Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “cell wall composition”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53Linked to original sources
PubMed1998

A dual labelling method for measuring uptake of low molecular weight compounds into the pathogenic yeast Candida albicans.

In contrast to other eukaryotic cells the pathogenic yeast Candida albicans is resistant to many structurally unrelated metabolic inhibitors. Reduced permeability due to the cell wall and/or altered plasma membrane composition is thought to be at least partly responsible for this phenomenon. To study the uptake of low molecular weight compounds into C. albicans we developed a dual labelling method. Intact cells, metabolically inactivated cells, spheroplasts or membrane fragments of C. albicans were incubated with various [14C]-labelled compound in the presence of [3H]-labelled water. After separation of cells and supernatant isotope ratios [3H]/[14C] were determined. Quotients of the isotope ratios from cells and supernatant, called enrichment coefficients, were calculated under all four conditions. The enrichment coefficients indicated whether a compound can enter C. albicans cells, is trapped within the cell wall, is enriched in the lipophilic membrane compartment, is actively accumulated or actively exported by multidrug resistance carriers. We used six structurally unrelated compounds to test our method. We found no evidence for a general impermeability of C. albicans.

Anti-Bacterial Agents↗
PubMed1999

Properties of extracellular polysaccharides of potato ring rot pathogen and corresponding recognition sites of potato cell walls.

The properties of extracellular polysaccharides of the potato ring rot pathogen Clavibacter michiganensis subsp. sepedonicus (Cms) and the corresponding recognition sites isolated from cell walls of potato suspension cultures have been studied. Extracellular polysaccharides of Cms consist of 4-6 components, which differ greatly in molecular mass (from <1 kD to >700 kD), and are capable of formation of associates stabilized by electrostatic interactions in the presence of calcium. Using affinity column chromatography, sites possessing affinity for the total extracellular polysaccharide complex of Cms were isolated from cell walls of suspension cultures of three potato varieties with different resistance to the pathogen. The content of the receptor sites consisting of glycopeptides and sugars for the variety devoid of resistance was 10 times greater than that for the resistant variety. In the receptor fraction for the latter variety, only sugars were found. The molecular masses of the components of the receptor fraction of cell walls were from 39 to 86 kD. Polypeptides in the recognition sites for the resistant variety escaped detection in electrophoretic patterns. Study of the amino acid composition of the receptor sites of cell walls showed that the sites of the resistant variety contained trace amounts of only seven amino acids. In the sites of the receptive variety 14 amino acids were found, the content of polar amino acids being twice as large as that of nonpolar amino acids. Among polar amino acids, glutamine and glycine prevailed, whereas among nonpolar amino acids valine was dominant. We suggest that one of the reasons of variety-specific resistance of potato to Cms is the absence or a low content of the sites revealing the affinity for bacterial extracellular polysaccharides on the plant cell surface.

Actinomycetales↗
PubMed1990

Intestinal flora of patients with rheumatoid arthritis: induction of chronic arthritis in rats by cell wall fragments from isolated Eubacterium aerofaciens strains.

The composition of the obligate anaerobic intestinal flora of patients with rheumatoid arthritis (RA) differed from that of healthy subjects (HS). Total numbers of aerobes as well as anaerobic coccoid rods were found elevated when compared with HS. Eubacterium species were found in all stool samples of both groups; Bifidobacterium species were present in seven (RA) and eight (HS) out of 10 subjects. From the flora of two RA patients and two HS Eubacterium species were isolated and identified. Cell wall fragments from four E. aerofaciens strains (two from RA, two from HS) were tested for arthritis induction in rats. All four strains induced chronic arthritis which was histologically confirmed. We concluded that in the normal intestinal flora of RA patients Eubacterium species are present in high numbers (i.e. greater than 10(9)/g faeces); cell walls from isolated E. aerofaciens strains had arthropathic properties.

Animals↗
PubMed1971

Electron microscopic observations on the structure of the envelopes of mature elementary bodies and developmental reticulate forms of Chlamydia psittaci.

Purified suspensions of Chlamydia psittaci were prepared from L cells. Thin sections of intact elementary bodies and intact developmental reticulate bodies and of their purified envelopes were observed by electron microscopy. In both intact organisms and partially purified envelopes, two membranous structures, each appearing in electron micrographs as two darkly stained layers, were observed. In the elementary body sections, the outer membrane was round, apparently rigid, and was not soluble in 0.5% sodium dodecyl sulfate. The inner layer was irregular in shape and was completely removed by detergent treatment. We interpret these results to indicate that the outer rigid layer of the envelope is the cell wall and the inner layer is the cytoplasmic membrane. When the fragile reticulate body envelopes were similarly studied, the outer cell wall was clearly visible, and some evidence of an inner membrane was seen. After treatment with nucleases and detergent, all evidence of inner or cytoplasmic membrane was removed, but the outer cell wall remained. Thus, it appears that the cell wall of this organism is continuous throughout the growth cycle and that the fragility and lack of rigidity of the reticulate body cell is due to changes in chemical composition or structure of the cell wall.

