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

PubMed

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.

Ethanol yields and cell wall properties in divergently bred switchgrass genotypes

USDA-ARS?s Scientific Manuscript database

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...

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

PubMed

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.

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

PubMed

Mélida, Hugo; Largo-Gosens, Asier; Novo-Uzal, Esther; Santiago, Rogelio; Pomar, Federico; García, Pedro; García-Angulo, Penélope; Acebes, José Luis; Álvarez, Jesús; Encina, Antonio

2015-04-01

Maize (Zea mays L.) suspension-cultured cells with up to 70% less cellulose were obtained by stepwise habituation to dichlobenil (DCB), a cellulose biosynthesis inhibitor. Cellulose deficiency was accompanied by marked changes in cell wall matrix polysaccharides and phenolics as revealed by Fourier transform infrared (FTIR) spectroscopy. Cell wall compositional analysis indicated that the cellulose-deficient cell walls showed an enhancement of highly branched and cross-linked arabinoxylans, as well as an increased content in ferulic acid, diferulates and p-coumaric acid, and the presence of a polymer that stained positive for phloroglucinol. In accordance with this, cellulose-deficient cell walls showed a fivefold increase in Klason-type lignin. Thioacidolysis/GC-MS analysis of cellulose-deficient cell walls indicated the presence of a lignin-like polymer with a Syringyl/Guaiacyl ratio of 1.45, which differed from the sensu stricto stress-related lignin that arose in response to short-term DCB-treatments. Gene expression analysis of these cells indicated an overexpression of genes specific for the biosynthesis of monolignol units of lignin. A study of stress signaling pathways revealed an overexpression of some of the jasmonate signaling pathway genes, which might trigger ectopic lignification in response to cell wall integrity disruptions. In summary, the structural plasticity of primary cell walls is proven, since a lignification process is possible in response to cellulose impoverishment. © 2015 Institute of Botany, Chinese Academy of Sciences.

A Transcriptomic Analysis of Xylan Mutants Does Not Support the Existence of a Secondary Cell Wall Integrity System in Arabidopsis

PubMed Central

Faria-Blanc, Nuno; Mortimer, Jenny C.; Dupree, Paul

2018-01-01

Yeast have long been known to possess a cell wall integrity (CWI) system, and recently an analogous system has been described for the primary walls of plants (PCWI) that leads to changes in plant growth and cell wall composition. A similar system has been proposed to exist for secondary cell walls (SCWI). However, there is little data to support this. Here, we analyzed the stem transcriptome of a set of cell wall biosynthetic mutants in order to investigate whether cell wall damage, in this case caused by aberrant xylan synthesis, activates a signaling cascade or changes in cell wall synthesis gene expression. Our data revealed remarkably few changes to the transcriptome. We hypothesize that this is because cells undergoing secondary cell wall thickening have entered a committed programme leading to cell death, and therefore a SCWI system would have limited impact. The absence of transcriptomic responses to secondary cell wall alterations may facilitate engineering of the secondary cell wall of plants. PMID:29636762

A Transcriptomic Analysis of Xylan Mutants Does Not Support the Existence of a Secondary Cell Wall Integrity System in Arabidopsis.

PubMed

Faria-Blanc, Nuno; Mortimer, Jenny C; Dupree, Paul

2018-01-01

Yeast have long been known to possess a cell wall integrity (CWI) system, and recently an analogous system has been described for the primary walls of plants (PCWI) that leads to changes in plant growth and cell wall composition. A similar system has been proposed to exist for secondary cell walls (SCWI). However, there is little data to support this. Here, we analyzed the stem transcriptome of a set of cell wall biosynthetic mutants in order to investigate whether cell wall damage, in this case caused by aberrant xylan synthesis, activates a signaling cascade or changes in cell wall synthesis gene expression. Our data revealed remarkably few changes to the transcriptome. We hypothesize that this is because cells undergoing secondary cell wall thickening have entered a committed programme leading to cell death, and therefore a SCWI system would have limited impact. The absence of transcriptomic responses to secondary cell wall alterations may facilitate engineering of the secondary cell wall of plants.

A specialized outer layer of the primary cell wall joins elongating cotton fibers into tissue-like bundles.

PubMed

Singh, Bir; Avci, Utku; Eichler Inwood, Sarah E; Grimson, Mark J; Landgraf, Jeff; Mohnen, Debra; Sørensen, Iben; Wilkerson, Curtis G; Willats, William G T; Haigler, Candace H

2009-06-01

Cotton (Gossypium hirsutum) provides the world's dominant renewable textile fiber, and cotton fiber is valued as a research model because of its extensive elongation and secondary wall thickening. Previously, it was assumed that fibers elongated as individual cells. In contrast, observation by cryo-field emission-scanning electron microscopy of cotton fibers developing in situ within the boll demonstrated that fibers elongate within tissue-like bundles. These bundles were entrained by twisting fiber tips and consolidated by adhesion of a cotton fiber middle lamella (CFML). The fiber bundles consolidated via the CFML ultimately formed a packet of fiber around each seed, which helps explain how thousands of cotton fibers achieve their great length within a confined space. The cell wall nature of the CFML was characterized using transmission electron microscopy, including polymer epitope labeling. Toward the end of elongation, up-regulation occurred in gene expression and enzyme activities related to cell wall hydrolysis, and targeted breakdown of the CFML restored fiber individuality. At the same time, losses occurred in certain cell wall polymer epitopes (as revealed by comprehensive microarray polymer profiling) and sugars within noncellulosic matrix components (as revealed by gas chromatography-mass spectrometry analysis of derivatized neutral and acidic glycosyl residues). Broadly, these data show that adhesion modulated by an outer layer of the primary wall can coordinate the extensive growth of a large group of cells and illustrate dynamic changes in primary wall structure and composition occurring during the differentiation of one cell type that spends only part of its life as a tissue.

Monitoring Meso-Scale Ordering of Cellulose in Intact Plant Cell Walls Using Sum Frequency Generation Spectroscopy1[C][W][OPEN

PubMed Central

Park, Yong Bum; Lee, Christopher M.; Koo, Bon-Wook; Park, Sunkyu; Cosgrove, Daniel J.; Kim, Seong H.

2013-01-01

Sum frequency generation (SFG) vibration spectroscopy can selectively detect crystalline cellulose without spectral interference from cell wall matrix components. Here, we show that the cellulose SFG spectrum is sensitive to cellulose microfibril alignment and packing within the cell wall. SFG intensity at 2,944 cm−1 correlated well with crystalline cellulose contents of various regions of the Arabidopsis (Arabidopsis thaliana) inflorescence, while changes in the 3,320/2,944 cm−1 intensity ratio suggest subtle changes in cellulose ordering as tissues mature. SFG analysis of two cellulose synthase mutants (irx1/cesa8 and irx3/cesa7) indicates a reduction in cellulose content without evidence of altered cellulose structure. In primary cell walls of Arabidopsis, cellulose exhibited a characteristic SFG peak at 2,920 and 3,320 cm−1, whereas in secondary cell walls, it had peaks at 2,944 and 3,320 cm−1. Starch (amylose) gave an SFG peak at 2,904 cm−1 (CH methine) whose intensity increased with light exposure prior to harvest. Selective removal of matrix polysaccharides from primary cell walls by acid hydrolysis resulted in an SFG spectrum resembling that of secondary wall cellulose. Our results show that SFG spectroscopy is sensitive to the ordering of cellulose microfibrils in plant cell walls at the meso scale (nm to μm) that is important for cell wall architecture but cannot be probed by other spectroscopic or diffraction techniques. PMID:23995148

Monitoring meso-scale ordering of cellulose in intact plant cell walls using sum frequency generation spectroscopy.

PubMed

Park, Yong Bum; Lee, Christopher M; Koo, Bon-Wook; Park, Sunkyu; Cosgrove, Daniel J; Kim, Seong H

2013-10-01

Sum frequency generation (SFG) vibration spectroscopy can selectively detect crystalline cellulose without spectral interference from cell wall matrix components. Here, we show that the cellulose SFG spectrum is sensitive to cellulose microfibril alignment and packing within the cell wall. SFG intensity at 2,944 cm(-1) correlated well with crystalline cellulose contents of various regions of the Arabidopsis (Arabidopsis thaliana) inflorescence, while changes in the 3,320/2,944 cm(-1) intensity ratio suggest subtle changes in cellulose ordering as tissues mature. SFG analysis of two cellulose synthase mutants (irx1/cesa8 and irx3/cesa7) indicates a reduction in cellulose content without evidence of altered cellulose structure. In primary cell walls of Arabidopsis, cellulose exhibited a characteristic SFG peak at 2,920 and 3,320 cm(-1), whereas in secondary cell walls, it had peaks at 2,944 and 3,320 cm(-1). Starch (amylose) gave an SFG peak at 2,904 cm(-1) (CH methine) whose intensity increased with light exposure prior to harvest. Selective removal of matrix polysaccharides from primary cell walls by acid hydrolysis resulted in an SFG spectrum resembling that of secondary wall cellulose. Our results show that SFG spectroscopy is sensitive to the ordering of cellulose microfibrils in plant cell walls at the meso scale (nm to μm) that is important for cell wall architecture but cannot be probed by other spectroscopic or diffraction techniques.

Characterizing phenolformaldehyde adhesive cure chemistry within the wood cell wall

Treesearch

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...

Comprehensive transcriptome analyses correlated with untargeted metabolome reveal differentially expressed pathways in response to cell wall alterations.

PubMed

Reem, Nathan T; Chen, Han-Yi; Hur, Manhoi; Zhao, Xuefeng; Wurtele, Eve Syrkin; Li, Xu; Li, Ling; Zabotina, Olga

2018-03-01

This research provides new insights into plant response to cell wall perturbations through correlation of transcriptome and metabolome datasets obtained from transgenic plants expressing cell wall-modifying enzymes. Plants respond to changes in their cell walls in order to protect themselves from pathogens and other stresses. Cell wall modifications in Arabidopsis thaliana have profound effects on gene expression and defense response, but the cell signaling mechanisms underlying these responses are not well understood. Three transgenic Arabidopsis lines, two with reduced cell wall acetylation (AnAXE and AnRAE) and one with reduced feruloylation (AnFAE), were used in this study to investigate the plant responses to cell wall modifications. RNA-Seq in combination with untargeted metabolome was employed to assess differential gene expression and metabolite abundance. RNA-Seq results were correlated with metabolite abundances to determine the pathways involved in response to cell wall modifications introduced in each line. The resulting pathway enrichments revealed the deacetylation events in AnAXE and AnRAE plants induced similar responses, notably, upregulation of aromatic amino acid biosynthesis and changes in regulation of primary metabolic pathways that supply substrates to specialized metabolism, particularly those related to defense responses. In contrast, genes and metabolites of lipid biosynthetic pathways and peroxidases involved in lignin polymerization were downregulated in AnFAE plants. These results elucidate how primary metabolism responds to extracellular stimuli. Combining the transcriptomics and metabolomics datasets increased the power of pathway prediction, and demonstrated the complexity of pathways involved in cell wall-mediated signaling.

Plant cell wall proteomics: the leadership of Arabidopsis thaliana

PubMed Central

Albenne, Cécile; Canut, Hervé; Jamet, Elisabeth

2013-01-01

Plant cell wall proteins (CWPs) progressively emerged as crucial components of cell walls although present in minor amounts. Cell wall polysaccharides such as pectins, hemicelluloses, and cellulose represent more than 90% of primary cell wall mass, whereas hemicelluloses, cellulose, and lignins are the main components of lignified secondary walls. All these polymers provide mechanical properties to cell walls, participate in cell shape and prevent water loss in aerial organs. However, cell walls need to be modified and customized during plant development and in response to environmental cues, thus contributing to plant adaptation. CWPs play essential roles in all these physiological processes and particularly in the dynamics of cell walls, which requires organization and rearrangements of polysaccharides as well as cell-to-cell communication. In the last 10 years, plant cell wall proteomics has greatly contributed to a wider knowledge of CWPs. This update will deal with (i) a survey of plant cell wall proteomics studies with a focus on Arabidopsis thaliana; (ii) the main protein families identified and the still missing peptides; (iii) the persistent issue of the non-canonical CWPs; (iv) the present challenges to overcome technological bottlenecks; and (v) the perspectives beyond cell wall proteomics to understand CWP functions. PMID:23641247

Electron Tomography of Cryo-Immobilized Plant Tissue: A Novel Approach to Studying 3D Macromolecular Architecture of Mature Plant Cell Walls In Situ

PubMed Central

Sarkar, Purbasha; Bosneaga, Elena; Yap, Edgar G.; Das, Jyotirmoy; Tsai, Wen-Ting; Cabal, Angelo; Neuhaus, Erica; Maji, Dolonchampa; Kumar, Shailabh; Joo, Michael; Yakovlev, Sergey; Csencsits, Roseann; Yu, Zeyun; Bajaj, Chandrajit; Downing, Kenneth H.; Auer, Manfred

2014-01-01

Cost-effective production of lignocellulosic biofuel requires efficient breakdown of cell walls present in plant biomass to retrieve the wall polysaccharides for fermentation. In-depth knowledge of plant cell wall composition is therefore essential for improving the fuel production process. The precise spatial three-dimensional (3D) organization of cellulose, hemicellulose, pectin and lignin within plant cell walls remains unclear to date since the microscopy techniques used so far have been limited to two-dimensional, topographic or low-resolution imaging, or required isolation or chemical extraction of the cell walls. In this paper we demonstrate that by cryo-immobilizing fresh tissue, then either cryo-sectioning or freeze-substituting and resin embedding, followed by cryo- or room temperature (RT) electron tomography, respectively, we can visualize previously unseen details of plant cell wall architecture in 3D, at macromolecular resolution (∼2 nm), and in near-native state. Qualitative and quantitative analyses showed that wall organization of cryo-immobilized samples were preserved remarkably better than conventionally prepared samples that suffer substantial extraction. Lignin-less primary cell walls were well preserved in both self-pressurized rapidly frozen (SPRF), cryo-sectioned samples as well as high-pressure frozen, freeze-substituted and resin embedded (HPF-FS-resin) samples. Lignin-rich secondary cell walls appeared featureless in HPF-FS-resin sections presumably due to poor stain penetration, but their macromolecular features could be visualized in unprecedented details in our cryo-sections. While cryo-tomography of vitreous tissue sections is currently proving to be instrumental in developing 3D models of lignin-rich secondary cell walls, here we confirm that the technically easier method of RT-tomography of HPF-FS-resin sections could be used immediately for routine study of low-lignin cell walls. As a proof of principle, we characterized the primary cell walls of a mutant (cob-6) and wild type Arabidopsis hypocotyl parenchyma cells by RT-tomography of HPF-FS-resin sections, and detected a small but significant difference in spatial organization of cellulose microfibrils in the mutant walls. PMID:25207917

THE PRIMARY CELL WALL. Progress Report, February 1, 1963 to October 31, 1963

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varner, J.E.

1964-10-31

Progress is reported in studies of hydroxyproline synthesis in sycamore cells grown in suspensions with and without the addition of D/sub 2/O. The relation of hydroxyproline to cellulose in cell walls was investigated in suspensions of cells from sycamore and ginkgo cell suspensions. (C.H.)

Xyloglucan Deficiency Disrupts Microtubule Stability and Cellulose Biosynthesis in Arabidopsis, Altering Cell Growth and Morphogenesis1[OPEN

PubMed Central

Xiao, Chaowen; Zhang, Tian; Zheng, Yunzhen

2016-01-01

Xyloglucan constitutes most of the hemicellulose in eudicot primary cell walls and functions in cell wall structure and mechanics. Although Arabidopsis (Arabidopsis thaliana) xxt1 xxt2 mutants lacking detectable xyloglucan are viable, they display growth defects that are suggestive of alterations in wall integrity. To probe the mechanisms underlying these defects, we analyzed cellulose arrangement, microtubule patterning and dynamics, microtubule- and wall-integrity-related gene expression, and cellulose biosynthesis in xxt1 xxt2 plants. We found that cellulose is highly aligned in xxt1 xxt2 cell walls, that its three-dimensional distribution is altered, and that microtubule patterning and stability are aberrant in etiolated xxt1 xxt2 hypocotyls. We also found that the expression levels of microtubule-associated genes, such as MAP70-5 and CLASP, and receptor genes, such as HERK1 and WAK1, were changed in xxt1 xxt2 plants and that cellulose synthase motility is reduced in xxt1 xxt2 cells, corresponding with a reduction in cellulose content. Our results indicate that loss of xyloglucan affects both the stability of the microtubule cytoskeleton and the production and patterning of cellulose in primary cell walls. These findings establish, to our knowledge, new links between wall integrity, cytoskeletal dynamics, and wall synthesis in the regulation of plant morphogenesis. PMID:26527657

Xyloglucan Deficiency Disrupts Microtubule Stability and Cellulose Biosynthesis in Arabidopsis, Altering Cell Growth and Morphogenesis

DOE PAGES

Xiao, Chaowen; Zhang, Tian; Zheng, Yunzhen; ...

2015-11-02

Here, xyloglucan constitutes most of the hemicellulose in eudicot primary cell walls and functions in cell wall structure and mechanics. Although Arabidopsis ( Arabidopsis thaliana) xxt1 xxt2 mutants lacking detectable xyloglucan are viable, they display growth defects that are suggestive of alterations in wall integrity. To probe the mechanisms underlying these defects, we analyzed cellulose arrangement, microtubule patterning and dynamics, microtubule- and wall-integrity-related gene expression, and cellulose biosynthesis in xxt1 xxt2 plants. We found that cellulose is highly aligned in xxt1 xxt2 cell walls, that its three-dimensional distribution is altered, and that microtubule patterning and stability are aberrant in etiolatedmore » xxt1 xxt2 hypocotyls. We also found that the expression levels of microtubule-associated genes, such as MAP70-5 and CLASP, and receptor genes, such as HERK1 and WAK1, were changed in xxt1 xxt2 plants and that cellulose synthase motility is reduced in xxt1 xxt2 cells, corresponding with a reduction in cellulose content. Our results indicate that loss of xyloglucan affects both the stability of the microtubule cytoskeleton and the production and patterning of cellulose in primary cell walls. These findings establish, to our knowledge, new links between wall integrity, cytoskeletal dynamics, and wall synthesis in the regulation of plant morphogenesis.« less

Dynamic Changes of Pectin Epitopes in Cell Walls during the Development of the Procambium–Cambium Continuum in Poplar

PubMed Central

Liu, Jundi; Hou, Jie; Chen, Huimin; Pei, Keliang; Li, Yi; He, Xin-Qiang

2017-01-01

The change of pectin epitopes during procambium–cambium continuum development was investigated by immunolocalization in poplar. The monoclonal antibody JIM5 labels homogalacturonan (HGA) with a low degree of esterification, and the monoclonal antibody JIM7 labels HGA with a high degree of methyl-esterification. Arabinan, rather than galactan, and HGA with low degree of esterification were located in the cell walls of procambial, while HGA with a low degree of esterification was located in the tangential walls, and galactan was located in both the tangential and radial walls of procambial, yet nearly no arabinan was located in the tangential walls of the cambial cells. The changes in pectin distribution took place when periclinal divisions appeared within a procambial trace. The distribution difference of pectin epitopes was also present in procambium–cambium derivatives. The arabinan existed in all cell walls of primary xylem, but was absent from the tangential walls of secondary xylem cells. The galactan existed only in mature primary phloem. Furthermore, 19 pectin methylesterases (PMEs) genes were identified by RNA sequencing, six genes presented highly differentially and were supposed to be involved in the cell wall esterification process. The results provide direct evidence of the dynamic changes of pectin epitopes during the development of the procambium–cambium continuum in poplar. PMID:28783076

Xyloglucan Deficiency Disrupts Microtubule Stability and Cellulose Biosynthesis in Arabidopsis, Altering Cell Growth and Morphogenesis.

PubMed

Xiao, Chaowen; Zhang, Tian; Zheng, Yunzhen; Cosgrove, Daniel J; Anderson, Charles T

2016-01-01

Xyloglucan constitutes most of the hemicellulose in eudicot primary cell walls and functions in cell wall structure and mechanics. Although Arabidopsis (Arabidopsis thaliana) xxt1 xxt2 mutants lacking detectable xyloglucan are viable, they display growth defects that are suggestive of alterations in wall integrity. To probe the mechanisms underlying these defects, we analyzed cellulose arrangement, microtubule patterning and dynamics, microtubule- and wall-integrity-related gene expression, and cellulose biosynthesis in xxt1 xxt2 plants. We found that cellulose is highly aligned in xxt1 xxt2 cell walls, that its three-dimensional distribution is altered, and that microtubule patterning and stability are aberrant in etiolated xxt1 xxt2 hypocotyls. We also found that the expression levels of microtubule-associated genes, such as MAP70-5 and CLASP, and receptor genes, such as HERK1 and WAK1, were changed in xxt1 xxt2 plants and that cellulose synthase motility is reduced in xxt1 xxt2 cells, corresponding with a reduction in cellulose content. Our results indicate that loss of xyloglucan affects both the stability of the microtubule cytoskeleton and the production and patterning of cellulose in primary cell walls. These findings establish, to our knowledge, new links between wall integrity, cytoskeletal dynamics, and wall synthesis in the regulation of plant morphogenesis. © 2016 American Society of Plant Biologists. All Rights Reserved.

Spatial organization of cellulose microfibrils and matrix polysaccharides in primary plant cell walls as imaged by multichannel atomic force microscopy.

PubMed

Zhang, Tian; Zheng, Yunzhen; Cosgrove, Daniel J

2016-01-01

We used atomic force microscopy (AFM), complemented with electron microscopy, to characterize the nanoscale and mesoscale structure of the outer (periclinal) cell wall of onion scale epidermis - a model system for relating wall structure to cell wall mechanics. The epidermal wall contains ~100 lamellae, each ~40 nm thick, containing 3.5-nm wide cellulose microfibrils oriented in a common direction within a lamella but varying by ~30 to 90° between adjacent lamellae. The wall thus has a crossed polylamellate, not helicoidal, wall structure. Montages of high-resolution AFM images of the newly deposited wall surface showed that single microfibrils merge into and out of short regions of microfibril bundles, thereby forming a reticulated network. Microfibril direction within a lamella did not change gradually or abruptly across the whole face of the cell, indicating continuity of the lamella across the outer wall. A layer of pectin at the wall surface obscured the underlying cellulose microfibrils when imaged by FESEM, but not by AFM. The AFM thus preferentially detects cellulose microfibrils by probing through the soft matrix in these hydrated walls. AFM-based nanomechanical maps revealed significant heterogeneity in cell wall stiffness and adhesiveness at the nm scale. By color coding and merging these maps, the spatial distribution of soft and rigid matrix polymers could be visualized in the context of the stiffer microfibrils. Without chemical extraction and dehydration, our results provide multiscale structural details of the primary cell wall in its near-native state, with implications for microfibrils motions in different lamellae during uniaxial and biaxial extensions. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Enzymes and other agents that enhance cell wall extensibility

NASA Technical Reports Server (NTRS)

Cosgrove, D. J.

1999-01-01

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

The role of the hemicelluloses in the nanobiology of wood cell walls : a systems theoretic perspective

Treesearch

Rajai H. Atalla

2005-01-01

The hemicelluloses have not received adequate attention in studies of wood cell walls because the complexity of their structures does not admit easy interpretation within the paradigms of polymer science. Two-phase composite models of the cell wall have led many to view their primary function as one of coupling cellulose and lignin to enhance the mechanical properties...

