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Sample records for normal cell wall

  1. Candida albicans Ecm33p Is Important for Normal Cell Wall Architecture and Interactions with Host Cells

    PubMed Central

    Martinez-Lopez, Raquel; Park, Hyunsook; Myers, Carter L.; Gil, Concha; Filler, Scott G.

    2006-01-01

    Candida albicans ECM33 encodes a glycosylphosphatidylinositol-linked cell wall protein that is important for cell wall integrity. It is also critical for normal virulence in the mouse model of hematogenously disseminated candidiasis. To identify potential mechanisms through which Ecm33p contributes to virulence, we investigated the interactions of C. albicans ecm33Δ mutants with endothelial cells and the FaDu oral epithelial cell line in vitro. The growth rate of blastospores of strains containing either one or no intact copies of ECM33 was 50% slower than that of strains containing two intact copies of ECM33. However, all strains germinated at the same rate, forming similar-length hyphae on endothelial cells and oral epithelial cells. Strains containing either one or no intact copies of ECM33 had modestly reduced adherence to both types of host cells, and a markedly reduced capacity to invade and damage these cells. Saccharomyces cerevisiae expressing C. albicans ECM33 did not adhere to or invade epithelial cells, suggesting that Ecm33p by itself does not act as an adhesin or invasin. Examination of ecm33Δ mutants by transmission electron microscopy revealed that the cell wall of these strains had an abnormally electron-dense outer mannoprotein layer, which may represent a compensatory response to reduced cell wall integrity. The hyphae of these mutants also had aberrant surface localization of the adhesin Als1p. Collectively, these results suggest that Ecm33p is required for normal cell wall architecture as well as normal function and expression of cell surface proteins in C. albicans. PMID:16400176

  2. Differential Transcriptional Response in Macrophages Infected with Cell Wall Deficient versus Normal Mycobacterium Tuberculosis

    PubMed Central

    Fu, Yu-Rong; Gao, Kun-Shan; Ji, Rui; Yi, Zheng-Jun

    2015-01-01

    Host-pathogen interactions determine the outcome following infection by mycobacterium tuberculosis (Mtb). Under adverse circumstances, normal Mtb can form cell-wall deficient (CWD) variants within macrophages, which have been considered an adaptive strategy for facilitating bacterial survival inside macrophages. However, the molecular mechanism by which infection of macrophages with different phenotypic Mtb elicits distinct responses of macrophages is not fully understood. To explore the molecular events triggered upon Mtb infection of macrophages, differential transcriptional responses of RAW264.7 cells infected with two forms of Mtb, CWD-Mtb and normal Mtb, were studied by microarray analysis. Some of the differentially regulated genes were confirmed by RT-qPCR in both RAW264.7 cells and primary macrophages. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway was used to analyze functions of differentially expressed genes. Distinct gene expression patterns were observed between CWD-Mtb and normal Mtb group. Mapt was up-regulated, while NOS2 and IL-11 were down-regulated in CWD-Mtb infected RAW264.7 cells and primary macrophages compared with normal Mtb infected ones. Many deregulated genes were found to be related to macrophages activation, immune response, phagosome maturation, autophagy and lipid metabolism. KEGG analysis showed that the differentially expressed genes were mainly involved in MAPK signaling pathway, nitrogen metabolism, cytokine-cytokine receptor interaction and focal adhesion. Taken together, the present study showed that differential macrophage responses were induced by intracellular CWD-Mtb an normal Mtb infection, which suggested that interactions between macrophages and different phenotypic Mtb are very complex. The results provide evidence for further understanding of pathogenesis of CWD-Mtb and may help in improving strategies to eliminate intracellular CWD-Mtb. PMID:25552926

  3. Human cytokine responses induced by Gram-positive cell walls of normal intestinal microbiota

    PubMed Central

    Chen, T; Isomäki, P; Rimpiläinen, M; Toivanen, P

    1999-01-01

    The normal microbiota plays an important role in the health of the host, but little is known of how the human immune system recognizes and responds to Gram-positive indigenous bacteria. We have investigated cytokine responses of peripheral blood mononuclear cells (PBMC) to Gram-positive cell walls (CW) derived from four common intestinal indigenous bacteria, Eubacterium aerofaciens (Eu.a.), Eubacterium limosum(Eu.l.), Lactobacillus casei(L.c.), and Lactobacillus fermentum (L.f.). Our results indicate that Gram-positive CW of the normal intestinal microbiota can induce cytokine responses of the human PBMC. The profile, level and kinetics of these responses are similar to those induced by lipopolysaccharide (LPS) or CW derived from a pathogen, Streptococcus pyogenes (S.p.). Bacterial CW are capable of inducing production of a proinflammatory cytokine, tumour necrosis factor-alpha (TNF-α), and an anti-inflammatory cytokine, IL-10, but not that of IL-4 or interferon-gamma (IFN-γ). Monocytes are the main cell population in PBMC to produce TNF-α and IL-10. Induction of cytokine secretion is serum-dependent; both CD14-dependent and -independent pathways are involved. These findings suggest that the human cytokine responses induced by Gram-positive CW of the normal intestinal microbiota are similar to those induced by LPS or Gram-positive CW of the pathogens. PMID:10540188

  4. Cell wall degradation is required for normal starch mobilisation in barley endosperm

    PubMed Central

    Andriotis, Vasilios M. E.; Rejzek, Martin; Barclay, Elaine; Rugen, Michael D.; Field, Robert A.; Smith, Alison M.

    2016-01-01

    Starch degradation in barley endosperm provides carbon for early seedling growth, but the control of this process is poorly understood. We investigated whether endosperm cell wall degradation is an important determinant of the rate of starch degradation. We identified iminosugar inhibitors of enzymes that degrade the cell wall component arabinoxylan. The iminosugar 1,4-dideoxy-1, 4-imino-l-arabinitol (LAB) inhibits arabinoxylan arabinofuranohydrolase (AXAH) but does not inhibit the main starch-degrading enzymes α- and β-amylase and limit dextrinase. AXAH activity in the endosperm appears soon after the onset of germination and resides in dimers putatively containing two isoforms, AXAH1 and AXAH2. Upon grain imbibition, mobilisation of arabinoxylan and starch spreads across the endosperm from the aleurone towards the crease. The front of arabinoxylan degradation precedes that of starch degradation. Incubation of grains with LAB decreases the rate of loss of both arabinoxylan and starch, and retards the spread of both degradation processes across the endosperm. We propose that starch degradation in the endosperm is dependent on cell wall degradation, which permeabilises the walls and thus permits rapid diffusion of amylolytic enzymes. AXAH may be of particular importance in this respect. These results provide new insights into the mobilization of endosperm reserves to support early seedling growth. PMID:27622597

  5. Cell-to-cell herniae in the arterial wall. I. The pathogenesis of vacuoles in the normal media.

    PubMed Central

    Joris, I.; Majno, G.

    1977-01-01

    Vacuoles were observed by light microscopy in the smooth muscle cells of the media in normal rat arteries. By electron microscopy these vacuoles were limited by two membranes; they usually contained myelin figures, a few organelles (especially mitochondria and microfilaments), and an amorphous background material that varied greatly in density. Morphologic evidence indicates that these structures arise by herniation of one smooth muscle cell into another; it is presumed that herniation occurs during contraction at weak points corresponding to areas where adjacent cells come in close contact. Such cell-to-cell herniae were mostly seen in small arteries (arterioles) with a diameter of 0.4 to 0.2 mm; however, none was found in coronary arteries of this size. This discrepancy suggests that the pathogenesis of cell-to-cell herniae is correlated not only with the caliber of the artery but also with functional demands. (Am J Pathol 87:375-398). Images Figure 9 Figure 1 Figure 10 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 PMID:557903

  6. Ultra-structural organisation of cell wall polymers in normal and tension wood of aspen revealed by polarisation FTIR microspectroscopy.

    PubMed

    Olsson, Anne-Mari; Bjurhager, Ingela; Gerber, Lorenz; Sundberg, Björn; Salmén, Lennart

    2011-06-01

    Polarisation Fourier transform infra-red (FTIR) microspectroscopy was used to characterize the organisation and orientation of wood polymers in normal wood and tension wood from hybrid aspen (Populus tremula × Populus tremuloides). It is shown that both xylan and lignin in normal wood are highly oriented in the fibre wall. Their orientation is parallel with the cellulose microfibrils and hence in the direction of the fibre axis. In tension wood a similar orientation of lignin was found. However, in tension wood absorption peaks normally assigned to xylan exhibited a 90° change in the orientation dependence of the vibrations as compared with normal wood. The molecular origin of these vibrations are not known, but they are abundant enough to mask the orientation dependence of the xylan signal from the S₂ layer in tension wood and could possibly come from other pentose sugars present in, or associated with, the gelatinous layer of tension wood fibres.

  7. The Lamportian cell wall

    SciTech Connect

    Keiliszewski, M.; Lamport, D. )

    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.

  8. The Cell Wall as the Antigenic Site for Antibodies Stimulating Ingestion (MSF) and Inhibition (BIF) of Brucella in Macrophages from Normal and Immune Animals

    PubMed Central

    Ralston, Doris J.; Elberg, S. S.

    1971-01-01

    Following extraction with hot trichloracetic acid and digestion with trypsin, deoxyribonuclease and ribonuclease, cell wall residues of Brucella melitensis strain Rev I contained an antigenic moiety capable of removing antibodies responsible for stimulation of ingestion, inhibition of Brucella growth by macrophages, and agglutination of Brucella. The preparation was dermonecrotic for both normal and immune rabbits and, when injected in oil, stimulated antibody production. The peptidoglycan-containing structure was degraded by egg-white lysozyme and enzymes from normal and immune macrophages with an accompanying loss of dermonecrotic and serumabsorbing capacity. PMID:5582072

  9. Separation and molecular characterization of mycolic acid from the cell wall skeleton of Mycobacterium bovis BCG Tokyo 172 (SMP-105) and BCG substrains by normal-phase high performance liquid chromatography and liquid chromatography/mass spectrometry.

    PubMed

    Uenishi, Yuko; Takii, Takemasa; Yano, Ikuya; Sunagawa, Makoto

    2009-06-01

    Since mycolic acids, the most characteristic major lipid component in mycobacterial cell envelopes, play pivotal roles in the cell surface-based host immune responses, normal-phase HPLC has been developed to quantify and identify mycolic acids of the cell wall skeleton from Mycobacterium bovis BCG Tokyo 172 (SMP-105).

  10. A Near-Wall Reynolds-Stress Closure Without Wall Normals

    NASA Technical Reports Server (NTRS)

    Yuan, S. P.; So, R. M. C.

    1997-01-01

    Turbulent wall-bounded complex flows are commonly encountered in engineering practice and are of considerable interest in a variety of industrial applications. The presence of a wall significantly affects turbulence characteristics. In addition to the wall effects, turbulent wall-bounded flows become more complicated by the presence of additional body forces (e.g. centrifugal force and Coriolis force) and complex geometry. Most near-wall Reynolds stress models are developed from a high-Reynolds-number model which assumes turbulence is homogenous (or quasi-homogenous). Near-wall modifications are proposed to include wall effects in near-wall regions. In this process, wall normals are introduced. Good predictions could be obtained by Reynolds stress models with wall normals. However, ambiguity arises when the models are applied in flows with multiple walls. Many models have been proposed to model turbulent flows. Among them, Reynolds stress models, in which turbulent stresses are obtained by solving the Reynolds stress transport equations, have been proved to be the most successful ones. To apply the Reynolds stress models to wall-bounded flows, near-wall corrections accounting for the wall effects are needed, and the resulting models are called near-wall Reynolds stress models. In most of the existing near-wall models, the near-wall corrections invoke wall normals. These wall-dependent near-wall models are difficult to implement for turbulent flows with complex geometry and may give inaccurate predictions due to the ambiguity of wall normals at corners connecting multiple walls. The objective of this study is to develop a more general and flexible near-wall Reynolds stress model without using any wall-dependent variable for wall-bounded turbulent flows. With the aid of near-wall asymptotic analysis and results of direct numerical simulation, a new near-wall Reynolds stress model (NNWRS) is formulated based on Speziale et al.'s high-Reynolds-stress model with wall

  11. Safranine fluorescent staining of wood cell walls.

    PubMed

    Bond, J; Donaldson, L; Hill, S; Hitchcock, K

    2008-06-01

    Safranine is an azo dye commonly used for plant microscopy, especially as a stain for lignified tissues such as xylem. Safranine fluorescently labels the wood cell wall, producing green/yellow fluorescence in the secondary cell wall and red/orange fluorescence in the middle lamella (ML) region. We examined the fluorescence behavior of safranine under blue light excitation using a variety of wood- and fiber-based samples of known composition to interpret the observed color differentiation of different cell wall types. We also examined the basis for the differences in fluorescence emission using spectral confocal microscopy to examine lignin-rich and cellulose-rich cell walls including reaction wood and decayed wood compared to normal wood. Our results indicate that lignin-rich cell walls, such as the ML of tracheids, the secondary wall of compression wood tracheids, and wood decayed by brown rot, tend to fluoresce red or orange, while cellulose-rich cell walls such as resin canals, wood decayed by white rot, cotton fibers and the G-layer of tension wood fibers, tend to fluoresce green/yellow. This variation in fluorescence emission seems to be due to factors including an emission shift toward red wavelengths combined with dye quenching at shorter wavelengths in regions with high lignin content. Safranine fluorescence provides a useful way to differentiate lignin-rich and cellulose-rich cell walls without counterstaining as required for bright field microscopy.

  12. Endoplasmic reticulum alpha-glycosidases of Candida albicans are required for N glycosylation, cell wall integrity, and normal host-fungus interaction.

    PubMed

    Mora-Montes, Héctor M; Bates, Steven; Netea, Mihai G; Díaz-Jiménez, Diana F; López-Romero, Everardo; Zinker, Samuel; Ponce-Noyola, Patricia; Kullberg, Bart Jan; Brown, Alistair J P; Odds, Frank C; Flores-Carreón, Arturo; Gow, Neil A R

    2007-12-01

    The cell surface of Candida albicans is enriched in highly glycosylated mannoproteins that are involved in the interaction with the host tissues. N glycosylation is a posttranslational modification that is initiated in the endoplasmic reticulum (ER), where the Glc(3)Man(9)GlcNAc(2) N-glycan is processed by alpha-glucosidases I and II and alpha1,2-mannosidase to generate Man(8)GlcNAc(2). This N-oligosaccharide is then elaborated in the Golgi to form N-glycans with highly branched outer chains rich in mannose. In Saccharomyces cerevisiae, CWH41, ROT2, and MNS1 encode for alpha-glucosidase I, alpha-glucosidase II catalytic subunit, and alpha1,2-mannosidase, respectively. We disrupted the C. albicans CWH41, ROT2, and MNS1 homologs to determine the importance of N-oligosaccharide processing on the N-glycan outer-chain elongation and the host-fungus interaction. Yeast cells of Cacwh41Delta, Carot2Delta, and Camns1Delta null mutants tended to aggregate, displayed reduced growth rates, had a lower content of cell wall phosphomannan and other changes in cell wall composition, underglycosylated beta-N-acetylhexosaminidase, and had a constitutively activated PKC-Mkc1 cell wall integrity pathway. They were also attenuated in virulence in a murine model of systemic infection and stimulated an altered pro- and anti-inflammatory cytokine profile from human monocytes. Therefore, N-oligosaccharide processing by ER glycosidases is required for cell wall integrity and for host-fungus interactions.

  13. Normal Untreated Jurkat Cells

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Biomedical research offers hope for a variety of medical problems, from diabetes to the replacement of damaged bone and tissues. Bioreactors, which are used to grow cells and tissue cultures, play a major role in such research and production efforts. The objective of the research was to define a way to differentiate between effects due to microgravity and those due to possible stress from non-optimal spaceflight conditions. These Jurkat cells, a human acute T-cell leukemia was obtained to evaluate three types of potential experimental stressors: a) Temperature elevation; b) Serum starvation; and c) Centrifugal force. The data from previous spaceflight experiments showed that actin filaments and cell shape are significantly different for the control. These normal cells serve as the baseline for future spaceflight experiments.

  14. A Near-Wall Reynolds-Stress Closure without Wall Normals

    NASA Technical Reports Server (NTRS)

    Yuan, S. P.; So, R. M. C.

    1997-01-01

    With the aid of near-wall asymptotic analysis and results of direct numerical simulation, a new near-wall Reynolds stress model (NNWRS) is formulated based on the SSG high-Reynolds-stress model with wall-independent near-wall corrections. Only one damping function is used for flows with a wide range of Reynolds numbers to ensure that the near-wall modifications diminish away from the walls. The model is able to reproduce complicated flow phenomena induced by complex geometry, such as flow recirculation, reattachment and boundary-layer redevelopment in backward-facing step flow and secondary flow in three-dimensional square duct flow. In simple flows, including fully developed channel/pipe flow, Couette flow and boundary-layer flow, the wall effects are dominant, and the NNWRS model predicts less degree of turbulent anisotropy in the near-wall region compared with a wall-dependent near-wall Reynolds Stress model (NWRS) developed by So and colleagues. The comparison of the predictions given by the two models rectifies the misconception that the overshooting of skin friction coefficient in backward-facing step flow prevalent in those near-wall, models with wall normal is caused by he use of wall normal.

  15. Plant cell walls to ethanol.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conversion of plant cell walls to ethanol constitutes generation 2 bioethanol production. The process consists of several steps: biomass selection/genetic modification, physiochemical pretreatment, enzymatic saccharification, fermentation, and separation. Ultimately, it is desired to combine as man...

  16. Isolation of the Cell Wall.

    PubMed

    Canut, Hervé; Albenne, Cécile; Jamet, Elisabeth

    2017-01-01

    This chapter describes a method allowing the purification of the cell wall for studying both polysaccharides and proteins. The plant primary cell wall is mainly composed of polysaccharides (90-95 % in mass) and of proteins (5-10 %). At the end of growth, specialized cells may synthesize a lignified secondary wall composed of polysaccharides (about 65 %) and lignin (about 35 %). Due to its composition, the cell wall is the cellular compartment having the highest density and this property is used for its purification. It plays critical roles during plant development and in response to environmental constraints. It is largely used in the food and textile industries as well as for the production of bioenergy. All these characteristics and uses explain why its study as a true cell compartment is of high interest. The proposed method of purification can be used for large amount of material but can also be downscaled to 500 mg of fresh material. Tools for checking the quality of the cell wall preparation, such as protein analysis and microscopy observation, are also provided.

  17. Sporothrix schenckii Cell Wall Peptidorhamnomannans

    PubMed Central

    Lopes-Bezerra, Leila M.

    2011-01-01

    This mini-review article is dedicated to clarifying certain important biochemical aspects of Sporothrix schenckii cell wall peptidorhamnomannans. Cell wall components involved in the host interaction such as antigens as well as a gp70 adhesin are important molecules present on the surface of the yeast parasitic phase. Other structural glycoconjugates present on the fungus cell surface are also described here. Knowledge of the fine structure of carbohydrate epitopes expressed on the surface in both morphological phases of S. schenckii permitted the development of non-invasive immunochemical methods to diagnose human and feline sporotrichosis. PMID:22203817

  18. Mast cells in the human alveolar wall: an electronmicroscopic study.

    PubMed Central

    Fox, B; Bull, T B; Guz, A

    1981-01-01

    Mast cells were identified by electronmicroscopy in the alveolar wall of the lung in 20 subjects (10 normal, 10 abnormal). A quantitative and qualitative study was made of the mast cells. In the normal lung there was an average concentration of 350 mast cells/mm2 of alveolar wall and in the abnormal 523/mm2. Mast cells occupied approximately 1.6-2.1% of the area of the alveolar wall. There was marked variation in the structure of the mast cell granules but no differences between those in the normal and abnormal lungs. There was evidence that constant degranulation of mast cells may be occurring in the lung. The role that alveolar mast cells may play in the vasoconstrictor response to alveolar hypoxia is discussed. It is suggested that the tachypnoea present in asthma may partly be due to release of mediators from sensitised mast cells within the alveolar wall. Images PMID:7328180

  19. Cell wall construction in Saccharomyces cerevisiae.

    PubMed

    Klis, Frans M; Boorsma, Andre; De Groot, Piet W J

    2006-02-01

    In this review, we discuss new insights in cell wall architecture and cell wall construction in the ascomycetous yeast Saccharomyces cerevisiae. Transcriptional profiling studies combined with biochemical work have provided ample evidence that the cell wall is a highly adaptable organelle. In particular, the protein population that is anchored to the stress-bearing polysaccharides of the cell wall, and forms the interface with the outside world, is highly diverse. This diversity is believed to play an important role in adaptation of the cell to environmental conditions, in growth mode and in survival. Cell wall construction is tightly controlled and strictly coordinated with progression of the cell cycle. This is reflected in the usage of specific cell wall proteins during consecutive phases of the cell cycle and in the recent discovery of a cell wall integrity checkpoint. When the cell is challenged with stress conditions that affect the cell wall, a specific transcriptional response is observed that includes the general stress response, the cell wall integrity pathway and the calcineurin pathway. This salvage mechanism includes increased expression of putative cell wall assemblases and some potential cross-linking cell wall proteins, and crucial changes in cell wall architecture. We discuss some more enzymes involved in cell wall construction and also potential inhibitors of these enzymes. Finally, we use both biochemical and genomic data to infer that the architectural principles used by S. cerevisiae to build its cell wall are also used by many other ascomycetous yeasts and also by some mycelial ascomycetous fungi.

  20. Back wall solar cell

    NASA Technical Reports Server (NTRS)

    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.

  1. Rare backflow and extreme wall-normal velocity fluctuations in near-wall turbulence

    NASA Astrophysics Data System (ADS)

    Lenaers, Peter; Li, Qiang; Brethouwer, Geert; Schlatter, Philipp; Örlü, Ramis

    2012-03-01

    Rare negative streamwise velocities and extreme wall-normal velocity fluctuations near the wall are investigated for turbulent channel flow at a series of Reynolds numbers based on friction velocity up to Reτ = 1000. Probability density functions of the wall-shear stress and velocity components are presented as well as joint probability density functions of the velocity components and the pressure. Backflow occurs more often (0.06% at the wall at Reτ = 1000) and further away (up to y+ = 8.5) from the wall for increasing Reynolds number. The regions of backflow are circular with an average diameter, based on ensemble averages, of approximately 20 viscous units independent of Reynolds number. A strong oblique vortex outside the viscous sublayer is found to cause this backflow. Extreme wall-normal velocity events occur also more often for increasing Reynolds number. These extreme fluctuations cause high flatness values near the wall (F(v) = 43 at Reτ = 1000). Positive and negative velocity spikes appear in pairs, located on the two edges of a strong streamwise vortex as documented by Xu et al. [Phys. Fluids 8, 1938 (1996)], 10.1063/1.868973 for Reτ = 180. The spikes are elliptical and orientated in streamwise direction with a typical length of 25 and a typical width of 7.5 viscous units at y+ ≈ 1. The negative spike occurs in a high-speed streak indicating a sweeping motion, while the positive spike is located in between a high and low-speed streak. The joint probability density functions of negative streamwise and extreme wall-normal velocity events show that these events are largely uncorrelated. The majority of both type of events can be found lying underneath a large-scale structure in the outer region with positive sign, which can be understood by considering the more intense velocity fluctuations due to amplitude modulation of the inner layer by the outer layer. Simulations performed at different resolutions give only minor differences. Results from

  2. Catalysts of plant cell wall loosening

    PubMed Central

    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 xyloglucan endotransglycosylase/hydrolase (XTH), and pectin methylesterases, and offer a critical assessment of their wall-loosening activity PMID:26918182

  3. Cell proliferation in normal epidermis

    SciTech Connect

    Weinstein, G.D.; McCullough, J.L.; Ross, P.

    1984-06-01

    A detailed examination of cell proliferation kinetics in normal human epidermis is presented. Using tritiated thymidine with autoradiographic techniques, proliferative and differentiated cell kinetics are defined and interrelated. The proliferative compartment of normal epidermis has a cell cycle duration (Tc) of 311 h derived from 3 components: the germinative labeling index (LI), the duration of DNA synthesis (ts), and the growth fraction (GF). The germinative LI is 2.7% +/- 1.2 and ts is 14 h, the latter obtained from a composite fraction of labeled mitoses curve obtained from 11 normal subjects. The GF obtained from the literature and from human skin xenografts to nude mice is estimated to be 60%. Normal-appearing epidermis from patients with psoriasis appears to have a higher proliferation rate. The mean LI is 4.2% +/- 0.9, approximately 50% greater than in normal epidermis. Absolute cell kinetic values for this tissue, however, cannot yet be calculated for lack of other information on ts and GF. A kinetic model for epidermal cell renewal in normal epidermis is described that interrelates the rate of birth/entry, transit, and/or loss of keratinocytes in the 3 epidermal compartments: proliferative, viable differentiated (stratum malpighii), and stratum corneum. Expected kinetic homeostasis in the epidermis is confirmed by the very similar ''turnover'' rates in each of the compartments that are, respectively, 1246, 1417, and 1490 cells/day/mm2 surface area. The mean epidermal turnover time of the entire tissue is 39 days. The Tc of 311 h in normal cells in 8-fold longer than the psoriatic Tc of 36 h and is necessary for understanding the hyperproliferative pathophysiologic process in psoriasis.

  4. The Structure of Plant Cell Walls

    PubMed Central

    Burke, David; Kaufman, Peter; McNeil, Michael; Albersheim, Peter

    1974-01-01

    The primary cell walls of six suspension-cultured monocots and of a single suspension-cultured gymnosperm have been investigated with the following results: (a) the compositions of all six monocot cell walls are remarkably similar, despite the fact that the cell cultures were derived from diverse tissues; (b) the cell walls of suspension-cultured monocots differ substantially from those of suspension-cultured dicots and from the suspension-cultured gymnosperm; (c) an arabinoxylan is a major component (40% or more by weight) of monocot primary cell walls; (d) mixed β-1,3; β-1,4-glucans were found only in the cell wall preparations of rye grass endosperm cells, and not in the cell walls of any of the other five monocot cell cultures nor in the walls of suspension-cultured Douglas fir cells; (e) the monocot primary cell walls studied contain from 9 to 14% cellulose, 7 to 18% uronic acids, and 7 to 17% protein; (f) hydroxyproline accounts for less than 0.2% of the cell walls of monocots. Similar data on the soluble extracellular polysaccharides secreted by these cells are included. PMID:16658824

  5. Moss cell walls: structure and biosynthesis

    PubMed Central

    Roberts, Alison W.; Roberts, Eric M.; 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 angiosperms encode the same families of cell wall glycosyl transferases, yet, in many cases these families have diversified independently in each lineage. Our understanding of land plant evolution could be enhanced by more complete knowledge of the relationships among glycosyl transferase functional diversification, cell wall structural and biochemical specialization, and the roles of cell walls in plant adaptation. As a foundation for these studies, we review the features of P. patens as an experimental system, analyses of cell wall composition in various moss species, recent studies that elucidate the structure and biosynthesis of cell wall polysaccharides in P. patens, and phylogenetic analysis of P. patens genes potentially involved in cell wall biosynthesis. PMID:22833752

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

    NASA Technical Reports Server (NTRS)

    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.

  7. Secondary cell walls: biosynthesis and manipulation.

    PubMed

    Kumar, Manoj; Campbell, Liam; Turner, Simon

    2016-01-01

    Secondary cell walls (SCWs) are produced by specialized plant cell types, and are particularly important in those cells providing mechanical support or involved in water transport. As the main constituent of plant biomass, secondary cell walls are central to attempts to generate second-generation biofuels. Partly as a consequence of this renewed economic importance, excellent progress has been made in understanding how cell wall components are synthesized. SCWs are largely composed of three main polymers: cellulose, hemicellulose, and lignin. In this review, we will attempt to highlight the most recent progress in understanding the biosynthetic pathways for secondary cell wall components, how these pathways are regulated, and how this knowledge may be exploited to improve cell wall properties that facilitate breakdown without compromising plant growth and productivity. While knowledge of individual components in the pathway has improved dramatically, how they function together to make the final polymers and how these individual polymers are incorporated into the wall remain less well understood.

  8. Biosynthesis: Imaging cell-wall biosynthesis live

    NASA Astrophysics Data System (ADS)

    Bugg, Timothy D. H.

    2013-01-01

    The biosynthesis of peptidoglycan is an important step in bacterial cell division and cell-wall maturation. Now it has been shown that fluorescent D-amino acids can be used to label the peptidoglycan cell wall of living bacteria, providing a new tool to study this important process.

  9. Plant cell walls to ethanol.

    PubMed

    Jordan, Douglas B; Bowman, Michael J; Braker, Jay D; Dien, Bruce S; Hector, Ronald E; Lee, Charles C; Mertens, Jeffrey A; Wagschal, Kurt

    2012-03-01

    Conversion of plant cell walls to ethanol constitutes second generation bioethanol production. The process consists of several steps: biomass selection/genetic modification, physiochemical pretreatment, enzymatic saccharification, fermentation and separation. Ultimately, it is desirable to combine as many of the biochemical steps as possible in a single organism to achieve CBP (consolidated bioprocessing). A commercially ready CBP organism is currently unreported. Production of second generation bioethanol is hindered by economics, particularly in the cost of pretreatment (including waste management and solvent recovery), the cost of saccharification enzymes (particularly exocellulases and endocellulases displaying kcat ~1 s-1 on crystalline cellulose), and the inefficiency of co-fermentation of 5- and 6-carbon monosaccharides (owing in part to redox cofactor imbalances in Saccharomyces cerevisiae).

  10. How do plant cell walls extend?

    NASA Technical Reports Server (NTRS)

    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).

  11. Cell Wall Assembly in Saccharomyces cerevisiae

    PubMed Central

    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 its remodeling in S. cerevisiae. We then review the regulatory dynamics of cell wall assembly, an area where functional genomics offers new insights into the integration of cell wall growth and morphogenesis with a polarized secretory system that is under cell cycle and cell type program controls. PMID:16760306

  12. [The cell wall of Coelastrum (Chlorophycees)].

    PubMed

    Reymond, O

    1975-01-01

    The cell wall of Coelastrum is usually composed of three layers. The outermost layer was studied most extensively. It consists of erect tubules which often bear long bristles whose function may be to stabilize the algae in its enviroment. The cell wall can modify its morphology according to the enviroment.

  13. Accelerating forward genetics for cell wall deconstruction

    PubMed Central

    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 introduction of next-generation sequencing technologies, it is now possible to quickly and efficiently map and clone genes of interest in record time. The combination of a classical genetics approach and cutting edge technology will propel cell wall biology in plants forward into the future. PMID:22685448

  14. Do plant cell walls have a code?

    PubMed

    Tavares, Eveline Q P; Buckeridge, Marcos S

    2015-12-01

    A code is a set of rules that establish correspondence between two worlds, signs (consisting of encrypted information) and meaning (of the decrypted message). A third element, the adaptor, connects both worlds, assigning meaning to a code. We propose that a Glycomic Code exists in plant cell walls where signs are represented by monosaccharides and phenylpropanoids and meaning is cell wall architecture with its highly complex association of polymers. Cell wall biosynthetic mechanisms, structure, architecture and properties are addressed according to Code Biology perspective, focusing on how they oppose to cell wall deconstruction. Cell wall hydrolysis is mainly focused as a mechanism of decryption of the Glycomic Code. Evidence for encoded information in cell wall polymers fine structure is highlighted and the implications of the existence of the Glycomic Code are discussed. Aspects related to fine structure are responsible for polysaccharide packing and polymer-polymer interactions, affecting the final cell wall architecture. The question whether polymers assembly within a wall display similar properties as other biological macromolecules (i.e. proteins, DNA, histones) is addressed, i.e. do they display a code?

  15. Isolation of plant cell wall proteins.

    PubMed

    Jamet, Elisabeth; Boudart, Georges; Borderies, Giséle; Charmont, Stephane; Lafitte, Claude; Rossignol, Michel; Canut, Herve; Pont-Lezica, Rafael

    2008-01-01

    The quality of a proteomic analysis of a cell compartment strongly depends on the reliability of the isolation procedure for the cell compartment of interest. Plant cell walls possess specific drawbacks: (1) the lack of a surrounding membrane may result in the loss of cell wall proteins (CWP) during the isolation procedure; (2) polysaccharide networks of cellulose, hemicelluloses, and pectins form potential traps for contaminants such as intracellular proteins; (3) the presence of proteins interacting in many different ways with the polysaccharide matrix require different procedures to elute them from the cell wall. Three categories of CWP are distinguished: labile proteins that have little or no interactions with cell wall components, weakly bound proteins extractable with salts, and strongly bound proteins. Two alternative protocols are decribed for cell wall proteomics: (1) nondestructive techniques allowing the extraction of labile or weakly bound CWP without damaging the plasma membrane; (2) destructive techniques to isolate cell walls from which weakly or strongly bound CWP can be extracted. These protocols give very low levels of contamination by intracellular proteins. Their application should lead to a realistic view of the cell wall proteome at least for labile and weakly bound CWP extractable by salts.

  16. Cell Wall Assembly in Fucus Zygotes

    PubMed Central

    Quatrano, Ralph S.; Stevens, Patricia T.

    1976-01-01

    Fertilization triggers the assembly of a cell wall around the egg cell of three brown algae, Fucus vesiculosus, F. distichus, and F. inflatus. New polysaccharide polymers are continually being added to the cell wall during the first 24 hours of synchronous embryo development. This wall assembly involves the extracellular deposition of fibrillar material by cytoplasmic vesicles fusing with the plasma membrane. One hour after fertilization a fragmented wall can be isolated free of cytoplasm and contains equal amounts of cellulose and alginic acid with no fucose-containing polymers (fucans) present. Birefringence of the wall caused by oriented cellulose microfibrils is not detected in all zygotes until 4 hours, at which time intact cell walls can be isolated that retain the shape of the zygote. These walls have a relatively low ratio of fucose to xylose and little sulfate when compared to walls from older embryos. When extracts of walls from 4-hour zygotes are subjected to cellulose acetate electrophoresis at pH 7, a single fucan (F1) can be detected. By 12 hours, purified cell walls are composed of fucans containing a relatively high ratio of fucose to xylose and high levels of sulfate, and contain a second fucan (F2) which is electrophoretically distinct from F1. F2 appears to be deposited in only a localized region of the wall, that which elongates to form the rhizoid cell. Throughout wall assembly, the polyuronide block co-polymer alginic acid did not significantly vary its mannuronic (M) to guluronic (G) acid ratio (0.33-0.55) or its block distribution (MG, 54%; GG, 30%; MM, 16%). From 6 to 24 hours of embryo development, the proportion of the major polysaccharide components found in purified walls is stable. Alginic acid is the major polymer and comprises about 60% of the total wall, while cellulose and the fucans each make-up about 20% of the remainder. During the extracellular assembly of this wall, the intracellular levels of the storage glucan laminaran

  17. The cell walls of Chara aspera Willd. (Charophyta) vegetative cells.

    PubMed

    Nyberg, H; Saranpää, P

    1989-01-01

    The ultrastructure of the vegetative cell walls of the charophyte Chara aspera Willd was studied with TEM. Thallus cells, rhizoid bulbil and rhizoidal node cells were investigated. The internodal cells transverse walls contained plasmodesmata. The longitudinal walls of the internodal cells were uniform, fibrillar, with two thin structurally distinct layers with different structure facing the cytoplasm. The outermost layers of internodal, cortical and rhizoid bulbil cells were composed of randomly orientated fibrils. The longitudinal walls of the cortical cells were helicoidal in structure. In the rhizoid bulbil cell walls, six different layers could be distinguished, but their occurrence seemed to depend on the fixation, staining and cutting procedures. A middle lamella and osmophilic deposits were found in the wall between rhizoidal node cells. The cytoplasmic structure of the internodal and cortical cells was not found to differ from other species of Chara. Charasomes were observed only in cortical cells.

  18. Recent advances in plant cell wall proteomics.

    PubMed

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

    2008-02-01

    The plant extracellular matrix contains typical polysaccharides such as cellulose, hemicelluloses, and pectins that interact to form dense interwoven networks. Plant cell walls play crucial roles during development and constitute the first barrier of defense against invading pathogens. Cell wall proteomics has greatly contributed to the description of the protein content of a compartment specific to plants. Around 400 cell wall proteins (CWPs) of Arabidopsis, representing about one fourth of its estimated cell wall proteome, have been described. The main points to note are that: (i) the diversity of enzymes acting on polysaccharides suggests a great plasticity of cell walls; (ii) CWPs such as proteases, polysaccharide hydrolytic enzymes, and lipases may contribute to the generation of signals; (iii) proteins of unknown functions were identified, suggesting new roles for cell walls. Recently, the characterization of PTMs such as N- and O-glycosylations improved our knowledge of CWP structure. The presence of many glycoside hydrolases and proteases suggests a complex regulation of CWPs involving various types of post-translational events. The first 3-D structures to be resolved gave clues about the interactions between CWPs, or between CWPs and polysaccharides. Future work should include: extracting and identifying CWPs still recalcitrant to proteomics, describing the cell wall interactome, improving quantification, and unraveling the roles of each of the CWPs.

  19. Polyphosphorylated fungal cell wall glycopeptides

    SciTech Connect

    Bonetti, S.J.; Black, B.; Gander, J.E.

    1987-05-01

    Penicillium charlesii secretes a 65 kDa peptidophosphogalactomannan (pPGM) containing 10 phosphodiester residues and 10 galactofuranosyl-containing galactin chains attached to a linear mannan; the polysaccharides is attached to a 3 kDa seryl- and threonyl-rich peptide. The authors have now isolated and partially characterized a form of pPGM released from mycelia of P. charlesii treated at 50/sup 0/C for 15, 30, 60 or 120 min. Two- to 3-fold more pPGM was released by heat treatment than is secreted. Crude pPGM, released by heat, was fractionated on DE-52 and was fractionated into two major fractions on the basis of its difference in negative charge. /sup 1/H-decoupled /sup 13/C NMR spectroscopy of these two fractions provided spectra very similar to that of secreted pPGM previously reported from this laboratory. /sup 1/H-decoupled /sup 31/P NMR showed major signals at 1.47, and 0.22 ppm and minor signals at 1.32, 1.15, 1.00, 0.91 and 0.76 ppm. These signals are upfield from phosphomonoesters and are in the region observed for (6-O-phosphorylcholine)- and (6-O-phosphorylethanolamine)-..cap alpha..-D-mannopyranosyl residues which are 0.22 and 0.90 ppm, respectively. These polymers contain 30 phosphodiester residues per molecule of 70 kDa mass compared with 10 phosphodiesters in secreted pPGM. Acid phosphatase and alkaline protease were the only lytic enzymes released by heat treatment. The evidence suggests that much of the pPGM is derived from cell walls; and that the polysaccharide is highly phosphorylated.

  20. Molecular regulation of plant cell wall extensibility

    NASA Technical Reports Server (NTRS)

    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.

  1. Cell wall, cytoskeleton, and cell expansion in higher plants.

    PubMed

    Bashline, Logan; Lei, Lei; Li, Shundai; Gu, Ying

    2014-04-01

    To accommodate two seemingly contradictory biological roles in plant physiology, providing both the rigid structural support of plant cells and the adjustable elasticity needed for cell expansion, the composition of the plant cell wall has evolved to become an intricate network of cellulosic, hemicellulosic, and pectic polysaccharides and protein. Due to its complexity, many aspects of the cell wall influence plant cell expansion, and many new and insightful observations and technologies are forthcoming. The biosynthesis of cell wall polymers and the roles of the variety of proteins involved in polysaccharide synthesis continue to be characterized. The interactions within the cell wall polymer network and the modification of these interactions provide insight into how the plant cell wall provides its dual function. The complex cell wall architecture is controlled and organized in part by the dynamic intracellular cytoskeleton and by diverse trafficking pathways of the cell wall polymers and cell wall-related machinery. Meanwhile, the cell wall is continually influenced by hormonal and integrity sensing stimuli that are perceived by the cell. These many processes cooperate to construct, maintain, and manipulate the intricate plant cell wall--an essential structure for the sustaining of the plant stature, growth, and life.

  2. 2003 Plant Cell Walls Gordon Conference

    SciTech Connect

    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.

  3. Refractive index of plant cell walls

    NASA Technical Reports Server (NTRS)

    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.

  4. Differential scanning calorimetry of plant cell walls

    SciTech Connect

    Lin, Liangshiou; Varner, J.E. ); Yuen, H.K. )

    1991-03-15

    High-sensitivity differential scanning calorimetry has been used to study the phase transition of cell wall preparations of the elongating and mature regions of soybean hypocotyls and of celery epidermis and collenchyma strands. A step-like transition believed to be glass transition was observed in walls isolated from the elongating region of soybean hypocotyls at 52.9C. Addition of 1 mM CaCl{sub 2} to the cell wall preparation increased the transition temperature to 60.8C and greatly reduced the transition magnitude. In walls from the mature region, the transition was small and occurred at a higher temperature (60.1C). Addition of calcium to the mature region cell wall had little effect on the transition. Based on the known interactions between calcium and pectin, the authors propose that calcium affects the glass transition by binding to the polygalacturonate backbone of wall pectin, resulting in a more rigid wall with a smaller transition at a higher temperature. The mature region either has more calcium in the wall or has more methyl-esterified pectin, making it less responsive to added calcium.

  5. Cell wall remodeling under abiotic stress

    PubMed Central

    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 all the peroxidase substrates in the cell wall. If ROS-levels remain high during prolonged stress, OH°-radicals are formed which lead to polymer cleavage. In concert with xyloglucan modifying enzymes and expansins, the resulting cell wall loosening allows further growth of stressed organs. PMID:25709610

  6. Role of cell wall deconstructing enzymes in the proanthocyanidin-cell wall adsorption-desorption phenomena.

    PubMed

    Castro-López, Liliana del Rocío; Gómez-Plaza, Encarna; Ortega-Regules, Ana; Lozada, Daniel; Bautista-Ortín, Ana Belén

    2016-04-01

    The transference of proanthocyanidins from grapes to wine is quite low. This could be due, among other causes, to proanthocyanidins being bound to grape cell wall polysaccharides, which are present in high concentrations in the must. Therefore, the effective extraction of proanthocyanidins from grapes will depend on the ability to disrupt these associations, and, in this respect, enzymes that degrade these polysaccharides could play an important role. The main objective of this work was to test the behavior of proanthocyanidin-cell wall interactions when commercial maceration enzymes are present in the solution. The results showed that cell wall polysaccharides adsorbed a high amount of proanthocyanidins and only a limited quantity of proanthocyanidins could be desorbed from the cell walls after washing with a model solution. The presence of enzymes in the solution reduced the proanthocyanidin-cell wall interaction, probably through the elimination of pectins from the cell wall network.

  7. Cell wall proteins: a new insight through proteomics.

    PubMed

    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-translational modifications have been characterized in cell wall proteins to date? The purpose of this review is to discuss the experimental results obtained to date using proteomics, as well as some of the new questions challenging future research.

  8. Modes of deformation of walled cells.

    PubMed

    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.

  9. Biosynthesis of Bacterial Cell Walls.

    DTIC Science & Technology

    amino acid accumulation level in Lactobacillus plantarum and Streptococcus faecalis despite a normal initial transport rate. In the course of these...biosynthesis of a dipeptide, D-alanylcysteine; A demonstration that a pantothenic acid deficiency renders L. plantarum unusually sensitive to lysozyme digestion...A quantitative description of the lipid constituents of S. faecalis and L. plantarum ; An investigation of the biochemical basis of a marked lytic

  10. Assembly of the Yeast Cell Wall

    PubMed Central

    Cabib, Enrico; Farkas, Vladimir; Kosík, Ondrej; Blanco, Noelia; Arroyo, Javier; McPhie, Peter

    2008-01-01

    The cross-linking of polysaccharides to assemble new cell wall in fungi requires mechanisms by which a preexisting linkage is broken for each new one made, to allow for the absence of free energy sources outside the plasma membrane. Previous work showed that Crh1p and Crh2p, putative transglycosylases, are required for the linkage of chitin to β(1–3)glucose branches of β(1–6)glucan in the cell wall of budding yeast. To explore the linking reaction in vivo and in vitro, we used fluorescent sulforhodamine-linked laminari-oligosaccharides as artificial chitin acceptors. In vivo, fluorescence was detected in bud scars and at a lower level in the cell contour, both being dependent on the CRH genes. The linking reaction was also shown in digitonin-permeabilized cells, with UDP-N-acetylglucosamine as the substrate for nascent chitin production. Both the nucleotide and the Crh proteins were required here. A gas1 mutant that overexpresses Crh1p showed very high fluorescence both in intact and permeabilized cells. In the latter, fluorescence was still incorporated in patches in the absence of UDP-GlcNAc. Isolated cell walls of this strain, when incubated with sulforhodamine-oligosaccharide, also showed Crhp-dependent fluorescence in patches, which were identified as bud scars. In all three systems, binding of the fluorescent material to chitin was verified by chitinase digestion. Moreover, the cell wall reaction was inhibited by chitooligosaccharides. These results demonstrate that the Crh proteins act by transferring chitin chains to β(1–6)glucan, with a newly observed high activity in the bud scar. The importance of transglycosylation for cell wall assembly is thus firmly established. PMID:18694928

  11. Detection of Cardiac Function Abnormality from MRI Images Using Normalized Wall Thickness Temporal Patterns.

    PubMed

    Wael, Mai; Ibrahim, El-Sayed H; Fahmy, Ahmed S

    2016-01-01

    Purpose. To develop a method for identifying abnormal myocardial function based on studying the normalized wall motion pattern during the cardiac cycle. Methods. The temporal pattern of the normalized myocardial wall thickness is used as a feature vector to assess the cardiac wall motion abnormality. Principal component analysis is used to reduce the feature dimensionality and the maximum likelihood method is used to differentiate between normal and abnormal features. The proposed method was applied on a dataset of 27 cases from normal subjects and patients. Results. The developed method achieved 81.5%, 85%, and 88.5% accuracy for identifying abnormal contractility in the basal, midventricular, and apical slices, respectively. Conclusions. A novel feature vector, namely, the normalized wall thickness, has been introduced for detecting myocardial regional wall motion abnormality. The proposed method provides assessment of the regional myocardial contractility for each cardiac segment and slice; therefore, it could be a valuable tool for automatic and fast determination of regional wall motion abnormality from conventional cine MRI images.

  12. Cell wall proteomic of Brachypodium distachyon grains: A focus on cell wall remodeling proteins.

    PubMed

    Francin-Allami, Mathilde; Merah, Kahina; Albenne, Cécile; Rogniaux, Hélène; Pavlovic, Marija; Lollier, Virginie; Sibout, Richard; Guillon, Fabienne; Jamet, Elisabeth; Larré, Colette

    2015-07-01

    Cell walls play key roles during plant development. Following their deposition into the cell wall, polysaccharides are continually remodeled according to the growth stage and stress environment to accommodate cell growth and differentiation. To date, little is known concerning the enzymes involved in cell wall remodeling, especially in gramineous and particularly in the grain during development. Here, we investigated the cell wall proteome of the grain of Brachypodium distachyon. This plant is a suitable model for temperate cereal crops. Among the 601 proteins identified, 299 were predicted to be secreted. These proteins were distributed into eight functional classes; the class of proteins that act on carbohydrates was the most highly represented. Among these proteins, numerous glycoside hydrolases were found. Expansins and peroxidases, which are assumed to be involved in cell wall polysaccharide remodeling, were also identified. Approximately half of the proteins identified in this study were newly discovered in grain and were not identified in the previous proteome analysis conducted using the culms and leaves of B. distachyon. Therefore, the data obtained from all organs of B. distachyon infer a global cell wall proteome consisting of 460 proteins. At present, this is the most extensive cell wall proteome of a monocot species.

  13. Roles of membrane trafficking in plant cell wall dynamics

    PubMed Central

    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 transport of the cell wall components and proteins that are involved in cell wall-related events could be specialized for each cell type, i.e., the machinery for cell wall biogenesis, modification, and maintenance could be transported via different trafficking pathways. In this review, we summarize the recent progress in the current understanding of the roles and mechanisms of membrane trafficking in plant cells and focus on the biogenesis and regulation of the cell wall. PMID:26539200

  14. Genetic and biochemical characterization of the GH72 family of cell wall transglycosylases in Neurospora crassa.

    PubMed

    Ao, Jie; Free, Stephen J

    2017-04-01

    The Neurospora crassa genome encodes five GH72 family transglycosylases, and four of these enzymes (GEL-1, GEL-2, GEL-3 and GEL-5) have been found to be present in the cell wall proteome. We carried out an extensive genetic analysis on the role of these four transglycosylases in cell wall biogenesis and demonstrated that the transglycosylases are required for the formation of a normal cell wall. As suggested by the proteomic analysis, we found that multiple transglycosylases were being expressed in N. crassa cells and that different combinations of the enzymes are required in different cell types. The combination of GEL-1, GEL-2 and GEL-5 is required for the growth of vegetative hyphae, while the GEL-1, GEL-2, GEL-3 combination is needed for the production of aerial hyphae and conidia. Our data demonstrates that the enzymes are redundant with partially overlapping enzymatic activities, which provides the fungus with a robust cell wall biosynthetic system. Characterization of the transglycosylase-deficient mutants demonstrated that the incorporation of cell wall proteins was severely compromised. Interestingly, we found that the transglycosylase-deficient mutant cell walls contained more β-1,3-glucan than the wild type cell wall. Our results demonstrate that the GH72 transglycosylases are not needed for the incorporation of β-1,3-glucan into the cell wall, but they are required for the incorporation of cell wall glycoprotein into the cell wall.

  15. Reconstitution of a Secondary Cell Wall in a Secondary Cell Wall-Deficient Arabidopsis Mutant

    PubMed Central

    Sakamoto, Shingo; Mitsuda, Nobutaka

    2015-01-01

    The secondary cell wall constitutes a rigid frame of cells in plant tissues where rigidity is required. Deposition of the secondary cell wall in fiber cells contributes to the production of wood in woody plants. The secondary cell wall is assembled through co-operative activities of many enzymes, and their gene expression is precisely regulated by a pyramidal cascade of transcription factors. Deposition of a transmuted secondary cell wall in empty fiber cells by expressing selected gene(s) in this cascade has not been attempted previously. In this proof-of-concept study, we expressed chimeric activators of 24 transcription factors that are preferentially expressed in the stem, in empty fiber cells of the Arabidopsis nst1-1 nst3-1 double mutant, which lacks a secondary cell wall in fiber cells, under the control of the NST3 promoter. The chimeric activators of MYB46, SND2 and ANAC075, as well as NST3, reconstituted a secondary cell wall with different characteristics from those of the wild type in terms of its composition. The transgenic lines expressing the SND2 or ANAC075 chimeric activator showed increased glucose and xylose, and lower lignin content, whereas the transgenic line expressing the MYB46 chimeric activator showed increased mannose content. The expression profile of downstream genes in each transgenic line was also different from that of the wild type. This study proposed a new screening strategy to identify factors of secondary wall formation and also suggested the potential of the artificially reconstituted secondary cell walls as a novel raw material for production of bioethanol and other chemicals. PMID:25535195

  16. Pulsatile flows and wall-shear stresses in models simulating normal and stenosed aortic arches

    NASA Astrophysics Data System (ADS)

    Huang, Rong Fung; Yang, Ten-Fang; Lan, Y.-K.

    2010-03-01

    Pulsatile aqueous glycerol solution flows in the models simulating normal and stenosed human aortic arches are measured by means of particle image velocimetry. Three transparent models were used: normal, 25% stenosed, and 50% stenosed aortic arches. The Womersley parameter, Dean number, and time-averaged Reynolds number are 17.31, 725, and 1,081, respectively. The Reynolds numbers based on the peak velocities of the normal, 25% stenosed, and 50% stenosed aortic arches are 2,484, 3,456, and 3,931, respectively. The study presents the temporal/spatial evolution processes of the flow pattern, velocity distribution, and wall-shear stress during the systolic and diastolic phases. It is found that the flow pattern evolving in the central plane of normal and stenosed aortic arches exhibits (1) a separation bubble around the inner arch, (2) a recirculation vortex around the outer arch wall upstream of the junction of the brachiocephalic artery, (3) an accelerated main stream around the outer arch wall near the junctions of the left carotid and the left subclavian arteries, and (4) the vortices around the entrances of the three main branches. The study identifies and discusses the reasons for the flow physics’ contribution to the formation of these features. The oscillating wall-shear stress distributions are closely related to the featured flow structures. On the outer wall of normal and slightly stenosed aortas, large wall-shear stresses appear in the regions upstream of the junction of the brachiocephalic artery as well as the corner near the junctions of the left carotid artery and the left subclavian artery. On the inner wall, the largest wall-shear stress appears in the region where the boundary layer separates.

  17. Cell Wall Heterogeneity in Root Development of Arabidopsis

    PubMed Central

    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

  18. KRE5 Suppression Induces Cell Wall Stress and Alternative ER Stress Response Required for Maintaining Cell Wall Integrity in Candida glabrata

    PubMed Central

    Sasaki, Masato; Ito, Fumie; Aoyama, Toshio; Sato-Okamoto, Michiyo; Takahashi-Nakaguchi, Azusa; Chibana, Hiroji; Shibata, Nobuyuki

    2016-01-01

    The maintenance of cell wall integrity in fungi is required for normal cell growth, division, hyphae formation, and antifungal tolerance. We observed that endoplasmic reticulum stress regulated cell wall integrity in Candida glabrata, which possesses uniquely evolved mechanisms for unfolded protein response mechanisms. Tetracycline-mediated suppression of KRE5, which encodes a predicted UDP-glucose:glycoprotein glucosyltransferase localized in the endoplasmic reticulum, significantly increased cell wall chitin content and decreased cell wall β-1,6-glucan content. KRE5 repression induced endoplasmic reticulum stress-related gene expression and MAP kinase pathway activation, including Slt2p and Hog1p phosphorylation, through the cell wall integrity signaling pathway. Moreover, the calcineurin pathway negatively regulated cell wall integrity, but not the reduction of β-1,6-glucan content. These results indicate that KRE5 is required for maintaining both endoplasmic reticulum homeostasis and cell wall integrity, and that the calcineurin pathway acts as a regulator of chitin-glucan balance in the cell wall and as an alternative mediator of endoplasmic reticulum stress in C. glabrata. PMID:27548283

  19. Measuring in vitro extensibility of growing plant cell walls.

    PubMed

    Cosgrove, Daniel J

    2011-01-01

    This article summarizes the theory and practical aspects of measuring cell wall properties by four different extensometer techniques and how the results of these methods relate to the concept and ideal measurement of cell wall extensibility in the context of cell growth. These in vivo techniques are particularly useful for studies of the molecular basis of cell wall extension. Measurements of breaking strength, elastic compliance, and plastic compliance may be informative about changes in cell wall structure, whereas measurements of wall stress relaxation and creep are sensitive to both changes in wall structure and wall-loosening processes, such as those mediated by expansins and some lytic enzymes. A combination of methods is needed to obtain a broader view of cell wall behavior and properties connected with the concept of cell wall extensibility.

  20. Cell wall proteome of pathogenic fungi.

    PubMed

    Karkowska-Kuleta, Justyna; Kozik, Andrzej

    2015-01-01

    A fast development of a wide variety of proteomic techniques supported by mass spectrometry coupled with high performance liquid chromatography has been observed in recent years. It significantly contributes to the progress in research on the cell wall, very important part of the cells of pathogenic fungi. This complicated structure composed of different polysaccharides, proteins, lipids and melanin, plays a key role in interactions with the host during infection. Changes in the set of the surface-exposed proteins under different environmental conditions provide an effective way for pathogens to respond, adapt and survive in the new niches of infection. This work summarizes the current state of knowledge on proteins, studied both qualitatively and quantitatively, and found within the cell wall of fungal pathogens for humans, including Candida albicans, Candida glabrata, Aspergillus fumigatus, Cryptococcus neoformans and other medically important fungi. The described proteomic studies involved the isolation and fractionation of particular sets of proteins of interest with various techniques, often based on differences in their linkages to the polysaccharide scaffold. Furthermore, the proteinaceous contents of extracellular vesicles ("virulence bags") of C. albicans, C. neoformans, Histoplasma capsulatum and Paracoccidioides brasiliensis are compared, because their production can partially explain the problem of non-classical protein secretion by fungi. The role assigned to surface-exposed proteins in pathogenesis of fungal infections is enormously high, thus justifying the need for further investigation of cell wall proteomes.

  1. Celery (Apium graveolens) parenchyma cell walls: cell walls with minimal xyloglucan.

    PubMed

    Thimm, Julian C.; Burritt, David J.; Sims, Ian M.; Newman, Roger H.; Ducker, William A.; Melton, Laurence D.

    2002-10-01

    The primary walls of celery (Apium graveolens L.) parenchyma cells were isolated and their polysaccharide components characterized by glycosyl linkage analysis, cross-polarization magic-angle spinning solid-state 13C nuclear magnetic resonance (CP/MAS 13C NMR) and X-ray diffraction. Glycosyl linkage analysis showed that the cell walls consisted of mainly cellulose (43 mol%) and pectic polysaccharides (51 mol%), comprising rhamnogalacturonan (28 mol%), arabinan (12 mol%) and galactan (11 mol%). The amounts of xyloglucan (2 mol%) and xylan (2 mol%) detected in the cell walls were strikingly low. The small amount of xyloglucan present means that it cannot coat the cellulose microfibrils. Solid-state 13C NMR signals were consistent with the constituents identified by glycosyl linkage analysis and allowed the walls to be divided into three domains, based on the rigidity of the polymers. Cellulose (rigid) and rhamnogalacturonan (semi-mobile) polymers responded to the CP/MAS 13C NMR pulse sequence and were distinguished by differences in proton spin relaxation time constants. The arabinans, the most mobile polymers, responded to single-pulse excitation (SPE), but not CP/MAS 13C NMR. From solid-state 13C NMR of the cell walls the diameter of the crystalline cellulose microfibrils was determined to be approximately 3 nm while X-ray diffraction of the cell walls gave a value for the diameter of approximately 2 nm.

