Thin film galvanic cell with RbAg4I5 solid electrolyte

International Nuclear Information System (INIS)

Bodnaruk, L.I.; Danilov, A.V.; Kulinkovich, V.E.; Aleskovskij, V.B.

1975-01-01

In order to decrease the size and weight and to increase the specific capacity and energy of galvanic cells, some solid electrolytes in the form of thin films are proposed. The galvanic cells were prepared by a combined method: the cathodic and anodic materials (Te and Ag) were evaporated under vacuo to cover an electrolyte layer, the latter being obtained by impregnating the porous materials with RbAg 4 I 5 acetonic solution. The most specific charge curves of the galvanic cells at various current densities are given: specific energy of the samples was 0.2 to 0.7 watt-h/kg, their capacity being 0.1 to 0.2 mah. Behaviour of the cells when stored (that of Ag(RbAg 4 I 5 ) interface in particular) was investigated, namely, the effect of the storage time on the capacity and internal resistance of the galvanic cell

RNAi mediated acute depletion of Retinoblastoma protein (pRb promotes aneuploidy in human primary cells via micronuclei formation

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Iovino Flora

2009-11-01

Full Text Available Abstract Background Changes in chromosome number or structure as well as supernumerary centrosomes and multipolar mitoses are commonly observed in human tumors. Thus, centrosome amplification and mitotic checkpoint dysfunctions are believed possible causes of chromosomal instability. The Retinoblastoma tumor suppressor (RB participates in the regulation of synchrony between DNA synthesis and centrosome duplication and it is involved in transcription regulation of some mitotic genes. Primary human fibroblasts were transfected transiently with short interfering RNA (siRNA specific for human pRb to investigate the effects of pRb acute loss on chromosomal stability. Results Acutely pRb-depleted fibroblasts showed altered expression of genes necessary for cell cycle progression, centrosome homeostasis, kinetochore and mitotic checkpoint proteins. Despite altered expression of genes involved in the Spindle Assembly Checkpoint (SAC the checkpoint seemed to function properly in pRb-depleted fibroblasts. In particular AURORA-A and PLK1 overexpression suggested that these two genes might have a role in the observed genomic instability. However, when they were post-transcriptionally silenced in pRb-depleted fibroblasts we did not observe reduction in the number of aneuploid cells. This finding suggests that overexpression of these two genes did not contribute to genomic instability triggered by RB acute loss although it affected cell proliferation. Acutely pRb-depleted human fibroblasts showed the presence of micronuclei containing whole chromosomes besides the presence of supernumerary centrosomes and aneuploidy. Conclusion Here we show for the first time that RB acute loss triggers centrosome amplification and aneuploidy in human primary fibroblasts. Altogether, our results suggest that pRb-depleted primary human fibroblasts possess an intact spindle checkpoint and that micronuclei, likely caused by mis-attached kinetochores that in turn trigger

Plant cell wall extensibility: connecting plant cell growth with cell wall structure, mechanics, and the action of wall-modifying enzymes

Energy Technology Data Exchange (ETDEWEB)

Cosgrove, Daniel J.

2015-11-25

The advent of user-friendly instruments for measuring force/deflection curves of plant surfaces at high spatial resolution has resulted in a recent outpouring of reports of the ‘Young's modulus’ of plant cell walls. The stimulus for these mechanical measurements comes from biomechanical models of morphogenesis of meristems and other tissues, as well as single cells, in which cell wall stress feeds back to regulate microtubule organization, auxin transport, cellulose deposition, and future growth directionality. In this article I review the differences between elastic modulus and wall extensibility in the context of cell growth. Some of the inherent complexities, assumptions, and potential pitfalls in the interpretation of indentation force/deflection curves are discussed. Reported values of elastic moduli from surface indentation measurements appear to be 10- to >1000-fold smaller than realistic tensile elastic moduli in the plane of plant cell walls. Potential reasons for this disparity are discussed, but further work is needed to make sense of the huge range in reported values. The significance of wall stress relaxation for growth is reviewed and connected to recent advances and remaining enigmas in our concepts of how cellulose, hemicellulose, and pectins are assembled to make an extensible cell wall. A comparison of the loosening action of α-expansin and Cel12A endoglucanase is used to illustrate two different ways in which cell walls may be made more extensible and the divergent effects on wall mechanics.

Regulation of cell wall biosynthesis.

Science.gov (United States)

Zhong, Ruiqin; Ye, Zheng-Hua

2007-12-01

Plant cell walls differ in their amount and composition among various cell types and even in different microdomains of the wall of a given cell. Plants must have evolved regulatory mechanisms controlling biosynthesis, targeted secretion, and assembly of wall components to achieve the heterogeneity in cell walls. A number of factors, including hormones, the cytoskeleton, glycosylphosphatidylinositol-anchored proteins, phosphoinositides, and sugar nucleotide supply, have been implicated in the regulation of cell wall biosynthesis or deposition. In the past two years, there have been important discoveries in transcriptional regulation of secondary wall biosynthesis. Several transcription factors in the NAC and MYB families have been shown to be the key switches for activation of secondary wall biosynthesis. These studies suggest a transcriptional network comprised of a hierarchy of transcription factors is involved in regulating secondary wall biosynthesis. Further investigation and integration of the regulatory players participating in the making of cell walls will certainly lead to our understanding of how wall amounts and composition are controlled in a given cell type. This may eventually allow custom design of plant cell walls on the basis of our needs.

Physical and Functional Interactions between ELL2 and RB in the Suppression of Prostate Cancer Cell Proliferation, Migration, and Invasion

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Xiaonan Qiu

2017-03-01

Full Text Available Elongation factor, RNA polymerase II, 2 (ELL2 is expressed and regulated by androgens in the prostate. ELL2 and ELL-associated factor 2 (EAF2 form a stable complex, and their orthologs in Caenorhabditis elegans appear to be functionally similar. In C. elegans, the EAF2 ortholog eaf-1 was reported to interact with the retinoblastoma (RB pathway to control development and fertility in worms. Because RB loss is frequent in prostate cancer, ELL2 interaction with RB might be important for prostate homeostasis. The present study explored physical and functional interaction of ELL2 with RB in prostate cancer. ELL2 expression in human prostate cancer specimens was detected using quantitative polymerase chain reaction coupled with laser capture microdissection. Co-immunoprecipitation coupled with deletion mutagenesis was used to determine ELL2 association with RB. Functional interaction between ELL2 and RB was tested using siRNA knockdown, BrdU incorporation, Transwell, and/or invasion assays in LNCaP, C4-2, and 22Rv1 prostate cancer cells. ELL2 expression was downregulated in high–Gleason score prostate cancer specimens. ELL2 could be bound and stabilized by RB, and this interaction was mediated through the N-terminus of ELL2 and the C-terminus of RB. Concurrent siRNA knockdown of ELL2 and RB enhanced cell proliferation, migration, and invasion as compared to knockdown of ELL2 or RB alone in prostate cancer cells. ELL2 and RB can interact physically and functionally to suppress prostate cancer progression.

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

Science.gov (United States)

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

Emerging differential roles of the pRb tumor suppressor in trichodysplasia spinulosa-associated polyomavirus and Merkel cell polyomavirus pathogeneses.

Science.gov (United States)

Wu, Julie H; Simonette, Rebecca A; Nguyen, Harrison P; Doan, Hung Q; Rady, Peter L; Tyring, Stephen K

2016-03-01

Merkel cell carcinoma (MCC) and trichodysplasia spinulosa (TS) are two proliferative cutaneous diseases caused by the Merkel cell polyomavirus (MCPyV) and trichodysplasia spinulosa-associated polyomavirus (TSPyV) respectively. Recently, studies have elucidated a key role of the small tumor (sT) antigen in the proliferative pathogenic mechanisms of MCPyV and likely TSPyV. While both sT antigens have demonstrated a capacity in regulating cellular pathways, it remains unknown whether MCPyV and TSPyV sT antigens contribute similarly or differentially to cell proliferation. The present study aims to explore the proliferative potential of MCPyV and TSPyV sT antigens by investigating their regulatory effects on the retinoblastoma protein (pRb) tumor suppressor. Inducible cell lines expressing MCPyV sT or TSPyV sT were created using a lentiviral packaging system. Cellular proteins were extracted and subjected to SDS-PAGE followed by Western blot detection and densitometric analysis. Expression of TSPyV sT markedly enhanced the phosphorylation of pRb in Western blot experiments. In contrast, expression of MCPyV sT did not alter pRb phosphorylation under the same experimental conditions. Densitometric analysis revealed that TSPyV sT antigen expression nearly doubled the ratio of phosphorylated to total pRb (P<0.001, Student's T-test), while MCPyV sT antigen expression did not cause significant change in pRb phosphorylation status. Given that hyperphosphorylation of pRb is associated with dysregulation of the cell cycle, S-phase induction, and increased cell proliferation, our findings support an important role of TSPyV-mediated pRb deactivation in the development of TS. The observation that the pRb tumor suppressor is inactivated by TSPyV sT but not MCPyV sT provides further insights into the distinct pathobiological mechanisms of MCC and TS. Copyright © 2016 Elsevier B.V. All rights reserved.

In vitro Rb-1 gene transfer to retinoblastoma cell lines

International Nuclear Information System (INIS)

Choi, Sang Wook; Ham, Yong Hoh; Kim, Mee Heui

1994-04-01

After transfection of Rb-vector to packaging cell line (CRIP) by Ca-P precipitation method, we could select nineteen colonies of G-418 resistant clone by ring cloning. Each colony was transduced to NIH3T3 cells to select the one which produces high titer virus. After NIH3T3 cells transduction, we could get 28 colony counts for the high, 127 for the middle, and 6 for the low viral titer. With the supernatant of the high viral titer colony (CRIPRb 2-5). We transduct retinoblastoma cell lines. 5 figs, 11 refs. (Author)

Plant cell wall polysaccharide analysis during cell elongation

DEFF Research Database (Denmark)

Guo, Xiaoyuan

Plant cell walls are complex structures whose composition and architecture are important to various cellular activities. Plant cell elongation requires a high level of rearrangement of the cell wall polymers to enable cell expansion. However, the cell wall polysaccharides dynamics during plant cell...... elongation is poorly understood. This PhD project aims to elucidate the cell wall compositional and structural change during cell elongation by using Comprehensive Microarray Polymer Profiling (CoMPP), microscopic techniques and molecular modifications of cell wall polysaccharide. Developing cotton fibre......, pea and Arabidopsis thaliana were selected as research models to investigate different types of cell elongation, developmental elongation and tropism elongation. A set of comprehensive analysis covering 4 cotton species and 11 time points suggests that non-cellulosic polysaccharides contribute...

Phospho-Rb mediating cell cycle reentry induces early apoptosis following oxygen-glucose deprivation in rat cortical neurons.

Science.gov (United States)

Yu, Ying; Ren, Qing-Guo; Zhang, Zhao-Hui; Zhou, Ke; Yu, Zhi-Yuan; Luo, Xiang; Wang, Wei

2012-03-01

The aim of this study was to investigate the relationship between cell cycle reentry and apoptosis in cultured cortical neurons following oxygen-glucose deprivation (OGD). We found that the percentage of neurons with BrdU uptake, TUNEL staining, and colocalized BrdU uptake and TUNEL staining was increased relative to control 6, 12 and 24 h after 1 h of OGD. The number of neurons with colocalized BrdU and TUNEL staining was decreased relative to the number of TUNEL-positive neurons at 24 h. The expression of phosphorylated retinoblastoma protein (phospho-Rb) was significantly increased 6, 12 and 24 h after OGD, parallel with the changes in BrdU uptake. Phospho-Rb and TUNEL staining were colocalized in neurons 6 and 12 h after OGD. This colocalization was strikingly decreased 24 h after OGD. Treatment with the cyclin-dependent kinase inhibitor roscovitine (100 μM) decreased the expression of phospho-Rb and reduced neuronal apoptosis in vitro. These results demonstrated that attempted cell cycle reentry with phosphorylation of Rb induce early apoptosis in neurons after OGD and there must be other mechanisms involved in the later stages of neuronal apoptosis besides cell cycle reentry. Phosphoralated Rb may be an important factor which closely associates aberrant cell cycle reentry with the early stages of neuronal apoptosis following ischemia/hypoxia in vitro, and pharmacological interventions for neuroprotection may be useful directed at this keypoint.

Deficiency of G1 regulators P53, P21Cip1 and/or pRb decreases hepatocyte sensitivity to TGFβ cell cycle arrest

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Harrison David J

2007-11-01

Full Text Available Abstract Background TGFβ is critical to control hepatocyte proliferation by inducing G1-growth arrest through multiple pathways leading to inhibition of E2F transcription activity. The retinoblastoma protein pRb is a key controller of E2F activity and G1/S transition which can be inhibited in viral hepatitis. It is not known whether the impairment of pRb would alter the growth inhibitory potential of TGFβ in disease. We asked how Rb-deficiency would affect responses to TGFβ-induced cell cycle arrest. Results Primary hepatocytes isolated from Rb-floxed mice were infected with an adenovirus expressing CRE-recombinase to delete the Rb gene. In control cells treatment with TGFβ prevented cells to enter S phase via decreased cMYC activity, activation of P16INK4A and P21Cip and reduction of E2F activity. In Rb-null hepatocytes, cMYC activity decreased slightly but P16INK4A was not activated and the great majority of cells continued cycling. Rb is therefore central to TGFβ-induced cell cycle arrest in hepatocytes. However some Rb-null hepatocytes remained sensitive to TGFβ-induced cell cycle arrest. As these hepatocytes expressed very high levels of P21Cip1 and P53 we investigated whether these proteins regulate pRb-independent signaling to cell cycle arrest by evaluating the consequences of disruption of p53 and p21Cip1. Hepatocytes deficient in p53 or p21Cip1 showed diminished growth inhibition by TGFβ. Double deficiency had a similar impact showing that in cells containing functional pRb; P21Cip and P53 work through the same pathway to regulate G1/S in response to TGFβ. In Rb-deficient cells however, p53 but not p21Cip deficiency had an additive effect highlighting a pRb-independent-P53-dependent effector pathway of inhibition of E2F activity. Conclusion The present results show that otherwise genetically normal hepatocytes with disabled p53, p21Cip1 or Rb genes respond less well to the antiproliferative effects of TGFβ. As the function of

Reconstitution of a secondary cell wall in a secondary cell wall-deficient Arabidopsis mutant.

Science.gov (United States)

Sakamoto, Shingo; Mitsuda, Nobutaka

2015-02-01

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. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-05-31

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

Emission characteristics of Xe-RbBr plasma

Science.gov (United States)

Heneral, A. A.; Avtaeva, S. V.

2017-12-01

The luminescence spectra of the longitudinal pulsed-periodic discharge in Xe-RbBr gas-vapour mixtures at low pressures are experimentally studied. Conditions for obtaining strong UV radiation of XeBr* exiplex molecules in the spectral range of 200-425 nm are found. The greatest output of the XeBr* UV radiation is provided at temperature of the gas-discharge tube walls of ~1000 K. The maximum UV emission power of the whole plasma volume is 4.8 W. Formation of XeBr* exciplex molecules in the pulsed-periodic discharge in Xe-RbBr gas-vapour mixtures at low pressures is discussed.

Heritable factors for radiation-induced osteosarcoma and the role of Rb1 in telomere maintenance in mesenchymal stem cells

International Nuclear Information System (INIS)

Rosemann, M.; Gonzalez-Vasconcellos, I.; Atkinson, M. J.

2013-01-01

Full text: Secondary tumors following a pediatric radiotherapy become an ever growing concern, a side effect of the improved therapeutic success leading to extended life span of the patients. Osteosarcoma (OS) and other soft-tissue sarcomas arise over proportionally frequent in the radiation field of former radiooncology patients. In an effort to map and identify inherited factors that govern individual susceptibility for these secondary, therapy associated tumors, we developed a mouse model that after injection of 227 thorium develops high numbers of OS and facilitates whole genome mapping of genetic variants that modify risk. We could identify genetic risk factors on 5 different chromosomes, that by independent segregation in the germline can interact in an additive manner and in combination alter the individual risk more than 3 fold. Using additional in-vitro studies and mouse knockout technology we could confirm that the responsible gene on the principal susceptibility locus is Rb1. Mice with a bone-specific Rb1+/- status exhibits increased bone tumor risk following irradiation. We have shown recently that the Rb1 tumor suppressor gene does not only regulates the cell cycle kinetics of mammalian cells, but that in normal osteoblasts is also crucial to protect telomeres from extensive erosion. An Rb1+/- deficiency therefore exhibit accelerated telomeric loss and, following ionising irradiation an excess of chromosomal defects. In the majority of secondary RT associated human OS, Rb1 was affected by allelic loss, whereas spontaneous human OS with no known radiation etiology show only 15%-20% Rb1 losses. It is assumed that the target cells for malignant transformation leading to OS are not the differentiating osteoblasts, but rather the long-term repopulating and pluripotent mesenchymal stem cells (MSC). These normal tissue stem cells are assumed to maintain a high degree of genome stability throughout the entire life span of an organism. One of the key factors

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

Science.gov (United States)

Huberman, Lori B; Murray, Andrew W

2014-01-01

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

A Model for Cell Wall Dissolution in Mating Yeast Cells: Polarized Secretion and Restricted Diffusion of Cell Wall Remodeling Enzymes Induces Local Dissolution

Science.gov (United States)

Huberman, Lori B.; Murray, Andrew W.

2014-01-01

Mating of the budding yeast, Saccharomyces cerevisiae, occurs when two haploid cells of opposite mating types signal using reciprocal pheromones and receptors, grow towards each other, and fuse to form a single diploid cell. To fuse, both cells dissolve their cell walls at the point of contact. This event must be carefully controlled because the osmotic pressure differential between the cytoplasm and extracellular environment causes cells with unprotected plasma membranes to lyse. If the cell wall-degrading enzymes diffuse through the cell wall, their concentration would rise when two cells touched each other, such as when two pheromone-stimulated cells adhere to each other via mating agglutinins. At the surfaces that touch, the enzymes must diffuse laterally through the wall before they can escape into the medium, increasing the time the enzymes spend in the cell wall, and thus raising their concentration at the point of attachment and restricting cell wall dissolution to points where cells touch each other. We tested this hypothesis by studying pheromone treated cells confined between two solid, impermeable surfaces. This confinement increases the frequency of pheromone-induced cell death, and this effect is diminished by reducing the osmotic pressure difference across the cell wall or by deleting putative cell wall glucanases and other genes necessary for efficient cell wall fusion. Our results support the model that pheromone-induced cell death is the result of a contact-driven increase in the local concentration of cell wall remodeling enzymes and suggest that this process plays an important role in regulating cell wall dissolution and fusion in mating cells. PMID:25329559

Isolation of the Cell Wall.

Science.gov (United States)

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.

Human biodistribution and radiation dosimetry of 82Rb.

Science.gov (United States)

Senthamizhchelvan, Srinivasan; Bravo, Paco E; Esaias, Caroline; Lodge, Martin A; Merrill, Jennifer; Hobbs, Robert F; Sgouros, George; Bengel, Frank M

2010-10-01

Prior estimates of radiation-absorbed doses from (82)Rb, a frequently used PET perfusion tracer, yielded discrepant results. We reevaluated (82)Rb dosimetry using human in vivo biokinetic measurements. Ten healthy volunteers underwent dynamic PET/CT (6 contiguous table positions, each with separate (82)Rb infusion). Source organ volumes of interest were delineated on the CT images and transferred to the PET images to obtain time-integrated activity coefficients. Radiation doses were estimated using OLINDA/EXM 1.0. The highest mean absorbed organ doses (μGy/MBq) were observed for the kidneys (5.81), heart wall (3.86), and lungs (2.96). Mean effective doses were 1.11 ± 0.22 and 1.26 ± 0.20 μSv/MBq using the tissue-weighting factors of the International Commission on Radiological Protection (ICRP), publications 60 and 103, respectively. Our current (82)Rb dosimetry suggests reasonably low radiation exposure. On the basis of this study, a clinical (82)Rb injection of 2 × 1,480 MBq (80 mCi) would result in a mean effective dose of 3.7 mSv using the weighting factors of the ICRP 103-only slightly above the average annual natural background exposure in the United States (3.1 mSv).

The Role of Auxin in Cell Wall Expansion.

Science.gov (United States)

Majda, Mateusz; Robert, Stéphanie

2018-03-22

Plant cells are surrounded by cell walls, which are dynamic structures displaying a strictly regulated balance between rigidity and flexibility. Walls are fairly rigid to provide support and protection, but also extensible, to allow cell growth, which is triggered by a high intracellular turgor pressure. Wall properties regulate the differential growth of the cell, resulting in a diversity of cell sizes and shapes. The plant hormone auxin is well known to stimulate cell elongation via increasing wall extensibility. Auxin participates in the regulation of cell wall properties by inducing wall loosening. Here, we review what is known on cell wall property regulation by auxin. We focus particularly on the auxin role during cell expansion linked directly to cell wall modifications. We also analyze downstream targets of transcriptional auxin signaling, which are related to the cell wall and could be linked to acid growth and the action of wall-loosening proteins. All together, this update elucidates the connection between hormonal signaling and cell wall synthesis and deposition.

The cell wall of Fusarium oxysporum

NARCIS (Netherlands)

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

1999-01-01

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

Bacillus subtilis as a platform for molecular characterisation of regulatory mechanisms of Enterococcus faecalis resistance against cell wall antibiotics.

Science.gov (United States)

Fang, Chong; Stiegeler, Emanuel; Cook, Gregory M; Mascher, Thorsten; Gebhard, Susanne

2014-01-01

To combat antibiotic resistance of Enterococcus faecalis, a better understanding of the molecular mechanisms, particularly of antibiotic detection, signal transduction and gene regulation is needed. Because molecular studies in this bacterium can be challenging, we aimed at exploiting the genetically highly tractable Gram-positive model organism Bacillus subtilis as a heterologous host. Two fundamentally different regulators of E. faecalis resistance against cell wall antibiotics, the bacitracin sensor BcrR and the vancomycin-sensing two-component system VanSB-VanRB, were produced in B. subtilis and their functions were monitored using target promoters fused to reporter genes (lacZ and luxABCDE). The bacitracin resistance system BcrR-BcrAB of E. faecalis was fully functional in B. subtilis, both regarding regulation of bcrAB expression and resistance mediated by the transporter BcrAB. Removal of intrinsic bacitracin resistance of B. subtilis increased the sensitivity of the system. The lacZ and luxABCDE reporters were found to both offer sensitive detection of promoter induction on solid media, which is useful for screening of large mutant libraries. The VanSB-VanRB system displayed a gradual dose-response behaviour to vancomycin, but only when produced at low levels in the cell. Taken together, our data show that B. subtilis is a well-suited host for the molecular characterization of regulatory systems controlling resistance against cell wall active compounds in E. faecalis. Importantly, B. subtilis facilitates the careful adjustment of expression levels and genetic background required for full functionality of the introduced regulators.

Characterization of the Sclerotinia sclerotiorum cell wall proteome.

Science.gov (United States)

Liu, Longzhou; Free, Stephen J

2016-08-01

We used a proteomic analysis to identify cell wall proteins released from Sclerotinia sclerotiorum hyphal and sclerotial cell walls via a trifluoromethanesulfonic acid (TFMS) digestion. Cell walls from hyphae grown in Vogel's glucose medium (a synthetic medium lacking plant materials), from hyphae grown in potato dextrose broth and from sclerotia produced on potato dextrose agar were used in the analysis. Under the conditions used, TFMS digests the glycosidic linkages in the cell walls to release intact cell wall proteins. The analysis identified 24 glycosylphosphatidylinositol (GPI)-anchored cell wall proteins and 30 non-GPI-anchored cell wall proteins. We found that the cell walls contained an array of cell wall biosynthetic enzymes similar to those found in the cell walls of other fungi. When comparing the proteins in hyphal cell walls grown in potato dextrose broth with those in hyphal cell walls grown in the absence of plant material, it was found that a core group of cell wall biosynthetic proteins and some proteins associated with pathogenicity (secreted cellulases, pectin lyases, glucosidases and proteases) were expressed in both types of hyphae. The hyphae grown in potato dextrose broth contained a number of additional proteins (laccases, oxalate decarboxylase, peroxidase, polysaccharide deacetylase and several proteins unique to Sclerotinia and Botrytis) that might facilitate growth on a plant host. A comparison of the proteins in the sclerotial cell wall with the proteins in the hyphal cell wall demonstrated that sclerotia formation is not marked by a major shift in the composition of cell wall protein. We found that the S. sclerotiorum cell walls contained 11 cell wall proteins that were encoded only in Sclerotinia and Botrytis genomes. © 2015 The Authors. Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd.

Effect of etoposide-induced alteration of the Mdm2-Rb signaling pathway on cellular senescence in A549 lung adenocarcinoma cells.

Science.gov (United States)

Dai, Wenjing; Jiang, Yi; Chen, Kairong; Qiu, Jing; Sun, Jian; Zhang, Wei; Zhou, Xiafei; Huang, Na; Li, Yunhui; Li, Wancheng

2017-10-01

The present study aimed to investigate the effect of various concentrations of etoposide (VP-16) on the E3 ubiquitin-protein ligase Mdm2 (Mdm2)-retinoblastoma (Rb) signaling pathway in the cellular senescence of A549 lung adenocarcinoma cells. A549 cells were randomly divided into the following four groups: Control group (no treatment), group 1 (1 µmol/l VP-16), group 2 (5 µmol/l VP-16) and group 3 (25 µmol/l VP-16). Each group was cultured for 48 h after treatment prior to observation of the alterations to cellular morphology. The cell cycle distribution of each group was also detected by flow cytometry. In addition, the activity of cellular senescence-associated β-galactosidase, and the expression of Mdm2 and phosphorylated (p-) Rb protein, was measured. The percentage of senescent cells was significantly higher following VP-16 treatment compared with the control group. The percentage of G 1 phase cells, and p-Rb protein and Mdm2 protein expression were also significantly different following VP-16 treatment compared with the control group. VP-16 increased the activity of β-galactosidase in the A459 cells. VP-16 also decreased the expression level of Mdm2 and p-Rb protein and inhibited cell cycle progression in G 1 . These results indicate that VP-16 induces the cellular senescence of A549 cells via the Mdm2-Rb signaling pathway. However, further investigations are required to validate the mechanisms underlying these effects of VP-16.

Cell wall mannoprotein of Candida albicans induces cell cycle alternation and inhibits apoptosis of HaCaT cells via NF-κB signal pathway.

Science.gov (United States)

Han, Yang; Jiang, Hang-Hang; Zhang, Yu-Jing; Hao, Xing-Jia; Sun, Yu-Zhe; Qi, Rui-Qun; Chen, Hong-Duo; Gao, Xing-Hua

2017-10-01

Candida albicans (C. albicans) is a commensal organism in human and a well-known dimorphic opportunistic pathogenic fungus. Though plenty of researches on the pathogenesis of C. albicans have been performed, the mechanism is not fully understood. The cell wall components of C. albicans have been documented to play important roles in its pathogenic processes. To further study the infectious mechanism of C. albicans, we investigated the potential functional role of its cell wall mannoprotein in cell cycle and apoptosis of HaCaT cells. We found that mannoprotein could promote the transition of cell cycle from G1/G0 to S phase, in which Cyclin D1, CDK4 and p-Rb, the major regulators of the cell cycle progression, showed significant upregulation, and CDKN1A (cyclin dependent kinase inhibitor 1A (p21)) showed significant downregulation. Mannoprotein also could inhibit apoptosis of HaCaT cells, which was well associated with increased expression of BCL2 (Bcl-2). Moreover, mannoprotein could increase the phosphorylation levels of RELA (p65) and NFKBIA (IκBα), as the key factors of NF-κB signal pathway in HaCaT cells, suggesting the activation of NF-κB signal pathway. Additionally, a NF-κB specific inhibitor, PDTC, could rescue the effect of mannoprotein on cell cycle and apoptosis of HaCaT cells, which suggested that mannoprotein could activate NF-κB signal pathway to mediate cell cycle alternation and inhibit apoptosis. Copyright © 2017. Published by Elsevier Ltd.

Functional duality of the cell wall.

Science.gov (United States)

Latgé, Jean-Paul; Beauvais, Anne

2014-08-01

The polysaccharide cell wall is the extracellular armour of the fungal cell. Although essential in the protection of the fungal cell against aggressive external stresses, the biosynthesis of the polysaccharide core is poorly understood. For a long time it was considered that this cell wall skeleton was a fixed structure whose role was only to be sensed as non-self by the host and consequently trigger the defence response. It is now known that the cell wall polysaccharide composition and localization continuously change to adapt to their environment and that these modifications help the fungus to escape from the immune system. Moreover, cell wall polysaccharides could function as true virulence factors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Diurnal Periodicity in the Supply of Cell Wall Components during Wood Cell Wall Formation

OpenAIRE

細尾, 佳宏

2012-01-01

This review summarizes recent studies on the diurnal periodicity in wood cell wall formation, with a major focus on those that we have conducted. Differences in the innermost surface of developing secondary walls of differentiating conifer tracheids can be seen from day to night Cellulose microfibrils are clearly evident during the day, and amorphous material containing abundant hemicelluloses is prevalent at night. These findings suggest a diurnal periodicity in the supply of cell wall compo...

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

Directory of Open Access Journals (Sweden)

Canut Hervé

2006-05-01

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

Prognostic implications of molecular and immunohistochemical profiles of the Rb and p53 cell cycle regulatory pathways in primary non-small cell lung carcinoma.

LENUS (Irish Health Repository)

Burke, Louise

2012-02-03

PURPOSE: Many studies have highlighted the aberrant expression and prognostic significance of individual proteins in either the Rb (particularly cyclin D1, p16INK4A, and pRb) or the p53 (p53 and p21Waf1) pathways in non-small cell lung cancer. We hypothesize that cumulative abnormalities within each and between these pathways would have significant prognostic potential regarding survival. EXPERIMENTAL DESIGN: Our study population consisted of 106 consecutive surgically resected cases of predominantly early-stage non-small cell lung cancer from the National Cancer Institute-Mayo Clinic series, and assessment of proteins involved both immunohistochemical (cyclin D1, p21Waf1, pRb, p16INK4A, and p53) and mutational analysis (p53) in relationship to staging and survival. RESULTS: Cyclin D1 overexpression was noted in 48% of the tumors, p16INK4A negative in 53%, pRb negative in 17%, p53 immunopositive in 50%, p53 mutation frequency in 48%, and p21(Waf1) overexpression in 47%, none with prognostic significance. Cyclin D1 overexpression in pRb-negative tumors revealed a significantly worse prognosis with a mean survival of 2.3 years (P = 0.004). A simultaneous p53 mutation dramatically reduced the mean survival time to 0.9 years (P = 0.007). Cyclin D1 overexpression with either a p53 mutation or a p53 overexpression was also associated with a significantly poorer prognosis (P = 0.0033 and 0.0063, respectively). CONCLUSIONS: Some cumulative abnormalities in the Rb and p53 pathways (e.g., cyclin D1 overexpression and p53 mutations) significantly cooperate to predict a poor prognosis; however, the complexity of the cell cycle protein interaction in any given tumor warrants caution in interpreting survival results when specific protein abnormalities are taken in isolation.

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

Science.gov (United States)

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

Deregulation of the RB pathway in human testicular germ cell tumours

DEFF Research Database (Denmark)

Bartkova, Jirina; Lukas, Claudia; Sørensen, Claus S

2003-01-01

Deregulation of the RB pathway is shared by most human malignancies. Components upstream of the retinoblastoma tumour suppressor (pRB), namely the INK4 family of cyclin-dependent kinase (CDK) inhibitors, the D-type cyclins, their partner kinases CDK4/CDK6, and pRB as their critical substrate...

Cell wall heterogeneity in root development of Arabidopsis

Directory of Open Access Journals (Sweden)

Marc Somssich

2016-08-01

Full Text Available 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 signalling 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-modelling to developmental stages of root cells, and dissect how root cell walls respond to certain environmental changes.

Alterations of 86Rb+ fluxes in poliovirus-infected HeLa cells and their dependence on virus replication

International Nuclear Information System (INIS)

Schaefer, A.; Geck, P.; Zibirre, R.; Kuehne, J.; Koch, G.

1984-01-01

Components of the 86Rb+ influx were investigated subsequent to poliovirus infection in the presence and absence of guanidine-HCl, both under normal steady-state conditions and after Na+ preloading of the cells. Measurements of the ouabain-sensitive 86Rb+ uptake indicated a biphasic change in the activity of the Na+, K+ pump in the course of virus infection: a transient increase in the second hour postinfection, that was detectable only after Na+ preloading and inhibition after 3 hr. The enhanced activity of the Na+, K+ pump was not affected, while the decrease later was fully prevented by the antiviral agent guanidine-HCl. The piretanide-sensitive 86Rb+ uptake due to the Na+, K+, 2 Cl- cotransport system also became strongly inhibited beginning in the second hour postinfection. The inhibition of this transport system was partially antagonized by guanidine-HCl. The remaining 86Rb+ influx in the presence of ouabain and piretanide increased in the third hour postinfection. The latter change in 86Rb+ influx, indicating an increased permeability to monovalent cations was completely abolished by guanidine-HCl

The RB/E2F pathway and regulation of RNA processing

Energy Technology Data Exchange (ETDEWEB)

Ahlander, Joseph [Department of Molecular and Cellular Biology, 1007 East Lowell Street, University of Arizona, Tucson, AZ 85721 (United States); Bosco, Giovanni, E-mail: gbosco@email.arizona.edu [Department of Molecular and Cellular Biology, 1007 East Lowell Street, University of Arizona, Tucson, AZ 85721 (United States)

2009-07-03

The retinoblastoma tumor suppressor protein (RB) is inactivated in a majority of cancers. RB restricts cell proliferation by inhibiting the E2F family of transcription factors. The current model for RB/E2F function describes its role in regulating transcription at gene promoters. Whether the RB or E2F proteins might play a role in gene expression beyond transcription initiation is not well known. This review describes evidence that points to a novel role for the RB/E2F network in the regulation of RNA processing, and we propose a model as a framework for future research. The elucidation of a novel role of RB in RNA processing will have a profound impact on our understanding of the role of this tumor suppressor family in cell and developmental biology.

