WorldWideScience

Sample records for cell wall composition

  1. Bio-based composites that mimic the plant cell wall

    OpenAIRE

    Li, Zhuo

    2009-01-01

    Nature creates high performance materials under modest conditions, i.e., neutral pH and ambient temperature and pressure. One of the most significant materials is the plant cell wall. The plant cell wall is a composite of oriented cellulose microfibrils reinforcing a lignin/hemicellulose matrix. In principle, the plant cell wall composite is designed much like a synthetic fiber-reinforced polymer composite. Unlike synthetic composites, the plant cell wall has an excellent combination of h...

  2. Alfalfa stem tissues: Cell wall deposition, composition, and degradability

    NARCIS (Netherlands)

    Jung, H.G.; Engels, F.M.

    2002-01-01

    Declining cell wall degradability of alfalfa (Medicago sativa L.) stems with maturation limits the nutritional value of alfalfa for ruminants. This study characterized changes in cell wall concentration, composition, and degradability by rumen microbes resulting from alfalfa stem tissue proliferatio

  3. Cell wall composition of chlorococcal algae

    OpenAIRE

    Blumreisinger, Maria; Meindl, Doris; Loos, Eckhard

    1983-01-01

    The cell walls of representatives of the genera Chlorella, Monoraphidium, Ankistrodesmus and Scenedesmus contained 24–74% neutral sugars, 1–24% uronic acids, 2–16% protein and 0–15% glucosamine. Two types of cell walls could be discerned containing as main sugars either rhamnose and galactose or mannose and glucose with a lack of galactose.

  4. Determining the polysaccharide composition of plant cell walls.

    Science.gov (United States)

    Pettolino, Filomena A; Walsh, Cherie; Fincher, Geoffrey B; Bacic, Antony

    2012-09-01

    The plant cell wall is a chemically complex structure composed mostly of polysaccharides. Detailed analyses of these cell wall polysaccharides are essential for our understanding of plant development and for our use of plant biomass (largely wall material) in the food, agriculture, fabric, timber, biofuel and biocomposite industries. We present analytical techniques not only to define the fine chemical structures of individual cell wall polysaccharides but also to estimate the overall polysaccharide composition of cell wall preparations. The procedure covers the preparation of cell walls, together with gas chromatography-mass spectrometry (GC-MS)-based methods, for both the analysis of monosaccharides as their volatile alditol acetate derivatives and for methylation analysis to determine linkage positions between monosaccharide residues as their volatile partially methylated alditol acetate derivatives. Analysis time will vary depending on both the method used and the tissue type, and ranges from 2 d for a simple neutral sugar composition to 2 weeks for a carboxyl reduction/methylation linkage analysis. PMID:22864200

  5. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

    Directory of Open Access Journals (Sweden)

    Ying Luo

    Full Text Available The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

  6. Cell Wall

    OpenAIRE

    Jamet, Elisabeth; Canut, Hervé; Boudart, Georges; Albenne, Cécile; Pont-Lezica, Rafael F

    2008-01-01

    This chapter covers our present knowledge of cell wall proteomics highlighting the distinctive features of cell walls and cell wall proteins in relation to problems encountered for protein extraction, separation and identification. It provides clues to design strategies for efficient cell wall proteomic studies. It gives an overview of the kinds of proteins that have yet been identified: the expected proteins vs the identified proteins. Finally, the new vision of the cell wall proteome, and t...

  7. In-vitro fermentability of cell walls as influenced by lignin composition and cross-linking.

    Science.gov (United States)

    We assessed how diverse modifications in lignin composition and reductions in ferulate-lignin cross-linking influence the degradability of cell walls. Cell walls from nonlignified maize cell suspensions were artificially lignified with varying ratios of normal monolignols (coniferyl and sinapyl alco...

  8. Cell wall composition and candidate biosynthesis gene expression during rice development

    DEFF Research Database (Denmark)

    Lin, Fan; Manisseri, Chithra; Fagerström, Alexandra;

    2016-01-01

    strong hypotheses for genes that synthesize xylans, mixed linkage glucan and pectin components. This work provides an extensive analysis of cell wall composition throughout rice development, identifies genes likely to synthesize grass cell walls, and provides a framework for development of genetically...

  9. Genome-Wide Association Mapping for Cell Wall Composition and Properties in Temperate Grasses

    DEFF Research Database (Denmark)

    Bellucci, Andrea

    -glucans. Plant cell wall biosynthesis is regulated by a large number of genes and regulatory factors but very few of these are known and characterized. This PhD project aimed to the identification of putative candidate genes involved in plant cell wall composition and properties using a genome wide (GWAS...... with a wide range of chemical bounds. At present the interest in plant cell wall is growing due to the possibility to convert ligno-cellulosic biomass (e.g. agricultural residues) into bioethanol but also for the benefits to human health of some cell wall constituents found in cereals, in particular beta...

  10. Immuno and affinity cytochemical analysis of cell wall composition in the moss Physcomitrella patens

    Directory of Open Access Journals (Sweden)

    Elizabeth A. Berry

    2016-03-01

    Full Text Available In contrast to homeohydric vascular plants, mosses employ a poikilohydric strategy for surviving in the dry aerial environment. A detailed understanding of the structure, composition, and development of moss cell walls can contribute to our understanding of not only the evolution of overall cell wall complexity, but also the differences that have evolved in response to selection for different survival strategies. The model moss species Physcomitrella patens has a predominantly haploid lifecycle consisting of protonemal filaments that regenerate from protoplasts and enlarge by tip growth, and leafy gametophores composed of cells that enlarge by diffuse growth and differentiate into several different types. Advantages for genetic studies include methods for efficient targeted gene modification and extensive genomic resources. Immuno and affinity cytochemical labeling were used to examine the distribution of polysaccharides and proteins in regenerated protoplasts, protonemal filaments, rhizoids, and sectioned gametophores of P. patens. The cell wall composition of regenerated protoplasts was also characterized by flow cytometry. Crystalline cellulose was abundant in the cell walls of regenerating protoplasts and protonemal cells that developed on media of high osmolarity, whereas homogalacturonan was detected in the walls of protonemal cells that developed on low osmolarity media and not in regenerating protoplasts. Mannan was the major hemicellulose detected in all tissues tested. Arabinogalactan proteins were detected in different cell types by different probes, consistent with structural heterogeneity. The results reveal developmental and cell type specific differences in cell wall composition and provide a basis for analyzing cell wall phenotypes in knockout mutants.

  11. Immuno and Affinity Cytochemical Analysis of Cell Wall Composition in the Moss Physcomitrella patens.

    Science.gov (United States)

    Berry, Elizabeth A; Tran, Mai L; Dimos, Christos S; Budziszek, Michael J; Scavuzzo-Duggan, Tess R; Roberts, Alison W

    2016-01-01

    In contrast to homeohydric vascular plants, mosses employ a poikilohydric strategy for surviving in the dry aerial environment. A detailed understanding of the structure, composition, and development of moss cell walls can contribute to our understanding of not only the evolution of overall cell wall complexity, but also the differences that have evolved in response to selection for different survival strategies. The model moss species Physcomitrella patens has a predominantly haploid lifecycle consisting of protonemal filaments that regenerate from protoplasts and enlarge by tip growth, and leafy gametophores composed of cells that enlarge by diffuse growth and differentiate into several different types. Advantages for genetic studies include methods for efficient targeted gene modification and extensive genomic resources. Immuno and affinity cytochemical labeling were used to examine the distribution of polysaccharides and proteins in regenerated protoplasts, protonemal filaments, rhizoids, and sectioned gametophores of P. patens. The cell wall composition of regenerated protoplasts was also characterized by flow cytometry. Crystalline cellulose was abundant in the cell walls of regenerating protoplasts and protonemal cells that developed on media of high osmolarity, whereas homogalactuonan was detected in the walls of protonemal cells that developed on low osmolarity media and not in regenerating protoplasts. Mannan was the major hemicellulose detected in all tissues tested. Arabinogalactan proteins were detected in different cell types by different probes, consistent with structural heterogneity. The results reveal developmental and cell type specific differences in cell wall composition and provide a basis for analyzing cell wall phenotypes in knockout mutants. PMID:27014284

  12. Immuno and Affinity Cytochemical Analysis of Cell Wall Composition in the Moss Physcomitrella patens.

    Science.gov (United States)

    Berry, Elizabeth A; Tran, Mai L; Dimos, Christos S; Budziszek, Michael J; Scavuzzo-Duggan, Tess R; Roberts, Alison W

    2016-01-01

    In contrast to homeohydric vascular plants, mosses employ a poikilohydric strategy for surviving in the dry aerial environment. A detailed understanding of the structure, composition, and development of moss cell walls can contribute to our understanding of not only the evolution of overall cell wall complexity, but also the differences that have evolved in response to selection for different survival strategies. The model moss species Physcomitrella patens has a predominantly haploid lifecycle consisting of protonemal filaments that regenerate from protoplasts and enlarge by tip growth, and leafy gametophores composed of cells that enlarge by diffuse growth and differentiate into several different types. Advantages for genetic studies include methods for efficient targeted gene modification and extensive genomic resources. Immuno and affinity cytochemical labeling were used to examine the distribution of polysaccharides and proteins in regenerated protoplasts, protonemal filaments, rhizoids, and sectioned gametophores of P. patens. The cell wall composition of regenerated protoplasts was also characterized by flow cytometry. Crystalline cellulose was abundant in the cell walls of regenerating protoplasts and protonemal cells that developed on media of high osmolarity, whereas homogalactuonan was detected in the walls of protonemal cells that developed on low osmolarity media and not in regenerating protoplasts. Mannan was the major hemicellulose detected in all tissues tested. Arabinogalactan proteins were detected in different cell types by different probes, consistent with structural heterogneity. The results reveal developmental and cell type specific differences in cell wall composition and provide a basis for analyzing cell wall phenotypes in knockout mutants.

  13. Chemical composition and cell wall polysaccharide degradability of pith and rind tissues from mature maize internodes

    Science.gov (United States)

    Our study was undertaken to identify tissue-specific biochemical traits that may be targeted in breeding programs for improving forage digestibility. We compared cell wall chemical composition and 24- and 96-h in vitro degradabilities in separated pith and rind tissues from six maize inbred lines. A...

  14. Cell wall composition as a maize defense mechanism against corn borers

    Science.gov (United States)

    European and Mediterranean corn borers are two of the most economically important insect pests of maize in North America and southern Europe, respectively. Cell wall structure and composition were evaluated in pith and rind tissues of diverse inbred lines as possible corn borer resistance traits. Ce...

  15. Cell wall compositional changes during incubation of plant roots measured by mid-infrared diffuse reflectance spectroscopy and fiber analysis

    Science.gov (United States)

    Plant roots, particularly the constituents of root cell walls (hemicellulose, cellulose and lignin), are important contributors to soil organic matter. Little is known about the cell wall composition of many important crop species or compositional changes as roots decay. The objectives of this stu...

  16. Cell wall and lipid composition of Isosphaera pallida, a budding eubacterium from hot springs.

    Science.gov (United States)

    Giovannoni, S J; Godchaux, W; Schabtach, E; Castenholz, R W

    1987-06-01

    Isosphaera pallida is an unusual gliding, budding eubacterium recently isolated from North American hot springs. Electron micrographs of ultrathin sections revealed a cell wall atypical of eubacteria: two electrondense layers separated by an electron-transparent layer, with no evident peptidoglycan layer. Growth was not inhibited by penicillin. Cell walls were isolated from sheared cells by velocity sedimentation. The rigid-layer fraction, prepared from cell walls by treatment with boiling 10% sodium dodecyl sulfate, was hydrolyzed and chemically analyzed for muramic acid. This essential component of peptidoglycan was absent. Amino acid analysis demonstrated a proteinaceous wall structure. Pitlike surface structures seen in negatively stained whole cells and thin sections were correlated with periodically spaced perforations of the rigid sacculus. An analysis of the lipid composition of I. pallida revealed typical ester-linked lipids with unbranched fatty acids, in contrast to the isoprenyl ether-linked lipids of archaebacteria, which also have proteinaceous cell walls. Capnoids, unusual sulfonolipids which are present in gliding bacteria of the Cytophaga-Flexibacter group, were absent. PMID:3584067

  17. [Composition of cell walls of 2 mutant strains of Streptomyces chrysomallus].

    Science.gov (United States)

    Zaretskaia, M Sh; Nefelova, M V; Baratova, L A; Polin, A N

    1984-12-01

    The cell walls and peptidoglycans of two mutant strains, Streptomyces chrysomallus var. carotenoides and Streptomyces chrysomallus var. macrotetrolidi, were studied. The strains are organisms producing carotenes and antibiotics of the macrotetrolide group. By the qualitative composition of the peptidoglycans the mutants belong to Streptomyces and are similar. Their glycan portion consists of equimolar quantities of N-acetyl glucosamine and muramic acid. The peptide subunit is presented by glutamic acid, L, L-diaminopimelic acid, glycine and alanine. The molar ratio of alanine is 1.2-1.3. The mutant strains differ in the content of carbohydrates, total phosphorus and phosphorus belonging to teichoic acids. Teichoic acids of the cell walls of the both strains are of the ribitolhosphate nature. The cell walls of the mutants contain polysaccharides differing from teichoic acids and consisting of glucose, galactose, arabinose and fucose. The influence of the cell wall composition of the mutant strains on their morphology and metabolism and comparison of the data relative to the mutant strains with those relative to the starting strain are discussed.

  18. Bacterial Cell Wall-Induced Arthritis: Chemical Composition and Tissue Distribution of Four Lactobacillus Strains

    OpenAIRE

    Šimelyte, Egle; Rimpiläinen, Marja; Lehtonen, Leena; Zhang, Xiang; Toivanen, Paavo

    2000-01-01

    To study what determines the arthritogenicity of bacterial cell walls, cell wall-induced arthritis in the rat was applied, using four strains of Lactobacillus. Three of the strains used proved to induce chronic arthritis in the rat; all were Lactobacillus casei. The cell wall of Lactobacillus fermentum did not induce chronic arthritis. All arthritogenic bacterial cell walls had the same peptidoglycan structure, whereas that of L. fermentum was different. Likewise, all arthritogenic cell walls...

  19. Cell wall and phospholipid composition and their contribution to the salt tolerance of Halomonas elongata.

    OpenAIRE

    Vreeland, R H; Anderson, R; Murray, R G

    1984-01-01

    The salt-tolerant bacterium Halomonas elongata makes a variety of physiological adaptations in response to increases in the salt concentration of its growth medium. The cell walls become more compact and internally coherent. The overall lipid pattern shows an increased amount of negatively charged lipids. In addition, the peptidoglycan composition of H. elongata, although not changing in response to increased NaCl, contains the hydrophobic amino acid leucine which is unique among bacterial sp...

  20. Cell wall fermentation kinetics are impacted more by lignin content and ferulate cross-linking than by lignin composition

    Science.gov (United States)

    BACKGROUND: We used a biomimetic model system to ascertain how reductions in ferulate-lignin cross-linking and shifts in lignin composition influence ruminal cell wall fermentation. Primary walls from maize cell suspensions with normal or reduced feruloylation were artificially lignified with variou...

  1. Overexpression of SbMyb60 impacts phenylpropanoid biosynthesis and alters secondary cell wall composition in sorghum bicolor

    Science.gov (United States)

    The phenylpropanoid biosynthesis pathway that generates lignin subunits represents a significant target to alter the abundance and composition of lignin. The major regulators of phenylpropanoid metabolism are myb transcription factors, which have been shown to modulate secondary cell wall compositi...

  2. Nitrogen fertilization affects silicon concentration, cell wall composition and biofuel potential of wheat straw

    DEFF Research Database (Denmark)

    Murozuka, Emiko; Laursen, Kristian Holst; Lindedam, Jane;

    2014-01-01

    Nitrogen is an essential input factor required for plant growth and biomass production. However, very limited information is available on how nitrogen fertilization affects the quality of crop residues to be used as lignocellulosic feedstock. In the present study, straw of winter wheat plants grown...... at six different levels of nitrogen supply ranging from 48 to 288kg nitrogen ha-1 was analyzed for major cell wall components and mineral elements. Enzymatic digestion of the straw was carried out to evaluate the saccharification efficiency. The nitrogen concentration in the straw dry matter increased...... saccharification efficiency was negatively correlated with the rate of nitrogen supply. We conclude that the level of nitrogen supply to wheat plants alters the composition of cell wall components in the straw and that this may result in reduced saccharification efficiency. © 2014 Elsevier Ltd....

  3. Isolate-dependent growth, virulence, and cell wall composition in the human pathogen Aspergillus fumigatus.

    Directory of Open Access Journals (Sweden)

    Nansalmaa Amarsaikhan

    Full Text Available The ubiquitous fungal pathogen Aspergillus fumigatus is a mediator of allergic sensitization and invasive disease in susceptible individuals. The significant genetic and phenotypic variability between and among clinical and environmental isolates are important considerations in host-pathogen studies of A. fumigatus-mediated disease. We observed decreased radial growth, rate of germination, and ability to establish colony growth in a single environmental isolate of A. fumigatus, Af5517, when compared to other clinical and environmental isolates. Af5517 also exhibited increased hyphal diameter and cell wall β-glucan and chitin content, with chitin most significantly increased. Morbidity, mortality, lung fungal burden, and tissue pathology were decreased in neutropenic Af5517-infected mice when compared to the clinical isolate Af293. Our results support previous findings that suggest a correlation between in vitro growth rates and in vivo virulence, and we propose that changes in cell wall composition may contribute to this phenotype.

  4. Change in wall composition of transfer and aleurone cells during wheat grain development.

    Science.gov (United States)

    Robert, P; Jamme, F; Barron, C; Bouchet, B; Saulnier, L; Dumas, P; Guillon, F

    2011-02-01

    In addition to the starchy endosperm, a specialized tissue accumulating storage material, the endosperm of wheat grain, comprises the aleurone layer and the transfer cells next to the crease. The transfer cells, located at the ventral region of the grain, are involved in nutrient transfer from the maternal tissues to the developing endosperm. Immunolabeling techniques, Raman spectroscopy, and synchrotron infrared micro-spectroscopy were used to study the chemistry of the transfer cell walls during wheat grain development. The kinetic depositions of the main cell wall polysaccharides of wheat grain endosperm, arabinoxylan, and (1-3)(1-4)-β-glucan in transfer cell walls were different from kinetics previously observed in the aleurone cell walls. While (1-3)(1-4)-β-glucan appeared first in the aleurone cell walls at 90°D, arabinoxylan predominated in the transfer cell walls from 90 to 445°D. Both aleurone and transfer cell walls were enriched in (1-3)(1-4)-β-glucan at the mature stage of wheat grain development. Arabinoxylan was more substituted in the transfer cell walls than in the aleurone walls. However, arabinoxylan was more feruloylated in the aleurone than in the transfer cell walls, whatever the stage of grain development. In the transfer cells, the ferulic acid was less abundant in the outer periclinal walls while para-coumarate was absent. Possible implications of such differences are discussed.

  5. The constrained torsional analysis of thin-walled variable cross-section multi-cell laminated composite beams

    OpenAIRE

    Ahmed, Malik Nazir

    1999-01-01

    A Constrained Torsional Analysis of Thin-Walled Variable Cross-Section Multi-Cell Laminated Composite Beams has been undertaken . The existing Isotopic theory has been modified using the effective engineering elastic constants to cater for the Composite structures under torsional loads. The relevant computer programs for the Composite structure analysis have also been developed. The results are discussed in detail for single-cell and multi-cell prismatic/tapered beams for all [0/45/-45/90], l...

  6. Cell wall composition profiling of parasitic giant dodder (Cuscuta reflexa) and its hosts: a priori differences and induced changes.

    Science.gov (United States)

    Johnsen, Hanne R; Striberny, Bernd; Olsen, Stian; Vidal-Melgosa, Silvia; Fangel, Jonatan U; Willats, William G T; Rose, Jocelyn K C; Krause, Kirsten

    2015-08-01

    Host plant penetration is the gateway to survival for holoparasitic Cuscuta and requires host cell wall degradation. Compositional differences of cell walls may explain why some hosts are amenable to such degradation while others can resist infection. Antibody-based techniques for comprehensive profiling of cell wall epitopes and cell wall-modifying enzymes were applied to several susceptible hosts and a resistant host of Cuscuta reflexa and to the parasite itself. Infected tissue of Pelargonium zonale contained high concentrations of de-esterified homogalacturonans in the cell walls, particularly adjacent to the parasite's haustoria. High pectinolytic activity in haustorial extracts and high expression levels of pectate lyase genes suggest that the parasite contributes directly to wall remodeling. Mannan and xylan concentrations were low in P. zonale and in five susceptible tomato introgression lines, but high in the resistant Solanum lycopersicum cv M82, and in C. reflexa itself. Knowledge of the composition of resistant host cell walls and the parasite's own cell walls is useful in developing strategies to prevent infection by parasitic plants. PMID:25808919

  7. Cell wall and lipid composition of Isosphaera pallida, a budding eubacterium from hot springs.

    OpenAIRE

    Giovannoni, S J; Godchaux, W; Schabtach, E; Castenholz, R W

    1987-01-01

    Isosphaera pallida is an unusual gliding, budding eubacterium recently isolated from North American hot springs. Electron micrographs of ultrathin sections revealed a cell wall atypical of eubacteria: two electrondense layers separated by an electron-transparent layer, with no evident peptidoglycan layer. Growth was not inhibited by penicillin. Cell walls were isolated from sheared cells by velocity sedimentation. The rigid-layer fraction, prepared from cell walls by treatment with boiling 10...

  8. Divergent selection for ester-linked diferulates in maize pith stalk tissues. Effects on cell wall composition and degradability.

    Science.gov (United States)

    Barros-Rios, Jaime; Malvar, Rosa A; Jung, Hans-Joachim G; Bunzel, Mirko; Santiago, Rogelio

    2012-11-01

    Cross-linking of grass cell wall components through diferulates (DFAs) has a marked impact on cell wall properties. However, results of genetic selection for DFA concentration have not been reported for any grass species. We report here the results of direct selection for ester-linked DFA concentration in maize stalk pith tissues and the associated changes in cell wall composition and biodegradability. After two cycles of divergent selection, maize populations selected for higher total DFA (DFAT) content (CHs) had 16% higher DFAT concentrations than populations selected for lower DFAT content (CLs). These significant DFA concentration gains suggest that DFA deposition in maize pith parenchyma cell walls is a highly heritable trait that is genetically regulated and can be modified trough conventional breeding. Maize populations selected for higher DFAT had 13% less glucose and 10% lower total cell wall concentration than CLs, suggesting that increased cross-linking of feruloylated arabinoxylans results in repacking of the matrix and possibly in thinner and firmer cell walls. Divergent selection affected esterified DFAT and monomeric ferulate ether cross link concentrations differently, supporting the hypothesis that the biosynthesis of these cell wall components are separately regulated. As expected, a more higher DFA ester cross-coupled arabinoxylan network had an effect on rumen cell wall degradability (CLs showed 12% higher 24-h total polysaccharide degradability than CHs). Interestingly, 8-8-coupled DFAs, previously associated with cell wall strength, were the best predictors of pith cell wall degradability (negative impact). Thus, further research on the involvement of these specific DFA regioisomers in limiting cell wall biodegradability is encouraged. PMID:22938993

  9. Cell-wall architecture and lignin composition of wheat developed in a microgravity environment

    Science.gov (United States)

    Levine, L. H.; Heyenga, A. G.; Levine, H. G.; Choi, J.; Davin, L. B.; Krikorian, A. D.; Lewis, N. G.; Sager, J. C. (Principal Investigator)

    2001-01-01

    The microgravity environment encountered during space-flight has long been considered to affect plant growth and developmental processes, including cell wall biopolymer composition and content. As a prelude to studying how microgravity is perceived - and acted upon - by plants, it was first instructive to investigate what gross effects on plant growth and development occurred in microgravity. Thus, wheat seedlings were exposed to microgravity on board the space shuttle Discovery (STS-51) for a 10 day duration, and these specimens were compared with their counterparts grown on Earth under the same conditions (e.g. controls). First, the primary roots of the wheat that developed under both microgravity and 1 g on Earth were examined to assess the role of gravity on cellulose microfibril (CMF) organization and secondary wall thickening patterns. Using a quick freeze/deep etch technique, this revealed that the cell wall CMFs of the space-grown wheat maintained the same organization as their 1 g-grown counterparts. That is, in all instances, CMFs were randomly interwoven with each other in the outermost layers (farthest removed from the plasma membrane), and parallel to each other within the individual strata immediately adjacent to the plasma membranes. The CMF angle in the innermost stratum relative to the immediately adjacent stratum was ca 80 degrees in both the space and Earth-grown plants. Second, all plants grown in microgravity had roots that grew downwards into the agar; they did not display "wandering" and upward growth as previously reported by others. Third, the space-grown wheat also developed normal protoxylem and metaxylem vessel elements with secondary thickening patterns ranging from spiral to regular pit to reticulate thickenings. Fourthly, both the space- and Earth-grown plants were essentially of the same size and height, and their lignin analyses revealed no substantial differences in their amounts and composition regardless of the gravitational

  10. Impact of Cell Wall Composition on Maize Resistance to Pests and Diseases

    OpenAIRE

    Malvar, Rosa A.; Rogelio Santiago; Jaime Barros-Rios

    2013-01-01

    In cereals, the primary cell wall is built of a skeleton of cellulosic microfibrils embedded in a matrix of hemicelluloses and smaller amounts of pectins, glycoproteins and hydroxycinnamates. Later, during secondary wall development, p-coumaryl, coniferyl and sinapyl alcohols are copolymerized to form mixed lignins. Several of these cell wall components show a determinative role in maize resistance to pest and diseases. However, defense mechanisms are very complex and vary among t...

  11. Impact of Cell Wall Composition on Maize Resistance to Pests and Diseases

    Science.gov (United States)

    Santiago, Rogelio; Barros-Rios, Jaime; Malvar, Rosa A.

    2013-01-01

    In cereals, the primary cell wall is built of a skeleton of cellulosic microfibrils embedded in a matrix of hemicelluloses and smaller amounts of pectins, glycoproteins and hydroxycinnamates. Later, during secondary wall development, p-coumaryl, coniferyl and sinapyl alcohols are copolymerized to form mixed lignins. Several of these cell wall components show a determinative role in maize resistance to pest and diseases. However, defense mechanisms are very complex and vary among the same plant species, different tissues or even the same tissue at different developmental stages. Thus, it is important to highlight that the role of the cell wall components needs to be tested in diverse genotypes and specific tissues where the feeding or attacking by the pathogen takes place. Understanding the role of cell wall constituents as defense mechanisms may allow modifications of crops to withstand pests and diseases. PMID:23535334

  12. Following the compositional changes of fresh grape skin cell walls during the fermentation process in the presence and absence of maceration enzymes.

    Science.gov (United States)

    Zietsman, Anscha J J; Moore, John P; Fangel, Jonatan U; Willats, William G T; Trygg, Johan; Vivier, Melané A

    2015-03-18

    Cell wall profiling technologies were used to follow compositional changes that occurred in the skins of grape berries (from two different ripeness levels) during fermentation and enzyme maceration. Multivariate data analysis showed that the fermentation process yielded cell walls enriched in hemicellulose components because pectin was solubilized (and removed) with a reduction as well as exposure of cell wall proteins usually embedded within the cell wall structure. The addition of enzymes caused even more depectination, and the enzymes unravelled the cell walls enabling better access to, and extraction of, all cell wall polymers. Overripe grapes had cell walls that were extensively hydrolyzed and depolymerized, probably by natural grape-tissue-ripening enzymes, and this enhanced the impact that the maceration enzymes had on the cell wall monosaccharide profile. The combination of the techniques that were used is an effective direct measurement of the hydrolysis actions of maceration enzymes on the cell walls of grape berry skin.

  13. The composition of cell wall skeleton and outermost lipids of Mycobacterium vaccae is modified by ethambutol treatment.

    Science.gov (United States)

    Rumijowska-Galewicz, Anna; Korycka-Machała, Małgorzata; Lisowska, Katarzyna; Dziadek, Jarosław

    2008-01-01

    Ethambutol (EMB) is a first line drug in tuberculosis treatment inhibiting the biosynthesis of arabinogalactan, which is a component of the mycobacterial cell wall. The growth of Mycobacterium vaccae cells in the presence of EMB increases cell wall permeability, which was monitored by beta-sitosterol biotransformation. GC/MS and GLC/MS (gas chromatography/mass spectrometry) analysis revealed dramatic changes in the content of covalently bound mycolic acids and in molar ratio galactose (Gal) to arabinose (Ara) in the cell envelopes of EMB-treated cells. The detected variations in the compositions of fatty acids indicate that both the cell wall skeleton and outer layer (free lipids) are decomposed due to EMB treatment.

  14. Compositional changes in cell wall polysaccharides from apple fruit callus cultures modulated by different plant growth regulators.

    Science.gov (United States)

    Alayón-Luaces, Paula; Ponce, Nora M A; Mroginski, Luis A; Stortz, Carlos A; Sozzi, Gabriel O

    2012-04-01

    The cell wall composition of apples callus cultures showed changes in the presence of 5 mg l(-1) of three different plant growth regulators (PGRs), namely picloram, abscisic acid and gibberellic acid. Although the structural functions of cell walls do not generally allow for pronounced variations of the total pectin and matrix glycan content, this work provides evidence that the addition of these plant growth regulators can rule, at least partly, cell wall metabolism in apple callus cultures. The chelator- and carbonate-extracts always had the analytical characteristics of pectins, with high proportions of uronic acids, arabinose and galactose as the main monosaccharides, and a significant proportion of rhamnose, but the cross-linking glycan fractions were still rich in RG-I-like material. The application of PGRs produced shifts of uronic acid and neutral sugars between fractions. Arabinose was the neutral sugar exhibiting more variations in apple callus cell wall. Picloram and abscisic acid produced an increase of the uronic acid contents of the cell walls. The AIRs obtained from calluses treated with different PGRs did not show large amounts of high molecular weight products, as determined by size-exclusion chromatography. For the carbonate-extract only the callus treated with picloram displayed two separated peaks for products of different molecular weights. The chromatographic profiles for the 4% KOH-extract displayed two peaks for all the treatments, one very sharp with high molecular weight, and another one wider of smaller molecular weight, whereas the difference between treatments can only be appraised through the areas of the peaks. This is the first report on cell wall composition from fruit calluses supplemented with different PGRs.

  15. Architecture of dermatophyte cell Walls: Electron microscopic and biochemical analysis

    Science.gov (United States)

    Nozawa, Y.; Kitajima, Y.

    1984-01-01

    A review with 83 references on the cell wall structure of dermatophytes is presented. Topics discussed include separation and preparation of cell walls; microstructure of cell walls by electron microscopy; chemical composition of cell walls; structural model of cell walls; and morphological structure of cell walls.

  16. The composite architecture of the wood cell wall. Nanostructure investigations with x-ray scattering

    International Nuclear Information System (INIS)

    The present thesis is concerned with the structure of the wood cell wall at nanometer level, in particular with the arrangement of the nano-sized cellulose fibrils that reinforce the cell wall. In this work, small-angle x-ray scattering (SAXS) and wide-angle x-ray diffraction were applied to investigate the tilt angle of the cellulose fibrils with respect to the longitudinal cell axis (microfibril angle) in the major part of the cell wall, the S2 layer. A comparative SAXS study on four native wood species (spruce, pine, oak and beech) revealed a decrease of microfibril angles from up to 40 o in the very first annual rings near the pith to about 0 o near the Bark in all species. This decrease is interpreted in terms of a mechanical optimization by structural adaptations. In addition to the laboratory x-ray investigations, synchrotron x-ray microdiffraction was used to study the local orientation of the cellulose fibrils with a position resolution of 2 gm. A new technique based on unusual scattering geometry with the sample in cross section was developed. Using this technique adjacent spruce wood cells were shown to exhibit exclusively right handed cellulose helices in the major part of the cell wall. Moreover, it was found that, within the experimental accuracy, the microfibril angle was constant across the whole S2 layer. Synchrotron microdiffraction on single cell walls near drying fissures in bordered pits showed that the fissure orientation roughly follows the cellulose fibrils in the S2 layer. Quite in contrast, the orientation of fissures in pits of different type, namely cross field pits, was found to be up to 25 o different from the fibril orientation determined by SAXS in the laboratory. (author)

  17. Composition and architecture of the cell walls of grasses and the mechanisms of synthesis of cell wall polysaccharides. Final report for period September 1, 1988 - April 30, 2001

    Energy Technology Data Exchange (ETDEWEB)

    Carpita, Nicholas C.

    2001-10-18

    This program was devoted toward complete understanding of the polysaccharide structure and architecture of the primary cell walls grasses and cereals, and the biosynthesis of the mixed-linkage beta-glucane, a cellulose interacting polymer that is synthesized uniquely by grass species and close relatives. With these studies as focal point, the support from DOE was instrumental in the development of new analytical means that enabled us to characterize carbohydrate structure, to reveal new features of cell wall dynamics during cell growth, and to apply these techniques in other model organisms. The support by DOE in these basic studies was acknowledged on numerous occasions in review articles covering current knowledge of cell wall structure, architecture, dynamics, biosynthesis, and in all genes related to cell wall biogenesis.

  18. Incorporation of p-coumarates into the cell walls of alfalfa changes the lignin composition

    Science.gov (United States)

    In general, monocots can contain a significant amount of an ester-linked p-coumarate (pCA) in their cell walls, but its function is unclear. One hypothesis is that pCA aids in the formation of syringyl-rich regions during lignification. Alfalfa (Medicago sativa), a dicot, is a cultivated perennial f...

  19. Cell Wall Composition and Underlying QTL in an F1 Pseudo-Testcross Population of Switchgrass

    Energy Technology Data Exchange (ETDEWEB)

    Serba, Desalegn D.; Sykes, Robert W.; Gjersing, Erica L.; Decker, Stephen R.; Daverdin, Guillaume; Devos, Katrien M.; Brummer, E. Charles; Saha, Malay C.

    2016-09-01

    Natural genetic variation for reduced recalcitrance can be used to improve switchgrass for biofuel production. A full-sib switchgrass mapping population developed by crossing a lowland genotype, AP13, and upland genotype, VS16, was evaluated at three locations (Ardmore and Burneyville, OK and Watkinsville, GA). Biomass harvested after senescence in 2009 and 2010 was evaluated at the National Renewable Energy Laboratory (NREL) for sugar release using enzymatic hydrolysis and for lignin content and syringyl/guaiacyl lignin monomer (S/G) ratio using pyrolysis molecular beam mass spectrometry (py-MBMS). Glucose and xylose release ranged from 120 to 313 and 123 to 263 mg g-1, respectively, while lignin content ranged from 19 to 27% of the dry biomass. Statistically significant differences were observed among the genotypes and the environments for the cell wall composition traits. Regression analysis showed that a unit increase in lignin content reduced total sugar release by an average of 10 mg g-1. Quantitative trait loci (QTL) analysis detected 9 genomic regions underlying sugar release and 14 for lignin content. The phenotypic variation explained by the individual QTL identified for sugar release ranged from 4.5 to 9.4 and for lignin content from 3.8 to 11.1%. Mapping of the QTL regions to the switchgrass genome sequence (v1.1) found that some of the QTL colocalized with genes involved in carbohydrate processing and metabolism, plant development, defense systems, and transcription factors. The markers associated with QTL can be implemented in breeding programs to efficiently develop improved switchgrass cultivars for biofuel production.

  20. Metal ion effects on hydraulic conductivity of bacterial cellulose-pectin composites used as plant cell wall analogs.

    Science.gov (United States)

    McKenna, Brigid A; Kopittke, Peter M; Wehr, J Bernhard; Blamey, F Pax C; Menzies, Neal W

    2010-02-01

    Low concentrations of some trace metals markedly reduce root elongation rate and cause ruptures to root rhizodermal and outer cortical cells in the elongation zone. The interactions between the trace metals and plant components responsible for these effects are not well understood but may be linked to changes in water uptake, cell turgor and cell wall extensibility. An experiment was conducted to investigate the effects of Al, La, Cu, Gd, Sc and Ru on the saturated hydraulic conductivity of bacterial cellulose (BC)-pectin composites, used as plant cell wall analogs. Hydraulic conductivity was reduced to approximately 30% of the initial flow rate by 39 microM Al and 0.6 microM Cu, approximately 40% by 4.6 microM La, 3 microM Sc and 4.4 microM Ru and approximately 55% by 3.4 microM Gd. Scanning electron microscopy (SEM) revealed changes in the ultrastructure of the composites. The results suggest that trace metal binding decreases the hydraulic conductivity through changes in pectin porosity. The experiment illustrates the importance of metal interactions with pectin, and the implications of such an interaction in plant metal toxicity and in normal cell wall processes. PMID:20053181

  1. The Lamportian cell wall

    Energy Technology Data Exchange (ETDEWEB)

    Keiliszewski, M.; Lamport, D. (Michigan State Univ. Plant Research Lab., East Lansing (United States))

    1991-05-01

    The Lamportian Warp-Weft hypothesis suggests a cellulose-extensin interpenetrating network where extensin mechanically couples the load-bearing cellulose microfibrils in a wall matrix that is best described as a microcomposite. This model is based on data gathered from the extensin-rich walls of tomato and sycamore cell suspension culture, wherein extensin precursors are insolubilized into the wall by undefined crosslinks. The authors recent work with cell walls isolated from intact tissue as well as walls from suspension cultured cells of the graminaceous monocots maize and rice, the non-graminaceous monocot asparagus, the primitive herbaceous dicot sugar beet, and the gymnosperm Douglas Fir indicate that although extensins are ubiquitous to all plant species examined, they are not the major structural protein component of most walls examined. Amino acid analyses of intact and HF-treated walls shows a major component neither an HRGP, nor directly comparable to the glycine-rich wall proteins such as those associated with seed coat walls or the 67 mole% glycine-rich proteins cloned from petunia and soybean. Clearly, structural wall protein alternatives to extensin exist and any cell wall model must take that into account. If we assume that extracellular matrices are a priori network structures, then new Hypless' structural proteins in the maize cell wall raise questions about the sort of network these proteins create: the kinds of crosslinks involved; how they are formed; and the roles played by the small amounts of HRGPs.

  2. Identification of Quantitative Trait Loci Affecting Hemicellulose Characteristics Based on Cell Wall Composition in a Wild and Cultivated Rice Species

    Institute of Scientific and Technical Information of China (English)

    Si-Ju Zhang; Xue-Qin Song; Bai-Sheng Yu; Bao-Cai Zhang; Chuan-Qing Sun; J. Paul Knox; Yi-Hua Zhou

    2012-01-01

    Cell wall hemicellulosic polysaccharides are structurally complex and diverse.Knowledge about the synthesisof cell wall hemicelluloses and their biological roles is limited.Quantitative trait loci (QTL) mapping is a helpful tool for the dissection of complex phenotypes for gene identification.In this study,we exploited the natural variation in cell wall monosaccharide levels between a common wild rice,Yuanj,and an elite indica cultivar,Teqing,and performed QTL mapping with their introgression lines (ILs).Chemical analyses conducted on the culms of Yuanj and Teqing showed that the major alterations are found in glucose and xylose levels,which are correlated with specific hemicellulosic polymers.Glycosidic linkage examination revealed that,in Yuanj,an increase in glucose content results from a higher level of mixed linkage β-glucan (MLG),whereas a reduction in xylose content reflects a low level of xylan backbone and a varied arabinoxylan (AX) structure.Seventeen QTLs for monosaccharides have been identified through composition analysis of the culm residues of 95 core ILs.Four major QTLs affecting xylose and glucose levels are responsible for 19 and 21% of the phenotypic variance,respectively.This study provides a unique resource for the genetic dissection of rice cell wall formation and remodeling in the vegetative organs.

  3. Unique aspects of the grass cell wall

    Science.gov (United States)

    Grasses are amongst the most important crops worldwide, and the composition of their cell walls is critical for uses as food, feed, and energy crops. Grass cell walls differ dramatically from dicot cell walls in terms of the major structural polysaccharides present, how those polysaccharides are lin...

  4. Moss cell walls: structure and biosynthesis

    OpenAIRE

    Alison W. Roberts; Eric M Roberts; Haigler, Candace H.

    2012-01-01

    The genome sequence of the moss Physcomitrella patens has stimulated new research examining the cell wall polysaccharides of mosses and the glycosyl transferases that synthesize them as a means to understand fundamental processes of cell wall biosynthesis and plant cell wall evolution. The cell walls of mosses and vascular plants are composed of the same classes of polysaccharides, but with differences in side chain composition and structure. Similarly, the genomes of P. patens and angiosperm...

  5. Cell wall composition of tomato fruit changes during development and inhibition of vesicle trafficking is associated with reduced pectin levels and reduced softening.

    Science.gov (United States)

    Lunn, Daniel; Phan, Thanh D; Tucker, Gregory A; Lycett, Grantley W

    2013-05-01

    Fruit development entails a multitude of biochemical changes leading up to the mature green stage. During this period the cell wall will undergo complex compositional and structural changes. Inhibition of genes encoding elements of the machinery involved in trafficking to the cell wall presents us with a useful tool to study these changes and their associated phenotypes. An antisense SlRab11a transgene has previously been shown to reduce ripening-associated fruit softening. SlRab11a is highly expressed during fruit development which is associated with a period of pectin influx into the wall. We have analysed the cell wall polysaccharides at different stages of growth and ripening of wild type and antisense SlRab11a transgenic tomato (Solanum lycopersicum cv, Ailsa Craig) fruit. Our results demonstrated intriguing changes in cell wall composition during the development and ripening of wild type Alisa Craig tomato fruit. Analysis of SlRab11a expression by TaqMan PCR showed it to be expressed most strongly during growth of the fruit, suggesting a possible role in cell wall deposition. The SlRab11a antisense fruit had a decreased proportion of pectin in the cell wall compared with the wild type. We suggest a new approach for modification of fruit shelf-life by changing cell wall deposition rather than cell wall hydrolytic enzymes.

  6. Identification of Bacterial Cell Wall Lyases via Pseudo Amino Acid Composition

    Science.gov (United States)

    Tang, Hua; Li, Wen-Chao; Wu, Hao; Ding, Hui

    2016-01-01

    Owing to the abuse of antibiotics, drug resistance of pathogenic bacteria becomes more and more serious. Therefore, it is interesting to develop a more reasonable way to solve this issue. Because they can destroy the bacterial cell structure and then kill the infectious bacterium, the bacterial cell wall lyases are suitable candidates of antibacteria sources. Thus, it is urgent to develop an accurate and efficient computational method to predict the lyases. Based on the consideration, in this paper, a set of objective and rigorous data was collected by searching through the Universal Protein Resource (the UniProt database), whereafter a feature selection technique based on the analysis of variance (ANOVA) was used to acquire optimal feature subset. Finally, the support vector machine (SVM) was used to perform prediction. The jackknife cross-validated results showed that the optimal average accuracy of 84.82% was achieved with the sensitivity of 76.47% and the specificity of 93.16%. For the convenience of other scholars, we built a free online server called Lypred. We believe that Lypred will become a practical tool for the research of cell wall lyases and development of antimicrobial agents. PMID:27437396

  7. Identification of Bacterial Cell Wall Lyases via Pseudo Amino Acid Composition.

    Science.gov (United States)

    Chen, Xin-Xin; Tang, Hua; Li, Wen-Chao; Wu, Hao; Chen, Wei; Ding, Hui; Lin, Hao

    2016-01-01

    Owing to the abuse of antibiotics, drug resistance of pathogenic bacteria becomes more and more serious. Therefore, it is interesting to develop a more reasonable way to solve this issue. Because they can destroy the bacterial cell structure and then kill the infectious bacterium, the bacterial cell wall lyases are suitable candidates of antibacteria sources. Thus, it is urgent to develop an accurate and efficient computational method to predict the lyases. Based on the consideration, in this paper, a set of objective and rigorous data was collected by searching through the Universal Protein Resource (the UniProt database), whereafter a feature selection technique based on the analysis of variance (ANOVA) was used to acquire optimal feature subset. Finally, the support vector machine (SVM) was used to perform prediction. The jackknife cross-validated results showed that the optimal average accuracy of 84.82% was achieved with the sensitivity of 76.47% and the specificity of 93.16%. For the convenience of other scholars, we built a free online server called Lypred. We believe that Lypred will become a practical tool for the research of cell wall lyases and development of antimicrobial agents. PMID:27437396

  8. Impaired Chloroplast Biogenesis in Immutans, an Arabidopsis Variegation Mutant, Modifies Developmental Programming, Cell Wall Composition and Resistance to Pseudomonas syringae.

    Science.gov (United States)

    Pogorelko, Gennady V; Kambakam, Sekhar; Nolan, Trevor; Foudree, Andrew; Zabotina, Olga A; Rodermel, Steven R

    2016-01-01

    The immutans (im) variegation mutation of Arabidopsis has green- and white- sectored leaves due to action of a nuclear recessive gene. IM codes for PTOX, a plastoquinol oxidase in plastid membranes. Previous studies have revealed that the green and white sectors develop into sources (green tissues) and sinks (white tissues) early in leaf development. In this report we focus on white sectors, and show that their transformation into effective sinks involves a sharp reduction in plastid number and size. Despite these reductions, cells in the white sectors have near-normal amounts of plastid RNA and protein, and surprisingly, a marked amplification of chloroplast DNA. The maintenance of protein synthesis capacity in the white sectors might poise plastids for their development into other plastid types. The green and white im sectors have different cell wall compositions: whereas cell walls in the green sectors resemble those in wild type, cell walls in the white sectors have reduced lignin and cellulose microfibrils, as well as alterations in galactomannans and the decoration of xyloglucan. These changes promote susceptibility to the pathogen Pseudomonas syringae. Enhanced susceptibility can also be explained by repressed expression of some, but not all, defense genes. We suggest that differences in morphology, physiology and biochemistry between the green and white sectors is caused by a reprogramming of leaf development that is coordinated, in part, by mechanisms of retrograde (plastid-to-nucleus) signaling, perhaps mediated by ROS. We conclude that variegation mutants offer a novel system to study leaf developmental programming, cell wall metabolism and host-pathogen interactions. PMID:27050746

  9. Cell Wall Biomolecular Composition Plays a Potential Role in the Host Type II Resistance to Fusarium Head Blight in Wheat.

    Science.gov (United States)

    Lahlali, Rachid; Kumar, Saroj; Wang, Lipu; Forseille, Li; Sylvain, Nicole; Korbas, Malgorzata; Muir, David; Swerhone, George; Lawrence, John R; Fobert, Pierre R; Peng, Gary; Karunakaran, Chithra

    2016-01-01

    Fusarium head blight (FHB) is a serious disease of wheat worldwide. Cultivar resistance to FHB depends on biochemical factors that confine the pathogen spread in spikes. Breeding for cultivar resistance is considered the most practical way to manage this disease. In this study, different spectroscopy and microscopy techniques were applied to discriminate resistance in wheat genotypes against FHB. Synchrotron-based spectroscopy and imaging techniques, including focal plane array infrared and X-ray fluorescence (XRF) spectroscopy were used to understand changes in biochemical and nutrients in rachis following FHB infection. Sumai3 and Muchmore were used to represent resistant and susceptible cultivars to FHB, respectively, in this study. The histological comparison of rachis showed substantial differences in the cell wall thickness between the cultivars after infection. Synchrotron-based infrared imaging emphasized substantial difference in biochemical composition of rachis samples between the two cultivars prior to visible symptoms; in the resistant Sumai3, infrared bands representing lignin and hemicellulose were stronger and more persistent compared to the susceptible cultivar. These bands may be the candidates of biochemical markers for FHB resistance. Focal plane array infrared imaging (FPA) spectra from the rachis epidermis and vascular bundles revealed a new band (1710 cm(-1)) related to the oxidative stress on the susceptible cultivar only. XRF spectroscopy data revealed differences in nutrients composition between cultivars, and between controls and inoculated samples, with substantial increases observed for Ca, K, Mn, Fe, Zn, and Si in the resistant cultivar. These nutrients are related to cell wall stability, metabolic process, and plant defense mechanisms such as lignification pathway and callose deposition. The combination of cell wall composition and lignification plays a role in the mechanism of type II host resistance to FHB. Biochemical profiling

  10. Cell Wall Biomolecular Composition Plays a Potential Role in the Host Type II Resistance to Fusarium Head Blight in Wheat

    Science.gov (United States)

    Lahlali, Rachid; Kumar, Saroj; Wang, Lipu; Forseille, Li; Sylvain, Nicole; Korbas, Malgorzata; Muir, David; Swerhone, George; Lawrence, John R.; Fobert, Pierre R.; Peng, Gary; Karunakaran, Chithra

    2016-01-01

    Fusarium head blight (FHB) is a serious disease of wheat worldwide. Cultivar resistance to FHB depends on biochemical factors that confine the pathogen spread in spikes. Breeding for cultivar resistance is considered the most practical way to manage this disease. In this study, different spectroscopy and microscopy techniques were applied to discriminate resistance in wheat genotypes against FHB. Synchrotron-based spectroscopy and imaging techniques, including focal plane array infrared and X-ray fluorescence (XRF) spectroscopy were used to understand changes in biochemical and nutrients in rachis following FHB infection. Sumai3 and Muchmore were used to represent resistant and susceptible cultivars to FHB, respectively, in this study. The histological comparison of rachis showed substantial differences in the cell wall thickness between the cultivars after infection. Synchrotron-based infrared imaging emphasized substantial difference in biochemical composition of rachis samples between the two cultivars prior to visible symptoms; in the resistant Sumai3, infrared bands representing lignin and hemicellulose were stronger and more persistent compared to the susceptible cultivar. These bands may be the candidates of biochemical markers for FHB resistance. Focal plane array infrared imaging (FPA) spectra from the rachis epidermis and vascular bundles revealed a new band (1710 cm−1) related to the oxidative stress on the susceptible cultivar only. XRF spectroscopy data revealed differences in nutrients composition between cultivars, and between controls and inoculated samples, with substantial increases observed for Ca, K, Mn, Fe, Zn, and Si in the resistant cultivar. These nutrients are related to cell wall stability, metabolic process, and plant defense mechanisms such as lignification pathway and callose deposition. The combination of cell wall composition and lignification plays a role in the mechanism of type II host resistance to FHB. Biochemical profiling

  11. Estimation of indigestible NDF in forages and concentrates from cell wall composition

    DEFF Research Database (Denmark)

    Krämer, Monika; Weisbjerg, Martin Riis; Lund, Peter;

    2012-01-01

    within plant type, where INDF is defined as the portion of plant cell walls not digested after 288 h rumen incubation in Dacron bags with 12 μm pore size. INDF is one of the more important parameters determining the net energy (NE) value of a diet in some recently developed ruminant feed evaluation...... to develop regression equations for INDF intended for use in practice based on a total of 321 samples. Plant type and species within plant type affected (P... prediction accuracy compared to simple regression equations. Estimation of INDF in DM was more accurate than estimation of INDF in ash-free neutral detergent fibre (aNDFom). Results indicate that universal regression equations among plant types are not possible, and, within plant types, prediction equations...

  12. Effect of alkaline hydrogen peroxide treatment on cell wall composition and digestion kinetics of sugarcane residues and wheat straw.

    Science.gov (United States)

    Amjed, M; Jung, H G; Donker, J D

    1992-09-01

    Our objective was to characterize changes in cell wall composition and digestibility of sugarcane bagasse, pith from bagasse, and wheat straw after treatment with alkaline hydrogen peroxide (AHP). The AHP treatment solution contained 1% H2O2 (wt/vol) maintained at pH 11.5 with NaOH. The H2O2 in solution amounted to 25% of the quantity of substrate treated. After treatment, residues were washed and dried. Detergent fiber composition, total fiber components (neutral sugars, uronic acids, Klason lignin, and noncore lignin phenolic acids), IVDMD, in vitro digestion kinetics of NDF, and monosaccharide digestibilities (24 and 120 h) were determined. Total fiber (TF) and NDF concentrations of all treatment residues were increased (P less than .05) over control substrates by AHP because of greater losses of cell solubles than of cell wall constituents. Hemicellulose:cellulose ratio in NDF of treatment residues was decreased (P less than .05) by AHP for all substrates, but the neutral sugar composition of TF did not agree with this preferential loss of hemicellulose components. Klason lignin, ADL, and esterified noncore lignin, especially ferulic acid, were reduced (P less than .05) by AHP, whereas etherified noncore lignin composition was unchanged. Treatment increased (P less than .05) IVDMD, extent of NDF digestion, and monosaccharide digestibilities of all crop residues. The rate of NDF digestion was increased (P less than .05) for the sugarcane residues but not for wheat straw. Alkaline hydrogen peroxide improved crop residue digestibility, probably as a result of the removal of core and noncore lignin fractions. PMID:1328129

  13. Abnormal physiological properties and altered cell wall composition in Streptococcus pneumoniae grown in the presence of clavulanic acid.

    Science.gov (United States)

    Severin, A; Severina, E; Tomasz, A

    1997-01-01

    Subinhibitory concentrations of clavulanate caused premature induction of stationary-phase autolysis, sensitization to lysozyme, and reductions in the MICs of deoxycholate and penicillin for Streptococcus pneumoniae. In the range of clavulanate concentrations producing these effects, this beta-lactam compound was selectively bound to PBP 3. Cell walls isolated from pneumococci grown in the presence of clavulanate showed increased sensitivity to the hydrolytic action of purified pneumococcal autolysin in vitro. High-performance liquid chromatography analysis of the peptidoglycan isolated from the clavulanate-grown cells showed major qualitative and quantitative changes in stem peptide composition, the most striking feature of which was the accumulation of peptide species carrying intact D-alanyl-D-alanine residues at the carboxy termini. The altered biological and biochemical properties of the clavulanate-grown pneumococci appear to be the consequences of suppressed D,D-carboxypeptidase activity. PMID:9055983

  14. Plant density and maturity stage impacts on stem cell wall composition in high quality and non-lodging alfalfa

    Science.gov (United States)

    The concentration of stem cell wall constituents in alfalfa (Medicago sativa L.) can affect energy availability in livestock production systems and energy conversion efficiency when alfalfa is used to produce biofuels. Knowledge of the environmental variability of cell wall concentration and composi...

  15. Cell wall composition and digestibility alterations in Brachypodium distachyon achieved through reduced expression of the UDP-arabinopyranose mutase

    Science.gov (United States)

    Nucleotide-activated sugars are essential substrates for plant cell wall carbohydrate-polymer biosynthetic glycosyltransferase enzymes. The most prevalent sugars in grass cell walls include glucose (Glc), xylose (Xyl), and arabinose (Ara). These sugars are biosynthetically related via the uridine di...

  16. Roles of membrane trafficking in plant cell wall dynamics

    OpenAIRE

    Ebine, Kazuo; Ueda, Takashi

    2015-01-01

    The cell wall is one of the characteristic components of plant cells. The cell wall composition differs among cell types and is modified in response to various environmental conditions. To properly generate and modify the cell wall, many proteins are transported to the plasma membrane or extracellular space through membrane trafficking, which is one of the key protein transport mechanisms in eukaryotic cells. Given the diverse composition and functions of the cell wall in plants, the transpor...

  17. Revealing changes in molecular composition of plant cell walls on the micron-level by Raman mapping and vertex component analysis (VCA).

    Science.gov (United States)

    Gierlinger, Notburga

    2014-01-01

    At the molecular level the plant cell walls consist of a few nanometer thick semi-crystalline cellulose fibrils embedded in amorphous matrix polymers such as pectins, hemicelluloses, and lignins. The arrangement of these molecules within the cell wall in different plant tissues, cells and cell wall layers is of crucial importance for a better understanding and thus optimized utilization of plant biomass. During the last years Confocal Raman microscopy evolved as a powerful method in plant science by revealing the different molecules in context with the microstructure. In this study two-dimensional spectral maps have been acquired of micro-cross-sections of spruce (softwood) and beech (hardwood). Raman images have been derived by using univariate (band integration, height ratios) and multivariate methods [vertex component analysis (VCA)]. While univariate analysis only visualizes changes in selected band heights or areas, VCA separates anatomical regions and cell wall layers with the most different molecular structures. Beside visualization of the distinguished regions and features the underlying molecular structure can be derived based on the endmember spectra. VCA revealed that the lumen sided S3 layer has a similar molecular composition as the pit membrane, both revealing a clear change in lignin composition compared to all other cell wall regions. Within the S2 layer a lamellar structure was visualized, which was elucidated to derive from slight changes in lignin composition and content and might be due to successive but not uniform lignification during growth. PMID:25071792

  18. Cell Wall Biology: Perspectives from Cell Wall Imaging

    Institute of Scientific and Technical Information of China (English)

    Kieran J.D.Lee; Susan E.Marcus; J.Paul Knox

    2011-01-01

    Polysaccharide-rich plant cell walls are important biomaterials that underpin plant growth,are major repositories for photosynthetically accumulated carbon,and,in addition,impact greatly on the human use of plants. Land plant cell walls contain in the region of a dozen major polysaccharide structures that are mostly encompassed by cellulose,hemicelluloses,and pectic polysaccharides. During the evolution of land plants,polysaccharide diversification appears to have largely involved structural elaboration and diversification within these polysaccharide groups. Cell wall chemistry is well advanced and a current phase of cell wall science is aimed at placing the complex polysaccharide chemistry in cellular contexts and developing a detailed understanding of cell wall biology. Imaging cell wall glycomes is a challenging area but recent developments in the establishment of cell wall molecular probe panels and their use in high throughput procedures are leading to rapid advances in the molecular understanding of the spatial heterogeneity of individual cell walls and also cell wall differences at taxonomic levels. The challenge now is to integrate this knowledge of cell wall heterogeneity with an understanding of the molecular and physiological mechanisms that underpin cell wall properties and functions.

  19. Revealing changes in molecular composition of plant cell walls on the micron-level by Raman mapping and vertex component analysis (VCA

    Directory of Open Access Journals (Sweden)

    Notburga eGierlinger

    2014-06-01

    Full Text Available At the molecular level the plant cell walls consist of a few nanometer thick semi-crystalline cellulose fibrils embedded in amorphous matrix polymers such as pectins, hemicelluloses and lignins. The arrangement of these molecules within the cell wall in different plant tissues, cells and cell wall layers is of crucial importance for a better understanding and thus optimized utilization of plant biomass. During the last years Confocal Raman microscopy evolved as a powerful method in plant science by revealing the different molecules in context with the microstructure. In this study two-dimensional spectral maps have been acquired of micro-cross-sections of spruce (softwood and beech (hardwood. Raman images have been derived by using univariate (band integration, height ratios and multivariate methods (vertex component analysis, VCA. While univariate analysis only visualizes changes in selected band heights or areas, VCA separates anatomical regions and cell wall layers with the most different molecular structures by projecting the data to the identified orthogonal subspace in an interactive way and finding the endmember by repeated iteration. Beside visualization of the distinguished regions and features the underlying molecular structure can be derived based on the endmember spectra. Only one pure component spectrum (lignin from the cell corner was extracted, while all other endmember spectra represented mixtures characteristic for the different resolved spatial areas. VCA revealed that the lumen sided S3 layer has a similar molecular composition as the pit membrane, both revealing a clear change in lignin composition compared to all other cell wall regions. Within the S2 layer a lamellar structure was visualized, which was elucidated to derive also from slight changes in lignin composition and content and might be due to successive but not uniform lignification during growth.

  20. Phytoremediation of cadmium-contaminated soils by young Douglas fir trees: effects of cadmium exposure on cell wall composition.

    Science.gov (United States)

    Astier, Cédric; Gloaguen, Vincent; Faugeron, Céline

    2014-01-01

    Douglas fir trees grown on an artificially Cd-contaminated soil, can tolerate this trace element (up to 68 mg/kg in soil) during several months. Most of the absorbed Cd is retained in roots (25 mg/kg DM), but transfer to aerial part is also effective. Showing the highest content, up to 6 mg/kg DM, among all the aboveground parts, barks seem to be a preferred storage compartment. However, the transfer factor is quite low, about 0.3. Another objective of this study was to compare the cell wall components of trees exposed to increasing Cd amounts in soil. A decrease in lignin and an increase in pectin contents were observed in response to increasing soil cadmium concentration. A concurrent reduction in methyl-esterification of pectin suggests than the structure of this major binding site could therefore be modified as a reaction to cadmium contamination. Future prospects will focus on the modulation of pectin composition in response to Cd exposure.

  1. Sugar deficiency causes changes in cuticle permeability and cell wall composition that influence fruit postharvest shelf-life

    OpenAIRE

    Vallarino, J; Yeats, T.H.; Rose, J K; Fernie, A.R.; Osorio, S.

    2014-01-01

    The cuticle is a protective layer synthesized by epidermal cells of the plants and consisting of cutin covered and filled by waxes. In tomato (Solanum lycopersicum) fruit, the thick cuticle embedding epidermal cells has crucial roles in the control of pathogens, water loss, cracking, and postharvest shelf-life. Tomato fruits with reduced expression of the tomato gene LIN5 encoding cell wall invertase exhibits decreases transpirational water loss. Transcriptomic, biochemical, histological, and...

  2. Quantitative Trait Loci and Trait Correlations for Maize Stover Cell Wall Composition and Glucose Release for Cellulosic Ethanol

    Science.gov (United States)

    In cellulosic ethanol production, the efficiency of converting maize (Zea mays L.) stover into fermentable sugars partly depends on the stover cell wall structure. Breeding for improved stover quality for cellulosic ethanol may benefit from the use of molecular markers. However, limited quantitative...

  3. Cell wall composition of Bacillus subtilis changes as a function of pH and Zn²⁺ exposure: insights from cryo-XPS measurements.

    Science.gov (United States)

    Ramstedt, Madeleine; Leone, Laura; Persson, Per; Shchukarev, Andrey

    2014-04-22

    Bacteria play an important role in the biogeochemical cycling of metals in the environment. Consequently, there is an interest to understand how the bacterial surfaces interact with metals in solution and how this affects the bacterial surface. In this work we have used a surface-sensitive analysis technique, cryogenic X-ray photoelectron spectroscopy (cryo-XPS), to monitor the surface of Bacillus subtilis cells as a function of pH and Zn(2+) content in saline solution. The objective of the study was twofold: (1) to investigate the agreement between two data treatment methods for XPS, as well as investigate to what extent sample pretreatment may influence XPS data of bacterial samples, and (2) to characterize how the surface chemistry of bacterial cells is influenced by different external conditions. (1) It was found that the two data treatment methods gave rise to comparable results. However, identical samples analyzed fast-frozen or dry exhibited larger differences in surface chemistry, indicating that sample pretreatment can to large extents influence the obtained surface composition of bacterial samples. (2) The bacterial cell wall (in fast-frozen samples) undergoes dramatic compositional changes with pH and with Zn(2+) exposure. The compositional changes are interpreted as an adaptive metal resistance response changing the biochemical composition of the bacterial cell wall. These results have implications for how adsorption processes at the surface of bacterial cells are analyzed, understood, modeled, and predicted.

  4. 2003 Plant Cell Walls Gordon Conference

    Energy Technology Data Exchange (ETDEWEB)

    Daniel J. Cosgrove

    2004-09-21

    This conference will address recent progress in many aspects of cell wall biology. Molecular, genetic, and genomic approaches are yielding major advances in our understanding of the composition, synthesis, and architecture of plant cell walls and their dynamics during growth, and are identifying the genes that encode the machinery needed to make their biogenesis possible. This meeting will bring together international scientists from academia, industry and government labs to share the latest breakthroughs and perspectives on polysaccharide biosynthesis, wood formation, wall modification, expansion and interaction with other organisms, and genomic & evolutionary analyses of wall-related genes, as well as to discuss recent ''nanotechnological'' advances that take wall analysis to the level of a single cell.

  5. Fermentation of the endosperm cell walls of monocotyledon and dicotyledon plant species: The relationship between cell wall characteristics and fermentability

    NARCIS (Netherlands)

    Laar, van H.; Tamminga, S.; Williams, B.A.; Verstegen, M.W.A.

    2000-01-01

    Cell walls from the endosperm of four monocotyledons (maize, wheat, rye, and rice) and four dicotyledons (soya bean, lupin, faba bean, and pea) seeds were studied to relate cell wall composition and structure with fermentation characteristics. Cell wall material was isolated from the endosperm of th

  6. Combining multivariate analysis and monosaccharide composition modeling to identify plant cell wall variations by Fourier Transform Near Infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    Smith-Moritz Andreia M

    2011-08-01

    Full Text Available Abstract We outline a high throughput procedure that improves outlier detection in cell wall screens using FT-NIR spectroscopy of plant leaves. The improvement relies on generating a calibration set from a subset of a mutant population by taking advantage of the Mahalanobis distance outlier scheme to construct a monosaccharide range predictive model using PLS regression. This model was then used to identify specific monosaccharide outliers from the mutant population.

  7. ZmXTH1, a new xyloglucan endotransglucosylase/hydrolase in maize, affects cell wall structure and composition in Arabidopsis thaliana.