Fission yeast Ags1 confers the essential septum strength needed for safe gradual cell abscission

PubMed Central

Sato, Mamiko; Muñoz, Javier; Moreno, M. Belén; Clemente-Ramos, Jose Angel; Ramos, Mariona; Okada, Hitoshi; Osumi, Masako; Durán, Angel; Ribas, Juan Carlos

2012-01-01

Fungal cytokinesis requires the assembly of a dividing septum wall. In yeast, the septum has to be selectively digested during the critical cell separation process. Fission yeast cell wall α(1-3)glucan is essential, but nothing is known about its localization and function in the cell wall or about cooperation between the α- and β(1-3)glucan synthases Ags1 and Bgs for cell wall and septum assembly. Here, we generate a physiological Ags1-GFP variant and demonstrate a tight colocalization with Bgs1, suggesting a cooperation in the important early steps of septum construction. Moreover, we define the essential functions of α(1-3)glucan in septation and cell separation. We show that α(1-3)glucan is essential for both secondary septum formation and the primary septum structural strength needed to support the physical forces of the cell turgor pressure during cell separation. Consequently, the absence of Ags1 and therefore α(1-3)glucan generates a special and unique side-explosive cell separation due to an instantaneous primary septum tearing caused by the turgor pressure. PMID:22891259

Angiogenesis and phenotypic alteration of alveolar capillary endothelium in areas of neoplastic cell spread in primary lung adenocarcinoma.

PubMed

Jin, E; Ghazizadeh, M; Fujiwara, M; Nagashima, M; Shimizu, H; Ohaki, Y; Arai, S; Gomibuchi, M; Takemura, T; Kawanami, O

2001-09-01

Normal alveolar capillary endothelium is quiescent in nature and displays anticoagulant thrombomodulin (TM) on its surface. The cytoplasms of these endothelial cells are ultrastructurally non-fenestrated type, and they barely express von Willebrand factor (vWf). Alveolar fibrosis is accompanied by a capillary endothelium reactive for vWf, and a loss of TM expression. In primary lung adenocarcinoma, neovascularization occurs in association with alveolar fibrosis. In order to study basic factors related to angiogenesis and phenotypic changes of the capillaries located in tumor-bearing alveolar walls, we examined 37 primary lung adenocarcinomas with electron microscopy and confocal laser scanning microscopy with antibodies for TM, vWf, vascular endothelial growth factor (VEGF), and its receptors (KDR and Flt-1), and proliferating markers (Ki-67/proliferating cell nuclear antigen). Tissues microdissected specifically from alveolar walls were used for reverse transcription-polymerase chain reaction (RT-PCR) to assess expressions of mRNA isoforms of VEGF and its receptors. New capillary branching was found by ultrastructural study in the alveolar walls in 12% of the patients. Nuclei of the capillary endothelial cells were reactive for proliferating cell markers. Endothelial fenestrae were developed in 65% of the patients, TM reactivity was lost in the alveolar capillaries, and their cell cytoplasms obtained a reactivity for vWf through a transitional mosaic-like distribution pattern of both antigens. Besides cytoplasmic VEGF expression in neoplastic cells, tumor-bearing alveolar walls showed significant expression of mRNA of VEGF165 and KDR. These findings imply that angiogenesis and phenotypic changes of the alveolar capillaries are closely related to a higher expression of tumor-associated VEGF165 and of KDR in the alveolar walls in primary lung adenocarcinoma.

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

PubMed

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.

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

PubMed

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.

The molecular basis of plant cell wall extension.

PubMed

Darley, C P; Forrester, A M; McQueen-Mason, S J

2001-09-01

In all terrestrial and aquatic plant species the primary cell wall is a dynamic structure, adjusted to fulfil a diversity of functions. However a universal property is its considerable mechanical and tensile strength, whilst being flexible enough to accommodate turgor and allow for cell elongation. The wall is a composite material consisting of a framework of cellulose microfibrils embedded in a matrix of non-cellulosic polysaccharides, interlaced with structural proteins and pectic polymers. The assembly and modification of these polymers within the growing cell wall has, until recently, been poorly understood. Advances in cytological and genetic techniques have thrown light on these processes and have led to the discovery of a number of wall-modifying enzymes which, either directly or indirectly, play a role in the molecular basis of cell wall expansion.

Phenolic components of the primary cell wall. Feruloylated disaccharides of D-galactose and L-arabinose from spinach polysaccharide.

PubMed Central

Fry, S C

1982-01-01

1. Cell walls from rapidly growing cell suspension cultures of Spinacia oleracea L. contained ferulic acid and p-coumaric acid esterified with a water-insoluble polymer. 2. Prolonged treatment with trypsin did not release may feruloyl esters from dearabinofuranosylated cell walls, and the polymer was also insoluble in phenol/acetic acid/water (2:1:1, w/v/v). 3. Treatment of the cell walls with the fungal hydrolase preparation "Driselase' did liberate low-Mr feruloyl esters. The major esters were 4-O-(6-O-feruloyl-beta-D-galactopyranosyl)-D-galactose and 3?-O-feruloyl-alpha-L-arabinopyranosyl)-L-arabinose. These two esters accounted for about 60% of the cell-wall ferulate. 4. It is concluded that the feruloylation of cell-wall polymers is not a random process, but occurs at very specific sites, probably on the arabinogalactan component of pectin. 5. The possible role of such phenolic substituents in cell-wall architecture and growth is discussed. PMID:7115300

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

PubMed Central

Yu, Qin; Hlavacka, Andrej; Matoh, Toru; Volkmann, Dieter; Menzel, Diedrik; Goldbach, Heiner E.; Baluška, František

2002-01-01

By using immunofluorescence microscopy, we observed rapidly altered distribution patterns of cell wall pectins in meristematic cells of maize (Zea mays) and wheat (Triticum aestivum) root apices. This response was shown for homogalacturonan pectins characterized by a low level (up to 40%) of methylesterification and for rhamnogalacturonan II pectins cross-linked by a borate diol diester. Under boron deprivation, abundance of these pectins rapidly increased in cell walls, whereas their internalization was inhibited, as evidenced by a reduced and even blocked accumulation of these cell wall pectins within brefeldin A-induced compartments. In contrast, root cells of species sensitive to the boron deprivation, like zucchini (Cucurbita pepo) and alfalfa (Medicago sativa), do not internalize cell wall pectins into brefeldin A compartments and do not show accumulation of pectins in their cell walls under boron deprivation. For maize and wheat root apices, we favor an apoplastic target for the primary action of boron deprivation, which signals deeper into the cell via endocytosis-mediated pectin signaling along putative cell wall-plasma membrane-cytoskeleton continuum. PMID:12226520

The Specific Nature of Plant Cell Wall Polysaccharides 1

PubMed Central

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

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

PubMed

Ptashnyk, Mariya; Seguin, Brian

2016-11-01

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

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

PubMed

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.

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

PubMed

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.

Developmental and Tissue-Specific Structural Alterations of the Cell-Wall Polysaccharides of Arabidopsis thaliana Roots.

PubMed Central

Freshour, G.; Clay, R. P.; Fuller, M. S.; Albersheim, P.; Darvill, A. G.; Hahn, M. G.

1996-01-01

The plant cell wall is a dynamic structure that plays important roles in growth and development and in the interactions of plants with their environment and other organisms. We have used monoclonal antibodies that recognize different carbohydrate epitopes present in plant cell-wall polysaccharides to locate these epitopes in roots of developing Arabidopsis thaliana seedlings. An epitope in the pectic polysaccharide rhamnogalacturonan I is observed in the walls of epidermal and cortical cells in mature parts of the root. This epitope is inserted into the walls in a developmentally regulated manner. Initially, the epitope is observed in atrichoblasts and later appears in trichoblasts and simultaneously in cortical cells. A terminal [alpha]-fucosyl-containing epitope is present in almost all of the cell walls in the root. An arabinosylated (1->6)-[beta]-galactan epitope is also found in all of the cell walls of the root with the exception of lateral root-cap cell walls. It is striking that these three polysaccharide epitopes are not uniformly distributed (or accessible) within the walls of a given cell, nor are these epitopes distributed equally across the two walls laid down by adjacent cells. Our results further suggest that the biosynthesis and differentiation of primary cell walls in plants are precisely regulated in a temporal, spatial, and developmental manner. PMID:12226270

Atomic force microscopy stiffness tomography on living Arabidopsis thaliana cells reveals the mechanical properties of surface and deep cell-wall layers during growth.

PubMed

Radotić, Ksenija; Roduit, Charles; Simonović, Jasna; Hornitschek, Patricia; Fankhauser, Christian; Mutavdžić, Dragosav; Steinbach, Gabor; Dietler, Giovanni; Kasas, Sandor

2012-08-08

Cell-wall mechanical properties play a key role in the growth and the protection of plants. However, little is known about genuine wall mechanical properties and their growth-related dynamics at subcellular resolution and in living cells. Here, we used atomic force microscopy (AFM) stiffness tomography to explore stiffness distribution in the cell wall of suspension-cultured Arabidopsis thaliana as a model of primary, growing cell wall. For the first time that we know of, this new imaging technique was performed on living single cells of a higher plant, permitting monitoring of the stiffness distribution in cell-wall layers as a function of the depth and its evolution during the different growth phases. The mechanical measurements were correlated with changes in the composition of the cell wall, which were revealed by Fourier-transform infrared (FTIR) spectroscopy. In the beginning and end of cell growth, the average stiffness of the cell wall was low and the wall was mechanically homogenous, whereas in the exponential growth phase, the average wall stiffness increased, with increasing heterogeneity. In this phase, the difference between the superficial and deep wall stiffness was highest. FTIR spectra revealed a relative increase in the polysaccharide/lignin content. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

In tobacco BY-2 cells xyloglucan oligosaccharides alter the expression of genes involved in cell wall metabolism, signalling, stress responses, cell division and transcriptional control.

PubMed

González-Pérez, Lien; Perrotta, Lara; Acosta, Alexis; Orellana, Esteban; Spadafora, Natasha; Bruno, Leonardo; Bitonti, Beatrice M; Albani, Diego; Cabrera, Juan Carlos; Francis, Dennis; Rogers, Hilary J

2014-10-01

Xyloglucan oligosaccharides (XGOs) are breakdown products of XGs, the most abundant hemicelluloses of the primary cell walls of non-Poalean species. Treatment of cell cultures or whole plants with XGOs results in accelerated cell elongation and cell division, changes in primary root growth, and a stimulation of defence responses. They may therefore act as signalling molecules regulating plant growth and development. Previous work suggests an interaction with auxins and effects on cell wall loosening, however their mode of action is not fully understood. The effect of an XGO extract from tamarind (Tamarindus indica) on global gene expression was therefore investigated in tobacco BY-2 cells using microarrays. Over 500 genes were differentially regulated with similar numbers and functional classes of genes up- and down-regulated, indicating a complex interaction with the cellular machinery. Up-regulation of a putative XG endotransglycosylase/hydrolase-related (XTH) gene supports the mechanism of XGO action through cell wall loosening. Differential expression of defence-related genes supports a role for XGOs as elicitors. Changes in the expression of genes related to mitotic control and differentiation also support previous work showing that XGOs are mitotic inducers. XGOs also affected expression of several receptor-like kinase genes and transcription factors. Hence, XGOs have significant effects on expression of genes related to cell wall metabolism, signalling, stress responses, cell division and transcriptional control.

Changes in the abundance of cell wall apiogalacturonan and xylogalacturonan and conservation of rhamnogalacturonan II structure during the diversification of the Lemnoideae.

PubMed

Avci, Utku; Peña, Maria J; O'Neill, Malcolm A

2018-04-01

The diversification of the Lemnoideae was accompanied by a reduction in the abundance of cell wall apiogalacturonan and an increase in xylogalacturonan whereas rhamnogalacturonan II structure and cross-linking are conserved. The subfamily Lemnoideae is comprised of five genera and 38 species of small, fast-growing aquatic monocots. Lemna minor and Spirodela polyrhiza belong to this subfamily and have primary cell walls that contain large amounts of apiogalacturonan and thus are distinct from the primary walls of most other flowering plants. However, the pectins in the cell walls of other members of the Lemnoideae have not been investigated. Here, we show that apiogalacturonan decreased substantially as the Lemnoideae diversified since Wolffiella and Wolffia walls contain between 63 and 88% less apiose than Spirodela, Landoltia, and Lemna walls. In Wolffia, the most derived genus, xylogalacturonan is far more abundant than apiogalacturonan, whereas in Wolffiella pectic polysaccharides have a high arabinose content, which may arise from arabinan sidechains of RG I. The apiose-containing pectin rhamnogalacturonan II (RG-II) exists in Lemnoideae walls as a borate cross-linked dimer and has a glycosyl sequence similar to RG-II from terrestrial plants. Nevertheless, species-dependent variations in the extent of methyl-etherification of RG-II sidechain A and arabinosylation of sidechain B are discernible. Immunocytochemical studies revealed that pectin methyl-esterification is higher in developing daughter frond walls than in mother frond walls, indicating that methyl-esterification is associated with expanding cells. Our data support the notion that a functional cell wall requires conservation of RG-II structure and cross-linking but can accommodate structural changes in other pectins. The Lemnoideae provide a model system to study the mechanisms by which wall structure and composition has changed in closely related plants with similar growth habits.

Golgi-Mediated Synthesis and Secretion of Matrix Polysaccharides of the Primary Cell Wall of Higher Plants

PubMed Central

Driouich, Azeddine; Follet-Gueye, Marie-Laure; Bernard, Sophie; Kousar, Sumaira; Chevalier, Laurence; Vicré-Gibouin, Maïté; Lerouxel, Olivier

2012-01-01

The Golgi apparatus of eukaryotic cells is known for its central role in the processing, sorting, and transport of proteins to intra- and extra-cellular compartments. In plants, it has the additional task of assembling and exporting the non-cellulosic polysaccharides of the cell wall matrix including pectin and hemicelluloses, which are important for plant development and protection. In this review, we focus on the biosynthesis of complex polysaccharides of the primary cell wall of eudicotyledonous plants. We present and discuss the compartmental organization of the Golgi stacks with regards to complex polysaccharide assembly and secretion using immuno-electron microscopy and specific antibodies recognizing various sugar epitopes. We also discuss the significance of the recently identified Golgi-localized glycosyltransferases responsible for the biosynthesis of xyloglucan (XyG) and pectin. PMID:22639665

Golgi-mediated synthesis and secretion of matrix polysaccharides of the primary cell wall of higher plants.

PubMed

Driouich, Azeddine; Follet-Gueye, Marie-Laure; Bernard, Sophie; Kousar, Sumaira; Chevalier, Laurence; Vicré-Gibouin, Maïté; Lerouxel, Olivier

2012-01-01

The Golgi apparatus of eukaryotic cells is known for its central role in the processing, sorting, and transport of proteins to intra- and extra-cellular compartments. In plants, it has the additional task of assembling and exporting the non-cellulosic polysaccharides of the cell wall matrix including pectin and hemicelluloses, which are important for plant development and protection. In this review, we focus on the biosynthesis of complex polysaccharides of the primary cell wall of eudicotyledonous plants. We present and discuss the compartmental organization of the Golgi stacks with regards to complex polysaccharide assembly and secretion using immuno-electron microscopy and specific antibodies recognizing various sugar epitopes. We also discuss the significance of the recently identified Golgi-localized glycosyltransferases responsible for the biosynthesis of xyloglucan (XyG) and pectin.

Border cell release: Cell separation without cell wall degradation?

PubMed

Mravec, Jozef

2017-07-03

Plant border cells are specialized cells derived from the root cap with roles in the biomechanics of root growth and in forming a barrier against pathogens. The mechanism of highly localized cell separation which is essential for their release to the environment is little understood. Here I present in situ analysis of Brachypodium distachyon, a model organism for grasses which possess type II primary cell walls poor in pectin content. Results suggest similarity in spatial dynamics of pectic homogalacturonan during dicot and monocot border cell release. Integration of observations from different species leads to the hypothesis that this process most likely does not involve degradation of cell wall material but rather uses unique cell wall structural and compositional means enabling both the rigidity of the root cap as well as detachability of given cells on its surface.

Atomic force microscopy based nanoindentation study of onion abaxial epidermis walls in aqueous environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xi, Xiaoning; Tittmann, Bernhard; Kim, Seong H.

An atomic force microscopy based nanoindentation method was employed to study how the structure of cellulose microfibril packing and matrix polymers affect elastic modulus of fully hydrated primary plant cell walls. The isolated, single-layered abaxial epidermis cell wall of an onion bulb was used as a test system since the cellulose microfibril packing in this cell wall is known to vary systematically from inside to outside scales and the most abundant matrix polymer, pectin, can easily be altered through simple chemical treatments such as ethylenediaminetetraacetic acid and calcium ions. Experimental results showed that the pectin network variation has significant impactsmore » on the cell wall modulus, and not the cellulose microfibril packing.« less

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

PubMed Central

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

2013-01-01

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

Evolution and diversity of plant cell walls: from algae to flowering plants.

PubMed

Popper, Zoë A; Michel, Gurvan; Hervé, Cécile; Domozych, David S; Willats, William G T; Tuohy, Maria G; Kloareg, Bernard; Stengel, Dagmar B

2011-01-01

All photosynthetic multicellular Eukaryotes, including land plants and algae, have cells that are surrounded by a dynamic, complex, carbohydrate-rich cell wall. The cell wall exerts considerable biological and biomechanical control over individual cells and organisms, thus playing a key role in their environmental interactions. This has resulted in compositional variation that is dependent on developmental stage, cell type, and season. Further variation is evident that has a phylogenetic basis. Plants and algae have a complex phylogenetic history, including acquisition of genes responsible for carbohydrate synthesis and modification through a series of primary (leading to red algae, green algae, and land plants) and secondary (generating brown algae, diatoms, and dinoflagellates) endosymbiotic events. Therefore, organisms that have the shared features of photosynthesis and possession of a cell wall do not form a monophyletic group. Yet they contain some common wall components that can be explained increasingly by genetic and biochemical evidence.

A fiber-reinforced-fluid model of anisotropic plant root cell growth

NASA Astrophysics Data System (ADS)

Jensen, Oliver E.; Dyson, Rosemary J.

2009-11-01

We present a theoretical model of a single cell in the expansion zone of the primary root of the plant Arabidopsis thaliana. The cell undergoes rapid elongation with approximately constant radius. Growth is driven by high internal turgor pressure causing viscous stretching of the cell wall, with embedded cellulose microfibrils providing the wall with strongly anisotropic properties. We represent the cell as a thin cylindrical fiber-reinforced viscous sheet between rigid end plates. Asymptotic reduction of the governing equations, under simple sets of assumptions about fiber and wall properties, yields variants of the traditional Lockhart equation that relates the axial cell growth rate to the internal pressure. The model provides insights into the geometric and biomechanical parameters underlying bulk quantities such as wall extensibility and shows how either dynamical changes in wall material properties or passive fibre reorientation may suppress cell elongation.

Assembly and enlargement of the primary cell wall in plants

NASA Technical Reports Server (NTRS)

Cosgrove, D. J.

1997-01-01

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

Assembly and enlargement of the primary cell wall in plants.

PubMed

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.

Isolation of the Cell Wall.

PubMed

Canut, Hervé; Albenne, Cécile; Jamet, Elisabeth

2017-01-01

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

Water-polysaccharide interactions in the primary cell wall of Arabidopsis thaliana from polarization transfer solid-state NMR.

PubMed

White, Paul B; Wang, Tuo; Park, Yong Bum; Cosgrove, Daniel J; Hong, Mei

2014-07-23

Polysaccharide-rich plant cell walls are hydrated under functional conditions, but the molecular interactions between water and polysaccharides in the wall have not been investigated. In this work, we employ polarization transfer solid-state NMR techniques to study the hydration of primary-wall polysaccharides of the model plant, Arabidopsis thaliana. By transferring water (1)H polarization to polysaccharides through distance- and mobility-dependent (1)H-(1)H dipolar couplings and detecting it through polysaccharide (13)C signals, we obtain information about water proximity to cellulose, hemicellulose, and pectins as well as water mobility. Both intact and partially extracted cell wall samples are studied. Our results show that water-pectin polarization transfer is much faster than water-cellulose polarization transfer in all samples, but the extent of extraction has a profound impact on the water-polysaccharide spin diffusion. Removal of calcium ions and the consequent extraction of homogalacturonan (HG) significantly slowed down spin diffusion, while further extraction of matrix polysaccharides restored the spin diffusion rate. These trends are observed in cell walls with similar water content, thus they reflect inherent differences in the mobility and spatial distribution of water. Combined with quantitative analysis of the polysaccharide contents, our results indicate that calcium ions and HG gelation increase the amount of bound water, which facilitates spin diffusion, while calcium removal disrupts the gel and gives rise to highly dynamic water, which slows down spin diffusion. The recovery of spin diffusion rates after more extensive extraction is attributed to increased water-exposed surface areas of the polysaccharides. Water-pectin spin diffusion precedes water-cellulose spin diffusion, lending support to the single-network model of plant primary walls in which a substantial fraction of the cellulose surface is surrounded by pectins.

Modulation of the degree and pattern of methyl-esterification of pectic homogalacturonan in plant cell walls. Implications for pectin methyl esterase action, matrix properties, and cell adhesion.

PubMed

Willats, W G; Orfila, C; Limberg, G; Buchholt, H C; van Alebeek, G J; Voragen, A G; Marcus, S E; Christensen, T M; Mikkelsen, J D; Murray, B S; Knox, J P

2001-06-01

Homogalacturonan (HG) is a multifunctional pectic polysaccharide of the primary cell wall matrix of all land plants. HG is thought to be deposited in cell walls in a highly methyl-esterified form but can be subsequently de-esterified by wall-based pectin methyl esterases (PMEs) that have the capacity to remove methyl ester groups from HG. Plant PMEs typically occur in multigene families/isoforms, but the precise details of the functions of PMEs are far from clear. Most are thought to act in a processive or blockwise fashion resulting in domains of contiguous de-esterified galacturonic acid residues. Such de-esterified blocks of HG can be cross-linked by calcium resulting in gel formation and can contribute to intercellular adhesion. We demonstrate that, in addition to blockwise de-esterification, HG with a non-blockwise distribution of methyl esters is also an abundant feature of HG in primary plant cell walls. A partially methyl-esterified epitope of HG that is generated in greatest abundance by non-blockwise de-esterification is spatially regulated within the cell wall matrix and occurs at points of cell separation at intercellular spaces in parenchymatous tissues of pea and other angiosperms. Analysis of the properties of calcium-mediated gels formed from pectins containing HG domains with differing degrees and patterns of methyl-esterification indicated that HG with a non-blockwise pattern of methyl ester group distribution is likely to contribute distinct mechanical and porosity properties to the cell wall matrix. These findings have important implications for our understanding of both the action of pectin methyl esterases on matrix properties and mechanisms of intercellular adhesion and its loss in plants.

Imaging Cell Wall Architecture in Single Zinnia elegans Tracheary Elements1[OA

PubMed Central

Lacayo, Catherine I.; Malkin, Alexander J.; Holman, Hoi-Ying N.; Chen, Liang; Ding, Shi-You; Hwang, Mona S.; Thelen, Michael P.