Fluorescence of RbH and RbD formed by irradiating the mixed gases Rb + H2 and Rb + D2 with laser light

International Nuclear Information System (INIS)

Kato, Hajime; Toyosaka, Yukiko; Suzuki, Tomonari

1985-01-01

When a mixture of 85 Rb, 85 Rb 2 , and D 2 was irradiated by laser light at 5145 or 4880 A, small visible particles appeared and the fluorescence spectra were observed. By analyzing these spectra, we determined the rotational constants B v and the centrifugal distortion constants D v and H v for the X 1 Σ + and A 1 Σ + states of 85 RbD. By considering the isotopic dependence of the Dunham coefficients, we determined various molecular constants of 85 RbH whose values were in good agreement with the observed fluorescence spectra of 85 RbH excited by laser lines at 4762, 4765, and 4880 A. The process of RbH formation is discussed. (author)

Glycoprotein component of plant cell walls

International Nuclear Information System (INIS)

Cooper, J.B.; Chen, J.A.; Varner, J.E.

1984-01-01

The primary wall surrounding most dicotyledonous plant cells contains a hydroxyproline-rich glycoprotein (HRGP) component named extensin. A small group of glycopeptides solubilized from isolated cell walls by proteolysis contained a repeated pentapeptide glycosylated by tri- and tetraarabinosides linked to hydroxyproline and, by galactose, linked to serine. Recently, two complementary approaches to this problem have provided results which greatly increase the understanding of wall extensin. In this paper the authors describe what is known about the structure of soluble extensin secreted into the walls of the carrot root cells

30 years of battling the cell wall.

Science.gov (United States)

Latgé, J P

2017-01-01

In Aspergillus fumigatus, like in other pathogenic fungi, the cell wall is essential for fungal growth as well as for resisting environmental stresses such as phagocytic killing. Most of the chemical analyses undertaken on the cell wall of A. fumigatus are focused on the mycelial cell wall because it is the vegetative stage of the fungus. However, the cell walls of the mycelium and conidium (which is the infective propagule) are different especially at the level of the surface layer, which plays a significant role in the interaction between A. fumigatus conidia and phagocytic cells of the immune system. In spite of the essential function of the cell wall in fungal life, progresses have been extremely slow in the understanding of biosynthesis as well in the identification of the key host responses against the cell wall components. A major difficulty is the fact that the composition and structural organization of the cell wall is not immutably set and is constantly reshuffled depending on the environmental conditions. © The Author 2016. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

2003 Plant Cell Walls Gordon Conference

Energy Technology Data Exchange (ETDEWEB)

Daniel J. Cosgrove

2004-09-21

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

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

Science.gov (United States)

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

2014-03-03

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 (ρ 0 ). 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 ρ 0 cells. Deletion of SCW11 significantly decreases the sensitivity of ρ 0 cells to SDS after salt treatment, while overexpression of SCW11 results in higher sensitivity. In addition, salt stress in ρ 0 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.

[miR-503-5p inhibits the proliferation of T24 and EJ bladder cancer cells by interfering with the Rb/E2F signaling pathway].

Science.gov (United States)

Li, Xiaohui; Han, Xingtao; Yang, Jinhui; Sun, Jiantao; Wei, Pengtao

2017-10-01

Objective To observe the effect of microRNA-503-5p (miR-503-5p) on the growth of T24 and EJ bladder cancer cells, and explore the possible molecular mechanism. Methods The miR-504-5p mimics or miR-NC was transfected into T24 and EJ cells. The target gene of miR-503-5p was predicted by bioinformatics. The expressions of E2F transcription factor 3 (E2F3) mRNA and Rb/E2F signaling pathway mRNA were detected by the real-time quantitative PCR (qPCR). The expressions of Rb/E2F signal pathway proteins E2F3, cyclin E, CDK2, Rb and p-Rb were detected by Western blotting. The cell cycle of bladder cancer cell lines was determined by flow cytometry. MTT assay and plate cloning assay were performed to observe the proliferation ability of bladder cancer cells. Results After miR-503-5p mimics transfection, the expression of miR-503-5p in bladder cancer cells significantly increased. The increased expression of miR-503-5p significantly reduced the expressions of E2F3 mRNA and Rb/E2F signaling pathway mRNA in bladder cancer cells. What's more, the expressions of Rb/E2F signal pathway proteins were down-regulated. The bladder cancer cells were arrested in G0/G1 phase, and their growth was significantly inhibited by miR-503-5p. Conclusion The miR-503-5p over-expression can inhibit the growth of bladder cancer cell lines T24 and EJ by down-regulating the expression of the Rb/E2F signaling pathway.

The plant cell wall integrity maintenance mechanism--a case study of a cell wall plasma membrane signaling network.

Science.gov (United States)

Hamann, Thorsten

2015-04-01

Some of the most important functions of plant cell walls are protection against biotic/abiotic stress and structural support during growth and development. A prerequisite for plant cell walls to perform these functions is the ability to perceive different types of stimuli in both qualitative and quantitative manners and initiate appropriate responses. The responses in turn involve adaptive changes in cellular and cell wall metabolism leading to modifications in the structures originally required for perception. While our knowledge about the underlying plant mechanisms is limited, results from Saccharomyces cerevisiae suggest the cell wall integrity maintenance mechanism represents an excellent example to illustrate how the molecular mechanisms responsible for stimulus perception, signal transduction and integration can function. Here I will review the available knowledge about the yeast cell wall integrity maintenance system for illustration purposes, summarize the limited knowledge available about the corresponding plant mechanism and discuss the relevance of the plant cell wall integrity maintenance mechanism in biotic stress responses. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

OpenAIRE

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 uni...

Investigation of Plant Cell Wall Properties: A Study of Contributions from the Nanoscale to the Macroscale Impacting Cell Wall Recalcitrance

Science.gov (United States)

Crowe, Jacob Dillon

Biochemical conversion of lignocellulosic biomass to fuel ethanol is one of a few challenging, yet opportune technologies that can reduce the consumption of petroleum-derived transportation fuels, while providing parallel reductions in greenhouse gas emissions. Biomass recalcitrance, or resistance to deconstruction, is a major technical challenge that limits effective conversion of biomass to fermentable sugars, often requiring a costly thermochemical pretreatment step to improve biomass deconstruction. Biomass recalcitrance is imparted largely by the secondary cell wall, a complex polymeric matrix of cell wall polysaccharides and aromatic heteropolymers, that provides structural stability to cells and enables plant upright growth. Polymers within the cell wall can vary both compositionally and structurally depending upon plant species and anatomical fraction, and have varied responses to thermochemical pretreatments. Cell wall properties impacting recalcitrance are still not well understood, and as a result, the goal of this dissertation is to investigate structural features of the cell wall contributing to recalcitrance (1) in diverse anatomical fractions of a single species, (2) in response to diverse pretreatments, and (3) resulting from genetic modification. In the first study, feedstock cell wall heterogeneity was investigated in anatomical (stem, leaf sheaths, and leaf blades) and internode fractions of switchgrass at varying tissue maturities. Lignin content was observed as the key contributor to recalcitrance in maturing stem tissues only, with non-cellulosic substituted glucuronoarabinoxylans and pectic polysaccharides contributing to cell wall recalcitrance in leaf sheath and leaf blades. Hydroxycinnamate (i.e., saponifiable p-coumarate and ferulate) content along with xylan and pectin extractability decreased with tissue maturity, suggesting lignification is only one component imparting maturity specific cell wall recalcitrance. In the second study

Studies of inelastic cross-section in Rb(7S) + Rb(5S) collisions

International Nuclear Information System (INIS)

Caiyan, L.; Ekers, A.; Latvia Univ., Riga; Klavins, J.; Jansons, M.

1996-01-01

The cross section σ = (8 ± 4) x 10 -15 cm 2 was determined for the Rb(7S) + Rb(5S) → Rb(5D) + Rb(5S) excitation energy transfer process, and the quenching cross section σ q = (2 ± 1) x 10 -14 cm 2 for the Rb(5D) state in collisions with ground state Rb atoms. Applying rubidium quasimolecular asymptotic potential curves at relatively large internuclear distances, a qualitative interpretation of the experimental results is presented. It is shown that the quenching of the Rb(5D) atoms in collisions may be explained by a reversed energy pooling process Rb(5D) + Rb(5S) → Rb(5P) + Rb(5P). (orig.)

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

Science.gov (United States)

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

Baicalein induces G1 arrest in oral cancer cells by enhancing the degradation of cyclin D1 and activating AhR to decrease Rb phosphorylation

Energy Technology Data Exchange (ETDEWEB)

Cheng, Ya-Hsin, E-mail: yhcheng@mail.cmu.edu.tw [Department of Physiology, School of Medicine, China Medical University, Taichung 40402, Taiwan, ROC (China); Li, Lih-Ann; Lin, Pinpin; Cheng, Li-Chuan [Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan, ROC (China); Hung, Chein-Hui [Graduate Institute of Clinical Medicine Sciences, Chang Gung University, Puizi City, Chiayi 613, Taiwan, ROC (China); Chang, Nai Wen [Department of Biochemistry, School of Medicine, China Medical University, Taichung, Taiwan, ROC (China); Lin, Chingju [Department of Physiology, School of Medicine, China Medical University, Taichung 40402, Taiwan, ROC (China)

2012-09-15

Baicalein is a flavonoid, known to have anti-inflammatory and anti-cancer effects. As an aryl hydrocarbon receptor (AhR) ligand, baicalein at high concentrations blocks AhR-mediated dioxin toxicity. Because AhR had been reported to play a role in regulating the cell cycle, we suspected that the anti-cancer effect of baicalein is associated with AhR. This study investigated the molecular mechanism involved in the anti-cancer effect of baicalein in oral cancer cells HSC-3, including whether such effect would be AhR-mediated. Results revealed that baicalein inhibited cell proliferation and increased AhR activity in a dose-dependent manner. Cell cycle was arrested at the G1 phase and the expression of CDK4, cyclin D1, and phosphorylated retinoblastoma (pRb) was decreased. When the AhR was suppressed by siRNA, the reduction of pRb was partially reversed, accompanied by a decrease of cell population at G1 phase and an increase at S phase, while the reduction of cyclin D1 and CDK4 did not change. This finding suggests that the baicalein activation of AhR is indeed associated with the reduction of pRb, but is independent of the reduction of cyclin D1 and CDK4. When cells were pre-treated with LiCl, the inhibitor of GSK-3β, the decrease of cyclin D1 was blocked and the reduction of pRb was recovered. The data indicates that in HSC-3 the reduction of pRb is both mediated by baicalein through activation of AhR and facilitation of cyclin D1 degradation, which causes cell cycle arrest at the G1 phase, and results in the inhibition of cell proliferation. -- Highlights: ► Baicalein causes the G1 phase arrest by decreasing Rb phosphorylation. ► Baicalein modulates AhR-mediated cell proliferation. ► Both AhR activation and cyclin D1 degradation results in hypophosphorylation of Rb. ► Baicalein facilitates cyclin D1 degradation by signalling the GSK-3β pathway.

Mechanochemical Polarization of Contiguous Cell Walls Shapes Plant Pavement Cells.

Science.gov (United States)

Majda, Mateusz; Grones, Peter; Sintorn, Ida-Maria; Vain, Thomas; Milani, Pascale; Krupinski, Pawel; Zagórska-Marek, Beata; Viotti, Corrado; Jönsson, Henrik; Mellerowicz, Ewa J; Hamant, Olivier; Robert, Stéphanie

2017-11-06

The epidermis of aerial plant organs is thought to be limiting for growth, because it acts as a continuous load-bearing layer, resisting tension. Leaf epidermis contains jigsaw puzzle piece-shaped pavement cells whose shape has been proposed to be a result of subcellular variations in expansion rate that induce local buckling events. Paradoxically, such local compressive buckling should not occur given the tensile stresses across the epidermis. Using computational modeling, we show that the simplest scenario to explain pavement cell shapes within an epidermis under tension must involve mechanical wall heterogeneities across and along the anticlinal pavement cell walls between adjacent cells. Combining genetics, atomic force microscopy, and immunolabeling, we demonstrate that contiguous cell walls indeed exhibit hybrid mechanochemical properties. Such biochemical wall heterogeneities precede wall bending. Altogether, this provides a possible mechanism for the generation of complex plant cell shapes. Copyright © 2017 Elsevier Inc. All rights reserved.

Overexpression of Brucella putative glycosyltransferase WbkA in B. abortus RB51 leads to production of exopolysaccharide.

Science.gov (United States)

Dabral, Neha; Jain-Gupta, Neeta; Seleem, Mohamed N; Sriranganathan, Nammalwar; Vemulapalli, Ramesh

2015-01-01

Brucella spp. are Gram-negative, facultative intracellular bacteria that cause brucellosis in mammals. Brucella strains containing the O-polysaccharide in their cell wall structure exhibit a smooth phenotype whereas the strains devoid of the polysaccharide show rough phenotype. B. abortus strain RB51 is a stable rough attenuated mutant which is used as a licensed live vaccine for bovine brucellosis. Previous studies have shown that the wboA gene, which encodes a glycosyltransferase required for the synthesis of O-polysaccharide, is disrupted in B. abortus RB51 by an IS711 element. Although complementation of strain RB51 with a functional wboA gene results in O-polysaccharide synthesis in the cytoplasm, it does not result in smooth phenotype. The aim of this study was to determine if overexpression of Brucella WbkA or WbkE, two additional putative glycosyltransferases essential for O-polysaccharide synthesis, in strain RB51 would result in the O-polysaccharide synthesis and smooth phenotype. Our results demonstrate that overexpression of wbkA or wbkE gene in RB51 does not result in O-polysaccharide expression as shown by Western blotting with specific antibodies. However, wbkA, but not wbkE, overexpression leads to the development of a clumping phenotype and the production of exopolysaccharide(s) containing mannose, galactose, N-acetylglucosamine, and N-acetylgalactosamine. Moreover, we found that the clumping recombinant strain displays increased adhesion to polystyrene plates. The recombinant strain was similar to strain RB51 in its attenuation characteristic and in its ability to induce protective immunity against virulent B. abortus challenge in mice.

Roles of membrane trafficking in plant cell wall dynamics

Directory of Open Access Journals (Sweden)

Kazuo eEbine

2015-10-01

Full Text Available 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.

Plant cell wall signalling and receptor-like kinases.

Science.gov (United States)

Wolf, Sebastian

2017-02-15

Communication between the extracellular matrix and the cell interior is essential for all organisms as intrinsic and extrinsic cues have to be integrated to co-ordinate development, growth, and behaviour. This applies in particular to plants, the growth and shape of which is governed by deposition and remodelling of the cell wall, a rigid, yet dynamic, extracellular network. It is thus generally assumed that cell wall surveillance pathways exist to monitor the state of the wall and, if needed, elicit compensatory responses such as altered expression of cell wall remodelling and biosynthesis genes. Here, I highlight recent advances in the field of cell wall signalling in plants, with emphasis on the role of plasma membrane receptor-like kinase complexes. In addition, possible roles for cell wall-mediated signalling beyond the maintenance of cell wall integrity are discussed. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

Chemical analysis of isolated cell walls of Gram-positive bacteria and the determination of the cell wall to cell mass ratio.

NARCIS (Netherlands)

Wal, van der A.; Norde, W.; Bendinger, B.; Zehnder, A.J.B.; Lyklema, J.

1997-01-01

Cell walls of five Gram-positive bacterial strains, including four coryneforms and a Bacillus brevis strain were isolated and subsequently chemically analysed. The wall contribution to the total cell mass is calculated from a comparison of D-Lactate concentrations in hydrolysates of whole cells and

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

NARCIS (Netherlands)

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

2000-01-01

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

Identification of Novel Cell Wall Components

Energy Technology Data Exchange (ETDEWEB)

Michelle Momany

2009-10-26

Our DOE Biosciences-funded work focused on the fungal cell wall and morphogenesis. We are especially interested in how new cell wall material is targeted to appropriate areas for polar (asymmetric) growth. Polar growth is the only way that filamentous fungi explore the environment to find suitable substrates to degrade. Work funded by this grant has resulted in a total of twenty peer-reviewed publications. In work funded by this grant, we identified nine Aspergillus nidulans temperature-sensitive (ts) mutants that fail to send out a germ tube and show a swollen cell phenotype at restrictive temperature, the swo mutants. In other organisms, a swollen cell phenotype is often associated with misdirected growth or weakened cell walls. Our work shows that several of the A. nidulans swo mutants have defects in the establishment and maintenance of polarity. Cloning of several swo genes by complementation also showed that secondary modification of proteins seems is important in polarity. We also investigated cell wall biosynthesis and branching based on leads in literature from other organisms and found that branching and nuclear division are tied and that the cell wall reorganizes during development. In our most recent work we have focused on gene expression during the shift from isotropic to polar growth. Surprisingly we found that genes previously thought to be involved only in spore formation are important in early vegetative growth as well.

The cell wall: a carbohydrate armour for the fungal cell.

Science.gov (United States)

Latgé, Jean-Paul

2007-10-01

The cell wall is composed of a polysaccharide-based three-dimensional network. Considered for a long time as an inert exoskeleton, the cell wall is now seen as a dynamic structure that is continuously changing as a result of the modification of culture conditions and environmental stresses. Although the cell wall composition varies among fungal species, chemogenomic comparative analysis have led to a better understanding of the genes and mechanisms involved in the construction of the common central core composed of branched beta1,3 glucan-chitin. Because of its essential biological role, unique biochemistry and structural organization and the absence in mammalian cells of most of its constitutive components, the cell wall is an attractive target for the development of new antifungal agents. Genomic as well as drug studies have shown that the death of the fungus can result from inhibition of cell wall polysaccharide synthases. To date, only beta1,3 glucan synthase inhibitors have been launched clinically and many more targets remain to be explored.

Outside-in control -Does plant cell wall integrity regulate cell cycle progression?

Science.gov (United States)

Gigli-Bisceglia, Nora; Hamann, Thorsten

2018-04-13

During recent years it has become accepted that plant cell walls are not inert objects surrounding all plant cells but are instead highly dynamic, plastic structures. They are involved in a large number of cell biological processes and contribute actively to plant growth, development and interaction with environment. Therefore, it is not surprising that cellular processes can control plant cell wall integrity while, simultaneously, cell wall integrity can influence cellular processes. In yeast and animal cells such a bi-directional relationship also exists between the yeast/animal extra-cellular matrices and the cell cycle. In yeast, the cell wall integrity maintenance mechanism and a dedicated plasmamembrane integrity checkpoint are mediating this relationship. Recent research has yielded insights into the mechanism controlling plant cell wall metabolism during cytokinesis. However, knowledge regarding putative regulatory pathways controlling adaptive modifications in plant cell cycle activity in response to changes in the state of the plant cell wall are not yet identified. In this review, we summarize similarities and differences in regulatory mechanisms coordinating extra cellular matrices and cell cycle activity in animal and yeast cells, discuss the available evidence supporting the existence of such a mechanism in plants and suggest that the plant cell wall integrity maintenance mechanism might also control cell cycle activity in plant cells. This article is protected by copyright. All rights reserved.

Molecular regulation of plant cell wall extensibility

Science.gov (United States)

Cosgrove, D. J.

1998-01-01

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

Evodiamine selectively targets cancer stem-like cells through the p53-p21-Rb pathway

International Nuclear Information System (INIS)

Han, Seula; Woo, Jong Kyu; Jung, Yuchae; Jeong, Dawoon; Kang, Minsook; Yoo, Young-Ji; Lee, Hani; Oh, Seung Hyun; Ryu, Jae-Ha; Kim, Woo-Young

2016-01-01

In spite of the recent improvements, the resistance to chemotherapy/radiotherapy followed by relapse is the main hurdle for the successful treatment of breast cancer, a leading cause of death in women. A small population of breast cancer cells that have stem-like characteristics (cancer stem-like cells; CSLC) may contribute to this resistance and relapse. Here, we report on a component of a traditional Chinese medicine, evodiamine, which selectively targets CSLC of breast cancer cell lines MCF7 and MDAMB 231 at a concentration that does show a little or no cytotoxic effect on bulk cancer cells. While evodiamine caused the accumulation of bulk cancer cells at the G2/M phase, it did not hold CSLC in a specific cell cycle phase but instead, selectively killed CSLC. This was not due to the culture of CSLC in suspension or without FBS. A proteomic analysis and western blotting revealed that evodiamine changed the expression of cell cycle regulating molecules more efficiently in CSLC cells than in bulk cancer cells. Surprisingly, evodiamine selectively activated p53 and p21 and decreased inactive Rb, the master molecules in G1/S checkpoint. These data collectively suggest a novel mechanism involving CSLC-specific targeting by evodiamine and its possible use to the therapy of breast cancer. - Highlights: • Evodiamine selectively kills breast cancer stem like cells at G1 phase. • Evodiamine utilizes different mechanism of cell cycle modulation in CSLC and in bulk cancer cells. • Evodiamine activate the p53, p21 and Rb pathway.

Evodiamine selectively targets cancer stem-like cells through the p53-p21-Rb pathway

Energy Technology Data Exchange (ETDEWEB)

Han, Seula [The Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women' s University, Seoul (Korea, Republic of); Woo, Jong Kyu [College of Pharmacy, Gachon University, Incheon (Korea, Republic of); Jung, Yuchae; Jeong, Dawoon; Kang, Minsook; Yoo, Young-Ji; Lee, Hani [The Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women' s University, Seoul (Korea, Republic of); Oh, Seung Hyun [College of Pharmacy, Gachon University, Incheon (Korea, Republic of); Ryu, Jae-Ha [The Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women' s University, Seoul (Korea, Republic of); Kim, Woo-Young, E-mail: wykim@sookmyung.ac.kr [The Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women' s University, Seoul (Korea, Republic of)

2016-01-22

In spite of the recent improvements, the resistance to chemotherapy/radiotherapy followed by relapse is the main hurdle for the successful treatment of breast cancer, a leading cause of death in women. A small population of breast cancer cells that have stem-like characteristics (cancer stem-like cells; CSLC) may contribute to this resistance and relapse. Here, we report on a component of a traditional Chinese medicine, evodiamine, which selectively targets CSLC of breast cancer cell lines MCF7 and MDAMB 231 at a concentration that does show a little or no cytotoxic effect on bulk cancer cells. While evodiamine caused the accumulation of bulk cancer cells at the G2/M phase, it did not hold CSLC in a specific cell cycle phase but instead, selectively killed CSLC. This was not due to the culture of CSLC in suspension or without FBS. A proteomic analysis and western blotting revealed that evodiamine changed the expression of cell cycle regulating molecules more efficiently in CSLC cells than in bulk cancer cells. Surprisingly, evodiamine selectively activated p53 and p21 and decreased inactive Rb, the master molecules in G1/S checkpoint. These data collectively suggest a novel mechanism involving CSLC-specific targeting by evodiamine and its possible use to the therapy of breast cancer. - Highlights: • Evodiamine selectively kills breast cancer stem like cells at G1 phase. • Evodiamine utilizes different mechanism of cell cycle modulation in CSLC and in bulk cancer cells. • Evodiamine activate the p53, p21 and Rb pathway.

Synthesis of plant cell wall oligosaccharides

DEFF Research Database (Denmark)

Clausen, Mads Hartvig

Plant cell walls are structurally complex and contain a large number of diverse carbohydrate polymers. These plant fibers are a highly valuable bio-resource and the focus of food, energy and health research. We are interested in studying the interplay of plant cell wall carbohydrates with proteins...... for characterizing protein-carbohydrate binding. The presentation will highlight chemical syntheses of plant cell wall oligosaccharides from the group and provide examples from studies of their interactions with proteins....... such as enzymes, cell surface lectins, and antibodies. However, detailed molecular level investigations of such interactions are hampered by the heterogeneity and diversity of the polymers of interest. To circumvent this, we target well-defined oligosaccharides with representative structures that can be used...

Organ size control is dominant over Rb family inactivation to restrict proliferation in vivo.

Science.gov (United States)

Ehmer, Ursula; Zmoos, Anne-Flore; Auerbach, Raymond K; Vaka, Dedeepya; Butte, Atul J; Kay, Mark A; Sage, Julien

2014-07-24

In mammals, a cell's decision to divide is thought to be under the control of the Rb/E2F pathway. We previously found that inactivation of the Rb family of cell cycle inhibitors (Rb, p107, and p130) in quiescent liver progenitors leads to uncontrolled division and cancer initiation. Here, we show that, in contrast, deletion of the entire Rb gene family in mature hepatocytes is not sufficient for their long-term proliferation. The cell cycle block in Rb family mutant hepatocytes is independent of the Arf/p53/p21 checkpoint but can be abrogated upon decreasing liver size. At the molecular level, we identify YAP, a transcriptional regulator involved in organ size control, as a factor required for the sustained expression of cell cycle genes in hepatocytes. These experiments identify a higher level of regulation of the cell cycle in vivo in which signals regulating organ size are dominant regulators of the core cell cycle machinery. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Overexpression of Brucella putative glycosyltransferase WbkA in B. abortus RB51 leads to production of exopolysaccharide

Directory of Open Access Journals (Sweden)

Neha eDabral

2015-06-01

Full Text Available Brucella spp. are Gram-negative, facultative intracellular bacteria that cause brucellosis in mammals. Brucella strains containing the O-polysaccharide in their cell wall structure exhibit a smooth phenotype whereas the strains devoid of the polysaccharide show rough phenotype. B. abortus strain RB51 is a stable rough attenuated mutant which is used as a licensed live vaccine for bovine brucellosis. Previous studies have shown that the wboA gene, which encodes a glycosyltransferase required for the synthesis of O-polysaccharide, is disrupted in B. abortus RB51 by an IS711 element. Although complementation of strain RB51 with a functional wboA gene results in O-polysaccharide synthesis in the cytoplasm, it does not result in smooth phenotype. The aim of this study was to determine if overexpression of Brucella WbkA or WbkE, two additional putative glycosyltransferases essential for O-polysaccharide synthesis, in strain RB51 would result in the O-polysaccharide synthesis and smooth phenotype. Our results demonstrate that overexpression of wbkA or wbkE gene in RB51 does not result in O-polysaccharide expression as shown by Western blotting with specific antibodies. However, wbkA, but not wbkE, overexpression leads to the development of a clumping phenotype and the production of exopolysaccharide(s containing mannose, galactose, N-acetylglucosamine and N-acetylgalactosamine. Moreover, we found that the clumping recombinant strain displays increased adhesion to polystyrene plates. The recombinant strain was similar to strain RB51 in its attenuation characteristic and in its ability to induce protective immunity against virulent B. abortus challenge in mice.

Effects of a laser beam profile on Zeeman electromagnetically induced transparency in the Rb buffer gas cell

International Nuclear Information System (INIS)

Nikolić, S N; Radonjić, M; Krmpot, A J; Lučić, N M; Zlatković, B V; Jelenković, B M

2013-01-01

Electromagnetically induced transparency (EIT) due to Zeeman coherences in the Rb buffer gas cell is studied for different laser beam profiles, laser beam radii and intensities from 0.1 to 10 mW cm −2 . EIT line shapes can be approximated by the Lorentzian for wide Gaussian laser beam (6.5 mm in diameter) if laser intensity is weak and for a Π laser beam profile of the same diameter. Line shapes of EIT become non-Lorentzian for the Gaussian laser beam if it is narrow (1.3 mm in diameter) or if it has a higher intensity. EIT amplitudes and linewidths, for both laser beam profiles of the same diameter, have very similar behaviour regarding laser intensity and Rb cell temperature. EIT amplitudes are maximal at a certain laser beam intensity and this intensity is higher for narrower laser beams. The EIT linewidth estimated at zero laser intensity is about 50 nT or 0.7 kHz, which refers to 1.5 ms relaxation times of Zeeman coherences in 87 Rb atoms in our buffer gas cell. Blocking of the centre of the wide Gaussian laser beam in front of the photo detector yields Lorentzian profiles with a much better contrast to the linewidth ratio for EIT at higher intensities, above ∼2 mW cm −2 . (paper)

Rb1 loss modifies but does not initiate alveolar rhabdomyosarcoma

Science.gov (United States)

2013-01-01

Background Alveolar rhabdomyosarcoma (aRMS) is a myogenic childhood sarcoma frequently associated with a translocation-mediated fusion gene, Pax3:Foxo1a. Methods We investigated the complementary role of Rb1 loss in aRMS tumor initiation and progression using conditional mouse models. Results Rb1 loss was not a necessary and sufficient mutational event for rhabdomyosarcomagenesis, nor a strong cooperative initiating mutation. Instead, Rb1 loss was a modifier of progression and increased anaplasia and pleomorphism. Whereas Pax3:Foxo1a expression was unaltered, biomarkers of aRMS versus embryonal rhabdomyosarcoma were both increased, questioning whether these diagnostic markers are reliable in the context of Rb1 loss. Genome-wide gene expression in Pax3:Foxo1a,Rb1 tumors more closely approximated aRMS than embryonal rhabdomyosarcoma. Intrinsic loss of pRb function in aRMS was evidenced by insensitivity to a Cdk4/6 inhibitor regardless of whether Rb1 was intact or null. This loss of function could be attributed to low baseline Rb1, pRb and phospho-pRb expression in aRMS tumors for which the Rb1 locus was intact. Pax3:Foxo1a RNA interference did not increase pRb or improve Cdk inhibitor sensitivity. Human aRMS shared the feature of low and/or heterogeneous tumor cell pRb expression. Conclusions Rb1 loss from an already low pRb baseline is a significant disease modifier, raising the possibility that some cases of pleomorphic rhabdomyosarcoma may in fact be Pax3:Foxo1a-expressing aRMS with Rb1 or pRb loss of function. PMID:24274149

The Specific Nature of Plant Cell Wall Polysaccharides 1

Science.gov (United States)

Nevins, Donald J.; English, Patricia D.; Albersheim, Peter

1967-01-01

Polysaccharide compositions of cell walls were assessed by quantitative analyses of the component sugars. Cell walls were hydrolyzed in 2 n trifluoroacetic acid and the liberated sugars reduced to their respective alditols. The alditols were acetylated and the resulting alditol acetates separated by gas chromatography. Quantitative assay of the alditol acetates was accomplished by electronically integrating the detector output of the gas chromatograph. Myo-inositol, introduced into the sample prior to hydrolysis, served as an internal standard. The cell wall polysaccharide compositions of plant varieties within a given species are essentially identical. However, differences in the sugar composition were observed in cell walls prepared from different species of the same as well as of different genera. The fact that the wall compositions of different varieties of the same species are the same indicates that the biosynthesis of cell wall polysaccharides is genetically regulated. The cell walls of various morphological parts (roots, hypocotyls, first internodes and primary leaves) of bean plants were each found to have a characteristic sugar composition. It was found that the cell wall sugar composition of suspension-cultured sycamore cells could be altered by growing the cells on different carbon sources. This demonstrates that the biosynthesis of cell wall polysaccharides can be manipulated without fatal consequences. PMID:16656594

At the border: the plasma membrane-cell wall continuum.

Science.gov (United States)

Liu, Zengyu; Persson, Staffan; Sánchez-Rodríguez, Clara

2015-03-01

Plant cells rely on their cell walls for directed growth and environmental adaptation. Synthesis and remodelling of the cell walls are membrane-related processes. During cell growth and exposure to external stimuli, there is a constant exchange of lipids, proteins, and other cell wall components between the cytosol and the plasma membrane/apoplast. This exchange of material and the localization of cell wall proteins at certain spots in the plasma membrane seem to rely on a particular membrane composition. In addition, sensors at the plasma membrane detect changes in the cell wall architecture, and activate cytoplasmic signalling schemes and ultimately cell wall remodelling. The apoplastic polysaccharide matrix is, on the other hand, crucial for preventing proteins diffusing uncontrollably in the membrane. Therefore, the cell wall-plasma membrane link is essential for plant development and responses to external stimuli. This review focuses on the relationship between the cell wall and plasma membrane, and its importance for plant tissue organization. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Cell wall-bound silicon optimizes ammonium uptake and metabolism in rice cells.

Science.gov (United States)

Sheng, Huachun; Ma, Jie; Pu, Junbao; Wang, Lijun

2018-05-16

Turgor-driven plant cell growth depends on cell wall structure and mechanics. Strengthening of cell walls on the basis of an association and interaction with silicon (Si) could lead to improved nutrient uptake and optimized growth and metabolism in rice (Oryza sativa). However, the structural basis and physiological mechanisms of nutrient uptake and metabolism optimization under Si assistance remain obscure. Single-cell level biophysical measurements, including in situ non-invasive micro-testing (NMT) of NH4+ ion fluxes, atomic force microscopy (AFM) of cell walls, and electrolyte leakage and membrane potential, as well as whole-cell proteomics using isobaric tags for relative and absolute quantification (iTRAQ), were performed. The altered cell wall structure increases the uptake rate of the main nutrient NH4+ in Si-accumulating cells, whereas the rate is only half in Si-deprived counterparts. Rigid cell walls enhanced by a wall-bound form of Si as the structural basis stabilize cell membranes. This, in turn, optimizes nutrient uptake of the cells in the same growth phase without any requirement for up-regulation of transmembrane ammonium transporters. Optimization of cellular nutrient acquisition strategies can substantially improve performance in terms of growth, metabolism and stress resistance.

On-Off Switches for Secondary Cell Wall Biosynthesis

Institute of Scientific and Technical Information of China (English)

Huan-Zhong Wang; Richard A.Dixon

2012-01-01

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

A Structurally Specialized Uniform Wall Layer is Essential for Constructing Wall Ingrowth Papillae in Transfer Cells

Science.gov (United States)

Xia, Xue; Zhang, Hui-Ming; Offler, Christina E.; Patrick, John W.