  2. Revealing the structural and functional diversity of plant cell walls.

    PubMed

    Knox, J Paul

    2008-06-01

    The extensive knowledge of the chemistry of isolated cell wall polymers, and that relating to the identification and partial annotation of gene families involved in their synthesis and modification, is not yet matched by a sophisticated understanding of the occurrence of the polymers within cell walls of the diverse cell types within a growing organ. Currently, the main sets of tools that are used to determine cell-type-specific configurations of cell wall polymers and aspects of cell wall microstructures are antibodies, carbohydrate-binding modules (CBMs) and microspectroscopies. As these tools are applied we see that cell wall polymers are extensively developmentally regulated and that there is a range of structurally distinct primary and secondary cell walls within organs and across species. The challenge now is to document cell wall structures in relation to diverse cell biological events and to integrate this knowledge with the emerging understanding of polymer functions.

  3. Cell Wall Binding Properties of the Bacillus subtilis Autolysin(s)

    PubMed Central

    Fan, David P.

    1970-01-01

    Cell walls isolated from exponentially growing Bacillus subtilis have autolysin(s) attached to them. An autolysin can be released from the walls by incubation at 0 C with 3 m LiCl. The enzyme can reattach to walls when the salt concentration is reduced. The bound enzyme cannot be removed or destroyed by washing the walls with 8 m urea at 0 C. The binding of free enzyme to walls at 0 C can take place normally in the presence of 2 m urea. PMID:4988245

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

    NASA Technical Reports Server (NTRS)

    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.

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

    SciTech Connect

    Bartley, Laura; Wu, Y.; Zhu, L.; Brummer, E. C.; Saha, M.

    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

  6. STREAMLINED METHOD FOR BIOMASS WHOLE-CELL-WALL STRUCTURAL PROFILING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In wide-ranging research aimed at altering plant cell wall characteristics by conventional breeding or modern genetic methods, one of the biggest problems is in delineating the effects on the cell wall. Plant cell walls are a complex conglomerate of a variety of polysaccharides and lignin. Each comp...

  7. STREAMLINED METHOD FOR BIOMASS WHOLE-CELL-WALL STRUCTURAL PROFILING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In wide-ranging research aimed at altering plant cell wall characteristics by conventional breeding or modern genetic methods, one of the biggest problems is in delineating the effects on the cell wall. Plant cell walls are a complex conglomerate of a variety of polysaccharides and lignin. Although ...

  8. The Structure of Plant Cell Walls

    PubMed Central

    Talmadge, Kenneth W.; Keegstra, Kenneth; Bauer, Wolfgang D.; Albersheim, Peter

    1973-01-01

    This is the first in a series of papers dealing with the structure of cell walls isolated from suspension-cultured sycamore cells (Acer pseudoplatanus). These studies have been made possible by the availability of purified hydrolytic enzymes and by recent improvements in the techniques of methylation analysis. These techniques have permitted us to identify and quantitate the macromolecular components of sycamore cell walls. These walls are composed of 10% arabinan, 2% 3,6-linked arabinogalactan, 23% cellulose, 9% oligo-arabinosides (attached to hydroxyproline), 8% 4-linked galactan, 10% hydroxyproline-rich protein, 16% rhamnogalacturonan, and 21% xyloglucan. The structures of the pectic polymers (the neutral arabinan, the neutral galactan, and the acidic rhamnogalacturonan) were obtained, in part, by methylation analysis of fragments of these polymers which were released from the sycamore walls by the action of a highly purified endopolygalacturonase. The data suggest a branched arabinan and a linear 4-linked galactan occurring as side chains on the rhamnogalacturonan. Small amounts or pieces of a xyloglucan, the wall hemicellulose, appear to be covalently linked to some of the galactan chains. Thus, the galactan appears to serve as a bridge between the xyloglucan and rhamnogalacturonan components of the wall. The rhamnogalacturonan consists of an α-(1 → 4)-linked galacturonan chain which is interspersed with 2-linked rhamnosyl residues. The rhamnosyl residues are not randomly distributed in the chain but probably occur in units of rhamnosyl- (1 → 4)-galacturonosyl- (1 → 2)-rhamnosyl. This sequence appears to alternate with a homogalacturonan sequence containing approximately 8 residues of 4-linked galacturonic acid. About half of the rhamnosyl residues are branched, having a substituent attached to carbon 4. This is likely to be the site of attachment of the 4-linked galactan. The hydroxyprolyl oligo-arabinosides of the hydroxyproline-rich glycoprotein

  9. Simulations of a Normal Shock Train in a Constant Area Duct Using Wall-Modeled LES

    NASA Astrophysics Data System (ADS)

    Vane, Zachary; Bermejo-Moreno, Ivan; Lele, Sanjiva

    2013-11-01

    Large-Eddy Simulations (LES) of a turbulent boundary layer interacting with a normal shock train in a constant area duct (STCAD) are performed using an unstructured solver. Comparisons between wall-modeled LES (WMLES) and wall-resolved LES (WRLES) calculations of a spanwise-periodic flow at M = 1.61 and Re = 16,200 are used to evaluate an equilibrium wall-model's ability to replicate the wall-resolved results. The WMLES approach is then used for simulations at the flow conditions (M = 1.61, Re = 162,000) of the Carroll & Dutton STCAD experiments where traditional WRLES was inaccessible. Spanwise-periodic WMLES calculations were unable to duplicate the experimental wall pressure and Laser Doppler Velocimetry data obtained along the spanwise center plane of the duct. Investigations of the full, low aspect ratio duct geometry were then performed using WMLES. Comparisons with experimental data provide an assessment of the wall-model's ability to simulate realistic, high Reynolds number, non-equilibrium flows. However, the lack of information with respect to the sidewall boundary layers from the experiment led to a WMLES parameter study of the effects of boundary layer confinement on the shock train. Initial results suggest that the tunnel blockage due to the boundary layer displacement thickness determines many of the STCAD's characteristics. A possible improvement to the wall-model through the inclusion of previously omitted non-equilibrium terms is currently being pursued.

  10. Monoclonal antibodies against plant cell wall polysaccharides

    SciTech Connect

    Hahn, M.G.; Bucheli, E.; Darvill, A.; Albersheim, P. )

    1989-04-01

    Monoclonal antibodies (McAbs) are useful tools to probe the structure of plant cell wall polysaccharides and to localize these polysaccharides in plant cells and tissues. Murine McAbs were generated against the pectic polysaccharide, rhamnogalacturonan I (RG-I), isolated from suspension-cultured sycamore cells. The McAbs that were obtained were grouped into three classes based upon their reactivities with a variety of plant polysaccharides and membrane glycoproteins. Eleven McAbs (Class I) recognize epitope(s) that appear to be immunodominant and are found in RG-I from sycamore and maize, citrus pectin, polygalacturonic acid, and membrane glycoproteins from suspension-cultured cells of sycamore, maize, tobacco, parsley, and soybean. A second group of five McAbs (Class II) recognize epitope(s) present in sycamore RG-I, but do not bind to any of the other polysaccharides or glycoproteins recognized by Class I. Lastly, one McAb (Class III) reacts with sycamore RG-I, sycamore and tamarind xyloglucan, and sycamore and rice glucuronoarabinoxylan, but does not bind to maize RG-I, polygalacturonic acid or the plant membrane glycoproteins recognized by Class I. McAbs in Classes II and III are likely to be useful in studies of the structure, biosynthesis and localization of plant cell wall polysaccharides.

  11. Engineering secondary cell wall deposition in plants

    PubMed Central

    Yang, Fan; Mitra, Prajakta; Zhang, Ling; Prak, Lina; Verhertbruggen, Yves; Kim, Jin-Sun; Sun, Lan; Zheng, Kejian; Tang, Kexuan; Auer, Manfred; Scheller, Henrik V; Loqué, Dominique

    2013-01-01

    Lignocellulosic biomass was used for thousands of years as animal feed and is now considered a great sugar source for biofuels production. It is composed mostly of secondary cell walls built with polysaccharide polymers that are embedded in lignin to reinforce the cell wall structure and maintain its integrity. Lignin is the primary material responsible for biomass recalcitrance to enzymatic hydrolysis. During plant development, deep reductions of lignin cause growth defects and often correlate with the loss of vessel integrity that adversely affects water and nutrient transport in plants. The work presented here describes a new approach to decrease lignin content while preventing vessel collapse and introduces a new strategy to boost transcription factor expression in native tissues. We used synthetic biology tools in Arabidopsis to rewire the secondary cell network by changing promoter-coding sequence associations. The result was a reduction in lignin and an increase in polysaccharide depositions in fibre cells. The promoter of a key lignin gene, C4H, was replaced by the vessel-specific promoter of transcription factor VND6. This rewired lignin biosynthesis specifically for vessel formation while disconnecting C4H expression from the fibre regulatory network. Secondly, the promoter of the IRX8 gene, secondary cell wall glycosyltransferase, was used to express a new copy of the fibre transcription factor NST1, and as the IRX8 promoter is induced by NST1, this also created an artificial positive feedback loop (APFL). The combination of strategies—lignin rewiring with APFL insertion—enhances polysaccharide deposition in stems without over-lignifying them, resulting in higher sugar yields after enzymatic hydrolysis. PMID:23140549

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

    PubMed Central

    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 walls need to be modified and customized during plant development and in response to environmental cues, thus contributing to plant adaptation. CWPs play essential roles in all these physiological processes and particularly in the dynamics of cell walls, which requires organization and rearrangements of polysaccharides as well as cell-to-cell communication. In the last 10 years, plant cell wall proteomics has greatly contributed to a wider knowledge of CWPs. This update will deal with (i) a survey of plant cell wall proteomics studies with a focus on Arabidopsis thaliana; (ii) the main protein families identified and the still missing peptides; (iii) the persistent issue of the non-canonical CWPs; (iv) the present challenges to overcome technological bottlenecks; and (v) the perspectives beyond cell wall proteomics to understand CWP functions. PMID:23641247

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

    PubMed

    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 walls need to be modified and customized during plant development and in response to environmental cues, thus contributing to plant adaptation. CWPs play essential roles in all these physiological processes and particularly in the dynamics of cell walls, which requires organization and rearrangements of polysaccharides as well as cell-to-cell communication. In the last 10 years, plant cell wall proteomics has greatly contributed to a wider knowledge of CWPs. This update will deal with (i) a survey of plant cell wall proteomics studies with a focus on Arabidopsis thaliana; (ii) the main protein families identified and the still missing peptides; (iii) the persistent issue of the non-canonical CWPs; (iv) the present challenges to overcome technological bottlenecks; and (v) the perspectives beyond cell wall proteomics to understand CWP functions.

  14. On the wall-normal velocity of the compressible boundary-layer equations

    NASA Technical Reports Server (NTRS)

    Pruett, C. David

    1991-01-01

    Numerical methods for the compressible boundary-layer equations are facilitated by transformation from the physical (x,y) plane to a computational (xi,eta) plane in which the evolution of the flow is 'slow' in the time-like xi direction. The commonly used Levy-Lees transformation results in a computationally well-behaved problem for a wide class of non-similar boundary-layer flows, but it complicates interpretation of the solution in physical space. Specifically, the transformation is inherently nonlinear, and the physical wall-normal velocity is transformed out of the problem and is not readily recovered. In light of recent research which shows mean-flow non-parallelism to significantly influence the stability of high-speed compressible flows, the contribution of the wall-normal velocity in the analysis of stability should not be routinely neglected. Conventional methods extract the wall-normal velocity in physical space from the continuity equation, using finite-difference techniques and interpolation procedures. The present spectrally-accurate method extracts the wall-normal velocity directly from the transformation itself, without interpolation, leaving the continuity equation free as a check on the quality of the solution. The present method for recovering wall-normal velocity, when used in conjunction with a highly-accurate spectral collocation method for solving the compressible boundary-layer equations, results in a discrete solution which is extraordinarily smooth and accurate, and which satisfies the continuity equation nearly to machine precision. These qualities make the method well suited to the computation of the non-parallel mean flows needed by spatial direct numerical simulations (DNS) and parabolized stability equation (PSE) approaches to the analysis of stability.

  15. Roles and regulation of plant cell walls surrounding plasmodesmata.

    PubMed

    Knox, J Paul; Benitez-Alfonso, Yoselin

    2014-12-01

    In plants, the intercellular transport of simple and complex molecules can occur symplastically through plasmodesmata. These are membranous channels embedded in cell walls that connect neighbouring cells. The properties of the cell walls surrounding plasmodesmata determine their transport capacity and permeability. These cell wall micro-domains are enriched in callose and have a characteristic pectin distribution. Cell wall modifications, leading to changes in plasmodesmata structure, have been reported to occur during development and in response to environmental signals. Cell wall remodelling enzymes target plasmodesmata to rapidly control intercellular communication in situ. Here we describe current knowledge on the composition of cell walls at plasmodesmata sites and on the proteins and signals that modify cell walls to regulate plasmodesmata aperture.

  16. Double-walled carbon nanotube solar cells.

    PubMed

    Wei, Jinquan; Jia, Yi; Shu, Qinke; Gu, Zhiyi; Wang, Kunlin; Zhuang, Daming; Zhang, Gong; Wang, Zhicheng; Luo, Jianbin; Cao, Anyuan; Wu, Dehai

    2007-08-01

    We directly configured double-walled carbon nanotubes as energy conversion materials to fabricate thin-film solar cells, with nanotubes serving as both photogeneration sites and a charge carriers collecting/transport layer. The solar cells consist of a semitransparent thin film of nanotubes conformally coated on a n-type crystalline silicon substrate to create high-density p-n heterojunctions between nanotubes and n-Si to favor charge separation and extract electrons (through n-Si) and holes (through nanotubes). Initial tests have shown a power conversion efficiency of >1%, proving that DWNTs-on-Si is a potentially suitable configuration for making solar cells. Our devices are distinct from previously reported organic solar cells based on blends of polymers and nanomaterials, where conjugate polymers generate excitons and nanotubes only serve as a transport path.

  17. Cell Wall Loosening in the Fungus, Phycomyces blakesleeanus

    PubMed Central

    Ortega, Joseph K. E.; Truong, Jason T.; Munoz, Cindy M.; Ramirez, David G.

    2015-01-01

    A considerable amount of research has been conducted to determine how cell walls are loosened to produce irreversible wall deformation and expansive growth in plant and algal cells. The same cannot be said about fungal cells. Almost nothing is known about how fungal cells loosen their walls to produce irreversible wall deformation and expansive growth. In this study, anoxia is used to chemically isolate the wall from the protoplasm of the sporangiophores of Phycomyces blakesleeanus. The experimental results provide direct evidence of the existence of chemistry within the fungal wall that is responsible for wall loosening, irreversible wall deformation and elongation growth. In addition, constant-tension extension experiments are conducted on frozen-thawed sporangiophore walls to obtain insight into the wall chemistry and wall loosening mechanism. It is found that a decrease in pH to 4.6 produces creep extension in the frozen-thawed sporangiophore wall that is similar, but not identical, to that found in frozen-thawed higher plant cell walls. Experimental results from frozen-thawed and boiled sporangiophore walls suggest that protein activity may be involved in the creep extension. PMID:27135318

  18. Normalized mean shapes and reference index values for computerized quantitative assessment indices of chest wall deformities

    NASA Astrophysics Data System (ADS)

    Kim, Ho Chul; Park, Man Sik; Lee, Seong Keon; Nam, Ki Chang; Park, Hyung Joo; Kim, Min Gi; Song, Jae-Jun; Choi, Hyuk

    2015-11-01

    We previously proposed a computerized index (eccentricity index [EI]) for chest-wall deformity measurements, such as pectus excavatum. We sought to define mean shapes based on normal chest walls and to propose for computerized index reference values of that are used in the quantitative analysis of the severity of chest-wall deformities. A total of 584 patients were classified into 18 groups, and a database of their chest-wall computed tomography (CT) scan images was constructed. The boundaries of the chest wall were extracted by using a segmentation algorithm, and the mean shapes were subsequently developed. The reference index values were calculated from the developed mean shapes. Reference index values for the EI were compared with a conventional index, the Haller index (HI). A close association has been shown between the two indices in multiple subjects (r = 0.974, P < 0.001). The newly developed mean shapes and reference index values supply both reliability and objectivity to the diagnosis, analysis, and treatment of chest-wall deformities. They promise to be highly useful in clinical settings.

  19. Right ventricular wall abscess in structurally normal heart after leg osteomyelitis: First case.

    PubMed

    Ahmad, Tanveer; Pasarad, Ashwini Kumar; Kishore, Kolkebaile Sadanand; Maheshwarappa, Nandakumar Neralakere

    2016-09-01

    A 3-year-old girl presented with fever and acute dyspnea for 4 days. She had suffered an injury to the left lower leg 3 weeks earlier, with abscess formation. Magnetic resonance imaging showed osteomyelitis of the lower tibia. Echocardiography showed a mass in the right ventricular wall. She underwent concomitant heart surgery for removal of the right ventricular mass and limb arthrotomy. We believe this is a first reported case in which a ventricular wall abscess developed in a structurally normal heart following leg osteomyelitis.

  20. Cell wall-associated kinases and pectin perception.

    PubMed

    Kohorn, Bruce D

    2016-01-01

    The pectin matrix of the angiosperm cell wall is regulated in both synthesis and modification and greatly influences the direction and extent of cell growth. Pathogens, herbivory and mechanical stresses all influence this pectin matrix and consequently plant form and function. The cell wall-associated kinases (WAKs) bind to pectin and regulate cell expansion or stress responses depending upon the state of the pectin. This review explores the WAKs in the context of cell wall biology and signal transduction pathways.

  1. THE STRUCTURE OF THE PRIMARY EPIDERMAL CELL WALL OF AVENA COLEOPTILES

    PubMed Central

    Bayley, S. T.; Colvin, J. R.; Cooper, F. P.; Martin-Smith, Cecily A.

    1957-01-01

    The primary walls of epidermal cells in Avena coleoptiles ranging in length from 2 to 40 mm. have been studied in the electron and polarizing microscopes and by the low-angle scattering of x-rays. The outer walls of these cells are composed of multiple layers of cellulose microfibrils oriented longitudinally; initially the number of layers is between 10 and 15 but this increases to about 25 in older tissue. Where epidermal cells touch, these multiple layers fuse gradually into a primary wall of the normal type between cells. In these radial walls, the microfibrils are oriented transversely. Possible mechanisms for the growth of the multilayered outer wall during cell elongation are discussed. PMID:13438900

  2. Grass cell walls: A story of cross-linking

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cell wall matrices are complex composites mainly of polysaccharides, phenolics (monomers and polymers), and protein. We are beginning to understand the synthesis of these major wall components individually, but still have a poor understanding of how the cell wall components are assembled into comple...

  3. Cortical microtubule rearrangements and cell wall patterning

    PubMed Central

    Oda, Yoshihisa

    2015-01-01

    Plant cortical microtubules, which form a highly ordered array beneath the plasma membrane, play essential roles in determining cell shape and function by directing the arrangement of cellulosic and non-cellulosic compounds on the cell surface. Interphase transverse arrays of cortical microtubules self-organize through their dynamic instability and inter-microtubule interactions, and by branch-form microtubule nucleation and severing. Recent studies revealed that distinct spatial signals including ROP GTPase, cellular geometry, and mechanical stress regulate the behavior of cortical microtubules at the subcellular and supercellular levels, giving rise to dramatic rearrangements in the cortical microtubule array in response to internal and external cues. Increasing evidence indicates that negative regulators of microtubules also contribute to the rearrangement of the cortical microtubule array. In this review, I summarize recent insights into how the rearrangement of the cortical microtubule array leads to proper, flexible cell wall patterning. PMID:25904930

  4. Exploiting fungal cell wall components in vaccines

    PubMed Central

    Levitz, Stuart M.; Huang, Haibin; Ostroff, Gary R.; Specht, Charles A.

    2014-01-01

    Innate recognition of fungi leads to strong adaptive immunity. Investigators are trying to exploit this observation in vaccine development by combining antigens with evolutionarily conserved fungal cell wall carbohydrates to induce protective responses. Best studied is β-1,3-glucan, a glycan that activates complement and is recognized by Dectin-1. Administration of antigens in association with β-1,3-glucan, either by direct conjugation or complexed in glucan particles, results in robust humoral and cellular immune responses. While the host has a host of mannose receptors, responses to fungal mannoproteins generally are amplified if cells are cooperatively stimulated with an additional danger signal such as a toll-like receptor agonist. Chitosan, a polycationic homopolymer of glucosamine manufactured by the deacetylation of chitin, is being studied as an adjuvant in DNA and protein-based vaccines. It appears particularly promising in mucosal vaccines. Finally, universal and organism-specific fungal vaccines have been formulated by conjugating fungal cell wall glycans to carrier proteins. A major challenge will be to advance these experimental findings so that at risk patients can be protected. PMID:25404118

  5. Grass Cell Walls: A Story of Cross-Linking

    PubMed Central

    Hatfield, Ronald D.; Rancour, David M.; Marita, Jane M.

    2017-01-01

    Cell wall matrices are complex composites mainly of polysaccharides, phenolics (monomers and polymers), and protein. We are beginning to understand the synthesis of these major wall components individually, but still have a poor understanding of how cell walls are assembled into complex matrices. Valuable insight has been gained by examining intact components to understand the individual elements that make up plant cell walls. Grasses are a prominent group within the plant kingdom, not only for their important roles in global agriculture, but also for the complexity of their cell walls. Ferulate incorporation into grass cell wall matrices (C3 and C4 types) leads to a cross-linked matrix that plays a prominent role in the structure and utilization of grass biomass compared to dicot species. Incorporation of p-coumarates as part of the lignin structure also adds to the complexity of grass cell walls. Feruoylation results in a wall with individual hemicellulosic polysaccharides (arabinoxylans) covalently linked to each other and to lignin. Evidence strongly suggests that ferulates not only cross-link arabinoxylans, but may be important factors in lignification of the cell wall. Therefore, the distribution of ferulates on arabinoxylans could provide a means of structuring regions of the matrix with the incorporation of lignin and have a significant impact upon localized cell wall organization. The role of other phenolics in cell wall formation such as p-coumarates (which can have concentrations higher than ferulates) remains unknown. It is possible that p-coumarates assist in the formation of lignin, especially syringyl rich lignin. The uniqueness of the grass cell wall compared to dicot sepcies may not be so much in the gross composition of the wall, but how the distinctive individual components are organized into a functional wall matrix. These features are discussed and working models are provided to illustrate how changing the organization of feruoylation and p

  6. Hanging-wall deformation above a normal fault: sequential limit analyses

    NASA Astrophysics Data System (ADS)

    Yuan, Xiaoping; Leroy, Yves M.; Maillot, Bertrand

    2015-04-01

    The deformation in the hanging wall above a segmented normal fault is analysed with the sequential limit analysis (SLA). The method combines some predictions on the dip and position of the active fault and axial surface, with geometrical evolution à la Suppe (Groshong, 1989). Two problems are considered. The first followed the prototype proposed by Patton (2005) with a pre-defined convex, segmented fault. The orientation of the upper segment of the normal fault is an unknown in the second problem. The loading in both problems consists of the retreat of the back wall and the sedimentation. This sedimentation starts from the lowest point of the topography and acts at the rate rs relative to the wall retreat rate. For the first problem, the normal fault either has a zero friction or a friction value set to 25o or 30o to fit the experimental results (Patton, 2005). In the zero friction case, a hanging wall anticline develops much like in the experiments. In the 25o friction case, slip on the upper segment is accompanied by rotation of the axial plane producing a broad shear zone rooted at the fault bend. The same observation is made in the 30o case, but without slip on the upper segment. Experimental outcomes show a behaviour in between these two latter cases. For the second problem, mechanics predicts a concave fault bend with an upper segment dip decreasing during extension. The axial surface rooting at the normal fault bend sees its dips increasing during extension resulting in a curved roll-over. Softening on the normal fault leads to a stepwise rotation responsible for strain partitioning into small blocks in the hanging wall. The rotation is due to the subsidence of the topography above the hanging wall. Sedimentation in the lowest region thus reduces the rotations. Note that these rotations predicted by mechanics are not accounted for in most geometrical approaches (Xiao and Suppe, 1992) and are observed in sand box experiments (Egholm et al., 2007, referring

  7. Cell wall fermentation kinetics impacted more by lignin content and cross-linking than by diverse shifts in lignin composition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We used a biomimetic model system to ascertain how lignification and diverse shifts in lignin cross-linking and composition influence cell wall fermentation. Primary cell walls from nonlignified maize cell suspensions were artificially lignified with varying ratios of normal monolignols (coniferyl a...

  8. Vessel wall-embedded dendritic cells induce T-cell autoreactivity and initiate vascular inflammation.

    PubMed

    Han, Ji W; Shimada, Kazunori; Ma-Krupa, Wei; Johnson, Tiffany L; Nerem, Robert M; Goronzy, Jörg J; Weyand, Cornelia M

    2008-03-14

    Human medium-sized and large arteries are targeted by inflammation with innate and adaptive immune responses occurring within the unique microspace of the vessel wall. How 3D spatial arrangements influence immune recognition and cellular response thresholds and which cell populations sense immunoactivating ligands and function as antigen-presenting cells are incompletely understood. To mimic the 3D context of human arteries, bioartificial arteries were engineered from collagen type I matrix, human vascular smooth muscle cells (VSMCs), and human endothelial cells and populated with cells implicated in antigen presentation and T-cell stimulation, including monocytes, macrophages, and myeloid dendritic cells (DCs). Responsiveness of wall-embedded antigen-presenting cells was probed with the Toll-like receptor ligand lipopolysaccharide, and inflammation was initiated by adding autologous CD4(+) T cells. DCs colonized the outermost VSMC layer, recapitulating their positioning at the media-adventitia border of normal arteries. Wall-embedded DCs responded to the microbial product lipopolysaccharide by entering the maturation program and upregulating the costimulatory ligand CD86. Activated DCs effectively stimulated autologous CD4 T cells, which produced the proinflammatory cytokine interferon-gamma and infiltrated deeply into the VSMC layer, causing matrix damage. Lipopolysaccharide-triggered macrophages were significantly less efficacious in recruiting T cells and promoting T-cell stimulation. CD14(+) monocytes, even when preactivated, failed to support initial steps of vascular wall inflammation. Innate immune cells, including monocytes, macrophages, and DCs, display differential functions in the vessel wall. DCs are superior in sensing pathogen-derived motifs and are highly efficient in breaking T-cell tolerance, guiding T cells toward proinflammatory and tissue-invasive behavior.

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

    PubMed Central

    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 the TCA-wall consisted of mostly peptidoglycan. By digesting the TCA-wall with lysozyme, the circular structures were greatly disturbed, and they disappeared after 60 min of treatment. From these observations it can be expected that the peptidoglycan is arranged in a concentric circular manner in the newly generated cell wall of Staphylococcus. Images PMID:7068534

  10. Enzymes and other agents that enhance cell wall extensibility

    NASA Technical Reports Server (NTRS)

    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.

  11. Disruption of hydrogen bonding between plant cell wall polymers by proteins that induce wall extension.

    PubMed Central

    McQueen-Mason, S; Cosgrove, D J

    1994-01-01

    Plant cell enlargement is controlled by the ability of the constraining cell wall to expand. This ability has been postulated to be under the control of polysaccharide hydrolases or transferases that weaken or rearrange the loadbearing polymeric networks in the wall. We recently identified a family of wall proteins, called expansins, that catalyze the extension of isolated plant cell walls. Here we report that these proteins mechanically weaken pure cellulose paper in extension assays and stress relaxation assays, without detectable cellulase activity (exo- or endo- type). Because paper derives its mechanical strength from hydrogen bonding between cellulose microfibrils, we conclude that expansins can disrupt hydrogen bonding between cellulose fibers. This conclusion is further supported by experiments in which expansin-mediated wall extension (i) was increased by 2 M urea (which should weaken hydrogen bonding between wall polymers) and (ii) was decreased by replacement of water with deuterated water, which has a stronger hydrogen bond. The temperature sensitivity of expansin-mediated wall extension suggests that units of 3 or 4 hydrogen bonds are broken by the action of expansins. In the growing cell wall, expansin action is likely to catalyze slippage between cellulose microfibrils and the polysaccharide matrix, and thereby catalyze wall stress relaxation, followed by wall surface expansion and plant cell enlargement. Images PMID:11607483

  12. Anthocyanins influence tannin-cell wall interactions.

    PubMed

    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.

  13. Tracing Cell Wall Biogenesis in Intact Cells and Plants 1

    PubMed Central

    Gibeaut, David M.; Carpita, Nicholas C.

    1991-01-01

    Cells of proso millet (Panicum miliaceum L. cv Abarr) in liquid culture and leaves of maize seedlings (Zea mays L. cv LH51 × LH1131) readily incorporated d-[U-14C]glucose and l-[U-14C]arabinose into soluble and cell wall polymers. Radioactivity from arabinose accumulated selectively in polymers containing arabinose or xylose because a salvage pathway and C-4 epimerase yield both nucleotide-pentoses. On the other hand, radioactivity from glucose was found in all sugars and polymers. Pulse-chase experiments with proso millet cells in liquid culture demonstrated turnover of buffer soluble polymers within minutes and accumulation of radioactive polymers in the cell wall. In leaves of maize seedlings, radioactive polymers accumulated quickly and peaked 30 hours after the pulse then decreased slowly for the remaining time course. During further growth of the seedlings, radioactive polymers became more tenaciously bound in the cell wall. Sugars were constantly recycled from turnover of polysaccharides of the cell wall. Arabinose, hydrolyzed from glucuronoarabinoxylans, and glucose, hydrolyzed from mixed-linkage (1→3, 1→4)β-d-glucans, constituted most of the sugar participating in turnover. Arabinogalactans were a large portion of the buffer soluble (cytoplasmic) polymers of both proso millet cells and maize seedlings, and these polymers also exhibited turnover. Our results indicate that the primary cell wall is not simply a sink for various polysaccharide components, but rather a dynamic compartment exhibiting long-term reorganization by turnover and alteration of specific polymers during development. PMID:16668434

  14. Disruption of cell walls for enhanced lipid recovery

    DOEpatents

    Knoshaug, Eric P; Donohoe, Bryon S; Gerken, Henri; Laurens, Lieve; Van Wychen, Stefanie Rose

    2015-03-24

    Presented herein are methods of using cell wall degrading enzymes for recovery of internal lipid bodies from biomass sources such as algae. Also provided are algal cells that express at least one exogenous gene encoding a cell wall degrading enzyme and methods for recovering lipids from the cells.

  15. Acute myocarditis with normal wall motion detected with 2D speckle tracking echocardiography

    PubMed Central

    Niel, Johannes; Aichinger, Josef; Ebner, Christian

    2016-01-01

    Summary We present the case of a 26-year-old male with acute tonsillitis who was referred for coronary angiography because of chest pain, elevated cardiac biomarkers, and biphasic T waves. The patient had no cardiovascular risk factors. Echocardiography showed no wall motion abnormalities and no pericardial effusion. 2D speckle tracking revealed distinct decreased regional peak longitudinal systolic strain in the lateral and posterior walls. Ischemic disease was extremely unlikely in view of his young age, negative family history regarding coronary artery disease, and lack of regional wall motion abnormalities on the conventional 2D echocardiogram. Coronary angiography was deferred as myocarditis was suspected. To confirm the diagnosis, cardiac magnetic resonance tomography (MRT) was performed, showing subepicardial delayed hyperenhancement in the lateral and posterior walls correlating closely with the strain pattern obtained by 2D speckle tracking echocardiography. With a working diagnosis of acute myocarditis associated with acute tonsillitis, we prescribed antibiotics and nonsteroidal anti-inflammatory drugs. The patient’s clinical signs resolved along with normalization of serum creatine kinase (CK) levels, and the patient was discharged on the third day after admission. Learning points Acute myocarditis can mimic acute coronary syndromes.Conventional 2D echocardiography lacks specific features for detection of subtle regional wall motion abnormalities.2D speckle tracking expands the scope of echocardiography in identifying myocardial dysfunction derived from edema in acute myocarditis. PMID:27249814

  16. Shifting foundations: the mechanical cell wall and development.

    PubMed

    Braybrook, Siobhan A; Jönsson, Henrik

    2016-02-01

    The cell wall has long been acknowledged as an important physical mediator of growth in plants. Recent experimental and modelling work has brought the importance of cell wall mechanics into the forefront again. These data have challenged existing dogmas that relate cell wall structure to cell/organ growth, that uncouple elasticity from extensibility, and those which treat the cell wall as a passive and non-stressed material. Within this review we describe experiments and models which have changed the ways in which we view the mechanical cell wall, leading to new hypotheses and research avenues. It has become increasingly apparent that while we often wish to simplify our systems, we now require more complex multi-scale experiments and models in order to gain further insight into growth mechanics. We are currently experiencing an exciting and challenging shift in the foundations of our understanding of cell wall mechanics in growth and development.

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

    NASA Technical Reports Server (NTRS)

    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.

  18. Evolution and diversity of green plant cell walls.

    PubMed

    Popper, Zoë A

    2008-06-01

    Plant cells are surrounded by a dynamic cell wall that performs many essential biological roles, including regulation of cell expansion, the control of tissue cohesion, ion-exchange and defence against microbes. Recent evidence shows that the suite of polysaccharides and wall proteins from which the plant cell wall is composed shows variation between monophyletic plant taxa. This is likely to have been generated during the evolution of plant groups in response to environmental stress. Understanding the natural variation and diversity that exists between cell walls from different taxa is key to facilitating their future exploitation and manipulation, for example by increasing lignocellulosic content or reducing its recalcitrance for use in biofuel generation.

  19. Multidimensional solid-state NMR spectroscopy of plant cell walls.

    PubMed

    Wang, Tuo; Phyo, Pyae; Hong, Mei

    2016-09-01

    Plant biomass has become an important source of bio-renewable energy in modern society. The molecular structure of plant cell walls is difficult to characterize by most atomic-resolution techniques due to the insoluble and disordered nature of the cell wall. Solid-state NMR (SSNMR) spectroscopy is uniquely suited for studying native hydrated plant cell walls at the molecular level with chemical resolution. Significant progress has been made in the last five years to elucidate the molecular structures and interactions of cellulose and matrix polysaccharides in plant cell walls. These studies have focused on primary cell walls of growing plants in both the dicotyledonous and grass families, as represented by the model plants Arabidopsis thaliana, Brachypodium distachyon, and Zea mays. To date, these SSNMR results have shown that 1) cellulose, hemicellulose, and pectins form a single network in the primary cell wall; 2) in dicot cell walls, the protein expansin targets the hemicellulose-enriched region of the cellulose microfibril for its wall-loosening function; and 3) primary wall cellulose has polymorphic structures that are distinct from the microbial cellulose structures. This article summarizes these key findings, and points out future directions of investigation to advance our fundamental understanding of plant cell wall structure and function.

  20. Wall teichoic acids prevent antibody binding to epitopes within the cell wall of Staphylococcus aureus.

    PubMed

    Gautam, Samir; Kim, Taehan; Lester, Evan; Deep, Deeksha; Spiegel, David A

    2016-01-15

    Staphylococcus aureus is a Gram-positive bacterial pathogen that produces a range of infections including cellulitis, pneumonia, and septicemia. The principle mechanism in antistaphylococcal host defense is opsonization with antibodies and complement proteins, followed by phagocytic clearance. Here we use a previously developed technique for installing chemical epitopes in the peptidoglycan cell wall to show that surface glycopolymers known as wall teichoic acids conceal cell wall epitopes, preventing their recognition and opsonization by antibodies. Thus, our results reveal a previously unrecognized immunoevasive role for wall teichoic acids in S. aureus: repulsion of peptidoglycan-targeted antibodies.

  1. Bacterial cell wall composition and the influence of antibiotics by cell-wall and whole-cell NMR

    PubMed Central

    Romaniuk, Joseph A. H.; Cegelski, Lynette

    2015-01-01

    The ability to characterize bacterial cell-wall composition and structure is crucial to understanding the function of the bacterial cell wall, determining drug modes of action and developing new-generation therapeutics. Solid-state NMR has emerged as a powerful tool to quantify chemical composition and to map cell-wall architecture in bacteria and plants, even in the context of unperturbed intact whole cells. In this review, we discuss solid-state NMR approaches to define peptidoglycan composition and to characterize the modes of action of old and new antibiotics, focusing on examples in Staphylococcus aureus. We provide perspectives regarding the selected NMR strategies as we describe the exciting and still-developing cell-wall and whole-cell NMR toolkit. We also discuss specific discoveries regarding the modes of action of vancomycin analogues, including oritavancin, and briefly address the reconsideration of the killing action of β-lactam antibiotics. In such chemical genetics approaches, there is still much to be learned from perturbations enacted by cell-wall assembly inhibitors, and solid-state NMR approaches are poised to address questions of cell-wall composition and assembly in S. aureus and other organisms. PMID:26370936

  2. (The structure of pectins from cotton suspension culture cell walls)

    SciTech Connect

    Mort, A.

    1990-01-01

    We have made progress on several projects to do with determining the structure of pectins. These include: (1) Devising a new sensitive method to determine the degree of methyl esterification (DOM) of pectins; (2) solubilization of all of RGI from cotton cell walls; (3) solubilization of RGII from cotton cell walls; (4) characterization of xyloglucan from cotton cell walls; and (5) investigation giving an indication of a cross-link between extension and pectin.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  4. [Hydroxyproline: Rich glycoproteins of the plant and cell wall

    SciTech Connect

    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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  6. Secondary cell walls: biosynthesis, patterned deposition and transcriptional regulation.

    PubMed

    Zhong, Ruiqin; Ye, Zheng-Hua

    2015-02-01

    Secondary walls are mainly composed of cellulose, hemicelluloses (xylan and glucomannan) and lignin, and are deposited in some specialized cells, such as tracheary elements, fibers and other sclerenchymatous cells. Secondary walls provide strength to these cells, which lend mechanical support and protection to the plant body and, in the case of tracheary elements, enable them to function as conduits for transporting water. Formation of secondary walls is a complex process that requires the co-ordinated expression of secondary wall biosynthetic genes, biosynthesis and targeted secretion of secondary wall components, and patterned deposition and assembly of secondary walls. Here, we provide a comprehensive review of genes involved in secondary wall biosynthesis and deposition. Most of the genes involved in the biosynthesis of secondary wall components, including cellulose, xylan, glucomannan and lignin, have been identified and their co-ordinated activation has been shown to be mediated by a transcriptional network encompassing the secondary wall NAC and MYB master switches and their downstream transcription factors. It has been demonstrated that cortical microtubules and microtubule-associated proteins play important roles in the targeted secretion of cellulose synthase complexes, the oriented deposition of cellulose microfibrils and the patterned deposition of secondary walls. Further investigation of many secondary wall-associated genes with unknown functions will provide new insights into the mechanisms controlling the formation of secondary walls that constitute the bulk of plant biomass.

  7. Small Molecule Probes for Plant Cell Wall Polysaccharide Imaging

    PubMed Central

    Wallace, Ian S.; Anderson, Charles T.

    2012-01-01

    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. PMID:22639673

  8. Cell wall ultrastructure of flocculent and non-flocculent Schizosaccharomyces pombe strains. Effect of cell wall hydrolysing enzymes on flocculation and cell wall ultastructure.

    PubMed

    Geleta, Anna; Kristóf, Z; Maráz, Anna

    2007-03-01

    Scanning and transmission electron microscopic studies revealed the presence of slime-like, amorphous material on the surface of Schizosaccahromyces pombe RIVE 4-2-1 cells, independently, whether they were in flocculated or in non-flocculated state. Close contact of the adjacent cells via the merging outermost cell wall layers was found, however, only in the case of floc formation, which was induced by cultivating the cells in the presence of 6% (v/v) ethanol. Irreversible loss of the flocculation ability of the cells by treatment with proteinases suggests that proteinaceous cell surface molecules as lectins contribute to the cell-to-cell interaction during flocculation. Both proteinase K and pronase treatments removed a distinct outer layer of the cell wall, which indicated that the protein moieties of the phosphogalactomannan outer surface layer has a crucial role in the maintenance of cell wall integrity. In the case of lysing enzyme treatment the removal of the outermost layer was also observed as the first step of the cell wall digestion, while driselase treatment resulted in almost complete digestion of the cell wall.

  9. An enlarged cell wall proteome of Arabidopsis thaliana rosettes.

    PubMed

    Hervé, Vincent; Duruflé, Harold; San Clemente, Hélène; Albenne, Cécile; Balliau, Thierry; Zivy, Michel; Dunand, Christophe; Jamet, Elisabeth

    2016-12-01

    Plant cells are surrounded by cell walls playing many roles during development and in response to environmental constraints. Cell walls are mainly composed of polysaccharides (cellulose, hemicelluloses and pectins), but they also contain proteins which are critical players in cell wall remodeling processes. Today, the cell wall proteome of Arabidopsis thaliana, a major dicot model plant, comprises more than 700 proteins predicted to be secreted (cell wall proteins-CWPs) identified in different organs or in cell suspension cultures. However, the cell wall proteome of rosettes is poorly represented with only 148 CWPs identified after extraction by vacuum infiltration. This new study allows enlarging its coverage. A destructive method starting with the purification of cell walls has been performed and two experiments have been compared. They differ by the presence/absence of protein separation by a short 1D-electrophoresis run prior to tryptic digestion and different gradient programs for peptide separation before mass spectrometry analysis. Altogether, the rosette cell wall proteome has been significantly enlarged to 361 CWPs, among which 213 newly identified in rosettes and 57 newly described. The identified CWPs fall in four major functional classes: 26.1% proteins acting on polysaccharides, 11.1% oxido-reductases, 14.7% proteases and 11.7% proteins possibly related to lipid metabolism.

  10. Preparation of Cell Wall Antigens of Staphylococcus aureus

    PubMed Central

    Kowalski, J. J.; Tipper, Donald J.; Berman, David T.

    1970-01-01

    Cell walls were prepared from Staphylococcus aureus strains Copenhagen and 263 by high-speed mixing in the presence of glass beads followed by differential centrifugation. Insoluble peptidoglycan complexes were derived from cell walls by extraction of teichoic acid with 10% trichloroacetic acid. Intact teichoic acid was prepared from each strain by digestion of cell walls with lysostaphin and isolated by column chromatography. Soluble glycopeptide (peptidoglycan in which only the glycan has been fragmented) and the stable complex of teichoic acid with glycopeptide were prepared by digestion of cell walls with Chalaropsis B endo-N-acetylmuramidase and were separated by column chromatography. Amino acid and amino sugar contents of walls and subunits of walls were comparable to those reported by others. Images PMID:16557799

  11. Screening and characterization of plant cell walls using carbohydrate microarrays.

    PubMed

    Sørensen, Iben; Willats, William G T

    2011-01-01

    Plant cells are surrounded by cell walls built largely from complex carbohydrates. The primary walls of growing plant cells consist of interdependent networks of three polysaccharide classes: cellulose, cross-linking glycans (also known as hemicelluloses), and pectins. Cellulose microfibrils are tethered together by cross-linking glycans, and this assembly forms the major load-bearing component of primary walls, which is infiltrated with pectic polymers. In the secondary walls of woody tissues, pectins are much reduced and walls are reinforced with the phenolic polymer lignin. Plant cell walls are essential for plant life and also have numerous industrial applications, ranging from wood to nutraceuticals. Enhancing our knowledge of cell wall biology and the effective use of cell wall materials is dependent to a large extent on being able to analyse their fine structures. We have developed a suite of techniques based on microarrays probed with monoclonal antibodies with specificity for cell wall components, and here we present practical protocols for this type of analysis.

  12. How the deposition of cellulose microfibrils builds cell wall architecture.

    PubMed

    Emons, A M; Mulder, B M

    2000-01-01

    Cell walls, the extracytoplasmic matrices of plant cells, consist of an ordered array of cellulose microfibrils embedded in a matrix of polysaccharides and glycoproteins. This construction is reminiscent of steel rods in reinforced concrete. How a cell organizes these ordered textures around itself, creating its own desirable environment, is a fascinating question. We believe that nature adopted an economical solution to this design problem: it exploits the geometrical constraints imposed by the shape of the cell and the limited space in which microfibrils are deposited, enabling the wall textures essentially to 'build themselves'. This does not imply that the cell cannot control its wall texture. On the contrary, the cell has ample regulatory mechanisms to control wall texture formation by controlling the insertion of synthases and the distance between individual microfibrils within a wall lamella.

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

    NASA Technical Reports Server (NTRS)

    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.

  14. Structural Studies of Complex Carbohydrates of Plant Cell Walls

    SciTech Connect

    Darvill, Alan; Hahn, Michael G.; O'Neill, Malcolm A.; York, William S.

    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.

  15. Role of Cell Cycle-regulated Expression in the Localized Incorporation of Cell Wall Proteins in Yeast

    PubMed Central

    Schenkman, Laura R.; Brul, Stanley; Pringle, John R.; Klis, Frans M.

    2006-01-01

    The yeast cell wall is an essential organelle that protects the cell from mechanical damage and antimicrobial peptides, participates in cell recognition and adhesion, and is important for the generation and maintenance of normal cell shape. We studied the localization of three covalently bound cell wall proteins in Saccharomyces cerevisiae. Tip1p was found only in mother cells, whereas Cwp2p was incorporated in small-to-medium–sized buds. When the promoter regions of TIP1 and CWP2 (responsible for transcription in early G1 and S/G2 phases, respectively) were exchanged, the localization patterns of Tip1p and Cwp2p were reversed, indicating that the localization of cell wall proteins can be completely determined by the timing of transcription during the cell cycle. The third protein, Cwp1p, was incorporated into the birth scar, where it remained for several generations. However, we could not detect any role of Cwp1p in strengthening the birth scar wall or any functional interaction with the proteins that mark the birth scar pole as a potential future budding site. Promoter-exchange experiments showed that expression in S/G2 phase is necessary but not sufficient for the normal localization of Cwp1p. Studies of mutants in which septum formation is perturbed indicate that the normal asymmetric localization of Cwp1p also depends on the normal timing of septum formation, composition of the septum, or both. PMID:16672383

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

    NASA Technical Reports Server (NTRS)

    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.

  17. Tissue-specific cell wall hydration in sugarcane stalks.

    PubMed

    Maziero, Priscila; Jong, Jennifer; Mendes, Fernanda M; Gonçalves, Adilson R; Eder, Michaela; Driemeier, Carlos

    2013-06-19

    Plant cell walls contain water, especially under biological and wet processing conditions. The present work characterizes this water in tissues of sugarcane stalks. Environmental scanning electron microscopy shows tissue deformation upon drying. Dynamic vapor sorption determines the equilibrium and kinetics of moisture uptake. Thermoporometry by differential scanning calorimetry quantifies water in nanoscale pores. Results show that cell walls from top internodes of stalks are more deformable, slightly more sorptive to moisture, and substantially more porous. These differences of top internode are attributed to less lignified walls, which is confirmed by lower infrared spectral signal from aromatics. Furthermore, cell wall nanoscale porosity, an architectural and not directly compositional characteristic, is shown to be tissue-specific. Nanoscale porosities are ranked as follows: pith parenchyma > pith vascular bundles > rind. This ranking coincides with wall reactivity and digestibility in grasses, suggesting that nanoscale porosity is a major determinant of wall recalcitrance.

  18. Methods for degrading or converting plant cell wall polysaccharides

    DOEpatents

    Berka, Randy; Cherry, Joel

    2008-08-19

    The present invention relates to methods for converting plant cell wall polysaccharides into one or more products, comprising: treating the plant cell wall polysaccharides with an effective amount of a spent whole fermentation broth of a recombinant microorganism, wherein the recombinant microorganism expresses one or more heterologous genes encoding enzymes which degrade or convert the plant cell wall polysaccharides into the one or more products. The present invention also relates to methods for producing an organic substance, comprising: (a) saccharifying plant cell wall polysaccharides with an effective amount of a spent whole fermentation broth of a recombinant microorganism, wherein the recombinant microorganism expresses one or more heterologous genes encoding enzymes which degrade or convert the plant cell wall polysaccharides into saccharified material; (b) fermenting the saccharified material of step (a) with one or more fermenting microoganisms; and (c) recovering the organic substance from the fermentation.

  19. Collenchyma: a versatile mechanical tissue with dynamic cell walls

    PubMed Central

    Leroux, Olivier

    2012-01-01

    Background Collenchyma has remained in the shadow of commercially exploited mechanical tissues such as wood and fibres, and therefore has received little attention since it was first described. However, collenchyma is highly dynamic, especially compared with sclerenchyma. It is the main supporting tissue of growing organs with walls thickening during and after elongation. In older organs, collenchyma may become more rigid due to changes in cell wall composition or may undergo sclerification through lignification of newly deposited cell wall material. While much is known about the systematic and organographic distribution of collenchyma, there is rather less information regarding the molecular architecture and properties of its cell walls. Scope and conclusions This review summarizes several aspects that have not previously been extensively discussed including the origin of the term ‘collenchyma’ and the history of its typology. As the cell walls of collenchyma largely determine the dynamic characteristics of this tissue, I summarize the current state of knowledge regarding their structure and molecular composition. Unfortunately, to date, detailed studies specifically focusing on collenchyma cell walls have not been undertaken. However, generating a more detailed understanding of the structural and compositional modifications associated with the transition from plastic to elastic collenchyma cell wall properties is likely to provide significant insights into how specific configurations of cell wall polymers result in specific functional properties. This approach, focusing on architecture and functional properties, is likely to provide improved clarity on the controversial definition of collenchyma. PMID:22933416

  20. Scaling properties of the mean wall-normal velocity in the zero pressure gradient boundary layer

    NASA Astrophysics Data System (ADS)

    Wei, Tie; Klewicki, Joseph

    2016-11-01

    The scaling properties of the mean wall-normal velocity, V (x , y) , in zero-pressure-gradient laminar and turbulent boundary layer flows is investigated using numerical simulation data, physical experiment data, and integral analyses of governing equations. The maximum mean wall-normal velocity, V∞, and the boundary layer thickness, δ, are evidenced to be the proper scaling for V over most if not the entire boundary layer. This is different from the behavior of the mean streamwise velocity (U) or the turbulent shear stress (T = - ρ < uv >), which depend on different characteristic length scales in the regions near to and away from the surface. Insights pertaining to this are further surmised from an analytical relationship for the ratio of the displacement to momentum thickness, i.e., shape factor, H. Integral analyses using the continuity and mean momentum equation show that (U∞V∞) /uτ2 = H , where uτ is the friction velocity. Both the laminar similarity solution and DNS data in post-transitional flows convincingly support this relation. Over the transitional regime, sufficiently high quality data is still lacking to check if this relation remains valid.

  1. Scaling properties of the mean wall-normal velocity in zero-pressure-gradient boundary layers

    NASA Astrophysics Data System (ADS)

    Wei, Tie; Klewicki, Joseph

    2016-12-01

    The scaling properties of the mean wall-normal velocity V (x ,y ) in zero-pressure-gradient laminar and turbulent boundary-layer flows are investigated using numerical simulation data, physical experiment data, and integral analyses of the governing equations. The maximum mean wall-normal velocity V∞ and the boundary-layer thickness δ are evidenced to be the proper scaling for V over most if not all of the boundary layer. This is different from the behavior of the mean streamwise velocity U or the turbulent shear stress T =-ρ , which depend on different characteristic length scales in the regions near and away from the surface, respectively. The reason for this apparent difference in scaling behaviors is described physically relative to the downstream development of the U velocity profile and the mechanisms of boundary-layer growth. Insights pertaining to this are further surmised from an analytical relationship for the ratio of the displacement to momentum thickness, i.e., shape factor H . Integral analyses using the continuity and mean momentum equation show that U∞V∞/uτ2=H , where uτ is the friction velocity. Both the laminar similarity solution and direct numerical simulation data in post-transitional flows convincingly support this relation. Over the transitional regime, data of sufficiently high quality are lacking to check if this relation remains valid.

  2. Mechanical properties of spruce wood cell walls by nanoindentation

    NASA Astrophysics Data System (ADS)

    Gindl, W.; Gupta, H. S.; Schöberl, T.; Lichtenegger, H. C.; Fratzl, P.

    2004-12-01

    In order to study the effects of structural variability, nanoindentation experiments were performed in Norway spruce cell walls with highly variable cellulose microfibril angle and lignin content. Contrary to hardness, which showed no statistically significant relationship with changing microfibril angle and lignin content, the elastic modulus of the secondary cell wall decreased significantly with increasing microfibril angle. While the elastic moduli of cell walls with large microfibril angle agreed well with published values, the elastic moduli of cell walls with small microfibril angle were clearly underestimated in nanoindentation measurements. Hardness measurements in the cell corner middle lamella allowed us to estimate the yield stress of the cell-wall matrix to be 0.34±0.16 GPa. Since the hardness of the secondary cell wall was statistically not different from the hardness of the cell corner middle lamella, irrespective of high variability in cellulose microfibril angle, it is proposed that compressive yielding of wood-cell walls is a matrix-dominated process.

  3. Dynamic metabolic flux analysis of plant cell wall synthesis.

    PubMed

    Chen, Xuewen; Alonso, Ana P; Shachar-Hill, Yair

    2013-07-01

    The regulation of plant cell wall synthesis pathways remains poorly understood. This has become a bottleneck in designing bioenergy crops. The goal of this study was to analyze the regulation of plant cell wall precursor metabolism using metabolic flux analysis based on dynamic labeling experiments. Arabidopsis T87 cells were cultured heterotrophically with (13)C labeled sucrose. The time course of ¹³C labeling patterns in cell wall precursors and related sugar phosphates was monitored using liquid chromatography tandem mass spectrometry until steady state labeling was reached. A kinetic model based on mass action reaction mechanisms was developed to simulate the carbon flow in the cell wall synthesis network. The kinetic parameters of the model were determined by fitting the model to the labeling time course data, cell wall composition, and synthesis rates. A metabolic control analysis was performed to predict metabolic regulations that may improve plant biomass composition for biofuel production. Our results describe the routes and rates of carbon flow from sucrose to cell wall precursors. We found that sucrose invertase is responsible for the entry of sucrose into metabolism and UDP-glucose-4-epimerase plays a dominant role in UDP-Gal synthesis in heterotrophic Aradidopsis cells under aerobic conditions. We also predicted reactions that exert strong regulatory influence over carbon flow to cell wall synthesis and its composition.

  4. Maize development: cell wall changes in leaves and sheaths

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Developmental changes occur in maize (Zea mays L.) as it transitions from juvenile stages to the mature plant. Changes also occur as newly formed cells mature into adult cells. Maize leaf blades, including the midribs and sheaths, undergo cell wall changes as cells transition to fully mature cell ty...

  5. The Plant Cell Wall: A Dynamic Barrier Against Pathogen Invasion

    PubMed Central

    Underwood, William

    2012-01-01

    Prospective plant pathogens must overcome the physical barrier presented by the plant cell wall. In addition to being a preformed, passive barrier limiting access of pathogens to plant cells, the cell wall is actively remodeled and reinforced specifically at discrete sites of interaction with potentially pathogenic microbes. Active reinforcement of the cell wall through the deposition of cell wall appositions, referred to as papillae, is an early response to perception of numerous categories of pathogens including fungi and bacteria. Rapid deposition of papillae is generally correlated with resistance to fungal pathogens that attempt to penetrate plant cell walls for the establishment of feeding structures. Despite the ubiquity and apparent importance of this early defense response, relatively little is known about the underlying molecular mechanisms and cellular processes involved in the targeting and assembly of papillae. This review summarizes recent advances in our understanding of cell wall-associated defenses induced by pathogen perception as well as the impact of changes in cell wall polymers on interactions with pathogens and highlights significant unanswered questions driving future research in the area. PMID:22639669

  6. A Fungal Endoglucanase with Plant Cell Wall Extension Activity1

    PubMed Central

    Yuan, Sheng; Wu, Yajun; Cosgrove, Daniel J.

