•The immunostimulatory activity of polysaccharides triggering cellular events is presented.•Glucans, mannans, and pectic polysaccharides are the most studied immunostimulatory polysaccharides.•The ...immunostimulatory activity is influenced by a combination of structural features.•Triple-helix and acetyl and sulfate groups highly contribute to the immunostimulation.•More in vitro and in vivo assays with well structurally defined polysaccharides are required.
Immunostimulatory polysaccharides are compounds capable of interacting with the immune system and enhance specific mechanisms of the host response. Glucans, mannans, pectic polysaccharides, arabinogalactans, fucoidans, galactans, hyaluronans, fructans, and xylans are polysaccharides with reported immunostimulatory activity. The structural features that have been related with such activity are the monosaccharide and glycosidic-linkage composition, conformation, molecular weight, functional groups, and branching characteristics. However, the establishment of structure–function relationships is possible only if purified and characterized polysaccharides are used and selective structural modifications performed. Aiming at contributing to the definition of the structure–function relationships necessary to design immunostimulatory polysaccharides with potential for preventive or therapeutical purposes or to be recognized as health-improving ingredients in functional foods, this review introduces basic immunological concepts required to understand the mechanisms that rule the potential claimed immunostimulatory activity of polysaccharides and critically presents a literature survey on the structural features of the polysaccharides and reported immunostimulatory activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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•Microwave hydrodiffusion and gravity (MHG) technology allows extraction and dehydration of broccoli by-products.•MHG allows a fast dehydration of the by-products.•MHG allows to ...stabilize broccoli by-products for further use.•MHG promotes pectic polysaccharides extraction.•Extracts are composed by a diversity of phenolics, sugars, amino acids, and glucosinolates.
Broccoli by-products from frozen-food industry account for 45% of the initial broccoli heads. They consist on stalks, inflorescences, and leaves, blanched and non-blanched, sharing the nutritional value and bioactive compounds of commercial broccoli heads. However, their high perishability prevents further valorisation. Therefore, in this study microwave hydrodiffusion and gravity (MHG) technology was used to dehydrate broccoli by-products and simultaneously recover the water-soluble diffused compounds for food ingredients use. The hydrodiffusion allowed to obtain a dried material with 12% moisture in 43 min when 550 g of broccoli by-products were used, preserving polysaccharides and proteins. Diffused water contained up to 317 µg/mL gallic acid equivalents of phenolic compounds, 11 mg/mL free sugars, 9 mg/mL amino acids, and 356 µg/mL glucosinolates, depending on the type of by-product used. These results show the potential of MHG technology for valorisation of broccoli by-products by its simultaneous stabilization by dehydration and extraction of bioactive compounds.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•Study of polysaccharides structure by sugar and methylation analysis and microarrays.•Composed of (β1→3, β1→4)-glucans, (α1→3)-, (α1→4)-mannans, and sulphated ...heterorhamnans.•Water-soluble polysaccharides from N. oculata stimulate B lymphocytes in vitro.
The relevance of microalgae biotechnology for producing high-value compounds with biomedical application, such as polysaccharides, has been increasing. Despite this, the knowledge about the composition and structure of microalgae polysaccharides is still scarce. In this work, water-soluble polysaccharides from Nannochloropsis oculata were extracted, fractionated, structurally analysed, and subsequently tested in terms of immunostimulatory activity. A combination of sugar and methylation analysis with interaction data of carbohydrate-binding proteins using carbohydrate microarrays disclosed the complex structural features of the different polysaccharides. These analyses showed that the water-soluble polysaccharides fractions from N. oculata were rich in (β1→3, β1→4)-glucans, (α1→3)-, (α1→4)-mannans, and anionic sulphated heterorhamnans. The immunostimulatory assay highlighted that these fractions could also stimulate murine B-lymphocytes. Thus, the N. oculata water-soluble polysaccharides show potential to be further explored for immune-mediated biomedical applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
While it is possible to define exile broadly as a specific type of mobility – ‘forced migration’ – the expression is subject to multiple definitions. In this article, the author looks at exile by ...drawing on ethnographic examples from the Associação de Exilados Políticos Portugueses (Association of Portuguese Political Exiles, AEP61‐74), founded in Lisbon in 2015. The author suggests that the concept of exile should not be a mere label for a particular type of person or situation (present in classic literary examples), but rather a conceptual category that can include a multitude of socio‐economic, historical, psychological and biographical realities.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
To study structure-function relationships of pectic polysaccharides with their immunostimulatory activity, broccoli by-products were used. Pectic polysaccharides composed by 64 mol% uronic acids, ...18 mol% Ara, and 10 mol% Gal, obtained by hot water extraction, activated B lymphocytes in vitro (25–250 μg/mL). To disclose active structural features, combinations of ethanol and chromatographic fractionation and modification of the polysaccharides were performed. Polysaccharides insoluble in 80 % ethanol (Et80) showed higher immunostimulatory activity than the pristine mixture, which was independent of molecular weight range (12–400 kDa) and removal of terminal or short Ara side chains. Chemical sulfation did not promote B lymphocyte activation. However, the action of pectin methylesterase and endo-polygalacturonase on hot water extracted polysaccharides produced an acidic fraction with a high immunostimulatory activity. The de-esterified homogalacturonan region seem to be an important core to confer pectic polysaccharides immunostimulatory activity. Therefore, agri-food by-products are a source of pectic polysaccharide functional food ingredients.