2010-01-01

The chemical and structural organization of the plant cell wall was examined in Zinnia elegans tracheary elements (TEs), which specialize by developing prominent secondary wall thickenings underlying the primary wall during xylogenesis in vitro. Three imaging platforms were used in conjunction with chemical extraction of wall components to investigate the composition and structure of single Zinnia TEs. Using fluorescence microscopy with a green fluorescent protein-tagged Clostridium thermocellum family 3 carbohydrate-binding module specific for crystalline cellulose, we found that cellulose accessibility and binding in TEs increased significantly following an acidified chlorite treatment. Examination of chemical composition by synchrotron radiation-based Fourier-transform infrared spectromicroscopy indicated a loss of lignin and a modest loss of other polysaccharides in treated TEs. Atomic force microscopy was used to extensively characterize the topography of cell wall surfaces in TEs, revealing an outer granular matrix covering the underlying meshwork of cellulose fibrils. The internal organization of TEs was determined using secondary wall fragments generated by sonication. Atomic force microscopy revealed that the resulting rings, spirals, and reticulate structures were composed of fibrils arranged in parallel. Based on these combined results, we generated an architectural model of Zinnia TEs composed of three layers: an outermost granular layer, a middle primary wall composed of a meshwork of cellulose fibrils, and inner secondary wall thickenings containing parallel cellulose fibrils. In addition to insights in plant biology, studies using Zinnia TEs could prove especially productive in assessing cell wall responses to enzymatic and microbial degradation, thus aiding current efforts in lignocellulosic biofuel production. PMID:20592039

Xylose-rich polysaccharides from the primary walls of embryogenic cell line of Pinus caribaea.

PubMed

Mollard, A; Domon, J M; David, H; Joseleau, J P

1997-08-01

Embryogenic cell lines of Pinus caribaea were isolated from somatic embryogenesis from zygotic embryos. Previous studies showed that the proteins and glycoproteins were characteristic of the embryogenic state. In the present work we were seeking typical feature in the polysaccharide from the cell walls of embryogenic calli at nine days of culture. Sequential extraction with water, ammonium oxalate, dimethyl sulfoxide, sodium borohydride and 4.3 M potassium hydroxide revealed that the extracted polysaccharides contained high proportions of arabinose and significant amounts of xylose. Fractionation of the hydrosoluble polymers on DEAE cellulose afforded a xylose-rich fraction (80% xylose, 24% glucose and lower properties of fucose and mannose). Methylation analysis and 13C-NMR spectra showed that the glycan backbone consisted of beta 1 --> 4 linked xylosyl residues Similar study of the fractions extracted respectively with DMSO and 4.3 M KOH showed the presence of polydisperse glycoxylans but excluded the presence of xyloglucan in significant amount. This could be a characteristic feature of embryogenic cells walls of Pinus caribaea or could be typical of cells grown as calluses. In the various fractions obtained from DEAE cellulose chromatography of the alkaline extract the infrequent occurrence of fucoxylans beside an arabinogalactan showed again the unusual nature of the cell wall polymers of this embryogenic lines, which seems to differ greatly from those found in the primary wall of cells from suspension cultures.

The Acid Growth Theory of auxin-induced cell elongation is alive and well

NASA Technical Reports Server (NTRS)

Rayle, D. L.; Cleland, R. E.

1992-01-01

Plant cells elongate irreversibly only when load-bearing bonds in the walls are cleaved. Auxin causes the elongation of stem and coleoptile cells by promoting wall loosening via cleavage of these bonds. This process may be coupled with the intercalation of new cell wall polymers. Because the primary site of auxin action appears to be the plasma membrane or some intracellular site, and wall loosening is extracellular, there must be communication between the protoplast and the wall. Some "wall-loosening factor" must be exported from auxin-impacted cells, which sets into motion the wall loosening events. About 20 years ago, it was suggested that the wall-loosening factor is hydrogen ions. This idea and subsequent supporting data gave rise to the Acid Growth Theory, which states that when exposed to auxin, susceptible cells excrete protons into the wall (apoplast) at an enhanced rate, resulting in a decrease in apoplastic pH. The lowered wall pH then activates wall-loosening processes, the precise nature of which is unknown. Because exogenous acid causes a transient (1-4 h) increase in growth rate, auxin must also mediate events in addition to wall acidification for growth to continue for an extended period of time. These events may include osmoregulation, cell wall synthesis, and maintenance of the capacity of walls to undergo acid-induced wall loosening. At present, we do not know if these phenomena are tightly coupled to wall acidification or if they are the products of multiple independent signal transduction pathways.

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

PubMed Central

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

2008-01-01

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

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

PubMed

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.

Pectic homogalacturonan masks abundant sets of xyloglucan epitopes in plant cell walls.

PubMed

Marcus, Susan E; Verhertbruggen, Yves; Hervé, Cécile; Ordaz-Ortiz, José J; Farkas, Vladimir; Pedersen, Henriette L; Willats, William G T; Knox, J Paul

2008-05-22

Molecular probes are required to detect cell wall polymers in-situ to aid understanding of their cell biology and several studies have shown that cell wall epitopes have restricted occurrences across sections of plant organs indicating that cell wall structure is highly developmentally regulated. Xyloglucan is the major hemicellulose or cross-linking glycan of the primary cell walls of dicotyledons although little is known of its occurrence or functions in relation to cell development and cell wall microstructure. Using a neoglycoprotein approach, in which a XXXG heptasaccharide of tamarind seed xyloglucan was coupled to BSA to produce an immunogen, we have generated a rat monoclonal antibody (designated LM15) to the XXXG structural motif of xyloglucans. The specificity of LM15 has been confirmed by the analysis of LM15 binding using glycan microarrays and oligosaccharide hapten inhibition of binding studies. The use of LM15 for the analysis of xyloglucan in the cell walls of tamarind and nasturtium seeds, in which xyloglucan occurs as a storage polysaccharide, indicated that the LM15 xyloglucan epitope occurs throughout the thickened cell walls of the tamarind seed and in the outer regions, adjacent to middle lamellae, of the thickened cell walls of the nasturtium seed. Immunofluorescence analysis of LM15 binding to sections of tobacco and pea stem internodes indicated that the xyloglucan epitope was restricted to a few cell types in these organs. Enzymatic removal of pectic homogalacturonan from equivalent sections resulted in the abundant detection of distinct patterns of the LM15 xyloglucan epitope across these organs and a diversity of occurrences in relation to the cell wall microstructure of a range of cell types. These observations support ideas that xyloglucan is associated with pectin in plant cell walls. They also indicate that documented patterns of cell wall epitopes in relation to cell development and cell differentiation may need to be re-considered in relation to the potential masking of cell wall epitopes by other cell wall components.

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

PubMed

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

2016-02-01

Barley (Hordeum vulgare L.) seed germination initiates many important biological processes such as DNA, membrane and mitochondrial repairs. However, little is known on cell wall modifications in germinating embryos. We have investigated cell wall polysaccharide composition change, gene transcription and alternative splicing events in four barley varieties at 24h and 48 h germination. Cell wall components in germinating barley embryos changed rapidly, with increases in cellulose and (1,3)(1,4)-β-D-glucan (20-100%) within 24h, but decreases in heteroxylan and arabinan (3-50%). There were also significant changes in the levels of type I arabinogalactans and heteromannans. Alternative splicing played very important roles in cell wall modifications. At least 22 cell wall transcripts were detected to undergo either alternative 3' splicing, alternative 5' splicing or intron retention type of alternative splicing. These genes coded enzymes catalyzing synthesis and degradation of cellulose, heteroxylan, (1,3)(1,4)-β-D-glucan and other cell wall polymers. Furthermore, transcriptional regulation also played very important roles in cell wall modifications. Transcript levels of primary wall cellulase synthase, heteroxylan synthesizing and nucleotide sugar inter-conversion genes were very high in germinating embryos. At least 50 cell wall genes changed transcript levels significantly. Expression patterns of many cell wall genes coincided with changes in polysaccharide composition. Our data showed that cell wall polysaccharide metabolism was very active in germinating barley embryos, which was regulated at both transcriptional and post-transcriptional levels. Copyright © 2015 Elsevier GmbH. All rights reserved.

Bioinspired Layer-by-Layer Microcapsules Based on Cellulose Nanofibers with Switchable Permeability.

PubMed

Paulraj, Thomas; Riazanova, Anastasia V; Yao, Kun; Andersson, Richard L; Müllertz, Anette; Svagan, Anna J

2017-04-10

Green, all-polysaccharide based microcapsules with mechanically robust capsule walls and fast, stimuli-triggered, and switchable permeability behavior show great promise in applications based on selective and timed permeability. Taking a cue from nature, the build-up and composition of plant primary cell walls inspired the capsule wall assembly, because the primary cell walls in plants exhibit high mechanical properties despite being in a highly hydrated state, primarily owing to cellulose microfibrils. The microcapsules (16 ± 4 μm in diameter) were fabricated using the layer-by-layer technique on sacrificial CaCO 3 templates, using plant polysaccharides (pectin, cellulose nanofibers, and xyloglucan) only. In water, the capsule wall was permeable to labeled dextrans with a hydrodynamic diameter of ∼6.6 nm. Upon exposure to NaCl, the porosity of the capsule wall quickly changed allowing larger molecules (∼12 nm) to permeate. However, the porosity could be restored to its original state by removal of NaCl, by which permeants became trapped inside the capsule's core. The high integrity of cell wall was due to the CNF and the ON/OFF alteration of the permeability properties, and subsequent loading/unloading of molecules, could be repeated several times with the same capsule demonstrating a robust microcontainer with controllable permeability properties.

Nanoscale movements of cellulose microfibrils in primary cell walls.

PubMed

Zhang, Tian; Vavylonis, Dimitrios; Durachko, Daniel M; Cosgrove, Daniel J

2017-04-28

The growing plant cell wall is commonly considered to be a fibre-reinforced structure whose strength, extensibility and anisotropy depend on the orientation of crystalline cellulose microfibrils, their bonding to the polysaccharide matrix and matrix viscoelasticity 1-4 . Structural reinforcement of the wall by stiff cellulose microfibrils is central to contemporary models of plant growth, mechanics and meristem dynamics 4-12 . Although passive microfibril reorientation during wall extension has been inferred from theory and from bulk measurements 13-15 , nanometre-scale movements of individual microfibrils have not been directly observed. Here we combined nanometre-scale imaging of wet cell walls by atomic force microscopy (AFM) with a stretching device and endoglucanase treatment that induces wall stress relaxation and creep, mimicking wall behaviours during cell growth. Microfibril movements during forced mechanical extensions differ from those during creep of the enzymatically loosened wall. In addition to passive angular reorientation, we observed a diverse repertoire of microfibril movements that reveal the spatial scale of molecular connections between microfibrils. Our results show that wall loosening alters microfibril connectivity, enabling microfibril dynamics not seen during mechanical stretch. These insights into microfibril movements and connectivities need to be incorporated into refined models of plant cell wall structure, growth and morphogenesis.

Cotton fiber tips have diverse morphologies and show evidence of apical cell wall synthesis

PubMed Central

Stiff , Michael R.; Haigler, Candace H.

2016-01-01

Cotton fibers arise through highly anisotropic expansion of a single seed epidermal cell. We obtained evidence that apical cell wall synthesis occurs through examining the tips of young elongating Gossypium hirsutum (Gh) and G. barbadense (Gb) fibers. We characterized two tip types in Gh fiber (hemisphere and tapered), each with distinct apical diameter, central vacuole location, and distribution of cell wall components. The apex of Gh hemisphere tips was enriched in homogalacturonan epitopes, including a relatively high methyl-esterified form associated with cell wall pliability. Other wall components increased behind the apex including cellulose and the α-Fuc-(1,2)-β-Gal epitope predominantly found in xyloglucan. Gb fibers had only one narrow tip type featuring characters found in each Gh tip type. Pulse-labeling of cell wall glucans indicated wall synthesis at the apex of both Gh tip types and in distal zones. Living Gh hemisphere and Gb tips ruptured preferentially at the apex upon treatment with wall degrading enzymes, consistent with newly synthesized wall at the apex. Gh tapered tips ruptured either at the apex or distantly. Overall, the results reveal diverse cotton fiber tip morphologies and support primary wall synthesis occurring at the apex and discrete distal regions of the tip. PMID:27301434

The Structure of Plant Cell Walls

PubMed Central

Wilder, Barry M.; Albersheim, Peter

1973-01-01

The molecular structure and chemical properties of the hemicellulose present in the isolated cell walls of suspension cultures of sycamore (Acer pseudoplatanus) cells has recently been described by Bauer et al. (Plant Physiol. 51: 174-187). The hemicellulose of the sycamore primary cell wall is a xyloglucan. This polymer functions as an important cross-link in the structure of the cell wall; the xyloglucan is hydrogen-bonded to cellulose and covalently attached to the pectic polymers. The present paper describes the structure of a xyloglucan present in the walls and in the extracellular medium of suspension-cultured Red Kidney bean (Phaseolus vulgaris) cells and compares the structure of the bean xyloglucan with the structure of the sycamore xyloglucan. Although some minor differences were found, the basic structure of the xyloglucans in the cell walls of these distantly related species is the same. The structure is based on a repeating heptasaccharide unit which consists of four residues of β-1, 4-linked glucose and three residues of terminal xylose linked to the 6 position of three of the glucosyl residues. PMID:16658434

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 eachmore » 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 synthesis pathway genes are induced by removal of cell wall, some cell wall synthesis apparatus must be shared in both cases. The cell wall re-synthesis mechanism may have broad application because our preliminary assay indicates that the cell wall characteristics are highly different from those produced during cytokinesis. A thorough understanding on the regulation of cell wall re-synthesis may lead to improvement of cell wall characteristics. b) Removal of cell wall results in chromatin decondensation Another interesting observation was that removal of cell wall was associated with substantial chromatin change. Our DNA DAPI stain, chromatin MNase digestion, histone modification proteomics, protein differential expression analysis, and DNA oligo array studies all supported that substantial chromatin change was associated with removal of cell wall treatment. It is still under investigation if the chromatin change is associated with activation of cell wall synthesis genes, in which chromatin remodeling is required. Another possibility is that the cell wall is required for stabilizing the chromatin structure in plant cells. Given that spindle fiber is directly connected with both chromatin structure and cell wall synthesis, it is possible that there is an intrinsic connection between cell wall and chromatin.« less

Cotton fiber cell walls of Gossypium hirsutum and Gossypium barbadense have differences related to loosely-bound xyloglucan.

PubMed

Avci, Utku; Pattathil, Sivakumar; Singh, Bir; Brown, Virginia L; Hahn, Michael G; Haigler, Candace H

2013-01-01

Cotton fiber is an important natural textile fiber due to its exceptional length and thickness. These properties arise largely through primary and secondary cell wall synthesis. The cotton fiber of commerce is a cellulosic secondary wall surrounded by a thin cuticulated primary wall, but there were only sparse details available about the polysaccharides in the fiber cell wall of any cotton species. In addition, Gossypium hirsutum (Gh) fiber was known to have an adhesive cotton fiber middle lamella (CFML) that joins adjacent fibers into tissue-like bundles, but it was unknown whether a CFML existed in other commercially important cotton fibers. We compared the cell wall chemistry over the time course of fiber development in Gh and Gossypium barbadense (Gb), the two most important commercial cotton species, when plants were grown in parallel in a highly controlled greenhouse. Under these growing conditions, the rate of early fiber elongation and the time of onset of secondary wall deposition were similar in fibers of the two species, but as expected the Gb fiber had a prolonged elongation period and developed higher quality compared to Gh fiber. The Gb fibers had a CFML, but it was not directly required for fiber elongation because Gb fiber continued to elongate rapidly after CFML hydrolysis. For both species, fiber at seven ages was extracted with four increasingly strong solvents, followed by analysis of cell wall matrix polysaccharide epitopes using antibody-based Glycome Profiling. Together with immunohistochemistry of fiber cross-sections, the data show that the CFML of Gb fiber contained lower levels of xyloglucan compared to Gh fiber. Xyloglucan endo-hydrolase activity was also higher in Gb fiber. In general, the data provide a rich picture of the similarities and differences in the cell wall structure of the two most important commercial cotton species.

Casparian bands occur in the periderm of Pelargonium hortorum stem and root.

PubMed

Meyer, Chris J; Peterson, Carol A

2011-04-01

Casparian bands are characteristic of the endodermis and exodermis of roots, but also occur infrequently in other plant organs, for example stems and leaves. To date, these structures have not been detected in phellem cells of a periderm. The aim of this study was to determine whether Casparian bands occur in phellem cells using tests that are known to detect Casparian bands in cells that also contain suberin lamellae. Both natural periderm and wound-induced structures were examined in shoots and roots. Using Pelargonium hortorum as a candidate species, the following tests were conducted: (1) staining with berberine and counterstaining with aniline blue, (2) mounting sections in concentrated sulphuric acid and (3) investigating the permeability of the walls with berberine as an apoplastic, fluorescent tracer. (1) Berberine-aniline blue staining revealed a modification in the radial and transverse walls of mature phellem cells in both stems and roots. Three days after wounding through to the cortex of stems, the boundary zone cells (pre-existing, living cells nearest the wound) had developed vividly stained primary walls. By 17 d, staining of mature phellem cells of wound-induced periderm was similar to that of natural periderm. (2) Mature native phellem cells of stems resisted acid digestion. (3) Berberine was excluded from the anticlinal (radial and transverse) walls of mature phellem cells in stems and roots, and from the wound-induced boundary zone. Casparian bands are present in mature phellem cells in both stems and roots of P. hortorum. It is proposed that Casparian bands act to retard water loss and pathogen entry through the primary cell walls of the phellem cells, thus contributing to the main functions of the periderm.

Quantitative trait loci for cell wall composition traits measured using near-infrared spectroscopy in the model C4 perennial grass Panicum hallii

DOE PAGES

Milano, Elizabeth R.; Payne, Courtney E.; Wolfrum, Edward J.; ...

2018-02-03

Biofuels derived from lignocellulosic plant material are an important component of current renewable energy strategies. Improvement efforts in biofuel feedstock crops have been primarily focused on increasing biomass yield with less consideration for tissue quality or composition. Four primary components found in the plant cell wall contribute to the overall quality of plant tissue and conversion characteristics, cellulose and hemicellulose polysaccharides are the primary targets for fuel conversion, while lignin and ash provide structure and defense. We explore the genetic architecture of tissue characteristics using a quantitative trait loci (QTL) mapping approach in Panicum hallii, a model lignocellulosic grass system.more » Diversity in the mapping population was generated by crossing xeric and mesic varietals, comparative to northern upland and southern lowland ecotypes in switchgrass. We use near-infrared spectroscopy with a primary analytical method to create a P. hallii specific calibration model to quickly quantify cell wall components. Ash, lignin, glucan, and xylan comprise 68% of total dry biomass in P. hallii: comparable to other feedstocks. We identified 14 QTL and one epistatic interaction across these four cell wall traits and found almost half of the QTL to localize to a single linkage group. Panicum hallii serves as the genomic model for its close relative and emerging biofuel crop, switchgrass (P. virgatum). We used high throughput phenotyping to map genomic regions that impact natural variation in leaf tissue composition. Understanding the genetic architecture of tissue traits in a tractable model grass system will lead to a better understanding of cell wall structure as well as provide genomic resources for bioenergy crop breeding programs.« less

Quantitative trait loci for cell wall composition traits measured using near-infrared spectroscopy in the model C4 perennial grass Panicum hallii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milano, Elizabeth R.; Payne, Courtney E.; Wolfrum, Edward J.

Biofuels derived from lignocellulosic plant material are an important component of current renewable energy strategies. Improvement efforts in biofuel feedstock crops have been primarily focused on increasing biomass yield with less consideration for tissue quality or composition. Four primary components found in the plant cell wall contribute to the overall quality of plant tissue and conversion characteristics, cellulose and hemicellulose polysaccharides are the primary targets for fuel conversion, while lignin and ash provide structure and defense. We explore the genetic architecture of tissue characteristics using a quantitative trait loci (QTL) mapping approach in Panicum hallii, a model lignocellulosic grass system.more » Diversity in the mapping population was generated by crossing xeric and mesic varietals, comparative to northern upland and southern lowland ecotypes in switchgrass. We use near-infrared spectroscopy with a primary analytical method to create a P. hallii specific calibration model to quickly quantify cell wall components. Ash, lignin, glucan, and xylan comprise 68% of total dry biomass in P. hallii: comparable to other feedstocks. We identified 14 QTL and one epistatic interaction across these four cell wall traits and found almost half of the QTL to localize to a single linkage group. Panicum hallii serves as the genomic model for its close relative and emerging biofuel crop, switchgrass (P. virgatum). We used high throughput phenotyping to map genomic regions that impact natural variation in leaf tissue composition. Understanding the genetic architecture of tissue traits in a tractable model grass system will lead to a better understanding of cell wall structure as well as provide genomic resources for bioenergy crop breeding programs.« less

Primary Metabolism during Biosynthesis of Secondary Wall Polymers of Protoxylem Vessel Elements1[OPEN

PubMed Central

Morisaki, Keiko; Sawada, Yuji; Sano, Ryosuke; Yamamoto, Atsushi; Kurata, Tetsuya; Suzuki, Shiro; Matsuda, Mami; Hasunuma, Tomohisa; Hirai, Masami Yokota

2016-01-01

Xylem vessels, the water-conducting cells in vascular plants, undergo characteristic secondary wall deposition and programmed cell death. These processes are regulated by the VASCULAR-RELATED NAC-DOMAIN (VND) transcription factors. Here, to identify changes in metabolism that occur during protoxylem vessel element differentiation, we subjected tobacco (Nicotiana tabacum) BY-2 suspension culture cells carrying an inducible VND7 system to liquid chromatography-mass spectrometry-based wide-target metabolome analysis and transcriptome analysis. Time-course data for 128 metabolites showed dynamic changes in metabolites related to amino acid biosynthesis. The concentration of glyceraldehyde 3-phosphate, an important intermediate of the glycolysis pathway, immediately decreased in the initial stages of cell differentiation. As cell differentiation progressed, specific amino acids accumulated, including the shikimate-related amino acids and the translocatable nitrogen-rich amino acid arginine. Transcriptome data indicated that cell differentiation involved the active up-regulation of genes encoding the enzymes catalyzing fructose 6-phosphate biosynthesis from glyceraldehyde 3-phosphate, phosphoenolpyruvate biosynthesis from oxaloacetate, and phenylalanine biosynthesis, which includes shikimate pathway enzymes. Concomitantly, active changes in the amount of fructose 6-phosphate and phosphoenolpyruvate were detected during cell differentiation. Taken together, our results show that protoxylem vessel element differentiation is associated with changes in primary metabolism, which could facilitate the production of polysaccharides and lignin monomers and, thus, promote the formation of the secondary cell wall. Also, these metabolic shifts correlate with the active transcriptional regulation of specific enzyme genes. Therefore, our observations indicate that primary metabolism is actively regulated during protoxylem vessel element differentiation to alter the cell’s metabolic activity for the biosynthesis of secondary wall polymers. PMID:27600813

Anatomical structure overrides temperature controls on magnesium uptake - calcification in the Arctic/subarctic coralline algae Leptophytum laeve and Kvaleya epilaeve (Rhodophyta; Corallinales)

NASA Astrophysics Data System (ADS)

Nash, Merinda C.; Adey, Walter

2018-02-01

Calcified coralline red algae are ecologically key organisms in photic benthic environments. In recent decades they have become important climate proxies, especially in the Arctic and subarctic. It has been widely accepted that magnesium content in coralline tissues is directly a function of ambient temperature, and this is a primary basis for their value as a climate archive. In this paper we show for two genera of Arctic/subarctic corallines, Leptophytum laeve and Kvaleya epilaeve, that previously unrecognised complex tissue and cell wall anatomy bears a variety of basal signatures for Mg content, with the accepted temperature relationship being secondary. The interfilament carbonate has lower Mg than adjacent cell walls and the hypothallial cell walls have the highest Mg content. The internal structure of the hypothallial cell walls can differ substantially from the perithallial radial cell wall structure. Using high-magnification scanning electron microscopy and etching we expose the nanometre-scale structures within the cell walls and interfilament. Fibrils concentrate at the internal and external edges of the cell walls. Fibrils ˜ 10 nm thick appear to thread through the radial Mg-calcite grains and form concentric bands within the cell wall. This banding may control Mg distribution within the cell. Similar fibril banding is present in the hypothallial cell walls but not the interfilament. Climate archiving with corallines can achieve greater precision with recognition of these parameters.