    Science.gov (United States)

    Genovesi, Valeria; Fornalé, Silvia; Fry, Stephen C; Ruel, Katia; Ferrer, Pau; Encina, Antonio; Sonbol, Fathi-Mohamed; Bosch, Josep; Puigdomènech, Pere; Rigau, Joan; Caparrós-Ruiz, David

    2008-01-01

    Xyloglucan endotransglucosylase/hydrolases (XTHs; EC 2.4.1.207 and/or EC 3.2.1.151) are enzymes involved in the modification of cell wall structure by cleaving and, often, also re-joining xyloglucan molecules in primary plant cell walls. Using a pool of antibodies raised against an enriched cell wall protein fraction, a new XTH cDNA in maize, ZmXTH1, has been isolated from a cDNA expression library obtained from the elongation zone of the maize root. The predicted protein has a putative N-terminal signal peptide and possesses the typical domains of this enzyme family, such as a catalytic domain that is homologous to that of Bacillus macerans beta-glucanase, a putative N-glycosylation motif, and four cysteine residues in the central and C terminal regions of the ZmXTH1 protein. Phylogenetic analysis of ZmXTH1 reveals that it belongs to subgroup 4, so far only reported from Poaceae monocot species. ZmXTH1 has been expressed in Pichia pastoris (a methylotrophic yeast) and the recombinant enzyme showed xyloglucan endotransglucosylase but not xyloglucan endohydrolase activity, representing the first enzyme belonging to subgroup 4 characterized in maize so far. Expression data indicate that ZmXTH1 is expressed in elongating tissues, modulated by culture conditions, and induced by gibberellins. Transient expression assays in onion cells reveal that ZmXTH1 is directed to the cell wall, although weakly bound. Finally, Arabidopsis thaliana plants expressing ZmXTH1 show slightly increased xyloglucan endohydrolase activity and alterations in the cell wall structure and composition. PMID:18316315

  8. Cell wall proteomics of crops

    OpenAIRE

    Komatsu, Setsuko; Yanagawa, Yuki

    2013-01-01

    Cell wall proteins play key roles in cell structure and metabolism, cell enlargement, signal transduction, responses to environmental stress, and many other physiological events. Agricultural crops are often used for investigating stress tolerance because cultivars with differing degrees of tolerance are available. Abiotic and biotic stress factors markedly influence the geographical distribution and yields of many crop species. Crop cell wall proteomics is of particular importance for improv...

  9. Aspergillus nidulans cell wall composition and function change in response to hosting several Aspergillus fumigatus UDP-galactopyranose mutase activity mutants.

    Directory of Open Access Journals (Sweden)

    Md Kausar Alam

    Full Text Available Deletion or repression of Aspergillus nidulans ugmA (AnugmA, involved in galactofuranose biosynthesis, impairs growth and increases sensitivity to Caspofungin, a β-1,3-glucan synthesis antagonist. The A. fumigatus UgmA (AfUgmA crystal structure has been determined. From that study, AfUgmA mutants with altered enzyme activity were transformed into AnugmA▵ to assess their effect on growth and wall composition in A. nidulans. The complemented (AnugmA::wild type AfugmA strain had wild type phenotype, indicating these genes had functional homology. Consistent with in vitro studies, AfUgmA residues R182 and R327 were important for its function in vivo, with even conservative amino (RK substitutions producing AnugmA? phenotype strains. Similarly, the conserved AfUgmA loop III histidine (H63 was important for Galf generation: the H63N strain had a partially rescued phenotype compared to AnugmA▵. Collectively, A. nidulans strains that hosted mutated AfUgmA constructs with low enzyme activity showed increased hyphal surface adhesion as assessed by binding fluorescent latex beads. Consistent with previous qPCR results, immunofluorescence and ELISA indicated that AnugmA▵ and AfugmA-mutated A. nidulans strains had increased α-glucan and decreased β-glucan in their cell walls compared to wild type and AfugmA-complemented strains. Like the AnugmA▵ strain, A. nidulans strains containing mutated AfugmA showed increased sensitivity to antifungal drugs, particularly Caspofungin. Reduced β-glucan content was correlated with increased Caspofungin sensitivity. Aspergillus nidulans wall Galf, α-glucan, and β-glucan content was correlated in A. nidulans hyphal walls, suggesting dynamic coordination between cell wall synthesis and cell wall integrity.

  10. Characterisation of cell wall polysaccharides in bilberries and black currants

    OpenAIRE

    Hilz, H

    2007-01-01

    During berry juice production, polysaccharides are released from the cell walls and cause thickening and high viscosity when the berries are mashed. Consequences are a low juice yield and a poor colour. This can be prevented by the use of enzymes that degrade these polysaccharides. To use these enzymes most efficiently, the structure and composition of the cell walls had to be known. This thesis describes a detailed composition of the cell walls of bilberries and black currants. The obtained ...

  11. Cell Wall Heterogeneity in Root Development of Arabidopsis

    Science.gov (United States)

    Somssich, Marc; Khan, Ghazanfar Abbas; Persson, Staffan

    2016-01-01

    Plant cell walls provide stability and protection to plant cells. During growth and development the composition of cell walls changes, but provides enough strength to withstand the turgor of the cells. Hence, cell walls are highly flexible and diverse in nature. These characteristics are important during root growth, as plant roots consist of radial patterns of cells that have diverse functions and that are at different developmental stages along the growth axis. Young stem cell daughters undergo a series of rapid cell divisions, during which new cell walls are formed that are highly dynamic, and that support rapid anisotropic cell expansion. Once the cells have differentiated, the walls of specific cell types need to comply with and support different cell functions. For example, a newly formed root hair needs to be able to break through the surrounding soil, while endodermal cells modify their walls at distinct positions to form Casparian strips between them. Hence, the cell walls are modified and rebuilt while cells transit through different developmental stages. In addition, the cell walls of roots readjust to their environment to support growth and to maximize nutrient uptake. Many of these modifications are likely driven by different developmental and stress signaling pathways. However, our understanding of how such pathways affect cell wall modifications and what enzymes are involved remain largely unknown. In this review we aim to compile data linking cell wall content and re-modeling to developmental stages of root cells, and dissect how root cell walls respond to certain environmental changes. PMID:27582757

  12. Cell Wall Heterogeneity in Root Development of Arabidopsis.

    Science.gov (United States)

    Somssich, Marc; Khan, Ghazanfar Abbas; Persson, Staffan

    2016-01-01

    Plant cell walls provide stability and protection to plant cells. During growth and development the composition of cell walls changes, but provides enough strength to withstand the turgor of the cells. Hence, cell walls are highly flexible and diverse in nature. These characteristics are important during root growth, as plant roots consist of radial patterns of cells that have diverse functions and that are at different developmental stages along the growth axis. Young stem cell daughters undergo a series of rapid cell divisions, during which new cell walls are formed that are highly dynamic, and that support rapid anisotropic cell expansion. Once the cells have differentiated, the walls of specific cell types need to comply with and support different cell functions. For example, a newly formed root hair needs to be able to break through the surrounding soil, while endodermal cells modify their walls at distinct positions to form Casparian strips between them. Hence, the cell walls are modified and rebuilt while cells transit through different developmental stages. In addition, the cell walls of roots readjust to their environment to support growth and to maximize nutrient uptake. Many of these modifications are likely driven by different developmental and stress signaling pathways. However, our understanding of how such pathways affect cell wall modifications and what enzymes are involved remain largely unknown. In this review we aim to compile data linking cell wall content and re-modeling to developmental stages of root cells, and dissect how root cell walls respond to certain environmental changes. PMID:27582757

  13. Absence of fks1p in lager brewing yeast results in aberrant cell wall composition and improved beer flavor stability.

    Science.gov (United States)

    Wang, Jin-jing; Xu, Wei-na; Li, Xin'er; Li, Jia; Li, Qi

    2014-06-01

    The flavor stability during storage is very important to the freshness and shelf life of beer. However, beer fermented with a yeast strain which is prone to autolyze will significantly affect the flavor of product. In this study, the gene encoding β-1,3-glucan synthetase catalytic subunit (fks1) of the lager yeast was destroyed via self-clone strategy. β-1,3-glucan is the principle cell wall component, so fks1 disruption caused a decrease in β-1,3-glucan level and increase in chitin level in cell wall, resulting in the increased cell wall thickness. Comparing with wild-type strain, the mutant strain had 39.9 and 63.41 % less leakage of octanoic acid and decanoic acid which would significantly affect the flavor of beer during storage. Moreover, the results of European Brewery Convention tube fermentation test showed that the genetic manipulation to the industrial brewing yeast helped with the anti-staling ability, rather than affecting the fermentation ability. The thiobarbituric acid value reduced by 65.59 %, and the resistant staling value increased by 26.56 %. Moreover, the anti-staling index of the beer fermented with mutant strain increased by 2.64-fold than that from wild-type strain respectively. China has the most production and consumption of beer around the world, so the quality of beer has a significant impact on Chinese beer industry. The result of this study could help with the improvement of the quality of beer in China as well as around the world.

  14. Characterization of the Sclerotinia sclerotiorum cell wall proteome.

    Science.gov (United States)

    Liu, Longzhou; Free, Stephen J

    2016-08-01

    We used a proteomic analysis to identify cell wall proteins released from Sclerotinia sclerotiorum hyphal and sclerotial cell walls via a trifluoromethanesulfonic acid (TFMS) digestion. Cell walls from hyphae grown in Vogel's glucose medium (a synthetic medium lacking plant materials), from hyphae grown in potato dextrose broth and from sclerotia produced on potato dextrose agar were used in the analysis. Under the conditions used, TFMS digests the glycosidic linkages in the cell walls to release intact cell wall proteins. The analysis identified 24 glycosylphosphatidylinositol (GPI)-anchored cell wall proteins and 30 non-GPI-anchored cell wall proteins. We found that the cell walls contained an array of cell wall biosynthetic enzymes similar to those found in the cell walls of other fungi. When comparing the proteins in hyphal cell walls grown in potato dextrose broth with those in hyphal cell walls grown in the absence of plant material, it was found that a core group of cell wall biosynthetic proteins and some proteins associated with pathogenicity (secreted cellulases, pectin lyases, glucosidases and proteases) were expressed in both types of hyphae. The hyphae grown in potato dextrose broth contained a number of additional proteins (laccases, oxalate decarboxylase, peroxidase, polysaccharide deacetylase and several proteins unique to Sclerotinia and Botrytis) that might facilitate growth on a plant host. A comparison of the proteins in the sclerotial cell wall with the proteins in the hyphal cell wall demonstrated that sclerotia formation is not marked by a major shift in the composition of cell wall protein. We found that the S. sclerotiorum cell walls contained 11 cell wall proteins that were encoded only in Sclerotinia and Botrytis genomes. PMID:26661933

  15. 14.7% efficient mesoscopic perovskite solar cells using single walled carbon nanotubes/carbon composite counter electrodes

    Science.gov (United States)

    Li, Hao; Cao, Kun; Cui, Jin; Liu, Shuangshuang; Qiao, Xianfeng; Shen, Yan; Wang, Mingkui

    2016-03-01

    A single walled carbon nanotube (SWCNT) possesses excellent hole conductivity. This work communicates an investigation of perovskite solar cells using a mesoscopic TiO2/Al2O3 structure as a framework in combination with a certain amount of SWCNT-doped graphite/carbon black counter electrode material. The CH3NH3PbI3-based device achieves a power conversion efficiency of 14.7% under AM 1.5G illumination. Detailed investigations show an increased charge collection in this device compared to that without the SWCNT additive.A single walled carbon nanotube (SWCNT) possesses excellent hole conductivity. This work communicates an investigation of perovskite solar cells using a mesoscopic TiO2/Al2O3 structure as a framework in combination with a certain amount of SWCNT-doped graphite/carbon black counter electrode material. The CH3NH3PbI3-based device achieves a power conversion efficiency of 14.7% under AM 1.5G illumination. Detailed investigations show an increased charge collection in this device compared to that without the SWCNT additive. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07347b

  16. Immobilization of cells via activated cell walls

    Energy Technology Data Exchange (ETDEWEB)

    Markt, M.; Kas, J.; Valentova, O.; Demnerova, K.; Vodrazka, Z.

    1986-10-01

    Cell walls of Saccharomyces cerevisiae and S. uvarum were activated by periodate oxidation of vicinal diol groups in cell wall polysaccharides. The aldehyde groups thus generated allow the yeast cells to be covalently bound to modified bead cellulose or macroporous glycidyl methacrylate supports, or to enzymes such as glucose oxidase and catalase. 6 references.

  17. Quantitative Prediction of Cell Wall Polysaccharide Composition in Grape (Vitis vinifera L.) and Apple (Malus domestica) Skins from Acid Hydrolysis Monosaccharide Profiles

    DEFF Research Database (Denmark)

    Arnous, Anis; Meyer, Anne S.

    2009-01-01

    On the basis of monosaccharide analysis after acid hydrolysis of fruit skin samples of three wine grape cultivars, Vitis vinifera L. Cabernet Sauvignon, Merlot, and Shiraz, and of two types of apple, Malus domestica Red Delicious and Golden Delicious, an iterative calculation method is reported......, 7 mol % arabinan, 4.5-5.0 mol % rhamnogalacturonan I, 3.5-4.0 mol % rhamnogalacturonan II, 3 mol % arabinogalactan, and 0.5-1.0 mol % mannans; the ranges indicate minor variations in the skin composition of the three different cultivars. These cell wall polysaccharides made up similar to 43...

  18. Cell wall integrity signaling and innate immunity in plants

    OpenAIRE

    Nühse, Thomas S.

    2012-01-01

    All plant pathogens and parasites have had to develop strategies to overcome cell walls in order to access the host’s cytoplasm. As a mechanically strong, multi-layered composite exoskeleton, the cell wall not only enables plants to grow tall but also protects them from such attacks. Many plant pathogens employ an arsenal of cell wall degrading enzymes, and it has long been thought that the detection of breaches in wall integrity contributes to the induction of defense. Cell wall fragments ar...

  19. Association Mapping of Cell Wall Synthesis Regulatory Genes and Cell Wall Quality in Switchgrass

    Energy Technology Data Exchange (ETDEWEB)

    Bartley, Laura [Univ. of Oklahoma, Norman, OK (United States). Dept. of Microbiology and Plant Biology; Wu, Y. [Oklahoma State Univ., Stillwater, OK (United States); Zhu, L. [Oklahoma State Univ., Stillwater, OK (United States); Brummer, E. C. [Noble Foundation, Ardmore, OK (United States); Saha, M. [Noble Foundation, Ardmore, OK (United States)

    2016-05-31

    Inefficient conversion of biomass to biofuels is one of the main barriers for biofuel production from such materials. Approximately half of polysaccharides in biomass remain unused by typical biochemical conversion methods. Conversion efficiency is influenced by the composition and structure of cell walls of biomass. Grasses such as wheat, maize, and rice, as well as dedicated perennial bioenergy crops, like switchgrass, make up ~55% of biomass that can be produced in the United States. Grass cell walls have a different composition and patterning compared with dicotyledonous plants, including the well-studied model plant, Arabidopsis. This project identified genetic determinants of cell wall composition in grasses using both naturally occurring genetic variation of switchgrass and gene network reconstruction and functional assays in rice. In addition, the project linked functional data in rice and other species to switchgrass improvement efforts through curation of the most abundant class of regulators in the switchgrass genome. Characterizing natural diversity of switchgrass for variation in cell wall composition and properties, also known as quality, provides an unbiased avenue for identifying biologically viable diversity in switchgrass cell walls. To characterizing natural diversity, this project generated cell wall composition and enzymatic deconstruction data for ~450 genotypes of the Switchgrass Southern Association Collection (SSAC), a diverse collection composed of 36 switchgrass accessions from the southern U.S. distribution of switchgrass. Comparing these data with other measures of cell wall quality for the same samples demonstrated the complementary nature of the diverse characterization platforms now being used for biomass characterization. Association of the composition data with ~3.2K single nucleotide variant markers identified six significant single nucleotide variant markers co-associated with digestibility and another compositional trait. These

  20. Characterization of Cell Wall Components and Their Modifications during Postharvest Storage of Asparagus officinalis L.: Storage-Related Changes in Dietary Fiber Composition.

    Science.gov (United States)

    Schäfer, Judith; Wagner, Steffen; Trierweiler, Bernhard; Bunzel, Mirko

    2016-01-20

    Changes in cell wall composition during storage of plant foods potentially alter the physiological effects of dietary fiber components. To investigate postharvest cell wall modifications of asparagus and their consequences in terms of insoluble dietary fiber structures, asparagus was stored at 20 and 1 °C for different periods of time. Structural analyses demonstrated postharvest changes in the polysaccharide profile, dominated by decreased portions of galactans. Increasing lignin contents correlated with compositional changes (monolignol ratios and linkage types) of the lignin polymer as demonstrated by chemical and two-dimensional nuclear magnetic resonance (2D-NMR) methods. Depending on the storage time and temperature, syringyl units were preferentially incorporated into the lignin polymer. Furthermore, a drastic increase in the level of ester-linked phenolic monomers (i.e., p-coumaric acid and ferulic acid) and polymer cross-links (di- and triferulic acids) was detected. The attachment of p-coumaric acid to lignin was demonstrated by 2D-NMR experiments. Potential consequences of postharvest modifications on physiological effects of asparagus dietary fiber are discussed.

  1. Characterization of Cell Wall Components and Their Modifications during Postharvest Storage of Asparagus officinalis L.: Storage-Related Changes in Dietary Fiber Composition.

    Science.gov (United States)

    Schäfer, Judith; Wagner, Steffen; Trierweiler, Bernhard; Bunzel, Mirko

    2016-01-20

    Changes in cell wall composition during storage of plant foods potentially alter the physiological effects of dietary fiber components. To investigate postharvest cell wall modifications of asparagus and their consequences in terms of insoluble dietary fiber structures, asparagus was stored at 20 and 1 °C for different periods of time. Structural analyses demonstrated postharvest changes in the polysaccharide profile, dominated by decreased portions of galactans. Increasing lignin contents correlated with compositional changes (monolignol ratios and linkage types) of the lignin polymer as demonstrated by chemical and two-dimensional nuclear magnetic resonance (2D-NMR) methods. Depending on the storage time and temperature, syringyl units were preferentially incorporated into the lignin polymer. Furthermore, a drastic increase in the level of ester-linked phenolic monomers (i.e., p-coumaric acid and ferulic acid) and polymer cross-links (di- and triferulic acids) was detected. The attachment of p-coumaric acid to lignin was demonstrated by 2D-NMR experiments. Potential consequences of postharvest modifications on physiological effects of asparagus dietary fiber are discussed. PMID:26671648

  2. Compositional changes in cell wall polysaccharides from five sweet cherry (Prunus avium L.) cultivars during on-tree ripening.

    Science.gov (United States)

    Basanta, María F; Ponce, Nora M A; Salum, María L; Raffo, María D; Vicente, Ariel R; Erra-Balsells, Rosa; Stortz, Carlos A

    2014-12-24

    Excessive softening is a major cause of postharvest deterioration during transportation and storage of fresh cherries. In continuing our studies to identify the factors determining the textural differences between sweet cherry fruit genotypes, we evaluated the solubilization, depolymerization, and monosaccharide composition of pectin and hemicelluloses from five sweet cherry cultivars ('Chelan', 'Sumele', 'Brooks', 'Sunburst', and 'Regina') with contrasting firmness and cracking susceptibility at two developmental stages (immature and ripe). In contrast to what is usually shown in most fruits, cherry softening could occur is some cultivars without marked increases in water-soluble pectin. Although polyuronide and hemicellulose depolymerization was observed in the water-soluble and dilute-alkali-soluble fractions, only moderate association occurs between initial polymer size and cultivar firmness. In all the genotypes the Na2CO3-soluble polysaccharides (NSF) represented the most abundant and dynamic wall fraction during ripening. Firm cultivars showed upon ripening a lower neutral sugars/uronic acid ratio in the NSF, suggesting that they have a lower proportion of highly branched polyuronides. The similar molar ratios of arabinose plus galactose to rhamnose [(Ara+Gal)/Rha] suggest that the cultivars differed in their relative proportion of homogalacturonan (HG) and rhamnogalacturonan I (RG-I) rather than in the size of the RG side chains; with greater proportions of HG in firmer cherries. Ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was useful to identify the depolymerization patterns of weakly bound pectins, but gave less accurate results on ionically bound pectins, and was unable to find any pattern on covalently bound pectins. PMID:25434844

  3. Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria.

    OpenAIRE

    Mistou, Michel-Yves; Sutcliffe, Iain; van Sorge, Nina

    2016-01-01

    The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall te...

  4. Shear-resistant behavior of light composite shear wall

    Institute of Scientific and Technical Information of China (English)

    李升才; 董毓利

    2015-01-01

    Shear test results for a composite wall panel in a light composite structure system are compared with test results for shear walls in Japan. The analysis results show that this kind of composite wall panel works very well, and can be regarded as a solid panel. The composite wall panel with a hidden frame is essential for bringing its effect on shear resistance into full play. Comprehensive analysis of the shear-resistant behavior of the composite wall panel suggests that the shear of the composite shear wall panel can be controlled by the cracking strength of the web shearing diagonal crack.

  5. Shear-Resistant Behavior Analysis of Light Composite Shear Walls

    Institute of Scientific and Technical Information of China (English)

    李升才; 江见鲸; 于庆荣

    2002-01-01

    Shear test results for a composite wall panel in a light composite structure system are compared with test results for shear walls in Japan in this paper. The analysis results show that this kind of composite wall panel works very well, and can be regarded as a solid panel. The composite wall panel with a hidden frame is essential for bringing its effect on shear resistance into full play. Comprehensive analysis of the shear-resistant behavior of the composite wall panel suggests that the shear of the composite shear wall panel can be controlled by the cracking strength of the web shearing diagonal crack.

  6. X-ray photoelectron emission spectromicroscopic analysis of arborescent lycopsid cell wall composition and Carboniferous coal ball preservation

    Energy Technology Data Exchange (ETDEWEB)

    Boyce, C. Kevin [Department of the Geophysical Sciences, University of Chicago, Chicago, IL 60637 (United States); Abrecht, Mike; Zhou, Dong; Gilbert, P.U.P.A. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)

    2010-08-01

    Two alternative processes complicate understanding of the biochemical origins and geochemical alteration of organic matter over geologic time: selective preservation of original biopolymers and in situ generation of new geopolymers. One of the best constrained potential sources of bio- and geochemical information about extinct fossil plants is frequently overlooked. Permineralized anatomically preserved plant fossils allow analysis of individual cell and tissue types that have an original biochemical composition already known from living plants. The original composition of more enigmatic fossils can be constrained by geochemical comparisons to tissues of better understood fossils from the same locality. This strategy is possible using synchrotron-based techniques for submicron-scale imaging with X-rays over a range of frequencies in order to provide information concerning the relative abundance of different organic bonds with X-ray Absorption Near Edge Spectroscopy. In this study, X-ray PhotoElectron Emission spectroMicroscopy (X-PEEM) was used to analyze the tissues of Lepidodendron, one of the lycopsid trees that were canopy dominants of many Pennsylvanian coal swamp forests. Its periderm or bark - the single greatest biomass contributor to many Late Paleozoic coals - is found to have a greater aliphatic content and an overall greater density of organic matter than lignified wood. Because X-PEEM allows simultaneous analysis of organic matter and matrix calcite in fully mineralized fossils, this technique also has great potential for analysis of fossil preservation, including documentation of significant traces of organic matter entrained in the calcite crystal fabric that fills the cell lumens. (author)

  7. Hemicellulose biosynthesis and degradation in tobacco cell walls

    NARCIS (Netherlands)

    Compier, M.G.M.

    2005-01-01

    Natural fibres have a wide range of technological applications, such as in paper and textile industries. The basic properties and the quality of plant fibres are determined by the composition of the plant cell wall. Characteristic for fibres are thick secondary cell walls, which consist of cellulose

  8. Transcript Profiling of Two Alfalfa Genotypes with Contrasting Cell Wall Composition in Stems Using a Cross-Species Platform: Optimizing Analysis by Masking Biased Probes

    Science.gov (United States)

    The stem cell walls of alfalfa [Medicago sativa (L.) ssp. sativa] genotype 252 have high cellulose and lignin concentrations, while stem cell walls of genotype 1283 have low cellulose and lignin concentrations. The GeneChip® Medicago Genome Array, developed for Medicago truncatula, is a suitable pla...

  9. Association Mapping of Cell Wall Synthesis Regulatory Genes and Cell Wall Quality in Switchgrass

    Energy Technology Data Exchange (ETDEWEB)

    Bartley, Laura [Univ. of Oklahoma, Norman, OK (United States). Dept. of Microbiology and Plant Biology; Wu, Y. [Oklahoma State Univ., Stillwater, OK (United States); Zhu, L. [Oklahoma State Univ., Stillwater, OK (United States); Brummer, E. C. [Noble Foundation, Ardmore, OK (United States); Saha, M. [Noble Foundation, Ardmore, OK (United States)

    2016-05-31

    Inefficient conversion of biomass to biofuels is one of the main barriers for biofuel production from such materials. Approximately half of polysaccharides in biomass remain unused by typical biochemical conversion methods. Conversion efficiency is influenced by the composition and structure of cell walls of biomass. Grasses such as wheat, maize, and rice, as well as dedicated perennial bioenergy crops, like switchgrass, make up ~55% of biomass that can be produced in the United States. Grass cell walls have a different composition and patterning compared with dicotyledonous plants, including the well-studied model plant, Arabidopsis. This project identified genetic determinants of cell wall composition in grasses using both naturally occurring genetic variation of switchgrass and gene network reconstruction and functional assays in rice. In addition, the project linked functional data in rice and other species to switchgrass improvement efforts through curation of the most abundant class of regulators in the switchgrass genome. Characterizing natural diversity of switchgrass for variation in cell wall composition and properties, also known as quality, provides an unbiased avenue for identifying biologically viable diversity in switchgrass cell walls. To characterizing natural diversity, this project generated cell wall composition and enzymatic deconstruction data for ~450 genotypes of the Switchgrass Southern Association Collection (SSAC), a diverse collection composed of 36 switchgrass accessions from the southern U.S. distribution of switchgrass. Comparing these data with other measures of cell wall quality for the same samples demonstrated the complementary nature of the diverse characterization platforms now being used for biomass characterization. Association of the composition data with ~3.2K single nucleotide variant markers identified six significant single nucleotide variant markers co-associated with digestibility and another compositional trait. These

  10. Transcript profiling of two alfalfa genotypes with contrasting cell wall composition in stems using a cross-species platform: optimizing analysis by masking biased probes

    Directory of Open Access Journals (Sweden)

    Jung Hans-Joachim G

    2010-05-01

    suggested co-expression of some neighbouring genes on Medicago chromosomes. Conclusions The problems associated with transcript profiling in alfalfa stems using the Medicago GeneChip as a CSH platform were mitigated by masking probes targeting ISV regions and SFPs. Using this masking protocol resulted in the identification of numerous candidate genes that may contribute to differences in cell wall concentration and composition of stems of two alfalfa genotypes.

  11. Cell Wall Integrity Signaling in Saccharomyces cerevisiae

    OpenAIRE

    Levin, David E.

    2005-01-01

    The yeast cell wall is a highly dynamic structure that is responsible for protecting the cell from rapid changes in external osmotic potential. The wall is also critical for cell expansion during growth and morphogenesis. This review discusses recent advances in understanding the various signal transduction pathways that allow cells to monitor the state of the cell wall and respond to environmental challenges to this structure. The cell wall integrity signaling pathway controlled by the small...

  12. Back wall solar cell

    Science.gov (United States)

    Brandhorst, H. W., Jr. (Inventor)

    1978-01-01

    A solar cell is disclosed which comprises a first semiconductor material of one conductivity type with one face having the same conductivity type but more heavily doped to form a field region arranged to receive the radiant energy to be converted to electrical energy, and a layer of a second semiconductor material, preferably highly doped, of opposite conductivity type on the first semiconductor material adjacent the first semiconductor material at an interface remote from the heavily doped field region. Instead of the opposite conductivity layer, a metallic Schottky diode layer may be used, in which case no additional back contact is needed. A contact such as a gridded contact, previous to the radiant energy may be applied to the heavily doped field region of the more heavily doped, same conductivity material for its contact.

  13. Accelerating forward genetics for cell wall deconstruction

    OpenAIRE

    Vidaurre, Danielle; Bonetta, Dario

    2012-01-01

    The elucidation of the genes involved in cell wall synthesis and assembly remains one of the biggest challenges of cell wall biology. Although traditional genetic approaches, using simple yet elegant screens, have identified components of the cell wall, many unknowns remain. Exhausting the genetic toolbox by performing sensitized screens, adopting chemical genetics or combining these with improved cell wall imaging, hold the promise of new gene discovery and function. With the recent introduc...

  14. Induction of innate immunity by Apergillus fumigatus cell wall polysaccharides is enhanced by the composite presentation of chitin and beta-glucan

    DEFF Research Database (Denmark)

    Dubey, L. K.; Moeller, J. B.; Schlosser, A.;

    2014-01-01

    Chitin and beta-glucan are conserved throughout evolution in the fungal cell wall and are the most common polysaccharides in fungal species. Together, these two polysaccharides form a structural scaffold that is essential for the survival of the fungus. In the present study, we demonstrated...... that Aspergillus fumigatus alkali-insoluble cell wall fragments (AIF), composed of chitin linked covalently to beta-glucan, induced enhanced immune responses when compared with individual cell wall polysaccharides. Intranasal administration of AIF induced eosinophil and neutrophil recruitment, chitinase activity......, TNF-alpha and TSLP production in mice lungs. Selective destruction of chitin or beta-glucan from AIF significantly reduced eosinophil and neutrophil recruitment as well as chitinase activity and cytokine expression by macrophages, indicating the synergistic effect of the cell wall polysaccharides when...

  15. The cell wall of Fusarium oxysporum

    NARCIS (Netherlands)

    Schoffelmeer, EAM; Klis, FM; Sietsma, JH; Cornelissen, BJC

    1999-01-01

    Sugar analysis of isolated cell walls from three formae speciales of Fusarium oxysporum showed that they contained not only glucose and (N-acetyl)-glucosamine, but also mannose, galactose, and uronic acids, presumably originating from cell wall glycoproteins. Cell wall glycoproteins accounted for 50

  16. Using RNA-Seq for gene identification, polymorphism detection and transcript profiling in two alfalfa genotypes with divergent cell wall composition in stems

    Directory of Open Access Journals (Sweden)

    Lamb JoAnn FS

    2011-04-01

    Full Text Available Abstract Background Alfalfa, [Medicago sativa (L. sativa], a widely-grown perennial forage has potential for development as a cellulosic ethanol feedstock. However, the genomics of alfalfa, a non-model species, is still in its infancy. The recent advent of RNA-Seq, a massively parallel sequencing method for transcriptome analysis, provides an opportunity to expand the identification of alfalfa genes and polymorphisms, and conduct in-depth transcript profiling. Results Cell walls in stems of alfalfa genotype 708 have higher cellulose and lower lignin concentrations compared to cell walls in stems of genotype 773. Using the Illumina GA-II platform, a total of 198,861,304 expression sequence tags (ESTs, 76 bp in length were generated from cDNA libraries derived from elongating stem (ES and post-elongation stem (PES internodes of 708 and 773. In addition, 341,984 ESTs were generated from ES and PES internodes of genotype 773 using the GS FLX Titanium platform. The first alfalfa (Medicago sativa gene index (MSGI 1.0 was assembled using the Sanger ESTs available from GenBank, the GS FLX Titanium EST sequences, and the de novo assembled Illumina sequences. MSGI 1.0 contains 124,025 unique sequences including 22,729 tentative consensus sequences (TCs, 22,315 singletons and 78,981 pseudo-singletons. We identified a total of 1,294 simple sequence repeats (SSR among the sequences in MSGI 1.0. In addition, a total of 10,826 single nucleotide polymorphisms (SNPs were predicted between the two genotypes. Out of 55 SNPs randomly selected for experimental validation, 47 (85% were polymorphic between the two genotypes. We also identified numerous allelic variations within each genotype. Digital gene expression analysis identified numerous candidate genes that may play a role in stem development as well as candidate genes that may contribute to the differences in cell wall composition in stems of the two genotypes. Conclusions Our results demonstrate that RNA

  17. Shape dynamics of growing cell walls

    CERN Document Server

    Banerjee, Shiladitya; Dinner, Aaron R

    2015-01-01

    We introduce a general theoretical framework to study the shape dynamics of actively growing and remodeling surfaces. Using this framework we develop a physical model for growing bacterial cell walls and study the interplay of cell shape with the dynamics of growth and constriction. The model allows us to derive constraints on cell wall mechanical energy based on the observed dynamics of cell shape. We predict that exponential growth in cell size requires a constant amount of cell wall energy to be dissipated per unit volume. We use the model to understand and contrast growth in bacteria with different shapes such as spherical, ellipsoidal, cylindrical and toroidal morphologies. Coupling growth to cell wall constriction, we predict a discontinuous shape transformation, from partial constriction to cell division, as a function of the chemical potential driving cell-wall synthesis. Our model for cell wall energy and shape dynamics relates growth kinetics with cell geometry, and provides a unified framework to d...

  18. [The effect of cytochalasin A on the composition of subcellular fractions of hyphae in the growth of Mucor mucedo. II. Composition of the cell wall].

    Science.gov (United States)

    el Mougith, A A; Fonvieille, J L; Dargent, R; Rami, J; Touzé-Soulet, J M

    1988-11-01

    Walls of young hyphae of Mucor mucedo L. growing in the presence or absence of cytochalasin A were isolated and their chemical content determined. Cytochalasin A induced modified proportions of various monomers resulting in a reduction of the (neutral sugars + glucuronic acid)/glucosamine ratio. The walls contained less proteins but more chitin-chitosan and phosphate. These modifications are discussed in relation to ultrastructural changes described previously.

  19. Changes of lipid domains in Bacillus subtilis cells with disrupted cell wall peptidoglycan

    OpenAIRE

    Muchová, Katarína; Wilkinson, Anthony J.; Barák, Imrich

    2011-01-01

    The cell wall is responsible for cell integrity and the maintenance of cell shape in bacteria. The Gram-positive bacterial cell wall consists of a thick peptidoglycan layer located on the outside of the cytoplasmic membrane. Bacterial cell membranes, like eukaryotic cell membranes, are known to contain domains of specific lipid and protein composition. Recently, using the membrane-binding fluorescent dye FM4-64, helix-like lipid structures extending along the long axis of the cell and consist...

  20. How cell wall complexity influences saccharification efficiency in Miscanthus sinensis.

    Science.gov (United States)

    De Souza, Amanda P; Alvim Kamei, Claire L; Torres, Andres F; Pattathil, Sivakumar; Hahn, Michael G; Trindade, Luisa M; Buckeridge, Marcos S

    2015-07-01

    The production of bioenergy from grasses has been developing quickly during the last decade, with Miscanthus being among the most important choices for production of bioethanol. However, one of the key barriers to producing bioethanol is the lack of information about cell wall structure. Cell walls are thought to display compositional differences that lead to emergence of a very high level of complexity, resulting in great diversity in cell wall architectures. In this work, a set of different techniques was used to access the complexity of cell walls of different genotypes of Miscanthus sinensis in order to understand how they interfere with saccharification efficiency. Three genotypes of M. sinensis displaying different patterns of correlation between lignin content and saccharification efficiency were subjected to cell wall analysis by quantitative/qualitative analytical techniques such as monosaccharide composition, oligosaccharide profiling, and glycome profiling. When saccharification efficiency was correlated negatively with lignin, the structural features of arabinoxylan and xyloglucan were found to contribute positively to hydrolysis. In the absence of such correlation, different types of pectins, and some mannans contributed to saccharification efficiency. Different genotypes of M. sinensis were shown to display distinct interactions among their cell wall components, which seem to influence cell wall hydrolysis. PMID:25908240

  1. Chemical Composition of Hypodermal and Endodermal Cell Walls and Xylem Vessels Isolated from Clivia miniata (Identification of the Biopolymers Lignin and Suberin).

    Science.gov (United States)

    Zeier, J.; Schreiber, L.

    1997-01-01

    The occurrence of the biopolymers lignin and suberin was investigated with hypodermal (HCW) and endodermal cell walls (ECW) and xylem vessels (XV) isolated from Clivia miniata Reg. roots. Both biopolymers were detected in HCW and ECW, whereas in XV, typical aliphatic suberin monomers were missing and only representative lignin monomers such as guaiacyl (G) and syringyl (S) units could be detected. The absolute amounts of lignin were about one order of magnitude higher compared with suberin in both HCW and ECW. The ratios of the two aromatic lignin units (G/S) decreased from 39 in XV and 10 in HCW to about 1 in ECW, indicating significant differences in lignin structure and function between the three investigated samples. Additionally, compared with the detectable lignin-derived aromatic units G and S, significantly higher amounts of esterified p-coumaric acid-derived aromatic monomers were obtained with HCW, but not with ECW. This is interpreted as a functional adaption of HCW toward pathogen defense at the root/soil interface. The final aim of this study was to provide a thorough chemical characterization of the composition of HCW, ECW, and XV, which in turn will form the basis for a better understanding of the relevant barriers toward the passive, radial, and apoplastic diffusion of solutes from the soil across the root cortex into the root cylinder. PMID:12223670

  2. Cell wall remodelling enzymes modulate fungal cell wall elasticity and osmotic stress resistance

    OpenAIRE

    Ene, Iuliana; Walker, Louise; Schiavone, Marion; Lee, Keunsook K.; Dague, Etienne; Gow, Neil A.R.; Munro, Carol A

    2015-01-01

    The fungal cell wall confers cell morphology and protection against environmental insults. For fungal pathogens, the cell wall is a key immunological modulator and an ideal therapeutic target. Yeast cell walls possess an inner matrix of interlinked β-glucan and chitin that is thought to provide tensile strength and rigidity. Yeast cells remodel their walls over time in response to environmental change, a process controlled by evolutionarily conserved stress (Hog1) and cell integrity (Mkc1, Ce...

  3. Regulation of Cell Wall Biogenesis in Saccharomyces cerevisiae: The Cell Wall Integrity Signaling Pathway

    OpenAIRE

    Levin, David E.

    2011-01-01

    The yeast cell wall is a strong, but elastic, structure that is essential not only for the maintenance of cell shape and integrity, but also for progression through the cell cycle. During growth and morphogenesis, and in response to environmental challenges, the cell wall is remodeled in a highly regulated and polarized manner, a process that is principally under the control of the cell wall integrity (CWI) signaling pathway. This pathway transmits wall stress signals from the cell surface to...

  4. The Utilization of Plant Facilities on the International Space Station—The Composition, Growth, and Development of Plant Cell Walls under Microgravity Conditions

    Directory of Open Access Journals (Sweden)

    Ann-Iren Kittang Jost

    2015-01-01

    Full Text Available In the preparation for missions to Mars, basic knowledge of the mechanisms of growth and development of living plants under microgravity (micro-g conditions is essential. Focus has centered on the g-effects on rigidity, including mechanisms of signal perception, transduction, and response in gravity resistance. These components of gravity resistance are linked to the evolution and acquisition of responses to various mechanical stresses. An overview is given both on the basic effect of hypergravity as well as of micro-g conditions in the cell wall changes. The review includes plant experiments in the US Space Shuttle and the effect of short space stays (8–14 days on single cells (plant protoplasts. Regeneration of protoplasts is dependent on cortical microtubules to orient the nascent cellulose microfibrils in the cell wall. The space protoplast experiments demonstrated that the regeneration capacity of protoplasts was retarded. Two critical factors are the basis for longer space experiments: a. the effects of gravity on the molecular mechanisms for cell wall development, b. the availability of facilities and hardware for performing cell wall experiments in space and return of RNA/DNA back to the Earth. Linked to these aspects is a description of existing hardware functioning on the International Space Station.

  5. The Utilization of Plant Facilities on the International Space Station-The Composition, Growth, and Development of Plant Cell Walls under Microgravity Conditions.

    Science.gov (United States)

    Jost, Ann-Iren Kittang; Hoson, Takayuki; Iversen, Tor-Henning

    2015-01-20

    In the preparation for missions to Mars, basic knowledge of the mechanisms of growth and development of living plants under microgravity (micro-g) conditions is essential. Focus has centered on the g-effects on rigidity, including mechanisms of signal perception, transduction, and response in gravity resistance. These components of gravity resistance are linked to the evolution and acquisition of responses to various mechanical stresses. An overview is given both on the basic effect of hypergravity as well as of micro-g conditions in the cell wall changes. The review includes plant experiments in the US Space Shuttle and the effect of short space stays (8-14 days) on single cells (plant protoplasts). Regeneration of protoplasts is dependent on cortical microtubules to orient the nascent cellulose microfibrils in the cell wall. The space protoplast experiments demonstrated that the regeneration capacity of protoplasts was retarded. Two critical factors are the basis for longer space experiments: a. the effects of gravity on the molecular mechanisms for cell wall development, b. the availability of facilities and hardware for performing cell wall experiments in space and return of RNA/DNA back to the Earth. Linked to these aspects is a description of existing hardware functioning on the International Space Station.

  6. Cell Wall Assembly in Saccharomyces cerevisiae

    OpenAIRE

    Lesage, Guillaume; Bussey, Howard

    2006-01-01

    An extracellular matrix composed of a layered meshwork of β-glucans, chitin, and mannoproteins encapsulates cells of the yeast Saccharomyces cerevisiae. This organelle determines cellular morphology and plays a critical role in maintaining cell integrity during cell growth and division, under stress conditions, upon cell fusion in mating, and in the durable ascospore cell wall. Here we assess recent progress in understanding the molecular biology and biochemistry of cell wall synthesis and it...

  7. How do plant cell walls extend?

    Science.gov (United States)

    Cosgrove, D. J.

    1993-01-01

    This article briefly summarizes recent work that identifies the biophysical and biochemical processes that give rise to the extension of plant cell walls. I begin with the biophysical notion of stress relaxation of the wall and follow with recent studies of wall enzymes thought to catalyze wall extension and relaxation. Readers should refer to detailed reviews for more comprehensive discussion of earlier literature (Taiz, 1984; Carpita and Gibeaut, 1993; Cosgrove, 1993).

  8. Microanalysis of Plant Cell Wall Polysaccharides

    Institute of Scientific and Technical Information of China (English)

    Nicolai Obel; Veronika Erben; Tatjana Schwarz; Stefan Kühne; Andrea Fodor; Markus Pauly

    2009-01-01

    Oligosaccharide Mass Profiling (OLIMP) allows a fast and sensitive assessment of cell wall polymer structure when coupled with Matrix Assisted Laser Desorption Ionisation Time Of Flight Mass Spectrometry (MALDI-TOF MS). The short time required for sample preparation and analysis makes possible the study of a wide range of plant organs, revealing a high degree of heterogeneity in the substitution pattern of wall polymers such as the cross-linking glycan xyloglucan and the pectic polysaccharide homogalacturonan. The high sensitivity of MALDI-TOF allows the use of small amounts of samples, thus making it possible to investigate the wall structure of single cell types when material is collected by such methods as laser micro-dissection. As an example, the analysis of the xyloglucan structure in the leaf cell types outer epidermis layer, entire epidermis cell layer, palisade mesophyll cells, and vascular bundles were investigated. OLIMP is amenable to in situ wall analysis, where wall polymers are analyzed on unprepared plant tissue itself without first iso-lating cell walls. In addition, OLIMP enables analysis of wall polymers in Golgi-enriched fractions, the location of nascent matrix polysaccharide biosynthesis, enabling separation of the processes of wall biosynthesis versus post-deposition apo-plastic metabolism. These new tools will make possible a semi-quantitative analysis of the cell wall at an unprecedented level.

  9. Modification of cell wall polysaccharides during retting of cassava roots.

    Science.gov (United States)

    Ngolong Ngea, Guillaume Legrand; Guillon, Fabienne; Essia Ngang, Jean Justin; Bonnin, Estelle; Bouchet, Brigitte; Saulnier, Luc

    2016-12-15

    Retting is an important step in traditional cassava processing that involves tissue softening of the roots to transform the cassava into flour and various food products. The tissue softening that occurs during retting was attributed to the degradation of cell wall pectins through the action of pectin-methylesterase and pectate-lyase that possibly originated from a microbial source or the cassava plant itself. Changes in cell wall composition were investigated during retting using chemical analysis, specific glycanase degradation and immuno-labelling of cell wall polysaccharides. Pectic 1,4-β-d-galactan was the main cell wall polysaccharide affected during the retting of cassava roots. This result suggested that better control of pectic galactan degradation and a better understanding of the degradation mechanism by endogenous endo-galactanase and/or exogenous microbial enzymes might contribute to improve the texture properties of cassava products. PMID:27451197

  10. WallProtDB, a database resource for plant cell wall proteomics

    OpenAIRE

    San Clemente, Hélène; Jamet, Elisabeth

    2015-01-01

    Background During the last fifteen years, cell wall proteomics has become a major research field with the publication of more than 50 articles describing plant cell wall proteomes. The WallProtDB database has been designed as a tool to facilitate the inventory, the interpretation of cell wall proteomics data and the comparisons between cell wall proteomes. Results WallProtDB (http://www.polebio.lrsv.ups-tlse.fr/WallProtDB/) presently contains 2170 proteins and ESTs identified experimentally i...

  11. Anthocyanins influence tannin-cell wall interactions.

    Science.gov (United States)

    Bautista-Ortín, Ana Belén; Martínez-Hernández, Alejandro; Ruiz-García, Yolanda; Gil-Muñoz, Rocío; Gómez-Plaza, Encarna

    2016-09-01

    The rate of tannin extraction was studied in a vinification of red grapes and the results compared with another vinification made with white grapes fermented as for typical red wine, in the presence of skins and seeds. Even though the grapes presented a quite similar skin and seed tannin content, the differences in tannin concentration between both vinifications was very large, despite the fact that the only apparent difference between the phenolic composition of both wines was the anthocyanin content. This suggests that anthocyanins play an important role in tannin extractability, perhaps because they affect the extent of the tannin-cell wall interaction, a factor that largely controls the resulting quantity of tannins in wines. To confirm this observation, the effect of anthocyanins on the tannin extractability from grape seeds and skin and on the interaction between tannins and grape cell walls suspended in model solutions were studied. The results indicated that anthocyanins favored skin and seed tannin extraction and that there is a competition for the adsorption sites between anthocyanins and tannins that increases the tannin content when anthocyanins are present. PMID:27041322

  12. Soya beans and Maize : The effect of chemical and physical structure of cell wall polysaccharides on fermentation kinetics

    OpenAIRE

    Laar, van de, P.

    2000-01-01

    The analysis of the relationship between cell wall composition and fermentation of endosperm cell walls of soya beans and maize was approached from three different angles. Firstly, the fermentation (rate and extent of fermentation, the sugar degradation pattern, and volatile fatty acid production) of soya bean and maize cell walls was analysed, both in situ and in vitro. This analysis revealed that the physical structure of the cell wall (particle size and cell wall thickness) influences cell...

  13. Cell wall proteins: a new insight through proteomics

    OpenAIRE

    Jamet, Elisabeth; Canut, Hervé; Boudart, Georges; Pont-Lezica, Rafael F

    2006-01-01

    Cell wall proteins are essential constituents of plant cell walls; they are involved in modifications of cell wall components, wall structure, signaling and interactions with plasma membrane proteins at the cell surface. The application of proteomic approaches to the cell wall compartment raises important questions: are there technical problems specific to cell wall proteomics? What kinds of proteins can be found in Arabidopsis walls? Are some of them unexpected? What sort of post-translation...

  14. Mutation of a family 8 glycosyltransferase gene alters cell wall carbohydrate composition and causes a humidity-sensitive semi-sterile dwarf phenotype in Arabidopsis.

    Science.gov (United States)

    Lao, Nga T; Long, Debbie; Kiang, Sophie; Coupland, George; Shoue, Douglas A; Carpita, Nicholas C; Kavanagh, Tony A

    2003-11-01

    The genome of Arabidopsis thaliana contains about 400 genes coding for glycosyltransferases, many of which are predicted to be involved in the synthesis and remodelling of cell wall components. We describe the isolation of a transposon-tagged mutant, parvus, which under low humidity conditions exhibits a severely dwarfed growth phenotype and failure of anther dehiscence resulting in semi-sterility. All aspects of the mutant phenotype were partially rescued by growth under high-humidity conditions, but not by the application of growth hormones or jasmonic acid. The mutation is caused by insertion of a maize Dissociation (Ds) element in a gene coding for a putative Golgi-localized glycosyltransferase belonging to family 8. Members of this family, originally identified on the basis of similarity to bacterial lipooligosaccharide glycosyltransferases, include enzymes known to be involved in the synthesis of bacterial and plant cell walls. Cell-wall carbohydrate analyses of the parvus mutant indicated reduced levels of rhamnogalacturonan I branching and alterations in the abundance of some xyloglucan linkages that may, however, be indirect consequences of the mutation. PMID:15010604

  15. Effects of light curing method and resin composite composition on composite adaptation to the cavity wall.

    Science.gov (United States)

    Yoshikawa, Takako; Morigami, Makoto; Sadr, Alireza; Tagami, Junji

    2014-01-01

    This study aimed to evaluate the effects of the light curing method and resin composite composition on marginal sealing and resin composite adaptation to the cavity wall. Cylindrical cavities were prepared on the buccal or lingual cervical regions. The teeth were restored using Clearfil Liner Bond 2V adhesive system and filled with Clearfil Photo Bright or Palfique Estelite resin composite. The resins were cured using the conventional or slow-start light curing method. After thermal cycling, the specimens were subjected to a dye penetration test. The slow-start curing method showed better resin composite adaptation to the cavity wall for both composites. Furthermore, the slow-start curing method resulted in significantly improved dentin marginal sealing compared with the conventional method for Clearfil Photo Bright. The light-cured resin composite, which exhibited increased contrast ratios duringpolymerization, seems to suggest high compensation for polymerization contraction stress when using the slow-start curing method.

  16. Penium margaritaceum: A Unicellular Model Organism for Studying Plant Cell Wall Architecture and Dynamics

    OpenAIRE

    Domozych, David S

    2014-01-01

    Penium margaritaceum is a new and valuable unicellular model organism for studying plant cell wall structure and developmental dynamics. This charophyte has a cell wall composition remarkably similar to the primary cell wall of many higher plants and clearly-defined inclusive zones containing specific polymers. Penium has a simple cylindrical phenotype with a distinct region of focused wall synthesis. Specific polymers, particularly pectins, can be identified using monoclonal antibodies rais...

  17. Histochemical effects of γ radiation on soft fruit cell walls

    International Nuclear Information System (INIS)

    Irradiation effects in peaches, tomatoes, cherries and grapes on the composition of cell wall polysaccharides were investigated by histochemical techniques. Cell wall polysaccharides, separated by a modified Jensen's method were pectins, hemicellulose, non-cellulosic polysaccharides and cellulose. The extinction values of Periodic Acid Schiff stained tissues was measured by microscopical photometry. Irradiation induced highly significant changes in polysaccharide composition of mesocarp cell walls; these changes were found to be a function of time of irradiation after harvest and of the species tested. A general influence on polysaccharide molecules was not found. Variations produced by irradiation are postulated to be an interference with a regulatory system rather than a breakdown of a functional molecule (metabolic enzyme or polysaccharide. (author)

  18. Accelerating forward genetics for cell wall deconstruction

    Directory of Open Access Journals (Sweden)

    Danielle eVidaurre

    2012-06-01

    Full Text Available One of the biggest challenges of cell wall biology is the elucidation of the genes involved the cell wall and their function due to the recalcitrance of the cell wall. Through traditional genetic approaches, many simple yet elegant screens have been able to identify components of the cell wall and their networks. Despite progress in the identification of several genes of the cell wall, there remain many unknown players whose function has yet to be determined. Exhausting the genetic toolbox by performing secondary screens on a genetically mutated background, chemical genetics using small molecules and improved cell wall imaging hold promise for new gene discovery and function. With the recent introduction of next-generation sequencing technologies, it is now possible to quickly and efficiently map and clone genes of interest in Arabidopsis and any model organism with a completed genome sequence. The combination of a classical genetics approach and cutting edge technology will propel cell wall biology of Arabidopsis and other useful crops forward into the future.

  19. Molecular regulation of plant cell wall extensibility

    Science.gov (United States)

    Cosgrove, D. J.

    1998-01-01

    Gravity responses in plants often involve spatial and temporal changes in cell growth, which is regulated primarily by controlling the ability of the cell wall to extend. The wall is thought to be a cellulose-hemicellulose network embedded in a hydrated matrix of complex polysaccharides and a small amount of structural protein. The wall extends by a form of polymer creep, which is mediated by expansins, a novel group of wall-loosening proteins. Expansins were discovered during a molecular dissection of the "acid growth" behavior of cell walls. Expansin alters the rheology of plant walls in profound ways, yet its molecular mechanism of action is still uncertain. It lacks detectable hydrolytic activity against the major components of the wall, but it is able to disrupt noncovalent adhesion between wall polysaccharides. The discovery of a second family of expansins (beta-expansins) sheds light on the biological role of a major group of pollen allergens and implies that expansins have evolved for diverse developmental functions. Finally, the contribution of other processes to wall extensibility is briefly summarized.

  20. Plant cell wall proteomics: the leadership of Arabidopsis thaliana

    OpenAIRE

    Albenne, Cécile; Canut, Hervé; Jamet, Elisabeth

    2013-01-01

    Plant cell wall proteins (CWPs) progressively emerged as crucial components of cell walls although present in minor amounts. Cell wall polysaccharides such as pectins, hemicelluloses, and cellulose represent more than 90% of primary cell wall mass, whereas hemicelluloses, cellulose, and lignins are the main components of lignified secondary walls. All these polymers provide mechanical properties to cell walls, participate in cell shape and prevent water loss in aerial organs. However, cell wa...

  1. Refractive index of plant cell walls

    Science.gov (United States)

    Gausman, H. W.; Allen, W. A.; Escobar, D. E.

    1974-01-01

    Air was replaced with media of higher refractive indices by vacuum infiltration in leaves of cucumber, blackeye pea, tomato, and string bean plants, and reflectance of noninfiltrated and infiltrated leaves was spectrophotometrically measured. Infiltrated leaves reflected less light than noninfiltrated leaves over the 500-2500-nm wavelength interval because cell wall-air interfaces were partly eliminated. Minimal reflectance should occur when the average refractive index of plant cell walls was matched by the infiltrating fluid. Although refractive indices that resulted in minimal reflectance differed among the four plant genera, an average value of 1.425 approximates the refractive index of plant cell walls for the four plant genera.

  2. Nanoindentation test and analysis of cell wall of strengthened composite wood%强化复合木材细胞壁的纳米压痕测试分析

    Institute of Scientific and Technical Information of China (English)

    林兰英; 傅峰

    2012-01-01

    通过纳米压痕测试技术,测定和分析了未处理材和经硅溶胶强化处理的复合木材细胞壁层面的力学性能和弹塑性,以及硅溶胶的存在位置对强化复合木材细胞壁微观力学性能的影响。结果表明:1)浸渍强化处理工艺可以使硅溶胶进入木材细胞壁,使得强化复合木材细胞壁的弹性模量和硬度达到18.64和0.64GPa,分别比未处理材提高59%和31%;2)控制改性处理工艺,可以得到改性细胞壁和既有改性细胞壁又有填充细胞腔2种改性形式的强化复合木材,并且2种改性形式下细胞壁层面上的弹性模量和硬度没有显著差异,证实了细胞腔填充对细胞壁层面的力学性能没有影响;3)复合木材细胞壁形貌表征和力学测试曲线表明,硅溶胶强化处理后的复合木材细胞壁保持了较好的弹塑性特性,相对弹性回复率与未处理材基本相同。%The mechanical properties and elastic-plastic of samples untreated and strengthened by silica sol using nanoindentation method were tested and analyzed. And the impacts of silica sol location on micro- mechanical properties of wood cell wall were also analyzed in this paper. The testing results indicated that: 1 ) the silica sol can be introduced into wood cell wall through impregnating process,and the modulus and hardness of cell wall of composite wood were 18. 64 and 0. 64 GPa,increased by 59% and 31% than untreated wood,respectively. 2) Two kinds of composite wood,the modified cell wall and the bulked cell wall,can be prepared through different vacuum-pressure processes,and the modulus and hardness of the two kinds of composite wood had no significant differences. It was indicated clearly that the filled lumina had no effects on the nano-mechanical properties of wood cell wall. 3 ) The cell wall morphology of the composite wood and testing curve analysis of nanoindentation showed that the wood cell wall after silica sol

  3. Cell wall proteomics of the green alga Haematococcus pluvialis (Chlorophyceae).

    Science.gov (United States)

    Wang, Sheng-Bing; Hu, Qiang; Sommerfeld, Milton; Chen, Feng

    2004-03-01

    The green microalga Haematococcus pluvialis can synthesize and accumulate large amounts of the ketocarotenoid astaxanthin, and undergo profound changes in cell wall composition and architecture during the cell cycle and in response to environmental stresses. In this study, cell wall proteins (CWPs) of H. pluvialis were systematically analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) coupled with peptide mass fingerprinting (PMF) and sequence-database analysis. In total, 163 protein bands were analyzed, which resulted in positive identification of 81 protein orthologues. The highly complex and dynamic composition of CWPs is manifested by the fact that the majority of identified CWPs are differentially expressed at specific stages of the cell cycle along with a number of common wall-associated 'housekeeping' proteins. The detection of cellulose synthase orthologue in the vegetative cells suggested that the biosynthesis of cellulose occurred during primary wall formation, in contrast to earlier observations that cellulose was exclusively present in the secondary wall of the organism. A transient accumulation of a putative cytokinin oxidase at the early stage of encystment pointed to a possible role in cytokinin degradation while facilitating secondary wall formation and/or assisting in cell expansion. This work represents the first attempt to use a proteomic approach to investigate CWPs of microalgae. The reference protein map constructed and the specific protein markers obtained from this study provide a framework for future characterization of the expression and physiological functions of the proteins involved in the biogenesis and modifications in the cell wall of Haematococcus and related organisms. PMID:14997492

  4. Homogenization of a viscoelastic model for plant cell wall biomechanics

    OpenAIRE

    Ptashnyk, Mariya; Seguin, Brian

    2015-01-01

    The microscopic structure of a plant cell wall is given by cellulose microfibrils embedded in a cell wall matrix. In this paper we consider a microscopic model for interactions between viscoelastic deformations of a plant cell wall and chemical processes in the cell wall matrix. We consider elastic deformations of the cell wall microfibrils and viscoelastic Kelvin--Voigt type deformations of the cell wall matrix. Using homogenization techniques (two-scale convergence and periodic unfolding me...

  5. Function of laccases in cell wall biosynthesis

    DEFF Research Database (Denmark)

    Larsen, Anders; Holm, Preben Bach; Andersen, Jeppe Reitan

    2011-01-01

    substrate specificities and expression patterns. As part of the strategic research centre Bio4Bio, the present project deals with laccase functions in relation to cell wall formation in grasses based on a study of the model species Brachypodium distachyon. Thirty-one isozymes have been retrieved from......Laccases are multicopper oxidases capable of polymerizing monolignols. Histochemical assays have shown temporal and spatial correlation with secondary cell wall formation in both herbs and woody perennials. However, in plants laccases constitutes a relatively large group of isoenzymes with unique...... hybridization. Specific isozymes that show high correlation with the process of secondary cell wall formation will be further studied in a reverse genetic study in which candidates will be knocked out using RNA interference. Phenotypes of knock-out mutants are to be described in relation to cell wall...

  6. Cell wall remodeling under abiotic stress

    OpenAIRE

    Tenhaken, Raimund

    2015-01-01

    Plants exposed to abiotic stress respond to unfavorable conditions on multiple levels. One challenge under drought stress is to reduce shoot growth while maintaining root growth, a process requiring differential cell wall synthesis and remodeling. Key players in this process are the formation of reactive oxygen species (ROS) and peroxidases, which initially cross-link phenolic compounds and glycoproteins of the cell walls causing stiffening. The function of ROS shifts after having converted a...

  7. Primary Cell Wall Structure in the Evolution of Land Plants

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Investigation of the primary cell walls of lower plants improves our understanding of the cell biology of these organisms but also has the potential to improve our understanding of cell wall structure and function in angiosperms that evolved from lower plants. Cell walls were prepared from eight species, ranging from a moss to advanced gymnosperms, and subjected to sequential chemical extraction to separate the main polysaccharide fractions. The glycosyl compositions of these fractions were then determined by gas chromatography. The results were compared among the eight plants and among data from related studies reported in the existing published reports to identify structural features that have been either highly conserved or clearly modified during evolution. Among the highly conserved features are the presence of a cellulose framework, the presence of certain hemicelluloses such as xyloglucan, and the presence of rhamnogalacturonan Ⅱ, a domain in pectic polysaccharides. Among the modified features are the abundance of mannosyl-containing hemicelluloses and the presence of methylated sugars.

  8. Titanium dioxide, single-walled carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Yuan; Li, Gonghu; Gray, Kimberly; Lueptow, Richard M.

    2015-07-14

    The present invention provides titanium dioxide/single-walled carbon nanotube composites (TiO.sub.2/SWCNTs), articles of manufacture, and methods of making and using such composites. In certain embodiments, the present invention provides membrane filters and ceramic articles that are coated with TiO.sub.2/SWCNT composite material. In other embodiments, the present invention provides methods of using TiO.sub.2/SWCNT composite material to purify a sample, such as a water or air sample.

  9. Cell-wall dynamics in growing bacteria

    Science.gov (United States)

    Furchtgott, Leon; Wingreen, Ned; Huang, Kerwyn Casey

    2010-03-01

    Bacterial cells come in a large variety of shapes, and cell shape plays an important role in the regulation of many biological functions. Cell shape in bacterial cells is dictated by a cell wall composed of peptidoglycan, a polymer made up of long, stiff glycan strands and flexible peptide crosslinks. Although much is understood about the structural properties of peptidoglycan, little is known about the dynamics of cell wall organization in bacterial cells. In particular, during cell growth, how does the bacterial cell wall continuously expand and reorganize while maintaining cell shape? In order to investigate this question quantitatively, we model the cell wall of the Gram-negative bacterium Escherichia coli using a simple elastic model, in which glycan and peptide subunits are treated as springs with different spring constants and relaxed lengths. We consider the peptidoglycan network as a single-layered network of these springs under tension due to an internal osmotic pressure. Within this model, we simulate possible hypotheses for cell growth as different combinations of addition of new springs and breakage of old springs.

  10. Modes of deformation of walled cells.

    Science.gov (United States)

    Dumais, Jacques

    2013-11-01

    The bewildering morphological diversity found in cells is one of the starkest illustrations of life's ability to self-organize. Yet the morphogenetic mechanisms that produce the multifarious shapes of cells are still poorly understood. The shared similarities between the walled cells of prokaryotes, many protists, fungi, and plants make these groups particularly appealing to begin investigating how morphological diversity is generated at the cell level. In this review, I attempt a first classification of the different modes of surface deformation used by walled cells. Five modes of deformation were identified: inextensional bending, equi-area shear, elastic stretching, processive intussusception, and chemorheological growth. The two most restrictive modes-inextensional and equi-area deformations-are embodied in the exine of pollen grains and the wall-like pellicle of euglenoids, respectively. For these modes, it is possible to express the deformed geometry of the cell explicitly in terms of the undeformed geometry and other easily observable geometrical parameters. The greatest morphogenetic power is reached with the processive intussusception and chemorheological growth mechanisms that underlie the expansive growth of walled cells. A comparison of these two growth mechanisms suggests a possible way to tackle the complexity behind wall growth.

  11. Cell wall integrity signalling in human pathogenic fungi.

    Science.gov (United States)

    Dichtl, Karl; Samantaray, Sweta; Wagener, Johannes

    2016-09-01

    Fungi are surrounded by a rigid structure, the fungal cell wall. Its plasticity and composition depend on active regulation of the underlying biosynthesis and restructuring processes. This involves specialised signalling pathways that control gene expression and activities of biosynthetic enzymes. The cell wall integrity (CWI) pathway is the central signalling cascade required for the adaptation to a wide spectrum of cell wall perturbing conditions, including heat, oxidative stress and antifungals. In the recent years, great efforts were made to analyse the CWI pathway of diverse fungi. It turned out that the CWI signalling cascade is mostly conserved in the fungal kingdom. In this review, we summarise as well as compare the current knowledge on the canonical CWI pathway in the human pathogenic fungi Candida albicans, Candida glabrata, Aspergillus fumigatus and Cryptococcus neoformans. Understanding the differences and similarities in the stress responses of these organisms could become a key to improving existing or developing new antifungal therapies. PMID:27155139

  12. A Composite Steel Plate Shear Walls for Offshore Constructions

    Directory of Open Access Journals (Sweden)

    Badri Albarody Thar M.

    2014-07-01

    Full Text Available A new-type of weldable composite steel plate shear wall, which consists of a steel plate sandwiched by either of two or one composite panels at each side or at one side, has been proposed. An analytical model for such shear wall – via shell model is derived and the vibrational modes are discussed. Truss reinforcement is used to increase the integration between the steel and composite layers and the cross sectional properties were graded by magnetic nanoparticles fillers. The thickness shear modes at the composite wall appear higher than those of thickness stretch modes, but they are varied in a very orderly manner with respect to the vibrational mode. Also, some of characteristics are examined.