    2001-01-01

    We have identified a wall hydrolytic enzyme from Trichoderma reesei with potent ability to induce extension of heat-inactivated type I cell walls. It is a small (23-kD) endo-1,4-β-glucanase (Cel12A) belonging to glycoside hydrolase family 12. Extension of heat-inactivated walls from cucumber (Cucumis sativus cv Burpee Pickler) hypocotyls was induced by Cel12A after a distinct lag time and was accompanied by a large increase in wall plasticity and elasticity. Cel12A also increased the rate of stress relaxation of isolated walls at very short times (<200 ms; equivalent to reducing t0, a parameter that estimates the minimum relaxation time). Similar changes in wall plasticity and elasticity were observed in wheat (Triticum aestivum cv Pennmore Winter) coleoptile (type II) walls, which showed only a negligible extension in response to Cel12A treatment. Thus, Cel12A modifies both type I and II walls, but substantial extension is found only in type I walls. Cel12A has strong endo-glucanase activity against xyloglucan and (1→3,1→4)-β-glucan, but did not exhibit endo-xylanase, endo-mannase, or endo-galactanase activities. In terms of kinetics of action and effects on wall rheology, wall loosening by Cel12A differs qualitatively from the action by expansins, which induce wall extension by a non-hydrolytic polymer creep mechanism. The action by Cel12A mimics some of the changes in wall rheology found after auxin-induced growth. The strategy used here to identify Cel12A could be used to identify analogous plant enzymes that cause auxin-induced changes in cell wall rheology. PMID:11553760

  7. Hysteresis and precession of a swirling jet normal to a wall.

    PubMed

    Shtern, V; Mi, J

    2004-01-01

    Interaction of a swirling jet with a no-slip surface has striking features of fundamental and practical interest. Different flow states and transitions among them occur at the same conditions in combustors, vortex tubes, and tornadoes. The jet axis can undergo precession and bending in combustors; this precession enhances large-scale mixing and reduces emissions of NOx. To explore the mechanisms of these phenomena, we address conically similar swirling jets normal to a wall. In addition to the Serrin model of tornadolike flows, a new model is developed where the flow is singularity free on the axis. New analytical and numerical solutions of the Navier-Stokes equations explain occurrence of multiple states and show that hysteresis is a common feature of wall-normal vortices or swirling jets no matter where sources of motion are located. Then we study the jet stability with the aid of a new approach accounting for deceleration and nonparallelism of the base flow. An appropriate transformation of variables reduces the stability problem for this strongly nonparallel flow to a set of ordinary differential equations. A particular flow whose stability is studied in detail is a half-line vortex normal to a rigid plane-a model of a tornado and of a swirling jet issuing from a nozzle in a combustor. Helical counter-rotating disturbances appear to be first growing as Reynolds number increases. Disturbance frequency changes its sign along the neutral curve while the wave number remains positive. Short disturbance waves propagate downstream and long waves propagate upstream. This helical instability causes bending of the vortex axis and its precession-the effects observed in technological flows and in tornadoes.

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

    PubMed Central

    De Souza, Amanda P.; Kamei, Claire L. Alvim; Torres, Andres F.; 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 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

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

    DOE PAGES

    De Souza, Amanda P.; Kamei, Claire L. Alvim; Torres, Andres F.; ...

    2015-04-23

    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 theymore » 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. In conclusion, different genotypes of M. sinensis were shown to display distinct interactions among their cell wall components, which seem to influence cell wall hydrolysis.« less

  10. Arabidopsis Regenerating Protoplast: A Powerful Model System for Combining the Proteomics of Cell Wall Proteins and the Visualization of Cell Wall Dynamics

    PubMed Central

    Yokoyama, Ryusuke; Kuki, Hiroaki; Kuroha, Takeshi; Nishitani, Kazuhiko

    2016-01-01

    The development of a range of sub-proteomic approaches to the plant cell wall has identified many of the cell wall proteins. However, it remains difficult to elucidate the precise biological role of each protein and the cell wall dynamics driven by their actions. The plant protoplast provides an excellent means not only for characterizing cell wall proteins, but also for visualizing the dynamics of cell wall regeneration, during which cell wall proteins are secreted. It therefore offers a unique opportunity to investigate the de novo construction process of the cell wall. This review deals with sub-proteomic approaches to the plant cell wall through the use of protoplasts, a methodology that will provide the basis for further exploration of cell wall proteins and cell wall dynamics. PMID:28248244

  11. Plant expansins: diversity and interactions with plant cell walls

    PubMed Central

    Cosgrove, Daniel J.

    2015-01-01

    Expansins were discovered two decades ago as cell wall proteins that mediate acid-induced growth by catalyzing loosening of plant cell walls without lysis of wall polymers. In the interim our understanding of expansins has gotten more complex through bioinformatic analysis of expansin distribution and evolution, as well as through expression analysis, dissection of the upstream transcription factors regulating expression, and identification of additional classes of expansin by sequence and structural similarities. Molecular analyses of expansins from bacteria have identified residues essential for wall loosening activity and clarified the bifunctional nature of expansin binding to complex cell walls. Transgenic modulation of expansin expression modifies growth and stress physiology of plants, but not always in predictable and even understandable ways. PMID:26057089

  12. Dynamic microtubules and the texture of plant cell walls.

    PubMed

    Lloyd, Clive

    2011-01-01

    The relationship between microtubules and cell-wall texture has had a fitful history in which progress in one area has not been matched by progress in the other. For example, the idea that wall texture arises entirely from self-assembly, independently of microtubules, originated with electron microscopic analyses of fixed cells that gave no clue to the ability of microtubules to reorganize. Since then, live-cell studies have established the surprising dynamicity of plant microtubules involving collisions, changes in angle, parallelization, and rotation of microtubule tracks. Combined with proof that cellulose synthases do track along shifting microtubules, this offers more realistic models for the dynamic influence of microtubules on wall texture than could have been imagined in the electron microscopic era-the era from which most ideas on wall texture originate. This review revisits the classical literature on wall organization from the vantage point of current knowledge of microtubule dynamics.

  13. Plant expansins: diversity and interactions with plant cell walls.

    PubMed

    Cosgrove, Daniel J

    2015-06-01

    Expansins were discovered two decades ago as cell wall proteins that mediate acid-induced growth by catalyzing loosening of plant cell walls without lysis of wall polymers. In the interim our understanding of expansins has gotten more complex through bioinformatic analysis of expansin distribution and evolution, as well as through expression analysis, dissection of the upstream transcription factors regulating expression, and identification of additional classes of expansin by sequence and structural similarities. Molecular analyses of expansins from bacteria have identified residues essential for wall loosening activity and clarified the bifunctional nature of expansin binding to complex cell walls. Transgenic modulation of expansin expression modifies growth and stress physiology of plants, but not always in predictable or even understandable ways.

  14. Normal development, oncogenesis and programmed cell death.

    PubMed

    Liebermann, D A

    1998-09-10

    Meeting's Report -- June 2, 1998, Sugarload Estate Conference Center, Philadelphia, Pennsylvania, USA. A symposium on Normal Development, Oncogenesis and Programmed Cell Death, was held at the Sugarload Estate Conference Center, Philadelphia, Pennsylvania, USA sponsored by the Fels Cancer Institute, Temple University School of Medicine, with the support of the Alliance Pharmaceutical Corporation. The symposium was organized by Drs Dan A Liebermann and Barbara Hoffman at the Fels. Invited speakers included: Dr Andrei V Gudkov (University of Illinois) who started the symposium talking about 'New cellular factors modulating the tumor suppressor function of p53'; Dr Yuri Lazebnik (Cold Spring Harbor Laboratories) spoke about 'Caspases considered as enemies within'; Dr E Premkumar Reddy (Fels Institute, Temple University) talked about recent exciting findings in his laboratory regarding 'JAK-STATs dedicated signaling pathways'; Dr Michael Greenberg (Harvard University) spoke about 'Signal transduction pathways that regulate differentiation and survival in the developing nervous system'; Dr Richard Kolesnick's (Memorial Sloan-Kettering Cancer Center) talk has been focused at 'Stress signals for apoptosis, including Ceramide and c-Jun Kinase/Stress-activated Protein Kinase'; Dr Barbara Hoffman (Fels Institute, Temple University) described research, conducted in collaboration with Dr Dan A Liebermann, aimed at deciphering the roles of 'myc, myb, and E2F as negative regulators of terminal differentiation', using hematopoietic cells as model system. Dr Daniel G Tenen (Harvard Medical School), described studies aimed at understanding the 'Regulation of hematopoietic cell development by lineage specific transcription regulators'. Dr George C Prendergast (The Wistar Institute) talked about the 'Myc-Bin1 signaling pathway in cell death and differentiation. Dr Ruth J Muschel (University of Pennsylvania) spoke about work, conducted in collaboration with Dr WG McKenna, aimed at

  15. Measurement of pectin methylation in plant cell walls

    SciTech Connect

    McFeeters, R.F.; Armstrong, S.A.

    1984-01-01

    A procedure was developed to measure the degree of pectin methylation in small samples of isolated cell walls from nonlignified plant tissues or pectin solutions. Galacturonic acid was determined colorimetrically with the 3,5-dimethylphenol reagent. Methylation was measured by base hydrolysis of galacturonic acid methyl esters, followed by gas chromatographic determination of released methanol. Estimates of the precision of analysis of pectin and cell wall samples were made. The coefficient of variation for estimates of the pectin esterification in cell walls isolated from 10-g samples of cucumber tissue ranged from 7.7 to 13.2%.

  16. Probing (macro)molecular transport through cell walls.

    PubMed

    Kilcher, Giona; Delneri, Daniela; Duckham, Craig; Tirelli, Nicola

    2008-01-01

    We here report a study on the passive permeability of hydrophobic probes through the cell wall of Saccharomyces cerevisiae. In this study we have prepared a series of fluorescent probes with similar chemical composition and molecular weight ranging from a few hundreds to a few thousands of g mol(-1). Their permeation into the cell body exhibits a clear MW cut-off and the underlying mechanism is governed by the permeation of individual molecules rather than aggregates. We also show that it is possible to reversibly alter the cell wall permeation properties without compromising the essence of its structure, by modifying the polarity/dielectric constant of the wall through solvent exchange.

  17. Hygroscopic swelling and shrinkage of latewood cell wall micropillars reveal ultrastructural anisotropy.

    PubMed

    Rafsanjani, Ahmad; Stiefel, Michael; Jefimovs, Konstantins; Mokso, Rajmund; Derome, Dominique; Carmeliet, Jan

    2014-06-06

    We document the hygroscopic swelling and shrinkage of the central and the thickest secondary cell wall layer of wood (named S2) in response to changes in environmental humidity using synchrotron radiation-based phase contrast X-ray tomographic nanoscopy. The S2 layer is a natural fibre-reinforced nano-composite polymer and is strongly reactive to water. Using focused ion beam, micropillars with a cross section of few micrometres are fabricated from the S2 layer of the latewood cell walls of Norway spruce softwood. The thin neighbouring cell wall layers are removed to prevent hindering or restraining of moisture-induced deformation during swelling or shrinkage. The proposed experiment intended to get further insights into the microscopic origin of the anisotropic hygro-expansion of wood. It is found that the swelling/shrinkage strains are highly anisotropic in the transverse plane of the cell wall, larger in the normal than in the direction parallel to the cell wall's thickness. This ultrastructural anisotropy may be due to the concentric lamellation of the cellulose microfibrils as the role of the cellulose microfibril angle in the transverse swelling anisotropy is negligible. The volumetric swelling of the cell wall material is found to be substantially larger than the one of wood tissues within the growth ring and wood samples made of several growth rings. The hierarchical configuration in wood optimally increases its dimensional stability in response to a humid environment with higher scales of complexity.

  18. Hygroscopic swelling and shrinkage of latewood cell wall micropillars reveal ultrastructural anisotropy

    PubMed Central

    Rafsanjani, Ahmad; Stiefel, Michael; Jefimovs, Konstantins; Mokso, Rajmund; Derome, Dominique; Carmeliet, Jan

    2014-01-01

    We document the hygroscopic swelling and shrinkage of the central and the thickest secondary cell wall layer of wood (named S2) in response to changes in environmental humidity using synchrotron radiation-based phase contrast X-ray tomographic nanoscopy. The S2 layer is a natural fibre-reinforced nano-composite polymer and is strongly reactive to water. Using focused ion beam, micropillars with a cross section of few micrometres are fabricated from the S2 layer of the latewood cell walls of Norway spruce softwood. The thin neighbouring cell wall layers are removed to prevent hindering or restraining of moisture-induced deformation during swelling or shrinkage. The proposed experiment intended to get further insights into the microscopic origin of the anisotropic hygro-expansion of wood. It is found that the swelling/shrinkage strains are highly anisotropic in the transverse plane of the cell wall, larger in the normal than in the direction parallel to the cell wall's thickness. This ultrastructural anisotropy may be due to the concentric lamellation of the cellulose microfibrils as the role of the cellulose microfibril angle in the transverse swelling anisotropy is negligible. The volumetric swelling of the cell wall material is found to be substantially larger than the one of wood tissues within the growth ring and wood samples made of several growth rings. The hierarchical configuration in wood optimally increases its dimensional stability in response to a humid environment with higher scales of complexity. PMID:24671938

  19. Cell Wall Metabolism in Response to Abiotic Stress.

    PubMed

    Le Gall, Hyacinthe; Philippe, Florian; Domon, Jean-Marc; Gillet, Françoise; Pelloux, Jérôme; Rayon, Catherine

    2015-02-16

    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.

  20. Cell Wall Metabolism in Response to Abiotic Stress

    PubMed Central

    Gall, Hyacinthe Le; Philippe, Florian; Domon, Jean-Marc; Gillet, Françoise; Pelloux, Jérôme; Rayon, Catherine

    2015-01-01

    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. PMID:27135320

  1. An Arabidopsis gene regulatory network for secondary cell wall synthesis

    SciTech Connect

    Taylor-Teeples, M.; Lin, L.; de Lucas, M.; Turco, G.; Toal, T. W.; Gaudinier, A.; Young, N. F.; Trabucco, G. M.; Veling, M. T.; Lamothe, R.; Handakumbura, P. P.; Xiong, G.; Wang, C.; Corwin, J.; Tsoukalas, A.; Zhang, L.; Ware, D.; Pauly, M.; Kliebenstein, D. J.; Dehesh, K.; Tagkopoulos, I.; Breton, G.; Pruneda-Paz, J. L.; Ahnert, S. E.; Kay, S. A.; Hazen, S. P.; Brady, S. M.

    2014-12-24

    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 transcriptional regulation of synthesis for each polymer is complex and vital to cell function. A regulatory hierarchy of developmental switches has been proposed, although the full complement of regulators remains unknown. In this paper, we present a protein–DNA network between Arabidopsis thaliana transcription factors and secondary cell wall metabolic genes with gene expression regulated by a series of feed-forward loops. This model allowed us to develop and validate new hypotheses about secondary wall gene regulation under abiotic stress. Distinct stresses are able to perturb targeted genes to potentially promote functional adaptation. Finally, these interactions will serve as a foundation for understanding the regulation of a complex, integral plant component.

  2. Magnetic domain wall conduits for single cell applications.

    PubMed

    Donolato, M; Torti, A; Kostesha, N; Deryabina, M; Sogne, E; Vavassori, P; Hansen, M F; Bertacco, R

    2011-09-07

    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 walls technology in lab-on-chip systems devoted to accurate individual cell trapping and manipulation.

  3. On the growth of walled cells: From shells to vesicles.

    NASA Astrophysics Data System (ADS)

    Boudaoud, Arezki

    2003-03-01

    The growth of isolated walled cells is investigated. Examples of such cells range from bacteria to giant algae, and include cochlear hair, plant root hair, fungi and yeast cells. They are modeled as elastic shells inflated by a liquid. Cell growth is driven by fluid pressure and is similar to a plastic deformation of the wall. The requirement of mechanical equilibrium leads to two new scaling laws for cell size that are in quantitative agreement with the compiled biological data. Given these results, possible shapes for growing cells are computed by analogy with those of vesicle membranes.

  4. Growth of Walled Cells: From Shells to Vesicles

    NASA Astrophysics Data System (ADS)

    Boudaoud, Arezki

    2003-07-01

    The growth of isolated walled cells is investigated. Examples of such cells range from bacteria to giant algae, and include cochlear hair, plant root hair, fungi, and yeast cells. They are modeled as elastic shells containing a liquid. Cell growth is driven by fluid pressure and is is similar to a plastic deformation of the wall. The requirement of mechanical equilibrium leads to two new scaling laws for cell size that are in quantitative agreement with the compiled biological data. Given these results, possible shapes for growing cells are computed by analogy with those of vesicle membranes.

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

    PubMed Central

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

    2014-01-01

    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 cells to SDS after salt treatment, while overexpression of SCW11 results in higher sensitivity. In addition, salt stress in ρ0 cells induces high levels of reactive oxygen species (ROS), which further damages the cell wall, causing cells to become more sensitive towards the cell wall-perturbing agent. PMID:28357227

  6. A formin-nucleated actin aster concentrates cell wall hydrolases for cell fusion in fission yeast

    PubMed Central

    Dudin, Omaya; Bendezú, Felipe O.; Groux, Raphael; Laroche, Thierry; Seitz, Arne

    2015-01-01

    Cell–cell fusion is essential for fertilization. For fusion of walled cells, the cell wall must be degraded at a precise location but maintained in surrounding regions to protect against lysis. In fission yeast cells, the formin Fus1, which nucleates linear actin filaments, is essential for this process. In this paper, we show that this formin organizes a specific actin structure—the actin fusion focus. Structured illumination microscopy and live-cell imaging of Fus1, actin, and type V myosins revealed an aster of actin filaments whose barbed ends are focalized near the plasma membrane. Focalization requires Fus1 and type V myosins and happens asynchronously always in the M cell first. Type V myosins are essential for fusion and concentrate cell wall hydrolases, but not cell wall synthases, at the fusion focus. Thus, the fusion focus focalizes cell wall dissolution within a broader cell wall synthesis zone to shift from cell growth to cell fusion. PMID:25825517

  7. New chemical tools to probe cell wall biosynthesis in bacteria.

    PubMed

    Gale, Robert T; Brown, Eric D

    2015-10-01

    Some of the most successful drugs in the antibiotic pharmacopeia are those that inhibit bacterial cell wall biosynthesis. However, the worldwide spread of bacterial antibiotic resistance has eroded the clinical efficacy of these drugs and the antibiotic pipeline continues to be lean as drug discovery programs struggle to bring new agents to the clinic. Nevertheless, cell wall biogenesis remains a high interest and celebrated target. Recent advances in the preparation of chemical probes and biosynthetic intermediates provide the tools necessary to better understand cell wall assembly. Likewise, these tools offer new opportunities to identify and evaluate novel biosynthetic inhibitors. This review aims to highlight these advancements and to provide context for their utility as innovative new tools to study cell wall biogenesis and for antibacterial drug discovery.

  8. Functional Analysis of Cellulose and Xyloglucan in the Walls of Stomatal Guard Cells of Arabidopsis.

    PubMed

    Rui, Yue; Anderson, Charles T

    2016-03-01

    Stomatal guard cells are pairs of specialized epidermal cells that control water and CO2 exchange between the plant and the environment. To fulfill the functions of stomatal opening and closure that are driven by changes in turgor pressure, guard cell walls must be both strong and flexible, but how the structure and dynamics of guard cell walls enable stomatal function remains poorly understood. To address this question, we applied cell biological and genetic analyses to investigate guard cell walls and their relationship to stomatal function in Arabidopsis (Arabidopsis thaliana). Using live-cell spinning disk confocal microscopy, we measured the motility of cellulose synthase (CESA)-containing complexes labeled by green fluorescent protein (GFP)-CESA3 and observed a reduced proportion of GFP-CESA3 particles colocalizing with microtubules upon stomatal closure. Imaging cellulose organization in guard cells revealed a relatively uniform distribution of cellulose in the open state and a more fibrillar pattern in the closed state, indicating that cellulose microfibrils undergo dynamic reorganization during stomatal movements. In cesa3(je5) mutants defective in cellulose synthesis and xxt1 xxt2 mutants lacking the hemicellulose xyloglucan, stomatal apertures, changes in guard cell length, and cellulose reorganization were aberrant during fusicoccin-induced stomatal opening or abscisic acid-induced stomatal closure, indicating that sufficient cellulose and xyloglucan are required for normal guard cell dynamics. Together, these results provide new insights into how guard cell walls allow stomata to function as responsive mediators of gas exchange at the plant surface.

  9. A versatile strategy for grafting polymers to wood cell walls.

    PubMed

    Keplinger, T; Cabane, E; Chanana, M; Hass, P; Merk, V; Gierlinger, N; Burgert, I

    2015-01-01

    The hierarchical structure of wood is composed of a cellulose skeleton of high structural order at various length scales. At the nanoscale and microscale the specific structural features of the cells and cell walls result in a lightweight structure with an anisotropic material profile of excellent mechanical performance. By being able to specifically functionalize wood at the level of cell and cell walls one can insert new properties and inevitably upscale them along the intrinsic hierarchical structure, to a level of large-scale engineering materials applications. For this purpose, however, precise control of the spatial distribution of the modifying substances in the complex wood structure is needed. Here we demonstrate a method to insert methacryl groups into wood cell walls using two different chemistry routes. By using these methacryl groups as the anchor points for grafting, various polymers can be inserted into the wood structure. Strikingly, depending on the methacryl precursor, the spatial distribution of the polymer differs strongly. As a proof of concept we grafted polystyrene as a model compound in the second modification step. In the case of methacryloyl chloride the polymer was located mainly at the interface between the cell lumina and the cell wall covering the inner surface of the cells and being traceable up to 2-3 μm in the cell wall, whereas in the case of methacrylic anhydride the polymer was located inside the whole cell wall. Scanning electron microscopy, Fourier transform infrared spectroscopy and especially Raman spectroscopy were used for an in-depth analysis of the modified wood at the cell wall level.

  10. Cell wall polysaccharides from fern leaves: evidence for a mannan-rich Type III cell wall in Adiantum raddianum.

    PubMed

    Silva, Giovanna B; Ionashiro, Mari; Carrara, Thalita B; Crivellari, Augusto C; Tiné, Marco A S; Prado, Jefferson; Carpita, Nicholas C; Buckeridge, Marcos S

    2011-12-01

    Primary cell walls from plants are composites of cellulose tethered by cross-linking glycans and embedded in a matrix of pectins. Cell wall composition varies between plant species, reflecting in some instances the evolutionary distance between them. In this work the monosaccharide compositions of isolated primary cell walls of nine fern species and one lycophyte were characterized and compared with those from Equisetum and an angiosperm dicot. The relatively high abundance of mannose in these plants suggests that mannans may constitute the major cross-linking glycan in the primary walls of pteridophytes and lycophytes. Pectin-related polysaccharides contained mostly rhamnose and uronic acids, indicating the presence of rhamnogalacturonan I highly substituted with galactose and arabinose. Structural and fine-structural analyses of the hemicellulose fraction of leaves of Adiantum raddianum confirmed this hypothesis. Linkage analysis showed that the mannan contains mostly 4-Man with very little 4,6-Man, indicating a low percentage of branching with galactose. Treatment of the mannan-rich fractions with endo-β-mannanase produced characteristic mannan oligosaccharides. Minor amounts of xyloglucan and xylans were also detected. These data and those of others suggest that all vascular plants contain xyloglucans, arabinoxylans, and (gluco)mannans, but in different proportions that define cell wall types. Whereas xyloglucan and pectin-rich walls define Type I walls of dicots and many monocots, arabinoxylans and lower proportion of pectin define the Type II walls of commelinoid monocots. The mannan-rich primary walls with low pectins of many ferns and a lycopod indicate a fundamentally different wall type among land plants, the Type III wall.

  11. An improved protocol to study the plant cell wall proteome

    PubMed Central

    Printz, Bruno; Dos Santos Morais, Raphaël; Wienkoop, Stefanie; Sergeant, Kjell; Lutts, Stanley; Hausman, Jean-Francois; Renaut, Jenny

    2015-01-01

    Cell wall proteins were extracted from alfalfa stems according to a three-steps extraction procedure using sequentially CaCl2, EGTA, and LiCl-complemented buffers. The efficiency of this protocol for extracting cell wall proteins was compared with the two previously published methods optimized for alfalfa stem cell wall protein analysis. Following LC-MS/MS analysis the three-steps extraction procedure resulted in the identification of the highest number of cell wall proteins (242 NCBInr identifiers) and gave the lowest percentage of non-cell wall proteins (about 30%). However, the three protocols are rather complementary than substitutive since 43% of the identified proteins were specific to one protocol. This three-step protocol was therefore selected for a more detailed proteomic characterization using 2D-gel electrophoresis. With this technique, 75% of the identified proteins were shown to be fraction-specific and 72.7% were predicted as belonging to the cell wall compartment. Although, being less sensitive than LC-MS/MS approaches in detecting and identifying low-abundant proteins, gel-based approaches are valuable tools for the differentiation and relative quantification of protein isoforms and/or modified proteins. In particular isoforms, having variations in their amino-acid sequence and/or carrying different N-linked glycan chains were detected and characterized. This study highlights how the extracting protocols as well as the analytical techniques devoted to the study of the plant cell wall proteome are complementary and how they may be combined to elucidate the dynamism of the plant cell wall proteome in biological studies. Data are available via ProteomeXchange with identifier PXD001927. PMID:25914713

  12. Polysaccharide-degrading Enzymes are Unable to Attack Plant Cell Walls without Prior Action by a "Wall-modifying Enzyme".

    PubMed

    Karr, A L; Albersheim, P

    1970-07-01

    A study of the degradation of plant cell walls by the mixture of enzymes present in Pectinol R-10 is described. A "wall-modifying enzyme" has been purified from this mixture by a combination of diethylaminoethyl cellulose, Bio Gel P-100, and carboxymethyl cellulose chromatography. Treatment of cell walls with the "wall-modifying enzyme" is shown to be a necessary prerequisite to wall degradation catalyzed by a mixture of polysaccharide-degrading enzymes prepared from Pectinol R-10 or by an alpha-galactosidase secreted by the pathogenic fungus Colletotrichum lindemuthianum. The action of the "wall-modifying enzyme" on cell walls is shown to result in both a release of water-soluble, 70% ethanol-insoluble polymers and an alteration of the residual cell wall. A purified preparation of the "wall-modifying enzyme" is unable to degrade a wide variety of polysaccharide, glycoside, and peptide substrates. However, the purified preparation of wall-modifying enzyme has a limited ability to degrade polygalacturonic acid. The fact that polygalacturonic acid inhibits the ability of the "wall-modifying enzyme" to affect cell walls suggests that the "wall-modifying enzyme" may be responsible for the limited polygalacturonic acid-degrading activity present in the purified preparation. The importance of a wall-modifying enzyme in developmental processes and in pathogenesis is discussed.

  13. Tubulin perturbation leads to unexpected cell wall modifications and affects stomatal behaviour in Populus

    PubMed Central

    Swamy, Prashant S.; Hu, Hao; Pattathil, Sivakumar; Maloney, Victoria J.; Xiao, Hui; Xue, Liang-Jiao; Chung, Jeng-Der; Johnson, Virgil E.; Zhu, Yingying; Peter, Gary F.; Hahn, Michael G.; Mansfield, Shawn D.; Harding, Scott A.; Tsai, Chung-Jui

    2015-01-01

    Cortical microtubules are integral to plant morphogenesis, cell wall synthesis, and stomatal behaviour, presumably by governing cellulose microfibril orientation. Genetic manipulation of tubulins often leads to abnormal plant development, making it difficult to probe additional roles of cortical microtubules in cell wall biogenesis. Here, it is shown that expressing post-translational C-terminal modification mimics of α-tubulin altered cell wall characteristics and guard cell dynamics in transgenic Populus tremula x alba that otherwise appear normal. 35S promoter-driven transgene expression was high in leaves but unusually low in xylem, suggesting high levels of tubulin transgene expression were not tolerated in wood-forming tissues during regeneration of transformants. Cellulose, hemicellulose, and lignin contents were unaffected in transgenic wood, but expression of cell wall-modifying enzymes, and extractability of lignin-bound pectin and xylan polysaccharides were increased in developing xylem. The results suggest that pectin and xylan polysaccharides deposited early during cell wall biogenesis are more sensitive to subtle tubulin perturbation than cellulose and matrix polysaccharides deposited later. Tubulin perturbation also affected guard cell behaviour, delaying drought-induced stomatal closure as well as light-induced stomatal opening in leaves. Pectins have been shown to confer cell wall flexibility critical for reversible stomatal movement, and results presented here are consistent with microtubule involvement in this process. Taken together, the data show the value of growth-compatible tubulin perturbations for discerning microtubule functions, and add to the growing body of evidence for microtubule involvement in non-cellulosic polysaccharide assembly during cell wall biogenesis. PMID:26246616

  14. Tubulin perturbation leads to unexpected cell wall modifications and affects stomatal behaviour in Populus

    DOE PAGES

    Swamy, Prashant S.; Hu, Hao; Pattathil, Sivakumar; ...

    2015-08-05

    Cortical microtubules are integral to plant morphogenesis, cell wall synthesis, and stomatal behaviour, presumably by governing cellulose microfibril orientation. Genetic manipulation of tubulins often leads to abnormal plant development, making it difficult to probe additional roles of cortical microtubules in cell wall biogenesis. Here, it is shown that expressing post-translational C-terminal modification mimics of α-tubulin altered cell wall characteristics and guard cell dynamics in transgenic Populus tremula x alba that otherwise appear normal. 35S promoter-driven transgene expression was high in leaves but unusually low in xylem, suggesting high levels of tubulin transgene expression were not tolerated in wood-forming tissues duringmore » regeneration of transformants. Cellulose, hemicellulose, and lignin contents were unaffected in transgenic wood, but expression of cell wall-modifying enzymes, and extractability of lignin-bound pectin and xylan polysaccharides were increased in developing xylem. The results suggest that pectin and xylan polysaccharides deposited early during cell wall biogenesis are more sensitive to subtle tubulin perturbation than cellulose and matrix polysaccharides deposited later. Tubulin perturbation also affected guard cell behaviour, delaying drought-induced stomatal closure as well as light-induced stomatal opening in leaves. Pectins have been shown to confer cell wall flexibility critical for reversible stomatal movement, and results presented here are consistent with microtubule involvement in this process. In conclusion, taken together, the data show the value of growth-compatible tubulin perturbations for discerning microtubule functions, and add to the growing body of evidence for microtubule involvement in non-cellulosic polysaccharide assembly during cell wall biogenesis.« less

  15. Pbx Proteins in Cryptococcus neoformans Cell Wall Remodeling and Capsule Assembly

    PubMed Central

    Kumar, Pardeep; Heiss, Christian; Santiago-Tirado, Felipe H.; Black, Ian; Azadi, Parastoo

    2014-01-01

    The cryptococcal capsule is a critical virulence factor of an important pathogen, but little is known about how it is associated with the cell or released into the environment. Two mutants lacking PBX1 and PBX2 were found to shed reduced amounts of the capsule polysaccharide glucuronoxylomannan (GXM). Nuclear magnetic resonance, composition, and physical analyses showed that the shed material was of normal mass but was slightly enriched in xylose. In contrast to previous reports, this material contained no glucose. Notably, the capsule fibers of pbxΔ mutant cells grown under capsule-inducing conditions were present at a lower than usual density and were loosely attached to the cell wall. Mutant cell walls were also defective, as indicated by phenotypes including abnormal cell morphology, reduced mating filamentation, and altered cell integrity. All observed phenotypes were shared between the two mutants and exacerbated in a double mutant. Consistent with a role in surface glycan synthesis, the Pbx proteins localized to detergent-resistant membrane domains. These results, together with the sequence motifs in the Pbx proteins, suggest that Pbx1 and Pbx2 are redundant proteins that act in remodeling the cell wall to maintain normal cell morphology and precursor availability for other glycan synthetic processes. Their absence results in aberrant cell wall growth and metabolic imbalance, which together impact cell wall and capsule synthesis, cell morphology, and capsule association. The surface changes also lead to increased engulfment by host phagocytes, consistent with the lack of virulence of pbx mutants in animal models. PMID:24585882

  16. The Permeability of Plant Cell Walls as Measured by Gel Filtration Chromatography

    NASA Astrophysics Data System (ADS)

    Tepeer, Mark; Taylor, Iain E. P.

    1981-08-01

    The permeability of plant cell walls to macromolecules may limit the ability of enzymes to alter the biochemical and physical properties of the wall. Proteins of molecular weight up to 60,000 can permeate a substantial portion of the cell wall. Measurements of wall permeability in which cells are exposed to hypertonic solutions of macromolecules may seriously underestimate wall permeability.

  17. Characterization and Localization of Insoluble Organic Matrices Associated with Diatom Cell Walls: Insight into Their Roles during Cell Wall Formation

    PubMed Central

    Tesson, Benoit; Hildebrand, Mark

    2013-01-01

    Organic components associated with diatom cell wall silica are important for the formation, integrity, and function of the cell wall. Polysaccharides are associated with the silica, however their localization, structure, and function remain poorly understood. We used imaging and biochemical approaches to describe in detail characteristics of insoluble organic components associated with the cell wall in 5 different diatom species. Results show that an insoluble organic matrix enriched in mannose, likely the diatotepum, is localized on the proximal surface of the silica cell wall. We did not identify any organic matrix embedded within the silica. We also identified a distinct material consisting of glucose polymer with variable localization depending on the species. In some species this component was directly involved in the morphogenesis of silica structure while in others it appeared to be only a structural component of the cell wall. A novel glucose-rich structure located between daughter cells during division was also identified. This work for the first time correlates the structure, composition, and localization of insoluble organic matrices associated with diatom cell walls. Additionally we identified a novel glucose polymer and characterized its role during silica structure formation. PMID:23626714

  18. Significant quantities of the glycolytic enzyme phosphoglycerate mutase are present in the cell wall of yeast Saccharomyces cerevisiae.

    PubMed Central

    Motshwene, Precious; Brandt, Wolf; Lindsey, George

    2003-01-01

    NaOH was used to extract proteins from the cell walls of the yeast Saccharomyces cerevisiae. This treatment was shown not to disrupt yeast cells, as NaOH-extracted cells displayed a normal morphology upon electron microscopy. Moreover, extracted and untreated cells had qualitatively similar protein contents upon disruption. When yeast was grown in the presence of 1 M mannitol, two proteins were found to be present at an elevated concentration in the cell wall. These were found to be the late-embryogenic-abundant-like protein heat-shock protein 12 and the glycolytic enzyme phosphoglycerate mutase. The presence of phosphoglycerate mutase in the cell wall was confirmed by immunocytochemical analysis. Not only was the phosphoglycerate mutase in the yeast cell wall found to be active, but whole yeast cells were also able to convert 3-phosphoglycerate in the medium into ethanol, provided that the necessary cofactors were present. PMID:12238949

  19. Role of the plant cell wall in gravity resistance.

    PubMed

    Hoson, Takayuki; Wakabayashi, Kazuyuki

    2015-04-01

    Gravity resistance, mechanical resistance to the gravitational force, is a principal graviresponse in plants, comparable to gravitropism. The cell wall is responsible for the final step of gravity resistance. The gravity signal increases the rigidity of the cell wall via the accumulation of its constituents, polymerization of certain matrix polysaccharides due to the suppression of breakdown, stimulation of cross-link formation, and modifications to the wall environment, in a wide range of situations from microgravity in space to hypergravity. Plants thus develop a tough body to resist the gravitational force via an increase in cell wall rigidity and the modification of growth anisotropy. The development of gravity resistance mechanisms has played an important role in the acquisition of responses to various mechanical stresses and the evolution of land plants.

  20. Ultrastructure and Composition of the Nannochloropsis gaditana Cell Wall

    PubMed Central

    Scholz, Matthew J.; Weiss, Taylor L.; Jinkerson, Robert E.; Jing, Jia; Roth, Robyn; Goodenough, Ursula; Posewitz, Matthew C.

    2014-01-01

    Marine algae of the genus Nannochloropsis are promising producers of biofuel precursors and nutraceuticals and are also harvested commercially for aquaculture feed. We have used quick-freeze, deep-etch electron microscopy, Fourier transform infrared spectroscopy, and carbohydrate analyses to characterize the architecture of the Nannochloropsis gaditana (strain CCMP 526) cell wall, whose recalcitrance presents a significant barrier to biocommodity extraction. The data indicate a bilayer structure consisting of a cellulosic inner wall (∼75% of the mass balance) protected by an outer hydrophobic algaenan layer. Cellulase treatment of walls purified after cell lysis generates highly enriched algaenan preparations without using the harsh chemical treatments typically used in algaenan isolation and characterization. Nannochloropsis algaenan was determined to comprise long, straight-chain, saturated aliphatics with ether cross-links, which closely resembles the cutan of vascular plants. Chemical identification of >85% of the isolated cell wall mass is detailed, and genome analysis is used to identify candidate biosynthetic enzymes. PMID:25239976

  1. Characterizing visible and invisible cell wall mutant phenotypes.

    PubMed

    Carpita, Nicholas C; McCann, Maureen C

    2015-07-01

    About 10% of a plant's genome is devoted to generating the protein machinery to synthesize, remodel, and deconstruct the cell wall. High-throughput genome sequencing technologies have enabled a reasonably complete inventory of wall-related genes that can be assembled into families of common evolutionary origin. Assigning function to each gene family member has been aided immensely by identification of mutants with visible phenotypes or by chemical and spectroscopic analysis of mutants with 'invisible' phenotypes of modified cell wall composition and architecture that do not otherwise affect plant growth or development. This review connects the inference of gene function on the basis of deviation from the wild type in genetic functional analyses to insights provided by modern analytical techniques that have brought us ever closer to elucidating the sequence structures of the major polysaccharide components of the plant cell wall.

  2. Motion of red blood cells near microvessel walls: effects of a porous wall layer

    PubMed Central

    HARIPRASAD, DANIEL S.; SECOMB, TIMOTHY W.

    2013-01-01

    A two-dimensional model is used to simulate the motion and deformation of a single mammalian red blood cell (RBC) flowing close to the wall of a microvessel, taking into account the effects of a porous endothelial surface layer (ESL) lining the vessel wall. Migration of RBCs away from the wall leads to the formation of a cell-depleted layer near the wall, which has a large effect on the resistance to blood flow in microvessels. The objective is to examine the mechanical factors causing this migration, including the effects of the ESL. The vessel is represented as a straight parallel-sided channel. The RBC is represented as a set of interconnected viscoelastic elements, suspended in plasma, a Newtonian fluid. The ESL is represented as a porous medium, and plasma flow in the layer is computed using the Brinkman approximation. It is shown that an initially circular cell positioned close to the ESL in a shear flow is deformed into an asymmetric shape. This breaking of symmetry leads to migration away from the wall. With increasing hydraulic resistivity of the layer, the rate of lateral migration increases. It is concluded that mechanical interactions of RBCs flowing in microvessels with a porous wall layer may reduce the rate of lateral migration and hence reduce the width of the cell-depleted zone external to the ESL, relative to the cell-depleted zone that would be formed if the interface between the ESL and free-flowing plasma were replaced by an impermeable boundary. PMID:23493820

  3. Determining the polysaccharide composition of plant cell walls.

    PubMed

    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.

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

    PubMed Central

    Feiz, Leila; Irshad, Muhammad; Pont-Lezica, Rafael F; Canut, Hervé; Jamet, Elisabeth

    2006-01-01

    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 new cell wall

  5. Electron microscopy of Staphylococcus aureus cell wall lysis.

    PubMed

    Virgilio, R; González, C; Muñoz, N; Mendoza, S

    1966-05-01

    Virgilio, Rafael (Escuela de Química y Farmacia, Universidad de Chile, Santiago, Chile), C. González, Nubia Muñoz, and Silvia Mendoza. Electron microscopy of Staphylococcus aureus cell wall lysis. J. Bacteriol. 91:2018-2024. 1966.-A crude suspension of Staphylococcus aureus cell walls (strain Cowan III) in buffer solution was shown by electron microscopy to lyse slightly after 16 hr, probably owing to the action of autolysin. The lysis was considerably faster and more intense after the addition of lysozyme. A remarkable reduction in thickness and rigidity of the cell walls, together with the appearance of many irregular protrusions in their outlines, was observed after 2 hr; after 16 hr, there remained only a few recognizable cell wall fragments but many residual particulate remnants. When autolysin was previously inactivated by trypsin, there was a complete inhibition of the lytic action of lysozyme; on the other hand, when autolysin was inactivated by heat and lysozyme was added, a distinct decrease in the thickness of the cell walls was observed, but there was no destruction of the walls. The lytic action of lysozyme, after treatment with hot 5% trichloroacetic acid, gave rise to a marked dissolution of the structure of the cell walls, which became lost against the background, without, however, showing ostensible alteration of wall outlines. From a morphological point of view, the lytic action of autolysin plus lysozyme was quite different from that of trichloroacetic acid plus lysozyme, as shown by electron micrographs, but in both cases it was very intense. This would suggest different mechanisms of action for these agents.

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

    PubMed

    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.

  7. Production Model Press for the Preparation of Bacterial Cell Walls

    PubMed Central

    Perrine, T. D.; Ribi, E.; Maki, W.; Miller, B.; Oertli, E.

    1962-01-01

    A modification of the apparatus previously described permits the preparation of cell walls in quantity. This consists of a heavy duty, double-acting hydraulic press with motor-driven pump, and a superstrength alloy steel pressure cell which is corrosion resistant. Liquid cooling of the jet is substituted for the previously used gas cooling to minimize aerosol formation and to facilitate subsequent treatment of the products. The device produces cell walls of excellent quality in good yield. The pressure cell has been used satisfactorily up to about 60,000 psi. Design details are given. Images FIG. 1 FIG. 2 FIG. 6 PMID:14485524

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

    PubMed

    Barbacci, Adelin; Lahaye, Marc; Magnenet, Vincent

    2013-01-01

    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.

  9. A widespread family of bacterial cell wall assembly proteins

    PubMed Central

    Kawai, Yoshikazu; Marles-Wright, Jon; Cleverley, Robert M; Emmins, Robyn; Ishikawa, Shu; Kuwano, Masayoshi; Heinz, Nadja; Bui, Nhat Khai; Hoyland, Christopher N; Ogasawara, Naotake; Lewis, Richard J; Vollmer, Waldemar; Daniel, Richard A; Errington, Jeff

    2011-01-01

    Teichoic acids and acidic capsular polysaccharides are major anionic cell wall polymers (APs) in many bacteria, with various critical cell functions, including maintenance of cell shape and structural integrity, charge and cation homeostasis, and multiple aspects of pathogenesis. We have identified the widespread LytR–Cps2A–Psr (LCP) protein family, of previously unknown function, as novel enzymes required for AP synthesis. Structural and biochemical analysis of several LCP proteins suggest that they carry out the final step of transferring APs from their lipid-linked precursor to cell wall peptidoglycan (PG). In Bacillus subtilis, LCP proteins are found in association with the MreB cytoskeleton, suggesting that MreB proteins coordinate the insertion of the major polymers, PG and AP, into the cell wall. PMID:21964069

  10. Plant metabolism and cell wall formation in space (microgravity) and on Earth

    NASA Technical Reports Server (NTRS)

    Lewis, Norman G.

    1994-01-01

    Variations in cell wall chemistry provide vascular plants with the ability to withstand gravitational forces, as well as providing facile mechanisms for correctional responses to various gravitational stimuli, e.g., in reaction wood formation. A principal focus of our current research is to precisely and systematically dissect the essentially unknown mechanism(s) of vascular plant cell wall assembly, particularly with respect to formation of its phenolic constituents, i.e., lignins and suberins, and how gravity impacts upon these processes. Formation of these phenolic polymers is of particular interest, since it appears that elaboration of their biochemical pathways was essential for successful land adaptation. By extrapolation, we are also greatly intrigued as to how the microgravity environment impacts upon 'normal' cell wall assembly mechanisms/metabolism.

  11. The composition of the cell wall of Aspergillus niger

    PubMed Central

    Johnston, I. R.

    1965-01-01

    1. The cell-wall composition of Aspergillus niger has been investigated. Analysis shows the presence of six sugars, glucose, galactose, mannose, arabinose, glucosamine and galactosamine, all in the d-configuration, except that a small amount of l-galactose may be present. Sixteen common amino acids are also present. 2. The wall consists chiefly of neutral carbohydrate (73–83%) and hexosamine (9–13%), with smaller amounts of lipid (2–7%), protein (0·5–2·5%) and phosphorus (less than 0·1%). The acetyl content (3·0–3·4%) corresponds to 1·0mole/mole of hexosamine nitrogen. 3. A fractionation of the cell-wall complex was achieved, with or without a preliminary phenol extraction, by using n-sodium hydroxide. Though this caused some degradation, 30–60% of the wall could be solubilized (depending on the preparation). Analyses on several fractions suggest that fractionation procedures bring about some separation of components although not in a clear-cut fashion. 4. Cell-wall preparations were shown to yield a fraction having [α]D approx. +240° (in n-sodium hydroxide) and consisting largely of glucose. This was separated into two subfractions, one of which had [α]D+281° (in n-sodium hydroxide) and had properties resembling the polysaccharide nigeran; the other had [α]D +231° (in n-sodium hydroxide). It is suggested that nigeran is a cell-wall component. PMID:5862404

  12. Control of Cell Wall Extensibility during Pollen Tube Growth

    PubMed Central

    Hepler, Peter K.

    2013-01-01

    In this review, we address the question of how the tip-growing pollen tube achieves its rapid rate of elongation while maintaining an intact cell wall. Although turgor is essential for growth to occur, the local expansion rate is controlled by local changes in the viscosity of the apical wall. We focus on several different structures and underlying processes that are thought to be major participants including exocytosis, the organization and activity of the actin cytoskeleton, calcium and proton physiology, and cellular energetics. We think that the actin cytoskeleton, in particular the apical cortical actin fringe, directs the flow of vesicles to the apical domain, where they fuse with the plasma membrane and contribute their contents to the expanding cell wall. While pH gradients, as generated by a proton-ATPase located on the plasma membrane along the side of the clear zone, may regulate rapid actin turnover and new polymerization in the fringe, the tip-focused calcium gradient biases secretion towards the polar axis. The recent data showing that exocytosis of new wall material precedes and predicts the process of cell elongation provide support for the idea that the intussusception of newly secreted pectin contributes to decreases in apical wall viscosity and to cell expansion. Other prime factors will be the localization and activity of the enzyme pectin methyl-esterase, and the chelation of calcium by pectic acids. Finally, we acknowledge a role for reactive oxygen species in the control of wall viscosity. PMID:23770837

  13. Control of cell wall extensibility during pollen tube growth.

    PubMed

    Hepler, Peter K; Rounds, Caleb M; Winship, Lawrence J

    2013-07-01

    In this review, we address the question of how the tip-growing pollen tube achieves its rapid rate of elongation while maintaining an intact cell wall. Although turgor is essential for growth to occur, the local expansion rate is controlled by local changes in the viscosity of the apical wall. We focus on several different structures and underlying processes that are thought to be major participants including exocytosis, the organization and activity of the actin cytoskeleton, calcium and proton physiology, and cellular energetics. We think that the actin cytoskeleton, in particular the apical cortical actin fringe, directs the flow of vesicles to the apical domain, where they fuse with the plasma membrane and contribute their contents to the expanding cell wall. While pH gradients, as generated by a proton-ATPase located on the plasma membrane along the side of the clear zone, may regulate rapid actin turnover and new polymerization in the fringe, the tip-focused calcium gradient biases secretion towards the polar axis. The recent data showing that exocytosis of new wall material precedes and predicts the process of cell elongation provide support for the idea that the intussusception of newly secreted pectin contributes to decreases in apical wall viscosity and to cell expansion. Other prime factors will be the localization and activity of the enzyme pectin methyl-esterase, and the chelation of calcium by pectic acids. Finally, we acknowledge a role for reactive oxygen species in the control of wall viscosity.

  14. Epigenetic Regulation of Normal and Transformed Breast Epithelial Cell Phenotype

    DTIC Science & Technology

    2009-06-01

    of nine cell lines corresponding to two different normal breast cell types isolated from three different individuals ( BPE 2, HME2, BPE3, HME3, BPE4...normal breast cell subtypes a ( BPE and HME) and their transformed derivatives (BPLER and HMLER) The results in Figure 1 indicate that the...process. 5 Table1 Karyotype analysis of two different normal breast cell subtypes a ( BPE and HME) and their

  15. Microfabricated alkali vapor cell with anti-relaxation wall coating

    SciTech Connect

    Straessle, R.; Pétremand, Y.; Briand, D.; Rooij, N. F. de; Pellaton, M.; Affolderbach, C.; Mileti, G.

    2014-07-28

    We present a microfabricated alkali vapor cell equipped with an anti-relaxation wall coating. The anti-relaxation coating used is octadecyltrichlorosilane and the cell was sealed by thin-film indium-bonding at a low temperature of 140 °C. The cell body is made of silicon and Pyrex and features a double-chamber design. Depolarizing properties due to liquid Rb droplets are avoided by confining the Rb droplets to one chamber only. Optical and microwave spectroscopy performed on this wall-coated cell are used to evaluate the cell's relaxation properties and a potential gas contamination. Double-resonance signals obtained from the cell show an intrinsic linewidth that is significantly lower than the linewidth that would be expected in case the cell had no wall coating but only contained a buffer-gas contamination on the level measured by optical spectroscopy. Combined with further experimental evidence this proves the presence of a working anti-relaxation wall coating in the cell. Such cells are of interest for applications in miniature atomic clocks, magnetometers, and other quantum sensors.

  16. Non-Gaussian yet normal diffusion of a bead near a wall

    NASA Astrophysics Data System (ADS)

    Matse, Mpumelelo; Bechhoefer, John

    Brownian motion of microscopic particles in a simple fluid exhibits two key properties: the mean-squared displacement (MSD) increases linearly with time (< Δx2 > = 2 DΔt , where D is the diffusivity) and the displacement distribution is Gaussian. Although linear MSD (''normal diffusion'') was initially assumed to always imply Gaussian displacements, recent experiments by Granick et al. show that this is not so. Chubynsky et al. [PRL 113, 098302, 2014] have argued that such behavior arises when D has temporal and/or spatial fluctuations that are convoluted together and form a non-Gaussian distribution. Experiments to date have been in complex settings where direct measurements of D (x , t) have not been possible. Here, we report experiments on a simple system where D (x , t) is known: the Brownian motion of a colloidal sphere near a wall. By choosing the particle size carefully, we ensure that the bead explores a wide range of D. We observe a linear MSD curve and non-Gaussian displacements for vertical motion and directly confirm the proposed mechanism of Chubynsky et al. for such ''diffusing diffusivity.'' Research funded by NSERC, Canada.

  17. Molecular Rigidity in Dry and Hydrated Onion Cell Walls.

    PubMed

    Ha, M. A.; Apperley, D. C.; Jarvis, M. C.

    1997-10-01

    Solid-state nuclear magnetic resonance relaxation experiments can provide information on the rigidity of individual molecules within a complex structure such as a cell wall, and thus show how each polymer can potentially contribute to the rigidity of the whole structure. We measured the proton magnetic relaxation parameters T2 (spin-spin) and T1p (spin-lattice) through the 13C-nuclear magnetic resonance spectra of dry and hydrated cell walls from onion (Allium cepa L.) bulbs. Dry cell walls behaved as rigid solids. The form of their T2 decay curves varied on a continuum between Gaussian, as in crystalline solids, and exponential, as in more mobile materials. The degree of molecular mobility that could be inferred from the T2 and T1p decay patterns was consistent with a crystalline state for cellulose and a glassy state for dry pectins. The theory of composite materials may be applied to explain the rigidity of dry onion cell walls in terms of their components. Hydration made little difference to the rigidity of cellulose and most of the xyloglucan shared this rigidity, but the pectic fraction became much more mobile. Therefore, the cellulose/xyloglucan microfibrils behaved as solid rods, and the most significant physical distinction within the hydrated cell wall was between the microfibrils and the predominantly pectic matrix. A minor xyloglucan fraction was much more mobile than the microfibrils and probably corresponded to cross-links between them. Away from the microfibrils, pectins expanded upon hydration into a nonhomogeneous, but much softer, almost-liquid gel. These data are consistent with a model for the stress-bearing hydrated cell wall in which pectins provide limited stiffness across the thickness of the wall, whereas the cross-linked microfibril network provides much greater rigidity in other directions.

  18. Identification of genes involved in cell wall biogenesis in grasses by differential gene expression profiling of elongating and non-elongating maize internodes

    PubMed Central

    Bosch, Maurice; Mayer, Claus-Dieter; Cookson, Alan; Donnison, Iain S.

    2011-01-01

    Despite the economic importance of grasses as food, feed, and energy crops, little is known about the genes that control their cell wall synthesis, assembly, and remodelling. Here a detailed transcriptome analysis that allowed the identification of genes involved in grass cell wall biogenesis is provided. Differential gene expression profiling, using maize oligonucleotide arrays, was used to identify genes differentially expressed between an elongating internode, containing cells exhibiting primary cell wall synthesis, and an internode that had just ceased elongation and in which many cells were depositing secondary cell wall material. This is one of only a few studies specifically aimed at the identification of cell wall-related genes in grasses. Analysis identified new candidate genes for a role in primary and secondary cell wall biogenesis in grasses. The results suggest that many proteins involved in cell wall processes during normal development are also recruited during defence-related cell wall remodelling events. This work provides a platform for studies in which candidate genes will be functionally tested for involvement in cell wall-related processes, increasing our knowledge of cell wall biogenesis and its regulation in grasses. Since several grasses are currently being developed as lignocellulosic feedstocks for biofuel production, this improved understanding of grass cell wall biogenesis is timely, as it will facilitate the manipulation of traits favourable for sustainable food and biofuel production. PMID:21402660

  19. Chromosome and cell wall segregation in Streptococcus faecium ATCC 9790

    SciTech Connect

    Higgins, M.L.; Glaser, D.; Dicker, D.T.; Zito, E.T.

    1989-01-01

    Segregation was studied by measuring the positions of autoradiographic grain clusters in chains formed from single cells containing on average less than one radiolabeled chromosome strand. The degree to which chromosomal and cell wall material cosegregated was quantified by using the methods of S. Cooper and M. Weinberger, dividing the number of chains labeled at the middle. This analysis indicated that in contrast to chromosomal segregation in Escherichia coli and, in some studies, to that in gram-positive rods, chromosomal segregation in Streptococcus faecium was slightly nonrandom and did not vary with growth rate. Results were not significantly affected by strand exchange. In contrast, labeled cell wall segregated predominantly nonrandomly.

  20. Analyzing Cell Wall Elasticity After Hormone Treatment: An Example Using Tobacco BY-2 Cells and Auxin.

    PubMed

    Braybrook, Siobhan A

    2017-01-01

    Atomic force microscopy, and related nano-indentation techniques, is a valuable tool for analyzing the elastic properties of plant cell walls as they relate to changes in cell wall chemistry, changes in development, and response to hormones. Within this chapter I will describe a method for analyzing the effect of the phytohormone auxin on the cell wall elasticity of tobacco BY-2 cells. This general method may be easily altered for different experimental systems and hormones of interest.

  1. RESEARCH ON CELL WALL CYTOCHEMISTRY OF SELECTED FUNGI.

    DTIC Science & Technology

    that the resistant material in their cell walls is chitin. All efforts to identify cellulose produced negative results. Solutions of chitinase ...fungi examined, especially Heterocephalum aurantiacum Plastid-like structures in the protoplasts are the cell organs which produce chitin. Chitin

  2. 15. View of interior, north wall of hot cell featuring ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. View of interior, north wall of hot cell featuring radioactive materials containment box, facing east - Nevada Test Site, Reactor Maintenance & Disassembly Complex, Junior Hot Cell, Jackass Flats, Area 25, South of intersection of Roads F & G, Mercury, Nye County, NV

  3. Cell-wall remodeling drives engulfment during Bacillus subtilis sporulation

    PubMed Central

    Ojkic, Nikola; López-Garrido, Javier; Pogliano, Kit; Endres, Robert G

    2016-01-01

    When starved, the Gram-positive bacterium Bacillus subtilis forms durable spores for survival. Sporulation initiates with an asymmetric cell division, creating a large mother cell and a small forespore. Subsequently, the mother cell membrane engulfs the forespore in a phagocytosis-like process. However, the force generation mechanism for forward membrane movement remains unknown. Here, we show that membrane migration is driven by cell wall remodeling at the leading edge of the engulfing membrane, with peptidoglycan synthesis and degradation mediated by penicillin binding proteins in the forespore and a cell wall degradation protein complex in the mother cell. We propose a simple model for engulfment in which the junction between the septum and the lateral cell wall moves around the forespore by a mechanism resembling the ‘template model’. Hence, we establish a biophysical mechanism for the creation of a force for engulfment based on the coordination between cell wall synthesis and degradation. DOI: http://dx.doi.org/10.7554/eLife.18657.001 PMID:27852437

  4. Brachypodium distachyon grain: characterization of endosperm cell walls.

    PubMed

    Guillon, Fabienne; Bouchet, Brigitte; Jamme, Frédéric; Robert, Paul; Quéméner, Bernard; Barron, Cécile; Larré, Colette; Dumas, Paul; Saulnier, Luc

    2011-01-01

    The wild grass Brachypodium distachyon has been proposed as an alternative model species for temperate cereals. The present paper reports on the characterization of B. distachyon grain, placing emphasis on endosperm cell walls. Brachypodium distachyon is notable for its high cell wall polysaccharide content that accounts for ∼52% (w/w) of the endosperm in comparison with 2-7% (w/w) in other cereals. Starch, the typical storage polysaccharide, is low [<10% (w/w)] in the endosperm where the main polysaccharide is (1-3) (1-4)-β-glucan [40% (w/w) of the endosperm], which in all likelihood plays a role as a storage compound. In addition to (1-3) (1-4)-β-glucan, endosperm cells contain cellulose and xylan in significant amounts. Interestingly, the ratio of ferulic acid to arabinoxylan is higher in B. distachyon grain than in other investigated cereals. Feruloylated arabinoxylan is mainly found in the middle lamella and cell junction zones of the storage endosperm, suggesting a potential role in cell-cell adhesion. The present results indicate that B. distachyon grains contain all the cell wall polysaccharides encountered in other cereal grains. Thus, due to its fully sequenced genome, its short life cycle, and the genetic tools available for mutagenesis/transformation, B. distachyon is a good model to investigate cell wall polysaccharide synthesis and function in cereal grains.