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

PubMed Central

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

2012-01-01

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

Organization of pectic arabinan and galactan side chains in association with cellulose microfibrils in primary cell walls and related models envisaged.

PubMed

Zykwinska, Agata; Thibault, Jean-François; Ralet, Marie-Christine

2007-01-01

The structure of arabinan and galactan domains in association with cellulose microfibrils was investigated using enzymatic and alkali degradation procedures. Sugar beet and potato cell wall residues (called 'natural' composites), rich in pectic neutral sugar side chains and cellulose, as well as 'artificial' composites, created by in vitro adsorption of arabinan and galactan side chains onto primary cell wall cellulose, were studied. These composites were sequentially treated with enzymes specific for pectic side chains and hot alkali. The degradation approach used showed that most of the arabinan and galactan side chains are in strong interaction with cellulose and are not hydrolysed by pectic side chain-degrading enzymes. It seems unlikely that isolated arabinan and galactan chains are able to tether adjacent microfibrils. However, cellulose microfibrils may be tethered by different pectic side chains belonging to the same pectic macromolecule.

Restricted cell elongation in Arabidopsis hypocotyls is associated with a reduced average pectin esterification level

PubMed Central

Derbyshire, Paul; McCann, Maureen C; Roberts, Keith

2007-01-01

Background Cell elongation is mainly limited by the extensibility of the cell wall. Dicotyledonous primary (growing) cell walls contain cellulose, xyloglucan, pectin and proteins, but little is known about how each polymer class contributes to the cell wall mechanical properties that control extensibility. Results We present evidence that the degree of pectin methyl-esterification (DE%) limits cell growth, and that a minimum level of about 60% DE is required for normal cell elongation in Arabidopsis hypocotyls. When the average DE% falls below this level, as in two gibberellic acid (GA) mutants ga1-3 and gai, and plants expressing pectin methyl-esterase (PME1) from Aspergillus aculeatus, then hypocotyl elongation is reduced. Conclusion Low average levels of pectin DE% are associated with reduced cell elongation, implicating PMEs, the enzymes that regulate DE%, in the cell elongation process and in responses to GA. At high average DE% other components of the cell wall limit GA-induced growth. PMID:17572910

Restricted cell elongation in Arabidopsis hypocotyls is associated with a reduced average pectin esterification level.

PubMed

Derbyshire, Paul; McCann, Maureen C; Roberts, Keith

2007-06-17

Cell elongation is mainly limited by the extensibility of the cell wall. Dicotyledonous primary (growing) cell walls contain cellulose, xyloglucan, pectin and proteins, but little is known about how each polymer class contributes to the cell wall mechanical properties that control extensibility. We present evidence that the degree of pectin methyl-esterification (DE%) limits cell growth, and that a minimum level of about 60% DE is required for normal cell elongation in Arabidopsis hypocotyls. When the average DE% falls below this level, as in two gibberellic acid (GA) mutants ga1-3 and gai, and plants expressing pectin methyl-esterase (PME1) from Aspergillus aculeatus, then hypocotyl elongation is reduced. Low average levels of pectin DE% are associated with reduced cell elongation, implicating PMEs, the enzymes that regulate DE%, in the cell elongation process and in responses to GA. At high average DE% other components of the cell wall limit GA-induced growth.

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

PubMed

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.

Cold stability of microtubules in wood-forming tissues of conifers during seasons of active and dormant cambium.

PubMed

Begum, Shahanara; Shibagaki, Masaki; Furusawa, Osamu; Nakaba, Satoshi; Yamagishi, Yusuke; Yoshimoto, Joto; Jin, Hyun-O; Sano, Yuzou; Funada, Ryo

2012-01-01

The cold stability of microtubules during seasons of active and dormant cambium was analyzed in the conifers Abies firma, Abies sachalinensis and Larix leptolepis by immunofluorescence microscopy. Samples were fixed at room temperature and at a low temperature of 2-3°C to examine the effects of low temperature on the stability of microtubules. Microtubules were visible in cambium, xylem cells and phloem cells after fixation at room temperature during seasons of active and dormant cambium. By contrast, fixation at low temperature depolymerized microtubules in cambial cells, differentiating tracheids, differentiating xylem ray parenchyma and phloem ray parenchyma cells during the active season. However, similar fixation did not depolymerize microtubules during cambial dormancy in winter. Our results indicate that the stability of microtubules in cambial cells and cambial derivatives at low temperature differs between seasons of active and dormant cambium. Moreover, the change in the stability of microtubules that we observed at low temperature might be closely related to seasonal changes in the cold tolerance of conifers. In addition, low-temperature fixation depolymerized microtubules in cambial cells and differentiating cells that had thin primary cell walls, while such low-temperature fixation did not depolymerize microtubules in differentiating secondary xylem ray parenchyma cells and tracheids that had thick secondary cell walls. The stability of microtubules at low temperature appears to depend on the structure of the cell wall, namely, primary or secondary. Therefore, we propose that the secondary cell wall might be responsible for the cold stability of microtubules in differentiating secondary xylem cells of conifers.

Pectin: cell biology and prospects for functional analysis.

PubMed

Willats, W G; McCartney, L; Mackie, W; Knox, J P

2001-09-01

Pectin is a major component of primary cell walls of all land plants and encompasses a range of galacturonic acid-rich polysaccharides. Three major pectic polysaccharides (homogalacturonan, rhamnogalacturonan-I and rhamnogalacturonan-II) are thought to occur in all primary cell walls. This review surveys what is known about the structure and function of these pectin domains. The high degree of structural complexity and heterogeneity of the pectic matrix is produced both during biosynthesis in the endomembrane system and as a result of the action of an array of wall-based pectin-modifying enzymes. Recent developments in analytical techniques and in the generation of anti-pectin probes have begun to place the structural complexity of pectin in cell biological and developmental contexts. The in muro de-methyl-esterification of homogalacturonan by pectin methyl esterases is emerging as a key process for the local modulation of matrix properties. Rhamnogalacturonan-I comprises a highly diverse population of spatially and developmentally regulated polymers, whereas rhamnogalacturonan-II appears to be a highly conserved and stable pectic domain. Current knowledge of biosynthetic enzymes, plant and microbial pectinases and the interactions of pectin with other cell wall components and the impact of molecular genetic approaches are reviewed in terms of the functional analysis of pectic polysaccharides in plant growth and development.

Size, Shape, and Arrangement of Cellulose Microfibril in Higher Plant Cell Walls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, S. Y.

2013-01-01

Plant cell walls from maize (Zea mays L.) are imaged using atomic force microscopy (AFM) at the sub-nanometer resolution. We found that the size and shape of fundamental cellulose elementary fibril (CEF) is essentially identical in different cell wall types, i.e., primary wall (PW), parenchyma secondary wall (pSW), and sclerenchyma secondary wall (sSW), which is consistent with previously proposed 36-chain model (Ding et al., 2006, J. Agric. Food Chem.). The arrangement of individual CEFs in these wall types exhibits two orientations. In PW, CEFs are horizontally associated through their hydrophilic faces, and the planar faces are exposed, forming ribbon-like macrofibrils.more » In pSW and sSW, CEFs are vertically oriented, forming layers, in which hemicelluloses are interacted with the hydrophobic faces of the CEF and serve as spacers between CEFs. Lignification occurs between CEF-hemicelluloses layers in secondary walls. Furthermore, we demonstrated quantitative analysis of plant cell wall accessibility to and digestibility by different cellulase systems at real-time using chemical imaging (e.g., stimulated Raman scattering) and fluorescence microscopy of labeled cellulases (Ding et al., 2012, Science, in press).« less

Immunomodulatory properties of carbon nanotubes are able to compensate immune function dysregulation caused by microgravity conditions

NASA Astrophysics Data System (ADS)

Crescio, Claudia; Orecchioni, Marco; Ménard-Moyon, Cécilia; Sgarrella, Francesco; Pippia, Proto; Manetti, Roberto; Bianco, Alberto; Delogu, Lucia Gemma

2014-07-01

Spaceflights lead to dysregulation of the immune cell functionality affecting the expression of activation markers and cytokine production. Short oxidized multi-walled carbon nanotubes functionalized by 1,3-dipolar cycloaddition have been reported to activate immune cells. In this Communication we have performed surface marker assays and multiplex ELISA on primary monocytes and T cells under microgravity. We have discovered that carbon nanotubes, through their immunostimulatory properties, are able to fight spaceflight immune system dysregulations.Spaceflights lead to dysregulation of the immune cell functionality affecting the expression of activation markers and cytokine production. Short oxidized multi-walled carbon nanotubes functionalized by 1,3-dipolar cycloaddition have been reported to activate immune cells. In this Communication we have performed surface marker assays and multiplex ELISA on primary monocytes and T cells under microgravity. We have discovered that carbon nanotubes, through their immunostimulatory properties, are able to fight spaceflight immune system dysregulations. Electronic supplementary information (ESI) available: Experimental section, structures of f-MWCNTs and uptake by human primary immune cells. See DOI: 10.1039/c4nr02711f

Abundance of mixed linkage glucan in mature tissues and secondary cell walls of grasses

PubMed Central

Vega-Sánchez, Miguel E.; Verhertbruggen, Yves; Scheller, Henrik V.; Ronald, Pamela C.

2013-01-01

(1,3; 1,4)-β-D-glucan, also known as mixed linkage glucan (MLG), is a polysaccharide that in flowering plants is unique to the cell walls of grasses and other related members of Poales. MLG is highly abundant in endosperm cell walls, where it is considered a storage carbohydrate. In vegetative tissues, MLG transiently accumulates in the primary cell walls of young, elongating organs. In evolutionary distant species such as Equisetum, MLG accumulates predominantly in old tissues in the stems. Similarly, we have recently shown that rice accumulates a large amount of MLG in mature stems, which prompted us to re-evaluate the hypothesis that MLG is solely related to growth in grass vegetative tissues. Here, we summarize data that confirms the presence of MLG in secondary cell walls and mature tissues in rice and other grasses. Along with these results, we discuss additional evidence indicating a broader role for MLG than previously considered. PMID:23299432

Extracellular cell wall β(1,3)glucan is required to couple septation to actomyosin ring contraction.

PubMed

Muñoz, Javier; Cortés, Juan Carlos G; Sipiczki, Matthias; Ramos, Mariona; Clemente-Ramos, José Angel; Moreno, M Belén; Martins, Ivone M; Pérez, Pilar; Ribas, Juan Carlos

2013-10-28

Cytokinesis has been extensively studied in different models, but the role of the extracellular cell wall is less understood. Here we studied this process in fission yeast. The essential protein Bgs4 synthesizes the main cell wall β(1,3)glucan. We show that Bgs4-derived β(1,3)glucan is required for correct and stable actomyosin ring positioning in the cell middle, before the start of septum formation and anchorage to the cell wall. Consequently, β(1,3)glucan loss generated ring sliding, oblique positioned rings and septa, misdirected septum synthesis indicative of relaxed rings, and uncoupling between a fast ring and membrane ingression and slow septum synthesis, suggesting that cytokinesis can progress with defective septum pushing and/or ring pulling forces. Moreover, Bgs4-derived β(1,3)glucan is essential for secondary septum formation and correct primary septum completion. Therefore, our results show that extracellular β(1,3)glucan is required for cytokinesis to connect the cell wall with the plasma membrane and for contractile ring function, as proposed for the equivalent extracellular matrix in animal cells.

Extracellular cell wall β(1,3)glucan is required to couple septation to actomyosin ring contraction

PubMed Central

Muñoz, Javier; Cortés, Juan Carlos G.; Sipiczki, Matthias; Ramos, Mariona; Clemente-Ramos, José Angel; Moreno, M. Belén; Martins, Ivone M.; Pérez, Pilar

2013-01-01

Cytokinesis has been extensively studied in different models, but the role of the extracellular cell wall is less understood. Here we studied this process in fission yeast. The essential protein Bgs4 synthesizes the main cell wall β(1,3)glucan. We show that Bgs4-derived β(1,3)glucan is required for correct and stable actomyosin ring positioning in the cell middle, before the start of septum formation and anchorage to the cell wall. Consequently, β(1,3)glucan loss generated ring sliding, oblique positioned rings and septa, misdirected septum synthesis indicative of relaxed rings, and uncoupling between a fast ring and membrane ingression and slow septum synthesis, suggesting that cytokinesis can progress with defective septum pushing and/or ring pulling forces. Moreover, Bgs4-derived β(1,3)glucan is essential for secondary septum formation and correct primary septum completion. Therefore, our results show that extracellular β(1,3)glucan is required for cytokinesis to connect the cell wall with the plasma membrane and for contractile ring function, as proposed for the equivalent extracellular matrix in animal cells. PMID:24165938

Two homologous genes, DCW1 (YKL046c) and DFG5, are essential for cell growth and encode glycosylphosphatidylinositol (GPI)-anchored membrane proteins required for cell wall biogenesis in Saccharomyces cerevisiae.

PubMed

Kitagaki, Hiroshi; Wu, Hong; Shimoi, Hitoshi; Ito, Kiyoshi

2002-11-01

The cell wall of Saccharomyces cerevisiae consists of glucan, chitin and various kinds of mannoproteins. Major parts of mannoproteins are synthesized as glycosylphosphatidylinositol (GPI)-anchored proteins and are then transferred to cell wall beta-1,6-glucan. A glycosyltransferase has been hypothesized to catalyse this transfer reaction. A database search revealed that the products of YKL046c and DFG5 are homologous to bacterial mannosidase. These genes are homologous to each other and have primary structures characteristic of GPI-anchored proteins. Although single disruptants of ykl046c and dfg5 were viable, ykl046cDelta was hypersensitive to a cell wall-digesting enzyme (zymolyase), suggesting that this gene is involved in cell wall biosynthesis. We therefore designated this gene as DCW1 (defective cell wall). A double disruptant of dcw1 and dfg5 was synthetically lethal, indicating that the functions of these gene products are redundant, and at least one of them is required for cell growth. Cells deficient in both Dcw1p and Dfg5p were round and large, had cell walls that contained an increased amount of chitin and secreted a major cell wall protein, Cwp1p, into the medium. Biochemical analyses showed that epitope-tagged Dcw1p is an N-glycosylated, GPI-anchored membrane protein and is localized in the membrane fraction including the cell surface. These results suggest that both Dcw1p and Dfg5p are GPI-anchored membrane proteins and are required for normal biosynthesis of the cell wall.

Understanding how the complex molecular architecture of mannan-degrading hydrolases contributes to plant cell wall degradation.

PubMed

Zhang, Xiaoyang; Rogowski, Artur; Zhao, Lei; Hahn, Michael G; Avci, Utku; Knox, J Paul; Gilbert, Harry J

2014-01-24

Microbial degradation of plant cell walls is a central component of the carbon cycle and is of increasing importance in environmentally significant industries. Plant cell wall-degrading enzymes have a complex molecular architecture consisting of catalytic modules and, frequently, multiple non-catalytic carbohydrate binding modules (CBMs). It is currently unclear whether the specificities of the CBMs or the topology of the catalytic modules are the primary drivers for the specificity of these enzymes against plant cell walls. Here, we have evaluated the relationship between CBM specificity and their capacity to enhance the activity of GH5 and GH26 mannanases and CE2 esterases against intact plant cell walls. The data show that cellulose and mannan binding CBMs have the greatest impact on the removal of mannan from tobacco and Physcomitrella cell walls, respectively. Although the action of the GH5 mannanase was independent of the context of mannan in tobacco cell walls, a significant proportion of the polysaccharide was inaccessible to the GH26 enzyme. The recalcitrant mannan, however, was fully accessible to the GH26 mannanase appended to a cellulose binding CBM. Although CE2 esterases display similar specificities against acetylated substrates in vitro, only CjCE2C was active against acetylated mannan in Physcomitrella. Appending a mannan binding CBM27 to CjCE2C potentiated its activity against Physcomitrella walls, whereas a xylan binding CBM reduced the capacity of esterases to deacetylate xylan in tobacco walls. This work provides insight into the biological significance for the complex array of hydrolytic enzymes expressed by plant cell wall-degrading microorganisms.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyerowitz, Elliot M.

2016-06-14

The overall goal of the revised scope of work for the final year of funding was to characterize cell wall biosynthesis in developing cotyledons and in the shoot apical meristem of Arabidopsis thaliana, as a way of learning about developmental control of cell wall biosynthesis in plants, and interactions between cell wall biosynthesis and the microtubule cytoskeleton. The proposed work had two parts – to look at the effect of mutation in the SPIRAL2 gene on microtubule organization and reorganization, and to thoroughly characterize the glycosyltransferase genes expressed in shoot apical meristems by RNA-seq experiments, by in situ hybridization ofmore » 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.« less

Morphology of the ampullae of Lorenzini in juvenile freshwater Carcharhinus leucas.

PubMed

Whitehead, Darryl L; Gauthier, Arnault R G; Mu, Erica W H; Bennett, Mike B; Tibbetts, Ian R

2015-05-01

Ampullae of Lorenzini were examined from juvenile Carcharhinus leucas (831-1,045 mm total length) captured from freshwater regions of the Brisbane River. The ampullary organ structure differs from all other previously described ampullae in the canal wall structure, the general shape of the ampullary canal, and the apically nucleated supportive cells. Ampullary pores of 140-205 µm in diameter are distributed over the surface of the head region with 2,681 and 2,913 pores present in two sharks that were studied in detail. The primary variation of the ampullary organs appears in the canal epithelial cells which occur as either flattened squamous epithelial cells or a second form of pseudostratified contour-ridged epithelial cells; both cell types appear to release material into the ampullary lumen. Secondarily, this ampullary canal varies due to involuted walls that form a clover-like canal wall structure. At the proximal end of the canal, contour-ridged cells abut a narrow region of cuboidal epithelial cells that verge on the constant, six alveolar sacs of the ampulla. The alveolar sacs contain numerous receptor and supportive cells bound by tight junctions and desmosomes. Pear-shaped receptor cells that possess a single apical kinocilium are connected basally by unmyelinated neural boutons. Opposed to previously described ampullae of Lorenzini, the supportive cells have an apical nucleus, possess a low number of microvilli, and form a unique, jagged alveolar wall. A centrally positioned centrum cap of cuboidal epithelial cells overlies a primary afferent lateral line nerve. © 2014 Wiley Periodicals, Inc.

Cytochemical localization of calcium in cap cells of primary roots of Zea mays L

NASA Technical Reports Server (NTRS)

Moore, R.

1985-01-01

The cellular distribution of Ca in caps of primary roots of Zea mays was examined during the onset and early stages of gravicurvature to determine its possible role in root gravitropism. Staining becomes associated with the portion of the cell wall adjacent to the distal end of the cell after five minutes, and persists throughout the onset of gravicurvature. The outermost peripheral cells of roots oriented horizontally and vertically secrete Ca through plasmodesmata-like channels in their cell walls. Data suggest that Ca is not transported laterally through the columella tissue,but rather that the movement of Ca to the lower side of caps of horizontally-oriented roots is at least partially through and/or on the mucilage of the cap, and via an electrochemical gradient. An important role in root gravitropism is indicated for Ca secretion by peripheral cells.

New techniques enable comparative analysis of microtubule orientation, wall texture, and growth rate in intact roots of Arabidopsis.

PubMed

Sugimoto, K; Williamson, R E; Wasteneys, G O

2000-12-01

This article explores root epidermal cell elongation and its dependence on two structural elements of cells, cortical microtubules and cellulose microfibrils. The recent identification of Arabidopsis morphology mutants with putative cell wall or cytoskeletal defects demands a procedure for examining and comparing wall architecture and microtubule organization patterns in this species. We developed methods to examine cellulose microfibrils by field emission scanning electron microscopy and microtubules by immunofluorescence in essentially intact roots. We were able to compare cellulose microfibril and microtubule alignment patterns at equivalent stages of cell expansion. Field emission scanning electron microscopy revealed that Arabidopsis root epidermal cells have typical dicot primary cell wall structure with prominent transverse cellulose microfibrils embedded in pectic substances. Our analysis showed that microtubules and microfibrils have similar orientation only during the initial phase of elongation growth. Microtubule patterns deviate from a predominantly transverse orientation while cells are still expanding, whereas cellulose microfibrils remain transverse until well after expansion finishes. We also observed microtubule-microfibril alignment discord before cells enter their elongation phase. This study and the new technology it presents provide a starting point for further investigations on the physical properties of cell walls and their mechanisms of assembly.

Patterning and lifetime of plasma membrane-localized cellulose synthase is dependent on actin organization in Arabidopsis interphase cells.

PubMed

Sampathkumar, Arun; Gutierrez, Ryan; McFarlane, Heather E; Bringmann, Martin; Lindeboom, Jelmer; Emons, Anne-Mie; Samuels, Lacey; Ketelaar, Tijs; Ehrhardt, David W; Persson, Staffan

2013-06-01

The actin and microtubule cytoskeletons regulate cell shape across phyla, from bacteria to metazoans. In organisms with cell walls, the wall acts as a primary constraint of shape, and generation of specific cell shape depends on cytoskeletal organization for wall deposition and/or cell expansion. In higher plants, cortical microtubules help to organize cell wall construction by positioning the delivery of cellulose synthase (CesA) complexes and guiding their trajectories to orient newly synthesized cellulose microfibrils. The actin cytoskeleton is required for normal distribution of CesAs to the plasma membrane, but more specific roles for actin in cell wall assembly and organization remain largely elusive. We show that the actin cytoskeleton functions to regulate the CesA delivery rate to, and lifetime of CesAs at, the plasma membrane, which affects cellulose production. Furthermore, quantitative image analyses revealed that actin organization affects CesA tracking behavior at the plasma membrane and that small CesA compartments were associated with the actin cytoskeleton. By contrast, localized insertion of CesAs adjacent to cortical microtubules was not affected by the actin organization. Hence, both actin and microtubule cytoskeletons play important roles in regulating CesA trafficking, cellulose deposition, and organization of cell wall biogenesis.

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

PubMed

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

2004-03-01

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

Overexpression of OsEXPA8, a Root-Specific Gene, Improves Rice Growth and Root System Architecture by Facilitating Cell Extension

PubMed Central

Ma, Nana; Wang, Ying; Qiu, Shichun; Kang, Zhenhui; Che, Shugang; Wang, Guixue; Huang, Junli

2013-01-01

Expansins are unique plant cell wall proteins that are involved in cell wall modifications underlying many plant developmental processes. In this work, we investigated the possible biological role of the root-specific α-expansin gene OsEXPA8 in rice growth and development by generating transgenic plants. Overexpression of OsEXPA8 in rice plants yielded pleiotropic phenotypes of improved root system architecture (longer primary roots, more lateral roots and root hairs), increased plant height, enhanced leaf number and enlarged leaf size. Further study indicated that the average cell length in both leaf and root vascular bundles was enhanced, and the cell growth in suspension cultures was increased, which revealed the cellular basis for OsEXPA8-mediated rice plant growth acceleration. Expansins are thought to be a key factor required for cell enlargement and wall loosening. Atomic force microscopy (AFM) technology revealed that average wall stiffness values for 35S::OsEXPA8 transgenic suspension-cultured cells decreased over six-fold compared to wild-type counterparts during different growth phases. Moreover, a prominent change in the wall polymer composition of suspension cells was observed, and Fourier-transform infrared (FTIR) spectra revealed a relative increase in the ratios of the polysaccharide/lignin content in cell wall compositions of OsEXPA8 overexpressors. These results support a role for expansins in cell expansion and plant growth. PMID:24124527

Mechanics of membrane bulging during cell-wall disruption in Gram-negative bacteria

NASA Astrophysics Data System (ADS)

Daly, Kristopher E.; Huang, Kerwyn Casey; Wingreen, Ned S.; Mukhopadhyay, Ranjan

2011-04-01

The bacterial cell wall is a network of sugar strands crosslinked by peptides that serve as the primary structure for bearing osmotic stress. Despite its importance in cellular survival, the robustness of the cell wall to network defects has been relatively unexplored. Treatment of the Gram-negative bacterium Escherichia coli with the antibiotic vancomycin, which disrupts the crosslinking of new material during growth, leads to the development of pronounced bulges and eventually of cell lysis. Here, we model the mechanics of the bulging of the cytoplasmic membrane through pores in the cell wall. We find that the membrane undergoes a transition between a nearly flat state and a spherical bulge at a critical pore radius of ~20 nm. This critical pore size is large compared to the typical distance between neighboring peptides and glycan strands, and hence pore size acts as a constraint on network integrity. We also discuss the general implications of our model to membrane deformations in eukaryotic blebbing and vesiculation in red blood cells.