  13. Profiling the Hydrolysis of Isolated Grape Berry Skin Cell Walls by Purified Enzymes.

    Science.gov (United States)

    Zietsman, Anscha J J; Moore, John P; Fangel, Jonatan U; Willats, William G T; Vivier, Melané A

    2015-09-23

    The unraveling of crushed grapes by maceration enzymes during winemaking is difficult to study because of the complex and rather undefined nature of both the substrate and the enzyme preparations. In this study we simplified both the substrate, by using isolated grape skin cell walls, and the enzyme preparations, by using purified enzymes in buffered conditions, to carefully follow the impact of the individual and combined enzymes on the grape skin cell walls. By using cell wall profiling techniques we could monitor the compositional changes in the grape cell wall polymers due to enzyme activity. Extensive enzymatic hydrolysis, achieved with a preparation of pectinases or pectinases combined with cellulase or hemicellulase enzymes, completely removed or drastically reduced levels of pectin polymers, whereas less extensive hydrolysis only opened up the cell wall structure and allowed extraction of polymers from within the cell wall layers. Synergistic enzyme activity was detectable as well as indications of specific cell wall polymer associations.

  14. "Steiner trees" between cell walls of sisal

    Institute of Scientific and Technical Information of China (English)

    LI GuanShi; YIN YaJun; LI Yan; ZHONG Zheng

    2009-01-01

    Through careful analysis on the cross-section of sisal fibers,it is found that the middle lamellae between the cell walls have clear geometric characteristics:between the cell walls of three neighboring cells,the middle lamellae form a three-way junction with 120°symmetry. If the neighboring three-way junctions are connected,a network of Steiner tree with angular symmetry and topological invariability is formed. If more and more Steiner trees are connected,a network of Steiner rings is generated. In another word,idealized cell walls and the middle lamellae are dominated by the Steiner geometry. This geometry not only depicts the geometric symmetry,the topological invariability and minimal property of the middle lamellae,but also controls the mechanics of sisal fibers.

  15. Antisense expression of the fasciclin-like arabinogalactan protein FLA6 gene in Populus inhibits expression of its homologous genes and alters stem biomechanics and cell wall composition in transgenic trees.

    Science.gov (United States)

    Wang, Haihai; Jiang, Chunmei; Wang, Cuiting; Yang, Yang; Yang, Lei; Gao, Xiaoyan; Zhang, Hongxia

    2015-03-01

    Fasciclin-like arabinogalactan proteins (FLAs) play important roles in the growth and development of roots, stems, and seeds in Arabidopsis. However, their biological functions in woody plants are largely unknown. In this work, we investigated the possible function of PtFLA6 in poplar. Quantitative real-time PCR, PtFLA6-yellow fluorescent protein (YFP) fusion protein subcellular localization, Western blotting, and immunohistochemical analyses demonstrated that the PtFLA6 gene was expressed specifically in the xylem of mature stem, and PtFLA6 protein was distributed ubiquitous in plant cells and accumulated predominantly in stem xylem fibres. Antisense expression of PtFLA6 in the aspen hybrid clone Poplar davidiana×Poplar bolleana reduced the transcripts of PtFLA6 and its homologous genes. Transgenic plants that showed a significant reduction in the transcripts of PtFLAs accumulated fewer PtFLA6 and arabinogalactan proteins than did the non-transgenic plants, leading to reduced stem flexural strength and stiffness. Further studies revealed that the altered stem biomechanics of transgenic plants could be attributed to the decreased cellulose and lignin composition in the xylem. In addition expression of some xylem-specific genes involved in cell wall biosynthesis was downregulated in these transgenic plants. All these results suggest that engineering the expression of PtFLA6 and its homologues could modulate stem mechanical properties by affecting cell wall composition in trees.

  16. TALEN mediated targeted mutagenesis of the caffeic acid O-methyltransferase in highly polyploid sugarcane improves cell wall composition for production of bioethanol.

    Science.gov (United States)

    Jung, Je Hyeong; Altpeter, Fredy

    2016-09-01

    Sugarcane (Saccharum spp. hybrids) is a prime crop for commercial biofuel production. Advanced conversion technology utilizes both, sucrose accumulating in sugarcane stems as well as cell wall bound sugars for commercial ethanol production. Reduction of lignin content significantly improves the conversion of lignocellulosic biomass into ethanol. Conventional mutagenesis is not expected to confer reduction in lignin content in sugarcane due to its high polyploidy (x = 10-13) and functional redundancy among homo(eo)logs. Here we deploy transcription activator-like effector nuclease (TALEN) to induce mutations in a highly conserved region of the caffeic acid O-methyltransferase (COMT) of sugarcane. Capillary electrophoresis (CE) was validated by pyrosequencing as reliable and inexpensive high throughput method for identification and quantitative characterization of TALEN mediated mutations. Targeted COMT mutations were identified by CE in up to 74 % of the lines. In different events 8-99 % of the wild type COMT were converted to mutant COMT as revealed by pyrosequencing. Mutation frequencies among mutant lines were positively correlated to lignin reduction. Events with a mutation frequency of 99 % displayed a 29-32 % reduction of the lignin content compared to non-transgenic controls along with significantly reduced S subunit content and elevated hemicellulose content. CE analysis displayed similar peak patterns between primary COMT mutants and their vegetative progenies suggesting that TALEN mediated mutations were faithfully transmitted to vegetative progenies. This is the first report on genome editing in sugarcane. The findings demonstrate that targeted mutagenesis can improve cell wall characteristics for production of lignocellulosic ethanol in crops with highly complex genomes. PMID:27306903

  17. Reinforcing methods for composite timber frame-fiberboard wall panels

    OpenAIRE

    Dobrila, Peter; Premrov, Miroslav

    2012-01-01

    This paper presents different possibilities on how to reinforce timber frame wall panels, which are mainly used as load-carrying capacity elements in the construction of prefabricated timber structures. These walls can be treated as composite elements composed of a timber frame and fiber-plaster boards. As the boards are the weaker part of the system they need to be somehow reinforced in order to assure the resistance and ductility of the elements especially in multi-level buildings located i...

  18. Ectopic lignification in primary cellulose-deficient cell walls of maize cell suspension cultures

    Institute of Scientific and Technical Information of China (English)

    Hugo Melida; Antonio Encina; Asier Largo-Gosens; Esther Novo-Uzal; Rogelio Santiago; Federico Pomar; Pedro Garca; Penelope Garca-Angulo; Jose Luis Acebes; Jesus Alvarez

    2015-01-01

    Maize (Zea mays L.) suspension-cultured cells with up to 70% less cellulose were obtained by stepwise habituation to dichlobenil (DCB), a cellulose biosynthesis inhibitor. Cellulose deficiency was accompanied by marked changes in cell wall matrix polysaccharides and phenolics as revealed by Fourier transform infrared (FTIR) spectroscopy. Cell wall compositional analysis indicated that the cellulose-deficient cell walls showed an enhancement of highly branched and cross-linked arabinoxylans, as well as an increased content in ferulic acid, diferulates and p-coumaric acid, and the presence of a polymer that stained positive for phloroglucinol. In accordance with this, cellulose-deficient cell walls showed a fivefold increase in Klason-type lignin. Thioacidolysis/GC-MS analysis of cellulose-deficient cell walls indicated the presence of a lignin-like polymer with a Syringyl/Guaiacyl ratio of 1.45, which differed from the sensu stricto stress-related lignin that arose in response to short-term DCB-treatments. Gene expression analysis of these cells indicated an overexpression of genes specific for the biosynthesis of monolignol units of lignin. A study of stress signaling pathways revealed an overexpression of some of the jasmonate signaling pathway genes, which might trigger ectopic lignification in response to cell wall integrity disruptions. In summary, the structural plasticity of primary cell walls is proven, since a lignification process is possible in response to cellulose impoverishment.

  19. Numerical Study of Classical and Composite Solar Walls by TRNSYS

    Institute of Scientific and Technical Information of China (English)

    Jibao SHEN; Stéphane LASSUE; Laurent ZALEWSKI; Dezhong HUANG

    2007-01-01

    The laboratory LAMTI has worked for several years on the study and the optimization of the thermal performances of passive solar walls like solar Trombe wall. These components of the buildings envelope have very complex behaviour because they are the seat of various coupled heat transfers modes and are subjected to the random variations of the meteorological parameters. Using the finite difference method (FDM) and starting from experimental results recorded during several years, a simulation model was developed and validated concerning the "composite" Trombe wall. In order to make this work more accessible to the community of the heat engineers,it appears interesting to build a simulation model which can be integrated into the library of elements of the TRNSYS software. A "Type" was thus carried out and the results obtained compared with those of the FDM model. In this work we compare the obtained results with these two numerical ways. The assumptions and the results of simulations are also confronted with those of an existing module in TRNSYS (Type 36) established for the "classical" Trombe wall. The study shows that the models that we developed are very precise and that certain assumptions must be used with a lot of precautions. The advantages of the composite Trombe solar wall compared to the Classical Trombe wall are highlighted for cold and/or cloudy climates.

  20. Microanalysis of Plant Cell Wall Polysaccharides

    NARCIS (Netherlands)

    Obel, N.; Erben, V.; Schwarz, T.; Kühnel, S.; Fodor, A.; Pauly, M.

    2009-01-01

    Oligosaccharide Mass Profiling (OLIMP) allows a fast and sensitive assessment of cell wall polymer structure when coupled with Matrix Assisted Laser Desorption Ionisation Time Of Flight Mass Spectrometry (MALDI-TOF MS). The short time required for sample preparation and analysis makes possible the s

  1. A 3-D Model of a Perennial Ryegrass Primary Cell Wall and Its Enzymatic Degradation

    OpenAIRE

    Indrakumar Vetharaniam; Kelly, William J.; Graeme T. Attwood; Harris, Philip J.

    2014-01-01

    We have developed a novel 3-D, agent-based model of cell-wall digestion to improve our understanding of ruminal cell-wall digestion. It offers a capability to study cell walls and their enzymatic modification, by providing a representation of cellulose microfibrils and non-cellulosic polysaccharides and by simulating their spatial and catalytic interactions with enzymes. One can vary cell-wall composition and the types and numbers of enzyme molecules, allowing the model to be applied to a ran...

  2. Single-Walled Carbon Nanotube/PMMA Composites

    Science.gov (United States)

    Du, Fangming; Fisher, John; Winey, Karen

    2003-03-01

    Single-walled carbon nanotubes (SWNTs) have demonstrated unique mechanical, thermal and electrical properties. Similar properties are expected for polymer/SWNT nanocomposites. A new processing method has been used to produce PMMA/SWNT composites, which provides better dispersion of SWNT in the polymer matrix. Optical microscopy of the samples show improved dispersion of SWNT in the PMMA matrix, which is the key factor of the composite performance. Aligned and unaligned composite samples have been made for both purified SWNT and functionalized SWNT with different SWNT loadings. The tensile, thermal conductivity, and electroconductivity measurements of these samples will be performed.

  3. Arrangement of peptidoglycan in the cell wall of Staphylococcus spp.

    OpenAIRE

    Amako, K; Umeda, A.; Murata, K

    1982-01-01

    The arrangement of peptidoglycan in the cell wall of Staphylococcus was observed with the newly developed freeze-fracture technique, using n-octanol instead of water as the freezing medium. The replica of the trichloroacetic acid-extracted cell wall (TCA-wall) showed two areas. One of them has a concentric circular structure, a characteristic surface structure of the staphylococcal cell wall, and the other showed an irregular and rough surface. The chemical analysis of the wall revealed that ...

  4. Fluorescent tags to explore cell wall structure and dynamics

    OpenAIRE

    Gonneau, Martine; Höfte, Herman; Vernhettes, Samantha

    2012-01-01

    Plant cell walls are highly dynamic and heterogeneous structures, which vary between cell types, growth stages but also between microdomains within a single cell wall. In this review, we summarize the imaging techniques using fluorescent tags that are currently being used and which should in the coming years revolutionize our understanding of the dynamics of cell wall architecture and the cellular processes involved in the synthesis of cell wall components.

  5. Fungal Cell Wall Dynamics and Infection Site Microenvironments: Signal Integration and Infection Outcome

    OpenAIRE

    Shepardson, Kelly M.; Cramer, Robert A.

    2013-01-01

    Upon entrance into the host, fungi encounter a myriad of host effector products and microenvironments that they sense and adapt to for survival. Alterations of the structure and composition of the cell wall is a major fungal adaptation mechanism to evade these environments. Here we discuss recent findings of host-microenvironmental induced fungal cell wall changes, including structure, composition, and protein content, and their effects on host immune responses. A take home message from these...

  6. Interconnections between cell wall polymers, wall mechanics, and cortical microtubules: Teasing out causes and consequences.

    Science.gov (United States)

    Xiao, Chaowen; Anderson, Charles T

    2016-09-01

    In plants, cell wall components including cellulose, hemicelluloses, and pectins interact with each other to form complex extracellular network structures that control cell growth and maintain cell shape. However, it is still not clear exactly how different wall polymers interact, how the conformations and interactions of cell wall polymers relate to wall mechanics, and how these factors impinge on intracellular structures such as the cortical microtubule cytoskeleton. Here, based on studies of Arabidopsis thaliana xxt1 xxt2 mutants, which lack detectable xyloglucan in their walls and display aberrant wall mechanics, altered cellulose patterning and biosynthesis, and reduced cortical microtubule stability, we discuss the potential relationships between cell wall biosynthesis, wall mechanics, and cytoskeletal dynamics in an effort to better understand their roles in controlling plant growth and morphogenesis.

  7. Interconnections between cell wall polymers, wall mechanics, and cortical microtubules: Teasing out causes and consequences.

    Science.gov (United States)

    Xiao, Chaowen; Anderson, Charles T

    2016-09-01

    In plants, cell wall components including cellulose, hemicelluloses, and pectins interact with each other to form complex extracellular network structures that control cell growth and maintain cell shape. However, it is still not clear exactly how different wall polymers interact, how the conformations and interactions of cell wall polymers relate to wall mechanics, and how these factors impinge on intracellular structures such as the cortical microtubule cytoskeleton. Here, based on studies of Arabidopsis thaliana xxt1 xxt2 mutants, which lack detectable xyloglucan in their walls and display aberrant wall mechanics, altered cellulose patterning and biosynthesis, and reduced cortical microtubule stability, we discuss the potential relationships between cell wall biosynthesis, wall mechanics, and cytoskeletal dynamics in an effort to better understand their roles in controlling plant growth and morphogenesis. PMID:27611066

  8. Cellulose-hemicellulose interaction in wood secondary cell-wall

    Science.gov (United States)

    Zhang, Ning; Li, Shi; Xiong, Liming; Hong, Yu; Chen, Youping

    2015-12-01

    The wood cell wall features a tough and relatively rigid fiber reinforced composite structure. It acts as a pressure vessel, offering protection against mechanical stress. Cellulose microfibrils, hemicellulose and amorphous lignin are the three major components of wood. The structure of secondary cell wall could be imagined as the same as reinforced concrete, in which cellulose microfibrils acts as reinforcing steel bar and hemicellulose-lignin matrices act as the concrete. Therefore, the interface between cellulose and hemicellulose/lignin plays a significant role in determine the mechanical behavior of wood secondary cell wall. To this end, we present a molecular dynamics (MD) simulation study attempting to quantify the strength of the interface between cellulose microfibrils and hemicellulose. Since hemicellulose binds with adjacent cellulose microfibrils in various patterns, the atomistic models of hemicellulose-cellulose composites with three typical binding modes, i.e. bridge, loop and random binding modes are constructed. The effect of the shape of hemicellulose chain on the strength of hemicellulose-cellulose composites under shear loadings is investigated. The contact area as well as hydrogen bonds between cellulose and hemicellulose, together with the covalent bonds in backbone of hemicellulose chain are found to be the controlling parameters which determine the strength of the interfaces in the composite system. For the bridge binding model, the effect of shear loading direction on the strength of the cellulose material is also studied. The obtained results suggest that the shear strength of wood-inspired engineering composites can be optimized through maximizing the formations of the contributing hydrogen bonds between cellulose and hemicellulose.

  9. Plant Cell Wall Matrix Polysaccharide Biosynthesis

    Institute of Scientific and Technical Information of China (English)

    Ajay Pal S. Sandhu; Gursharn S. Randhawa; Kanwarpal S. Dhugga

    2009-01-01

    The wall of an expanding plant cell consists primarily of cellulose microfibrils embedded in a matrix of hemi-cellulosic and pectic polysaccharides along with small amounts of structural and enzymatic proteins. Matrix polysacchar-ides are synthesized in the Golgi and exported to the cell wall by exocytosis, where they intercalate among cellulose microfibrUs, which are made at the plasma membrane and directly deposited into the cell wall. Involvement of Golgi glucan synthesis in auxin-induced cell expansion has long been recognized; however, only recently have the genes corresponding to glucan synthases been identified. Biochemical purification was unsuccessful because of the labile nature and very low abundance of these enzymes. Mutational genetics also proved fruitless. Expression of candidate genes identified through gene expression profiling or comparative genomics in heterologous systems followed by functional characterization has been relatively successful. Several genes from the cellulose synthase-like (Cs/) family have been found to be involved in the synthesis of various hemicellulosic glycans. The usefulness of this approach, however, is limited to those enzymes that probably do not form complexes consisting of unrelated proteins. Nonconventional approaches will continue to incre-mentally unravel the mechanisms of Golgi polysaccharide biosynthesis.

  10. Advanced technologies for plant cell wall evolution and diversity

    DEFF Research Database (Denmark)

    Fangel, Jonatan Ulrik

    Plant cell walls consist of polysaccharides, glycoproteins and phenolic polymers interlinked together in a highly complex network. The detailed analysis of cell walls is challenging because of their inherent complexity and heterogeneity. Also, complex carbohydrates, unlike proteins and nucleotide...

  11. Fluorescent tags to explore cell wall structure and dynamics.

    OpenAIRE

    Martine eGonneau; Herman eHöfte; Samantha eVernhettes

    2012-01-01

    Plant cell walls are highly dynamic and heterogeneic structures, which vary between celltypes, growth stages but also between microdomains within a single cell wall. In this review, we summarize the imaging techniques using fluorescent tags that are currently being used and which should in the coming years revolutionize our understanding of the dynamics of cell wall architecture and the cellular processes involved in synthesis of cell wall components.

  12. Wall relaxation and the driving forces for cell expansive growth

    Science.gov (United States)

    Cosgrove, D. J.

    1987-01-01

    When water uptake by growing cells is prevented, the turgor pressure and the tensile stress in the cell wall are reduced by continued wall loosening. This process, termed in vivo stress relaxation, provides a new way to study the dynamics of wall loosening and to measure the wall yield threshold and the physiological wall extensibility. Stress relaxation experiments indicate that wall stress supplies the mechanical driving force for wall yielding. Cell expansion also requires water absorption. The driving force for water uptake during growth is created by wall relaxation, which lowers the water potential of the expanding cells. New techniques for measuring this driving force show that it is smaller than believed previously; in elongating stems it is only 0.3 to 0.5 bar. This means that the hydraulic resistance of the water transport pathway is small and that rate of cell expansion is controlled primarily by wall loosening and yielding.

  13. Plant cell wall dynamics and wall-related susceptibility in plant–pathogen interactions

    OpenAIRE

    Bellincampi, Daniela; Cervone, Felice; Lionetti, Vincenzo

    2014-01-01

    The cell wall is a dynamic structure that often determines the outcome of the interactions between plants and pathogens. It is a barrier that pathogens need to breach to colonize the plant tissue. While fungal necrotrophs extensively destroy the integrity of the cell wall through the combined action of degrading enzymes, biotrophic fungi require a more localized and controlled degradation of the cell wall in order to keep the host cells alive and utilize their feeding structures. Also bacteri...

  14. Plant cell wall dynamics and wall-related susceptibility in plant-pathogen interactions

    OpenAIRE

    Daniela eBellincampi; Felice eCervone; Vincenzo eLionetti

    2014-01-01

    The cell wall is a dynamic structure that often determines the outcome of the interactions between plants and pathogens. It is a barrier that pathogens need to breach to colonize the plant tissue. While fungal necrotrophs extensively destroy the integrity of the cell wall through the combined action of degrading enzymes, biotrophic fungi require a more localized and controlled degradation of the cell wall in order to keep the host cells alive and utilize their feeding structures. Also bacteri...

  15. Beyond growth: novel functions for bacterial cell wall hydrolases.

    Science.gov (United States)

    Wyckoff, Timna J; Taylor, Jennifer A; Salama, Nina R

    2012-11-01

    The peptidoglycan cell wall maintains turgor pressure and cell shape of most bacteria. Cell wall hydrolases are essential, together with synthases, for growth and daughter cell separation. Recent work in diverse organisms has uncovered new cell wall hydrolases that act autonomously or on neighboring cells to modulate invasion of prey cells, cell shape, innate immune detection, intercellular communication, and competitor lysis. The hydrolases involved in these processes catalyze the cleavage of bonds throughout the sugar and peptide moities of peptidoglycan. Phenotypes associated with these diverse hydrolases reveal new functions of the bacterial cell wall beyond growth and division.

  16. The cell-wall glycoproteins of the green alga Scenedesmus obliquus. The predominant cell-wall polypeptide of Scenedesmus obliquus is related to the cell-wall glycoprotein gp3 of Chlamydomonas reinhardtii.

    Science.gov (United States)

    Voigt, Jürgen; Stolarczyk, Adam; Zych, Maria; Malec, Przemysław; Burczyk, Jan

    2014-02-01

    The green alga Scenedesmus obliquus contains a multilayered cell wall, ultrastructurally similar to that of Chlamydomonas reinhardtii, although its proportion of hydroxyproline is considerably lower. Therefore, we have investigated the polypeptide composition of the insoluble and the chaotrope-soluble wall fractions of S. obliquus. The polypeptide pattern of the chaotrope-soluble wall fraction was strongly modified by chemical deglycosylation with anhydrous hydrogen fluoride (HF) in pyridine indicating that most of these polypeptides are glycosylated. Polypeptide constituents of the chaotrope-soluble cell-wall fraction with apparent molecular masses of 240, 270, 265, and 135 kDa cross-reacted with a polyclonal antibody raised against the 100 kDa deglycosylation product of the C. reinhardtii cell-wall glycoprotein GP3B. Chemical deglycosylation of the chaotrope-soluble wall fraction resulted in a 135 kDa major polypeptide and a 106 kDa minor component reacting with the same antibody. This antibody recognized specific peptide epitopes of GP3B. When the insoluble wall fraction of S. obliquus was treated with anhydrous HF/pyridine, three polypeptides with apparent molecular masses of 144, 135, and 65 kDa were solubilized, which also occured in the deglycosylated chaotrope-soluble wall fraction. These findings indicate that theses glycoproteins are cross-linked to the insoluble wall fraction via HF-sensitive bonds. PMID:24388513

  17. Immunoprofiling reveals unique cell-specific patterns of wall epitopes in the expanding Arabidopsis stem.

    Science.gov (United States)

    Hall, Hardy C; Cheung, Jingling; Ellis, Brian E

    2013-04-01

    The Arabidopsis inflorescence stem undergoes rapid directional growth, requiring massive axial cell-wall extension in all its tissues, but, at maturity, these tissues are composed of cell types that exhibit markedly different cell-wall structures. It is not clear whether the cell-wall compositions of these cell types diverge rapidly following axial growth cessation, or whether compositional divergence occurs at earlier stages in differentiation, despite the common requirement for cell-wall extensibility. To examine this question, seven cell types were assayed for the abundance and distribution of 18 major cell-wall glycan classes at three developmental stages along the developing inflorescence stem, using a high-throughput immunolabelling strategy. These stages represent a phase of juvenile growth, a phase displaying the maximum rate of stem extension, and a phase in which extension growth is ceasing. The immunolabelling patterns detected demonstrate that the cell-wall composition of most stem tissues undergoes pronounced changes both during and after rapid extension growth. Hierarchical clustering of the immunolabelling signals identified cell-specific binding patterns for some antibodies, including a sub-group of arabinogalactan side chain-directed antibodies whose epitope targets are specifically associated with the inter-fascicular fibre region during the rapid cell expansion phase. The data reveal dynamic, cell type-specific changes in cell-wall chemistry across diverse cell types during cell-wall expansion and maturation in the Arabidopsis inflorescence stem, and highlight the paradox between this structural diversity and the uniform anisotropic cell expansion taking place across all tissues during stem growth.

  18. Decreased Polysaccharide Feruloylation Compromises Plant Cell Wall Integrity and Increases Susceptibility to Necrotrophic Fungal Pathogens

    Directory of Open Access Journals (Sweden)

    Nathan T Reem

    2016-05-01

    Full Text Available The complexity of cell wall composition and structure determines the strength, flexibility, and function of the primary cell wall in plants. However, the contribution of the various components to cell wall integrity and function remains unclear. Modifications of cell wall composition can induce plant responses known as Cell Wall Integrity control. In this study, we used transgenic expression of the fungal feruloyl esterase AnFAE to examine the effect of post-synthetic modification of Arabidopsis and Brachypodium cell walls. Transgenic Arabidopsis plants expressing AnFAE showed a significant reduction of monomeric ferulic acid, increased amounts of wall-associated extensins, and increased susceptibility to Botrytis cinerea, compared with wild type. Transgenic Brachypodium showed reductions in monomeric and dimeric ferulic acids and increased susceptibility to Bipolaris sorokiniana. Upon infection, transgenic Arabidopsis and Brachypodium plants also showed increased expression of several defense-related genes compared with wild type. These results demonstrate a role, in both monocot and dicot plants, of polysaccharide feruloylation in plant cell wall integrity, which contributes to plant resistance to necrotrophic pathogens.

  19. Two cationic peroxidases from cell walls of Araucaria araucana seeds.

    Science.gov (United States)

    Riquelme, A; Cardemil, L

    1995-05-01

    We have previously reported the purification and partial characterization of two cationic peroxidases from the cell walls of seeds and seedlings of the South American conifer, Araucaria araucana. In this work, we have studied the amino acid composition and NH2-terminal sequences of both enzymes. We also compare the data obtained from these analyses with those reported for other plant peroxidases. The two peroxidases are similar in their amino acid compositions. Both are particularly rich in glycine, which comprises more than 30% of the amino acid residues. The content of serine is also high, ca 17%. The two enzymes are different in their content of arginine, alanine, valine, phenylalanine and threonine. Both peroxidases have identical NH2-terminal sequences, indicating that the two proteins are genetically related and probably are isoforms of the same kind of peroxidase. The amino acid composition and NH2-terminal sequence analyses showed marked differences from the cationic peroxidases from turnip and horseradish. PMID:7786490

  20. Photoresponse from noble metal nanoparticles-multi walled carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Scarselli, M.; Camilli, L.; Castrucci, P.; De Crescenzi, M. [Dipartimento di Fisica, Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma (Italy); Matthes, L. [Dipartimento di Fisica, Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma (Italy); Institut fuer Festkoepertheorie und optik, Friedrich Schiller Universitaet, Max-Wien Platz 1, Jena (Germany); Pulci, O. [Dipartimento di Fisica, Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma (Italy); ETSF, MIFO, and CNR-ISM, Via del Fosso del Cavaliere, Roma (Italy); Gatto, E.; Venanzi, M. [Dipartimento di Scienze e Tecnologie Chimiche, Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma (Italy)

    2012-12-10

    In this Letter, we investigated the photo-response of multi wall carbon nanotube-based composites obtained from in situ thermal evaporation of noble metals (Au, Ag, and Cu) on the nanotube films. The metal deposition process produced discrete nanoparticles on the nanotube outer walls. The nanoparticle-carbon nanotube films were characterized by photo-electrochemical measurements in a standard three electrode cell. The photocurrent from the decorated carbon nanotubes remarkably increased with respect to that of bare multiwall tubes. With the aid of first-principle calculations, these results are discussed in terms of metal nanoparticle-nanotube interactions and electronic charge transfer at the interface.

  1. Self-repairing composite walls for pressurized space habitats

    Science.gov (United States)

    Dry, Carolyn

    2016-04-01

    A most important factor for human occupied habitats in space is to ensure that the pressurized habitat does not lose pressure catastrophically by the penetration of space debris or micrometeorites through the wall and into the pressurized space. Regenerative self repairing composites used for the space station habitat to prevent loss of pressure was demonstrated in tests The wall sample had ambient pressurized on one side with vacuum on the other, then was punctured all the way through; the pressure reading went from -26 inches of mercury to -26 inches and stayed there indefinitely. There was no loss of pressure! This will be a game changer for space habitat design. This represents a proposed test bed experimental effort on the International Space Station for self repairing regenerative walls of pressurized habitats, supported by significant puncture over vacuum and puncture testing performed to date, which will provide NASA with an innovative new light weight multi-hit superior Astronaut Protective Wall solution for pressurized space habitats.

  2. Progress Towards the Tomato Fruit Cell Wall Proteome

    Directory of Open Access Journals (Sweden)

    Eliel eRuiz May

    2013-05-01

    Full Text Available The plant cell wall (CW compartment, or apoplast, is host to a highly dynamic proteome, comprising large numbers of both enzymatic and structural proteins. This reflects its importance as the interface between adjacent cells and the external environment, the presence of numerous extracellular metabolic and signaling pathways, and the complex nature of wall structural assembly and remodeling during cell growth and differentiation. Tomato fruit ontogeny, with its distinct phases of rapid growth and ripening, provides a valuable experimental model system for CW proteomic studies, in that it involves substantial wall assembly, remodeling and coordinated disassembly. Moreover, diverse populations of secreted proteins must be deployed to resist microbial infection and protect against abiotic stresses. Tomato fruits also provide substantial amounts of biological material, which is a significant advantage for many types of biochemical analyses, and facilitates the detection of lower abundance proteins. In this review we describe a variety of orthogonal techniques that have been applied to identify CW localized proteins from tomato fruit, including approaches that: target the proteome of the CW and the overlying cuticle; functional ‘secretome’ screens; lectin affinity chromatography; and computational analyses to predict proteins that enter the secretory pathway. Each has its merits and limitations, but collectively they are providing important insights into CW proteome composition and dynamics, as well as some potentially controversial issues, such as the prevalence of non-canonical protein secretion.

  3. Cell wall proteins in seedling cotyledons of Prosopis chilensis.

    Science.gov (United States)

    Rodríguez, J G; Cardemil, L

    1994-01-01

    Four cell wall proteins of cotyledons of Prosopis chilensis seedlings were characterized by PAGE and Western analyses using a polyclonal antibody, generated against soybean seed coat extensin. These proteins had M(r)s of 180,000, 126,000, 107,000 and 63,000, as determined by SDS-PAGE. The proteins exhibited a fluorescent positive reaction with dansylhydrazine suggesting that they are glycoproteins; they did not show peroxidase activity. The cell wall proteins were also characterized by their amino acid composition and by their amino-terminal sequence. These analyses revealed that there are two groups of related cell wall proteins in the cotyledons. The first group comprises the proteins of M(r)s 180,000, 126,000, 107,000 which are rich in glutamic acid/glutamine and aspartic acid/asparagine and they have almost identical NH2-terminal sequences. The second group comprises the M(r) 63,000 protein which is rich in proline, glycine, valine and tyrosine, with an NH2-terminal sequence which was very similar to that of soybean proline-rich proteins.

  4. Mass spectrometry for characterizing plant cell wall polysaccharides

    Directory of Open Access Journals (Sweden)

    Stefan eBauer

    2012-03-01

    Full Text Available Mass spectrometry is a selective and powerful technique to obtain identification and structural information on compounds present in complex mixtures. Since it requires only small sample amount it is an excellent tool for researchers interested in detecting changes in composition of complex carbohydrates of plants. This mini-review gives an overview of common mass spectrometry techniques applied to the analysis of plant cell wall carbohydrates. It presents examples in which mass spectrometry has been used to elucidate the structure of oligosaccharides derived from hemicelluloses and pectins and illustrates how information on sequence, linkages, branching and modifications are obtained from characteristic fragmentation patterns.

  5. Enzymes and other agents that enhance cell wall extensibility

    Science.gov (United States)

    Cosgrove, D. J.

    1999-01-01

    Polysaccharides and proteins are secreted to the inner surface of the growing cell wall, where they assemble into a network that is mechanically strong, yet remains extensible until the cells cease growth. This review focuses on the agents that directly or indirectly enhance the extensibility properties of growing walls. The properties of expansins, endoglucanases, and xyloglucan transglycosylases are reviewed and their postulated roles in modulating wall extensibility are evaluated. A summary model for wall extension is presented, in which expansin is a primary agent of wall extension, whereas endoglucanases, xyloglucan endotransglycosylase, and other enzymes that alter wall structure act secondarily to modulate expansin action.

  6. Effects of foliar boron application on seed composition, cell wall boron, and seed delta 15N and delta 13C isotopes in soybean are influenced by water stress

    Science.gov (United States)

    Although the effect of foliar boron (B) application on yield and quality is well established for crops, limited information and controversial results still exist on the effects of foliar B application on soybean seed composition (seed protein, oil, fatty acids, and sugars). The objective of this res...

  7. Effect of shear connectors on local buckling and composite action in steel concrete composite walls

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai, E-mail: kai-zh@purdue.edu [School of Civil Engineering, Purdue University, West Lafayette, IN (United States); Varma, Amit H., E-mail: ahvarma@purdue.edu [School of Civil Engineering, Purdue University, West Lafayette, IN (United States); Malushte, Sanjeev R., E-mail: smalusht@bechtel.com [Bechtel Power Corporation, Frederick, MD (United States); Gallocher, Stewart, E-mail: stewart.gallocher@steelbricks.com [Modular Walling Systems Ltd., Glasgow (United Kingdom)

    2014-04-01

    Steel concrete composite (SC) walls are being used for the third generation nuclear power plants, and also being considered for small modular reactors. SC walls consist of thick concrete walls with exterior steel faceplates serving as reinforcement. These steel faceplates are anchored to the concrete infill using shear connectors, for example, headed steel studs. The steel faceplate thickness (t{sub p}) and yield stress (F{sub y}), and the shear connector spacing (s), stiffness (k{sub s}), and strength (Q{sub n}) determine: (a) the level of composite action between the steel plates and the concrete infill, (b) the development length of steel faceplates, and (c) the local buckling of the steel faceplates. Thus, the shear connectors have a significant influence on the behavior of composite SC walls, and should be designed accordingly. This paper presents the effects of shear connector design on the level of composite action and development length of steel faceplates in SC walls. The maximum steel plate slenderness, i.e., ratio of shear connector spacing-to-plate thickness (s/t{sub p}) ratio to prevent local buckling before yielding is also developed based on the existing experimental database and additional numerical analysis.

  8. Effect of shear connectors on local buckling and composite action in steel concrete composite walls

    International Nuclear Information System (INIS)

    Steel concrete composite (SC) walls are being used for the third generation nuclear power plants, and also being considered for small modular reactors. SC walls consist of thick concrete walls with exterior steel faceplates serving as reinforcement. These steel faceplates are anchored to the concrete infill using shear connectors, for example, headed steel studs. The steel faceplate thickness (tp) and yield stress (Fy), and the shear connector spacing (s), stiffness (ks), and strength (Qn) determine: (a) the level of composite action between the steel plates and the concrete infill, (b) the development length of steel faceplates, and (c) the local buckling of the steel faceplates. Thus, the shear connectors have a significant influence on the behavior of composite SC walls, and should be designed accordingly. This paper presents the effects of shear connector design on the level of composite action and development length of steel faceplates in SC walls. The maximum steel plate slenderness, i.e., ratio of shear connector spacing-to-plate thickness (s/tp) ratio to prevent local buckling before yielding is also developed based on the existing experimental database and additional numerical analysis

  9. A Bi-layer Composite Film Based on TiO2 Hollow Spheres, P25, and Multi-walled Carbon Nanotubes for Efficient Photoanode of Dye-sensitized Solar Cell

    Institute of Scientific and Technical Information of China (English)

    Putao Zhang; Zhiqiang Hu; Yan Wang; Yiying Qin; Wenqin Li; Jinmin Wang

    2016-01-01

    A bi-layer photoanode for dye-sensitized solar cell (DSSC) was fabricated, in which TiO2 hollow spheres (THSs) were designed as a scattering layer and P25/multi-walled carbon nanotubes (MWNTs) as an under-layer. The THSs were synthesized by a sacrifice template method and showed good light scattering ability as an over-layer of the pho-toanode. MWNTs were mixed with P25 to form an under-layer of the photoanode to improve the electron transmission ability of the photoanode. The power conversion efficiency of this kind of DSSC with bi-layer was enhanced to 5.13%, which is 14.25%higher than that of pure P25 DSSC. Graphical Abstract A bi-layer composite photoanode based on P25/MWNTs-THSs with improved light scattering and electron transmission, which will provide a new insight into fabrication and structure design of highly efficient dye-sensitized solar cells.

  10. Pectic substances from soybean cell walls distinguish themselves from other plant cell wall pectins

    NARCIS (Netherlands)

    Huisman, M.M.H.; Schols, H.A.; Voragen, A.G.J.

    2003-01-01

    The uncommon structural features of soybean cell wall pectic substances explain their resistance to degradation by enzymes generally used to degrade this kind of polymers, and indicates that a search for new enzymes is required to enable enzymatic modification of these polysaccharides

  11. Cell Wall Ultrastructure of Stem Wood, Roots, and Needles of a Conifer Varies in Response to Moisture Availability.

    Science.gov (United States)

    Pattathil, Sivakumar; Ingwers, Miles W; Victoriano, Olivia L; Kandemkavil, Sindhu; McGuire, Mary Anne; Teskey, Robert O; Aubrey, Doug P

    2016-01-01

    The composition, integrity, and architecture of the macromolecular matrix of cell walls, collectively referred to as cell wall ultrastructure, exhibits variation across species and organs and among cell types within organs. Indirect approaches have suggested that modifications to cell wall ultrastructure occur in response to abiotic stress; however, modifications have not been directly observed. Glycome profiling was used to study cell wall ultrastructure by examining variation in composition and extractability of non-cellulosic glycans in cell walls of stem wood, roots, and needles of loblolly pine saplings exposed to high and low soil moisture. Soil moisture influenced physiological processes and the overall composition and extractability of cell wall components differed as a function of soil moisture treatments. The strongest response of cell wall ultrastructure to soil moisture was increased extractability of pectic backbone epitopes in the low soil moisture treatment. The higher abundance of these pectic backbone epitopes in the oxalate extract indicate that the loosening of cell wall pectic components could be associated with the release of pectic signals as a stress response. The increased extractability of pectic backbone epitopes in response to low soil moisture availability was more pronounced in stem wood than in roots or needles. Additional responses to low soil moisture availability were observed in lignin-associated carbohydrates released in chlorite extracts of stem wood, including an increased abundance of pectic arabinogalactan epitopes. Overall, these results indicate that cell walls of loblolly pine organs undergo changes in their ultrastructural composition and extractability as a response to soil moisture availability and that cell walls of the stem wood are more responsive to low soil moisture availability compared to cell walls of roots and needles. To our knowledge, this is the first direct evidence, delineated by glycomic analyses, that

  12. Sucrose synthase affects carbon partitioning to increase cellulose production and altered cell wall ultrastructure

    OpenAIRE

    Coleman, Heather D.; Yan, Jimmy; Mansfield, Shawn D

    2009-01-01

    Overexpression of the Gossypium hirsutum sucrose synthase (SuSy) gene under the control of 2 promoters was examined in hybrid poplar (Populus alba × grandidentata). Analysis of RNA transcript abundance, enzyme activity, cell wall composition, and soluble carbohydrates revealed significant changes in the transgenic lines. All lines showed significantly increased SuSy enzyme activity in developing xylem. This activity manifested in altered secondary cell wall cellulose content per dry weight in...

  13. Trans-Golgi Network-An Intersection of Trafficking Cell Wall Components

    Institute of Scientific and Technical Information of China (English)

    Natasha Worden; Eunsook Park; Georgia Drakakaki

    2012-01-01

    The cell wall,a crucial cell compartment,is composed of a network of polysaccharides and proteins,providing structural support and protection from external stimuli.While the cell wall structure and biosynthesis have been extensively studied,very little is known about the transport of polysaccharides and other components into the developing cell wall.This review focuses on endomembrane trafficking pathways involved in cell wall deposition.Cellulose synthase complexes are assembled in the Golgi,and are transported in vesicles to the plasma membrane.Non-cellulosic polysaccharides are synthesized in the Golgi apparatus,whereas cellulose is produced by enzyme complexes at the plasma membrane.Polvsaccharides and enzymes that are involved in cell wall modification and assembly are transported by distinct vesicle types to their destinations; however,the precise mechanisms involved in selection,sorting and delivery remain to be identified.The endomembrane system orchestrates the delivery of Golgi-derived and possibly endocytic vesicles carrying cell wall and cell membrane components to the newly-formed cell plate.However,the nature of these vesicles,their membrane compositions,and the timing of their delivery are largely unknown.Emerging technologies such as chemical genomics and proteomics are promising avenues to gain insight into the trafficking of cell wall components.

  14. Fluorescent single walled nanotube/silica composite materials

    Science.gov (United States)

    Dattelbaum, Andrew M.; Gupta, Gautam; Duque, Juan G.; Doorn, Stephen K.; Hamilton, Christopher E.; DeFriend Obrey, Kimberly A.

    2013-03-12

    Fluorescent composites of surfactant-wrapped single-walled carbon nanotubes (SWNTs) were prepared by exposing suspensions of surfactant-wrapped carbon nanotubes to tetramethylorthosilicate (TMOS) vapor. Sodium deoxycholate (DOC) and sodium dodecylsulphate (SDS) were the surfactants. No loss in emission intensity was observed when the suspension of DOC-wrapped SWNTs were exposed to the TMOS vapors, but about a 50% decrease in the emission signal was observed from the SDS-wrapped SWNTs nanotubes. The decrease in emission was minimal by buffering the SDS/SWNT suspension prior to forming the composite. Fluorescent xerogels were prepared by adding glycerol to the SWNT suspensions prior to TMOS vapor exposure, followed by drying the gels. Fluorescent aerogels were prepared by replacing water in the gels with methanol and then exposing them to supercritical fluid drying conditions. The aerogels can be used for gas sensing.

  15. Two endogenous proteins that induce cell wall extension in plants

    Science.gov (United States)

    McQueen-Mason, S.; Durachko, D. M.; Cosgrove, D. J.

    1992-01-01

    Plant cell enlargement is regulated by wall relaxation and yielding, which is thought to be catalyzed by elusive "wall-loosening" enzymes. By employing a reconstitution approach, we found that a crude protein extract from the cell walls of growing cucumber seedlings possessed the ability to induce the extension of isolated cell walls. This activity was restricted to the growing region of the stem and could induce the extension of isolated cell walls from various dicot stems and the leaves of amaryllidaceous monocots, but was less effective on grass coleoptile walls. Endogenous and reconstituted wall extension activities showed similar sensitivities to pH, metal ions, thiol reducing agents, proteases, and boiling in methanol or water. Sequential HPLC fractionation of the active wall extract revealed two proteins with molecular masses of 29 and 30 kD associated with the activity. Each protein, by itself, could induce wall extension without detectable hydrolytic breakdown of the wall. These proteins appear to mediate "acid growth" responses of isolated walls and may catalyze plant cell wall extension by a novel biochemical mechanism.

  16. Single Wall Carbon Nanotube-polymer Solar Cells

    Science.gov (United States)

    Bailey, Sheila G.; Castro, Stephanie L.; Landi, Brian J.; Gennett, Thomas; Raffaelle, Ryne P.

    2005-01-01

    Investigation of single wall carbon nanotube (SWNT)-polymer solar cells has been conducted towards developing alternative lightweight, flexible devices for space power applications. Photovoltaic devices were constructed with regioregular poly(3-octylthiophene)-(P3OT) and purified, >95% w/w, laser-generated SWNTs. The P3OT composites were deposited on ITO-coated polyethylene terapthalate (PET) and I-V characterization was performed under simulated AM0 illumination. Fabricated devices for the 1.0% w/w SWNT-P3OT composites showed a photoresponse with an open-circuit voltage (V(sub oc)) of 0.98 V and a short-circuit current density (I(sub sc)) of 0.12 mA/sq cm. Optimization of carrier transport within these novel photovoltaic systems is proposed, specifically development of nanostructure-SWNT complexes to enhance exciton dissociation.

  17. Immunogold localization of xyloglucan and rhamnogalacturonan I in the cell walls of suspension-cultured sycamore cells.

    Science.gov (United States)

    Moore, P J; Darvill, A G; Albersheim, P; Staehelin, L A

    1986-11-01

    PLANT CELL WALLS SERVE SEVERAL FUNCTIONS: they impart rigidity to the plant, provide a physical and chemical barrier between the cell and its environment, and regulate the size and shape of each cell. Chemical studies have provided information on the biochemical composition of the plant cell walls as well as detailed knowledge of individual cell wall molecules. In contrast, very little is known about the distribution of specific cell wall components around individual cells and throughout tissues. To address this problem, we have produced polyclonal antibodies against two cell wall matrix components; rhamnogalacturonan I (RG-I), a pectic polysaccharide, and xyloglucan (XG), a hemicellulose. By using the antibiodies as specific markers we have been able to localize these polymers on thin sections of suspension-cultured sycamore cells (Acer pseudoplatanus). Our results reveal that each molecule has a unique distribution. XG is localized throughout the entire wall and middle lamella. RG-I is restricted to the middle lamella and is especially evident in the junctions between cells. These observations indicate that plant cell walls may have more distinct chemical (and functional?) domains than previously envisaged.

  18. An arabidopsis gene regulatory network for secondary cell wall synthesis

    Science.gov (United States)

    The plant cell wall is an important factor for determining cell shape, function and response to the environment. Secondary cell walls, such as those found in xylem, are composed of cellulose, hemicelluloses and lignin and account for the bulk of plant biomass. The coordination between transcriptiona...

  19. Cosegregation of cell wall and DNA in Bacillus subtilis.

    OpenAIRE

    Schlaeppi, J M; Karamata, D

    1982-01-01

    Cosegregation of cell wall and DNA of a lysis-negative mutant of Bacillus subtilis was examined by continuously labeling (i) cell wall, (ii) DNA, and (iii) both cell wall and DNA. After four to five generations of chase in liquid media it was found by light microscope autoradiography that the numbers of wall segregation units per cell are 29 and 9 in rich and minimal medium, respectively. Under the same conditions the numbers of segregation units of DNA were almost 50% lower: 15 and 5, respec...

  20. Cell wall sorting of lipoproteins in Staphylococcus aureus.

    OpenAIRE

    Navarre, W W; Daefler, S; Schneewind, O

    1996-01-01

    Many surface proteins are thought to be anchored to the cell wall of gram-positive organisms via their C termini, while the N-terminal domains of these molecules are displayed on the bacterial surface. Cell wall anchoring of surface proteins in Staphylococcus aureus requires both an N-terminal leader peptide and a C-terminal cell wall sorting signal. By fusing the cell wall sorting of protein A to the C terminus of staphylococcal beta-lactamase, we demonstrate here that lipoproteins can also ...

  1. Cell wall degradation in the autolysis of filamentous fungi.

    Science.gov (United States)

    Perez-Leblic, M I; Reyes, F; Martinez, M J; Lahoz, R

    1982-12-27

    A systematic study on autolysis of the cell walls of fungi has been made on Neurospora crassa, Botrytis cinerea, Polystictus versicolor, Aspergillus nidulans, Schizophyllum commune, Aspergillus niger, and Mucor mucedo. During autolysis each fungus produces the necessary lytic enzymes for its autodegradation. From autolyzed cultures of each fungus enzymatic precipitates were obtained. The degree of lysis of the cell walls, obtained from non-autolyzed mycelia, was studied by incubating these cell walls with and without a supply of their own lytic enzymes. The degree of lysis increased with the incubation time and generally was higher with a supply of lytic enzymes. Cell walls from mycelia of different ages were obtained. A higher degree of lysis was always found, in young cell walls than in older cell walls, when exogenous lytic enzymes were present. In all the fungi studied, there is lysis of the cell walls during autolysis. This is confirmed by the change of the cell wall structure as well as by the degree of lysis reached by the cell wall and the release of substances, principally glucose and N-acetylglucosamine in the medium.

  2. Nanosurgery: observation of peptidoglycan strands in Lactobacillus helveticus cell walls

    Energy Technology Data Exchange (ETDEWEB)

    Firtel, Max; Henderson, Grant; Sokolov, Igor

    2004-11-15

    The internal cell wall structure of the bacterium Lactobacillus helveticus has been observed in situ in aqueous solution using an atomic force microscope (AFM). The AFM tip was used not only for imaging but presumably to remove mechanically large patches of the outer cell wall after appropriate chemical treatment, which typically leaves the bacteria alive. The surface exposed after this 'surgery' revealed {approx}26 nm thick twisted strands within the cell wall. The structure and location of the observed strands are consistent with the glycan backbone of peptidoglycan fibers that give strength to the cell wall. The structural organization of these fibers has not been observed previously.

  3. Small molecule probes for plant cell wall polysaccharide imaging

    Directory of Open Access Journals (Sweden)

    Ian eWallace

    2012-05-01

    Full Text Available Plant cell walls are composed of interlinked polymer networks consisting of cellulose, hemicelluloses, pectins, proteins, and lignin. The ordered deposition of these components is a dynamic process that critically affects the development and differentiation of plant cells. However, our understanding of cell wall synthesis and remodeling, as well as the diverse cell wall architectures that result from these processes, has been limited by a lack of suitable chemical probes that are compatible with live-cell imaging. In this review, we summarize the currently available molecular toolbox of probes for cell wall polysaccharide imaging in plants, with particular emphasis on recent advances in small molecule-based fluorescent probes. We also discuss the potential for further development of small molecule probes for the analysis of cell wall architecture and dynamics.

  4. Cell wall structure and biogenesis in Aspergillus species.

    Science.gov (United States)

    Yoshimi, Akira; Miyazawa, Ken; Abe, Keietsu

    2016-09-01

    Aspergillus species are among the most important filamentous fungi from the viewpoints of industry, pathogenesis, and mycotoxin production. Fungal cells are exposed to a variety of environmental stimuli, including changes in osmolality, temperature, and pH, which create stresses that primarily act on fungal cell walls. In addition, fungal cell walls are the first interactions with host cells in either human or plants. Thus, understanding cell wall structure and the mechanism of their biogenesis is important for the industrial, medical, and agricultural fields. Here, we provide a systematic review of fungal cell wall structure and recent findings regarding the cell wall integrity signaling pathways in aspergilli. This accumulated knowledge will be useful for understanding and improving the use of industrial aspergilli fermentation processes as well as treatments for some fungal infections. PMID:27140698

  5. Soya beans and Maize : The effect of chemical and physical structure of cell wall polysaccharides on fermentation kinetics

    NARCIS (Netherlands)

    Laar, van H.

    2000-01-01

    The analysis of the relationship between cell wall composition and fermentation of endosperm cell walls of soya beans and maize was approached from three different angles. Firstly, the fermentation (rate and extent of fermentation, the sugar degradation pattern, and volatile fatty acid production) o

  6. Cellulose synthesis in two secondary cell wall processes in a single cell type

    OpenAIRE

    Mendu, Venugopal; Stork, Jozsef; Harris, Darby; DeBolt, Seth

    2011-01-01

    Plant cells have a rigid cell wall that constrains internal turgor pressure yet extends in a regulated and organized manner to allow the cell to acquire shape. The primary load-bearing macromolecule of a plant cell wall is cellulose, which forms crystalline microfibrils that are organized with respect to a cell's function and shape requirements. A primary cell wall is deposited during expansion whereas secondary cell wall is synthesized post expansion during differentiation. A complex form of...

  7. Inter-wall bridging induced peeling of multi-walled carbon nanotubes during tensile failure in aluminum matrix composites.

    Science.gov (United States)

    Chen, Biao; Li, Shufeng; Imai, Hisashi; Umeda, Junko; Takahashi, Makoto; Kondoh, Katsuyoshi

    2015-02-01

    In situ scanning electron microscopy (SEM) observation of a tensile test was performed to investigate the fracturing behavior of multi-walled carbon nanotubes (MWCNTs) in powder metallurgy Al matrix composites. A multiple peeling phenomenon during MWCNT fracturing was clearly observed. Its formation mechanism and resultant effect on the composite strength were examined. Through transition electron microscopy characterizations, it was observed that defective structures like inter-wall bridges cross-linked adjacent walls of MWCNTs. This structure was helpful to improve the inter-wall bonding conditions, leading to the effective load transfer between walls and resultant peeling behaviors of MWCNTs. These results might provide new understandings of the fracturing mechanisms of carbon nanotube reinforcements for designing high-performance nanocomposites. PMID:25437849

  8. Structure of Plant Cell Walls : XXVI. The Walls of Suspension-Cultured Sycamore Cells Contain a Family of Rhamnogalacturonan-I-Like Pectic Polysaccharides.

    Science.gov (United States)

    Ishii, T; Thomas, J; Darvill, A; Albersheim, P

    1989-02-01

    Considerable information has been obtained about the primary structures of suspension-cultured sycamore (Acer pseudoplatanus) cell-wall pectic polysaccharides, i.e. rhamnogalacturonan I, rhamnogalacturonan II, and homogalacturonan. However, these polysaccharides, which are solubilized from the walls by endo-alpha-1,4-polygalacturonase, account for only about half of the pectic polysaccharides known to be present in sycamore cell walls. We now report that, after exhaustive treatment with endo-alpha-1,4-polygalacturonase, additional pectic polysaccharides were extracted from sycamore cell walls by treatment with Na(2)CO(3) at 1 and 22 degrees C. These previously uncharacterized polysaccharides accounted for approximately 4% of the cell wall. Based on the glycosyl and glycosyl-linkage compositions and the nature of the products obtained by treating the quantitatively predominant NaCO(3)-extracted polysaccharides with lithium metal dissolved in ethylenediamine, the polysaccharides were found to strongly resemble rhamnogalacturonan I. However, unlike rhamnogalacturonan I that characteristically had equal amounts of 2- and 2,4-linked rhamnosyl residues in its backbone, the polysaccharides extracted in Na(2)CO(3) at 1 degrees C had markedly disparate ratios of 2- to 2,4-linked rhamnosyl residues. We concluded that polysaccharides similar to rhamnogalacturonan I but with different degrees of branching are present in the walls of suspension-cultured sycamore cells.

  9. Measurement of streptococcal cell wall in tissues of rats resistant or susceptible to cell wall-induced chronic erosive arthritis.

    OpenAIRE

    Anderle, S K; Allen, J B; Wilder, R L; Eisenberg, R A; Cromartie, W J; Schwab, J. H.

    1985-01-01

    The quantity of streptococcal cell wall localized in the joints of rats of strains which are either susceptible (Sprague-Dawley, LEW/N, M520/N) or resistant (Buffalo, WKY/N, F344/N) to cell wall-induced chronic erosive arthritis was measured after intraperitoneal injection of group A streptococcal cell wall fragments. Susceptibility or resistance was not associated with a difference in the amount of cell wall localized in limbs or other tissues. It is concluded that although localization of c...

  10. Anhydrobiosis in yeast: cell wall mannoproteins are important for yeast Saccharomyces cerevisiae resistance to dehydration.

    Science.gov (United States)

    Borovikova, Diana; Teparić, Renata; Mrša, Vladimir; Rapoport, Alexander

    2016-08-01

    The state of anhydrobiosis is linked with the reversible delay of metabolism as a result of strong dehydration of cells, and is widely distributed in nature. A number of factors responsible for the maintenance of organisms' viability in these conditions have been revealed. This study was directed to understanding how changes in cell wall structure may influence the resistance of yeasts to dehydration-rehydration. Mutants lacking various cell wall mannoproteins were tested to address this issue. It was revealed that mutants lacking proteins belonging to two structurally and functionally unrelated groups (proteins non-covalently attached to the cell wall, and Pir proteins) possessed significantly lower cell resistance to dehydration-rehydration than the mother wild-type strain. At the same time, the absence of the GPI-anchored cell wall protein Ccw12 unexpectedly resulted in an increase of cell resistance to this treatment; this phenomenon is explained by the compensatory synthesis of chitin. The results clearly indicate that the cell wall structure/composition relates to parameters strongly influencing yeast viability during the processes of dehydration-rehydration, and that damage to cell wall proteins during yeast desiccation can be an important factor leading to cell death. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Micropipette aspiration on the outer hair cell lateral wall.

    OpenAIRE

    Sit, P S; Spector, A A; Lue, A J; Popel, A S; Brownell, W.E.

    1997-01-01

    The mechanical properties of the lateral wall of the guinea pig cochlear outer hair cell were studied using the micropipette aspiration technique. A fire-polished micropipette with an inner diameter of approximately 4 microm was brought into contact with the lateral wall and negative pressure was applied. The resulting deformation of the lateral wall was recorded on videotape and subjected to morphometric analysis. The relation between the length of the aspirated portion of the cell and aspir...

  12. Assembly and enlargement of the primary cell wall in plants

    Science.gov (United States)

    Cosgrove, D. J.

    1997-01-01

    Growing plant cells are shaped by an extensible wall that is a complex amalgam of cellulose microfibrils bonded noncovalently to a matrix of hemicelluloses, pectins, and structural proteins. Cellulose is synthesized by complexes in the plasma membrane and is extruded as a self-assembling microfibril, whereas the matrix polymers are secreted by the Golgi apparatus and become integrated into the wall network by poorly understood mechanisms. The growing wall is under high tensile stress from cell turgor and is able to enlarge by a combination of stress relaxation and polymer creep. A pH-dependent mechanism of wall loosening, known as acid growth, is characteristic of growing walls and is mediated by a group of unusual wall proteins called expansins. Expansins appear to disrupt the noncovalent bonding of matrix hemicelluloses to the microfibril, thereby allowing the wall to yield to the mechanical forces generated by cell turgor. Other wall enzymes, such as (1-->4) beta-glucanases and pectinases, may make the wall more responsive to expansin-mediated wall creep whereas pectin methylesterases and peroxidases may alter the wall so as to make it resistant to expansin-mediated creep.

  13. Structural Studies of Complex Carbohydrates of Plant Cell Walls

    Energy Technology Data Exchange (ETDEWEB)

    Darvill, Alan [Univ. of Georgia, Athens, GA (United States); Hahn, Michael G. [Univ. of Georgia, Athens, GA (United States); O' Neill, Malcolm A. [Univ. of Georgia, Athens, GA (United States); York, William S. [Univ. of Georgia, Athens, GA (United States)

    2015-02-17

    Most of the solar energy captured by land plants is converted into the polysaccharides (cellulose, hemicellulose, and pectin) that are the predominant components of the cell wall. These walls, which account for the bulk of plant biomass, have numerous roles in the growth and development of plants. Moreover, these walls have a major impact on human life as they are a renewable source of biomass, a source of diverse commercially useful polymers, a major component of wood, and a source of nutrition for humans and livestock. Thus, understanding the molecular mechanisms that lead to wall assembly and how cell walls and their component polysaccharides contribute to plant growth and development is essential to improve and extend the productivity and value of plant materials. The proposed research will develop and apply advanced analytical and immunological techniques to study specific changes in the structures and interactions of the hemicellulosic and pectic polysaccharides that occur during differentiation and in response to genetic modification and chemical treatments that affect wall biosynthesis. These new techniques will make it possible to accurately characterize minute amounts of cell wall polysaccharides so that subtle changes in structure that occur in individual cell types can be identified and correlated to the physiological or developmental state of the plant. Successful implementation of this research will reveal fundamental relationships between polysaccharide structure, cell wall architecture, and cell wall functions.

  14. Single-walled carbon nanotube networks in conductive composite materials.

    Science.gov (United States)

    Bârsan, Oana A; Hoffmann, Günter G; van der Ven, Leo G J; de With, G Bert

    2014-01-01

    Electrically conductive composite materials can be used for a wide range of applications because they combine the advantages of a specific polymeric material (e.g., thermal and mechanical properties) with the electrical properties of conductive filler particles. However, the overall electrical behaviour of these composite materials is usually much below the potential of the conductive fillers, mainly because by mixing two different components, new interfaces and interphases are created, changing the properties and behaviours of both. Our goal is to characterize and understand the nature and influence of these interfaces on the electrical properties of composite materials. We have improved a technique based on the use of sodium carboxymethyl cellulose (CMC) to disperse single-walled carbon nanotubes (SWCNTs) in water, followed by coating glass substrates, and drying and removing the CMC with a nitric acid treatment. We used electron microscopy and atomic force microscopy techniques to characterize the SWCNT films, and developed an in situ resistance measurement technique to analyse the influence of both the individual components and the mixture of an epoxy/amine system on the electrical behaviour of the SWCNTs. The results showed that impregnating a SWCNT network with a polymer is not the only factor that affects the film resistance; air exposure, temperature, physical and chemical properties of the individual polymer components, and also the formation of a polymeric network, can all have an influence on the macroscopic electrical properties of the initial SWCNT network. These results emphasize the importance of understanding the effects that each of the components can have on each other before trying to prepare an efficient polymer composite material. PMID:25430670

  15. Characterising the cellulose synthase complexes of cell walls

    NARCIS (Netherlands)

    Mansoori Zangir, N.

    2012-01-01

    One of the characteristics of the plant kingdom is the presence of a structural cell wall. Cellulose is a major component in both the primary and secondary cell walls of plants. In higher plants cellulose is synthesized by so called rosette protein complexes with cellulose synthases (CESAs) as the c

  16. 2012 PLANT CELL WALLS GORDON RESEARCH CONFERENCE AND GORDON RESEARCH SEMINAR, AUGUST 4-10, 2012

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Jocelyn

    2012-08-10

    The sub-theme of this year’s meeting, ‘Cell Wall Research in a Post-Genome World’, will be a consideration of the dramatic technological changes that have occurred in the three years since the previous cell wall Gordon Conference in the area of DNA sequencing. New technologies are providing additional perspectives of plant cell wall biology across a rapidly growing number of species, highlighting a myriad of architectures, compositions, and functions in both "conventional" and specialized cell walls. This meeting will focus on addressing the knowledge gaps and technical challenges raised by such diversity, as well as our need to understand the underlying processes for critical applications such as crop improvement and bioenergy resource development.

  17. The Paracoccidioides cell wall: past and present layers towards understanding interaction with the host

    Directory of Open Access Journals (Sweden)

    Rosana ePuccia

    2011-12-01

    Full Text Available The cell wall of pathogenic fungi plays import roles in interaction with the host, so that its composition and structure may determine the course of infection. Here we present an overview of the current and past knowledge on the cell wall constituents of Paracoccidioides brasiliensis and P. lutzii. These are temperature-dependent dimorphic fungi that cause paracoccidioidomycosis, a systemic granulomatous and debilitating disease. Focus is given on cell wall carbohydrate and protein contents, their immune-stimulatory features, adhesion properties, drug target characteristics, and morphological phase specificity. We offer a journey towards the future understanding of the dynamic life that takes place in the cell wall and of the changes that it may suffer when living in the human host.

  18. Engineering the Oryza sativa cell wall with rice NAC transcription factors regulating secondary wall formation

    Directory of Open Access Journals (Sweden)

    Kouki eYoshida

    2013-10-01

    Full Text Available Plant tissues that require structural rigidity synthesize a thick, strong secondary cell wall of lignin, cellulose and hemicelluloses in a complicated bridged structure. Master regulators of secondary wall synthesis were identified in dicots, and orthologs of these regulators have been identified in monocots, but regulation of secondary cell wall formation in monocots has not been extensively studied. Here we demonstrate that the rice transcription factors SECONDARY WALL NAC DOMAIN PROTEINs (SWNs can regulate secondary wall formation in rice (Oryza sativa and are potentially useful for engineering the monocot cell wall. The OsSWN1 promoter is highly active in sclerenchymatous cells of the leaf blade and less active in xylem cells. By contrast, the OsSWN2 promoter is highly active in xylem cells and less active in sclerenchymatous cells. OsSWN2 splicing variants encode two proteins; the shorter protein (OsSWN2S has very low transcriptional activation ability, but the longer protein (OsSWN2L and OsSWN1 have strong transcriptional activation ability. In rice, expression of an OsSWN2S chimeric repressor, driven by the OsSWN2 promoter, resulted in stunted growth and para-wilting (leaf rolling and browning under normal water conditions due to impaired vascular vessels. The same OsSWN2S chimeric repressor, driven by the OsSWN1 promoter, caused a reduction of cell wall thickening in sclerenchymatous cells, a drooping leaf phenotype, reduced lignin and xylose contents and increased digestibility as forage. These data suggest that OsSWNs regulate secondary wall formation in rice and manipulation of OsSWNs may enable improvements in monocotyledonous crops for forage or biofuel applications.