  5. Cell wall proteome analysis of Arabidopsis thaliana mature stems.

    PubMed

    Duruflé, Harold; Clemente, Hélène San; Balliau, Thierry; Zivy, Michel; Dunand, Christophe; Jamet, Elisabeth

    2017-02-02

    Plant stems carry flowers necessary for species propagation and need to be adapted to mechanical disturbance and environmental factors. The stem cell walls are different from other organs and can modify their rigidity or viscoelastic properties for the integrity and the robustness required to withstand mechanical impacts and environmental stresses. Plant cell wall is composed of complex polysaccharide networks also containing cell wall proteins (CWPs) crucial to perceive and limit the environmental effects. The CWPs are fundamental players in cell wall remodeling processes, and today, only 86 have been identified from the mature stems of the model plant Arabidopsis thaliana. With a destructive method, this study has enlarged its coverage to 302 CWPs. This new proteome is mainly composed of 27.5% proteins acting on polysaccharides, 16% proteases, 11.6% oxido-reductases, 11% possibly related to lipid metabolism and 11% of proteins with interacting domains with proteins or polysaccharides. Compared to stem cell wall proteomes already available (Brachypodium distachyon, Sacharum officinarum, Linum usitatissimum, Medicago sativa), that of A. thaliana stems has a higher proportion of proteins acting on polysaccharides and of proteases, but a lower proportion of oxido-reductases.

  6. Gene expression in Fusarium graminearum grown on plant cell wall.

    PubMed

    Carapito, Raphaël; Hatsch, Didier; Vorwerk, Sonja; Petkovski, Elizabet; Jeltsch, Jean-Marc; Phalip, Vincent

    2008-05-01

    Fusarium graminearum is a phytopathogenic filamentous fungus attacking a wide range of plants including Humulus lupulus (hop). Transcriptional analysis of F. graminearum grown on minimal media containing hop cell wall or glucose as the sole carbon source was performed by applying a highly stringent method combining microarrays and a subtracted cDNA library. In addition to genes coding for various cell wall degrading enzymes (CWDE), several metabolic pathways were induced in response to the plant cell wall substrate. Many genes participating in these pathways are probably involved in cellular transport. But the most interesting was that all the genes composing the 4-aminobutyrate-shunt (GABA-shunt) were also up-regulated in the presence of plant cell wall material and were present in the cDNA library. This study provides a description of a part of the fungal gene expression profile when it is in contact with raw biological materials, and helps in understanding the plant cell wall degradation and the infection process.

  7. The role of the cell wall in plant immunity

    PubMed Central

    Malinovsky, Frederikke G.; Fangel, Jonatan U.; Willats, William G. T.

    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 processes underlying cell wall modification poses special challenges for plant glycobiology. In this review we describe the major molecular and cellular mechanisms that underlie the roles of cell walls in plant defense against pathogen attack. In so doing, we also highlight some of the challenges inherent in studying these interactions, and briefly describe the analytical potential of molecular probes used in conjunction with carbohydrate microarray technology. PMID:24834069

  8. Effect of temperature on plant elongation and cell wall extensibility.

    PubMed

    Pietruszka, M; Lewicka, S

    2007-03-01

    Lockhart equation was derived for explaining plant cell expansion where both cell wall extension and water uptake must occur concomitantly. Its fundamental contribution was to express turgor pressure explicitly in terms of osmosis and wall mechanics. Here we present a new equation in which pressure is determined by temperature. It also accounts for the role of osmosis and consequently the role of water uptake in growing cell. By adopting literature data, we also attempt to report theoretically the close relation between plant elongation and cell wall extensibility. This is accomplished by the modified equation of growth solved for various temperatures in case of two different species. The results enable to interpret empirical data in terms of our model and fully confirm its applicability to the investigation of the problem of plant cell extensibility in function of environmental temperature. Moreover, by separating elastic effects from growth process we specified the characteristic temperature common for both processes which corresponds to the resonance energy of biochemical reactions as well as to the rapid softening of the elastic modes toward the high temperature end where we encountered viscoelastic and/or plastic behavior as dominating. By introducing analytical formulae connected with growth and elastic properties of the cell wall, we conclude with the statement how these both processes contribute quantitatively to the resonance-like shape of the elongation curve. In addition, the tension versus temperature "phase diagram" for a living plant cell is presented.

  9. Cell Wall Regeneration around Protoplasts Isolated from Convolvulus Tissue Culture 1

    PubMed Central

    Horine, Randall K.; Ruesink, Albert W.

    1972-01-01

    Protoplasts of Convolvulus arvensis L. tissue culture regenerated a wall-like structure within 3 days in culture. Although unusually electron dense and atypically amorphous in the electron microscope, this structure could be digested with Myrothecium cellulase but was resistant to protease, a Rohm and Haas pectinase, and a β-1, 3-exoglucanase just like the original wall. A cytochemical test for callose was negative. Wall regeneration required a readily metabolized external carbon source and was not inhibited by a high concentration of cycloheximide, puromycin, or actinomycin D. Protoplast budding was correlated with the wall regeneration, and the latter was related quantitatively to the sucrose concentration in the medium. Although a concentration of 1 μm 2,4-dichlorophenoxy acetic acid is used normally for both general culture of the tissue and for wall regeneration, concentrations of 0 and 0.1 mm, which are highly deleterious to growth, have no appreciable effect on the incidence of the wall-like structure regenerated around protoplasts. The ability of protoplasts to undergo cell wall regeneration was decreased when they were cultured in the presence of proteolytic enzymes. Images PMID:16658192

  10. A new method for extraction of pectin from cell walls

    SciTech Connect

    Maness, N.O.; Mort, A.J. )

    1991-05-01

    Pectin is often extracted from plant tissues using the Ca{sup ++} chelators ethylenediamine tetraacetate (EDTA) or cyclohexane-trans-1,2 diamine tetraacetate (CDTA). While these chelators are effective in solubilizing pectin, even after extensive dialysis against distilled water, EDTA or CDTA remains associated with the pectin. The authors have found that if 500 mM imidazole buffer, pH 7.0 is substituted for 50 mM CDTA, pH 6.5, and for equivalent extraction periods, an equivalent amount of pectin with the same sugar composition is extracted. But, the imidazole buffer can be dialyzed away completely into distilled water. Their alternative procedure for extraction of pectin from cell walls will be presented. Utilization of the procedure for extraction of whole cell walls or cell walls pretreated with liquid hydrogen fluoride is discussed.

  11. Freezing stresses and hydration of isolated cell walls.

    PubMed

    Yoon, Yonghyeon; Pope, Jim; Wolfe, Joe

    2003-06-01

    The hydration of the cell walls of the giant alga Chara australis was measured as a function of temperature using quantitative deuterium nuclear magnetic resonance (NMR) of samples hydrated with D2O. At temperatures 23-5K below freezing, the hydration ratio (the ratio of mass of unfrozen water in microscopic phases in the cell wall to the dry mass) increases slowly with increasing temperature from about 0.2 to 0.4. It then rises rapidly with temperature in the few Kelvin below the freezing temperature. The linewidth of the NMR signal varies approximately linearly with the reciprocal of the hydration ratio, and with the freezing point depression or water potential. These empirical relations may be useful in estimating cell wall water contents in heterogeneous samples.

  12. [Stem and progenitor cells in biostructure of blood vessel walls].

    PubMed

    Korta, Krzysztof; Kupczyk, Piotr; Skóra, Jan; Pupka, Artur; Zejler, Paweł; Hołysz, Marcin; Gajda, Mariusz; Nowakowska, Beata; Barć, Piotr; Dorobisz, Andrzej T; Dawiskiba, Tomasz; Szyber, Piotr; Bar, Julia

    2013-09-18

    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.

  13. Restoration of normal phenotype in cancer cells

    DOEpatents

    Bissell, Mina J.; Weaver, Valerie M.

    1998-01-01

    A method for reversing expression of malignant phenotype in cancer cells is described. The method comprises applying .beta..sub.1 integrin function-blocking antibody to the cells. The method can be used to assess the progress of cancer therapy. Human breast epithelial cells were shown to be particularly responsive.

  14. Restoration of normal phenotype in cancer cells

    DOEpatents

    Bissell, M.J.; Weaver, V.M.

    1998-12-08

    A method for reversing expression of malignant phenotype in cancer cells is described. The method comprises applying {beta}{sub 1} integrin function-blocking antibody to the cells. The method can be used to assess the progress of cancer therapy. Human breast epithelial cells were shown to be particularly responsive. 14 figs.

  15. Novel insights of ethylene role in strawberry cell wall metabolism.

    PubMed

    Villarreal, Natalia M; Marina, María; Nardi, Cristina F; Civello, Pedro M; Martínez, Gustavo A

    2016-11-01

    Due to its organoleptic and nutraceutical qualities, strawberry fruit (Fragaria x ananassa, Duch) is a worldwide important commodity. The role of ethylene in the regulation of strawberry cell wall metabolism was studied in fruit from Toyonoka cultivar harvested at white stage, when most changes associated with fruit ripening have begun. Fruit were treated with ethephon, an ethylene-releasing reagent, or with 1-methylcyclopropene (1-MCP), a competitive inhibitor of ethylene action, maintaining a set of non-treated fruit as controls for each condition. Ethephon treated-fruit showed higher contents of hemicelluloses, cellulose and neutral sugars regarding controls, while 1-MCP-treated fruit showed a lower amount of those fractions. On the other hand, ethephon-treated fruit presented a lower quantity of galacturonic acid from ionically and covalently bound pectins regarding controls, while 1-MCP-treated fruit showed higher contents of those components. We also explored the ethylene effect over the mRNA accumulation of genes related to pectins and hemicelluloses metabolism, and a relationship between gene expression patterns and cell wall polysaccharides contents was shown. Moreover, we detected that strawberry necrotrophic pathogens growth more easily on plates containing cell walls from ethephon-treated fruit regarding controls, while a lower growth rate was observed when cell walls from 1-MCP treated fruit were used as the only carbon source, suggesting an effect of ethylene on cell wall structure. Around 60% of strawberry cell wall is made up of pectins, which in turns is 70% made by homogalacturonans. Our findings support the idea of a central role for pectins on strawberry fruit softening and a participation of ethylene in the regulation of this process.

  16. Particle Trajectories in Rotating Wall Cell Culture Devices

    NASA Technical Reports Server (NTRS)

    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.

  17. Cell Walls and the Convergent Evolution of the Viral Envelope

    PubMed Central

    Buchmann, Jan P.

    2015-01-01

    SUMMARY Why some viruses are enveloped while others lack an outer lipid bilayer is a major question in viral evolution but one that has received relatively little attention. The viral envelope serves several functions, including protecting the RNA or DNA molecule(s), evading recognition by the immune system, and facilitating virus entry. Despite these commonalities, viral envelopes come in a wide variety of shapes and configurations. The evolution of the viral envelope is made more puzzling by the fact that nonenveloped viruses are able to infect a diverse range of hosts across the tree of life. We reviewed the entry, transmission, and exit pathways of all (101) viral families on the 2013 International Committee on Taxonomy of Viruses (ICTV) list. By doing this, we revealed a strong association between the lack of a viral envelope and the presence of a cell wall in the hosts these viruses infect. We were able to propose a new hypothesis for the existence of enveloped and nonenveloped viruses, in which the latter represent an adaptation to cells surrounded by a cell wall, while the former are an adaptation to animal cells where cell walls are absent. In particular, cell walls inhibit viral entry and exit, as well as viral transport within an organism, all of which are critical waypoints for successful infection and spread. Finally, we discuss how this new model for the origin of the viral envelope impacts our overall understanding of virus evolution. PMID:26378223

  18. Interactions of Condensed Tannins with Saccharomyces cerevisiae Yeast Cells and Cell Walls: Tannin Location by Microscopy.

    PubMed

    Mekoue Nguela, Julie; Vernhet, Aude; Sieczkowski, Nathalie; Brillouet, Jean-Marc

    2015-09-02

    Interactions between grape tannins/red wine polyphenols and yeast cells/cell walls was previously studied within the framework of red wine aging and the use of yeast-derived products as an alternative to aging on lees. Results evidenced a quite different behavior between whole cells (biomass grown to elaborate yeast-derived products, inactivated yeast, and yeast inactivated after autolysis) and yeast cell walls (obtained from mechanical disruption of the biomass). Briefly, whole cells exhibited a high capacity to irreversibly adsorb grape and wine tannins, whereas only weak interactions were observed for cell walls. This last point was quite unexpected considering the literature and called into question the real role of cell walls in yeasts' ability to fix tannins. In the present work, tannin location after interactions between grape and wine tannins and yeast cells and cell walls was studied by means of transmission electron microscopy, light epifluorescence, and confocal microscopy. Microscopy observations evidenced that if tannins interact with cell walls, and especially cell wall mannoproteins, they also diffuse freely through the walls of dead cells to interact with their plasma membrane and cytoplasmic components.

  19. MECHANISM OF CELL WALL PENETRATION BY VIRUSES

    PubMed Central

    Puck, Theodore T.; Lee, Howard H.

    1954-01-01

    Treatment of radioactively labelled host cells with T1 or T2 bacteriophages induces a leakage of cellular P and S into the medium. Evidence is presented showing that this increased cell permeability is not the result of complete lysis of a small fraction of the cells, but rather is made up of contributions from all or most of the infected population. This leakage of cellular constituents exhibits the following characteristics: (a) Infection of a cell with a single virus suffices to evoke the reaction; (b) Increasing the multiplicity up to 7 to 8 virus particles per cell does not affect the extent of leakage produced; (c) Some leakage does occur at 0°C., but much less than at 37°C.; (d) Infection by T1 virus results in a smaller amount of leakage than in the case of T2, but the pattern of response to varying virus multiplicity is the same; (e) The P resulting from such leakage contains no DNA and chemically resembles that which elutes in smaller amounts from uninfected cells; (f) At 37°C. the virus-induced leakage reaction appears within a matter of seconds, and usually decreases after 2 to 3 minutes; (g) The reaction is inhibited by 0.025 M Mg++. Theoretical considerations are presented suggesting the place of this reaction in the sequence of events constituting the virus penetration reaction; its relationship to the phenomenon of lysis-from-without; and its resemblance to the leakage reaction produced by electrostatic binding of ionized compounds to cell surfaces. The existence of similar effects in avian-mammalian virus systems is noted. PMID:13163323

  20. Domain conservation in several volvocalean cell wall proteins.

    PubMed

    Woessner, J P; Molendijk, A J; van Egmond, P; Klis, F M; Goodenough, U W; Haring, M A

    1994-11-01

    Based on our previous work demonstrating that (SerPro)x epitopes are common to extensin-like cell wall proteins in Chlamydomonas' reinhardtii, we looked for similar proteins in the distantly related species C. eugametos. Using a polyclonal antiserum against a (SerPro)10 oligopeptide, we found distinct sets of stage-specific polypeptides immunoprecipitated from in vitro translations of C. eugametos RNA. Screening of a C. eugametos cDNA expression library with the antiserum led to the isolation of a cDNA (WP6) encoding a (SerPro)x-rich multidomain wall protein. Analysis of a similarly selected cDNA (VSP-3) from a C. reinhardtii cDNA expression library revealed that it also coded for a (SerPro)x-rich multidomain wall protein. The C-terminal rod domains of VSP-3 and WP6 are highly homologous, while the N-terminal domains are dissimilar; however, the N-terminal domain of VSP-3 is homologous to the globular domain of a cell wall protein from Volvox carteri. Exon shuffling might be responsible for this example of domain conservation over 350 million years of volvocalean cell wall protein evolution.

  1. A control systems approach to quantify wall shear stress normalization by flow-mediated dilation in the brachial artery.

    PubMed

    van Bussel, Frank C G; van Bussel, Bas C T; Hoeks, Arnold P G; Op 't Roodt, Jos; Henry, Ronald M A; Ferreira, Isabel; Vanmolkot, Floris H M; Schalkwijk, Casper G; Stehouwer, Coen D A; Reesink, Koen D

    2015-01-01

    Flow-mediated dilation is aimed at normalization of local wall shear stress under varying blood flow conditions. Blood flow velocity and vessel diameter are continuous and opposing influences that modulate wall shear stress. We derived an index FMDv to quantify wall shear stress normalization performance by flow-mediated dilation in the brachial artery. In 22 fasting presumed healthy men, we first assessed intra- and inter-session reproducibilities of two indices pFMDv and mFMDv, which consider the relative peak and relative mean hyperemic change in flow velocity, respectively. Second, utilizing oral glucose loading, we evaluated the tracking performance of both FMDv indices, in comparison with existing indices [i.e., the relative peak diameter increase (%FMD), the peak to baseline diameter ratio (Dpeak/Dbase), and the relative peak diameter increase normalized to the full area under the curve of blood flow velocity with hyperemia (FMD/shearAUC) or with area integrated to peak hyperemia (FMD/shearAUC_peak)]. Inter-session and intra-session reproducibilities for pFMDv, mFMDv and %FMD were comparable (intra-class correlation coefficients within 0.521-0.677 range). Both pFMDv and mFMDv showed more clearly a reduction after glucose loading (reduction of ~45%, p≤0.001) than the other indices (% given are relative reductions): %FMD (~11%, p≥0.074); Dpeak/Dbase (~11%, p≥0.074); FMD/shearAUC_peak (~20%, p≥0.016) and FMD/shearAUC (~38%, p≤0.038). Further analysis indicated that wall shear stress normalization under normal (fasting) conditions is already far from ideal (FMDv < 1), which (therefore) does not materially change with glucose loading. Our approach might be useful in intervention studies to detect intrinsic changes in shear stress normalization performance in conduit arteries.

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

    NASA Technical Reports Server (NTRS)

    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.

  3. Engineering temporal accumulation of a low recalcitrance polysaccharide leads to increased C6 sugar content in plant cell walls.

    PubMed

    Vega-Sánchez, Miguel E; Loqué, Dominique; Lao, Jeemeng; Catena, Michela; Verhertbruggen, Yves; Herter, Thomas; Yang, Fan; Harholt, Jesper; Ebert, Berit; Baidoo, Edward E K; Keasling, Jay D; Scheller, Henrik V; Heazlewood, Joshua L; Ronald, Pamela C

    2015-09-01

    Reduced cell wall recalcitrance and increased C6 monosaccharide content are desirable traits for future biofuel crops, as long as these biomass modifications do not significantly alter normal growth and development. Mixed-linkage glucan (MLG), a cell wall polysaccharide only present in grasses and related species among flowering plants, is comprised of glucose monomers linked by both β-1,3 and β-1,4 bonds. Previous data have shown that constitutive production of MLG in barley (Hordeum vulgare) severely compromises growth and development. Here, we used spatio-temporal strategies to engineer Arabidopsis thaliana plants to accumulate significant amounts of MLG in the cell wall by expressing the rice CslF6 MLG synthase using secondary cell wall and senescence-associated promoters. Results using secondary wall promoters were suboptimal. When the rice MLG synthase was expressed under the control of a senescence-associated promoter, we obtained up to four times more glucose in the matrix cell wall fraction and up to a 42% increase in saccharification compared to control lines. Importantly, these plants grew and developed normally. The induction of MLG deposition at senescence correlated with an increase of gluconic acid in cell wall extracts of transgenic plants in contrast to the other approaches presented in this study. MLG produced in Arabidopsis has an altered structure compared to the grass glucan, which likely affects its solubility, while its molecular size is unaffected. The induction of cell wall polysaccharide biosynthesis in senescing tissues offers a novel engineering alternative to enhance cell wall properties of lignocellulosic biofuel crops.

  4. Cell-wall composition and structure of yeast cells and conjugation tubes of Tremella mesenterica.

    PubMed

    Reid, I D; Bartnicki-Garcia, S

    1976-09-01

    Cell walls prepared from vegetative yeast cells and from hormone-induced conjugation tubes of the basidiomycete Tremella mesenterica had similar compositions. Evidence was found for 1,3-alpha-glucan (yeast 38%, tube 25%), 1,3-beta-1,6-beta-glucan (yeast 33%, tube 48%) and chitin (both less than 3%) in the walls. The walls also contained xylose (5 to 7%), mannose (6%), glucuronic acid (approx. 2%), and traces of galactose. Protein amounted to less than 2% of the wall weight. The cell capsule was very insoluble and could not be removed from the cell wall. The conjugation hormone did not appear to exert its effect on cell shape by causing gross changes in wall composition.

  5. An Arabidopsis gene regulatory network for secondary cell wall synthesis

    DOE PAGES

    Taylor-Teeples, M.; Lin, L.; de Lucas, M.; ...

    2014-12-24

    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 transcriptional regulation of synthesis for each polymer is complex and vital to cell function. A regulatory hierarchy of developmental switches has been proposed, although the full complement of regulators remains unknown. In this paper, we present a protein–DNA network between Arabidopsis thaliana transcription factors and secondary cell wall metabolic genes with gene expression regulated bymore » a series of feed-forward loops. This model allowed us to develop and validate new hypotheses about secondary wall gene regulation under abiotic stress. Distinct stresses are able to perturb targeted genes to potentially promote functional adaptation. Finally, these interactions will serve as a foundation for understanding the regulation of a complex, integral plant component.« less

  6. Wood Contains a Cell-Wall Structural Protein

    NASA Astrophysics Data System (ADS)

    Bao, Wuli; O'Malley, David M.; Sederoff, Ronald R.

    1992-07-01

    A pine extensin-like protein (PELP) has been localized in metabolically active cells of differentiating xylem and in mature wood of loblolly pine (Pinus taeda L.). This proline-rich glycosylated protein was purified from cell walls of differentiating xylem by differential solubility and gel electrophoresis. Polyclonal rabbit antibodies were raised against the deglycosylated purified protein (dPELP) and purified antibody was used for immunolocalization. Immunogold and alkaline phosphatase secondary antibody staining both show antigen in secondary cell walls of earlywood and less staining in latewood. Immunoassays of milled dry wood were developed and used to show increased availability of antigen after hydrogen fluoride or cellulase treatment and decreased antigen after chlorite treatment. The specificity of the antigen-antibody reaction was confirmed by competition assays and by preadsorption of antibody to the purified protein. We propose that extensin-like protein is present in xylem cell walls during lignification and that the protein remains as a structural component of cell walls in wood for many years after xylogenesis. We suggest that such structural proteins play important roles in the differentiation of xylem and thereby could affect the properties of wood.

  7. Interaction between a normal shock wave and a turbulent boundary layer at high transonic speeds. II - Wall shear stress

    NASA Technical Reports Server (NTRS)

    Liou, M. S.; Adamson, T. C., Jr.

    1980-01-01

    Asymptotic methods are used to calculate the shear stress at the wall for the interaction between a normal shock wave and a turbulent boundary layer on a flat plate. A mixing length model is used for the eddy viscosity. The shock wave is taken to be strong enough that the sonic line is deep in the boundary layer and the upstream influence is thus very small. It is shown that unlike the result found for laminar flow an asymptotic criterion for separation is not found; however, conditions for incipient separation are computed numerically using the derived solution for the shear stress at the wall. Results are compared with available experimental measurements.

  8. Study of coherent structures of turbulence with large wall-normal gradients in thermophysical properties using direct numerical simulation

    NASA Astrophysics Data System (ADS)

    Reinink, Shawn K.; Yaras, Metin I.

    2015-06-01

    Forced-convection heat transfer in a heated working fluid at a thermodynamic state near its pseudocritical point is poorly predicted by correlations calibrated with data at subcritical temperatures and pressures. This is suggested to be primarily due to the influence of large wall-normal thermophysical property gradients that develop in proximity of the pseudocritical point on the concentration of coherent turbulence structures near the wall. The physical mechanisms dominating this influence remain poorly understood. In the present study, direct numerical simulation is used to study the development of coherent vortical structures within a turbulent spot under the influence of large wall-normal property gradients. A turbulent spot rather than a fully turbulent boundary layer is used for the study, for the coherent structures of turbulence in a spot tend to be in a more organized state which may allow for more effective identification of cause-and-effect relationships. Large wall-normal gradients in thermophysical properties are created by heating the working fluid which is near the pseudocritical thermodynamic state. It is found that during improved heat transfer, wall-normal gradients in density accelerate the growth of the Kelvin-Helmholtz instability mechanism in the shear layer enveloping low-speed streaks, causing it to roll up into hairpin vortices at a faster rate. It is suggested that this occurs by the baroclinic vorticity generation mechanism which accelerates the streamwise grouping of vorticity during shear layer roll-up. The increased roll-up frequency leads to reduced streamwise spacing between hairpin vortices in wave packets. The density gradients also promote the sinuous instability mode in low-speed streaks. The resulting oscillations in the streaks in the streamwise-spanwise plane lead to locally reduced spanwise spacing between hairpin vortices forming over adjacent low-speed streaks. The reduction in streamwise and spanwise spacing between

  9. Cell-wall recovery after irreversible deformation of wood.

    PubMed

    Keckes, Jozef; Burgert, Ingo; Frühmann, Klaus; Müller, Martin; Kölln, Klaas; Hamilton, Myles; Burghammer, Manfred; Roth, Stephan V; Stanzl-Tschegg, Stefanie; Fratzl, Peter

    2003-12-01

    The remarkable mechanical properties of biological materials reside in their complex hierarchical architecture and in specific molecular mechanistic phenomena. The fundamental importance of molecular interactions and bond recovery has been suggested by studies on deformation and fracture of bone and nacre. Like these mineral-based materials, wood also represents a complex nanocomposite with excellent mechanical performance, despite the fact that it is mainly based on polymers. In wood, however, the mechanistic contribution of processes in the cell wall is not fully understood. Here we have combined tensile tests on individual wood cells and on wood foils with simultaneous synchrotron X-ray diffraction analysis in order to separate deformation mechanisms inside the cell wall from those mediated by cell-cell interactions. We show that tensile deformation beyond the yield point does not deteriorate the stiffness of either individual cells or foils. This indicates that there is a dominant recovery mechanism that re-forms the amorphous matrix between the cellulose microfibrils within the cell wall, maintaining its mechanical properties. This stick-slip mechanism, rather like Velcro operating at the nanometre level, provides a 'plastic response' similar to that effected by moving dislocations in metals. We suggest that the molecular recovery mechanism in the cell matrix is a universal phenomenon dominating the tensile deformation of different wood tissue types.

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

    PubMed

    Reboul, Rebecca; Tenhaken, Raimund

    2012-02-01

    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 previously favored xyloglucan.

  11. Cell wall structure and function in lactic acid bacteria

    PubMed Central

    2014-01-01

    The cell wall of Gram-positive bacteria is a complex assemblage of glycopolymers and proteins. It consists of a thick peptidoglycan sacculus that surrounds the cytoplasmic membrane and that is decorated with teichoic acids, polysaccharides, and proteins. It plays a major role in bacterial physiology since it maintains cell shape and integrity during growth and division; in addition, it acts as the interface between the bacterium and its environment. Lactic acid bacteria (LAB) are traditionally and widely used to ferment food, and they are also the subject of more and more research because of their potential health-related benefits. It is now recognized that understanding the composition, structure, and properties of LAB cell walls is a crucial part of developing technological and health applications using these bacteria. In this review, we examine the different components of the Gram-positive cell wall: peptidoglycan, teichoic acids, polysaccharides, and proteins. We present recent findings regarding the structure and function of these complex compounds, results that have emerged thanks to the tandem development of structural analysis and whole genome sequencing. Although general structures and biosynthesis pathways are conserved among Gram-positive bacteria, studies have revealed that LAB cell walls demonstrate unique properties; these studies have yielded some notable, fundamental, and novel findings. Given the potential of this research to contribute to future applied strategies, in our discussion of the role played by cell wall components in LAB physiology, we pay special attention to the mechanisms controlling bacterial autolysis, bacterial sensitivity to bacteriophages and the mechanisms underlying interactions between probiotic bacteria and their hosts. PMID:25186919

  12. Titration of Isolated Cell Walls of Lemna minor L 1

    PubMed Central

    Morvan, Claudine; Demarty, Maurice; Thellier, Michel

    1979-01-01

    A theoretical model has been built to bypass the equation of titration of the cell wall. This equation, which is an extension of the Henderson-Hasselbach equation, underlines the importance of the exchange constant, the ionic strength as well as the rate of neutralization. The model is restricted to the case when the ionization degree is equal to the neutralization degree. The shape of the titration curve is shown to be strongly dependent on the valency of the base used. Experimental results have shown that isolated cell walls bear at least two kinds of sites. The first sites which are titrated after a short time of equilibration are attributed to polyuronic acids (capacity: 0.3 milliequivalents per gram fresh cell walls). The second sites, are obtained after a long time of equilibration (capacity: 1.2 to 1.3 milliequivalents per gram, fresh cell walls). Titrations have been performed with different bases [KOH, NaOH, and Ca(OH)2] and under different ionic strengths. The results obtained with NaOH and KOH do not exhibit any difference of selectivity. Conversely, the sites have a much bigger affinity for the Ca2+ ions than for the monovalent ones. The apparent pKa of the uronic acids was estimated to lie between 3.0 and 3.4; this is consistent with the values obtained with polyuronic acid solutions. PMID:16660868

  13. Imaging of plant cell walls by confocal Raman microscopy.

    PubMed

    Gierlinger, Notburga; Keplinger, Tobias; Harrington, Michael

    2012-09-01

    Raman imaging of plant cell walls represents a nondestructive technique that can provide insights into chemical composition in context with structure at the micrometer level (<0.5 μm). The major steps of the experimental procedure are described: sample preparation (embedding and microcutting), setting the mapping parameters, and finally the calculation of chemical images on the basis of the acquired Raman spectra. Every Raman image is based on thousands of spectra, each being a spatially resolved molecular 'fingerprint' of the cell wall. Multiple components are analyzed within the native cell walls, and insights into polymer composition as well as the orientation of the cellulose microfibrils can be gained. The most labor-intensive step of this process is often the sample preparation, as the imaging approach requires a flat surface of the plant tissue with intact cell walls. After finishing the map (acquisition time is ∼10 min to 10 h, depending on the size of the region of interest and scanning parameters), many possibilities exist for the analysis of spectral data and image generation.

  14. Polymer mobility in cell walls of cucumber hypocotyls

    NASA Technical Reports Server (NTRS)

    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.

  15. Determination of carbohydrate profile in sugarbeet (Beta vulgaris) cell walls

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugarbeet germplasms USH20, C869, EL55, EL54 were used, and different tissues at different developmental stages were sampled, including dry seeds, germinating seedlings, developing leaves, mature leaves, petioles, hypocotyls, mature roots, flowering stems and inflorescences. Cell Wall Composition An...

  16. Using isolated cell wall xylan to identify recalcitrant oligosaccharides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbaceous biomass is a renewable source of carbohydrates with potential for use in microbial conversion to biofuels. Xylan comprises 20-40% of herbaceous biomass cell wall material and its full depolymerization benefits the economics of bioconversion. To understand the limitations of commercial enz...

  17. Biosynthesis and assembly of cell wall polysaccharides in cereal grasses

    SciTech Connect

    Carpita, N.C.

    1991-04-01

    We have just completed the second year of a three-year project entitled Biosynthesis assembly of cell wall polysaccharides in cereal grasses.'' We made significant progress on two aspects of cell wall synthesis in grasses and greatly refined gas-liquid and high- performance liquid chromatographic techniques necessary to identify the products of synthesis in vitro and in vivo. First, Dr. David Gibeaut, a post-doctoral associate, devised a convenient procedure for the enrichment of Golgi membranes by flotation centrifugation following initial downward rate-zonal separation. Based on comparison of the IDPase marker enzyme, flotation centrifugation enriched the Golgi apparatus almost 7-fold after the initial downward separation. This system is now used in our studies of the synthesis in vitro of the mixed-linkage {beta}-D-glucan. Second, Gibeaut and I have devised a simple technique to feed radioactive sugars into intact growing seedlings and follow incorporation of radioactivity into and turnover from specific cell wall polysaccharides. The project has also provided a few spin-off projects that have been productive as well. First, in collaboration with the group of Prof. Peter Kaufman, University of Michigan, we examined changes in cell wall structure concomitant with reaction to gravistimulation in the gravisensing oat pulvinus. Second, Dr. Gibeaut developed a simple clean-up procedure for partially methylated alditol derivatives to remove a large amount of undesirable interfering compounds that confound separation of the derivatives by gas-liquid chromatography. 5 refs.

  18. A cytoplasmic peptidoglycan amidase homologue controls mycobacterial cell wall synthesis

    PubMed Central

    Boutte, Cara C; Baer, Christina E; Papavinasasundaram, Kadamba; Liu, Weiru; Chase, Michael R; Meniche, Xavier; Fortune, Sarah M; Sassetti, Christopher M; Ioerger, Thomas R; Rubin, Eric J

    2016-01-01

    Regulation of cell wall assembly is essential for bacterial survival and contributes to pathogenesis and antibiotic tolerance in Mycobacterium tuberculosis (Mtb). However, little is known about how the cell wall is regulated in stress. We found that CwlM, a protein homologous to peptidoglycan amidases, coordinates peptidoglycan synthesis with nutrient availability. Surprisingly, CwlM is sequestered from peptidoglycan (PG) by localization in the cytoplasm, and its enzymatic function is not essential. Rather, CwlM is phosphorylated and associates with MurA, the first enzyme in PG precursor synthesis. Phosphorylated CwlM activates MurA ~30 fold. CwlM is dephosphorylated in starvation, resulting in lower MurA activity, decreased cell wall metabolism, and increased tolerance to multiple antibiotics. A phylogenetic analysis of cwlM implies that localization in the cytoplasm drove the evolution of this factor. We describe a system that controls cell wall metabolism in response to starvation, and show that this regulation contributes to antibiotic tolerance. DOI: http://dx.doi.org/10.7554/eLife.14590.001 PMID:27304077

  19. Molecular deformation mechanisms of the wood cell wall material.

    PubMed

    Jin, Kai; Qin, Zhao; Buehler, Markus J

    2015-02-01

    Wood is a biological material with outstanding mechanical properties resulting from its hierarchical structure across different scales. Although earlier work has shown that the cellular structure of wood is a key factor that renders it excellent mechanical properties at light weight, the mechanical properties of the wood cell wall material itself still needs to be understood comprehensively. The wood cell wall material features a fiber reinforced composite structure, where cellulose fibrils act as stiff fibers, and hemicellulose and lignin molecules act as soft matrix. The angle between the fiber direction and the loading direction has been found to be the key factor controlling the mechanical properties. However, how the interactions between theses constitutive molecules contribute to the overall properties is still unclear, although the shearing between fibers has been proposed as a primary deformation mechanism. Here we report a molecular model of the wood cell wall material with atomistic resolution, used to assess the mechanical behavior under shear loading in order to understand the deformation mechanisms at the molecular level. The model includes an explicit description of cellulose crystals, hemicellulose, as well as lignin molecules arranged in a layered nanocomposite. The results obtained using this model show that the wood cell wall material under shear loading deforms in an elastic and then plastic manner. The plastic regime can be divided into two parts according to the different deformation mechanisms: yielding of the matrix and sliding of matrix along the cellulose surface. Our molecular dynamics study provides insights of the mechanical behavior of wood cell wall material at the molecular level, and paves a way for the multi-scale understanding of the mechanical properties of wood.

  20. Compositional characterization and imaging of "Wall-bound" acylesters of Populus trichocarpa Reveal Differential Accumulation of acyl Molecules in Normal and Reactive Woods

    SciTech Connect

    Guo, J.; Park, S; Yu, X; Liu, C

    2008-01-01

    Acylesterification is one of the common modifications of cell wall non-cellulosic polysaccharides and/or lignin primarily in monocot plants. We analyzed the cell-wall acylesters of black cottonwood (Populus trichocarpa Torr. & Gray) with liquid chromatography-mass spectrometry (LC-MS), Fourier transform-infrared (FT-IR) microspectroscopy, and synchrotron infrared (IR) imaging facility. The results revealed that the cell wall of dicotyledonous poplar, as the walls of many monocot grasses, contains a considerable amount of acylesters, primarily acetyl and p-hydroxycinnamoyl molecules. The 'wall-bound' acetate and phenolics display a distinct tissue specific-, bending stress responsible- and developmental-accumulation pattern. The 'wall-bound' p-coumarate predominantly accumulated in young leaves and decreased in mature leaves, whereas acetate and ferulate mostly amassed in the cell wall of stems. Along the development of stem, the level of the 'wall-bound' ferulate gradually increased, while the basal level of p-coumarate further decreased. Induction of tension wood decreased the accumulation of the 'wall-bound' phenolics while the level of acetate remained constant. Synchrotron IR-mediated chemical compositional imaging revealed a close spatial distribution of acylesters with cell wall polysaccharides in poplar stem. These results indicate that different 'wall-bound' acylesters play distinct roles in poplar cell wall structural construction and/or metabolism of cell wall matrix components.

  1. Identifying new lignin bioengineering targets: 1. Monolignol-substitute impacts on lignin formation and cell wall fermentability

    PubMed Central

    2010-01-01

    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 of ester group hydroxylation

  2. Identifying new lignin bioengineering targets: impact of epicatechin, quercetin glycoside, and gallate derivatives on the lignification and fermentation of maize cell walls

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Apoplastic targeting of secondary metabolites compatible with monolignol polymerization may provide new avenues for designing lignins that are less inhibitory toward fiber fermentation. To identify suitable monolignol substitutes, we artificially lignified maize cell walls with normal monolignols pl...

  3. Measurement of three-dimensional normal vectors, principal curvatures, and wall thickness of the heart using cine-MRI

    NASA Astrophysics Data System (ADS)

    Coghlan, Leslie; Singleton, H. R.; Dell'Italia, L. J.; Linderholm, C. E.; Pohost, G. M.

    1995-05-01

    We have developed a method for measuring the detailed in vivo three dimensional geometry of the left and right ventricles using cine-magnetic resonance imaging. From data in the form of digitized short axis outlines, the normal vectors, principal curvatures and directions, and wall thickness were computed. The method was evaluated on simulated ellipsoids and on human MRI data. Measurements of normal vectors and of wall thickness were very accurate in simulated data and appeared appropriate in patient data. On simulated data, measurements of the principal curvature k1 (corresponding approximately to the short axis direction of the left ventricle) and of principal directions were quite accurate, but measurements of the other principal curvature (k2) were less accurate. The reasons behind this are considered. We expect improvements in the accuracy with thinner slices and improved representation of the surface data. Gradient echo images were acquired from 8 dogs with a 1.5T system (Philips Gyroscan) at baseline and four months after closed chest experimentally produced mitral regurgitation (MR). The product (k1 + k2) X wall thickness averaged over all slices at end-diastole was significantly lower after surgery (n equals 8, p < 0.005). These geometry changes were consistent with the expected increase in wall stress after MR.

  4. Engineering of plant cell walls for enhanced biofuel production.

    PubMed

    Loqué, Dominique; Scheller, Henrik V; Pauly, Markus

    2015-06-01

    The biomass of plants consists predominately of cell walls, a sophisticated composite material composed of various polymer networks including numerous polysaccharides and the polyphenol lignin. In order to utilize this renewable, highly abundant resource for the production of commodity chemicals such as biofuels, major hurdles have to be surpassed to reach economical viability. Recently, major advances in the basic understanding of the synthesis of the various wall polymers and its regulation has enabled strategies to alter the qualitative composition of wall materials. Such emerging strategies include a reduction/alteration of the lignin network to enhance polysaccharide accessibility, reduction of polymer derived processing inhibitors, and increases in polysaccharides with a high hexose/pentose ratio.

  5. Effects of posture on chest-wall configuration and motion during tidal breathing in normal men

    PubMed Central

    Takashima, Sachie; Nozoe, Masafumi; Mase, Kyoshi; Kouyama, Yusuke; Matsushita, Kazuhiro; Ando, Hiroshi

    2017-01-01

    [Purpose] The purpose of this study was to clarify the impact of postural changes during tidal breathing on the configuration and motion of chest-wall in order to further breathing motion evaluation. [Subjects and Methods] Chest-wall configuration and motion in the supine, right lateral, and sitting positions were measured using optoelectronic plethysmography in 15 healthy adult men. [Results] The anteroposterior diameters of the chest wall were significantly lower in the supine position for the pulmonary and abdominal rib cages, whereas the mediolateral diameters in the lateral position were lowest for the abdominal rib cage. Regarding chest-wall motion, both craniocaudal and anteroposterior motions of the anterior surface of the pulmonary and abdominal rib cages were significantly greater in the sitting position. Regarding motion of the left lateral abdominal rib cage, lateral motion was greatest in the lateral position. [Conclusion] Chest-wall configuration and motion changed according to posture in healthy men, particularly in the pulmonary and abdominal rib cages. PMID:28210033

  6. Resistance to antibiotics targeted to the bacterial cell wall.

    PubMed

    Nikolaidis, I; Favini-Stabile, S; Dessen, A

    2014-03-01

    Peptidoglycan is the main component of the bacterial cell wall. It is a complex, three-dimensional mesh that surrounds the entire cell and is composed of strands of alternating glycan units crosslinked by short peptides. Its biosynthetic machinery has been, for the past five decades, a preferred target for the discovery of antibacterials. Synthesis of the peptidoglycan occurs sequentially within three cellular compartments (cytoplasm, membrane, and periplasm), and inhibitors of proteins that catalyze each stage have been identified, although not all are applicable for clinical use. A number of these antimicrobials, however, have been rendered inactive by resistance mechanisms. The employment of structural biology techniques has been instrumental in the understanding of such processes, as well as the development of strategies to overcome them. This review provides an overview of resistance mechanisms developed toward antibiotics that target bacterial cell wall precursors and its biosynthetic machinery. Strategies toward the development of novel inhibitors that could overcome resistance are also discussed.

  7. Cell wall metabolism in Bacillus subtilis subsp. niger: accumulation of wall polymers in the supernatant of chemostat cultures.

    PubMed Central

    de Boer, W; Kruyssen, F J; Wouters, J T

    1981-01-01

    Cell wall polymers were measured both in the cells and in the cell-free medium of samples from steady-state chemostat cultures of Bacillus subtilis, growing at various rates under magnesium or phosphate limitation. The presence of both peptidoglycan and anionic wall polymers in the culture supernatant showed the occurrence of wall turnover in these cultures. Variable proportions of the total peptidoglycan present in the culture samples were found outside the cells in duplicate cultures, indicating that the rate of peptidoglycan turnover is variable in B. subtilis. Besides peptidoglycan, anionic wall polymers were detected in the culture supernatant: teichoic acid in magnesium-limited cultures and teichuronic acid in phosphate-limited cultures. In several samples, the ratio between the peptidoglycan and the anionic polymer concentrations was significantly lower in the extracellular fluid than in the walls. This divergency was attributed to the occurrence of direct secretion of anionic polymers after their synthesis. PMID:6787016

  8. Dynamic rheological properties of plant cell-wall particle dispersions.

    PubMed

    Day, Li; Xu, Mi; Øiseth, Sofia K; Lundin, Leif; Hemar, Yacine

    2010-12-01

    The rheological behaviour of plant cell-wall particle dispersions was investigated using dynamic oscillatory measurements. Two starting plant materials, broccoli stem and carrot were used and two types of particles were obtained by mechanically shearing blanched (80°C, 10 min) or cooked (100°C, 15 min) plant tissues. Blanching resulted in cell-wall particles made up of a collection of clusters of cells with an average particles size of ∼200 μm, while cooking generated nearly all single-cell particles with an average particle size of ∼80 μm. The rheological measurements showed that in the range of weight concentrations considered (∼0.5% to ∼8%) the dispersions behaved as elastic materials with the elastic modulus G' higher than G″ within the frequency range (0.01-10 Hz). This study shows that the behaviour of the complex modulus G* as a function of the effective volume fraction ϕ can be modelled using different theoretical equations. To do so, it is assumed that below a critical volume fraction ϕc a network of plant cell-wall particles was formed and G* as a function of ϕ obeys a power-law relationship. However above ϕc, where the particles were highly packed, G* could be modelled using theoretical equations developed for concentrated emulsions and elastic particle dispersions.

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

    SciTech Connect

    Peng, Zhaohua PEng; Ronald, Palmela; Wang, Guo-Liang

    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. Restrictive glycosylphosphatidylinositol anchor synthesis in cwh6/gpi3 yeast cells causes aberrant biogenesis of cell wall proteins.

    PubMed Central

    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 structures. The majority of the cell wall protein precursors that eventually left the ER were not covalently incorporated into the cell wall but were secreted into the growth medium. Despite the inefficient incorporation of cell wall proteins, there was no net effect on the protein level in the cell wall. It is postulated that the availability of GPI-dependent cell wall proteins determines the rate of cell wall construction and limits growth rate. PMID:9079905

  11. Pinoresinol reductase 1 impacts lignin distribution during secondary cell wall biosynthesis in Arabidopsis.

    PubMed

    Zhao, Qiao; Zeng, Yining; Yin, Yanbin; Pu, Yunqiao; Jackson, Lisa A; Engle, Nancy L; Martin, Madhavi Z; Tschaplinski, Timothy J; Ding, Shi-You; Ragauskas, Arthur J; Dixon, Richard A

    2015-04-01

    Pinoresinol reductase (PrR) catalyzes the conversion of the lignan (-)-pinoresinol to (-)-lariciresinol in Arabidopsis thaliana, where it is encoded by two genes, PrR1 and PrR2, that appear to act redundantly. PrR1 is highly expressed in lignified inflorescence stem tissue, whereas PrR2 expression is barely detectable in stems. Co-expression analysis has indicated that PrR1 is co-expressed with many characterized genes involved in secondary cell wall biosynthesis, whereas PrR2 expression clusters with a different set of genes. The promoter of the PrR1 gene is regulated by the secondary cell wall related transcription factors SND1 and MYB46. The loss-of-function mutant of PrR1 shows, in addition to elevated levels of pinoresinol, significantly decreased lignin content and a slightly altered lignin structure with lower abundance of cinnamyl alcohol end groups. Stimulated Raman scattering (SRS) microscopy analysis indicated that the lignin content of the prr1-1 loss-of-function mutant is similar to that of wild-type plants in xylem cells, which exhibit a normal phenotype, but is reduced in the fiber cells. Together, these data suggest an association of the lignan biosynthetic enzyme encoded by PrR1 with secondary cell wall biosynthesis in fiber cells.

  12. Pinoresinol reductase 1 impacts lignin distribution during secondary cell wall biosynthesis in Arabidopsis

    SciTech Connect

    Zhao, Qiao; Zeng, Yining; Yin, Yanbin; Pu, Yunqiao; Jackson, Lisa A.; Engle, Nancy L.; Martin, Madhavi Z.; Tschaplinski, Timothy J.; Ding, Shi-You; Ragauskas, Arthur J.; Dixon, Richard A.

    2014-08-05

    In this paper, pinoresinol reductase (PrR) catalyzes the conversion of the lignan (-)-pinoresinol to (-)-lariciresinol in Arabidopsis thaliana, where it is encoded by two genes, PrR1 and PrR2, that appear to act redundantly. PrR1 is highly expressed in lignified inflorescence stem tissue, whereas PrR2 expression is barely detectable in stems. Co-expression analysis has indicated that PrR1 is co-expressed with many characterized genes involved in secondary cell wall biosynthesis, whereas PrR2 expression clusters with a different set of genes. The promoter of the PrR1 gene is regulated by the secondary cell wall related transcription factors SND1 and MYB46. The loss-of-function mutant of PrR1 shows, in addition to elevated levels of pinoresinol, significantly decreased lignin content and a slightly altered lignin structure with lower abundance of cinnamyl alcohol end groups. Stimulated Raman scattering (SRS) microscopy analysis indicated that the lignin content of the prr1-1 loss-of-function mutant is similar to that of wild-type plants in xylem cells, which exhibit a normal phenotype, but is reduced in the fiber cells. Finally, together, these data suggest an association of the lignan biosynthetic enzyme encoded by PrR1 with secondary cell wall biosynthesis in fiber cells.

  13. Pinoresinol reductase 1 impacts lignin distribution during secondary cell wall biosynthesis in Arabidopsis

    DOE PAGES

    Zhao, Qiao; Zeng, Yining; Yin, Yanbin; ...

    2014-08-05

    In this paper, pinoresinol reductase (PrR) catalyzes the conversion of the lignan (-)-pinoresinol to (-)-lariciresinol in Arabidopsis thaliana, where it is encoded by two genes, PrR1 and PrR2, that appear to act redundantly. PrR1 is highly expressed in lignified inflorescence stem tissue, whereas PrR2 expression is barely detectable in stems. Co-expression analysis has indicated that PrR1 is co-expressed with many characterized genes involved in secondary cell wall biosynthesis, whereas PrR2 expression clusters with a different set of genes. The promoter of the PrR1 gene is regulated by the secondary cell wall related transcription factors SND1 and MYB46. The loss-of-function mutantmore » of PrR1 shows, in addition to elevated levels of pinoresinol, significantly decreased lignin content and a slightly altered lignin structure with lower abundance of cinnamyl alcohol end groups. Stimulated Raman scattering (SRS) microscopy analysis indicated that the lignin content of the prr1-1 loss-of-function mutant is similar to that of wild-type plants in xylem cells, which exhibit a normal phenotype, but is reduced in the fiber cells. Finally, together, these data suggest an association of the lignan biosynthetic enzyme encoded by PrR1 with secondary cell wall biosynthesis in fiber cells.« less

  14. Viscoelastic properties of cell walls of single living plant cells determined by dynamic nanoindentation.

    PubMed

    Hayot, Céline M; Forouzesh, Elham; Goel, Ashwani; Avramova, Zoya; Turner, Joseph A

    2012-04-01

    Plant development results from controlled cell divisions, structural modifications, and reorganizations of the cell wall. Thereby, regulation of cell wall behaviour takes place at multiple length scales involving compositional and architectural aspects in addition to various developmental and/or environmental factors. The physical properties of the primary wall are largely determined by the nature of the complex polymer network, which exhibits time-dependent behaviour representative of viscoelastic materials. Here, a dynamic nanoindentation technique is used to measure the time-dependent response and the viscoelastic behaviour of the cell wall in single living cells at a micron or sub-micron scale. With this approach, significant changes in storage (stiffness) and loss (loss of energy) moduli are captured among the tested cells. The results reveal hitherto unknown differences in the viscoelastic parameters of the walls of same-age similarly positioned cells of the Arabidopsis ecotypes (Col 0 and Ws 2). The technique is also shown to be sensitive enough to detect changes in cell wall properties in cells deficient in the activity of the chromatin modifier ATX1. Extensive computational modelling of the experimental measurements (i.e. modelling the cell as a viscoelastic pressure vessel) is used to analyse the influence of the wall thickness, as well as the turgor pressure, at the positions of our measurements. By combining the nanoDMA technique with finite element simulations quantifiable measurements of the viscoelastic properties of plant cell walls are achieved. Such techniques are expected to find broader applications in quantifying the influence of genetic, biological, and environmental factors on the nanoscale mechanical properties of the cell wall.

  15. Viscoelastic properties of cell walls of single living plant cells determined by dynamic nanoindentation

    PubMed Central

    Hayot, Céline M.; Forouzesh, Elham; Goel, Ashwani; Avramova, Zoya; Turner, Joseph A.

    2012-01-01

    Plant development results from controlled cell divisions, structural modifications, and reorganizations of the cell wall. Thereby, regulation of cell wall behaviour takes place at multiple length scales involving compositional and architectural aspects in addition to various developmental and/or environmental factors. The physical properties of the primary wall are largely determined by the nature of the complex polymer network, which exhibits time-dependent behaviour representative of viscoelastic materials. Here, a dynamic nanoindentation technique is used to measure the time-dependent response and the viscoelastic behaviour of the cell wall in single living cells at a micron or sub-micron scale. With this approach, significant changes in storage (stiffness) and loss (loss of energy) moduli are captured among the tested cells. The results reveal hitherto unknown differences in the viscoelastic parameters of the walls of same-age similarly positioned cells of the Arabidopsis ecotypes (Col 0 and Ws 2). The technique is also shown to be sensitive enough to detect changes in cell wall properties in cells deficient in the activity of the chromatin modifier ATX1. Extensive computational modelling of the experimental measurements (i.e. modelling the cell as a viscoelastic pressure vessel) is used to analyse the influence of the wall thickness, as well as the turgor pressure, at the positions of our measurements. By combining the nanoDMA technique with finite element simulations quantifiable measurements of the viscoelastic properties of plant cell walls are achieved. Such techniques are expected to find broader applications in quantifying the influence of genetic, biological, and environmental factors on the nanoscale mechanical properties of the cell wall. PMID:22291130

  16. Penium margaritaceum as a model organism for cell wall analysis of expanding plant cells.

    PubMed

    Rydahl, Maja G; Fangel, Jonatan U; Mikkelsen, Maria Dalgaard; Johansen, I Elisabeth; Andreas, Amanda; Harholt, Jesper; Ulvskov, Peter; Jørgensen, Bodil; Domozych, David S; Willats, William G T

    2015-01-01

    The growth of a plant cell encompasses a complex set of subcellular components interacting in a highly coordinated fashion. Ultimately, these activities create specific cell wall structural domains that regulate the prime force of expansion, internally generated turgor pressure. The precise organization of the polymeric networks of the cell wall around the protoplast also contributes to the direction of growth, the shape of the cell, and the proper positioning of the cell in a tissue. In essence, plant cell expansion represents the foundation of development. Most studies of plant cell expansion have focused primarily upon late divergent multicellular land plants and specialized cell types (e.g., pollen tubes, root hairs). Here, we describe a unicellular green alga, Penium margaritaceum (Penium), which can serve as a valuable model organism for understanding cell expansion and the underlying mechanics of the cell wall in a single plant cell.

  17. (Rapid regulatory control of plant cell expansion and wall relaxation)

    SciTech Connect

    Cosgrove, D.J.

    1990-01-01

    This section presents a brief overview of accomplishments related to this project in the past 3-year period. Our work has focused on the basic mechanisms of plant cell expansion, particularly on the interrelations of water and solute transport with cell wall relaxation and expansion. To study these processes, we have developed new methods and used these methods to analyze the dynamic behavior of growth processes and to examine how various agents (GA, drought, light, genetic lesions) alter the growth machinery of the cell.

  18. Tomato Fruit Cell Wall Synthesis during Development and Senescence : In Vivo Radiolabeling of Wall Fractions Using [C]Sucrose.

    PubMed

    Mitcham, E J; Gross, K C; Ng, T J

    1989-02-01

    The pedicel of tomato fruit (Lycopersicon esculentum Mill., cv ;Rutgers') of different developmental stages from immature-green (IG) to red was injected on the vine with 7 microcuries [(14)C(U)]sucrose and harvested after 18 hours. Cell walls were isolated from outer pericarp and further fractionated yielding ionically associated pectin, covalently bound pectin, hemicellulosic fraction I, hemicellulosic fraction II, and cellulosic fraction II. The dry weight of the total cell wall and of each cell wall fraction per gram fresh weight of pericarp tissue decreased after the mature-green (MG) stage of development. Incorporation of radiolabeled sugars into each fraction decreased from the IG to MG3 (locules jellied but still green) stage. Incorporation in all fractions increased from MG3 to breaker and turning (T) and then decreased from T to red. Data indicate that cell wall synthesis continues throughout ripening and increases transiently from MG4 (locules jellied and yellow to pink in color) to T, corresponding to the peak in respiration and ethylene synthesis during the climacteric. Synthesis continued at a time when total cell wall fraction dry weight decreased indicating the occurrence of cell wall turnover. Synthesis and insertion of a modified polymer with removal of other polymers may produce a less rigid cell wall and allow softening of the tissue integrity during ripening.

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

    PubMed

    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.

  20. Combined histochemistry and autofluorescence for identifying lignin distribution in cell walls.

    PubMed

    De Micco, V; Aronne, G

    2007-08-01

    Histological staining methods commonly used for detecting cellulose and lignin in cell walls were combined with epifluorescence microscopy to visualize differences in lignification between and within cellular elements. We tested our approach on sections of one-year-old branches of Fraxinus ornus L., Myrtus communis L., Olea europaea L., Pistacia lentiscus L. and Rhamnus alaternus L., containing both normal and tension wood. Sections were subjected to various staining techniques, viz. safranin O, safranin O/fast green FCF, and alcoholic solutions of safranin O/astra blue, according to the commonly accepted protocols. Stained and unstained sections were compared using both light and epifluorescence microscopy. Safranin O with or without counterstaining hid the strong fluorescence of vessel walls, cell corners and middle lamellae allowing the secondary wall fibers to fluoresce more clearly. Epifluorescence microscopy applied to stained sections showed more cell wall details than autofluorescence of unstained sections or white light microscopy of counterstained sections. This simple approach proved reliable and valuable for detecting differences in lignification in thick sections without the need for costly equipment.

  1. Metabolomic analysis of normal and sickle cell erythrocytes.

    PubMed

    Darghouth, D; Koehl, B; Junot, C; Roméo, P-H

    2010-09-01

    Metabolic signatures of specialized circulating hematopoietic cells in physiological or human hematological diseases start to be described. We use a simple and highly reproductive extraction method of erythrocytes metabolites coupled with a liquid chromatography-mass spectrometry based metabolites profiling method to determine metabolomes of normal and sickle cell erythrocytes. Sickle cell erythrocytes and normal erythrocytes metabolomes display major differences in glycolysis, in glutathione, in ascorbate metabolisms and in metabolites associated to membranes turnover. In addition, the amounts of metabolites derived from urea cycle and NO metabolism that partly take place within erythrocyte were different between normal and sickle cell erythrocytes. These results show that metabolic profiling of red blood cell diseases can now be determined and might indicate new biomarkers that can be used for the follow-up of sickle cell patients.