2017-01-01

Transfer cells are characterized by wall labyrinths with either a flange or reticulate architecture. A literature survey established that reticulate wall ingrowth papillae ubiquitously arise from a modified component of their wall labyrinth, termed the uniform wall layer; a structure absent from flange transfer cells. This finding sparked an investigation of the deposition characteristics and role of the uniform wall layer using a Vicia faba cotyledon culture system. On transfer of cotyledons to culture, their adaxial epidermal cells spontaneously trans-differentiate to a reticulate architecture comparable to their abaxial epidermal transfer cell counterparts formed in planta. Uniform wall layer construction commenced once adaxial epidermal cell expansion had ceased to overlay the original outer periclinal wall on its inner surface. In contrast to the dense ring-like lattice of cellulose microfibrils in the original primary wall, the uniform wall layer was characterized by a sparsely dispersed array of linear cellulose microfibrils. A re-modeled cortical microtubule array exerted no influence on uniform wall layer formation or on its cellulose microfibril organization. Surprisingly, formation of the uniform wall layer was not dependent upon depositing a cellulose scaffold. In contrast, uniform wall cellulose microfibrils were essential precursors for constructing wall ingrowth papillae. On converging to form wall ingrowth papillae, the cellulose microfibril diameters increased 3-fold. This event correlated with up-regulated differential, and transfer-cell specific, expression of VfCesA3B while transcript levels of other cellulose biosynthetic-related genes linked with primary wall construction were substantially down-regulated. PMID:29259611

Architecture and Biosynthesis of the Saccharomyces cerevisiae Cell Wall

Science.gov (United States)

Orlean, Peter

2012-01-01

The wall gives a Saccharomyces cerevisiae cell its osmotic integrity; defines cell shape during budding growth, mating, sporulation, and pseudohypha formation; and presents adhesive glycoproteins to other yeast cells. The wall consists of β1,3- and β1,6-glucans, a small amount of chitin, and many different proteins that may bear N- and O-linked glycans and a glycolipid anchor. These components become cross-linked in various ways to form higher-order complexes. Wall composition and degree of cross-linking vary during growth and development and change in response to cell wall stress. This article reviews wall biogenesis in vegetative cells, covering the structure of wall components and how they are cross-linked; the biosynthesis of N- and O-linked glycans, glycosylphosphatidylinositol membrane anchors, β1,3- and β1,6-linked glucans, and chitin; the reactions that cross-link wall components; and the possible functions of enzymatic and nonenzymatic cell wall proteins. PMID:23135325

The role of p53 and pRB in apoptosis and cancer

DEFF Research Database (Denmark)

Hickman, Emma S; Moroni, M Cristina; Helin, Kristian

2002-01-01

Loss of function of both the p53 pathway and the retinoblastoma protein (pRB) pathway plays a significant role in the development of most human cancers. Loss of pRB results in deregulated cell proliferation and apoptosis, whereas loss of p53 desensitizes cells to checkpoint signals, including...

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-06-14

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

The transcription factor Rap1p is required for tolerance to cell-wall perturbing agents and for cell-wall maintenance in Saccharomyces cerevisiae.

Science.gov (United States)

Azad, Gajendra Kumar; Singh, Vikash; Baranwal, Shivani; Thakare, Mayur Jankiram; Tomar, Raghuvir S

2015-01-02

Yeast repressor activator protein (Rap1p) is involved in genomic stability and transcriptional regulation. We explored the function of Rap1p in yeast physiology using Rap1p truncation mutants. Our results revealed that the N-terminal truncation of Rap1p (Rap1ΔN) leads to hypersensitivity towards elevated temperature and cell-wall perturbing agents. Cell wall analysis showed an increase in the chitin and glucan content in Rap1ΔN cells as compared with wild type cells. Accordingly, mutant cells had a twofold thicker cell wall, as observed by electron microscopy. Furthermore, Rap1ΔN cells had increased levels of phosphorylated Slt2p, a MAP kinase of the cell wall integrity pathway. Mutant cells also had elevated levels of cell wall integrity response transcripts. Taken together, our findings suggest a connection between Rap1p and cell wall homeostasis. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Organ Size Control Is Dominant over Rb Family Inactivation to Restrict Proliferation In Vivo

Directory of Open Access Journals (Sweden)

Ursula Ehmer

2014-07-01

Full Text Available In mammals, a cell’s decision to divide is thought to be under the control of the Rb/E2F pathway. We previously found that inactivation of the Rb family of cell cycle inhibitors (Rb, p107, and p130 in quiescent liver progenitors leads to uncontrolled division and cancer initiation. Here, we show that, in contrast, deletion of the entire Rb gene family in mature hepatocytes is not sufficient for their long-term proliferation. The cell cycle block in Rb family mutant hepatocytes is independent of the Arf/p53/p21 checkpoint but can be abrogated upon decreasing liver size. At the molecular level, we identify YAP, a transcriptional regulator involved in organ size control, as a factor required for the sustained expression of cell cycle genes in hepatocytes. These experiments identify a higher level of regulation of the cell cycle in vivo in which signals regulating organ size are dominant regulators of the core cell cycle machinery.

Mechanosensation Dynamically Coordinates Polar Growth and Cell Wall Assembly to Promote Cell Survival.

Science.gov (United States)

Davì, Valeria; Tanimoto, Hirokazu; Ershov, Dmitry; Haupt, Armin; De Belly, Henry; Le Borgne, Rémi; Couturier, Etienne; Boudaoud, Arezki; Minc, Nicolas

2018-04-23

How growing cells cope with size expansion while ensuring mechanical integrity is not known. In walled cells, such as those of microbes and plants, growth and viability are both supported by a thin and rigid encasing cell wall (CW). We deciphered the dynamic mechanisms controlling wall surface assembly during cell growth, using a sub-resolution microscopy approach to monitor CW thickness in live rod-shaped fission yeast cells. We found that polar cell growth yielded wall thinning and that thickness negatively influenced growth. Thickness at growing tips exhibited a fluctuating behavior with thickening phases followed by thinning phases, indicative of a delayed feedback promoting thickness homeostasis. This feedback was mediated by mechanosensing through the CW integrity pathway, which probes strain in the wall to adjust synthase localization and activity to surface growth. Mutants defective in thickness homeostasis lysed by rupturing the wall, demonstrating its pivotal role for walled cell survival. Copyright © 2018 Elsevier Inc. All rights reserved.

Ouabain-sensitive Rb+ uptake in mouse eggs and preimplantation conceptuses

International Nuclear Information System (INIS)

Van Winkle, L.J.; Campione, A.L.

1991-01-01

The results of histochemical and immunocytochemical studies have been used elsewhere to support the hypothesis that Na+/K(+)-ATPase expression is initiated or increases dramatically in preimplantation mouse conceptuses just before they begin to cavitate. Moreover, localization of the enzyme in the inner membrane of the mural trophoblast is thought to be involved directly in formation and maintenance of the blastocyst cavity. Presumably, Na+/K(+)-ATPase extrudes the cation, Na+, and therefore water into the cavity. The cation transporting activity of the enzyme can be determined by measuring ouabain-sensitive Rb+ uptake by cells. Therefore, we measured Rb+ uptake in mouse eggs and preimplantation conceptuses at various stages of development. 86Rb+ uptake by conceptuses increased linearly with time for at least 60 min in medium containing 0.7 mM total Rb+ plus K+ in the absence or presence of 1.0 mM ouabain, and ouabain inhibited more than 70% of 86Rb+ uptake. The ouabain concentration at 1/2 of maximum inhibition of the ouabain-sensitive component of 86Rb+ uptake was about 10-20 microM in eggs and conceptuses at all stages of preimplantation development. Moreover, ouabain-sensitive Rb+ uptake had a twofold higher Vmax value in blastocysts than in eggs or conceptuses at earlier stages of development (i.e., approximately 173 vs 70-100 fmole.conceptus-1.min-1), although the total cell surface area also was probably about two times greater in blastocysts than in eggs or other conceptuses. Ouabain-sensitive Rb+ transport in eggs and conceptuses may have occurred via a single ouabain-sensitive Rb+ transporter with a Hill coefficient of 1.5-1.8 (Hill plots). When it was assumed that the Hill coefficient had a value of 2.0, however, eggs and conceptuses appeared to contain at least two forms of Na+/K(+)-ATPase activity

Experimental Model to Study the Role of Retinoblastoma Gene Product (pRb) for Determination of Adipocyte Differentiation.

Science.gov (United States)

Popov, B V; Shilo, P S; Zhidkova, O V; Zaichik, A M; Petrov, N S

2015-06-01

Using stable constitutive expression of retinoblastoma gene product (pRb) in polypotent mesenchymal 10T1/2 cells we obtained stable cell lines hyperexpressing functionally active or inactive mutant pRb. The cells producing active exogenous pRb demonstrated high sensitivity to adipocyte differentiation inductors, whereas production of inactive form of the exogenous protein suppressed adipocyte differentiation. The obtained lines can serve as the experimental model for studying the role of pRb in determination of adipocyte differentiation.

A dynamical model for plant cell wall architecture formation.

NARCIS (Netherlands)

Mulder, B.M.; Emons, A.M.C.

2001-01-01

We discuss a dynamical mathematical model to explain cell wall architecture in plant cells. The highly regular textures observed in cell walls reflect the spatial organisation of the cellulose microfibrils (CMFs), the most important structural component of cell walls. Based on a geometrical theory

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

Directory of Open Access Journals (Sweden)

Kouki eYoshida

2013-10-01

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

Branched pectic galactan in phloem-sieve-element cell walls: implications for cell mechanics

DEFF Research Database (Denmark)

Torode, Thomas A.; O'Neill, Rachel E.; Marcus, Susan E.

2017-01-01

has previously been identified in garlic bulbs in which the LM26 epitope is widespread throughout most cell walls including those of phloem cells. Garlic bulb cell wall material has been used to confirm the association of the LM26 epitope with cell wall pectic rhamnogalacturonan-I (RG...

Small molecule probes for plant cell wall polysaccharide imaging

Directory of Open Access Journals (Sweden)

Ian eWallace

2012-05-01

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

Microbial transformation of ginsenoside Rb1 to compound K by Lactobacillus paralimentarius.

Science.gov (United States)

Quan, Lin-Hu; Kim, Yeon-Ju; Li, Guan Hao; Choi, Kwang-Tea; Yang, Deok-Chun

2013-06-01

In this study, the major ginsenoside Rb1 was transformed into the more pharmacologically active minor compound K by food grade Lactobacillus paralimentarius LH4, which was isolated from kimchi, a traditional Korean fermented food. The enzymatic reaction was analyzed by TLC, HPLC, and NMR. Using the cell-free enzyme of Lactobacillus paralimentarius LH4 at optimal conditions for 30 °C at pH 6.0, 1.0 mg ml(-1) ginsenoside Rb1 was transformed into 0.52 mg ml(-1) compound K within 72 h, with a corresponding molar conversion yield of 88 %. The cell-free enzyme hydrolyzed the two glucose moieties attached to the C-3 position and the outer glucose moiety attached to the C-20 position of the ginsenoside Rb1. The cell-free enzyme hydrolyzed the ginsenoside Rb1 along the following pathway: ginsenoside Rb1 → gypenoside XVII and ginsenoside Rd → ginsenoside F2 → compound K. Our results indicate that Lactobacillus paralimentarius LH4 has the potential to be applied for the preparation of compound K in the food industry.

A computational approach for inferring the cell wall properties that govern guard cell dynamics.

Science.gov (United States)

Woolfenden, Hugh C; Bourdais, Gildas; Kopischke, Michaela; Miedes, Eva; Molina, Antonio; Robatzek, Silke; Morris, Richard J

2017-10-01

Guard cells dynamically adjust their shape in order to regulate photosynthetic gas exchange, respiration rates and defend against pathogen entry. Cell shape changes are determined by the interplay of cell wall material properties and turgor pressure. To investigate this relationship between turgor pressure, cell wall properties and cell shape, we focused on kidney-shaped stomata and developed a biomechanical model of a guard cell pair. Treating the cell wall as a composite of the pectin-rich cell wall matrix embedded with cellulose microfibrils, we show that strong, circumferentially oriented fibres are critical for opening. We find that the opening dynamics are dictated by the mechanical stress response of the cell wall matrix, and as the turgor rises, the pectinaceous matrix stiffens. We validate these predictions with stomatal opening experiments in selected Arabidopsis cell wall mutants. Thus, using a computational framework that combines a 3D biomechanical model with parameter optimization, we demonstrate how to exploit subtle shape changes to infer cell wall material properties. Our findings reveal that proper stomatal dynamics are built on two key properties of the cell wall, namely anisotropy in the form of hoop reinforcement and strain stiffening. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd and Society for Experimental Biology.

Changes in Cell Wall Polysaccharides Associated With Growth 1

Science.gov (United States)

Nevins, Donald J.; English, Patricia D.; Albersheim, Peter

1968-01-01

Changes in the polysaccharide composition of Phaseolus vulgaris, P. aureus, and Zea mays cell walls were studied during the first 28 days of seedling development using a gas chromatographic method for the analysis of neutral sugars. Acid hydrolysis of cell wall material from young tissues liberates rhamnose, fucose, arabinose, xylose, mannose, galactose, and glucose which collectively can account for as much as 70% of the dry weight of the wall. Mature walls in fully expanded tissues of these same plants contain less of these constituents (10%-20% of dry wt). Gross differences are observed between developmental patterns of the cell wall in the various parts of a seedling, such as root, stem, and leaf. The general patterns of wall polysaccharide composition change, however, are similar for analogous organs among the varieties of a species. Small but significant differences in the rates of change in sugar composition were detected between varieties of the same species which exhibited different growth patterns. The cell walls of species which are further removed phylogenetically exhibit even more dissimilar developmental patterns. The results demonstrate the dynamic nature of the cell wall during growth as well as the quantitative and qualitative exactness with which the biosynthesis of plant cell walls is regulated. PMID:16656862

Cell Wall Metabolism in Response to Abiotic Stress

Science.gov (United States)

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

Two endogenous proteins that induce cell wall extension in plants

Science.gov (United States)

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

1992-01-01

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

Altered Cell Wall Plasticity Can Restrict Plant Growth under Ammonium Nutrition.

Science.gov (United States)

Podgórska, Anna; Burian, Maria; Gieczewska, Katarzyna; Ostaszewska-Bugajska, Monika; Zebrowski, Jacek; Solecka, Danuta; Szal, Bożena

2017-01-01

Plants mainly utilize inorganic forms of nitrogen (N), such as nitrate (NO 3 - ) and ammonium (NH 4 + ). However, the composition of the N source is important, because excess of NH 4 + promotes morphological disorders. Plants cultured on NH 4 + as the sole N source exhibit serious growth inhibition, commonly referred to as "ammonium toxicity syndrome." NH 4 + -mediated suppression of growth may be attributable to both repression of cell elongation and reduction of cell division. The precondition for cell enlargement is the expansion of the cell wall, which requires the loosening of the cell wall polymers. Therefore, to understand how NH 4 + nutrition may trigger growth retardation in plants, properties of their cell walls were analyzed. We found that Arabidopsis thaliana using NH 4 + as the sole N source has smaller cells with relatively thicker cell walls. Moreover, cellulose, which is the main load-bearing polysaccharide revealed a denser assembly of microfibrils. Consequently, the leaf blade tissue showed elevated tensile strength and indicated higher cell wall stiffness. These changes might be related to changes in polysaccharide and ion content of cell walls. Further, NH 4 + toxicity was associated with altered activities of cell wall modifying proteins. The lower activity and/or expression of pectin hydrolyzing enzymes and expansins might limit cell wall expansion. Additionally, the higher activity of cell wall peroxidases can lead to higher cross-linking of cell wall polymers. Overall, the NH 4 + -mediated inhibition of growth is related to a more rigid cell wall structure, which limits expansion of cells. The changes in cell wall composition were also indicated by decreased expression of Feronia , a receptor-like kinase involved in the control of cell wall extension.

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

Science.gov (United States)

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

1990-01-01

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

Disruption of cell walls for enhanced lipid recovery

Science.gov (United States)

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.

Cell Wall Composition and Candidate Biosynthesis Gene Expression During Rice Development

Energy Technology Data Exchange (ETDEWEB)

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.

2016-08-01

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.

Structural Studies of Complex Carbohydrates of Plant Cell Walls

Energy Technology Data Exchange (ETDEWEB)

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

2015-02-17

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

Hybrid optical pumping of K and Rb atoms in a paraffin coated vapor cell

Science.gov (United States)

Li, Wenhao; Peng, Xiang; Budker, Dmitry; Wickenbrock, Arne; Pang, Bo; Zhang, Rui; Guo, Hong

2017-10-01

Dynamic hybrid optical pumping effects with a radio-frequency-field-driven nonlinear magneto-optical rotation (RF NMOR) scheme are studied in a dual-species paraffin coated vapor cell. By pumping K atoms and probing $^{87}$Rb atoms, we achieve an intrinsic magnetic resonance linewidth of 3 Hz and the observed resonance is immune to power broadening and light-shift effects. Such operation scheme shows favorable prospects for atomic magnetometry applications.

Wall relaxation and the driving forces for cell expansive growth

Science.gov (United States)

Cosgrove, D. J.

1987-01-01

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

Ginsenoside Rb1 protects against 6-hydroxydopamine-induced oxidative stress by increasing heme oxygenase-1 expression through an estrogen receptor-related PI3K/Akt/Nrf2-dependent pathway in human dopaminergic cells

International Nuclear Information System (INIS)

Hwang, Yong Pil; Jeong, Hye Gwang

2010-01-01

Phytoestrogens are polyphenolic non-steroidal plant compounds with estrogen-like biological activity. Ginseng, the root of Panax ginseng C.A. Meyer (Araliaceae), is a popular traditional herbal medicine. Ginsenoside Rb1 (Rb1), an active component commonly found in ginseng root, is a phytoestrogen that exerts estrogen-like activity. In this study, we demonstrate that the phytoestrogen Rb1 inhibits 6-hydroxydopamine (6-OHDA)-induced oxidative injury via an ER-dependent Gβ1/PI3K/Akt and heme oxygenase-1 (HO-1) pathway. Pretreatment of SH-SY5Y cells with Rb1 significantly reduced 6-OHDA-induced caspase-3 activation and subsequent cell death. Rb1 also up-regulated HO-1 expression, which conferred cytoprotection against 6-OHDA-induced oxidative injury. Moreover, Rb1 induced both Nrf2 nuclear translocation, which is upstream of HO-1 expression and PI3K activation, a pathway that is involved in induced Nrf2 nuclear translocation, HO-1 expression and cytoprotection. Also, Rb1-mediated increases in PI3K activation and HO-1 induction were reversed by co-treatment with ICI 182,780 and pertussis toxin. Taken together, these results suggest that Rb1 augments the cellular antioxidant defenses through ER-dependent HO-1 induction via the Gβ1/PI3K/Akt-Nrf2 signaling pathway, thereby protecting cells from oxidative stress. Thus our study indicates that Rb1 has a partial cytoprotective role in dopaminergic cell culture systems.

An enzymatic approach to cell wall structure | Hungate | South ...

African Journals Online (AJOL)

Ruminococcus albus was incubated with isolated alfalfa cell wall material for 72 h in batch culture. Cellulose in the cell walls was digested to a somewhat greater extent (88%) than were the fermentable sugars of the hemicellulose fraction (62- 76%). The digestibility of the total insoluble alfalfa cell wall, including lignin but ...

Pea Border Cell Maturation and Release Involve Complex Cell Wall Structural Dynamics.

Science.gov (United States)

Mravec, Jozef; Guo, Xiaoyuan; Hansen, Aleksander Riise; Schückel, Julia; Kračun, Stjepan Krešimir; Mikkelsen, Maria Dalgaard; Mouille, Grégory; Johansen, Ida Elisabeth; Ulvskov, Peter; Domozych, David S; Willats, William George Tycho

2017-06-01

The adhesion of plant cells is vital for support and protection of the plant body and is maintained by a variety of molecular associations between cell wall components. In some specialized cases, though, plant cells are programmed to detach, and root cap-derived border cells are examples of this. Border cells (in some species known as border-like cells) provide an expendable barrier between roots and the environment. Their maturation and release is an important but poorly characterized cell separation event. To gain a deeper insight into the complex cellular dynamics underlying this process, we undertook a systematic, detailed analysis of pea ( Pisum sativum ) root tip cell walls. Our study included immunocarbohydrate microarray profiling, monosaccharide composition determination, Fourier-transformed infrared microspectroscopy, quantitative reverse transcription-PCR of cell wall biosynthetic genes, analysis of hydrolytic activities, transmission electron microscopy, and immunolocalization of cell wall components. Using this integrated glycobiology approach, we identified multiple novel modes of cell wall structural and compositional rearrangement during root cap growth and the release of border cells. Our findings provide a new level of detail about border cell maturation and enable us to develop a model of the separation process. We propose that loss of adhesion by the dissolution of homogalacturonan in the middle lamellae is augmented by an active biophysical process of cell curvature driven by the polarized distribution of xyloglucan and extensin epitopes. © 2017 American Society of Plant Biologists. All Rights Reserved.

Magnetic domain wall conduits for single cell applications

DEFF Research Database (Denmark)

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

2011-01-01

The ability to trap, manipulate and release single cells on a surface is important both for fundamental studies of cellular processes and for the development of novel lab-on-chip miniaturized tools for biological and medical applications. In this paper we demonstrate how magnetic domain walls...... 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....

Crystal structure of 4-RbHo(PO3)4, 4-RbTm(PO3)4 and 4-CsEr(PO3)4

International Nuclear Information System (INIS)

Maksimova, S.I.; Palkina, K.K.; Chibiskova, N.T.

1982-01-01

X-ray structural study of 4-RbLn(PO 3 ) 4 (Ln=Mo, Tm) and 4-CsEr(PO 3 ) 4 is carried out. The compounds are crystallized in monoclinic crystal system, sp. gr P2 1 /n. Parameters of their unit cell, atom coordinates, anisotropic heat parameters, interatomic distances and valent angles are given. 4-RbHo(PO 3 ) 4 , 4-RbTm(PO 3 ) 4 , 4-CsEr(PO 3 ) 4 are isostructural to previously studied TlNd(PO 3 ) and 4-RbNd(PO 3 ) 4 . Using as an example the structural type 4-M 1 Ln(PO 3 ) 4 it is shown that the change of the shortest distances Ln-Ln, M 1 -M 1 and M 1 -Ln, as well as of degree of polymorphous chain corrugation to a higher extent depends on rare earth atom dimensions, than on monovalent metal ion dimensions [ru

The tumor suppressor Rb and its related Rbl2 genes are regulated by Utx histone demethylase

Energy Technology Data Exchange (ETDEWEB)

Terashima, Minoru; Ishimura, Akihiko; Yoshida, Masakazu [Division of Functional Genomics, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Ishikawa (Japan); Suzuki, Yutaka; Sugano, Sumio [Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Chiba (Japan); Suzuki, Takeshi, E-mail: suzuki-t@staff.kanazawa-u.ac.jp [Division of Functional Genomics, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Ishikawa (Japan)

2010-08-20

Research highlights: {yields} Utx increases expression of Rb and Rbl2 genes through its demethylase activity. {yields} Utx changes histone H3 methylation on the Rb and Rbl2 promoters. {yields} Utx induces decreased cell proliferation of mammalian primary cells. -- Abstract: Utx is a candidate tumor suppressor gene that encodes histone H3 lysine 27 (H3K27) demethylase. In this study, we found that ectopic expression of Utx enhanced the expression of retinoblastoma tumor suppressor gene Rb and its related gene Rbl2. This activation was dependent on the demethylase activity of Utx, and was suggested to contribute to the decreased cell proliferation induced by Utx. A chromatin immunoprecipitation assay showed that over-expressed Utx was associated with the promoter regions of Rb and Rbl2 resulting in the removal of repressive H3K27 tri-methylation and the increase in active H3K4 tri-methylation. Furthermore, siRNA-mediated knockdown of Utx revealed the recruitment of endogenous Utx protein on the promoters of Rb and Rbl2 genes. These results indicate that Rb and Rbl2 are downstream target genes of Utx and may play important roles in Utx-mediated cell growth control.

Yeast cell wall chitin reduces wine haze formation.

Science.gov (United States)

Ndlovu, Thulile; Divol, Benoit; Bauer, Florian F

2018-04-27

Protein haze formation in bottled wines is a significant concern for the global wine industry and wine clarification before bottling is therefore a common but expensive practice. Previous studies have shown that wine yeast strains can reduce haze formation through the secretion of certain mannoproteins, but it has been suggested that other yeast-dependent haze protective mechanisms exist. On the other hand, addition of chitin has been shown to reduce haze formation, likely because grape chitinases have been shown to be the major contributors to haze. In this study, Chardonnay grape must fermented by various yeast strains resulted in wines with different protein haze levels indicating differences in haze protective capacities of the strains. The cell wall chitin levels of these strains were determined, and a strong correlation between cell wall chitin levels and haze protection capability was observed. To further evaluate the mechanism of haze protection, Escherichia coli -produced GFP-tagged grape chitinase was shown to bind efficiently to yeast cell walls in a cell wall chitin concentration-dependent manner, while commercial chitinase was removed from synthetic wine in quantities also correlated with the cell wall chitin levels of the strains. Our findings suggest a new mechanism of reducing wine haze, and propose a strategy for optimizing wine yeast strains to improve wine clarification. Importance In this study, we establish a new mechanism by which wine yeast strains can impact on the protein haze formation of wines, and demonstrate that yeast cell wall chitin binds grape chitinase in a chitin-concentration dependent manner. We also show that yeast can remove this haze-forming protein from wine. Chitin has in the past been shown to efficiently reduce wine haze formation when added to the wine in high concentration as a clarifying agent. Our data suggest that the selection of yeast strains with high levels of cell wall chitin can reduce protein haze. We also

Differential gene expression profiling of endometrium during the mid-luteal phase of the estrous cycle between a repeat breeder (RB) and non-RB cows.

Science.gov (United States)

Hayashi, Ken-Go; Hosoe, Misa; Kizaki, Keiichiro; Fujii, Shiori; Kanahara, Hiroko; Takahashi, Toru; Sakumoto, Ryosuke

2017-03-23

were localized in luminal and glandular epithelial cells and stroma of the endometrium. The present study showed that endometrial gene expression profiles are different between RB and non-RB cows. The identified candidate endometrial genes and functions in each endometrial compartment may contribute to bovine reproductive performance.

A pathological study on overexpression of c-fos and Rb proteins in human radiation skin ulcer

International Nuclear Information System (INIS)

Du Yuejiao; Wang Dewen; Gao Yabing

1996-01-01

We performed an immunohistochemical study on human radiation skin ulcer by using antibodies against c-fos and Rb proteins and antigen-repairing method with a microwave oven. We found that the positive rates of overexpression of c-fos and Rb proteins were 84.0% and 100%, respectively. The overexpression of c-fos protein was mainly observed in cell nuclei of squamous epithelial cells, fibroblasts, endothelial cells, and leiomyocytes in media and fibrocytes in adventitia of arterioles. The location of the Rb protein overexpression was mostly similar to that of c-fos protein. The overexpression of c-fos and Rb proteins may be related to cancer transformation and poor healing of radiation-induced skin ulcers

RB1CC1 Protein Suppresses Type II Collagen Synthesis in Chondrocytes and Causes Dwarfism*

Science.gov (United States)

Nishimura, Ichiro; Chano, Tokuhiro; Kita, Hiroko; Matsusue, Yoshitaka; Okabe, Hidetoshi

2011-01-01

RB1-inducible coiled-coil 1 (RB1CC1) functions in various processes, such as cell growth, differentiation, senescence, apoptosis, and autophagy. The conditional transgenic mice with cartilage-specific RB1CC1 excess that were used in the present study were made for the first time by the Cre-loxP system. Cartilage-specific RB1CC1 excess caused dwarfism in mice without causing obvious abnormalities in endochondral ossification and subsequent skeletal development from embryo to adult. In vitro and in vivo analysis revealed that the dwarf phenotype in cartilaginous RB1CC1 excess was induced by reductions in the total amount of cartilage and the number of cartilaginous cells, following suppressions of type II collagen synthesis and Erk1/2 signals. In addition, we have demonstrated that two kinds of SNPs (T-547C and C-468T) in the human RB1CC1 promoter have significant influence on the self-transcriptional level. Accordingly, human genotypic variants of RB1CC1 that either stimulate or inhibit RB1CC1 transcription in vivo may cause body size variations. PMID:22049074

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

DEFF Research Database (Denmark)

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

2015-01-01

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

Pea border cell maturation and release involve complex cell wall structural dynamics

DEFF Research Database (Denmark)

Mravec, Jozef; Guo, Xiaoyuan; Hansen, Aleksander Riise

2017-01-01

The adhesion of plant cells is vital for support and protection of the plant body and is maintained by a variety of molecular associations between cell wall components. In some specialized cases though, plant cells are programmed to detach and root cap-derived border cells are examples of this....... Border cells (in some species known as border-like cells) provide an expendable barrier between roots and the environment. Their maturation and release is an important but poorly characterized cell separation event. To gain a deeper insight into the complex cellular dynamics underlying this process, we...... undertook a systematic, detailed analysis of pea (Pisum sativum) root tip cell walls. Our study included immuno-carbohydrate microarray profiling, monosaccharide composition determination, Fourier-transformed infrared microspectroscopy (FT-IR), quantitative RT-PCR of cell wall biosynthetic genes, analysis...

Cell wall composition and candidate biosynthesis gene expression during rice development

DEFF Research Database (Denmark)

Lin, Fan; Manisseri, Chithra; Fagerström, Alexandra

2016-01-01

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...

Satellite bands of the RbCs molecule in the range of highly excited states

Energy Technology Data Exchange (ETDEWEB)

Rakić, Mario; Beuc, Robert; Skenderović, Hrvoje, E-mail: hrvoje@ifs.hr [Institute of Physics, Bijenička cesta 46, Zagreb 10000 (Croatia); Bouloufa-Maafa, Nadia; Dulieu, Olivier; Vexiau, Romain [Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, Bât. 505, Campus d’Orsay, Orsay Cedex 91405 (France); Pichler, Goran [Physics Department, Kuwait University, PO Box 5969, Safat—13060 (Kuwait)

2016-05-28

We report on the observation of three RbCs satellite bands in the blue and green ranges of the visible spectrum. Absorption measurements are performed using all-sapphire cell filled with a mixture of Rb and Cs. We compare high resolution absorption spectrum of Rb-Cs vapor mixture with pure Rb and Cs vapor spectra from the literature. After detailed analysis, the new satellite bands of RbCs molecule at 418.3 nm, 468.3, and 527.5 nm are identified. The origin of these bands is discussed by direct comparison with difference potentials derived from quantum chemistry calculations of RbCs potential energy curves. These bands originate from the lower Rydberg states of the RbCs molecule. This study thus provides further insight into photoassociation of lower Rydberg molecular states, approximately between Cs(7s) + Rb(5s) and Cs(6s) + Rb(6p) asymptotes, in ultracold gases.

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

DEFF Research Database (Denmark)

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

2006-01-01

The effects of the cellulose inhibitor dichlobenil on the cell wall composition and structure during the habituation/dehabituation process of suspension-cultured bean cells were assessed. A range of techniques were used including cell wall fractionation, sugar analysis, immunofluorescence...... and fluorochrome labelling of resin-embedded sections, and immunodot assays (IDAs) of cell wall fractions. The cell walls from bean cell suspensions with initial levels of habituation to dichlobenil had decreased levels of cellulose, but this effect lessened with increasing numbers of subcultures. All cell walls...

Reduced Wall Acetylation Proteins Play Vital and Distinct Roles in Cell Wall O-Acetylation in Arabidopsis

DEFF Research Database (Denmark)

Manabe, Yuzuki; Verhertbruggen, Yves; Gille, Sascha

2013-01-01

The Reduced Wall Acetylation (RWA) proteins are involved in cell wall acetylation in plants. Previously, we described a single mutant, rwa2, which has about 20% lower level of O-acetylation in leaf cell walls and no obvious growth or developmental phenotype. In this study, we generated double....... The quadruple rwa mutant can be completely complemented with the RWA2 protein expressed under 35S promoter, indicating the functional redundancy of the RWA proteins. Nevertheless, the degree of acetylation of xylan, (gluco) mannan, and xyloglucan as well as overall cell wall acetylation is affected differently...... in different combinations of triple mutants, suggesting their diversity in substrate preference. The overall degree of wall acetylation in the rwa quadruple mutant was reduced by 63% compared with the wild type, and histochemical analysis of the rwa quadruple mutant stem indicates defects in cell...

The Role of Pectin Acetylation in the Organization of Plant Cell Walls

DEFF Research Database (Denmark)

Fimognari, Lorenzo

adopt defined 3D organization to allow their composition/interactions to be tweaked upon developmental need. Failure to build functional cell wall architecture will affect plant growth and resistance to stresses. In this PhD dissertation I explored the role of pectin acetylation in controlling...... wall organization, namely polysaccharides-to-polysaccharides interactions. These results suggest that cell wall acetylation is a mechanism that plants evolved to control cell wall organization. In Manuscript III, we report the characterization of Arabidopsis mutants trichome birefringence like (tbl) 10......All plant cells are surrounded by one or more cell wall layers. The cell wall serves as a stiff mechanical support while it allows cells to expand and provide a protective barrier to invading pathogens. Cell walls are dynamic structures composed of entangled cell wall polysaccharides that must...

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

Science.gov (United States)

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

2015-01-01

Yeast cells are protected by a cell wall that plays an important role in the exchange of substances with the environment. The cell wall structure is dynamic and can adapt to different physiological states or environmental conditions. For the investigation of morphological changes, selective staining with fluorescent dyes is a valuable tool. Furthermore, cell wall staining is used to facilitate sub-cellular localization experiments with fluorescently-labeled proteins and the detection of yeast cells in non-fungal host tissues. Here, we report staining of Saccharomyces cerevisiae cell wall with Trypan Blue, which emits strong red fluorescence upon binding to chitin and yeast glucan; thereby, it facilitates cell wall analysis by confocal and super-resolution microscopy. The staining pattern of Trypan Blue was similar to that of the widely used UV-excitable, blue fluorescent cell wall stain Calcofluor White. Trypan Blue staining facilitated quantification of cell size and cell wall volume when utilizing the optical sectioning capacity of a confocal microscope. This enabled the quantification of morphological changes during growth under anaerobic conditions and in the presence of chemicals, demonstrating the potential of this approach for morphological investigations or screening assays.