  19. Engineering the Oryza sativa cell wall with rice NAC transcription factors regulating secondary wall formation.

    Science.gov (United States)

    Yoshida, Kouki; Sakamoto, Shingo; Kawai, Tetsushi; Kobayashi, Yoshinori; Sato, Kazuhito; Ichinose, Yasunori; Yaoi, Katsuro; Akiyoshi-Endo, Miho; Sato, Hiroko; Takamizo, Tadashi; Ohme-Takagi, Masaru; Mitsuda, Nobutaka

    2013-01-01

    Plant tissues that require structural rigidity synthesize a thick, strong secondary cell wall of lignin, cellulose and hemicelluloses in a complicated bridged structure. Master regulators of secondary wall synthesis were identified in dicots, and orthologs of these regulators have been identified in monocots, but regulation of secondary cell wall formation in monocots has not been extensively studied. Here we demonstrate that the rice transcription factors SECONDARY WALL NAC DOMAIN PROTEINs (SWNs) can regulate secondary wall formation in rice (Oryza sativa) and are potentially useful for engineering the monocot cell wall. The OsSWN1 promoter is highly active in sclerenchymatous cells of the leaf blade and less active in xylem cells. By contrast, the OsSWN2 promoter is highly active in xylem cells and less active in sclerenchymatous cells. OsSWN2 splicing variants encode two proteins; the shorter protein (OsSWN2S) has very low transcriptional activation ability, but the longer protein (OsSWN2L) and OsSWN1 have strong transcriptional activation ability. In rice, expression of an OsSWN2S chimeric repressor, driven by the OsSWN2 promoter, resulted in stunted growth and para-wilting (leaf rolling and browning under normal water conditions) due to impaired vascular vessels. The same OsSWN2S chimeric repressor, driven by the OsSWN1 promoter, caused a reduction of cell wall thickening in sclerenchymatous cells, a drooping leaf phenotype, reduced lignin and xylose contents and increased digestibility as forage. These data suggest that OsSWNs regulate secondary wall formation in rice and manipulation of OsSWNs may enable improvements in monocotyledonous crops for forage or biofuel applications. PMID:24098302

  20. Enhancement of beta-sitosterol transformation in Mycobacterium vaccae with increased cell wall permeability.

    Science.gov (United States)

    Korycka-Machała, M; Rumijowska-Galewicz, A; Lisowska, K; Ziolkowskit, A; Sedlacze, L

    2001-01-01

    Mycobacterium vaccae exposed to compounds which are known to disorganise the cell wall composition and architecture (protamine, glycine) showed increased specific activity in beta-sitosterol biotransformation to androstene derivatives, intennediates in the production of most medical steroids. GC/MS analysis of free lipid fatty acids revealed higher content of unsaturated compounds, mainly C16:1 and C18:1 in protamine- and glycine-treated cells than that in control cells, which seems to change the permeability features of the cell wall barrier, facilitating hydrophobic beta-sitosterol diffusion.

  1. The role of wall calcium in the extension of cell walls of soybean hypocotyls

    Science.gov (United States)

    Virk, S. S.; Cleland, R. E.

    1990-01-01

    Calcium crosslinks are load-bearing bonds in soybean (Glycine max (L.) Merr.) hypocotyl cell walls, but they are not the same load-bearing bonds that are broken during acid-mediated cell elongation. This conclusion is reached by studying the relationship between wall calcium, pH and the facilitated creep of frozen-thawed soybean hypocotyl sections. Supporting data include the following observations: 1) 2-[(2-bis-[carboxymethyl]amino-5-methylphenoxy)methyl]-6-methoxy-8-bis[car boxymethyl]aminoquinoline (Quin 2) and ethylene glycol-bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) caused only limited facilitated creep as compared with acid, despite removal of comparable or larger amounts of wall calcium; 2) the pH-response curves for calcium removal and acid-facilitated creep were different; 3) reversible acid-extension occurred even after removal of almost all wall calcium with Quin 2; and 4) growth of abraded sections did not involve a proportional loss of wall calcium. Removal of wall calcium, however, increased the capacity of the walls to undergo acid-facilitated creep. These data indicate that breakage of calcium crosslinks is not a major mechanism of cell-wall loosening in soybean hypocotyl tissues.

  2. On-Off Switches for Secondary Cell Wall Biosynthesis

    Institute of Scientific and Technical Information of China (English)

    Huan-Zhong Wang; Richard A.Dixon

    2012-01-01

    Secondary cell walls provide plants with rigidity and strength to support their body weight and ensure water and nutrient transport.They also provide textiles,timber,and potentially second-generation biofuels for human use.Genes responsible for synthesis of the different cell wall components,namely cellulose,hemicelluloses,and lignin,are coordinately expressed and under transcriptional regulation.In the past several years,cell wall-related NAC and MYB transcription factors have been intensively investigated in different species and shown to be master switches of secondary cell wall biosynthesis.Positive and negative regulators,which function upstream of NAC master switches,have also been identified in different plant tissues.Further elucidation of the regulatory mechanisms of cell wall synthesis will facilitate the engineering of plant feedstocks suitable for biofuel production.

  3. On-off switches for secondary cell wall biosynthesis.

    Science.gov (United States)

    Wang, Huan-Zhong; Dixon, Richard A

    2012-03-01

    Secondary cell walls provide plants with rigidity and strength to support their body weight and ensure water and nutrient transport. They also provide textiles, timber, and potentially second-generation biofuels for human use. Genes responsible for synthesis of the different cell wall components, namely cellulose, hemicelluloses, and lignin, are coordinately expressed and under transcriptional regulation. In the past several years, cell wall-related NAC and MYB transcription factors have been intensively investigated in different species and shown to be master switches of secondary cell wall biosynthesis. Positive and negative regulators, which function upstream of NAC master switches, have also been identified in different plant tissues. Further elucidation of the regulatory mechanisms of cell wall synthesis will facilitate the engineering of plant feedstocks suitable for biofuel production. PMID:22138968

  4. Decreased Polysaccharide Feruloylation Compromises Plant Cell Wall Integrity and Increases Susceptibility to Necrotrophic Fungal Pathogens

    Science.gov (United States)

    Reem, Nathan T.; Pogorelko, Gennady; Lionetti, Vincenzo; Chambers, Lauran; Held, Michael A.; Bellincampi, Daniela; Zabotina, Olga A.

    2016-01-01

    The complexity of cell wall composition and structure determines the strength, flexibility, and function of the primary cell wall in plants. However, the contribution of the various components to cell wall integrity (CWI) and function remains unclear. Modifications of cell wall composition can induce plant responses known as CWI control. In this study, we used transgenic expression of the fungal feruloyl esterase AnFAE to examine the effect of post-synthetic modification of Arabidopsis and Brachypodium cell walls. Transgenic Arabidopsis plants expressing AnFAE showed a significant reduction of monomeric ferulic acid, decreased amounts of wall-associated extensins, and increased susceptibility to Botrytis cinerea, compared with wild type. Transgenic Brachypodium showed reductions in monomeric and dimeric ferulic acids and increased susceptibility to Bipolaris sorokiniana. Upon infection, transgenic Arabidopsis and Brachypodium plants also showed increased expression of several defense-related genes compared with wild type. These results demonstrate a role, in both monocot and dicot plants, of polysaccharide feruloylation in plant CWI, which contributes to plant resistance to necrotrophic pathogens. PMID:27242834

  5. Decreased Polysaccharide Feruloylation Compromises Plant Cell Wall Integrity and Increases Susceptibility to Necrotrophic Fungal Pathogens.

    Science.gov (United States)

    Reem, Nathan T; Pogorelko, Gennady; Lionetti, Vincenzo; Chambers, Lauran; Held, Michael A; Bellincampi, Daniela; Zabotina, Olga A

    2016-01-01

    The complexity of cell wall composition and structure determines the strength, flexibility, and function of the primary cell wall in plants. However, the contribution of the various components to cell wall integrity (CWI) and function remains unclear. Modifications of cell wall composition can induce plant responses known as CWI control. In this study, we used transgenic expression of the fungal feruloyl esterase AnFAE to examine the effect of post-synthetic modification of Arabidopsis and Brachypodium cell walls. Transgenic Arabidopsis plants expressing AnFAE showed a significant reduction of monomeric ferulic acid, decreased amounts of wall-associated extensins, and increased susceptibility to Botrytis cinerea, compared with wild type. Transgenic Brachypodium showed reductions in monomeric and dimeric ferulic acids and increased susceptibility to Bipolaris sorokiniana. Upon infection, transgenic Arabidopsis and Brachypodium plants also showed increased expression of several defense-related genes compared with wild type. These results demonstrate a role, in both monocot and dicot plants, of polysaccharide feruloylation in plant CWI, which contributes to plant resistance to necrotrophic pathogens.

  6. Decreased Polysaccharide Feruloylation Compromises Plant Cell Wall Integrity and Increases Susceptibility to Necrotrophic Fungal Pathogens.

    Science.gov (United States)

    Reem, Nathan T; Pogorelko, Gennady; Lionetti, Vincenzo; Chambers, Lauran; Held, Michael A; Bellincampi, Daniela; Zabotina, Olga A

    2016-01-01

    The complexity of cell wall composition and structure determines the strength, flexibility, and function of the primary cell wall in plants. However, the contribution of the various components to cell wall integrity (CWI) and function remains unclear. Modifications of cell wall composition can induce plant responses known as CWI control. In this study, we used transgenic expression of the fungal feruloyl esterase AnFAE to examine the effect of post-synthetic modification of Arabidopsis and Brachypodium cell walls. Transgenic Arabidopsis plants expressing AnFAE showed a significant reduction of monomeric ferulic acid, decreased amounts of wall-associated extensins, and increased susceptibility to Botrytis cinerea, compared with wild type. Transgenic Brachypodium showed reductions in monomeric and dimeric ferulic acids and increased susceptibility to Bipolaris sorokiniana. Upon infection, transgenic Arabidopsis and Brachypodium plants also showed increased expression of several defense-related genes compared with wild type. These results demonstrate a role, in both monocot and dicot plants, of polysaccharide feruloylation in plant CWI, which contributes to plant resistance to necrotrophic pathogens. PMID:27242834

  7. The Plant Cell Wall: A Complex and Dynamic Structure As Revealed by the Responses of Genes under Stress Conditions.

    Science.gov (United States)

    Houston, Kelly; Tucker, Matthew R; Chowdhury, Jamil; Shirley, Neil; Little, Alan

    2016-01-01

    The plant cell wall has a diversity of functions. It provides a structural framework to support plant growth and acts as the first line of defense when the plant encounters pathogens. The cell wall must also retain some flexibility, such that when subjected to developmental, biotic, or abiotic stimuli it can be rapidly remodeled in response. Genes encoding enzymes capable of synthesizing or hydrolyzing components of the plant cell wall show differential expression when subjected to different stresses, suggesting they may facilitate stress tolerance through changes in cell wall composition. In this review we summarize recent genetic and transcriptomic data from the literature supporting a role for specific cell wall-related genes in stress responses, in both dicot and monocot systems. These studies highlight that the molecular signatures of cell wall modification are often complex and dynamic, with multiple genes appearing to respond to a given stimulus. Despite this, comparisons between publically available datasets indicate that in many instances cell wall-related genes respond similarly to different pathogens and abiotic stresses, even across the monocot-dicot boundary. We propose that the emerging picture of cell wall remodeling during stress is one that utilizes a common toolkit of cell wall-related genes, multiple modifications to cell wall structure, and a defined set of stress-responsive transcription factors that regulate them. PMID:27559336

  8. The Plant Cell Wall: A Complex and Dynamic Structure As Revealed by the Responses of Genes under Stress Conditions

    Science.gov (United States)

    Houston, Kelly; Tucker, Matthew R.; Chowdhury, Jamil; Shirley, Neil; Little, Alan

    2016-01-01

    The plant cell wall has a diversity of functions. It provides a structural framework to support plant growth and acts as the first line of defense when the plant encounters pathogens. The cell wall must also retain some flexibility, such that when subjected to developmental, biotic, or abiotic stimuli it can be rapidly remodeled in response. Genes encoding enzymes capable of synthesizing or hydrolyzing components of the plant cell wall show differential expression when subjected to different stresses, suggesting they may facilitate stress tolerance through changes in cell wall composition. In this review we summarize recent genetic and transcriptomic data from the literature supporting a role for specific cell wall-related genes in stress responses, in both dicot and monocot systems. These studies highlight that the molecular signatures of cell wall modification are often complex and dynamic, with multiple genes appearing to respond to a given stimulus. Despite this, comparisons between publically available datasets indicate that in many instances cell wall-related genes respond similarly to different pathogens and abiotic stresses, even across the monocot-dicot boundary. We propose that the emerging picture of cell wall remodeling during stress is one that utilizes a common toolkit of cell wall-related genes, multiple modifications to cell wall structure, and a defined set of stress-responsive transcription factors that regulate them. PMID:27559336

  9. Detection of Cell Wall Chemical Variation in Zea Mays Mutants Using Near-Infrared Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Buyck, N.; Thomas, S.

    2001-01-01

    Corn stover is regarded as the prime candidate feedstock material for commercial biomass conversion in the United States. Variations in chemical composition of Zea mays cell walls can affect biomass conversion process yields and economics. Mutant lines were constructed by activating a Mu transposon system. The cell wall chemical composition of 48 mutant families was characterized using near-infrared (NIR) spectroscopy. NIR data were analyzed using a multivariate statistical analysis technique called Principal Component Analysis (PCA). PCA of the NIR data from 349 maize leaf samples reveals 57 individuals as outliers on one or more of six Principal Components (PCs) at the 95% confidence interval. Of these, 19 individuals from 16 families are outliers on either PC3 (9% of the variation) or PC6 (1% of the variation), the two PCs that contain information about cell wall polymers. Those individuals for which altered cell wall chemistry is confirmed with wet chemical analysis will then be subjected to fermentation analysis to determine whether or not biomass conversion process kinetics, yields and/or economics are significantly affected. Those mutants that provide indications for a decrease in process cost will be pursued further to identify the gene(s) responsible for the observed changes in cell wall composition and associated changes in process economics. These genes will eventually be incorporated into maize breeding programs directed at the development of a truly dual use crop.

  10. Insights into plant cell wall structure, architecture, and integrity using glycome profiling of native and AFEXTM-pre-treated biomass

    OpenAIRE

    Pattathil, Sivakumar; Hahn, Michael G.; Dale, Bruce E; Chundawat, Shishir P. S.

    2015-01-01

    Cell walls, which constitute the bulk of plant biomass, vary considerably in their structure, composition, and architecture. Studies on plant cell walls can be conducted on both native and pre-treated plant biomass samples, allowing an enhanced understanding of these structural and compositional variations. Here glycome profiling was employed to determine the relative abundance of matrix polysaccharides in several phylogenetically distinct native and pre-treated plant biomasses. Eight distinc...

  11. Expression of S-adenosylmethionine Hydrolase in Tissues Synthesizing Secondary Cell Walls Alters Specific Methylated Cell Wall Fractions and Improves Biomass Digestibility.

    Science.gov (United States)

    Eudes, Aymerick; Zhao, Nanxia; Sathitsuksanoh, Noppadon; Baidoo, Edward E K; Lao, Jeemeng; Wang, George; Yogiswara, Sasha; Lee, Taek Soon; Singh, Seema; Mortimer, Jenny C; Keasling, Jay D; Simmons, Blake A; Loqué, Dominique

    2016-01-01

    Plant biomass is a large source of fermentable sugars for the synthesis of bioproducts using engineered microbes. These sugars are stored as cell wall polymers, mainly cellulose and hemicellulose, and are embedded with lignin, which makes their enzymatic hydrolysis challenging. One of the strategies to reduce cell wall recalcitrance is the modification of lignin content and composition. Lignin is a phenolic polymer of methylated aromatic alcohols and its synthesis in tissues developing secondary cell walls is a significant sink for the consumption of the methyl donor S-adenosylmethionine (AdoMet). In this study, we demonstrate in Arabidopsis stems that targeted expression of AdoMet hydrolase (AdoMetase, E.C. 3.3.1.2) in secondary cell wall synthesizing tissues reduces the AdoMet pool and impacts lignin content and composition. In particular, both NMR analysis and pyrolysis gas chromatography mass spectrometry of lignin in engineered biomass showed relative enrichment of non-methylated p-hydroxycinnamyl (H) units and a reduction of dimethylated syringyl (S) units. This indicates a lower degree of methylation compared to that in wild-type lignin. Quantification of cell wall-bound hydroxycinnamates revealed a reduction of ferulate in AdoMetase transgenic lines. Biomass from transgenic lines, in contrast to that in control plants, exhibits an enrichment of glucose content and a reduction in the degree of hemicellulose glucuronoxylan methylation. We also show that these modifications resulted in a reduction of cell wall recalcitrance, because sugar yield generated by enzymatic biomass saccharification was greater than that of wild-type plants. Considering that transgenic plants show no important diminution of biomass yields, and that heterologous expression of AdoMetase protein can be spatiotemporally optimized, this novel approach provides a valuable option for the improvement of lignocellulosic biomass feedstock. PMID:27486577

  12. Expression of S-adenosylmethionine Hydrolase in Tissues Synthesizing Secondary Cell Walls Alters Specific Methylated Cell Wall Fractions and Improves Biomass Digestibility

    Directory of Open Access Journals (Sweden)

    Aymerick Eudes

    2016-07-01

    Full Text Available Plant biomass is a large source of fermentable sugars for the synthesis of bioproducts using engineered microbes. These sugars are stored as cell wall polymers, mainly cellulose and hemicellulose, and are embedded with lignin, which makes their enzymatic hydrolysis challenging. One of the strategies to reduce cell wall recalcitrance is the modification of lignin content and composition. Lignin is a phenolic polymer of methylated aromatic alcohols and its synthesis in tissues developing secondary cell walls is a significant sink for the consumption of the methyl donor S-adenosylmethionine (AdoMet. In this study, we demonstrate in Arabidopsis stems that targeted expression of S-adenosylmethionine hydrolase (AdoMetase, E.C. 3.3.1.2 in secondary cell-wall synthesizing tissues reduces the AdoMet pool and impacts lignin content and composition. In particular, both NMR analysis and pyrolysis gas chromatography mass spectrometry of lignin in engineered biomass showed relative enrichment of non-methylated p-hydroxycinnamyl (H units and a reduction of dimethylated syringyl (S units. This indicates a lower degree of methylation compared to that in wild-type lignin. Quantification of cell wall-bound hydroxycinnamates revealed a reduction of ferulate in AdoMetase transgenic lines. Biomass from transgenic lines, in contrast to that in control plants, exhibits an enrichment of glucose content and a reduction in the degree of hemicellulose glucuronoxylan methylation. We also show that these modifications resulted in a reduction of cell wall recalcitrance, because sugar yield generated by enzymatic biomass saccharification was greater than that of wild type plants. Considering that transgenic plants show no important diminution of biomass yields, and that heterologous expression of AdoMetase protein can be spatiotemporally optimized, this novel approach provides a valuable option for the improvement of lignocellulosic biomass feedstock.

  13. Expression of S-adenosylmethionine Hydrolase in Tissues Synthesizing Secondary Cell Walls Alters Specific Methylated Cell Wall Fractions and Improves Biomass Digestibility

    Science.gov (United States)

    Eudes, Aymerick; Zhao, Nanxia; Sathitsuksanoh, Noppadon; Baidoo, Edward E. K.; Lao, Jeemeng; Wang, George; Yogiswara, Sasha; Lee, Taek Soon; Singh, Seema; Mortimer, Jenny C.; Keasling, Jay D.; Simmons, Blake A.; Loqué, Dominique

    2016-01-01

    Plant biomass is a large source of fermentable sugars for the synthesis of bioproducts using engineered microbes. These sugars are stored as cell wall polymers, mainly cellulose and hemicellulose, and are embedded with lignin, which makes their enzymatic hydrolysis challenging. One of the strategies to reduce cell wall recalcitrance is the modification of lignin content and composition. Lignin is a phenolic polymer of methylated aromatic alcohols and its synthesis in tissues developing secondary cell walls is a significant sink for the consumption of the methyl donor S-adenosylmethionine (AdoMet). In this study, we demonstrate in Arabidopsis stems that targeted expression of AdoMet hydrolase (AdoMetase, E.C. 3.3.1.2) in secondary cell wall synthesizing tissues reduces the AdoMet pool and impacts lignin content and composition. In particular, both NMR analysis and pyrolysis gas chromatography mass spectrometry of lignin in engineered biomass showed relative enrichment of non-methylated p-hydroxycinnamyl (H) units and a reduction of dimethylated syringyl (S) units. This indicates a lower degree of methylation compared to that in wild-type lignin. Quantification of cell wall-bound hydroxycinnamates revealed a reduction of ferulate in AdoMetase transgenic lines. Biomass from transgenic lines, in contrast to that in control plants, exhibits an enrichment of glucose content and a reduction in the degree of hemicellulose glucuronoxylan methylation. We also show that these modifications resulted in a reduction of cell wall recalcitrance, because sugar yield generated by enzymatic biomass saccharification was greater than that of wild-type plants. Considering that transgenic plants show no important diminution of biomass yields, and that heterologous expression of AdoMetase protein can be spatiotemporally optimized, this novel approach provides a valuable option for the improvement of lignocellulosic biomass feedstock. PMID:27486577

  14. Repair of abdominal wall defects in vitro and in vivo using VEGF sustained-release multi-walled carbon nanotubes (MWNT composite scaffolds.

    Directory of Open Access Journals (Sweden)

    Zhicheng Song

    Full Text Available OBJECTIVE: Porcine acellular dermal matrices (ADM have been widely used in experimental and clinical research for abdominal wall repair. Compared to porcine small intestinal submucosa (SIS, the effect of these matrices on the regenerative capacity of blood vessels is still not ideal. Multi-walled carbon nanotubes (MWNTs can more effectively transport VEGF to cells or tissues because of their large specific surface area and interior cavity. In this study, we explored the safety and efficacy of implanted VEGF-loaded MWNT composite scaffolds in vitro and vivo to repair abdominal wall defects. MATERIALS AND METHODS: VEGF-loaded MWNTs were prepared by a modified plasma polymerization treatment. Four composite scaffolds were evaluated for cytotoxicity, proliferation, and release dynamics. We created 3 cm×4 cm abdominal wall defects in 43 Sprague-Dawley rats. After implantation times of 2, 4, 8, and 12 weeks, the scaffolds and the surrounding tissues were collected and examined by gross inspection, biomechanical testing, and histological examination. RESULTS: A 5-10 nm poly(lactic-co-glycolic acid (PLGA film was evenly distributed on MWNTs. The 3% MWNT composite group showed lower cytotoxicity and appropriate release performance, and it was thus tested in vivo. In rats with the 3% composite implanted, host cells were prevented from migrating to the ADM at 2 weeks, vascularization was established more rapidly at 12 weeks, and the values for both the maximum load and the elastic modulus were significantly lower than in the ADM-alone group (p<0.01. Histological staining revealed that the MWNT was still not completely eliminated 12 weeks after implantation. CONCLUSION: MWNTs were able to carry VEGF to cells or tissues, and the 3% MWNT composite material showed lower cytotoxicity and had an appropriate release performance, which prompted faster vascularization of the ADM than other scaffolds. Nevertheless, the MWNTs induced harmful effects that should be

  15. Chemical characterisation and analysis of the cell wall polysaccharides of duckweed (Lemna minor).

    Science.gov (United States)

    Zhao, X; Moates, G K; Wellner, N; Collins, S R A; Coleman, M J; Waldron, K W

    2014-10-13

    Duckweed is potentially an ideal biofuel feedstock due to its high proportion of cellulose and starch and low lignin content. However, there is little detailed information on the composition and structure of duckweed cell walls relevant to optimising the conversion of duckweed biomass to ethanol and other biorefinery products. This study reports that, for the variety and batch evaluated, carbohydrates constitute 51.2% (w/w) of dry matter while starch accounts for 19.9%. This study, for the first time, analyses duckweed cell wall composition through a detailed sequential extraction. The cell wall is rich in cellulose and also contains 20.3% pectin comprising galacturonan, xylogalacturonan, rhamnogalacturonan; 3.5% hemicellulose comprising xyloglucan and xylan, and 0.03% phenolics. In addition, essential fatty acids (0.6%, α-linolenic and linoleic/linoelaidic acid) and p-coumaric acid (0.015%) respectively are the most abundant fatty acids and phenolics in whole duckweed. PMID:25037369

  16. Aleurone Cell Walls of Wheat Grain: High Spatial Resolution Investigation Using Synchrotron Infrared Microspectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jamme, F.; Robert, R; Bouchet, B; Saulnier, L; Dumas, P; Guillon, F

    2008-01-01

    Infrared microspectroscopy and immunolabeling techniques were employed in order to obtain deeper insight into the biochemical nature of aleurone cell walls of wheat grain. The use of a synchrotron source, thanks to its intrinsic brightness, has provided unprecedented information at the level of a few micrometers and has allowed the discrimination of various polysaccharides in cell walls. The high spectral quality obtained in the small analyzed domain has been beneficial in estimating the relative proportions of {Beta}-glucan and arabinoxylan, through the use of principal component analysis (PCA). The highest amount of {Beta}-glucan is found in periclinal cell walls close to the starchy endosperm. The junction regions between aleurone cells are enriched in arabinoxylan. At the early stage of wheat grain development (271 degrees D), the chemical composition along the cell walls is more heterogeneous than at the mature stage. Both synchrotron infrared microspectroscopy and immunolabeling experiments made it possible to reveal the spatial heterogeneity of the various chemical compositions of aleurone cell walls.

  17. A proteomic and genetic analysis of the Neurospora crassa conidia cell wall proteins identifies two glycosyl hydrolases involved in cell wall remodeling.

    Science.gov (United States)

    Ao, Jie; Aldabbous, Mash'el; Notaro, Marysa J; Lojacono, Mark; Free, Stephen J

    2016-09-01

    A proteomic analysis of the conidial cell wall identified 35 cell wall proteins. A comparison with the proteome of the vegetative hyphae showed that 16 cell wall proteins were shared, and that these shared cell wall proteins were cell wall biosynthetic proteins or cell wall structural proteins. Deletion mutants for 34 of the genes were analyzed for phenotypes indicative of conidial cell wall defects. Mutants for two cell wall glycosyl hydrolases, the CGL-1 β-1,3-glucanase (NCU07523) and the NAG-1 exochitinase (NCU10852), were found to have a conidial separation phenotype. These two enzymes function in remodeling the cell wall between adjacent conidia to facilitate conidia formation and dissemination. Using promoter::RFP and promoter::GFP constructs, we demonstrated that the promoters for 15 of the conidia-specific cell wall genes, including cgl-1 and nag-1, provided for conidia-specific gene expression or for a significant increase in their expression during conidiation. PMID:27381444

  18. Mechanical properties of plant cell walls probed by relaxation spectra

    DEFF Research Database (Denmark)

    Hansen, Steen Laugesen; Ray, Peter Martin; Karlsson, Anders Ola;

    2011-01-01

    type. This may be due to the plant’s ability to compensate for the wall modification or because the biophysical method that is often employed, determination of simple elastic modulus and breakstrength, lacks the resolving power necessary for detecting subtle mechanical phenotypes. Here, we apply...... a method, determination of relaxation spectra, which probes, and can separate, the viscoelastic properties of different cell wall components (i.e. those properties that depend on the elastic behavior of load-bearing wall polymers combined with viscous interactions between them). A computer program, Bayes......Relax, that deduces relaxation spectra from appropriate rheological measurements is presented and made accessible through a Web interface. BayesRelax models the cell wall as a continuum of relaxing elements, and the ability of the method to resolve small differences in cell wall mechanical properties is demonstrated...

  19. Glycosytransferases involved in arabinosylation of cell wall extensins

    DEFF Research Database (Denmark)

    Petersen, Bent L; Harholt, Jesper; Jørgensen, Bodil;

    2011-01-01

    Extensins are a group of ancient hydroxyproline rich cell wall glycoproteins that are found in some chlorophyte algae (such as Chlamydomonas), where they constitute the main wall building block, as well as in higher plant cell walls, where they constitute a relatively minor component of particular...... al (2007) Molecular characterization of two Arabidopsis thaliana glycosyltransferase mutants, rra-1 and -2, which have a reduced content of arabinose in a polymer tightly associated with the cellulose residue. Plant Mol. Biol. 64:439-451 Gille et al (2009) Identification of plant cell wall mutants...... importance to wall assembly. The GlycosylTransferase family 77 (GT-family-77) rra1-2 (Egelund et al. 2007) and xeg113 (Gille et al. 2009) Arabidopsis, mutants have been suggested to be arabinosyltransferases involved in arabinosylation of extensins. We have now isolated extensins from these mutants and a new...

  20. Cell Wall Metabolism in Response to Abiotic Stress

    Directory of Open Access Journals (Sweden)

    Hyacinthe Le Gall

    2015-02-01

    Full Text Available This review focuses on the responses of the plant cell wall to several abiotic stresses including drought, flooding, heat, cold, salt, heavy metals, light, and air pollutants. The effects of stress on cell wall metabolism are discussed at the physiological (morphogenic, transcriptomic, proteomic and biochemical levels. The analysis of a large set of data shows that the plant response is highly complex. The overall effects of most abiotic stress are often dependent on the plant species, the genotype, the age of the plant, the timing of the stress application, and the intensity of this stress. This shows the difficulty of identifying a common pattern of stress response in cell wall architecture that could enable adaptation and/or resistance to abiotic stress. However, in most cases, two main mechanisms can be highlighted: (i an increased level in xyloglucan endotransglucosylase/hydrolase (XTH and expansin proteins, associated with an increase in the degree of rhamnogalacturonan I branching that maintains cell wall plasticity and (ii an increased cell wall thickening by reinforcement of the secondary wall with hemicellulose and lignin deposition. Taken together, these results show the need to undertake large-scale analyses, using multidisciplinary approaches, to unravel the consequences of stress on the cell wall. This will help identify the key components that could be targeted to improve biomass production under stress conditions.

  1. 2D-immunoblotting analysis of Sporothrix schenckii cell wall

    Directory of Open Access Journals (Sweden)

    Estela Ruiz-Baca

    2011-03-01

    Full Text Available We utilized two-dimensional gel electrophoresis and immunoblotting (2D-immunoblotting with anti-Sporothrix schenckii antibodies to identify antigenic proteins in cell wall preparations obtained from the mycelial and yeast-like morphologies of the fungus. Results showed that a 70-kDa glycoprotein (Gp70 was the major antigen detected in the cell wall of both morphologies and that a 60-kDa glycoprotein was present only in yeast-like cells. In addition to the Gp70, the wall from filament cells showed four proteins with molecular weights of 48, 55, 66 and 67 kDa, some of which exhibited several isoforms. To our knowledge, this is the first 2D-immunoblotting analysis of the S. schenckii cell wall.

  2. A system for identification of candidate genes controlling cell wall synthesis in alfalfa stems

    Science.gov (United States)

    Usefulness of alfalfa for livestock feeding and production of lignocellulose-derived ethanol would be improved by genetic alteration of stem cell wall concentration and composition. This could be accomplished through selective breeding and transgenic technologies. However, development of alfalfa cel...

  3. Structural characterization of pectic hairy regions isolated from apple cell walls.

    NARCIS (Netherlands)

    Schols, H.A.

    1995-01-01

    Cell wall pectic substances have a great influence on the production and quality aspects of apple juice. Apple juices were characterized by their polysaccharide content and composition. A pectic fraction, retained by ultrafiltration of a liquefaction juice, was isolated and termed MHR (modified hair

  4. Investigation of transient heat transfer in composite walls using carbon/epoxy composites as an example

    Directory of Open Access Journals (Sweden)

    Terpiłowski Janusz

    2015-12-01

    Full Text Available The paper presents the application of similarity theory to investigations of transient heat transfer in materials with complex structure. It describes the theoretical-experimental method for identification and design of the structure of two-component composite walls based on the research of the thermal diffusivity for the composite and its matrix separately. The thermal diffusivity was measured by means of the modified flash method. The method was tested on two samples of double-layer ‘epoxy resin – polyamide’. All the investigated samples had the same diameter of 12 mm and thickness ranging from 1.39–2.60 mm and their equivalent value of thermal diffusivity ranging from (1.21–1.98×10−7 m2/s. Testing the method and research on carbon/epoxy composites was carried out at temperatures close to room temperature.

  5. Investigation of transient heat transfer in composite walls using carbon/epoxy composites as an example

    Science.gov (United States)

    Terpiłowski, Janusz; Gawron, Bartosz; Woroniak, Grzegorz

    2015-12-01

    The paper presents the application of similarity theory to investigations of transient heat transfer in materials with complex structure. It describes the theoretical-experimental method for identification and design of the structure of two-component composite walls based on the research of the thermal diffusivity for the composite and its matrix separately. The thermal diffusivity was measured by means of the modified flash method. The method was tested on two samples of double-layer `epoxy resin - polyamide'. All the investigated samples had the same diameter of 12 mm and thickness ranging from 1.39-2.60 mm and their equivalent value of thermal diffusivity ranging from (1.21-1.98)×10-7 m2/s. Testing the method and research on carbon/epoxy composites was carried out at temperatures close to room temperature.

  6. Up against the wall: is yeast cell wall integrity ensured by mechanosensing in plasma membrane microdomains?

    Science.gov (United States)

    Kock, Christian; Dufrêne, Yves F; Heinisch, Jürgen J

    2015-02-01

    Yeast cell wall integrity (CWI) signaling serves as a model of the regulation of fungal cell wall synthesis and provides the basis for the development of antifungal drugs. A set of five membrane-spanning sensors (Wsc1 to Wsc3, Mid2, and Mtl1) detect cell surface stress and commence the signaling pathway upon perturbations of either the cell wall structure or the plasma membrane. We here summarize the latest advances in the structure/function relationship primarily of the Wsc1 sensor and critically review the evidence that it acts as a mechanosensor. The relevance and physiological significance of the information obtained for the function of the other CWI sensors, as well as expected future developments, are discussed.

  7. [Degradation of cell wall polysaccharides during postharvest fruit ripening and softening of different apple varieties].

    Science.gov (United States)

    Jin, Chang-Hai; Mizuno, Masashi; Kan, Juan; Suo, Biao; Wang, Zhi-Jun; Tsuchida, Hironobu

    2006-12-01

    The cell wall material (CWM) and eight cell wall polysaccharides fractions were extracted from 'Fuji' and 'Kinsei' apples during storage at different time (0 and 42 days). The sugar composition characteristics of each fraction were determined by gas chromatography. The results showed that, during storages, the firmness of 'Kinsei' apples decreased significantly, and a significant peak of ethylene production was shown after 10 d storage, but only a little ethylene was produced in 'Fuji' apples, which had a better storability. Compare to other cell wall polysaccharide fractions, in Na(2)CO(3)-soluble pectic fractions of apple fruit, there were abundant rhamnogalacturonan I (RG-I), which branched highly in side chains due to the compositions of arabinans, galactans, arabinogalactans etc. As for cell wall polysaccharides, in 'Kinsei' apples, the decrease of pectic fractions was shown most significantly in Na(2)CO(3)-1 fraction, which was associated with a significant degradation of arabinosyl and galactosyl residues on the side chains. Further more, higher molecular mass in Na(2)CO(3)-1 pectic polysaccharides degraded and turned into ones with smaller molecular mass. From these results, the degradation of side chains in Na(2)CO(3)-1 pectic polysaccharides under the activity of enzyme was considered one of the most significant factors of apple fruit softening through modifying the network of cell wall polysaccharides.

  8. Analysis of Cell Wall Teichoic Acids in Staphylococcus aureus.

    Science.gov (United States)

    Covas, Gonçalo; Vaz, Filipa; Henriques, Gabriela; Pinho, Mariana G; Filipe, Sérgio R

    2016-01-01

    Most bacterial cells are surrounded by a surface composed mainly of peptidoglycan (PGN), a glycopolymer responsible for ensuring the bacterial shape and a telltale molecule that betrays the presence of bacteria to the host immune system. In Staphylococcus aureus, as in most gram-positive bacteria, peptidoglycan is concealed by covalently linked molecules of wall teichoic acids (WTA)-phosphate rich molecules made of glycerol and ribitol phosphates which may be tailored by different amino acids and sugars.In order to analyze and compare the composition of WTA produced by different S. aureus strains, we describe methods to: (1) quantify the total amount of WTA present at the bacterial cell surface, through the determination of the inorganic phosphate present in phosphodiester linkages of WTA; (2) identify which sugar constituents are present in the assembled WTA molecules, by detecting the monosaccharides, released by acid hydrolysis, through an high-performance anion exchange chromatography analysis coupled with pulsed amperometric detection (HPAEC-PAD) and (3) compare the polymerization degree of WTA found at the cell surface of different S. aureus strains, through their different migration in a polyacrylamide gel electrophoresis (PAGE). PMID:27311674

  9. Plant cell walls: New insights from ancient species

    DEFF Research Database (Denmark)

    Sørensen, Iben; Willats, William George Tycho

    2008-01-01

    Cell walls are a defining feature of plants and have numerous crucial roles in growth and development. They are also the largest source of terrestrial biomass and have many important industrial applications - ranging from bulk products to functional food ingredients. There is considerable interest...... in the structure and functions of cell walls, and in the evolution of their remarkably complex polysaccharide structures. The grasses and cereals (order Poales), have long been regarded as being unique in that their cell walls contain an unbranched homopolymer, (1¿3)(1¿4)-ß-D-glucan, in which short blocks of (1...... in horsetails (Equisetales order) was therefore significant and has prompted a re-evaluation of some of the current views on cell wall evolution and structural diversity. Addendum to: Sørensen I, Pettolino FA, Wilson SM, Doblin MS, Johansen B, Bacic A, Willats WGT. Mixed-linkage (1¿3),(1¿4)-ß...

  10. Experiment and calculation on seismic behavior of RC composite core walls with concealed steel truss

    Institute of Scientific and Technical Information of China (English)

    Wanlin CAO; Weihua CHANG; Changjun ZHAO; Jianwei ZHANG

    2009-01-01

    To improve the seismic performance of reinforced concrete core walls, reinforced concrete com-posite core walls with concealed steel truss were proposed and systemically investigated. Two 1/6 scale core wall specimens, including a normal reinforced concrete core wall and a reinforced concrete composite core wall with concealed steel truss, were designed. The experimental study on seismic performance under cyclic loading was carried out. The load-carrying capacity, stiffness, ductility,hysteretic behavior and energy dissipation of the core walls were discussed. The test results showed that the seismic performance of core walls is improved greatly by the concealed steel truss. The calculated results were found to agree well with the actual measured ones.

  11. Oocyst wall formation and composition in coccidian parasites

    Directory of Open Access Journals (Sweden)

    Kelly Mai

    2009-03-01

    Full Text Available The oocyst wall of coccidian parasites is a robust structure that is resistant to a variety of environmental and chemical insults. This resilience allows oocysts to survive for long periods, facilitating transmission from host to host. The wall is bilayered and is formed by the sequential release of the contents of two specialized organelles - wall forming body 1 and wall forming body 2 - found in the macrogametocyte stage of Coccidia. The oocyst wall is over 90% protein but few of these proteins have been studied. One group is cysteine-rich and may be presumed to crosslink via disulphide bridges, though this is yet to be investigated. Another group of wall proteins is rich in tyrosine. These proteins, which range in size from 8-31 kDa, are derived from larger precursors of 56 and 82 kDa found in the wall forming bodies. Proteases may catalyze processing of the precursors into tyrosine-rich peptides, which are then oxidatively crosslinked in a reaction catalyzed by peroxidases. In support of this hypothesis, the oocyst wall has high levels of dityrosine bonds. These dityrosine crosslinked proteins may provide a structural matrix for assembly of the oocyst wall and contribute to its resilience.

  12. Immunocytochemical characterization of the cell walls of bean cell suspensions during habituation and dehabituation to dichlobenil

    DEFF Research Database (Denmark)

    Garcia-Angulo, P.; Willats, W. G. T.; Encina, A. E.;

    2006-01-01

    and fluorochrome labelling of resin-embedded sections, and immunodot assays (IDAs) of cell wall fractions. The cell walls from bean cell suspensions with initial levels of habituation to dichlobenil had decreased levels of cellulose, but this effect lessened with increasing numbers of subcultures. All cell walls...... in habituated cells also diminished with the increasing number of subcultures. Habituated cells also liberated less extensin into the medium. In habituated cells, a decrease in the cell wall arabinogalactan protein (AGP) labelling was observed both in cell walls and in the culture medium. The increase...... in the number of subcultures in 0.3 µM dichlobenil was accompanied by an increment in some pectic epitopes (JIM5 and LM5) and a decrease in other pectic and in protein epitopes (JIM7, PAM1, LM6, LM2 and MAC207), indicating a re-structuring of cell walls throughout the habituation procedure. Dehabituated cells...

  13. Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations

    Directory of Open Access Journals (Sweden)

    Wenchao Liu

    2016-03-01

    Full Text Available The seismic performance of recycled aggregate concrete (RAC composite shear walls with different expandable polystyrene (EPS configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC protective layer (EPS modules as the external insulation layer, and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls.

  14. Analyzing the complex machinery of cell wall biosynthesis

    OpenAIRE

    Timmers, J.F.P.

    2009-01-01

    The plant cell wall polymers make up most of the plant biomass and provide the raw material for many economically important products including food, feed, bio-materials, chemicals, textiles, and biofuel. This broad range of functions and applications make the biosynthesis of these polysaccharides a highly interesting target of scientific research. In this thesis a protein-protein interaction strategy was used to gain insight in the cell wall biosynthesis of Arabidopsis thaliana and to identif...

  15. Patterns of expression of cell wall related genes in sugarcane

    Directory of Open Access Journals (Sweden)

    Lima D.U.

    2001-01-01

    Full Text Available Our search for genes related to cell wall metabolism in the sugarcane expressed sequence tag (SUCEST database (http://sucest.lbi.dcc.unicamp.br resulted in 3,283 reads (1% of the total reads which were grouped into 459 clusters (potential genes with an average of 7.1 reads per cluster. To more clearly display our correlation coefficients, we constructed surface maps which we used to investigate the relationship between cell wall genes and the sugarcane tissues libraries from which they came. The only significant correlations that we found between cell wall genes and/or their expression within particular libraries were neutral or synergetic. Genes related to cellulose biosynthesis were from the CesA family, and were found to be the most abundant cell wall related genes in the SUCEST database. We found that the highest number of CesA reads came from the root and stem libraries. The genes with the greatest number of reads were those involved in cell wall hydrolases (e.g. beta-1,3-glucanases, xyloglucan endo-beta-transglycosylase, beta-glucosidase and endo-beta-mannanase. Correlation analyses by surface mapping revealed that the expression of genes related to biosynthesis seems to be associated with the hydrolysis of hemicelluloses, pectin hydrolases being mainly associated with xyloglucan hydrolases. The patterns of cell wall related gene expression in sugarcane based on the number of reads per cluster reflected quite well the expected physiological characteristics of the tissues. This is the first work to provide a general view on plant cell wall metabolism through the expression of related genes in almost all the tissues of a plant at the same time. For example, developing flowers behaved similarly to both meristematic tissues and leaf-root transition zone tissues. Besides providing a basis for future research on the mechanisms of plant development which involve the cell wall, our findings will provide valuable tools for plant engineering in the

  16. Salt stress causes cell wall damage in yeast cells lacking mitochondrial DNA

    OpenAIRE

    Qiuqiang Gao; Liang-Chun Liou; Qun Ren; Xiaoming Bao; Zhaojie Zhang

    2015-01-01

    The yeast cell wall plays an important role in maintaining cell morphology, cell integrity and response to environmental stresses. Here, we report that salt stress causes cell wall damage in yeast cells lacking mitochondrial DNA (ρ0). Upon salt treatment, the cell wall is thickened, broken and becomes more sensitive to the cell wall-perturbing agent sodium dodecyl sulfate (SDS). Also, SCW11 mRNA levels are elevated in ρ0 cells. Deletion of SCW11 significantly decreases the sensitivity of ρ0 c...

  17. Extracellular Vesicle-Associated Transitory Cell Wall Components and Their Impact on the Interaction of Fungi with Host Cells.

    Science.gov (United States)

    Nimrichter, Leonardo; de Souza, Marcio M; Del Poeta, Maurizio; Nosanchuk, Joshua D; Joffe, Luna; Tavares, Patricia de M; Rodrigues, Marcio L

    2016-01-01

    Classic cell wall components of fungi comprise the polysaccharides glucans and chitin, in association with glycoproteins and pigments. During the last decade, however, system biology approaches clearly demonstrated that the composition of fungal cell walls include atypical molecules historically associated with intracellular or membrane locations. Elucidation of mechanisms by which many fungal molecules are exported to the extracellular space suggested that these atypical components are transitorily located to the cell wall. The presence of extracellular vesicles (EVs) at the fungal cell wall and in culture supernatants of distinct pathogenic species suggested a highly functional mechanism of molecular export in these organisms. Thus, the passage of EVs through fungal cell walls suggests remarkable molecular diversity and, consequently, a potentially variable influence on the host antifungal response. On the basis of information derived from the proteomic characterization of fungal EVs from the yeasts Cryptoccocus neoformans and Candida albicans and the dimorphic fungi Histoplasma capsulatum and Paracoccidioides brasiliensis, our manuscript is focused on the clear view that the fungal cell wall is much more complex than previously thought. PMID:27458437

  18. Extracellular Vesicle-Associated Transitory Cell Wall Components and Their Impact on the Interaction of Fungi with Host Cells

    Science.gov (United States)

    Nimrichter, Leonardo; de Souza, Marcio M.; Del Poeta, Maurizio; Nosanchuk, Joshua D.; Joffe, Luna; Tavares, Patricia de M.; Rodrigues, Marcio L.

    2016-01-01

    Classic cell wall components of fungi comprise the polysaccharides glucans and chitin, in association with glycoproteins and pigments. During the last decade, however, system biology approaches clearly demonstrated that the composition of fungal cell walls include atypical molecules historically associated with intracellular or membrane locations. Elucidation of mechanisms by which many fungal molecules are exported to the extracellular space suggested that these atypical components are transitorily located to the cell wall. The presence of extracellular vesicles (EVs) at the fungal cell wall and in culture supernatants of distinct pathogenic species suggested a highly functional mechanism of molecular export in these organisms. Thus, the passage of EVs through fungal cell walls suggests remarkable molecular diversity and, consequently, a potentially variable influence on the host antifungal response. On the basis of information derived from the proteomic characterization of fungal EVs from the yeasts Cryptoccocus neoformans and Candida albicans and the dimorphic fungi Histoplasma capsulatum and Paracoccidioides brasiliensis, our manuscript is focused on the clear view that the fungal cell wall is much more complex than previously thought. PMID:27458437

  19. Pectin, a versatile polysaccharide present in plant cell walls

    NARCIS (Netherlands)

    Voragen, A.G.J.; Coenen, G.J.; Verhoef, R.P.; Schols, H.A.

    2009-01-01

    Pectin or pectic substances are collective names for a group of closely associated polysaccharides present in plant cell walls where they contribute to complex physiological processes like cell growth and cell differentiation and so determine the integrity and rigidity of plant tissue. They also pla

  20. Altered cell wall disassembly during ripening of Cnr tomato fruit: implications for cell adhesion and fruit softening

    DEFF Research Database (Denmark)

    Orfila, C.; Huisman, M.M.H.; Willats, William George Tycho;

    2002-01-01

    The Cnr (Colourless non-ripening) tomato (Lycopersicon esculentum Mill.) mutant has an aberrant fruit-ripening phenotype in which fruit do not soften and have reduced cell adhesion between pericarp cells. Cell walls from Cnr fruit were analysed in order to assess the possible contribution of pectic...... polysaccharides to the non-softening and altered cell adhesion phenotype. Cell wall material (CWM) and solubilised fractions of mature green and red ripe fruit were analysed by chemical, enzymatic and immunochemical techniques. No major differences in CWM sugar composition were detected although differences were...... found in the solubility and composition of the pectic polysaccharides extracted from the CWM at both stages of development. In comparison with the wild type, the ripening-associated solubilisation of homogalacturonan-rich pectic polysaccharides was reduced in Cnr. The proportion of carbohydrate...

  1. A model for cell wall dissolution in mating yeast cells: polarized secretion and restricted diffusion of cell wall remodeling enzymes induces local dissolution.

    Directory of Open Access Journals (Sweden)

    Lori B Huberman

    Full Text Available Mating of the budding yeast, Saccharomyces cerevisiae, occurs when two haploid cells of opposite mating types signal using reciprocal pheromones and receptors, grow towards each other, and fuse to form a single diploid cell. To fuse, both cells dissolve their cell walls at the point of contact. This event must be carefully controlled because the osmotic pressure differential between the cytoplasm and extracellular environment causes cells with unprotected plasma membranes to lyse. If the cell wall-degrading enzymes diffuse through the cell wall, their concentration would rise when two cells touched each other, such as when two pheromone-stimulated cells adhere to each other via mating agglutinins. At the surfaces that touch, the enzymes must diffuse laterally through the wall before they can escape into the medium, increasing the time the enzymes spend in the cell wall, and thus raising their concentration at the point of attachment and restricting cell wall dissolution to points where cells touch each other. We tested this hypothesis by studying pheromone treated cells confined between two solid, impermeable surfaces. This confinement increases the frequency of pheromone-induced cell death, and this effect is diminished by reducing the osmotic pressure difference across the cell wall or by deleting putative cell wall glucanases and other genes necessary for efficient cell wall fusion. Our results support the model that pheromone-induced cell death is the result of a contact-driven increase in the local concentration of cell wall remodeling enzymes and suggest that this process plays an important role in regulating cell wall dissolution and fusion in mating cells.

  2. A model for cell wall dissolution in mating yeast cells: polarized secretion and restricted diffusion of cell wall remodeling enzymes induces local dissolution.

    Science.gov (United States)

    Huberman, Lori B; Murray, Andrew W

    2014-01-01

    Mating of the budding yeast, Saccharomyces cerevisiae, occurs when two haploid cells of opposite mating types signal using reciprocal pheromones and receptors, grow towards each other, and fuse to form a single diploid cell. To fuse, both cells dissolve their cell walls at the point of contact. This event must be carefully controlled because the osmotic pressure differential between the cytoplasm and extracellular environment causes cells with unprotected plasma membranes to lyse. If the cell wall-degrading enzymes diffuse through the cell wall, their concentration would rise when two cells touched each other, such as when two pheromone-stimulated cells adhere to each other via mating agglutinins. At the surfaces that touch, the enzymes must diffuse laterally through the wall before they can escape into the medium, increasing the time the enzymes spend in the cell wall, and thus raising their concentration at the point of attachment and restricting cell wall dissolution to points where cells touch each other. We tested this hypothesis by studying pheromone treated cells confined between two solid, impermeable surfaces. This confinement increases the frequency of pheromone-induced cell death, and this effect is diminished by reducing the osmotic pressure difference across the cell wall or by deleting putative cell wall glucanases and other genes necessary for efficient cell wall fusion. Our results support the model that pheromone-induced cell death is the result of a contact-driven increase in the local concentration of cell wall remodeling enzymes and suggest that this process plays an important role in regulating cell wall dissolution and fusion in mating cells.

  3. High-throughput microarray mapping of cell wall polymers in roots and tubers during the viscosity reducing process

    DEFF Research Database (Denmark)

    Yuhong, Huang; Willats, William George Tycho; Lange, Lene;

    2015-01-01

    Viscosity reduction has a great impact on the efficiency of ethanol production when using roots and tubers as feedstock. Plant cell wall-degrading enzymes (PCWDEs) have been successfully applied to overcome the challenges posed by high viscosity. However, the changes in cell wall polymers during...... the viscosity reducing process are poorly characterized. Comprehensive microarray polymer profiling (CoMPP), which is a high-throughput microarray, was used for the first time to map changes in the cell wall polymers of sweet potato (Ipomoea batatas), cassava (Manihot esculenta) and Canna edulis Ker. (Canna...... edulis) over the entire viscosity reducing process. The results indicated that the composition of cell wall polymers among these three roots and tubers was markedly different. The gel-like matrix and glycoprotein network in the Canna edulis Ker. cell wall caused difficulty in viscosity reduction...

  4. Evaluation of cell wall preparations for proteomics: a new procedure for purifying cell walls from Arabidopsis hypocotyls

    Directory of Open Access Journals (Sweden)

    Canut Hervé

    2006-05-01

    Full Text Available Abstract Background The ultimate goal of proteomic analysis of a cell compartment should be the exhaustive identification of resident proteins; excluding proteins from other cell compartments. Reaching such a goal closely depends on the reliability of the isolation procedure for the cell compartment of interest. Plant cell walls possess specific difficulties: (i the lack of a surrounding membrane may result in the loss of cell wall proteins (CWP during the isolation procedure, (ii polysaccharide networks of cellulose, hemicelluloses and pectins form potential traps for contaminants such as intracellular proteins. Several reported procedures to isolate cell walls for proteomic analyses led to the isolation of a high proportion (more than 50% of predicted intracellular proteins. Since isolated cell walls should hold secreted proteins, one can imagine alternative procedures to prepare cell walls containing a lower proportion of contaminant proteins. Results The rationales of several published procedures to isolate cell walls for proteomics were analyzed, with regard to the bioinformatic-predicted subcellular localization of the identified proteins. Critical steps were revealed: (i homogenization in low ionic strength acid buffer to retain CWP, (ii purification through increasing density cushions, (iii extensive washes with a low ionic strength acid buffer to retain CWP while removing as many cytosolic proteins as possible, and (iv absence of detergents. A new procedure was developed to prepare cell walls from etiolated hypocotyls of Arabidopsis thaliana. After salt extraction, a high proportion of proteins predicted to be secreted was released (73%, belonging to the same functional classes as proteins identified using previously described protocols. Finally, removal of intracellular proteins was obtained using detergents, but their amount represented less than 3% in mass of the total protein extract, based on protein quantification. Conclusion The

  5. Another brick in the cell wall: biosynthesis dependent growth model.

    Directory of Open Access Journals (Sweden)

    Adelin Barbacci

    Full Text Available Expansive growth of plant cell is conditioned by the cell wall ability to extend irreversibly. This process is possible if (i a tensile stress is developed in the cell wall due to the coupling effect between turgor pressure and the modulation of its mechanical properties through enzymatic and physicochemical reactions and if (ii new cell wall elements can be synthesized and assembled to the existing wall. In other words, expansive growth is the result of coupling effects between mechanical, thermal and chemical energy. To have a better understanding of this process, models must describe the interplay between physical or mechanical variable with biological events. In this paper we propose a general unified and theoretical framework to model growth in function of energy forms and their coupling. This framework is based on irreversible thermodynamics. It is then applied to model growth of the internodal cell of Chara corallina modulated by changes in pressure and temperature. The results describe accurately cell growth in term of length increment but also in term of cell pectate biosynthesis and incorporation to the expanding wall. Moreover, the classical growth model based on Lockhart's equation such as the one proposed by Ortega, appears as a particular and restrictive case of the more general growth equation developed in this paper.

  6. Altered cell wall disassembly during ripening of Cnr tomato fruit : implications for cell wall adhesion and fruit softening

    NARCIS (Netherlands)

    Orfila, C.; Huisman, M.M.H.; Willats, W.G.T.; Alebeek, van G.J.W.M.; Schols, H.A.; Seymour, G.B.; Knox, J.P.

    2002-01-01

    The Cnr (Colourless non-ripening) tomato (Lycopersicon esculentum Mill.) mutant has an aberrant fruit-ripening phenotype in which fruit do not soften and have reduced cell adhesion between pericarp cells. Cell walls from Cnr fruit were analysed in order to assess the possible contribution of pectic

  7. Cell wall staining with Trypan blue enables quantitative analysis of morphological changes in yeast cells

    DEFF Research Database (Denmark)

    Liesche, Johannes; Marek, Magdalena; Günther-Pomorski, Thomas

    2015-01-01

    staining with fluorescent dyes is a valuable tool. Furthermore, cell wall staining is used to facilitate sub-cellular localization experiments with fluorescently-labeled proteins and the detection of yeast cells in non-fungal host tissues. Here, we report staining of Saccharomyces cerevisiae cell wall......Yeast cells are protected by a cell wall that plays an important role in the exchange of substances with the environment. The cell wall structure is dynamic and can adapt to different physiological states or environmental conditions. For the investigation of morphological changes, selective...... with Trypan Blue, which emits strong red fluorescence upon binding to chitin and yeast glucan; thereby, it facilitates cell wall analysis by confocal and super-resolution microscopy. The staining pattern of Trypan Blue was similar to that of the widely used UV-excitable, blue fluorescent cell wall stain...

  8. Strengthening of Unreinforced Masonry Walls with Composite Materials

    OpenAIRE

    Ioana-Sorina Enţuc; N. Ţăranu; Gabriel Oprişan

    2004-01-01

    Unreinforced masonry (URM) is considered one of the oldest construction materials being until the end of XIXth century, the basic material for: foundations, walls, columns, volts, staircases, floor joints, roofs, retaining walls, drainage channels, barrages, etc. Construction with URM elements posses a series of advantages such as: fire resistance, thermal an acoustic insulations between interior and outside spaces, humidity resistance. However the URM elements have some significant inconveni...

  9. Inhibitors targeting on cell wall biosynthesis pathway of MRSA.

    Science.gov (United States)

    Hao, Haihong; Cheng, Guyue; Dai, Menghong; Wu, Qinghua; Yuan, Zonghui

    2012-11-01

    Methicillin resistant Staphylococcus aureus (MRSA), widely known as a type of new superbug, has aroused world-wide concern. Cell wall biosynthesis pathway is an old but good target for the development of antibacterial agents. Peptidoglycan and wall teichoic acids (WTAs) biosynthesis are two main processes of the cell wall biosynthesis pathway (CWBP). Other than penicillin-binding proteins (PBPs), some key factors (Mur enzymes, lipid I or II precursor, etc.) in CWBP are becoming attractive molecule targets for the discovery of anti-MRSA compounds. A number of new compounds, with higher affinity for PBPs or with inhibitory activity on such molecule targets in CWBP of MRSA, have been in the pipeline recently. This review concludes recent research achievements and provides a complete picture of CWBP of MRSA, including the peptidoglycan and wall teichoic acids synthesis pathway. The potential inhibitors targeting on CWBP are subsequently presented to improve development of novel therapeutic strategies for MRSA. PMID:22898792

  10. Co-delivery of cell-wall-forming enzymes in the same vesicle for coordinated fungal cell wall formation.

    Science.gov (United States)

    Schuster, Martin; Martin-Urdiroz, Magdalena; Higuchi, Yujiro; Hacker, Christian; Kilaru, Sreedhar; Gurr, Sarah J; Steinberg, Gero

    2016-01-01

    Fungal cells are surrounded by an extracellular cell wall. This complex matrix of proteins and polysaccharides protects against adverse stresses and determines the shape of fungal cells. The polysaccharides of the fungal wall include 1,3-β-glucan and chitin, which are synthesized by membrane-bound synthases at the growing cell tip. A hallmark of filamentous fungi is the class V chitin synthase, which carries a myosin-motor domain. In the corn smut fungus Ustilago maydis, the myosin-chitin synthase Mcs1 moves to the plasma membrane in secretory vesicles, being delivered by kinesin-1 and myosin-5. The myosin domain of Mcs1 enhances polar secretion by tethering vesicles at the site of exocytosis. It remains elusive, however, how other cell-wall-forming enzymes are delivered and how their activity is coordinated post secretion. Here, we show that the U. maydis class VII chitin synthase and 1,3-β-glucan synthase travel in Mcs1-containing vesicles, and that their apical secretion depends on Mcs1. Once in the plasma membrane, anchorage requires enzyme activity, which suggests co-synthesis of chitin and 1,3-β-glucan polysaccharides at sites of exocytosis. Thus, delivery of cell-wall-forming enzymes in Mcs1 vesicles ensures local foci of fungal cell wall formation. PMID:27563844

  11. Simulated microgravity inhibits cell wall regeneration of Penicillium decumbens protoplasts

    Science.gov (United States)

    Zhao, C.; Sun, Y.; Yi, Z. C.; Rong, L.; Zhuang, F. Y.; Fan, Y. B.

    2010-09-01

    This work compares cell wall regeneration from protoplasts of the fungus Penicillium decumbens under rotary culture (simulated microgravity) and stationary cultures. Using an optimized lytic enzyme mixture, protoplasts were successfully released with a yield of 5.3 × 10 5 cells/mL. Under simulated microgravity conditions, the protoplast regeneration efficiency was 33.8%, lower than 44.9% under stationary conditions. Laser scanning confocal microscopy gave direct evidence for reduced formation of polysaccharides under simulated conditions. Scanning electron microscopy showed the delayed process of cell wall regeneration by simulated microgravity. The delayed regeneration of P. decumbens cell wall under simulated microgravity was likely caused by the inhibition of polysaccharide synthesis. This research contributes to the understanding of how gravitational loads affect morphological and physiological processes of fungi.

  12. Magnetic domain wall conduits for single cell applications

    DEFF Research Database (Denmark)

    Donolato, Marco; Torti, A.; Kostesha, Natalie;

    2011-01-01

    The ability to trap, manipulate and release single cells on a surface is important both for fundamental studies of cellular processes and for the development of novel lab-on-chip miniaturized tools for biological and medical applications. In this paper we demonstrate how magnetic domain walls...... generated in micro- and nano-structures fabricated on a chip surface can be used to handle single yeast cells labeled with magnetic beads. In detail, first we show that the proposed approach maintains the microorganism viable, as proven by monitoring the division of labeled yeast cells trapped by domain...... walls over 16 hours. Moreover, we demonstrate the controlled transport and release of individual yeast cells via displacement and annihilation of individual domain walls in micro- and nano-sized magnetic structures. These results pave the way to the implementation of magnetic devices based on domain...

  13. Temporal sequence of cell wall disassembly events in developing fruits. 2. Analysis of blueberry (Vaccinium species).

    Science.gov (United States)

    Vicente, Ariel R; Ortugno, Claudia; Rosli, Hernan; Powell, Ann L T; Greve, L Carl; Labavitch, John M

    2007-05-16

    Softening and pathogen susceptibility are the major factors limiting the marketing of blueberries as fresh fruits, and these traits are associated with fruit cell wall structure. However, few studies that characterize wall modifications occurring during development and ripening have been reported for this fruit. In this study the ripening-associated modifications of blueberry fruit cell walls (composition, pectin and hemicellulose solubilization, and depolymerization) at five stages of ripeness have been analyzed. Xylose was found to be the most abundant noncellulosic neutral sugar associated with fruit walls, and the observed high Xyl/Glc ratio suggested that xylans, which are usually a minor hemicellulosic fruit wall component, are abundant in blueberry. The pectic matrix showed increased solubilization at early and intermediate stages of ripening, but no changes were detected in late ripening. Furthermore, little reduction in pectin polymer size occurred during blueberry ripening. In contrast, hemicellulose levels decreased as ripening progressed, and a clear depolymerization of these components was observed. A model for cell wall degradation in this fruit is discussed. PMID:17428068

  14. How cell wall complexity influences saccharification efficiency in Miscanthus sinensis

    NARCIS (Netherlands)

    Souza, De Amanda P.; Lessa Alvim Kamei, Claire; Torres Salvador, Andres Francisco; Pattathil, Sivakumar; Hahn, Michael G.; Trindade, Luisa M.; Buckeridge, Marcos S.

    2015-01-01

    The production of bioenergy from grasses has been developing quickly during the last decade, with Miscanthus being among the most important choices for production of bioethanol. However, one of the key barriers to producing bioethanol is the lack of information about cell wall structure. Cell wal

  15. Alterations in auxin homeostasis suppress defects in cell wall function.

    Directory of Open Access Journals (Sweden)

    Blaire J Steinwand

    Full Text Available The plant cell wall is a highly dynamic structure that changes in response to both environmental and developmental cues. It plays important roles throughout plant growth and development in determining the orientation and extent of cell expansion, providing structural support and acting as a barrier to pathogens. Despite the importance of the cell wall, the signaling pathways regulating its function are not well understood. Two partially redundant leucine-rich-repeat receptor-like kinases (LRR-RLKs, FEI1 and FEI2, regulate cell wall function in Arabidopsis thaliana roots; disruption of the FEIs results in short, swollen roots as a result of decreased cellulose synthesis. We screened for suppressors of this swollen root phenotype and identified two mutations in the putative mitochondrial pyruvate dehydrogenase E1α homolog, IAA-Alanine Resistant 4 (IAR4. Mutations in IAR4 were shown previously to disrupt auxin homeostasis and lead to reduced auxin function. We show that mutations in IAR4 suppress a subset of the fei1 fei2 phenotypes. Consistent with the hypothesis that the suppression of fei1 fei2 by iar4 is the result of reduced auxin function, disruption of the WEI8 and TAR2 genes, which decreases auxin biosynthesis, also suppresses fei1 fei2. In addition, iar4 suppresses the root swelling and accumulation of ectopic lignin phenotypes of other cell wall mutants, including procuste and cobra. Further, iar4 mutants display decreased sensitivity to the cellulose biosynthesis inhibitor isoxaben. These results establish a role for IAR4 in the regulation of cell wall function and provide evidence of crosstalk between the cell wall and auxin during cell expansion in the root.

  16. Structure, function, and biosynthesis of plant cell walls: proceedings of the seventh annual symposium in botany

    Energy Technology Data Exchange (ETDEWEB)

    Dugger, W.M.; Bartnicki-Garcia, S. (eds.)