  2. Microfluidic channel for characterizing normal and breast cancer cells

    NASA Astrophysics Data System (ADS)

    TruongVo, T. N.; Kennedy, R. M.; Chen, H.; Chen, A.; Berndt, A.; Agarwal, M.; Zhu, L.; Nakshatri, H.; Wallace, J.; Na, S.; Yokota, H.; Ryu, J. E.

    2017-03-01

    A microfluidic channel was designed and fabricated for the investigation of behaviors of normal and cancer cells in a narrow channel. A specific question addressed in this study was whether it is possible to distinguish normal versus cancer cells by detecting their stationary and passing behaviors through a narrow channel. We hypothesized that due to higher deformability, softer cancer cells will pass through the channel further and quicker than normal cells. Two cell lines, employed herein, were non-tumor breast epithelial cells (MCF-10A; 11.2  ±  2.4 µm in diameter) and triple negative breast cancer cells (MDA-MB-231; 12.4  ±  2.1 µm in diameter). The microfluidic channel was 300 µm long and linearly tapered with a width of 30 µm at an inlet to 5 µm at an outlet. The result revealed that MDA-MB-231 cells entered and stuck further toward the outlet than MCF-10A cells in response to a slow flow (2 µl min‑1). Further, in response to a fast flow (5 µl min‑1), the passage time (mean  ±  s.d.) was 26.6  ±  43.9 s for normal cells (N  =  158), and 1.9  ±  1.4 s for cancer cells (N  =  128). The measurement of stiffness by atomic force microscopy as well as model-based predictions pointed out that MDA-MB-231 cells are significantly softer than MCF-10A cells. Collectively, the result in this study suggests that analysis of an individual cell’s behavior through a narrow channel can characterize deformable cancer cells from normal ones, supporting the possibility of enriching circulating tumor cells using novel microfluidics-based analysis.

  3. Plant cell walls: Protecting the barrier from degradation by microbial enzymes.

    PubMed

    Lagaert, Stijn; Beliën, Tim; Volckaert, Guido

    2009-12-01

    Plant cell walls are predominantly composed of polysaccharides, which are connected in a strong, yet resilient network. They determine the size and shape of plant cells and form the interface between the cell and its often hostile environment. To penetrate the cell wall and thus infect plants, most phytopathogens secrete numerous cell wall degrading enzymes. Conversely, as a first line of defense, plant cell walls contain an array of inhibitors of these enzymes. Scientific knowledge on these inhibitors significantly progressed in the past years and this review is meant to give a comprehensive overview of plant inhibitors against microbial cell wall degrading enzymes and their role in plant protection.

  4. Cell wall bound anionic peroxidases from asparagus byproducts.

    PubMed

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

    2014-10-08

    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.

  5. Characterisation of cell wall polysaccharides from rapeseed (Brassica napus) meal.

    PubMed

    Pustjens, Annemieke M; Schols, Henk A; Kabel, Mirjam A; Gruppen, Harry

    2013-11-06

    To enable structural characteristics of individual cell wall polysaccharides from rapeseed (Brassica napus) meal (RSM) to be studied, polysaccharide fractions were sequentially extracted. Fractions were analysed for their carbohydrate (linkage) composition and polysaccharide structures were also studied by enzymatic fingerprinting. The RSM fractions analysed contained pectic polysaccharides: homogalacturonan in which 60% of the galacturonic acid residues are methyl-esterified, arabinan branched at the O-2 position and arabinogalactan mainly type II. This differs from characteristics previously reported for Brassica campestris meal, another rapeseed cultivar. Also, in the alkali extracts hemicelluloses were analysed as xyloglucan both of the XXGG- and XXXG-type decorated with galactosyl, fucosyl and arabinosyl residues, and as xylan with O-methyl-uronic acid attached. The final residue after extraction still contained xyloglucan and remaining (pectic) polysaccharides next to cellulose, showing that the cell wall matrix of RSM is very strongly interconnected.

  6. Compounds active against cell walls of medically important fungi.

    PubMed Central

    Hector, R F

    1993-01-01

    A number of substances that directly or indirectly affect the cell walls of fungi have been identified. Those that actively interfere with the synthesis or degradation of polysaccharide components share the property of being produced by soil microbes as secondary metabolites. Compounds specifically interfering with chitin or beta-glucan synthesis have proven effective in studies of preclinical models of mycoses, though they appear to have a restricted spectrum of coverage. Semisynthetic derivatives of some of the natural products have offered improvements in activity, toxicology, or pharmacokinetic behavior. Compounds which act on the cell wall indirectly or by a secondary mechanism of action, such as the azoles, act against diverse fungi but are usually fungistatic in nature. Overall, these compounds are attractive candidates for further development. PMID:8457977

  7. Cell wall teichoic acids of two Brevibacterium strains.

    PubMed

    Shashkov, A S; Potekhina, N V; Evtushenko, L I; Naumova, I B

    2004-06-01

    Structurally identical teichoic acids were detected in cell walls of two soil isolates assigned to Brevibacterium linens based on phylogenetic data. Both cell walls contain unsubstituted 1,3-poly(glycerol phosphate) and poly(glycosylglycerol phosphate). Repeating units of the latter--alpha-D-GlcpNAc-(1-->4)-beta-D-Galp-(1-->1)-Gro--are bound by phosphodiester bonds including OH-3 of galactose and OH-3 of glycerol. Some of the N-acetylglucosamine residues have 4,6-pyruvic acid acetal, amounts of the latter in the two strains being unequal. Species-specificity of the structures of teichoic acids in the genus Brevibacterium is discussed.

  8. Dynamics of cell wall elasticity pattern shapes the cell during yeast mating morphogenesis

    PubMed Central

    Goldenbogen, Björn; Giese, Wolfgang; Hemmen, Marie; Uhlendorf, Jannis; Herrmann, Andreas

    2016-01-01

    The cell wall defines cell shape and maintains integrity of fungi and plants. When exposed to mating pheromone, Saccharomyces cerevisiae grows a mating projection and alters in morphology from spherical to shmoo form. Although structural and compositional alterations of the cell wall accompany shape transitions, their impact on cell wall elasticity is unknown. In a combined theoretical and experimental approach using finite-element modelling and atomic force microscopy (AFM), we investigated the influence of spatially and temporally varying material properties on mating morphogenesis. Time-resolved elasticity maps of shmooing yeast acquired with AFM in vivo revealed distinct patterns, with soft material at the emerging mating projection and stiff material at the tip. The observed cell wall softening in the protrusion region is necessary for the formation of the characteristic shmoo shape, and results in wider and longer mating projections. The approach is generally applicable to tip-growing fungi and plants cells. PMID:27605377

  9. Dynamics of cell wall elasticity pattern shapes the cell during yeast mating morphogenesis.

    PubMed

    Goldenbogen, Björn; Giese, Wolfgang; Hemmen, Marie; Uhlendorf, Jannis; Herrmann, Andreas; Klipp, Edda

    2016-09-01

    The cell wall defines cell shape and maintains integrity of fungi and plants. When exposed to mating pheromone, Saccharomyces cerevisiae grows a mating projection and alters in morphology from spherical to shmoo form. Although structural and compositional alterations of the cell wall accompany shape transitions, their impact on cell wall elasticity is unknown. In a combined theoretical and experimental approach using finite-element modelling and atomic force microscopy (AFM), we investigated the influence of spatially and temporally varying material properties on mating morphogenesis. Time-resolved elasticity maps of shmooing yeast acquired with AFM in vivo revealed distinct patterns, with soft material at the emerging mating projection and stiff material at the tip. The observed cell wall softening in the protrusion region is necessary for the formation of the characteristic shmoo shape, and results in wider and longer mating projections. The approach is generally applicable to tip-growing fungi and plants cells.

  10. Single-molecule imaging reveals modulation of cell wall synthesis dynamics in live bacterial cells

    PubMed Central

    Lee, Timothy K.; Meng, Kevin; Shi, Handuo; Huang, Kerwyn Casey

    2016-01-01

    The peptidoglycan cell wall is an integral organelle critical for bacterial cell shape and stability. Proper cell wall construction requires the interaction of synthesis enzymes and the cytoskeleton, but it is unclear how the activities of individual proteins are coordinated to preserve the morphology and integrity of the cell wall during growth. To elucidate this coordination, we used single-molecule imaging to follow the behaviours of the two major peptidoglycan synthases in live, elongating Escherichia coli cells and after perturbation. We observed heterogeneous localization dynamics of penicillin-binding protein (PBP) 1A, the synthase predominantly associated with cell wall elongation, with individual PBP1A molecules distributed between mobile and immobile populations. Perturbations to PBP1A activity, either directly through antibiotics or indirectly through PBP1A's interaction with its lipoprotein activator or other synthases, shifted the fraction of mobile molecules. Our results suggest that multiple levels of regulation control the activity of enzymes to coordinate peptidoglycan synthesis. PMID:27774981

  11. Enzyme Amplified Detection of Microbial Cell Wall Components

    NASA Technical Reports Server (NTRS)

    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.

  12. Substitution of L-fucose by L-galactose in cell walls of arabidopsis mur1

    SciTech Connect

    Zablackis, E.; York, W.S.; Pauly, M.

    1996-06-21

    An Arabidopsis thaliana mutant (mur1) has less than 2 percent of the normal amounts of L-fucose in the primary cell walls of aerial portions of the plant. The survival of mur1 plants challenged the hypothesis that fucose is a required component of biologically active oligosaccharides derived from cell wall xyloglucan. However, the replacement of L-fucose (that is, 6-deoxyl-L-galactose) by L-galactose does not detectably alter the biological activity of the oligosaccharides derived from xyloglucan. Thus, essential structural and conformational features of xyloglucan and xyloglucan-derived oligosaccharides are retained when L-galactose replaces L-fucose. 29 refs., 2 figs., 2 tabs.

  13. Proteomic Analysis to Identify Tightly-Bound Cell Wall Protein in Rice Calli

    PubMed Central

    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. Based on bioinformatics analyses, 389 classical rice cell wall proteins, possessing a signal peptide, and 334 putative non-classical cell wall proteins, lacking a signal peptide, were identified. By combining previously established rice cell wall protein databases with current data for the classical rice cell wall proteins, a comprehensive rice cell wall proteome, comprised of 496 proteins, was constructed. A comparative analysis of the rice and Arabidopsis cell wall proteomes revealed a high level of homology, suggesting a predominant conservation between monocot and eudicot cell wall proteins. This study importantly increased information on cell wall proteins, which serves for future functional analyses of these identified rice cell wall proteins. PMID:26194822

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

    SciTech Connect

    Meyerowitz, Elliot M.

    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.

  15. Fungal invasion of normally non-phagocytic host cells.

    PubMed

    Filler, Scott G; Sheppard, Donald C

    2006-12-01

    Many fungi that cause invasive disease invade host epithelial cells during mucosal and respiratory infection, and subsequently invade endothelial cells during hematogenous infection. Most fungi invade these normally non-phagocytic host cells by inducing their own uptake. Candida albicans hyphae interact with endothelial cells in vitro by binding to N-cadherin on the endothelial cell surface. This binding induces rearrangement of endothelial cell microfilaments, which results in the endocytosis of the organism. The capsule of Cryptococcus neoformans is composed of glucuronoxylomannan, which binds specifically to brain endothelial cells, and appears to mediate both adherence and induction of endocytosis. The mechanisms by which other fungal pathogens induce their own uptake are largely unknown. Some angioinvasive fungi, such as Aspergillus species and the Zygomycetes, invade endothelial cells from the abluminal surface during the initiation of invasive disease, and subsequently invade the luminal surface of endothelial cells during hematogenous dissemination. Invasion of normally non-phagocytic host cells has different consequences, depending on the type of invading fungus. Aspergillus fumigatus blocks apoptosis of pulmonary epithelial cells, whereas Paracoccidioides brasiliensis induces apoptosis of epithelial cells. This review summarizes the mechanisms by which diverse fungal pathogens invade normally non-phagocytic host cells and discusses gaps in our knowledge that provide opportunities for future research.

  16. Fungal Invasion of Normally Non-Phagocytic Host Cells

    PubMed Central

    Filler, Scott G; Sheppard, Donald C

    2006-01-01

    Many fungi that cause invasive disease invade host epithelial cells during mucosal and respiratory infection, and subsequently invade endothelial cells during hematogenous infection. Most fungi invade these normally non-phagocytic host cells by inducing their own uptake. Candida albicans hyphae interact with endothelial cells in vitro by binding to N-cadherin on the endothelial cell surface. This binding induces rearrangement of endothelial cell microfilaments, which results in the endocytosis of the organism. The capsule of Cryptococcus neoformans is composed of glucuronoxylomannan, which binds specifically to brain endothelial cells, and appears to mediate both adherence and induction of endocytosis. The mechanisms by which other fungal pathogens induce their own uptake are largely unknown. Some angioinvasive fungi, such as Aspergillus species and the Zygomycetes, invade endothelial cells from the abluminal surface during the initiation of invasive disease, and subsequently invade the luminal surface of endothelial cells during hematogenous dissemination. Invasion of normally non-phagocytic host cells has different consequences, depending on the type of invading fungus. Aspergillus fumigatus blocks apoptosis of pulmonary epithelial cells, whereas Paracoccidioides brasiliensis induces apoptosis of epithelial cells. This review summarizes the mechanisms by which diverse fungal pathogens invade normally non-phagocytic host cells and discusses gaps in our knowledge that provide opportunities for future research. PMID:17196036

  17. Progress toward the tomato fruit cell wall proteome

    PubMed Central

    Ruiz-May, Eliel; Rose, Jocelyn K. C.

    2013-01-01

    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. PMID:23755055

  18. Lignin variability in plant cell walls: contribution of new models.

    PubMed

    Neutelings, Godfrey

    2011-10-01

    Lignin is a major component of certain plant cell walls. The enzymes and corresponding genes associated with the metabolic pathway leading to the production of this complex phenolic polymer have been studied for many years now and are relatively well characterized. The use of genetically modified model plants (Arabidopsis, tobacco, poplar.) and mutants has contributed greatly to our current understanding of this process. The recent utilisation and/or development of a number of dedicated genomic and transcriptomic tools for other species opens new perspectives for advancing our knowledge of the biological role of this important polymer in less typical situations and/or species. In this context, studies on the formation of hypolignified G-type fibres in angiosperm tension wood, and the natural hypolignification of secondary cell walls in plant bast fibre species such as hemp (Cannabis sativa), flax (Linum usitatissimum) or ramie (Boehmeria nivea) are starting to provide novel information about how plants control secondary cell wall formation. Finally, other biologically interesting species for which few molecular resources currently exist could also represent interesting future models.

  19. Cell Wall β-(1,6)-Glucan of Saccharomyces cerevisiae

    PubMed Central

    Aimanianda, Vishukumar; Clavaud, Cécile; Simenel, Catherine; Fontaine, Thierry; Delepierre, Muriel; Latgé, Jean-Paul

    2009-01-01

    Despite its essential role in the yeast cell wall, the exact composition of the β-(1,6)-glucan component is not well characterized. While solubilizing the cell wall alkali-insoluble fraction from a wild type strain of Saccharomyces cerevisiae using a recombinant β-(1,3)-glucanase followed by chromatographic characterization of the digest on an anion exchange column, we observed a soluble polymer that eluted at the end of the solvent gradient run. Further characterization indicated this soluble polymer to have a molecular mass of ∼38 kDa and could be hydrolyzed only by β-(1,6)-glucanase. Gas chromatographymass spectrometry and NMR (1H and 13C) analyses confirmed it to be a β-(1,6)-glucan polymer with, on average, branching at every fifth residue with one or two β-(1,3)-linked glucose units in the side chain. This polymer peak was significantly reduced in the corresponding digests from mutants of the kre genes (kre9 and kre5) that are known to play a crucial role in the β-(1,6)-glucan biosynthesis. In the current study, we have developed a biochemical assay wherein incubation of UDP-[14C]glucose with permeabilized S. cerevisiae yeasts resulted in the synthesis of a polymer chemically identical to the branched β-(1,6)-glucan isolated from the cell wall. Using this assay, parameters essential for β-(1,6)-glucan synthetic activity were defined. PMID:19279004

  20. Adsorption of polycyclic aromatic hydrocarbons (PAHs) on Rhizopus oryzae cell walls: application of cosolvent models for validating the cell wall-water partition coefficient.

    PubMed

    Ma, Bin; Xu, Minmin; Wang, Jiaojiao; Chen, Huaihai; He, Yan; Wu, Laosheng; Wang, Haizhen; Xu, Jianming

    2011-11-01

    The cell wall-cosolvent partition coefficients (Km) of polycyclic aromatic hydrocarbons (PAHs) were determined for Rhizopus oryzae cell walls by controlling the volume fraction of methanol (f) ranging from 0.1 to 0.5. Five cosolvent models were employed for extrapolating the cell wall-water partition coefficients (Kw) in pure water. The extrapolated Kw values of four PAHs on R. oryzae cell walls were ranged from 2.9 to 5.1. Comparison of various Kw values of pyrene generated from extrapolation and the QSPR model, together with predicted different (PD), mean percentage deviations (MPD), and root mean square errors (RSE), revealed that the performance of the LL and Bayesian models were the best among all five tested cosolvent models. This study suggests that R. oryzae cell walls play an important role in the partitioning of PAHs during bioremediation because of the high Kw of fungal cell walls.

  1. Role of Multivalent Cations in the Organization, Structure, and Assembly of the Cell Wall of Pseudomonas aeruginosa

    PubMed Central

    Asbell, Mary A.; Eagon, R. G.

    1966-01-01

    Asbell, Mary A. (University of Georgia, Athens), and R. G. Eagon. Role of multivalent cations in the organization, structure, and assembly of the cell wall of Pseudomonas aeruginosa. J. Bacteriol. 92:380–387. 1966. —Incubation of Pseudomonas aeruginosa with ethylenediaminetetraacetate induced the formation of osmotically fragile rods termed osmoplasts. These could be restored to osmotically stable forms by multivalent cations. Only those cells restored by divalent cations normally found in the cell wall were capable of multiplication. The respiration of restored cells, however, was unimpaired, irrespective of whether they were capable of multiplication. Moreover, the permeability characteristics of osmoplasts and restored cells were unimpaired. When multivalent cations were chelated from the cell wall and replaced by sodium, a weakened cell wall and an osmotically fragile cell resulted. This was apparently caused by the absence of cross-linkages in the cell wall via multivalent cations. Tris(hydroxymethyl)aminomethane buffer compounded the lethal effects of ethylenediaminetetraacetate. The lipopolysaccharide component was inferred to be the site of attack by ethylenediaminetetraacetate. A mechanism for the synthesis of the lipopolysaccharide sacculus was proposed whereby negatively charged subunits are “trapped” by forming ionic and coordinate bonds intermediated by multivalent cations. PMID:16562124

  2. Hypergravity Effects on Dendritic Cells and Vascular Wall Interactions

    NASA Astrophysics Data System (ADS)

    Bellik, L.; Parenti, A.; Ledda, F.; Basile, V.; Romano, G.; Fusi, F.; Monici, M.

    2009-01-01

    Dendritic cells (DCs), the most potent antigen-presenting cells inducing specific immune responses, are involved in the pathogenesis of atherosclerosis. In this inflammatory disease, DCs increase in number, being particularly abundant in the shoulder regions of plaques. Since the exposure to altered gravitational conditions results in a significant impairment of the immune function, the aim of this study was to investigate the effects of hypergravity on both the function of DCs and their interactions with the vascular wall cells. Monocytes from peripheral blood mononuclear cells of healthy volunteers were sorted by CD14+ magnetic beads selection, cultured for 6 days in medium supplemented with GM-CSF and IL-4, followed by a further maturation stimulus. DC phenotype, assessed by flow cytometry, showed a high expression of the specific DC markers CD80, CD86, HLA-DR and CD83. The DCs obtained were then exposed to hypergravitational stimuli and their phenotype, cytoskeleton, ability to activate lymphocytes and interaction with vascular wall cells were investigated. The findings showed that the exposure to hypergravity conditions resulted in a significant impairment of DC cytoskeletal organization, without affecting the expression of DC markers. Moreover, an increase in DC adhesion to human vascular smooth muscle cells and in their ability to activate lymphocytes was observed.

  3. Evaluating fundamental position-dependent differences in wood cell wall adhesion using nanoindentation.

    PubMed

    Obersriebnig, Michael; Konnerth, Johannes; Gindl-Altmutter, Wolfgang

    2013-01-01

    Spruce wood specimens were bonded with one-component polyurethane (PUR) and urea-formaldehyde (UF) adhesive, respectively. The adhesion of the adhesives to the wood cell wall was evaluated at two different locations by means of a new micromechanical assay based on nanoindentation. One location tested corresponded to the interface between the adhesive and the natural inner cell wall surface of the secondary cell wall layer 3 (S3), whereas the second location corresponded to the interface between the adhesive and the freshly cut secondary cell wall layer 2 (S2). Overall, a trend towards reduced cell wall adhesion was found for PUR compared to UF. Position-resolved examination revealed excellent adhesion of UF to freshly cut cell walls (S2) but significantly diminished adhesion to the inner cell wall surface (S3). In contrast, PUR showed better adhesion to the inner cell wall surface and less adhesion to freshly cut cell walls. Atomic force microscopy revealed a less polar character for the inner cell wall surface (S3) compared to freshly cut cell walls (S2). It is proposed that differences in the polarity of the used adhesives and the surface chemistry of the two cell wall surfaces examined account for the observed trends.

  4. Cell Wall Composition and Candidate Biosynthesis Gene Expression During Rice Development.

    PubMed

    Lin, Fan; Manisseri, Chithra; Fagerström, Alexandra; Peck, Matthew L; Vega-Sánchez, Miguel E; Williams, Brian; Chiniquy, Dawn M; Saha, Prasenjit; Pattathil, Sivakumar; Conlin, Brian; Zhu, Lan; Hahn, Michael G; Willats, William G T; Scheller, Henrik V; Ronald, Pamela C; Bartley, Laura E

    2016-10-01

    Cell walls of grasses, including cereal crops and biofuel grasses, comprise the majority of plant biomass and intimately influence plant growth, development and physiology. However, the functions of many cell wall synthesis genes, and the relationships among and the functions of cell wall components remain obscure. To better understand the patterns of cell wall accumulation and identify genes that act in grass cell wall biosynthesis, we characterized 30 samples from aerial organs of rice (Oryza sativa cv. Kitaake) at 10 developmental time points, 3-100 d post-germination. Within these samples, we measured 15 cell wall chemical components, enzymatic digestibility and 18 cell wall polysaccharide epitopes/ligands. We also used quantitative reverse transcription-PCR to measure expression of 50 glycosyltransferases, 15 acyltransferases and eight phenylpropanoid genes, many of which had previously been identified as being highly expressed in rice. Most cell wall components vary significantly during development, and correlations among them support current understanding of cell walls. We identified 92 significant correlations between cell wall components and gene expression and establish nine 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 improved grasses for use in lignocellulosic biofuel production and agriculture.

  5. Modeling of thin, back-wall silicon solar cells

    NASA Technical Reports Server (NTRS)

    Baraona, C. R.

    1979-01-01

    The performance of silicon solar cells with p-n junctions on the nonilluminated surface (i.e., upside-down or back-wall cells) was calculated. These structures consisted of a uniformly shaped p-type substrate layer, a p(+)-type field layer on the front (illuminated) surface, and a shallow, n-type junction on the back (nonilluminated) surface. A four-layer solar cell model was used to calculate efficiency, open-circuit voltage, and short-circuit current. The effect on performance of p-layer thickness and resistivity was determined. The diffusion length was varied to simulate the effect of radiation damage. The results show that peak initial efficiencies greater than 15 percent are possible for cell thicknesses or 100 micrometers or less. After 10 years of radiation damage in geosynchronous orbit, thin (25 to 50 micrometers thick) cells made from 10 to 100 ohm cm material show the smallest decrease (approximately 10 percent) in performance.

  6. The Tomato Fruit Cell Wall : II. Polyuronide Metabolism in a Nonsoftening Tomato Mutant.

    PubMed

    Koch, J L; Nevins, D J

    1990-03-01

    A nonsoftening tomato (Lycopersicon esculentum L.) variety, dg, was examined to assess the physiological basis for its inability to soften during ripening. Total uronic acid levels, 18 milligrams uronic acid/100 milligrams wall, and the extent of pectin esterification, 60 mole%, remained constant throughout fruit development in this mutant. The proportion of uronic acid susceptible to polygalacturonase in vitro also remained constant. Pretreatment of heat-inactivated dg fruit cell walls with tomato pectinmethylesterase enhances polygalacturonase susceptibility at all ripening stages. Pectinesterase activity of cell wall protein extracts from red ripe dg fruit was half that in extracts from analogous tissue of VF145B. Polygalacturonase activities of cell wall extracts, however, were similar in both varieties. Diffusion of uronic acid from tissue discs of both varieties increased beginning at the turning stage to a maximum of 2.0 milligrams uronic acid released/gram fresh weight at the ripe stage. The increased quantity of hydrolytic products released during ripening suggests the presence of in situ polygalacturonase activity. Low speed centrifugation was employed to induce efflux of uronide components from the cell wall tree space. In normal fruit, at the turning stage, 2.1 micrograms uronic acid/gram fresh weight was present in the eluant after 1 hour, and this value increased to a maximum of 8.2 micrograms uronic acid/gram fresh weight at the red ripe stage. However, centrifuge-aided extraction of hydrolytic products failed to provide evidence for in situ polygalacturonase activity in dg fruit. We conclude that pectinesterase and polygalacturonase enzymes are not active in situ during the ripening of dg fruit. This could account for the maintenance of firmness in ripe fruit tissue.

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

    SciTech Connect

    Bahrin, Muhammad Hannan Rahman, Anwar Abdul Hamzah, Mohd Arif Mamat, Mohd Rizal; Azman, Azraf; Hasan, Hasni

    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.

  8. Evidence for 'silicon' within the cell walls of suspension-cultured rice cells.

    PubMed

    He, Congwu; Wang, Lijun; Liu, Jian; Liu, Xin; Li, Xiuli; Ma, Jie; Lin, Yongjun; Xu, Fangsen

    2013-11-01

    Despite the ubiquity and beneficial role of silicon (Si) in plant biology, structural and chemical mechanisms operating at the single-cell level have not been extensively studied. To obtain insights regarding the effect of Si on individual cells, we cultivated suspended rice (Oryza sativa) cells in the absence and presence of Si and analyzed single cells using a combination of physical techniques including atomic force microscopy (AFM). Si is naturally present as a constituent of the cell walls, where it is firmly bound to the cell wall matrix rather than occurring within intra- or extracellular silica deposition, as determined by using inductively coupled plasma mass spectrometry (ICP-MS) and X-ray photoelectron spectroscopy (XPS). This species of Si, linked with the cell wall matrix, improves the structural stability of cell walls during their expansion and subsequent cell division. Maintaining cell shape is thereby enhanced, which may be crucial for the function and survival of cells. This study provides further evidence that organosilicon is present in plant cell walls, which broadens our understanding of the chemical nature of 'anomalous Si' in plant biology.

  9. Phenotypic plasticity in normal breast derived epithelial cells

    PubMed Central

    2014-01-01

    Background Normal, healthy human breast tissue from a variety of volunteer donors has become available for research thanks to the establishment of the Susan G. Komen for the Cure® Tissue Bank at the IU Simon Cancer Center (KTB). Multiple epithelial (K-HME) and stromal cells (K-HMS) were established from the donated tissue. Explant culture was utilized to isolate the cells from pieces of breast tissue. Selective media and trypsinization were employed to select either epithelial cells or stromal cells. The primary, non-transformed epithelial cells, the focus of this study, were characterized by immunohistochemistry, flow cytometry, and in vitro cell culture. Results All of the primary, non-transformed epithelial cells tested have the ability to differentiate in vitro into a variety of cell types when plated in or on biologic matrices. Cells identified include stratified squamous epithelial, osteoclasts, chondrocytes, adipocytes, neural progenitors/neurons, immature muscle and melanocytes. The cells also express markers of embryonic stem cells. Conclusions The cell culture conditions employed select an epithelial cell that is pluri/multipotent. The plasticity of the epithelial cells developed mimics that seen in metaplastic carcinoma of the breast (MCB), a subtype of triple negative breast cancer; and may provide clues to the origin of this particularly aggressive type of breast cancer. The KTB is a unique biorepository, and the normal breast epithelial cells isolated from donated tissue have significant potential as new research tools. PMID:24915897

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

    PubMed

    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.

  11. [Large artery wall properties in dialyse and renal transplant patients with normal blood pressure].

    PubMed

    Posadzy-Małaczyńska, Anna; Kosch, Marcus; Hausberg, Martin; Rahn, Karl H; Małaczyński, Paweł; Głuszek, Jerzy; Tykarski, Andrzej

    2004-01-01

    Structural and mechanical properties of the arterial wall are altered in patients with renal failure. Age and hypertension are known to affect the vessel wall structure. Aging process of arterial wall appears to be accelerated in patients with end-stage renal failure. The mechanisms responsible for reduced arterial compliance and distensibility in dialyse patients and renal transplant recipients without hypertension remain to be evaluated. 20 normotensive dialyse patients (D), 20 normotensive renal transplant recipients (T) and 20 healthy volunteers (N) matched for age, sex and blood pressure as controls were enrolled in to the study. Patients with cardiovascular risk factors and diabetes were excluded. The arterial blood pressure of all patients placed below 140/90 mmHg. The dialyse patients and renal transplant recipients were eligible for the study if the serum creatinine level was below 2 mg/dl. In all subjects, fasting concentrations of serum creatinine, total cholesterol, HDL-cholesterol, LDL-cholesterol, hemoglobin and glucose were determined at enrollment to the study. Long-term immunosuppression consisted of cyclosporine and prednisolone. Blood pressure was measured using an automatic sphygmomanometer (Criticon Dinamap model 1846 SX). Pulse wave velocity (PWV) was evaluated using non-invasive automatic Complior device. The vessel wall properties of the left common carotid artery were studied using multigate pulsed Doppler's system (Pie Medical Equipment BV Maastricht, The Netherlands). The frequency of transducer used was 7.5 MHz. With this non-invasive method, the end-diastolic diameter (d) and the systolic increase of vessel diameter (distension delta d) were measured using ECG trigger. From these data relative systolic increase of vessel diameter (delta d/d) and arterial wall distensibility coefficient (DC) were calculated. Simultaneously with the ultrasound measurements at the left common carotid artery carotid pulse waveforms are recorded using

  12. Cytotoxicity of algae extracts on normal and malignant cells.

    PubMed

    Bechelli, Jeremy; Coppage, Myra; Rosell, Karen; Liesveld, Jane

    2011-01-01

    Algae preparations are commonly used in alternative medicine. We examined the effects of algae extracts on normal hematopoietic cells and leukemia cells. Ethanol extracts were prepared of Dunaliella salina (Dun), Astaxanthin (Ast), Spirulina platensis (Spir), and Aphanizomenon flos-aquae (AFA). Cell viability effects were completed by Annexin staining. Ast and AFA inhibited HL-60 and MV-4-11 whereas Dun and Spir had no effect. Primary AML blasts demonstrated increased apoptosis in AFA. Primary CLL cells showed apoptosis at 24 hours after exposure to Dun, Ast, Spir, and AFA. High AFA concentrations decreased viability of normal marrow cells. Normal CD34+ viability was inhibited by Dun. Dun and AFA inhibited BFU-E, but all extracts inhibited CFU-GM. Cell-cycle analysis of AML cell lines showed G0/G1 arrest in the presence of AFA. These data suggest that algae extracts may inhibit AML cell lines and leukemia blasts, but they may also have potential inhibitory effects on normal hematopoiesis.

  13. Comparative survival study of glial cells and cells composing walls of blood vessels in crustacean ventral nerve cord after photodynamic treatment

    NASA Astrophysics Data System (ADS)

    Kolosov, Mikhail S.; Shubina, Elena

    2015-03-01

    Photodynamic therapy is a prospective treatment modality of brain cancers. It is of importance to have information about relative survival rate of different cell types in nerve tissue during photodynamic treatment. Particularly, for development of sparing strategy of the photodynamic therapy of brain tumors, which pursuits both total elimination of malignant cells, which are usually of glial origin, and, at the same time, preservation of normal blood circulation as well as normal glial cells in the brain. The aim of this work was to carry out comparative survival study of glial cells and cells composing walls of blood vessels after photodynamic treatment, using simple model object - ventral nerve cord of crustacean.

  14. Cell wall pH and auxin transport velocity

    NASA Technical Reports Server (NTRS)

    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.

  15. Enzymology and molecular biology of cell wall biosynthesis. Progress report

    SciTech Connect

    Ray, P.M.

    1993-03-20

    In order to be able to explore the control of cell wall polysaccharide synthesis at the molecular level, which inter alia might eventually lead to means for useful modification of plant biomass polysaccharide production, the immediate goals of this project are to identify polypeptides responsible for wall polysaccharide synthase activities and to obtain clones of the genes that encode them. We are concentrating on plasma membraneassociated (1,3)-{beta}-glucan synthase (glucan synthase-II or GS-II) and Golgi-associated (1,4)-{beta}-glucan synthase (glucan synthase-I or GS-I), of growing pea stem tissue. Our progress has been much more rapid with respect to GS-II than regarding GS-I.

  16. Normal modes of magnetic domain wall motion in a confined stripe domain lattice

    SciTech Connect

    Spreen, J.H.; Argyle, B.E.

    1982-06-01

    We report the observation of standing wave modes in an array of stripe domains confined by a pair of parallel cracks in a Gd, Ga:YIG film. These modes appear in the response spectrum of the confined lattice as shallow minima or maxima at frequencies lower than that of the usual domain wall resonance peak. A simple model, analogous to the forced response of a membrane clamped at the edges, fits the spatial patterns of wall motion observed at the frequencies of the maxima and minima. Experimental frequency-wave vector values, interpreted with guidance from this analogy, provide the first experimental dispersion curve for a stripe domain lattice. We compare this result with recent theoretical calculations. The experimental value of the uniform mode frequency is 41.5 +- 0.2 MHz, with a long wavelength group velocity of 330 +- 50 m/sec. A surprising conclusion from the observed extrema of the spatial patterns is that the damping of the waves is an order of magnitude less than expected from the damping of the uniform mode. The estimated decay length for a propagating wave is 400 ..mu...

  17. Monoclonal antibodies, carbohydrate-binding modules, and the detection of polysaccharides in plant cell walls.

    PubMed

    Hervé, Cécile; Marcus, Susan E; Knox, J Paul

    2011-01-01

    Plant cell walls are diverse composites of complex polysaccharides. Molecular probes such as monoclonal antibodies (MABs) and carbohydrate-binding modules (CBMs) are important tools to detect and dissect cell wall structures in plant materials. We provide an account of methods that can be used to detect cell wall polysaccharide structures (epitopes) in plant materials and also describe treatments that can provide information on the masking of sets of polysaccharides that may prevent detection. These masking -phenomena may indicate potential interactions between sets of cell wall polysaccharides, and methods to uncover them are an important aspect of cell wall immunocytochemistry.

  18. Comparative structure and biomechanics of plant primary and secondary cell walls.

    PubMed

    Cosgrove, Daniel J; Jarvis, Michael C

    2012-01-01

    Recent insights into the physical biology of plant cell walls are reviewed, summarizing the essential differences between primary and secondary cell walls and identifying crucial gaps in our knowledge of their structure and biomechanics. Unexpected parallels are identified between the mechanism of expansion of primary cell walls during growth and the mechanisms by which hydrated wood deforms under external tension. There is a particular need to revise current "cartoons" of plant cell walls to be more consistent with data from diverse approaches and to go beyond summarizing limited aspects of cell walls, serving instead as guides for future experiments and for the application of new techniques.

  19. Scattering properties of microalgae: the effect of cell size and cell wall

    NASA Astrophysics Data System (ADS)

    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.

  20. Identification of Two Saccharomyces cerevisiae Cell Wall Mannan Chemotypes

    PubMed Central

    Cawley, T. N.; Ballou, Clinton E.

    1972-01-01

    We have obtained evidence for two structurally and antigenically different Saccharomyces cerevisiae cell wall mannans. One, which occurs widely and is found in S. cerevisiae strain 238C, is already known to be a neutral mannan which yields mannose, mannobiose, mannotriose, and mannotetraose on acetolysis of the (1 → 6)-linked backbone. The other, which was found in S. cerevisiae brewer's strains, is a phosphomannan with a structure very similar to that of Kloeckera brevis mannan. S. cerevisiae (brewer's yeast strain) was agglutinated by antiserum prepared against Kloeckera brevis cells. The mannan, isolated from a proteolytic digest of the cell wall of the former, did not react with S. cerevisiae 238C antiserum, whereas it cross-reacted strongly with K. brevis antiserum. Controlled acetolysis cleaved the (1 → 6)-linkages in the polysaccharide backbone and released mannose, mannobiose, mannotriose, and mannotriose phosphate. Mild acid treatment of the phosphomannan hydrolyzed the phosphodiester linkage, yielding phosphomonoester mannan and mannose. The resulting phosphomonoester mannan reacted with antiserum prepared against K. brevis possessing monoester phosphate groups on the cell surface. α-d-Mannose-1-phosphate completely inhibited the precipitin reaction between brewer's yeast mannan and the homologous antiserum. Flocculent and nonflocculent strains of this yeast were shown to have similar structural and immunological properties. PMID:4559821

  1. The wall traction induced by flowing red blood cells in model microvessels and its potential mechanotransduction

    NASA Astrophysics Data System (ADS)

    Freund, Jonathan; Vermot, Julien

    2013-11-01

    There is evidence in early embryonic development, even well before advective oxygen transport is important, that the presence of red bloods cells per se trigger essential steps of normal vascular development. For example, showed that sequestration of blood cells early in the development of a mouse, such that the hematocrit is reduced, suppresses normal vascular network development. Vascular development also provides a model for remodeling and angiogenesis. We consider the transient stresses associated with blood cells flowing in model microvessels of comparable diameter to those at early stages of development (6 μm to 12 μm). A detailed simulation tool is used to show that passing blood cells present a significant fluctuating traction signature on the vessel wall, well above the mean stresses. This is particularly pronounced for slow flows (<= 50 μm/s) or small diameters (<= 7 μm), for which root-mean-square wall traction fluctuations can exceed their mean. These events potentially present mechanotranduction triggers that direct development or remodeling. Attenuation of such fluctuating tractions by a viscoelastic endothelial glycocalyx layer is also considered. NSF supported.

  2. Cell culture for three-dimensional modeling in rotating-wall vessels: an application of simulated microgravity

    NASA Technical Reports Server (NTRS)

    Schwarz, R. P.; Goodwin, T. J.; Wolf, D. A.

    1992-01-01

    High-density, three-dimensional cell cultures are difficult to grow in vitro. The rotating-wall vessel (RWV) described here has cultured BHK-21 cells to a density of 1.1 X 10(7) cells/ml. Cells on microcarriers were observed to grow with enhanced bridging in this batch culture system. The RWV is a horizontally rotated tissue culture vessel with silicon membrane oxygenation. This design results in a low-turbulence, low-shear cell culture environment with abundant oxygenation. The RWV has the potential to culture a wide variety of normal and neoplastic cells.

  3. Kinesin-4 Functions in Vesicular Transport on Cortical Microtubules and Regulates Cell Wall Mechanics during Cell Elongation in Plants.

    PubMed

    Kong, Zhaosheng; Ioki, Motohide; Braybrook, Siobhan; Li, Shundai; Ye, Zheng-Hua; Julie Lee, Yuh-Ru; Hotta, Takashi; Chang, Anny; Tian, Juan; Wang, Guangda; Liu, Bo

    2015-07-01

    In plants, anisotropic cell expansion depends on cortical microtubules that serve as tracks along which macromolecules and vesicles are transported by the motor kinesins of unknown identities. We used cotton (Gossypium hirsutum) fibers that underwent robust elongation to discover kinesins that are involved in cell elongation and found Gh KINESIN-4A expressed abundantly. The motor was detected by immunofluorescence on vesicle-like structures that were associated with cortical microtubules. In Arabidopsis thaliana, the orthologous motor At KINESIN-4A/FRA1, previously implicated in cellulose deposition during secondary growth in fiber cells, was examined by live-cell imaging in cells expressing the fluorescently tagged functional protein. The motor decorated vesicle-like particles that exhibit a linear movement along cortical microtubules with an average velocity of 0.89 μm/min, which was significantly different from those linked to cellulose biosynthesis. We also discovered that At KINESIN-4A/FRA1 and the related At KINESIN-4C play redundant roles in cell wall mechanics, cell elongation, and the axial growth of various vegetative and reproductive organs, as the loss of At KINESIN-4C greatly enhanced the defects caused by a null mutation at the KINESIN-4A/FRA1 locus. The double mutant displayed a lack of cell wall softening at normal stages of rapid cell elongation. Furthermore, enhanced deposition of arabinose-containing carbohydrate was detected in the kinesin-4 mutants. Our findings established a connection between the Kinesin-4-based transport of cargoes containing non-cellulosic components along cortical microtubules and cell wall mechanics and cell elongation in flowering plants.

  4. Tubulin perturbation leads to unexpected cell wall modifications and affects stomatal behaviour in Populus

    SciTech Connect

    Swamy, Prashant S.; Hu, Hao; Pattathil, Sivakumar; Maloney, Victoria J.; Xiao, Hui; Xue, Liang -Jiao; Chung, Jeng -Der; Johnson, Virgil E.; Zhu, Yingying; Peter, Gary F.; Hahn, Michael G.; Mansfield, Shawn D.; Harding, Scott A.; Tsai, Chung -Jui

    2015-08-05

    Cortical microtubules are integral to plant morphogenesis, cell wall synthesis, and stomatal behaviour, presumably by governing cellulose microfibril orientation. Genetic manipulation of tubulins often leads to abnormal plant development, making it difficult to probe additional roles of cortical microtubules in cell wall biogenesis. Here, it is shown that expressing post-translational C-terminal modification mimics of α-tubulin altered cell wall characteristics and guard cell dynamics in transgenic Populus tremula x alba that otherwise appear normal. 35S promoter-driven transgene expression was high in leaves but unusually low in xylem, suggesting high levels of tubulin transgene expression were not tolerated in wood-forming tissues during regeneration of transformants. Cellulose, hemicellulose, and lignin contents were unaffected in transgenic wood, but expression of cell wall-modifying enzymes, and extractability of lignin-bound pectin and xylan polysaccharides were increased in developing xylem. The results suggest that pectin and xylan polysaccharides deposited early during cell wall biogenesis are more sensitive to subtle tubulin perturbation than cellulose and matrix polysaccharides deposited later. Tubulin perturbation also affected guard cell behaviour, delaying drought-induced stomatal closure as well as light-induced stomatal opening in leaves. Pectins have been shown to confer cell wall flexibility critical for reversible stomatal movement, and results presented here are consistent with microtubule involvement in this process. In conclusion, taken together, the data show the value of growth-compatible tubulin perturbations for discerning microtubule functions, and add to the growing body of evidence for microtubule involvement in non-cellulosic polysaccharide assembly during cell wall biogenesis.

  5. Stem cells in normal mammary gland and breast cancer.

    PubMed

    Luo, Jie; Yin, Xin; Ma, Tao; Lu, Jun

    2010-04-01

    The mammary gland is a structurally dynamic organ that undergoes dramatic alterations with age, menstrual cycle, and reproductive status. Mammary gland stem cells, the minor cell population within the mature organ, are thought to have multiple functions in regulating mammary gland development, tissue maintenance, major growth, and structural remodeling. In addition, accumulative evidence suggests that breast cancers are initiated and maintained by a subpopulation of tumor cells with stem cell features (called cancer stem cells). A variety of methods have been developed to identify and characterize mammary stem cells, and several signal transduction pathways have been identified to be essential for the self-renewal and differentiation of mammary gland stem cells. Understanding the origin of breast cancer stem cells, their relationship to breast cancer development, and the differences between normal and cancer stem cells may lead to novel approaches to breast cancer diagnosis, prevention, and treatment.

  6. Isolation and identification of normal killer cells from Syrian hamsters

    SciTech Connect

    Matveeva, V.A.; Klyuchareva, T.E.

    1986-09-01

    This paper gives data on isolation of normal killer cells from the blood and various tissues of Syrian hamsters in a Percoll density gradient and their identification on the basis of morphologic criteria and cytotoxic activity (CTA). CTA of the isolated cells was studied in the cytotoxic test with target cells of a human MOLT-4 thymoma cell labeled with /sup 51/Cr. Isolation of large granular lymphocytes from blood, spleen, and bone marrow of Syrian hamsters in Percoll density gradient is shown in the results of five experiments used for cells of each type.

  7. Normalization of cell responses in cat striate cortex

    NASA Technical Reports Server (NTRS)

    Heeger, D. J.

    1992-01-01

    Simple cells in the striate cortex have been depicted as half-wave-rectified linear operators. Complex cells have been depicted as energy mechanisms, constructed from the squared sum of the outputs of quadrature pairs of linear operators. However, the linear/energy model falls short of a complete explanation of striate cell responses. In this paper, a modified version of the linear/energy model is presented in which striate cells mutually inhibit one another, effectively normalizing their responses with respect to stimulus contrast. This paper reviews experimental measurements of striate cell responses, and shows that the new model explains a significantly larger body of physiological data.

  8. Single-walled carbon nanohorn (SWNH) aggregates inhibited proliferation of human liver cell lines and promoted apoptosis, especially for hepatoma cell lines

    PubMed Central

    Zhang, Jinqian; Sun, Qiang; Bo, Jian; Huang, Rui; Zhang, Mengran; Xia, Zhenglin; Ju, Lili; Xiang, Guoan

    2014-01-01

    Single-walled carbon nanohorns (SWNHs) may be useful as carriers for anticancer drugs due to their particular structure. However, the interactions between the material itself and cancerous or normal cells have seldom been studied. To address this problem, the effects of raw SWNH material on the biological functions of human liver cell lines were studied. Our results showed that unmodified SWNHs inhibited mitotic entry, growth, and proliferation of human liver cell lines and promoted their apoptosis, especially in hepatoma cell lines. Individual spherical SWNH particles were found inside the nuclei of human hepatoma HepG2 cells and the lysosomes of normal human liver L02 cells, implying that SWNH particles could penetrate into human liver cells_and the different interacted mechanisms on human normal cell lines compared to hepatoma cell lines. Further research on the mechanisms and application in treatment of hepatocellular carcinoma with SWNHs is needed. PMID:24523586

  9. Preparing normal tissue cells for space flight experiments.

    PubMed

    Koch, Claudia; Kohn, Florian P M; Bauer, Johann

    2016-01-01

    Deterioration of health is a problem in modern space flight business. In order to develop countermeasures, research has been done on human bodies and also on single cells. Relevant experiments on human cells in vitro are feasible when microgravity is simulated by devices such as the Random Positioning Machine or generated for a short time during parabolic flights. However, they become difficult in regard to performance and interpretation when long-term experiments are designed that need a prolonged stay on the International Space Station (ISS). One huge problem is the transport of living cells from a laboratory on Earth to the ISS. For this reason, mainly rapidly growing, rather robust human cells such as cancer cells, embryonic cells, or progenitor cells have been investigated on the ISS up to now. Moreover, better knowledge on the behavior of normal mature cells, which mimic the in vivo situation, is strongly desirable. One solution to the problem could be the use of redifferentiable cells, which grow rapidly and behave like cancer cells in plain medium, but are reprogrammed to normal cells when substances like retinoic acid are added. A list of cells capable of redifferentiation is provided, together with names of suitable drugs, in this review.

  10. The Neurospora crassa CPS-1 polysaccharide synthase functions in cell wall biosynthesis.

    PubMed

    Fu, Ci; Sokolow, Eleanor; Rupert, Christopher B; Free, Stephen J

    2014-08-01

    The Neurospora crassa cps-1 gene encodes a polysaccharide synthase with homology to the Cryptococcus neoformans hyaluronic acid synthase Cps1p. Homologs of the cps-1 gene are found in the genomes of many fungi. Loss of CPS-1 results in a cell wall defect that affects all stages of the N. crassa life cycle, including vegetative growth, protoperithecia (female mating structure) development, and conidia (asexual spore) development. The cell wall of cps-1 deletion mutants is sensitive to cell wall perturbation reagents. Our results demonstrate that CPS-1 is required for the incorporation of cell wall proteins into the cell wall and plays a critical role in cell wall biogenesis. We found that the N. crassa cell wall is devoid of hyaluronic acid, and conclude that the polysaccharide produced by the CPS-1 is not hyaluronic acid.

  11. Soluble Signals from Cells Identified at the Cell Wall Establish a Developmental Pathway in Carrot.

    PubMed Central

    McCabe, P. F.; Valentine, T. A.; Forsberg, L. S.; Pennell, R. I.

    1997-01-01

    Cells in a plant differentiate according to their positions and use cell-cell communication to assess these positions. Similarly, single cells in suspension cultures can develop into somatic embryos, and cell-cell communication is thought to control this process. The monoclonal antibody JIM8 labels an epitope on cells in specific positions in plants. JIM8 also labels certain cells in carrot embryogenic suspension cultures. We have used JIM8 and secondary antibodies coupled to paramagnetic beads to label and immunomagnetically sort single cells in a carrot embryogenic suspension culture into pure populations. Cells in the JIM8(+) population develop into somatic embryos, whereas cells in the JIM8(-) population do not form somatic embryos. However, certain cells in JIM8(+) cultures (state B cells) undergo asymmetric divisions, resulting in daughter cells (state C cells) that do not label with JIM8 and that sort to JIM8(-) cultures. State C cells are competent to form somatic embryos, and we show here that a conditioned growth medium from a culture of JIM8(+) cells allows state C cells in a JIM8(-) culture to go on and develop into somatic embryos. JIM8 labels cells in suspension cultures at the cell wall. Therefore, a cell with a role in cell-cell communication and early cell fate selection can be identified by an epitope in its cell wall. PMID:12237357

  12. The CWB2 Cell Wall-Anchoring Module Is Revealed by the Crystal Structures of the Clostridium difficile Cell Wall Proteins Cwp8 and Cwp6.

    PubMed

    Usenik, Aleksandra; Renko, Miha; Mihelič, Marko; Lindič, Nataša; Borišek, Jure; Perdih, Andrej; Pretnar, Gregor; Müller, Uwe; Turk, Dušan

    2017-03-07

    Bacterial cell wall proteins play crucial roles in cell survival, growth, and environmental interactions. In Gram-positive bacteria, cell wall proteins include several types that are non-covalently attached via cell wall binding domains. Of the two conserved surface-layer (S-layer)-anchoring modules composed of three tandem SLH or CWB2 domains, the latter have so far eluded structural insight. The crystal structures of Cwp8 and Cwp6 reveal multi-domain proteins, each containing an embedded CWB2 module. It consists of a triangular trimer of Rossmann-fold CWB2 domains, a feature common to 29 cell wall proteins in Clostridium difficile 630. The structural basis of the intact module fold necessary for its binding to the cell wall is revealed. A comparison with previously reported atomic force microscopy data of S-layers suggests that C. difficile S-layers are complex oligomeric structures, likely composed of several different proteins.

  13. Mechanical properties of normal versus cancerous breast cells

    PubMed Central

    Smelser, Amanda M.; Macosko, Jed C.; O’Dell, Adam P.; Smyre, Scott; Bonin, Keith

    2016-01-01

    A cell’s mechanical properties are important in determining its adhesion, migration, and response to the mechanical properties of its microenvironment and may help explain behavioral differences between normal and cancerous cells. Using fluorescently labeled peroxisomes as microrheological probes, the interior mechanical properties of normal breast cells were compared to a metastatic breast cell line, MDA-MB-231. To estimate the mechanical properties of cell cytoplasms from the motions of their peroxisomes, it was necessary to reduce the contribution of active cytoskeletal motions to peroxisome motion. This was done by treating the cells with blebbistatin, to inhibit myosin II, or with sodium azide and 2-deoxy-D-glucose, to reduce intracellular ATP. Using either treatment, the peroxisomes exhibited normal diffusion or subdiffusion, and their mean squared displacements (MSDs) showed that the MDA-MB-231 cells were significantly softer than normal cells. For these two cell types, peroxisome MSDs in treated and untreated cells converged at high frequencies, indicating that cytoskeletal structure was not altered by the drug treatment. The MSDs from ATP-depleted cells were analyzed by the generalized Stokes–Einstein relation to estimate the interior viscoelastic modulus G* and its components, the elastic shear modulus G′ and viscous shear modulus G″, at angular frequencies between 0.126 and 628rad/s. These moduli are the material coefficients that enter into stress–strain relations and relaxation times in quantitative mechanical models such as the poroelastic model of the interior regions of cancerous and non-cancerous cells. PMID:25929519

  14. Transient sedimentation in a cell with top and bottom walls

    NASA Astrophysics Data System (ADS)

    Dance, Sarah; Maxey, Martin

    2002-11-01

    Wall boundary conditions may play a role in the screening of particle velocity fluctuations in Stokes suspensions. Using a Force-Coupling Method (Maxey and Patel, Int. J. Multiphase Flow 27 (2001)) we simulate transient sedimentation. The numerical scheme is a mixed Fourier-spectral element method, based on the Uzawa algorithm for Stokes flows. The sedimentation cell has top and bottom wall boundaries and periodic boundaries in the horizontal. These boundaries are chosen both for computational convenience, and to determine the relative importance of bottom and side walls in screening the velocity fluctuations. We consider several different box sizes, in an attempt to elucidate the connection between particle velocity fluctuation levels and box width. We quantify the evolution of particle mean velocities and fluctuations as well as the particle microstructure. In each case we observe an initial growth, followed by a decay in both the mean particle velocity and fluctuations. We also observe that a stable stratification develops. We suggest that the stratification is important in the evolution of the bulk mean velocity. We propose a mechanism involving particle cluster dynamics to explain the behaviour of the velocity fluctuations.

  15. Forage digestibility: the intersection of cell wall lignification and plant tissue anatomy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cellulose and the other polysaccharides present in forage cell walls can be completely degraded by the rumen microflora but only when these polysaccharides have been isolated from the wall and all matrix structures eliminated. Understanding how cell wall component interactions limit microbial degrad...

  16. Dendrites of rod bipolar cells sprout in normal aging retina.

    PubMed

    Liets, Lauren C; Eliasieh, Kasra; van der List, Deborah A; Chalupa, Leo M

    2006-08-08

    The aging nervous system is known to manifest a variety of degenerative and regressive events. Here we report the unexpected growth of dendrites in the retinas of normal old mice. The dendrites of many rod bipolar cells in aging mice were observed to extend well beyond their normal strata within the outer plexiform layer to innervate the outer nuclear layer where they appeared to form contacts with the spherules of rod photoreceptors. Such dendritic sprouting increased with age and was evident at all retinal eccentricities. These results provide evidence of retinal plasticity associated with normal aging.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. A selective inhibitor of cell proliferation from normal serum.

    PubMed Central

    Harrington, W N; Godman, G C

    1980-01-01

    A factor in normal serum that selectively and reversibly inhibits proliferation of cells in culture has been enriched 160-fold from calf serum by sequential ammonium sulfate precipitation, gel filtration, and lectin-affinity chromatography. DNA synthesis of normal (but not transformed) rat hepatocytes, human lymphoblast lines, and mitogen-stimulated murine spleen cells is inhibited by greater than 90%, and Vero, murine myeloma, MELC, and a human colon carcinoma cell line to a lesser extent. Growth of other cell lines tested was not affected. Responsive cells are arrested apparently in G1 by this inhibitor, the effect of which is maximal by 24 hr and is spontaneously reversible thereafter unless it is renewed. The active fraction is a protein that migrates with the alpha 2-globulins; it is not a lipoprotein, and it is of high apparent molecular weight. PMID:6928635

  19. Changes in cell wall polysaccharide composition, gene transcription and alternative splicing in germinating barley embryos.

    PubMed

    Zhang, Qisen; Zhang, Xiaoqi; Pettolino, Filomena; Zhou, Gaofeng; Li, Chengdao

    2016-02-01

    Barley (Hordeum vulgare L.) seed germination initiates many important biological processes such as DNA, membrane and mitochondrial repairs. However, little is known on cell wall modifications in germinating embryos. We have investigated cell wall polysaccharide composition change, gene transcription and alternative splicing events in four barley varieties at 24h and 48 h germination. Cell wall components in germinating barley embryos changed rapidly, with increases in cellulose and (1,3)(1,4)-β-D-glucan (20-100%) within 24h, but decreases in heteroxylan and arabinan (3-50%). There were also significant changes in the levels of type I arabinogalactans and heteromannans. Alternative splicing played very important roles in cell wall modifications. At least 22 cell wall transcripts were detected to undergo either alternative 3' splicing, alternative 5' splicing or intron retention type of alternative splicing. These genes coded enzymes catalyzing synthesis and degradation of cellulose, heteroxylan, (1,3)(1,4)-β-D-glucan and other cell wall polymers. Furthermore, transcriptional regulation also played very important roles in cell wall modifications. Transcript levels of primary wall cellulase synthase, heteroxylan synthesizing and nucleotide sugar inter-conversion genes were very high in germinating embryos. At least 50 cell wall genes changed transcript levels significantly. Expression patterns of many cell wall genes coincided with changes in polysaccharide composition. Our data showed that cell wall polysaccharide metabolism was very active in germinating barley embryos, which was regulated at both transcriptional and post-transcriptional levels.

