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‣ Estudos anatômicos e fisiológicos de frutos de caquizeiro (Diospyros kaki L.) quanto ao acúmulo de taninos e aos processos de destanização; Anatomical and physiological studies of persimmon fruits (Diospyros kaki L.) on the tannin accumulation and deastringency processes

Tessmer, Magda Andréia
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/04/2014 Português
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O presente trabalho visou analisar comparativamente as alterações fisiológicas e estruturais de caquis adstringentes (PVA) e não adstringentes (PCNA) desde o início do desenvolvimento até a maturação avançada. Além disso, na pós-colheita, foram realizados tratamentos de destanização e testadas diferentes condições de armazenamento para "Giombo". Este trabalho está sendo apresentado em seis capítulos, sendo que os últimos cinco capítulos referem-se aos experimentos realizados entre 2010 a 2013. No capítulo 2 é apresentado o desenvolvimento de caquis "Giombo" (PVA) e "Fuyu"(PCNA). Foi possível observar que a diferenciação das células taníferas e o processo de acúmulo de taninos no vacúolo não variou entre as cultivares, porém houve diferença significativa em relação à densidade de células taníferas e aos teores de taninos solúveis. O capítulo 3 apresenta o estudo comparativo de sete estádios de maturação de caquis "Giombo" e "Rojo Brillante"(PVA) e "Fuyu" e "Hana Fuyu" (PCNA). A redução da firmeza do mesocarpo de caquis de ambos os grupos está relacionada ao avanço da maturação e não à perda natural da adstringência. A capacidade antioxidante e o teor de sólidos solúveis em caquis dos dois grupos indicam que pode haver relação com a perda natural da adstringência...

‣ Polygalacturonase-mediated dissolution and depolymerization of pectins in solutions mimicking the pH and mineral composition of tomato fruit apoplast

Almeida, Domingos P. F.; Huber, Donald J.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2007 Português
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The effects of polygalacturonase (PG) on pectin dissolution and depolymerization were examined in cell walls from mature-green tomato fruit incubated in a conventional (C) buffer (30 mMsodium acetate, 150 mMNaCl, pH 4.5) and in buffers mimicking the apoplastic solution of maturegreen (MG) and ripe fruit (R). Pectin dissolution from cell walls was much higher in C-buffer than in MG- or R-buffers. Buffered phenol inactivated cell walls incubated in C-buffer released 4.9 mg mg 1 pectin, which increased to 86.4 mg mg 1 when PG was added. In the R-buffer, PG increased the pectin dissolution from inactive cell walls from 0.5 to 18.3 mg mg 1. However, when the assay was conducted in buffer mimicking maturegreen fruits, added PG did not increase pectin dissolution. The release of uronic acids from active cell walls in C-buffer and R-buffer was consistently lower than that from inactive walls due to the activity of pectinmethylesterase. Gel filtration profiles of CDTA-soluble pectins extracted from cell walls previously incubated in C-buffer or R-buffer with PG reveal that the enzyme is capable of hydrolyzing insoluble, ionically bound, pectins. These data support the idea that pH and mineral composition of the fruit apoplast provide a means for biochemical regulation of cell wall metabolism.

‣ Pectins from apple pomace

Marcon,Márcia V.; Vriesmann,Lúcia C.; Wosiacki,Gilvan; Beleski-Carneiro,Eliana; Petkowicz,Carmen L. O.
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 Português
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Extractions of apple pectins from apple pomace were performed using an experimental design with 2² factorial. The extractor agent was 5 % (w/v) citric acid and the variables were time (30, 50 and 80 min) and temperature (50, 75 and 100 °C). The best yield (16.8 %) was obtained using higher temperatures (100 °C; 80 min). Monosaccharide composition of the pectic fractions was similar to others already described.