Cell Wall Architecture of the Elongating Maize Coleoptile1

PubMed Central

Carpita, Nicholas C.; Defernez, Marianne; Findlay, Kim; Wells, Brian; Shoue, Douglas A.; Catchpole, Gareth; Wilson, Reginald H.; McCann, Maureen C.

2001-01-01

The primary walls of grasses are composed of cellulose microfibrils, glucuronoarabinoxylans (GAXs), and mixed-linkage β-glucans, together with smaller amounts of xyloglucans, glucomannans, pectins, and a network of polyphenolic substances. Chemical imaging by Fourier transform infrared microspectroscopy revealed large differences in the distributions of many chemical species between different tissues of the maize (Zea mays) coleoptile. This was confirmed by chemical analyses of isolated outer epidermal tissues compared with mesophyll-enriched preparations. Glucomannans and esterified uronic acids were more abundant in the epidermis, whereas β-glucans were more abundant in the mesophyll cells. The localization of β-glucan was confirmed by immunocytochemistry in the electron microscope and quantitative biochemical assays. We used field emission scanning electron microscopy, infrared microspectroscopy, and biochemical characterization of sequentially extracted polymers to further characterize the cell wall architecture of the epidermis. Oxidation of the phenolic network followed by dilute NaOH extraction widened the pores of the wall substantially and permitted observation by scanning electron microscopy of up to six distinct microfibrillar lamellae. Sequential chemical extraction of specific polysaccharides together with enzymic digestion of β-glucans allowed us to distinguish two distinct domains in the grass primary wall. First, a β-glucan-enriched domain, coextensive with GAXs of low degrees of arabinosyl substitution and glucomannans, is tightly associated around microfibrils. Second, a GAX that is more highly substituted with arabinosyl residues and additional glucomannan provides an interstitial domain that interconnects the β-glucan-coated microfibrils. Implications for current models that attempt to explain the biochemical and biophysical mechanism of wall loosening during cell growth are discussed. PMID:11598229

Cellular growth in plants requires regulation of cell wall biochemistry.

PubMed

Chebli, Youssef; Geitmann, Anja

2017-02-01

Cell and organ morphogenesis in plants are regulated by the chemical structure and mechanical properties of the extracellular matrix, the cell wall. The two primary load bearing components in the plant cell wall, the pectin matrix and the cellulose/xyloglucan network, are constantly remodelled to generate the morphological changes required during plant development. This remodelling is regulated by a plethora of loosening and stiffening agents such as pectin methyl-esterases, calcium ions, expansins, and glucanases. The tight spatio-temporal regulation of the activities of these agents is a sine qua non condition for proper morphogenesis at cell and tissue levels. The pectin matrix and the cellulose-xyloglucan network operate in concert and their behaviour is mutually dependent on their chemical, structural and mechanical modifications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cytochemical localization of calcium in cap cells of primary roots of Zea mays L

NASA Technical Reports Server (NTRS)

Moore, R.

1986-01-01

The distribution of calcium (Ca) in caps of vertically- and horizontally-oriented roots of Zea mays was monitored to determine its possible role in root graviresponsiveness. A modification of the antimonate precipitation procedure was used to localize Ca in situ. In vertically-oriented roots, the presumed graviperceptive (i.e., columella) cells were characterized by minimal and symmetric staining of the plasmalemma and mitochondria. No precipitate was present in plasmodesmata or cell walls. Within 5 min after horizontal reorientation, staining was associated with the portion of the cell wall adjacent to the distal end of the cell. This asymmetric staining persisted throughout the onset of gravicurvature. No staining of lateral cell walls of columella cells was observed at any stage of gravicurvature, suggesting that a lateral flow of Ca through the columella tissue of horizontally-oriented roots does not occur. The outermost peripheral cells of roots oriented horizontally and vertically secrete Ca through plasmodesmata-like structures in their cell walls. These results are discussed relative to proposed roles of root-cap Ca in root gravicurvature.

Age Effects on Hypocotyl Mechanics.

PubMed

Saxe, Friederike; Weichold, Susann; Reinecke, Antje; Lisec, Jan; Döring, Anett; Neumetzler, Lutz; Burgert, Ingo; Eder, Michaela

2016-01-01

Numerous studies deal with composition and molecular processes involved in primary cell wall formation and alteration in Arabidopsis. However, it still remains difficult to assess the relation between physiological properties and mechanical function at the cell wall level. The thin and fragile structure of primary cell walls and their large biological variability, partly related to structural changes during growth, make mechanical experiments challenging. Since, to the best of our knowledge, there is no reliable data in the literature about how the properties of the fully elongated zone of hypocotyls change with age. We studied in a series of experiments on two different seed batches the tensile properties the region below the growth zone of 4 to 7 day old etiolated Arabidopsis hypocotyls. Additionally, we analysed geometrical parameters, hypocotyl density and cellulose content as individual traits and their relation to tissue mechanics. No significant differences of the mechanical parameters of the non-growing region between 5-7 day old plants could be found whereas in 4 day old plants both tensile stiffness and ultimate tensile stress were significantly lower than in the older plants. Furthermore hypocotyl diameters and densities remain almost the same for 5, 6 and 7 day old seedlings. Naturally, hypocotyl lengths increase with age. The evaluation whether the choice-age or length-influences the mechanical properties showed that both are equally applicable sampling parameters. Additionally, our detailed study allows for the estimation of biological variability, connections between mechanics and hypocotyl age could be established and complement the knowledge on biochemistry and genetics affecting primary plant cell wall growth. The application of two different micromechanical devices for testing living Arabidopsis hypocotyls allows for emphasizing and discussing experimental limitations and for presenting a wide range of possibilities to address current and future questions related to plant cell wall mechanics, synthesis and growth in combination with molecular biology methodologies.

New insights into pioneer root xylem development: evidence obtained from Populus trichocarpa plants grown under field conditions

PubMed Central

Bagniewska-Zadworna, Agnieszka; Arasimowicz-Jelonek, Magdalena; Smoliński, Dariusz J.; Stelmasik, Agnieszka

2014-01-01

Background and Aims Effective programmed xylogenesis is critical to the structural framework of the plant root system and its central role in the acquisition and long-distance transport of water and nutrients. The process of xylem differentiation in pioneer roots under field conditions is poorly understood. In this study it is hypothesized that xylogenesis, an example of developmental programmed cell death (PCD), in the roots of woody plants demonstrates a clearly defined sequence of events resulting in cell death. A comprehensive analysis was therefore undertaken to identify the stages of xylogenesis in pioneer roots from procambial cells to fully functional vessels with lignified cell walls and secondary cell wall thickenings. Methods Xylem differentiation was monitored in the pioneer roots of Populus trichocarpa at the cytological level using rhizotrons under field conditions. Detection and localization of the signalling molecule nitric oxide (NO) and hydrogen peroxide (H2O2) was undertaken and a detailed examination of nuclear changes during xylogenesis was conducted. In addition, analyses of the expression of genes involved in secondary cell wall synthesis were performed in situ. Key Results The primary event in initially differentiating tracheary elements (TEs) was a burst of NO in thin-walled cells, followed by H2O2 synthesis and the appearance of TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling)-positive nuclei. The first changes in nuclear structure were observed in the early stages of xylogenesis of pioneer roots, prior to lignification; however, the nucleus was detectable under transmission electron microscopy in differentiating cells until the stage at which vacuole integrity was maintained, indicating that their degradation was slow and prolonged. The subsequent sequence of events involved secondary cell wall formation and autophagy. Potential gene markers from the cinnamyl alcohol dehydrogenase (CAD) gene family that were related to secondary wall synthesis were associated with primary xylogenesis, showing clear expression in cells that undergo differentiation into TEs and in the thin-walled cells adjacent to the xylem pole. Conclusions The early events of TE formation during pioneer root development are described, together with the timing of xylogenesis from signalling via NO, through secondary cell wall synthesis and autophagy events that are initiated long before lignification. This is the first work describing experiments conducted in planta on roots under field conditions demonstrating that the process of xylogenesis in vivo might be gradual and complex. PMID:24812251

AUXIN BINDING PROTEIN1 Links Cell Wall Remodeling, Auxin Signaling, and Cell Expansion in Arabidopsis[W

PubMed Central

Paque, Sébastien; Mouille, Grégory; Grandont, Laurie; Alabadí, David; Gaertner, Cyril; Goyallon, Arnaud; Muller, Philippe; Primard-Brisset, Catherine; Sormani, Rodnay; Blázquez, Miguel A.; Perrot-Rechenmann, Catherine

2014-01-01

Cell expansion is an increase in cell size and thus plays an essential role in plant growth and development. Phytohormones and the primary plant cell wall play major roles in the complex process of cell expansion. In shoot tissues, cell expansion requires the auxin receptor AUXIN BINDING PROTEIN1 (ABP1), but the mechanism by which ABP1 affects expansion remains unknown. We analyzed the effect of functional inactivation of ABP1 on transcriptomic changes in dark-grown hypocotyls and investigated the consequences of gene expression on cell wall composition and cell expansion. Molecular and genetic evidence indicates that ABP1 affects the expression of a broad range of cell wall–related genes, especially cell wall remodeling genes, mainly via an SCFTIR/AFB-dependent pathway. ABP1 also functions in the modulation of hemicellulose xyloglucan structure. Furthermore, fucosidase-mediated defucosylation of xyloglucan, but not biosynthesis of nonfucosylated xyloglucan, rescued dark-grown hypocotyl lengthening of ABP1 knockdown seedlings. In muro remodeling of xyloglucan side chains via an ABP1-dependent pathway appears to be of critical importance for temporal and spatial control of cell expansion. PMID:24424095

Effects of Pectin Molecular Weight Changes on the Structure, Dynamics, and Polysaccharide Interactions of Primary Cell Walls of Arabidopsis thaliana: Insights from Solid-State NMR.

PubMed

Phyo, Pyae; Wang, Tuo; Xiao, Chaowen; Anderson, Charles T; Hong, Mei

2017-09-11

Significant cellulose-pectin interactions in plant cell walls have been reported recently based on 2D 13 C solid-state NMR spectra of intact cell walls, but how these interactions affect cell growth has not been probed. Here, we characterize two Arabidopsis thaliana lines with altered expression of the POLYGALACTURONASE INVOLVED IN EXPANSION1 (PGX1) gene, which encodes a polygalacturonase that cleaves homogalacturonan (HG). PGX1 AT plants overexpress PGX1, have HG with lower molecular weight, and grow larger, whereas pgx1-2 knockout plants have HG with higher molecular weight and grow smaller. Quantitative 13 C solid-state NMR spectra show that PGX1 AT cell walls have lower galacturonic acid and xylose contents and higher HG methyl esterification than controls, whereas high molecular weight pgx1-2 walls have similar galacturonic acid content and methyl esterification as controls. 1 H-transferred 13 C INEPT spectra indicate that the interfibrillar HG backbones are more aggregated whereas the RG-I side chains are more dispersed in PGX1 AT cell walls than in pgx1-2 walls. In contrast, the pectins that are close to cellulose become more mobile and have weaker cross peaks with cellulose in PGX1 AT walls than in pgx1-2 walls. Together, these results show that polygalacturonase-mediated plant growth is accompanied by increased esterification and decreased cross-linking of HG, increased aggregation of interfibrillar HG, and weaker HG-cellulose interactions. These structural and dynamical differences give molecular insights into how pectins influence wall dynamics during cell growth.

The βI-galactosidase of Cicer arietinum is located in thickened cell walls such as those of collenchyma, sclerenchyma and vascular tissue.

PubMed

Martín, I; Jiménez, T; Hernández-Nistal, J; Dopico, B; Labrador, E

2011-09-01

We report localisation of the chickpea βI-Gal, a member of the chickpea β-galactosidase family, which contains at least four members. After generation of specific antibodies, the distribution and cellular immunolocalisation of the protein in different organs and developmental stages of the plant was studied. βI-Gal protein is much longer than the other chickpea β-galactosidases because of the presence of a lectin-like domain in the carboxyl terminus of the protein. Western blot experiments indicated that the active βI-Gal retains this lectin-like domain for its function in the plant. The βI-Gal protein was mainly detected in cell walls of elongating organs, such as seedling epicotyls and stem internodes. An immunolocation study indicated a very good correlation between the presence of this βΙ-galactosidase and cells whose walls are thickening, not only in aged epicotyls and mature internodes in the final phase of elongation, but mostly in cells with a support function, such as collenchyma cells, xylem and phloem fibres and a layer of sclerenchyma cells surrounding the vascular cylinder (perivascular fibres). These results could suggest a function for the βI-Gal in modification of cell wall polymers, leading to thicker walls than the primary cell walls. © 2011 German Botanical Society and The Royal Botanical Society of the Netherlands.

Gene Mining for Proline Based Signaling Proteins in Cell Wall of Arabidopsis thaliana

PubMed Central

Ihsan, Muhammad Z.; Ahmad, Samina J. N.; Shah, Zahid Hussain; Rehman, Hafiz M.; Aslam, Zubair; Ahuja, Ishita; Bones, Atle M.; Ahmad, Jam N.

2017-01-01

The cell wall (CW) as a first line of defense against biotic and abiotic stresses is of primary importance in plant biology. The proteins associated with cell walls play a significant role in determining a plant's sustainability to adverse environmental conditions. In this work, the genes encoding cell wall proteins (CWPs) in Arabidopsis were identified and functionally classified using geneMANIA and GENEVESTIGATOR with published microarrays data. This yielded 1605 genes, out of which 58 genes encoded proline-rich proteins (PRPs) and glycine-rich proteins (GRPs). Here, we have focused on the cellular compartmentalization, biological processes, and molecular functioning of proline-rich CWPs along with their expression at different plant developmental stages. The mined genes were categorized into five classes on the basis of the type of PRPs encoded in the cell wall of Arabidopsis thaliana. We review the domain structure and function of each class of protein, many with respect to the developmental stages of the plant. We have then used networks, hierarchical clustering and correlations to analyze co-expression, co-localization, genetic, and physical interactions and shared protein domains of these PRPs. This has given us further insight into these functionally important CWPs and identified a number of potentially new cell-wall related proteins in A. thaliana. PMID:28289422

Cell wall microstructure, pore size distribution and absolute density of hemp shiv

PubMed Central

Lawrence, M.; Ansell, M. P.; Hussain, A.

2018-01-01

This paper, for the first time, fully characterizes the intrinsic physical parameters of hemp shiv including cell wall microstructure, pore size distribution and absolute density. Scanning electron microscopy revealed microstructural features similar to hardwoods. Confocal microscopy revealed three major layers in the cell wall: middle lamella, primary cell wall and secondary cell wall. Computed tomography improved the visualization of pore shape and pore connectivity in three dimensions. Mercury intrusion porosimetry (MIP) showed that the average accessible porosity was 76.67 ± 2.03% and pore size classes could be distinguished into micropores (3–10 nm) and macropores (0.1–1 µm and 20–80 µm). The absolute density was evaluated by helium pycnometry, MIP and Archimedes' methods. The results show that these methods can lead to misinterpretation of absolute density. The MIP method showed a realistic absolute density (1.45 g cm−3) consistent with the density of the known constituents, including lignin, cellulose and hemi-cellulose. However, helium pycnometry and Archimedes’ methods gave falsely low values owing to 10% of the volume being inaccessible pores, which require sample pretreatment in order to be filled by liquid or gas. This indicates that the determination of the cell wall density is strongly dependent on sample geometry and preparation. PMID:29765652

Cell wall microstructure, pore size distribution and absolute density of hemp shiv

NASA Astrophysics Data System (ADS)

Jiang, Y.; Lawrence, M.; Ansell, M. P.; Hussain, A.

2018-04-01

This paper, for the first time, fully characterizes the intrinsic physical parameters of hemp shiv including cell wall microstructure, pore size distribution and absolute density. Scanning electron microscopy revealed microstructural features similar to hardwoods. Confocal microscopy revealed three major layers in the cell wall: middle lamella, primary cell wall and secondary cell wall. Computed tomography improved the visualization of pore shape and pore connectivity in three dimensions. Mercury intrusion porosimetry (MIP) showed that the average accessible porosity was 76.67 ± 2.03% and pore size classes could be distinguished into micropores (3-10 nm) and macropores (0.1-1 µm and 20-80 µm). The absolute density was evaluated by helium pycnometry, MIP and Archimedes' methods. The results show that these methods can lead to misinterpretation of absolute density. The MIP method showed a realistic absolute density (1.45 g cm-3) consistent with the density of the known constituents, including lignin, cellulose and hemi-cellulose. However, helium pycnometry and Archimedes' methods gave falsely low values owing to 10% of the volume being inaccessible pores, which require sample pretreatment in order to be filled by liquid or gas. This indicates that the determination of the cell wall density is strongly dependent on sample geometry and preparation.

α-Xylosidase plays essential roles in xyloglucan remodelling, maintenance of cell wall integrity, and seed germination in Arabidopsis thaliana

PubMed Central

Shigeyama, Takuma; Watanabe, Asuka; Tokuchi, Konatsu; Toh, Shigeo; Sakurai, Naoki; Shibuya, Naoto; Kawakami, Naoto

2016-01-01

Regulation and maintenance of cell wall physical properties are crucial for plant growth and environmental response. In the germination process, hypocotyl cell expansion and endosperm weakening are prerequisites for dicot seeds to complete germination. We have identified the Arabidopsis mutant thermoinhibition-resistant germination 1 (trg1), which has reduced seed dormancy and insensitivity to unfavourable conditions for germination owing to a loss-of-function mutation of TRG1/XYL1, which encodes an α-xylosidase. Compared to those of wild type, the elongating stem of trg1 showed significantly lower viscoelasticity, and the fruit epidermal cells were longitudinally shorter and horizontally enlarged. Actively growing tissues of trg1 over-accumulated free xyloglucan oligosaccharides (XGOs), and the seed cell wall had xyloglucan with a greatly reduced molecular weight. These observations suggest that XGOs reduce xyloglucan size by serving as an acceptor in transglycosylation and eventually enhancing cell wall loosening. TRG1/XYL1 gene expression was abundant in growing wild-type organs and tissues but relatively low in cells at most actively elongating part of the tissues, suggesting that α-xylosidase contributes to maintaining the mechanical integrity of the primary cell wall in the growing and pre-growing tissues. In germinating seeds of trg1, expression of genes encoding specific abscisic acid and gibberellin metabolism enzymes was altered in accordance with the aberrant germination phenotype. Thus, cell wall integrity could affect seed germination not only directly through the physical properties of the cell wall but also indirectly through the regulation of hormone gene expression. PMID:27605715

Deletion of Aspergillus nidulans GDP-mannose transporters affects hyphal morphometry, cell wall architecture, spore surface character, cell adhesion, and biofilm formation.

PubMed

Kadry, Ashraf A; El-Ganiny, Amira M; Mosbah, Rasha A; Kaminskyj, Susan G W

2018-07-01

Systemic human fungal infections are increasingly common. Aspergillus species cause most of the airborne fungal infections. Life-threatening invasive aspergillosis was formerly found only in immune-suppressed patients, but recently some strains of A. fumigatus have become primary pathogens. Many fungal cell wall components are absent from mammalian systems, so they are potential drug targets. Cell-wall-targeting drugs such as echinocandins are used clinically, although echinocandin-resistant strains were discovered shortly after their introduction. Currently there are no fully effective anti-fungal drugs. Fungal cell wall glycoconjugates modulate human immune responses, as well as fungal cell adhesion, biofilm formation, and drug resistance. Guanosine diphosphate (GDP) mannose transporters (GMTs) transfer GDP-mannose from the cytosol to the Golgi lumen prior to mannosylation. Aspergillus nidulans GMTs are encoded by gmtA and gmtB. Here we elucidate the roles of A. nidulans GMTs. Strains engineered to lack either or both GMTs were assessed for hyphal and colonial morphology, cell wall ultrastructure, antifungal susceptibility, spore hydrophobicity, adherence and biofilm formation. The gmt-deleted strains had smaller colonies with reduced sporulation and with thicker hyphal walls. The gmtA deficient spores had reduced hydrophobicity and were less adherent and less able to form biofilms in vitro. Thus, gmtA not only participates in maintaining the cell wall integrity but also plays an important role in biofilm establishment and adherence of A. nidulans. These findings suggested that GMTs have roles in A. nidulans growth and cell-cell interaction and could be a potential target for new antifungals that target virulence determinants.

Transcriptomic and anatomical complexity of primary, seminal, and crown roots highlight root type-specific functional diversity in maize (Zea mays L.)

PubMed Central

Tai, Huanhuan; Lu, Xin; Opitz, Nina; Marcon, Caroline; Paschold, Anja; Lithio, Andrew; Nettleton, Dan; Hochholdinger, Frank

2016-01-01

Maize develops a complex root system composed of embryonic and post-embryonic roots. Spatio-temporal differences in the formation of these root types imply specific functions during maize development. A comparative transcriptomic study of embryonic primary and seminal, and post-embryonic crown roots of the maize inbred line B73 by RNA sequencing along with anatomical studies were conducted early in development. Seminal roots displayed unique anatomical features, whereas the organization of primary and crown roots was similar. For instance, seminal roots displayed fewer cortical cell files and their stele contained more meta-xylem vessels. Global expression profiling revealed diverse patterns of gene activity across all root types and highlighted the unique transcriptome of seminal roots. While functions in cell remodeling and cell wall formation were prominent in primary and crown roots, stress-related genes and transcriptional regulators were over-represented in seminal roots, suggesting functional specialization of the different root types. Dynamic expression of lignin biosynthesis genes and histochemical staining suggested diversification of cell wall lignification among the three root types. Our findings highlight a cost-efficient anatomical structure and a unique expression profile of seminal roots of the maize inbred line B73 different from primary and crown roots. PMID:26628518

Salinity stress inhibits bean leaf expansion by reducing turgor, not wall extensibility

NASA Technical Reports Server (NTRS)

Neumann, P. M.; Van Volkenburgh, E.; Cleland, R. E.

1988-01-01

Treatment of bean (Phaseolus vulgaris L.) seedlings with low levels of salinity (50 or 100 millimolar NaCl) decreased the rate of light-induced leaf cell expansion in the primary leaves over a 3 day period. This decrease could be due to a reduction in one or both of the primary cellular growth parameters: wall extensibility and cell turgor. Wall extensibility was assessed by the Instron technique. Salinity did not decrease extensibility and caused small increases relative to the controls after 72 hours. On the other hand, 50 millimolar NaCl caused a significant reduction in leaf bulk turgor at 24 hours; adaptive decreases in leaf osmotic potential (osmotic adjustment) were more than compensated by parallel decreases in xylem tension potential and the leaf apoplastic solute potential, resulting in a decreased leaf water potential. It is concluded that in bean seedlings, mild salinity initially affects leaf growth rate by a decrease in turgor rather than by a reduction in wall extensibility. Moreover, long-term salinization (10 days) resulted in an apparent mechanical adjustment, i.e. an increase in wall extensibility, which may help counteract reductions in turgor and maintain leaf growth rates.