Cell wall staining with Trypan Blue enables quantitative analysis of morphological changes in yeast cells

Directory of Open Access Journals (Sweden)

Johannes eLiesche

2015-02-01

Full Text Available Yeast cells are protected by a cell wall that plays an important role in the exchange of substances with the environment. The cell wall structure is dynamic and can adapt to different physiological states or environmental conditions. For the investigation of morphological changes, selective staining with fluorescent dyes is a valuable tool. Furthermore, cell wall staining is used to facilitate sub-cellular localization experiments with fluorescently-labeled proteins and the detection of yeast cells in non-fungal host tissues. Here, we report staining of Saccharomyces cerevisiae cell wall with Trypan Blue, which emits strong red fluorescence upon binding to chitin and yeast glucan; thereby, it facilitates cell wall analysis by confocal and super-resolution microscopy. The staining pattern of Trypan Blue was similar to that of the widely used UV-excitable, blue fluorescent cell wall stain Calcofluor White. Trypan Blue staining facilitated quantification of cell size and cell wall volume when utilizing the optical sectioning capacity of a confocal microscope. This enabled the quantification of morphological changes during growth under anaerobic conditions and in the presence of chemicals, demonstrating the potential of this approach for morphological investigations or screening assays.

Zebrafish usp39 mutation leads to rb1 mRNA splicing defect and pituitary lineage expansion.

Directory of Open Access Journals (Sweden)

Yesenia Ríos

2011-01-01

Full Text Available Loss of retinoblastoma (Rb tumor suppressor function is associated with human malignancies. Molecular and genetic mechanisms responsible for tumorigenic Rb downregulation are not fully defined. Through a forward genetic screen and positional cloning, we identified and characterized a zebrafish ubiquitin specific peptidase 39 (usp39 mutation, the yeast and human homolog of which encodes a component of RNA splicing machinery. Zebrafish usp39 mutants exhibit microcephaly and adenohypophyseal cell lineage expansion without apparent changes in major hypothalamic hormonal and regulatory signals. Gene expression profiling of usp39 mutants revealed decreased rb1 and increased e2f4, rbl2 (p130, and cdkn1a (p21 expression. Rb1 mRNA overexpression, or antisense morpholino knockdown of e2f4, partially reversed embryonic pituitary expansion in usp39 mutants. Analysis of pre-mRNA splicing status of critical cell cycle regulators showed misspliced Rb1 pre-mRNA resulting in a premature stop codon. These studies unravel a novel mechanism for rb1 regulation by a neuronal mRNA splicing factor, usp39. Zebrafish usp39 regulates embryonic pituitary homeostasis by targeting rb1 and e2f4 expression, respectively, contributing to increased adenohypophyseal sensitivity to these altered cell cycle regulators. These results provide a mechanism for dysregulated rb1 and e2f4 pathways that may result in pituitary tumorigenesis.

Al-induced root cell wall chemical components differences of wheat ...

African Journals Online (AJOL)

Root growth is different in plants with different levels of Al-tolerance under Al stress. Cell wall chemical components of root tip cell are related to root growth. The aim of this study was to explore the relationship between root growth difference and cell wall chemical components. For this purpose, the cell wall chemical ...

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

Science.gov (United States)

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.

2D-immunoblotting analysis of Sporothrix schenckii cell wall

Directory of Open Access Journals (Sweden)

Estela Ruiz-Baca

2011-03-01

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

Proteomic analysis of cell walls of two developmental stages of alfalfa stems

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Julian C Verdonk

2012-12-01

Full Text Available Cell walls are important for the growth and development of all plants. They are also valuable resources for feed and fiber, and more recently as a potential feedstock for bioenergy production. Cell wall proteins comprise only a fraction of the cell wall, but play important roles in establishing the walls and in the chemical interactions (e.g. crosslinking of cell wall components. This crosslinking provides structure, but restricts digestibility of cell wall complex carbohydrates, limiting available energy in animal and bioenergy production systems. Manipulation of cell wall proteins could be a strategy to improve digestibility. An analysis of the cell wall proteome of apical alfalfa stems (less mature, more digestible and basal alfalfa stems (more mature, less digestible was conducted using a recently developed low-salt/density gradient method for the isolation of cell walls. Walls were subsequently subjected to a modified extraction utilizing EGTA to remove pectins, followed by a LiCl extraction to isolate more tightly bound proteins. Recovered proteins were identified using shotgun proteomics. We identified 272 proteins in the alfalfa stem cell wall proteome, 153 of which had not previously been identified in cell wall proteomic analyses. Nearly 70% percent of the identified proteins were predicted to be secreted, as would be expected for most cell wall proteins, an improvement over previously published studies using traditional cell wall isolation methods. A comparison of our and several other cell wall proteomic studies indicates little overlap in identified proteins among them, which may be largely due to differences in the tissues used as well as differences in experimental approach.

Mechanical properties of plant cell walls probed by relaxation spectra

DEFF Research Database (Denmark)

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

2011-01-01

Relax, that deduces relaxation spectra from appropriate rheological measurements is presented and made accessible through a Web interface. BayesRelax models the cell wall as a continuum of relaxing elements, and the ability of the method to resolve small differences in cell wall mechanical properties is demonstrated......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...

Enzymatic Modification of Plant Cell Wall Polysaccharides

DEFF Research Database (Denmark)

Øbro, Jens; Hayashi, Takahisa; Mikkelsen, Jørn Dalgaard

2011-01-01

Plant cell walls are intricate structures with remarkable properties, widely used in almost every aspect of our life. Cell walls consist largely of complex polysaccharides and there is often a need for chemical and biochemical processing before industrial use. There is an increasing demand...... for sustainable processes that replace chemical treatments with white biotechnology. Plants can contribute significantly to this sustainable process by producing plant or microbialenzymes in planta that are necessary for plant cell wall modification or total degradation. This will give rise to superior food...... fibres, hydrocolloids, paper,textile, animal feeds or biofuels. Classical microbial-based fermentation systems could in the future face serious competition from plant-based expression systems for enzyme production. Plant expressed enzymes can either be targeted to specific cellular compartments...

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

Science.gov (United States)

Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

2015-01-01

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

An emerging role of pectic rhamnogalacturonanII for cell wall integrity

OpenAIRE

Reboul, Rebecca; Tenhaken, Raimund

2012-01-01

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

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

OpenAIRE

Daniel J. Cosgrove

2016-01-01

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

Engineering cell wall synthesis mechanism for enhanced PHB accumulation in E. coli.

Science.gov (United States)

Zhang, Xing-Chen; Guo, Yingying; Liu, Xu; Chen, Xin-Guang; Wu, Qiong; Chen, Guo-Qiang

2018-01-01

The rigidity of bacterial cell walls synthesized by a complicated pathway limit the cell shapes as coccus, bar or ellipse or even fibers. A less rigid bacterium could be beneficial for intracellular accumulation of poly-3-hydroxybutyrate (PHB) as granular inclusion bodies. To understand how cell rigidity affects PHB accumulation, E. coli cell wall synthesis pathway was reinforced and weakened, respectively. Cell rigidity was achieved by thickening the cell walls via insertion of a constitutive gltA (encoding citrate synthase) promoter in front of a series of cell wall synthesis genes on the chromosome of several E. coli derivatives, resulting in 1.32-1.60 folds increase of Young's modulus in mechanical strength for longer E. coli cells over-expressing fission ring FtsZ protein inhibiting gene sulA. Cell rigidity was weakened by down regulating expressions of ten genes in the cell wall synthesis pathway using CRISPRi, leading to elastic cells with more spaces for PHB accumulation. The regulation on cell wall synthesis changes the cell rigidity: E. coli with thickened cell walls accumulated only 25% PHB while cell wall weakened E. coli produced 93% PHB. Manipulation on cell wall synthesis mechanism adds another possibility to morphology engineering of microorganisms. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Evolution of the cell wall components during terrestrialization

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Alicja Banasiak

2014-12-01

Full Text Available Colonization of terrestrial ecosystems by the first land plants, and their subsequent expansion and diversification, were crucial for the life on the Earth. However, our understanding of these processes is still relatively poor. Recent intensification of studies on various plant organisms have identified the plant cell walls are those structures, which played a key role in adaptive processes during the evolution of land plants. Cell wall as a structure protecting protoplasts and showing a high structural plasticity was one of the primary subjects to changes, giving plants the new properties and capabilities, which undoubtedly contributed to the evolutionary success of land plants. In this paper, the current state of knowledge about some main components of the cell walls (cellulose, hemicelluloses, pectins and lignins and their evolutionary alterations, as preadaptive features for the land colonization and the plant taxa diversification, is summarized. Some aspects related to the biosynthesis and modification of the cell wall components, with particular emphasis on the mechanism of transglycosylation, are also discussed. In addition, new surprising discoveries related to the composition of various cell walls, which change how we perceive their evolution, are presented, such as the presence of lignin in red algae or MLG (1→3,(1→4-β-D-glucan in horsetails. Currently, several new and promising projects, regarding the cell wall, have started, deciphering its structure, composition and metabolism in the evolutionary context. That additional information will allow us to better understand the processes leading to the terrestrialization and the evolution of extant land plants.

Bioinspired metal-cell wall-metal sandwich structure on an individual bacterial cell scaffold.

Science.gov (United States)

Zhang, Xiaoliang; Yu, Mei; Liu, Jianhua; Li, Songmei

2012-08-25

Pd nanoparticles were introduced to individual Bacillus cells and dispersedly anchored on both the inside and outside of the cell walls. The anchored nanoparticles served as "seeds" to drive the formation of double metallic layers forming a metal-cell wall-metal sandwich structure at the single-cell level.

Phenotype-Based Screening of Small Molecules to Modify Plant Cell Walls Using BY-2 Cells.

Science.gov (United States)

Okubo-Kurihara, Emiko; Matsui, Minami

2018-01-01

The plant cell wall is an important and abundant biomass with great potential for use as a modern recyclable resource. For effective utilization of this cellulosic biomass, its ability to degrade efficiently is key point. With the aim of modifying the cell wall to allow easy decomposition, we used chemical biological technology to alter its structure. As a first step toward evaluating the chemicals in the cell wall we employed a phenotype-based approach using high-throughput screening. As the plant cell wall is essential in determining cell morphology, phenotype-based screening is particularly effective in identifying compounds that bring about alterations in the cell wall. For rapid and reproducible screening, tobacco BY-2 cell is an excellent system in which to observe cell morphology. In this chapter, we provide a detailed chemical biological methodology for studying cell morphology using tobacco BY-2 cells.

Tools to Understand Structural Property Relationships for Wood Cell Walls

Science.gov (United States)

Joseph E. Jakes; Daniel J. Yelle; Charles R. Frihart

2011-01-01

Understanding structure-property relationships for wood cell walls has been hindered by the complex polymeric structures comprising these cell walls and the difficulty in assessing meaningful mechanical property measurements of individual cell walls. To help overcome these hindrances, we have developed two experimental methods: 1) two-dimensional solution state nuclear...

The plant cell wall in the feeding sites of cyst nematodes.

Science.gov (United States)

Bohlmann, Holger; Sobczak, Miroslaw

2014-01-01

Plant parasitic cyst nematodes (genera Heterodera and Globodera) are serious pests for many crops. They enter the host roots as migratory second stage juveniles (J2) and migrate intracellularly toward the vascular cylinder using their stylet and a set of cell wall degrading enzymes produced in the pharyngeal glands. They select an initial syncytial cell (ISC) within the vascular cylinder or inner cortex layers to induce the formation of a multicellular feeding site called a syncytium, which is the only source of nutrients for the parasite during its entire life. A syncytium can consist of more than hundred cells whose protoplasts are fused together through local cell wall dissolutions. While the nematode produces a cocktail of cell wall degrading and modifying enzymes during migration through the root, the cell wall degradations occurring during syncytium development are due to the plants own cell wall modifying and degrading proteins. The outer syncytial cell wall thickens to withstand the increasing osmotic pressure inside the syncytium. Furthermore, pronounced cell wall ingrowths can be formed on the outer syncytial wall at the interface with xylem vessels. They increase the surface of the symplast-apoplast interface, thus enhancing nutrient uptake into the syncytium. Processes of cell wall degradation, synthesis and modification in the syncytium are facilitated by a variety of plant proteins and enzymes including expansins, glucanases, pectate lyases and cellulose synthases, which are produced inside the syncytium or in cells surrounding the syncytium.

The plant cell wall in the feeding sites of cyst nematodes

Directory of Open Access Journals (Sweden)

Holger eBohlmann

2014-03-01

Full Text Available Plant parasitic cyst nematodes (genera Heterodera and Globodera are serious pests for many crops. They enter the host roots as migratory second stage juveniles (J2 and migrate intracellularly towards the vascular cylinder using their stylet and a set of cell wall degrading enzymes produced in the pharyngeal glands. They select an initial syncytial cell (ISC within the vascular cylinder or inner cortex layers to induce the formation of a multicellular feeding site called a syncytium, which is the only source of nutrients for the parasite during its entire life. A syncytium can consist of more than hundred cells whose protoplasts are fused together through local cell wall dissolutions. While the nematode produces a cocktail of cell wall degrading and modifying enzymes during migration through the root, the cell wall degradations occurring during syncytium development are due to the plants own cell wall modifying and degrading proteins. The outer syncytial cell wall thickens to withstand the increasing osmotic pressure inside the syncytium. Furthermore, pronounced cell wall ingrowths can be formed on the outer syncytial wall at the interface with xylem vessels. They increase the surface of the symplast-apoplast interface, thus enhancing nutrient uptake into the syncytium. Processes of cell wall degradation, synthesis and modification in the syncytium are facilitated by a variety of plant proteins and enzymes including expansins, glucanases, pectate lyases and cellulose synthases, which are produced inside the syncytium or in cells surrounding the syncytium.

Cell Wall Composition, Biosynthesis and Remodeling during Pollen Tube Growth

Directory of Open Access Journals (Sweden)

Jean-Claude Mollet

2013-03-01

Full Text Available The pollen tube is a fast tip-growing cell carrying the two sperm cells to the ovule allowing the double fertilization process and seed setting. To succeed in this process, the spatial and temporal controls of pollen tube growth within the female organ are critical. It requires a massive cell wall deposition to promote fast pollen tube elongation and a tight control of the cell wall remodeling to modify the mechanical properties. In addition, during its journey, the pollen tube interacts with the pistil, which plays key roles in pollen tube nutrition, guidance and in the rejection of the self-incompatible pollen. This review focuses on our current knowledge in the biochemistry and localization of the main cell wall polymers including pectin, hemicellulose, cellulose and callose from several pollen tube species. Moreover, based on transcriptomic data and functional genomic studies, the possible enzymes involved in the cell wall remodeling during pollen tube growth and their impact on the cell wall mechanics are also described. Finally, mutant analyses have permitted to gain insight in the function of several genes involved in the pollen tube cell wall biosynthesis and their roles in pollen tube growth are further discussed.

Dynamic changes in transcriptome and cell wall composition underlying brassinosteroid-mediated lignification of switchgrass suspension cells.

Science.gov (United States)

Rao, Xiaolan; Shen, Hui; Pattathil, Sivakumar; Hahn, Michael G; Gelineo-Albersheim, Ivana; Mohnen, Debra; Pu, Yunqiao; Ragauskas, Arthur J; Chen, Xin; Chen, Fang; Dixon, Richard A

2017-01-01

Plant cell walls contribute the majority of plant biomass that can be used to produce transportation fuels. However, the complexity and variability in composition and structure of cell walls, particularly the presence of lignin, negatively impacts their deconstruction for bioenergy. Metabolic and genetic changes associated with secondary wall development in the biofuel crop switchgrass ( Panicum virgatum ) have yet to be reported. Our previous studies have established a cell suspension system for switchgrass, in which cell wall lignification can be induced by application of brassinolide (BL). We have now collected cell wall composition and microarray-based transcriptome profiles for BL-induced and non-induced suspension cultures to provide an overview of the dynamic changes in transcriptional reprogramming during BL-induced cell wall modification. From this analysis, we have identified changes in candidate genes involved in cell wall precursor synthesis, cellulose, hemicellulose, and pectin formation and ester-linkage generation. We have also identified a large number of transcription factors with expression correlated with lignin biosynthesis genes, among which are candidates for control of syringyl (S) lignin accumulation. Together, this work provides an overview of the dynamic compositional changes during brassinosteroid-induced cell wall remodeling, and identifies candidate genes for future plant genetic engineering to overcome cell wall recalcitrance.

The receptor-like kinase AtVRLK1 regulates secondary cell wall thickening.

Science.gov (United States)

Huang, Cheng; Zhang, Rui; Gui, Jinshan; Zhong, Yu; Li, Laigeng

2018-04-20

During the growth and development of land plants, some specialized cells, such as tracheary elements, undergo secondary cell wall thickening. Secondary cell walls contain additional lignin, compared with primary cell walls, thus providing mechanical strength and potentially improving defenses against pathogens. However, the molecular mechanisms that initiate wall thickening are unknown. In this study, we identified an Arabidopsis thaliana leucine-rich repeat receptor-like kinase, encoded by AtVRLK1 (Vascular-Related RLK 1), that is specifically expressed in cells undergoing secondary cell wall thickening. Suppression of AtVRLK1expression resulted in a range of phenotypes that included retarded early elongation of the inflorescence stem, shorter fibers, slower root growth, and shorter flower filaments. In contrast, upregulation of AtVRLK1 led to longer fiber cells, reduced secondary cell wall thickening in fiber and vessel cells, and defects in anther dehiscence. Molecular and cellular analyses showed that downregulation of AtVRLK1 promoted secondary cell wall thickening and upregulation of AtVRLK1 enhanced cell elongation and inhibited secondary cell wall thickening. We propose that AtVRLK1 functions as a signaling component in coordinating cell elongation and cell wall thickening during growth and development. {copyright, serif} 2018 American Society of Plant Biologists. All rights reserved.

Evidence for differentiation of cell wall poles in Bacillus subtilis

International Nuclear Information System (INIS)

Sonnenfeld, E.M.

1985-01-01

Previous data have suggested that the chromosome of Bacillus subtilis was found to the cell surface at polar regions. A significant corollary of DNA attachment to cell poles is the role of the cell wall in chromosome segregation. This project was mainly concerned with visualizing the DNA-cell wall association through autoradiography. The origin and terminus of replication were labelled with ( 3 H)-thymidine using a temperature-sensitive DNA initiation mutant. It was found that most of the radioactivity was associated with cell poles. Ultrastructural analyses of cell walls stained with dilute cationized ferritin showed that the polar area contained a site of dense electronegativity. It is not immediately apparent why cell wall poles would contain an area with a high concentration of negative charge. This finding may be related to the cell pole functioning as the site of chromosome attachment. An additional observation encountered in this study was that cell wall exhibited asymmetry with regard to negative charge, the outside surface being more electronegative than the inside. A significant consequence of this finding is that both teichoic acid and muramyl peptides are situated perpendicularly to the cell surface. This favored arrangement may facilitate cell separation during the division process due to opposition of like charges at septa. The results of this work provide further convincing evidence that the cell wall of B. subtilis is differentiated

Hemicellulose biosynthesis and degradation in tobacco cell walls

NARCIS (Netherlands)

Compier, M.G.M.

2005-01-01

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

Binding of 18F by cell membranes and cell walls of Streptococcus mutans

International Nuclear Information System (INIS)

Yotis, W.W.; Zeb, M.; McNulty, J.; Kirchner, F.; Reilly, C.; Glendenin, L.

1983-01-01

The binding of 18 F to isolated cell membranes and cell walls of Streptococcus mutans GS-5 or other bacteria was assayed. The attachment of 18 F to these cell envelopes proceeded slowly and reached equilibrium within 60 min. 18 F binding was stimulated by Ca 2+ (1 mM). The binding of 18 F to cellular components was dependent upon the pH, as well as the amount of 18 F and dose of the binder employed. The binding of 18 F by cell walls prepared from fluoride-sensitive and fluoride-resistant cells of S. salivarius and S. mutans did not differ significantly. The pretreatment of cell walls or cell membranes for 60 min at 30 degrees C with 1 mg of RNase, DNase, or trypsin per ml did not influence the binding of 18 F by the walls and membranes of S. mutans GS-5. However, prior exposure of cell membranes to sodium dodecyl sulfate caused a significant reduction in the number of 18 F atoms bound by the membranes. In saturated assay systems, cell membranes of S. mutans GS-5 bound 10(15) to 10(16) atoms of 18 F per mg (dry weight), whereas cell walls from S. mutans GS-5, FA-1, and HS-6 or Actinomyces viscosus T14V and T14AV bound 10(12) to 10(13) atoms of 18 F per mg (dry weight). 18 F in this quantity (10(12) to 10(13) atoms) cannot be detected with the fluoride electrode. The data provide, for the first time, a demonstration of 18 F binding by cell membranes and walls of oral flora

Enzymes and other agents that enhance cell wall extensibility

Science.gov (United States)

Cosgrove, D. J.

1999-01-01

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

DPL-1 DP, LIN-35 Rb and EFL-1 E2F act with the MCD-1 zinc-finger protein to promote programmed cell death in Caenorhabditis elegans.

Science.gov (United States)

Reddien, Peter W; Andersen, Erik C; Huang, Michael C; Horvitz, H Robert

2007-04-01

The genes egl-1, ced-9, ced-4, and ced-3 play major roles in programmed cell death in Caenorhabditis elegans. To identify genes that have more subtle activities, we sought mutations that confer strong cell-death defects in a genetically sensitized mutant background. Specifically, we screened for mutations that enhance the cell-death defects caused by a partial loss-of-function allele of the ced-3 caspase gene. We identified mutations in two genes not previously known to affect cell death, dpl-1 and mcd-1 (modifier of cell death). dpl-1 encodes the C. elegans homolog of DP, the human E2F-heterodimerization partner. By testing genes known to interact with dpl-1, we identified roles in cell death for four additional genes: efl-1 E2F, lin-35 Rb, lin-37 Mip40, and lin-52 dLin52. mcd-1 encodes a novel protein that contains one zinc finger and that is synthetically required with lin-35 Rb for animal viability. dpl-1 and mcd-1 act with efl-1 E2F and lin-35 Rb to promote programmed cell death and do so by regulating the killing process rather than by affecting the decision between survival and death. We propose that the DPL-1 DP, MCD-1 zinc finger, EFL-1 E2F, LIN-35 Rb, LIN-37 Mip40, and LIN-52 dLin52 proteins act together in transcriptional regulation to promote programmed cell death.

RB975242 and RB975201 - Late maturation sugarcane varieties

Directory of Open Access Journals (Sweden)

Monalisa Sampaio Carneiro

2016-11-01

Full Text Available The sugarcane varieties RB975201 and RB975242 were developed and released for harvest at the end of the season (late maturation in the CentralSouth region of Brazil. In specific environments, these varieties were compared with commercial standards in sugar yield per area. They are resistant to major sugarcane diseases and present the Bru1 gene of resistance to brown rust.

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

Directory of Open Access Journals (Sweden)

Ying Luo

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

Structural analysis of cell wall polysaccharides using PACE

Energy Technology Data Exchange (ETDEWEB)

Mortimer, Jennifer C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Institute

2017-01-01

The plant cell wall is composed of many complex polysaccharides. The composition and structure of the polysaccharides affect various cell properties including cell shape, cell function and cell adhesion. Many techniques to characterize polysaccharide structure are complicated, requiring expensive equipment and specialized operators e.g. NMR, MALDI-MS. PACE (Polysaccharide Analysis using Carbohydrate gel Electrophoresis) uses a simple, rapid technique to analyze polysaccharide quantity and structure (Goubet et al. 2002). Whilst the method here describes xylan analysis, it can be applied (by use of the appropriate glycosyl hydrolase) to any cell wall polysaccharide.

Isolation of a novel cell wall architecture mutant of rice with defective Arabidopsis COBL4 ortholog BC1 required for regulated deposition of secondary cell wall components.

Science.gov (United States)

Sato, Kanna; Suzuki, Ryu; Nishikubo, Nobuyuki; Takenouchi, Sachi; Ito, Sachiko; Nakano, Yoshimi; Nakaba, Satoshi; Sano, Yuzou; Funada, Ryo; Kajita, Shinya; Kitano, Hidemi; Katayama, Yoshihiro

2010-06-01

The plant secondary cell wall is a highly ordered structure composed of various polysaccharides, phenolic components and proteins. Its coordinated regulation of a number of complex metabolic pathways and assembly has not been resolved. To understand the molecular mechanisms that regulate secondary cell wall synthesis, we isolated a novel rice mutant, cell wall architecture1 (cwa1), that exhibits an irregular thickening pattern in the secondary cell wall of sclerenchyma, as well as culm brittleness and reduced cellulose content in mature internodes. Light and transmission electron microscopy revealed that the cwa1 mutant plant has regions of local aggregation in the secondary cell walls of the cortical fibers in its internodes, showing uneven thickness. Ultraviolet microscopic observation indicated that localization of cell wall phenolic components was perturbed and that these components abundantly deposited at the aggregated cell wall regions in sclerenchyma. Therefore, regulation of deposition and assembly of secondary cell wall materials, i.e. phenolic components, appear to be disturbed by mutation of the cwa1 gene. Genetic analysis showed that cwa1 is allelic to brittle culm1 (bc1), which encodes the glycosylphosphatidylinositol-anchored COBRA-like protein specifically in plants. BC1 is known as a regulator that controls the culm mechanical strength and cellulose content in the secondary cell walls of sclerenchyma, but the precise function of BC1 has not been resolved. Our results suggest that CWA1/BC1 has an essential role in assembling cell wall constituents at their appropriate sites, thereby enabling synthesis of solid and flexible internodes in rice.

Endotoxins, Glucans and Other Microbial Cell Wall Agents

NARCIS (Netherlands)

Basinas, Ioannis; Elholm, Grethe; Wouters, Inge M.

2017-01-01

During the last decades an increasing interest in microbial cell wall agents has been established, since exposure to these agents has been linked to a wide range of adverse and beneficial health effects. The term microbial cell wall agents refers to a group of molecules of different composition that

Characterising the cellulose synthase complexes of cell walls

NARCIS (Netherlands)

Mansoori Zangir, N.

2012-01-01

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

Magnetic field exposure stiffens regenerating plant protoplast cell walls.

Science.gov (United States)

Haneda, Toshihiko; Fujimura, Yuu; Iino, Masaaki

2006-02-01

Single suspension-cultured plant cells (Catharanthus roseus) and their protoplasts were anchored to a glass plate and exposed to a magnetic field of 302 +/- 8 mT for several hours. Compression forces required to produce constant cell deformation were measured parallel to the magnetic field by means of a cantilever-type force sensor. Exposure of intact cells to the magnetic field did not result in any changes within experimental error, while exposure of regenerating protoplasts significantly increased the measured forces and stiffened regenerating protoplasts. The diameters of intact cells or regenerating protoplasts were not changed after exposure to the magnetic field. Measured forces for regenerating protoplasts with and without exposure to the magnetic field increased linearly with incubation time, with these forces being divided into components based on the elasticity of synthesized cell walls and cytoplasm. Cell wall synthesis was also measured using a cell wall-specific fluorescent dye, and no changes were noted after exposure to the magnetic field. Analysis suggested that exposure to the magnetic field roughly tripled the Young's modulus of the newly synthesized cell wall without any lag.

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

Science.gov (United States)

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

2016-07-01

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. © FEMS 2016.

RhoE interferes with Rb inactivation and regulates the proliferation and survival of the U87 human glioblastoma cell line

International Nuclear Information System (INIS)

Poch, Enric; Minambres, Rebeca; Mocholi, Enric; Ivorra, Carmen; Perez-Arago, Amparo; Guerri, Consuelo; Perez-Roger, Ignacio; Guasch, Rosa M.

2007-01-01

Rho GTPases are important regulators of actin cytoskeleton, but they are also involved in cell proliferation, transformation and oncogenesis. One of this proteins, RhoE, inhibits cell proliferation, however the mechanism that regulates this effect remains poorly understood. Therefore, we undertook the present study to determine the role of RhoE in the regulation of cell proliferation. For this purpose we generated an adenovirus system to overexpress RhoE in U87 glioblastoma cells. Our results show that RhoE disrupts actin cytoskeleton organization and inhibits U87 glioblastoma cell proliferation. Importantly, RhoE expressing cells show a reduction in Rb phosphorylation and in cyclin D1 expression. Furthermore, RhoE inhibits ERK activation following serum stimulation of quiescent cells. Based in these findings, we propose that RhoE inhibits ERK activation, thereby decreasing cyclin D1 expression and leading to a reduction in Rb inactivation, and that this mechanism is involved in the RhoE-induced cell growth inhibition. Moreover, we also demonstrate that RhoE induces apoptosis in U87 cells and also in colon carcinoma and melanoma cells. These results indicate that RhoE plays an important role in the regulation of cell proliferation and survival, and suggest that this protein may be considered as an oncosupressor since it is capable to induce apoptosis in several tumor cell lines

PDGFRα depletion attenuates glioblastoma stem cells features by modulation of STAT3, RB1 and multiple oncogenic signals.

Science.gov (United States)

Cenciarelli, Carlo; Marei, Hany E; Felsani, Armando; Casalbore, Patrizia; Sica, Gigliola; Puglisi, Maria Ausiliatrice; Cameron, Angus J M; Olivi, Alessandro; Mangiola, Annunziato

2016-08-16

Platelet derived growth factor receptors (PDGFRs) play an important role in tumor pathogenesis, and they are frequently overexpressed in glioblastoma (GBM). Earlier we have shown a higher protein expression of PDGFR isoforms (α and β) in peritumoral-tissue derived cancer stem cells (p-CSC) than in tumor core (c-CSC) of several GBM affected patients. In the current study, in order to assess the activity of PDGFRα/PDGF-AA signaling axis, we performed time course experiments to monitor the effects of exogenous PDGF-AA on the expression of downstream target genes in c-CSC vs p-CSC. Interestingly, in p-CSC we detected the upregulation of Y705-phosphorylated Stat3, concurrent with a decrement of Rb1 protein in its active state, within minutes of PDGF-AA addition. This finding prompted us to elucidate the role of PDGFRα in self-renewal, invasion and differentiation in p-CSC by using short hairpin RNA depletion of PDGFRα expression. Notably, in PDGFRα-depleted cells, protein analysis revealed attenuation of stemness-related and glial markers expression, alongside early activation of the neuronal marker MAP2a/b that correlated with the induction of tumor suppressor Rb1. The in vitro reduction of the invasive capacity of PDGFRα-depleted CSC as compared to parental cells correlated with the downmodulation of markers of epithelial-mesenchymal transition phenotype and angiogenesis. Surprisingly, we observed the induction of anti-apoptotic proteins and compensatory oncogenic signals such as EDN1, EDNRB, PRKCB1, PDGF-C and PDGF-D. To conclude, we hypothesize that the newly discovered PDGFRα/Stat3/Rb1 regulatory axis might represent a potential therapeutic target for GBM treatment.

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

Science.gov (United States)

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

Characterizing visible and invisible cell wall mutant phenotypes

Energy Technology Data Exchange (ETDEWEB)

Carpita, Nicholas C.; McCann, Maureen C.

2015-04-06

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.

Genome-wide analysis of cell wall-related genes in Tuber melanosporum.

Science.gov (United States)

Balestrini, Raffaella; Sillo, Fabiano; Kohler, Annegret; Schneider, Georg; Faccio, Antonella; Tisserant, Emilie; Martin, Francis; Bonfante, Paola

2012-06-01

A genome-wide inventory of proteins involved in cell wall synthesis and remodeling has been obtained by taking advantage of the recently released genome sequence of the ectomycorrhizal Tuber melanosporum black truffle. Genes that encode cell wall biosynthetic enzymes, enzymes involved in cell wall polysaccharide synthesis or modification, GPI-anchored proteins and other cell wall proteins were identified in the black truffle genome. As a second step, array data were validated and the symbiotic stage was chosen as the main focus. Quantitative RT-PCR experiments were performed on 29 selected genes to verify their expression during ectomycorrhizal formation. The results confirmed the array data, and this suggests that cell wall-related genes are required for morphogenetic transition from mycelium growth to the ectomycorrhizal branched hyphae. Labeling experiments were also performed on T. melanosporum mycelium and ectomycorrhizae to localize cell wall components.

Pea Border Cell Maturation and Release Involve Complex Cell Wall Structural Dynamics1[OPEN

Science.gov (United States)

2017-01-01

The adhesion of plant cells is vital for support and protection of the plant body and is maintained by a variety of molecular associations between cell wall components. In some specialized cases, though, plant cells are programmed to detach, and root cap-derived border cells are examples of this. Border cells (in some species known as border-like cells) provide an expendable barrier between roots and the environment. Their maturation and release is an important but poorly characterized cell separation event. To gain a deeper insight into the complex cellular dynamics underlying this process, we undertook a systematic, detailed analysis of pea (Pisum sativum) root tip cell walls. Our study included immunocarbohydrate microarray profiling, monosaccharide composition determination, Fourier-transformed infrared microspectroscopy, quantitative reverse transcription-PCR of cell wall biosynthetic genes, analysis of hydrolytic activities, transmission electron microscopy, and immunolocalization of cell wall components. Using this integrated glycobiology approach, we identified multiple novel modes of cell wall structural and compositional rearrangement during root cap growth and the release of border cells. Our findings provide a new level of detail about border cell maturation and enable us to develop a model of the separation process. We propose that loss of adhesion by the dissolution of homogalacturonan in the middle lamellae is augmented by an active biophysical process of cell curvature driven by the polarized distribution of xyloglucan and extensin epitopes. PMID:28400496

Discovery of novel cell wall-active compounds using P ywaC, a sensitive reporter of cell wall stress, in the model gram-positive bacterium Bacillus subtilis.