  20. A radioimmunoassay for lignin in plant cell walls

    SciTech Connect

    Dawley, R.M.

    1989-01-01

    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 {beta}-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 {eta}g/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. {sup 125}I 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 NaClO{sub 2} delignification. The RIA was found to be less sensitive than expected, so several avenues for improving the method are discussed.

  1. Lignification in poplar tension wood lignified cell wall layers.

    PubMed

    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.

  2. The mechanisms of plant cell wall deconstruction during enzymatic hydrolysis.

    PubMed

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

    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, particularly when it comes to up-scaling of processes based on insoluble feed stocks.

  3. Amino acids of the cell wall of Nocardia rubra.

    PubMed

    Beaman, B L; Kim, K S; Salton, M R; Barksdale, L

    1971-11-01

    Two classes of preparations of cell walls of Nocardia rubra strain 721-A, digested by trypsin and pepsin with or without subsequent extraction in alkaline ethanol, when examined by electron microscope and analyzed quantitatively for amino acid content differ in ultrastructure and constituent amino acids. Evidence suggests that the lipid-associated amino acids (as peptide or protein) occupy a location superficial to the basal peptido-glycan layer of this nocardia. Their removal is associated with the loss of a characteristic pattern of the outer envelope.

  4. Theoretical investigation on breaking plant cell wall by laser

    NASA Astrophysics Data System (ADS)

    Chen, Liang-cai; Wang, Jin-ji; Ma, Peng; Zuo, Du-luo; Wang, Xin-bing; Cheng, Zu-hai

    2011-11-01

    The experiment collected some spinach leaves which were irradiated by pulsed CO2 laser with energy 5.6J, 8.0J and 9.5J respectively. Each of them was soaked in three kinds of solvents (water, ethanol, the mixture of ethanol and petroleum ether) respectively. The experiment shows that the ethanol solution which contains the irradiated leaves turn dark green than the ethanol solution which contains the intact leaves and the color of solution with the leaves irradiated by CO2 laser with 9.5J changes the most significantly. Further, selective excitation on the molecular level of the cell wall were used to explain the phenomenon.

  5. Theoretical investigation on breaking plant cell wall by laser

    NASA Astrophysics Data System (ADS)

    Chen, Liang-cai; Wang, Jin-ji; Ma, Peng; Zuo, Du-luo; Wang, Xin-bing; Cheng, Zu-hai

    2012-03-01

    The experiment collected some spinach leaves which were irradiated by pulsed CO2 laser with energy 5.6J, 8.0J and 9.5J respectively. Each of them was soaked in three kinds of solvents (water, ethanol, the mixture of ethanol and petroleum ether) respectively. The experiment shows that the ethanol solution which contains the irradiated leaves turn dark green than the ethanol solution which contains the intact leaves and the color of solution with the leaves irradiated by CO2 laser with 9.5J changes the most significantly. Further, selective excitation on the molecular level of the cell wall were used to explain the phenomenon.

  6. Structure, cell wall elasticity and polysaccharide properties of living yeast cells, as probed by AFM

    NASA Astrophysics Data System (ADS)

    Alsteens, David; Dupres, Vincent; McEvoy, Kevin; Wildling, Linda; Gruber, Hermann J.; Dufrêne, Yves F.

    2008-09-01

    Although the chemical composition of yeast cell walls is known, the organization, assembly, and interactions of the various macromolecules remain poorly understood. Here, we used in situ atomic force microscopy (AFM) in three different modes to probe the ultrastructure, cell wall elasticity and polymer properties of two brewing yeast strains, i.e. Saccharomyces carlsbergensis and S. cerevisiae. Topographic images of the two strains revealed smooth and homogeneous cell surfaces, and the presence of circular bud scars on dividing cells. Nanomechanical measurements demonstrated that the cell wall elasticity of S. carlsbergensis is homogeneous. By contrast, the bud scar of S. cerevisiae was found to be stiffer than the cell wall, presumably due to the accumulation of chitin. Notably, single molecule force spectroscopy with lectin-modified tips revealed major differences in polysaccharide properties of the two strains. Polysaccharides were clearly more extended on S. cerevisiae, suggesting that not only oligosaccharides, but also polypeptide chains of the mannoproteins were stretched. Consistent with earlier cell surface analyses, these findings may explain the very different aggregation properties of the two organisms. This study demonstrates the power of using multiple complementary AFM modalities for probing the organization and interactions of the various macromolecules of microbial cell walls.

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

    PubMed Central

    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 previously favored xyloglucan. PMID:22353862

  8. Heterogeneity in the chemistry, structure and function of plant cell walls.

    PubMed

    Burton, Rachel A; Gidley, Michael J; Fincher, Geoffrey B

    2010-10-01

    Higher plants resist the forces of gravity and powerful lateral forces through the cumulative strength of the walls that surround individual cells. These walls consist mainly of cellulose, noncellulosic polysaccharides and lignin, in proportions that depend upon the specific functions of the cell and its stage of development. Spatially and temporally controlled heterogeneity in the physicochemical properties of wall polysaccharides is observed at the tissue and individual cell levels, and emerging in situ technologies are providing evidence that this heterogeneity also occurs across a single cell wall. We consider the origins of cell wall heterogeneity and identify contributing factors that are inherent in the molecular mechanisms of polysaccharide biosynthesis and are crucial for the changing biological functions of the wall during growth and development. We propose several key questions to be addressed in cell wall biology, together with an alternative two-phase model for the assembly of noncellulosic polysaccharides in plants.

  9. Cancer stem cells from a rare form of glioblastoma multiforme involving the neurogenic ventricular wall

    PubMed Central

    2012-01-01

    Background The cancer stem cell (CSC) hypothesis posits that deregulated neural stem cells (NSCs) form the basis of brain tumors such as glioblastoma multiforme (GBM). GBM, however, usually forms in the cerebral white matter while normal NSCs reside in subventricular and hippocampal regions. We attempted to characterize CSCs from a rare form of glioblastoma multiforme involving the neurogenic ventricular wall. Methods We described isolating CSCs from a GBM involving the lateral ventricles and characterized these cells with in vitro molecular biomarker profiling, cellular behavior, ex vivo and in vivo techniques. Results The patient’s MRI revealed a heterogeneous mass with associated edema, involving the left subventricular zone. Histological examination of the tumor established it as being a high-grade glial neoplasm, characterized by polygonal and fusiform cells with marked nuclear atypia, amphophilic cytoplasm, prominent nucleoli, frequent mitotic figures, irregular zones of necrosis and vascular hyperplasia. Recurrence of the tumor occurred shortly after the surgical resection. CD133-positive cells, isolated from the tumor, expressed stem cell markers including nestin, CD133, Ki67, Sox2, EFNB1, EFNB2, EFNB3, Cav-1, Musashi, Nucleostemin, Notch 2, Notch 4, and Pax6. Biomarkers expressed in differentiated cells included Cathepsin L, Cathepsin B, Mucin18, Mucin24, c-Myc, NSE, and TIMP1. Expression of unique cancer-related transcripts in these CD133-positive cells, such as caveolin-1 and −2, do not appear to have been previously reported in the literature. Ex vivo organotypic brain slice co-culture showed that the CD133+ cells behaved like tumor cells. The CD133-positive cells also induced tumor formation when they were stereotactically transplanted into the brains of the immune-deficient NOD/SCID mice. Conclusions This brain tumor involving the neurogenic lateral ventricular wall was comprised of tumor-forming, CD133-positive cancer stem cells, which are likely

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

    PubMed Central

    Deguchi, Shigeru; Tsujii, Kaoru; Horikoshi, Koki

    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 temperatures well over 200 °C. The results show very hot and compressed water is needed to make mushrooms mushy. PMID:26148792

  11. 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.

    PubMed

    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.

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

    PubMed

    Domozych, David S

    2014-11-18

    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 raised against polymers of higher plant cell walls. Immunofluorescence-based labeling is easily performed using live cells that subsequently can be returned to culture and monitored. This feature allows for rapid assessment of wall expansion rates and identification of multiple polymer types in the wall microarchitecture during the cell cycle. Cryofixation by means of spray freezing provides excellent transmission electron microscopy imaging of the cell, including its elaborate endomembrane and cytoskeletal systems, both integral to cell wall development. Penium's fast growth rate allows for convenient microarray screening of various agents that alter wall biosynthesis and metabolism. Finally, recent successful development of transformed cell lines has allowed for non-invasive imaging of proteins in cells and for RNAi reverse genetics that can be used for cell wall biosynthesis studies.

  13. Daughter cell separation is controlled by cytokinetic ring-activated cell wall hydrolysis.

    PubMed

    Uehara, Tsuyoshi; Parzych, Katherine R; Dinh, Thuy; Bernhardt, Thomas G

    2010-04-21

    During bacterial cytokinesis, hydrolytic enzymes are used to split wall material shared by adjacent daughter cells to promote their separation. Precise control over these enzymes is critical to prevent breaches in wall integrity that can cause cell lysis. How these potentially lethal hydrolases are regulated has remained unknown. Here, we investigate the regulation of cell wall turnover at the Escherichia coli division site. We show that two components of the division machinery with LytM domains (EnvC and NlpD) are direct regulators of the cell wall hydrolases (amidases) responsible for cell separation (AmiA, AmiB and AmiC). Using in vitro cell wall cleavage assays, we show that EnvC activates AmiA and AmiB, whereas NlpD activates AmiC. Consistent with these findings, we show that an unregulated EnvC mutant requires functional AmiA or AmiB but not AmiC to induce cell lysis, and that the loss of NlpD phenocopies an AmiC(-) defect. Overall, our results suggest that cellular amidase activity is regulated spatially and temporally by coupling their activation to the assembly of the cytokinetic ring.

  14. Daughter cell separation is controlled by cytokinetic ring-activated cell wall hydrolysis

    PubMed Central

    Uehara, Tsuyoshi; Parzych, Katherine R; Dinh, Thuy; Bernhardt, Thomas G

    2010-01-01

    During bacterial cytokinesis, hydrolytic enzymes are used to split wall material shared by adjacent daughter cells to promote their separation. Precise control over these enzymes is critical to prevent breaches in wall integrity that can cause cell lysis. How these potentially lethal hydrolases are regulated has remained unknown. Here, we investigate the regulation of cell wall turnover at the Escherichia coli division site. We show that two components of the division machinery with LytM domains (EnvC and NlpD) are direct regulators of the cell wall hydrolases (amidases) responsible for cell separation (AmiA, AmiB and AmiC). Using in vitro cell wall cleavage assays, we show that EnvC activates AmiA and AmiB, whereas NlpD activates AmiC. Consistent with these findings, we show that an unregulated EnvC mutant requires functional AmiA or AmiB but not AmiC to induce cell lysis, and that the loss of NlpD phenocopies an AmiC− defect. Overall, our results suggest that cellular amidase activity is regulated spatially and temporally by coupling their activation to the assembly of the cytokinetic ring. PMID:20300061

  15. Anabolic androgens affect the competitive interactions in cell migration and adhesion between normal mouse urothelial cells and urothelial carcinoma cells.

    PubMed

    Huang, Chi-Ping; Hsieh, Teng-Fu; Chen, Chi-Cheng; Hung, Xiao-Fan; Yu, Ai-Lin; Chang, Chawnshang; Shyr, Chih-Rong

    2014-09-26

    The urothelium is constantly rebuilt by normal urothelial cells to regenerate damaged tissues caused by stimuli in urine. However, the urothelial carcinoma cells expand the territory by aberrant growth of tumor cells, which migrate and occupy the damaged tissues to spread outside and disrupt the normal cells and organized tissues and form a tumor. Therefore, the interaction between normal urothelial cells and urothelial carcinoma cells affect the initiation and progression of urothelial tumors if normal urothelial cells fail to migrate and adhere to the damages sites to regenerate the tissues. Here, comparing normal murine urothelial cells with murine urothelial carcinoma cells (MBT-2), we found that normal cells had less migration ability than carcinoma cells. And in our co-culture system we found that carcinoma cells had propensity migrating toward normal urothelial cells and carcinoma cells had more advantages to adhere than normal cells. To reverse this condition, we used anabolic androgen, dihyrotestosterone (DHT) to treat normal cells and found that DHT treatment increased the migration ability of normal urothelial cells toward carcinoma cells and the adhesion capacity in competition with carcinoma cells. This study provides the base of a novel therapeutic approach by using anabolic hormone-enforced normal urothelial cells to regenerate the damage urothelium and defend against the occupancy of carcinoma cells to thwart cancer development and recurrence.

  16. Alloantigen presenting function of normal human CD34+ hematopoietic cells.

    PubMed

    Rondelli, D; Andrews, R G; Hansen, J A; Ryncarz, R; Faerber, M A; Anasetti, C

    1996-10-01

    The identification of the CD34 molecule, expressed almost exclusively on human hematopoietic stem cells and committed progenitors, and the development of CD34-specific monoclonal antibodies have made procurement of relatively pure populations of CD34+ marrow cells for autologous transplantation feasible. Characterization of the immunogenicity of CD34+ marrow cells may facilitate the design of successful strategies to use these cells for allogeneic transplantation. CD34+ marrow cells from normal volunteers were enriched to greater than 98% purity by immunoaffinity chromatography on column followed by fluorescence-activated cell sorting. Purified CD34+ cells were tested for expression of HLA-DR and other accessory molecules, and function in hematopoietic colony growth and mixed leukocyte culture (MLC) assays. Greater than 95% CD34+ cells were positive for HLA-DR and 74% +/- 10% were highly positive for CD18, the common beta-chain of a leukointegrin family. CD34+/CD18- cells were small, agranular lymphocytes which contained the majority of precursors for colony-forming cells detected in long-term cultures. They produced almost no stimulation of purified T cells from HLA-DR-incompatible individuals in bulk MLC or in limiting dilution assay. In contrast, CD34+/CD18+ cells were large, were enriched for cells forming mixed colonies in short- but not long-term assays, and were capable of stimulating allogeneic T cells. CD86, a natural ligand for the T-cell activation molecule CD28, was coexpressed with CD18 in 6% +/- 3% of CD34+ cells. CD34+/CD86+ cells, but not CD34+/CD86- cells, exhibited strong alloantigen presenting function. Thus, pluripotent hematopoietic activity and alloantigen presenting function are attributes of distinct subsets of CD34+ marrow cells. CD34+/CD18- or CD34+/CD86- cells may be more effective than either the whole CD34+ population or unseparated marrow in engrafting allogeneic recipients and may also facilitate induction of tolerance.

  17. The Impact of Microfibril Orientations on the Biomechanics of Plant Cell Walls and Tissues.

    PubMed

    Ptashnyk, Mariya; Seguin, Brian

    2016-11-01

    The microscopic structure and anisotropy of plant cell walls greatly influence the mechanical properties, morphogenesis, and growth of plant cells and tissues. The microscopic structure and properties of cell walls are determined by the orientation and mechanical properties of the cellulose microfibrils and the mechanical properties of the cell wall matrix. Viewing the shape of a plant cell as a square prism with the axis aligning with the primary direction of expansion and growth, the orientation of the microfibrils within the side walls, i.e. the parts of the cell walls on the sides of the cells, is known. However, not much is known about their orientation at the upper and lower ends of the cell. Here we investigate the impact of the orientation of cellulose microfibrils within the upper and lower parts of the plant cell walls by solving the equations of linear elasticity numerically. Three different scenarios for the orientation of the microfibrils are considered. We also distinguish between the microstructure in the side walls given by microfibrils perpendicular to the main direction of the expansion and the situation where the microfibrils are rotated through the wall thickness. The macroscopic elastic properties of the cell wall are obtained using homogenization theory from the microscopic description of the elastic properties of the cell wall microfibrils and wall matrix. It is found that the orientation of the microfibrils in the upper and lower parts of the cell walls affects the expansion of the cell in the lateral directions and is particularly important in the case of forces acting on plant cell walls and tissues.

  18. Properties of lead deposits in cell walls of radish (Raphanus sativus) roots.

    PubMed

    Inoue, Hiroshi; Fukuoka, Daisuke; Tatai, Yuri; Kamachi, Hiroyuki; Hayatsu, Manabu; Ono, Manami; Suzuki, Suechika

    2013-01-01

    Various mechanisms are involved in detoxification of heavy metals such as lead (Pb) in plant cells. Most of the Pb taken up by plants accumulates in their roots. However, the detailed properties of Pb complexes in roots remain unclear. We have investigated the properties of Pb deposits in root cell walls of radish (Raphanus sativus L.) seedlings grown on glass beads bed containing Pb pellets, which are the source of Pb-contamination in shooting range soils. Pb deposits were tightly bound to cell walls. Cell wall fragments containing about 50,000 ppm Pb were prepared from the roots. After extracting Pb from the cell wall fragments using HCl, Pb ions were recombined with the Pb-extracted cell wall fragments in a solution containing Pb acetate. When the cell wall fragments were treated with pectinase (E.C. 3.2.1.15) and were chemically modified with 1-ethyl-3-dimethylamino-propylcarboimide, the Pb-rebinding ability of the treated cell wall fragments decreased. When acid-treated cell wall fragments were incubated in a solution containing Pb(2+) and excess amounts of a chelating agent, Pb recombined with the cell wall fragments were measured to estimate the affinity between Pb(2+) and the cell wall fragments. Our data show that Pb(2+) binds to carboxyl groups of cell walls. The source of the carboxyl groups is suggested to be pectic compounds. A stability constant of the Pb-cell wall complex was estimated to be about 10(8). The role of root cell walls in the mechanism underlying heavy metal tolerance was discussed.

  19. Thyroid stem cells: lessons from normal development and thyroid cancer

    PubMed Central

    Thomas, Dolly; Friedman, Susan; Lin, Reigh-Yi

    2009-01-01

    Ongoing advances in stem cell research have opened new avenues for therapy for many human disorders. Until recently, however, thyroid stem cells have been relatively understudied. Here, we review what is known about thyroid stem cells and explore their utility as models of normal and malignant biological development. We also discuss the cellular origin of thyroid cancer stem cells and explore the clinical implications of cancer stem cells in the thyroid gland. Since thyroid cancer is the most common form of endocrine cancer and that thyroid hormone is needed for the growth and metabolism of each cell in the body, understanding the molecular and the cellular aspects of thyroid stem cell biology will ultimately provide insights into mechanisms underlying human disease. PMID:18310275

  20. A study of structural differences between liver cancer cells and normal liver cells using FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Sheng, Daping; Xu, Fangcheng; Yu, Qiang; Fang, Tingting; Xia, Junjun; Li, Seruo; Wang, Xin

    2015-11-01

    Since liver cancer seriously threatens human health, it is very urgent to explore an effective method for diagnosing liver cancer early. In this study, we investigated the structure differences of IR spectra between neoplastic liver cells and normal liver cells. The major differences of absorption bands were observed between liver cancer cells and normal liver cells, the values of A2955/A2921, A1744/A1082, A1640/A1535, H1121/H1020 might be potentially useful factors for distinguishing liver cancer cells from normal liver cells. Curve fitting also provided some important information on structural differences between malignant and normal liver cancer cells. Furthermore, IR spectra combined with hierarchical cluster analysis could make a distinction between liver cancer cells and normal liver cells. The present results provided enough cell basis for diagnosis of liver cancer by FTIR spectroscopy, suggesting FTIR spectroscopy may be a potentially useful tool for liver cancer diagnosis.

  1. [Immunophenotypic characteristics of peripheral blood cells in normal elderly men].

    PubMed

    Wang, Ya-Zhe; Chang, Yan; Lu, Dan; Shi, Hong-Xia; Huang, Xiao-Jun; Liu, Yan-Rong

    2013-12-01

    This study was aimed to distinguish abnormal cells and to diagnose hematologic diseases through recognizing antigen expression pattern and percentage of peripheral blood cells in normal elderly men. Antigen expression of blast cells, granulocytes, monocytes, lymphocytes, nucleated red blood cells and plasma cells was detected by seven-color flow cytometry in a total of 88 peripheral blood samples from normal elderly men, aged median 82 years old, from 70 to 98 years. Groups were divided according to age, region and underlying diseases, and the percentages of different subgroup cells were examined to confirm whether the differences were significant or not. The results showed that the median proportion of CD34(+) blast cells in peripheral blood from normal elderly men were 0.017% (0.015%-0.020%), with high expression of HLA-DR, CD33, CD13 and CD117, low expression of myeloid antigens, such as CD15, CD11b and CD16, while lymphoid antigens were seldom positive, including CD7, CD19 and CD56. Dim-expression of CD38 was found in peripheral blood blast cells, CD38(dim)+/- cell percentage in blast cells was 61.36% ± 18.26%. In the differentiation and development of granulocytes, CD16(-), CD13(+) CD16(+) (intermediate) and CD16(+) (strong) CD13(+) cells appeared in sequence from immature to mature granulocytes, whose median proportions in nuclear cells were 0.04%, 0.30% and 61.30%, respectively. The percentages of immature monocytes, such as CD64(+) CD14(-) and HLA-DR(+) CD11b(-) cells, were from 0.00% to 0.10% and from 0.07% to 0.68%, separately. No significant differences were found between different subgroups (P > 0.05). It is concluded that the immunophenotypic characteristics and referential percentages of CD34(+) blast cells, granulocytes and monocytes with different development stages in peripheral blood from normal elderly men are recognized, which can help to discriminate abnormal cells.

  2. Chemical Profiling of the Plant Cell Wall through Raman Microspectroscopy

    SciTech Connect

    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.

  3. Biosynthesis of non-cellulosic polysaccharides of plant cell walls.

    PubMed

    Dhugga, Kanwarpal S

    2012-02-01

    Enzymes that make the polymer backbones of plant cell wall polysaccharides have proven to be recalcitrant to biochemical purification. Availability of mutational genetics and genomic tools paved the way for rapid progress in identifying genes encoding various cell wall glycan synthases. Mutational genetics, the primary tool used in unraveling cellulose biosynthesis, was ineffective in assigning function to any of the hemicellulosic, polymerizing glycan synthases. A combination of comparative genomics and functional expression in a heterologous system allowed identification of various cellulose synthase-like (Csl) sequences as being involved in the formation of β-1,4-mannan, β-1,4-glucan, and mixed-linked glucan. A number of xylose-deficient mutants have led to a variety of genes, none of which thus far possesses the motifs known to be conserved among polymerizing β-glycan synthases. Except for xylan synthase, which appears to be an agglomerate of proteins just like cellulose synthase, Golgi glycan synthases already identified suggest that the catalytic polypeptide by itself is sufficient for enzyme activity, most likely as a homodimer. Several of the Csl genes remain to be assigned a function. The possibility of the involvement of various Csl genes in making more than one product remains.

  4. Ultrastructure of the Epidermal Cell Wall and Cuticle of Tomato Fruit (Solanum lycopersicum L.) during Development.

    PubMed

    Segado, Patricia; Domínguez, Eva; Heredia, Antonio

    2016-02-01

    The epidermis plays a pivotal role in plant development and interaction with the environment. However, it is still poorly understood, especially its outer epidermal wall: a singular wall covered by a cuticle. Changes in the cuticle and cell wall structures are important to fully understand their functions. In this work, an ultrastructure and immunocytochemical approach was taken to identify changes in the cuticle and the main components of the epidermal cell wall during tomato fruit development. A thin and uniform procuticle was already present before fruit set. During cell division, the inner side of the procuticle showed a globular structure with vesicle-like particles in the cell wall close to the cuticle. Transition between cell division and elongation was accompanied by a dramatic increase in cuticle thickness, which represented more than half of the outer epidermal wall, and the lamellate arrangement of the non-cutinized cell wall. Changes in this non-cutinized outer wall during development showed specific features not shared with other cell walls. The coordinated nature of the changes observed in the cuticle and the epidermal cell wall indicate a deep interaction between these two supramolecular structures. Hence, the cuticle should be interpreted within the context of the outer epidermal wall.

  5. The toughness of secondary cell wall and woody tissue

    PubMed Central

    Lucas, P. W.; Tan, H. T. W.; Cheng, P. Y.

    1997-01-01

    The 'across grain' toughness of 51 woods has been determined on thin wet sections using scissors. The moisture content of sections and the varying sharpness of the scissor blades had little effect on the results. In thin sections (less than 0.6mm), toughness rose linearly with section thickness. The intercept toughness at zero thickness, estimated from regression analysis, was proportional to relative density, consistent with values reported for non-woody plant tissues. Extrapolation of the intercept toughness of these woods and other plant tissues/materials to a relative density of 1.0 predicted a toughness of 3.45kJ m-2 , which we identify with the intrinsic toughness of the cell wall. This quantity appears to predict published results from KIC tests on woods and is related to the propensity for crack deflection. The slope of the relationship between section thickness and toughness, describing the work of plastic buckling of cells, was not proportional to relative density, the lightest (balsa) and heaviest (lignum vitae) woods fracturing with less plastic work than predicted. The size of the plastic zone around the crack tip was estimated to be 0.5mm in size. From this, the hypothetical overall toughness of a thick (greater than 1 mm) block of solid cell wall material was calculated as 39.35 kJ m-2, due to both cell wall resistance (10 per cent) and the plastic buckling of cells (90 per cent). This value successfully predicts the toughness of most commercial woods (of relative densities between 0.2 and 0.8) from 'work area' tests in tension and bending. Though density was the most important factor, both fibre width/fibre length (in hardwoods) and lignin/cellulose ratios were negatively correlated with the work of plastic buckling, after correcting for density. At low densities the work of plastic buckling in the longitudinal radial (LR) direction exceeded that in longitudinal tangential (LT), but the reverse was true for relative densities above 0.25. This could

  6. Comparison of Chemical Components of Cell Walls of Brucella abortus Strains of Low and High Virulence.

    PubMed

    Kellerman, G D; Foster, J W; Badakhsh, F F

    1970-09-01

    Amino acid, carbohydrate, and lipid components of cell walls of Brucella abortus strain 19A (low virulence) and strain 2308 (high virulence) were compared by thin layer chromatography (TLC) and by use of an amino acid analyzer. A total of 15 amino acids were detected by both chromatographic methods. Each amino acid was present in greater amounts in strain 2308 than in strain 19A when equal amounts of hydrolysates of cell wall and endotoxin-containing preparations were analyzed. A component with the same R(F) value as ethanolamine was present in strain 2308 cell wall hydrolysates but was not revealed by TLC of strain 19A cell wall hydrolysates. This component was not detected with the amino acid analyzer. TLC of cell walls tagged with 2,4-dinitrofluorobenzene prior to hydrolysis showed that phenylalanine was a terminal amino acid in cell walls of B. abortus strains 19A and 2308, B. suis strain 1776, and B. melitensis strain 2500. Carbohydrates detected in cell walls of strains 19A and 2308 by TLC were tentatively identified as glucose, mannose, rhamnose, and galactose. Colorimetric tests were also positive for 2-keto-3-deoxy-octulosonic acid, heptose, and dideoxyhexose. At least seven lipid components were detected by TLC of ether extracts of cell walls of strains 19A and 2308. It is suggested that one or more lipids is important in maintaining cell wall structure, because isolated cell walls rapidly became fragmented after exposure to ether.

  7. Plant Cell Wall Proteins: A Large Body of Data, but What about Runaways?

    PubMed Central

    Albenne, Cécile; Canut, Hervé; Hoffmann, Laurent; Jamet, Elisabeth

    2014-01-01

    Plant cell wall proteomics has been a very dynamic field of research for about fifteen years. A full range of strategies has been proposed to increase the number of identified proteins and to characterize their post-translational modifications. The protocols are still improving to enlarge the coverage of cell wall proteomes. Comparisons between these proteomes have been done based on various working strategies or different physiological stages. In this review, two points are highlighted. The first point is related to data analysis with an overview of the cell wall proteomes already described. A large body of data is now available with the description of cell wall proteomes of seventeen plant species. CWP contents exhibit particularities in relation to the major differences in cell wall composition and structure between these plants and between plant organs. The second point is related to methodology and concerns the present limitations of the coverage of cell wall proteomes. Because of the variety of cell wall structures and of the diversity of protein/polysaccharide and protein/protein interactions in cell walls, some CWPs can be missing either because they are washed out during the purification of cell walls or because they are covalently linked to cell wall components. PMID:28250379

  8. Plant Cell Wall Proteins: A Large Body of Data, but What about Runaways?

    PubMed

    Albenne, Cécile; Canut, Hervé; Hoffmann, Laurent; Jamet, Elisabeth

    2014-04-17

    Plant cell wall proteomics has been a very dynamic field of research for about fifteen years. A full range of strategies has been proposed to increase the number of identified proteins and to characterize their post-translational modifications. The protocols are still improving to enlarge the coverage of cell wall proteomes. Comparisons between these proteomes have been done based on various working strategies or different physiological stages. In this review, two points are highlighted. The first point is related to data analysis with an overview of the cell wall proteomes already described. A large body of data is now available with the description of cell wall proteomes of seventeen plant species. CWP contents exhibit particularities in relation to the major differences in cell wall composition and structure between these plants and between plant organs. The second point is related to methodology and concerns the present limitations of the coverage of cell wall proteomes. Because of the variety of cell wall structures and of the diversity of protein/polysaccharide and protein/protein interactions in cell walls, some CWPs can be missing either because they are washed out during the purification of cell walls or because they are covalently linked to cell wall components.

  9. Cell wall proteins of Sporothrix schenckii as immunoprotective agents.

    PubMed

    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).

  10. Rapid regulatory control of plant cell expansion and wall relaxation

    SciTech Connect

    Cosgrove, D.J.

    1991-08-14

    The aim of this project is to elucidate the biophysical and cellular mechanisms that control plant cell expansion. At present we are attempting to characterize the kinetics of the system(s) responsible for regulatory and compensatory behavior of growing cells and tissues. This work is significantly because it indicates that biochemical loosening and biophysical stress relaxation of the wall are part of a feedback loop controlling growth. This report briefly summarizes the efforts and results of the past 12 months. In large part, we have been trying to analyze the nature of growth rate noise,'' i.e. spontaneous and often erratic variations in growth rate. We are obtaining evidence that such noise'' is not random, but rather reveals an underlying growth mechanism with complex dynamics.

  11. Monosaccharide and Chitin Content of Cell Walls of Histoplasma capsulatum and Blastomyces dermatitidis

    PubMed Central

    Domer, Judith E.

    1971-01-01

    Cell walls of Histoplasma capsulatum and Blastomyces dermatitidis, obtained by mechanical breakage of yeast- and mycelial-phase cultures, were lipid-extracted and then fractionated with ethylenediamine. Unextracted cell walls, lipid-extracted cell walls, and the three fractions resulting from ethylenediamine treatment were examined for monosaccharide and chitin content. The yeast-phase cell walls of five strains of H. capsulatum fell into two categories, designated chemotypes I and II, one of which, chemotype II, was similar to yeast-phase cell walls derived from three strains of B. dermatitidis. H. capsulatum chemotype I cell walls were characterized by lower content of material soluble in ethylenediamine, higher chitin content, and lower monosaccharide content than H. capsulatum chemotype II or B. dermatitidis cell walls. Approximately 80% of the monosaccharides of chemotype I cell walls was combined in forms susceptible to attack by mild acid hydrolysis, compared with about 50% of the monosaccharides of chemotype II and B. dermatitidis. H. capsulatum and B. dermatitidis yeast-phase cell walls could be distinguished, however, by their susceptibility to attack by a crude enzyme system derived from a Streptomyces sp. incubated with chitin as the only carbon source. Both glucose and acetylglucosamine were released from H. capsulatum cell walls, regardless of chemotype, during enzymatic hydrolysis, whereas only acetylglucosamine was released from B. dermatitidis yeast-phase cell walls. Mycelial-phase cell walls of H. capsulatum and B. dermatitidis were characterized by lower content of material soluble in ethylenediamine, higher proportions of mannose, and lower chitin content than their respective yeast phases. Glucose and acetylglucosamine were both released from all mycelial-phase cell walls, whether H. capsulatum or B. dermatitidis, by the crude enzyme system. PMID:5095293

  12. G-fibre cell wall development in willow stems during tension wood induction

    PubMed Central

    Gritsch, Cristina; Wan, Yongfang; Mitchell, Rowan A. C.; Shewry, Peter R.; Hanley, Steven J.; Karp, Angela

    2015-01-01

    Willows (Salix spp.) are important as a potential feedstock for bioenergy and biofuels. Previous work suggested that reaction wood (RW) formation could be a desirable trait for biofuel production in willows as it is associated with increased glucose yields, but willow RW has not been characterized for cell wall components. Fasciclin-like arabinogalactan (FLA) proteins are highly up-regulated in RW of poplars and are considered to be involved in cell adhesion and cellulose biosynthesis. COBRA genes are involved in anisotropic cell expansion by modulating the orientation of cellulose microfibril deposition. This study determined the temporal and spatial deposition of non-cellulosic polysaccharides in cell walls of the tension wood (TW) component of willow RW and compared it with opposite wood (OW) and normal wood (NW) using specific antibodies and confocal laser scanning microscopy and transmission electron microscopy. In addition, the expression patterns of an FLA gene (SxFLA12) and a COBRA-like gene (SxCOBL4) were compared using RNA in situ hybridization. Deposition of the non-cellulosic polysaccharides (1–4)-β-D-galactan, mannan and de-esterified homogalacturonan was found to be highly associated with TW, often with the G-layer itself. Of particular interest was that the G-layer itself can be highly enriched in (1–4)-β-D-galactan, especially in G-fibres where the G-layer is still thickening, which contrasts with previous studies in poplar. Only xylan showed a similar distribution in TW, OW, and NW, being restricted to the secondary cell wall layers. SxFLA12 and SxCOBL4 transcripts were specifically expressed in developing TW, confirming their importance. A model of polysaccharides distribution in developing willow G-fibre cells is presented. PMID:26220085

  13. G-fibre cell wall development in willow stems during tension wood induction.

    PubMed

    Gritsch, Cristina; Wan, Yongfang; Mitchell, Rowan A C; Shewry, Peter R; Hanley, Steven J; Karp, Angela

    2015-10-01

    Willows (Salix spp.) are important as a potential feedstock for bioenergy and biofuels. Previous work suggested that reaction wood (RW) formation could be a desirable trait for biofuel production in willows as it is associated with increased glucose yields, but willow RW has not been characterized for cell wall components. Fasciclin-like arabinogalactan (FLA) proteins are highly up-regulated in RW of poplars and are considered to be involved in cell adhesion and cellulose biosynthesis. COBRA genes are involved in anisotropic cell expansion by modulating the orientation of cellulose microfibril deposition. This study determined the temporal and spatial deposition of non-cellulosic polysaccharides in cell walls of the tension wood (TW) component of willow RW and compared it with opposite wood (OW) and normal wood (NW) using specific antibodies and confocal laser scanning microscopy and transmission electron microscopy. In addition, the expression patterns of an FLA gene (SxFLA12) and a COBRA-like gene (SxCOBL4) were compared using RNA in situ hybridization. Deposition of the non-cellulosic polysaccharides (1-4)-β-D-galactan, mannan and de-esterified homogalacturonan was found to be highly associated with TW, often with the G-layer itself. Of particular interest was that the G-layer itself can be highly enriched in (1-4)-β-D-galactan, especially in G-fibres where the G-layer is still thickening, which contrasts with previous studies in poplar. Only xylan showed a similar distribution in TW, OW, and NW, being restricted to the secondary cell wall layers. SxFLA12 and SxCOBL4 transcripts were specifically expressed in developing TW, confirming their importance. A model of polysaccharides distribution in developing willow G-fibre cells is presented.

  14. Characterization of Plant Cell Wall Damage-Associated Molecular Patterns Regulating Immune Responses.

    PubMed

    Bacete, Laura; Mélida, Hugo; Pattathil, Sivakumar; Hahn, Michael G; Molina, Antonio; Miedes, Eva

    2017-01-01

    The plant cell wall is one of the first defensive barriers that pathogens need to overcome to successfully colonize plant tissues. Plant cell wall is considered a dynamic structure that regulates both constitutive and inducible defense mechanisms. The wall is a potential source of a diverse set of Damage-Associated Molecular Patterns (DAMPs), which are signalling molecules that trigger immune responses. However, just a few active wall ligands, such as oligogalacturonic acids (OGs), have been characterized so far. To identify additional wall-derived DAMPs, we obtained different plant wall fractions and tested their capacity to trigger immune responses using a calcium read-out system. To characterize the active DAMPs structures present in these fractions, we applied Glycome Profiling, a technology that uses a large and diverse set of specific monoclonal antibodies against wall carbohydrate ligands. The methods describe here can be used in combination with other biochemical approaches to identify and purify new plant cell wall DAMPs.

  15. The connection of cytoskeletal network with plasma membrane and the cell wall

    PubMed Central

    Liu, Zengyu; Persson, Staffan; Zhang, Yi

    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 biosynthesis and modifications, and aim to provide a platform for further studies in this field. PMID:25693826

  16. Murein and pseudomurein cell wall binding domains of bacteria and archaea--a comparative view.

    PubMed

    Visweswaran, Ganesh Ram R; Dijkstra, Bauke W; Kok, Jan

    2011-12-01

    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 acts as an adhesion platform for bacteriophages. The walls of bacteria and archaea are mostly composed of murein and pseudomurein, respectively. Cell wall binding domains play a crucial role in the non-covalent attachment of proteins to cell walls. Here, we give an overview of the similarities and differences in the biochemical and functional properties of the two major murein and pseudomurein cell wall binding domains, i.e., the Lysin Motif (LysM) domain (Pfam PF01476) and the pseudomurein binding (PMB) domain (Pfam PF09373) of bacteria and archaea, respectively.

  17. Duplication of the genome in normal and cancer cell cycles.

    PubMed

    Bandura, Jennifer L; Calvi, Brian R

    2002-01-01

    It is critical to discover the mechanisms of normal cell cycle regulation if we are to fully understand what goes awry in cancer cells. The normal eukaryotic cell tightly regulates the activity of origins of DNA replication so that the genome is duplicated exactly once per cell cycle. Over the last ten years much has been learned concerning the cell cycle regulation of origin activity. It is now clear that the proteins and cell cycle mechanisms that control origin activity are largely conserved from yeast to humans. Despite this conservation, the composition of origins of DNA replication in higher eukaryotes remains ill defined. A DNA consensus for predicting origins has yet to emerge, and it is of some debate whether primary DNA sequence determines where replication initiates. In this review we outline what is known about origin structure and the mechanism of once per cell cycle DNA replication with an emphasis on recent advances in mammalian cells. We discuss the possible relevance of these regulatory pathways for cancer biology and therapy.

  18. Immortalization of human normal and NF1 neurofibroma Schwann cells.

    PubMed

    Li, Hua; Chang, Lung-Ji; Neubauer, Debbie R; Muir, David F; Wallace, Margaret R

    2016-10-01

    Neurofibromas, which are benign Schwann cell tumors, are the hallmark feature in the autosomal dominant condition neurofibromatosis 1 (NF1) and are associated with biallelic loss of NF1 gene function. There is a need for effective therapies for neurofibromas, particularly the larger, plexiform neurofibromas. Tissue culture is an important tool for research. However, it is difficult to derive enriched human Schwann cell cultures, and most enter replicative senescence after 6-10 passages, impeding cell-based research in NF1. Through exogenous expression of human telomerase reverse transcriptase and murine cyclin-dependent kinase (mCdk4), normal (NF1 wild-type), neurofibroma-derived Schwann cells heterozygous for NF1 mutation, and neurofibroma-derived Schwann cells homozygous for NF1 mutation were immortalized, including some matched samples from the same NF1 patient. Initial experiments employed retroviral vectors, while subsequent work utilized lentiviral vectors carrying these genes because of improved efficiency. Expression of both transgenes was required for immortalization. Molecular and immunohistochemical analysis indicated that these cell lines are of Schwann cell lineage and have a range of phenotypes, many of which are consistent with their primary cultures. This is the first report of immortalization and detailed characterization of multiple human NF1 normal nerve and neurofibroma-derived Schwann cell lines, which will be highly useful research tools to study NF1 and other Schwann tumor biology and conditions.

  19. A cell-based screening system for detection of inhibitors toward mycobacterial cell wall core.

    PubMed

    Gao, Peng; Guan, Yan; Song, Danqing; Xiao, Chunling

    2009-06-01

    Mycobacterium tuberculosis and nonpathogenic bacteria, Corynebacterium glutamicum, possess a common and unusual cell wall architecture. A cell-based screening system was designed to identify novel compounds interacting with the synthesis, assembly or regulation of the M. tuberculosis cell wall. C. glutamicum was tested in a paired medium assay in 96-well plates with natural product extracts and pure chemical compounds in the presence and absence of the osmotic stabilizer, sorbitol and some ions. Growth was visually examined over a 12-h period and detected with a microplate reader for absorbance at 544 nm. Screening hits from the osmotic stabilizer rescue were then examined by mycolic acid analysis to confirm the effect on cell wall integrity.

  20. Hydrodynamics, wall-slip, and normal-stress differences in rarefied granular Poiseuille flow

    NASA Astrophysics Data System (ADS)

    Gupta, Ronak; Alam, Meheboob

    2017-02-01

    Hydrodynamic fields, macroscopic boundary conditions, and non-Newtonian rheology of the acceleration-driven Poiseuille flow of a dilute granular gas are probed using "direct simulation Monte Carlo" method for a range of Knudsen numbers (Kn, the ratio between the mean free path and the macroscopic length), spanning the rarefied regime of slip and transitional flows. It is shown that the "dissipation-induced clustering" (for 1 -en>0 , where en is the restitution coefficient), leading to inhomogeneous density profiles along the transverse direction, competes with "rarefaction-induced declustering" (for Kn>0 ) phenomenon, leaving seemingly "anomalous" footprints on several hydrodynamic and rheological quantities; one example is the well-known rarefaction-induced temperature bimodality, which could also result from inelastic dissipation that dominates in the continuum limit (Kn→0 ) as found recently [Alam et al., J. Fluid Mech. 782, 99 (2015), 10.1017/jfm.2015.523]. The simulation data on the slip velocity and the temperature slip are contrasted with well-established boundary conditions for molecular gases. A modified Maxwell-Navier-type boundary condition is found to hold in granular Poiseuille flow, with the velocity slip length following a power-law relation with Knudsen number Knδ, with δ ≈0.95 , for Kn≤0.1 . Transverse profiles of both first [N1(y ) ] and second [N2(y ) ] normal stress differences seem to correlate well with respective density profiles at small Kn; their centerline values [N1(0 ) and N2(0 ) ] can be of "odd" sign with respect to their counterparts in molecular gases. The phase diagrams are constructed in the (Kn,1 -en ) plane that demarcates the regions of influence of inelasticity and rarefaction, which compete with each other resulting in the sign change of both N1(0 ) and N2(0 ) . The results on normal stress differences are rationalized via a comparison with a Burnett-order theory [Sela and Goldhirsch, J. Fluid Mech. 361, 41 (1998), 10

  1. Hydrodynamics, wall-slip, and normal-stress differences in rarefied granular Poiseuille flow.

    PubMed

    Gupta, Ronak; Alam, Meheboob

    2017-02-01

    Hydrodynamic fields, macroscopic boundary conditions, and non-Newtonian rheology of the acceleration-driven Poiseuille flow of a dilute granular gas are probed using "direct simulation Monte Carlo" method for a range of Knudsen numbers (Kn, the ratio between the mean free path and the macroscopic length), spanning the rarefied regime of slip and transitional flows. It is shown that the "dissipation-induced clustering" (for 1-e_{n}>0, where e_{n} is the restitution coefficient), leading to inhomogeneous density profiles along the transverse direction, competes with "rarefaction-induced declustering" (for Kn>0) phenomenon, leaving seemingly "anomalous" footprints on several hydrodynamic and rheological quantities; one example is the well-known rarefaction-induced temperature bimodality, which could also result from inelastic dissipation that dominates in the continuum limit (Kn→0) as found recently [Alam et al., J. Fluid Mech. 782, 99 (2015)JFLSA70022-112010.1017/jfm.2015.523]. The simulation data on the slip velocity and the temperature slip are contrasted with well-established boundary conditions for molecular gases. A modified Maxwell-Navier-type boundary condition is found to hold in granular Poiseuille flow, with the velocity slip length following a power-law relation with Knudsen number Kn^{δ}, with δ≈0.95, for Kn≤0.1. Transverse profiles of both first [N_{1}(y)] and second [N_{2}(y)] normal stress differences seem to correlate well with respective density profiles at small Kn; their centerline values [N_{1}(0) and N_{2}(0)] can be of "odd" sign with respect to their counterparts in molecular gases. The phase diagrams are constructed in the (Kn,1-e_{n}) plane that demarcates the regions of influence of inelasticity and rarefaction, which compete with each other resulting in the sign change of both N_{1}(0) and N_{2}(0). The results on normal stress differences are rationalized via a comparison with a Burnett-order theory [Sela and Goldhirsch,

  2. Polysaccharide-degrading Enzymes are Unable to Attack Plant Cell Walls without Prior Action by a “Wall-modifying Enzyme” 1

    PubMed Central

    Karr, Arthur L.; Albersheim, Peter

    1970-01-01

    A study of the degradation of plant cell walls by the mixture of enzymes present in Pectinol R-10 is described. A “wall-modifying enzyme” has been purified from this mixture by a combination of diethylaminoethyl cellulose, Bio Gel P-100, and carboxymethyl cellulose chromatography. Treatment of cell walls with the “wall-modifying enzyme” is shown to be a necessary prerequisite to wall degradation catalyzed by a mixture of polysaccharide-degrading enzymes prepared from Pectinol R-10 or by an α-galactosidase secreted by the pathogenic fungus Colletotrichum lindemuthianum. The action of the “wall-modifying enzyme” on cell walls is shown to result in both a release of water-soluble, 70% ethanol-insoluble polymers and an alteration of the residual cell wall. A purified preparation of the “wall-modifying enzyme” is unable to degrade a wide variety of polysaccharide, glycoside, and peptide substrates. However, the purified preparation of wall-modifying enzyme has a limited ability to degrade polygalacturonic acid. The fact that polygalacturonic acid inhibits the ability of the “wall-modifying enzyme” to affect cell walls suggests that the “wall-modifying enzyme” may be responsible for the limited polygalacturonic acid-degrading activity present in the purified preparation. The importance of a wall-modifying enzyme in developmental processes and in pathogenesis is discussed. PMID:16657425

  3. Optical Properties of Human Cancer and Normal Cells

    NASA Astrophysics Data System (ADS)

    Sander, Christopher; Sun, Nan; Johnson, Jeffrey; Stack, Sharon; Tanner, Carol; Ruggiero, Steven

    2014-03-01

    We have investigated the optical properties of human oral and ovarian cancer and normal cells. Specifically, we have measured the absolute optical extinction for both whole cells and intra-cellular material in aqueous suspension. Measurements were conducted over a wavelength range of 250 to 1000nm with 1 nm resolution using Light Transmission Spectroscopy (LTS). This provides both the absolute extinction of materials under study and, with Mie inversion, the absolute number of particles of a given diameter as a function of diameter in the range of 1 to 3000 nm. Our preliminary studies show significant differences in both the extinction and particle size distributions associated with cancer versus normal cells, which appear to be correlated with differences in the particle size distribution in the range of ~ 50 to 250 nm.

  4. High Power Tests of Normal Conducting Single-Cell Structures

    SciTech Connect

    Dolgashev, V.A.; Tantawi, S.G.; Nantista, C.D.; Higashi, Y.; Higo, T.; /KEK, Tsukuba

    2007-11-07

    We report the results of the first high power tests of single-cell traveling-wave and standing-wave structures. These tests are part of an experimental and theoretical study of rf breakdown in normal conducting structures at 11.4 GHz. The goal of this study is to determine the gradient potential of normal-conducting rf-powered particle beam accelerators. The test setup consists of reusable mode converters and short test structures and is powered by SLAC's XL-4 klystron. This setup was created for economical testing of different cell geometries, cell materials and preparation techniques with short turn-around time. The mode launchers and structures were manufactured at SLAC and KEK and tested in the SLAC Klystron Test Lab.

  5. Cell death during the postnatal morphogenesis of the normal rabbit kidney and in experimental renal polycystosis.

    PubMed Central

    García-Porrero, J A; Ojeda, J L; Hurlé, J M

    1978-01-01

    We have studied, by means of optic and electron microscopy, the normal and abnormal cell death that takes place during the postnatal morphogenesis of rabbit kidney, and in the experimental renal polycystosis produced by methylprednisolone acetate. In the normal kidney intertubular cell death can be observed during the first 20 days of the postnatal development. However, cell death in the normal metanephric blastema is a very rare event. In the polycystic kidney numerous dead cells can be seen between the third and forty eighth days after injection. The topography and morphology of the dead cells depend on the stage in the evolution of the disease. In the 'stage of renal immaturity', dying and dead cells are present in the nephrogenic tissue, in the dilating collecting tubules and in the intertubular spaces. In this stage the cellular pathology is essentially nuclear. In the stage of tubular cysts, the dead cells are mostly located in the walls of cysts, with some dead cells, but mostly cellular debris in their lumina. At this stage the cellular pathology is basically cytoplasmic. The dead cells are eventually digested by what appear to be phagocytes of tubular epithelial origin. It is suggested that cell death is an important factor in the evolution of the lesions of renal polycystosis induced by corticosteroids, and probably in the initiation of the pathological process as well. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 17 Fig. 18 Fig. 19 PMID:670065

  6. Effect of silencing the two major tomato fruit pectin methylesterase isoforms on cell wall pectin metabolism.

    PubMed

    Wen, B; Ström, A; Tasker, A; West, G; Tucker, G A

    2013-11-01

    Post-harvest storage is largely limited by fruit softening, a result of cell wall degradation. Pectin methylesterase (PE) (EC 3.1.1.11) is a major hydrolase responsible for pectin de-esterification in the cell wall, a response to fruit ripening. Two major PE isoforms, PE1 and PE2, have been isolated from tomato (Solanum lycopersicon) pericarp tissue and both have previously been down-regulated using antisense suppression. In this paper, PE1 and PE2 double antisense tomato plants were successfully generated through crossing the two single antisense lines. In the double antisense fruit, approximately 10% of normal PE activity remained and ripening associated pectin de-esterification was almost completely blocked. However, double antisense fruit softened normally during ripening. In tomato fruit, the PE1 isoform was found to contribute little to total PE activity and have little effect on the degree of esterification of pectin. In contrast, the other dominant fruit isoform, PE2, has a major impact on de-esterification of total pectin. PE2 appears to act on non-CDTA-soluble pectin during ripening and on CDTA-soluble pectin before the start of ripening in a potentially block-wise fashion.

  7. The influence of supine posture on chest wall volume changes is higher in obese than in normal weight children.

    PubMed

    Silva, Letícia; Barcelar, Jacqueline de Melo; Rattes, Catarina Souza; Sayão, Larissa Bouwman; Reinaux, Cyda Albuquerque; Campos, Shirley L; Brandão, Daniella Cunha; Fregonezi, Guilherme; Aliverti, Andrea; Dornelas de Andrade, Armèle

    2015-02-01

    The objective of this study was to analyze thoraco-abdominal kinematics in obese children in seated and supine positions during spontaneous quiet breathing. An observational study of pulmonary function and chest wall volume assessed by optoelectronic plethysmography was conducted on 35 children aged 8-12 years that were divided into 2 groups according to weight/height ratio percentiles: there were 18 obese children with percentiles greater than 95 and 17 normal weight children with percentiles of 5-85. Pulmonary function (forced expiratory volume in 1 s (FEV1); forced vital capacity (FVC); and FEV1/FVC ratio), ventilatory pattern, total and compartment chest wall volume variations, and thoraco-abdominal asynchronies were evaluated. Tidal volume was greater in seated position. Pulmonary and abdominal rib cage tidal volume and their percentage contribution to tidal volume were smaller in supine position in both obese and control children, while abdominal tidal volume and its percentage contribution was greater in the supine position only in obese children and not in controls. No statistically significant differences were found between obese and control children and between supine and seated positions regarding thoraco-abdominal asynchronies. We conclude that in obese children thoraco-abdominal kinematics is influenced by supine posture, with an increase of the abdominal and a decreased rib cage contribution to ventilation, suggesting that in this posture areas of hypoventilation can occur in the lung.

  8. Fractionation and Structural Characterization of Arabinogalactan-Proteins from the Cell Wall of Rose Cells.

    PubMed Central

    Serpe, M. D.; Nothnagel, E. A.

    1995-01-01

    Arabinogalactan-proteins (AGPs) have been purified from Paul's Scarlet rose (Rosa sp.) cell walls. As estimated by gel permeation chromatography, the apparent molecular masses of the two major cell-wall AGP fractions were 130 and 242 kD. Since the 130-kD AGP had a ratio of arabinose/glucuronic acid that was 12 times higher than that of the 242-kD AGP, the fractions were named cell-wall AGP1 (CW-AGP1) and glucuronogalactan-protein (GGP), respectively. CW-AGP1 and GGP contained predominantly t-arabinofuranosyl residues; 3-linked, 6-linked, and 3,6-branched galactopyranosyl residues; and 4-linked and t-glucuronopyranosyl residues. The 1H-nuclear magnetic resonance spectra of CW-AGP1 and GGP showed that the arabinofuranosyl and galactopyranosyl residues were predominantly in [alpha]- and [beta]-anomeric configuration, respectively, and that GGP contained a few O-acetyl residues. The protein moieties of CW-AGP1 and GGP were both rich in hydroxyproline and alanine but differed in the percentage of various amino acids, including hydroxyproline, alanine, serine, and glycine. Cell-wall AGPs bound to ([beta]-D-glucosyl)3 Yariv phenylglycoside, but the stoichiometry of binding was about 6 times greater in GGP than in other Rosa AGPs. GGP seems to be peculiar to the cell wall, since no similar molecule was found in the culture medium. PMID:12228648

  9. Cell Wall Yield Properties of Growing Tissue 1

    PubMed Central

    Cosgrove, Daniel J.

    1985-01-01

    Growing pea stem tissue, when isolated from an external supply of water, undegoes stress relaxation because of continued loosening of the cell wall. A theoretical analysis is presented to show that such stress relaxation should result in an exponential decrease in turgor pressure down to the yield threshold (Y), with a rate constant given by φε where φ is the metabolically maintained irreversible extensibility of the cell wall and ε is the volumetric elastic modulus of the cell. This theory represents a new method to determine φ in growing tissues. Stress relaxation was measured in pea (Pisum sativus L.) stem segments using the pressure microprobe technique. From the rate of stress relaxation, φ of segments pretreated with water was calculated to be 0.08 per megapascal per hour while that of auxin-pretreated tissue was 0.24 per megapascal per hour. These values agreed closely with estimates of φ made by a steady-state technique. The yield threshold (0.29 megapascal) was not affected by auxin. Technical difficulties with measuring φ by stress relaxation may arise due to an internal water reserve or due to changes in φ subsequent to excision. These difficulties are discussed and evaluated. A theoretical analysis is also presented to show that the tissue hydraulic conductance may be estimated from the T½ of tissue swelling. Experimentally, pea stems had a swelling T½ of 2.0 minutes, corresponding to a relative hydraulic conductance of about 2.0 per megapascal per hour. This value is at least 8 times larger than φ. From these data and from computer modeling, it appears that the radial gradient in water potential which sustains water uptake in growing pea segments is small (0.04 megapascal). This means that hydraulic conductance does not substantially restrict growth. The results also demonstrate that the stimulation of growth by auxin can be entirely accounted for by the change in φ. PMID:16664243

  10. Single-walled carbon nanotubes as specific targeting and Raman spectroscopic agents for detection and discrimination of single human breast cancer cells

    NASA Astrophysics Data System (ADS)

    Nima, Zeid A.; Mahmood, Meena W.; Karmakar, Alokita; Mustafa, Thikra; Bourdo, Shawn; Xu, Yang; Biris, Alexandru S.

    2013-05-01

    Raman active nano-complex agents based on single-walled carbon nanotubes (SWCNTs) are prepared and used for the swift and specific detection of breast cancer cells. SWCNTs are functionalized to bond covalently with the anti-epithelial cell adhesion molecule (anti-EpCAM) antibody, which is specific to the highly expressed EpCAM antigen on the surface of breast cancer cells (MCF-7), but not on normal cells. The Raman nano-complexes demonstrate excellent ability to detect in vitro single breast cancer cells (MCF-7) and discriminate between them and normal fibroblast cells during the first 30 min of the targeting process. Raman linearity scanning is collected from a monolayer cell mixture, including both cancer cells and normal cells incubated with anti-EpCAM-SWCNTs, using a 633-nm laser excitation. The results shows that the Raman signal collected from targeted MCF-7 cells is extremely high, whereas there is little signal from the normal cells.