Homogalacturonan methyl-esterification and plant development.

PubMed

Wolf, Sebastian; Mouille, Grégory; Pelloux, Jérome

2009-09-01

The ability of a plant cell to expand is largely defined by the physical constraints imposed by its cell wall. Accordingly, cell wall properties have to be regulated during development. The pectic polysaccharide homogalacturonan is a major component of the plant primary walls. Biosynthesis and in muro modification of homogalacturonan have recently emerged as key determinants of plant development, controlling cell adhesion, organ development, and phyllotactic patterning. This review will focus on recent findings regarding impact of homogalacturonan content and methyl-esterification status of this polymer on plant life. De-methyl-esterification of homogalacturonan occurs through the action of the ubiquitous enzyme 'pectin methyl-esterase'. We here describe various strategies developed by the plant to finely tune the methyl-esterification status of homogalacturonan along key events of the plant lifecycle.

[Induction of polygalacturonases important in pathogenicity of Pseudomonas solanacearum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-01-01

Recent studies on the importance of hydroxyproline-rich glycoproteins (HPRG's) in the nature and function of plant cell walls have led to the question as to whether proteolytic enzymes are also involved in tissue maceration and act in concert with other cell wall degrading enzymes in the process. The primary objective of this research was to determine whether proteolytic enzymes, in combination with other enzymes, are involved in the degradation of plant cell walls and thus may be essential for pathogenesis by certain soft rot bacteria. The proteolytic enzymes of Erwinia carotovora subsp.carotovora (Ecc) grown on various media were examined bymore » isoelectrofocusing in polyacrylamide gels over a pH range of 3-10. In addition to the main protease present in culture filtrates, low concentrations of several other proteases were present in extracts from potato tubers infected by Ecc. These enzymes degraded gelatin, soluble collagen, and Hide Powder Azure, and showed weak activity on casein, but did not degrade insoluble collagen or elastin. Ecc proteases appear capable of degrading at least one type of cell wall protein in vitro, but we were unable to obtain evidence that these proteases can attack cell wall proteins in muro. The results indicate that some glycosidic alkali- labile bonds have to be broken befor Ecc proteases can degrade cell wall proteins. Thus, these proteases may play a role in cell wall degradation only when acting in concert with other enzymes that split glycosidic bonds.« less

[Induction of polygalacturonases important in pathogenicity of Pseudomonas solanacearum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-12-31

Recent studies on the importance of hydroxyproline-rich glycoproteins (HPRG`s) in the nature and function of plant cell walls have led to the question as to whether proteolytic enzymes are also involved in tissue maceration and act in concert with other cell wall degrading enzymes in the process. The primary objective of this research was to determine whether proteolytic enzymes, in combination with other enzymes, are involved in the degradation of plant cell walls and thus may be essential for pathogenesis by certain soft rot bacteria. The proteolytic enzymes of Erwinia carotovora subsp.carotovora (Ecc) grown on various media were examined bymore » isoelectrofocusing in polyacrylamide gels over a pH range of 3-10. In addition to the main protease present in culture filtrates, low concentrations of several other proteases were present in extracts from potato tubers infected by Ecc. These enzymes degraded gelatin, soluble collagen, and Hide Powder Azure, and showed weak activity on casein, but did not degrade insoluble collagen or elastin. Ecc proteases appear capable of degrading at least one type of cell wall protein in vitro, but we were unable to obtain evidence that these proteases can attack cell wall proteins in muro. The results indicate that some glycosidic alkali- labile bonds have to be broken befor Ecc proteases can degrade cell wall proteins. Thus, these proteases may play a role in cell wall degradation only when acting in concert with other enzymes that split glycosidic bonds.« less

βIII-Gal is involved in galactan reduction during phloem element differentiation in chickpea stems.

PubMed

Martín, Ignacio; Hernández-Nistal, Josefina; Albornos, Lucía; Labrador, Emilia; Dopico, Berta

2013-06-01

βIII-Gal, a member of the chickpea β-galactosidase family, is the enzyme responsible for the cell wall autolytic process. This enzyme, whose activity increases during epicotyl growth, displays significant hydrolytic activity against cell wall pectins, and its natural substrate has been determined as an arabinogalactan from the pectic fraction of the cell wall. In the present work, the localization of βIII-Gal in different seedling and plant organs was analyzed by using specific anti-βIII-Gal antibodies. Our results revealed that besides its possible role in cell wall loosening and in early events during primary xylem and phloem fiber differentiation βIII-Gal acts on the development of sieve elements. Localization of the enzyme in this tissue, both in epicotyls and radicles from seedlings and in the different stem internodes, is consistent with the reduction in galactan during the maturation of phloem elements, as can be observed with LM5 antibodies. Thus, βIII-Gal could act on its natural substrate, the neutral side chains of rhamnogalacturonan I, contributing to cell wall reinforcement allowing phloem elements to differentiate, and conferring the necessary strengthening of the cell wall to fulfill its function. This work completes the immunolocation studies of all known chickpea β-galactosidases. Taken together, our results reflect the broad range of developmental processes covered by different members of this protein family, and confirm their crucial role in cell wall remodeling during tissue differentiation.

Cellulose Structural Polymorphism in Plant Primary Cell Walls Investigated by High-Field 2D Solid-State NMR Spectroscopy and Density Functional Theory Calculations.

PubMed

Wang, Tuo; Yang, Hui; Kubicki, James D; Hong, Mei

2016-06-13

The native cellulose of bacterial, algal, and animal origins has been well studied structurally using X-ray and neutron diffraction and solid-state NMR spectroscopy, and is known to consist of varying proportions of two allomorphs, Iα and Iβ, which differ in hydrogen bonding, chain packing, and local conformation. In comparison, cellulose structure in plant primary cell walls is much less understood because plant cellulose has lower crystallinity and extensive interactions with matrix polysaccharides. Here we have combined two-dimensional magic-angle-spinning (MAS) solid-state nuclear magnetic resonance (solid-state NMR) spectroscopy at high magnetic fields with density functional theory (DFT) calculations to obtain detailed information about the structural polymorphism and spatial distributions of plant primary-wall cellulose. 2D (13)C-(13)C correlation spectra of uniformly (13)C-labeled cell walls of several model plants resolved seven sets of cellulose chemical shifts. Among these, five sets (denoted a-e) belong to cellulose in the interior of the microfibril while two sets (f and g) can be assigned to surface cellulose. Importantly, most of the interior cellulose (13)C chemical shifts differ significantly from the (13)C chemical shifts of the Iα and Iβ allomorphs, indicating that plant primary-wall cellulose has different conformations, packing, and hydrogen bonding from celluloses of other organisms. 2D (13)C-(13)C correlation experiments with long mixing times and with water polarization transfer revealed the spatial distributions and matrix-polysaccharide interactions of these cellulose structures. Celluloses f and g are well mixed chains on the microfibril surface, celluloses a and b are interior chains that are in molecular contact with the surface chains, while cellulose c resides in the core of the microfibril, outside spin diffusion contact with the surface. Interestingly, cellulose d, whose chemical shifts differ most significantly from those of bacterial, algal, and animal cellulose, interacts with hemicellulose, is poorly hydrated, and is targeted by the protein expansin during wall loosening. To obtain information about the C6 hydroxymethyl conformation of these plant celluloses, we carried out DFT calculations of (13)C chemical shifts, using the Iα and Iβ crystal structures as templates and varying the C5-C6 torsion angle. Comparison with the experimental chemical shifts suggests that all interior cellulose favor the tg conformation, but cellulose d also has a similar propensity to adopt the gt conformation. These results indicate that cellulose in plant primary cell walls, due to their interactions with matrix polysaccharides, and has polymorphic structures that are not a simple superposition of the Iα and Iβ allomorphs, thus distinguishing them from bacterial and animal celluloses.

Cellulose Structural Polymorphism in Plant Primary Cell Walls Investigated by High-Field 2D Solid-State NMR Spectroscopy and Density Functional Theory Calculations

PubMed Central

Wang, Tuo; Yang, Hui; Kubicki, James D.; Hong, Mei

2017-01-01

The native cellulose of bacterial, algal, and animal origins has been well studied structurally using X-ray and neutron diffraction and solid-state NMR spectroscopy, and is known to consist of varying proportions of two allomorphs, Iα and Iβ, which differ in hydrogen bonding, chain packing, and local conformation. In comparison, cellulose structure in plant primary cell walls is much less understood because plant cellulose has lower crystallinity and extensive interactions with matrix polysaccharides. Here we have combined two-dimensional magic-angle-spinning (MAS) solid-state nuclear magnetic resonance (solid-state NMR) spectroscopy at high magnetic fields with density functional theory (DFT) calculations to obtain detailed information about the structural polymorphism and spatial distributions of plant primary-wall cellulose. 2D 13C-13C correlation spectra of uniformly 13C-labeled cell walls of several model plants resolved seven sets of cellulose chemical shifts. Among these, five sets (denoted a-e) belong to cellulose in the interior of the microfibril while two sets (f and g) can be assigned to surface cellulose. Importantly, most of the interior cellulose 13C chemical shifts differ significantly from the 13C chemical shifts of the Iα and Iβ allomorphs, indicating that plant primary-wall cellulose has different conformations, packing and hydrogen bonding from celluloses of other organisms. 2D 13C-13C correlation experiments with long mixing times and with water polarization transfer revealed the spatial distributions and matrix-polysaccharide interactions of these cellulose structures. Cellulose f and g are well mixed chains on the microfibril surface, cellulose a and b are interior chains that are in molecular contact with the surface chains, while cellulose c resides in the core of the microfibril, outside spin diffusion contact with the surface. Interestingly, cellulose d, whose chemical shifts differ most significantly from those of bacterial, algal and animal cellulose, interacts with hemicellulose, is poorly hydrated, and is targeted by the protein expansin during wall loosening. To obtain information about the C6 hydroxymethyl conformation of these plant celluloses, we carried out DFT calculations of 13C chemical shifts, using the Iα and Iβ crystal structures as templates and varying the C5-C6 torsion angle. Comparison with the experimental chemical shifts suggests that all interior cellulose favor the tg conformation, but cellulose d also has a similar propensity to adopt the gt conformation. These results indicate that cellulose in plant primary cell walls, due to their interactions with matrix polysaccharides, has polymorphic structures that are not a simple superposition of the Iα and Iβ allomorphs, thus distinguishing them from bacterial and animal celluloses. PMID:27192562

Identification and characterization of glycosyltransferases involved in the synthesis of the side chains of the cell wall pectic polysaccharide rhamnogalacturonan II

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Neill, Malcolm

Our goal was to gain insight into the genes and proteins involved in the biosynthesis of rhamnogalacturonan II (RG-II), a borate cross-linked and structurally conserved pectic polysaccharide present in the primary cell walls of all vascular plants. The research conducted during the funding period established that (i) Avascular plants have the ability to synthesize UDP-apiose but lack the glycosyltransferase machinery required to synthesize RG-II or other apiose-containing cell wall glycans. (ii) RG-II structure is highly conserved in the Lemnaceae (duckweeds and relatives). However, the structures of other wall pectins and hemicellulose have changed substantial during the diversification of the Lemnaceae.more » This supports the notion that a precise structure of RG-II must be maintained to allow borate cross-linking to occur in a controlled manner. (iii) Enzymes involved in the conversion of UDP-GlcA to UDP-Api, UDP-Xyl, and UDP-Ara may have an important role in controlling the composition of duckweed cell walls. (iv) RG-II exists as the borate ester cross-linked dimer in the cell walls of soybean root hairs and roots. Thus, RG-II is present in the walls of plants cells that grow by tip or by expansive growth. (v) A reduction in RG-II cross-linking in the maize tls1 mutant, which lacks a borate channel protein, suggests that the growth defects observed in the mutant are, at least in part, due to defects in the cell wall.« less

Primary Signet Ring Cell Carcinoma of Rectum Diagnosed by Boring Biopsy in Combination with Endoscopic Mucosal Resection.

PubMed

Hirata, Yoshito; Kanno, Keishi; Kishikawa, Nobusuke; Tomoda, Shinji; Kimura, Kazuki; Kobayashi, Tomoki; Miyamori, Daisuke; Otani, Yuichiro; Mizooka, Masafumi; Arihiro, Koji; Oka, Shiro; Tanaka, Shinji; Tazuma, Susumu

2018-01-01

A 46-year-old man with severe back pain visited our hospital. Magnetic resonance imaging revealed extensive bone metastasis and rectal wall thickness. Colonoscopy revealed circumferential stenosis with edematous mucosa, suggesting colon cancer. However, histological findings of biopsy specimens revealed inflammatory cells but no malignant cells. The patient underwent endoscopic ultrasound, which demonstrated edematous wall thickness without destruction of the normal layer structure. After unsuccessful detection of neoplastic cells by boring biopsies, we performed endoscopic mucosal resection followed by boring biopsies that finally revealed signet ring cell carcinoma. Herein, we present a case and provide a review of the literature.

Validation test of 125 Ah advanced design IPV nickel-hydrogen flight cells

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1993-01-01

An update of validation test results confirming the advanced design nickel-hydrogen cell is presented. An advanced 125 Ah individual pressure vessel Ni-H cell was designed. The primary function of the advanced cell is to store and deliver energy for long-term LEO spacecraft missions. The new features of this design are: (1) use of 26 percent rather than 31 percent KOH electrolyte; (2) use of a patented catalyzed wall wick; (3) use of serrated-edge separators to facilitate gaseous O and H flow within the cell, while maintaining physical contact with the wall wick for electrolyte management; and (4) use of a floating rather than a fixed stack to accommodate Ni electrode expansion due to charge/discharge cycling. The significant improvements resulting from these innovations are extended cycle life; enhanced thermal, electrolyte, and oxygen management; and accommodation of Ni electrode expansion. Six 125 Ah flight cells based on this design were fabricated; the catalyzed wall wick cells have been cycled for over 19,000 cycles with no cell failures in the continuing test. Two of the noncatalyzed wall wick cells failed (cycles 9588 and 13,900).

Primary undifferentiated small round cell sarcoma of the deep abdominal wall with a novel variant of t(10;19) CIC-DUX4 gene fusion.

PubMed

Tsukamoto, Yoshitane; Futani, Hiroyuki; Yoshiya, Shinichi; Watanabe, Takahiro; Kihara, Takako; Matsuo, Shohei; Hirota, Seiichi

2017-10-01

We experienced a 38-year-old Japanese male with t(10;19) CIC-DUX4 -positive undifferentiated small round cell sarcoma in the deep abdominal wall. Three months before his first visit to our hospital, he noticed a mass in his right abdominal wall. Computed tomography on admission revealed a solid abdominal tumor 70×53mm in size and multiple small tumors in both lungs. The biopsy of the abdominal tumor revealed undifferentiated small round cell sarcoma, suggestive of Ewing sarcoma. Under the clinical diagnosis of Ewing-like sarcoma of the abdominal wall with multiple lung metastases, several cycles of ICE (ifosfamide, carboplatin and etoposide) therapy were performed. After the chemotherapy, the lung metastases disappeared, while the primary lesion rapidly grew. Additional VDC (vincristine, doxorubicin and cyclophosphamide) therapy was carried out without apparent effect. Although the surgical removal of the primary lesion was done, peritoneal dissemination and a huge metastatic liver tumor appeared thereafter. The patient died of disease progression two months after the surgery. The total clinical course was approximately one year, showing that the tumor was extremely aggressive. The tumor cells of the surgical specimen were positive for CD99, WT1, calretinin, INI1, ERG and Fli1 by immunohistochemistry. Fusion gene analyses using the frozen surgical material revealed negativity for EWSR1-Fli1, EWSR1-ERG and t(4;19) CIC-DUX4 fusions, but positivity for t(10;19) CIC-DUX4 fusion. Thus, we made a final pathological diagnosis of t(10;19) CIC-DUX4-positive undifferentiated small round cell sarcoma. To our knowledge, this is the 13th case of t(10;19) CIC-DUX4 undifferentiated small round cell sarcoma with precise clinicopathological information. Especially in our case, two types of t(10;19) CIC-DUX4 fusion transcripts were observed, both of which are in-frame and novel. Copyright © 2017 Elsevier GmbH. All rights reserved.

Formation of Rhamnogalacturonan II-Borate Dimer in Pectin Determines Cell Wall Thickness of Pumpkin Tissue1

PubMed Central

Ishii, Tadashi; Matsunaga, Toshiro; Hayashi, Noriko

2001-01-01

Boron (B) deficiency results in inhibition of pumpkin (Cucurbia moschata Duchesne) growth that is accompanied by swelling of the cell walls. Monomeric rhamnogalacturonan II (mRG-II) accounted for 80% to 90% of the total RG-II in B-deficient walls, whereas the borate ester cross-linked RG-II dimer (dRG-II-B) accounted for more than 80% of the RG-II in control plants. The results of glycosyl residue and glycosyl linkage composition analyses of the RG-II from control and B-deficient plants were similar. Thus, B deficiency does not alter the primary structure of RG-II. The addition of 10B-enriched boric acid to B-deficient plants resulted within 5 h in the conversion of mRG-II to dRG-II-10B. The wall thickness of the 10B-treated plants and control plants was similar. The formation and possible functions of a borate ester cross-linked RG-II in the cell walls are discussed. PMID:11500567

Honeycomb vs. Foam: Evaluating Potential Upgrades to ISS Module Shielding

NASA Technical Reports Server (NTRS)

Ryan, Shannon J.; Christiansen, Eric L.

2009-01-01

The presence of honeycomb cells in a dual-wall structure is advantageous for mechanical performance and low weight in spacecraft primary structures but detrimental for shielding against impact of micrometeoroid and orbital debris particles (MMOD). The presence of honeycomb cell walls acts to restrict the expansion of projectile and bumper fragments, resulting in the impact of a more concentrated (and thus lethal) fragment cloud upon the shield rear wall. The Multipurpose Laboratory Module (MLM) is a Russian research module scheduled for launch and ISS assembly in 2011 (currently under review). Baseline shielding of the MLM is expected to be predominantly similar to that of the existing Functional Energy Block (FGB), utilizing a baseline triple wall configuration with honeycomb sandwich panels for the dual bumpers and a thick monolithic aluminum pressure wall. The MLM module is to be docked to the nadir port of the Zvezda service module and, as such, is subject to higher debris flux than the FGB module (which is aligned along the ISS flight vector). Without upgrades to inherited shielding, the MLM penetration risk is expected to be significantly higher than that of the FGB module. Open-cell foam represents a promising alternative to honeycomb as a sandwich panel core material in spacecraft primary structures as it provides comparable mechanical performance with a minimal increase in weight while avoiding structural features (i.e. channeling cells) detrimental to MMOD shielding performance. In this study, the effect of replacing honeycomb sandwich panel structures with metallic open-cell foam structures on MMOD shielding performance is assessed for an MLM-representative configuration. A number of hypervelocity impact tests have been performed on both the baseline honeycomb configuration and upgraded foam configuration, and differences in target damage, failure limits, and derived ballistic limit equations are discussed.

Four Novel Cellulose Synthase (CESA) Genes from Birch (Betula platyphylla Suk.) Involved in Primary and Secondary Cell Wall Biosynthesis

PubMed Central

Liu, Xuemei; Wang, Qiuyu; Chen, Pengfei; Song, Funan; Guan, Minxiao; Jin, Lihua; Wang, Yucheng; Yang, Chuanping

2012-01-01

Cellulose synthase (CESA), which is an essential catalyst for the generation of plant cell wall biomass, is mainly encoded by the CesA gene family that contains ten or more members. In this study; four full-length cDNAs encoding CESA were isolated from Betula platyphylla Suk., which is an important timber species, using RT-PCR combined with the RACE method and were named as BplCesA3, −4, −7 and −8. These deduced CESAs contained the same typical domains and regions as their Arabidopsis homologs. The cDNA lengths differed among these four genes, as did the locations of the various protein domains inferred from the deduced amino acid sequences, which shared amino acid sequence identities ranging from only 63.8% to 70.5%. Real-time RT-PCR showed that all four BplCesAs were expressed at different levels in diverse tissues. Results indicated that BplCESA8 might be involved in secondary cell wall biosynthesis and floral development. BplCESA3 appeared in a unique expression pattern and was possibly involved in primary cell wall biosynthesis and seed development; it might also be related to the homogalacturonan synthesis. BplCESA7 and BplCESA4 may be related to the formation of a cellulose synthase complex and participate mainly in secondary cell wall biosynthesis. The extremely low expression abundance of the four BplCESAs in mature pollen suggested very little involvement of them in mature pollen formation in Betula. The distinct expression pattern of the four BplCesAs suggested they might participate in developments of various tissues and that they are possibly controlled by distinct mechanisms in Betula. PMID:23202892

Crystalline and amorphous cellulose in the secondary walls of Arabidopsis.

PubMed

Ruel, Katia; Nishiyama, Yoshiharu; Joseleau, Jean-Paul

2012-09-01

In the cell walls of higher plants, cellulose chains are present in crystalline microfibril, with an amorphous part at the surface, or present as amorphous material. To assess the distribution and relative occurrence of the two forms of cellulose in the inflorescence stem of Arabidopsis, we used two carbohydrate-binding modules, CBM3a and CBM28, specific for crystalline and amorphous cellulose, respectively, with immunogold detection in TEM. The binding of the two CBMs displayed specific patterns suggesting that the synthesis of cellulose leads to variable nanodomains of cellulose structures according to cell type. In developing cell walls, only CBM3a bound significantly to the incipient primary walls, indicating that at the onset of its deposition cellulose is in a crystalline structure. As the secondary wall develops, the labeling with both CBMs becomes more intense. The variation of the labeling pattern by CBM3a between transverse and longitudinal sections appeared related to microfibril orientation and differed between fibers and vessels. Although the two CBMs do not allow the description of the complete status of cellulose microstructures, they revealed the dynamics of the deposition of crystalline and amorphous forms of cellulose during wall formation and between cell types adapting cellulose microstructures to the cell function. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Effect of LEO cycling on 125 Ah advanced design IPV nickel-hydrogen battery cells

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1990-01-01

An advanced 125 Ah individual pressure vessel (IPV) nickel-hydrogen cell was designed. The primary function of the advanced cell, is to store and deliver energy for long term, low earth-orbit (LEO) spacecraft missions. The new features of this design are: (1) use of 26 percent rather than 31 percent potassium hydroxide (KOH) electrolyte, (2) use of a patented catalyzed wall wick, (3) use of serrated edge separators to facilitate gaseous oxygen and hydrogen flow within the cell, while still maintaining physical contact with the wall wick for electrolyte management, and (4) use of a floating rather than a fixed stack (state-of-the-art) to accommodate nickel electrode expansion. Six 125 Ah flight cells based on this design were fabricated by Eagle-Picher. Three of the cells contain all of the advanced features (test cells) and three are the same as the test cells except they don't have catalyst on the wall wick (control cells). All six cells are in the process of being evaluated in a LEO cycle life test. The cells have accumulated about 4700 LEO cycles (60 percent DOD 10 C). There have been no cell failures, the catalyzed wall wick cells however, are performing better.