Science.gov (United States)

Czarny, T L; Perri, A L; French, S; Brown, E D

2014-06-01

The emergence of antibiotic resistance in recent years has radically reduced the clinical efficacy of many antibacterial treatments and now poses a significant threat to public health. One of the earliest studied well-validated targets for antimicrobial discovery is the bacterial cell wall. The essential nature of this pathway, its conservation among bacterial pathogens, and its absence in human biology have made cell wall synthesis an attractive pathway for new antibiotic drug discovery. Herein, we describe a highly sensitive screening methodology for identifying chemical agents that perturb cell wall synthesis, using the model of the Gram-positive bacterium Bacillus subtilis. We report on a cell-based pilot screen of 26,000 small molecules to look for cell wall-active chemicals in real time using an autonomous luminescence gene cluster driven by the promoter of ywaC, which encodes a guanosine tetra(penta)phosphate synthetase that is expressed under cell wall stress. The promoter-reporter system was generally much more sensitive than growth inhibition testing and responded almost exclusively to cell wall-active antibiotics. Follow-up testing of the compounds from the pilot screen with secondary assays to verify the mechanism of action led to the discovery of 9 novel cell wall-active compounds. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Mechanical feedback coordinates cell wall expansion and assembly in yeast mating morphogenesis

Science.gov (United States)

2018-01-01

The shaping of individual cells requires a tight coordination of cell mechanics and growth. However, it is unclear how information about the mechanical state of the wall is relayed to the molecular processes building it, thereby enabling the coordination of cell wall expansion and assembly during morphogenesis. Combining theoretical and experimental approaches, we show that a mechanical feedback coordinating cell wall assembly and expansion is essential to sustain mating projection growth in budding yeast (Saccharomyces cerevisiae). Our theoretical results indicate that the mechanical feedback provided by the Cell Wall Integrity pathway, with cell wall stress sensors Wsc1 and Mid2 increasingly activating membrane-localized cell wall synthases Fks1/2 upon faster cell wall expansion, stabilizes mating projection growth without affecting cell shape. Experimental perturbation of the osmotic pressure and cell wall mechanics, as well as compromising the mechanical feedback through genetic deletion of the stress sensors, leads to cellular phenotypes that support the theoretical predictions. Our results indicate that while the existence of mechanical feedback is essential to stabilize mating projection growth, the shape and size of the cell are insensitive to the feedback. PMID:29346368

Tet1 is required for Rb phosphorylation during G1/S phase transition

International Nuclear Information System (INIS)

Huang, Shengsong; Zhu, Ziqi; Wang, Yiqin; Wang, Yanru; Xu, Longxia; Chen, Xuemei; Xu, Qing; Zhang, Qimin; Zhao, Xin; Yu, Yi; Wu, Denglong

2013-01-01

Highlights: •Tet1 was required for NIT3T3 proliferation. •Tet1 depletion inhibited G1-S entry. •Cyclin D1 accumulation and Rb phosphorylation was blocked by Tet1 knockdown. -- Abstract: DNA methylation plays an important role in many biological processes, including regulation of gene expression, maintenance of chromatin conformation and genomic stability. TET-family proteins convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), which indicates that these enzymes may participate in DNA demethylation. The function of TET1 has not yet been well characterized in somatic cells. Here, we show that depletion of Tet1 in NIH3T3 cells inhibits cell growth. Furthermore, Tet1 knockdown blocks cyclin D1 accumulation in G1 phase, inhibits Rb phosphorylation and consequently delays entrance to G1/S phase. Taken together, this study demonstrates that Tet1 is required for cell proliferation and that this process is mediated through the Rb pathway

Brassinosteroid Mediated Cell Wall Remodeling in Grasses under Abiotic Stress

Directory of Open Access Journals (Sweden)

Xiaolan Rao

2017-05-01

Full Text Available Unlike animals, plants, being sessile, cannot escape from exposure to severe abiotic stresses such as extreme temperature and water deficit. The dynamic structure of plant cell wall enables them to undergo compensatory changes, as well as maintain physical strength, with changing environments. Plant hormones known as brassinosteroids (BRs play a key role in determining cell wall expansion during stress responses. Cell wall deposition differs between grasses (Poaceae and dicots. Grass species include many important food, fiber, and biofuel crops. In this article, we focus on recent advances in BR-regulated cell wall biosynthesis and remodeling in response to stresses, comparing our understanding of the mechanisms in grass species with those in the more studied dicots. A more comprehensive understanding of BR-mediated changes in cell wall integrity in grass species will benefit the development of genetic tools to improve crop productivity, fiber quality and plant biomass recalcitrance.

Assembly and enlargement of the primary cell wall in plants

Science.gov (United States)

Cosgrove, D. J.

1997-01-01

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

The Cell Wall of Bacillus subtilis

NARCIS (Netherlands)

Scheffers, Dirk-Jan; Graumann, Peter

2012-01-01

The cell wall of Bacillus subtilis is a rigid structure on the outside of the cell that forms the first barrier between the bacterium and the environment, and at the same time maintains cell shape and withstands the pressure generated by the cell’s turgor. In this chapter, the chemical composition

The Cell Wall-Associated Proteins in the Dimorphic Pathogenic Species of Paracoccidioides.

Science.gov (United States)

Puccia, Rosana; Vallejo, Milene C; Longo, Larissa V G

2017-01-01

Paracoccidioides brasiliensis and P. lutzii cause human paracoccidioidomycosis (PCM). They are dimorphic ascomycetes that grow as filaments at mild temperatures up to 28oC and as multibudding pathogenic yeast cells at 37oC. Components of the fungal cell wall have an important role in the interaction with the host because they compose the cell outermost layer. The Paracoccidioides cell wall is composed mainly of polysaccharides, but it also contains proportionally smaller rates of proteins, lipids, and melanin. The polysaccharide cell wall composition and structure of Paracoccidioides yeast cells, filamentous and transition phases were studied in detail in the past. Other cell wall components have been better analyzed in the last decades. The present work gives to the readers a detailed updated view of cell wall-associated proteins. Proteins that have been localized at the cell wall compartment using antibodies are individually addressed. We also make an overview about PCM, the Paracoccidioides cell wall structure, secretion mechanisms, and fungal extracellular vesicles. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Employing proteomic analysis to compare Paracoccidioides lutzii yeast and mycelium cell wall proteins.

Science.gov (United States)

Araújo, Danielle Silva; de Sousa Lima, Patrícia; Baeza, Lilian Cristiane; Parente, Ana Flávia Alves; Melo Bailão, Alexandre; Borges, Clayton Luiz; de Almeida Soares, Célia Maria

2017-11-01

Paracoccidioidomycosis is an important systemic mycosis caused by thermodimorphic fungi of the Paracoccidioides genus. During the infective process, the cell wall acts at the interface between the fungus and the host. In this way, the cell wall has a key role in growth, environment sensing and interaction, as well as morphogenesis of the fungus. Since the cell wall is absent in mammals, it may present molecules that are described as target sites for new antifungal drugs. Despite its importance, up to now few studies have been conducted employing proteomics in for the identification of cell wall proteins in Paracoccidioides spp. Here, a detailed proteomic approach, including cell wall-fractionation coupled to NanoUPLC-MS E , was used to study and compare the cell wall fractions from Paracoccidioides lutzii mycelia and yeast cells. The analyzed samples consisted of cell wall proteins extracted by hot SDS followed by extraction by mild alkali. In summary, 512 proteins constituting different cell wall fractions were identified, including 7 predicted GPI-dependent cell wall proteins that are potentially involved in cell wall metabolism. Adhesins previously described in Paracoccidioides spp. such as enolase, glyceraldehyde-3-phosphate dehydrogenase were identified. Comparing the proteins in mycelium and yeast cells, we detected some that are common to both fungal phases, such as Ecm33, and some specific proteins, as glucanase Crf1. All of those proteins were described in the metabolism of cell wall. Our study provides an important elucidation of cell wall composition of fractions in Paracoccidioides, opening a way to understand the fungus cell wall architecture. Copyright © 2017 Elsevier B.V. All rights reserved.

Advanced technologies for plant cell wall evolution and diversity

DEFF Research Database (Denmark)

Fangel, Jonatan Ulrik

Plant cell walls consist of polysaccharides, glycoproteins and phenolic polymers interlinked together in a highly complex network. The detailed analysis of cell walls is challenging because of their inherent complexity and heterogeneity. Also, complex carbohydrates, unlike proteins and nucleotides...... cannot really be synthesised or sequenced. The work described in this thesis is focused to a large extent on the development of a microarray-based high-throughput method for cell wall analysis known as Comprehensive microarray polymer profiling or CoMPP. The procedure uses highly specific molecular...... probes (monoclonal antibodies mAbs and carbohydrate binding modules, CBMs) to rapidly profile polysaccharides across a sample set. During my PhD I have further developed the CoMPP technique and used it for cell wall analysis within the context of a variety of applied and fundamental projects. The data...

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

NARCIS (Netherlands)

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

2002-01-01

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

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

Directory of Open Access Journals (Sweden)

Aymerick Eudes

2016-07-01

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

The Role of RB in the Therapeutic Response of Breast Cancer

National Research Council Canada - National Science Library

Bosco, Emily E

2005-01-01

The retinoblastoma tumor suppressor protein (RB) participates in the growth regulation of breast cancer cells by controlling G-S phase progression and mediating cell cycle arrest in response to anti-mitogenic signaling...

Final report on the IAEA research contracts No. 1194/RB, 1194/R1/RB and 1194/R2/RB

International Nuclear Information System (INIS)

Zobor, E.; Janosy, J.S.; Szentgali, A.

1980-09-01

The final report summarizes the research activities made in the framework of the IAEA Research Contracts No. 1194/RB, 1194/R1/RB and 1194/R2/RB. A multilevel hierarchical control system is treated which uses weakly-coupled low dimensional subsystems under the supervision of a dynamic coordinator program. This self-organizing adaptive control system was checked by a 5 MW research reactor. As an example the paper describes the experimental computer control system of the 5 MW WWR-SM research reactor, where the reactor power and outlet temperature have been controlled on the basis of the treated control concept since 1978. (author)

Optimization of degradation of Reactive Black 5 (RB5) and electricity generation in solar photocatalytic fuel cell system.

Science.gov (United States)

Khalik, Wan Fadhilah; Ho, Li-Ngee; Ong, Soon-An; Voon, Chun-Hong; Wong, Yee-Shian; Yusoff, NikAthirah; Lee, Sin-Li; Yusuf, Sara Yasina

2017-10-01

The photocatalytic fuel cell (PFC) system was developed in order to study the effect of several operating parameters in degradation of Reactive Black 5 (RB5) and its electricity generation. Light irradiation, initial dye concentration, aeration, pH and cathode electrode are the operating parameters that might give contribution in the efficiency of PFC system. The degradation of RB5 depends on the presence of light irradiation and solar light gives better performance to degrade the azo dye. The azo dye with low initial concentration decolorizes faster compared to higher initial concentration and presence of aeration in PFC system would enhance its performance. Reactive Black 5 rapidly decreased at higher pH due to the higher amount of OH generated at higher pH and Pt-loaded carbon (Pt/C) was more suitable to be used as cathode in PFC system compared to Cu foil and Fe foil. The rapid decolorization of RB5 would increase their voltage output and in addition, it would also increase their V oc , J sc and P max . The breakage of azo bond and aromatic rings was confirmed through UV-Vis spectrum and COD analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

Cosgrove, D. J.

1993-01-01

Expansive growth of plant cells is controlled principally by processes that loosen the wall and enable it to expand irreversibly. The central role of wall relaxation for cell expansion is reviewed. The most common methods for assessing the extension properties of plant cell walls ( wall extensibility') are described, categorized and assessed critically. What emerges are three fundamentally different approaches which test growing cells for their ability (a) to enlarge at different values of turgor, (b) to induce wall relaxation, and (c) to deform elastically or plastically in response to an applied tensile force. Analogous methods with isolated walls are similarly reviewed. The results of these different assays are related to the nature of plant cell growth and pertinent biophysical theory. I argue that the extensibilities' measured by these assays are fundamentally different from one another and that some are more pertinent to growth than others.

Immunogold scanning electron microscopy can reveal the polysaccharide architecture of xylem cell walls

Science.gov (United States)

Sun, Yuliang; Juzenas, Kevin

2017-01-01

Abstract Immunofluorescence microscopy (IFM) and immunogold transmission electron microscopy (TEM) are the two main techniques commonly used to detect polysaccharides in plant cell walls. Both are important in localizing cell wall polysaccharides, but both have major limitations, such as low resolution in IFM and restricted sample size for immunogold TEM. In this study, we have developed a robust technique that combines immunocytochemistry with scanning electron microscopy (SEM) to study cell wall polysaccharide architecture in xylem cells at high resolution over large areas of sample. Using multiple cell wall monoclonal antibodies (mAbs), this immunogold SEM technique reliably localized groups of hemicellulosic and pectic polysaccharides in the cell walls of five different xylem structures (vessel elements, fibers, axial and ray parenchyma cells, and tyloses). This demonstrates its important advantages over the other two methods for studying cell wall polysaccharide composition and distribution in these structures. In addition, it can show the three-dimensional distribution of a polysaccharide group in the vessel lateral wall and the polysaccharide components in the cell wall of developing tyloses. This technique, therefore, should be valuable for understanding the cell wall polysaccharide composition, architecture and functions of diverse cell types. PMID:28398585

N-acetylglucosamine affects Cryptococcus neoformans cell-wall composition and melanin architecture.

Science.gov (United States)

Camacho, Emma; Chrissian, Christine; Cordero, Radames J B; Liporagi-Lopes, Livia; Stark, Ruth E; Casadevall, Arturo

2017-11-01

Cryptococcus neoformans is an environmental fungus that belongs to the phylum Basidiomycetes and is a major pathogen in immunocompromised patients. The ability of C. neoformans to produce melanin pigments represents its second most important virulence factor, after the presence of a polysaccharide capsule. Both the capsule and melanin are closely associated with the fungal cell wall, a complex structure that is essential for maintaining cell morphology and viability under conditions of stress. The amino sugar N-acetylglucosamine (GlcNAc) is a key constituent of the cell-wall chitin and is used for both N-linked glycosylation and GPI anchor synthesis. Recent studies have suggested additional roles for GlcNAc as an activator and mediator of cellular signalling in fungal and plant cells. Furthermore, chitin and chitosan polysaccharides interact with melanin pigments in the cell wall and have been found to be essential for melanization. Despite the importance of melanin, its molecular structure remains unresolved; however, we previously obtained critical insights using advanced nuclear magnetic resonance (NMR) and imaging techniques. In this study, we investigated the effect of GlcNAc supplementation on cryptococcal cell-wall composition and melanization. C. neoformans was able to metabolize GlcNAc as a sole source of carbon and nitrogen, indicating a capacity to use a component of a highly abundant polymer in the biospherenutritionally. C. neoformans cells grown with GlcNAc manifested changes in the chitosan cell-wall content, cell-wall thickness and capsule size. Supplementing cultures with isotopically 15 N-labelled GlcNAc demonstrated that the exogenous monomer serves as a building block for chitin/chitosan and is incorporated into the cell wall. The altered chitin-to-chitosan ratio had no negative effects on the mother-daughter cell separation; growth with GlcNAc affected the fungal cell-wall scaffold, resulting in increased melanin deposition and assembly. In

Next generation sequencing of Cytokeratin 20-negative Merkel cell carcinoma reveals ultraviolet-signature mutations and recurrent TP53 and RB1 inactivation.

Science.gov (United States)

Harms, Paul W; Collie, Angela M B; Hovelson, Daniel H; Cani, Andi K; Verhaegen, Monique E; Patel, Rajiv M; Fullen, Douglas R; Omata, Kei; Dlugosz, Andrzej A; Tomlins, Scott A; Billings, Steven D

2016-03-01

Merkel cell carcinoma is a rare but highly aggressive cutaneous neuroendocrine carcinoma. Cytokeratin 20 (CK20) is expressed in ~95% of Merkel cell carcinomas and is useful for distinction from morphologically similar entities including metastatic small-cell lung carcinoma. Lack of CK20 expression may make diagnosis of Merkel cell carcinoma more challenging, and has unknown biological significance. Approximately 80% of CK20-positive Merkel cell carcinomas are associated with the oncogenic Merkel cell polyomavirus. Merkel cell carcinomas lacking Merkel cell polyomavirus display distinct genetic changes from Merkel cell polyomavirus-positive Merkel cell carcinoma, including RB1 inactivating mutations. Unlike CK20-positive Merkel cell carcinoma, the majority of CK20-negative Merkel cell carcinomas are Merkel cell polyomavirus-negative, suggesting CK20-negative Merkel cell carcinomas predominantly arise through virus-independent pathway(s) and may harbor additional genetic differences from conventional Merkel cell carcinoma. Hence, we analyzed 15 CK20-negative Merkel cell carcinoma tumors (10 Merkel cell polyomavirus-negative, four Merkel cell polyomavirus-positive, and one undetermined) using the Ion Ampliseq Comprehensive Cancer Panel, which assesses copy number alterations and mutations in 409 cancer-relevant genes. Twelve tumors displayed prioritized high-level chromosomal gains or losses (average 1.9 per tumor). Non-synonymous high-confidence somatic mutations were detected in 14 tumors (average 11.9 per tumor). Assessing all somatic coding mutations, an ultraviolet-signature mutational profile was present, and more prevalent in Merkel cell polyomavirus-negative tumors. Recurrent deleterious tumor suppressor mutations affected TP53 (9/15, 60%), RB1 (3/15, 20%), and BAP1 (2/15, 13%). Oncogenic activating mutations included PIK3CA (3/15, 20%), AKT1 (1/15, 7%) and EZH2 (1/15, 7%). In conclusion, CK20-negative Merkel cell carcinoma display overlapping genetic changes

Next Generation Sequencing of Cytokeratin 20-Negative Merkel Cell Carcinoma Reveals Ultraviolet Signature Mutations and Recurrent TP53 and RB1 Inactivation

Science.gov (United States)

Harms, Paul W.; Collie, Angela M. B.; Hovelson, Daniel H.; Cani, Andi K.; Verhaegen, Monique E.; Patel, Rajiv M.; Fullen, Douglas R.; Omata, Kei; Dlugosz, Andrzej A.; Tomlins, Scott A.; Billings, Steven D.

2016-01-01

Merkel cell carcinoma is a rare but highly aggressive cutaneous neuroendocrine carcinoma. Cytokeratin-20 (CK20) is expressed in approximately 95% of Merkel cell carcinomas and is useful for distinction from morphologically similar entities including metastatic small cell lung carcinoma. Lack of CK20 expression may make diagnosis of Merkel cell carcinoma more challenging, and has unknown biological significance. Approximately 80% of CK20-positive Merkel cell carcinomas are associated with the oncogenic Merkel cell polyomavirus. Merkel cell carcinomas lacking Merkel cell polyomavirus display distinct genetic changes from Merkel cell polyomavirus-positive Merkel cell carcinoma, including RB1 inactivating mutations. Unlike CK20-positive Merkel cell carcinoma, the majority of CK20-negative Merkel cell carcinomas are Merkel cell polyomavirus-negative, suggesting CK20-negative Merkel cell carcinomas predominantly arise through virus-independent pathway(s) and may harbor additional genetic differences from conventional Merkel cell carcinoma. Hence, we analyzed 15 CK20-negative Merkel cell carcinoma tumors (ten Merkel cell polyomavirus-negative, four Merkel cell polyomavirus-positive, and one undetermined) using the Ion Ampliseq Comprehensive Cancer Panel, which assesses copy number alterations and mutations in 409 cancer-relevant genes. Twelve tumors displayed prioritized high-level chromosomal gains or losses (average 1.9 per tumor). Non-synonymous high confidence somatic mutations were detected in 14 tumors (average 11.9 per tumor). Assessing all somatic coding mutations, an ultraviolet-signature mutational profile was present, and more prevalent in Merkel cell polyomavirus-negative tumors. Recurrent deleterious tumor suppressor mutations affected TP53 (9/15, 60%), RB1 (3/15, 20%), and BAP1 (2/15, 13%). Oncogenic activating mutations included PIK3CA (3/15, 20%), AKT1 (1/15, 7%)) and EZH2 (1/15, 7%). In conclusion, CK20-negative Merkel cell carcinoma display overlapping

Processive motions of MreB micro-filaments coordinate cell wall growth

Science.gov (United States)

Garner, Ethan

2012-02-01

Rod-shaped bacteria elongate by the action of cell-wall synthesis complexes linked to underlying dynamic MreB filaments, but how these proteins function to allow continued elongation as a rod remains unknown. To understand how the movement of these filaments relates to cell wall synthesis, we characterized the dynamics of MreB and the cell wall elongation machinery using high-resolution particle tracking in Bacillus subtilis. We found that both MreB and the elongation machinery move in linear paths across the cell, moving at similar rates (˜20nm / second) and angles to the cell body, suggesting they function as single complexes. These proteins move circumferentially around the cell, principally perpendicular to its length. We find that the motions of these complexes are independent, as they can pause and reverse,and also as nearby complexes move independently in both directions across one surface of the cell. Inhibition of cell wall synthesis with antibiotics or depletions in the cell wall synthesis machinery blocked MreB movement, suggesting that the cell wall synthetic machinery is the motor in this system. We propose that bacteria elongate by the uncoordinated, circumferential movements of synthetic complexes that span the plasma membrane and insert radial hoops of new peptidoglycan during their transit.

Roles of tRNA in cell wall biosynthesis

DEFF Research Database (Denmark)

Dare, Kiley; Ibba, Michael

2012-01-01

Recent research into various aspects of bacterial metabolism such as cell wall and antibiotic synthesis, degradation pathways, cellular stress, and amino acid biosynthesis has elucidated roles of aminoacyl-transfer ribonucleic acid (aa-tRNA) outside of translation. Although the two enzyme families...... responsible for cell wall modifications, aminoacyl-phosphatidylglycerol synthases (aaPGSs) and Fem, were discovered some time ago, they have recently become of intense interest for their roles in the antimicrobial resistance of pathogenic microorganisms. The addition of positively charged amino acids...... and play a role in resistance to antibiotics that target the cell wall. Additionally, the formation of truncated peptides results in shorter peptide bridges and loss of branched linkages which makes bacteria more susceptible to antimicrobials. A greater understanding of the structure and substrate...

High-resolution solution-state NMR of unfractionated plant cell walls

Science.gov (United States)

John Ralph; Fachuang Lu; Hoon Kim; Dino Ress; Daniel J. Yelle; Kenneth E. Hammel; Sally A. Ralph; Bernadette Nanayakkara; Armin Wagner; Takuya Akiyama; Paul F. Schatz; Shawn D. Mansfield; Noritsugu Terashima; Wout Boerjan; Bjorn Sundberg; Mattias Hedenstrom

2009-01-01

Detailed structural studies on the plant cell wall have traditionally been difficult. NMR is one of the preeminent structural tools, but obtaining high-resolution solution-state spectra has typically required fractionation and isolation of components of interest. With recent methods for dissolution of, admittedly, finely divided plant cell wall material, the wall can...

Particle Trajectories in Rotating Wall Cell Culture Devices

Science.gov (United States)

Ramachandran N.; Downey, J. P.

1999-01-01

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

Characteristic thickened cell walls of the bracts of the 'eternal flower' Helichrysum bracteatum.

Science.gov (United States)

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

2008-07-01

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. 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. 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. 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.

Plant cell walls to ethanol.

Science.gov (United States)

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...

The cell wall stress response in Aspergillus niger involves increased expression of the glutamine: Fructose-6-phosphate amidotransferase-encoding gene (gfaA) and increased deposition of chitin in the cell wall

NARCIS (Netherlands)

Ram, A.F.J.; Arentshorst, M.; Damveld, R.A.; Kuyk, P.A. van; Klis, F.M.; Hondel, C.A.M.J.J. van den

2004-01-01

Perturbation of cell wall synthesis in Saccharomyces cerevisiae, either by mutations in cell wall synthesis-related genes or by adding compounds that interfere with normal cell wall assembly, triggers a compensatory response to ensure cell wall integrity. This response includes an increase in chitin

First-principles calculations of two cubic fluoropervskite compounds: RbFeF3 and RbNiF3

International Nuclear Information System (INIS)

Mubarak, A.A.; Al-Omari, Saleh

2015-01-01

We present first-principles calculations of the structural, elastic, electronic, magnetic and optical properties for RbFeF 3 and RbNiF 3 . The full-potential linear augmented plan wave (FP-LAPW) method within the density functional theory was utilized to perform the present calculations. We employed the generalized gradient approximation as exchange-correlation potential. It was found that the calculated analytical lattice parameters agree with previous studies. The analysis of elastic constants showed that the present compounds are elastically stable and anisotropic. Moreover, both compounds are classified as a ductile compound. The calculations of the band structure and density functional theory revealed that the RbFeF 3 compound has a half-metallic behavior while the RbNiF 3 compound has a semiconductor behavior with indirect (M–Γ) band gap. The ferromagnetic behavior was studied for both compounds. The optical properties were calculated for the radiation of up to 40 eV. A beneficial optics technology is predicted as revealed from the optical spectra. - Highlights: • RbFeF 3 and RbNiCl 3 compounds are elastically stable. • RbFeF 3 and RbNiCl 3 compounds are classified as a ductile compound. • The RbFeF 3 compound has a half-metallic behavior while the RbNiF 3 compound has a semiconductor behavior. • The optical properties were calculated for the radiation of up to 40 eV

Cell wall remodeling in mycorrhizal symbiosis: a way towards biotrophism.

Science.gov (United States)

Balestrini, Raffaella; Bonfante, Paola

2014-01-01

Cell walls are deeply involved in the molecular talk between partners during plant and microbe interactions, and their role in mycorrhizae, i.e., the widespread symbiotic associations established between plant roots and soil fungi, has been investigated extensively. All mycorrhizal interactions achieve full symbiotic functionality through the development of an extensive contact surface between the plant and fungal cells, where signals and nutrients are exchanged. The exchange of molecules between the fungal and the plant cytoplasm takes place both through their plasma membranes and their cell walls; a functional compartment, known as the symbiotic interface, is thus defined. Among all the symbiotic interfaces, the complex intracellular interface of arbuscular mycorrhizal (AM) symbiosis has received a great deal of attention since its first description. Here, in fact, the host plasma membrane invaginates and proliferates around all the developing intracellular fungal structures, and cell wall material is laid down between this membrane and the fungal cell surface. By contrast, in ectomycorrhizae (ECM), where the fungus grows outside and between the root cells, plant and fungal cell walls are always in direct contact and form the interface between the two partners. The organization and composition of cell walls within the interface compartment is a topic that has attracted widespread attention, both in ecto- and endomycorrhizae. The aim of this review is to provide a general overview of the current knowledge on this topic by integrating morphological observations, which have illustrated cell wall features during mycorrhizal interactions, with the current data produced by genomic and transcriptomic approaches.

Synthesis and Characterization of the Rubidium Thiophosphate Rb 6 (PS 5 )(P 2 S 10 ) and the Rubidium Silver Thiophosphates Rb 2 AgPS 4 , RbAg 5 (PS 4 ) 2 and Rb 3 Ag 9 (PS 4 ) 4

KAUST Repository

Alahmary, Fatimah S.; Davaasuren, Bambar; Khanderi, Jayaprakash; Rothenberger, Alexander

2016-01-01

The metal thiophosphates Rb2AgPS4 (2), RbAg5(PS4)2 (3), and Rb3Ag9(PS4)4 (4) were synthesized by stoichiometric reactions, whereas Rb6(PS5)(P2S10) (1) was prepared with excess amount of sulfur. The compounds crystallize as follows: 1 monoclinic, P21

Changes in cell wall properties coincide with overexpression of extensin fusion proteins in suspension cultured tobacco cells.

Science.gov (United States)

Tan, Li; Pu, Yunqiao; Pattathil, Sivakumar; Avci, Utku; Qian, Jin; Arter, Allison; Chen, Liwei; Hahn, Michael G; Ragauskas, Arthur J; Kieliszewski, Marcia J

2014-01-01

Extensins are one subfamily of the cell wall hydroxyproline-rich glycoproteins, containing characteristic SerHyp4 glycosylation motifs and intermolecular cross-linking motifs such as the TyrXaaTyr sequence. Extensins are believed to form a cross-linked network in the plant cell wall through the tyrosine-derivatives isodityrosine, pulcherosine, and di-isodityrosine. Overexpression of three synthetic genes encoding different elastin-arabinogalactan protein-extensin hybrids in tobacco suspension cultured cells yielded novel cross-linking glycoproteins that shared features of the extensins, arabinogalactan proteins and elastin. The cell wall properties of the three transgenic cell lines were all changed, but in different ways. One transgenic cell line showed decreased cellulose crystallinity and increased wall xyloglucan content; the second transgenic cell line contained dramatically increased hydration capacity and notably increased cell wall biomass, increased di-isodityrosine, and increased protein content; the third transgenic cell line displayed wall phenotypes similar to wild type cells, except changed xyloglucan epitope extractability. These data indicate that overexpression of modified extensins may be a route to engineer plants for bioenergy and biomaterial production.

Neuroprotective effects of ginsenoside Rb1 on high glucose-induced neurotoxicity in primary cultured rat hippocampal neurons.

Science.gov (United States)

Liu, Di; Zhang, Hong; Gu, Wenjuan; Liu, Yuqin; Zhang, Mengren

2013-01-01

Ginsenoside Rb1 is one of the main active principles in traditional herb ginseng and has been reported to have a wide variety of neuroprotective effects. Endoplasmic reticulum (ER) stress has been implicated in neurodegenerative diseases, so the present study aimed to observe the effects of ginsenoside Rb1 on ER stress signaling pathways in high glucose-treated hippocampal neurons. The results from MTT, TUNEL labeling and Annexin V-FITC/PI/Hoechst assays showed that incubating neurons with 50 mM high glucose for 72 h decreased cell viability and increased the number of apoptotic cells whereas treating neurons with 1 μM Rb1 for 72 h protected the neurons against high glucose-induced cell damage. Further molecular mechanism study demonstrated that Rb1 suppressed the activation of ER stress-associated proteins including protein kinase RNA (PKR)-like ER kinase (PERK) and C/EBP homology protein (CHOP) and downregulation of Bcl-2 induced by high glucose. Moreover, Rb1 inhibited both the elevation of intracellular reactive oxygen species (ROS) and the disruption of mitochondrial membrane potential induced by high glucose. In addition, the high glucose-induced cell apoptosis, activation of ER stress, ROS accumulation and mitochondrial dysfunction can also be attenuated by the inhibitor of ER stress 4-phenylbutyric acid (4-PBA) and anti-oxidant N-acetylcysteine(NAC). In conclusion, these results suggest that Rb1 may protect neurons against high glucose-induced cell injury through inhibiting CHOP signaling pathway as well as oxidative stress and mitochondrial dysfunction.

Inhibition of white light of 86Rb+ absorption in the root apex of corn

International Nuclear Information System (INIS)

McKendree, W.L.; Smith, R.C.

1990-01-01

Measurements of cell lengths made at 0.5 millimeter intervals in median longitudinal sections of the primary roots of corn (Zea mays) were used to construct a growth curve. The region 1.5 to 4.0 millimeters from the apex contained the largest number of elongating cells. Absorption of 86 Rb + was measured using intact, dark-grown corn seedlings. Following uptake and exchange, the terminal 8.0 millimeters of each root was cut into four 2.0 millimeter segments. Maximum 86 Rb + uptake occurred in the region from 0.0 to 4.0 millimeter from the root tip. Washing the intact primary root in fresh 2.0 millimolar CaSO 4 for 2 hours prior to uptake augmented the rate of 86 Rb + uptake in all regions. Illumination with white light during washing caused a reduction of 86 Rb + uptake as compared with controls washing in darkness, and the region of greatest light response was the region of elongation. Removal of the coleoptile prior to washing did not prevent the light inhibition of subsequent 86 Rb + uptake. Removal of the root cap prior to washing in light partially reversed the light-induced inhibition of the washing response

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

Science.gov (United States)

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.

Knockdown of hypoxia-inducible factor-1 alpha reduces proliferation, induces apoptosis and attenuates the aggressive phenotype of retinoblastoma WERI-Rb-1 cells under hypoxic conditions.

Science.gov (United States)

Xia, Tian; Cheng, Hao; Zhu, Yu

2014-01-01

Hypoxia-inducible factor-1 alpha (HIF-1α) plays a critical role in tumor cell adaption to hypoxia by inducing the transcription of numerous genes. The role of HIF-1α in malignant retinoblastoma remains unclear. We analyzed the role of HIF-1α in WERI-Rb-1 retinoblastoma cells under hypoxic conditions. CoCl2 (125 mmol/L) was added to the culture media to mimic hypoxia. HIF-1α was silenced using siRNA. Gene and protein expression were measured by semi-quantitative RT-PCR and Western blotting. Cell cycle and apoptosis were analyzed by flow cytometry. Cell proliferation, adhesion and invasion were assayed using MTT, Transwell invasion, and cell adhesion assays respectively. Hypoxia significantly upregulated HIF-1α protein expression and the HIF-1α target genes VEGF, GLUT1, and Survivin mRNA. HIF-1α mRNA expression was not affected by hypoxia. Transfection of the siRNA expression plasmid pRNAT-CMV3.2/Neo-HIF-1α silenced HIF-1α by approximately 80% in hypoxic WERI-Rb-1 cells. The knockdown of HIF-1α under hypoxic conditions downregulated VEGF, GLUT1, and Survivin mRNA. It also inhibited proliferation, promoted apoptosis, induced the G0/G1 phase cell cycle arrest, and reduced the adhesion and invasion of WERI-Rb-1 cells. HIF-1α plays a major role in the survival and aggressive phenotype of retinoblastoma cells under hypoxic conditions. Targeting HIF-1α may be a promising therapeutic strategy for human malignant retinoblastoma.