‣ Acidic polysaccharides from Psidium cattleianum (Araçá)

Vriesmann,Lúcia Cristina; Petkowicz,Carmen Lúcia de Oliveira; Carneiro,Paulo Irajara Borba; Costa,Maria Eugênia; Beleski-Carneiro,Eliana
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2009 Português
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The aim of this work was to study the acidic polysaccharides of Psidium cattleianum. Pectic fractions were obtained by successive extractions with water, EDTA and sodium carbonate (4 and 25ºC). Monosaccharide composition, total carbohydrates, uronic acids and protein contents were determined for each fraction. The yield of water and EDTA-soluble fractions and high content of uronic acid were consistent with the presence of pectins probably arising from the middle lamellae. On the other hand, sodium carbonate-soluble pectins had a higher neutral sugar content, indicating highly branched polysaccharides in these fractions, consistent with pectins from cell wall.

‣ Changes in pectins of the Xylopodium of Ocimum nudicaule from dormancy to sprouting

Braga,Márcia Regina; Carpita,Nicholas C.; Dietrich,Sonia M. C.; Figueiredo-Ribeiro,Rita de Cássia L.
Fonte: Brazilian Journal of Plant Physiology Publicador: Brazilian Journal of Plant Physiology
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2006 Português
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The thickened underground organ of Ocimum nudicaule is a tuber-like structure (xylopodium) that is dormant in winter and sprouts at the beginning of the spring. Changes in content of cell wall polysaccharides were shown to occur from dormancy to sprouting. Pectic polysaccharides of O. nudicaule were analyzed in relation to composition, molecular mass, and linkage structure in these two phenological phases. The pectin content was 33 % lower during sprouting when compared to dormancy. Changes were also observed in the molecular mass of the pectin fraction from dormancy to sprouting. Galacturonic acid was the predominant sugar, suggesting the presence of a homogalacturonan as the main pectic polysaccharide. A decrease in the acidic polysaccharides, homogalacturonans and rhamnogalacturonan I, equally accounted for the decrease in the pectin composition upon sprouting. These acidic carbohydrates were predominantly detected in the cell walls of the phellogen region of the xylopodium, suggesting catabolism of the cell walls of this tissue during bud flushing. These results suggest that variations in the content and in the molecular mass of pectins, in addition to changes in their composition and structure could be related to storage function as well as cell wall extension growth...

‣ Degradation of Pectins with Different Degrees of Esterification by Bacteroides thetaiotaomicron Isolated from Human Gut Flora

Dongowski, Gerhard; Lorenz, Angelika; Anger, Horst
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /04/2000 Português
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A complete human fecal flora and cultures of defined species obtained from fecal flora were investigated in vitro to determine their ability to ferment the dietary fiber pectin. Bacteroides thetaiotaomicron was tested as a pectin-degrading microorganism alone and in coculture with Escherichia coli. Macromolecular pectins with different degrees of esterification were used as substrates in microbial degradation studies. The levels of oligogalacturonic acids formed in batch cultures were estimated during a 24- or 48-h incubation period by using high-performance thin-layer chromatography and high-performance anion-exchange chromatography. The spectrum and the amount of unsaturated oligogalacturonic acids formed as intermediate products of pectin fermentation changed permanently in the culture media during incubation with the complete fecal flora. After 24 h, no oligogalacturonic acids were detected. The pectin-degrading activities of pure cultures of B. thetaiotaomicron were lower than the pectin-degrading activity of a complete fecal flora. Cocultures of B. thetaiotaomicron and E. coli exhibited intermediate levels of degradation activity. In pure cultures of E. coli no pectin-degrading activity was found. Additionally, the rate of pectin degradation was affected by the degree of esterification of the substrate. Saturated oligogalacturonic acids were not found during pectin fermentation. The disappearance of oligogalacturonic acids in the later stages of fermentation with both the complete fecal flora and B. thetaiotaomicron was accompanied by increased formation of short-chain fatty acids.

