditions, the control of CLE2 and CLE4 expression is maintained. Altogether, the results show that LecRK-I.9 is a key player in negatively regulating both pre-branch site formation and lateral root emergence., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)
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- 2024
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8. Maternal short chain fructo-oligosaccharides supplementation during late gestation and lactation influences milk components and offspring gut metabolome: a pilot study.
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Le Bourgot C, Lollier V, Richer Y, Thoulouze L, Svilar L, Le Gall S, Blat S, and Le Huërou-Luron I
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- Animals, Swine, Pregnancy, Female, Humans, Pilot Projects, Dietary Supplements analysis, Diet veterinary, Metabolome, Oligosaccharides metabolism, Lipids, Animal Feed analysis, Milk metabolism, Lactation
- Abstract
Breast milk composition is influenced by maternal diet. This study aimed to evaluate if supplementation of maternal diet with a prebiotic fibre, through its potential effect on milk composition, can be a leverage to orientate the gut microbiota of infants in a way that would be beneficial for their health. Twelve sows received a diet supplemented with short chain fructo-oligosaccharides or maltodextrins during the last month of gestation and the lactation. Oligosaccharidic and lipidomic profiles of colostrum and mature milk (21 days), as well as faecal microbiota composition and metabolomic profile of 21 day-old piglets were evaluated. The total porcine milk oligosaccharide concentration tended to be lower in scFOS-supplemented sows, mainly due to the significant reduction of the neutral core oligosaccharides (in particular that of a tetrahexose). Maternal scFOS supplementation affected the concentration of 31 lipids (mainly long-chain triglycerides) in mature milk. Faecal short-chain fatty acid content and that of 16 bacterial metabolites were modified by scFOS supplementation. Interestingly, the integrative data analysis gave a novel insight into the relationships between (i) maternal milk lipids and PMOs and (ii) offspring faecal bacteria and metabolites. In conclusion, scFOS-enriched maternal diet affected the composition of mature milk, and this was associated with a change in the colonisation of the offspring intestinal microbiota., (© 2024. The Author(s).)
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- 2024
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9. The Ustilago maydis AA10 LPMO is active on fungal cell wall chitin.
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Yao RA, Reyre J-L, Tamburrini KC, Haon M, Tranquet O, Nalubothula A, Mukherjee S, Le Gall S, Grisel S, Longhi S, Madhuprakash J, Bissaro B, and Berrin J-G
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- Cell Wall metabolism, Basidiomycota, Cellulose metabolism, Mixed Function Oxygenases metabolism, Chitin metabolism, Polysaccharides metabolism
- Abstract
Lytic polysaccharide monooxygenases (LPMOs) can perform oxidative cleavage of glycosidic bonds in carbohydrate polymers (e.g., cellulose, chitin), making them more accessible to hydrolytic enzymes. While most studies have so far mainly explored the role of LPMOs in a (plant) biomass conversion context, alternative roles and paradigms begin to emerge. The AA10 LPMOs are active on chitin and/or cellulose and mostly found in bacteria and in some viruses and archaea. Interestingly, AA10-encoding genes are also encountered in some pathogenic fungi of the Ustilaginomycetes class, such as Ustilago maydis , responsible for corn smut disease. Transcriptomic studies have shown the overexpression of the AA10 gene during the infectious cycle of U. maydis . In fact, U. maydis has a unique AA10 gene that codes for a catalytic domain appended with a C-terminal disordered region. To date, there is no public report on fungal AA10 LPMOs. In this study, we successfully produced the catalytic domain of this LPMO ( Um AA10_cd) in Pichia pastoris and carried out its biochemical characterization. Our results show that Um AA10_cd oxidatively cleaves α- and β-chitin with C1 regioselectivity and boosts chitin hydrolysis by a GH18 chitinase from U. maydis ( Um GH18A). Using a biologically relevant substrate, we show that Um AA10_cd exhibits enzymatic activity on U. maydis fungal cell wall chitin and promotes its hydrolysis by Um GH18A. These results represent an important step toward the understanding of the role of LPMOs in the fungal cell wall remodeling process during the fungal life cycle.IMPORTANCELytic polysaccharide monooxygenases (LPMOs) have been mainly studied in a biotechnological context for the efficient degradation of recalcitrant polysaccharides. Only recently, alternative roles and paradigms begin to emerge. In this study, we provide evidence that the AA10 LPMO from the phytopathogen Ustilago maydis is active against fungal cell wall chitin. Given that chitin-active LPMOs are commonly found in microbes, it is important to consider fungal cell wall as a potential target for this enigmatic class of enzymes., Competing Interests: The authors declare no conflict of interest.