  11. Normalization of CD4+ T Cell Metabolism Reverses Lupus

    PubMed Central

    Yin, Yiming; Choi, Seung-Chul; Xu, Zhiwei; Perry, Daniel J.; Seay, Howard; Croker, Byron P.; Sobel, Eric S.; Brusko, Todd M.; Morel, Laurence

    2015-01-01

    Systemic Lupus Erythematosus (SLE) is an autoimmune disease in which autoreactive CD4+ T cells play an essential role. CD4+ T cells rely on glycolysis for inflammatory effector functions, but recent studies have shown that mitochondrial metabolism supports their chronic activation. How these processes contribute to lupus is unclear. Here, we show that both glycolysis and mitochondrial oxidative metabolism are elevated in CD4+ T cells from lupus-prone B6.Sle1.Sle2.Sle3 (TC) mice as compared to non-autoimmune controls. In vitro, both the mitochondrial metabolism inhibitor metformin and the glucose metabolism inhibitor 2-Deoxy-D-glucose (2DG) reduced IFNγ production, although at different stages of activation. Metformin also restored the defective IL-2 production by TC CD4+ T cells. In vivo, treatment of TC mice and other lupus models with a combination of metformin and 2DG normalized T cell metabolism and reversed disease biomarkers. Further, CD4+ T cells from SLE patients also exhibited enhanced glycolysis and mitochondrial metabolism that correlated with their activation status, and their excessive IFNγ production was significantly reduced by metformin in vitro. These results suggest that normalization of T cell metabolism through the dual inhibition of glycolysis and mitochondrial metabolism is a promising therapeutic venue for SLE. PMID:25673763

  12. Prediction of Bubble Diameter at Detachment from a Wall Orifice in Liquid Cross Flow Under Reduced and Normal Gravity Conditions

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Kamotani, Y.

    2003-01-01

    Bubble formation and detachment is an integral part of the two-phase flow science. The objective of the present work is to theoretically investigate the effects of liquid cross-flow velocity, gas flow rate embodied in the momentum flux force, and orifice diameter on bubble formation in a wall-bubble injection configuration. A two-dimensional one-stage theoretical model based on a global force balance on the bubble evolving from a wall orifice in a cross liquid flow is presented in this work. In this model, relevant forces acting on the evolving bubble are expressed in terms of the bubble center of mass coordinates and solved simultaneously. Relevant forces in low gravity included the momentum flux, shear-lift, surface tension, drag and inertia forces. Under normal gravity conditions, the buoyancy force, which is dominant under such conditions, can be added to the force balance. Two detachment criteria were applicable depending on the gas to liquid momentum force ratio. For low ratios, the time when the bubble acceleration in the direction of the detachment angle is greater or equal to zero is calculated from the bubble x and y coordinates. This time is taken as the time at which all the detaching forces that are acting on the bubble are greater or equal to the attaching forces. For high gas to liquid momentum force ratios, the time at which the y coordinate less the bubble radius equals zero is calculated. The bubble diameter is evaluated at this time as the diameter at detachment from the fact that the bubble volume is simply given by the product of the gas flow rate and time elapsed. Comparison of the model s predictions was also made with predictions from a two-dimensional normal gravity model based on Kumar-Kuloor formulation and such a comparison is presented in this work.

  13. Ultrastructure of Fibre and Parenchyma Cell Walls During Early Stages of Culm Development in Dendrocalamus asper

    PubMed Central

    GRITSCH, CRISTINA SANCHIS; MURPHY, RICHARD J.

    2005-01-01

    • Background and Aims The anatomy of bamboo culms and the multilayered structure of fibre cell walls are known to be the main determinant factors for its physical and mechanical properties. Studies on the bamboo cell wall have focussed mainly on fully elongated and mature fibres. The main aim of this study was to describe the ultrastructure of primary and secondary cell walls in culm tissues of Dendrocalamus asper at different stages of development. • Methods The development of fibre and parenchyma tissues was classified into four stages based on light microscopy observations made in tissues from juvenile plants. The stages were used as a basis for transmission electron microscopy study on the ultrastructure of the cell wall during the process of primary and early secondary cell wall formation. Macerations and phloroglucinol–HCl staining were employed to investigate fibre cell elongation and fibre cell wall lignification, respectively. • Key Results The observations indicated that the primary wall is formed by the deposition of two distinct layers during the elongation of the internode and that secondary wall synthesis may begin before the complete cessation of internode and fibre elongation. Elongation was followed by a maturation phase characterized by the deposition of multiple secondary wall layers, which varied in number according to the cell type, location in the culm tissue and stage of shoot development. Lignification of fibre cell walls started at the period prior to the cessation of internode elongation. • Conclusions The structure of the primary cell wall was comprised of two layers. The fibre secondary cell wall began to be laid down while the cells were still undergoing some elongation, suggesting that it may act to cause the slow-down and eventual cessation of cell elongation. PMID:15665037

  14. Bacterial cell wall biogenesis is mediated by SEDS and PBP polymerase families functioning semi-autonomously

    PubMed Central

    Cho, Hongbaek; Wivagg, Carl N.; Kapoor, Mrinal; Barry, Zachary; Rohs, Patricia D.A.; Suh, Hyunsuk; Marto, Jarrod A.; Garner, Ethan C.; Bernhardt, Thomas G.

    2016-01-01

    Multi-protein complexes organized by cytoskeletal proteins are essential for cell wall biogenesis in most bacteria. Current models of the wall assembly mechanism assume class A penicillin-binding proteins (aPBPs), the targets of penicillin-like drugs, function as the primary cell wall polymerases within these machineries. Here, we use an in vivo cell wall polymerase assay in Escherichia coli combined with measurements of the localization dynamics of synthesis proteins to investigate this hypothesis. We find that aPBP activity is not necessary for glycan polymerization by the cell elongation machinery as is commonly believed. Instead, our results indicate that cell wall synthesis is mediated by two distinct polymerase systems, SEDS-family proteins working within the cytoskeletal machines and aPBP enzymes functioning outside of these complexes. These findings thus necessitate a fundamental change in our conception of the cell wall assembly process in bacteria. PMID:27643381

  15. Diverse Functions for Six Glycosyltransferases in Caulobacter crescentus Cell Wall Assembly

    PubMed Central

    Yakhnina, Anastasiya A.

    2013-01-01

    The essential process of peptidoglycan synthesis requires two enzymatic activities, transpeptidation and transglycosylation. While the PBP2 and PBP3 transpeptidases perform highly specialized functions that are widely conserved, the specific roles of different glycosyltransferases are poorly understood. For example, Caulobacter crescentus encodes six glycosyltransferase paralogs of largely unknown function. Using genetic analyses, we found that Caulobacter glycosyltransferases are primarily redundant but that PbpX is responsible for most of the essential glycosyltransferase activity. Cells containing PbpX as their sole glycosyltransferase are viable, and the loss of pbpX leads to a general defect in the integrity of the cell wall structure even in the presence of the other five glycosyltransferases. However, neither PbpX nor any of its paralogs is required for the specific processes of cell elongation or division, while the cell wall synthesis required for stalk biogenesis is only partially disrupted in several of the glycosyltransferase mutants. Despite their genetic redundancy, Caulobacter glycosyltransferases exhibit different subcellular localizations. We suggest that these enzymes have specialized roles and normally function in distinct subcomplexes but retain the ability to substitute for one another so as to ensure the robustness of the peptidoglycan synthesis process. PMID:23935048

  16. Chitosan, the deacetylated form of chitin, is necessary for cell wall integrity in Cryptococcus neoformans.

    PubMed

    Baker, Lorina G; Specht, Charles A; Donlin, Maureen J; Lodge, Jennifer K

    2007-05-01

    Cryptococcus neoformans is an opportunistic fungal pathogen that causes cryptococcal meningoencephalitis, particularly in immunocompromised patients. The fungal cell wall is an excellent target for antifungal therapies as it is an essential organelle that provides cell structure and integrity, it is needed for the localization or attachment of known virulence factors, including the polysaccharide capsule, melanin, and phospholipase, and it is critical for host-pathogen interactions. In C. neoformans, chitosan produced by the enzymatic removal of acetyl groups from nascent chitin polymers has been implicated as an important component of the vegetative cell wall. In this study, we identify four putative chitin/polysaccharide deacetylases in C. neoformans. We have demonstrated that three of these deacetylases, Cda1, Cda2, and Cda3, can account for all of the chitosan produced during vegetative growth in culture, but the function for one, Fpd1, remains undetermined. The data suggest a model for chitosan production in vegetatively growing C. neoformans where the three chitin deacetylases convert chitin generated by the chitin synthase Chs3 into chitosan. Utilizing a collection of chitin/polysaccharide deacetylase deletion strains, we determined that during vegetative growth, chitosan helps to maintain cell integrity and aids in bud separation. Additionally, chitosan is necessary for maintaining normal capsule width and the lack of chitosan results in a "leaky melanin" phenotype. Our analysis indicates that chitin deacetylases and the chitosan made by them may prove to be excellent antifungal targets.

  17. Ultrastructural Localization of a Bean Glycine-Rich Protein in Unlignified Primary Walls of Protoxylem Cells.

    PubMed Central

    Ryser, U; Keller, B

    1992-01-01

    A polyclonal antibody was used to localize a glycine-rich cell wall protein (GRP 1.8) in French bean hypocotyls with the indirect immunogold method. GRP 1.8 could be localized mainly in the unlignified primary cell walls of the oldest protoxylem elements and also in cell corners of both proto- and metaxylem elements. In addition, GRP 1.8 was detected in phloem using tissue printing. The labeled primary walls of dead protoxylem cells showed a characteristically dispersed ultrastructure, resulting from the action of hydrolases during the final steps of cell maturation and from mechanical stress due to hypocotyl growth. Primary walls of living protoxylem and adjacent parenchyma cells were only weakly labeled. This was true also for the secondary walls of proto- and metaxylem cells, which in addition showed high background labeling. Inhibition of lignification with a specific and potent inhibitor of phenylalanine ammonia-lyase did not lead to enhanced labeling of secondary walls, showing that lignin does not mask the presence of GRP 1.8 in these walls. Dictyosomes of living proto- and metaxylem cells were not labeled, but dictyosomes of xylem parenchyma cells without secondary walls, adjacent to strongly labeled protoxylem elements, were clearly labeled. These observations suggest that GRP 1.8 is not produced by xylem vessels but by xylem parenchyma cells that export the protein to the wall of protoxylem vessels. PMID:12297662

  18. Laccases Direct Lignification in the Discrete Secondary Cell Wall Domains of Protoxylem1[W][OPEN

    PubMed Central

    Schuetz, Mathias; Benske, Anika; Smith, Rebecca A.; Watanabe, Yoichiro; Tobimatsu, Yuki; Ralph, John; Demura, Taku; Ellis, Brian; Samuels, A. Lacey

    2014-01-01

    Plants precisely control lignin deposition in spiral or annular secondary cell wall domains during protoxylem tracheary element (TE) development. Because protoxylem TEs function to transport water within rapidly elongating tissues, it is important that lignin deposition is restricted to the secondary cell walls in order to preserve the plasticity of adjacent primary wall domains. The Arabidopsis (Arabidopsis thaliana) inducible VASCULAR NAC DOMAIN7 (VND7) protoxylem TE differentiation system permits the use of mutant backgrounds, fluorescent protein tagging, and high-resolution live-cell imaging of xylem cells during secondary cell wall development. Enzymes synthesizing monolignols, as well as putative monolignol transporters, showed a uniform distribution during protoxylem TE differentiation. By contrast, the oxidative enzymes LACCASE4 (LAC4) and LAC17 were spatially localized to secondary cell walls throughout protoxylem TE differentiation. These data support the hypothesis that precise delivery of oxidative enzymes determines the pattern of cell wall lignification. This view was supported by lac4lac17 mutant analysis demonstrating that laccases are necessary for protoxylem TE lignification. Overexpression studies showed that laccases are sufficient to catalyze ectopic lignin polymerization in primary cell walls when exogenous monolignols are supplied. Our data support a model of protoxylem TE lignification in which monolignols are highly mobile once exported to the cell wall, and in which precise targeting of laccases to secondary cell wall domains directs lignin deposition. PMID:25157028

  19. Laccases direct lignification in the discrete secondary cell wall domains of protoxylem.

    PubMed

    Schuetz, Mathias; Benske, Anika; Smith, Rebecca A; Watanabe, Yoichiro; Tobimatsu, Yuki; Ralph, John; Demura, Taku; Ellis, Brian; Samuels, A Lacey

    2014-10-01

    Plants precisely control lignin deposition in spiral or annular secondary cell wall domains during protoxylem tracheary element (TE) development. Because protoxylem TEs function to transport water within rapidly elongating tissues, it is important that lignin deposition is restricted to the secondary cell walls in order to preserve the plasticity of adjacent primary wall domains. The Arabidopsis (Arabidopsis thaliana) inducible VASCULAR NAC DOMAIN7 (VND7) protoxylem TE differentiation system permits the use of mutant backgrounds, fluorescent protein tagging, and high-resolution live-cell imaging of xylem cells during secondary cell wall development. Enzymes synthesizing monolignols, as well as putative monolignol transporters, showed a uniform distribution during protoxylem TE differentiation. By contrast, the oxidative enzymes LACCASE4 (LAC4) and LAC17 were spatially localized to secondary cell walls throughout protoxylem TE differentiation. These data support the hypothesis that precise delivery of oxidative enzymes determines the pattern of cell wall lignification. This view was supported by lac4lac17 mutant analysis demonstrating that laccases are necessary for protoxylem TE lignification. Overexpression studies showed that laccases are sufficient to catalyze ectopic lignin polymerization in primary cell walls when exogenous monolignols are supplied. Our data support a model of protoxylem TE lignification in which monolignols are highly mobile once exported to the cell wall, and in which precise targeting of laccases to secondary cell wall domains directs lignin deposition.

  20. Cell wall biogenesis of Arabidopsis thaliana elongating cells: transcriptomics complements proteomics

    PubMed Central

    Jamet, Elisabeth; Roujol, David; San-Clemente, Hélène; Irshad, Muhammad; Soubigou-Taconnat, Ludivine; Renou, Jean-Pierre; Pont-Lezica, Rafael

    2009-01-01

    Background Plant growth is a complex process involving cell division and elongation. Arabidopsis thaliana hypocotyls undergo a 100-fold length increase mainly by cell elongation. Cell enlargement implicates significant changes in the composition and structure of the cell wall. In order to understand cell wall biogenesis during cell elongation, mRNA profiling was made on half- (active elongation) and fully-grown (after growth arrest) etiolated hypocotyls. Results Transcriptomic analysis was focused on two sets of genes. The first set of 856 genes named cell wall genes (CWGs) included genes known to be involved in cell wall biogenesis. A significant proportion of them has detectable levels of transcripts (55.5%), suggesting that these processes are important throughout hypocotyl elongation and after growth arrest. Genes encoding proteins involved in substrate generation or in synthesis of polysaccharides, and extracellular proteins were found to have high transcript levels. A second set of 2927 genes labeled secretory pathway genes (SPGs) was studied to search for new genes encoding secreted proteins possibly involved in wall expansion. Based on transcript level, 433 genes were selected. Genes not known to be involved in cell elongation were found to have high levels of transcripts. Encoded proteins were proteases, protease inhibitors, proteins with interacting domains, and proteins involved in lipid metabolism. In addition, 125 of them encoded proteins with yet unknown function. Finally, comparison with results of a cell wall proteomic study on the same material revealed that 48 out of the 137 identified proteins were products of the genes having high or moderate level of transcripts. About 15% of the genes encoding proteins identified by proteomics showed levels of transcripts below background. Conclusion Members of known multigenic families involved in cell wall biogenesis, and new genes that might participate in cell elongation were identified. Significant

  1. Single walled carbon nanotube networks as substrates for bone cells

    NASA Astrophysics Data System (ADS)

    Tutak, Wojtek

    A central effort in biomedical research concerns the development of materials for sustaining and controlling cell growth. Carbon nanotube based substrates have been shown to support the growth of different kinds of cells. However the underlying molecular mechanisms remain poorly defined. To address the fundamental question of mechanisms by which nanotubes promote bone mitosis and histogenesis, primary calvariae osteoblastic cells were grown on single walled carbon nanotube (SWNT) network substrates. Using a combination of biochemical and optical techniques, we demonstrate here that SWNT networks promote cell development through two distinct steps. Initially, SWNTs are absorbed in a process that resembles endocytosis, inducing acute toxicity. Nanotube mediated cell destruction, however, induces a release of endogenous factors that act to boost the activity of the surviving cells by stimulating the synthesis of extracellular matrix. In the second part of the research, minimally invasive SWNT matrices were used to further investigate network properties for biomedical applications without extensive presence of cytotoxicity. In the literature, carbon nanotube based substrates have been shown to support the growth of different cell types and, as such, have raised considerable interest in their possible use in biomedical applications. Nanotube matrices that are embedded in polymers cause inherent changes in nanotube chemical and physical film properties. Thus, it is critical to understand how the physical properties of the pristine networks affect the biology of the host tissue. Here, we investigated how the physical and chemical properties of SWNT networks impact the response of MC3T3-E1 bone osteoblasts. We found that two fundamental steps in cell growth: initial attachment to the substrate and proliferation, are strongly dependent on the energy and roughness of the surface, respectively. Thus, fine-tuning the properties of the film may represent a strategy to optimize

  2. Starting to Gel: How Arabidopsis Seed Coat Epidermal Cells Produce Specialized Secondary Cell Walls

    PubMed Central

    Voiniciuc, Cătălin; Yang, Bo; Schmidt, Maximilian Heinrich-Wilhelm; Günl, Markus; Usadel, Björn

    2015-01-01

    For more than a decade, the Arabidopsis seed coat epidermis (SCE) has been used as a model system to study the synthesis, secretion and modification of cell wall polysaccharides, particularly pectin. Our detailed re-evaluation of available biochemical data highlights that Arabidopsis seed mucilage is more than just pectin. Typical secondary wall polymers such as xylans and heteromannans are also present in mucilage. Despite their low abundance, these components appear to play essential roles in controlling mucilage properties, and should be further investigated. We also provide a comprehensive community resource by re-assessing the mucilage phenotypes of almost 20 mutants using the same conditions. We conduct an in-depth functional evaluation of all the SCE genes described in the literature and propose a revised model for mucilage production. Further investigation of SCE cells will improve our understanding of plant cell walls. PMID:25658798

  3. 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

    SciTech Connect

    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.

  4. Single Wall Carbon Nanotube-polymer Solar Cells

    NASA Technical Reports Server (NTRS)

    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.

  5. Bacterial cell wall assembly: still an attractive antibacterial target.

    PubMed

    Bugg, Timothy D H; Braddick, Darren; Dowson, Christopher G; Roper, David I

    2011-04-01

    The development of new antibacterial agents to combat worsening antibiotic resistance is still a priority area in anti-infectives research, but in the post-genomic era it has been more difficult than expected to identify new lead compounds from high-throughput screening, and very challenging to obtain antibacterial activity for lead compounds. Bacterial cell-wall peptidoglycan biosynthesis is a well-established target for antibacterial chemotherapy, and recent developments enable the entire biosynthetic pathway to be reconstituted for detailed biochemical study and high-throughput inhibitor screening. This review article discusses recent developments in the availability of peptidoglycan biosynthetic intermediates, the identification of lead compounds for both the earlier cytoplasmic steps and the later lipid-linked steps, and the application of new methods such as structure-based drug design, phage display and surface science.

  6. Pectinous cell wall thickenings formation - A common defense strategy of plants to cope with Pb.

    PubMed

    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.

  7. Mechanisms for shaping, orienting, positioning and patterning plant secondary cell walls.

    PubMed

    Pesquet, Edouard; Korolev, Andrey V; Calder, Grant; Lloyd, Clive W

    2011-06-01

    Xylem vessels are cells that develop a specifically ornamented secondary cell wall to ensure their vascular function, conferring both structural strength and impermeability. Further plasticity is given to these vascular cells by a range of different patterns described by their secondary cell walls that-as for the growth of all plant organs-are developmentally regulated. Microtubules and their associated proteins, named MAPs, are essential to define the shape, the orientation, the position and the overall pattern of these secondary cell walls. Key actors in this process are the land-plant specific MAP70 proteins which not only allow the secondary cell wall to be positioned at the cell cortex but also determine the overall pattern described by xylem vessel secondary cell walls

  8. Plant cell walls throughout evolution: towards a molecular understanding of their design principles.

    PubMed

    Sarkar, Purbasha; Bosneaga, Elena; Auer, Manfred

    2009-01-01

    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.

  9. Detecting Cellulase Penetration Into Corn Stover Cell Walls by Immuno-Electron Microscopy

    SciTech Connect

    Donohoe, B. S.; Selig, M. J.; Viamajala, S.; Vinzant, T. B.; Adney, W. S.; Himmel, M. E.

    2009-06-15

    In general, pretreatments are designed to enhance the accessibility of cellulose to enzymes, allowing for more efficient conversion. In this study, we have detected the penetration of major cellulases present in a commercial enzyme preparation (Spezyme CP) into corn stem cell walls following mild-, moderate- and high-severity dilute sulfuric acid pretreatments. The Trichoderma reesei enzymes, Cel7A (CBH I) and Cel7B (EG I), as well as the cell wall matrix components xylan and lignin were visualized within digested corn stover cell walls by immuno transmission electron microscopy (TEM) using enzyme- and polymer-specific antibodies. Low severity dilute-acid pretreatment (20 min at 100 C) enabled <1% of the thickness of secondary cell walls to be penetrated by enzyme, moderate severity pretreatment at (20 min at 120 C) allowed the enzymes to penetrate {approx}20% of the cell wall, and the high severity (20 min pretreatment at 150 C) allowed 100% penetration of even the thickest cell walls. These data allow direct visualization of the dramatic effect dilute-acid pretreatment has on altering the condensed ultrastructure of biomass cell walls. Loosening of plant cell wall structure due to pretreatment and the subsequently improved access by cellulases has been hypothesized by the biomass conversion community for over two decades, and for the first time, this study provides direct visual evidence to verify this hypothesis. Further, the high-resolution enzyme penetration studies presented here provide insight into the mechanisms of cell wall deconstruction by cellulolytic enzymes.

  10. Plant cell walls throughout evolution: towards a molecular understanding of their design principles

    SciTech Connect

    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.

  11. Plasma-dependent chemotaxis of macrophages toward BCG cell walls and the mycobacterial glycolipid P3.

    PubMed

    Kelly, M T

    1977-01-01

    BCG cell walls, associated with oil droplets in the form of emulsions in saline, generate macrophage chemotactic activity from fresh guinea pig plasma. Serum and heat-inactivated plasma were inactive, suggesting involvement of complement or fibrinogen-derived chemotactic factors. Suspensions of cell walls and oil droplets each generated chemotactic activity from plasma, and the activity of the cell wall vaccine was due to the additive effects of these two components. A mycobacterial glycolipid (P3), which is a constituent of BCG cell walls, also had plasma-dependent chemotactic activity. The results suggest that macrophage chemotaxis may be an important part of the immunopotentiating activity of these mycobacterial products.

  12. Production of Bacteriolytic Enzymes by Streptomyces globisporus Regulated by Exogenous Bacterial Cell Walls

    PubMed Central

    Brönneke, Volker; Fiedler, Franz

    1994-01-01

    Mutanolysin biosynthesis and pigment production in Streptomyces globisporus ATCC 21553 were stimulated by adding bacterial cell walls to the medium. The increased bacteriolytic activity in the supernatant correlated with an increased de novo synthesis of mutanolysin and was between 4- and 20-fold higher than in cultures grown without bacterial cell walls. The increase in mutanolysin synthesis was brought about by enhanced transcription of the mutanolysin gene. The stimulation was only observed in medium which contained dextrin or starch as the carbon source. Glucose abolished the stimulation and also inhibited the low constitutive synthesis of mutanolysin. The induction of lytic activity was observed to require minimally 0.4 mg of bacterial cell walls per ml, whereas 0.6 mg of bacterial cell walls per ml yielded maximal lytic activity. Further supplements of bacterial cell walls did not result in enhanced lytic activity. The stimulation could be achieved independently of the phase of growth of the Streptomyces strain. Cultures grown in the presence of bacterial cell walls exhibited a higher growth yield. However, the accelerated growth was not the reason for the increased amount of mutanolysin produced. The growth of cultures with peptidoglycan monomers added to the medium instead of cell walls was similarly increased, but an effect on the biosynthesis of mutanolysin was not observed. All bacterial cell walls tested were capable of eliciting the stimulation of lytic activity, including cell walls of archaea, which contained pseudomurein. Images PMID:16349213

  13. Structure of the Cell Wall Anchor of Surface Proteins in Staphylococcus aureus

    NASA Astrophysics Data System (ADS)

    Schneewind, Olaf; Fowler, Audree; Faull, Kym F.

    1995-04-01

    Many surface proteins are anchored to the cell wall of Gram-positive bacteria and are involved in the pathogenesis of these organisms. A hybrid molecule was designed that, when expressed in Staphylococcus aureus, was anchored to the cell wall and could be released by controlled enzymatic digestion. By a combination of molecular biology and mass spectrometry techniques, the structure of the cell wall anchor of surface proteins in S. aureus was revealed. After cleavage of surface proteins between threonine and glycine of the conserved LPXTG motif, the carboxyl of threonine is amide-linked to the free amino group of the pentaglycine crossbridge in the staphylococcal cell wall.

  14. Wall extensibility: its nature, measurement and relationship to plant cell growth

    NASA Technical Reports Server (NTRS)

    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.

  15. DBIO Best Thesis Award: Mechanics, Dynamics, and Organization of the Bacterial Cytoskeleton and Cell Wall

    NASA Astrophysics Data System (ADS)

    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.

  16. [Hydroxyproline: Rich glycoproteins of the plant and cell wall]. Annual technical progress report, 1993

    SciTech Connect

    Varner, J.E.

    1993-06-01

    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.

  17. Vesicles between plasma membrane and cell wall prior to visible senescence of Iris and Dendrobium flowers.

    PubMed

    Kamdee, Channatika; Kirasak, Kanjana; Ketsa, Saichol; van Doorn, Wouter G

    2015-09-01

    Cut Iris flowers (Iris x hollandica, cv. Blue Magic) show visible senescence about two days after full opening. Epidermal cells of the outer tepals collapse due to programmed cell death (PCD). Transmission electron microscopy (TEM) showed irregular swelling of the cell walls, starting prior to cell collapse. Compared to cells in flowers that had just opened, wall thickness increased up to tenfold prior to cell death. Fibrils were visible in the swollen walls. After cell death very little of the cell wall remained. Prior to and during visible wall swelling, vesicles (paramural bodies) were observed between the plasma membrane and the cell walls. The vesicles were also found in groups and were accompanied by amorphous substance. They usually showed a single membrane, and had a variety of diameters and electron densities. Cut Dendrobium hybrid cv. Lucky Duan flowers exhibited visible senescence about 14 days after full flower opening. Paramural bodies were also found in Dendrobium tepal epidermis and mesophyll cells, related to wall swelling and degradation. Although alternative explanations are well possible, it is hypothesized that paramural bodies carry enzymes involved in cell wall breakdown. The literature has not yet reported such bodies in association with senescence/PCD.

  18. Characteristic Thickened Cell Walls of the Bracts of the ‘Eternal Flower’ Helichrysum bracteatum

    PubMed Central

    Nishikawa, Kuniko; Ito, Hiroaki; Awano, Tatsuya; Hosokawa, Munetaka; Yazawa, Susumu

    2008-01-01

    Background and Aims Helichrysum bracteatum is called an ‘eternal flower’ and has large, coloured, scarious bracts. These maintain their aesthetic value without wilting or discoloration for many years. There have been no research studies of cell death or cell morphology of the scarious bract, and hence the aim of this work was to elucidate these characteristics for the bract of H. bracteatum. Methods DAPI (4'6-diamidino-2-phenylindol dihydrochloride) staining and fluorescence microscopy were used for observation of cell nuclei. Light microscopy (LM), transmission electron microscopy (TEM) and polarized light microscopy were used for observation of cells, including cell wall morphology. Key Results Cell death occurred at the bract tip during the early stage of flower development. The cell wall was the most prominent characteristic of H. bracteatum bract cells. Characteristic thickened secondary cell walls on the inside of the primary cell walls were observed in both epidermal and inner cells. In addition, the walls of all cells exhibited birefringence. Characteristic thickened secondary cell walls have orientated cellulose microfibrils as well as general secondary cell walls of the tracheary elements. For comparison, these characters were not observed in the petal and bract tissues of Chrysanthemum morifolium. Conclusions Bracts at anthesis are composed of dead cells. Helichrysum bracteatum bracts have characteristic thickened secondary cell walls that have not been observed in the parenchyma of any other flowers or leaves. The cells of the H. bracteatum bract differ from other tissues with secondary cell walls, suggesting that they may be a new cell type. PMID:18436550

  19. Involvement of TBL/DUF231 proteins into cell wall biology

    PubMed Central

    Selbig, Joachim; Scheible, Wolf-Rüdiger

    2010-01-01

    Through map-based cloning we determined TRICHOME BIREFRINGENCE (TBR) belongs to a plant-specific, yet anonymous gene family with 46 members in Arabidopsis thaliana. These genes all encode the domain of unknown function 231 (DUF231). TBR and its homolog TRICHOME BIREFRINGENCE-LIKE3 (TBL3) are transcriptionally coordinated with CELLULOSE SYNTHASE (CESA) genes, and loss of TBR or TBL3 results in decreased levels of crystalline secondary wall cellulose in trichomes and stems, respectively. Loss of TBR or TBL3 further results in increased pectin methylesterase (PME) activity and reduced pectin esterification in etiolated Arabidopsis hypocotyls. Together, the results suggest that DUF231 proteins might function in the maintenance of pectin- and probably homogalacturonan esterification, and that this is a requirement for normal secondary wall cellulose synthesis, at least in some tissues and organs. Here we expand the discussion about the role of TBL/DUF231 proteins in cell wall biology based on sequence and structure analyses. Our analysis revealed structural similarities of TBR with a rhamnogalacturonan acetylesterase (RGAE) of Aspergillus aculeatus and the protein LUSTRIN A-LIKE (Oryza sativa). The implications of these findings in regard to TBL functions are discussed. PMID:20657172

  20. Involvement of TBL/DUF231 proteins into cell wall biology.

    PubMed

    Bischoff, Volker; Selbig, Joachim; Scheible, Wolf-Rüdiger

    2010-08-01

    Through map-based cloning we determined TRICHOME BIREFRINGENCE (TBR) to belong to a plant-specific, yet anonymous gene family with 46 members in Arabidopsis thaliana. These genes all encode the domain of unknown function 231 (DUF231). TBR and its homolog TRICHOME BIREFRINGENCE-LIKE3 (TBL3) are transcriptionally coordinated with CELLULOSE SYNTHASE (CESA) genes, and loss of TBR or TBL3 results in decreased levels of crystalline secondary wall cellulose in trichomes and stems, respectively. Loss of TBR or TBL3 further results in increased pectin methylesterase (PME) activity and reduced pectin esterification in etiolated Arabidopsis hypocotyls. Together, the results suggest that DUF231 proteins might function in the maintenance of pectin- and probably homogalacturonan esterification, and that this is a requirement for normal secondary wall cellulose synthesis, at least in some tissues and organs. Here we expand the discussion about the role of TBL/DUF231 proteins in cell wall biology based on sequence and structure analyses. Our analysis revealed structural similarities of TBR with a rhamnogalacturonan acetylesterase (RGAE) of Aspergillus aculeatus and the protein LUSTRIN A-LIKE (Oryza sativa). The implications of these findings in regard to TBL functions are discussed.

  1. Importance of the Candida albicans cell wall during commensalism and infection.

    PubMed

    Gow, Neil A R; Hube, Bernhard

    2012-08-01

    An imbalance of the normal microbial flora, breakage of epithelial barriers or dysfunction of the immune system favour the transition of the human pathogenic yeast Candida albicans from a commensal to a pathogen. C. albicans has evolved to be adapted as a commensal on mucosal surfaces. As a commensal it has also acquired attributes, which are necessary to avoid or overcome the host defence mechanisms. The human host has also co-evolved to recognize and eliminate potential fungal invaders. Many of the fungal genes that have been the focus of this co-evolutionary process encode cell wall components. In this review, we will discuss the transition from commensalism to pathogenesis, the key players of the fungal cell surface that are important for this transition, the role of the morphology and the mechanisms of host recognition and response.

  2. Changes in levels of cell wall constituents in wheat seedlings grown under continuous hypergravity conditions

    NASA Astrophysics Data System (ADS)

    Wakabayashi, K.; Soga, K.; Kamisaka, S.; Hoson, T.

    Effects of continuous hypergravity stimuli on the amounts and composition of cell wall constituents were investigated in wheat shoots. Hypergravity (300 g) treatment for three days after germination increased the net amount of cell wall polysaccharides such as hemicellulose and cellulose, but reduced the shoot elongation. As a result, the amount of cell wall polysaccharides per unit length of shoot increased under hypergravity. The hemicellulose fraction contained polysaccharides in the middle and low molecular mass range (5 kDa-1 MDa) and increased in response to hypergravity. Also, the amounts of arabinose (Ara) and xylose (Xyl), the major sugar components of the hemicellulose fraction, increased under hypergravity conditions. In addition to wall polysaccharides, hypergravity increased the amounts of cell wall-bound phenolic acids, such as ferulic acid (FA) and diferulic acid (DFA). Furthermore, the activity of phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) was enhanced under hypergravity conditions. These results suggest that continuous hypergravity stimulates the synthesis of cell wall constituents, especially hemicellulosic arabinoxylans and cell wall-bound FA and DFA in wheat shoots. The increased PAL activity may promote the formation of FA and DFA. These changes in cell wall architecture may be involved in making rigid and tough cell walls under hypergravity conditions and thereby contribute to the ability of plant to sustain their structures against gravitational stimuli.

  3. Mycobacterium tuberculosis CwsA overproduction modulates cell division and cell wall synthesis.

    PubMed

    Plocinski, P; Martinez, L; Sarva, K; Plocinska, R; Madiraju, M; Rajagopalan, M

    2013-12-01

    We recently showed that two small membrane proteins of Mycobacterium tuberculosis, CwsA and CrgA, interact with each other, and that loss of CwsA in M. smegmatis is associated with defects in the cell division and cell wall synthesis processes. Here we show that CwsA overproduction also affected growth, cell division and cell shape of M. smegmatis and M. tuberculosis. CwsA overproduction in M. tuberculosis led to increased sensitivity to cefsulodin, a penicillin-binding protein (PBP) 1A/1B targeting beta (β) -lactam, but was unaffected by other β-lactams and vancomycin. A M. smegmatis cwsA overexpressing strain showed bulgy cells, increased fluorescent vancomycin staining and altered localization of Wag31-mCherry fusion protein. However, the levels of phosphorylated Wag31, important for optimal peptidoglycan synthesis and growth in mycobacteria, were not affected. Interestingly, CwsA overproduction in E. coli led to the formation of large rounded cells that eventually lysed whereas the overproduction of FtsZ along with CwsA reversed this phenotype. Together, our results emphasize that optimal levels of CwsA are required for regulated cell wall synthesis, hence maintenance of cell shape, and that CwsA likely interacts with and modulates the activities of other cell wall synthetic components including PBPs.

  4. Transcription factors of M-phase cyclin CLB2 in the yeast cell wall integrity checkpoint.

    PubMed

    Sekiya, Mizuho; Nogami, Satoru; Ohya, Yoshikazu

    2009-08-01

    The cell wall integrity checkpoint coordinates cell wall synthesis and mitosis in the budding yeast, Saccharomyces cerevisiae. It has been reported that this checkpoint arrests the cell cycle at G2/M phase with repression of the M phase cyclin Clb2p at the transcriptional level, under perturbation of cell wall synthesis. We demonstrate that an override of this checkpoint with accumulation of CLB2 mRNA is induced when negative CLB2 transcription factors are deleted or when positive CLB2 transcription factors are overproduced in cell wall-defective cells. Our data imply that transcription factors for CLB2 are involved in the cell wall integrity checkpoint system and suggest that there are multiple regulation pathways of the checkpoint.

  5. Members of the Hsp70 family of proteins in the cell wall of Saccharomyces cerevisiae.

    PubMed Central

    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 implicated in translocation across the membrane and as molecular chaperones, and changes in the profile of cell wall proteins suggested that these proteins may have a similar role in the cell wall. PMID:8755907

  6. Suppression of the Lytic and Bactericidal Effects of Cell Wall-Inhibitory Antibiotics

    PubMed Central

    Lopez, Ruben; Ronda-Lain, Conchita; Tapia, Alfonso; Waks, Susan B.; Tomasz, Alexander

    1976-01-01

    The bacteriolytic effect of beta-lactam antibiotics on Bacillus subtilis and on Streptococcus pneumoniae was found to be a function of the pH; lysis was suppressed if the pH of the pneumococcal culture was below 6.0 during penicillin treatment. In the case of B. subtilis, growth at pH 6.6 prevented penicillin-induced lysis. In pneumococci, the addition of trypsin to the growth medium also protected against lysis. The pH-dependent protection phenomenon resembled in several respects the antibiotic “tolerance” of pneumococci with a defective autolytic system. (i) At the pH nonpermissive for lysis, the bacteria retained their normal sensitivity to beta-lactam and to other cell wall inhibitors; however, instead of lysis, the drug-treated bacteria simply stopped growing. Loss of viability of the cells was also greatly reduced. (ii) Protection against lysis was independent of the dose and chemical nature of the cell wall inhibitors. (iii) The protection effect was reversible; lysis and loss of viability could be triggered by a postincubation of the drug-treated bacteria at the pH permissive for lysis. PMID:10831

  7. Rab24 is required for normal cell division.

    PubMed

    Militello, Rodrigo D; Munafó, Daniela B; Berón, Walter; López, Luis A; Monier, Solange; Goud, Bruno; Colombo, María I

    2013-05-01

    Rab24 is an atypical member of the Rab GTPase family whose distribution in interphase cells has been characterized; however, its function remains largely unknown. In this study, we have analyzed the distribution of Rab24 throughout cell division. We have observed that Rab24 was located at the mitotic spindle in metaphase, at the midbody during telophase and in the furrow during cytokinesis. We have also observed partial co-localization of Rab24 and tubulin and demonstrated its association to microtubules. Interestingly, more than 90% of transiently transfected HeLa cells with Rab24 presented abnormal nuclear connections (i.e., chromatin bridges). Furthermore, in CHO cells stably transfected with GFP-Rab24wt, we observed a large percentage of binucleated and multinucleated cells. In addition, these cells presented an extremely large size and multiple failures in mitosis, as aberrant spindle formation (metaphase), delayed chromosomes (telophase) and multiple cytokinesis. A marked increase in binucleated, multinucleated and multilobulated nucleus formation was observed in HeLa cells depleted of Rab24. We also present evidence that a fraction of Rab24 associates with microtubules. In addition, Rab24 knock down resulted in misalignment of chromosomes and abnormal spindle formation in metaphase leading to the appearance of delayed chromosomes during late telophase and failures in cytokinesis. Our findings suggest that an adequate level of Rab24 is necessary for normal cell division. In summary, Rab24 modulates several mitotic events, including chromosome segregation and cytokinesis, perhaps through the interaction with microtubules.

  8. Transcription profiling using RNA-Seq demonstrates expression differences in the body walls of juvenile albino and normal sea cucumbers Apostichopus japonicus

    NASA Astrophysics Data System (ADS)

    Ma, Deyou; Yang, Hongsheng; Sun, Lina; Chen, Muyan

    2014-01-01

    Sea cucumbers Apostichopus japonicus are one of the most important aquaculture species in China. Their normal body color is black to fit their surroundings. Wild albinos are rare and hard to breed. To understand the differences between albino and normal (control) sea cucumbers at the transcriptional level, we sequenced the transcriptomes in their body-wall tissues using RNA-Seq high-throughput sequencing. Approximately 4.876 million (M) and 4.884 M 200-nucleotide-long cDNA reads were produced in the cDNA libraries derived from the body walls of albino and control samples, respectively. A total of 9 561 (46.89%) putative genes were identified from among the RNA-Seq reads in both libraries. After filtering, 837 significantly differentially regulated genes were identified in the albino library compared with in the control library, and 3.6% of the differentially expressed genes (DEGs) were found to have changed those more than five-fold. The expression levels of 10 DEGs were checked by real-time PCR and the results were in full accord with the RNA-Seq expression trends, although the amplitude of the differences in expression levels was lower in all cases. A series of pathways were significantly enriched for the DEGs. These pathways were closely related to phagocytosis, the complement and coagulation cascades, apoptosis-related diseases, cytokine-cytokine receptor interaction, and cell adhesion. The differences in gene expression and enriched pathways between the albino and control sea cucumbers offer control targets for cultivating excellent albino A. japonicus strains in the future.

  9. 9-Lipoxygenase-Derived Oxylipins Activate Brassinosteroid Signaling to Promote Cell Wall-Based Defense and Limit Pathogen Infection1

    PubMed Central

    Marcos, Ruth; Izquierdo, Yovanny; Vellosillo, Tamara; Kulasekaran, Satish; Cascón, Tomás; Hamberg, Mats; Castresana, Carmen

    2015-01-01

    The oxylipins, a large family of oxygenated lipid derivatives, regulate plant development and immunity. Two members of the 9-lipoxygenase (9-LOX) oxylipin pathway, 9-hydroxyoctadecatrienoic acid and 9-ketooctadecatrienoic acid, control root development and plant defense. Studies in Arabidopsis (Arabidopsis thaliana) using a series of 9-hydroxyoctadecatrienoic acid- and 9-ketooctadecatrienoic acid-insensitive nonresponding to oxylipins (noxy) mutants showed the importance of the cell wall as a 9-LOX-induced defense component and the participation of NOXY proteins in signaling cell wall damage. Here, we examined 9-LOX signaling using the mutants lox1lox5, which lacks 9-LOX activity, and noxy2-2, which shows oxylipin insensitivity and mitochondrial dysfunction. Mutants in brassinosteroids (BRs), a class of plant hormones necessary for normal plant growth and the control of cell wall integrity, were also analyzed. Several lines of evidence indicated that 9-LOX-derived oxylipins induce BR synthesis and signaling to activate cell wall-based responses such as callose deposition and that constitutive activation of BR signaling in bri1-EMS-suppressor 1-D (bes1-D) plants enhances this response. We found that constitutive BR signaling in bes1-D and brassinolide-resistant 1-1D (bzr1-1D) mutants conferred resistance to Pseudomonas syringae. bes1-D and bzr1-1D showed increased resistance to Golovinomyces cichoracearum, an obligate biotrophic fungus that penetrates the cell wall for successful infection, whereas susceptibility was enhanced in lox1lox5 and noxy2-2. Our results indicate a sequential action of 9-LOX and BR signaling in activating cell wall-based defense, and this response prevents pathogen infection. These results show interaction between the 9-LOX and BR pathways and help to clarify their role in modulating plant defense. PMID:26417008

  10. Traffic monitors at the cell periphery: the role of cell walls during early female reproductive cell differentiation in plants.

    PubMed

    Tucker, Matthew R; Koltunow, Anna M G

    2014-02-01

    The formation of female gametes in plants occurs within the ovule, a floral organ that is also the precursor of the seed. Unlike animals, plants lack a typical germline separated from the soma early in development and rely on positional signals, including phytohormones, mobile mRNAs and sRNAs, to direct diploid somatic precursor cells onto a reproductive program. In addition, signals moving between plant cells must overcome the architectural limitations of a cell wall which surrounds the plasma membrane. Recent studies have addressed the molecular and histological signatures of young ovule cells and indicate that dynamic cell wall changes occur over a short developmental window. These changes in cell wall properties impact signal flow and ovule cell identity, thereby aiding the establishment of boundaries between reproductive and somatic ovule domains.

  11. Two-dimensional simulation of red blood cell motion near a wall under a lateral force.

    PubMed

    Hariprasad, Daniel S; Secomb, Timothy W

    2014-11-01

    The motion of a red blood cell suspended in a linear shear flow adjacent to a fixed boundary subject to an applied lateral force directed toward the boundary is simulated. A two-dimensional model is used that represents the viscous and elastic properties of normal red blood cells. Shear rates in the range of 100 to 600 s^{-1} are considered, and the suspending medium viscosity is 1 cP. In the absence of a lateral force, the cell executes a tumbling motion. With increasing lateral force, a transition from tumbling to tank-treading is predicted. The minimum force required to ensure tank-treading increases nonlinearly with the shear rate. Transient swinging motions occur when the force is slightly larger than the transition value. The applied lateral force is balanced by a hydrodynamic lift force resulting from the positive orientation of the long axis of the cell with respect to the wall. In the case of cyclic tumbling motions, the orientation angle takes positive values through most of the cycle, resulting in lift generation. These results are used to predict the motion of a cell close to the outer edge of the cell-rich core region that is generated when blood flows in a narrow tube. In this case, the lateral force is generated by shear-induced dispersion, resulting from cell-cell interactions in a region with a concentration gradient. This force is estimated using previous data on shear-induced dispersion. The cell is predicted to execute tank-treading motions at normal physiological hematocrit levels, with the possibility of tumbling at lower hematocrit levels.

  12. Two-dimensional simulation of red blood cell motion near a wall under a lateral force

    PubMed Central

    Hariprasad, Daniel S.; Secomb, Timothy W.

    2015-01-01

    The motion of a red blood cell suspended in a linear shear flow adjacent to a fixed boundary subject to an applied lateral force directed towards the boundary is simulated. A two-dimensional model is used that represents the viscous and elastic properties of normal red blood cells. Shear rates in the range of 100 s−1 to 600 s−1 are considered, and the suspending medium viscosity is 1 cP. In the absence of a lateral force, the cell executes a tumbling motion. With increasing lateral force, a transition from tumbling to tank-treading is predicted. The minimum force required to ensure tank-treading increases non-linearly with the shear rate. Transient swinging motions occur when the force is slightly larger than the transition value. The applied lateral force is balanced by a hydrodynamic lift force resulting from the positive orientation of the long axis of the cell with respect to the wall. In the case of cyclic tumbling motions, the orientation angle takes positive values through most of the cycle, resulting in lift generation. These results are used to predict the motion of a cell close to the outer edge of the cell-rich core region that is generated when blood flows in a narrow tube. In this case, the lateral force is generated by shear-induced dispersion, resulting from cell-cell interactions in a region with a concentration gradient. This force is estimated using previous data on shear-induced dispersion. The cell is predicted to execute tank-treading motions at normal physiological hematocrit levels, with the possibility of tumbling at lower hematocrit levels. PMID:25493888

  13. Heteromannan and Heteroxylan Cell Wall Polysaccharides Display Different Dynamics During the Elongation and Secondary Cell Wall Deposition Phases of Cotton Fiber Cell Development

    PubMed Central

    Hernandez-Gomez, Mercedes C.; Runavot, Jean-Luc; Guo, Xiaoyuan; Bourot, Stéphane; Benians, Thomas A.S.; Willats, William G.T.; Meulewaeter, Frank; Knox, J. Paul

    2015-01-01

    The roles of non-cellulosic polysaccharides in cotton fiber development are poorly understood. Combining glycan microarrays and in situ analyses with monoclonal antibodies, polysaccharide linkage analyses and transcript profiling, the occurrence of heteromannan and heteroxylan polysaccharides and related genes in developing and mature cotton (Gossypium spp.) fibers has been determined. Comparative analyses on cotton fibers at selected days post-anthesis indicate different temporal and spatial regulation of heteromannan and heteroxylan during fiber development. The LM21 heteromannan epitope was more abundant during the fiber elongation phase and localized mainly in the primary cell wall. In contrast, the AX1 heteroxylan epitope occurred at the transition phase and during secondary cell wall deposition, and localized in both the primary and the secondary cell walls of the cotton fiber. These developmental dynamics were supported by transcript profiling of biosynthetic genes. Whereas our data suggest a role for heteromannan in fiber elongation, heteroxylan is likely to be involved in the regulation of cellulose deposition of secondary cell walls. In addition, the relative abundance of these epitopes during fiber development varied between cotton lines with contrasting fiber characteristics from four species (G. hirsutum, G. barbadense, G. arboreum and G. herbaceum), suggesting that these non-cellulosic polysaccharides may be involved in determining final fiber quality and suitability for industrial processing. PMID:26187898

  14. Protein diffusion in plant cell plasma membranes: the cell-wall corral

    PubMed Central

    Martinière, Alexandre; Runions, John

    2013-01-01

    Studying protein diffusion informs us about how proteins interact with their environment. Work on protein diffusion over the last several decades has illustrated the complex nature of biological lipid bilayers. The plasma membrane contains an array of membrane-spanning proteins or proteins with peripheral membrane associations. Maintenance of plasma membrane microstructure can be via physical features that provide intrinsic ordering such as lipid microdomains, or from membrane-associated structures such as the cytoskeleton. Recent evidence indicates, that in the case of plant cells, the cell wall seems to be a major player in maintaining plasma membrane microstructure. This interconnection / interaction between cell-wall and plasma membrane proteins most likely plays an important role in signal transduction, cell growth, and cell physiological responses to the environment. PMID:24381579

  15. Cell wall dynamics modulate acetic acid-induced apoptotic cell death of Saccharomyces cerevisiae

    PubMed Central

    Rego, António; Duarte, Ana M.; Azevedo, Flávio; Sousa, Maria J.; Côrte-Real, Manuela; Chaves, Susana R.

    2014-01-01

    Acetic acid triggers apoptotic cell death in Saccharomyces cerevisiae, similar to mammalian apoptosis. To uncover novel regulators of this process, we analyzed whether impairing MAPK signaling affected acetic acid-induced apoptosis and found the mating-pheromone response and, especially, the cell wall integrity pathways were the major mediators, especially the latter, which we characterized further. Screening downstream effectors of this pathway, namely targets of the transcription factor Rlm1p, highlighted decreased cell wall remodeling as particularly important for acetic acid resistance. Modulation of cell surface dynamics therefore emerges as a powerful strategy to increase acetic acid resistance, with potential application in industrial fermentations using yeast, and in biomedicine to exploit the higher sensitivity of colorectal carcinoma cells to apoptosis induced by acetate produced by intestinal propionibacteria. PMID:28357256

  16. Pathobiology of Pneumocystis pneumonia: life cycle, cell wall and cell signal transduction.

    PubMed

    Skalski, Joseph H; Kottom, Theodore J; Limper, Andrew H

    2015-09-01

    Pneumocystis is a genus of ascomycetous fungi that are highly morbid pathogens in immunosuppressed humans and other mammals. Pneumocystis cannot easily be propagated in culture, which has greatly hindered understanding of its pathobiology. The Pneumocystis life cycle is intimately associated with its mammalian host lung environment, and life cycle progression is dependent on complex interactions with host alveolar epithelial cells and the extracellular matrix. The Pneumocystis cell wall is a varied and dynamic structure containing a dominant major surface glycoprotein, β-glucans and chitins that are important for evasion of host defenses and stimulation of the host immune system. Understanding of Pneumocystis cell signaling pathways is incomplete, but much has been deduced by comparison of the Pneumocystis genome with homologous genes and proteins in related fungi. In this mini-review, the pathobiology of Pneumocystis is reviewed, with particular focus on the life cycle, cell wall components and cell signal transduction.

  17. Insolubilization of hydroxyproline-rich cell wall glycoprotein in aerated carrot root slices.

    PubMed

    Cooper, J B; Varner, J E

    1983-04-15

    The hydroxyproline-rich glycoprotein of plant cell walls is secreted from the cytoplasm as a soluble monomer which slowly becomes insolubilized. A tyrosine derivative, isodityrosine, is formed in the cell wall during this insolubilization and could serve as a protein-protein crosslink. Glycoprotein insolubilization is inhibited by peroxidase inhibitors and free radical scavengers, the most effective of which is L-ascorbate. These data support a hypothesis that the hydroxyproline-rich cell wall glycoprotein forms a covalently crosslinked wall network under the control of an extracellular peroxidase/ascorbate oxidase system.

  18. Cell-free layer and wall shear stress variation in microvessels.

    PubMed

    Yin, Xuewen; Zhang, Junfeng

    2012-01-01

    In this study, we simulated multiple red blood cells flowing through straight microvessels with the immersed-boundary lattice-Boltzmann model to examine the shear stress variation on the microvessel surface and its relation to the properties of cell-free layer. Significant variation in shear stress has been observed due to the irregular configuration of blood cells flowing near the microvessel wall. A low shear stress is typically found at locations where there is a cell flowing close to the wall, and a large shear stress at locations with a relatively wide gap between cell and wall. This relationship between the shear stress magnitude and the distance between cell and wall has been attributed to the reverse pressure difference developed between the front and rear sides of a cell flowing near the vessel wall. We further studied the effects of several hemodynamic factors on the variation of shear stress, including the cell deformability, the flow rate, and the aggregation among red blood cells. These simulations show that the shear stress variation is less profound in situations with wider cell-free layers, since the reverse pressure difference around the edge cells is less evident, and the influence of this pressure difference on wall shear stress becomes weaker. This study also demonstrates the complexity of the flow field in the gap between cell and wall. More precise experimental techniques are required accurately measure such shear stress variation in microcirculation.

  19. Cell Differentiation and Spatial Organization in Yeast Colonies: Role of Cell-Wall Integrity Pathway.

    PubMed

    Piccirillo, Sarah; Morales, Rita; White, Melissa G; Smith, Keston; Kapros, Tamas; Honigberg, Saul M

    2015-12-01

    Many microbial communities contain organized patterns of cell types, yet relatively little is known about the mechanism or function of this organization. In colonies of the budding yeast Saccharomyces cerevisiae, sporulation occurs in a highly organized pattern, with a top layer of sporulating cells sharply separated from an underlying layer of nonsporulating cells. A mutant screen identified the Mpk1 and Bck1 kinases of the cell-wall integrity (CWI) pathway as specifically required for sporulation in colonies. The CWI pathway was induced as colonies matured, and a target of this pathway, the Rlm1 transcription factor, was activated specifically in the nonsporulating cell layer, here termed feeder cells. Rlm1 stimulates permeabilization of feeder cells and promotes sporulation in an overlying cell layer through a cell-nonautonomous mechanism. The relative fraction of the colony apportioned to feeder cells depends on nutrient environment, potentially buffering sexual reproduction against suboptimal environments.

  20. Germ tube-specific antigens of Candida albicans cell walls

    SciTech Connect

    Sundstrom, P.R.

    1986-01-01

    Studies were performed to characterize the surface differences between blastospores and germ tubes of the pathogenic, dimorphic yeast, Candida albicans, and to identify components of yeast cells responsible for these differences. Investigation of surfaces differences of the two growth forms was facilitated by the production of rabbit antiserum prepared against Formalin-treated yeast possessing germ tubes. To prepare antiserum specific for germ tubes, this serum was adsorbed with stationary phase blastospores. Whereas the unadsorbed antiserum reacted with both blastospore and germ tube forms by immunofluorescence and Enzyme-Linked Immunosorbent Assay, the adsorbed antiserum did not react with blastospores but detected germ tube-specific antigens in hyphal forms. The differences between blastospores and germ tubes of Candida albicans, were further studied by comparing enzymatic digests of cell walls of both growth forms in radiolabeled organisms. Organisms were labeled either on the surface with /sup 125/I, or metabolically with (/sup 35/S) methionine or (/sup 3/H) mannose. Three-surface-located components (as shown by antibody adsorption and elution experiments) were precipitated from Zymolase digests. All three components were mannoproteins as shown by their ability to bind Concanavalin A, and to be labeled in protein labeling procedures, and two of these (200,000 and 155,000 molecular weight) were germ tube specific, as shown by their ability to be precipitated by germ tube-specific antiserum. Monoclonal antibodies were prepared to C. albicans, using blastospores bearing germ tubes as immunogen.

  1. Polysaccharide composition of unlignified cell walls of pineapple [Ananas comosus (L.) Merr.] fruit.

    PubMed Central

    Smith, B G; Harris, P J

    1995-01-01

    The polysaccharides of cell walls isolated from the fleshy, edible part of the fruit of the monocotyledon pineapple [Ananas comosus (L.) Merr.] (family Bromeliaceae) were analyzed chemically. These cell walls were derived mostly from parenchyma cells and were shown histochemically to be unlignified, but they contained ester-linked ferulic acid. The analyses indicated that the noncellulosic polysaccharide composition of the cell walls was intermediate between that of unlignified cell walls of species of the monocotyledon family Poaceae (grasses and cereals) and that of unlignified cell walls of dicotyledons. Glucuronoarabinoxylans were the major non-cellulosic polysaccharides in the pineapple cell walls. Xyloglucans were also present, together with small amounts of pectic polysaccharides and glucomannans (or galactoglucomannans). The large amounts of glucuronoarabinoxylans and small amounts of pectic polysaccharides resemble the noncellulosic polysaccharide composition of the unlignified cell walls of the Poaceae. However, the absence of (1-->3,1-->4)-beta-glucans, the presence of relatively large amounts of xyloglucans, and the possible structure of the xyloglucans resemble the noncellulosic polysaccharide composition of the unlignified cell walls of dicotyledons. PMID:7770529

  2. Cell wall as a target for bacteria inactivation by pulsed electric fields

    PubMed Central

    Pillet, Flavien; Formosa-Dague, Cécile; Baaziz, Houda; Dague, Etienne; Rols, Marie-Pierre

    2016-01-01

    The integrity and morphology of bacteria is sustained by the cell wall, the target of the main microbial inactivation processes. One promising approach to inactivation is based on the use of pulsed electric fields (PEF). The current dogma is that irreversible cell membrane electro-permeabilisation causes the death of the bacteria. However, the actual effect on the cell-wall architecture has been poorly explored. Here we combine atomic force microscopy and electron microscopy to study the cell-wall organization of living Bacillus pumilus bacteria at the nanoscale. For vegetative bacteria, exposure to PEF led to structural disorganization correlated with morphological and mechanical alterations of the cell wall. For spores, PEF exposure led to the partial destruction of coat protein nanostructures, associated with internal alterations of cortex and core. Our findings reveal for the first time that the cell wall and coat architecture are directly involved in the electro-eradication of bacteria. PMID:26830154

  3. Investigation of Hydrogen Storage in Single Walled Carbon Nanotubes for Fuel Cells-2

    DTIC Science & Technology

    2010-03-11

    1 Final Report Title: Investigation of hydrogen storage in Single Walled Carbon Nanotubes for fuel cells - 2 AFOSR/AOARD...SUBTITLE Investigation of hydrogen storage in single walled carbon nanotubes for fuel cells-2 5a. CONTRACT NUMBER FA23860914157 5b. GRANT NUMBER...SUPPLEMENTARY NOTES 14. ABSTRACT Single walled carbon nanotubes (SWCNTs) dispersed in 2-propanol are deposited on the alumina substrate using drop caste

  4. Miniature1-encoded cell wall invertase is essential for assembly and function of wall-in-growth in the maize endosperm transfer cell

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The miniature1 (mn1) seed phenotype in maize is due to a loss-of-function mutation at the Mn1 locus that encodes a cell wall invertase, INCW2, which localizes exclusively to the basal endosperm transfer cells (BETC) of developing seeds. A common feature of all transfer cells is the labyrinth-like wa...