‣ Short-Term Boron Deprivation Inhibits Endocytosis of Cell Wall Pectins in Meristematic Cells of Maize and Wheat Root Apices1

Yu, Qin; Hlavacka, Andrej; Matoh, Toru; Volkmann, Dieter; Menzel, Diedrik; Goldbach, Heiner E.; Baluška, František
Fonte: American Society of Plant Physiologists Publicador: American Society of Plant Physiologists
Tipo: Artigo de Revista Científica
Publicado em /09/2002 Português
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By using immunofluorescence microscopy, we observed rapidly altered distribution patterns of cell wall pectins in meristematic cells of maize (Zea mays) and wheat (Triticum aestivum) root apices. This response was shown for homogalacturonan pectins characterized by a low level (up to 40%) of methylesterification and for rhamnogalacturonan II pectins cross-linked by a borate diol diester. Under boron deprivation, abundance of these pectins rapidly increased in cell walls, whereas their internalization was inhibited, as evidenced by a reduced and even blocked accumulation of these cell wall pectins within brefeldin A-induced compartments. In contrast, root cells of species sensitive to the boron deprivation, like zucchini (Cucurbita pepo) and alfalfa (Medicago sativa), do not internalize cell wall pectins into brefeldin A compartments and do not show accumulation of pectins in their cell walls under boron deprivation. For maize and wheat root apices, we favor an apoplastic target for the primary action of boron deprivation, which signals deeper into the cell via endocytosis-mediated pectin signaling along putative cell wall-plasma membrane-cytoskeleton continuum.

‣ F-Actin-Dependent Endocytosis of Cell Wall Pectins in Meristematic Root Cells. Insights from Brefeldin A-Induced Compartments1

Baluška, František; Hlavacka, Andrej; Šamaj, Jozef; Palme, Klaus; Robinson, David G.; Matoh, Toru; McCurdy, David W.; Menzel, Diedrik; Volkmann, Dieter
Fonte: American Society of Plant Physiologists Publicador: American Society of Plant Physiologists
Tipo: Artigo de Revista Científica
Publicado em /09/2002 Português
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Brefeldin A (BFA) inhibits exocytosis but allows endocytosis, making it a valuable agent to identify molecules that recycle at cell peripheries. In plants, formation of large intracellular compartments in response to BFA treatment is a unique feature of some, but not all, cells. Here, we have analyzed assembly and distribution of BFA compartments in development- and tissue-specific contexts of growing maize (Zea mays) root apices. Surprisingly, these unique compartments formed only in meristematic cells of the root body. On the other hand, BFA compartments were absent from secretory cells of root cap periphery, metaxylem cells, and most elongating cells, all of which are active in exocytosis. We report that cell wall pectin epitopes counting rhamnogalacturonan II dimers cross-linked by borate diol diester, partially esterified (up to 40%) homogalacturonan pectins, and (1→4)-β-d-galactan side chains of rhamnogalacturonan I were internalized into BFA compartments. In contrast, Golgi-derived secretory (esterified up to 80%) homogalacturonan pectins localized to the cytoplasm in control cells and did not accumulate within characteristic BFA compartments. Latrunculin B-mediated depolymerization of F-actin inhibited internalization and accumulation of cell wall pectins within intracellular BFA compartments. Importantly...