    1984-01-01

    Papers in the following areas were included in these symposium proceedings: (1) cell wall chemistry and biosynthesis; (2) cell wall hydrolysis and associated physiology; (3) cellular events associated with cell wall biosynthesis; and (4) interactions of plant cell walls with pathogens and related responses. Papers have been individually abstracted for the data base. (ACR)

  17. Vibration and Instability of Rotating Composite Thin-Walled Shafts with Internal Damping

    OpenAIRE

    Ren Yongsheng; Zhang Xingqi; Liu Yanghang; Chen Xiulong

    2014-01-01

    The dynamical analysis of a rotating thin-walled composite shaft with internal damping is carried out analytically. The equations of motion are derived using the thin-walled composite beam theory and the principle of virtual work. The internal damping of shafts is introduced by adopting the multiscale damping analysis method. Galerkin’s method is used to discretize and solve the governing equations. Numerical study shows the effect of design parameters on the natural frequencies, critical rot...

  18. Finite Element Analysis of Composite Hardened Walls Subjected to Blast Loads

    OpenAIRE

    Girum S. Urgessa

    2009-01-01

    Problem statement: There is currently no standard design guideline to determine the number of composites needed to retrofit masonry walls in order to withstand a given explosion. Past design approaches were mainly based on simplified single-degree-of-freedom analysis. A finite element analysis was conducted for concrete masonry walls hardened with composites and subjected to short duration blast loads. Approach: The analysis focused on displacement time history responses which form the basis ...

  19. The Structure of Plant Cell Walls: II. The Hemicellulose of the Walls of Suspension-cultured Sycamore Cells.

    Science.gov (United States)

    Bauer, W D; Talmadge, K W; Keegstra, K; Albersheim, P

    1973-01-01

    The molecular structure, chemical properties, and biological function of the xyloglucan polysaccharide isolated from cell walls of suspension-cultured sycamore (Acer pseudoplatanus) cells are described. The sycamore wall xyloglucan is compared to the extracellular xyloglucan secreted by suspension-cultured sycamore cells into their culture medium and is also compared to the seed "amyloid" xyloglucans.Xyloglucan-or fragments of xyloglucan-and acidic fragments of the pectic polysaccharides are released from endopolygalacturonase-pretreated sycamore walls by treatment of these walls with 8 m urea, endoglucanase, or 0.5 n NaOH. Some of the xyloglucan thus released is found to cochromatograph with the acidic pectic fragments on diethylaminoethyl Sephadex. The chemical or enzymic treatments required for the release of xyloglucan from the walls and the cochromatography of xyloglucan with the acidic pectic fragments indicate that xyloglucan is covalently linked to the pectic polysaccharides and is noncovalently bound to the cellulose fibrils of the sycamore cell wall.The molecular structure of sycamore xyloglucan was characterized by methylation analysis of the oligosaccharides obtained by endoglucanase treatment of the polymer. The structure of the polymer is based on a repeating heptasaccharide unit which consists of 4 residues of beta-1-4-linked glucose and 3 residues of terminal xylose. A single xylose residue is glycosidically linked to carbon 6 of 3 of the glucosyl residues.

  20. The Interplay between Cell Wall Mechanical Properties and the Cell Cycle in Staphylococcus aureus

    OpenAIRE

    Bailey, Richard G.; Turner, Robert D.; Mullin, Nic; Clarke, Nigel,; Foster, Simon J.; Hobbs, Jamie K.

    2014-01-01

    The nanoscale mechanical properties of live Staphylococcus aureus cells during different phases of growth were studied by atomic force microscopy. Indentation to different depths provided access to both local cell wall mechanical properties and whole-cell properties, including a component related to cell turgor pressure. Local cell wall properties were found to change in a characteristic manner throughout the division cycle. Splitting of the cell into two daughter cells followed a local softe...

  1. Target or barrier? The cell wall of early- and later- diverging plants vs cadmium toxicity: differences in the response mechanisms

    Directory of Open Access Journals (Sweden)

    Luigi eParrotta

    2015-03-01

    Full Text Available Increasing industrialization and urbanization result in emission of pollutants in the environment including toxic heavy metals, as cadmium and lead. Among the different heavy metals contaminating the environment, cadmium raises great concern, as it is ecotoxic and as such can heavily impact ecosystems. The cell wall is the first structure of plant cells to come in contact with heavy metals. Its composition, characterized by proteins, polysaccharides and in some instances lignin and other phenolic compounds, confers the ability to bind non-covalently and/or covalently heavy metals via functional groups. A strong body of evidence in the literature has shown the role of the cell wall in heavy metal response: it sequesters heavy metals, but at the same time its synthesis and composition can be severely affected. The present review analyzes the dual property of plant cell walls, i.e. barrier and target of heavy metals, by taking Cd toxicity as example. Following a summary of the known physiological and biochemical responses of plants to Cd, the review compares the wall-related mechanisms in early- and later-diverging land plants, by considering the diversity in cell wall composition. By doing so, common as well as unique response mechanisms to metal/cadmium toxicity are identified among plant phyla and discussed. After discussing the role of hyperaccumulators’ cell walls as a particular case, the review concludes by considering important aspects for plant engineering.

  2. Strengthening of Unreinforced Masonry Walls with Composite Materials

    Directory of Open Access Journals (Sweden)

    Ioana-Sorina Enţuc

    2004-01-01

    Full Text Available Unreinforced masonry (URM is considered one of the oldest construction materials being until the end of XIXth century, the basic material for: foundations, walls, columns, volts, staircases, floor joints, roofs, retaining walls, drainage channels, barrages, etc. Construction with URM elements posses a series of advantages such as: fire resistance, thermal an acoustic insulations between interior and outside spaces, humidity resistance. However the URM elements have some significant inconveniences such as: large self weight (heaviness causes cracks in the other elements of structures, reduced mechanical strengths in comparison with other traditional materials (steel and concrete, low tenacity, great manual labor consumptions, and vulnerability to earthquakes. Various factors cause deteriorations which must be overcome by strengthening solutions. Some strengthening solutions based on fiber reinforced polymers (FRP products applied directly on URM brick walls are presented in the paper.

  3. Synthesis and Application of Plant Cell Wall Oligogalactans

    DEFF Research Database (Denmark)

    Andersen, Mathias Christian Franch

    The plant cell walls represent almost 50% of the biomass found in plants and are therefore one of the main targets for biotechnological research. Major motivators are their potential as a renewable energy source for transport fuels, as functional foods, and as a source of raw materials to generate...... chemical building blocks for industrial processes. To achieve a sustainable development it is necessary to optimize plant production and utilization. This will require a better understanding of the cell wall structure and function at the molecular level. The cell wall is composed by an intricate network...... of the arabinogalactans series. The fragments were applied in the characterization of a glycosyl transferase, a hydrolase and to study the important cancer biomarker galectin-3. The work done during an external stay at University of Oxford is also presented. This concerns isolation and modification...

  4. Fluorescent Probes for Exploring Plant Cell Wall Deconstruction: A Review

    Directory of Open Access Journals (Sweden)

    Gabriel Paës

    2014-07-01

    Full Text Available Plant biomass is a potential resource of chemicals, new materials and biofuels that could reduce our dependency on fossil carbon, thus decreasing the greenhouse effect. However, due to its chemical and structural complexity, plant biomass is recalcitrant to green biological transformation by enzymes, preventing the establishment of integrated bio-refineries. In order to gain more knowledge in the architecture of plant cell wall to facilitate their deconstruction, many fluorescent probes bearing various fluorophores have been devised and used successfully to reveal the changes in structural motifs during plant biomass deconstruction, and the molecular interactions between enzymes and plant cell wall polymers. Fluorescent probes are thus relevant tools to explore plant cell wall deconstruction.

  5. Transcriptional Wiring of Cell Wall-Related Genes in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Marek Mutwil; Colin Ruprecht; Federico M. Giorgi; Martin Bringmann; Bj(o)rn Usadel; Staffan Persson

    2009-01-01

    Transcriptional coordination, or co-expression, of genes may signify functional relatedness of the correspond-ing proteins. For example, several genes involved in secondary cell wall cellulose biosynthesis are co-expressed with genes engaged in the synthesis of xylan, which is a major component of the secondary cell wall. To extend these types of anal-yses, we investigated the co-expression relationships of all Carbohydrate-Active enZYmes (CAZy)-related genes for Arabidopsis thaliana. Thus, the intention was to transcriptionally link different cell wall-related processes to each other, and also to other biological functions. To facilitate easy manual inspection, we have displayed these interactions as networks and matrices, and created a web-based interface (http://aranet.mpimp-golm.mpg.de/corecarb) containing downloadable files for all the transcriptional associations.

  6. The role of the cell wall in plant immunity

    DEFF Research Database (Denmark)

    Malinovsky, Frederikke Gro; Fangel, Jonatan Ulrik; Willats, William George Tycho

    2014-01-01

    The battle between plants and microbes is evolutionarily ancient, highly complex, and often co-dependent. A primary challenge for microbes is to breach the physical barrier of host cell walls whilst avoiding detection by the plant's immune receptors. While some receptors sense conserved microbial...... features, others monitor physical changes caused by an infection attempt. Detection of microbes leads to activation of appropriate defense responses that then challenge the attack. Plant cell walls are formidable and dynamic barriers. They are constructed primarily of complex carbohydrates joined...... by numerous distinct connection types, and are subject to extensive post-synthetic modification to suit prevailing local requirements. Multiple changes can be triggered in cell walls in response to microbial attack. Some of these are well described, but many remain obscure. The study of the myriad of subtle...

  7. Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations

    OpenAIRE

    Wenchao Liu; Wanlin Cao; Jianwei Zhang; Qiyun Qiao; Heng Ma

    2016-01-01

    The seismic performance of recycled aggregate concrete (RAC) composite shear walls with different expandable polystyrene (EPS) configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ra...

  8. Stem and progenitor cells in biostructure of blood vessel walls

    Directory of Open Access Journals (Sweden)

    Krzysztof Korta

    2013-09-01

    Full Text Available Development of vascular and hematopoietic systems during organogenesis occurs at the same time. During vasculogenesis, a small part of cells does not undergo complete differentiation but stays on this level, “anchored” in tissue structures described as stem cell niches. The presence of blood vessels within tissue stem cell niches is typical and led to identification of niches and ensures that they are functioning. The three-layer biostructure of vessel walls for artery and vein, tunica: intima, media and adventitia, for a long time was defined as a mechanical barrier between vessel light and the local tissue environment. Recent findings from vascular biology studies indicate that vessel walls are dynamic biostructures, which are equipped with stem and progenitor cells, described as vascular wall-resident stem cells/progenitor cells (VW-SC/PC. Distinct zones for vessel wall harbor heterogeneous subpopulations of VW-SC/PC, which are described as “subendothelial or vasculogenic zones”. Recent evidence from in vitro and in vivo studies show that prenatal activity of stem and progenitor cells is not only limited to organogenesis but also exists in postnatal life, where it is responsible for vessel wall homeostasis, remodeling and regeneration. It is believed that VW-SC/PC could be engaged in progression of vascular disorders and development of neointima. We would like to summarize current knowledge about mesenchymal and progenitor stem cell phenotype with special attention to distribution and biological properties of VW-SC/PC in biostructures of intima, media and adventitia niches. It is postulated that in the near future, niches for VW-SC/PC could be a good source of stem and progenitor cells, especially in the context of vessel tissue bioengineering as a new alternative to traditional revascularization therapies.

  9. Particle Trajectories in Rotating Wall Cell Culture Devices

    Science.gov (United States)

    Ramachandran N.; Downey, J. P.

    1999-01-01

    Cell cultures are extremely important to the medical community since such cultures provide an opportunity to perform research on human tissue without the concerns inherent in experiments on individual humans. Development of cells in cultures has been found to be greatly influenced by the conditions of the culture. Much work has focused on the effect of the motions of cells in the culture relative to the solution. Recently rotating wall vessels have been used with success in achieving improved cellular cultures. Speculation and limited research have focused on the low shear environment and the ability of rotating vessels to keep cells suspended in solution rather than floating or sedimenting as the primary reasons for the improved cellular cultures using these devices. It is widely believed that the cultures obtained using a rotating wall vessel simulates to some degree the effect of microgravity on cultures. It has also been speculated that the microgravity environment may provide the ideal acceleration environment for culturing of cellular tissues due to the nearly negligible levels of sedimentation and shear possible. This work predicts particle trajectories of cells in rotating wall vessels of cylindrical and annular design consistent with the estimated properties of typical cellular cultures. Estimates of the shear encountered by cells in solution and the interactions with walls are studied. Comparisons of potential experiments in ground and microgravity environments are performed.

  10. Mixed Convection in a Composite System Bounded by Vertical Walls

    Directory of Open Access Journals (Sweden)

    N. Srivastava

    2010-01-01

    Full Text Available A combined convection process between two parallel vertical infinite walls, containing an incompressible viscous fluid layer and a fluid saturated porous layer has been presented analytically. There is a vertical axial variation of temperature in the upward direction along the walls. The Brinkman extended Darcy model is applied to describe the momentum transfer in the porous region. The viscosity of the fluid layer and the effective viscosity of the porous layer are assumed to be different. Also the thermal conductivities of both fluid and porous layers are assumed to be different. The graphs and tables have been used to distinguish the influence of distinct parameters on the velocity and skin-friction. It is determined that the velocity is intensified on making greater the temperature difference between the walls while increment in the viscosity ratio (porous/fluid parameter diminishes the velocity of the fluid. It has been observed that the numerical values of the skin-frictions have an increasing tendency with the increment in the values of temperature difference between the walls while decreasing tendency with the increment in the viscosity ratio parameter (porous/fluid.

  11. Characters of Fractal Ultrastructure in Wood Cell Wall

    Institute of Scientific and Technical Information of China (English)

    LI Beimei; ZHAO Guangjie

    2006-01-01

    Fractal theory was introduced in order to describe the ultrastructure of wood cell wall in this paper.The cellulose chain clusters around nano-scale were viewed as a fractal object that consists of many fibrillar structural units with different scales including microfibrils.On the basis of the morphological data of wood cell wall.fractal dimensions of multi-level fibrillar structural units were calculated by fractal-geometry approach,and then the morphological and structural characteristics of fibers as well as the influences on wood properties were investigated according to the dimensions.Besides,the fractal self-nesting character of the ultrastruture was also analyzed.

  12. Phagocytic properties of lung alveolar wall cells

    Directory of Open Access Journals (Sweden)

    Tanaka,Akisuke

    1974-04-01

    Full Text Available For the purpose to define the mechanism of heavy metal intoxication by inhalation, morphologic observations were made on rat lungs after nasal instillation of iron colloid particles of positive and negative electric charges. Histochemical observation was also made on the liver and spleen of these animals. The instilled iron colloid particles reach the alveolar cavity easily, as can be seen in the tissue sections stained by Prussian blue reaction. Alveolar macrophages do take up them avidly both of positive and negative charges, though much less the positive particles than negative ones. In contrast, the alveolar epithelial cells take up solely positive particles by phagocytosis but not negative ones. Electron microscope observation revealed that the positive particles are ingested by Type I epithelial cells by pinocytosis and by Type II cells by phagocytosis as well. Then the iron colloid particles are transferred into the basement membrane by exocytosis. Travelling through the basement membrane they are again taken up by capillary endothelial cells by phagocytosis. Some particles were found in the intercellular clefts of capillary endothelial cells but not any iron colloid particles in the intercellular spaces of epithelial cells and in the capillary lumen. However, the liver and spleen tissues of the animals given iron colloid showed a strong positive iron reaction. On the basis of these observations, the mechanism of acute intoxication by inhaling heavy metal dusts like lead fume is discussed from the view point of selective uptake of alveolar epithelial and capillary endothelial cells for the particles of the positive electric cha'rge.

  13. Role of Protein Glycosylation in Candida parapsilosis Cell Wall Integrity and Host Interaction

    Science.gov (United States)

    Pérez-García, Luis A.; Csonka, Katalin; Flores-Carreón, Arturo; Estrada-Mata, Eine; Mellado-Mojica, Erika; Németh, Tibor; López-Ramírez, Luz A.; Toth, Renata; López, Mercedes G.; Vizler, Csaba; Marton, Annamaria; Tóth, Adél; Nosanchuk, Joshua D.; Gácser, Attila; Mora-Montes, Héctor M.

    2016-01-01

    Candida parapsilosis is an important, emerging opportunistic fungal pathogen. Highly mannosylated fungal cell wall proteins are initial contact points with host immune systems. In Candida albicans, Och1 is a Golgi α1,6-mannosyltransferase that plays a key role in the elaboration of the N-linked mannan outer chain. Here, we disrupted C. parapsilosis OCH1 to gain insights into the contribution of N-linked mannosylation to cell fitness and to interactions with immune cells. Loss of Och1 in C. parapsilosis resulted in cellular aggregation, failure of morphogenesis, enhanced susceptibility to cell wall perturbing agents and defects in wall composition. We removed the cell wall O-linked mannans by β-elimination, and assessed the relevance of mannans during interaction with human monocytes. Results indicated that O-linked mannans are important for IL-1β stimulation in a dectin-1 and TLR4-dependent pathway; whereas both, N- and O-linked mannans are equally important ligands for TNFα and IL-6 stimulation, but neither is involved in IL-10 production. Furthermore, mice infected with C. parapsilosis och1Δ null mutant cells had significantly lower fungal burdens compared to wild-type (WT)-challenged counterparts. Therefore, our data are the first to demonstrate that C. parapsilosis N- and O-linked mannans have different roles in host interactions than those reported for C. albicans. PMID:27014229

  14. Cell Wall Polysaccharides of Candida albicans Induce Mast Cell Degranulation in the Gut

    OpenAIRE

    Sakurai, Atsuko; Yamaguchi, Natsu; Sonoyama, Kei

    2012-01-01

    We investigated Candida albicans-induced mast cell degranulation in vitro and in vivo. Cell wall fraction but not culture supernatant and cell membrane fraction prepared from hyphally grown C. albicans induced β-hexosaminidase release in RBL-2H3 cells. Cell wall mannan and soluble β-glucan fractions also induced β-hexosaminidase release. Histological examination of mouse forestomach showed that C. albicans gut colonization induces mast cell degranulation. However, intragastric administration ...

  15. A model of cell wall expansion based on thermodynamics of polymer networks

    Science.gov (United States)

    Veytsman, B. A.; Cosgrove, D. J.

    1998-01-01

    A theory of cell wall extension is proposed. It is shown that macroscopic properties of cell walls can be explained through the microscopic properties of interpenetrating networks of cellulose and hemicellulose. The qualitative conclusions of the theory agree with the existing experimental data. The dependence of the cell wall yield threshold on the secretion of the wall components is discussed.

  16. The Cellulose System in the Cell Wall of Micrasterias

    Science.gov (United States)

    Kim; Herth; Vuong; Chanzy

    1996-11-01

    The cellulose system of the cell wall of Micrasterias denticulata and Micrasterias rotata was analyzed by diffraction contrast transmission electron microscopy, electron diffraction, and X-ray analysis. The studies, achieved on disencrusted cell ghosts, confirmed that the cellulose microfibrils occurred in crisscrossed bands consisting of a number of parallel ribbon-like microfibrils. The individual microfibrils had thicknesses of 5 nm for a width of around 20 nm, but in some instances, two or three microfibrils merged into one another to yield larger monocrystalline domains reaching up to 60 nm in lateral size. The orientation of the cellulose of Micrasterias is very unusual, as it was found that in the cell wall, the equatorial crystallographic planes of cellulose having a d-spacing of 0.60 nm [(11;0) in the Ibeta cellulose unit cell defined by Sugiyama et al., 1991, Macromolecules 24, 4168-4175] were oriented perpendicular to the cell wall surface. Up to now, such orientation has been found only in Spirogyra, another member of the Zygnemataceae group. The unusual structure of the secondary wall cellulose of Micrasterias may be tentatively correlated with the unique organization of the terminal complexes, which in this alga occur as hexagonal arrays of rosettes. PMID:8986649

  17. The metabolic enzyme ManA reveals a link between cell wall integrity and chromosome morphology.

    OpenAIRE

    Maya Elbaz; Sigal Ben-Yehuda

    2010-01-01

    Author Summary The bacterial cell is resistant to extremes of osmotic pressure and protected against mechanical damages by the existence of a rigid outer shell defined as the cell wall. The strength of the cell wall is achieved by the presence of long glycan strands cross-linked by peptide side bridges. The cell wall is a dynamic structure continuously being synthesized and modified to allow for cell growth and division. Damaging the cell wall leads to abnormal cellular morphologies and cell ...

  18. Cell culture compositions

    Science.gov (United States)

    Dunn-Coleman, Nigel; Goedegebuur, Frits; Ward, Michael; Yiao, Jian

    2014-03-18

    The present invention provides a novel endoglucanase nucleic acid sequence, designated egl6 (SEQ ID NO:1 encodes the full length endoglucanase; SEQ ID NO:4 encodes the mature form), and the corresponding endoglucanase VI amino acid sequence ("EGVI"; SEQ ID NO:3 is the signal sequence; SEQ ID NO:2 is the mature sequence). The invention also provides expression vectors and host cells comprising a nucleic acid sequence encoding EGVI, recombinant EGVI proteins and methods for producing the same.

  19. Catalysts of plant cell wall loosening [version 1; referees: 2 approved

    OpenAIRE

    Cosgrove, Daniel J.

    2016-01-01

    The growing cell wall in plants has conflicting requirements to be strong enough to withstand the high tensile forces generated by cell turgor pressure while selectively yielding to those forces to induce wall stress relaxation, leading to water uptake and polymer movements underlying cell wall expansion. In this article, I review emerging concepts of plant primary cell wall structure, the nature of wall extensibility and the action of expansins, family-9 and -12 endoglucanases, family-16 xyl...

  20. An emerging role of pectic rhamnogalacturonanII for cell wall integrity

    OpenAIRE

    Reboul, Rebecca; Tenhaken, Raimund

    2012-01-01

    The plant cell wall is a complex network of different polysaccharides and glycoproteins, showing high diversity in nature. The essential components, tethering cell wall are under debate, as novel mutants challenge established models. The mutant ugd2,3 with a reduced supply of the important wall precursor UDP-glucuronic acid reveals the critical role of the pectic compound rhamnogalacturonanII for cell wall stability. This polymer seems to be more important for cell wall integrity than the pre...

  1. Analysis and seismic tests of composite shear walls with CFST columns and steel plate deep beams

    Science.gov (United States)

    Dong, Hongying; Cao, Wanlin; Wu, Haipeng; Zhang, Jianwei; Xu, Fangfang

    2013-12-01

    A composite shear wall concept based on concrete filled steel tube (CFST) columns and steel plate (SP) deep beams is proposed and examined in this study. The new wall is composed of three different energy dissipation elements: CFST columns; SP deep beams; and reinforced concrete (RC) strips. The RC strips are intended to allow the core structural elements — the CFST columns and SP deep beams — to work as a single structure to consume energy. Six specimens of different configurations were tested under cyclic loading. The resulting data are analyzed herein. In addition, numerical simulations of the stress and damage processes for each specimen were carried out, and simulations were completed for a range of location and span-height ratio variations for the SP beams. The simulations show good agreement with the test results. The core structure exhibits a ductile yielding mechanism characteristic of strong column-weak beam structures, hysteretic curves are plump and the composite shear wall exhibits several seismic defense lines. The deformation of the shear wall specimens with encased CFST column and SP deep beam design appears to be closer to that of entire shear walls. Establishing optimal design parameters for the configuration of SP deep beams is pivotal to the best seismic behavior of the wall. The new composite shear wall is therefore suitable for use in the seismic design of building structures.

  2. Regulation of genes involved in cell wall synthesis and structure during Ustilago maydis dimorphism.

    Science.gov (United States)

    Robledo-Briones, Mariana; Ruiz-Herrera, José

    2013-02-01

    The cell wall is the structure that provides the shape to fungal cells and protects them from the difference in osmotic pressure existing between the cytosol and the external medium. Accordingly, changes in structure and composition of the fungal wall must occur during cell differentiation, including the dimorphic transition of fungi. We analyzed, by use of microarrays, the transcriptional regulation of the 639 genes identified to be involved in cell wall synthesis and structure plus the secretome of the Basidiomycota species Ustilago maydis during its dimorphic transition induced by a change in pH. Of these, 189 were differentially expressed during the process, and using as control two monomorphic mutants, one yeast like and the other mycelium constitutive, 66 genes specific of dimorphism were identified. Most of these genes were up-regulated in the mycelial phase. These included CHS genes, genes involved in β-1,6-glucan synthesis, N-glycosylation, and proteins containing a residue of glycosylphosphatidylinositol, and a number of genes from the secretome. The possible significance of these data on cell wall plasticity is discussed.

  3. Pectic arabinan side chains are essential for pollen cell wall integrity during pollen development.

    Science.gov (United States)

    Cankar, Katarina; Kortstee, Anne; Toonen, Marcel A J; Wolters-Arts, Mieke; Houbein, Rudolf; Mariani, Celestina; Ulvskov, Peter; Jorgensen, Bodil; Schols, Henk A; Visser, Richard G F; Trindade, Luisa M

    2014-05-01

    Pectin is a complex polysaccharide and an integral part of the primary plant cell wall and middle lamella, contributing to cell wall mechanical strength and cell adhesion. To understand the structure-function relationships of pectin in the cell wall, a set of transgenic potato lines with altered pectin composition was analysed. The expression of genes encoding enzymes involved in pectin acetylation, degradation of the rhamnogalacturonan backbone and type and length of neutral side chains, arabinan and galactan in particular, has been altered. Upon crossing of different transgenic lines, some transgenes were not transmitted to the next generation when these lines were used as a pollen donor, suggesting male sterility. Viability of mature pollen was severely decreased in potato lines with reduced pectic arabinan, but not in lines with altered galactan side chains. Anthers and pollen of different developmental stages were microscopically examined to study the phenotype in more detail. Scanning electron microscopy of flowers showed collapsed pollen grains in mature anthers and in earlier stages cytoplasmic protrusions at the site of the of kin pore, eventually leading to bursting of the pollen grain and leaking of the cytoplasm. This phenomenon is only observed after the microspores are released and the tapetum starts to degenerate. Timing of the phenotype indicates a role for pectic arabinan side chains during remodelling of the cell wall when the pollen grain is maturing and dehydrating.

  4. Environmental stability of stem cell wall traits in alfalfa

    Science.gov (United States)

    The concentration of stem cell wall constituents in alfalfa, Medicago sativa L., herbage can affect dry matter intake and energy availability in dairy and beef production systems and impact energy conversion efficiency when alfalfa is used to produce biofuels. Stem Klason lignin, glucose, xylose, an...

  5. Evidence for a Melanin Cell Wall Component in Pneumocystis carinii

    OpenAIRE

    Icenhour, Crystal R.; Kottom, Theodore J.; Limper, Andrew H.

    2003-01-01

    Fluorescein isothiocyanate-labeled monoclonal antibodies specific for fungal melanin were used in this study to visualize melanin-like components of the Pneumocystis carinii cell wall. A colorimetric enzyme assay confirmed these findings. This is the first report of melanin-like pigments in Pneumocystis.

  6. Characterisation of cell-wall polysaccharides from mandarin segment membranes

    NARCIS (Netherlands)

    Coll-Almela, L.; Saura-Lopez, D.; Laencina-Sanchez, J.; Schols, H.A.; Voragen, A.G.J.; Ros-García, J.M.

    2015-01-01

    In an attempt to develop a process of enzymatic peeling of mandarin segments suitable for use on an industrial scale, the cell wall fraction of the segment membrane of Satsuma mandarin fruits was extracted to obtain a chelating agent-soluble pectin fraction (ChSS), a dilute sodium hydroxide-soluble

  7. The identification of cell wall degrading enzymes in Globodera rostochiensis

    NARCIS (Netherlands)

    Popeijus, H.E.

    2002-01-01

    This thesis describes the identification of cell wall degrading enzymes of the potato cyst nematode Globodera rostochiensis . A robust method using expressed sequence tags (ESTs) was applied to identify new parasitism related enzymes. One of the ESTs revealed the first pectate lyase from a metazoan

  8. Characterisation of cell wall polysaccharides in bilberries and black currants

    NARCIS (Netherlands)

    Hilz, H.

    2007-01-01

    During berry juice production, polysaccharides are released from the cell walls and cause thickening and high viscosity when the berries are mashed. Consequences are a low juice yield and a poor colour. This can be prevented by the use of enzymes that degrade these polysaccharides. To use these enzy

  9. Analyzing the complex machinery of cell wall biosynthesis

    NARCIS (Netherlands)

    Timmers, J.F.P.

    2009-01-01

    The plant cell wall polymers make up most of the plant biomass and provide the raw material for many economically important products including food, feed, bio-materials, chemicals, textiles, and biofuel. This broad range of functions and applications make the biosynthesis of these polysaccharides a

  10. Microstructural study of carbonized wood after cell wall sectioning

    NARCIS (Netherlands)

    Ishimaru, Kengo; Hata, Toshimitsu; Bronsveld, Paul; Imamura, Yuji

    2007-01-01

    Wooden blocks of Japanese cedar (Cryptomeria japonica) were carbonized at 700 and 1,800 degrees C. The microstructure was analyzed by transmission electron microscopy (TEM) and mu-Raman spectroscopy of the inner planes of wood cell walls. The predominant structure was of a turbostratic nature and no

  11. Hetero-oligomeric cell wall channels (porins) of Nocardia farcinica.

    Science.gov (United States)

    Kläckta, Christian; Knörzer, Philipp; Riess, Franziska; Benz, Roland

    2011-06-01

    The cell wall of Nocardia farcinica contains a cation-selective cell wall channel, which may be responsible for the limited permeability of the cell wall of N. farcinica for negatively charged antibiotics. Based on partial sequencing of the protein responsible for channel formation derived from N. farcinica ATTC 3318 we were able to identify the corresponding genes (nfa15890 and nfa15900) within the known genome of N. farcinica IFM 10152. The corresponding genes of N. farcinica ATTC 3318 were separately expressed in the Escherichia coli BL21DE3Omp8 strain and the N-terminal His10-tagged proteins were purified to homogeneity using immobilized metal affinity chromatography. The pure proteins were designated NfpANHis and NfpBNHis, for N. farcinica porin A and N. farcinica porin B. The two proteins were checked separately for channel formation in lipid bilayers. Our results clearly indicate that the proteins NfpANHis and NfpBNHis expressed in E. coli could only together form a channel in lipid bilayer membranes. This means that the cell wall channel of N. farcinica is formed by a heterooligomer. NfpA and NfpB form together a channel that may structurally be related to MspA of Mycobacterium smegmatis based on amino acid comparison and renaturation procedure. PMID:21092733

  12. Polymer mobility in cell walls of cucumber hypocotyls

    Science.gov (United States)

    Fenwick, K. M.; Apperley, D. C.; Cosgrove, D. J.; Jarvis, M. C.

    1999-01-01

    Cell walls were prepared from the growing region of cucumber (Cucumis sativus) hypocotyls and examined by solid-state 13C NMR spectroscopy, in both enzymically active and inactivated states. The rigidity of individual polymer segments within the hydrated cell walls was assessed from the proton magnetic relaxation parameter, T2, and from the kinetics of cross-polarisation from 1H to 13C. The microfibrils, including most of the xyloglucan in the cell wall, as well as cellulose, behaved as very rigid solids. A minor xyloglucan fraction, which may correspond to cross-links between microfibrils, shared a lower level of rigidity with some of the pectic galacturonan. Other pectins, including most of the galactan side-chain residues of rhamnogalacturonan I, were much more mobile and behaved in a manner intermediate between the solid and liquid states. The only difference observed between the enzymically active and inactive cell walls, was the loss of a highly mobile, methyl-esterified galacturonan fraction, as the result of pectinesterase activity.

  13. The digestion of yeast cell wall polysaccharides in veal calves

    NARCIS (Netherlands)

    Gaillard, B.D.E.; Weerden, van E.J.

    1976-01-01

    1. The digestibility of the cell wall polysaccharides of an alkane-grown yeast in different parts of the digestive tract of two veal calves fitted with re-entrant cannulas at the end of the ileum was studied by replacing part of the skim-milk powder of their ‘normal’, milk-substitute (all-milk-prote

  14. The MP65 gene is required for cell wall integrity, adherence to epithelial cells and biofilm formation in Candida albicans

    Directory of Open Access Journals (Sweden)

    Girolamo Antonietta

    2011-05-01

    Full Text Available Abstract Background The MP65 gene of Candida albicans (orf19.1779 encodes a putative β-glucanase mannoprotein of 65 kDa, which plays a main role in a host-fungus relationship, morphogenesis and pathogenicity. In this study, we performed an extensive analysis of a mp65Δ mutant to assess the role of this protein in cell wall integrity, adherence to epithelial cells and biofilm formation. Results The mp65Δ mutant showed a high sensitivity to a range of cell wall-perturbing and degrading agents, especially Congo red, which induced morphological changes such as swelling, clumping and formation of hyphae. The mp65Δ mutant showed an activation of two MAPKs (Mkc1p and Cek1p, a high level of expression of two stress-related genes (DDR48 and SOD5, and a modulated expression of β-glucan epitopes, but no gross changes in cell wall polysaccharide composition. Interestingly, the mp65Δ mutant displayed a marked reduction in adhesion to BEC and Caco-2 cells and severe defects in biofilm formation when compared to the wild type. All of the mentioned properties were totally or partially recovered in a revertant strain, demonstrating the specificity of gene deletion. Conclusions We demonstrate that the MP65 gene of Candida albicans plays a significant role in maintaining cell wall integrity, as well as in adherence to epithelia and biofilm formation, which are major virulence attributes of this fungus.

  15. Effects of Multi-Walled Carbon Nanotubes on The Mechanical Properties of Glass/Polyester Composites

    OpenAIRE

    M. Mehrdad Shokrieh; A Saeedi; M. Chitsazzadeh

    2012-01-01

    Excellent mechanical properties of carbon nanotubes (CNTs) make them outstanding candidate reinforcements to enhance mechanical properties of conventional composites. The glass/polyester composites are widely used in many industries and applications. Improving the mechanical properties of such composites with addition of CNTs can increase their applications. In this research, multi-walled carbon nanotube (MWCNT) at different weight ratios (0.05, 0.1, 0.3, 0.5 wt.%) were added to chopped stran...

  16. A Phosphorylated Pseudokinase Complex Controls Cell Wall Synthesis in Mycobacteria

    OpenAIRE

    Gee, Christine L.; Papavinasasundaram, Kadamba G.; Blair, Sloane R.; Baer, Christina E.; Falick, Arnold M.; King, David S.; Griffin, Jennifer E.; Venghatakrishnan, Harene; Zukauskas, Andrew; Wei, Jun-Rong; Dhiman, Rakesh K.; Crick, Dean C.; Rubin, Eric J.; Sassetti, Christopher M.; Alber, Tom

    2012-01-01

    Prokaryotic cell wall biosynthesis is coordinated with cell growth and division, but the mechanisms regulating this dynamic process remain obscure. Here, we describe a phosphorylation-dependent regulatory complex that controls peptidoglycan (PG) biosynthesis in Mycobacterium tuberculosis. We found that PknB, a PG-responsive Ser-Thr protein kinase (STPK), initiates complex assembly by phosphorylating a kinase-like domain in the essential PG biosynthetic protein, MviN. This domain was structura...

  17. Structure of Plant Cell Walls: XI. GLUCURONOARABINOXYLAN, A SECOND HEMICELLULOSE IN THE PRIMARY CELL WALLS OF SUSPENSION-CULTURED SYCAMORE CELLS.

    Science.gov (United States)

    Darvill, J E; McNeil, M; Darvill, A G; Albersheim, P

    1980-12-01

    The isolation, purification, and partial characterization of a glucuronoarabinoxylan, a previously unobserved component of the primary cell walls of dicotyledonous plants, are described. The glucuronoarabinoxylan constitutes approximately 5% of the primary walls of suspension-cultured sycamore cells. This glucuronoarabinoxylan possesses many of the structural characteristics of analogous polysaccharides that have been isolated from the primary and secondary cell walls of monocots as well as from the secondary cell walls of dicots. The glucuronoarabinoxylan of primary dicot cell walls has a linear beta-1,4-linked d-xylopyranosyl backbone with both neutral and acidic sidechains attached at intervals along its length. The acidic sidechains are terminated with glucuronosyl or 4-O-methyl glucuronosyl residues, whereas the neutral sidechains are composed of arabinosyl and/or xylosyl residues.

  18. Large-scale co-expression approach to dissect secondary cell wall formation across plant species

    Directory of Open Access Journals (Sweden)

    Colin eRuprecht

    2011-07-01

    Full Text Available Plant cell walls are complex composites largely consisting of carbohydrate-based polymers, and are generally divided into primary and secondary walls based on content and characteristics. Cellulose microfibrils constitute a major component of both primary and secondary cell walls and are synthesized at the plasma membrane by cellulose synthase (CESA complexes. Several studies in Arabidopsis have demonstrated the power of co-expression analyses to identify new genes associated with secondary wall cellulose biosynthesis. However, across-species comparative co-expression analyses remain largely unexplored. Here, we compared co-expressed gene vicinity networks of primary and secondary wall CESAs in Arabidopsis, barley, rice, poplar, soybean, Medicago and wheat, and identified gene families that are consistently co-regulated with cellulose biosynthesis. In addition to the expected polysaccharide acting enzymes, we also found many gene families associated with cytoskeleton, signaling, transcriptional regulation, oxidation and protein degradation. Based on these analyses, we selected and biochemically analyzed T-DNA insertion lines corresponding to approximately twenty genes from gene families that re-occur in the co-expressed gene vicinity networks of secondary wall CESAs across the seven species. We developed a statistical pipeline using principal component analysis (PCA and optimal clustering based on silhouette width to analyze sugar profiles. One of the mutants, corresponding to a pinoresinol reductase gene, displayed disturbed xylem morphology and held lower levels of lignin molecules. We propose that this type of large-scale co-expression approach, coupled with statistical analysis of the cell wall contents, will be useful to facilitate rapid knowledge transfer across plant species.

  19. Femtosecond Dynamics in Single Wall Carbon Nanotube/Poly(3-Hexylthiophene Composites

    Directory of Open Access Journals (Sweden)

    Alexandrou Ioannis

    2008-01-01

    Full Text Available AbstractFemtosecond transient absorption measurements on single wall carbon nanotube/poly(3-hexylthiophene composites are used to investigate the relaxation dynamics of this blended material. The influence of the addition of nanotubes in polymer matrix on the ultrashort relaxation dynamics is examined in detail. The introduction of nanotube/polymer heterojunctions enhances the exciton dissociation and quenches the radiative recombination of composites. The relaxation dynamics of these composites are compared with the fullerene derivative-polymer composites with the same matrix. These results provide explanation to the observed photovoltaic performance of two types of composites.

  20. Crushing Strength of Aluminum Honeycomb with Thinning Cell Wall

    Science.gov (United States)

    Ogasawara, Nagahisa; Chiba, Norimasa; Kobayashi, Eiji; Kikuchi, Yuji

    To evaluate the crash safety of automobiles, various collision tests are performed by the auto industry. In the offset frontal collision test and the side collision test, the target is an aluminum honeycomb material which has thinning cell walls. In this study, based on the analyses of the shock absorption mechanism, a new crushing strength formula is proposed. First, load-displacement curves obtained from compression tests in quasi-static condition showed an almost linear relation between a thinning rate of cell walls and a crushing strength. Second, based on Wierzbicki's theory, a new formula was proposed, which can estimate a crushing strength of a honeycomb material with thinning wall. In addition, a correcting equation which considered an elastic deformation was also proposed. Third, parametric analyses were carried out with a FE model which can simulate a delamination between cell walls. The results obtained from the theory and FEM almost corresponded to each other for a wide range of the thinning rate. Fourth, impact tests were carried out, in which the weight was dropped freely at the speed used for the automobile tests. Those results almost agreed well with the sum of the theoretical crush strength and the inside air pressure.

  1. Mixed-linkage (1-->3),(1-->4)-beta-D-glucan is not unique to the Poales and is an abundant component of Equisetum arvense cell walls

    DEFF Research Database (Denmark)

    Sørensen, Iben; Pettolino, Filomena A; Wilson, Sarah M;

    2008-01-01

    Mixed-linkage (1-->3),(1-->4)-beta-D-glucan (MLG) is widely considered to be a defining feature of the cell walls of plants in the Poales order. However, we conducted an extensive survey of cell-wall composition in diverse land plants and discovered that MLG is also abundant in the walls...... consists mostly of cellotetraose rather than cellotetriose, and lacks long 1,4-beta-linked glucan blocks. Monosaccharide linkage analyses and immunochemical profiling indicated that, in E. arvense, MLG is a component of cell walls that have a novel architecture that differs significantly from...... that of the generally recognized type I and II cell walls. Unlike in type II walls, MLG in E. arvense does not appear to be co-extensive with glucuroarabinoxylans but occurs in walls that are rich in pectin. Immunofluorescence and immunogold localization showed that MLG occurs in both young and old regions of E...

  2. Esterified phenolics of the cell walls of chufa (Cyperus esculentusL. ) tubers and their role in texture.

    Science.gov (United States)

    Parker, M L; Ng, A; Smith, A C; Waldron, K W

    2000-12-01

    Chufas (Cyperus esculentus) are edible tubers that, like Chinese waterchestnut (CWC), are very crisp when raw and do not soften when cooked. The present study compares the mechanical properties of chufas with those of potato and CWC in relation to the carbohydrate and phenolic compositions of the cell walls. The cutting toughness of raw chufa was higher than that of raw CWC and potato; its value decreased on boiling, as also observed with CWC, but remained over twice that of raw potato. Chufa cell walls were rich in xylose, arabinose, glucose, uronic acid, and galactose, with minor quantities of mannose. The cell walls of the parenchyma exhibited a uniform pH-dependent autofluorescence indicating the presence of cinnamic acid derivatives. Analysis of these revealed that peeled tuber cell walls are rich in ferulic acid, whereas p-coumaric acid dominates the monomeric phenol fraction of the skin. Cell wall material from both skin and peeled tubers contains a significant amount of different diferulic acids ( approximately 20% of the wall ferulic acid), consisting mainly of the 8-O-4'-, 8-5'-, and 5-5'-dimers. These are potentially available to form thermally stable cross-links between polysaccharides within the wall and between cells. This may confer thermal stability of texture. PMID:11141285

  3. Macroporous silica–alumina composites with mesoporous walls

    Indian Academy of Sciences (India)

    Gautam Gundiah

    2001-04-01

    Macroporous silica–alumina composites with mesopores have been prepared by employing polymethylmethacrylate beads as templates in the presence of the cationic surfactant, N-cetyl-N,N,N-trimethylammonium bromide. The Si/Al ratio in the composites has been varied between 4.5 and 48 and the occurrence of mesopores has been verified by X-ray diffraction. The surface areas of the samples vary between 676 and 1038 m2g–1, with the highest value in the sample with Si/Al = 48.

  4. Changes in the chemical properties and swelling coefficient of alfalfa root cell walls in the presence of toluene as a toxic agent.

    Science.gov (United States)

    Sharifi, M; Khoshgoftarmanesh, A H; Hadadzadeh, H

    2016-04-01

    The influence of toluene pollution on the chemical properties and swelling coefficient of root cell walls in alfalfa (Medicago sativa L.) was investigated. Two sets of alfalfa seedlings were selected and one set was treated with 450 mg L(-1) toluene in the nutrient solution under hydroponic culture. Thirty days after treatment with toluene, alfalfa plants were harvested and the root cell walls were isolated. Fourier-transform infrared (FTIR) spectroscopy was carried out for the characterization of the root cell walls composition. The cation exchange capacity (CEC) and the swelling coefficient of the root cell walls (Kcw) were estimated at various pH values. The toluene contamination significantly reduced the mass of the cell wall material in the alfalfa roots. According to the FTIR spectra, the toluene pollution can change the alfalfa root cell wall properties by reducing the cell wall functional groups. These functional groups are probably related to the proteins and polysaccharides in the cell wall. Also, toluene pollution strongly reduced CEC and Kcw of the root cell walls. The results show that the decrease in the active sites of adsorption on the root cell walls as a response to toluene pollution can affect the water flow rate and the mineral nutrients uptake by roots. PMID:26728292

  5. Finite Element Analysis of Composite Hardened Walls Subjected to Blast Loads

    Directory of Open Access Journals (Sweden)

    Girum S. Urgessa

    2009-01-01

    Full Text Available Problem statement: There is currently no standard design guideline to determine the number of composites needed to retrofit masonry walls in order to withstand a given explosion. Past design approaches were mainly based on simplified single-degree-of-freedom analysis. A finite element analysis was conducted for concrete masonry walls hardened with composites and subjected to short duration blast loads. Approach: The analysis focused on displacement time history responses which form the basis for retrofit design guidelines against blast loadings. The blast was determined from 0.5 kg equivalent TNT explosive at 1.83 m stand-off distance to simulate small mailroom bombs. Two and four layered retrofitted walls were investigated. Uncertainties in the finite model analysis of walls such as pressure distributions, effect of mid height explosive bursts versus near the ground explosive bursts and variations in modulus of elasticity of the wall were presented. Results: Uniformly distributed blast loads over the retrofitted wall height produced a small difference in peak displacement results when compared to the non-uniform pressure distribution. Ground explosive burst was shown to produce a 62.7% increase in energy and a higher peak displacement response when compared to mid-height explosive burst. Conclusion: The parametric study on the variation of modulus of elasticity of concrete masonry showed no significant effect on peak displacement affirming the use of the resistance deflection contribution of the composite in retrofit designs.

  6. In situ microscopic observation of chitin and fungal cells with chitinous cell walls in hydrothermal conditions

    OpenAIRE

    Shigeru Deguchi; Kaoru Tsujii; Koki Horikoshi

    2015-01-01

    Recent findings of intact chitin in fossil records suggest surprisingly high recalcitrance of this biopolymer during hydrothermal treatments. We also know in the experience of everyday life that mushroom, cells of which have chitinous cell walls, do not fall apart however long they are simmered. We used in situ optical microscopy to examine chitin and fungal cells with chitinous cell walls during hydrothermal treatments, and obtained direct evidence that they remained undegraded at temperatur...

  7. Seasonal biochemical changes in composition of body wall tissues of sea cucumber Apostichopus japonicus

    Science.gov (United States)

    Gao, Fei; Xu, Qiang; Yang, Hongsheng

    2011-03-01

    Seasonal Variation in proximate, amino acid and fatty acid composition of the body wall of sea cucumber Apostichopus japonicus was evaluated. The proximate composition, except for ash content, changed significantly among seasons ( PEPA (20:5n-3), AA (20:4n-6) and DHA (22:6n-3) were the major polyunsaturated fatty acids (PUFA). The proportions of SFA and PUFA yielded significant seasonal variations ( P<0.001), but MUFA did not changed significantly. The results indicated that the biochemical compositions of the body wall in A. japonicus were significantly influenced by seasons and that the body wall tissue is an excellent source of protein, MUFA and n-3 PUFA for humans.

  8. In Plan Shear Retrofit of Masonry Walls with Fibre Reinforced Polymer Composites Experimental Investigations

    Directory of Open Access Journals (Sweden)

    Tamás Nagy-György

    2006-01-01

    Full Text Available The paper presents the results from tests on clay brick masonry walls strengthened using fiber reinforced polymer (FRP composites. Five 1.50x1.50 m wall specimens have been subjected to pure in plan shear loads up to failure and then retrofitted on one side, with different types, percentages and lay-ups of the fiber sheets. Based on the experi¬mental results, it was proven the effectiveness of using externally bonded composites for retrofitting brick masonry walls, with less disruption during strengthening, and in this way with reduced costs compared with other conventional repairing and strengthening tech¬niques. Performances of the different strengthening configurations were compared in terms of ultimate load, strain in composite and failure mechanism.

  9. Identification of Cell Wall Synthesis Regulatory Genes Controlling Biomass Characteristics and Yield in Rice (Oryza Sativa)

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Zhaohua PEng [Mississippi State University; Ronald, Palmela [UC-Davis; Wang, Guo-Liang [The Ohio State University

    2013-04-26

    This project aims to identify the regulatory genes of rice cell wall synthesis pathways using a cell wall removal and regeneration system. We completed the gene expression profiling studies following the time course from cell wall removal to cell wall regeneration in rice suspension cells. We also completed, total proteome, nuclear subproteome and histone modification studies following the course from cell wall removal and cell wall regeneration process. A large number of differentially expressed regulatory genes and proteins were identified. Meanwhile, we generated RNAi and over-expression transgenic rice for 45 genes with at least 10 independent transgenic lines for each gene. In addition, we ordered T-DNA and transposon insertion mutants for 60 genes from Korea, Japan, and France and characterized the mutants. Overall, we have mutants and transgenic lines for over 90 genes, exceeded our proposed goal of generating mutants for 50 genes. Interesting Discoveries a) Cell wall re-synthesis in protoplasts may involve a novel cell wall synthesis mechanism. The synthesis of the primary cell wall is initiated in late cytokinesis with further modification during cell expansion. Phragmoplast plays an essential role in cell wall synthesis. It services as a scaffold for building the cell plate and formation of a new cell wall. Only one phragmoplast and one new cell wall is produced for each dividing cell. When the cell wall was removed enzymatically, we found that cell wall re-synthesis started from multiple locations simultaneously, suggesting that a novel mechanism is involved in cell wall re-synthesis. This observation raised many interesting questions, such as how the starting sites of cell wall synthesis are determined, whether phragmoplast and cell plate like structures are involved in cell wall re-synthesis, and more importantly whether the same set of enzymes and apparatus are used in cell wall re-synthesis as during cytokinesis. Given that many known cell wall

  10. Surface Analyses and Immune Reactivities of Major Cell Wall-Associated Proteins of Group A Streptococcus

    OpenAIRE

    Cole, Jason N; Ramirez, Ruben D.; Currie, Bart J.; Cordwell, Stuart J.; Djordjevic, Steven P.; Mark J Walker

    2005-01-01

    A proteomic analysis was undertaken to identify cell wall-associated proteins of Streptococcus pyogenes. Seventy-four distinct cell wall-associated proteins were identified, 66 of which were novel. Thirty-three proteins were immunoreactive with pooled S. pyogenes-reactive human antisera. Biotinylation of the GAS cell surface identified 23 cell wall-associated proteins that are surface exposed.

  11. Pectic arabinan side chains are essential for pollen cell wall integrity during pollen development

    NARCIS (Netherlands)

    Cankar, K.; Kortstee, A.J.; Toonen, M.A.J.; Wolters-Arts, M.; Houbein, R.; Mariani, C.; Ulvskov, P.; Jorgensen, B.; Schols, H.A.; Visser, R.G.F.; Trindade, L.M.

    2014-01-01

    Pectin is a complex polysaccharide and an integral part of the primary plant cell wall and middle lamella, contributing to cell wall mechanical strength and cell adhesion. To understand the structure–function relationships of pectin in the cell wall, a set of transgenic potato lines with altered pec

  12. Targeted and non-targeted effects in cell wall polysaccharides from transgenetically modified potato tubers

    NARCIS (Netherlands)

    Huang, J.H.

    2016-01-01

    The plant cell wall is a chemically complex network composed mainly of polysaccharides. Cell wall polysaccharides surround and protect plant cells and are responsible for the stability and rigidity of plant tissue. Pectin is a major component of primary cell wall and the middle lamella of plants. Ho

  13. Influence of sorbitol on protein production and glycosylation and cell wall formation in Trichoderma reesei.

    Science.gov (United States)

    Górka-Nieć, Wioletta; Perlińska-Lenart, Urszula; Zembek, Patrycja; Palamarczyk, Grażyna; Kruszewska, Joanna S

    2010-10-01

    Sorbitol is often used at 1 mol/liter as an osmotic stabilizer for cultivation of fungi with a fragile cell wall phenotype. On the other hand, at this concentration sorbitol causes an osmotic stress in fungal cells resulting in intensive production of intracellular glycerol. The highly increased consumption of glucose for glycerol synthesis may lead to changes in processes requiring carbohydrate residues. This study provides new information on the consequences of osmotic stress to the cell wall composition, protein production and glycosylation, and cell morphology of Trichoderma reesei. We observed that high osmolarity conditions enhanced biomass production and strongly limited synthesis of cell wall glucans and chitin. Moreover, in these conditions the amount of secreted protein decreased nearly ten-fold and expression of cbh1 and cbh2 genes coding for cellobiohydrolase I and cellobiohydrolase II, the main secretory proteins in T. reesei, was inhibited resulting in a lack of the proteins in the cell and cultivation medium. The activity of DPM synthase, enzyme engaged in both N- and O-glycosylation pathways, was reduced two-fold, suggesting an overall inhibition of protein glycosylation. However, the two modes of glycosylation were affected divergently: O-glycosylation of secreted proteins decreased in the early stages of growth while N-glycosylation significantly increased in the stationary phase.

  14. Orbital wall infarction in child with sickle cell disease.

    Science.gov (United States)

    Janssens, C; Claeys, L; Maes, P; Boiy, T; Wojciechowski, M

    2015-12-01

    We present the case of a 17-year-old boy, known with homozygous sickle cell disease, who was admitted because of generalised pain. He developed bilateral periorbital oedema and proptosis, without pain or visual disturbances. In addition to hyperhydration, oxygen and analgesia IV antibiotics were started, to cover a possible osteomyelitis. Patients with sickle cell disease are at risk for vaso-occlusive crises, when the abnormally shaped red blood cells aggregate and block the capillaries. Such a crisis typically presents at a location with high bone marrow activity, as the vertebrae and long bones. At an early age, the bone marrow is still active at other sites, for example the orbital wall, and thus infarction can also occur there. Thus, in young persons with sickle cell disease, it is important to consider orbital wall infarction in the differential diagnosis, since the approach is different from osteomyelitis. If the disease is complicated by an orbital compression syndrome, corticosteroids or surgical intervention may be necessary to preserve the vision. In our patient, an MRI of the orbitae demonstrated periorbital oedema with bone anomalies in the orbital and frontal bones, confirming orbital wall infarction. Ophthalmological examination revealed no signs of pressure on the nervus opticus. The patient recovered gradually with conservative treatment.

  15. Orbital wall infarction in child with sickle cell disease.

    Science.gov (United States)

    Janssens, C; Claeys, L; Maes, P; Boiy, T; Wojciechowski, M

    2015-12-01

    We present the case of a 17-year-old boy, known with homozygous sickle cell disease, who was admitted because of generalised pain. He developed bilateral periorbital oedema and proptosis, without pain or visual disturbances. In addition to hyperhydration, oxygen and analgesia IV antibiotics were started, to cover a possible osteomyelitis. Patients with sickle cell disease are at risk for vaso-occlusive crises, when the abnormally shaped red blood cells aggregate and block the capillaries. Such a crisis typically presents at a location with high bone marrow activity, as the vertebrae and long bones. At an early age, the bone marrow is still active at other sites, for example the orbital wall, and thus infarction can also occur there. Thus, in young persons with sickle cell disease, it is important to consider orbital wall infarction in the differential diagnosis, since the approach is different from osteomyelitis. If the disease is complicated by an orbital compression syndrome, corticosteroids or surgical intervention may be necessary to preserve the vision. In our patient, an MRI of the orbitae demonstrated periorbital oedema with bone anomalies in the orbital and frontal bones, confirming orbital wall infarction. Ophthalmological examination revealed no signs of pressure on the nervus opticus. The patient recovered gradually with conservative treatment. PMID:26790559

  16. Antigenicity and immunogenicity of an extract from the cell wall and cell membrane of Histoplasma capsulatum yeast cells.

    OpenAIRE

    Gómez, A M; Rhodes, J C; Deepe, G S

    1991-01-01

    In order to identify T-cell antigens from Histoplasma capsulatum yeast cells, we prepared a detergent extract of the cell wall and cell membrane of yeast-phase H. capsulatum G217B and analyzed its antigenicity and immunogenicity. Mice injected with viable H. capsulatum yeast cells or with 500 or 1,000 micrograms of the extract mounted a delayed-type hypersensitivity response to solubilized cell wall and cell membrane. Vaccination with this antigenic preparation conferred a protective immune r...

  17. Melanin is an essential component for the integrity of the cell wall of Aspergillus fumigatus conidia

    Directory of Open Access Journals (Sweden)

    Georgeault Sonia

    2009-08-01

    Full Text Available Abstract Background Aspergillus fumigatus is the most common agent of invasive aspergillosis, a feared complication in severely immunocompromised patients. Despite the recent commercialisation of new antifungal drugs, the prognosis for this infection remains uncertain. Thus, there is a real need to discover new targets for therapy. Particular attention has been paid to the biochemical composition and organisation of the fungal cell wall, because it mediates the host-fungus interplay. Conidia, which are responsible for infections, have melanin as one of the cell wall components. Melanin has been established as an important virulence factor, protecting the fungus against the host's immune defences. We suggested that it might also have an indirect role in virulence, because it is required for correct assembly of the cell wall layers of the conidia. Results We used three A. fumigatus isolates which grew as white or brown powdery colonies, to demonstrate the role of melanin. Firstly, sequencing the genes responsible for biosynthesis of melanin (ALB1, AYG1, ARP1, ARP2, ABR1 and ABR2 showed point mutations (missense mutation, deletion or insertion in the ALB1 gene for pigmentless isolates or in ARP2 for the brownish isolate. The isolates were then shown by scanning electron microscopy to produce numerous, typical conidial heads, except that the conidia were smooth-walled, as previously observed for laboratory mutants with mutations in the PKSP/ALB1 gene. Flow cytometry showed an increase in the fibronectin binding capacity of conidia from mutant isolates, together with a marked decrease in the binding of laminin to the conidial surface. A marked decrease in the electronegative charge of the conidia and cell surface hydrophobicity was also seen by microelectrophoresis and two-phase partitioning, respectively. Ultrastructural studies of mutant isolates detected considerable changes in the organisation of the conidial wall, with the loss of the outermost

  18. Cell wall bound anionic peroxidases from asparagus byproducts.

    Science.gov (United States)

    Jaramillo-Carmona, Sara; López, Sergio; Vazquez-Castilla, Sara; Jimenez-Araujo, Ana; Rodriguez-Arcos, Rocio; Guillen-Bejarano, Rafael

    2014-10-01

    Asparagus byproducts are a good source of cationic soluble peroxidases (CAP) useful for the bioremediation of phenol-contaminated wastewaters. In this study, cell wall bound peroxidases (POD) from the same byproducts have been purified and characterized. The covalent forms of POD represent >90% of the total cell wall bound POD. Isoelectric focusing showed that whereas the covalent fraction is constituted primarily by anionic isoenzymes, the ionic fraction is a mixture of anionic, neutral, and cationic isoenzymes. Covalently bound peroxidases were purified by means of ion exchange chromatography and affinity chromatography. In vitro detoxification studies showed that although CAP are more effective for the removal of 4-CP and 2,4-DCP, anionic asparagus peroxidase (AAP) is a better option for the removal of hydroxytyrosol (HT), the main phenol present in olive mill wastewaters.

  19. Cytoplasmic streaming in plant cells: the role of wall slip.

    Science.gov (United States)

    Wolff, K; Marenduzzo, D; Cates, M E

    2012-06-01

    We present a computer simulation study, via lattice Boltzmann simulations, of a microscopic model for cytoplasmic streaming in algal cells such as those of Chara corallina. We modelled myosin motors tracking along actin lanes as spheres undergoing directed motion along fixed lines. The sphere dimension takes into account the fact that motors drag vesicles or other organelles, and, unlike previous work, we model the boundary close to which the motors move as walls with a finite slip layer. By using realistic parameter values for actin lane and myosin density, as well as for endoplasmic and vacuole viscosity and the slip layer close to the wall, we find that this simplified view, which does not rely on any coupling between motors, cytoplasm and vacuole other than that provided by viscous Stokes flow, is enough to account for the observed magnitude of streaming velocities in intracellular fluid in living plant cells.

  20. Roles of tRNA in cell wall biosynthesis

    DEFF Research Database (Denmark)

    Dare, Kiley; Ibba, Michael

    2012-01-01

    responsible for cell wall modifications, aminoacyl-phosphatidylglycerol synthases (aaPGSs) and Fem, were discovered some time ago, they have recently become of intense interest for their roles in the antimicrobial resistance of pathogenic microorganisms. The addition of positively charged amino acids...... to phosphatidylglycerol (PG) by aaPGSs neutralizes the lipid bilayer making the bacteria less susceptible to positively charged antimicrobial agents. Fem transferases utilize aa-tRNA to form peptide bridges that link strands of peptidoglycan. These bridges vary among the bacterial species in which they are present...... and play a role in resistance to antibiotics that target the cell wall. Additionally, the formation of truncated peptides results in shorter peptide bridges and loss of branched linkages which makes bacteria more susceptible to antimicrobials. A greater understanding of the structure and substrate...

  1. Effects of spaceflight on polysaccharides of Saccharomyces cerevisiae cell wall.

    Science.gov (United States)

    Liu, Hong-Zhi; Wang, Qiang; Liu, Xiao-Yong; Tan, Sze-Sze

    2008-12-01

    Freeze-dried samples of four Saccharomyces cerevisiae strains, namely, FL01, FL03, 2.0016, and 2.1424, were subjected to spaceflight. After the satellite's landing on Earth, the samples were recovered and changes in yeast cell wall were analyzed. Spaceflight strains of all S. cerevisiae strains showed significant changes in cell wall thickness (P growth curve analysis showed spaceflight S. cerevisiae 2.0016 had a faster growth rate, shorter lag phase periods, higher final biomass, and higher content of beta-glucan. Genetic stability analysis showed that prolonged subculturing of spaceflight strain S. cerevisiae 2.0016 did not lead to the appearance of variants, indicating that the genetic stability of S. cerevisiae 2.0016 mutant could be sufficient for its exploitation of beta-glucan production. PMID:18797865

  2. Regulation of plant cells, cell walls and development by mechanical signals

    Energy Technology Data Exchange (ETDEWEB)

    Meyerowitz, Elliot M. [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2016-06-14

    The overall goal of the revised scope of work for the final year of funding was to characterize cell wall biosynthesis in developing cotyledons and in the shoot apical meristem of Arabidopsis thaliana, as a way of learning about developmental control of cell wall biosynthesis in plants, and interactions between cell wall biosynthesis and the microtubule cytoskeleton. The proposed work had two parts – to look at the effect of mutation in the SPIRAL2 gene on microtubule organization and reorganization, and to thoroughly characterize the glycosyltransferase genes expressed in shoot apical meristems by RNA-seq experiments, by in situ hybridization of the RNAs expressed in the meristem, and by antibody staining of the products of the glycosyltransferases in meristems. Both parts were completed; the spiral2 mutant was found to speed microtubule reorientation after ablation of adjacent cells, supporting our hypothesis that reorganization correlates with microtubule severing, the rate of which is increased by the mutation. The glycosyltransferase characterization was completed and published as Yang et al. (2016). Among the new things learned was that primary cell wall biosynthesis is strongly controlled both by cell type, and by stage of cell cycle, implying not only that different, even adjacent, cells can have different sugar linkages in their (nonshared) walls, but also that a surprisingly large proportion of glycosyltransferases is regulated in the cell cycle, and therefore that the cell cycle regulates wall maturation to a degree previously unrecognized.

  3. REGULATION OF PLANT CELLS, CELL WALLS AND DEVELOPMENT BY MECHANICAL SIGNALS

    Energy Technology Data Exchange (ETDEWEB)

    Meyerowitz, Elliot M [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2016-08-22

    The overall goal of the revised scope of work for the final year of funding was to characterize cell wall biosynthesis in developing cotyledons and in the shoot apical meristem of Arabidopsis thaliana, as a way of learning about developmental control of cell wall biosynthesis in plants, and interactions between cell wall biosynthesis and the microtubule cytoskeleton. The proposed work had two parts – to look at the effect of mutation in the SPIRAL2 gene on microtubule organization and reorganization, and to thoroughly characterize the glycosyltransferase genes expressed in shoot apical meristems by RNA-seq experiments, by in situ hybridization of the RNAs expressed in the meristem, and by antibody staining of the products of the glycosyltransferases in meristems. Both parts were completed; the spiral2 mutant was found to speed microtubule reorientation after ablation of adjacent cells, supporting our hypothesis that reorganization correlates with microtubule severing, the rate of which is increased by the mutation. The glycosyltransferase characterization was completed and published as Yang et al. (2016). Among the new things learned was that primary cell wall biosynthesis is strongly controlled both by cell type, and by stage of cell cycle, implying not only that different, even adjacent, cells can have different sugar linkages in their (nonshared) walls, but also that a surprisingly large proportion of glycosyltransferases is regulated in the cell cycle, and therefore that the cell cycle regulates wall maturation to a degree previously unrecognized.

  4. Cell wall glycoproteins at interaction sites between parasitic giant dodder (Cuscuta reflexa) and its host Pelargonium zonale.