Cell Membrane↗
PubMed1988

Characterization of root hair cell walls as potential barriers to the infection of plants by rhizobia : the carbohydrate component.

The sugar compositions of root hairs of a variety of plant species were determined. Root hairs of legumes had very similar compositions, whereas those of different families varied widely. Only approximately 50% of the weight of the root hairs of legumes could be accounted for by sugar. Up to 80% of the weight of root hairs from other sources could be accounted for by sugars. Protein made up 5 to 8% of the weight of root hairs of dicots but only 1.3% in corn. Comparison between cell walls from various root cell types within legumes showed that the polysaccharide compositions of root epidermal, root hair, and root cortical cells were very similar. Cotton root hairs were markedly different from walls of mesophyll and epidermal cells of cotyledons from cotton.

Journal Article↗
PubMed1983

Reduced degradability by lysozyme of staphylococcal cell walls after chloramphenicol treatment.

The effectiveness of host defence against staphylococcal infections depends on the capability of phagocytes to degrade the bacterial cell walls. Treatment with bacteriostatic agents like chloramphenicol could cause problems since under these drugs staphylococcal walls will be substantially thickened. This study presents evidence that the additional wall material built in the presence of chloramphenicol could moreover be rendered more resistant to lysosomal enzymes: In vitro at pH 5.6, lysozyme from hen egg-white proved to degrade the chloramphenicol-wall material at a velocity reduced to 20% of that of the normal wall. Thus, during the degradation of chloramphenicol-treated staphylococcal cell walls the phagocytes have to deal not only with a quantitative but also with a qualitative problem. Possible reasons for the reduced degradability as to chloramphenicol-induced alterations of the wall composition as well as to activating effects of lysozyme on cell wall autolysins are discussed in view of microbiological and medical implications.

Cell Wall↗
PubMed1986

Proliferation of human peripheral blood mononuclear cells induced by Candida albicans and its cell wall fractions.

Glutaraldehyde-inactivated cells and cell-wall fractions of Candida albicans were studied for their capacity to induce or inhibit the in-vitro proliferation of human peripheral blood mononuclear cells (PBMC), as measured by 3H-thymidine incorporation. Both the intact cells (CA) and a phosphorylated gluco-mannan-protein complex of the cell wall (GMP), in microgram doses, were strong inducers of PBMC proliferation, with a peak of activity at 6-9 days of culture and varying with the PBMC donor. A significant but much lower proliferation was observed on exposure of PBMC to a low-protein (less than 3% by weight) mannan component (M) of the cell wall. Both a hot-alkali extracted mannan-protein complex (M-alk), comparable to GMP in crude chemical composition, and an alkali-insoluble cell-wall glucan (GG) were inactive. None of the Candida fractions induced a lymphoproliferation of umbilical cord blood cells and all fractions, except GG, were equally effective in binding human anti-Candida antibodies as shown by a sensitive ELISA-inhibition assay. Moreover, a monoclonal antibody against the class II determinant of the HLA complex inhibited PBMC proliferation irrespective of the Candida antigen used. Taken together, the data shows that in inducing lymphoproliferation, Candida fractions act as specific antigens rather than as non-specific mitogens. Use of intact Candida cells and chemically-defined cell-wall components appears preferable to use of undefined antigenic mixtures as stimulators of PBMC proliferation.

Adult↗
PubMed2000

Fermentation of a bacterial cellulose/xylan composite by mixed ruminal microflora: implications for the role of polysaccharide matrix interactions in plant cell wall biodegradability.

Growth of the cellulose-synthesizing bacterium Acetobacter xylinum ATCC 53524 in media supplemented with 5% (w/v) glucose and 0.2% (w/v) of a water-soluble, nearly linear xylan from tobacco stalks resulted in the synthesis of a highly crystalline composite having a xylose/glucose ratio ranging from 0.06 to 0.24. The digestion of one composite (88% cellulose/12% xylan) by mixed ruminal microflora displayed kinetics of gas production similar to those of an unassociated mixture of the two components added in a xylan/cellulose ratio similar to that of the composite. The data suggest that intimate association of xylan and cellulose, as is typically found in secondary plant cell walls, does not inhibit the rate of digestion of the component polysaccharides.