‣ Direct Compression Behavior of Low- and High-Methoxylated Pectins

Salbu, Linda; Bauer-Brandl, Annette; Tho, Ingunn
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Publicado em 15/12/2009 Português
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The objective of this study was to evaluate possible usefulness of pectins for direct compression of tablets. The deformation behavior of pectin grades of different degree of methoxylation (DM), namely, 5%, 10%, 25%, 35%, 40%, 50%, and 60% were, examined in terms of yield pressures (YP) derived from Heckel profiles for both compression and decompression and measurements of elastic recovery after ejection. All pectin grades showed a high degree of elastic recovery. DM 60% exhibited most plastic deformation (YP 70.4 MPa) whereas DM 5% (104.6 MPa) and DM 10% (114.7 MPa) least. However, DM 60% gave no coherent tablets, whereas tablet tensile strengths for DM 5% and DM 10% were comparable to Starch 1500®. Also, Heckel profiles were similar to Starch 1500®. For sieved fractions (180–250 and 90–125 μm) of DM 25% and DM 40% originating from the very same batch, YPs were alike, indicating minor effects of particle size. These facts indicate that DM is important for the compaction behavior, and batch-to-batch variability should also be considered. Therefore, pectins of low degree of methoxylation may have a potential as direct compression excipients.

‣ Illuminating the wall: Using click chemistry to image pectins in Arabidopsis cell walls

Anderson, Charles T.; Wallace, Ian S.
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
Publicado em 01/06/2012 Português
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Plant cell walls are the most abundant biomaterials on Earth and serve a multitude of purposes in human society. These complex extracellular matrices are mainly composed of polysaccharides, including cellulose, hemicelluloses, and pectins, which cannot be cytologically examined using conventional techniques. Click chemistry, which exploits a bio-orthogonal cycloaddition reaction between alkynyl and azido groups, has proven to be useful for the metabolic incorporation and detection of modified sugars in polysaccharides in animals, fungi, and bacteria, but its use to interrogate the biosynthesis or dynamics of plant cell walls has not been previously reported. Recently, we found that an alkynylated analog of fucose can be metabolically incorporated into Arabidopsis thaliana cell walls and click labeled with fluorescent probes, facilitating imaging of cell wall carbohydrates. Despite the presence of fucose in several classes of wall polysaccharides, fucose-alkyne was primarily incorporated into rhamnogalacturonan-I, a type of pectin. Using timecourse and pulse-labeling experiments, we observed the dynamics of pectin delivery and reorganization in expanding cell walls. The use of click chemistry to investigate plant cell wall architecture should help bridge the gap between biochemical characterization of isolated cell wall components and an understanding of how those components interact in intact cell walls.

‣ Rhamnogalacturonan-II cross-linking of plant pectins via boron bridges occurs during polysaccharide synthesis and/or secretion

Chormova, Dimitra; Messenger, David J; Fry, Stephen C
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
Publicado em 06/03/2014 Português
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Rhamnogalacturonan-II (RG-II), a domain of plant cell wall pectins, is able to cross-link with other RG-II domains through borate diester bridges. Although it is known to affect mechanical properties of the cell wall, the biochemical requirements and lifecycle of this cross-linking remain unclear. We developed a PAGE methodology to allow separation of monomeric and dimeric RG-II and used this to study the dynamics of cross-linking in vitro and in vivo. Rosa cells grown in medium with no added boron contained no RG-II dimers, although these re-appeared after addition of boron to the medium. However, other Rosa cultures which were unable to synthesize new polysaccharides did not show dimer formation. We conclude that RG-II normally becomes cross-linked intraprotoplasmically or during secretion, but not post-secretion.

‣ Characterization of Two Homogalacturonan Pectins with Immunomodulatory Activity from Green Tea

Wang, Huijun; Wei, Guodong; Liu, Fei; Banerjee, Gautam; Joshi, Manoj; Bligh, S. W. Annie; Shi, Songshan; Lian, Hui; Fan, Hongwei; Gu, Xuelan; Wang, Shunchun
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 04/06/2014 Português
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Two natural homogalacturonan (HG) pectins (MW ca. 20 kDa) were isolated from green tea based on their immunomodulatory activity. The crude tea polysaccharides (TPS1 and TPS2) were obtained from green tea leaves by hot water extraction and followed by 40% and 70% ethanol precipitation, respectively. Two homogenous water soluble polysaccharides (TPS1-2a and TPS1-2b) were obtained from TPS1 after purification with gel permeation, which gave a higher phagocytic effect than TPS2. A combination of composition, methylation and configuration analyses, as well as NMR (nuclear magnetic resonance) spectroscopy revealed that TPS1-2a and TPS1-2b were homogalacturonan (HG) pectins consisting of a backbone of 1,4-linked α-d-galacturonic acid (GalA) residues with 28.4% and 26.1% of carboxyl groups as methyl ester, respectively. The immunological assay results demonstrated that TPS1-2, which consisted mainly of HG pectins, showed phagocytosis-enhancing activity in HL-60 cells.