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•Pectic polysaccharides from broccoli by-products activate B lymphocytes.•Immunostimulation do not rely on terminal arabinose and molecular weight.•Chemical sulfation does not impact immunostimulatory activity.•De-esterified homogalacturonan regions are an important core for activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Ce texte s’inscrit dans un projet de cartographie et d’analyse critique de la production de médias portugais dans le contexte migratoire. Privilégiant le Brésil, il analyse la façon dont les médias ...ethniques et leurs producteurs constituent l’un des instruments clés d’une culture de l’expression dont l’analyse offre une voie d’entrée dans les processus de production et d’exposition culturelle et identitaire des migrants. Ils permettent tout autant de mieux connaître leurs logiques de « marchandisation de la nostalgie » et d’utilisation des niches du commerce ethnique inscrites dans l’espace urbain.
Inserido num projeto de mapeamento e análise crítica da produção mediática portuguesa em contexto migratório, este texto foca-se no Brasil analisando como a mídia étnica e os seus produtores constituem uma das formas de cultura expressiva mais importante para pensar os processos de produção e exibição cultural e identitária das comunidades migrantes mas também as suas lógicas de « mercadorização da nostalgia » e de aproveitamento dos nichos comerciais étnicos inscritos no espaço urbano.
This article, part of a broader effort to map and critically analyze Portuguese media production in a migratory context, focuses on Brazil, analyzing how ethnic media and its producers constitute one of the most important forms of expressive culture in thinking about processes of cultural and identity production and exhibition of migrant communities, but also the logic of « commodification of nostalgia » and exploitation of urban ethnic commercial niches.
•A branched arabinogalactan (AG) was isolated from Pistachio hull.•The purified fractions contained a type II arabinogalactan carbohydrate moiety.•AG structural elucidation was attained by ...methylation analysis, 1D/2D NMR, and SEC.•Arabinogalactans displayedimmuno-enhancing effects.•Pistachio AG could be explored as a potent food additive or nutritional supplement.
This work studies the extraction and purification of a novel arabinogalactan from pistachio external hull. It was extracted with a simple method from pistachio hull which is considered as unexploited waste. Based on the results of sugar analysis by GC-FID, glycosidic linkage by GC–MS, NMR spectroscopy, and molecular weight by Size Exclusion Chromatography, pistachio hull water soluble polysaccharides (PHWSP) were identified as a type II arabinogalactan (AG), with characteristic terminally linked α-Araf, (α1 → 5)-Araf, (α1 → 3,5)-Araf, terminally linked β-Galp, (β1 → 6)-Galp, and (β1 → 3,6)-Galp. DEPT-135, HSQC, HMBC and COSY NMR data suggested the presence of (β1 → 3)-Galp mainly branched at O-6 with (β1 → 6)-Galp chains, α-Araf chains, and terminally linked α-Araf. These AG from pistachio external hulls showed in vitro stimulatory activity for B cells, suggesting their possible use as an immunological stimulant in nutraceutical and biomedical applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Chloroplast located Glutamine Synthetase (GS2) is believed to play a major role in the reassimilation of ammonium generated by photorespiration, being GS2 knockout mutants unable to grow under ...photorespiratory conditions (low-CO2 atmosphere) in the species characterized so far (Barley, Lotus). To investigate the importance of GS2 in A. thaliana nitrogen metabolism mutant plants devoid of this GS isoenzyme were characterized. It was shown that GS2 mutants although smaller, slightly chlorotic and with the nitrogen metabolism impaired, were able to grow and complete their life cycle under ordinary air conditions. Surprisingly, GS2 mutants were more tolerant to salt stress than wild-type plants. The lack of GS2 seems to be compensated by higher expression of some GS cytosolic isogenes, namely GLN1;2 and GLN1;3 and by glutamate dehydrogenase, whose activity and expression is enhanced in the GS2 mutant plants and might account for the increased tolerance to salt stress. Under conditions that minimize photorespiration (CO2-enriched atmosphere) plant growth and ammonium assimilation impairment is less evident in the GS2 mutant plants and is accompanied by an adjustment of levels of expression of the cytosolic isogenes, with an increase in the expression of GLN1;3 and a decrease in the expression of the GLN1;1 and GLN1;2. Altogether the results confirm a major role of GS2 in the assimilation of ammonium released during photorespiration, but suggest a redundancy of activity with cytosolic GSs and GDH and further support the involvement of the chloroplastic isoenzyme in primary nitrogen assimilation and plant growth and development in A. thaliana.