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- 2023
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10. The Maize Pathogen Ustilago maydis Secretes Glycoside Hydrolases and Carbohydrate Oxidases Directed toward Components of the Fungal Cell Wall.
- Author
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Reyre JL, Grisel S, Haon M, Navarro D, Ropartz D, Le Gall S, Record E, Sciara G, Tranquet O, Berrin JG, and Bissaro B
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- Carbohydrates, Oxidoreductases metabolism, Fungal Proteins genetics, Fungal Proteins metabolism, Zea mays metabolism, Cell Wall metabolism, Fungi metabolism, Plants metabolism, Phylogeny, Glucans metabolism, Basidiomycota, Ustilago, Glycoside Hydrolases metabolism
- Abstract
Filamentous fungi are keystone microorganisms in the regulation of many processes occurring on Earth, such as plant biomass decay and pathogenesis as well as symbiotic associations. In many of these processes, fungi secrete carbohydrate-active enzymes (CAZymes) to modify and/or degrade carbohydrates. Ten years ago, while evaluating the potential of a secretome from the maize pathogen Ustilago maydis to supplement lignocellulolytic cocktails, we noticed it contained many unknown or poorly characterized CAZymes. Here, and after reannotation of this data set and detailed phylogenetic analyses, we observed that several CAZymes (including glycoside hydrolases and carbohydrate oxidases) are predicted to act on the fungal cell wall (FCW), notably on β-1,3-glucans. We heterologously produced and biochemically characterized two new CAZymes, called Um GH16_1-A and Um AA3_2-A. We show that Um GH16_1-A displays β-1,3-glucanase activity, with a preference for β-1,3-glucans with short β-1,6 substitutions, and Um AA3_2-A is a dehydrogenase catalyzing the oxidation of β-1,3- and β-1,6-gluco-oligosaccharides into the corresponding aldonic acids. Working on model β-1,3-glucans, we show that the linear oligosaccharide products released by Um GH16_1-A are further oxidized by Um AA3_2-A, bringing to light a putative biocatalytic cascade. Interestingly, analysis of available transcriptomics data indicates that both Um GH16_1-A and Um AA3_2-A are coexpressed, only during early stages of U. maydis infection cycle. Altogether, our results suggest that both enzymes are connected and that additional accessory activities still need to be uncovered to fully understand the biocatalytic cascade at play and its physiological role. IMPORTANCE Filamentous fungi play a central regulatory role on Earth, notably in the global carbon cycle. Regardless of their lifestyle, filamentous fungi need to remodel their own cell wall (mostly composed of polysaccharides) to grow and proliferate. To do so, they must secrete a large arsenal of enzymes, most notably carbohydrate-active enzymes (CAZymes). However, research on fungal CAZymes over past decades has mainly focused on finding efficient plant biomass conversion processes while CAZymes directed at the fungus itself have remained little explored. In the present study, using the maize pathogen Ustilago maydis as model, we set off to evaluate the prevalence of CAZymes directed toward the fungal cell wall during growth of the fungus on plant biomass and characterized two new CAZymes active on fungal cell wall components. Our results suggest the existence of a biocatalytic cascade that remains to be fully understood.
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- 2022
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11. Impact of cell wall non-cellulosic and cellulosic polymers on the mechanical properties of flax fibre bundles.
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Gautreau M, Durand S, Paturel A, Le Gall S, Foucat L, Falourd X, Novales B, Ralet MC, Chevallier S, Kervoelen A, Bourmaud A, Guillon F, and Beaugrand J
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- Cell Wall chemistry, Cellulose chemistry, Oxalates, Polymers metabolism, Flax
- Abstract
Fibre bundles are groups of elementary fibres glued together thanks to the middle lamella, and are the main fraction in plant fibre composites. In this study, relationship between the mechanical properties of flax fibre bundles, chemical composition and cellulose structure were investigated. To do so, a sequential biopolymer extraction was implemented. Fibre bundles were first depectinated by oxalate extraction, and then the hemicelluloses were extracted by LiCl/dimethyl sulfoxide (DMSO) and KOH. The oxalate extract consisted of homogalacturonans and type I rhamnogalacturonans, while the LiCl extract was composed mainly of glucomannans and the KOH extract of xyloglucans. The KOH stage resulted in the appearance of cellulose II in flax bundles. The extraction of pectin and hemicelluloses led to the disappearance of the middle lamella concomitant with a decrease in the tensile Young's modulus and maximum strength. Finally, the fibre bundle composition, ultrastructure and mechanical properties are discussed together in view of the thin middle lamella., (Copyright © 2022 Elsevier Ltd. All rights reserved.)