    Science.gov (United States)

    Striberny, Bernd; Krause, Kirsten

    2015-01-01

    The process of host plant penetration by parasitic dodder (genus Cuscuta) is accompanied by molecular and structural changes at the host/parasite interface. Recently, changes in pectin methyl esterification levels in the host cell walls abutting parasitic cells in established infection sites were reported. In addition to that, we show here that the composition of cell wall glycoproteins in Cuscuta-infected Pelargonium zonale undergoes substantial changes. While several arabinogalactan protein epitopes exhibit decreased abundances in the vicinity of the Cuscuta reflexa haustorium, extensins tend to increase in the infected areas. PMID:26367804

  5. Cell wall glycoproteins at interaction sites between parasitic giant dodder (Cuscuta reflexa) and its host Pelargonium zonale.

    Science.gov (United States)

    Striberny, Bernd; Krause, Kirsten

    2015-01-01

    The process of host plant penetration by parasitic dodder (genus Cuscuta) is accompanied by molecular and structural changes at the host/parasite interface. Recently, changes in pectin methyl esterification levels in the host cell walls abutting parasitic cells in established infection sites were reported. In addition to that, we show here that the composition of cell wall glycoproteins in Cuscuta-infected Pelargonium zonale undergoes substantial changes. While several arabinogalactan protein epitopes exhibit decreased abundances in the vicinity of the Cuscuta reflexa haustorium, extensins tend to increase in the infected areas.

  6. Cell wall perturbation sensitizes fungi to the antimalarial drug chloroquine

    OpenAIRE

    Islahudin, Farida; Khozoie, Combiz; Bates, Steven; Ting, Kang-Nee; Pleass, Richard J.; Avery, Simon V.

    2013-01-01

    Chloroquine (CQ) has been a mainstay of antimalarial drug treatment for several decades. Additional therapeutic actions of CQ have been described, including some reports of fungal inhibition. Here we investigated the action of CQ in fungi, including the yeast model Saccharomyces cerevisiae. A genomewide yeast deletion strain collection was screened against CQ, revealing that bck1Δ and slt2Δ mutants of the cell wall integrity pathway are CQ hypersensitive. This phenotype was rescued with sorbi...

  7. Life behind cell walls: paradigm lost, paradigm regained.

    Science.gov (United States)

    Lamport, D T

    2001-09-01

    This review of the living cell wall and its protein components is in two parts. The first is anecdotal. A personal account spanning over 40 years research may perhaps be an antidote to one stereotypical view of scientists as detached and humorless. The second part deals with the meaning of function, particularly as it applies to hydroxyproline-rich glycoproteins. Function is a difficult word to define objectively. However, with help from such luminaries as Humpty Dumpty: "A word means what I want it to mean, neither more nor less," and Wittgenstein: "Giving examples of usage ... is the only way to talk about meaning," it is possible to construct a ziggurat representing increasingly complex levels of organization from molecular structure to ecology. Forty years ago I suggested that hydroxyproline-rich structural proteins played a key role in cell wall functioning. But because the bulk of the wall is carbohydrate, there has been an understandable resistance to paradigm change. Expansins, paradoxically, contribute greatly to this resistance because their modus operandi as cell-wall-loosening proteins is based on the idea that they break hydrogen bonds between polysaccharide chains allowing slippage. However, this view is not consistent with the recent discovery [Grobe et al. (1999) Eur. J. Biochem 263: 33-40] that beta-expansins may be proteases, as it implies that the extensin network is not a straightjacket but a substrate for expansin in muro. Such a direct role for extensins in both negative and positive regulation of cell expansion and elongation may constitute a major morphogenetic mechanism operating at all levels of plant growth and development.

  8. The Mechanisms of Plant Cell Wall Deconstruction during Enzymatic Hydrolysis

    OpenAIRE

    Thygesen, Lisbeth G; Thybring, Emil E.; Johansen, Katja S.; Claus Felby

    2014-01-01

    Mechanical agitation during enzymatic hydrolysis of insoluble plant biomass at high dry matter contents is indispensable for the initial liquefaction step in biorefining. It is known that particle size reduction is an important part of liquefaction, but the mechanisms involved are poorly understood. Here we put forward a simple model based on mechanical principles capable of capturing the result of the interaction between mechanical forces and cell wall weakening via hydrolysis of glucosidic ...

  9. Antioxidant properties of cell wall polysaccharides of Stevia rebaudiana leaves

    OpenAIRE

    Mediesse Kengne Francine; Woguia Alice Louise; Fogue Souopgui Pythagore; Atogho-Tiedeu Barbara; Simo Gustave; Thaddée Boudjeko

    2014-01-01

    Objective: To examine the total phenolic and protein contents, and the antioxidant activities of cell wall polysaccharide fractions of Stevia rebaudiana leaves. Methods: Three different polysaccharide-enriched fractions, namely FPE (extract with 50 mmol/ L ethylene diamine tetra acetic acid), FPK (extract with 0.05 mol/L KOH) and FH (extract with 4 mol/L KOH) were extracted from Stevia rebaudiana leaves. The antioxidant activity of these fractions was evaluated based on thei...

  10. Enzyme Amplified Detection of Microbial Cell Wall Components

    Science.gov (United States)

    Wainwright, Norman R.

    2004-01-01

    This proposal is MBL's portion of NASA's Johnson Space Center's Astrobiology Center led by Principal Investigator, Dr. David McKay, entitled: 'Institute for the Study of Biomarkers in Astromaterials.' Dr. Norman Wainwright is the principal investigator at MBL and is responsible for developing methods to detect trace quantities of microbial cell wall chemicals using the enzyme amplification system of Limulus polyphemus and other related methods.

  11. Cell-wall hemicelluloses as mobile carbon stores in plants

    OpenAIRE

    Schädel, Christina

    2009-01-01

    Hemicelluloses are the second most abundant polysaccharide in nature after cellulose. So far, the chemical heterogeneity of cell-wall hemicelluloses and the relatively large sample-volume required in existing methods represent major obstacles for large-scale, cross-species analyses of this important plant compounds. Here, we apply a new micro-extraction method to analyse hemicelluloses and the ratio of ‘cellulose and lignin’ to hemicelluloses in different tissues of 28 plant species comprisin...

  12. Protein transport across the cell wall of monoderm Gram-positive bacteria

    OpenAIRE

    Forster, Brian M.; Marquis, Hélène

    2012-01-01

    In monoderm (single membrane) Gram-positive bacteria, the majority of secreted proteins are first translocated across the cytoplasmic membrane into the inner wall zone. For a subset of these proteins, final destination is within the cell envelope either as membrane-anchored or cell wall-anchored proteins, whereas another subset of proteins is destined to be transported across the cell wall into the extracellular milieu. Although the cell wall is a porous structure, there is evidence that, for...

  13. The cell wall and endoplasmic reticulum stress responses are coordinately regulated in Saccharomyces cerevisiae

    OpenAIRE

    Krysan, Damian J.

    2009-01-01

    The unfolded protein response (UPR) is an intracellular signaling pathway that regulates the cellular response to the accumulation of misfolded proteins in eukaryotes. Our group has demonstrated that cell wall stress activates UPR in yeast through signals transmitted by the cell wall integrity (CWI) mitogen-activated protein (MAP) kinase cascade. The UPR is required to maintain cell wall integrity; mutants lacking a functional UPR have defects in cell wall biosynthesis and are hypersensitive ...

  14. Homogenization of a system of elastic and reaction-diffusion equations modelling plant cell wall biomechanics

    OpenAIRE

    Ptashnyk, Mariya; Seguin, Brian

    2014-01-01

    In this paper we present a derivation and multiscale analysis of a mathematical model for plant cell wall biomechanics that takes into account both the microscopic structure of a cell wall coming from the cellulose microfibrils and the chemical reactions between the cell wall's constituents. Particular attention is paid to the role of pectin and the impact of calcium-pectin cross-linking chemistry on the mechanical properties of the cell wall. We prove the existence and uniqueness of the stro...

  15. X-ray photoelectron spectroscopy analysis of whole cells and isolated cell walls of gram-positive bacteria: comparison with biochemical analysis.

    OpenAIRE

    Dufrêne, Yves; van der Wal, A.; Norde, W; Rouxhet, Paul

    1997-01-01

    The surface chemical composition of whole cells and isolated cell walls of four coryneform bacteria and of a Bacillus brevis strain has been determined by X-ray photoelectron spectroscopy (XPS). The XPS data were converted into concentrations of model compounds: peptides, polysaccharides, and hydrocarbonlike compounds. The composition of the surface of B. brevis differed markedly from that of coryneforms: the peptide concentration was about twice higher in the former case, which is attributed...

  16. Uniformity of Glycyl Bridge Lengths in the Mature Cell Walls of Fem Mutants of Methicillin-Resistant Staphylococcus aureus

    OpenAIRE

    Sharif, Shasad; Kim, Sung Joon; Labischinski, Harald; Chen, Jiawei; Schaefer, Jacob

    2013-01-01

    Peptidoglycan (PG) composition in intact cells of methicillin-resistant Staphylococcus aureus (MRSA) and its isogenic Fem mutants has been characterized by measuring the glycine content of PG bridge structures by solid-state nuclear magnetic resonance (NMR). The glycine content estimated from integrated intensities (rather than peak heights) in the cell walls of whole cells was increased by approximately 30% for the FemA mutant and was reduced by 25% for the FemB mutant relative to expected v...

  17. Composite Behavior of Insulated Concrete Sandwich Wall Panels Subjected to Wind Pressure and Suction

    OpenAIRE

    Insub Choi; JunHee Kim; Ho-Ryong Kim

    2015-01-01

    A full-scale experimental test was conducted to analyze the composite behavior of insulated concrete sandwich wall panels (ICSWPs) subjected to wind pressure and suction. The experimental program was composed of three groups of ICSWP specimens, each with a different type of insulation and number of glass-fiber-reinforced polymer (GFRP) shear grids. The degree of composite action of each specimen was analyzed according to the load direction, type of the insulation, and number of GFRP shear gri...

  18. Genomic characterization of plant cell wall degrading enzymes and in silico analysis of xylanses and polygalacturonases of Fusarium virguliforme

    Science.gov (United States)

    Plant cell wall degrading enzymes (PCWDEs) are important effectors for plant pathogens to invade plants. In this study, the composition of PCWDEs in Fusarium virguliforme that were grown for 5-days and 20 days in liquid medium was determined by RNA-Seq. Differential expression analysis showed more P...

  19. A rapid method to screen for cell-wall mutants using discriminant analysis of Fourier transform infrared spectra

    International Nuclear Information System (INIS)

    We have developed a rapid method to screen large numbers of mutant plants for a broad range of cell wall phenotypes using Fourier transform infrared (FTIR) microspectroscopy of leaves. We established and validated a model that can discriminate between the leaves of wild-type and a previously defined set of cell-wall mutants of Arabidopsis. Exploratory principal component analysis indicated that mutants deficient in different cell-wall sugars can be distinguished from each other. Discrimination of cell-wall mutants from wild-type was independent of variability in starch content or additional unrelated mutations that might be present in a heavily mutagenised population. We then developed an analysis of FTIR spectra of leaves obtained from over 1000 mutagenised flax plants, and selected 59 plants whose spectral variation from wild-type was significantly out of the range of a wild-type population, determined by Mahalanobis distance. Cell wall sugars from the leaves of selected putative mutants were assayed by gas chromatography-mass spectrometry and 42 showed significant differences in neutral sugar composition. The FTIR spectra indicated that six of the remaining 17 plants have altered ester or protein content. We conclude that linear discriminant analysis of FTIR spectra is a robust method to identify a broad range of structural and architectural alterations in cell walls, appearing as a consequence of developmental regulation, environmental adaptation or genetic modification. (author)

  20. Plectasin, a Fungal Defensin, Targets the Bacterial Cell Wall Precursor Lipid II

    DEFF Research Database (Denmark)

    Schneider, Tanja; Kruse, Thomas; Wimmer, Reinhard;

    2010-01-01

    that plectasin, a fungal defensin, acts by directly binding the bacterial cell-wall precursor Lipid II. A wide range of genetic and biochemical approaches identify cell-wall biosynthesis as the pathway targeted by plectasin. In vitro assays for cell-wall synthesis identified Lipid II as the specific cellular...

  1. Staphylococcus aureus Cell Wall Stress Stimulon Gene-lacZ Fusion Strains: Potential for Use in Screening for Cell Wall-Active Antimicrobials▿

    OpenAIRE

    Steidl, Rebecca; Pearson, Stacy; Stephenson, Robert E.; Ledala, Nagender; Sitthisak, Sutthirat; Wilkinson, Brian J; Jayaswal, Radheshyam K.

    2008-01-01

    lacZ fusion strains were constructed using the promoters of five cell wall stress stimulon genes: pbp2, tcaA, vraSR, sgtB, and lytR. All fusion strains were induced only in the presence of cell wall-active antibiotics, suggesting the potential of these strains for use in high-throughput screening for new cell wall-active agents.

  2. The Unfolded Protein Response Is Induced by the Cell Wall Integrity Mitogen-activated Protein Kinase Signaling Cascade and Is Required for Cell Wall Integrity in Saccharomyces cerevisiae

    OpenAIRE

    Scrimale, Thomas; DiDone, Louis; de Mesy Bentley, Karen L.; Krysan, Damian J.

    2009-01-01

    The yeast cell wall is an extracellular structure that is dependent on secretory and membrane proteins for its construction. We investigated the role of protein quality control mechanisms in cell wall integrity and found that the unfolded protein response (UPR) and, to a lesser extent, endoplasmic reticulum (ER)-associated degradation (ERAD) pathways are required for proper cell wall construction. Null mutation of IRE1, double mutation of ERAD components (hrd1Δ and ubc7Δ) and ire1Δ, or expres...

  3. Stress analysis for wall structure in mobile hot cell design

    Energy Technology Data Exchange (ETDEWEB)

    Bahrin, Muhammad Hannan, E-mail: hannan@nuclearmalaysia.gov.my; Rahman, Anwar Abdul, E-mail: anwar@nuclearmalaysia.gov.my; Hamzah, Mohd Arif, E-mail: arif@nuclearmalaysia.gov.my; Mamat, Mohd Rizal; Azman, Azraf; Hasan, Hasni [Prototype and Plant Development Centre, Technical Services Division, Malaysian Nuclear Agency (Malaysia)

    2016-01-22

    Malaysian Nuclear Agency is developing a Mobile Hot Cell (MHC) in order to handle and manage Spent High Activity Radioactive Sources (SHARS) such as teletherapy heads and irradiators. At present, there are only two units of MHC in the world, in South Africa and China. Malaysian Mobile Hot cell is developed by Malaysian Nuclear Agency with the assistance of IAEA expert, based on the design of South Africa and China, but with improved features. Stress analysis has been performed on the design in order to fulfil the safety requirement in operation of MHC. This paper discusses the loading analysis effect from the sand to the MHC wall structure.

  4. Effect of Wall Charge on Striation in Plasma Display Cells

    Institute of Scientific and Technical Information of China (English)

    HE Feng; OUYANG Jiting; CAO Jing; FENG Shuo; MIAO Jinsong; WANG Jianqi

    2007-01-01

    Different configurations and driving voltages have been employed to investigate the effect of the wall charge on the striations in macroscopic plasma display panel (PDP) cells.The experimental results show that a discharge channel near the dielectric layer is indispensable to striation occurring in the anode area during a discharge,while the pre-accumulated charge on the dielectric layer and the surface state are not important.The origin of the striation is related only to the physical process in the cell.The dielectric layer acts as a charge collector during a PDP discharge.

  5. Crystallization and melting behavior of multi-walled carbon nanotube-reinforced nylon-6 composites

    NARCIS (Netherlands)

    Phang, In Yee; Ma, Jianhua; Shen, Lu; Liu, Tianxi; Zhang, Wei-De

    2006-01-01

    The crystallization and melting behavior of neat nylon-6 (PA6) and multi-walled carbon nanotubes (MWNTs)/PA6 composites prepared by simple melt-compounding was comparatively studied. Differential scanning calorimetry (DSC) results show two crystallization exotherms (TCC, 1 and TCC, 2) for PA6/MWNTs

  6. Properties of novel composite meshes in chest wall reconstruction: A comparative animal study

    Directory of Open Access Journals (Sweden)

    Patrick Zardo

    2014-01-01

    Conclusion: We consider composite grafts a suitable alternative for chest wall reconstruction. They are characterized by good overall biointegration and limited perigraft-fibrosis, thus potentially facilitating redo-procedures, even though a hydrophilic coating per se does not appear to prevent intrathoracic adhesion formation.

  7. Deformability of plastering compositions in design solutions of modern thermal protective exterior walls

    Directory of Open Access Journals (Sweden)

    R.R. Vakhitov

    2013-04-01

    Full Text Available In recent years, appearance of new constructive decisions for multilayer thermal efficient walls in the practice of design and construction caused the increasing use of protective and decorative plaster compositions. Comprehensive protective plaster systems nowadays are used in the facade insulation systems as a protective layer on the surface of polystyrene foam or mineral wool boards, forming the insulating layer to the outer walls of concrete blocks. They are also used for exterior finish of walls made of gas-concrete blocks, plastering the brickwork of the buildings operated by rehabilitation, in particular, apartment houses of old mass series. The problem of ensuring durability of thermal efficient external walls with the use of protective and decorative plaster systems were identified in this article. The factors, affecting the resistance of facade plasters to the action of external conditions in operating process were considered. The weaknesses in the necessary characteristics of plaster mixtures provided by material manufacturers are revealed. The existing methods for determining crack resistance of plaster compositions are monitored. The author's method of determining the maximum stretch of plaster compositions is given. The article presents tests results of various plaster compositions, confirming the effectiveness of the proposed method.

  8. Quantitative CT: Associations between Emphysema, Airway Wall Thickness and Body Composition in COPD

    DEFF Research Database (Denmark)

    Rutten, Erica P A; Grydeland, Thomas B; Pillai, Sreekumar G;

    2011-01-01

    The objective of the present study was to determine the association between CT phenotypes-emphysema by low attenuation area and bronchitis by airway wall thickness-and body composition parameters in a large cohort of subjects with and without COPD. In 452 COPD subjects and 459 subjects without COPD...

  9. In situ analysis of cell wall polymers associated with phloem fibre cells in stems of hemp, Cannabis sativa L.

    Science.gov (United States)

    Blake, Anthony W; Marcus, Susan E; Copeland, James E; Blackburn, Richard S; Knox, J Paul

    2008-06-01

    A study of stem anatomy and the sclerenchyma fibre cells associated with the phloem tissues of hemp (Cannabis sativa L.) plants is of interest for both understanding the formation of secondary cell walls and for the enhancement of fibre utility as industrial fibres and textiles. Using a range of molecular probes for cell wall polysaccharides we have surveyed the presence of cell wall components in stems of hemp in conjunction with an anatomical survey of stem and phloem fibre development. The only polysaccharide detected to occur abundantly throughout the secondary cell walls of phloem fibres was cellulose. Pectic homogalacturonan epitopes were detected in the primary cell walls/intercellular matrices between the phloem fibres although these epitopes were present at a lower level than in the surrounding parenchyma cell walls. Arabinogalactan-protein glycan epitopes displayed a diversity of occurrence in relation to fibre development and the JIM14 epitope was specific to fibre cells, binding to the inner surface of secondary cell walls, throughout development. Xylan epitopes were found to be present in the fibre cells (and xylem secondary cell walls) and absent from adjacent parenchyma cell walls. Analysis of xylan occurrence in the phloem fibre cells of hemp and flax indicated that xylan epitopes were restricted to the primary cell walls of fibre cells and were not present in the secondary cell walls of these cells.

  10. A Model for Cell Wall Dissolution in Mating Yeast Cells: Polarized Secretion and Restricted Diffusion of Cell Wall Remodeling Enzymes Induces Local Dissolution

    OpenAIRE

    Huberman, Lori B.; Murray, Andrew W.

    2014-01-01

    Mating of the budding yeast, Saccharomyces cerevisiae, occurs when two haploid cells of opposite mating types signal using reciprocal pheromones and receptors, grow towards each other, and fuse to form a single diploid cell. To fuse, both cells dissolve their cell walls at the point of contact. This event must be carefully controlled because the osmotic pressure differential between the cytoplasm and extracellular environment causes cells with unprotected plasma membranes to lyse. If the cell...

  11. Ultra fast UV-photo detector based on single-walled carbon nanotube/PEDOT-PSS composites.

    Science.gov (United States)

    Najeeb, Choolakadavil Khalid; Lee, Jae-Hyoek; Chang, Jingbo; Kang, Won-Seok; Kim, Jae-Ho

    2009-12-01

    Single-walled carbon nanotube (SWNT)/Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS), composites (SWNT/PEDOT-PSS) have been prepared using SWNTs surface modified with a natural gum, 'gum arabic' by simple mixing process. Thin films of SWNTs, PEDOT-PSS and the composites were prepared by vacuum filtration technique and were exposed to ultraviolet (UV) radiations for photoconductivity measurements. The surface resistivity of pristine SWNTs film increased from initial value of 50 omega to 92 omega and that of the polymer film decreased from 6.7 Komega to 3.1 Komega while the resistivity of the composite film decreased from 267 omega to 232 omega upon UV illumination. When the lamp was switched off, the initial resistivities of PEDOT: PSS and SWNTs films were recovered very slowly. Interestingly, on the other hand the composite films demonstrated a very fast relaxation within a few minutes. An on-off cycle ruled out the possibility of local heating effect and revealed that the switching property was originated from the fast transport of charge and heat in the composite films. This property of composite film might open up optoelectronic applications involving photoconductivity, such as photo sensors, organic light emitting diodes (OLED) and organic solar cells. Here in, we demonstrate the application of the SWNT/PEDOT-PSS composite film based device as a UV sensor.

  12. Expansins are among plant cell wall modifying agents specifically expressed during development of nematode-induced syncytia

    OpenAIRE

    Fudali, Sylwia; Sobczak, Miroslaw; Janakowski, Slawomir; Griesser, Michaela; Grundler, Florian MW; Golinowski, Wladyslaw

    2008-01-01

    Cyst nematodes are economically important pests. As obligatory biotrophic endoparasites they invade host roots and induce formation of syncytia, structures that serve them as the only source of nutrients. During syncytium development, extensive cell wall modifications take place. Cell wall dissolution occurs during cell wall opening formation, cell walls expand during hypertrophy of syncytial elements and local cell wall synthesis leads to the thickening of syncytial cell wall and the formati...

  13. Multi-wall carbon nanotubes reinforced aluminum composites synthesized by hot press sintering and squeeze casting

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue-xi; YANG Li; DENG Chun-feng; WANG De-zun

    2006-01-01

    Multi-wall carbon nanotubes (MWNTs) have high mechanical properties and are considered a kind of realistic reinforcement for polymers, ceramics and metals. The hot press sintering and squeeze casting were adopted to synthesize MWNTs reinforced aluminum composites. In hot press sintered MWNTs/Al composites, MWNTs agglomerates distribute along aluminum powders and have low bonding strength with aluminum. But MWNTs agglomerates distribute evenlyin the squeeze cast MWNTs/Al composites. Some dispersed nanotubes bond well with aluminum matrix and few dislocations can be found in the nanotube areas,which implies little thermal residual stress in squeeze cast MWNTs/Al composites. This indicates that the strengthen mechanisms in nanometer sized MWNTs/Al composites may be different from that in micrometer sized whisker composites.

  14. Pressure Dependent Wall Relaxation in Polarized $^3$He Gaseous Cells

    CERN Document Server

    Peng, C; Chu, P -H; Gao, H; Zhang, Y

    2013-01-01

    Pressure dependence of longitudinal relaxation time (T$_1$) due to the cell wall was observed previously at both room temperature and low temperature in valved Rb-coated refillable $^3$He gaseous cells in \\cite{Zheng2}. The diffusion of $^3$He from measurement cell through a capillary tube to the valve and the subsequent depolarization on the surface of the valve was proposed to possibly explain such a pressure dependence at room temperature \\cite{Saam}. In this paper, we investigate this diffusion effect through measurements of T$_1$ with newly designed Rb-coated Pyrex glass cells at 295 K as well as finite element analysis (FEA) studies. Both the experimental results and FEA studies show that the diffusion effect is insufficient to explain the observed linear pressure-dependent behavior of T$_1$.

  15. Clear Cell Adenocarcinoma Arising from Abdominal Wall Endometriosis

    Directory of Open Access Journals (Sweden)

    Thouraya Achach

    2008-01-01

    Full Text Available Endometriosis is a frequent benign disorder. Malignancy arising in extraovarian endometriosis is a rare event. A 49-year-old woman is presented with a large painful abdominal wall mass. She underwent a myomectomy, 20 years before, for uterus leiomyoma. Computed tomography suggested that this was a desmoid tumor and she underwent surgery. Histological examination showed a clear cell adenocarcinoma associated with endometriosis foci. Pelvic ultrasound, computed tomography, and endometrial curettage did not show any malignancy or endometriosis in the uterus and ovaries. Adjuvant chemotherapy was recommended, but the patient was lost to follow up. Six months later, she returned with a recurrence of the abdominal wall mass. She was given chemotherapy and then she was reoperated.

  16. Cell wall pH and auxin transport velocity

    Science.gov (United States)

    Hasenstein, K. H.; Rayle, D.

    1984-01-01

    According to the chemiosmotic polar diffusion hypothesis, auxin pulse velocity and basal secretion should increase with decreasing cell wall pH. Experiments were designed to test this prediction. Avena coleoptile sections were preincubated in either fusicoccin (FC), cycloheximide, pH 4.0, or pH 8.0 buffer and subsequently their polar transport capacities were determined. Relative to controls, FC enhanced auxin (IAA) uptake while CHI and pH 8.0 buffer reduced IAA uptake. Nevertheless, FC reduced IAA pulse velocity while cycloheximide increased velocity. Additional experiments showed that delivery of auxin to receivers is enhanced by increased receiver pH. This phenomenon was overcome by a pretreatment of the tissue with IAA. Our data suggest that while acidic wall pH values facilitate cellular IAA uptake, they do not enhance pulse velocity or basal secretion. These findings are inconsistent with the chemiosmotic hypothesis for auxin transport.

  17. An in vitro model of the glomerular capillary wall using electrospun collagen nanofibres in a bioartificial composite basement membrane.

    Directory of Open Access Journals (Sweden)

    Sadie C Slater

    Full Text Available The filtering unit of the kidney, the glomerulus, contains capillaries whose walls function as a biological sieve, the glomerular filtration barrier. This comprises layers of two specialised cells, glomerular endothelial cells (GEnC and podocytes, separated by a basement membrane. Glomerular filtration barrier function, and dysfunction in disease, remains incompletely understood, partly due to difficulties in studying the relevant cell types in vitro. We have addressed this by generation of unique conditionally immortalised human GEnC and podocytes. However, because the glomerular filtration barrier functions as a whole, it is necessary to develop three dimensional co-culture models to maximise the benefit of the availability of these cells. Here we have developed the first two tri-layer models of the glomerular capillary wall. The first is based on tissue culture inserts and provides evidence of cell-cell interaction via soluble mediators. In the second model the synthetic support of the tissue culture insert is replaced with a novel composite bioartificial membrane. This consists of a nanofibre membrane containing collagen I, electrospun directly onto a micro-photoelectroformed fine nickel supporting mesh. GEnC and podocytes grew in monolayers on either side of the insert support or the novel membrane to form a tri-layer model recapitulating the human glomerular capillary in vitro. These models will advance the study of both the physiology of normal glomerular filtration and of its disruption in glomerular disease.

  18. Multi-walled Carbon Nano tubes/ Polyetherimide Composite Hollow Fibers for Gas Separation

    International Nuclear Information System (INIS)

    Composite hollow fibers were prepared by incorporating 1 wt % of multi walled carbon nano tubes (MWCNTs) within polyether imide (PEI) polymer matrix. Surfactant modification using non-ionic surfactant, Triton X100 was conducted to improve the dispersion of nano tubes in the polymer matrix during the preparation of polymer dope. The morphological structure and mechanical properties of the resulting composite hollow fibers were characterized. This study demonstrated the role of Triton X100 in facilitating the synergetic effects of MWCNTs and PEI where the resulting composite membrane is anticipated to have potential application in membrane based gas separation. (author)

  19. [Surface modification and microstructure of single-walled carbon nanotubes for dental composite resin].

    Science.gov (United States)

    Xia, Yang; Zhang, Feimin; Xu, Li'na; Gu, Ning

    2006-12-01

    In order to improve its dispersion condition in dental composite resin and enhance its interaction with the matrix, single-walled carbon nanotubes(SWNTs) were refluxed and oxidized, then treated by APTE. Their outer surface were coated by nano-SiO2 particles using sol-gel process, then further treated by organosilanes ATES. IR and TEM were used to analyze modification results. TEM pictures showed nano-particles were on the surface of SWNTs; IR showed characteristic adsorbing bands of SiO2. Composite resin specimen with modified SWNTs was prepared and examined by TEM. SWNTs were detected in composite resin matrix among other inorganic fillers.

  20. Scattering properties of microalgae: the effect of cell size and cell wall

    Science.gov (United States)

    Svensen, Øyvind; Frette, Øyvind; Rune Erga, Svein

    2007-08-01

    The main objective of this work was to investigate how the cell size and the presence of a cell wall influence the scattering properties of the green microalgae Chlamydomonas reinhardtii. The growth cycle of two strains, one with a cell wall and one without, was synchronized to be in the same growth phase. Measurements were conducted at two different phases of the growth cycle on both strains of the algae. It was found that the shape of the scattering phase function was very similar for both strains at both growth phases, but the regular strain with a cell wall scatters more strongly than the wall-less mutant. It was also found that the mutant strain has a stronger increase in scattering than the regular strain, as the algae grow, and that the scattering from the regular strain is more wavelength dependent than from the mutant strain.

  1. [Hydroxyproline: Rich glycoproteins of the plant and cell wall

    Energy Technology Data Exchange (ETDEWEB)

    Varner, J.E.

    1993-01-01

    Since xylem tissue includes the main cell types which are lignified, we are interested in gene expression of glycine-rich proteins and proline-rich proteins, and other proteins which are involved in secondary cell wall thickening during xylogenesis. Since the main feature of xylogenesis is the deposition of additional wall components, study of the mechanism of xylogenesis will greatly advance our knowledge of the synthesis and assembly of wall macromolecules. We are using the in vitro xylogenesis system from isolated Zinnia mesophyll cells to isolate genes which are specifically expressed during xylogenesis. We have used subtractive hybridization methods to isolate a number of cDNA clones for differentially regulated genes from the cells after hormonal induction. So far, we have partially characterized 18 different cDNA clones from 239 positive clones. These differentially regulated genes can be divided into three sets according to the characteristics of gene expression in the induction medium and the control medium. The first set is induced in both the induction medium and the control medium without hormones. The second set is induced mainly in the induction medium and in the control medium with the addition of NAA alone. Two of thesegenes are exclusively induced by auxin. The third set of genes is induced mainly in the induction medium. Since these genes are not induced by either auxin or cytokinin alone, they may be directly involved in the process of xylogenesis. Our experiments on the localization of H[sub 2]O[sub 2] production reinforce the earlier ideas of others that H[sub 2]O[sub 2] is involved in normal lignification.

  2. Numerical Analysis of Composite Steel Concrete Structural Shear Walls with Steel Encased Profiles

    Directory of Open Access Journals (Sweden)

    Daniel Dan

    2009-01-01

    Full Text Available The use of common reinforced concrete shear walls in high rise buildings is sometimes limited because of the large amount of reinforcement localized at the end of the element. A good alternative in avoiding this disadvantage is to use composite steel concrete structural shear walls with steel encased profiles. This solution used for high rise buildings, offers to designers lateral stiffness, shear capacity and high bending resisting moment of structural walls. The encasement of the steel shapes in concrete is applied also for the following purposes: flexural stiffening and strengthening of compression elements; fire protection; potentially easier repairs after moderate damage; economy with respect both to material and construction. Until now in the national and international literature poor information about nonlinear behaviour of composite steel concrete structural shear walls with steel encased profiles is available. A theoretical and experimental program related to the behaviour of steel concrete structural shear walls with steel encased profiles is developed at “Politehnica” University of Timişoara. The program refers to six different elements, which differ by the shape of the steel encased profile and also by the arrangement of steel shapes on the cross section of the element. In order to calibrate the elements for experimental study some numerical analysis were made. The paper presents the results of numerical analysis with details of stress distribution, crack distribution, structural stiffness at various loads, and load bearing capacity of the elements.

  3. THE ANALYSIS OF THIN WALLED COMPOSITE LAMINATED HELICOPTER ROTOR WITH HIERARCHICAL WARPING FUNCTIONS AND FINITE ELEMENT METHOD

    Institute of Scientific and Technical Information of China (English)

    诸德超; 邓忠民; 王荇卫

    2001-01-01

    In the present paper, a series of hierarchical warping functions is developed to analyze the static and dynamic problems of thin walled composite laminated helicopter rotors composed of several layers with single closed cell. This ethod is the development and extension of the traditional constrained warping theory of thin walled metallic beams, which had been proved very successful since 1940s. The warping distribution along the perimeter of each layer is expanded into a series of successively corrective warping functions with the traditional warping function caused by free torsion or free bending as the first term, and is assumed to be piecewise linear along the thickness direction of layers. The governing equations are derived based upon the variational principle of minimum potential energy for static analysis and Rayleigh Quotient for free vibration analysis. Then the hierarchical finite element method is introduced to form a numerical algorithm. Both static and natural vibration problems of sample box beams are analyzed with the present method to show the main mechanical behavior of the thin walled composite laminated helicopter rotor.

  4. Characterization of cell wall polysaccharides of cherry (Prunus cerasus var. Schattenmorelle) fruit and pomace.

    Science.gov (United States)

    Kosmala, Monika; Milala, Joanna; Kołodziejczyk, Krzysztof; Markowski, Jarosław; Mieszczakowska, Monika; Ginies, Christian; Renard, Catherine M G C

    2009-12-01

    The polysaccharide composition of cell wall of sour cherry (Prunus cerasus var. Schattenmorelle) fruit and pomace was investigated. Furthermore, the alcohol insoluble solids composition of 'Kelleriis' and 'Dobreczyn Botermo' varieties were studied too. Yield of alcohol insoluble solids for fruits was lower than 10%, and for pomaces circa 50%. Uronic acid was the main pectin component of alcohol insoluble solids. Enzymes used as juice processing aids decreased the content of uronic acid. Araban and galactan side chains bonded tightly to cellulose presence was suggested by high content of arabinose and galactose in hemicellulose fraction. The process of drying at below 70 degrees C did not influence polysaccharide composition of sour cherry pomaces. Alcohol insoluble solids of fruits expressed higher hydration properties than of pomaces. PMID:19757068

  5. Induction kinetics of the Staphylococcus aureus cell wall stress stimulon in response to different cell wall active antibiotics

    Directory of Open Access Journals (Sweden)

    Berger-Bächi Brigitte

    2011-01-01

    Full Text Available Abstract Background Staphylococcus aureus activates a protective cell wall stress stimulon (CWSS in response to the inhibition of cell wall synthesis or cell envelope damage caused by several structurally and functionally different antibiotics. CWSS induction is coordinated by the VraSR two-component system, which senses an unknown signal triggered by diverse cell wall active agents. Results We have constructed a highly sensitive luciferase reporter gene system, using the promoter of sas016 (S. aureus N315, which detects very subtle differences in expression as well as measuring > 4 log-fold changes in CWSS activity, to compare the concentration dependence of CWSS induction kinetics of antibiotics with different cell envelope targets. We compared the effects of subinhibitory up to suprainhibitory concentrations of fosfomycin, D-cycloserine, tunicamycin, bacitracin, flavomycin, vancomycin, teicoplanin, oxacillin, lysostaphin and daptomycin. Induction kinetics were both strongly antibiotic- and concentration-dependent. Most antibiotics triggered an immediate response with induction beginning within 10 min, except for tunicamycin, D-cycloserine and fosfomycin which showed lags of up to one generation before induction commenced. Induction characteristics, such as the rate of CWSS induction once initiated and maximal induction reached, were strongly antibiotic dependent. We observed a clear correlation between the inhibitory effects of specific antibiotic concentrations on growth and corresponding increases in CWSS induction kinetics. Inactivation of VraR increased susceptibility to the antibiotics tested from 2- to 16-fold, with the exceptions of oxacillin and D-cycloserine, where no differences were detected in the methicillin susceptible S. aureus strain background analysed. There was no apparent correlation between the induction capacity of the various antibiotics and the relative importance of the CWSS for the corresponding resistance phenotypes

  6. Direct measurement of cell wall stress-stiffening and turgor pressure in live bacterial cells

    CERN Document Server

    Deng, Yi; Shaevitz, Joshua W

    2011-01-01

    The mechanical properties of gram-negative bacteria are governed by a rigid peptidoglycan (PG) cell wall and the turgor pressure generated by the large concentration of solutes in the cytoplasm. The elasticity of the PG has been measured in bulk and in isolated sacculi and shown to be compliant compared to the overall stiffness of the cell itself. However, the stiffness of the cell wall in live cells has not been measured. In particular, the effects that pressure-induced stress might have on the stiffness of the mesh-like PG network have not been addressed even though polymeric materials often exhibit large amounts of stress-stiffening. We study bulging Escherichia coli cells using atomic force microscopy to separate the contributions of the cell wall and turgor pressure to the overall cell stiffness. We find strong evidence of power-law stress-stiffening in the E. coli cell wall, with an exponent of $1.07 \\pm 0.25$, such that the wall is significantly stiffer in live cells ($E\\sim32\\pm10$ MPa) than in unpres...

  7. Lubrication effectiveness of composite lubricants during P/M electrostatic die wall lubrication and warm compaction

    Institute of Scientific and Technical Information of China (English)

    Xia Yang; Shiju Guo; Farid Akhtar

    2006-01-01

    The lubrication effectiveness of the composite lubricants, 50wt% ethylene bis-stearamide (EBS) wax + 50wt% graphite and 50wt% EBS wax + 50wt% BN, during the powder metallurgy (P/M) electrostatic die wall lubrication and warm compaction was studied. The results show that the combination of 50wt% EBS wax and 50wt% graphite has excellent lubrication performance, resulting in fairly high green densities, but the mixture of 50wt% EBS wax and 50wt% BN has less beneficial effect. In addition, corresponding die temperatures should be applied when different die wall lubricants are used to achieve the highest green densities.

  8. Chromatin and Cell Wall Staining of Schizosaccharomyces pombe.

    Science.gov (United States)

    Hagan, Iain M

    2016-01-01

    Fission yeasts grow by tip extension, maintaining a constant width until they reach a critical size threshold and divide. Division by medial fission-which gives these yeast their name-generates a new end that arises from the site of cytokinesis. The old end, which was produced during the previous cell cycle, initiates progression of the new cell cycle, and in G2, the new end is activated in a process termed new-end takeoff (NETO). In this protocol, the fluorescent stains calcofluor and 4',6-diamidino-2-phenylindole (DAPI) are used to give a rapid and informative assessment of morphogenesis and cell-cycle progression in the fission yeast Schizosaccharomyces pombe Calcofluor reveals the timing of NETO because it stains the birth scars that are generated at new ends by cytokinesis less efficiently than the rest of the cell wall. Intense calcofluor staining of the septum and measurement of cell length are also widely used to identify dividing cells and to gauge the timing of mitotic commitment. Staining nuclei with DAPI identifies mono- and binucleated cells and complements the calcofluor staining procedure to evaluate the stages of the cell cycle and identify mitotic errors. Equally simple DAPI staining procedures reveal chromatin structure in higher resolution, facilitating more accurate staging of mitotic progression and characterization of mitotic errors. PMID:27250942

  9. Members of the Hsp70 family of proteins in the cell wall of Saccharomyces cerevisiae.

    OpenAIRE

    López-Ribot, J L; Chaffin, W L

    1996-01-01

    Western blot (immunoblot) analysis of cell wall and cytosolic extracts obtained from parental and ssa1 and ssa2 single- and double-mutant strains of Saccharomyces cerevisiae showed that the heat shock protein 70 (Hsp70) products of these genes, previously thought to be restricted to the cell interior, are also present in the cell wall. A cell wall location was further confirmed by indirect immunofluorescence with intact cells and biotinylation of extracellular Hsp70. Hsp70s have been implicat...

  10. Nutrient depletion modifies cell wall adsorption activity of wine yeast.

    Science.gov (United States)

    Sidari, R; Caridi, A

    2016-06-01

    Yeast cell wall is a structure that helps yeasts to manage and respond to many environmental stresses. The mannosylphosphorylation is a modification in response to stress that provides the cell wall with negative charges able to bind compounds present in the environment. Phenotypes related to the cell wall modification such as the filamentous growth in Saccharomyces cerevisiae are affected by nutrient depletion. The present work aimed at describing the effect of carbon and/or nitrogen limitation on the aptitude of S. cerevisiae strains to bind coloured polyphenols. Carbon- and nitrogen-rich or deficient media supplemented with grape polyphenols were used to simulate different grape juice conditions-early, mid, 'adjusted' for nitrogen, and late fermentations. In early fermentation condition, the R+G+B values range from 106 (high adsorption, strain Sc1128) to 192 (low adsorption, strain Σ1278b), in mid-fermentation the values range from 111 (high adsorption, strain Sc1321) to 258 (low adsorption, strain Sc2306), in 'adjusted' for nitrogen conditions the values range from 105 (high adsorption, strain Sc1321) to 194 (low adsorption, strain Sc2306) while in late fermentation conditions the values range from 101 (high adsorption, strain Sc384) to 293 (low adsorption, strain Sc2306). The effect of nutrient availability is not univocal for all the strains and the different media tested modified the strains behaviour. In all the media the strains show significant differences. Results demonstrate that wine yeasts decrease/increase their parietal adsorption activity according to the nutrient availability. The wide range of strain variability observed could be useful in selecting wine starters. PMID:27116955

  11. Cu/single-walled carbon nanotube laminate composites fabricated by cold rolling and annealing

    International Nuclear Information System (INIS)

    The remarkable mechanical, electrical and thermal properties of single-walled carbon nanotubes (SWCNTs) have attracted extensive research interest as structural and functional materials. In particular, SWCNTs have been used to reinforce polymers and ceramic composites and great progress has been made. For metal matrix composites, the limitation of the conventional manufacturing process and the difficulty in dispersing nanotubes within metal matrices hinder the development of metal matrix composites. In this paper, we demonstrate a successful fabrication of Cu/SWCNT laminate composites by combined techniques of cold rolling and annealing, using 19 layers of large-area SWCNT films sandwiched between 20 layers of Cu thin foils. The tensile strength and Young's modulus of the resultant laminate composites are 361 MPa and 132 GPa, respectively, exhibiting an improvement over the comparative pure Cu foils processed under identical conditions. These results suggest that good interfacial adhesions between nanotubes and the Cu matrix have been achieved after the rolling-annealing-rolling processes

  12. Cu/single-walled carbon nanotube laminate composites fabricated by cold rolling and annealing

    Science.gov (United States)

    Li, Yan-Hui; Housten, William; Zhao, Yimin; Qiu Zhu, Yan

    2007-05-01

    The remarkable mechanical, electrical and thermal properties of single-walled carbon nanotubes (SWCNTs) have attracted extensive research interest as structural and functional materials. In particular, SWCNTs have been used to reinforce polymers and ceramic composites and great progress has been made. For metal matrix composites, the limitation of the conventional manufacturing process and the difficulty in dispersing nanotubes within metal matrices hinder the development of metal matrix composites. In this paper, we demonstrate a successful fabrication of Cu/SWCNT laminate composites by combined techniques of cold rolling and annealing, using 19 layers of large-area SWCNT films sandwiched between 20 layers of Cu thin foils. The tensile strength and Young's modulus of the resultant laminate composites are 361 MPa and 132 GPa, respectively, exhibiting an improvement over the comparative pure Cu foils processed under identical conditions. These results suggest that good interfacial adhesions between nanotubes and the Cu matrix have been achieved after the rolling-annealing-rolling processes.

  13. A radioimmunoassay for lignin in plant cell walls

    International Nuclear Information System (INIS)

    Lignin detection and determination in herbaceous tissue requires selective, specific assays which are not currently available. A radioimmunoassay (RIA) was developed to study lignin metabolism in these tissues. A β-aryl ether lignin model compound was synthesized, linked to keyhole limpet hemocyanin using a water-soluble carbodiimide, and injected into rabbits. The highest titer of the antiserum obtained was 34 ηg/mL of model derivatized BSA. An in vitro system was developed to characterize the RIA. The model compound was linked to amino activated polyacrylamide beads to mimic lignin in the cell walls. 125I Radiolabelled protein A was used to detect IgG antibody binding. The RIA was shown in the in vitro system to exhibit saturable binding. The amount of antibody bound decreased when the serum was diluted. Immunoelectrophoresis and competitive binding experiments confirmed that both aromatic rings of the lignin model compound had been antigenic. Chlorogenic acid, a phenolic known to be present in plant cells, did not compete for antibody binding. The RIA was used to measure lignin in milled plant samples and barley seedlings. Antiserum binding to wheat cell walls and stressed barley segments was higher than preimmune serum binding. Antibody binding to stressed barley tissue decreased following NaClO2 delignification. The RIA was found to be less sensitive than expected, so several avenues for improving the method are discussed

  14. Lignification in poplar tension wood lignified cell wall layers.

    Science.gov (United States)

    Yoshinaga, Arata; Kusumoto, Hiroshi; Laurans, Françoise; Pilate, Gilles; Takabe, Keiji

    2012-09-01

    The lignification process in poplar tension wood lignified cell wall layers, specifically the S(1) and S(2) layers and the compound middle lamella (CML), was analysed using ultraviolet (UV) and transmission electron microscopy (TEM). Variations in the thickness of the gelatinous layer (G-layer) were also measured to clarify whether the lignified cell wall layers had completed their lignification before the deposition of G-layers, or, on the contrary, if lignification of these layers was still active during G-layer formation. Observations using UV microscopy and TEM indicated that both UV absorbance and the degree of potassium permanganate staining increased in the CML and S(1) and S(2) layers during G-layer formation, suggesting that the lignification of these lignified layers is still in progress during G-layer formation. In the context of the cell-autonomous monolignol synthesis hypothesis, our observations suggest that monolignols must go through the developing G-layer during the lignification of CML and the S(1) and S(2) layers. The alternative hypothesis of external synthesis (in the rays) does not require that monolignols go through the G-layer before being deposited in the CML, or the S(1) and S(2) layers. Interestingly, the previous observation of lignin in the poplar G-layer was not confirmed with the microscopy techniques used in the present study. PMID:22933655

  15. Absence of correlation between rates of cell wall turnover and autolysis shown by Bacillus subtilis mutants.

    OpenAIRE

    Vitković, L; Cheung, H. Y.; Freese, E

    1984-01-01

    Bacillus subtilis mutants with reduced rates of cell wall autolysis reached a constant rate of wall turnover after a longer lag than the standard strain but eventually showed the same turnover rate. In reverse, a turnover-deficient mutant autolysed at a slightly higher rate than the standard strain. Consequently, there is no correlation between the rates of cell wall turnover and autolysis.

  16. Induced mutations in tomato SlExp1 alter cell wall metabolism and delay fruit softening.

    Science.gov (United States)

    Minoia, Silvia; Boualem, Adnane; Marcel, Fabien; Troadec, Christelle; Quemener, Bernard; Cellini, Francesco; Petrozza, Angelo; Vigouroux, Jacqueline; Lahaye, Marc; Carriero, Filomena; Bendahmane, Abdelhafid

    2016-01-01

    Fruit ripening and softening are key traits for many fleshy fruit. Since cell walls play a key role in the softening process, expansins have been investigated to control fruit over ripening and deterioration. In tomato, expression of Expansin 1 gene, SlExp1, during fruit ripening was associated with fruit softening. To engineer tomato plants with long shelf life, we screened for mutant plants impaired in SlExp1 function. Characterization of two induced mutations, Slexp1-6_W211S, and Slexp1-7_Q213Stop, showed that SlExp1 loss of function leads to enhanced fruit firmness and delayed fruit ripening. Analysis of cell wall polysaccharide composition of Slexp1-7_Q213Stop mutant pointed out significant differences for uronic acid, neutral sugar and total sugar contents. Hemicelluloses chemistry analysis by endo-β-1,4-d-glucanase hydrolysis and MALDI-TOF spectrometry revealed that xyloglucan structures were affected in the fruit pericarp of Slexp1-7_Q213Stop mutant. Altogether, these results demonstrated that SlExp1 loss of function mutants yield firmer and late ripening fruits through modification of hemicellulose structure. These SlExp1 mutants represent good tools for breeding long shelf life tomato lines with contrasted fruit texture as well as for the understanding of the cell wall polysaccharide assembly dynamics in fleshy fruits.

  17. Destructuring plant biomass: Focus on fungal and extremophilic cell wall hydrolases

    Science.gov (United States)

    Guerriero, Gea; Hausman, Jean-Francois; Strauss, Joseph; Ertan, Haluk; Siddiqui, Khawar Sohail

    2016-01-01

    The use of plant biomass as feedstock for biomaterial and biofuel production is relevant in the current bio-based economy scenario of valorizing renewable resources. Fungi, which degrade complex and recalcitrant plant polymers, secrete different enzymes that hydrolyze plant cell wall polysaccharides. The present review discusses the current research trends on fungal, as well as extremophilic cell wall hydrolases that can withstand extreme physico-chemical conditions required in efficient industrial processes. Secretomes of fungi from the phyla Ascomycota, Basidiomycota, Zygomycota and Neocalli-mastigomycota are presented along with metabolic cues (nutrient sensing, coordination of carbon and nitrogen metabolism) affecting their composition. We conclude the review by suggesting further research avenues focused on the one hand on a comprehensive analysis of the physiology and epigenetics underlying cell wall degrading enzyme production in fungi and on the other hand on the analysis of proteins with unknown function and metagenomics of extremophilic consortia. The current advances in consolidated bioprocessing, altered secretory pathways and creation of designer plants are also examined. Furthermore, recent developments in enhancing the activity, stability and reusability of enzymes based on synergistic, proximity and entropic effects, fusion enzymes, structure-guided recombination between homologous enzymes and magnetic enzymes are considered with a view to improving saccharification. PMID:25804821

  18. Chemical, colloidal and mechanical contributions to the state of water in wood cell walls

    Science.gov (United States)

    Bertinetti, L.; Fratzl, P.; Zemb, T.

    2016-08-01

    The properties of wood depend strongly on its water content, but the physicochemical basis for the interaction of water with cell wall components is poorly understood. Due to the importance of the problem both in the context of wood technology and the biological function of swelling and dehydration for growth stresses and seed dispersal, a wealth of descriptive data has been accumulated but a microscopic theory of water-biomolecular interactions is missing. We develop here, at a primitive level, a minimal parameter-free, coarse-grained, model of wood secondary cell walls to predict water absorption, in the form of an equation of state. It includes for the first time all three—mechanical, colloidal and chemical—contributions, taking into account the cell walls microstructure. The hydration force around the elongated cellulose crystals and entropy of mixing of the matrix polymers (hemicelluloses and lignin) are the dominant contributions driving the swelling. The elastic energy needed to swell the composite is the main term opposing water uptake. Hysteresis is not predicted but water uptake versus humidity, is reproduced in a large temperature range. Within this framework, the origin of wood dissolution and different effects of wood treatments on water sorption can be understood at the molecular level.

  19. The Mechanisms of Plant Cell Wall Deconstruction during Enzymatic Hydrolysis

    DEFF Research Database (Denmark)

    Thygesen, Lisbeth Garbrecht; E. Thybring, Emil; Johansen, Katja Salomon;

    2014-01-01

    Mechanical agitation during enzymatic hydrolysis of insoluble plant biomass at high dry matter contents is indispensable for the initial liquefaction step in biorefining. It is known that particle size reduction is an important part of liquefaction, but the mechanisms involved are poorly understood....... Here we put forward a simple model based on mechanical principles capable of capturing the result of the interaction between mechanical forces and cell wall weakening via hydrolysis of glucosidic bonds. This study illustrates that basic material science insights are relevant also within biochemistry...

  20. Chitosan Obtained from Cell Wall of Aspergillus Niger Mycelium

    Institute of Scientific and Technical Information of China (English)

    HUANG Hui-li; LIN Wen-luan; LIN Jian-ming

    2004-01-01

    Chitin from cell walls of Aspergillus Niger mycelium was prepared. A new method for the preparation of high deacetylation degree chitosan was studied in a dilute sodium hydroxide solution at a high pressure. The experimental results indicate that the deacetylation degree of the chitosan can reach 80% under the condition of a 5.00 mol/L sodium hydroxide solution at 0.1 MPa of pressure for 1 h. This method shows the advantages of the applications in the industry production and environment protection.

  1. wall

    Directory of Open Access Journals (Sweden)

    Irshad Kashif

    2016-01-01

    Full Text Available Maintaining indoor climatic conditions of buildings compatible with the occupant comfort by consuming minimum energy, especially in a tropical climate becomes a challenging problem for researchers. This paper aims to investigate this problem by evaluating the effect of different kind of Photovoltaic Trombe wall system (PV-TW on thermal comfort, energy consumption and CO2 emission. A detailed simulation model of a single room building integrated with PV-TW was modelled using TRNSYS software. Results show that 14-35% PMV index and 26-38% PPD index reduces as system shifted from SPV-TW to DGPV-TW as compared to normal buildings. Thermal comfort indexes (PMV and PPD lie in the recommended range of ASHARE for both DPV-TW and DGPV-TW except for the few months when RH%, solar radiation intensity and ambient temperature were high. Moreover PVTW system significantly reduces energy consumption and CO2 emission of the building and also 2-4.8 °C of temperature differences between indoor and outdoor climate of building was examined.

  2. Single-walled carbon nanotube incorporated novel three phase carbon/epoxy composite with enhanced properties.

    Science.gov (United States)

    Rana, Sohel; Alagirusamy, Ramasamy; Joshi, Mangala

    2011-08-01

    In the present work, single-walled carbon nanotubes were dispersed within the matrix of carbon fabric reinforced epoxy composites in order to develop novel three phase carbon/epoxy/single-walled carbon nanotube composites. A combination of ultrasonication and high speed mechanical stirring at 2000 rpm was used to uniformly disperse carbon nanotubes in the epoxy resin. The state of carbon nanotube dispersion in the epoxy resin and within the nanocomposites was characterized with the help of optical microscopy and atomic force microscopy. Pure carbon/epoxy and three phase composites were characterized for mechanical properties (tensile and compressive) as well as for thermal and electrical conductivity. Fracture surfaces of composites after tensile test were also studied in order to investigate the effect of dispersed carbon nanotubes on the failure behavior of composites. Dispersion of only 0.1 wt% nanotubes in the matrix led to improvements of 95% in Young's modulus, 31% in tensile strength, 76% in compressive modulus and 41% in compressive strength of carbon/epoxy composites. In addition to that, electrical and thermal conductivity also improved significantly with addition of carbon nanotubes. PMID:22103118

  3. Development and Analysis of Synthetic Composite Materials Emulating Patient AAA Wall Material Properties

    Science.gov (United States)

    Margossian, Christa M.

    Abdominal Aortic Aneurysm (AAA) rupture accounts for 14,000 deaths a year in the United States. Since the number of ruptures has not decreased significantly in recent years despite improvements in imaging and surgical procedures, there is a need for an accurate, noninvasive technique capable of establishing rupture risk for specific patients and discriminating lesions at high risk. In this project, synthetic composite materials replicating patient-specific wall stiffness and strength were developed and their material properties evaluated. Composites utilizing various fibers were developed to give a range of stiffness from 1825.75 kPa up through 8187.64 kPa with one base material, Sylgard 170. A range of strength from 631.12 kPa to 1083 kPa with the same base material was also found. By evaluating various base materials and various reinforcing fibers, a catalogue of stiffnesses and strengths was started to allow for adaptation to specific patient properties. Three specific patient properties were well-matched with two composites fabricated: silk thread-reinforced Sylgard 170 and silk thread-reinforced Dragon Skin 20. The composites showed similar stiffnesses to the specific patients while reaching target stresses at particular strains. Not all patients were matched with composites as of yet, but recommendations for future matches are able to be determined. These composites will allow for the future evaluation of flow-induced wall stresses in models replicating patient material properties and geometries.

  4. Xyloglucan Metabolism Differentially Impacts the Cell Wall Characteristics of the Endosperm and Embryo during Arabidopsis Seed Germination.

    Science.gov (United States)

    Sechet, Julien; Frey, Anne; Effroy-Cuzzi, Delphine; Berger, Adeline; Perreau, François; Cueff, Gwendal; Charif, Delphine; Rajjou, Loïc; Mouille, Grégory; North, Helen M; Marion-Poll, Annie

    2016-03-01

    Cell wall remodeling is an essential mechanism for the regulation of plant growth and architecture, and xyloglucans (XyGs), the major hemicellulose, are often considered as spacers of cellulose microfibrils during growth. In the seed, the activity of cell wall enzymes plays a critical role in germination by enabling embryo cell expansion leading to radicle protrusion, as well as endosperm weakening prior to its rupture. A screen for Arabidopsis (Arabidopsis thaliana) mutants affected in the hormonal control of germination identified a mutant, xyl1, able to germinate on paclobutrazol, an inhibitor of gibberellin biosynthesis. This mutant also exhibited reduced dormancy and increased resistance to high temperature. The XYL1 locus encodes an α-xylosidase required for XyG maturation through the trimming of Xyl. The xyl1 mutant phenotypes were associated with modifications to endosperm cell wall composition that likely impact on its resistance, as further demonstrated by the restoration of normal germination characteristics by endosperm-specific XYL1 expression. The absence of phenotypes in mutants defective for other glycosidases, which trim Gal or Fuc, suggests that XYL1 plays the major role in this process. Finally, the decreased XyG abundance in hypocotyl longitudinal cell walls of germinating embryos indicates a potential role in cell wall loosening and anisotropic growth together with pectin de-methylesterification. PMID:26826221

  5. Nanomaterial cytotoxicity is composition, size, and cell type dependent

    Directory of Open Access Journals (Sweden)

    Sohaebuddin Syed K

    2010-08-01

    Full Text Available Abstract Background Despite intensive research efforts, reports of cellular responses to nanomaterials are often inconsistent and even contradictory. Additionally, relationships between the responding cell type and nanomaterial properties are not well understood. Using three model cell lines representing different physiological compartments and nanomaterials of different compositions and sizes, we have systematically investigated the influence of nanomaterial properties on the degrees and pathways of cytotoxicity. In this study, we selected nanomaterials of different compositions (TiO2 and SiO2 nanoparticles, and multi-wall carbon nanotubes [MWCNTs] with differing size (MWCNTs of different diameters 50 nm; but same length 0.5-2 μm to analyze the effects of composition and size on toxicity to 3T3 fibroblasts, RAW 264.7 macrophages, and telomerase-immortalized (hT bronchiolar epithelial cells. Results Following characterization of nanomaterial properties in PBS and serum containing solutions, cells were exposed to nanomaterials of differing compositions and sizes, with cytotoxicity monitored through reduction in mitochondrial activity. In addition to cytotoxicity, the cellular response to nanomaterials was characterized by quantifying generation of reactive oxygen species, lysosomal membrane destabilization and mitochondrial permeability. The effect of these responses on cellular fate - apoptosis or necrosis - was then analyzed. Nanomaterial toxicity was variable based on exposed cell type and dependent on nanomaterial composition and size. In addition, nanomaterial exposure led to cell type dependent intracellular responses resulting in unique breakdown of cellular functions for each nanomaterial: cell combination. Conclusions Nanomaterials induce cell specific responses resulting in variable toxicity and subsequent cell fate based on the type of exposed cell. Our results indicate that the composition and size of nanomaterials as well as the

  6. Determination of the pore size of cell walls of living plant cells

    Energy Technology Data Exchange (ETDEWEB)

    Carpita, N.; Sabularse, D.; Montezinos, D.; Delmer, D.P.

    1979-09-14

    The limiting diameter of pores in the walls of living plant cells through which molecules can freely pass has been determined by a solute exclusion technique to be 35 to 38 angstroms for hair cells of Raphanus sativus roots and fibers of Gossypium hirsutum, 38 to 40 angstroms for cultured cells of Acer pseudoplatanus, and 45 to 52 angstroms for isolated palisade parenchyma cells of the leaves of Xanthium strumarium and Commelina communis. These results indicate that molecules with diameters larger than these pores would be restricted in their ability to penetrate such a cell wall, and that such a wall may represent a more significant barrier to cellular communication than has been previously assumed.

  7. Changes in plant cell-wall structure of corn stover due to hot compressed water pretreatment and enhanced enzymatic hydrolysis.

    Science.gov (United States)

    Zhou, Wei; Yang, Maohua; Wang, Caixia; Liu, Jianfei; Xing, Jianmin

    2014-08-01

    Corn stover is a potential feedstock for biofuel production. This work investigated physical and chemical changes in plant cell-wall structure of corn stover due to hot compressed water (HCW) pretreatment at 170-190 °C in a tube reactor. Chemical composition analysis showed the soluble hemicellulose content increased with pretreatment temperature, whereas the hemicellulose content decreased from 29 to 7 % in pretreated solids. Scanning electron microscopy revealed the parenchyma-type second cell-wall structure of the plant was almost completely removed at 185 °C, and the sclerenchyma-type second cell wall was greatly damaged upon addition of 5 mmol/L ammonium sulfate during HCW pretreatment. These changes favored accessibility for enzymatic action. Enzyme saccharification of solids by optimized pretreatment with HCW at 185 °C resulted in an enzymatic hydrolysis yield of 87 %, an enhancement of 77 % compared to the yield from untreated corn stover.

  8. Rhizobium sp. Degradation of Legume Root Hair Cell Wall at the Site of Infection Thread Origin

    OpenAIRE

    Ridge, Robert W.; Rolfe, Barry G.

    1985-01-01

    Using a new microinoculation technique, we demonstrated that penetration of Rhizobium sp. into the host root hair cell occurs at 20 to 22 h after inoculation. It did this by dissolving the cell wall maxtrix, leaving a layer of depolymerized wall microfibrils. Colony growth pressure “stretched” the weakened wall, forming a bulge into an interfacial zone between the wall and plasmalemma. At the same time vesicular bodies, similar to plasmalemmasomes, accumulated at the penetration site in a man...

  9. Implication of multi-walled carbon nanotubes on polymer/graphene composites

    International Nuclear Information System (INIS)

    Highlights: • Influence of adding carbon nanotubes (CNTs) into elastomer/graphene composites. • Multi-walled CNTs work supplementally to GnPs by forming conductive networks. • The findings illuminate marked synergistic effect between MWCNTs and graphene sheets. - Abstract: Graphene sheets stack in polymer matrices while multi-walled carbon nanotubes (MWCNTs) entangle themselves, forming two daunting challenges in the design and fabrication of polymer composites. Both challenges have been simultaneously addressed in this study by hybridizing the two nanomaterials through melt compounding to develop elastomer/graphene platelet/MWCNT (3-phase) composites, where MWCNTs were fixed at 2.8 vol% (5 wt%) for all fractions. We investigated the composites’ structure and properties, and compared the 3-phase composites with elastomer/graphene platelet (2-phase) composites. MWCNTs may bridge graphene platelets (GnPs) and promote their dispersion in the matrix, which would provide more interface area between the matrix and the fillers. MWCNTs worked supplementally to GnPs by forming conductive networks, where MWCNTs acted as long nanocables to transport electrons and stress while GnPs served as interconnection sites between the tubes forming local conductive paths. This produced a percolation threshold of electrical conductivity at 2.3 vol% for 3-phase composites, 88% lower than that of 2-phase composites. At 26.7 vol% of total filler content (MWCNTs + GnPs), tensile strength, Young’s modulus and tear strength showed respectively 303%, 115%, 155% further improvements over those of 2-phase composites. These improvements are originated from the synergistic effect between GnPs and MWCNTs. The conducting elastomeric composites developed would potentially open the door for applications in automotive and aerospace industries

  10. Chemical Profiling of the Plant Cell Wall through Raman Microspectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Han, Ju; Singh, Seema; Sun, Lan; Simmons, Blake; Auer, Manfred; Parvin, Bahram

    2010-03-02

    This paper presents a computational framework for chemical pro.ling of the plant cell wall through the Raman spectroscopy. The system enables query of known spectral signatures and clustering of spectral data based on intrinsic properties. As a result, presence and relative concentration of speci.c chemical bonds can be quanti.ed. The primary contribution of this paper is in representation of raman pro.le in terms of .uorescence background and multiscale peak detection at each grid point (voxel). Such a representation allows ef.cient spatial segmentation based on the coupling between high-level salient properties and low-level symbolic representation at each voxel. The high-level salient properties refer to preferred peaks and their attributes for the entire image. The low-level symbolic representations are based on .uorescence background, spectral peak locations, and their attributes. We present results on a corn stover tissue section that is imaged through Raman microscopy, and the results are consistent with the literature. In addition, automatic clustering indicates several distinct layers of the cell walls with different spectral signatures.