  5. Composition and desiccation-induced alterations of the cell wall in the resurrection plant Craterostigma wilmsii.

    PubMed

    Vicré, Maïté; Lerouxel, Olivier; Farrant, Jill; Lerouge, Patrice; Driouich, Azeddine

    2004-02-01

    Resurrection plants have the unique capacity to revive from an air-dried state. In order to tolerate desiccation they have to overcome a number of stresses, mechanical stress being one. In leaves of the Craterostigma species, an extensive shrinkage occurs during drying as well as a considerable cell wall folding. Our previous microscopically analysis using immunocytochemistry on the resurrection plant Craterostigma wilmsii, has shown an increase in labelling of xyloglucan and unesterified pectins in the cell wall during drying. In this study, we have undertaken a biochemical approach to separate, quantify and characterize major cell wall polysaccharides in fully hydrated and dry leaves of C. wilmsii. Our results show that the overall cell wall composition of C. wilmsii leaves was similar to that of other dicotyledonous plants with respect to the pectin content. However, the structure of the hemicellulosic polysaccharide xyloglucan was characterized to be XXGG-type. The data also demonstrate marked changes in the hemicellulosic wall fraction from dry plants compared to hydrated ones. The most conspicuous change was a decrease in glucose content in the hemicellulosic fraction of dry plants. In addition, xyloglucan from the cell wall of dry leaves was relatively more substituted with galactose than in hydrated walls. Together these findings show that dehydration induces significant alteration of polysaccharide content and structure in the cell wall of C. wilmsii, which in turn might be involved in the modulation of the mechanical properties of the wall during dehydration.

  6. CELL WALL CARBOHYDRATE EPITOPES IN THE GREEN ALGA OEDOGONIUM BHARUCHAE F. MINOR (OEDOGONIALES, CHLOROPHYTA)(1).

    PubMed

    Estevez, José M; Leonardi, Patricia I; Alberghina, Josefina S

    2008-10-01

    Cell wall changes in vegetative and suffultory cells (SCs) and in oogonial structures from Oedogonium bharuchae N. D. Kamat f. minor Vélez were characterized using monoclonal antibodies against several carbohydrate epitopes. Vegetative cells and SCs develop only a primary cell wall (PCW), whereas mature oogonial cells secrete a second wall, the oogonium cell wall (OCW). Based on histochemical and immunolabeling results, (1→4)-β-glucans in the form of crystalline cellulose together with a variable degree of Me-esterified homogalacturonans (HGs) and hydroxyproline-rich glycoprotein (HRGP) epitopes were detected in the PCW. The OCW showed arabinosides of the extensin type and low levels of arabinogalactan-protein (AGP) glycans but lacked cellulose, at least in its crystalline form. Surprisingly, strong colabeling in the cytoplasm of mature oogonia cells with three different antibodies (LM-5, LM-6, and CCRC-M2) was found, suggesting the presence of rhamnogalacturonan I (RG-I)-like structures. Our results are discussed relating the possible functions of these cell wall epitopes with polysaccharides and O-glycoproteins during oogonium differentiation. This study represents the first attempt to characterize these two types of cell walls in O. bharuchae, comparing their similarities and differences with those from other green algae and land plants. This work represents a contribution to the understanding of how cell walls have evolved from simple few-celled to complex multicelled organisms.

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

    PubMed Central

    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

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

    DOE PAGES

    Berry, Elizabeth A.; Tran, Mai L.; Dimos, Christos S.; ...

    2016-03-08

    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 severalmore » 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.« less

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

    SciTech Connect

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

    2016-03-08

    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.

  10. Distinct cell wall architectures in seed endosperms in representatives of the Brassicaceae and Solanaceae.

    PubMed

    Lee, Kieran J D; Dekkers, Bas J W; Steinbrecher, Tina; Walsh, Cherie T; Bacic, Antony; Bentsink, Leónie; Leubner-Metzger, Gerhard; Knox, J Paul

    2012-11-01

    In some species, a crucial role has been demonstrated for the seed endosperm during germination. The endosperm has been shown to integrate environmental cues with hormonal networks that underpin dormancy and seed germination, a process that involves the action of cell wall remodeling enzymes (CWREs). Here, we examine the cell wall architectures of the endosperms of two related Brassicaceae, Arabidopsis (Arabidopsis thaliana) and the close relative Lepidium (Lepidium sativum), and that of the Solanaceous species, tobacco (Nicotiana tabacum). The Brassicaceae species have a similar cell wall architecture that is rich in pectic homogalacturonan, arabinan, and xyloglucan. Distinctive features of the tobacco endosperm that are absent in the Brassicaceae representatives are major tissue asymmetries in cell wall structural components that reflect the future site of radicle emergence and abundant heteromannan. Cell wall architecture of the micropylar endosperm of tobacco seeds has structural components similar to those seen in Arabidopsis and Lepidium endosperms. In situ and biomechanical analyses were used to study changes in endosperms during seed germination and suggest a role for mannan degradation in tobacco. In the case of the Brassicaceae representatives, the structurally homogeneous cell walls of the endosperm can be acted on by spatially regulated CWRE expression. Genetic manipulations of cell wall components present in the Arabidopsis seed endosperm demonstrate the impact of cell wall architectural changes on germination kinetics.

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

    PubMed

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

    2011-04-01

    European and Mediterranean corn borers are two of the most economically important insect pests of maize (Zea mays L.) in North America and southern Europe, respectively. Cell wall structure and composition were evaluated in pith and rind tissues of resistant and susceptible inbred lines as possible corn borer resistance traits. Composition of cell wall polysaccharides, lignin concentration and composition, and cell wall bound forms of hydroxycinnamic acids were measured. As expected, most of the cell wall components were found at higher concentrations in the rind than in the pith tissues, with the exception of galactose and total diferulate esters. Pith of resistant inbred lines had significantly higher concentrations of total cell wall material than susceptible inbred lines, indicating that the thickness of cell walls could be the initial barrier against corn borer larvae attack. Higher concentrations of cell wall xylose and 8-O-4-coupled diferulate were found in resistant inbreds. Stem tunneling by corn borers was negatively correlated with concentrations of total diferulates, 8-5-diferulate and p-coumarate esters. Higher total cell wall, xylose, and 8-coupled diferulates concentrations appear to be possible mechanisms of corn borer resistance.

  12. Ethanol yields and cell wall properties in divergently bred switchgrass genotypes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic modification of herbaceous plant cell walls to increase biofuels yields from harvested biomass is a primary bioenergy research goal. The focus of much of this research has been on cell wall lignin concentration. Using switchgrass genotypes developed by divergent breeding for ruminant diges...

  13. Analyses of extracellular carbohydrates in oomycetes unveil the existence of three different cell wall types.

    PubMed

    Mélida, Hugo; Sandoval-Sierra, Jose V; Diéguez-Uribeondo, Javier; Bulone, Vincent

    2013-02-01

    Some of the most devastating plant and animal pathogens belong to the oomycete class. The cell walls of these microorganisms represent an excellent target for disease control, but their carbohydrate composition is elusive. We have undertaken a detailed cell wall analysis in 10 species from 2 major oomycete orders, the Peronosporales and the Saprolegniales, thereby unveiling the existence of 3 clearly different cell wall types: type I is devoid of N-acetylglucosamine (GlcNAc) but contains glucuronic acid and mannose; type II contains up to 5% GlcNAc and residues indicative of cross-links between cellulose and 1,3-β-glucans; type III is characterized by the highest GlcNAc content (>5%) and the occurrence of unusual carbohydrates that consist of 1,6-linked GlcNAc residues. These 3 cell wall types are also distinguishable by their cellulose content and the fine structure of their 1,3-β-glucans. We propose a cell wall paradigm for oomycetes that can serve as a basis for the establishment of cell wall architectural models and the further identification of cell wall subtypes. This paradigm is complementary to morphological and molecular criteria for taxonomic grouping and provides useful information for unraveling poorly understood cell wall carbohydrate biosynthetic pathways through the identification and characterization of the corresponding enzymes.

  14. Comparison of stem morphology and anatomy of two alfalfa clonal lines exhibiting divergent cell wall composition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In previous research, two alfalfa clonal lines (252, 1283) were identified that exhibited environmentally stable differences in stem cell walls. Compared to stems of 1283, stems of 252 have a higher cell wall concentration and greater amounts of lignin and cellulose but reduced levels of pectic suga...

  15. De-esterified Pectins in the Cell Walls of Cotton Fiber: A Study of Fiber Mutants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the wild-type cotton (DP 5690), the cell walls of elongating cotton fibers are bilayered, with the outer layer enriched in de-esterified homogalacturonan (HGA), and an inner layer enriched in xyloglucans and cellulose. This bilayer is conspicuously absent in the cell walls of the ovule epidermal...

  16. Comparison of the Cell-Wall Composition of Morphologically Distinct Actinomycetes

    PubMed Central

    Yamaguchi, Tatsuro

    1965-01-01

    Yamaguchi, Tatsuro (The University of Tokyo, Tokyo, Japan). Comparison of the cell-wall composition of morphologically distinct actinomycetes. J. Bacteriol. 89:444–453. 1965.—Cell-wall composition of various morphologically distinct actinomycetes was studied to determine the relationship, if any, between cell-wall composition and morphological criteria in actinomycete taxonomy. The methods used were similar to those of Cummins and Harris. At least five types of cell-wall composition were obtained; however, these were not always correlated with groupings by the conventional classification system. For instance, the sporangium-forming actinomycetes, Actinoplanaceae, had three types of cell-wall composition; the composition of cell walls of Promicromonospora, Micromonospora, and Microbispora was the same as, or similar to, that of Actinomyces, Actinoplanes, and Streptosporangium, respectively; Chainia, Actinopycnidium, Actinosporangium, and Microellobosporia had the same cell-wall composition as Streptomyces, whereas that of Streptoverticillium was slightly different. Possible implications of cell-wall composition and morphological differentiation of hyphae for the taxonomy and phylogeny of actinomycetes are also discussed. PMID:14255713

  17. Tightly Bound Binary Toxin in the Cell Wall of Bacillus sphaericus

    PubMed Central

    Klein, Daniela; Uspensky, Igor; Braun, Sergei

    2002-01-01

    We have shown that urea-extracted cell wall of entomopathogenic Bacillus sphaericus 2297 and some other strains is a potent larvicide against Culex pipiens mosquitoes, with 50% lethal concentrations comparable to that of the well-known B. sphaericus binary toxin, with which it acts synergistically. The wall toxicity develops in B. sphaericus 2297 cultures during the late logarithmic stage, earlier than the appearance of the binary toxin crystal. It disappears with sporulation when the binary toxin activity reaches its peak. Disruption of the gene for the 42-kDa protein (P42) of the binary toxin abolishes both cell wall toxicity and crystal formation. However, the cell wall of B. sphaericus 2297, lacking P42, kills C. pipiens larvae when mixed with Escherichia coli cells expressing P42. Thus, the cell wall toxicity in strongly toxic B. sphaericus strains must be attributed to the presence in the cell wall of tightly bound 51-kDa (P51) and P42 binary toxin proteins. The synergism between binary toxin crystals and urea-treated cell wall preparations reflects suboptimal distribution of binary toxin subunits in both compartments. Binary toxin crystal is slightly deficient in P51, while cell wall is lacking in P42. PMID:12089007

  18. Tightly bound binary toxin in the cell wall of Bacillus sphaericus.

    PubMed

    Klein, Daniela; Uspensky, Igor; Braun, Sergei

    2002-07-01

    We have shown that urea-extracted cell wall of entomopathogenic Bacillus sphaericus 2297 and some other strains is a potent larvicide against Culex pipiens mosquitoes, with 50% lethal concentrations comparable to that of the well-known B. sphaericus binary toxin, with which it acts synergistically. The wall toxicity develops in B. sphaericus 2297 cultures during the late logarithmic stage, earlier than the appearance of the binary toxin crystal. It disappears with sporulation when the binary toxin activity reaches its peak. Disruption of the gene for the 42-kDa protein (P42) of the binary toxin abolishes both cell wall toxicity and crystal formation. However, the cell wall of B. sphaericus 2297, lacking P42, kills C. pipiens larvae when mixed with Escherichia coli cells expressing P42. Thus, the cell wall toxicity in strongly toxic B. sphaericus strains must be attributed to the presence in the cell wall of tightly bound 51-kDa (P51) and P42 binary toxin proteins. The synergism between binary toxin crystals and urea-treated cell wall preparations reflects suboptimal distribution of binary toxin subunits in both compartments. Binary toxin crystal is slightly deficient in P51, while cell wall is lacking in P42.

  19. A summary of staphylococcal C-terminal SH3b_5 cell wall binding domains.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Staphylococcal peptidoglycan hydrolases are a potential new source of antimicrobials. A large subset of these proteins contain a C-terminal SH3b_5 cell wall binding domain that has been shown for some to be essential for accurate cell wall recognition and subsequent staphylolytic activity, propert...

  20. Cell wall proteomics contributes to explore the functional proteins of Brachypodium distachyon grains.

    PubMed

    Fang, Xianping; Chen, Wenyue; Ma, Huasheng

    2015-07-01

    The plant cell wall is the first barrier in response to external stimuli and cell wall proteins (CWPs) can play an important role in the modulation of plant growth and development. In the past 10 years, the plant cell wall proteomics has increasingly become a very active research filed, which provides a broader understanding of CWPs for people. The cell wall proteome of Arabidopsis, rice, and other model plants has begun to take shape, and proteomic technology has become an effective way to identify the candidate functional CWPs in large scale. The challenging work of Francin-Allami et al. (Proteomics 2015, 15, 2296-2306) is a vital step toward building the most extensive cell wall proteome of a monocot species. They identified 299 cell wall proteins in Brachypodium distachyon grains, and also compared the grain cell wall proteome with those of B. distachyon culms and leaves, which provides a new perspective for further explaining the plant cell wall structures and remodeling mechanism.

  1. Analyses of Extracellular Carbohydrates in Oomycetes Unveil the Existence of Three Different Cell Wall Types

    PubMed Central

    Mélida, Hugo; Sandoval-Sierra, Jose V.; Diéguez-Uribeondo, Javier

    2013-01-01

    Some of the most devastating plant and animal pathogens belong to the oomycete class. The cell walls of these microorganisms represent an excellent target for disease control, but their carbohydrate composition is elusive. We have undertaken a detailed cell wall analysis in 10 species from 2 major oomycete orders, the Peronosporales and the Saprolegniales, thereby unveiling the existence of 3 clearly different cell wall types: type I is devoid of N-acetylglucosamine (GlcNAc) but contains glucuronic acid and mannose; type II contains up to 5% GlcNAc and residues indicative of cross-links between cellulose and 1,3-β-glucans; type III is characterized by the highest GlcNAc content (>5%) and the occurrence of unusual carbohydrates that consist of 1,6-linked GlcNAc residues. These 3 cell wall types are also distinguishable by their cellulose content and the fine structure of their 1,3-β-glucans. We propose a cell wall paradigm for oomycetes that can serve as a basis for the establishment of cell wall architectural models and the further identification of cell wall subtypes. This paradigm is complementary to morphological and molecular criteria for taxonomic grouping and provides useful information for unraveling poorly understood cell wall carbohydrate biosynthetic pathways through the identification and characterization of the corresponding enzymes. PMID:23204192

  2. Hypothesis of mitochondrial oncogenesis as the trigger of normal cells to cancer cells.

    PubMed

    Du, Jianping

    2014-06-01

    The Warburg Effect showed that energy metabolism of cancer cells was similar to prokaryotic cells, which were different from normal eucaryotic cells. The Endosymbiotic Theory offered a plausible explanation that the eucaryotic cells were evolved from prokaryotic cells, by which host cells (ancient prokaryotic cells) had ingested mitochondria (ancient aerobic bacteria), which depended on oxidative phosphorylation rather than glycolysis for generating energy. The alteration of energy metabolism might mean that the survival style of cancer cells were the re-evolution from eucaryotic cells to prokaryotic cells. But how this alteration happened was still unknown. This hypothesis tries to explain how mitochondria take part in the re-evolution from normal cell to cancer cell.

  3. Molecular biology of normal melanocytes and melanoma cells.

    PubMed

    Bandarchi, Bizhan; Jabbari, Cyrus Aleksandre; Vedadi, Ali; Navab, Roya

    2013-08-01

    Malignant melanoma is one of the most aggressive malignancies in humans and is responsible for 60-80% of deaths from skin cancers. The 5-year survival of patients with metastatic malignant melanoma is about 14%. Its incidence has been increasing in the white population over the past two decades. The mechanisms leading to malignant transformation of melanocytes and melanocytic lesions are poorly understood. In developing malignant melanoma, there is a complex interaction of environmental and endogenous (genetic) factors, including: dysregulation of cell proliferation, programmed cell death (apoptosis) and cell-to-cell interactions. The understanding of genetic alterations in signalling pathways of primary and metastatic malignant melanoma and their interactions may lead to therapeutics modalities, including targeted therapies, particularly in advanced melanomas that have high mortality rates and are often resistant to chemotherapy and radiotherapy. Our knowledge regarding the molecular biology of malignant melanoma has been expanding. Even though several genes involved in melanocyte development may also be associated with melanoma cell development, it is still unclear how a normal melanocyte becomes a melanoma cell. This article reviews the molecular events and recent findings associated with malignant melanoma.

  4. Mesenchymal precursor cells in the blood of normal individuals

    PubMed Central

    Zvaifler, Nathan J; Marinova-Mutafchieva, Lilla; Adams, Gill; Edwards, Christopher J; Moss, Jill; Burger, Jan A; Maini, Ravinder N

    2000-01-01

    Introduction: Adult human bone marrow contains a minority population of MSCs that contribute to the regeneration of tissues such as bone, cartilage, muscle, ligaments, tendons, fat, and stroma. Evidence that these MSCs are pluripotent, rather than being a mixture of committed progenitor cells each with a restricted potential, includes their rapid proliferation in culture, a characteristic morphology, the presence of typical marker proteins, and their consistent differentiation into various mesenchymal lineages. These attributes are maintained through multiple passages and are identifiable in individual stem cells. Aims: Since stem cells are present in both the bone marrow and other tissues, we thought it possible that cells with a similar appearance and pluripotent mesenchymal potential would be present in the blood. We applied techniques used successfully with marrow MSCs to identify similar cells in elutriation fractions of normal human blood. Methods: BMPCs were elutriated by diluting the buffy coats from 500 ml of anticoagulant-treated, platelet-depleted blood 1:4 in RPMI-1640 medium (RPMI) and layering 25-ml portions over 20 ml of Lymphoprep™. These samples were centrifuged at 2000 rpm for 20 min. The leukocyte-rich interface cells were collected, made up to 20 ml in RPMI, and separated by density-gradient centrifugation. The interface cells, now depleted of red blood cells, were collected, resuspended in 50 ml of sterile RMPI and 5% heat-inactivated FCS, and introduced into the sample line of the flow system of a Beckman JE-50 cell elutriator charged with elutriation buffer. The chamber was centrifuged at 25 000 rpm at 10°C and the flow rate adjusted to 12 ml/min. After about 150 ml had been collected, the flow rate was increased by 1 ml/min. Fractions nos. 1-6 (flow rates of 12-16 ml/min) contained most of the lymphocytes. Monocytes usually appeared in fractions 6 or 7 (as determined by flow cytometric analysis in a fluorescence-activated cell sorter

  5. Experimental approaches to study plant cell walls during plant-microbe interactions.

    PubMed

    Xia, Ye; Petti, Carloalberto; Williams, Mark A; DeBolt, Seth

    2014-01-01

    Plant cell walls provide physical strength, regulate the passage of bio-molecules, and act as the first barrier of defense against biotic and abiotic stress. In addition to providing structural integrity, plant cell walls serve an important function in connecting cells to their extracellular environment by sensing and transducing signals to activate cellular responses, such as those that occur during pathogen infection. This mini review will summarize current experimental approaches used to study cell wall functions during plant-pathogen interactions. Focus will be paid to cell imaging, spectroscopic analyses, and metabolic profiling techniques.

  6. The preparation of immunogenic cell walls from a highly protective strain of Clostridium chauvoei.

    PubMed

    Chandler, H M; Hamilton, R C

    1975-05-01

    Conventional methods for the preparation of cell walls of a highly protective strain of Clostridium chauvoei destroy the protective antigen. Bacteria were therefore lysed by the enzyme pronase instead of by the mechanical disintegration methods commonly employed. Final purification and separation of cell walls and membranes was achieved by equilibrium density-gradient centrifugation with sodium iodide in a zonal rotor. The resultant cell walls had a two-layered structure when seen in ultra-thin section and were highly immunogenic when used to immunize mice against challenge with C. chauvoei. Rabbit antisera raised against the cell walls provided passive protection against challenge in mice and the level of protection was not diminished by the absorption of all agglutinins from the sera. These results confirm previous observations that the protective antigen is a heatlabile cell wall antigen which stimulates the production of non-agglutinating protective antibody.

  7. Non-invasive imaging of cellulose microfibril orientation within plant cell walls by polarized Raman microspectroscopy.

    PubMed

    Sun, Lan; Singh, Seema; Joo, Michael; Vega-Sanchez, Miguel; Ronald, Pamela; Simmons, Blake A; Adams, Paul; Auer, Manfred

    2016-01-01

    Cellulose microfibrils represent the major scaffold of plant cell walls. Different packing and orientation of the microfibrils at the microscopic scale determines the macroscopic properties of cell walls and thus affect their functions with a profound effect on plant survival. We developed a polarized Raman microspectroscopic method to determine cellulose microfibril orientation within rice plant cell walls. Employing an array of point measurements as well as area imaging and subsequent Matlab-assisted data processing, we were able to characterize the distribution of cellulose microfibril orientation in terms of director angle and anisotropy magnitude. Using this approach we detected differences between wild type rice plants and the rice brittle culm mutant, which shows a more disordered cellulose microfibril arrangement, and differences between different tissues of a wild type rice plant. This novel non-invasive Raman imaging approach allows for quantitative assessment of cellulose fiber orientation in cell walls of herbaceous plants, an important advancement in cell wall characterization.

  8. Interactions between grape skin cell wall material and commercial enological tannins. Practical implications.

    PubMed

    Bautista-Ortín, Ana Belén; Cano-Lechuga, Mario; Ruiz-García, Yolanda; Gómez-Plaza, Encarna

    2014-01-01

    Commercial enological tannins were used to investigate the role that cell wall material plays in proanthocyanidin adsorption. Insoluble cell wall material, prepared from the skin of Vitis vinifera L. cv. Monastrell berries, was combined with solutions containing six different commercial enological tannins (proanthocyanidin-type tannins). Analysis of the proanthocyanidins in the solution, after fining with cell wall material, using phloroglucinolysis and size exclusion chromatography, provided quantitative and qualitative information on the non-adsorbed compounds. Cell wall material showed strong affinity for the proanthocyanidins, one of the commercial tannins being bound up to 61% in the experiment. Comparison of the molecular mass distribution of the commercial enological tannins in solution, before and after fining, suggested that cell walls affinity for proanthocyanidins was more related with the proanthocyanidin molecular mass than with their percentage of galloylation. These interactions may have some enological implications, especially as regards the time of commercial tannins addition to the must/wine.

  9. Dressed to impress: impact of environmental adaptation on the C andida albicans cell wall

    PubMed Central

    2015-01-01

    Summary C andida albicans is an opportunistic fungal pathogen of humans causing superficial mucosal infections and life‐threatening systemic disease. The fungal cell wall is the first point of contact between the invading pathogen and the host innate immune system. As a result, the polysaccharides that comprise the cell wall act as pathogen associated molecular patterns, which govern the host–pathogen interaction. The cell wall is dynamic and responsive to changes in the external environment. Therefore, the host environment plays a critical role in regulating the host–pathogen interaction through modulation of the fungal cell wall. This review focuses on how environmental adaptation modulates the cell wall structure and composition, and the subsequent impact this has on the innate immune recognition of C . albicans. PMID:25846717

  10. Variability of cell wall polysaccharides composition and hemicellulose enzymatic profile in an apple progeny.

    PubMed

    Galvez-Lopez, D; Laurens, F; Quéméner, B; Lahaye, M

    2011-12-01

    The genetic variability of apple cell walls polysaccharides chemical composition and structure was assessed in a progeny of 141 individuals harvested over 2 years. The variability of the hemicelluloses oligosaccharides released by glucanase was analyzed by MALDI-TOF MS. The genetic contribution was distinguished from harvest year as well as from parental crossing patterns and scab resistance selection. Results showed that harvest year had a major impact on cell wall polysaccharide composition and structure. Within each harvest, genetic effect impact more significantly cell wall polysaccharide chemistry than does reciprocal crossing or early scab selection. Uronic acids, glucose, galactose and xylose contents as well as some glucomannan and xyloglucan structures have a high heritability. This first cell wall chemotyping of an apple progeny opens the way for future searches of genetic markers for the chemical variability of cell wall polysaccharides.

  11. Measurements of cell wall mechanical properties using optically trapped fluorescent microspheres

    NASA Astrophysics Data System (ADS)

    Ermilov, Sergey; Qian, Feng; Murdock, David; Brownell, William E.; Anvari, Bahman

    2004-10-01

    Information on plasma membrane (PM) and cell wall mechanical properties is important for many biophysical applications, especially for those, which involve cells, undergoing significant mechanical stress (red blood cells, outer hair cells, fibrocytes, etc.). Optical tweezers is frequently used to study PM mechanics, particularly by pulling long PM tethers. One of the limitations on using optical tweezers to study cell wall mechanics is associated with transillumination technique of the trapped object position sensing, which prevents accurate mechanical testing in the proximity to the cell. In this work we use an optical tweezers in conjunction with a position-sensing system, which spectrally separates signals from the trapped fluorescent microsphere and imaging background. We have used this setup to study mechanics of the cell wall and PM separated from the underlying cytoskeleton on human embryonic kidney cells. We measured the force exerted by the cell on the trapped microsphere as a function of the cell wall displacement during the process of tether formation, and as a function of time during the process of tether growth and relaxation. Tethering force - cell wall displacement profiles have shown a behavior, implying that tether formation process starts with elastic deformation of the intact cell wall, followed by the plastic deformations and sliding of the PM over the underlying cytoskeleton, and ends with the local separation of a PM. Tethering force - cell wall displacement profiles have been used to estimate tether formation force, stiffness parameter of the cell wall and the works of tether formation, elastic and plastic deformations of the cell wall, related to the mechanical properties of a composite cell wall and cell wall - plasma membrane association strength. Temporal steady-state and relaxation tethering force profiles have been similar to the ones measured using transillumination position sensing, however average force values have been smaller in

  12. 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.

    PubMed

    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

  13. The Cell Wall Lipid PDIM Contributes to Phagosomal Escape and Host Cell Exit of Mycobacterium tuberculosis

    PubMed Central

    Quigley, Jeff; Hughitt, V. Keith; Velikovsky, Carlos A.; Mariuzza, Roy A.

    2017-01-01

    ABSTRACT The cell wall of Mycobacterium tuberculosis is composed of unique lipids that are important for pathogenesis. Indeed, the first-ever genetic screen in M. tuberculosis identified genes involved in the biosynthesis and transport of the cell wall lipid PDIM (phthiocerol dimycocerosates) as crucial for the survival of M. tuberculosis in mice. Here we show evidence for a novel molecular mechanism of the PDIM-mediated virulence in M. tuberculosis. We characterized the DNA interaction and the regulon of Rv3167c, a transcriptional repressor that is involved in virulence regulation of M. tuberculosis, and discovered that it controls the PDIM operon. A loss-of-function genetic approach showed that PDIM levels directly correlate with the capacity of M. tuberculosis to escape the phagosome and induce host cell necrosis and macroautophagy. In conclusion, our study attributes a novel role of the cell wall lipid PDIM in intracellular host cell modulation, which is important for host cell exit and dissemination of M. tuberculosis. PMID:28270579

  14. Cell envelope stress response in cell wall-deficient L-forms of Bacillus subtilis.

    PubMed

    Wolf, Diana; Domínguez-Cuevas, Patricia; Daniel, Richard A; Mascher, Thorsten

    2012-11-01

    L-forms are cell wall-deficient bacteria that can grow and proliferate in osmotically stabilizing media. Recently, a strain of the Gram-positive model bacterium Bacillus subtilis was constructed that allowed controlled switching between rod-shaped wild-type cells and corresponding L-forms. Both states can be stably maintained under suitable culture conditions. Because of the absence of a cell wall, L-forms are known to be insensitive to β-lactam antibiotics, but reports on the susceptibility of L-forms to other antibiotics that interfere with membrane-anchored steps of cell wall biosynthesis are sparse, conflicting, and strongly influenced by strain background and method of L-form generation. Here we investigated the response of B. subtilis to the presence of cell envelope antibiotics, with regard to both antibiotic resistance and the induction of the known LiaRS- and BceRS-dependent cell envelope stress biosensors. Our results show that B. subtilis L-forms are resistant to antibiotics that interfere with the bactoprenol cycle, such as bacitracin, vancomycin, and mersacidin, but are hypersensitive to nisin and daptomycin, which both affect membrane integrity. Moreover, we established a lacZ-based reporter gene assay for L-forms and provide evidence that LiaRS senses its inducers indirectly (damage sensing), while the Bce module detects its inducers directly (drug sensing).

  15. β-(1,3)-Glucan Unmasking in Some Candida albicans Mutants Correlates with Increases in Cell Wall Surface Roughness and Decreases in Cell Wall Elasticity.

    PubMed

    Hasim, Sahar; Allison, David P; Retterer, Scott T; Hopke, Alex; Wheeler, Robert T; Doktycz, Mitchel J; Reynolds, Todd B

    2017-01-01

    Candida albicans is among the most common human fungal pathogens, causing a broad range of infections, including life-threatening systemic infections. The cell wall of C. albicans is the interface between the fungus and the innate immune system. The cell wall is composed of an outer layer enriched in mannosylated glycoproteins (mannan) and an inner layer enriched in β-(1,3)-glucan and chitin. Detection of C. albicans by Dectin-1, a C-type signaling lectin specific for β-(1,3)-glucan, is important for the innate immune system to recognize systemic fungal infections. Increased exposure of β-(1,3)-glucan to the immune system occurs when the mannan layer is altered or removed in a process called unmasking. Nanoscale changes to the cell wall during unmasking were explored in live cells with atomic force microscopy (AFM). Two mutants, the cho1Δ/Δ and kre5Δ/Δ mutants, were selected as representatives that exhibit modest and strong unmasking, respectively. Comparisons of the cho1Δ/Δ and kre5Δ/Δ mutants to the wild type reveal morphological changes in their cell walls that correlate with decreases in cell wall elasticity. In addition, AFM tips functionalized with Dectin-1 revealed that the forces of binding of Dectin-1 to all of the strains were similar, but the frequency of binding was highest for the kre5Δ/Δ mutant, decreased for the cho1Δ/Δ mutant, and rare for the wild type. These data show that nanoscale changes in surface topology are correlated with increased Dectin-1 adhesion and decreased cell wall elasticity. AFM, using tips functionalized with immunologically relevant molecules, can map epitopes of the cell wall and increase our understanding of pathogen recognition by the immune system.

  16. Cotton fiber tips have diverse morphologies and show evidence of apical cell wall synthesis

    PubMed Central

    Stiff , Michael R.; Haigler, Candace H.

    2016-01-01

    Cotton fibers arise through highly anisotropic expansion of a single seed epidermal cell. We obtained evidence that apical cell wall synthesis occurs through examining the tips of young elongating Gossypium hirsutum (Gh) and G. barbadense (Gb) fibers. We characterized two tip types in Gh fiber (hemisphere and tapered), each with distinct apical diameter, central vacuole location, and distribution of cell wall components. The apex of Gh hemisphere tips was enriched in homogalacturonan epitopes, including a relatively high methyl-esterified form associated with cell wall pliability. Other wall components increased behind the apex including cellulose and the α-Fuc-(1,2)-β-Gal epitope predominantly found in xyloglucan. Gb fibers had only one narrow tip type featuring characters found in each Gh tip type. Pulse-labeling of cell wall glucans indicated wall synthesis at the apex of both Gh tip types and in distal zones. Living Gh hemisphere and Gb tips ruptured preferentially at the apex upon treatment with wall degrading enzymes, consistent with newly synthesized wall at the apex. Gh tapered tips ruptured either at the apex or distantly. Overall, the results reveal diverse cotton fiber tip morphologies and support primary wall synthesis occurring at the apex and discrete distal regions of the tip. PMID:27301434

  17. Differential recognition of plant cell walls by microbial xylan-specific carbohydrate-binding modules.

    PubMed

    McCartney, Lesley; Blake, Anthony W; Flint, James; Bolam, David N; Boraston, Alisdair B; Gilbert, Harry J; Knox, J Paul

    2006-03-21

    Glycoside hydrolases that degrade plant cell walls have complex molecular architectures in which one or more catalytic modules are appended to noncatalytic carbohydrate-binding modules (CBMs). CBMs promote binding to polysaccharides and potentiate enzymic hydrolysis. Although there are diverse sequence-based families of xylan-binding CBMs, these modules, in general, recognize both decorated and unsubstituted forms of the target polysaccharide, and thus the evolutionary rationale for this diversity is unclear. Using immunohistochemistry to interrogate the specificity of six xylan-binding CBMs for their target polysaccharides in cell walls has revealed considerable differences in the recognition of plant materials between these protein modules. Family 2b and 15 CBMs bind to xylan in secondary cell walls in a range of dicotyledon species, whereas family 4, 6, and 22 CBMs display a more limited capability to bind to secondary cell walls. A family 35 CBM, which displays more restricted ligand specificity against purified xylans than the other five protein modules, reveals a highly distinctive binding pattern to plant material including the recognition of primary cell walls of certain dicotyledons, a feature shared with CBM15. Differences in the specificity of the CBMs toward walls of wheat grain and maize coleoptiles were also evident. The variation in CBM specificity for ligands located in plant cell walls provides a biological rationale for the repertoire of structurally distinct xylan-binding CBMs present in nature, and points to the utility of these modules in probing the molecular architecture of cell walls.

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

    PubMed Central

    Mistou, Michel-Yves; Sutcliffe, Iain C.; van Sorge, Nina M.

    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 teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. PMID:26975195

  19. β-1,3-Glucans are components of brown seaweed (Phaeophyceae) cell walls.

    PubMed

    Raimundo, Sandra Cristina; Pattathil, Sivakumar; Eberhard, Stefan; Hahn, Michael G; Popper, Zoë A

    2017-03-01

    LAMP is a cell wall-directed monoclonal antibody (mAb) that recognizes a β-(1,3)-glucan epitope. It has primarily been used in the immunolocalization of callose in vascular plant cell wall research. It was generated against a brown seaweed storage polysaccharide, laminarin, although it has not often been applied in algal research. We conducted in vitro (glycome profiling of cell wall extracts) and in situ (immunolabeling of sections) studies on the brown seaweeds Fucus vesiculosus (Fucales) and Laminaria digitata (Laminariales). Although glycome profiling did not give a positive signal with the LAMP mAb, this antibody clearly detected the presence of the β-(1,3)-glucan in situ, showing that this epitope is a constituent of these brown algal cell walls. In F. vesiculosus, the β-(1,3)-glucan epitope was present throughout the cell walls in all thallus parts; in L. digitata, the epitope was restricted to the sieve plates of the conductive elements. The sieve plate walls also stained with aniline blue, a fluorochrome used as a probe for callose. Enzymatic digestion with an endo-β-(1,3)-glucanase removed the ability of the LAMP mAb to label the cell walls. Thus, β-(1,3)-glucans are structural polysaccharides of F. vesiculosus cell walls and are integral components of the sieve plates in these brown seaweeds, reminiscent of plant callose.

  20. Histology and cell wall biochemistry of stone cells in the physical defence of conifers against insects.

    PubMed

    Whitehill, Justin G A; Henderson, Hannah; Schuetz, Mathias; Skyba, Oleksandr; Yuen, Macaire Man Saint; King, John; Samuels, A Lacey; Mansfield, Shawn D; Bohlmann, Jörg

    2016-08-01

    Conifers possess an array of physical and chemical defences against stem-boring insects. Stone cells provide a physical defence associated with resistance against bark beetles and weevils. In Sitka spruce (Picea sitchensis), abundance of stone cells in the cortex of apical shoots is positively correlated with resistance to white pine weevil (Pissodes strobi). We identified histological, biochemical and molecular differences in the stone cell phenotype of weevil resistant (R) or susceptible (S) Sitka spruce genotypes. R trees displayed significantly higher quantities of cortical stone cells near the apical shoot node, the primary site for weevil feeding. Lignin, cellulose, xylan and mannan were the most abundant components of stone cell secondary walls, respectively. Lignin composition of stone cells isolated from R trees contained a higher percentage of G-lignin compared with S trees. Transcript profiling revealed higher transcript abundance in the R genotype of coumarate 3-hydroxylase, a key monolignol biosynthetic gene. Developing stone cells in current year apical shoots incorporated fluorescent-tagged monolignol into the secondary cell wall, while mature stone cells of previous year apical shoots did not. Stone cell development is an ephemeral process, and fortification of shoot tips in R trees is an effective strategy against insect feeding.

  1. RF Breakdown in Normal Conducting Single-Cell Structures

    SciTech Connect

    Dolgashev, V.A.; Nantista, C.D.; Tantawi, S.G.; Higashi, Y.; Higo, T.; /KEK, Tsukuba

    2006-02-22

    Operating accelerating gradient in normal conducting accelerating structures is often limited by rf breakdown. The limit depends on multiple parameters, including input rf power, rf circuit, cavity shape and material. Experimental and theoretical study of the effects of these parameters on the breakdown limit in full scale structures is difficult and costly. We use 11.4 GHz single-cell traveling wave and standing wave accelerating structures for experiments and modeling of rf breakdown behavior. These test structures are designed so that the electromagnetic fields in one cell mimic the fields in prototype multicell structures for the X-band linear collider. Fields elsewhere in the test structures are significantly lower than that of the single cell. The setup uses matched mode converters that launch the circular TM{sub 01} mode into short test structures. The test structures are connected to the mode launchers with vacuum rf flanges. This setup allows economic testing of different cell geometries, cell materials and preparation techniques with short turn-around time. Simple 2D geometry of the test structures simplifies modeling of the breakdown currents and their thermal effects.

  2. Human Normal Bronchial Epithelial Cells: A Novel In Vitro Cell Model for Toxicity Evaluation

    PubMed Central

    Huang, Haiyan; Xia, Bo; Liu, Hongya; Li, Jie; Lin, Shaolin; Li, Tiyuan; Liu, Jianjun; Li, Hui

    2015-01-01

    Human normal cell-based systems are needed for drug discovery and toxicity evaluation. hTERT or viral genes transduced human cells are currently widely used for these studies, while these cells exhibited abnormal differentiation potential or response to biological and chemical signals. In this study, we established human normal bronchial epithelial cells (HNBEC) using a defined primary epithelial cell culture medium without transduction of exogenous genes. This system may involve decreased IL-1 signaling and enhanced Wnt signaling in cells. Our data demonstrated that HNBEC exhibited a normal diploid karyotype. They formed well-defined spheres in matrigel 3D culture while cancer cells (HeLa) formed disorganized aggregates. HNBEC cells possessed a normal cellular response to DNA damage and did not induce tumor formation in vivo by xenograft assays. Importantly, we assessed the potential of these cells in toxicity evaluation of the common occupational toxicants that may affect human respiratory system. Our results demonstrated that HNBEC cells are more sensitive to exposure of 10~20 nm-sized SiO2, Cr(VI) and B(a)P compared to 16HBE cells (a SV40-immortalized human bronchial epithelial cells). This study provides a novel in vitro human cells-based model for toxicity evaluation, may also be facilitating studies in basic cell biology, cancer biology and drug discovery. PMID:25861018

  3. Reactive oxygen species and nitric oxide affect cell wall metabolism in tobacco BY-2 cells.

    PubMed

    Pacoda, Daniela; Montefusco, Anna; Piro, Gabriella; Dalessandro, Giuseppe

    2004-10-01

    The effects of hydrogen peroxide (H2O2), nitric oxide (NO), and a combination of both on the metabolism of cell wall polysaccharides were studied in tobacco (Nicotiana tabacum L.) cv Bright Yellow 2 (BY-2) suspension cultured cells in the presence of D-[U-14C]glucose or D-[U-14C]galactose as radioactive tracers. We found that the radiolabelling of newly synthesised total cell wall polysaccharides (pectins, hemicelluloses and alpha-cellulose), buffer-soluble polysaccharides, and membrane-associated polysaccharides decreased under the influence of exogenous systems generating H2O2 and NO. However, when the total amount of newly synthesised cell wall polysaccharides was calculated as a percentage of the total cellular radioactivity (ethanol-soluble pool plus the homogenate of ethanol-insoluble material), all treatments showed negligible effects in the presence of D-[U-14C]glucose or D-[U-14C]galactose as tracers. This occurred because the treatments generating H2O2, NO and H2O2 plus NO caused a marked decrease in the concentration of the ethanol-soluble pool as well as in the total radioactivity found in the homogenate of the ethanol-insoluble material. Most of the radioactivity taken up by the cells was evolved as 14CO2 during the respiratory processes. A qualitative and quantitative characterisation of the ethanol-soluble pool showed that radioactive UDP-sugars in BY-2 suspension cultured cells were differentially reduced by all treatments. Therefore, the decrease of the newly synthesised cell wall polysaccharides seems to be strictly dependent on the reduction of the UDP-sugars pool.

  4. Directed plant cell-wall accumulation of iron: Embedding co-catalyst for efficient biomass conversion

    SciTech Connect

    Lin, Chien -Yuan; Jakes, Joseph E.; Donohoe, Bryon S.; Ciesielski, Peter N.; Yang, Haibing; Gleber, Sophie -Charlotte; Vogt, Stefan; Ding, Shi -You; Peer, Wendy A.; Murphy, Angus S.; McCann, Maureen C.; Himmel, Michael E.; Tucker, Melvin P.; Wei, Hui

    2016-10-21

    Plant lignocellulosic biomass is an abundant, renewable feedstock for the production of biobased fuels and chemicals. Previously, we showed that iron can act as a co-catalyst to improve the deconstruction of lignocellulosic biomass. However, directly adding iron catalysts into biomass prior to pretreatment is diffusion limited, and increases the cost of biorefinery operations. Recently, we developed a new strategy for expressing iron-storage protein ferritin intracellularly to accumulate iron as a catalyst for the downstream deconstruction of lignocellulosic biomass. In this study, we extend this approach by fusing the heterologous ferritin gene with a signal peptide for secretion into Arabidopsis cell walls (referred to here as FerEX). The transgenic Arabidopsis plants. FerEX. accumulated iron under both normal and iron-fertilized growth conditions; under the latter (iron-fertilized) condition, FerEX transgenic plants showed an increase in plant height and dry weight by 12 and 18 %, respectively, compared with the empty vector control plants. The SDS- and native-PAGE separation of cell-wall protein extracts followed by Western blot analyses confirmed the extracellular expression of ferritin in FerEX plants. Meanwhile, Perls' Prussian blue staining and X-ray fluorescence microscopy (XFM) maps revealed iron depositions in both the secondary and compound middle lamellae cell-wall layers, as well as in some of the corner compound middle lamella in FerEX. Remarkably, their harvested biomasses showed enhanced pretreatability and digestibility, releasing, respectively, 21 % more glucose and 34 % more xylose than the empty vector control plants. These values are significantly higher than those of our recently obtained ferritin intracellularly expressed plants. This study demonstrated that extracellular expression of ferritin in Arabidopsis can produce plants with increased growth and iron accumulation, and reduced thermal and enzymatic recalcitrance. Here, the results are

  5. Single-Wall Carbon Nanotube Anodes for Lithium Cells

    NASA Technical Reports Server (NTRS)

    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.

  6. Modifications of Saccharomyces pastorianus cell wall polysaccharides with brewing process.

    PubMed

    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.

  7. Epithelial cell differentiation in normal and transgenic mouse intestinal isografts

    PubMed Central

    1991-01-01

    Transgenes consisting of segments of the rat liver fatty acid-binding protein (L-FABP) gene's 5' non-transcribed domain linked to the human growth hormone (hGH) gene (minus its regulatory elements) have provided useful tools for analyzing the mechanisms that regulate cellular and spatial differentiation of the continuously renewing gut epithelium. We have removed the jejunum from normal and transgenic fetal mice before or coincident with, cytodifferentiation of its epithelium. These segments were implanted into the subcutaneous tissues of young adult CBY/B6 nude mouse hosts to determine whether the bipolar, migration- dependent differentiation pathways of gut epithelial cells can be established and maintained in the absence of its normal luminal environment. Immunocytochemical analysis of isografts harvested 4-6 wk after implantation revealed that activation of the intact endogenous mouse L-FABP gene (fabpl) in differentiating enterocytes is perfectly recapitulated as these cells are translocated along the crypt-to-villus axis. Similarly, Paneth and goblet cells appear to appropriately differentiate as they migrate to the crypt base and villus tip, respectively. The enteroendocrine cell subpopulations present in intact 4-6-wk-old jejunum are represented in these isografts. Their precise spatial distribution along the crypt-to-villus axis mimics that seen in the intact gut. A number of complex interrelationships between enteroendocrine subpopulations are also recapitulated. In both "intact" and isografted jejunum, nucleotides -596 to +21 of the rat L-FABP gene were sufficient to direct efficient expression of the hGH reporter to enterocytes although precocious expression of the transgene occurred in cells located in the upper crypt, before their translocation to the villus base. Inappropriate expression of hGH occurred in a high percentage (greater than 80%) of secretin, gastrin, cholecystokinin, and gastric inhibitory peptide producing enteroendocrine cells present

  8. DEFECTIVE KERNEL1 (DEK1) Regulates Cell Walls in the Leaf Epidermis.

    PubMed

    Amanda, Dhika; Doblin, Monika S; Galletti, Roberta; Bacic, Antony; Ingram, Gwyneth C; Johnson, Kim L

    2016-12-01

    The plant epidermis is crucial to survival, regulating interactions with the environment and controlling plant growth. The phytocalpain DEFECTIVE KERNEL1 (DEK1) is a master regulator of epidermal differentiation and maintenance, acting upstream of epidermis-specific transcription factors, and is required for correct cell adhesion. It is currently unclear how changes in DEK1 lead to cellular defects in the epidermis and the pathways through which DEK1 acts. We have combined growth kinematic studies, cell wall analysis, and transcriptional analysis of genes downstream of DEK1 to determine the cause of phenotypic changes observed in DEK1-modulated lines of Arabidopsis (Arabidopsis thaliana). We reveal a novel role for DEK1 in the regulation of leaf epidermal cell wall structure. Lines with altered DEK1 activity have epidermis-specific changes in the thickness and polysaccharide composition of cell walls that likely underlie the loss of adhesion between epidermal cells in plants with reduced levels of DEK1 and changes in leaf shape and size in plants constitutively overexpressing the active CALPAIN domain of DEK1. Calpain-overexpressing plants also have increased levels of cellulose and pectins in epidermal cell walls, and this is correlated with the expression of several cell wall-related genes, linking transcriptional regulation downstream of DEK1 with cellular effects. These findings significantly advance our understanding of the role of the epidermal cell walls in growth regulation and establish a new role for DEK1 in pathways regulating epidermal cell wall deposition and remodeling.

  9. Phosphatase activity on the cell wall of Fonsecaea pedrosoi.

    PubMed

    Kneipp, L F; Palmeira, V F; Pinheiro, A A S; Alviano, C S; Rozental, S; Travassos, L R; Meyer-Fernandes, J R

    2003-12-01

    The activity of a phosphatase was characterized in intact mycelial forms of Fonsecaea pedrosoi, a pathogenic fungus that causes chromoblastomycosis. At pH 5.5, this fungus hydrolyzed p-nitrophenylphosphate (p-NPP) to p-nitrophenol (p-NP) at a rate of 12.78 +/- 0.53 nmol p-NP per h per mg hyphal dry weight. The values of Vmax and apparent Km for p-NPP hydrolyses were measured as 17.89 +/- 0.92 nmol p-NP per h per mg hyphal dry weight and 1.57 +/- 0.26 mmol/l, respectively. This activity was inhibited at increased pH, a finding compatible with an acid phosphatase. The enzymatic activity was strongly inhibited by classical inhibitors of acid phosphatases such as sodium orthovanadate (Ki = 4.23 micromol/l), sodium molybdate (Ki = 7.53 micromol/l) and sodium fluoride (Ki = 126.78 micromol/l) in a dose-dependent manner. Levamizole (1 mmol/l) and sodium tartrate (10 mmol/l), had no effect on the enzyme activity. Cytochemical localization of the acid phosphatase showed electrondense cerium phosphate deposits on the cell wall, as visualized by transmission electron microscopy. Phosphatase activity in F. pedrosoi seems to be associated with parasitism, as sclerotic cells, which are the fungal forms mainly detected in chromoblastomycosis lesions, showed much higher activities than conidia and mycelia did. A strain of F. pedrosoi recently isolated from a human case of chromoblastomycosis also showed increased enzyme activity, suggesting that the expression of surface phosphatases may be stimulated by interaction with the host.

  10. Endoplasmic reticulum-derived reactive oxygen species (ROS) is involved in toxicity of cell wall stress to Candida albicans.

    PubMed

    Yu, Qilin; Zhang, Bing; Li, Jianrong; Zhang, Biao; Wang, Honggang; Li, Mingchun

    2016-10-01

    The cell wall is an important cell structure in both fungi and bacteria, and hence becomes a common antimicrobial target. The cell wall-perturbing agents disrupt synthesis and function of cell wall components, leading to cell wall stress and consequent cell death. However, little is known about the detailed mechanisms by which cell wall stress renders fungal cell death. In this study, we found that ROS scavengers drastically attenuated the antifungal effect of cell wall-perturbing agents to the model fungal pathogen Candida albicans, and these agents caused remarkable ROS accumulation and activation of oxidative stress response (OSR) in this fungus. Interestingly, cell wall stress did not cause mitochondrial dysfunction and elevation of mitochondrial superoxide levels. Furthermore, the iron chelator 2,2'-bipyridyl (BIP) and the hydroxyl radical scavengers could not attenuate cell wall stress-caused growth inhibition and ROS accumulation. However, cell wall stress up-regulated expression of unfold protein response (UPR) genes, enhanced protein secretion and promoted protein folding-related oxidation of Ero1, an important source of ROS production. These results indicated that oxidation of Ero1 in the endoplasmic reticulum (ER), rather than mitochondrial electron transport and Fenton reaction, contributed to cell wall stress-related ROS accumulation and consequent growth inhibition. Our findings uncover a novel link between cell wall integrity (CWI), ER function and ROS production in fungal cells, and shed novel light on development of strategies promoting the antifungal efficacy of cell wall-perturbing agents against fungal infections.

  11. Wall Extensibility and Cell Hydraulic Conductivity Decrease in Enlarging Stem Tissues at Low Water Potentials 1

    PubMed Central

    Nonami, Hiroshi; Boyer, John S.

    1990-01-01

    Measurements with a guillotine psychrometer (H Nonami, JS Boyer [1990] Plant Physiol 94: 1601-1609) indicate that the inhibition of stem growth at low water potentials (low ψw) is accompanied by decreases in cell wall extensibility and tissue hydraulic conductance to water that eventually limit growth rate in soybean (Glycine max L. Merr.). To check this conclusion, we measured cell wall properties and cell hydraulic conductivities with independent techniques in soybean seedlings grown and treated the same way, i.e. grown in the dark and exposed to low ψw by transplanting dark grown seedlings to vermiculite of low water content. Wall properties were measured with an extensiometer modified for intact plants, and conductances were measured with a cell pressure probe in intact plants. Theory was developed to relate the wall measurements to those with the psychrometer. In the elongation zone, the plastic deformability of the walls decreased when measured with the extensiometer while growth was inhibited at low ψw. It increased during a modest growth recovery. This behavior was the same as that for the wall extensibility observed previously with the psychrometer. Tissue that was killed before measurement with the extensiometer also showed a similar response, indicating that changes in wall extensibility represented changes in wall physical properties and not rates of wall biosynthesis. The elastic compliance (reciprocal of bulk elastic modulus) did not change in the elongating or mature tissue. The hydraulic conductivity of cortical cells decreased in the elongating tissue and increased slightly during growth recovery in a response similar to that observed with the psychrometer. We conclude that the plastic properties of the cell walls and the conductance of the cells to water were decreased at low ψw but that the elastic properties of the walls were of little consequence in this response. PMID:16667664

  12. Transform-limited pulse generation in normal cavity dispersion erbium doped single-walled carbon nanotubes mode-locked fiber ring laser.

    PubMed

    Chernysheva, M A; Krylov, A A; Ogleznev, A A; Arutyunyan, N R; Pozharov, A S; Obraztsova, E D; Dianov, E M

    2012-10-08

    We demonstrate an erbium doped fiber ring laser mode-locked with a carboxymetylcellulose high-optical quality film with dispersed single-walled carbon nanotubes (SWCNT). The laser with large normal net cavity dispersion generates near bandwidth-limited picosecond inverse modified soliton pulses at 1.56 µm.

  13. A chimeric NST repressor has the potential to improve glucose productivity from plant cell walls.

    PubMed

    Iwase, Akira; Hideno, Akihiro; Watanabe, Keiji; Mitsuda, Nobutaka; Ohme-Takagi, Masaru

    2009-07-15

    Bioethanol might be produced more economically and with less ecological impact (with reduced exploitation of food crops) if we could increase the production of glucose from the cellulosic materials in plant cell walls. However, plant cell walls are relatively resistant to enzymatic and physicochemical hydrolysis and, therefore, it is necessary to develop methods for reducing such resistance. Changes in plant cell wall materials, by genetic engineering, that render them more easily hydrolyzable to glucose might be a valuable approach to this problem. We showed previously that, in Arabidopsis, NAC secondary wall thickening-promoting factor1 (NST1) and NST3 are key regulators of secondary wall formation. We report here that transgenic Arabidopsis plants that expressed a chimeric repressor derived from NST1 produced cell wall materials that were twice as susceptible to both enzymatic and physicochemical hydrolysis as those from wild-type plants. The yields of glucose from both fresh and dry biomass were increased in the chimeric repressor lines. Use of the NST1 chimeric repressor might enhance production of glucose from plant cell walls, by changing the nature of the cell walls themselves.

  14. Genetic modification of plant cell walls to enhance biomass yield and biofuel production in bioenergy crops.

    PubMed

    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.

  15. Mechanical Properties of Plant Cell Walls Probed by Relaxation Spectra1[W][OA

    PubMed Central

    Hansen, Steen Laugesen; Ray, Peter Martin; Karlsson, Anders Ola; Jørgensen, Bodil; Borkhardt, Bernhard; Petersen, Bent Larsen; Ulvskov, Peter

    2011-01-01

    Transformants and mutants with altered cell wall composition are expected to display a biomechanical phenotype due to the structural role of the cell wall. It is often quite difficult, however, to distinguish the mechanical behavior of a mutant's or transformant's cell walls from that of the wild 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, BayesRelax, 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 using tuber tissue from wild-type and transgenic potatoes (Solanum tuberosum) that differ in rhamnogalacturonan I side chain structure. PMID:21075961

  16. [Some effects of the neodymium ion on the cell wall structure of Staphyloccocus aruea].

    PubMed

    Huo, Guang Hua; Zhang, Dong Yan; Zhang, Tong

    2007-12-01

    The aim of this research is to study the effect of neodymium ion on the cell wall structure of Staphyloccocus aruea using transmission electron microscope, amino acid analyzer, infrared absorption spectrometry (IR). Experimental results show that Nd3+ can change the shape and the structure of the cell wall of Staphyloccocus aruea NdCl3 with lower concentration than the bacteriostatic concentration can help to synthesize the cell wall structure of Staphyloccocus aruea. Nd3+ with higher concentration than the bacteriostatic concentration can break the peptide bond and the hydrogen bond so as to break the net structure in the peptideoglycan cell.

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

    PubMed Central

    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