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- 2022
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12. SARS-CoV-2 and Prevotella spp.: friend or foe? A systematic literature review.
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Tamanai-Shacoori Z, Le Gall-David S, Moussouni F, Sweidan A, Polard E, Bousarghin L, and Jolivet-Gougeon A
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- Azithromycin pharmacology, Humans, Pandemics, Prevotella, SARS-CoV-2, COVID-19, Coinfection
- Abstract
During this global pandemic of the COVID-19 disease, a lot of information has arisen in the media and online without scientific validation, and among these is the possibility that this disease could be aggravated by a secondary bacterial infection such as Prevotella, as well as the interest or not in using azithromycin, a potentially active antimicrobial agent. The aim of this study was to carry out a systematic literature review, to prove or disprove these allegations by scientific arguments. The search included Medline, PubMed, and Pubtator Central databases for English-language articles published 1999-2021. After removing duplicates, a total of final eligible studies ( n =149) were selected. There were more articles showing an increase of Prevotella abundance in the presence of viral infection like that related to Human Immunodeficiency Virus (HIV), Papillomavirus (HPV), Herpesviridae and respiratory virus, highlighting differences according to methodologies and patient groups. The arguments for or against the use of azithromycin are stated in light of the results of the literature, showing the role of intercurrent factors, such as age, drug consumption, the presence of cancer or periodontal diseases. However, clinical trials are lacking to prove the direct link between the presence of Prevotella spp. and a worsening of COVID-19, mainly those using azithromycin alone in this indication.
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- 2022
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13. Systematic comparison of eight methods for preparation of high purity sulfated fucans extracted from the brown alga Pelvetia canaliculata.
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Nikolić Chenais J, Marion L, Larocque R, Jam M, Jouanneau D, Cladiere L, Le Gall S, Fanuel M, Desban N, Rogniaux H, Ropartz D, Ficko-Blean E, and Michel G
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- Molecular Weight, Oligosaccharides chemistry, Polysaccharides chemistry, Phaeophyceae chemistry
- Abstract
Sulfated fucans from brown algae are a heterogeneous group of biologically active molecules. To learn more on their structure and to analyze and exploit their biological activities, there is a growing need to develop reliable and cost effective protocols for their preparation. In the present study, a brown alga Pelvetia canaliculata (Linnaeus) was used as a rich source of sulfated fucans. Sulfated fucan preparation methods included neutral and acidic extractions followed by purification with activated charcoal (AC), polyvinylpolypyrrolidone (PVPP), or cetylpyridinium chloride (CPC). Final products were compared in terms of yield, purity, monosaccharide composition and molecular weight. Acidic extractions provided higher yields compared to neutral ones, whereas the AC purification provided sulfated fucan products with the highest purity. Mass spectrometry analyses were done on oligosaccharides produced by the fucanase MfFcnA from the marine bacterium Mariniflexille fucanivorans. This has provided unique insight into enzyme specificity and the structural characteristics of sulfated fucans., (Copyright © 2022 Elsevier B.V. All rights reserved.)
- Published
- 2022
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14. Structure of heteroxylans from vitreous and floury endosperms of maize grain and impact on the enzymatic degradation.
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Bonnin E, Joseph-Aimé M, Fillaudeau L, Durand S, Falourd X, Le Gall S, and Saulnier L
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- Endosperm chemistry, Starch chemistry, Xylans chemistry, Zea mays chemistry, Endo-1,4-beta Xylanases metabolism, Endosperm metabolism, Flour, Starch metabolism, Xylans metabolism, Zea mays metabolism
- Abstract
Heteroxylans (HX) from vitreous and floury parts of maize endosperm were isolated. Structural analysis showed a xylan backbone with few unsubstituted xylose residues (<9%) demonstrating the high content in side chains in both fractions. HX from floury endosperm contained more arabinose and galactose than vitreous HX. The mono-substitution rate was 15% higher in the vitreous endosperm HX. Similar amounts of uronic acids were present in both fractions (~7% DM). Galactose in the floury endosperm HX was present exclusively in terminal position. A xylanase preparation solubilized more material from floury (40.5%) than from vitreous endosperm cell walls (15%). This could be a consequence of the structural differences between the two fractions and/or of the impact of structure on the interaction abilities of these fractions with other cell wall polysaccharides. Our study advances the understanding of cell wall polysaccharides in maize endosperm and their role in enzymatic susceptibility of maize grain., (Copyright © 2021. Published by Elsevier Ltd.)
- Published
- 2022
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