‣ Physical and chemical properties and antioxidant activity of modified and unmodified pectins extracted from orange bagasse

Venzon, Simoni Spohr
Fonte: Campo Mourao; Medianeira Publicador: Campo Mourao; Medianeira
Tipo: Dissertação de Mestrado
Português
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Modified pectin is a polysaccharide rich in galacturonic acid altered by pH adjustment and thermal treatment used especially as an anti-cancer agent. The aim of this work was to study the physical and chemical properties of modified and unmodified pectins extracted from orange bagasse by using citric and nitric acids. The galacturonic acid content, degree of esterification, Fourier Transform Infrared 30 Spectroscopy profile, molar mass, intrinsic viscosity, rheological properties and antioxidant activity of the pectins were evaluated. The modification process caused the de-esterification of pectins, responsible for improving the intestinal absorption of modified pectin and a decrease of molecular weight due to removal of neutral sugars, maintaining the linear chain of galacturonic acid. Such changes also caused a significant increase in the in vitro antioxidant activity and influenced the rheological properties of pectin, reducing its viscosity. This work showed that the modification of pectin from orange bagasse with citric and nitric acids altered its structural and physical characteristics as well as its biological activity toward a free-radical, suggesting that some functional properties related to antioxidant activity activity and absorption of nutrients may be increased.

‣ Cell wall composition regulates cell shape and growth behaviour in pollen tubes

Chebli, Youssef
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
Português
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L’une des particularités fondamentales caractérisant les cellules végétales des cellules animales est la présence de la paroi cellulaire entourant le protoplaste. La paroi cellulaire joue un rôle primordial dans (1) la protection du protoplaste, (2) est impliquée dans les mécanismes de filtration et (3) est le lieu de maintes réactions biochimiques nécessaires à la régulation du métabolisme et des propriétés mécaniques de la cellule. Les propriétés locales d’élasticité, d’extensibilité, de plasticité et de dureté des composants pariétaux déterminent la géométrie et la forme des cellules lors des processus de différentiation et de morphogenèse. Le but de ma thèse est de comprendre les rôles que jouent les différents composants pariétaux dans le modelage de la géométrie et le contrôle de la croissance des cellules végétales. Pour atteindre cet objectif, le modèle cellulaire sur lequel je me suis basé est le tube pollinique ou gamétophyte mâle. Le tube pollinique est une protubérance cellulaire qui se forme à partir du grain de pollen à la suite de son contact avec le stigmate. Sa fonction est la livraison des cellules spermatiques à l’ovaire pour effectuer la double fécondation. Le tube pollinique est une cellule à croissance apicale...

‣ The role of pectins in the regulation of plant defence responses against pathogens

Spadoni, Sara
Fonte: La Sapienza Publicador: La Sapienza
Tipo: Tese de Doutorado
Português
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Lucchese, Fernando Marra, Mauro De Dominicis, Raffaele

‣ Pectins as possible source of the copper involved in the green staining alteration of cv. Gordal table olives