Protein diffusion in plant cell plasma membranes: the cell-wall corral.

Science.gov (United States)

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.

Cell Wall Structure of Coccoid Green Algae as an Important Trade-Off Between Biotic Interference Mechanisms and Multidimensional Cell Growth.

Science.gov (United States)

Dunker, Susanne; Wilhelm, Christian

2018-01-01

Coccoid green algae can be divided in two groups based on their cell wall structure. One group has a highly chemical resistant cell wall (HR-cell wall) containing algaenan. The other group is more susceptible to chemicals (LR-cell wall - Low resistant cell wall). Algaenan is considered as important molecule to explain cell wall resistance. Interestingly, cell wall types (LR- and HR-cell wall) are not in accordance with the taxonomic classes Chlorophyceae and Trebouxiophyceae, which makes it even more interesting to consider the ecological function. It was already shown that algaenan helps to protect against virus, bacterial and fungal attack, but in this study we show for the first time that green algae with different cell wall properties show different sensitivity against interference competition with the cyanobacterium Microcystis aeruginosa . Based on previous work with co-cultures of M. aeruginosa and two green algae ( Acutodesmus obliquus and Oocystis marssonii ) differing in their cell wall structure, it was shown that M. aeruginosa could impair only the growth of the green algae if they belong to the LR-cell wall type. In this study it was shown that the sensitivity to biotic interference mechanism shows a more general pattern within coccoid green algae species depending on cell wall structure.

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

Directory of Open Access Journals (Sweden)

Adelin Barbacci

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

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

Science.gov (United States)

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

1998-01-01

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

Patterns of expression of cell wall related genes in sugarcane

Directory of Open Access Journals (Sweden)

Lima D.U.

2001-01-01

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

Phase formation in the Li2MoO4-Rb2MoO4-Ln2(MoO4)3 systems and the properties of LiRbLn2(MoO4)4

International Nuclear Information System (INIS)

Basovich, O.M.; Khajkina, E.G.; Vasil'ev, E.V.; Frolov, A.M.

1995-01-01

Phase equilibria within subsolidus range of ternary salt systems Li 2 MoO 4 -Rb 2 MoO 4 -Ln 2 (MoO 4 ) 4 (Ln - Nd, Er) are analyzed. Formation of ternary molybdate LiRbNd 2 (MoO 4 ) 4 is proved along LiNd(MoO 4 ) 2 -RbNd(MoO 4 )-2 cross-section. Phase diagram of this cross-section is plotted. Similar compounds are synthesized for Ln = La-Eu. The parameters of their monoclinic elementary cells are determined. Luminescent properties of LiRbLa 2 (MoO 4 ) 4 -Nd 3+ are studied. 17 refs., 4 figs., 2 tabs

Role of the plant cell wall in gravity resistance.

Science.gov (United States)

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. Copyright © 2014 Elsevier Ltd. All rights reserved.

Long Non-Coding RNAs Embedded in the Rb and p53 Pathways

Energy Technology Data Exchange (ETDEWEB)

Subramanian, Murugan; Jones, Matthew F.; Lal, Ashish, E-mail: ashish.lal@nih.gov [Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (United States)

2013-12-04

In recent years, long non-coding RNAs (lncRNAs) have gained significant attention as a novel class of gene regulators. Although a small number of lncRNAs have been shown to regulate gene expression through diverse mechanisms including transcriptional regulation, mRNA splicing and translation, the physiological function and mechanism of action of the vast majority are not known. Profiling studies in cell lines and tumor samples have suggested a potential role of lncRNAs in cancer. Indeed, distinct lncRNAs have been shown to be embedded in the p53 and Rb networks, two of the major tumor suppressor pathways that control cell cycle progression and survival. Given the fact that inactivation of Rb and p53 is a hallmark of human cancer, in this review we discuss recent evidence on the function of lncRNAs in the Rb and p53 signaling pathways.

Long Non-Coding RNAs Embedded in the Rb and p53 Pathways

International Nuclear Information System (INIS)

Subramanian, Murugan; Jones, Matthew F.; Lal, Ashish

2013-01-01

In recent years, long non-coding RNAs (lncRNAs) have gained significant attention as a novel class of gene regulators. Although a small number of lncRNAs have been shown to regulate gene expression through diverse mechanisms including transcriptional regulation, mRNA splicing and translation, the physiological function and mechanism of action of the vast majority are not known. Profiling studies in cell lines and tumor samples have suggested a potential role of lncRNAs in cancer. Indeed, distinct lncRNAs have been shown to be embedded in the p53 and Rb networks, two of the major tumor suppressor pathways that control cell cycle progression and survival. Given the fact that inactivation of Rb and p53 is a hallmark of human cancer, in this review we discuss recent evidence on the function of lncRNAs in the Rb and p53 signaling pathways

Purification and characterization of a soybean cell wall protein

International Nuclear Information System (INIS)

San Francisco, S.; Tierney, M.L.

1989-01-01

Plant cell wall composition is thought to reflect cellular responses to developmental and environmental signals. We have purified a 33 kDa protein from cell wall extracts of soybean seedlings which is most abundant in extracts from the hook region of the hypocotyl and is rich in proline and hydroxypyroline. In vivo 3 H-proline labelling of hypocotyl tissues indicates that the hook tissue is the predominant site for synthesis of this protein. In unwounded hook, label is incorporated into a 33 kDa protein, while in wounded hook this and additional proteins rich in proline are synthesized. Similarly treated cell wall extracts analyzed by Western blot analysis, using a polyclonal antibody raised against this 33kD protein, showed that the 33 kDa protein is most abundant in cell wall extracts from the hook region of unwounded seedlings and does not increase upon wounding. An immunologically related 35kD protein is also apparent in extracts from wounded hooks and appears to co-migrate with one of the labelled proteins extractable from this tissue. These data indicate that there are two related, proline-rich cell wall proteins in the hook region of soybean seedlings, one of which (33 kDa) is prominent during seedling development and another (35 kDa) which is wound inducible

Local differentiation of cell wall matrix polysaccharides in sinuous pavement cells: its possible involvement in the flexibility of cell shape.

Science.gov (United States)

Sotiriou, P; Giannoutsou, E; Panteris, E; Galatis, B; Apostolakos, P

2018-03-01

The distribution of homogalacturonans (HGAs) displaying different degrees of esterification as well as of callose was examined in cell walls of mature pavement cells in two angiosperm and two fern species. We investigated whether local cell wall matrix differentiation may enable pavement cells to respond to mechanical tension forces by transiently altering their shape. HGA epitopes, identified with 2F4, JIM5 and JIM7 antibodies, and callose were immunolocalised in hand-made or semithin leaf sections. Callose was also stained with aniline blue. The structure of pavement cells was studied with light and transmission electron microscopy (TEM). In all species examined, pavement cells displayed wavy anticlinal cell walls, but the waviness pattern differed between angiosperms and ferns. The angiosperm pavement cells were tightly interconnected throughout their whole depth, while in ferns they were interconnected only close to the external periclinal cell wall and intercellular spaces were developed between them close to the mesophyll. Although the HGA epitopes examined were located along the whole cell wall surface, the 2F4- and JIM5- epitopes were especially localised at cell lobe tips. In fern pavement cells, the contact sites were impregnated with callose and JIM5-HGA epitopes. When tension forces were applied on leaf regions, the pavement cells elongated along the stretching axis, due to a decrease in waviness of anticlinal cell walls. After removal of tension forces, the original cell shape was resumed. The presented data support that HGA epitopes make the anticlinal pavement cell walls flexible, in order to reversibly alter their shape. Furthermore, callose seems to offer stability to cell contacts between pavement cells, as already suggested in photosynthetic mesophyll cells. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Cell wall and DNA cosegregation in Bacillus subtilis studied by electron microscope autoradiography

International Nuclear Information System (INIS)

Schlaeppi, J.M.; Schaefer, O.; Karamata, D.

1985-01-01

Cells of a Bacillus subtilis mutant deficient in both major autolytic enzyme activities were continuously labeled in either cell wall or DNA or both cell wall and DNA. After appropriate periods of chase in minimal as well as in rich medium, thin sections of cells were autoradiographed and examined by electron microscopy. The resolution of the method was adequate to distinguish labeled DNA units from cell wall units. The latter, which could be easily identified, were shown to segregate symmetrically, suggesting a zonal mode of new wall insertion. DNA units could also be clearly recognized despite a limited fragmentation; they segregated asymmetrically with respect to the nearest septum. Analysis of cells simultaneously labeled in cell wall and DNA provided clear visual evidence of their regular but asymmetrical cosegregation, confirming a previous report obtained by light microscope autoradiography. In addition to labeled wall units, electron microscopy of thin sections of aligned cells has revealed fibrillar networks of wall material which are frequently associated with the cell surface. Most likely, these structures correspond to wall sloughed off by the turnover mechanism but not yet degraded to filterable or acid-soluble components

Structure of the cell wall of mango after application of ionizing radiation

International Nuclear Information System (INIS)

Silva, Josenilda M.; Villar, Heldio P.; Pimentel, Rejane M.M.

2012-01-01

Cells of the mesocarp of mango cultivar Tommy Atkins were analyzed by Transmission Electron Microscope—TEM to evaluate the effects of doses of 0.5 and 1.0 kGy applied immediately after the fruit and after storage for twenty days at a temperature of 12 °C followed by 5 days of simulated marketing at a temperature of 21 °C. No alteration was found in the structure of the cell wall, middle lamella, and plasma membrane of fruits when analyzed immediately after application of doses. The mesocarp cell structure of the cell wall, middle lamella, and the plasma membrane did however undergo changes after storage. Fruits that received a dose of 0.5 kGy displayed slight changes in cell wall structure and slight disintegration of the middle lamella. Fruits that received a dose of 1.0 kGy displayed more severe changes in the structure of the cell wall, greater middle lamella degradation, and displacement of the plasma membrane. - Highlights: ► Mesocarp cells were analyzed by Transmission Electron Microscope—TEM. ► No change in cell wall structure, middle lamella and plasma membrane was found in fruits immediately after irradiation. ► Changes in cell wall structure, middle lamella and plasma membrane happened after storage. ► Fruits subjected to 0.5 kGy showed smaller cell wall change.

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

International Nuclear Information System (INIS)

Alsteens, David; Dupres, Vincent; Evoy, Kevin Mc; Dufrene, Yves F; Wildling, Linda; Gruber, Hermann J

2008-01-01

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

Ginsenosides Rb1 and Rg1 Stimulate Melanogenesis in Human Epidermal Melanocytes via PKA/CREB/MITF Signaling

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Mao Lin

2014-01-01

Full Text Available Reduced or defective melanin skin pigmentation may cause many hypopigmentation disorders and increase the risk of damage to the skin triggered by UV irradiation. Ginsenosides Rb1 and Rg1 have many molecular targets including the cAMP-response element-binding protein (CREB, which is involved in melanogenesis. This study aimed to investigate the effects of ginsenosides Rb1 and Rg1 on melanogenesis in human melanocytes and their related mechanisms. The effects of Rb1 and Rg1 on cell viability, tyrosinase activity, cellular melanin content and protein levels of tyrosinase, microphthalmia-associated transcription factor (MITF, and activation of CREB in melanocytes were assessed. Results showed that Rb1 or Rg1 significantly increased cellular melanin content and tyrosinase activity in a dose-dependent manner. By contrast, the cell viability of melanocytes remained unchanged. After exposure to Rb1 or Rg1, the protein levels of tyrosinase, MITF, and phosphorylated CREB were significantly increased. Furthermore, pretreatment with the selective PKA inhibitor H-89 significantly blocked the Rb1- or Rg1-induced increase of melanin content. These findings indicated that Rb1 and Rg1 increased melanogenesis and tyrosinase activity in human melanocytes, which was associated with activation of PKA/CREB/MITF signaling. The effects and mechanisms of Rb1 or Rg1 on skin pigmentation deserve further study.

Protein diffusion in plant cell plasma membranes: The cell-wall corral

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Alexandre eMartinière

2013-12-01

Full Text Available 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.

Longevity in vivo of primary cell wall cellulose synthases.

Science.gov (United States)

Hill, Joseph Lee; Josephs, Cooper; Barnes, William J; Anderson, Charles T; Tien, Ming

2018-02-01

Our work focuses on understanding the lifetime and thus stability of the three main cellulose synthase (CESA) proteins involved in primary cell wall synthesis of Arabidopsis. It had long been thought that a major means of CESA regulation was via their rapid degradation. However, our studies here have uncovered that AtCESA proteins are not rapidly degraded. Rather, they persist for an extended time in the plant cell. Plant cellulose is synthesized by membrane-embedded cellulose synthase complexes (CSCs). The CSC is composed of cellulose synthases (CESAs), of which three distinct isozymes form the primary cell wall CSC and another set of three isozymes form the secondary cell wall CSC. We determined the stability over time of primary cell wall (PCW) CESAs in Arabidopsis thaliana seedlings, using immunoblotting after inhibiting protein synthesis with cycloheximide treatment. Our work reveals very slow turnover for the Arabidopsis PCW CESAs in vivo. Additionally, we show that the stability of all three CESAs within the PCW CSC is altered by mutations in individual CESAs, elevated temperature, and light conditions. Together, these results suggest that CESA proteins are very stable in vivo, but that their lifetimes can be modulated by intrinsic and environmental cues.

Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks

Energy Technology Data Exchange (ETDEWEB)

François, B. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l’Epitaphe, 25030 Besançon (France); INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Calosso, C. E.; Micalizio, S. [INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Abdel Hafiz, M.; Boudot, R. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l’Epitaphe, 25030 Besançon (France)

2015-09-15

We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be −109 and −141 dB rad{sup 2}/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is −105 and −138 dB rad{sup 2}/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10{sup −14} for the Cs cell clock and 2 × 10{sup −14} for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10{sup −15} level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

Plant cell wall sugars: sweeteners for a bio-based economy.

Science.gov (United States)

Van de Wouwer, Dorien; Boerjan, Wout; Vanholme, Bartel

2018-02-12

Global warming and the consequent climate change is one of the major environmental challenges we are facing today. The driving force behind the rise in temperature is our fossil-based economy, which releases massive amounts of the greenhouse gas carbon dioxide into the atmosphere. In order to reduce greenhouse gas emission, we need to scale down our dependency on fossil resources, implying that we need other sources for energy and chemicals to feed our economy. Here, plants have an important role to play; by means of photosynthesis, plants capture solar energy to split water and fix carbon derived from atmospheric carbon dioxide. A significant fraction of the fixed carbon ends up as polysaccharides in the plant cell wall. Fermentable sugars derived from cell wall polysaccharides form an ideal carbon source for the production of bio-platform molecules. However, a major limiting factor in the use of plant biomass as feedstock for the bio-based economy is the complexity of the plant cell wall and its recalcitrance towards deconstruction. To facilitate the release of fermentable sugars during downstream biomass processing, the composition and structure of the cell wall can be engineered. Different strategies to reduce cell wall recalcitrance will be described in this review. The ultimate goal is to obtain a tailor-made biomass, derived from plants with a cell wall optimized for particular industrial or agricultural applications, without affecting plant growth and development. This article is protected by copyright. All rights reserved.

Endometrial stromal cell attachment and matrix homeostasis in abdominal wall endometriomas.

Science.gov (United States)

Itoh, Hiroko; Mogami, Haruta; Bou Nemer, Laurice; Word, Larry; Rogers, David; Miller, Rodney; Word, R Ann

2018-02-01

How does progesterone alter matrix remodeling in abdominal wall endometriomas compared with normal endometrium? Progesterone may prevent attachment of endometrial cells to the abdominal wall, but does not ameliorate abnormal stromal cell responses of abdominal wall endometriomas. Menstruation is a tightly orchestrated physiologic event in which steroid hormones and inflammatory cells cooperatively initiate shedding of the endometrium. Abdominal wall endometriomas represent a unique form of endometriosis in which endometrial cells inoculate fascia or dermis at the time of obstetrical or gynecologic surgery. Invasion of endometrium into ectopic sites requires matrix metalloproteinases (MMPs) for tissue remodeling but endometrium is not shed externally. Observational study in 14 cases and 19 controls. Tissues and stromal cells isolated from 14 abdominal wall endometriomas were compared with 19 normal cycling endometrium using immunohistochemistry, quantitative PCR, gelatin zymography and cell attachment assays. P values cell preps to provide scientific rigor to the conclusions. The results indicate that MMP2 and MMP9 are not increased by TGFβ1 in endometrioma stromal cells. Although progesterone prevents attachment of endometrioma cells to matrix components of the abdominal wall, it does not ameliorate these abnormal stromal cell responses to TGFβ1. N/A. Endometriomas were collected from women identified pre-operatively. Not all endometriomas were collected. Stromal cells from normal endometrium were from different patients, not women undergoing endometrioma resection. This work provides insight into the mechanisms by which progesterone may prevent abdominal wall endometriomas but, once established, are refractory to progesterone treatment. Tissue acquisition was supported by NIH P01HD087150. Authors have no competing interests. © The Author(s) 2017. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-04-26

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

The cell wall protein Ecm33 of Candida albicans is involved in chronological life span, morphogenesis, cell wall regeneration, stress tolerance and host-cell interaction

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Ana eGil-Bona

2016-02-01

Full Text Available Ecm33 is a glycosylphosphatidylinositol (GPI-anchored protein in the human pathogen Candida albicans. This protein is known to be involved in fungal cell wall integrity and is also critical for normal virulence in the mouse model of hematogenously disseminated candidiasis, but its function remains unknown. In this work, several phenotypic analyses of the C. albicans ecm33/ecm33 mutant (RML2U were performed. We observed that RML2U displays the inability of protoplast to regenerate the cell wall, activation of the cell wall integrity pathway, hypersensitivity to temperature, osmotic and oxidative stresses and a shortened chronological lifespan. During the exponential and stationary culture phases, nuclear and actin staining revealed the possible arrest of the cell cycle in RML2U cells. Interestingly, a veil growth, never previously described in C. albicans, was serendipitously observed under static stationary cells. The cells that formed this structure were also observed in cornmeal liquid cultures. These cells are giant, round cells, without DNA, and contain large vacuoles, similar to autophagic cells observed in other fungi. Furthermore, RML2U was phagocytozed more than the wild-type strain by macrophages at earlier time points, but the damage caused to the mouse cells was less than with the wild-type strain. Additionally, the percentage of RML2U apoptotic cells after interaction with macrophages was fewer than in the wild-type strain.

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

Science.gov (United States)

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.

A novel screening method for cell wall mutants in Aspergillus niger identifies UDP-galactopyranose mutase as an important protein in fungal cell wall biosynthesis

NARCIS (Netherlands)

Damveld, R.A.; Franken, A.; Arentshorst, M.; Punt, P.J.; Klis, F.M.; van den Hondel, C.A.M.J.J.; Ram, A.F.J.

2008-01-01

To identify cell wall biosynthetic genes in filamentous fungi and thus potential targets for the discovery of new antifungals, we developed a novel screening method for cell wall mutants. It is based on our earlier observation that the Aspergillus niger agsA gene, which encodes a putative

Interaction and modulation of two antagonistic cell wall enzymes of mycobacteria.

Directory of Open Access Journals (Sweden)

Erik C Hett

2010-07-01

Full Text Available Bacterial cell growth and division require coordinated cell wall hydrolysis and synthesis, allowing for the removal and expansion of cell wall material. Without proper coordination, unchecked hydrolysis can result in cell lysis. How these opposing activities are simultaneously regulated is poorly understood. In Mycobacterium tuberculosis, the resuscitation-promoting factor B (RpfB, a lytic transglycosylase, interacts and synergizes with Rpf-interacting protein A (RipA, an endopeptidase, to hydrolyze peptidoglycan. However, it remains unclear what governs this synergy and how it is coordinated with cell wall synthesis. Here we identify the bifunctional peptidoglycan-synthesizing enzyme, penicillin binding protein 1 (PBP1, as a RipA-interacting protein. PBP1, like RipA, localizes both at the poles and septa of dividing cells. Depletion of the ponA1 gene, encoding PBP1 in M. smegmatis, results in a severe growth defect and abnormally shaped cells, indicating that PBP1 is necessary for viability and cell wall stability. Finally, PBP1 inhibits the synergistic hydrolysis of peptidoglycan by the RipA-RpfB complex in vitro. These data reveal a post-translational mechanism for regulating cell wall hydrolysis and synthesis through protein-protein interactions between enzymes with antagonistic functions.

Studies on the decoupled rotation bands in the nuclei 79Rb, 81Rb, and 79Kr

International Nuclear Information System (INIS)

Panqueva Alvarez, J.H.

1982-01-01

High spin states in 79 Rb, 81 Rb, and 79 Kr were studied by means of the following reactions: 63 Cu( 19 F,p2n) 79 Rb, 70 Ge( 12 C,p2n) 79 Rb, 65 Cu( 16 O,2n) 79 Rb, 65 Cu( 19 F,p2n) 81 Rb, 63 Cu( 19 F,2pn) 79 Kr, and 70 Ge( 12 C,2pn) 79 Kr. On the base of γ single spectra, excitation functions, γ angular distributions, γγ and nγ coincidences, RDDS- and DSA lifetime measurements a level scheme of 79 Rb with 13 new found excited states is proposed. Also a series of stretched E2-transitions between posivite parity states in 79 Kr could be identified. The observed M1 and E2 transition probabilities, which were obtained via the experimental determination of the lifetime as well the branching ratio of 26 excited states, form the base for a comprehensive discussion of the nuclear structure of the studied isotopes. For this reason theoretical calculations with the asymmetric rotor-plus-quasiparticle with variable moment of inertia (AROVMI) as well with the interacting boson-fermion (IBVM) model were performed. The good agreement between experiment and theory permits to relate the decrease of the B(E2)-values in 79 Rb to a finite dimensional (N=8) boson space, to cancel the discrepancies stated by Friederichs et.al., and to analyze 79 Kr the influence of a gsub(9/2) neutron on the deformation of the 78 Kr core. (orig./HSI) [de

Stomatal cell wall composition: distinctive structural patterns associated with different phylogenetic groups.

Science.gov (United States)

Shtein, Ilana; Shelef, Yaniv; Marom, Ziv; Zelinger, Einat; Schwartz, Amnon; Popper, Zoë A; Bar-On, Benny; Harpaz-Saad, Smadar

2017-04-01

Stomatal morphology and function have remained largely conserved throughout ∼400 million years of plant evolution. However, plant cell wall composition has evolved and changed. Here stomatal cell wall composition was investigated in different vascular plant groups in attempt to understand their possible effect on stomatal function. A renewed look at stomatal cell walls was attempted utilizing digitalized polar microscopy, confocal microscopy, histology and a numerical finite-elements simulation. The six species of vascular plants chosen for this study cover a broad structural, ecophysiological and evolutionary spectrum: ferns ( Asplenium nidus and Platycerium bifurcatum ) and angiosperms ( Arabidopsis thaliana and Commelina erecta ) with kidney-shaped stomata, and grasses (angiosperms, family Poaceae) with dumbbell-shaped stomata ( Sorghum bicolor and Triticum aestivum ). Three distinct patterns of cellulose crystallinity in stomatal cell walls were observed: Type I (kidney-shaped stomata, ferns), Type II (kidney-shaped stomata, angiosperms) and Type III (dumbbell-shaped stomata, grasses). The different stomatal cell wall attributes investigated (cellulose crystallinity, pectins, lignin, phenolics) exhibited taxon-specific patterns, with reciprocal substitution of structural elements in the end-walls of kidney-shaped stomata. According to a numerical bio-mechanical model, the end walls of kidney-shaped stomata develop the highest stresses during opening. The data presented demonstrate for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. It is also highly intriguing that in angiosperms crystalline cellulose appears to have replaced lignin that occurs in the stomatal end-walls of ferns serving a similar wall strengthening function. Such taxon-specific spatial patterns of cell wall components could imply different biomechanical functions, which in turn could be a consequence of differences in

Cell-wall recovery after irreversible deformation of wood

Science.gov (United States)

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.

original article the use of morphological and cell wall chemical

African Journals Online (AJOL)

boaz

THE USE OF MORPHOLOGICAL AND CELL WALL CHEMICAL MARKERS IN. THE IDENTIFICATION OF ... aerial hyphae, with or without diffusible pigments on medium surface (7, 14). Cell wall components of Actinomycetes enable rapid qualitative identification of certain .... Alexander von Humboldt Foundation and the.

A novel screening method for cell wall mutants in Aspergillus niger identifies UDP-galactopyranose mutase as an important protein in fungal cell wall biosynthesis

NARCIS (Netherlands)

Damveld, R.A.; Franken, A.; Arentshorst, M.; Punt, P.J.; Klis, F.M.; Hondel, C.A.M.J.J. van den; Ram, A.F.J.

2008-01-01

To identify cell wall biosynthetic genes in filamentous fungi and thus potential targets for the discovery of new antifungals, we developed a novel screening method for cell wall mutants. It is based on our earlier observation that the Aspergillus niger agsA gene, which encodes a putative a-glucan

Whole-Cell Biocatalysis for Producing Ginsenoside Rd from Rb1 Using Lactobacillus rhamnosus GG.

Science.gov (United States)

Ku, Seockmo; You, Hyun Ju; Park, Myeong Soo; Ji, Geun Eog

2016-07-28

Ginsenosides are the major active ingredients in ginseng used for human therapeutic plant medicines. One of the most well-known probiotic bacteria among the various strains on the functional food market is Lactobacillus rhamnosus GG. Biocatalytic methods using probiotic enzymes for producing deglycosylated ginsenosides such as Rd have a growing significance in the functional food industry. The addition of 2% cellobiose (w/v) to glucose-free de Man-Rogosa-Sharpe broths notably induced β-glucosidase production from L. rhamnosus GG. Enzyme production and activity were optimized at a pH, temperature, and cellobiose concentration of 6.0, 40°C, and 2% (w/v), respectively. Under these controlled conditions, β-glucosidase production in L. rhamnosus GG was enhanced by 25-fold. Additionally, whole-cell homogenates showed the highest β-glucosidase activity when compared with disrupted cell suspensions; the cell disruption step significantly decreased the β-glucosidase activity. Based on the optimized enzyme conditions, whole-cell L. rhamnosus GG was successfully used to convert ginsenoside Rb1 into Rd.

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

Science.gov (United States)

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

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

Science.gov (United States)

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.

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

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Purbasha; Bosneaga, Elena; Auer, Manfred

2009-02-16

Throughout their life, plants typically remain in one location utilizing sunlight for the synthesis of carbohydrates, which serve as their sole source of energy as well as building blocks of a protective extracellular matrix, called the cell wall. During the course of evolution, plants have repeatedly adapted to their respective niche,which is reflected in the changes of their body plan and the specific design of cell walls. Cell walls not only changed throughout evolution but also are constantly remodelled and reconstructed during the development of an individual plant, and in response to environmental stress or pathogen attacks. Carbohydrate-rich cell walls display complex designs, which together with the presence of phenolic polymers constitutes a barrier for microbes, fungi, and animals. Throughout evolution microbes have co-evolved strategies for efficient breakdown of cell walls. Our current understanding of cell walls and their evolutionary changes are limited as our knowledge is mainly derived from biochemical and genetic studies, complemented by a few targeted yet very informative imaging studies. Comprehensive plant cell wall models will aid in the re-design of plant cell walls for the purpose of commercially viable lignocellulosic biofuel production as well as for the timber, textile, and paper industries. Such knowledge will also be of great interest in the context of agriculture and to plant biologists in general. It is expected that detailed plant cell wall models will require integrated correlative multimodal, multiscale imaging and modelling approaches, which are currently underway.

Current Models for Transcriptional Regulation of Secondary Cell Wall Biosynthesis in Grasses

Directory of Open Access Journals (Sweden)

Xiaolan Rao

2018-04-01

Full Text Available Secondary cell walls mediate many crucial biological processes in plants including mechanical support, water and nutrient transport and stress management. They also provide an abundant resource of renewable feed, fiber, and fuel. The grass family contains the most important food, forage, and biofuel crops. Understanding the regulatory mechanism of secondary wall formation in grasses is necessary for exploiting these plants for agriculture and industry. Previous research has established a detailed model of the secondary wall regulatory network in the dicot model species Arabidopsis thaliana. Grasses, branching off from the dicot ancestor 140–150 million years ago, display distinct cell wall morphology and composition, suggesting potential for a different secondary wall regulation program from that established for dicots. Recently, combined application of molecular, genetic and bioinformatics approaches have revealed more transcription factors involved in secondary cell wall biosynthesis in grasses. Compared with the dicots, grasses exhibit a relatively conserved but nevertheless divergent transcriptional regulatory program to activate their secondary cell wall development and to coordinate secondary wall biosynthesis with other physiological processes.

High temperature induced disruption of the cell wall integrity and structure in Pleurotus ostreatus mycelia.

Science.gov (United States)

Qiu, Zhiheng; Wu, Xiangli; Gao, Wei; Zhang, Jinxia; Huang, Chenyang

2018-05-30

Fungal cells are surrounded by a tight cell wall to protect them from harmful environmental conditions and to resist lysis. The synthesis and assembly determine the shape, structure, and integrity of the cell wall during the process of mycelial growth and development. High temperature is an important abiotic stress, which affects the synthesis and assembly of cell walls. In the present study, the chitin and β-1,3-glucan concentrations in the cell wall of Pleurotus ostreatus mycelia were changed after high-temperature treatment. Significantly higher chitin and β-1,3-glucan concentrations were detected at 36 °C than those incubated at 28 °C. With the increased temperature, many aberrant chitin deposition patches occurred, and the distribution of chitin in the cell wall was uneven. Moreover, high temperature disrupts the cell wall integrity, and P. ostreatus mycelia became hypersensitive to cell wall-perturbing agents at 36 °C. The cell wall structure tended to shrink or distorted after high temperature. The cell walls were observed to be thicker and looser by using transmission electron microscopy. High temperature can decrease the mannose content in the cell wall and increase the relative cell wall porosity. According to infrared absorption spectrum, high temperature broke or decreased the glycosidic linkages. Finally, P. ostreatus mycelial cell wall was easily degraded by lysing enzymes after high-temperature treatment. In other words, the cell wall destruction caused by high temperature may be a breakthrough for P. ostreatus to be easily infected by Trichoderma.

THESEUS 1, FERONIA and relatives: a family of cell wall-sensing receptor kinases?

Science.gov (United States)

Cheung, Alice Y; Wu, Hen-Ming

2011-12-01

The plant cell wall provides form and integrity to the cell as well as a dynamic interface between a cell and its environment. Therefore mechanisms capable of policing changes in the cell wall, signaling cellular responses including those that would feedback regulate cell wall properties are expected to play important roles in facilitating growth and ensuring survival. Discoveries in the last few years that the Arabidopsis THESEUS 1 receptor-like kinase (RLK) may function as a sensor for cell wall defects to regulate growth and that its relatives FERONIA and ANXURs regulate pollen tube integrity imply strongly that they play key roles in cell wall-related processes. Furthermore, FERONIA acts as a cell surface regulator for RAC/ROP GTPases and activates production of reactive oxygen species which are, respectively, important molecular switches and mediators for diverse processes. These findings position the THESEUS 1/FERONIA family RLKs as surface regulators and potential cell wall sensors capable of broadly and profoundly impacting cellular pathways in response to diverse signals. Copyright © 2011 Elsevier Ltd. All rights reserved.

Characterization of xylan in the early stages of secondary cell wall formation in tobacco bright yellow-2 cells.

Science.gov (United States)

Ishii, Tadashi; Matsuoka, Keita; Ono, Hiroshi; Ohnishi-Kameyama, Mayumi; Yaoi, Katsuro; Nakano, Yoshimi; Ohtani, Misato; Demura, Taku; Iwai, Hiroaki; Satoh, Shinobu

2017-11-15

The major polysaccharides present in the primary and secondary walls surrounding plant cells have been well characterized. However, our knowledge of the early stages of secondary wall formation is limited. To address this, cell walls were isolated from differentiating xylem vessel elements of tobacco bright yellow-2 (BY-2) cells induced by VASCULAR-RELATED NAC-DOMAIN7 (VND7). The walls of induced VND7-VP16-GR BY-2 cells consisted of cellulose, pectic polysaccharides, hemicelluloses, and lignin, and contained more xylan and cellulose compared with non-transformed BY-2 and uninduced VND7-VP16-GR BY-2 cells. A reducing end sequence of xylan containing rhamnose and galaturonic acid- residues is present in the walls of induced, uninduced, and non-transformed BY-2 cells. Glucuronic acid residues in xylan from walls of induced cells are O-methylated, while those of xylan in non-transformed BY-2 and uninduced cells are not. Our results show that xylan changes in chemical structure and amounts during the early stages of xylem differentiation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation of microstructural and mechanical properties of cell walls of closed-cell aluminium alloy foams

Energy Technology Data Exchange (ETDEWEB)

Islam, M.A.; Kader, M.A.; Hazell, P.J.; Brown, A.D. [School of Engineering and Information Technology, UNSW Canberra, ACT 2610 (Australia); Saadatfar, M. [Department of Applied Mathematics, Australian National University, Canberra ACT 0200 (Australia); Quadir, M.Z [Electron Microscope Unit, Mark Wainwright Analytical Centre (MWAC), The University of New South Wales, Sydney, NSW 2052 (Australia); Microscopy and Microanalysis Facility (MMF), John de Laeter Centre (JdLC), Curtin University, WA 6102 (Australia); Escobedo, J.P., E-mail: J.Escobedo-Diaz@adfa.edu.au [School of Engineering and Information Technology, UNSW Canberra, ACT 2610 (Australia)

2016-06-01

This study investigates the influence of microstructure on the strength properties of individual cell walls of closed-cell stabilized aluminium foams (SAFs). Optical microscopy (OM), micro-computed X-ray tomography (µ-CT), electron backscattering diffraction (EBSD), and energy dispersive X-ray spectroscopy (EDS) analyses were conducted to examine the microstructural properties of SAF cell walls. Novel micro-tensile tests were performed to investigate the strength properties of individual cell walls. Microstructural analysis of the SAF cell walls revealed that the material consists of eutectic Al-Si and dendritic a-Al with an inhomogeneous distribution of intermetallic particles and micro-pores (void defects). These microstructural features affected the micro-mechanism fracture behaviour and tensile strength of the specimens. Laser-based extensometer and digital image correlation (DIC) analyses were employed to observe the strain fields of individual tensile specimens. The tensile failure mode of these materials has been evaluated using microstructural analysis of post-mortem specimens, revealing a brittle cleavage fracture of the cell wall materials. The micro-porosities and intermetallic particles reduced the strength under tensile loading, limiting the elongation to fracture on average to ~3.2% and an average ultimate tensile strength to ~192 MPa. Finally, interactions between crack propagation and obstructing intermetallic compounds during the tensile deformation have been elucidated.