  11. Ag-silica composite nanotube with controlled wall structures for biomedical applications.

    Science.gov (United States)

    He, Haiyan; Wang, Juan; Gao, Qian; Chang, Mingwei; Ren, Zhaohui; Zhang, Xiwen; Li, Xiang; Weng, Wenjian; Han, Gaorong

    2013-11-01

    A range of Ag-silica composite nanotubes with tailored wall structures were successfully synthesized in situ by single-nozzle electrospinning. By increasing AgNO3 concentration, the wall structure of Ag-silica tubes changes from dense to porous, and eventually turns into a 'lace-like' structure. This is attributed to Ag ions doping into the SiOSi network of precursors, as illustrated in FTIR study. More importantly, Ag-silica composite nanotubes show robust antibacterial activity against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms. Therefore, it is a breakthrough of the nanostructure biomaterial research for future medical applications that require strong antibacterial properties. PMID:23907057

  12. Electromagnetic interference (EMI) shielding of single-walled carbon nanotube epoxy composites.

    Science.gov (United States)

    Li, Ning; Huang, Yi; Du, Feng; He, Xiaobo; Lin, Xiao; Gao, Hongjun; Ma, Yanfeng; Li, Feifei; Chen, Yongsheng; Eklund, Peter C

    2006-06-01

    Single-walled carbon nanotube (SWNT)-polymer composites have been fabricated to evaluate the electromagnetic interference (EMI) shielding effectiveness (SE) of SWNTs. Our results indicate that SWNTs can be used as effective lightweight EMI shielding materials. Composites with greater than 20 dB shielding efficiency were obtained easily. EMI SE was tested in the frequency range of 10 MHz to 1.5 GHz, and the highest EMI shielding efficiency (SE) was obtained for 15 wt % SWNT, reaching 49 dB at 10 MHz and exhibiting 15-20 dB in the 500 MHz to 1.5 GHz range. The EMI SE was found to correlate with the dc conductivity, and this frequency range is found to be dominated by reflection. The effects of SWNT wall defects and aspect ratio on the EMI SE were also studied. PMID:16771569

  13. Deformation and Failure of a Multi-Wall Carbon Nanotube Yarn Composite

    Science.gov (United States)

    Gates, Thomas S.; Jefferson, Gail D.; Frankland, Sarah-Jane V.

    2008-01-01

    Forests of multi-walled carbon nanotubes can be twisted and manipulated into continuous fibers or yarns that exhibit many of the characteristics of traditional textiles. Macro-scale analysis and test may provide strength and stiffness predictions for a composite composed of a polymer matrix and low-volume fraction yarns. However, due to the nano-scale of the carbon nanotubes, it is desirable to use atomistic calculations to consider tube-tube interactions and the influence of simulated twist on the effective friction coefficient. This paper reports laboratory test data on the mechanical response of a multi-walled, carbon nanotube yarn/polymer composite from both dynamic and quasi-static tensile tests. Macroscale and nano-scale analysis methods are explored and used to define some of the key structure-property relationships. The measured influence of hot-wet aging on the tensile properties is also reported.

  14. Single walled carbon nanotube network—Tetrahedral amorphous carbon composite film

    Energy Technology Data Exchange (ETDEWEB)

    Iyer, Ajai, E-mail: ajai.iyer@aalto.fi; Liu, Xuwen; Koskinen, Jari [Department of Materials Science and Engineering, School of Chemical Technology, Aalto University, POB 16200, 00076 Espoo (Finland); Kaskela, Antti; Kauppinen, Esko I. [NanoMaterials Group, Department of Applied Physics, School of Science, Aalto University, POB 15100, 00076 Espoo (Finland); Johansson, Leena-Sisko [Department of Forest Products Technology, School of Chemical Technology, Aalto University, POB 16400, 00076 Espoo (Finland)

    2015-06-14

    Single walled carbon nanotube network (SWCNTN) was coated by tetrahedral amorphous carbon (ta-C) using a pulsed Filtered Cathodic Vacuum Arc system to form a SWCNTN—ta-C composite film. The effects of SWCNTN areal coverage density and ta-C coating thickness on the composite film properties were investigated. X-Ray photoelectron spectroscopy measurements prove the presence of high quality sp{sup 3} bonded ta-C coating on the SWCNTN. Raman spectroscopy suggests that the single wall carbon nanotubes (SWCNTs) forming the network survived encapsulation in the ta-C coating. Nano-mechanical testing suggests that the ta-C coated SWCNTN has superior wear performance compared to uncoated SWCNTN.

  15. Identifying new lignin bioengineering targets: 1. Monolignol-substitute impacts on lignin formation and cell wall fermentability

    Directory of Open Access Journals (Sweden)

    Lu Fachuang

    2010-06-01

    Full Text Available Abstract Background Recent discoveries highlighting the metabolic malleability of plant lignification indicate that lignin can be engineered to dramatically alter its composition and properties. Current plant biotechnology efforts are primarily aimed at manipulating the biosynthesis of normal monolignols, but in the future apoplastic targeting of phenolics from other metabolic pathways may provide new approaches for designing lignins that are less inhibitory toward the enzymatic hydrolysis of structural polysaccharides, both with and without biomass pretreatment. To identify promising new avenues for lignin bioengineering, we artificially lignified cell walls from maize cell suspensions with various combinations of normal monolignols (coniferyl and sinapyl alcohols plus a variety of phenolic monolignol substitutes. Cell walls were then incubated in vitro with anaerobic rumen microflora to assess the potential impact of lignin modifications on the enzymatic degradability of fibrous crops used for ruminant livestock or biofuel production. Results In the absence of anatomical constraints to digestion, lignification with normal monolignols hindered both the rate and extent of cell wall hydrolysis by rumen microflora. Inclusion of methyl caffeate, caffeoylquinic acid, or feruloylquinic acid with monolignols considerably depressed lignin formation and strikingly improved the degradability of cell walls. In contrast, dihydroconiferyl alcohol, guaiacyl glycerol, epicatechin, epigallocatechin, and epigallocatechin gallate readily formed copolymer-lignins with normal monolignols; cell wall degradability was moderately enhanced by greater hydroxylation or 1,2,3-triol functionality. Mono- or diferuloyl esters with various aliphatic or polyol groups readily copolymerized with monolignols, but in some cases they accelerated inactivation of wall-bound peroxidase and reduced lignification; cell wall degradability was influenced by lignin content and the degree

  16. Murein and pseudomurein cell wall binding domains of bacteria and archaea-a comparative view

    NARCIS (Netherlands)

    Visweswaran, Ganesh Ram R.; Dijkstra, Bauke W.; Kok, Jan

    2011-01-01

    The cell wall, a major barrier protecting cells from their environment, is an essential compartment of both bacteria and archaea. It protects the organism from internal turgor pressure and gives a defined shape to the cell. The cell wall serves also as an anchoring surface for various proteins and a

  17. Cell wall proteins of Sporothrix schenckii as immunoprotective agents.

    Science.gov (United States)

    Alba-Fierro, Carlos A; Pérez-Torres, Armando; López-Romero, Everardo; Cuéllar-Cruz, Mayra; Ruiz-Baca, Estela

    2014-01-01

    Sporothrix schenckii is the etiological agent of sporotrichosis, an endemic subcutaneous mycosis in Latin America. Cell wall (CW) proteins located on the cell surface are inducers of cellular and humoral immune responses, potential candidates for diagnosis purposes and to generate vaccines to prevent fungal infections. This mini-review emphasizes the potential use of S. schenckii CW proteins as protective and therapeutic immune response inducers against sporotrichosis. A number of pathogenic fungi display CW components that have been characterized as inducers of protective cellular and humoral immune responses against the whole pathogen from which they were originally purified. The isolation and characterization of immunodominant protein components of the CW of S. schenckii have become relevant because of their potential in the development of protective and therapeutic immune responses against sporotrichosis. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012).

  18. Molecular Mechanisms for Vascular Development and Secondary Cell Wall Formation

    Science.gov (United States)

    Yang, Jung Hyun; Wang, Huanzhong

    2016-01-01

    Vascular tissues are important for transporting water and nutrients throughout the plant and as physical support of upright growth. The primary constituents of vascular tissues, xylem, and phloem, are derived from the meristematic vascular procambium and cambium. Xylem cells develop secondary cell walls (SCWs) that form the largest part of plant lignocellulosic biomass that serve as a renewable feedstock for biofuel production. For the last decade, research on vascular development and SCW biosynthesis has seen rapid progress due to the importance of these processes to plant biology and to the biofuel industry. Plant hormones, transcriptional regulators and peptide signaling regulate procambium/cambium proliferation, vascular patterning, and xylem differentiation. Transcriptional regulatory pathways play a pivot role in SCW biosynthesis. Although most of these discoveries are derived from research in Arabidopsis, many genes have shown conserved functions in biofuel feedstock species. Here, we review the recent advances in our understanding of vascular development and SCW formation and discuss potential biotechnological uses. PMID:27047525

  19. Proteomic Analysis to Identify Tightly-Bound Cell Wall Protein in Rice Calli

    OpenAIRE

    Cho, Won Kyong; Hyun, Tae Kyung; Kumar, Dhinesh; Rim, Yeonggil; Chen, Xiong Yan; Jo, Yeonhwa; Kim, Suwha; Lee, Keun Woo; Park, Zee-Yong; Lucas, William J.; Kim, Jae-Yean

    2015-01-01

    Rice is a model plant widely used for basic and applied research programs. Plant cell wall proteins play key roles in a broad range of biological processes. However, presently, knowledge on the rice cell wall proteome is rudimentary in nature. In the present study, the tightly-bound cell wall proteome of rice callus cultured cells using sequential extraction protocols was developed using mass spectrometry and bioinformatics methods, leading to the identification of 1568 candidate proteins. Ba...

  20. First-wall tile attachment using carbon-carbon composite fittings

    International Nuclear Information System (INIS)

    As the reality of a tokamak device capable of achieving sustained burn missions approaches, the need for a reliable and maintainable plasma-interfacing first wall becomes more evident. This is especially true of compact ignition tokamaks such as LITE, ISP, and Ignitor. Current studies indicate that the compact ignition tokamak may be designed for inertial cooling using a cryogen such as liquid nitrogen, for active cooling using water, or for a combination of inertial (LN2) and active (H2O) cooling. In none of these cases it is anticipated that the first wall proper will be actively cooled. Based on limiter development for operating tokamaks such as the Tokamak Fusion Test Reactor and on supporting engineering studies, an array of monolithic graphite blocks or tiles of appropriate thickness, size, and shape appears to be the most effective approach for a first-wall design. The entire internal wetted surface of the vacuum vessel, exclusive of penetrations and minimal clearance (∼ 1.5 mm) between tiles, will be covered by the monolithic graphite tiles. One of the major challenges of this first-wall approach will be the physical attachment of the tiles to the vacuum vessel inner surface. This paper presents unique first-wall tile attachment concepts that use structural attachment of the graphite tiles to an Inconel 625 vacuum vessel with carbon-carbon composite structural/mechanical elements

  1. Experimental and analytical study on seismic behavior of steel-concrete multienergy dissipation composite shear walls

    Science.gov (United States)

    Dong, Hongying; Cao, Wanlin; Wu, Haipeng; Qiao, Qiyun; Yu, Chuanpeng

    2015-03-01

    In this paper, a steel-concrete multi-energy dissipation composite shear wall, comprised of steel-reinforced concrete (SRC) columns, steel plate (SP) deep beams, a concrete wall and energy dissipation strips, is proposed. In order to study the multi-energy dissipation behavior and restorability after an earthquake, two stages of low cyclic loading tests were carried out on ten test specimens. In the first stage, test on five specimens with different number of SP deep beams was carried out, and the test lasted until the displacement drift reached 2%. In the second stage, thin SPs were welded to both sides of the five specimens tested in the first stage, and the same test was carried out on the repaired specimens (designated as new specimens). The load-bearing capacity, stiffness, ductility, hysteretic behavior and failure characteristics were analyzed for both stages and the results are discussed herein. Extrapolating from these results, strength calculation models and formulas are proposed herein and simulations using ABAQUS carried out; they show good agreement with the test results. The study demonstrates that SRC columns, SP deep beams, concrete wall and energy dissipation strips cooperate well and play an important role in energy dissipation. In addition, this study shows that the shear wall has good recoverability after an earthquake, and that the welding of thin SP's to repair a deformed wall is a practicable technique.

  2. Identification of Lignin and Polysaccharide Modifications in Populus Wood by Chemometric Analysis of 2D NMR Spectra from Dissolved Cell Walls

    Institute of Scientific and Technical Information of China (English)

    Mattias Hedenstrom; Susanne Wiklund-Lindstrom; Tommy (O)man; Fachuang Lu; Lorenz Gerber; Paul Schatz; Bj(o)rn Sundberg; John Ralph

    2009-01-01

    2D ~(13)C-~1H HSQC NMR spectroscopy of acetylated cell walls in solution gives a detailed fingerprint that can be used to assess the chemical composition of the complete wall without extensive degradation. We demonstrate how multivariate analysis of such spectra can be used to visualize cell wall changes between sample types as high-resolution 2D NMR loading spectra. Changes in composition and structure for both lignin and polysaccharides can subsequently be interpreted on a molecular level. The multivariate approach alleviates problems associated with peak picking of overlap-ping peaks, and it allows the deduction of the relative importance of each peak for sample discrimination. As a first proof of concept, we compare Populus tension wood to normal wood. All well established differences in cellulose, hemicellulose, and lignin compositions between these wood types were readily detected, confirming the reliability of the multivariate approach. In a second example, wood from transgenic Populus modified in their degree of pectin methylesterification was compared to that of wild-type trees. We show that differences in both lignin and polysaccharide composition that are difficult to detect with traditional spectral analysis and that could not be a priori predicted were revealed by the multi-variate approach. 2D NMR of dissolved cell wall samples combined with multivariate analysis constitutes a novel approach in cell wall analysis and provides a new tool that will benefit cell wall research.

  3. Binding of paraquat to cell walls of paraquat resistant and susceptible biotypes of Hordeum glaucum

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, H.M.; Preston, C.; Powles, S.B. [University of Adeilaide, Glen Osmond, SA (Australia). CRC for Weed Management Systems and Department of Crop Protection

    1997-12-31

    Full text: Paraquat is a widely used, non-selective, light activated contact herbicide acting as a photosystem electron acceptor. Resistance to paraquat in weed species has occurred in Australia and world-wide following extensive use of this herbicide. The mechanism of resistance to paraquat in `Hordeum glaucum` is correlated with reduced herbicide translocation and may be due to sequestration of herbicide away from its site of action by either binding to cell walls or other means. We measured paraquat binding to a cell wall fraction in resistant and susceptible biotypes of H. glaucum to determine whether differences in binding of paraquat to cell walls could explain herbicide resistance. The cell wall fraction was isolated from leaves of resistant and susceptible biotypes and incubated with {sup 14}C-labelled paraquat. Of the total paraquat - absorbed by a cell wall preparation, about 80% remains strongly bind to the cell wall and doesn`t readily exchange with solution in the absence of divalent cations. Divalent cations (Ca{sup 2+},putrescine and paraquat) can competitively exchange for paraquat tightly bound to the cell wall. From kinetic experiments it seems that there are two types of binding sites in the cell wall with different affinities for paraquat. No significant differences between cell wall, characteristics of resistant and susceptible biotypes of H. glaucum have been found in any of our experiments. Therefore, increased binding of paraquat to the cell wall appears not to be a mechanism for exclusion of paraquat in resistant biotype

  4. On sixfold coupled vibrations of thin-walled composite box beams

    OpenAIRE

    Vo, Thuc; Lee, Jaehong; Ahn, Namshik

    2009-01-01

    This paper presents a general analytical model for free vibration of thin-walled composite beams with arbitrary laminate stacking sequences and studies the effects of shear deformation over the natural frequencies. This model is based on the first-order shear-deformable beam theory and accounts for all the structural coupling coming from the material anisotropy. The seven governing differential equations for coupled flexural–torsional–shearing vibration are derived from the Hamilton’s princip...

  5. Seismic in-plane behavior of URM walls upgraded with composites

    OpenAIRE

    Elgawady, Mohamed; Smith, Ian

    2005-01-01

    Existing unreinforced masonry (URM) buildings, many of which have historical and cultural importance, constitute a significant portion of existing buildings around the world. Recent earthquakes have shown the vulnerability of such URM buildings. This thesis investigates the in-plane seismic behavior of URM walls retrofitted using composites. The thesis includes an extensive dynamic and static cyclic tests followed with development of an analytical model. For the dynamic tests, five half-scale...

  6. Fabrication of multi-walled carbon nanotubes-aluminum matrix composite by powder metallurgy technique

    Science.gov (United States)

    Bunakov, N. A.; Kozlov, D. V.; Golovanov, V. N.; Klimov, E. S.; Grebchuk, E. E.; Efimov, M. S.; Kostishko, B. B.

    We report on fabrication of an aluminum matrix composite containing multi-walled carbon nanotubes (MWCNTs) produced by MOCVD method and functionalized via acid treatment by a H2SO4/HNO3 mixture. Specimens were prepared by spark plasma sintering (SPS) of the aluminum powder with different amounts of functionalized MWCNTs (FMWCNTs) in the range of 0.1-1 wt.%. We studied the effect of FMWCNTs amount on microstructure and mechanical properties of composites. It is shown that functionalization allows homogeneous dispersing of the MWCNTs in Al powder. The maximal increase in micro-hardness and tensile strength is registered at 0.1 wt.%.

  7. Vibration and Stability of Variable Cross Section Thin-Walled Composite Shafts with Transverse Shear

    Directory of Open Access Journals (Sweden)

    Ma Jing-min

    2015-01-01

    Full Text Available A dynamic model of composite shaft with variable cross section is presented. Free vibration equations of the variable cross section thin-walled composite shaft considering the effect of shear deformation are established based on a refined variational asymptotic method and Hamilton’s principle. The numerical results calculated by Galerkin method are analyzed to indicate the effects of ply angle, taper ratio, and transverse shear deformation on the first natural frequency and critical rotating speed. The results are compared with those obtained by using finite element package ANSYS and available in the literature using other models.

  8. Characterizations of Enriched Metallic Single-Walled Carbon Nanotubes in Polymer Composite

    Science.gov (United States)

    Chen, Bin; Li, Jing; Lu, Yijiang; Cinke, Martin; Au, Dyng; Harmon, Julie P.; Muisener, Patricia Anne O.; Clayton, LaNetra; D'Angelo, John

    2003-01-01

    Using different processing conditions, we disperse the single-walled carbon nanotube (SWNT) into the polymethyl methacrylate (PMMA) to form composites. In the melt-blended sample, the SWNTs originally semiconducting - became predominantly metallic after dispersion into the melt-blended composite. The interaction of the PMMA and SWNT is investigated by the polarized Raman studies. The structure changes in the PMMA and SWNT shows that the anisotropic interactions are responsible for SWNT electronic density of states (DOS) changes. The increased metallic SWNT percentage is confirmed by the conductivity and dielectric constant measurements .

  9. Synthesis and Characterization of Multi Wall Carbon Nanotubes (MWCNT) Reinforced Sintered Magnesium Matrix Composites

    Science.gov (United States)

    Vijaya Bhaskar, S.; Rajmohan, T.; Palanikumar, K.; Bharath Ganesh Kumar, B.

    2016-04-01

    Metal matrix composites (MMCs) reinforced with ceramic nano particles (less than 100 nm), termed as metal matrix nano composites (MMNCs), can overcome those disadvantages associated with the conventional MMCs. MMCs containing carbon nanotubes are being developed and projected for diverse applications in various fields of engineering like automotive, avionic, electronic and bio-medical sectors. The present investigation deals with the synthesis and characterization of hybrid magnesium matrix reinforced with various different wt% (0-0.45) of multi wall carbon nano tubes (MWCNT) and micro SiC particles prepared through powder metallurgy route. Microstructure and mechanical properties such as micro hardness and density of the composites were examined. Microstructure of MMNCs have been investigated by scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectroscopy (EDS) for better observation of dispersion of reinforcement. The results indicated that the increase in wt% of MWCNT improves the mechanical properties of the composite.

  10. Rheological and mechanical study of regenerated cellulose/multi-walled carbon nanotube composites

    Science.gov (United States)

    Shao, Wei; Wang, Shuxia; Liu, Hui; Wu, Jimin; Huang, Min; Ma, Wenjing; Huang, Chaobo

    2016-09-01

    Regenerated cellulose (RC)-based composites reinforced with multi-walled carbon nanotubes (MWCNTs) were prepared by a facile casting method. The morphology and microstructure of the fabricated composites were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Thermogravimetry and derivative thermogravimetric analysis were conducted to investigate the effect of MWCNTs on the thermal behaviors of the RC. The results showed that the introduction of MWCNTs enhanced the thermal stability of the RC. Moreover, the effect of the dispersion state of MWCNTs in microcrystalline cellulose/ZnCl2 solutions with varying MWCNT loadings was studied by rheological tests. The mechanical properties of composite films were remarkably improved compared to those of pure RC film. Specifically, the composite film containing 3 wt% of MWCNTs exhibits a 123% enhancement in tensile strength and a 163% enhancement in the Young’s modulus compared with the pure RC film.

  11. Rheological and mechanical study of regenerated cellulose/multi-walled carbon nanotube composites.

    Science.gov (United States)

    Shao, Wei; Wang, Shuxia; Liu, Hui; Wu, Jimin; Huang, Min; Ma, Wenjing; Huang, Chaobo

    2016-09-30

    Regenerated cellulose (RC)-based composites reinforced with multi-walled carbon nanotubes (MWCNTs) were prepared by a facile casting method. The morphology and microstructure of the fabricated composites were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Thermogravimetry and derivative thermogravimetric analysis were conducted to investigate the effect of MWCNTs on the thermal behaviors of the RC. The results showed that the introduction of MWCNTs enhanced the thermal stability of the RC. Moreover, the effect of the dispersion state of MWCNTs in microcrystalline cellulose/ZnCl2 solutions with varying MWCNT loadings was studied by rheological tests. The mechanical properties of composite films were remarkably improved compared to those of pure RC film. Specifically, the composite film containing 3 wt% of MWCNTs exhibits a 123% enhancement in tensile strength and a 163% enhancement in the Young's modulus compared with the pure RC film. PMID:27574002

  12. Use of the Plant Defense Protein Osmotin To Identify Fusarium oxysporum Genes That Control Cell Wall Properties

    KAUST Repository

    Lee, H.

    2010-02-26

    Fusarium oxysporum is the causative agent of fungal wilt disease in a variety of crops. The capacity of a fungal pathogen such as F. oxysporum f. sp. nicotianae to establish infection on its tobacco (Nicotiana tabacum) host depends in part on its capacity to evade the toxicity of tobacco defense proteins, such as osmotin. Fusarium genes that control resistance to osmotin would therefore reflect coevolutionary pressures and include genes that control mutual recognition, avoidance, and detoxification. We identified FOR (Fusarium Osmotin Resistance) genes on the basis of their ability to confer osmotin resistance to an osmotin-sensitive strain of Saccharomyces cerevisiae. FOR1 encodes a putative cell wall glycoprotein. FOR2 encodes the structural gene for glutamine:fructose-6-phosphate amidotransferase, the first and rate-limiting step in the biosynthesis of hexosamine and cell wall chitin. FOR3 encodes a homolog of SSD1, which controls cell wall composition, longevity, and virulence in S. cerevisiae. A for3 null mutation increased osmotin sensitivity of conidia and hyphae of F. oxysporum f. sp. nicotianae and also reduced cell wall β-1,3-glucan content. Together our findings show that conserved fungal genes that determine cell wall properties play a crucial role in regulating fungal susceptibility to the plant defense protein osmotin.

  13. High-throughput microarray mapping of cell wall polymers in roots and tubers during the viscosity-reducing process.

    Science.gov (United States)

    Huang, Yuhong; Willats, William G; Lange, Lene; Jin, Yanling; Fang, Yang; Salmeán, Armando A; Pedersen, Henriette L; Busk, Peter Kamp; Zhao, Hai

    2016-03-01

    Viscosity reduction has a great impact on the efficiency of ethanol production when using roots and tubers as feedstock. Plant cell wall-degrading enzymes have been successfully applied to overcome the challenges posed by high viscosity. However, the changes in cell wall polymers during the viscosity-reducing process are poorly characterized. Comprehensive microarray polymer profiling, which is a high-throughput microarray, was used for the first time to map changes in the cell wall polymers of sweet potato (Ipomoea batatas), cassava (Manihot esculenta), and Canna edulis Ker. over the entire viscosity-reducing process. The results indicated that the composition of cell wall polymers among these three roots and tubers was markedly different. The gel-like matrix and glycoprotein network in the C. edulis Ker. cell wall caused difficulty in viscosity reduction. The obvious viscosity reduction of the sweet potato and the cassava was attributed to the degradation of homogalacturonan and the released 1,4-β-d-galactan and 1,5-α-l-arabinan. PMID:25757626

  14. Seasonal biochemical changes in composition of body wall tissues of sea cucumber Apostichopus japonicus

    Institute of Scientific and Technical Information of China (English)

    GAO Fei; XU Qiang; YANG Hongsheng

    2011-01-01

    Seasonal variation in proximate, amino acid and fatty acid composition of the body wall of sea cucumber Apostichopus japonicus was evaluated. The proximate composition, except for ash content, changed significantly among seasons (P<0.05). Alanine, glycine, glutamic acid and asparagic acid were the most abundant amino acids. Total amino acid and essential amino acid contents both varied clearly with seasons (P<0.05). 16:0 and 16:1n7 were the primary saturated fatty acid (SFA)and monounsaturated fatty acid (MUFA) respectively for all months. EPA (20:5n-3), AA (20:4n-6)and DHA (22:6n-3) were the major polyunsaturated fatty acids (PUFA). The proportions of SFA and PUFA yielded significant seasonal variations (P<0.001), but MUFA did not changed significantly.The results indicated that the biochemical compositions of the body wall in A. japonicus were significantly influenced by seasons and that the body wall tissue is an excellent source of protein,MUFA and n-3 PUFA for humans.

  15. Hematopoietic Stem Cells Expansion in Rotating Wall Vessel

    Institute of Scientific and Technical Information of China (English)

    Yang LIU; Tian-Qing LIU; Xiu-Bo FAN; Dan GE; Zhan-Feng CUI; Xue-Hu MA

    2005-01-01

    @@ 1 Introduction Clinical trials have demonstrated that ex vivo expanded hematopoietic stem cells (HSCs) and progenitors offer great promise in reconstituting in vivo hematopoiesis in patients who have undergone intensive chemotherapy.It is therefore necessary to develop a clinical-scale culture system to provide the expanded HSCs and progenitors.Static culture systems such as T-flasks and gas-permeable blood bags are the most widely used culture devices for expanding hematopoietic cells. But they reveal several inherent limitations: ineffective mixing, lack of control options for dissolved oxygen and pH and difficulty in continuous feeding, which restricts the usefulness of static systems. Several advanced bioreactors have been used in the field of HSCs expansion. But hematopoietic cells are extremely sensitive to shear, so cells in bioreactors such as stirred and perfusion culture systems may suffer physical damage. This problem will be improved by applying the rotating wall vessel (RWV) bioreactor in clinic because of its low shear and unique structure. In this research, cord blood (CB) HSCs were expanded by means of a cell-dilution feeding protocol in RWV.

  16. The connection of cytoskeletal network with plasma membrane and the cell wall

    Institute of Scientific and Technical Information of China (English)

    Zengyu Liu; Staffan Persson; Yi Zhang

    2015-01-01

    The cell wall provides external support of the plant cells, while the cytoskeletons including the microtubules and the actin filaments constitute an internal framework. The cytoskeletons contribute to the cell wall biosynthesis by spatially and temporarily regulating the transportation and deposition of cell wall components. This tight control is achieved by the dynamic behavior of the cytoskeletons, but also through the tethering of these structures to the plasma membrane. This tethering may also extend beyond the plasma membrane and impact on the cell wall, possibly in the form of a feedback loop. In this review, we discuss the linking components between the cytoskeletons and the plasma membrane, and/or the cell wall. We also discuss the prospective roles of these components in cell wall biosyn-thesis and modifications, and aim to provide a platform for further studies in this field.

  17. Research on the Changes of Cell Wall Composition in Different Varieties of Loquat Pulp During Fruit Development%不同枇杷品种果实发育过程中果肉细胞壁组分的研究

    Institute of Scientific and Technical Information of China (English)

    陈宇; 黄志明; 叶美兰; 吴锦程

    2012-01-01

    探讨不同发育时期,细胞壁组分的变化对不同品种枇杷果肉质地的影响。以果肉质地差异较大的'解放钟'(Eriobotrya japonica Lindl.cv.Jiefangzhong)和'白梨'枇杷(Eriobotrya japonica Lindl.cv.Baili)为试材,分析果实在生长发育过程中细胞壁组分的变化,分析果肉质地差异性与细胞壁成分之间的相关性。结果表明,果实生长发育过程中,'解放钟'和'白梨'枇杷果肉水溶性果胶(water solublepectin,WSP)含量均呈上升趋势;离子结合果胶(Ionic bound pectin,ISP)、共价结合果胶(covalently boundpectin,CSP)、纤维素(Cellulose)、半纤维素(semi-cellulose)、总钙和氯化钠溶性钙含量均呈下降趋势。在果实发育后期',解放钟'果肉WSP和细胞壁离子结合蛋白含量显著高于'白梨'(P〈0.05),但两者的细胞壁共价结合蛋白含量差异不大'。解放钟'果肉纤维素含量始终高于'白梨'且差异达显著水平(P〈0.05),而果肉半纤维素含量差异不显著(P〉0.05)。WSP、ISP、CSP、纤维素、半纤维素、离子结合蛋白与枇杷果肉质地形成相关,WSP、纤维素和离子结合蛋白是形成'解放钟'和'白梨'枇杷果肉质地差异的主要因素。%To discuss effects of cell wall composition on the pulp texture during fruit development. Eriobotrya japonica Lindl. cv.‘Jiefangzhong’and Eriobotrya japonica Lindl. cv.‘Baili’loquat were used as matierials to study relationship between pulp texture and cell wall composition during fruit development. The results indicated that the cotents of water soluble pectin (WSP) in loquat pulp showed an increasing tendency, and the cotents ionic bound pectin (ISP), covalently bound pectin (CSP), cellulose, semi-cellulose, total calcium and sodium chloride soluble calcium were downtrend during fruit development. During later-developing stage, the contents of WSP and cell wall

  18. Arabidopsis Heterotrimeric G-protein Regulates Cell Wall Defense and Resistance to Necrotrophic Fungi

    Institute of Scientific and Technical Information of China (English)

    Magdalena Delcado-Cerezo; Paul Schulze-Lefert; Shauna Somerville; José Manuel Estevez; Staffan Persson; Antonio Molina; Clara Sánchez-Rodríguez; Viviana Escudero; Eva Miedes; Paula Virginia Fernández; Lucía Jordá; Camilo Hernández-Blanco; Andrea Sánchez-Vallet; Pawel Bednarek

    2012-01-01

    The Arabidopsis heterotrimeric G-protein controls defense responses to necrotrophic and vascular fungi.The agb1 mutant impaired in the Gβ subunit displays enhanced susceptibility to these pathogens.Gβ/AGB1 forms an obligate dimer with either one of the Arabidopsis Gγ subunits (γ1/AGG1 and γ2/AGG2).Accordingly,we now demonstrate that the agg1 agg2 double mutant is as susceptible as agb1 plants to the necrotrophic fungus Plectosphaerella cucumerina.To elucidate the molecular basis of heterotrimeric G-protein-mediated resistance,we performed a comparative transcriptomic analysis of agb1-1 mutant and wild-type plants upon inoculation with P cucumerina.This analysis,together with metabolomic studies,demonstrated that G-protein-mediated resistance was independent of defensive pathways required for resistance to necrotrophic fungi,such as the salicylic acid,jasmonic acid,ethylene,abscisic acid,and tryptophan-derived metabolites signaling,as these pathways were not impaired in agb1 and agg1 agg2 mutants.Notably,many mis-regulated genes in agb1 plants were related with cell wall functions,which was also the case in agg1 agg2 mutant.Biochemical analyses and Fourier Transform InfraRed (FTIR) spectroscopy of cell walls from G-protein mutants revealed that the xylose content was lower in agb1 and agg1 agg2 mutants than in wild-type plants,and that mutant walls had similar FTIR spectratypes,which differed from that of wild-type plants.The data presented here suggest a canonical functionality of the Gβ and Gγ1/γ2 subunits in the control of Arabidopsis immune responses and the regulation of cell wall composition.

  19. Experimental thermal study and numerical simulation of a composite solar wall. Optimization of the energetic performances; Etude thermique experimentale et simulation numerique d`un mur solaire composite. Optimisation des performances energetiques

    Energy Technology Data Exchange (ETDEWEB)

    Zalewski, L.

    1996-11-27

    The objective of this work is the analysis of a passive solar component: the composite solar wall, a building component, which includes an insulating panel located behind the massive wall. This panel has two vents located at the top and at the bottom, which allow the air to circulate from the room to the layer in contact with the back of the massive wall, where it is heated, and then back to the room. The solar energy is transferred to the building by conduction through the massive wall, and then by convection using a thermosyphon phenomenon. The monitoring of 2 solar houses in Verdun-Thierville (Meuse, France) has clearly shown, control issues of the air layer. The wall must be operated as autonomously as possible, to not be a constraint for the occupants and to get an optimization of the energy gains. To solve these problems, a composite solar wall prototype was erected in a test cell at Cadarache and tested in real operating conditions. This allows to use a more complete instrumentation, to have access more easily to the sensors and to study various configurations. The first experiments revealed an inverse thermosyphon phenomenon. To avoid this effect, two systems were designed, tested at Cadarache and then implemented in the walls at Verdun. (author) 77 refs.

  20. IDENTIFYING GENES CONTROLLING FERULATE CROSS-LINKING FORMATION IN GRASS CELL WALLS

    Energy Technology Data Exchange (ETDEWEB)

    de O Buanafina, Marcia Maria

    2013-10-16

    DESCRIPTION/ABSTRACT This proposal focuses on cell wall feruloylation and our long term goal is to identify and isolate novel genes controlling feruloylation and to characterize the phenotype of mutants in this pathway, with a spotlight on cell wall properties. Currently, the genes underlying AX feruloylation have not been identified and the isolation of such genes could be of great importance in manipulating ferulates accretion to the wall. Mutation of the feruloyl transferase gene(s) should lead to less ferulates secreted to the cell wall and reduced ferulate cross-linking. Our current research is based on the hypothesis that controlling the level of total feruloylation will have a direct impact on the level of cross-linking and in turn impact biomass utility for forage and biofuel production. Our results/accomplishments for this project so far include: 1. Mutagenised Brachypodium population. We have developed EMS mutagenized populations of model grass species Brachypodium distachyon. EMS populations have been developed from over 28,000 mutagenized seeds generating 5,184 M2 families. A total of 20,793 plants have been screened and 1,233 were originally selected. 2. Selected Brachypodium mutants: Potential mutants on their levels of cell wall ferulates and cell wall AX ? have been selected from 708 M2 families. A total of 303 back-crosses to no-mutagenized parental stock have been done, followed by selfing selected genotypes in order to confirm heritability of traits and to remove extraneous mutations generated by EMS mutagenesis. We are currently growing 12 F5 and F6 populations in order to assess CW composition. If low level of ferulates are confirmed in the candidate lines selected the mutation could be altered in different in one or several kinds of genes such as genes encoding an AX feruloyl transferase; genes encoding the arabinosyl transferase; genes encoding the synthesis of the xylan backbone; genes encoding enzymes of the monolignol pathway affecting FA

  1. Biochemistry and Cell Wall Changes Associated with Noni (Morinda citrifolia L.) Fruit Ripening.

    Science.gov (United States)

    Cárdenas-Coronel, Wendy G; Carrillo-López, Armando; Vélez de la Rocha, Rosabel; Labavitch, John M; Báez-Sañudo, Manuel A; Heredia, José B; Zazueta-Morales, José J; Vega-García, Misael O; Sañudo-Barajas, J Adriana

    2016-01-13

    Quality and compositional changes were determined in noni fruit harvested at five ripening stages, from dark-green to thaslucent-grayish. Fruit ripening was accompanied by acidity and soluble solids accumulation but pH diminution, whereas the softening profile presented three differential steps named early (no significant softening), intermediate (significant softening), and final (dramatic softening). At early step the extensive depolymerization of hydrosoluble pectins and the significantly increment of pectinase activities did not correlate with the slight reduction in firmness. The intermediate step showed an increment of pectinases and hemicellulases activities. The final step was accompanied by the most significant reduction in the yield of alcohol-insoluble solids as well as in the composition of uronic acids and neutral sugars; pectinases increased their activity and depolymerization of hemicellulosic fractions occurred. Noni ripening is a process conducted by the coordinated action of pectinases and hemicellulases that promote the differential dissasembly of cell wall polymers.

  2. Structural characterization of a mixed-linkage glucan deficient mutant reveals alteration in cellulose microfibril orientation in rice coleoptile mesophyll cell walls

    Directory of Open Access Journals (Sweden)

    Andreia Michelle Smith-Moritz

    2015-08-01

    Full Text Available The CELLULOSE SYNTHASE-LIKE F6 (CslF6 gene was previously shown to mediate the biosynthesis of mixed-linkage glucan (MLG, a cell wall polysaccharide that is hypothesized to be a tightly associated with cellulose and also have a role in cell expansion in the primary cell wall of young seedlings in grass species. We have recently shown that loss-of-function cslf6 rice mutants do not accumulate MLG in most vegetative tissues. Despite the absence of a structurally important polymer, MLG, these mutants are unexpectedly viable and only show a moderate growth compromise compared to wild type. Therefore these mutants are ideal biological systems to test the current grass cell wall model. In order to gain a better understanding of the role of MLG in the primary wall, we performed in-depth compositional and structural analyses of the cell walls of three day-old rice seedlings using various biochemical and novel microspectroscopic approaches. We found that cellulose content as well as matrix polysaccharide composition was not significantly altered in the MLG deficient mutant. However, we observed a significant change in cellulose microfibril bundle organization in mesophyll cell walls of the cslf6 mutant. Using synchrotron source Fourier Transform Mid-Infrared Spectromicroscopy for high-resolution imaging, we determined that the bonds associated with cellulose and arabinoxylan, another major component of the primary cell was of grasses, were in a lower energy configuration compared to wild type, suggesting a slightly weaker primary wall in MLG deficient mesophyll cells. Taken together, these results suggest that MLG may influence cellulose deposition in mesophyll cell walls without significantly affecting anisotropic growth thus challenging MLG importance in cell wall expansion.

  3. Area Expansivity Moduli of Regenerating Plant Protoplast Cell Walls Exposed to Shear Flows

    Science.gov (United States)

    Fujimura, Yuu; Iino, Masaaki; Watanabe, Ugai

    2005-05-01

    To control the elasticity of the plant cell wall, protoplasts isolated from cultured Catharanthus roseus cells were regenerated in shear flows of 115 s-1 (high shear) and 19.2 s-1 (low shear, as a control). The surface area expansivity modulus and the surface breaking strength of these regenerating protoplasts were measured by a micropipette aspiration technique. Cell wall synthesis was also measured using a cell wall-specific fluorescent dye. High shear exposure for 3 h doubled both the surface area modulus and breaking strength observed under low shear, significantly decreased cell wall synthesis, and roughly quadrupled the moduli of the cell wall. Based on the cell wall synthesis data, we estimated the three-dimensional modulus of the cell wall to be 4.1± 1.2 GPa for the high shear, and 0.35± 0.2 GPa for the low shear condition, using the surface area expansivity modulus divided by the cell wall thickness, which is identical with the Young’s modulus divided by 2(1-σ), where σ is Poisson's ratio. We concluded that high shear exposure considerably strengthens the newly synthesized cell wall.

  4. Schottky Diodes Based on Polyaniline/Multi-Walled Carbon Nanotube Composites

    Science.gov (United States)

    Hajibadali, A.; Nejad, M. Baghaei; Farzi, G.

    2015-08-01

    Polyaniline/multi-walled carbon nanotube composites (PANI/MWCNT), with various concentration of multi-walled carbon nanotube, were synthesized. Several Schottky diodes were fabricated, where PANI or PANI/MWCNT composites, aluminum, and gold were used as semiconductor, Schottky contact, and ohmic contact, respectively. Then current-voltage characteristics of the fabricated diodes were measured at room temperature and within the bias range of -5 to +5 V. The measurements were repeated three times for each sample to verify repeatability of experiment. The obtained results show that by increasing the MWCNT concentration, the current intensity increases. Furthermore, I-V characteristics of pure polyaniline Schottky diode follows the thermionic emission mechanism while the I-V characteristics of Schottky diodes based on PANI/MWCNT composites show two distinct power law regions. At lower voltages, the mechanism follows Ohm's Law, whereas at higher voltages, the mechanism is compatible with space charge limited conduction emission mechanism. The parameters of Schottky diodes were determined, and it was observed that critical voltage decreased when the concentration of MWCNT in the composite increased.

  5. Synthesis of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes composite for supercapacitance application

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Rajesh Kr., E-mail: r05bhu@gmail.com [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore (Singapore); Xingjue, Wang [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore (Singapore); Kumar, Vinod [Department of Zoology, Banaras Hindu University, Varanasi (India); Srivastava, Anchal [Department of Physics, Banaras Hindu University, Varanasi (India); Singh, Vidya Nand [CSIR-National Physical Laboratory, New Delhi (India)

    2014-11-05

    Highlights: • We are reporting supercapacitance performance of BI-GO/MWCNTs composite. • The specific capacitance of BI-GO/MWCNTs is 275 and 460 F/g at 200 and 5 mV/s scan rate. • This composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate. - Abstract: We are reporting the fabrication, characterizations and supercapacitance performance of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes (BI-GO/MWCNTs) composite. The synthesis of BI-GO materials involves cyclization reaction of carboxylic groups on GO among the hydroxyl and amino groups on o-phenylenediamine. The BI-GO/MWCNTs composite has been fabricated via in situ reduction of BI-GO using hydrazine in presence of MWCNTs. Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) have been used to characterize its surface and elemental composition. The uniform dispersion of MWCNTs with BI-GO helps to improve the charge transfer reaction during electrochemical process. The specific capacitance of BI-GO/MWCNTs composite is 275 and 460 F/g at 200 and 5 mV/s scan rate in 1 mol/L aqueous solution of H{sub 2}SO{sub 4}. This BI-GO/MWCNTs composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate, which represents its good electrochemical stability.

  6. The effect of multi-wall carbon nanotubes on electromagnetic interference shielding of ceramic composites.

    Science.gov (United States)

    Shi, Sui-Lin; Liang, Ji

    2008-06-25

    Multi-wall carbon nanotubes (MWCNTs)-3 mol% yttria-stabilized zirconia (3Y-TZP) (MWCNTs-3Y-TZP) composite was prepared by spark plasma sintering. The complex permittivities of the composite have been measured in the Ku-band range (12.4-18 GHz) and it is found that both the real and imaginary permittivities of the composite increase with the increasing content of MWCNTs. The effect of the content of MWCNTs on the electromagnetic interference (EMI) shielding effectiveness (SE) of the composite has been evaluated, and it is found that the EMI SE of the composite increases with the increasing content of MWCNTs. An EMI SE value as high as 25-30 dB has been achieved in the Ku-band range for the composite with 9 wt% content of MWCNTs, indicating that the MWCNTs-3Y-TZP composite can be used as an effective EMI shielding material. PMID:21828667

  7. Facile preparation and electrochemical characterization of cobalt oxide/multi-walled carbon nanotube composites for supercapacitors

    Science.gov (United States)

    Lang, Junwei; Yan, Xingbin; Xue, Qunji

    A series of cobalt oxide/multi-walled carbon nanotube (Co 3O 4/MWCNT) composites are successfully synthesized by a facile chemical co-precipitation method followed by a simple thermal treatment process. The morphology and structure of as-obtained composites are characterized by X-ray diffraction, scanning electron microscopy, and N 2-adsorption/desorption measurements, and the electrochemical properties are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). For all Co 3O 4/MWCNT composites, MWCNTs are well dispersed in the loosely packed Co 3O 4 nanoparticles. Among them, the Co 3O 4-5%MWCNT composite exhibits the highest specific surface area of 137 m 2 g -1 and a mesoporous structure with a narrow distribution of pore size from 2 to 10 nm. Because of the synergistic effects coming from Co 3O 4 nanoparticles and MWCNTs, the electrochemical performances of pure Co 3O 4 material are significantly improved after adding MWCNTs. The Co 3O 4-5%MWCNT composite shows the largest specific capacitance of 418 F g -1 at a current density of 0.625 A g -1 in 2 M KOH electrolyte. Furthermore, this composite exhibits good cycling stability and lifetime. Therefore, based on the above investigation, such Co 3O 4/MWCNT composite could be a potential candidate for supercapacitors.

  8. Cell wall antibiotics provoke accumulation of anchored mCherry in the cross wall of Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Wenqi Yu

    Full Text Available A fluorescence microscopy method to directly follow the localization of defined proteins in Staphylococcus was hampered by the unstable fluorescence of fluorescent proteins. Here, we constructed plasmid (pCX encoded red fluorescence (RF mCherry (mCh hybrids, namely mCh-cyto (no signal peptide and no sorting sequence, mCh-sec (with signal peptide, and mCh-cw (with signal peptide and cell wall sorting sequence. The S. aureus clones targeted mCh-fusion proteins into the cytosol, the supernatant and the cell envelope respectively; in all cases mCherry exhibited bright fluorescence. In staphylococci two types of signal peptides (SP can be distinguished: the +YSIRK motif SP(lip and the -YSIRK motif SP(sasF. mCh-hybrids supplied with the +YSIRK motif SP(lip were always expressed higher than those with -YSIRK motif SP(sasF. To study the location of the anchoring process and also the influence of SP type, mCh-cw was supplied on the one hand with +YSIRK motif (mCh-cw1 and the other hand with -YSIRK motif (mCh-cw2. MCh-cw1 preferentially localized at the cross wall, while mCh-cw2 preferentially localized at the peripheral wall. Interestingly, when treated with sub-lethal concentrations of penicillin or moenomycin, both mCh-cw1 and mCh-cw2 were concentrated at the cross wall. The shift from the peripheral wall to the cross wall required Sortase A (SrtA, as in the srtA mutant this effect was blunted. The effect is most likely due to antibiotic mediated increase of free anchoring sites (Lipid II at the cross wall, the substrate of SrtA, leading to a preferential incorporation of anchored proteins at the cross wall.

  9. Cell wall sorting signals in surface proteins of gram-positive bacteria.

    OpenAIRE

    Schneewind, O; Mihaylova-Petkov, D; Model, P

    1993-01-01

    Staphylococcal protein A is anchored to the cell wall, a unique cellular compartment of Gram-positive bacteria. The sorting signal sufficient for cell wall anchoring consists of an LPXTG motif, a C-terminal hydrophobic domain and a charged tail. Homologous sequences are found in many surface proteins of Gram-positive bacteria and we explored the universality of these sequences to serve as cell wall sorting signals. We show that several signals are able to anchor fusion proteins to the staphyl...

  10. In vivo cell wall loosening by hydroxyl radicals during cress seed germination and elongation growth

    OpenAIRE

    Müller, Kerstin; Linkies, Ada; Vreeburg, Robert A. M.; Fry, Stephen C; Krieger-Liszkay, Anja; Leubner-Metzger, Gerhard

    2009-01-01

    Loosening of cell walls is an important developmental process in key stages of plant life cycles, including seed germination, elongation growth and fruit ripening. Here we report direct in vivo evidence for hydroxyl radical (•OH)-mediated cell wall loosening during plant seed germination and seedling growth. We used electron paramagnetic resonance (EPR)-spectroscopy to show that •OH is generated in the cell wall during radicle elongation and weakening of the endosperm of cress (Lepidium sativ...

  11. Cell Wall Microstructure Analysis Implicates Hemicellulose Polysaccharides in Cell Adhesion in Tomato Fruit Pericarp Parenchyma

    Institute of Scientific and Technical Information of China (English)

    Jose J. Ordaz-Ortiz; Susan E. Marcus; J. Paul Knox

    2009-01-01

    Methods developed to isolate intact cells from both unripe and ripe tomato fruit pericarp parenchyma have allowed the cell biological analysis of polysaccharide epitopes at the surface of separated cells. The LM7 pectic homoga-lacturonan epitope is a marker of the junctions of adhesion planes and intercellular spaces in parenchyma systems. The LM7 epitope persistently marked the former edge of adhesion planes at the surface of cells separated from unripe and ripened tomato fruit and also from fruits with the Cnr mutation. The LM 11 xylan epitope was associated, in sections, with cell walls lining intercellular space but the epitope was not detected at the surface of isolated cells, being lost during cell isolation. The LM15 xyloglucan epitope was present at the surface of cells isolated from unripe fruit in a pattern reflecting the former edge of cell adhesion planes/intercellular space but with gaps and apparent breaks, An equivalent pattern ofLM15 epitope occurrence was revealed at the surface of cells isolated by pectate lyase action but was not present in cells isolated from ripe fruit or from Cnr fruit. In contrast to wild-type cells, the LM5 galactan and LM21 mannan epitopes oc-curred predominantly in positions reflecting intercellular space in Cnr, suggesting a concerted alteration in cell wall mi-crostructure in response to this mutation. Galactanase and mannanase, along with pectic homogalacturonan-degrading enzymes, were capable of releasing cells from unripe fruit parenchyma. These observations indicate that hemicellulose polymers are present in architectural contexts reflecting cell adhesion and that several cell wall polysaccharide classes are likely to contribute to cell adhesion/cell separation in tomato fruit pericarp parenchyma.

  12. Pectinous cell wall thickenings formation - A common defense strategy of plants to cope with Pb.

    Science.gov (United States)

    Krzesłowska, Magdalena; Rabęda, Irena; Basińska, Aneta; Lewandowski, Michał; Mellerowicz, Ewa J; Napieralska, Anna; Samardakiewicz, Sławomir; Woźny, Adam

    2016-07-01

    Lead, one of the most abundant and hazardous trace metals affecting living organisms, has been commonly detected in plant cell walls including some tolerant plants, mining ecotypes and hyperaccumulators. We have previously shown that in tip growing Funaria sp. protonemata cell wall is remodeled in response to lead by formation of thickenings rich in low-methylesterified pectins (pectin epitope JIM5 - JIM5-P) able to bind metal ions, which accumulate large amounts of Pb. Hence, it leads to the increase of cell wall capacity for Pb compartmentalization. Here we show that diverse plant species belonging to different phyla (Arabidopsis, hybrid aspen, star duckweed), form similar cell wall thickenings in response to Pb. These thickenings are formed in tip growing cells such as the root hairs, and in diffuse growing cells such as meristematic and root cap columella cells of root apices in hybrid aspen and Arabidopsis and in mesophyll cells in star duckweed fronds. Notably, all analyzed cell wall thickenings were abundant in JIM5-P and accumulated high amounts of Pb. In addition, the co-localization of JIM5-P and Pb commonly occurred in these cells. Hence, cell wall thickenings formed the extra compartment for Pb accumulation. In this way plant cells increased cell wall capacity for compartmentalization of this toxic metal, protecting protoplast from its toxicity. As cell wall thickenings occurred in diverse plant species and cell types differing in the type of growth we may conclude that pectinous cell wall thickenings formation is a widespread defense strategy of plants to cope with Pb. Moreover, detection of natural defense strategy, increasing plant cell walls capacity for metal accumulation, reveals a promising direction for enhancing plant efficiency in phytoremediation. PMID:27107260

  13. Pectinous cell wall thickenings formation - A common defense strategy of plants to cope with Pb.

    Science.gov (United States)

    Krzesłowska, Magdalena; Rabęda, Irena; Basińska, Aneta; Lewandowski, Michał; Mellerowicz, Ewa J; Napieralska, Anna; Samardakiewicz, Sławomir; Woźny, Adam

    2016-07-01

    Lead, one of the most abundant and hazardous trace metals affecting living organisms, has been commonly detected in plant cell walls including some tolerant plants, mining ecotypes and hyperaccumulators. We have previously shown that in tip growing Funaria sp. protonemata cell wall is remodeled in response to lead by formation of thickenings rich in low-methylesterified pectins (pectin epitope JIM5 - JIM5-P) able to bind metal ions, which accumulate large amounts of Pb. Hence, it leads to the increase of cell wall capacity for Pb compartmentalization. Here we show that diverse plant species belonging to different phyla (Arabidopsis, hybrid aspen, star duckweed), form similar cell wall thickenings in response to Pb. These thickenings are formed in tip growing cells such as the root hairs, and in diffuse growing cells such as meristematic and root cap columella cells of root apices in hybrid aspen and Arabidopsis and in mesophyll cells in star duckweed fronds. Notably, all analyzed cell wall thickenings were abundant in JIM5-P and accumulated high amounts of Pb. In addition, the co-localization of JIM5-P and Pb commonly occurred in these cells. Hence, cell wall thickenings formed the extra compartment for Pb accumulation. In this way plant cells increased cell wall capacity for compartmentalization of this toxic metal, protecting protoplast from its toxicity. As cell wall thickenings occurred in diverse plant species and cell types differing in the type of growth we may conclude that pectinous cell wall thickenings formation is a widespread defense strategy of plants to cope with Pb. Moreover, detection of natural defense strategy, increasing plant cell walls capacity for metal accumulation, reveals a promising direction for enhancing plant efficiency in phytoremediation.

  14. Antioxidant properties of cell wall polysaccharides of Stevia rebaudiana leaves

    Directory of Open Access Journals (Sweden)

    Mediesse Kengne Francine

    2014-12-01

    Full Text Available Objective: To examine the total phenolic and protein contents, and the antioxidant activities of cell wall polysaccharide fractions of Stevia rebaudiana leaves. Methods: Three different polysaccharide-enriched fractions, namely FPE (extract with 50 mmol/ L ethylene diamine tetra acetic acid, FPK (extract with 0.05 mol/L KOH and FH (extract with 4 mol/L KOH were extracted from Stevia rebaudiana leaves. The antioxidant activity of these fractions was evaluated based on their ability to scavenge DPPH (1, 1-diphenyl-2-picryl hydrazyl free radical, to reduce ferric power, to chelate ferrous ion and to protect human DNA. Results: The results indicated that protein content was found to be higher in FPK polysaccharide enriched fraction (47.48 µg per mg of FPK. Furthermore, the phenolic compound analysis according to the Folin-Ciocalteu method was higher in FPK (17.71 µg ferulic acid. The DPPH maximal inhibition percentage of the three polysaccharide-enriched fractions at 400 µg/mL was 27.66%, 59.90% and 23.21% respectively for FPE, FPK and FH. All the polysaccharide fractions exhibited a ferric reducing power except the FH one. The three fractions also exhibited lipid peroxidation inhibition, and they completely reverted the DNA damage induced by H2O2/FeCl2. FPK showed the strongest scavenging activity against the DPPH radical, the best chelating ability and lipid peroxidation inhibition. Conclusions: Stevia cell wall polysaccharide fractions are potent protective agents against oxidative stress. The analysis revealed major differences in the antioxidant activity in the three polysaccharides fractions. However, the 0.05 mol/L KOH pectin fraction (FPK showed better antioxidant activity.

  15. Antioxidant properties of cell wall polysaccharides of Stevia rebaudiana leaves

    Institute of Scientific and Technical Information of China (English)

    Mediesse Kengne Francine; Woguia Alice Louise; Fogue Souopgui Pythagore; Atogho-Tiedeu Barbara; Simo Gustave; Thadde Boudjeko

    2014-01-01

    Objective: To examine the total phenolic and protein contents, and the antioxidant activities of cell wall polysaccharide fractions of Stevia rebaudiana leaves.Methods:L ethylene diamine tetra acetic acid), FPK (extract with 0.05 mol/L KOH) and FH (extract with 4 mol/L KOH) were extracted from Stevia rebaudiana leaves. The antioxidant activity of these fractions was evaluated based on their ability to scavenge DPPH (1, 1-diphenyl-2-picryl hydrazyl) free radical, to reduce ferric power, to chelate ferrous ion and to protect human DNA. Three different polysaccharide-enriched fractions, namely FPE (extract with 50 mmol/Results: The results indicated that protein content was found to be higher in FPK polysaccharide enriched fraction (47.48 µg per mg of FPK). Furthermore, the phenolic compound analysis according to the Folin-Ciocalteu method was higher in FPK (17.71 µg ferulic acid). The DPPH maximal inhibition percentage of the three polysaccharide-enriched fractions at 400 µg/mL was 27.66%, 59.90% and 23.21% respectively for FPE, FPK and FH. All the polysaccharide fractions exhibited a ferric reducing power except the FH one. The three fractions also exhibited lipid peroxidation inhibition, and they completely reverted the DNA damage induced by H2O2/FeCl2. FPK showed the strongest scavenging activity against the DPPH radical, the best chelating ability and lipid peroxidation inhibition.Conclusions: Stevia cell wall polysaccharide fractions are potent protective agents against oxidative stress. The analysis revealed major differences in the antioxidant activity in the three polysaccharides fractions. However, the 0.05 mol/L KOH pectin fraction (FPK) showed better antioxidant activity.

  16. Wet spinning of PVA composite fibers with a large fraction of multi-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Dengpan Lai

    2015-10-01

    Full Text Available PVA composites fibers with a large fraction of multi-walled carbon nanotubes modified by both covalent and non-covalent functionalization were produced by a wet-spinning process. Model XQ-1 tensile tester, thermogravimetric analysis, scanning electron microscopy, differential scanning calorimetry, and wide-angle X-ray diffraction were used to characterize the properties of PVA/MWNT composite fibers. The TGA results suggested that MWNTs content in composite fibers were ranged from 5.3 wt% to 27.6 wt%. The mechanical properties of PVA/MWNT composite fibers were obviously superior to pure PVA fiber. The Young׳s modulus of composite fibers enhanced with increasing the content of MWNTs, and it rised gradually from 6.7 GPa for the pure PVA fiber to 12.8 GPa for the composite fibers with 27.6 wt% MWNTs. Meanwhile, the tensile strength increased gradually from 0.39 GPa for the pure PVA fiber to 0.74 GPa for the composite fibers with 14.4 wt% MWNTs. Nevertheless, the tensile strength of the composite fibers decreased as the MWNTs content up to 27.6 wt%. SEM results indicated that the MWNTs homogeneously dispersed in the composite fibers, however some agglomerates also existed when the content of MWNTs reached 27.6 wt%. DSC results proved strong interfacial interaction between MWNTs and PVA chain, which benefited composite fibers in the efficient stress-transfer. WXAD characterization showed that the orientation of PVA molecules declined from 94.1% to 90.9% with the increasing of MWNTs content. The good dispersibility of MWNTs throughout PVA matrix and efficient stress-transfer between MWNTs and PVA matrix may contributed to significant enhancement in the mechanical properties.

  17. Plant cell walls throughout evolution: towards a molecular understanding of their design principles

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Purbasha; Bosneaga, Elena; Auer, Manfred

    2009-02-16

    Throughout their life, plants typically remain in one location utilizing sunlight for the synthesis of carbohydrates, which serve as their sole source of energy as well as building blocks of a protective extracellular matrix, called the cell wall. During the course of evolution, plants have repeatedly adapted to their respective niche,which is reflected in the changes of their body plan and the specific design of cell walls. Cell walls not only changed throughout evolution but also are constantly remodelled and reconstructed during the development of an individual plant, and in response to environmental stress or pathogen attacks. Carbohydrate-rich cell walls display complex designs, which together with the presence of phenolic polymers constitutes a barrier for microbes, fungi, and animals. Throughout evolution microbes have co-evolved strategies for efficient breakdown of cell walls. Our current understanding of cell walls and their evolutionary changes are limited as our knowledge is mainly derived from biochemical and genetic studies, complemented by a few targeted yet very informative imaging studies. Comprehensive plant cell wall models will aid in the re-design of plant cell walls for the purpose of commercially viable lignocellulosic biofuel production as well as for the timber, textile, and paper industries. Such knowledge will also be of great interest in the context of agriculture and to plant biologists in general. It is expected that detailed plant cell wall models will require integrated correlative multimodal, multiscale imaging and modelling approaches, which are currently underway.

  18. Curved walls: Grain growth, settling, and composition patterns in T Tauri disk dust submlimation fronts

    CERN Document Server

    McClure, M K; Calvet, N; Espaillat, C; Hartmann, L; Sargent, B; Watson, D M; Ingleby, L; Hernandez, J

    2013-01-01

    The dust sublimation walls of disks around T Tauri stars represent a directly observable cross-section through the disk atmosphere and midplane. Their emission properties can probe the grain size distribution and composition of the innermost regions of the disk, where terrestrial planets form. Here we calculate the inner dust sublimation wall properties for four classical T Tauri stars with a narrow range of spectral types and inclination angles and a wide range of mass accretion rates to determine the extent to which the walls are radially curved. Best-fits to the near- and mid-IR excesses are found for curved, 2-layer walls in which the lower layer contains larger, hotter, amorphous pyroxene grains with Mg/(Mg+Fe)=0.6 and the upper layer contains submicron, cooler, mixed amorphous olivine and forsterite grains. As the mass accretion rates decrease from 10^(-8) to 10^(-10) Msol/yr, the maximum grain size in the lower layer decreases from 3 to 0.5 microns. We attribute this to a decrease in fragmentation and ...

  19. Computation of macro-fiber composite integrated thin-walled smart structures

    Science.gov (United States)

    Zhang, S. Q.; Zhang, S. Y.; Chen, M.; Bai, J.; Li, J.

    2016-07-01

    Due to high flexibility, reliability, and strong actuation forces, piezo fiber based composite smart material, macro-fiber composite (MFC), is increasingly applied in various fields for vibration suppression, shape control, and health monitoring. The complexity arrangement of MFC materials makes them difficult in numerical simulations. This paper develops a linear electro-mechanically coupled finite element (FE) model for composite laminated thin-walled smart structures bonded with MFC patches considering arbitrary piezo fiber orientation. Two types of MFCs are considered, namely, MFC-d31 in which the d 31 effect dominates the actuation forces, and MFC-d33 which mainly uses the d 33 effect. The proposed FE model is validated by static analysis of an MFC bonded smart plate.

  20. Magnetic studies of polystyrene/iron-filled multi-wall carbon nanotube composite films

    Science.gov (United States)

    Makarova, T. L.; Zakharchuk, I.; Geydt, P.; Lahderanta, E.; Komlev, A. A.; Zyrianova, A. A.; Kanygin, M. A.; Sedelnikova, O. V.; Suslyaev, V. I.; Bulusheva, L. G.; Okotrub, A. V.

    2016-10-01

    Polystyrene/iron-filled multi-wall carbon nanotube composite films were prepared by solution processing, forge-rolling and stretching methods. Elongated iron carbide nanoparticles formed because of catalytic growth are situated inside the hollow cavity of the nanotubes. Magnetic susceptibility measurements as well as records of isothermal hysteresis loops performed in three perpendicular directions of magnetic field confirmed that the nanotubes have a preferential alignment in the matrix. Strong diamagnetic anisotropy in the composites emerges not only from the MWCNTs but also from the polystyrene matrix. The polymer sticks to the honeycomb lattice through the interaction of the π-orbitals of the phenyl ring and those of the carbon nanotube, contributing to anisotropic diamagnetic response. The contribution of iron nanoparticles to overall magnetic response strongly depends on nanotube concentration in the composite as well as on matrix-filler non-covalent stacking, which influences magnetic interparticle interactions.

  1. Molecular design of strong single-wall carbon nanotube/polyelectrolyte multilayer composites

    Science.gov (United States)

    Mamedov, Arif A.; Kotov, Nicholas A.; Prato, Maurizio; Guldi, Dirk M.; Wicksted, James P.; Hirsch, Andreas

    2002-11-01

    The mechanical failure of hybrid materials made from polymers and single-wall carbon nanotubes (SWNT) is primarily attributed to poor matrix-SWNT connectivity and severe phase segregation. Both problems can be successfully mitigated when the SWNT composite is made following the protocol of layer-by-layer assembly. This deposition technique prevents phase segregation of the polymer/SWNT binary system, and after subsequent crosslinking, the nanometre-scale uniform composite with SWNT loading as high as 50 wt% can be obtained. The free-standing SWNT/polyelectrolyte membranes delaminated from the substrate were found to be exceptionally strong with a tensile strength approaching that of hard ceramics. Because of the lightweight nature of SWNT composites, the prepared free-standing membranes can serve as components for a variety of long-lifetime devices.

  2. Distinct electrical effects of multi-walled carbon nanotubes in two composites

    Science.gov (United States)

    Wang, Leizhi; Wang, Hua; Datta, Timir; Yin, Ming; Tian, Xingyou

    2014-11-01

    The temperature dependent conductivity of multi-walled carbon nanotube film (MWNT) is reported and the different electrical properties of nanotubes in two composites are compared. Due to the disordered structures, our carbon nanotube film displays variable range hopping behavior. While the geometric distributions of carbon nanotubes in the conducting polyaniline (PANI) and insulating polyamide (PA66) are similar, charge carriers transport distinctly. The conductive PANI, following one-dimensional variable range hopping, dominates the electrical properties of MWNT/PANI composites. The effect of MWNTs becomes prominent only at low temperature range. However, the contact junctions composed by adjacent carbon nanotubes, instead of nanotubes themselves or the polymer matrix, determine the electrical properties of MWNT/PA66 composites, showing the fluctuation induced tunneling characteristic.