Gallardo Guerrero, Lourdes; Hornero-Méndez, Dámaso; Mínguez Mosquera, María Isabel
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artículo Formato: 118 bytes; text/plain
Português
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6 pages, 2 figures.-- PMID: 12405770 [PubMed].-- Printed version published on Nov 6, 2002.; The pectic and pigment compositions and Ca and Cu contents of the alcohol-insoluble solid (AIS) residues were determined in cv. Gordal olives treated with NaOH solution and kept at different constant pH values (3.5−6.5). The same controls were made in table olives presenting green staining alteration. The ratio between the various pectin fractions of the more acid pH experiment samples remained similar in fruits not showing green staining. In altered fruits, the protopectin fraction was lower, and the calcium pectate or EDTA soluble pectins were higher. Regarding the presence of Ca and Cu in the AIS, it was observed that, whereas Ca levels fell at the most acid pH values, those of Cu increased. The concentration of Ca was higher in the AIS of altered olives than in nonaltered ones. The same trend was seen for the zone with or without green staining of an altered fruit. In the case of Cu, the relationship was the opposite: a decrease in the levels of AIS Cu in fruits and zones of fruits with green staining. This result was correlated with the highest concentration of Cu−chlorophyll complexes found in such samples and suggested that pectins might act as a reservoir of Cu involved in the alteration.; Peer reviewed

‣ Distribution of pectins in the pollen apertures of Oenothera hookeri.velans ster/+ster

Noher de Halac, I.; Cismondi, Inés Adriana; Rodríguez García, María I.; Famá, G.
Fonte: Centro Regional de Investigaciones Científicas y Tecnológicas (Mendoza, Argentina) Publicador: Centro Regional de Investigaciones Científicas y Tecnológicas (Mendoza, Argentina)
Tipo: Artículo
Português
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Cell wall pectins are some of the most complex biopolymers known, and yet their functions remain largely mysterious. The aim of this paper was to deepen the study of the spatial pattern of pectin distribution in the aperture of Oenothera hookeri.velans ster/+ster fertile pollen. We used "in situ" immunocytochemical techniques at electron microscopy, involving monoclonal antibodies JIM5 and JIM7 directed against pectin epitopes in fertile pollen grains of Oenothera hookeri.velans ster/+ster. The same region was also analyzed by classical cytochemistry for polysaccharide detection. Immunogold labelling at the JIM7 epitope showed only in mature pollen labelling mainly located at the intine endo-aperture region. Cytoplasmic structures near the plasma membrane of the vegetative cell showed no labelling gold grains. In the same pollen stage the labelling at the JIM5 epitope was mostly confined to a layer located in the limit between the endexine and the ektexine at the level of the border of the oncus. Some tubuli at the base of the ektexine showed also an accumulation of gold particles. No JIM5 label was demonstrated in the aperture chamber and either in any cytoplasmic structure of the pollen grains. The immunocytochemical technique, when compared with the traditional methods for non- cellulose polysaccharide cytochemistry is fare more sensitive and allows the univocal determination of temporal and spatial location of pectins recognized by the JIM7 and JIM5 MAbs.; We are grateful for the grant of the Research Council of Argentina (CONICET). The study was also supported by project no. PGC BMC 2000-1484 from the Spanish Ministerio de Ciencia y Tecnología.; Peer reviewed

‣ Pectin methyl esterases and pectins in normal and hyperhydric shoots of carnation cultured in vitro.

Saher, Shady; Piqueras, Abel; Hellín, Eladio; Olmos, Enrique
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 100864 bytes; application/msword
Português
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5 pages, 2 figures, 2 tables.; Control and hyperhydric micropropagated plantlets from three carnation cultivars have been used to study their pectin composition and the activity of pectin methyl esterases (PMEs; EC 3.1.1.11). Pectins are a highly heterogeneous group of polymers that contribute to cell adhesion, cell wall architecture, and cell wall mechanical strength. Pectins control cell wall porosity and cell wall ionic status and are implicated in intercellular space development. The degree of esterification of pectins is controlled by the activity of cell wall PMEs; their different actions can affect the properties of the cell wall, which have been considered important with respect to controlling the development of hyperhydricity. The total pectins of hyperhydric leaves of the three varieties were significantly reduced in comparison with controls. The pectate fraction was significantly increased in hyperhydric leaves of all varieties while soluble pectins and protopectins were significantly lower. The PME activity of hyperhydric leaves was higher (4–10 times) compared to controls of the three varieties. Isoelectric focusing of PME isozymes revealed the presence of three isoforms; neutral PME activity was the major isozyme in control and hyperhydric leaves of the three varieties...