Acetobacter↗
PubMed1966

Chemical and antigenic analysis of the cell walls of Neisseria meningitidis group B.

Vedros, Neylan A. (Naval Medical Research Institute, Bethesda, Md.), and Paul R. Hill. Chemical and antigenic analysis of the cell walls of Neisseria meningitidis group B. J. Bacteriol. 91:1992-1997. 1966.-Cell walls have been isolated from Neisseria meningitidis group B, by rapid freeze-thawing or treatment with sodium deoxycholate. Chemical analysis of the cell walls indicated that the amino acid composition, and content of hexosamines and of lipids, were similar to those reported for Escherichia coli, except for higher concentrations of alanine, methionine, glutamic acid, and phenylalanine. The meningococcal cell walls showed groupspecificity in the complement-fixation test, were nontoxic for rabbits, and in rabbits produced antibodies which protected mice from challenge with the homologous strain.

Alanine↗
PubMed2002

Three-dimensional macroporous calcium phosphate bioceramics with nested chitosan sponges for load-bearing bone implants.

Three-dimensional macroporous calcium phosphate bioceramics embedded with porous chitosan sponges were synthesized to produce composite scaffolds with high mechanical strength and a large surface/volume ratio for load-bearing bone repairing and substitutes. The macroporous calcium phosphate bioceramics with pore diameters of 300 microm to 600 microm were developed using a porogen burnout technique, and the chitosan sponges were formed inside the pores of the bioceramics by first introducing chiosan solution into the pores followed by a freeze-drying process. Our scanning electron microscopy results showed that the pore size of chitosan sponges formed inside the macroporous structure of bioceramics was approximately 100 microm, a structure favorable for bone tissue in-growth. The compressive modulus and yield stress of the composite scaffolds were both greatly improved in comparison with that of HA/beta-TCP scaffolds. The simulated body fluid (SBF) and cell culture experiments were conducted to assess the bioactivity and biocompatibility of the scaffolds. In the SBF tests, a layer of randomly oriented needle-like apatite crystals formed on the scaffold surface after sample immersion in SBF, which suggested that the composite material has good bioactivity. The cell culture experiments showed that MG63 osteoblast cells attached to the composite scaffolds, proliferated on the scaffold surface, and migrated onto the pore walls, indicating good cell biocompatibility of the scaffold. The cell differentiation on the composite scaffolds was evaluated by alkaline phosphatase (ALP) assay. Compared with the control in tissue culture dishes, the cells had almost the same ALP activity on the composite scaffolds during the first 11 days of culture.

Alkaline Phosphatase↗
PubMedDate not supplied

[The cell wall teichoic acids of streptomycetes from the "Streptomyces cyaneus" cluster].

The cell wall anionic polymers of the 13 species of the "Streptomyces cyaneus" cluster have a similar structure and contain beta-glucosylated 1,5-poly(ribitol phosphate) and 1,3-poly(glycerol phosphate). In the degree of glucosylation of the ribitol phosphate units of their teichoic acids, the cluster members can be divided into two groups. The streptomycetes of the first group (S. afghaniensis, S. janthinus, S. purpurascens, S. roseoviolaceus, and S. violatus) are characterized by a very similar structure of their cell walls, completely glucosylated 1,5-poly(ribitol phosphate) chains, and a high degree of DNA homology (67-88%). The cell wall teichoic acids of the second group (S. azureus, S. bellus, S. caelestis, S. coeruleorubidus, S. curacoi, and S. violarus) differ in the degree of beta-glucosylation of their 1,5-poly(ribitol phosphate) chains and have a lower level of DNA homology (54-76%). Two streptomycetes of the cluster (S. cyaneus and S. hawaiiensis) are genetically distant from the other cluster members but have the same composition and structure of the cell wall teichoic acids as the second-group streptomycetes. The data obtained confirm the genetic relatedness of the "S. cyaneus" cluster members and suggest that the structure of the cell wall teichoic acids may serve as one of the taxonomic criteria of the species-level status of streptomycetes.

Cell Wall↗
PubMed1984

Characterization of the cell wall and outer membrane of Rhodopseudomonas capsulata.