Effect of LEO cycling on 125 Ah advanced design IPV nickel-hydrogen battery cells

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1990-01-01

An advanced 125 Ah individual pressure vessel (IPV) nickel-hydrogen cell was designed. The primary function of the advanced cell is to store and deliver energy for long-term, low earth-orbit (LEO) spacecraft missions. The new features of this design are: (1) use of 26 percent rather than 31 percent potassium hydroxide (KOH) electrolyte, (2) use of a patented catalyzed wall wick, (3) use of serrated-edge separators to facilitate gaseous oxygen and hydrogen flow within the cell, while still maintaining physical contact with the wall wick for electrolyte management, and (4) use of a floating rather than a fixed stack (state-of-the-art) to accommodate nickel electrode expansion. Six 125-Ah flight cells based on this design were fabricated by Eagle-Picher. Three of the cells contain all of the advanced features (test cells) and three are the same as the test cells except they don't have catalyst on the wall wick (control cells). All six cells are in the process of being evaluated in a LEO cycle life test. The cells have accumulated about 4700 LEO cycles (60 percent DOD 10 C). There have been no cell failures; the catalyzed wall wick cells, however, are performing better.

Modular off-axis solar concentrator

DOEpatents

Plesniak, Adam P; Hall, John C

2015-01-27

A solar concentrator including a housing defining a vertical axis and including a receiving wall connected to a reflecting wall to define an internal volume and an opening into the internal volume, wherein the reflecting wall defines at least one primary optical element, and wherein at least a portion of the reflecting wall includes a layer of reflective material, the housing further including a cover connected to the receiving wall and the reflecting wall to seal the opening, and at least one receiver mounted on the receiving wall such that a vertical axis of the receiver is disposed at a non-zero angle relative to the vertical axis of the housing, the receiver including at least one photovoltaic cell.

Cellulose synthase complexes act in a concerted fashion to synthesize highly aggregated cellulose in secondary cell walls of plants

PubMed Central

Li, Shundai; Bashline, Logan; Zheng, Yunzhen; Xin, Xiaoran; Huang, Shixin; Kong, Zhaosheng; Kim, Seong H.; Cosgrove, Daniel J.; Gu, Ying

2016-01-01

Cellulose, often touted as the most abundant biopolymer on Earth, is a critical component of the plant cell wall and is synthesized by plasma membrane-spanning cellulose synthase (CESA) enzymes, which in plants are organized into rosette-like CESA complexes (CSCs). Plants construct two types of cell walls, primary cell walls (PCWs) and secondary cell walls (SCWs), which differ in composition, structure, and purpose. Cellulose in PCWs and SCWs is chemically identical but has different physical characteristics. During PCW synthesis, multiple dispersed CSCs move along a shared linear track in opposing directions while synthesizing cellulose microfibrils with low aggregation. In contrast, during SCW synthesis, we observed swaths of densely arranged CSCs that moved in the same direction along tracks while synthesizing cellulose microfibrils that became highly aggregated. Our data support a model in which distinct spatiotemporal features of active CSCs during PCW and SCW synthesis contribute to the formation of cellulose with distinct structure and organization in PCWs and SCWs of Arabidopsis thaliana. This study provides a foundation for understanding differences in the formation, structure, and organization of cellulose in PCWs and SCWs. PMID:27647923

Cellulose synthase complexes act in a concerted fashion to synthesize highly aggregated cellulose in secondary cell walls of plants.

PubMed

Li, Shundai; Bashline, Logan; Zheng, Yunzhen; Xin, Xiaoran; Huang, Shixin; Kong, Zhaosheng; Kim, Seong H; Cosgrove, Daniel J; Gu, Ying

2016-10-04

Cellulose, often touted as the most abundant biopolymer on Earth, is a critical component of the plant cell wall and is synthesized by plasma membrane-spanning cellulose synthase (CESA) enzymes, which in plants are organized into rosette-like CESA complexes (CSCs). Plants construct two types of cell walls, primary cell walls (PCWs) and secondary cell walls (SCWs), which differ in composition, structure, and purpose. Cellulose in PCWs and SCWs is chemically identical but has different physical characteristics. During PCW synthesis, multiple dispersed CSCs move along a shared linear track in opposing directions while synthesizing cellulose microfibrils with low aggregation. In contrast, during SCW synthesis, we observed swaths of densely arranged CSCs that moved in the same direction along tracks while synthesizing cellulose microfibrils that became highly aggregated. Our data support a model in which distinct spatiotemporal features of active CSCs during PCW and SCW synthesis contribute to the formation of cellulose with distinct structure and organization in PCWs and SCWs of Arabidopsis thaliana This study provides a foundation for understanding differences in the formation, structure, and organization of cellulose in PCWs and SCWs.

Differential metabolism of pectic galactan in tomato and strawberry fruit: detection of the LM26 branched galactan epitope in ripe strawberry fruit.

PubMed

Posé, Sara; Marcus, Susan E; Paul Knox, J

2018-04-24

Antibody-based approaches have been used to study cell wall architecture and modifications during the ripening process of two important fleshy fruit crops: tomato and strawberry. Cell wall polymers in both unripe and ripe fruits have been sequentially solubilized and fractions analysed with sets of monoclonal antibodies focusing on the pectic polysaccharides. We demonstrate the specific detection of the LM26 branched galactan epitope, associated with rhamnogalacturonan-I, in cell walls of ripe strawberry fruit. Analytical approaches confirm that the LM26 epitope is linked to sets of rhamnogalacturonan-I and homogalacturonan molecules. The cellulase-degradation of cellulose-rich residues that releases cell wall polymers intimately linked with cellulose microfibrils has been used to explore aspects of branched galactan occurrence and galactan metabolism. In situ analyses of ripe strawberry fruits indicate that the LM26 epitope is present in all primary cell walls and also particularly abundant in vascular tissues. The significance of the occurrence of branched galactan structures in the side chains of rhamnogalacturonan-I pectins in the context of ripening strawberry fruit is discussed. This article is protected by copyright. All rights reserved.

α-Xylosidase plays essential roles in xyloglucan remodelling, maintenance of cell wall integrity, and seed germination in Arabidopsis thaliana.

PubMed

Shigeyama, Takuma; Watanabe, Asuka; Tokuchi, Konatsu; Toh, Shigeo; Sakurai, Naoki; Shibuya, Naoto; Kawakami, Naoto

2016-10-01

Regulation and maintenance of cell wall physical properties are crucial for plant growth and environmental response. In the germination process, hypocotyl cell expansion and endosperm weakening are prerequisites for dicot seeds to complete germination. We have identified the Arabidopsis mutant thermoinhibition-resistant germination 1 (trg1), which has reduced seed dormancy and insensitivity to unfavourable conditions for germination owing to a loss-of-function mutation of TRG1/XYL1, which encodes an α-xylosidase. Compared to those of wild type, the elongating stem of trg1 showed significantly lower viscoelasticity, and the fruit epidermal cells were longitudinally shorter and horizontally enlarged. Actively growing tissues of trg1 over-accumulated free xyloglucan oligosaccharides (XGOs), and the seed cell wall had xyloglucan with a greatly reduced molecular weight. These observations suggest that XGOs reduce xyloglucan size by serving as an acceptor in transglycosylation and eventually enhancing cell wall loosening. TRG1/XYL1 gene expression was abundant in growing wild-type organs and tissues but relatively low in cells at most actively elongating part of the tissues, suggesting that α-xylosidase contributes to maintaining the mechanical integrity of the primary cell wall in the growing and pre-growing tissues. In germinating seeds of trg1, expression of genes encoding specific abscisic acid and gibberellin metabolism enzymes was altered in accordance with the aberrant germination phenotype. Thus, cell wall integrity could affect seed germination not only directly through the physical properties of the cell wall but also indirectly through the regulation of hormone gene expression. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Spatial gradients in cell wall composition and transcriptional profiles along elongating maize internodes

PubMed Central

2014-01-01

Background The elongating maize internode represents a useful system for following development of cell walls in vegetative cells in the Poaceae family. Elongating internodes can be divided into four developmental zones, namely the basal intercalary meristem, above which are found the elongation, transition and maturation zones. Cells in the basal meristem and elongation zones contain mainly primary walls, while secondary cell wall deposition accelerates in the transition zone and predominates in the maturation zone. Results The major wall components cellulose, lignin and glucuronoarabinoxylan (GAX) increased without any abrupt changes across the elongation, transition and maturation zones, although GAX appeared to increase more between the elongation and transition zones. Microarray analyses show that transcript abundance of key glycosyl transferase genes known to be involved in wall synthesis or re-modelling did not match the increases in cellulose, GAX and lignin. Rather, transcript levels of many of these genes were low in the meristematic and elongation zones, quickly increased to maximal levels in the transition zone and lower sections of the maturation zone, and generally decreased in the upper maturation zone sections. Genes with transcript profiles showing this pattern included secondary cell wall CesA genes, GT43 genes, some β-expansins, UDP-Xylose synthase and UDP-Glucose pyrophosphorylase, some xyloglucan endotransglycosylases/hydrolases, genes involved in monolignol biosynthesis, and NAM and MYB transcription factor genes. Conclusions The data indicated that the enzymic products of genes involved in cell wall synthesis and modification remain active right along the maturation zone of elongating maize internodes, despite the fact that corresponding transcript levels peak earlier, near or in the transition zone. PMID:24423166

Expression of mung bean pectin acetyl esterase in potato tubers: effect on acetylation of cell wall polymers and tuber mechanical properties.

PubMed

Orfila, Caroline; Dal Degan, Florence; Jørgensen, Bodil; Scheller, Henrik Vibe; Ray, Peter M; Ulvskov, Peter

2012-07-01

A mung bean (Vigna radiata) pectin acetyl esterase (CAA67728) was heterologously expressed in tubers of potato (Solanum tuberosum) under the control of the granule-bound starch synthase promoter or the patatin promoter in order to probe the significance of O-acetylation on cell wall and tissue properties. The recombinant tubers showed no apparent macroscopic phenotype. The enzyme was recovered from transgenic tubers using a high ionic strength buffer and the extract was active against a range of pectic substrates. Partial in vivo de-acetylation of cell wall polysaccharides occurred in the transformants, as shown by a 39% decrease in the degree of acetylation (DA) of tuber cell wall material (CWM). Treatment of CWM using a combination of endo-polygalacturonase and pectin methyl esterase extracted more pectin polymers from the transformed tissue compared to wild type. The largest effect of the pectin acetyl esterase (68% decrease in DA) was seen in the residue from this extraction, suggesting that the enzyme is preferentially active on acetylated pectin that is tightly bound to the cell wall. The effects of acetylation on tuber mechanical properties were investigated by tests of failure under compression and by determination of viscoelastic relaxation spectra. These tests suggested that de-acetylation resulted in a stiffer tuber tissue and a stronger cell wall matrix, as a result of changes to a rapidly relaxing viscoelastic component. These results are discussed in relation to the role of pectin acetylation in primary cell walls and its implications for industrial uses of potato fibres.

Sustained expression of MCP-1 by low wall shear stress loading concomitant with turbulent flow on endothelial cells of intracranial aneurysm.

PubMed

Aoki, Tomohiro; Yamamoto, Kimiko; Fukuda, Miyuki; Shimogonya, Yuji; Fukuda, Shunichi; Narumiya, Shuh

2016-05-09

Enlargement of a pre-existing intracranial aneurysm is a well-established risk factor of rupture. Excessive low wall shear stress concomitant with turbulent flow in the dome of an aneurysm may contribute to progression and rupture. However, how stress conditions regulate enlargement of a pre-existing aneurysm remains to be elucidated. Wall shear stress was calculated with 3D-computational fluid dynamics simulation using three cases of unruptured intracranial aneurysm. The resulting value, 0.017 Pa at the dome, was much lower than that in the parent artery. We loaded wall shear stress corresponding to the value and also turbulent flow to the primary culture of endothelial cells. We then obtained gene expression profiles by RNA sequence analysis. RNA sequence analysis detected hundreds of differentially expressed genes among groups. Gene ontology and pathway analysis identified signaling related with cell division/proliferation as overrepresented in the low wall shear stress-loaded group, which was further augmented by the addition of turbulent flow. Moreover, expression of some chemoattractants for inflammatory cells, including MCP-1, was upregulated under low wall shear stress with concomitant turbulent flow. We further examined the temporal sequence of expressions of factors identified in an in vitro study using a rat model. No proliferative cells were detected, but MCP-1 expression was induced and sustained in the endothelial cell layer. Low wall shear stress concomitant with turbulent flow contributes to sustained expression of MCP-1 in endothelial cells and presumably plays a role in facilitating macrophage infiltration and exacerbating inflammation, which leads to enlargement or rupture.

Transcriptomic and anatomical complexity of primary, seminal, and crown roots highlight root type-specific functional diversity in maize (Zea mays L.).

PubMed

Tai, Huanhuan; Lu, Xin; Opitz, Nina; Marcon, Caroline; Paschold, Anja; Lithio, Andrew; Nettleton, Dan; Hochholdinger, Frank

2016-02-01

Maize develops a complex root system composed of embryonic and post-embryonic roots. Spatio-temporal differences in the formation of these root types imply specific functions during maize development. A comparative transcriptomic study of embryonic primary and seminal, and post-embryonic crown roots of the maize inbred line B73 by RNA sequencing along with anatomical studies were conducted early in development. Seminal roots displayed unique anatomical features, whereas the organization of primary and crown roots was similar. For instance, seminal roots displayed fewer cortical cell files and their stele contained more meta-xylem vessels. Global expression profiling revealed diverse patterns of gene activity across all root types and highlighted the unique transcriptome of seminal roots. While functions in cell remodeling and cell wall formation were prominent in primary and crown roots, stress-related genes and transcriptional regulators were over-represented in seminal roots, suggesting functional specialization of the different root types. Dynamic expression of lignin biosynthesis genes and histochemical staining suggested diversification of cell wall lignification among the three root types. Our findings highlight a cost-efficient anatomical structure and a unique expression profile of seminal roots of the maize inbred line B73 different from primary and crown roots. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Selectively Structural Determination of Cellulose and Hemicellulose in Plant Cell Wall

NASA Astrophysics Data System (ADS)

Huang, Shih-Chun; Park, Yong; Cosgrove, Daniel; Maranas, Janna; Janna Maranas Team; Daniel Cosgrove Team

2013-03-01

Primary plant cell walls support the plant body, and regulate cell size, and plant growth. It contains several biopolymers that can be categorized into three groups: cellulose, hemicellulose and pectin. To determine the structure of plant cell wall, we use small angle neutron scattering in combination with selective deuteration and contrast matching method. We compare the structure between wild Arabidopsis thaliana and its xyloglucan-deficient mutant. Hemicellulose in both samples forms coil with similar radii of gyration, and weak scattering from the mutant suggests a limited amount of hemicellulose in the xyloglucan-deficient mutant. We observe good amount of hemicellulose coating on cellulose microfibrils only in wild Arabidopsis. The absence of coating in its xyloglucan-deficient mutation suggests the other polysaccharides do not have comparable interaction with cellulose. This highlights the importance of xyloglucan in plant cell wall. At larger scale, the average distance between cellulose fibril is found smaller than reported value, which directly reflects on their smaller matured plant size. U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Center for LignoCellulose Structure and Formation

Quantitative parameters of seminiferous epithelium in secretory and excretory oligoazoospermia.

PubMed

Francavilla, S; Martini, M; Properzi, G; Cordeschi, G

1990-01-01

Testicular biopsy specimens from infertile men (sperm count, less than 10(6)/ml) were evaluated on 1-micron thick sections, and counts of stem cells and differentiated spermatogonia, primary spermatocytes, early and late spermatids, and Sertoli cells were compared to counts in six fertile men. Biopsy specimens were also compared for the appearance of seminiferous tubule wall, blood vessels, and interstitium. Infertile men were grouped according to the following diagnoses: hypospermatogenesis (n = 5), spermatocyte arrest of spermatogenesis (n = 5), and obstruction of the genital tract (n = 7). A low productivity of spermatogenesis in cases of hypospermatogenesis appeared to be due to an exaggerated degeneration of primary spermatocytes and to a yield of abnormal spermatids. A block of meiosis in spermatocyte arrest was associated with a degeneration of primary spermatocytes and with a reduced number of staminal spermatogonia. Abnormal spermiogenesis was observed in cases of obstruction of the genital tract and was associated with an increase in stem cell spermatogonia. A thickening of seminiferous tubule and blood vessel walls could be responsible for the limited functional capacity of Sertoli cells, causing altered spermiogenesis in cases of excretory azoospermia. A severe primitive failure of Sertoli cells in secretory oligoazoospermia could account for a deranged maturation and degeneration of premeiotic and postmeiotic germ cells.

Effect of single-walled carbon nanotubes on primary immune cells in vitro

NASA Astrophysics Data System (ADS)

Zhang, Jin-chao; Ji, Xiao-yu; Liu, Cui-lian; Shen, Shi-gang; Wang, Shu-xiang; Sun, Jing

2008-06-01

Carbon nanotubes (CNTs) are emerging as innovative tools in nanobiotechnology. However, their toxic effects on environment and health have become an issue of great concern. The effect of single-walled carbon nanotubes (SWCNTs) on primary immune cells in vitro was studied in this paper. The results indicated that SWCNTs (25 and 50 μg/mL) could promote the proliferation of spleen cells. However, they had no significant effect on the proliferation of spleen cells at concentrations of 1 and 10 μg/mL. They also had no effect on T-lymphocyte proliferation stimulated by concanavalinA (ConA) at lower concentrations. Moreover, they turned to inhibit T-lymphocyte proliferation at higher concentrations. It was found that SWCNTs inhibited the B-lymphocyte proliferation stimulated by lipopolysaccharides (LPS) at concentrations of 1, 10, 25 and 50 μg/mL. What is more, they significantly decreased the Natural Killer (NK) cell activity compared with the control group at all tested concentrations. The results suggest that SWCNTs have possibly negative effects on immune cells in vitro.

Structure of Cellulose Microfibrils in Primary Cell Walls from Collenchyma1[C][W][OA

PubMed Central

Thomas, Lynne H.; Forsyth, V. Trevor; Šturcová, Adriana; Kennedy, Craig J.; May, Roland P.; Altaner, Clemens M.; Apperley, David C.; Wess, Timothy J.; Jarvis, Michael C.

2013-01-01

In the primary walls of growing plant cells, the glucose polymer cellulose is assembled into long microfibrils a few nanometers in diameter. The rigidity and orientation of these microfibrils control cell expansion; therefore, cellulose synthesis is a key factor in the growth and morphogenesis of plants. Celery (Apium graveolens) collenchyma is a useful model system for the study of primary wall microfibril structure because its microfibrils are oriented with unusual uniformity, facilitating spectroscopic and diffraction experiments. Using a combination of x-ray and neutron scattering methods with vibrational and nuclear magnetic resonance spectroscopy, we show that celery collenchyma microfibrils were 2.9 to 3.0 nm in mean diameter, with a most probable structure containing 24 chains in cross section, arranged in eight hydrogen-bonded sheets of three chains, with extensive disorder in lateral packing, conformation, and hydrogen bonding. A similar 18-chain structure, and 24-chain structures of different shape, fitted the data less well. Conformational disorder was largely restricted to the surface chains, but disorder in chain packing was not. That is, in position and orientation, the surface chains conformed to the disordered lattice constituting the core of each microfibril. There was evidence that adjacent microfibrils were noncovalently aggregated together over part of their length, suggesting that the need to disrupt these aggregates might be a constraining factor in growth and in the hydrolysis of cellulose for biofuel production. PMID:23175754

Structure of cellulose microfibrils in primary cell walls from collenchyma.

PubMed

Thomas, Lynne H; Forsyth, V Trevor; Sturcová, Adriana; Kennedy, Craig J; May, Roland P; Altaner, Clemens M; Apperley, David C; Wess, Timothy J; Jarvis, Michael C

2013-01-01

In the primary walls of growing plant cells, the glucose polymer cellulose is assembled into long microfibrils a few nanometers in diameter. The rigidity and orientation of these microfibrils control cell expansion; therefore, cellulose synthesis is a key factor in the growth and morphogenesis of plants. Celery (Apium graveolens) collenchyma is a useful model system for the study of primary wall microfibril structure because its microfibrils are oriented with unusual uniformity, facilitating spectroscopic and diffraction experiments. Using a combination of x-ray and neutron scattering methods with vibrational and nuclear magnetic resonance spectroscopy, we show that celery collenchyma microfibrils were 2.9 to 3.0 nm in mean diameter, with a most probable structure containing 24 chains in cross section, arranged in eight hydrogen-bonded sheets of three chains, with extensive disorder in lateral packing, conformation, and hydrogen bonding. A similar 18-chain structure, and 24-chain structures of different shape, fitted the data less well. Conformational disorder was largely restricted to the surface chains, but disorder in chain packing was not. That is, in position and orientation, the surface chains conformed to the disordered lattice constituting the core of each microfibril. There was evidence that adjacent microfibrils were noncovalently aggregated together over part of their length, suggesting that the need to disrupt these aggregates might be a constraining factor in growth and in the hydrolysis of cellulose for biofuel production.

Modeling gross primary production of an evergreen needleleaf forest using MODIS and climate data

Treesearch

Xiangming Xiao; Qingyuan Zhang; David Hollinger; John Aber; Berrien, III Moore

2005-01-01

Forest canopies are composed of photosynthetically active vegetation (PAV, chloroplasts) and nonphotosynthetic vegetation (NPV, e.g., cell wall, vein, branch). The fraction of photosynthetically active radiation (PAR) absorbed by the canopy (FAPAR) should be partitioned into FAPARPAV and FAPARNPV. Gross primary production (...

Particle Trajectories in Rotating Wall Cell Culture Devices

NASA Technical Reports Server (NTRS)

Ramachandran N.; Downey, J. P.

1999-01-01

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

Functional characterization of a tomato COBRA-like gene functioning in fruit development and ripening

PubMed Central

2012-01-01

Background Extensive studies have demonstrated that the COBRA gene is critical for biosynthesis of cell wall constituents comprising structural tissues of roots, stalks, leaves and other vegetative organs, however, its role in fruit development and ripening remains largely unknown. Results We identified a tomato gene (SlCOBRA-like) homologous to Arabidopsis COBRA, and determined its role in fleshy fruit biology. The SlCOBRA-like gene is highly expressed in vegetative organs and in early fruit development, but its expression in fruit declines dramatically during ripening stages, implying a primary role in early fruit development. Fruit-specific suppression of SlCOBRA-like resulted in impaired cell wall integrity and up-regulation of genes encoding proteins involved in cell wall degradation during early fruit development. In contrast, fruit-specific overexpression of SlCOBRA-like resulted in increased wall thickness of fruit epidermal cells, more collenchymatous cells beneath the epidermis, elevated levels of cellulose and reduced pectin solubilization in the pericarp cells of red ripe fruits. Moreover, transgenic tomato fruits overexpressing SlCOBRA-like exhibited desirable early development phenotypes including enhanced firmness and a prolonged shelf life. Conclusions Our results suggest that SlCOBRA-like plays an important role in fruit cell wall architecture and provides a potential genetic tool for extending the shelf life of tomato and potentially additional fruits. PMID:23140186

Building bridges: formin1 of Arabidopsis forms a connection between the cell wall and the actin cytoskeleton.