•A. thaliana GS2 knockout mutants are able to survive under photorespiratory conditions.•A species-specific compensatory mechanism leads to survival of A. thaliana GS2 mutants under low CO2.•In A. thaliana GS2 mutants GS1 acts redundantly with GDH assimilating photorespiratory ammonium.•The role of GS2 in primary nitrogen assimilation can be partially replaced by a GS1 isoenzyme, GLN1; 3.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Yeast cell walls undergo modifications during the brewing process, leading to a remodelling of their architecture. One significant change is the increased insolubility of the cell wall glycogen pool, ...likely due to the formation of covalent bonds between glycogen and cell wall polysaccharides. To verify this hypothesis, we extracted the brewer's spent yeast with 4 M KOH, obtaining an insoluble glucan fraction (AE.4 M) primarily composed of (α1 → 4)- and (1 → 3)-linked Glc residues. Dynamic nuclear polarization solid-state NMR of AE.4 M revealed distinct glucan resonances that helped to differentiate between α- and β glucosyl (1 → 4)-linked residues, and confirm covalent linkages between (β1 → 3)-glucans and glycogen through a (β1 → 4)-linkage.
The hydrolysis with different endo-glucanases (zymolyase, cellulase, and lichenase) was used to obtain solubilized high molecular weight glycogen fractions. NMR analysis showed that covalent links between glycogen and (β1 → 6)-glucans through (α1 → 6) glycosidic linkage, with branching at the C6 position involving (β1 → 3), and (β1 → 6)-glucans. HPAEC-PAD analysis of the enzymatically released oligosaccharides confirmed covalent linkages of (β1 → 3), (β1 → 6)-, and (β1 → 4)-glucan motifs with (α1 → 4)-glucans. This combination of multiple enzymatic approaches and NMR methods shed light into the role of yeast cell wall glycogen as a structural core covalently linked to other cell wall components during the brewing process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Human visual cortex does not represent the whole visual field with the same detail. Changes in receptive field size, population receptive field (pRF) size and cortical magnification factor (CMF) with ...eccentricity are well established, and associated with changes in visual acuity with eccentricity. Visual acuity also changes across polar angle. However, it remains unclear how RF size, pRF size and CMF change across polar angle. Here, we examine differences in pRF size and CMF across polar angle in V1, V2 and V3 using pRF modeling of human fMRI data. In these visual field maps, we find smaller pRFs and larger CMFs in horizontal (left and right) than vertical (upper and lower) visual field quadrants. Differences increase with eccentricity, approximately in proportion to average pRF size and CMF. Similarly, we find larger CMFs in the lower than upper quadrant, and again differences increase with eccentricity. However, pRF size differences between lower and upper quadrants change direction with eccentricity. Finally, we find slightly smaller pRFs in the left than right quadrants of V2 and V3, though this difference is very small, and we find no differences in V1 and no differences in CMF. Moreover, differences in pRF size and CMF vary gradually with polar angle and are not limited to the meridians or visual field map discontinuities. PRF size and CMF differences do not consistently follow patterns of cortical curvature, despite the link between cortical curvature and polar angle in V1. Thus, the early human visual cortex has a radially asymmetric representation of the visual field. These asymmetries may underlie consistent reports of asymmetries in perceptual abilities.
•PRFs are smaller in horizontal than vertical visual field quadrants of V1, V2 & V3.•Cortical magnification is correspondingly larger in these horizontal quadrants.•Cortical magnification is larger in the lower than the upper quadrant.•The size of these differences typically increases with visual field eccentricity.•Upper versus lower quadrant PRF size differences change direction with eccentricity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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