Sucrose density gradient centrifugation of cell envelopes of chemotrophically grown cells of Rhodopseudomonas capsulata St. Louis (= ATCC 23782) resulted in the separation of a cytoplasmic membrane from a cell wall fraction (buoyant densities, 1.139 and 1.215 g/cm3, respectively). The cell wall fractions (untreated or Triton extracted) contained peptidoglycan- and lipopolysaccharide-specific components. Their neutral sugar content, mainly rhamnose and galactose, was high (250 and 100 micrograms/mg [dry weight] of material) due to a non-lipopolysaccharide polymer. The fatty acid content was low (less than or equal to 60 micrograms/mg [dry weight] of material), and half of it was contributed by lipopolysaccharide (3-OH-C10:0, C12:1, and 3-oxo-C14:0). The predominant other fatty acid was C18:1. An outer membrane fraction, obtained by lysozyme treatment of the Triton-extracted cell wall, showed essentially the same chemical composition except for almost complete removal of peptidoglycan. Saline extraction (0.9% NaCl, 37 degrees C, 2 h) removed a lipopolysaccharide-protein(-phospholipid?) complex from whole cells of R. capsulata St. Louis. The polypeptide patterns of the cell wall and outer membrane as revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis comprised 20 to 25 different polypeptides (most of them very faint) and were dominated by a single, heat-modifiable major protein (Mr 69,000 after solubilization below 60 degrees C; Mr 33,000 at temperatures above 70 degrees C).

Carbohydrates↗
PubMed1999

Smooth muscle cells and fibroblasts of the coronary arteries derive from epithelial-mesenchymal transformation of the epicardium.

Previous research has revealed that cells contributing to coronary vascular formation are derived from the dorsal mesocardium, however, the fate of these cells during consecutive stages of heart development is still unclear. We have conducted a study regarding the recruitment of vascular components and the subsequent differentiation into mature vessel wall structures with the aid of immunohistochemical markers directed against endothelium, smooth muscle cells, and fibroblasts. The proepicardial organ including an adhering piece of primordial liver of quail embryos (ranging from HH15 to HH18) was transplanted into the pericardial cavity of chicken embryos (ranging from HH15 to HH18). The chicken-quail chimeras (n=16) were harvested from the early stage of endothelial tube formation (HH25) to the late stage of mature vessel wall composition (HH43). Before HH32 endothelial cells have invaded the myocardium to give rise to yet undifferentiated coronary vessels. These endothelial cells are not accompanied by other non-endothelial cells. The superficial epicardial layer changes from a squamous mesothelium into a cuboid epithelium preceding media and adventitia formation. Subsequently, a condensed area of mesenchymal cells delaminates from the cuboidal lining extending toward the vessel plexus. Around the coronary arteries, these mesenchymal cells differentiate into smooth muscle cells or fibroblasts as shown by immunohistochemical markers. We conclude that epithelial-mesenchymal transformation of the epicardial lining delivers the smooth muscle cells and fibroblasts of the coronary arterial vessel wall. Molecules involved in epithelial transformation processes elsewhere in the embryo are also expressed within the subepicardial layer, and are considered to participate in inducing this process.

Actins↗
PubMed2002

Polysaccharide analysis using carbohydrate gel electrophoresis: a method to study plant cell wall polysaccharides and polysaccharide hydrolases.

A method to characterize plant cell wall polysaccharides is presented. The complexity of the polymer structures and the large number of different charged and uncharged monosaccharides that make up plant polysaccharides have previously made analysis technically demanding and laborious. Polysaccharide analysis using carbohydrate gel electrophoresis (PACE) relies on derivatization of reducing ends of sugars and oligosaccharides with a fluorophore, followed by electrophoresis under optimized conditions in polyacrylamide gels. We show that PACE is a sensitive and simple tool for studying the monosaccharide composition of polysaccharides and of cell wall preparations. In combination with specific hydrolases, it can be used to analyze the structure of polysaccharides. Moreover, the specificity and kinetics of the plant polysaccharide hydrolases themselves can be quickly and effectively studied. PACE can detect as little as 500 fmol of monosaccharides and 100 fmol of oligosaccharides, and it is fast and quantitative.

Arabidopsis↗
PubMed2006

Wall ingrowths in epidermal transfer cells of Vicia faba cotyledons are modified primary walls marked by localized accumulations of arabinogalactan proteins.