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

Energy Technology Data Exchange (ETDEWEB)

Carpita, Nicholas C.

2001-10-18

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

Calibration of RB reactor power; Kalibrisanje snage reaktora RB

Energy Technology Data Exchange (ETDEWEB)

Sotic, O; Markovic, H; Ninkovic, M; Strugar, P; Dimitrijevic, Z; Takac, S; Stefanovic, D; Kocic, A; Vranic, S [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

1976-09-15

The first and only calibration of RB reactor power was done in 1962, and the obtained calibration ratio was used irrespective of the lattice pitch and core configuration. Since the RB reactor is being prepared for operation at higher power levels it was indispensable to reexamine the calibration ratio, estimate its dependence on the lattice pitch, critical level of heavy water and thickness of the side reflector. It was necessary to verify the reliability of control and dosimetry instruments, and establish neutron and gamma dose dependence on reactor power. Two series of experiments were done in June 1976. First series was devoted to tests of control and dosimetry instrumentation and measurements of radiation in the RB reactor building dependent on reactor power. Second series covered measurement of thermal and epithermal neuron fluxes in the reactor core and calculation of reactor power. Four different reactor cores were chosen for these experiments. Reactor pitches were 8, 8{radical}2, and 16 cm with 40, 52 and 82 fuel channels containing 2% enriched fuel. Obtained results and analysis of these results are presented in this document with conclusions related to reactor safe operation.

The tumor suppressors pRB and p53 as regulators of adipocyte differentiation and function

DEFF Research Database (Denmark)

Hallenborg, Philip; Feddersen, Søren; Madsen, Lise

2009-01-01

BACKGROUND: The retinoblastoma protein (pRB) and p53 are crucial members of regulatory networks controlling the cell cycle and apoptosis, and a hallmark of virtually all cancers is dysregulation of expression or function of pRB or p53. Although they are best known for their role in cancer...

Cell wall as a target for bacteria inactivation by pulsed electric fields

Science.gov (United States)

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

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

Science.gov (United States)

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...

Stomatal Function Requires Pectin De-methyl-esterification of the Guard Cell Wall.

Science.gov (United States)

Amsbury, Sam; Hunt, Lee; Elhaddad, Nagat; Baillie, Alice; Lundgren, Marjorie; Verhertbruggen, Yves; Scheller, Henrik V; Knox, J Paul; Fleming, Andrew J; Gray, Julie E

2016-11-07

Stomatal opening and closure depends on changes in turgor pressure acting within guard cells to alter cell shape [1]. The extent of these shape changes is limited by the mechanical properties of the cells, which will be largely dependent on the structure of the cell walls. Although it has long been observed that guard cells are anisotropic due to differential thickening and the orientation of cellulose microfibrils [2], our understanding of the composition of the cell wall that allows them to undergo repeated swelling and deflation remains surprisingly poor. Here, we show that the walls of guard cells are rich in un-esterified pectins. We identify a pectin methylesterase gene, PME6, which is highly expressed in guard cells and required for stomatal function. pme6-1 mutant guard cells have walls enriched in methyl-esterified pectin and show a decreased dynamic range in response to triggers of stomatal opening/closure, including elevated osmoticum, suggesting that abrogation of stomatal function reflects a mechanical change in the guard cell wall. Altered stomatal function leads to increased conductance and evaporative cooling, as well as decreased plant growth. The growth defect of the pme6-1 mutant is rescued by maintaining the plants in elevated CO 2 , substantiating gas exchange analyses, indicating that the mutant stomata can bestow an improved assimilation rate. Restoration of PME6 rescues guard cell wall pectin methyl-esterification status, stomatal function, and plant growth. Our results establish a link between gene expression in guard cells and their cell wall properties, with a corresponding effect on stomatal function and plant physiology. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Exploring the Role of Cell Wall-Related Genes and Polysaccharides during Plant Development.

Science.gov (United States)

Tucker, Matthew R; Lou, Haoyu; Aubert, Matthew K; Wilkinson, Laura G; Little, Alan; Houston, Kelly; Pinto, Sara C; Shirley, Neil J

2018-05-31

The majority of organs in plants are not established until after germination, when pluripotent stem cells in the growing apices give rise to daughter cells that proliferate and subsequently differentiate into new tissues and organ primordia. This remarkable capacity is not only restricted to the meristem, since maturing cells in many organs can also rapidly alter their identity depending on the cues they receive. One general feature of plant cell differentiation is a change in cell wall composition at the cell surface. Historically, this has been viewed as a downstream response to primary cues controlling differentiation, but a closer inspection of the wall suggests that it may play a much more active role. Specific polymers within the wall can act as substrates for modifications that impact receptor binding, signal mobility, and cell flexibility. Therefore, far from being a static barrier, the cell wall and its constituent polysaccharides can dictate signal transmission and perception, and directly contribute to a cell's capacity to differentiate. In this review, we re-visit the role of plant cell wall-related genes and polysaccharides during various stages of development, with a particular focus on how changes in cell wall machinery accompany the exit of cells from the stem cell niche.

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

Directory of Open Access Journals (Sweden)

Indrakumar Vetharaniam

2014-05-01

Full Text Available We have developed a novel 3-D, agent-based model of cell-wall digestion to improve our understanding of ruminal cell-wall digestion. It offers a capability to study cell walls and their enzymatic modification, by providing a representation of cellulose microfibrils and non-cellulosic polysaccharides and by simulating their spatial and catalytic interactions with enzymes. One can vary cell-wall composition and the types and numbers of enzyme molecules, allowing the model to be applied to a range of systems where cell walls are degraded and to the modification of cell walls by endogenous enzymes. As a proof of principle, we have modelled the wall of a mesophyll cell from the leaf of perennial ryegrass and then simulated its enzymatic degradation. This is a primary, non-lignified cell wall and the model includes cellulose, hemicelluloses (glucuronoarabinoxylans, 1,3;1,4-β-glucans, and xyloglucans and pectin. These polymers are represented at the level of constituent monosaccharides, and assembled to form a 3-D, meso-scale representation of the molecular structure of the cell wall. The composition of the cell wall can be parameterised to represent different walls in different cell types and taxa. The model can contain arbitrary combinations of different enzymes. It simulates their random diffusion through the polymer networks taking collisions into account, allowing steric hindrance from cell-wall polymers to be modelled. Steric considerations are included when target bonds are encountered, and breakdown products resulting from enzymatic activity are predicted.

Modification of antioxidant systems in cell walls of maize roots by different nitrogen sources

International Nuclear Information System (INIS)

Hadži-Tašković Šukalović V; Vuletić, M.; Marković, K.; Željko, Vučinić; Kravić, N.

2016-01-01

Antioxidant systems of maize root cell walls grown on different nitrogen sources were evaluated. Plants were grown on a medium containing only NO3- or the mixture of NO3-+NH4+, in a 2:1 ratio. Eleven-day old plants, two days after the initiation of lateral roots, were used for the experiments. Cell walls were isolated from lateral roots and primary root segments, 2-7 cm from tip to base, representing zones of intense or decreased growth rates, respectively. Protein content and the activity of enzymes peroxidase, malate dehydrogenase and ascorbate oxidase ionically or covalently bound to the walls, as well as cell wall phenolic content and antioxidant capacity, were determined. Cell walls of plants grown on mixed N possess more developed enzymatic antioxidant systems and lower non-enzymatic antioxidant defenses than cell walls grown on NO3-. Irrespective of N treatment, the activities of all studied enzymes and protein content were higher in cell walls of lateral compared to primary roots. Phenolic content of cell walls isolated from lateral roots was higher in NO3--grown than in mixed N grown plants. No significant differences could be observed in the isozyme patterns of cell wall peroxidases isolated from plants grown on different nutrient solution. Our results indicate that different N treatments modify the antioxidant systems of root cell walls. Treatment with NO3- resulted in an increase of constitutive phenolic content, while the combination of NO3-+NH4+ elevated the redox enzyme activities in root cell walls.

Modification of antioxidant systems in cell walls of maize roots by different nitrogen sources

Energy Technology Data Exchange (ETDEWEB)

Hadži-Tašković Šukalović V; Vuletić, M.; Marković, K.; Željko, Vučinić; Kravić, N.

2016-07-01

Antioxidant systems of maize root cell walls grown on different nitrogen sources were evaluated. Plants were grown on a medium containing only NO3- or the mixture of NO3-+NH4+, in a 2:1 ratio. Eleven-day old plants, two days after the initiation of lateral roots, were used for the experiments. Cell walls were isolated from lateral roots and primary root segments, 2-7 cm from tip to base, representing zones of intense or decreased growth rates, respectively. Protein content and the activity of enzymes peroxidase, malate dehydrogenase and ascorbate oxidase ionically or covalently bound to the walls, as well as cell wall phenolic content and antioxidant capacity, were determined. Cell walls of plants grown on mixed N possess more developed enzymatic antioxidant systems and lower non-enzymatic antioxidant defenses than cell walls grown on NO3-. Irrespective of N treatment, the activities of all studied enzymes and protein content were higher in cell walls of lateral compared to primary roots. Phenolic content of cell walls isolated from lateral roots was higher in NO3--grown than in mixed N grown plants. No significant differences could be observed in the isozyme patterns of cell wall peroxidases isolated from plants grown on different nutrient solution. Our results indicate that different N treatments modify the antioxidant systems of root cell walls. Treatment with NO3- resulted in an increase of constitutive phenolic content, while the combination of NO3-+NH4+ elevated the redox enzyme activities in root cell walls.

Imaging the Dynamics of Cell Wall Polymer Deposition in the Unicellular Model Plant, Penium margaritaceum.

Science.gov (United States)

Domozych, David; Lietz, Anna; Patten, Molly; Singer, Emily; Tinaz, Berke; Raimundo, Sandra C

2017-01-01

The unicellular green alga, Penium margaritaceum, represents a novel and valuable model organism for elucidating cell wall dynamics in plants. This organism's cell wall contains several polymers that are highly similar to those found in the primary cell walls of land plants. Penium is easily grown in laboratory culture and is effectively manipulated in various experimental protocols including microplate assays and correlative microscopy. Most importantly, Penium can be live labeled with cell wall-specific antibodies or other probes and returned to culture where specific cell wall developmental events can be monitored. Additionally, live cells can be rapidly cryo-fixed and cell wall surface microarchitecture can be observed with variable pressure scanning electron microscopy. Here, we describe the methodology for maintaining Penium for experimental cell wall enzyme studies.

Analysis list: RB1 [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available RB1 Prostate,Uterus + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/R...B1.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/RB1.5.tsv http://dbarchive.biosciencedbc.jp/...kyushu-u/hg19/target/RB1.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/RB1.Prostate.tsv,http://dbarchive.bioscience...dbc.jp/kyushu-u/hg19/colo/RB1.Uterus.tsv http://dbarchive.bioscience...dbc.jp/kyushu-u/hg19/colo/Prostate.gml,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Uterus.gml ...

Investigation of the functional role of CSLD proteins in plant cell wall deposition

Energy Technology Data Exchange (ETDEWEB)

Nielsen, Erik Etlar [Univ. of Michigan, Ann Arbor, MI (United States)

2017-11-21

The overall goal of this research proposal was to characterize the molecular machinery responsible for polarized secretion of cell wall components in Arabidopsis thaliana. We have used the polarized expansion that occurs during root hair cell growth to identify membrane trafficking pathways involved in polarized secretion of cell wall components to the expanding tips of these cells, and we have recently shown that CSLD3 is preferentially targeted to the apical plasma membranes in root hair cells, where it plays essential roles during cell wall deposition in these cells. The specific aims of the project are designed to answer the following objective: Identification of the cell wall polysaccharide class that CSLD proteins synthesize.

The role of the cell wall in plant immunity

DEFF Research Database (Denmark)

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

2014-01-01

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

Deregulation of p53 and RB Transcriptional Control Leads to Overexpression of DNA Methyltransferases in Lung Cancer

Directory of Open Access Journals (Sweden)

Yen-An Tang

2014-06-01

Conclusions: This study provides cell and clinical evidence that p53 and RB pathways transcriptionally repress DNMT expression. Normal expression of DNMT3A, RB and MDM2 proteins can be a biomarker for good prognosis in lung cancer.

Mutation of p107 exacerbates the consequences of Rb loss in embryonic tissues and causes cardiac and blood vessel defects.

Science.gov (United States)

Berman, Seth D; West, Julie C; Danielian, Paul S; Caron, Alicia M; Stone, James R; Lees, Jacqueline A

2009-09-01

The retinoblastoma tumor-suppressor protein, pRb, is a member of the pocket protein family that includes p107 and p130. These proteins have well-defined roles in regulating entry into and exit from the cell cycle and also have cell cycle-independent roles in facilitating differentiation. Here we investigate the overlap between pocket protein's function during embryonic development by using conditional mutant alleles to generate Rb;p107 double-mutant embryos (DKOs) that develop in the absence of placental defects. These DKOs die between e13.5 and e14.5, much earlier than either the conditional Rb or the germline p107 single mutants, which survive to birth or are largely viable, respectively. Analyses of the e13.5 DKOs shows that p107 mutation exacerbates the phenotypes resulting from pRb loss in the central nervous system and lens, but not in the peripheral nervous system. In addition, these embryos exhibit novel phenotypes, including increased proliferation of blood vessel endothelial cells, and heart defects, including double-outlet right ventricle (DORV). The DORV is caused, at least in part, by a defect in blood vessel endothelial cells and/or heart mesenchymal cells. These findings demonstrate novel, overlapping functions for pRb and p107 in numerous murine tissues.

Cell Wall Remodeling by a Synthetic Analog Reveals Metabolic Adaptation in Vancomycin Resistant Enterococci.

Science.gov (United States)

Pidgeon, Sean E; Pires, Marcos M

2017-07-21

Drug-resistant bacterial infections threaten to overburden our healthcare system and disrupt modern medicine. A large class of potent antibiotics, including vancomycin, operate by interfering with bacterial cell wall biosynthesis. Vancomycin-resistant enterococci (VRE) evade the blockage of cell wall biosynthesis by altering cell wall precursors, rendering them drug insensitive. Herein, we reveal the phenotypic plasticity and cell wall remodeling of VRE in response to vancomycin in live bacterial cells via a metabolic probe. A synthetic cell wall analog was designed and constructed to monitor cell wall structural alterations. Our results demonstrate that the biosynthetic pathway for vancomycin-resistant precursors can be hijacked by synthetic analogs to track the kinetics of phenotype induction. In addition, we leveraged this probe to interrogate the response of VRE cells to vancomycin analogs and a series of cell wall-targeted antibiotics. Finally, we describe a proof-of-principle strategy to visually inspect drug resistance induction. Based on our findings, we anticipate that our metabolic probe will play an important role in further elucidating the interplay among the enzymes involved in the VRE biosynthetic rewiring.

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

OpenAIRE

Cho, Won Kyong; Hyun, Tae Kyung; Kumar, Dhinesh; Rim, Yeonggil; Chen, Xiong Yan; Jo, Yeonhwa; Kim, Suwha; Lee, Keun Woo; Park, Zee-Yong; Lucas, William J.; Kim, Jae-Yean

2015-01-01

Rice is a model plant widely used for basic and applied research programs. Plant cell wall proteins play key roles in a broad range of biological processes. However, presently, knowledge on the rice cell wall proteome is rudimentary in nature. In the present study, the tightly-bound cell wall proteome of rice callus cultured cells using sequential extraction protocols was developed using mass spectrometry and bioinformatics methods, leading to the identification of 1568 candidate proteins. Ba...

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

OpenAIRE

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

2009-01-01

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

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

DEFF Research Database (Denmark)

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

2002-01-01

The Cnr (Colourless non-ripening) tomato (Lycopersicon esculentum Mill.) mutant has an aberrant fruit-ripening phenotype in which fruit do not soften and have reduced cell adhesion between pericarp cells. Cell walls from Cnr fruit were analysed in order to assess the possible contribution of pectic...... polysaccharides to the non-softening and altered cell adhesion phenotype. Cell wall material (CWM) and solubilised fractions of mature green and red ripe fruit were analysed by chemical, enzymatic and immunochemical techniques. No major differences in CWM sugar composition were detected although differences were...... that was chelator-soluble was 50% less in Cnr cell walls at both the mature green and red ripe stages. Chelator-soluble material from ripe-stage Cnr was more susceptible to endo-polygalacturonase degradation than the corresponding material from wild-type fruit. In addition, cell walls from Cnr fruit contained...

Loss of heterozygosity of CDKN2A (p16INK4a) and RB1 tumor suppressor genes in testicular germ cell tumors

International Nuclear Information System (INIS)

Vladusic, Tomislav; Hrascan, Reno; Pecina-Slaus, Nives; Vrhovac, Ivana; Gamulin, Marija; Franekic, Jasna; Kruslin, Bozo

2010-01-01

Testicular germ cell tumors (TGCTs) are the most frequent malignances in young adult men. The two main histological forms, seminomas and nonseminomas, differ biologically and clinically. pRB protein and its immediate upstream regulator p16INK4a are involved in the RB pathway which is deregulated in most TGCTs. The objective of this study was to evaluate the occurrence of loss of heterozygosity (LOH) of the CDKN2A (p16INK4a) and RB1 tumor suppressor genes in TGCTs. Forty TGCTs (18 seminomas and 22 nonseminomas) were analyzed by polymerase chain reaction using the restriction fragment length polymorphism or the nucleotide repeat polymorphism method. LOH of the CDKN2A was found in two (6%) out of 34 (85%) informative cases of our total TGCT sample. The observed changes were assigned to two (11%) nonseminomas out of 18 (82%) informative samples. Furthermore, LOH of the RB1 was detected in two (6%) out of 34 (85%) informative cases of our total TGCT sample. Once again, the observed changes were assigned to two (10.5%) nonseminomas out of 19 (86%) informative samples. Both LOHs of the CDKN2A were found in nonseminomas with a yolk sac tumor component, and both LOHs of the RB1 were found in nonseminomas with an embryonal carcinoma component. The higher incidence of observed LOH in nonseminomas may provide a clue to their invasive behavior

75 FR 15326 - Airworthiness Directives; Rolls-Royce plc RB211-Trent 500, 700, and 800 Series Turbofan Engines

Science.gov (United States)

2010-03-29

... ambient conditions, ice can accumulate on the walls of the fuel pipes within the aircraft fuel system... aircraft in combination with Rolls-Royce engines that feature similar fuel systems to the RB211-Trent 800... the aircraft fuel system, which can then be released downstream when fuel flow demand is increased...

Reciprocal Interactions between Cadmium-Induced Cell Wall Responses and Oxidative Stress in Plants

Directory of Open Access Journals (Sweden)

Christophe Loix

2017-10-01

Full Text Available Cadmium (Cd pollution renders many soils across the world unsuited or unsafe for food- or feed-orientated agriculture. The main mechanism of Cd phytotoxicity is the induction of oxidative stress, amongst others through the depletion of glutathione. Oxidative stress can damage lipids, proteins, and nucleic acids, leading to growth inhibition or even cell death. The plant cell has a variety of tools to defend itself against Cd stress. First and foremost, cell walls might prevent Cd from entering and damaging the protoplast. Both the primary and secondary cell wall have an array of defensive mechanisms that can be adapted to cope with Cd. Pectin, which contains most of the negative charges within the primary cell wall, can sequester Cd very effectively. In the secondary cell wall, lignification can serve to immobilize Cd and create a tougher barrier for entry. Changes in cell wall composition are, however, dependent on nutrients and conversely might affect their uptake. Additionally, the role of ascorbate (AsA as most important apoplastic antioxidant is of considerable interest, due to the fact that oxidative stress is a major mechanism underlying Cd toxicity, and that AsA biosynthesis shares several links with cell wall construction. In this review, modifications of the plant cell wall in response to Cd exposure are discussed. Focus lies on pectin in the primary cell wall, lignification in the secondary cell wall and the importance of AsA in the apoplast. Regarding lignification, we attempt to answer the question whether increased lignification is merely a consequence of Cd toxicity, or rather an elicited defense response. We propose a model for lignification as defense response, with a central role for hydrogen peroxide as substrate and signaling molecule.

Insights into cell wall structure of Sida hermaphrodita and its influence on recalcitrance.

Science.gov (United States)

Damm, Tatjana; Pattathil, Sivakumar; Günl, Markus; Jablonowski, Nicolai David; O'Neill, Malcolm; Grün, Katharina Susanne; Grande, Philipp Michael; Leitner, Walter; Schurr, Ulrich; Usadel, Björn; Klose, Holger

2017-07-15

The perennial plant Sida hermaphrodita (Sida) is attracting attention as potential energy crop. Here, the first detailed view on non-cellulosic Sida cell wall polysaccharide composition, structure and architecture is given. Cell walls were prepared from Sida stems and sequentially extracted with aqueous buffers and alkali. The structures of the quantitatively predominant polysaccharides present in each fraction were determined by biochemical characterization, glycome profiling and mass spectrometry. The amounts of glucose released by Accellerase-1500 ® treatment of the cell wall and the cell wall residue remaining after each extraction were used to assess the roles of pectin and hemicellulose in the recalcitrance of Sida biomass. 4-O-Methyl glucuronoxylan with a low proportion of side substitutions was identified as the major non-cellulosic glycan component of Sida stem cell walls. Pectic polysaccharides and xylans were found to be associated with lignin, suggesting that these polysaccharides have roles in Sida cell wall recalcitrance to enzymatic hydrolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pumilio and nanos RNA-binding proteins counterbalance the transcriptional consequences of RB1 inactivation.

Science.gov (United States)

Miles, Wayne O; Dyson, Nicholas J

2014-01-01

The ability of the retinoblastoma protein (RB) tumor suppressor to repress transcription stimulated by the E2 promoter binding factors (E2F) is integral to its biological functions. Our recent report described a conserved feedback mechanism mediated by the RNA-binding proteins Pumilio and Nanos that increases in importance following RB loss and helps cells to tolerate deregulated E2F.

Autoradiographic studies on the kinetics of fetal supporting cells and wall cells in rats 19 days after conception

International Nuclear Information System (INIS)

Lugani-Mehta, S.

1980-01-01

The duration of the S-phase of supporting cells and wall cells of rat fetuses aged 19 days was determined by the ''labelled mitosis'' method. The supporting cells are predecessors of the sertoli cells while the wall cells are predecessors of the boundary tissue and, possibly, of part of the peritubular Leydig cell system. The S-phase of the supporting cells was found to last 10.1 h while the S-phase of the wall cells lasted 9.2 h. The data were not in agreement with the data of other authors. (orig./MG) [de

Evidence that pulsed electric field treatment enhances the cell wall porosity of yeast cells.

Science.gov (United States)

Ganeva, Valentina; Galutzov, Bojidar; Teissie, Justin

2014-02-01

The application of rectangular electric pulses, with 0.1-2 ms duration and field intensity of 2.5-4.5 kV/cm, to yeast suspension mediates liberation of cytoplasmic proteins without cell lysis. The aim of this study was to evaluate the effect of pulsed electric field with similar parameters on cell wall porosity of different yeast species. We found that electrically treated cells become more susceptible to lyticase digestion. In dependence on the strain and the electrical conditions, cell lysis was obtained at 2-8 times lower enzyme concentration in comparison with control untreated cells. The increase of the maximal lysis rate was between two and nine times. Furthermore, when applied at low concentration (1 U/ml), the lyticase enhanced the rate of protein liberation from electropermeabilized cells without provoking cell lysis. Significant differences in the cell surface of control and electrically treated cells were revealed by scanning electron microscopy. Data presented in this study allow us to conclude that electric field pulses provoke not only plasma membrane permeabilization, but also changes in the cell wall structure, leading to increased wall porosity.

The plant secretory pathway seen through the lens of the cell wall.

Science.gov (United States)

van de Meene, A M L; Doblin, M S; Bacic, Antony

2017-01-01

Secretion in plant cells is often studied by looking at well-characterised, evolutionarily conserved membrane proteins associated with particular endomembrane compartments. Studies using live cell microscopy and fluorescent proteins have illuminated the highly dynamic nature of trafficking, and electron microscopy studies have resolved the ultrastructure of many compartments. Biochemical and molecular analyses have further informed about the function of particular proteins and endomembrane compartments. In plants, there are over 40 cell types, each with highly specialised functions, and hence potential variations in cell biological processes and cell wall structure. As the primary function of secretion in plant cells is for the biosynthesis of cell wall polysaccharides and apoplastic transport complexes, it follows that utilising our knowledge of cell wall glycosyltransferases (GTs) and their polysaccharide products will inform us about secretion. Indeed, this knowledge has led to novel insights into the secretory pathway, including previously unseen post-TGN secretory compartments. Conversely, our knowledge of trafficking routes of secretion will inform us about polarised and localised deposition of cell walls and their constituent polysaccharides/glycoproteins. In this review, we look at what is known about cell wall biosynthesis and the secretory pathway and how the different approaches can be used in a complementary manner to study secretion and provide novel insights into these processes.

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

Science.gov (United States)

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.

Stem and progenitor cells in biostructure of blood vessel walls

Directory of Open Access Journals (Sweden)

Krzysztof Korta

2013-09-01

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

Solid-State NMR on bacterial cells: selective cell wall signal enhancement and resolution improvement using dynamic nuclear polarization

International Nuclear Information System (INIS)

Takahashi, Hiroki; Bardet, Michel; De Paepe, Gael; Hediger, Sabine; Ayala, Isabel; Simorre, Jean-Pierre

2013-01-01

Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance (NMR) has recently emerged as a powerful technique for the study of material surfaces. In this study, we demonstrate its potential to investigate cell surface in intact cells. Using Bacillus subtilis bacterial cells as an example, it is shown that the polarizing agent 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL) has a strong binding affinity to cell wall polymers (peptidoglycan). This particular interaction is thoroughly investigated with a systematic study on extracted cell wall materials, disrupted cells, and entire cells, which proved that TOTAPOL is mainly accumulating in the cell wall. This property is used on one hand to selectively enhance or suppress cell wall signals by controlling radical concentrations and on the other hand to improve spectral resolution by means of a difference spectrum. Comparing DNP-enhanced and conventional solid-state NMR, an absolute sensitivity ratio of 24 was obtained on the entire cell sample. This important increase in sensitivity together with the possibility of enhancing specifically cell wall signals and improving resolution really opens new avenues for the use of DNP-enhanced solid-state NMR as an on-cell investigation tool. (authors)

Solid-state NMR on bacterial cells: selective cell wall signal enhancement and resolution improvement using dynamic nuclear polarization.

Science.gov (United States)

Takahashi, Hiroki; Ayala, Isabel; Bardet, Michel; De Paëpe, Gaël; Simorre, Jean-Pierre; Hediger, Sabine

2013-04-03

Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance (NMR) has recently emerged as a powerful technique for the study of material surfaces. In this study, we demonstrate its potential to investigate cell surface in intact cells. Using Bacillus subtilis bacterial cells as an example, it is shown that the polarizing agent 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL) has a strong binding affinity to cell wall polymers (peptidoglycan). This particular interaction is thoroughly investigated with a systematic study on extracted cell wall materials, disrupted cells, and entire cells, which proved that TOTAPOL is mainly accumulating in the cell wall. This property is used on one hand to selectively enhance or suppress cell wall signals by controlling radical concentrations and on the other hand to improve spectral resolution by means of a difference spectrum. Comparing DNP-enhanced and conventional solid-state NMR, an absolute sensitivity ratio of 24 was obtained on the entire cell sample. This important increase in sensitivity together with the possibility of enhancing specifically cell wall signals and improving resolution really opens new avenues for the use of DNP-enhanced solid-state NMR as an on-cell investigation tool.

Identifying Genes Controlling Ferulate Cross-Linking Formation in Grass Cell Walls

Energy Technology Data Exchange (ETDEWEB)

de O. Buanafina, Marcia Maria [Pennsylvania State Univ., University Park, PA (United States)

2013-10-16

This proposal focuses on cell wall feruloylation and our long term goal is to identify and isolate novel genes controlling feruloylation and to characterize the phenotype of mutants in this pathway, with a spotlight on cell wall properties.

Cell Wall Diversity in Forage Maize

NARCIS (Netherlands)

Torres, A.F.; Noordam-Boot, C.M.M.; Dolstra, Oene; Weijde, van der Tim; Combes, Eliette; Dufour, Philippe; Vlaswinkel, Louis; Visser, R.G.F.; Trindade, L.M.

2015-01-01

Genetic studies are ideal platforms for assessing the extent of genetic diversity, inferring the genetic architecture, and evaluating complex trait interrelations for cell wall compositional and bioconversion traits relevant to bioenergy applications. Through the characterization of a forage

Mitotic defects lead to pervasive aneuploidy and accompany loss of RB1 activity in mouse LmnaDhe dermal fibroblasts.

Directory of Open Access Journals (Sweden)

C Herbert Pratt

2011-03-01

Full Text Available Lamin A (LMNA is a component of the nuclear lamina and is mutated in several human diseases, including Emery-Dreifuss muscular dystrophy (EDMD; OMIM ID# 181350 and the premature aging syndrome Hutchinson-Gilford progeria syndrome (HGPS; OMIM ID# 176670. Cells from progeria patients exhibit cell cycle defects in both interphase and mitosis. Mouse models with loss of LMNA function have reduced Retinoblastoma protein (RB1 activity, leading to aberrant cell cycle control in interphase, but how mitosis is affected by LMNA is not well understood.We examined the cell cycle and structural phenotypes of cells from mice with the Lmna allele, Disheveled hair and ears (Lmna(Dhe. We found that dermal fibroblasts from heterozygous Lmna(Dhe (Lmna(Dhe/+ mice exhibit many phenotypes of human laminopathy cells. These include severe perturbations to the nuclear shape and lamina, increased DNA damage, and slow growth rates due to mitotic delay. Interestingly, Lmna(Dhe/+ fibroblasts also had reduced levels of hypophosphorylated RB1 and the non-SMC condensin II-subunit D3 (NCAP-D3, a mitosis specific centromere condensin subunit that depends on RB1 activity. Mitotic check point control by mitotic arrest deficient-like 1 (MAD2L1 also was perturbed in Lmna(Dhe/+ cells. Lmna(Dhe/+ fibroblasts were consistently aneuploid and had higher levels of micronuclei and anaphase bridges than normal fibroblasts, consistent with chromosome segregation defects.These data indicate that RB1 may be a key regulator of cellular phenotype in laminopathy-related cells, and suggest that the effects of LMNA on RB1 include both interphase and mitotic cell cycle control.

Mitotic Defects Lead to Pervasive Aneuploidy and Accompany Loss of RB1 Activity in Mouse LmnaDhe Dermal Fibroblasts

Science.gov (United States)

Pratt, C. Herbert; Curtain, Michelle; Donahue, Leah Rae; Shopland, Lindsay S.

2011-01-01

Background Lamin A (LMNA) is a component of the nuclear lamina and is mutated in several human diseases, including Emery-Dreifuss muscular dystrophy (EDMD; OMIM ID# 181350) and the premature aging syndrome Hutchinson-Gilford progeria syndrome (HGPS; OMIM ID# 176670). Cells from progeria patients exhibit cell cycle defects in both interphase and mitosis. Mouse models with loss of LMNA function have reduced Retinoblastoma protein (RB1) activity, leading to aberrant cell cycle control in interphase, but how mitosis is affected by LMNA is not well understood. Results We examined the cell cycle and structural phenotypes of cells from mice with the Lmna allele, Disheveled hair and ears (LmnaDhe). We found that dermal fibroblasts from heterozygous LmnaDhe (LmnaDhe/+) mice exhibit many phenotypes of human laminopathy cells. These include severe perturbations to the nuclear shape and lamina, increased DNA damage, and slow growth rates due to mitotic delay. Interestingly, LmnaDhe/+ fibroblasts also had reduced levels of hypophosphorylated RB1 and the non-SMC condensin II-subunit D3 (NCAP-D3), a mitosis specific centromere condensin subunit that depends on RB1 activity. Mitotic check point control by mitotic arrest deficient-like 1 (MAD2L1) also was perturbed in LmnaDhe /+ cells. LmnaDhe /+ fibroblasts were consistently aneuploid and had higher levels of micronuclei and anaphase bridges than normal fibroblasts, consistent with chromosome segregation defects. Conclusions These data indicate that RB1 may be a key regulator of cellular phenotype in laminopathy-related cells, and suggest that the effects of LMNA on RB1 include both interphase and mitotic cell cycle control. PMID:21464947

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; FINAL

International Nuclear Information System (INIS)

Carpita, Nicholas C.