‣ BEHAVIOUR OF AMIDATE PECTINS GELS IN THE PRESENCE OF DIFFERENT SWEETENERS AND SEVERAL CALCIUM CONTENTS; COMPORTAMENTO DE GÉIS DE PECTINAS EM PRESENÇA DE DIFERENTES ADOÇANTES E TEORES VARIADOS DE CÁLCIO*

CAMPOS, ADRIANE MULINARI; Universidade Católica do Paraná; CÂNDIDO, LYS MARY BILESKI; Universidade Federal do Paraná
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 08/05/2009 Português
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The effect of different sweeteners and the level of calcium on the strength of amidated pectins gels were studied. Model gels were prepared with 25, 35, 45 and 55 mg ca+2 / 9 pectin and the sweeteners sucrose, glucose, fructose, high maltose syrup, glucose syrup, invert sugar, sorbitol and the blends sucrose/sorbitol and manitol/sorbitol (25% soluble solida). Amidated low methoxyl pectins 8001 and 8002 (Braspectina) were added at the 0,8% level. Pectin 8001 was best adaptable to systems with sequestrant agents. Mode1 gels with fructose and sorbitol need 45 and 55 mg ca+2 / g pectin, respectively. pectin 8002 with 25 mg Ca+2 / g pectin give gels o f sucrose, glucose, high maltose syrup, glucose syrup and invert sugar more consistent than pectin 8001.; Géis modelo foram preparados para verificar o efeito de diferentes adoçantes e teores variados de cálcio sobre a força do gel de pectinas amidadas. O estudo foi realizado com 25, 35, 45 e 55 mg de cálcio/g de pectina e, com os adoçantes sacarose, glucose, frutose, xarope de alto teor de maltose, xarope de glucose, açúcar invertido, sorbitol e as misturas de frutose/sorbitol e manitol/sorbitol, em quantidade que totalizasse 25% de sólidos solúveis. Empregou-se o teor de 0...

‣ Distribution of pectins in the pollen apertures of Oenothera hookeri.velans ster/+ster:

Noher de Halac,I.; Cismondi,I.A.; Rodriguez-Garcia,M.I.; Famá,G.
Fonte: Biocell Publicador: Biocell
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2003 Português
Relevância na Pesquisa
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Cell wall pectins are some of the most complex biopolymers known, and yet their functions remain largely mysterious. The aim of this paper was to deepen the study of the spatial pattern of pectin distribution in the aperture of Oenothera hookeri.velans ster/+ster fertile pollen. We used "in situ" immunocytochemical techniques at electron microscopy, involving monoclonal antibodies JIM5 and JIM7 directed against pectin epitopes in fertile pollen grains of Oenothera hookeri.velans ster/+ster. The same region was also analyzed by classical cytochemistry for polysaccharide detection. Immunogold labelling at the JIM7 epitope showed only in mature pollen labelling mainly located at the intine endo-aperture region. Cytoplasmic structures near the plasma membrane of the vegetative cell showed no labelling gold grains. In the same pollen stage the labelling at the JIM5 epitope was mostly confined to a layer located in the limit between the endexine and the ektexine at the level of the border of the oncus. Some tubuli at the base of the ektexine showed also an accumulation of gold particles. No JIM5 label was demonstrated in the aperture chamber and either in any cytoplasmic structure of the pollen grains. The immunocytochemical technique, when compared with the traditional methods for non- cellulose polysaccharide cytochemistry is fare more sensitive and allows the univocal determination of temporal and spatial location of pectins recognized by the JIM7 and JIM5 MAbs.