Despite the importance of transfer cells in enhancing nutrient transport in plants, little is known about how deposition of the complex morphology of their wall ingrowths is regulated. We probed thin sections of mature cotyledon epidermal transfer cells of Vicia faba with affinity probes and antibodies specific to polysaccharides and glycoproteins, to determine the distribution of these components in their walls. Walls of these transfer cells consist of the pre-existing primary wall, a uniformly deposited wall layer and wall ingrowths which are comprised of two regions; an electron-opaque inner region and an electron-translucent outer region. The primary wall reacted strongly with antibodies against esterified pectin, xyloglucan, the side chains of rhamnogalaturonan-1 and a cellulase-gold affinity probe. The electron-opaque inner region of wall ingrowths displayed a similar labeling pattern to that of the primary wall, showing strong cross-reactivity with all antibodies tested, except those reacting against highly de-esterified pectins. The electron-opaque outer layer of developmentally more mature wall ingrowths reacted strongly with anti-callose monoclonal and polyclonal antibodies, but showed no reaction for pectin or xyloglucan antibodies or the cellulase-gold affinity probe. The plasma membrane-wall interface was labeled strongly with anti-arabinogalactan protein (AGP) antibodies, with some AGP-reactive antibodies also labeling the electron-translucent zone. Nascent wall ingrowths were labeled specifically with AGPs but not anti-callose. A reduction in wall ingrowth density was observed when developing transfer cells were exposed to beta-d-glucosyl Yariv reagent compared with controls. Our results indicate that wall ingrowths of transfer cells are primary wall-like in composition and probably require AGPs for localized deposition.

Biological Transport↗
PubMed2004

Modelling the mechanical properties of single suspension-cultured tomato cells.

BACKGROUND AND AIMS: The relationship between composition and structure of plant primary cell walls, and cell mechanical properties is not fully understood, partly because intrinsic properties of walls such as Young's modulus cannot be obtained readily. The aim of this work is to show that Young's modulus of walls of single suspension-cultured tomato cells can be determined by modelling force-deformation data. METHODS: The model simulates the compression of a cell between two flat surfaces, with the cell treated as a liquid-filled sphere with thin compressible walls. The cell wall and membrane were taken to be permeable, but the compression was so fast that water loss could be neglected in the simulations. Force-deformation data were obtained by compressing the cells in micromanipulation experiments. RESULTS: Good fits were obtained between the model and low-strain experimental data, using the modulus and initial inflation of the cell as adjustable parameters. The mean Young's modulus for 2-week-old cells was found to be 2.3 +/- 0.2 GPa at pH 5. This corresponds to an instantaneous bulk modulus of elasticity of approx. 7 MPa, similar to a value found by the pressure probe method. However, Young's modulus is a better parameter, as it should depend only on the composition and structure of the cell wall, not on bulk cell behaviour. This new method has been used to show that Young's modulus of cultured tomato cell walls is at its lowest at pH 4.5, the pH optimum for expansin activity. CONCLUSIONS: The linear elastic model is very suitable for estimating wall Young's modulus from micromanipulation experiments on single tomato cells. This is a powerful method for determining cell wall material properties.

Biomechanical Phenomena↗
PubMed2000

Genes and plant cell walls: a difficult relationship.

Chemical information, carried by genes, is one of several types of information important for the functioning of cells and organisms. While genes govern the two-dimensional flow of information, the cell walls are at the basis of a structural, three-dimensional framework of plant form and growth. Recent data show the walls to be a cellular 'organelle' undergoing dynamic changes in response to a plethora of stimuli. In this review, an integrated approach, rooted in the organismal perspective, is taken to consider the role of cell walls in the biology of plants. First, the complexity of molecular and biochemical events leading to the biosynthesis of wall components is described within the framework of its spatial cellular organisation, and the major regulatory check-points are characterised. Second, cell walls form a structural and functional continuum within the whole plant and thus could be defined in relation to the protoplasts that produce them and in relation to the plant itself. Model systems of suspension-cultured cells are used to reveal the existence of a bidirectional exchange of information between the protoplast and its walls. The 'plasticity' of plant cell reactions, seen in defence responses or in changes in wall composition, to e.g. stress, plant growth regulators or chemical agents as well as the role of cell walls and/or wall components in somatic embryogenesis are also discussed. Third, being a continuum within the plant body, the walls fulfil vital functions in plant growth and development. The examples characterised include the determination of cellular polarity and the plane of cell division, cytokinesis, and the role of plasmodesmata in cell-to-cell communication and the formation of functional symplastic domains. Fourth, the exocellular control of morphogenetic processes is described and the potential of cell walls as determinants or reservoirs of positional information is indicated. Particular emphasis is put on the (bio)chemical signals coming through or derived from cell walls as well as the mechanical properties of the walls. Based on those data, the 'plant body' concept is formulated. The plant is thus treated as a unit filled with intertwining networks: (1) symplastic, (2) the endomembrane system and (3) cytoskeletal, with cell walls providing an architectural scaffolding and communication ports formed within (4) the cytoskeleton-plasma membrane-cell wall continuum.

Cell Communication↗