  3. Principles of bacterial cell-size determination revealed by cell wall synthesis perturbations

    OpenAIRE

    Carolina Tropini; Timothy K. Lee; Jen Hsin; Samantha M. Desmarais; Tristan Ursell; Russell D. Monds; Kerwyn Casey Huang

    2014-01-01

    Although bacterial cell morphology is tightly controlled, the principles of size regulation remain elusive. In Escherichia coli, perturbation of cell-wall synthesis often results in similar morphologies, making it difficult to deconvolve the complex genotype-phenotype relationships underlying morphogenesis. Here we modulated cell width through heterologous expression of sequences encoding the essential enzyme PBP2 and through sublethal treatments with drugs that inhibit PBP2 and the MreB cyto...

  4. CELL-WALL GROWTH AND PROTEIN SECRETION IN FUNGI

    NARCIS (Netherlands)

    SIETSMA, JH; WOSTEN, HAB; WESSELS, JGH

    1995-01-01

    Secretion of proteins is a vital process in fungi. Because hyphal walls form a diffusion barrier for proteins, a mechanism different from diffusion probably exist to transport proteins across the wall. In Schizophyllum commune, evidence has been obtained for synthesis at the hyphal apex of wall comp

  5. A phosphorylated pseudokinase complex controls cell wall synthesis in mycobacteria.

    Science.gov (United States)

    Gee, Christine L; Papavinasasundaram, Kadamba G; Blair, Sloane R; Baer, Christina E; Falick, Arnold M; King, David S; Griffin, Jennifer E; Venghatakrishnan, Harene; Zukauskas, Andrew; Wei, Jun-Rong; Dhiman, Rakesh K; Crick, Dean C; Rubin, Eric J; Sassetti, Christopher M; Alber, Tom

    2012-01-24

    Prokaryotic cell wall biosynthesis is coordinated with cell growth and division, but the mechanisms regulating this dynamic process remain obscure. Here, we describe a phosphorylation-dependent regulatory complex that controls peptidoglycan (PG) biosynthesis in Mycobacterium tuberculosis. We found that PknB, a PG-responsive Ser-Thr protein kinase (STPK), initiates complex assembly by phosphorylating a kinase-like domain in the essential PG biosynthetic protein, MviN. This domain was structurally diverged from active kinases and did not mediate phosphotransfer. Threonine phosphorylation of the pseudokinase domain recruited the FhaA protein through its forkhead-associated (FHA) domain. The crystal structure of this phosphorylated pseudokinase-FHA domain complex revealed the basis of FHA domain recognition, which included unexpected contacts distal to the phosphorylated threonine. Conditional degradation of these proteins in mycobacteria demonstrated that MviN was essential for growth and PG biosynthesis and that FhaA regulated these processes at the cell poles and septum. Controlling this spatially localized PG regulatory complex is only one of several cellular roles ascribed to PknB, suggesting that the capacity to coordinate signaling across multiple processes is an important feature conserved between eukaryotic and prokaryotic STPK networks. PMID:22275220

  6. Wall extensibility: its nature, measurement and relationship to plant cell growth

    Science.gov (United States)

    Cosgrove, D. J.

    1993-01-01

    Expansive growth of plant cells is controlled principally by processes that loosen the wall and enable it to expand irreversibly. The central role of wall relaxation for cell expansion is reviewed. The most common methods for assessing the extension properties of plant cell walls ( wall extensibility') are described, categorized and assessed critically. What emerges are three fundamentally different approaches which test growing cells for their ability (a) to enlarge at different values of turgor, (b) to induce wall relaxation, and (c) to deform elastically or plastically in response to an applied tensile force. Analogous methods with isolated walls are similarly reviewed. The results of these different assays are related to the nature of plant cell growth and pertinent biophysical theory. I argue that the extensibilities' measured by these assays are fundamentally different from one another and that some are more pertinent to growth than others.

  7. DBIO Best Thesis Award: Mechanics, Dynamics, and Organization of the Bacterial Cytoskeleton and Cell Wall

    Science.gov (United States)

    Wang, Siyuan

    2012-02-01

    Bacteria come in a variety of shapes. While the peptidoglycan (PG) cell wall serves as an exoskeleton that defines the static cell shape, the internal bacterial cytoskeleton mediates cell shape by recruiting PG synthesis machinery and thus defining the pattern of cell-wall synthesis. While much is known about the chemistry and biology of the cytoskeleton and cell wall, much of their biophysics, including essential aspects of the functionality, dynamics, and organization, remain unknown. This dissertation aims to elucidate the detailed biophysical mechanisms of cytoskeleton guided wall synthesis. First, I find that the bacterial cytoskeleton MreB contributes nearly as much to the rigidity of an Escherichia coli cell as the cell wall. This conclusion implies that the cytoskeletal polymer MreB applies meaningful force to the cell wall, an idea favored by theoretical modeling of wall growth, and suggests an evolutionary origin of cytoskeleton-governed cell rigidity. Second, I observe that MreB rotates around the long axis of E. coli, and the motion depends on wall synthesis. This is the first discovery of a cell-wall assembly driven molecular motor in bacteria. Third, I prove that both cell-wall synthesis and the PG network have chiral ordering, which is established by the spatial pattern of MreB. This work links the molecular structure of the cytoskeleton and of the cell wall with organismal-scale behavior. Finally, I develop a mathematical model of cytoskeleton-cell membrane interactions, which explains the preferential orientation of different cytoskeleton components in bacteria.

  8. Parameter Sensitivity Analysis on Deformation of Composite Soil-Nailed Wall Using Artificial Neural Networks and Orthogonal Experiment

    OpenAIRE

    Jianbin Hao; Banqiao Wang

    2014-01-01

    Based on the back-propagation algorithm of artificial neural networks (ANNs), this paper establishes an intelligent model, which is used to predict the maximum lateral displacement of composite soil-nailed wall. Some parameters, such as soil cohesive strength, soil friction angle, prestress of anchor cable, soil-nail spacing, soil-nail diameter, soil-nail length, and other factors, are considered in the model. Combined with the in situ test data of composite soil-nail wall reinforcement engi...

  9. Intraspecific variability of cadmium tolerance and accumulation, and cadmium-induced cell wall modifications in the metal hyperaccumulator Arabidopsis halleri.

    Science.gov (United States)

    Meyer, Claire-Lise; Juraniec, Michal; Huguet, Stéphanie; Chaves-Rodriguez, Elena; Salis, Pietro; Isaure, Marie-Pierre; Goormaghtigh, Erik; Verbruggen, Nathalie

    2015-06-01

    Certain molecular mechanisms of Cd tolerance and accumulation have been identified in the model species Arabidopsis halleri, while intraspecific variability of these traits and the mechanisms of shoot detoxification were little addressed. The Cd tolerance and accumulation of metallicolous and non-metallicolous A. halleri populations from different genetic units were tested in controlled conditions. In addition, changes in shoot cell wall composition were investigated using Fourier transform infrared spectroscopy. Indeed, recent works on A. halleri suggest Cd sequestration both inside cells and in the cell wall/apoplast. All A. halleri populations tested were hypertolerant to Cd, and the metallicolous populations were on average the most tolerant. Accumulation was highly variable between and within populations, and populations that were non-accumulators of Cd were identified. The effect of Cd on the cell wall composition was quite similar in the sensitive species A. lyrata and in A. halleri individuals; the pectin/polysaccharide content of cell walls seems to increase after Cd treatment. Nevertheless, the changes induced by Cd were more pronounced in the less tolerant individuals, leading to a correlation between the level of tolerance and the extent of modifications. This work demonstrated that Cd tolerance and accumulation are highly variable traits in A. halleri, suggesting adaptation at the local scale and involvement of various molecular mechanisms. While in non-metallicolous populations drastic modifications of the cell wall occur due to higher Cd toxicity and/or Cd immobilization in this compartment, the increased tolerance of metallicolous populations probably involves other mechanisms such as vacuolar sequestration. PMID:25873677

  10. Effects of Multi-Walled Carbon Nanotubes on The Mechanical Properties of Glass/Polyester Composites

    Directory of Open Access Journals (Sweden)

    M. Mehrdad Shokrieh

    2012-10-01

    Full Text Available Excellent mechanical properties of carbon nanotubes (CNTs make them outstanding candidate reinforcements to enhance mechanical properties of conventional composites. The glass/polyester composites are widely used in many industries and applications. Improving the mechanical properties of such composites with addition of CNTs can increase their applications. In this research, multi-walled carbon nanotube (MWCNT at different weight ratios (0.05, 0.1, 0.3, 0.5 wt.% were added to chopped strand mat (CSM/Polyester composites. Mechanical stirring with the aid of sonication technique were used to achieve a good dispersion state of MWCNTs in the polymeric matrix. The specimens were fabricated by the hand layup method. It is assumed that a high level of dispersion in the preparation stage may lead to better mechanical properties of the nanocomposite. Scanning electron microscopy (SEM was employed to determine the dispersion state of carbon nanotubes in the matrix. Mechanical tests (tensile and flexural were performed in order to evaluate the effects of adding MWCNT on CSM/Polyester composites. The results exhibit improvements in flexural strength while the values of tensile strength do not show significant changes. Although addition of filler at all above ratios increased the flexural strength, introducing only 0.05 wt.% MWCNT into the CSM/Polyester composites enhanced the flexural strength by 45%. Moreover, improvements in Young's and flexural moduli were observed.

  11. Preparation and characterization of magnetic multi-walled carbon nanotubes-poly(L-lactide) composite

    International Nuclear Information System (INIS)

    The composites based on poly(L-lactide) (PLLA) and two kinds of multi-wall carbon nanotubes (Fe3O4/MWCNTs and MWCNTs) were prepared by solution casting. The molecular level interactions, thermal, magnetic, mechanical properties and dispersion of MWCNTs in polymer matrix were investigated by Raman spectroscopy, differential scanning calorimetry (DSC), magnetic property measure system (MPMS), tensile test and scanning electron microscopy (SEM). The results of Raman spectra revealed the doping-type molecular interaction between filler and polymer matrix. Compared to the pure PLLA, the glass transition temperature (Tg) of MWCNTs/PLLA and Fe3O4/MWCNTs/PLLA composites increased from 50 to 51 deg. C and from 50 to 58 deg. C, respectively. The Fe3O4/MWCNTs/PLLA composite was supermagnetic at room temperature. The Young's modulus, elongation rate at break and tensile strength of Fe3O4/MWCNTs/PLLA composite were improved compared to the neat PLLA and MWCNTs/PLLA composite. Fe3O4/MWCNTs were finely dispersed in the PLLA matrix. The results present potential applications for the biodegradable Fe3O4/MWCNTs/PLLA composite in tissue engineer, biomedicine and bone fixation

  12. Reduced Wall Acetylation Proteins Play Vital and Distinct Roles in Cell Wall O-Acetylation in Arabidopsis

    DEFF Research Database (Denmark)

    Manabe, Yuzuki; Verhertbruggen, Yves; Gille, Sascha;

    2013-01-01

    . The quadruple rwa mutant can be completely complemented with the RWA2 protein expressed under 35S promoter, indicating the functional redundancy of the RWA proteins. Nevertheless, the degree of acetylation of xylan, (gluco) mannan, and xyloglucan as well as overall cell wall acetylation is affected differently...

  13. Intraspecific variability of cadmium tolerance and accumulation, and cadmium-induced cell wall modifications in the metal hyperaccumulator Arabidopsis halleri

    OpenAIRE

    Meyer, Claire-Lise; Juraniec, Michal; Huguet, Stéphanie; Chaves-Rodriguez, Elena; Salis, Pietro; Isaure, Marie-Pierre; Goormaghtigh, Erik; Verbruggen, Nathalie

    2015-01-01

    Certain molecular mechanisms of Cd tolerance and accumulation have been identified in the model species Arabidopsis halleri, while intraspecific variability of these traits and the mechanisms of shoot detoxification were little addressed. The Cd tolerance and accumulation of metallicolous and non-metallicolous A. halleri populations from different genetic units were tested in controlled conditions. In addition, changes in shoot cell wall composition were investigated using Fourier transform i...

  14. The surface modifications of multi-walled carbon nanotubes for multi-walled carbon nanotube/poly(ether ether ketone) composites

    Science.gov (United States)

    Cao, Zongshuang; Qiu, Li; Yang, Yongzhen; Chen, Yongkang; Liu, Xuguang

    2015-10-01

    The effects of surface modifications of multi-walled carbon nanotubes (MWCNTs) on the morphology, dynamic mechanical and tribological properties of multi-walled carbon nanotube/poly(ether ether ketone) (MWCNT/PEEK) composites have been investigated. MWCNTs were treated with mixed acids to obtain acid-functionalized MWCNTs. Then the acid-functionalized MWCNTs were modified with ethanolamine (named e-MWCNTs). The MWCNT/PEEK composites were prepared by a solution-blending method. A more homogeneous distribution of e-MWCNTs within the composites was found with scanning electron microscopy. Dynamic mechanical analysis demonstrated a clear increase in the storage modulus of e-MWCNT/PEEK composites because of the improved interfacial adhesion strength between e-MWCNTs and PEEK. Furthermore, the presence of e-MWCNTs caused an enhancement in the glass transition temperature of the composites. Wear tests have shown that the friction coefficient of e-MWCNT/PEEK composites decreased significantly during the test after the running-in period. This suggests that there is an obvious improvement in tribological properties of e-MWCNT/PEEK composites. Overall, the e-MWCNT/PEEK composites have exhibited improved properties and are promising for their applications in industry.

  15. Charge Transport in Carbon Nanotubes-Polymer Composite Photovoltaic Cells

    Directory of Open Access Journals (Sweden)

    Joel Davenas

    2009-06-01

    Full Text Available We investigate the dark and illuminated current density-voltage (J/V characteristics of poly(2-methoxy-5-(2’-ethylhexyloxy1-4-phenylenevinylene (MEH-PPV/single-walled carbon nanotubes (SWNTs composite photovoltaic cells. Using an exponential band tail model, the conduction mechanism has been analysed for polymer only devices and composite devices, in terms of space charge limited current (SCLC conduction mechanism, where we determine the power parameters and the threshold voltages. Elaborated devices for MEH-PPV:SWNTs (1:1 composites showed a photoresponse with an open-circuit voltage Voc of 0.4 V, a short-circuit current density JSC of 1 µA/cm² and a fill factor FF of 43%. We have modelised the organic photovoltaic devices with an equivalent circuit, where we calculated the series and shunt resistances.

  16. Restrictive glycosylphosphatidylinositol anchor synthesis in cwh6/gpi3 yeast cells causes aberrant biogenesis of cell wall proteins.

    OpenAIRE

    Vossen, J.H.; Müller, W. H.; Lipke, P N; Klis, F. M.

    1997-01-01

    We previously reported that the defects in the Saccharomyces cerevisiae cwh6 Calcofluor white-hypersensitive cell wall mutant are caused by a mutation in SPT14/GPI3, a gene involved in glycosylphosphatidylinositol (GPI) anchor biosynthesis. Here we describe the effect of cwh6/spt14/gpi3 on the biogenesis of cell wall proteins. It was found that the release of precursors of cell wall proteins from the endoplasmic reticulum (ER) was retarded. This was accompanied by proliferation of ER structur...

  17. Effect of aluminum closed-cell foam filling on the quasi-static axial crush performance of glass fiber reinforced polyester composite and aluminum/composite hybrid tubes

    OpenAIRE

    Güden, Mustafa; YÜKSEL, Sinan; Taşdemirci, Alper; Tanoğlu, Metin

    2007-01-01

    The effect of Al closed-cell foam filling on the quasi-static crushing behavior of an E-glass woven fabric polyester composite tube and thin-walled Al/polyester composite hybrid tube was experimentally investigated. For comparison, empty Al, empty composite and empty hybrid tubes were also tested. Empty composite and empty hybrid tubes crushed predominantly in progressive crushing mode, without applying any triggering mechanism. Foam filling was found to be ineffective in increasing the crush...

  18. NAC-MYB-based transcriptional regulation of secondary cell wall biosynthesis in land plants

    OpenAIRE

    Nakano, Yoshimi; Yamaguchi, Masatoshi; Endo, Hitoshi; Rejab, Nur Ardiyana; Ohtani, Misato

    2015-01-01

    Plant cells biosynthesize primary cell walls (PCW) in all cells and produce secondary cell walls (SCWs) in specific cell types that conduct water and/or provide mechanical support, such as xylem vessels and fibers. The characteristic mechanical stiffness, chemical recalcitrance, and hydrophobic nature of SCWs result from the organization of SCW-specific biopolymers, i.e., highly ordered cellulose, hemicellulose, and lignin. Synthesis of these SCW-specific biopolymers requires SCW-specific enz...

  19. FINITE ELEMENT ANALYSIS OF THE FATIGUE BEHAVIOR OF WOOD FIBER CELL WALLS

    Directory of Open Access Journals (Sweden)

    Phichit Somboon

    2008-11-01

    Full Text Available The fatigue behavior of the wood fiber cell wall under mechanical treatment in refining was simulated dynamically using a finite element method. The effect of the amplitude and frequency of impacts on the mechanical breakdown of the fiber wall structure was examined. The proposed model of the fiber cell wall was constructed from elementary microfibrils in various orientations embedded in isotropic lignin. The fatigue of the cell wall was simulated under normal refiner mechanical pulping conditions. A cyclic load was applied on the model fiber through a hemispherical grit proposed to be applied on the surface on refiner segments. Changes in the elastic modulus of the cell wall were analyzed to determine the potential for cell wall breakdown. An increase in the amplitude of applied forces and frequency of impacts was found to have a significant influence on the reduction of the elastic modulus of the wall structure. A high frequency of impacts increased the stiffness of the cell wall, but resulted in faster reduction of the elastic modulus. At a lower amplitude of impacts, efficient breakdown of the cell wall using grits was achieved with a high frequency of impacts or a high rotational speed of refiners.

  20. Rapid analysis of Listeria monocytogenes cell wall teichoic acid carbohydrates by ESI-MS/MS.

    Directory of Open Access Journals (Sweden)

    Marcel R Eugster

    Full Text Available We report the application of electrospray ionization (ESI mass spectrometry for compositional characterization of wall teichoic acids (WTA, a major component of gram-positive bacterial cell walls. Tandem mass spectrometry (ESI-MS/MS of purified and chemically hydrolyzed monomeric WTA components provided sufficient information to identify WTA monomers and their specific carbohydrate constituents. A lithium matrix was used for ionization of uncharged WTA monomers, and successfully applied to analyze the WTA molecules of four Listeria strains differing in carbohydrate substitution on a conserved polyribitol-phosphate backbone structure. Carbohydrate residues such as N-acetylglucosamine or rhamnose linked to the WTA could directly be identified by ESI-MS/MS, circumventing the need for quantitative analysis by gas chromatography. The presence of a terminal N-acetylglucosamine residue tethered to the ribitol was confirmed using fluorescently labeled wheat-germ agglutinin. In conclusion, the mass spectrometry method described here will greatly facilitate compositional analysis and characterization of teichoic acids and similar macromolecules from diverse bacterial species, and represents a significant advance in the identification of serovar-specific carbohydrates and sugar molecules on bacteria.

  1. Heat and mass transfers in a concrete wall with composite liner under accidental conditions

    Energy Technology Data Exchange (ETDEWEB)

    Billard, Y.; Shekarchi, M.; Debicki, G. E-mail: Gerard.debicki@insa-lyon.fr; Granger, L.; Chauvel, D

    2004-03-01

    The aim of this work was to study the behaviour of a concrete wall, covered with a composite liner and exposed to accidental conditions leading to high temperatures and pressures on a face of the material. In the laboratory, two practical levels of accidental situations (beyond design) have been considered. Firstly, the 'SC1' scenario (accidental conditions) consisted of a rise from ambient conditions to a saturation point of 160 deg. C, and a pressure of 0.75 MPa in 12 h, using the maximum increase possible with the apparatus. This rise was then followed by cooling, leading to 0.22 MPa and 120 deg. C in 24 h. These conditions were maintained for several days. Secondly, a 'SC2' scenario (severe accident conditions) consisted of a rise to a saturation point of 173 deg. C and a pressure of 1 MPa, these conditions were maintained for 24 h before cooling. A cylindrical specimen of 1.3 m of thickness was used. Thermocouples, pressure taps and moisture gauges were implemented before concreting. These devices provided local information, and were mostly distributed in the first 0.30 m of the concrete. The concrete composition (high performance concrete) was the same as that used for the construction of the CIVAUX 2 nuclear power station. Typical experimental results for the evolution of temperature, pressure and water content as functions of time are shown for the two test conditions. The concrete attached to the back of the composite dried, and a mass transfer was induced towards colder zones in the centre of the specimen. The liner acted as a heat insulator and the pressure acting on the back of the composite remained lower than that applied on the composite. The residual adhesion of the liner to the concrete was measured. Finally, the overall results allowed the comparison of situations where the wall was lined and unlined, during exposure to SC1 and SC2 conditions.

  2. Primary abdominal wall clear cell carcinoma arising from incisional endometriosis

    Institute of Scientific and Technical Information of China (English)

    Burcu Gundogdu; Isin Ureyen; Gunsu Kimyon; Hakan Turan; Nurettin Boran; Gokhan Tulunay; Dilek Bulbul; Taner Turan; M Faruk Kose

    2013-01-01

    A 49 year-old patient with the complaint of a mass located in the caesarean scar was admitted. There was a fixed mass 30í30 mm in diameter with regular contour located at the right corner of the pfannenstiel incision. Computed tomography revealed a (40í50í50) mm solid mass lesion with margins that cannot be distinguished from the uterus, bladder and small intestines and a heterogeneous mass lesion (50í45í55) mm in diameter, located in the right side of the anterior abdominal wall. Cytoreductive surgery including total abdominal hysterectomy and bilateral salpingo-oophorectomy was performed. Final pathology was clear cell carcinoma. Clear cell carcinoma arising from an extraovarian endometriotic focus was diagnosed and the patient received 6 cycles paclitaxel-carboplatin chemotherapy as adjuvant treatment. The patient who was lost to follow-up applied to our clinic 2 years after surgery with a recurrent mass in the left inguinal region. After 3 cycles of chemotherapy, the patient's tumoral mass in the left inguinal region was excised. The result of the pathology was carcinoma metastasis. It is decided that the following treatment of the patient should be palliative radiation therapy. The patient who underwent palliative radiation therapy died of disease after 4 months of the second operation.

  3. Structures tubulaires minces en matériaux composites. Principes de calcul Thin-Walled Composite Tubular Structures. Calculation Method

    Directory of Open Access Journals (Sweden)

    Odru P.

    2006-11-01

    Full Text Available Cet article présente une méthode de calcul des structures composites fibres-résine appliquée aux cas des tubes minces. Outre l'établissement des relations contraintes - déformations généralisées des tubes à partir des caractéristiques des matériaux de base et de leur orientation, on pose les relations permettant de calculer leur comportement et leur dimensionnement sous des charges axisymétriques combinées de traction, pression et flexion. Une méthode simplifiée applicable au cas des composites microfissurés est aussi présentée. On montre ensuite, à travers quelques exemples concrets d'applications, les propriétés intéressantes ou inhabituelles que le matériau permet de conférer aux structures. This article presents a method of calculation of composite structures applied to thin-walled tubes. Starting from the characteristics and orientation of the basic materials, the generalized stress-strain equations of the tubes are determined ; then the relationship allowing the calculation of their design and behavior under combined axisymmetrical loads of tension, pressure and bending are established. A simplified method applicable to microcracked composite materials is also described. Several complete examples of applications illustrate the interesting or unusual properties that this material can impart to structures

  4. Arthritis by autoreactive T cell lines obtained from rats after injection of intestinal bacterial cell wall fragments

    NARCIS (Netherlands)

    I. Klasen (Ina); J. Kool (Jeanette); M.J. Melief; I. Loeve (I.); W.B. van den Berg (Wim); A.J. Severijnen; M.P.H. Hazenberg (Maarten)

    1992-01-01

    markdownabstract__Abstract__ T cell lines (B13, B19) were isolated from the lymph nodes of Lewis rats 12 days after an arthritogenic injection of cell wall fragments of Eubacterium aerofaciens (ECW), a major resident of the human intestinal flora. These cell wall fragments consist of peptidoglycan

  5. Fasciclin-like arabinogalactan proteins: specialization for stem biomechanics and cell wall architecture in Arabidopsis and Eucalyptus.

    Science.gov (United States)

    MacMillan, Colleen P; Mansfield, Shawn D; Stachurski, Zbigniew H; Evans, Rob; Southerton, Simon G

    2010-05-01

    The ancient cell adhesion fasciclin (FAS) domain is found in bacteria, fungi, algae, insects and animals, and occurs in a large family of fasciclin-like arabinogalactan proteins (FLAs) in higher plants. Functional roles for FAS-containing proteins have been determined for insects, algae and vertebrates; however, the biological functions of the various higher-plant FLAs are not clear. Expression of some FLAs has been correlated with the onset of secondary-wall cellulose synthesis in Arabidopsis stems, and also with wood formation in the stems and branches of trees, suggesting a biological role in plant stems. We examined whether FLAs contribute to plant stem biomechanics. Using phylogenetic, transcript abundance and promoter-GUS fusion analyses, we identified a conserved subset of single FAS domain FLAs (group A FLAs) in Eucalyptus and Arabidopsis that have specific and high transcript abundance in stems, particularly in stem cells undergoing secondary-wall deposition, and that the phylogenetic conservation appears to extend to other dicots and monocots. Gene-function analyses revealed that Arabidopsis T-DNA knockout double mutant stems had altered stem biomechanics with reduced tensile strength and a reduced tensile modulus of elasticity, as well as altered cell-wall architecture and composition, with increased cellulose microfibril angle and reduced arabinose, galactose and cellulose content. Using materials engineering concepts, we relate the effects of these FLAs on cell-wall composition with stem biomechanics. Our results suggest that a subset of single FAS domain FLAs contributes to plant stem strength by affecting cellulose deposition, and to the stem modulus of elasticity by affecting the integrity of the cell-wall matrix.

  6. Building and degradation of secondary cell walls: are there common patterns of lamellar assembly of cellulose microfibrils and cell wall delamination?

    Science.gov (United States)

    De Micco, Veronica; Ruel, Katia; Joseleau, Jean-Paul; Aronne, Giovanna

    2010-08-01

    During cell wall formation and degradation, it is possible to detect cellulose microfibrils assembled into thicker and thinner lamellar structures, respectively, following inverse parallel patterns. The aim of this study was to analyse such patterns of microfibril aggregation and cell wall delamination. The thickness of microfibrils and lamellae was measured on digital images of both growing and degrading cell walls viewed by means of transmission electron microscopy. To objectively detect, measure and classify microfibrils and lamellae into thickness classes, a method based on the application of computerized image analysis combined with graphical and statistical methods was developed. The method allowed common classes of microfibrils and lamellae in cell walls to be identified from different origins. During both the formation and degradation of cell walls, a preferential formation of structures with specific thickness was evidenced. The results obtained with the developed method allowed objective analysis of patterns of microfibril aggregation and evidenced a trend of doubling/halving lamellar structures, during cell wall formation/degradation in materials from different origin and which have undergone different treatments. PMID:20532796

  7. Effective permittivity of single-walled carbon nanotube composites: Two-fluid model

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Afshin, E-mail: a.moradi@kut.ac.ir [Department of Engineering Physics, Kermanshah University of Technology, Kermanshah (Iran, Islamic Republic of); Department of Nano Sciences, Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran (Iran, Islamic Republic of); Zangeneh, Hamid Reza; Moghadam, Firoozeh Karimi [Department of Photonics, Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of)

    2015-12-15

    We develop an effective medium theory to obtain effective permittivity of a composite of two-dimensional (2D) aligned single-walled carbon nanotubes. Electronic excitations on each nanotube surface are modeled by an infinitesimally thin layer of a 2D electron gas represented by two interacting fluids, which takes into account different nature of the σ and π electrons. Calculations of both real and imaginary parts of the effective dielectric function of the system are presented, for different values of the filling factor and radius of carbon nanotubes.

  8. Near-infrared fluorescent single walled carbon nanotube-chitosan composite: Interfacial strain transfer efficiency assessment

    Science.gov (United States)

    Mol Menamparambath, Mini; Arabale, Girish; Nikolaev, Pavel; Baik, Seunghyun; Arepalli, Sivaram

    2013-04-01

    Effective load transfer at the single walled carbon nanotube (SWCNT)-polymer interface is most desirable for mechanically reinforced polymer composites. Versatile layer-by-layer assembly technique achieved dispersion and uniform distribution of sodium carboxymethylcellulose (CMC)-solubilized SWCNTs within the polymer matrix. Electrostatic interaction between positively charged chitosan and negatively charged CMC facilitates design of an optically active biocompatible nanocomposite. Interfacial strain transfer efficiency of SWCNT-chitosan nanocomposite was assessed via SWCNT Raman and photoluminescence band shifts under uniaxial strain. Photoluminescence peak shift rates of individual semiconducting SWCNTs were investigated and compared with tight binding model calculations.

  9. Laplace transform solution for heat transfer in composite walls with periodic boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zedan, M.F.; Mujahid, A.M. (King Saud Univ., Riyadh (Saudi Arabia))

    1993-02-01

    An analytic solution was developed for the heat transfer in a composite wall with periodic ambient temperature on one side and a constant-temperature fluid on the other side. A number of test cases with exact solutions showed that the method is accurate in predicting the transient and the steady periodic parts of the response. Computationally, the method is very efficient in the sense that the solution is only obtained at the points(s) of interest and not at all grid points as in finite difference methods. 5 refs., 3 figs.

  10. Effective permittivity of single-walled carbon nanotube composites: Two-fluid model

    International Nuclear Information System (INIS)

    We develop an effective medium theory to obtain effective permittivity of a composite of two-dimensional (2D) aligned single-walled carbon nanotubes. Electronic excitations on each nanotube surface are modeled by an infinitesimally thin layer of a 2D electron gas represented by two interacting fluids, which takes into account different nature of the σ and π electrons. Calculations of both real and imaginary parts of the effective dielectric function of the system are presented, for different values of the filling factor and radius of carbon nanotubes

  11. Metal coated functionalized single-walled carbon nanotubes for composite applications

    Science.gov (United States)

    Zeng, Qiang

    This study is considered as a method for producing multifunctional composite materials by using metals coated Single-walled Carbon Nanotubes (SWCNTs). In this research, various metals (Ni, Cu, Ag) were successfully deposited onto the surface of SWCNTs. It has been found that homogenous dispersion and dense nucleation sites are the necessary conditions to form uniform coatings on SWCNTs. Functionalization has been applied to achieve considerable improvement in the dispersion of purified SWCNTs and creates more nucleation sites for subsequent metal deposition. A three-step electroless plating approach was used and the coating mechanism is described in the paper. The samples were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Raman spectroscopy, fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). Bulk copper/aluminum-SWNT composites were processed by powder metallurgy with wet mixing techniques. Coated SWCNTs were well dispersed in the metal matrix. Cold pressing followed by sintering was applied to control porosity. The relationships between hardness and SWCNTs addition were discussed. Ni-SWCNTs composite coatings were prepared by electro-composite deposition. SWCNTs were suspended in a Ni deposition electrolyte and deposited together with nickel during electrodeposition. SWCNTs concentrations in the coatings were found to be related to the SWCNTs concentration in the solution, current density and agitation rate. The microstructure of the coatings has been examined by electron microscopy. Ni coated SWCNTs were also incorporated into the high temperature Bismaleimide (BMI)/graphite composite to improve Electromagnetic Interference (EMI) shielding and surface conductivity. The vacuum assisted resin transfer molding (VARTM) was used to process these composites. Surface and volume resistivity and EMI shielding effectiveness of the composites

  12. Pectic homogalacturonan masks abundant sets of xyloglucan epitopes in plant cell walls

    Directory of Open Access Journals (Sweden)

    Pedersen Henriette L

    2008-05-01

    Full Text Available Abstract Background Molecular probes are required to detect cell wall polymers in-situ to aid understanding of their cell biology and several studies have shown that cell wall epitopes have restricted occurrences across sections of plant organs indicating that cell wall structure is highly developmentally regulated. Xyloglucan is the major hemicellulose or cross-linking glycan of the primary cell walls of dicotyledons although little is known of its occurrence or functions in relation to cell development and cell wall microstructure. Results Using a neoglycoprotein approach, in which a XXXG heptasaccharide of tamarind seed xyloglucan was coupled to BSA to produce an immunogen, we have generated a rat monoclonal antibody (designated LM15 to the XXXG structural motif of xyloglucans. The specificity of LM15 has been confirmed by the analysis of LM15 binding using glycan microarrays and oligosaccharide hapten inhibition of binding studies. The use of LM15 for the analysis of xyloglucan in the cell walls of tamarind and nasturtium seeds, in which xyloglucan occurs as a storage polysaccharide, indicated that the LM15 xyloglucan epitope occurs throughout the thickened cell walls of the tamarind seed and in the outer regions, adjacent to middle lamellae, of the thickened cell walls of the nasturtium seed. Immunofluorescence analysis of LM15 binding to sections of tobacco and pea stem internodes indicated that the xyloglucan epitope was restricted to a few cell types in these organs. Enzymatic removal of pectic homogalacturonan from equivalent sections resulted in the abundant detection of distinct patterns of the LM15 xyloglucan epitope across these organs and a diversity of occurrences in relation to the cell wall microstructure of a range of cell types. Conclusion These observations support ideas that xyloglucan is associated with pectin in plant cell walls. They also indicate that documented patterns of cell wall epitopes in relation to cell

  13. The effects of functionalized multi-walled carbon nanotube on mechanical properties of multi-walled carbon nanotube/epoxy composites

    Directory of Open Access Journals (Sweden)

    Mehdi Ardjmand

    2015-12-01

    Full Text Available The mechanical properties of the multi-walled carbon nanotube (MWCNT/epoxy composites affected by carboxyl and amino functionalized MWCNT are investigated. Tensile tests of the specimens were carried out to obtain mechanical properties of MWCNT/epoxy composites for various weight-percents (wt % of MWCNTs. In order to properly predict the mechanical properties of MWCNT reinforced epoxy composites, the effect of MWCNTs de bonding is considered through applying a correction factor to a Halpin-Tsai equation. Applicability of the modified model was endorsed by the experimental results.

  14. Single-wall carbon nanotube (SWCNT) functionalized Sn-Ag-Cu lead-free composite solders

    International Nuclear Information System (INIS)

    Sn-3.8Ag-0.7Cu-based composite solders functionalized with single-wall carbon nanotubes (SWCNTs) with various weight proportions ranging from 0.01 to 1 wt% were successfully produced. The microstuctural, melting and mechanical properties of Sn-3.8Ag-0.7Cu-based composite solders were evaluated as a function of different wt% of SWCNT addition. The microstructures of the composite specimens were studied by means of field-emission scanning electron microscope (FE-SEM). It was observed that SWCNTs were homogeneously distributed at the edges of Ag3Sn compounds that are distributed evenly in the β-Sn solder matrix. Energy dispersion X-ray (EDX) analysis method was employed to reveal the presence of the phases existed in the solder composites. The mechanical properties of the composite solders were evaluated by Vickers-microhardness measurements and tensile tests performed at room temperature. The different wt% and addition of SWCNTs to Sn-3.8Ag-0.7Cu produced a dramatic increase in tensile strength, hardness, and better melting characteristics. A slight decrease in elongation to failure was observed. FE-SEM observations of the fracture surface, revealed the overall failure mechanism as the ductile manner of failure

  15. Cell wall growth during elongation and division : one ring to bind them?

    NARCIS (Netherlands)

    Scheffers, Dirk-Jan

    2007-01-01

    The role of the cell division protein FtsZ in bacterial cell wall (CW) synthesis is believed to be restricted to localizing proteins involved in the synthesis of the septal wall. Elsewhere, compelling evidence is provided that in Caulobacter crescentus, FtsZ plays an additional role in CW synthesis

  16. Detection of 2 immunoreactive antigens in the cell wall of Sporothrix brasiliensis and Sporothrix globosa.

    Science.gov (United States)

    Ruiz-Baca, Estela; Hernández-Mendoza, Gustavo; Cuéllar-Cruz, Mayra; Toriello, Conchita; López-Romero, Everardo; Gutiérrez-Sánchez, Gerardo

    2014-07-01

    The cell wall of members of the Sporothrix schenckii complex contains highly antigenic molecules which are potentially useful for the diagnosis and treatment of sporotrichosis. In this study, 2 immunoreactive antigens of 60 (Gp60) and 70 kDa (Gp70) were detected in the cell wall of the yeast morphotypes of Sporothrix brasiliensis and Sporothrix globosa.

  17. CONSTITUTIVE MELANIN IN THE CELL WALL OF THE ETIOLOGIC AGENT OF LOBO'S DISEASE

    Directory of Open Access Journals (Sweden)

    TABORDA Valeria B.A.

    1999-01-01

    Full Text Available Lobo's disease is a chronic granulomatous disease caused by the obligate pathogenic fungus, whose cell walls contain constitutive melanin. In contrast, melanin does not occur in the cell walls of Paracoccidioides brasiliensis when stained by the Fontana-Masson stain.

  18. Consolidated pretreatment and hydrolysis of plant biomass expressing cell wall degrading enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Raab, R. Michael; Zhang, Dongcheng; Bougri, Oleg

    2016-02-02

    Methods for consolidated pretreatment and hydrolysis of genetically engineered plants expressing cell wall degrading enzymes are provided. Expression cassettes and vectors for making transgenic plants are described. Plants engineered to express one or more cell wall degrading enzymes using expression cassettes and vectors of the invention are also provided.

  19. The microwave absorbing properties of SmCo attached single wall carbon nanotube/epoxy composites

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Liming, E-mail: lmyu@shu.edu.cn; Li, Bo; Sheng, Leimei; An, Kang; Zhao, Xinluo, E-mail: xlzhao@shu.edu.cn

    2013-10-25

    Highlights: •The SmCo nanoparticles attached SWCNTs were prepared by dc arc discharge method. •The nano-composite prepared by a rare earth permanent magnet Sm{sub 2}Co{sub 17} as catalyst. •The SmCo attached SWCNT/epoxy composites have an excellent electromagnetic matching characteristics. •The reflection loss and bandwidth below −20 dB of the composite can reach −23.7 dB, 6.2 GHz, respectively. -- Abstract: The SmCo nanoparticles attached single wall carbon nanotubes (SmCo attached SWCNTs) were prepared by hydrogen dc arc discharge method using 2:17 type SmCo permanent powder as catalyst. The SmCo attached SWCNT/epoxy composites with different doping ratios were investigated in the frequency region of 2–18 GHz. The complex permittivity and permeability of the SmCo attached SWCNT/epoxy composites were calculated. The reflection loss properties were simulated by transmission line theory and the microwave absorptive mechanisms were discussed. The results indicate that, due to the better interfacial polarization absorption mechanism of SmCo attached SWCNTs and the electromagnetic (EM) matching of magnetic loss and dielectric loss, the microwave absorption properties of SmCo attached SWCNT/epoxy are evidently improved. When the SmCo attached SWCNTs is doped by 1 wt%, the composite display a larger and wider absorption peak, and the bandwidth of the reflection loss below −20 dB is larger than 6 GHz with the thickness of 3.3 mm. It is expected that the new SmCo attached SWCNT/epoxy composites will be a good microwave absorbing material for the applications in X band, Ku band, or even K band.

  20. Structure of the cell wall of mango after application of ionizing radiation

    International Nuclear Information System (INIS)

    Cells of the mesocarp of mango cultivar Tommy Atkins were analyzed by Transmission Electron Microscope—TEM to evaluate the effects of doses of 0.5 and 1.0 kGy applied immediately after the fruit and after storage for twenty days at a temperature of 12 °C followed by 5 days of simulated marketing at a temperature of 21 °C. No alteration was found in the structure of the cell wall, middle lamella, and plasma membrane of fruits when analyzed immediately after application of doses. The mesocarp cell structure of the cell wall, middle lamella, and the plasma membrane did however undergo changes after storage. Fruits that received a dose of 0.5 kGy displayed slight changes in cell wall structure and slight disintegration of the middle lamella. Fruits that received a dose of 1.0 kGy displayed more severe changes in the structure of the cell wall, greater middle lamella degradation, and displacement of the plasma membrane. - Highlights: ► Mesocarp cells were analyzed by Transmission Electron Microscope—TEM. ► No change in cell wall structure, middle lamella and plasma membrane was found in fruits immediately after irradiation. ► Changes in cell wall structure, middle lamella and plasma membrane happened after storage. ► Fruits subjected to 0.5 kGy showed smaller cell wall change.

  1. Cell wall carbohydrates from fruit pulp of Argania spinosa: structural analysis of pectin and xyloglucan polysaccharides.

    Science.gov (United States)

    Aboughe-Angone, Sophie; Nguema-Ona, Eric; Ghosh, Partha; Lerouge, Patrice; Ishii, Tadashi; Ray, Bimalendu; Driouich, Azeddine

    2008-01-14

    Isolated cell walls of Argania spinosa fruit pulp were fractionated into their polysaccharide constituents and the resulting fractions were analysed for monosaccharide composition and chemical structure. The data reveal the presence of homogalacturonan, rhamnogalacturonan-I (RG-I) and rhamnogalacturonan-II (RG-II) in the pectic fraction. RG-I is abundant and contains high amounts of Ara and Gal, indicative of an important branching in this polysaccharide. RG-II is less abundant than RG-I and exists as a dimer. Structural characterisation of xyloglucan using enzymatic hydrolysis, gas chromatography, MALDI-TOF-MS and methylation analysis shows that XXGG, XXXG, XXLG and XLLG are the major subunit oligosaccharides in the ratio of 0.6:1:1.2:1.6. This finding demonstrates that the major neutral hemicellulosic polysaccharide is a galacto-xyloglucan. In addition, Argania fruit xyloglucan has no XUFG, a novel xyloglucan motif recently discovered in Argania leaf cell walls. Finally, the isolation and analysis of arabinogalactan-proteins showed that Argania fruit pulp is rich in these proteoglycans. PMID:18005949

  2. Enhancement of Palm Oil Extraction Using Cell Wall Degrading Enzyme Formulation

    International Nuclear Information System (INIS)

    In this recent work, application of aqueous enzymatic process to enhance recovery of palm oil was studied. Experiments were carried out to investigate the structural carbohydrate composition of oil palm mesocarp (Elaeis guineensis) and to analyze the effect of different combination of enzymes on the palm oil recovery and degree of digestibility and the respective correlation. The optimum combination of enzymes comprising of Cellic CTec2 (X1), Cellic HTec2 (X2) and Pectinex Ultra SP-L (X3) for Aqueous Enzymatic Oil Extraction Process (AEOEP), were determined using Simplex Lattice mixture design under fixed parameters. Maximum oil recovery of 88 % was achieved with ratio of enzymes at 0.46: 0.34: 0.2 (X1:X2:X3), at enzyme loading of 30 mg protein/ 10 g substrate, substrate loading of 50 % w/v, pH 4.8, and 2 hours of incubation at 50 degree Celsius. The conversion of reducing sugar at corresponding condition was measured to evaluate the effectiveness of enzymes in degrading fruit cell wall releasing trapped oil. Moreover, transmission electron microscopy (TEM) was utilized to indicate the increase in cell wall disintegration leading to higher release of oil with enzymatic treatment. (author)

  3. Clinostation influence on regeneration of cell wall in Solanum Tuberosum L. protoplasts

    Science.gov (United States)

    Nedukha, Elena M.; Sidorov, V. A.; Samoylov, V. M.

    1994-08-01

    Regeneration of cell walls in protoplasts was investigated using light- and electronmicroscopic methods. The protoplasts were isolated from mesophyll of Solanum tuberosum leaves and were cultivated on the horizontal low rotating clinostat (2 rpm) and in control for 10 days. Using a fluorescent method (with Calcofluor white) it was demonstrated that changes in vector gravity results in an regeneration inhibition of cell wall. With electron-microscopical and electro-cytochemical methods (staining with alcianum blue) dynamics of the regeneration of cell walls in protoplasts was studied; carbohydrate matrix of cell walls is deposited at the earliest stages of this process. The influence of microgravity on the cell wall regeneration is discussed in higher plants.

  4. Generation of hydroxyl radical in isolated pea root cell wall, and the role of cell wall-bound peroxidase, Mn-SOD and phenolics in their production.

    Science.gov (United States)

    Kukavica, Biljana; Mojovic, Milos; Vuccinic, Zeljko; Maksimovic, Vuk; Takahama, Umeo; Jovanovic, Sonja Veljovic

    2009-02-01

    The hydroxyl radical produced in the apoplast has been demonstrated to facilitate cell wall loosening during cell elongation. Cell wall-bound peroxidases (PODs) have been implicated in hydroxyl radical formation. For this mechanism, the apoplast or cell walls should contain the electron donors for (i) H(2)O(2) formation from dioxygen; and (ii) the POD-catalyzed reduction of H(2)O(2) to the hydroxyl radical. The aim of the work was to identify the electron donors in these reactions. In this report, hydroxyl radical (.OH) generation in the cell wall isolated from pea roots was detected in the absence of any exogenous reductants, suggesting that the plant cell wall possesses the capacity to generate .OH in situ. Distinct POD and Mn-superoxide dismutase (Mn-SOD) isoforms different from other cellular isoforms were shown by native gel electropho-resis to be preferably bound to the cell walls. Electron paramagnetic resonance (EPR) spectroscopy of cell wall isolates containing the spin-trapping reagent, 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO), was used for detection of and differentiation between .OH and the superoxide radical (O(2)(-).). The data obtained using POD inhibitors confirmed that tightly bound cell wall PODs are involved in DEPMPO/OH adduct formation. A decrease in DEPMPO/OH adduct formation in the presence of H(2)O(2) scavengers demonstrated that this hydroxyl radical was derived from H(2)O(2). During the generation of .OH, the concentration of quinhydrone structures (as detected by EPR spectroscopy) increased, suggesting that the H(2)O(2) required for the formation of .OH in isolated cell walls is produced during the reduction of O(2) by hydroxycinnamic acids. Cell wall isolates in which the proteins have been denaturated (including the endogenous POD and SOD) did not produce .OH. Addition of exogenous H(2)O(2) again induced the production of .OH, and these were shown to originate from the Fenton reaction with tightly bound metal ions

  5. [Transfer of T-DNA from agrobacteria into plant cells through cell walls and membranes].

    Science.gov (United States)

    Chumakov, M I

    2001-01-01

    Discusses probable routes of agrobacterial penetration through the plant integumental tissues, cell wall, and plant cell plasmodesma. Analyzes the contribution of extracellular structures of agrobacteria in penetration through barriers of a plant cell, primary contact (adhesion), and during DNA transfer from bacterial (E. coli, A. tumefaciens) to recipient (bacterial or plant) cells. Discusses the relationship between donor cell adhesion to recipient cell surface and the infectious and conjugation processes. Considers the probable role of piles in conjugative transfer of agrobacterial DNA through membranes of donor and recipient (bacterial and plant) cells. Analyzes the contribution of the plant cell cytoskeleton to T-DNA transfer. Suggests a model of transport of T-DNA-VirD2 complex and VirE2 proteins through independent channels consisting of vir-coded proteins. PMID:11236737

  6. Composite of single walled carbon nanotube and sulfosalicylic acid doped polyaniline: a thermoelectric material

    Science.gov (United States)

    Jana Chatterjee, Mukulika; Banerjee, Dipali; Chatterjee, Krishanu

    2016-08-01

    Nanocomposites containing single walled carbon nanotubes (SWCNTs) and highly ordered polyaniline (PANI) have been synthesized employing an in situ polymerization using different weight percentages of single-walled carbon nanotube (SWCNT) as template and aniline as a reactant. The composites show homogeneously dispersed SWCNTs which are uniformly coated with PANI through a strong interface interaction. Structural characterization shows that the PANI cultivated along the surface of the SWCNTs in an ordered manner during the SWCNT-directed polymerization process. Measurements at room temperature displayed a significant enhancement in both the electrical conductivity and thermoelectric power which could be attributed to the more ordered chain structures of the PANI on SWCNT. As a result, the power factor of the composite is improved which increases with temperature. At the same time, the measured value of thermal conductivity at room temperature being lowest among the reported values, has resulted in best ZT at room temperature. The lowest value of thermal conductivity is attributed to the large phonon scattering due to the introduction of nanointerfaces.

  7. Highly mobile ferroelastic domain walls in compositionally graded ferroelectric thin films.

    Science.gov (United States)

    Agar, J C; Damodaran, A R; Okatan, M B; Kacher, J; Gammer, C; Vasudevan, R K; Pandya, S; Dedon, L R; Mangalam, R V K; Velarde, G A; Jesse, S; Balke, N; Minor, A M; Kalinin, S V; Martin, L W

    2016-05-01

    Domains and domain walls are critical in determining the response of ferroelectrics, and the ability to controllably create, annihilate, or move domains is essential to enable a range of next-generation devices. Whereas electric-field control has been demonstrated for ferroelectric 180° domain walls, similar control of ferroelastic domains has not been achieved. Here, using controlled composition and strain gradients, we demonstrate deterministic control of ferroelastic domains that are rendered highly mobile in a controlled and reversible manner. Through a combination of thin-film growth, transmission-electron-microscopy-based nanobeam diffraction and nanoscale band-excitation switching spectroscopy, we show that strain gradients in compositionally graded PbZr1-xTixO3 heterostructures stabilize needle-like ferroelastic domains that terminate inside the film. These needle-like domains are highly labile in the out-of-plane direction under applied electric fields, producing a locally enhanced piezoresponse. This work demonstrates the efficacy of novel modes of epitaxy in providing new modalities of domain engineering and potential for as-yet-unrealized nanoscale functional devices. PMID:26878312

  8. Dynamic stiffness matrix of thin-walled composite I-beam with symmetric and arbitrary laminations

    Science.gov (United States)

    Kim, Nam-Il; Shin, Dong Ku; Park, Young-Suk

    2008-11-01

    For the spatially coupled free vibration analysis of thin-walled composite I-beam with symmetric and arbitrary laminations, the exact dynamic stiffness matrix based on the solution of the simultaneous ordinary differential equations is presented. For this, a general theory for the vibration analysis of composite beam with arbitrary lamination including the restrained warping torsion is developed by introducing Vlasov's assumption. Next, the equations of motion and force-displacement relationships are derived from the energy principle and the first order of transformed simultaneous differential equations are constructed by using the displacement state vector consisting of 14 displacement parameters. Then explicit expressions for displacement parameters are derived and the exact dynamic stiffness matrix is determined using force-displacement relationships. In addition, the finite-element (FE) procedure based on Hermitian interpolation polynomials is developed. To verify the validity and the accuracy of this study, the numerical solutions are presented and compared with analytical solutions, the results from available references and the FE analysis using the thin-walled Hermitian beam elements. Particular emphasis is given in showing the phenomenon of vibrational mode change, the effects of increase of the modulus and the bending-twisting coupling stiffness for beams with various boundary conditions.

  9. Highly mobile ferroelastic domain walls in compositionally graded ferroelectric thin films

    Science.gov (United States)

    Agar, J. C.; Damodaran, A. R.; Okatan, M. B.; Kacher, J.; Gammer, C.; Vasudevan, R. K.; Pandya, S.; Dedon, L. R.; Mangalam, R. V. K.; Velarde, G. A.; Jesse, S.; Balke, N.; Minor, A. M.; Kalinin, S. V.; Martin, L. W.

    2016-05-01

    Domains and domain walls are critical in determining the response of ferroelectrics, and the ability to controllably create, annihilate, or move domains is essential to enable a range of next-generation devices. Whereas electric-field control has been demonstrated for ferroelectric 180° domain walls, similar control of ferroelastic domains has not been achieved. Here, using controlled composition and strain gradients, we demonstrate deterministic control of ferroelastic domains that are rendered highly mobile in a controlled and reversible manner. Through a combination of thin-film growth, transmission-electron-microscopy-based nanobeam diffraction and nanoscale band-excitation switching spectroscopy, we show that strain gradients in compositionally graded PbZr1-xTixO3 heterostructures stabilize needle-like ferroelastic domains that terminate inside the film. These needle-like domains are highly labile in the out-of-plane direction under applied electric fields, producing a locally enhanced piezoresponse. This work demonstrates the efficacy of novel modes of epitaxy in providing new modalities of domain engineering and potential for as-yet-unrealized nanoscale functional devices.

  10. A new picture of cell wall protein dynamics in elongating cells of Arabidopsis thaliana: Confirmed actors and newcomers

    OpenAIRE

    Jamet Elisabeth; Pont-Lezica Rafael; Borderies Gisèle; Canut Hervé; Irshad Muhammad

    2008-01-01

    Abstract Background Cell elongation in plants requires addition and re-arrangements of cell wall components. Even if some protein families have been shown to play roles in these events, a global picture of proteins present in cell walls of elongating cells is still missing. A proteomic study was performed on etiolated hypocotyls of Arabidopsis used as model of cells undergoing elongation followed by growth arrest within a short time. Results Two developmental stages (active growth and after g...

  11. Single-Wall Carbon Nanotube Anodes for Lithium Cells

    Science.gov (United States)

    Hepp, Aloysius F.; Raffaelle, Ryne; Gennett, Tom; Kumta, Prashant; Maranchi, Jeff; Heben, Mike

    2006-01-01

    In recent experiments, highly purified batches of single-wall carbon nanotubes (SWCNTs) have shown promise as superior alternatives to the graphitic carbon-black anode materials heretofore used in rechargeable thin-film lithium power cells. The basic idea underlying the experiments is that relative to a given mass of graphitic carbon-black anode material, an equal mass of SWCNTs can be expected to have greater lithium-storage and charge/discharge capacities. The reason for this expectation is that whereas the microstructure and nanostructure of a graphitic carbon black is such as to make most of the interior of the material inaccessible for intercalation of lithium, a batch of SWCNTs can be made to have a much more open microstructure and nanostructure, such that most of the interior of the material is accessible for intercalation of lithium. Moreover, the greater accessibility of SWCNT structures can be expected to translate to greater mobilities for ion-exchange processes and, hence, an ability to sustain greater charge and discharge current densities.

  12. Modifications of Saccharomyces pastorianus cell wall polysaccharides with brewing process.

    Science.gov (United States)

    Bastos, Rita; Coelho, Elisabete; Coimbra, Manuel A

    2015-06-25

    The cell wall polysaccharides of brewers spent yeast Saccharomyces pastorianus (BSY) and the inoculum yeast (IY) were studied in order to understand the changes induced by the brewing process. The hot water and alkali extractions performed solubilized mainly mannoproteins, more branched for BSY than those of IY. Also, (31)P solid state NMR showed that the BSY mannoproteins were 3 times more phosphorylated. By electron microscopy it was observed that the final residues of alkali sequential extraction until 4M KOH preserved the yeast three-dimensional structure. The final residues, composed mainly by glucans (92%), showed that the BSY, when compared with IY, contained higher amount of (1→4)-linked Glc (43% for BSY and 16% for IY) and lower (1→3)-linked Glc (17% for BSY and 42% for IY). The enzymatic treatment of final residue showed that both BSY and IY had (α1→4)-linked Glc and (β1→4)-linked Glc, in a 2:1 ratio, showing that S. pastorianus increases their cellulose-like linkages with the brewing process.

  13. The cell wall-targeting antibiotic stimulon of Enterococcus faecalis.

    Directory of Open Access Journals (Sweden)

    Jacqueline Abranches

    Full Text Available Enterococcus faecalis is an opportunistic nosocomial pathogen that is highly resistant to a variety of environmental insults, including an intrinsic tolerance to antimicrobials that target the cell wall (CW. With the goal of determining the CW-stress stimulon of E. faecalis, the global transcriptional profile of E. faecalis OG1RF exposed to ampicillin, bacitracin, cephalotin or vancomycin was obtained via microarrays. Exposure to the β-lactams ampicillin and cephalotin resulted in the fewest transcriptional changes with 50 and 192 genes differentially expressed 60 min after treatment, respectively. On the other hand, treatment with bacitracin or vancomycin for 60 min affected the expression of, respectively, 377 and 297 genes. Despite the differences in the total number of genes affected, all antibiotics induced a very similar gene expression pattern with an overrepresentation of genes encoding hypothetical proteins, followed by genes encoding proteins associated with cell envelope metabolism as well as transport and binding proteins. In particular, all drug treatments, most notably bacitracin and vancomycin, resulted in an apparent metabolic downshift based on the repression of genes involved in translation, energy metabolism, transport and binding. Only 19 genes were up-regulated by all conditions at both the 30 and 60 min time points. Among those 19 genes, 4 genes encoding hypothetical proteins (EF0026, EF0797, EF1533 and EF3245 were inactivated and the respective mutant strains characterized in relation to antibiotic tolerance and virulence in the Galleria mellonella model. The phenotypes obtained for two of these mutants, ΔEF1533 and ΔEF3245, support further characterization of these genes as potential candidates for the development of novel preventive or therapeutic approaches.

  14. pH and electrical actuation of single walled carbon nanotube/chitosan composite fibers

    Science.gov (United States)

    Ozarkar, Sukrut; Jassal, Manjeet; Agrawal, Ashwini K.

    2008-10-01

    In the present study, an attempt has been made to utilize the pH responsive nature of chitosan to produce fibers which can respond to an applied electric voltage. Single walled carbon nanotubes (SWCNTs) have been used for reinforcing the chitosan fibers. But the SWCNTs are associated with their own challenges of aggregation which have been solved in this study by suitable functionalization. Electron microscopy and Raman spectroscopy was used to investigate the dispersions. The functionalized SWCNTs showed improved dispersion in chitosan. The SWCNT/chitosan composite fibers were successfully solution spun and heat-set to give stable fibers of 50 ± 2 µm. The composite fibers exhibited a significant increase in the mechanical properties. The tenacity of the composite fibers reinforced with functionalized SWCNTs increased from 96 to 226 MPa with an increase in SWCNT content from 0 to 0.2 wt%. The strong interaction of carboxylic functional groups of functionalized SWCNTs with the chitosan matrix may be responsible for the improved dispersion and considerable enhancement of the mechanical properties. Further, the stability of the fibers towards the pH switching environment has also been investigated, along with the response to an applied electric voltage. Composite fibers prepared using 0.1 wt% of functionalized carbon nanotubes were observed to exhibit a stable response with high magnitude of strain and high strain rate.

  15. Pressureless sintering and mechanical properties of hydroxyapatite/functionalized multi-walled carbon nanotube composite.

    Science.gov (United States)

    Abden, M J; Afroze, J D; Alam, M S; Bahadur, N M

    2016-10-01

    This work aims to study the optimum sintering conditions of hydroxyapatite/functionalized multi-walled carbon nanotube (HA/f-MWCNT) composite with improved mechanical properties for bone implant applications using a pressureless sintering technique. The carboxyl functional group (COOH) introduced by the acid treatment on the MWCNT surface by which HA molecules are grafted onto the surface of functionalized MWCNT with strong interfacial bonding. The composite exhibits a lower hemolytic rate of 1.27%. The flexible nature of f-MWCNT makes them bend and attached to the HA grains, indicates that f-MWCNT bear significant stress by sharing a portion of the load and it leads to improve their mechanical properties. The maximum Vickers hardness of 3.6GPa is obtained for the HA/f-MWCNT composite sintered at 1100°C, whereas the highest compressive strength of 481.7MPa and fracture toughness of 2.38MPa.m(1/2) achieved after sintering at 1150°C. This study demonstrated that HA/f-MWCNT composite create suitable structures by vacuum pressureless sintering technique to satisfy the mechanical requirements for bone tissues. PMID:27287138

  16. Composite Behavior of Insulated Concrete Sandwich Wall Panels Subjected to Wind Pressure and Suction

    Directory of Open Access Journals (Sweden)

    Insub Choi

    2015-03-01

    Full Text Available A full-scale experimental test was conducted to analyze the composite behavior of insulated concrete sandwich wall panels (ICSWPs subjected to wind pressure and suction. The experimental program was composed of three groups of ICSWP specimens, each with a different type of insulation and number of glass-fiber-reinforced polymer (GFRP shear grids. The degree of composite action of each specimen was analyzed according to the load direction, type of the insulation, and number of GFRP shear grids by comparing the theoretical and experimental values. The failure modes of the ICSWPs were compared to investigate the effect of bonds according to the load direction and type of insulation. Bonds based on insulation absorptiveness were effective to result in the composite behavior of ICSWP under positive loading tests only, while bonds based on insulation surface roughness were effective under both positive and negative loading tests. Therefore, the composite behavior based on surface roughness can be applied to the calculation of the design strength of ICSWPs with continuous GFRP shear connectors.

  17. THERMAL DECOMPOSITION AND FLAMMABILITY OF ACRYLONITRILE-BUTADIENE-STYRENE/MULTI-WALLED CARBON NANOTUBES COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Li-fang Tong; Hai-yun Ma; Zheng-ping Fang

    2008-01-01

    Thermal and flammability properties of acrylonitrile-butadiene-styrene copolymer (ABS) with the addition of multi-walled carbon nanotubes (MWNTs) were studied. ABS/MWNTs composites were prepared via melt blending with the MWNTs content varied from 0.2% to 4.0% by mass. Thermogravimetry results showed that the addition of MWNTs accelerated the degradation of ABS during the whole process under air atmosphere, and both onset and maximum degradation temperature were lower than those of pure ABS. The destabilization effect of MWNTs on the thermal stability of the composites became unobvious under nitrogen, and the addition of MWNTs could improve the maximum degradation temperature. The heat release rate and time of ignition (tign) for the composites reduced greatly with the addition of MWNTs especially when the concentration of nanotubes was higher than 1.0%. The accumulation of carbon nanotubes with a network structure was observed and the char layer became thicker with increasing nanotubes concentration. Results from Raman spectra showed a higher degree of graphitization for the residues of ABS/MWNTs composites.

  18. A comparative study of EMI shielding properties of carbon nanofiber and multi-walled carbon nanotube filled polymer composites.

    Science.gov (United States)

    Yang, Yonglai; Gupta, Mool C; Dudley, Kenneth L; Lawrence, Roland W

    2005-06-01

    Electromagnetic interference shielding properties of carbon nanofiber- and multi-walled carbon nanotube-filled polystyrene composites were investigated in the frequency range of 8.2-12.4 GHz (X-band). It was observed that the shielding effectiveness of composites was frequency independent, and increased with the increase of carbon nanofiber or nanotube loading. At the same filler loading, multi-walled carbon nanotube-filled polystyrene composites exhibited higher shielding effectiveness compared to those filled with carbon nanofibers. In particular, carbon nanotubes were more effective than nanofibers in providing high EMI shielding at low filler loadings. The experimental data showed that the shielding effectiveness of the composite containing 7 wt% carbon nanotubes could reach more than 26 dB, implying that such a composite can be used as a potential electromagnetic interference shielding material. The dominant shielding mechanism of carbon nanotube-filled polystyrene composites was also discussed. PMID:16060155

  19. Identification of the cell wall receptor for Candida nodaensis Killer toxin

    OpenAIRE

    Silva, Sónia Carina; Aguiar, Cristina; Veríssimo, P.; Pires, E.; Lucas, Cândida

    2004-01-01

    Comunicação efectuada no XIV Congresso Nacional de Bioquímica em Vilamoura (Portugal), 2004. The biological action of the K toxins involves a first step in the killing process, which correspond to the adsorption the toxin to the cell wall of sensitive cells. Here we describe the work performed towards the identification of the cell wall receptor for the zymocin under this study. For this purpose, the main cell wall components of the sensitive yeast Pichia guilliermondii were extracted. Th...

  20. Genetic modification of plant cell walls to enhance biomass yield and biofuel production in bioenergy crops.

    Science.gov (United States)

    Wang, Yanting; Fan, Chunfen; Hu, Huizhen; Li, Ying; Sun, Dan; Wang, Youmei; Peng, Liangcai

    2016-01-01

    Plant cell walls represent an enormous biomass resource for the generation of biofuels and chemicals. As lignocellulose property principally determines biomass recalcitrance, the genetic modification of plant cell walls has been posed as a powerful solution. Here, we review recent progress in understanding the effects of distinct cell wall polymers (cellulose, hemicelluloses, lignin, pectin, wall proteins) on the enzymatic digestibility of biomass under various physical and chemical pretreatments in herbaceous grasses, major agronomic crops and fast-growing trees. We also compare the main factors of wall polymer features, including cellulose crystallinity (CrI), hemicellulosic Xyl/Ara ratio, monolignol proportion and uronic acid level. Furthermore, the review presents the main gene candidates, such as CesA, GH9, GH10, GT61, GT43 etc., for potential genetic cell wall modification towards enhancing both biomass yield and enzymatic saccharification in genetic mutants and transgenic plants. Regarding cell wall modification, it proposes a novel groove-like cell wall model that highlights to increase amorphous regions (density and depth) of the native cellulose microfibrils, providing a general strategy for bioenergy crop breeding and biofuel processing technology. PMID:27269671