2001-01-01

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

2009 Plant Cell Walls Gordon Research Conference-August 2-7,2009

Energy Technology Data Exchange (ETDEWEB)

Mohnen, Debra [Univ. of Georgia, Athens, GA (United States)

2009-08-07

Plant cell walls are a complex cellular compartment essential for plant growth, development and response to biotic and abiotic stress and a major biological resource for meeting our future bioenergy and natural product needs. The goal of the 2009 Plant Cell Walls Gordon Research Conference is to summarize and critically evaluate the current level of understanding of the structure, synthesis and function of the whole plant extracellular matrix, including the polysaccharides, proteins, lignin and waxes that comprise the wall, and the enzymes and regulatory proteins that drive wall synthesis and modification. Innovative techniques to study how both primary and secondary wall polymers are formed and modified throughout plant growth will be emphasized, including rapid advances taking place in the use of anti-wall antibodies and carbohydrate binding proteins, comparative and evolutionary wall genomics, and the use of mutants and natural variants to understand and identify wall structure-function relationships. Discussions of essential research advances needed to push the field forward toward a systems biology approach will be highlighted. The meeting will include a commemorative lecture in honor of the career and accomplishments of the late Emeritus Professor Bruce A. Stone, a pioneer in wall research who contributed over 40 years of outstanding studies on plant cell wall structure, function, synthesis and remodeling including emphasis on plant cell wall beta-glucans and arabinogalactans. The dwindling supply of fossil fuels will not suffice to meet our future energy and industrial product needs. Plant biomass is the renewable resource that will fill a large part of the void left by vanishing fossil fuels. It is therefore critical that basic research scientists interact closely with industrial researchers to critically evaluate the current state of knowledge regarding how plant biomass, which is largely plant cell walls, is synthesized and utilized by the plant. A final

Anharmonic properties of Raman modes in double wall carbon nano tubes

Energy Technology Data Exchange (ETDEWEB)

Marquina, J. [Universidad de los Andes, Facultad de Ciencias, Centro de Estudios Avanzados en Optica, 5101 Merida (Venezuela, Bolivarian Republic of); Power, Ch.; Gonzalez, J. [Universidad de los Andes, Facultad de Ciencias, Centro de Estudios en Semiconductores, 5101 Merida (Venezuela, Bolivarian Republic of); Broto, J. M. [Universite de Toulouse, Laboratoire National des Champs Magnetiques Intenses, CNRS UPR 3228, 31400 Toulouse (France); Flahaut, E., E-mail: castella@ula.v [Universite Paul Sabatier, Laboratoire de Chimie des Materiaux Inorganiques, UMR CNRS 5085, 31062 Toulouse (France)

2011-07-01

The temperature dependence of the radial breathing modes (RB Ms) and the zone-center tangential optical phonons (G-bands) of double-walled carbon nano tubes has been investigated between 300 and 700 K using Raman scattering. As expected, with increasing temperature, the frequencies of the Raman peaks, including the RB Ms and G-bands downshift simultaneously. We show here that the temperature dependence of the RB Ms can be fitted by a simple linear dependence and different RB Ms have different frequency shifts. We observe a noticeable nonlinearity in the temperature dependence of the G-band associated with the outer semiconducting tube G+ext (s). The deviation from the linear trend is due to the contribution of the third-order anharmonic term in the lattice potential energy with a pure temperature effect. An estimated value of 1.5 for the Grueneisen parameter of the G+ext (s) band was found. (Author)

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

Science.gov (United States)

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

2016-01-01

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

Temperature Gradients on the Cell Wall in the Critical Viscosity Experiment

Science.gov (United States)

Berg, Robert F.; Moldover, Michael R.

1993-01-01

Because of the diverging susceptibility delta rho/delta Tau near the liquid-vapor critical point, temperature gradients must be kept small to maintain adequate sample homogeneity. In our Science Requirements Document we paid particular attention to radial density gradients caused by equilibration of the xenon sample. Axial density gradients were addressed through the requirement that the cell's copper wall have a gradient less than 22 microK/m. This report re-examines the cell wall's temperature distribution in more detail by estimating all known significant contributions to temperature differences on the cell's wall.

Chalcone Synthase (CHS) Gene Suppression in Flax Leads to Changes in Wall Synthesis and Sensing Genes, Cell Wall Chemistry and Stem Morphology Parameters

Science.gov (United States)

Zuk, Magdalena; Działo, Magdalena; Richter, Dorota; Dymińska, Lucyna; Matuła, Jan; Kotecki, Andrzej; Hanuza, Jerzy; Szopa, Jan

2016-01-01

The chalcone synthase (CHS) gene controls the first step in the flavonoid biosynthesis. In flax, CHS down-regulation resulted in tannin accumulation and reduction in lignin synthesis, but plant growth was not affected. This suggests that lignin content and thus cell wall characteristics might be modulated through CHS activity. This study investigated the possibility that CHS affects cell wall sensing as well as polymer content and arrangement. CHS-suppressed and thus lignin-reduced plants showed significant changes in expression of genes involved in both synthesis of components and cell wall sensing. This was accompanied by increased levels of cellulose and hemicellulose. CHS-reduced flax also showed significant changes in morphology and arrangement of the cell wall. The stem tissue layers were enlarged averagely twofold compared to the control, and the number of fiber cells more than doubled. The stem morphology changes were accompanied by reduction of the crystallinity index of the cell wall. CHS silencing induces a signal transduction cascade that leads to modification of plant metabolism in a wide range and thus cell wall structure. PMID:27446124

Function and Biosynthesis of Cell Wall α-1,3-Glucan in Fungi

Directory of Open Access Journals (Sweden)

Akira Yoshimi

2017-11-01

Full Text Available Although α-1,3-glucan is a major cell wall polysaccharide in filamentous fungi, its biological functions remain unclear, except that it acts as a virulence factor in animal and plant pathogenic fungi: it conceals cell wall β-glucan on the fungal cell surface to circumvent recognition by hosts. However, cell wall α-1,3-glucan is also present in many of non-pathogenic fungi. Recently, the universal function of α-1,3-glucan as an aggregation factor has been demonstrated. Applications of fungi with modified cell wall α-1,3-glucan in the fermentation industry and of in vitro enzymatically-synthesized α-1,3-glucan in bio-plastics have been developed. This review focuses on the recent progress in our understanding of the biological functions and biosynthetic mechanism of cell wall α-1,3-glucan in fungi. We briefly consider the history of studies on α-1,3-glucan, overview its biological functions and biosynthesis, and finally consider the industrial applications of fungi deficient in α-1,3-glucan.

Characterizing phenolformaldehyde adhesive cure chemistry within the wood cell wall

Science.gov (United States)

Daniel J. Yelle; John Ralph

2016-01-01

Adhesive bonding of wood using phenol-formaldehyde remains the industrial standard in wood product bond durability. Not only does this adhesive infiltrate the cell wall, it also is believed to form primary bonds with wood cell wall polymers, particularly guaiacyl lignin. However, the mechanism by which phenol-formaldehyde adhesive intergrally interacts and bonds to...

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

DEFF Research Database (Denmark)

Cankar, Katarina; Kortstee, Anne; Toonen, Marcel A.J.

2014-01-01

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

Chapter 3 Cell Wall Chemistry

Science.gov (United States)

Roger M. Rowell; Roger Pettersen; Mandla A. Tshabalala

2012-01-01

Wood is best defined as a three-dimensional biopolymer composite composed of an interconnected network of cellulose, hemicelluloses and lignin with minor amounts of extractives, and inorganics. The major chemical component of a living tree is water, but on a dry weight basis, all wood cell walls consist mainly of sugar-based polymers (carbohydrates, 65-75%) that are...

Rapid detection of RB1 recurrent mutations in retinoblastoma by ...

Indian Academy of Sciences (India)

In about half of the patients, one mutation is inherited via the germinal cells, while in the .... mutational hot spots in the RB1 gene, making genetic testing complex and challenging ... by direct sequencing. High normal background in sequenc-.

Histochemical effects of γ radiation on soft fruit cell walls

International Nuclear Information System (INIS)

Foa, E.; Jona, R.; Vallania, R.

1980-01-01

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

Regulations and instructions for RB reactor operation; Propisi i uputstva za rad reaktora RB

Energy Technology Data Exchange (ETDEWEB)

NONE

1977-07-01

This document includes regulations for reactor RB operation, behaviour and presence of staff in the reactor building; regulations for performing experiments at the RB reactor, regulations and int ructions for the reactor operators and other staff on duty. A chapter is devoted to instruction for reactor operation with the operating documentation and special duties of the operators. Regulations and instruction concerned with accidents are described with classification of accidents and evacuation plan. Annexes to this document include: the present status of the reactor; program for training the reactor operators; forms which are obligatory to be signed for any operating activity, and the certificate of the RB reactor lattice.

The Cell Wall of the Human Fungal Pathogen Aspergillus fumigatus: Biosynthesis, Organization, Immune Response, and Virulence.

Science.gov (United States)

Latgé, Jean-Paul; Beauvais, Anne; Chamilos, Georgios

2017-09-08

More than 90% of the cell wall of the filamentous fungus Aspergillus fumigatus comprises polysaccharides. Biosynthesis of the cell wall polysaccharides is under the control of three types of enzymes: transmembrane synthases, which are anchored to the plasma membrane and use nucleotide sugars as substrates, and cell wall-associated transglycosidases and glycosyl hydrolases, which are responsible for remodeling the de novo synthesized polysaccharides and establishing the three-dimensional structure of the cell wall. For years, the cell wall was considered an inert exoskeleton of the fungal cell. The cell wall is now recognized as a living organelle, since the composition and cellular localization of the different constitutive cell wall components (especially of the outer layers) vary when the fungus senses changes in the external environment. The cell wall plays a major role during infection. The recognition of the fungal cell wall by the host is essential in the initiation of the immune response. The interactions between the different pattern-recognition receptors (PRRs) and cell wall pathogen-associated molecular patterns (PAMPs) orientate the host response toward either fungal death or growth, which would then lead to disease development. Understanding the molecular determinants of the interplay between the cell wall and host immunity is fundamental to combatting Aspergillus diseases.

Autochthonous tumors driven by Rb1 loss have an ongoing requirement for the RBP2 histone demethylase.

Science.gov (United States)

McBrayer, Samuel K; Olenchock, Benjamin A; DiNatale, Gabriel J; Shi, Diana D; Khanal, Januka; Jennings, Rebecca B; Novak, Jesse S; Oser, Matthew G; Robbins, Alissa K; Modiste, Rebecca; Bonal, Dennis; Moslehi, Javid; Bronson, Roderick T; Neuberg, Donna; Nguyen, Quang-De; Signoretti, Sabina; Losman, Julie-Aurore; Kaelin, William G

2018-04-17

Inactivation of the retinoblastoma gene ( RB1 ) product, pRB, is common in many human cancers. Targeting downstream effectors of pRB that are central to tumorigenesis is a promising strategy to block the growth of tumors harboring loss-of-function RB1 mutations. One such effector is retinoblastoma-binding protein 2 (RBP2, also called JARID1A or KDM5A), which encodes an H3K4 demethylase. Binding of pRB to RBP2 has been linked to the ability of pRB to promote senescence and differentiation. Importantly, genetic ablation of RBP2 is sufficient to phenocopy pRB's ability to induce these cellular changes in cell culture experiments. Moreover, germline Rbp2 deletion significantly impedes tumorigenesis in Rb1 +/- mice. The value of RBP2 as a therapeutic target in cancer, however, hinges on whether loss of RBP2 could block the growth of established tumors as opposed to simply delaying their onset. Here we show that conditional, systemic ablation of RBP2 in tumor-bearing Rb1 +/- mice is sufficient to slow tumor growth and significantly extend survival without causing obvious toxicity to the host. These findings show that established Rb1 -null tumors require RBP2 for growth and further credential RBP2 as a therapeutic target in human cancers driven by RB1 inactivation.

Control of Cell Wall Extensibility during Pollen Tube Growth

OpenAIRE

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

2013-01-01

Tip-growing pollen tubes achieve rapid elongation while maintaining cell wall integrity by balancing local expansion, controlled by local changes in wall viscosity, against exocytosis, influenced by the activity of the actin cytoskeleton, cellular energetics, and calcium and proton physiology.

Comprehensive evaluation of Streptococcus sanguinis cell wall-anchored proteins in early infective endocarditis.

Science.gov (United States)

Turner, Lauren Senty; Kanamoto, Taisei; Unoki, Takeshi; Munro, Cindy L; Wu, Hui; Kitten, Todd

2009-11-01

Streptococcus sanguinis is a member of the viridans group of streptococci and a leading cause of the life-threatening endovascular disease infective endocarditis. Initial contact with the cardiac infection site is likely mediated by S. sanguinis surface proteins. In an attempt to identify the proteins required for this crucial step in pathogenesis, we searched for surface-exposed, cell wall-anchored proteins encoded by S. sanguinis and then used a targeted signature-tagged mutagenesis (STM) approach to evaluate their contributions to virulence. Thirty-three predicted cell wall-anchored proteins were identified-a number much larger than those found in related species. The requirement of each cell wall-anchored protein for infective endocarditis was assessed in the rabbit model. It was found that no single cell wall-anchored protein was essential for the development of early infective endocarditis. STM screening was also employed for the evaluation of three predicted sortase transpeptidase enzymes, which mediate the cell surface presentation of cell wall-anchored proteins. The sortase A mutant exhibited a modest (approximately 2-fold) reduction in competitiveness, while the other two sortase mutants were indistinguishable from the parental strain. The combined results suggest that while cell wall-anchored proteins may play a role in S. sanguinis infective endocarditis, strategies designed to interfere with individual cell wall-anchored proteins or sortases would not be effective for disease prevention.

Immersion Refractometry of Isolated Bacterial Cell Walls

Science.gov (United States)

Marquis, Robert E.

1973-01-01

Immersion-refractometric and light-scattering measurements were adapted to determinations of average refractive indices and physical compactness of isolated bacterial cell walls. The structures were immersed in solutions containing various concentrations of polymer molecules that cannot penetrate into wall pores, and then an estimate was made of the polymer concentration or the refractive index of the polymer solution in which light scattering was reduced to zero. Because each wall preparation was heterogeneous, the refractive index of the medium for zero light scattering had to be estimated by extrapolation. Refractive indices for walls suspended in bovine serum albumin solutions ranged from 1.348 for walls of the rod form of Arthrobacter crystallopoietes to 1.382 for walls of the teichoic acid deficient, 52A5 strain of Staphylococcus aureus. These indices were used to calculate approximate values for solids content per milliliter, and the calculated values agreed closely with those estimated from a knowledge of dextran-impermeable volumes per gram, dry weight, of the walls. When large molecules such as dextrans or serum albumin were used for immersion refractometry, the refractive indices obtained were for entire walls, including both wall polymers and wall water. When smaller molecules that can penetrate wall pores to various extents were used with Micrococcus lysodeikticus walls, the average, apparent refractive index of the structures increased as the molecular size of probing molecules was decreased. It was possible to obtain an estimate of 1.45 to 1.46 for the refractive index of wall polymers, predominantly peptidoglycans in this case, by extrapolating the curve for refractive index versus molecular radius to a value of 0.2 nm, the approximate radius of a water molecule. This relatively low value for polymer refractive index was interpreted as evidence in favor of the amorphous, elastic model of peptidoglycan structure and against the crystalline, rigid

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

NARCIS (Netherlands)

Huang, J.H.

2016-01-01

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

Identification of polysaccharide hydrolases involved in autolytic degradation of Zea cell walls

International Nuclear Information System (INIS)

Nock, L.P.; Smith, C.J.

1987-01-01

Cell walls of Zea mays (cv L.G.11) seedlings labeled with 14 C were treated with α-amylase from Bacillus subtilis to remove starch and mixed linkage glucans. These walls released arabinose, xylose, galactose, and galacturonic acid in addition to glucose when they were allowed to autolyze. Methylation analysis was performed on samples of wall which had been incubated autolytically and the results indicated that degradation of the major polymer of the wall, the glucoarabinoxylan, had occurred. A number of glycanases could be dissociated from the wall by use of 3 M LiCL. The proteins which were released were found to contain a number of exoglycosidase activities in addition to being effective in degrading the polysaccharide substrates, araban, xylan, galactan, laminarin, mannan, and polygalacturonic acid. The effects of these enzymes on the wall during autolysis appear to result from endo-activity in addition to exo-activity. The structural changes that occurred in the cell walls during autolysis were found to be related to the changes previously found to occur in cell walls during auxin induced extension

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

OpenAIRE

Krysan, Damian J

2009-01-01

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

Turnover of galactans and other cell wall polysaccharides during development of flax plants

International Nuclear Information System (INIS)

Gorshkova, T.A.; Chemikosova, S.B.; Lozovaya, V.V.; Carpita, N.C.

1997-01-01

We investigated the synthesis and turnover of cell wall polysaccharides of the flax (Linum usitatissimum L.) plant during development of the phloem fibers. One-month-old flax plants were exposed to a 40-min pulse with 14CO2 followed by 8-h, 24-h, and 1-month periods of chase with ambient CO2, and radioactivity in cell wall sugars was determined in various plant parts. The relative radioactivity of glucose in noncellulosic polysaccharides was the highest compared with all other cell wall sugars immediately after the pulse and decreased substantially during the subsequent chase. The relative radioactivities of the other cell wall sugars changed with differing rates, indicating turnover of specific polysaccharides. Notably, after 1 month of chase there was a marked decrease in the proportional mass and total radioactivity in cell wall galactose, indicating a long-term turnover of the galactans enriched in the fiber-containing tissues. The ratio of radiolabeled xylose to arabinose also increased during the chase, indicating a turnover of arabinose-containing polymers and interconversion to xylose. The pattern of label redistribution differed between organs, indicating that the cell wall turnover processes are tissue- and cell-specific

The Modification of Cell Wall Properties by Expression of Recombinant Resilin in Transgenic Plants.

Science.gov (United States)

Preis, Itan; Abramson, Miron; Shoseyov, Oded

2018-04-01

Plant tissue is composed of many different types of cells. Plant cells required to withstand mechanical pressure, such as vessel elements and fibers, have a secondary cell wall consisting of polysaccharides and lignin, which strengthen the cell wall structure and stabilize the cell shape. Previous attempts to alter the properties of the cell wall have mainly focused on reducing the amount of lignin or altering its structure in order to ease its extraction from raw woody materials for the pulp and paper and biorefinery industries. In this work, we propose the in vivo modification of the cell wall structure and mechanical properties by the introduction of resilin, an elastic protein that is able to crosslink with lignin monomers during cell wall synthesis. The effects of resilin were studied in transgenic eucalyptus plants. The protein was detected within the cell wall and its expression led to an increase in the elastic modulus of transgenic stems. In addition, transgenic stems displayed a higher yield point and toughness, indicating that they were able to absorb more energy before breaking.

Cell wall composition throughout development for the model grass Brachypodium distanchyon

Directory of Open Access Journals (Sweden)

David eRancour

2012-12-01

Full Text Available Temperate perennial grasses are important worldwide as a livestock nutritive energy source and a potential feedstock for lignocellulosic biofuel production. The annual temperate grass Brachypodium distanchyon has been championed as a useful model system to facilitate biological research in agriculturally important temperate forage grasses based on phylogenetic relationships. To physically corroborate genetic predictions, we determined the chemical composition profiles of organ-specific cell walls throughout the development of two common diploid accessions of Brachypodium distanchyon, Bd21-3 and Bd21. Chemical analysis was performed on cell walls isolated from distinct organs (i.e. leaves, sheaths, stems and roots at three developmental stages of 1 12-day seedling, 2 vegetative-to-reproductive transition, and 3 mature seed-fill. In addition, we have included cell wall analysis of embryonic callus used for genetic transformations. Composition of cell walls based on components lignin, hydroxycinnamates, uronosyls, neutral sugars, and protein suggests that Brachypodium distanchyon is similar chemically to agriculturally important forage grasses. There were modest compositional differences in hydroxycinnamate profiles between accessions Bd21-3 and Bd21. In addition, when compared to agronomical important C3 grasses, more mature Brachypodium stem cell walls have a relative increase in glucose of 48% and a decrease in lignin of 36%. Though differences exists between Brachypodium and agronomical important C3 grasses, Brachypodium distanchyon should be still a useful model system for genetic manipulation of cell wall composition to determine the impact upon functional characteristics such as rumen digestibility or energy conversion efficiency for bioenergy production.

Cell wall composition throughout development for the model grass Brachypodium distachyon

Science.gov (United States)

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

2012-01-01

Temperate perennial grasses are important worldwide as a livestock nutritive energy source and a potential feedstock for lignocellulosic biofuel production. The annual temperate grass Brachypodium distachyon has been championed as a useful model system to facilitate biological research in agriculturally important temperate forage grasses based on phylogenetic relationships. To physically corroborate genetic predictions, we determined the chemical composition profiles of organ-specific cell walls throughout the development of two common diploid accessions of Brachypodium distachyon, Bd21-3 and Bd21. Chemical analysis was performed on cell walls isolated from distinct organs (i.e., leaves, sheaths, stems, and roots) at three developmental stages of (1) 12-day seedling, (2) vegetative-to-reproductive transition, and (3) mature seed fill. In addition, we have included cell wall analysis of embryonic callus used for genetic transformations. Composition of cell walls based on components lignin, hydroxycinnamates, uronosyls, neutral sugars, and protein suggests that Brachypodium distachyon is similar chemically to agriculturally important forage grasses. There were modest compositional differences in hydroxycinnamate profiles between accessions Bd21-3 and Bd21. In addition, when compared to agronomical important C3 grasses, more mature Brachypodium stem cell walls have a relative increase in glucose of 48% and a decrease in lignin of 36%. Though differences exist between Brachypodium and agronomical important C3 grasses, Brachypodium distachyon should be still a useful model system for genetic manipulation of cell wall composition to determine the impact upon functional characteristics such as rumen digestibility or energy conversion efficiency for bioenergy production. PMID:23227028

Insight into the architecture of the NuRD complex: structure of the RbAp48-MTA1 subcomplex.

Science.gov (United States)

Alqarni, Saad S M; Murthy, Andal; Zhang, Wei; Przewloka, Marcin R; Silva, Ana P G; Watson, Aleksandra A; Lejon, Sara; Pei, Xue Y; Smits, Arne H; Kloet, Susan L; Wang, Hongxin; Shepherd, Nicholas E; Stokes, Philippa H; Blobel, Gerd A; Vermeulen, Michiel; Glover, David M; Mackay, Joel P; Laue, Ernest D

2014-08-08

The nucleosome remodeling and deacetylase (NuRD) complex is a widely conserved transcriptional co-regulator that harbors both nucleosome remodeling and histone deacetylase activities. It plays a critical role in the early stages of ES cell differentiation and the reprogramming of somatic to induced pluripotent stem cells. Abnormalities in several NuRD proteins are associated with cancer and aging. We have investigated the architecture of NuRD by determining the structure of a subcomplex comprising RbAp48 and MTA1. Surprisingly, RbAp48 recognizes MTA1 using the same site that it uses to bind histone H4, showing that assembly into NuRD modulates RbAp46/48 interactions with histones. Taken together with other results, our data show that the MTA proteins act as scaffolds for NuRD complex assembly. We further show that the RbAp48-MTA1 interaction is essential for the in vivo integration of RbAp46/48 into the NuRD complex. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Formation of wood secondary cell wall may involve two type cellulose synthase complexes in Populus.

Science.gov (United States)

Xi, Wang; Song, Dongliang; Sun, Jiayan; Shen, Junhui; Li, Laigeng

2017-03-01

Cellulose biosynthesis is mediated by cellulose synthases (CesAs), which constitute into rosette-like cellulose synthase complexe (CSC) on the plasma membrane. Two types of CSCs in Arabidopsis are believed to be involved in cellulose synthesis in the primary cell wall and secondary cell walls, respectively. In this work, we found that the two type CSCs participated cellulose biosynthesis in differentiating xylem cells undergoing secondary cell wall thickening in Populus. During the cell wall thickening process, expression of one type CSC genes increased while expression of the other type CSC genes decreased. Suppression of different type CSC genes both affected the wall-thickening and disrupted the multilaminar structure of the secondary cell walls. When CesA7A was suppressed, crystalline cellulose content was reduced, which, however, showed an increase when CesA3D was suppressed. The CesA suppression also affected cellulose digestibility of the wood cell walls. The results suggest that two type CSCs are involved in coordinating the cellulose biosynthesis in formation of the multilaminar structure in Populus wood secondary cell walls.

Overexpression of HDAC1 induces cellular senescence by Sp1/PP2A/pRb pathway

International Nuclear Information System (INIS)

Chuang, Jian-Ying; Hung, Jan-Jong

2011-01-01

Highlights: → Overexpression of HDAC1 induces Sp1 deacetylation and raises Sp1/p300 complex formation to bind to PP2Ac promoter. → Overexpression of HDAC1 strongly inhibits the phosphorylation of pRb through up-regulation of PP2A. → Overexpressed HDAC1 restrains cell proliferaction and induces cell senescence though a novel Sp1/PP2A/pRb pathway. -- Abstract: Senescence is associated with decreased activities of DNA replication, protein synthesis, and cellular division, which can result in deterioration of cellular functions. Herein, we report that the growth and division of tumor cells were significantly repressed by overexpression of histone deacetylase (HDAC) 1 with the Tet-off induced system or transient transfection. In addition, HDAC1 overexpression led to senescence through both an accumulation of hypophosphorylated active retinoblastoma protein (pRb) and an increase in the protein level of protein phosphatase 2A catalytic subunit (PP2Ac). HDAC1 overexpression also increased the level of Sp1 deacetylation and elevated the interaction between Sp1 and p300, and subsequently that Sp1/p300 complex bound to the promoter of PP2Ac, thus leading to induction of PP2Ac expression. Similar results were obtained in the HDAC1-Tet-off stable clone. Taken together, these results indicate that HDAC1 overexpression restrained cell proliferation and induced premature senescence in cervical cancer cells through a novel Sp1/PP2A/pRb pathway.

Overexpression of HDAC1 induces cellular senescence by Sp1/PP2A/pRb pathway

Energy Technology Data Exchange (ETDEWEB)

Chuang, Jian-Ying [Department of Pharmacology, National Cheng-Kung University, Tainan 701, Taiwan (China); Hung, Jan-Jong, E-mail: petehung@mail.ncku.edu.tw [Department of Pharmacology, National Cheng-Kung University, Tainan 701, Taiwan (China); Institute of Bioinformatics and Biosignal Transduction, National Cheng-Kung University, Tainan 701, Taiwan (China)

2011-04-15

Highlights: {yields} Overexpression of HDAC1 induces Sp1 deacetylation and raises Sp1/p300 complex formation to bind to PP2Ac promoter. {yields} Overexpression of HDAC1 strongly inhibits the phosphorylation of pRb through up-regulation of PP2A. {yields} Overexpressed HDAC1 restrains cell proliferaction and induces cell senescence though a novel Sp1/PP2A/pRb pathway. -- Abstract: Senescence is associated with decreased activities of DNA replication, protein synthesis, and cellular division, which can result in deterioration of cellular functions. Herein, we report that the growth and division of tumor cells were significantly repressed by overexpression of histone deacetylase (HDAC) 1 with the Tet-off induced system or transient transfection. In addition, HDAC1 overexpression led to senescence through both an accumulation of hypophosphorylated active retinoblastoma protein (pRb) and an increase in the protein level of protein phosphatase 2A catalytic subunit (PP2Ac). HDAC1 overexpression also increased the level of Sp1 deacetylation and elevated the interaction between Sp1 and p300, and subsequently that Sp1/p300 complex bound to the promoter of PP2Ac, thus leading to induction of PP2Ac expression. Similar results were obtained in the HDAC1-Tet-off stable clone. Taken together, these results indicate that HDAC1 overexpression restrained cell proliferation and induced premature senescence in cervical cancer cells through a novel Sp1/PP2A/pRb pathway.

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

Science.gov (United States)

Krzesłowska, Magdalena; Rabęda, Irena; Basińska, Aneta; Lewandowski, Michał; Mellerowicz, Ewa J; Napieralska, Anna; Samardakiewicz, Sławomir; Woźny, Adam

2016-07-01

Lead, one of the most abundant and hazardous trace metals affecting living organisms, has been commonly detected in plant cell walls including some tolerant plants, mining ecotypes and hyperaccumulators. We have previously shown that in tip growing Funaria sp. protonemata cell wall is remodeled in response to lead by formation of thickenings rich in low-methylesterified pectins (pectin epitope JIM5 - JIM5-P) able to bind metal ions, which accumulate large amounts of Pb. Hence, it leads to the increase of cell wall capacity for Pb compartmentalization. Here we show that diverse plant species belonging to different phyla (Arabidopsis, hybrid aspen, star duckweed), form similar cell wall thickenings in response to Pb. These thickenings are formed in tip growing cells such as the root hairs, and in diffuse growing cells such as meristematic and root cap columella cells of root apices in hybrid aspen and Arabidopsis and in mesophyll cells in star duckweed fronds. Notably, all analyzed cell wall thickenings were abundant in JIM5-P and accumulated high amounts of Pb. In addition, the co-localization of JIM5-P and Pb commonly occurred in these cells. Hence, cell wall thickenings formed the extra compartment for Pb accumulation. In this way plant cells increased cell wall capacity for compartmentalization of this toxic metal, protecting protoplast from its toxicity. As cell wall thickenings occurred in diverse plant species and cell types differing in the type of growth we may conclude that pectinous cell wall thickenings formation is a widespread defense strategy of plants to cope with Pb. Moreover, detection of natural defense strategy, increasing plant cell walls capacity for metal accumulation, reveals a promising direction for enhancing plant efficiency in phytoremediation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of shear stress on 86Rb+ efflux and cytosolic Ca2+ of calf pulmonary artery endothelial cells (CPAEs)

International Nuclear Information System (INIS)

Alevriadou, B.R.; Mo, M.; Rickman, D.S.; Eskin, S.G.; McIntire, L.V.; Schilling, W.P.

1991-01-01

The effect of flow-induced shear stress (SS) on membrane K + permeability and cytosolic free Ca 2+ , [Ca 2+ ] i , was investigated by measuring 86 Rb + efflux and fura-2 fluorescence in CPAEs using a parallel plate flow chamber. Increasing SS from 1 to 2.4, 4.8 or 10 dyn/cm 2 produced a graded, transient increase in 86 Rb + efflux which peaked within 1 min and subsequently declined rapidly towards pre-stimulus levels. Mathematical modeling confirmed that the transient increase in 86 Rb + efflux did not reflect a washout phenomenon. Upon returning SS to 1 dyn/cm 2 , 86 Rb + efflux initially decreased, but returned slowly to basal values. In contrast, application of bradykinin (BK) at a constant SS of either 0.33 or 1 dyn/cm 2 produced a transient increase in 86 Rb + efflux that was followed by a sustained elevated phase during which time efflux gradually returned to pre-stimulus levels. To determine the mechanism by which shear stress increases K + permeability, the effect of tetrabutylammonium ion (TBA), a selective inhibitor of Ca 2+ -dependent K + channels (K Ca ), on both the BK- and SS-induced increases in 86 Rb + efflux, was examined. TBA inhibited the BK-stimulated increase in 86 Rb + efflux >90% under both stationary and flow conditions and significantly reduced SS-dependent 86 Rb + efflux 38.3%. These results suggest that increased 86 Rb + efflux from CPAEs with SS occurs, at least in part, via K Ca and suggests that SS increases cytosolic Ca 2+ . However, when measured using fura-2-loaded CPAEs, SS was without significant effect on [Ca 2+ ] i

Ethanol yields and cell wall properties in divergently bred switchgrass genotypes

Science.gov (United States)

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...

On the robustness of the geometrical model for cell wall deposition

NARCIS (Netherlands)

Diotallevi, F.; Mulder, B.M.; Grasman, J.

2010-01-01

All plant cells are provided with the necessary rigidity to withstand the turgor by an exterior cell wall. This wall is composed of long crystalline cellulose microfibrils embedded in a matrix of other polysaccharides. The cellulose microfibrils are deposited by mobile membrane bound protein

RB Research nuclear reactor RB reactor, Annual report for 2000

International Nuclear Information System (INIS)

Milosevic, M.

2000-12-01

Report on RB reactor operation during 2000 contains 3 parts. Part one contains a brief description of reactor operation and reactor components, relevant dosimetry data and radiation protection issues, personnel and financial data. Part two is devoted to maintenance of the reactor components, namely, fuel, heavy water, reactor vessel, heavy water circulation system, absorption rods and heavy water level-meters, maintenance of electronic, mechanical, electrical and auxiliary equipment. Part three contains data concerned with reactor operation and utilization with a comprehensive list of publications resulting from experiments done at the RB reactor. It contains data about reactor operation during previous 14 years, i.e. from 1986 - 2000

Cell wall changes during the formation of aerenchyma in sugarcane roots.

Science.gov (United States)

Leite, D C C; Grandis, A; Tavares, E Q P; Piovezani, A R; Pattathil, S; Avci, U; Rossini, A; Cambler, A; De Souza, A P; Hahn, M G; Buckeridge, M S

2017-11-10

Aerenchyma develops in different plant organs and leads to the formation of intercellular spaces that can be used by the plant to transport volatile substances. Little is known about the role of cell walls in this process, although the mechanism of aerenchyma formation is known to involve programmed cell death and some cell wall modifications. We assessed the role that cell wall-related mechanisms might play in the formation of aerenchyma in sugarcane roots. Sections of roots (5 cm) were subjected to microtomography analysis. These roots were divided into 1-cm segments and subjected to cell wall fractionation. We performed analyses of monosaccharides, oligosaccharides and lignin and glycome profiling. Sections were visualized by immunofluorescence and immunogold labelling using selected monoclonal antibodies against polysaccharide epitopes according to the glycome profiles. During aerenchyma formation, gas spaces occupied up to 40 % of the cortex cross-section within the first 5 cm of the root. As some of the cortex cells underwent dissolution of the middle lamellae, leading to cell separation, cell expansion took place along with cell death. Mixed-linkage β-glucan was degraded along with some homogalacturonan and galactan, culminating in the formation of cell wall composites made of xyloglucan, arabinoxylans, cellulose and possibly lignin. The composites formed seem to play a role in the physical-chemical properties of the gas chambers, providing mechanical resistance to forces acting upon the root and at the same time decreasing permeability to gases. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Measurement of rod-drop time for control and safety rods at the RB reactor; Merenje vremena pada kontrolne sipke i sigurnosnih sipki reaktora RB