PubMed

Martinière, Alexandre; Gayral, Philippe; Hawes, Chris; Runions, John

2011-04-01

Actin microfilament (MF) organization and remodelling is critical to cell function. The formin family of actin binding proteins are involved in nucleating MFs in Arabidopsis thaliana. They all contain formin homology domains in the intracellular, C-terminal half of the protein that interacts with MFs. Formins in class I are usually targeted to the plasma membrane and this is true of Formin1 (AtFH1) of A. thaliana. In this study, we have investigated the extracellular domain of AtFH1 and we demonstrate that AtFH1 forms a bridge from the actin cytoskeleton, across the plasma membrane and is anchored within the cell wall. AtFH1 has a large, extracellular domain that is maintained by purifying selection and that contains four conserved regions, one of which is responsible for immobilising the protein. Protein anchoring within the cell wall is reduced in constructs that express truncations of the extracellular domain and in experiments in protoplasts without primary cell walls. The 18 amino acid proline-rich extracellular domain that is responsible for AtFH1 anchoring has homology with cell-wall extensins. We also have shown that anchoring of AtFH1 in the cell wall promotes actin bundling within the cell and that overexpression of AtFH1 has an inhibitory effect on organelle actin-dependant dynamics. Thus, the AtFH1 bridge provides stable anchor points for the actin cytoskeleton and is probably a crucial component of the signalling response and actin-remodelling mechanisms. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

Dramatic performance of Clostridium thermocellum explained by its wide range of cellulase modalities.

PubMed

Xu, Qi; Resch, Michael G; Podkaminer, Kara; Yang, Shihui; Baker, John O; Donohoe, Bryon S; Wilson, Charlotte; Klingeman, Dawn M; Olson, Daniel G; Decker, Stephen R; Giannone, Richard J; Hettich, Robert L; Brown, Steven D; Lynd, Lee R; Bayer, Edward A; Himmel, Michael E; Bomble, Yannick J

2016-02-01

Clostridium thermocellum is the most efficient microorganism for solubilizing lignocellulosic biomass known to date. Its high cellulose digestion capability is attributed to efficient cellulases consisting of both a free-enzyme system and a tethered cellulosomal system wherein carbohydrate active enzymes (CAZymes) are organized by primary and secondary scaffoldin proteins to generate large protein complexes attached to the bacterial cell wall. This study demonstrates that C. thermocellum also uses a type of cellulosomal system not bound to the bacterial cell wall, called the "cell-free" cellulosomal system. The cell-free cellulosome complex can be seen as a "long range cellulosome" because it can diffuse away from the cell and degrade polysaccharide substrates remotely from the bacterial cell. The contribution of these two types of cellulosomal systems in C. thermocellum was elucidated by characterization of mutants with different combinations of scaffoldin gene deletions. The primary scaffoldin, CipA, was found to play the most important role in cellulose degradation by C. thermocellum, whereas the secondary scaffoldins have less important roles. Additionally, the distinct and efficient mode of action of the C. thermocellum exoproteome, wherein the cellulosomes splay or divide biomass particles, changes when either the primary or secondary scaffolds are removed, showing that the intact wild-type cellulosomal system is necessary for this essential mode of action. This new transcriptional and proteomic evidence shows that a functional primary scaffoldin plays a more important role compared to secondary scaffoldins in the proper regulation of CAZyme genes, cellodextrin transport, and other cellular functions.

Arabidopsis thalianafrom Polarization Transfer Solid-State NMR

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, Paul B; Wang, Tuo; Park, Yong Bum

2014-07-23

Polysaccharide-rich plant cell walls are hydrated under functional conditions, but the molecular interactions between water and polysaccharides in the wall have not been investigated. In this work, we employ polarization transfer solid-state NMR techniques to study the hydration of primary-wall polysaccharides of the model plant, Arabidopsis thaliana. By transferring water 1H polarization to polysaccharides through distance- and mobility-dependent 1H–1H dipolar couplings and detecting it through polysaccharide 13C signals, we obtain information about water proximity to cellulose, hemicellulose, and pectins as well as water mobility. Both intact and partially extracted cell wall samples are studied. Our results show that water–pectin polarizationmore » transfer is much faster than water–cellulose polarization transfer in all samples, but the extent of extraction has a profound impact on the water–polysaccharide spin diffusion. Removal of calcium ions and the consequent extraction of homogalacturonan (HG) significantly slowed down spin diffusion, while further extraction of matrix polysaccharides restored the spin diffusion rate. These trends are observed in cell walls with similar water content, thus they reflect inherent differences in the mobility and spatial distribution of water. Combined with quantitative analysis of the polysaccharide contents, our results indicate that calcium ions and HG gelation increase the amount of bound water, which facilitates spin diffusion, while calcium removal disrupts the gel and gives rise to highly dynamic water, which slows down spin diffusion. The recovery of spin diffusion rates after more extensive extraction is attributed to increased water-exposed surface areas of the polysaccharides. Water–pectin spin diffusion precedes water–cellulose spin diffusion, lending support to the single-network model of plant primary walls in which a substantial fraction of the cellulose surface is surrounded by pectins.« less

Alteration of Oriented Deposition of Cellulose Microfibrils by Mutation of a Katanin-Like Microtubule-Severing Protein

PubMed Central

Burk, David H.; Ye, Zheng-Hua

2002-01-01

It has long been hypothesized that cortical microtubules (MTs) control the orientation of cellulose microfibril deposition, but no mutants with alterations of MT orientation have been shown to affect this process. We have shown previously that in Arabidopsis, the fra2 mutation causes aberrant cortical MT orientation and reduced cell elongation, and the gene responsible for the fra2 mutation encodes a katanin-like protein. In this study, using field emission scanning electron microscopy, we found that the fra2 mutation altered the normal orientation of cellulose microfibrils in walls of expanding cells. Although cellulose microfibrils in walls of wild-type cells were oriented transversely along the elongation axis, cellulose microfibrils in walls of fra2 cells often formed bands and ran in different directions. The fra2 mutation also caused aberrant deposition of cellulose microfibrils in secondary walls of fiber cells. The aberrant orientation of cellulose microfibrils was shown to be correlated with disorganized cortical MTs in several cell types examined. In addition, the thickness of both primary and secondary cell walls was reduced significantly in the fra2 mutant. These results indicate that the katanin-like protein is essential for oriented cellulose microfibril deposition and normal cell wall biosynthesis. We further demonstrated that the Arabidopsis katanin-like protein possessed MT-severing activity in vitro; thus, it is an ortholog of animal katanin. We propose that the aberrant MT orientation caused by the mutation of katanin results in the distorted deposition of cellulose microfibrils, which in turn leads to a defect in cell elongation. These findings strongly support the hypothesis that cortical MTs regulate the oriented deposition of cellulose microfibrils that determines the direction of cell elongation. PMID:12215512

Alteration of oriented deposition of cellulose microfibrils by mutation of a katanin-like microtubule-severing protein.

PubMed

Burk, David H; Ye, Zheng-Hua

2002-09-01

It has long been hypothesized that cortical microtubules (MTs) control the orientation of cellulose microfibril deposition, but no mutants with alterations of MT orientation have been shown to affect this process. We have shown previously that in Arabidopsis, the fra2 mutation causes aberrant cortical MT orientation and reduced cell elongation, and the gene responsible for the fra2 mutation encodes a katanin-like protein. In this study, using field emission scanning electron microscopy, we found that the fra2 mutation altered the normal orientation of cellulose microfibrils in walls of expanding cells. Although cellulose microfibrils in walls of wild-type cells were oriented transversely along the elongation axis, cellulose microfibrils in walls of fra2 cells often formed bands and ran in different directions. The fra2 mutation also caused aberrant deposition of cellulose microfibrils in secondary walls of fiber cells. The aberrant orientation of cellulose microfibrils was shown to be correlated with disorganized cortical MTs in several cell types examined. In addition, the thickness of both primary and secondary cell walls was reduced significantly in the fra2 mutant. These results indicate that the katanin-like protein is essential for oriented cellulose microfibril deposition and normal cell wall biosynthesis. We further demonstrated that the Arabidopsis katanin-like protein possessed MT-severing activity in vitro; thus, it is an ortholog of animal katanin. We propose that the aberrant MT orientation caused by the mutation of katanin results in the distorted deposition of cellulose microfibrils, which in turn leads to a defect in cell elongation. These findings strongly support the hypothesis that cortical MTs regulate the oriented deposition of cellulose microfibrils that determines the direction of cell elongation.

A comparative genome analysis of PME and PMEI families reveals the evolution of pectin metabolism in plant cell walls.

PubMed

Wang, Maojun; Yuan, Daojun; Gao, Wenhui; Li, Yang; Tan, Jiafu; Zhang, Xianlong

2013-01-01

Pectins are fundamental polysaccharides in the plant primary cell wall. Pectins are synthesized and secreted to cell walls as highly methyl-esterified polymers and then demethyl-esterified by pectin methylesterases (PMEs), which are spatially regulated by pectin methylesterase inhibitors (PMEIs). Although PME and PMEI genes are pivotal in plant cell wall formation, few studies have focused on the evolutionary patterns of the PME and PMEI gene families. In this study, the gene origin, evolution, and expression diversity of these two families were systematically analyzed using 11 representative species, including algae, bryophytes, lycophytes and flowering land plants. The results show that 1) for the two subfamilies (PME and proPME) of PME, the origin of the PME subfamily is consistent with the appearance of pectins in early charophyte cell walls, 2) Whole genome duplication (WGD) and tandem duplication contribute to the expansion of proPME and PMEI families in land plants, 3) Evidence of selection pressure shows that the proPME and PMEI families have rapidly evolved, particularly the PMEI family in vascular plants, and 4) Comparative expression profile analysis of the two families indicates that the eudicot Arabidopsis and monocot rice have different expression patterns. In addition, the gene structure and sequence analyses show that the origin of the PMEI domain may be derived from the neofunctionalization of the pro domain after WGD. This study will advance the evolutionary understanding of the PME and PMEI families and plant cell wall development.

S-nitrosoglutathione promotes cell wall remodelling, alters the transcriptional profile and induces root hair formation in the hairless root hair defective 6 (rhd6) mutant of Arabidopsis thaliana.

PubMed

Moro, Camila Fernandes; Gaspar, Marilia; da Silva, Felipe Rodrigues; Pattathil, Sivakumar; Hahn, Michael G; Salgado, Ione; Braga, Marcia Regina

2017-03-01

Nitric oxide (NO) exerts pleiotropic effects on plant development; however, its involvement in cell wall modification during root hair formation (RHF) has not yet been addressed. Here, mutants of Arabidopsis thaliana with altered root hair phenotypes were used to assess the involvement of S-nitrosoglutathione (GSNO), the primary NO source, in cell wall dynamics and gene expression in roots induced to form hairs. GSNO and auxin restored the root hair phenotype of the hairless root hair defective 6 (rhd6) mutant. A positive correlation was observed between increased NO production and RHF induced by auxin in rhd6 and transparent testa glabra (ttg) mutants. Deposition of an epitope within rhamnogalacturonan-I recognized by the CCRC-M2 antibody was delayed in root hair cells (trichoblasts) compared with nonhair cells (atrichoblasts). GSNO, but not auxin, restored the wild-type root glycome and transcriptome profiles in rhd6, modulating the expression of a large number of genes related to cell wall composition and metabolism, as well as those encoding ribosomal proteins, DNA and histone-modifying enzymes and proteins involved in post-translational modification. Our results demonstrate that NO plays a key role in cell wall remodelling in trichoblasts and suggest that it also participates in chromatin modification in root cells of A. thaliana. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

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

PubMed

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

2008-01-01

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

A novel membrane anchor for FtsZ is linked to cell wall hydrolysis in Caulobacter crescentus.

PubMed

Meier, Elizabeth L; Razavi, Shiva; Inoue, Takanari; Goley, Erin D

2016-07-01

In most bacteria, the tubulin-like GTPase FtsZ forms an annulus at midcell (the Z-ring) which recruits the division machinery and regulates cell wall remodeling. Although both activities require membrane attachment of FtsZ, few membrane anchors have been characterized. FtsA is considered to be the primary membrane tether for FtsZ in bacteria, however in Caulobacter crescentus, FtsA arrives at midcell after stable Z-ring assembly and early FtsZ-directed cell wall synthesis. We hypothesized that additional proteins tether FtsZ to the membrane and demonstrate that in C. crescentus, FzlC is one such membrane anchor. FzlC associates with membranes directly in vivo and in vitro and recruits FtsZ to membranes in vitro. As for most known membrane anchors, the C-terminal peptide of FtsZ is required for its recruitment to membranes by FzlC in vitro and midcell recruitment of FzlC in cells. In vivo, overproduction of FzlC causes cytokinesis defects whereas deletion of fzlC causes synthetic defects with dipM, ftsE and amiC mutants, implicating FzlC in cell wall hydrolysis. Our characterization of FzlC as a novel membrane anchor for FtsZ expands our understanding of FtsZ regulators and establishes a role for membrane-anchored FtsZ in the regulation of cell wall hydrolysis. © 2016 John Wiley & Sons Ltd.

Validation test of 125 Ah advanced design IPV nickel-hydrogen flight cells

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1993-01-01

An update of validation test results confirming the advanced design nickel-hydrogen cell is presented. An advanced 125 Ah individual pressure vessel (IPV) nickel-hydrogen cell was designed. The primary function of the advanced cell is to store and deliver energy for long-term, Low-Earth-Orbit (LEO) spacecraft missions. The new features of this design, which are not incorporated in state-of-the-art design cells, are: (1) use of 26 percent rather than 31 percent potassium hydroxide (KOH) electrolyte; (2) use of a patented catalyzed wall wick; (3) use of serrated-edge separators to facilitate gaseous oxygen and hydrogen flow within the cell, while still maintaining physical contact with the wall wick for electrolyte management; and (4) use of a floating rather than a fixed stack (state-of-the-art) to accommodate nickel electrode expansion due to charge/discharge cycling. The significant improvements resulting from these innovations are extended cycle life; enhanced thermal, electrolyte, and oxygen management; and accommodation of nickel electrode expansion. Six 125 Ah flight cells based on this design were fabricated by Eagle-Picher. Three of the cells contain all of the advanced features (test cells) and three are the same as the test cells except they do not have catalyst on the wall wick (control cells). All six cells are in the process of being evaluated in a LEO cycle life test at the Naval Weapons Support Center, Crane, IN, under a NASA Lewis Research Center contract. The catalyzed wall wick cells have been cycled for over 19000 cycles with no cell failures in the continuing test. Two of the noncatalyzed wall wick cells failed (cycles 9588 and 13,900).

Heat stress causes alterations in the cell-wall polymers and anatomy of coffee leaves (Coffea arabica L.).

PubMed

Lima, Rogério Barbosa; dos Santos, Tiago Benedito; Vieira, Luiz Gonzaga Esteves; Ferrarese, Maria de Lourdes Lúcio; Ferrarese-Filho, Osvaldo; Donatti, Lucélia; Boeger, Maria Regina Torres; Petkowicz, Carmen Lúcia de Oliveira

2013-03-01

Coffee plants were subjected to heat stress (37 °C) and compared with control plants (24 °C). Cell wall polysaccharides were extracted using water (W), EDTA (E) and 4M NaOH (H30 and H70). In addition, monolignols were analyzed, and the leaves were observed by microscopy. Plants under heat stress accumulated higher contents of arabinose and galactose in fraction W. Xylose contents were observed to decrease in H30 fractions after the heat stress, whereas galactose and uronic acid increased. H70 fractions from plants exposed to heat stress showed increased xylose contents, whereas the contents of arabinose and glucose decreased. Differences in the molar-mass profiles of polysaccharides were also observed. The primary monolignol contents increased after the heat stress. Structural alterations in palisade cells and ultrastructural damage in chloroplasts were also observed. Our results demonstrate that the chemical profile of coffee cell-wall polymers and structural cell anatomy change under heat stress. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of microgravity environment on cell wall regeneration, cell divisions, growth, and differentiation of plants from protoplasts (7-IML-1)

NASA Technical Reports Server (NTRS)

Rasmussen, Ole

1992-01-01

The primary goal of this project is to investigate if microgravity has any influence on growth and differentiation of protoplasts. Formation of new cell walls on rapeseed protoplasts takes place within the first 24 hours after isolation. Cell division can be observed after 2-4 days and formation of cell aggregates after 5-7 days. Therefore, it is possible during the 7 day IML-1 Mission to investigate if cell wall formation, cell division, and cell differentiation are influenced by microgravity. Protoplasts of rapeseeds and carrot will be prepared shortly before launch and injected into 0.6 ml polyethylene bags. Eight bags are placed in an aluminum block inside the ESA Type 1 container. The containers are placed at 4 C in PTCU's and transferred to orbiter mid-deck. At 4 C all cell processes are slowed down, including cell wall formation. Latest access to the shuttle will be 12 hours before launch. In orbit the containers will be transferred from the PTC box to the 22 C Biorack incubator. The installation of a 1 g centrifuge in Biorack will make it possible to distinguish between effects of near weightlessness and effects caused by cosmic radiation and other space flight factors including vibrations. Parallel control experiments will be carried out on the ground. Other aspects of the experiment are discussed.

XET Activity is Found Near Sites of Growth and Cell Elongation in Bryophytes and Some Green Algae: New Insights into the Evolution of Primary Cell Wall Elongation

PubMed Central

Van Sandt, Vicky S. T.; Stieperaere, Herman; Guisez, Yves; Verbelen, Jean-Pierre; Vissenberg, Kris

2007-01-01

Background and Aims In angiosperms xyloglucan endotransglucosylase (XET)/hydrolase (XTH) is involved in reorganization of the cell wall during growth and development. The location of oligo-xyloglucan transglucosylation activity and the presence of XTH expressed sequence tags (ESTs) in the earliest diverging extant plants, i.e. in bryophytes and algae, down to the Phaeophyta was examined. The results provide information on the presence of an XET growth mechanism in bryophytes and algae and contribute to the understanding of the evolution of cell wall elongation in general. Methods Representatives of the different plant lineages were pressed onto an XET test paper and assayed. XET or XET-related activity was visualized as the incorporation of fluorescent signal. The Physcomitrella genome database was screened for the presence of XTHs. In addition, using the 3′ RACE technique searches were made for the presence of possible XTH ESTs in the Charophyta. Key Results XET activity was found in the three major divisions of bryophytes at sites corresponding to growing regions. In the Physcomitrella genome two putative XTH-encoding cDNA sequences were identified that contain all domains crucial for XET activity. Furthermore, XET activity was located at the sites of growth in Chara (Charophyta) and Ulva (Chlorophyta) and a putative XTH ancestral enzyme in Chara was identified. No XET activity was identified in the Rhodophyta or Phaeophyta. Conclusions XET activity was shown to be present in all major groups of green plants. These data suggest that an XET-related growth mechanism originated before the evolutionary divergence of the Chlorobionta and open new insights in the evolution of the mechanisms of primary cell wall expansion. PMID:17098750

Texture of cellulose microfibrils of root hair cell walls of Arabidopsis thaliana, Medicago truncatula, and Vicia sativa.

PubMed

Akkerman, M; Franssen-Verheijen, M A W; Immerzeel, P; Hollander, L D E N; Schel, J H N; Emons, A M C

2012-07-01

Cellulose is the most abundant biopolymer on earth, and has qualities that make it suitable for biofuel. There are new tools for the visualisation of the cellulose synthase complexes in living cells, but those do not show their product, the cellulose microfibrils (CMFs). In this study we report the characteristics of cell wall textures, i.e. the architectures of the CMFs in the wall, of root hairs of Arabidopsis thaliana, Medicago truncatula and Vicia sativa and compare the different techniques we used to study them. Root hairs of these species have a random primary cell wall deposited at the root hair tip, which covers the outside of the growing and fully grown hair. The secondary wall starts between 10 (Arabidopsis) and 40 (Vicia) μm from the hair tip and the CMFs make a small angle, Z as well as S direction, with the long axis of the root hair. CMFs are 3-4 nm wide in thin sections, indicating that single cellulose synthase complexes make them. Thin sections after extraction of cell wall matrix, leaving only the CMFs, reveal the type of wall texture and the orientation and width of CMFs, but CMF density within a lamella cannot be quantified, and CMF length is always underestimated by this technique. Field emission scanning electron microscopy and surface preparations for transmission electron microscopy reveal the type of wall texture and the orientation of individual CMFs. Only when the orientation of CMFs in subsequent deposited lamellae is different, their density per lamella can be determined. It is impossible to measure CMF length with any of the EM techniques. © 2012 The Authors Journal of Microscopy © 2012 Royal Microscopical Society.

Downregulation of a UDP-Arabinomutase Gene in Switchgrass (Panicum virgatum L.) Results in Increased Cell Wall Lignin While Reducing Arabinose-Glycans

DOE PAGES

Willis, Jonathan D.; Smith, James A.; Mazarei, Mitra; ...

2016-10-26

Switchgrass (Panicum virgatum L.) is a C 4 perennial prairie grass and a dedicated feedstock for lignocellulosic biofuels. Saccharification and biofuel yields are inhibited by the plant cell wall's natural recalcitrance against enzymatic degradation. Plant hemicellulose polysaccharides such as arabinoxylans structurally support and cross-link other cell wall polymers. Grasses predominately have Type II cell walls that are abundant in arabinoxylan, which comprise nearly 25% of aboveground biomass. A primary component of arabinoxylan synthesis is uridine diphosphate (UDP) linked to arabinofuranose (Araf). A family of UDP-arabinopyranose mutase (UAM)/reversible glycosylated polypeptides catalyze the interconversion between UDP-arabinopyranose (UDP-Arap) and UDP-Araf. The expression ofmore » a switchgrass arabinoxylan biosynthesis pathway gene, PvUAM1, was decreased via RNAi to investigate its role in cell wall recalcitrance in the feedstock. PvUAM1 encodes a switchgrass homolog of UDP-arabinose mutase, which converts UDP-Arap to UDP-Araf. Southern blot analysis revealed each transgenic line contained between one to at least seven T-DNA insertions, resulting in some cases, a 95% reduction of native PvUAM1 transcript in stem internodes. Transgenic plants had increased pigmentation in vascular tissues at nodes, but were otherwise similar in morphology to the non-transgenic control. Cell wall-associated arabinose was decreased in leaves and stems by over 50%, but there was an increase in cellulose. In addition, there was a commensurate change in arabinose side chain extension. Cell wall lignin composition was altered with a concurrent increase in lignin content and transcript abundance of lignin biosynthetic genes in mature tillers. Enzymatic saccharification efficiency was unchanged in the transgenic plants relative to the control. Plants with attenuated PvUAM1 transcript had increased cellulose and lignin in cell walls. A decrease in cell wall-associated arabinose was expected, which was likely caused by fewer Araf residues in the arabinoxylan. The decrease in arabinoxylan may cause a compensation response to maintain cell wall integrity by increasing cellulose and lignin biosynthesis. In cases in which increased lignin is desired, e.g., feedstocks for carbon fiber production, downregulated UAM1 coupled with altered expression of other arabinoxylan biosynthesis genes might result in even higher production of lignin in biomass.« less

Downregulation of a UDP-Arabinomutase Gene in Switchgrass (Panicum virgatum L.) Results in Increased Cell Wall Lignin While Reducing Arabinose-Glycans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Willis, Jonathan D.; Smith, James A.; Mazarei, Mitra

Switchgrass (Panicum virgatum L.) is a C 4 perennial prairie grass and a dedicated feedstock for lignocellulosic biofuels. Saccharification and biofuel yields are inhibited by the plant cell wall's natural recalcitrance against enzymatic degradation. Plant hemicellulose polysaccharides such as arabinoxylans structurally support and cross-link other cell wall polymers. Grasses predominately have Type II cell walls that are abundant in arabinoxylan, which comprise nearly 25% of aboveground biomass. A primary component of arabinoxylan synthesis is uridine diphosphate (UDP) linked to arabinofuranose (Araf). A family of UDP-arabinopyranose mutase (UAM)/reversible glycosylated polypeptides catalyze the interconversion between UDP-arabinopyranose (UDP-Arap) and UDP-Araf. The expression ofmore » a switchgrass arabinoxylan biosynthesis pathway gene, PvUAM1, was decreased via RNAi to investigate its role in cell wall recalcitrance in the feedstock. PvUAM1 encodes a switchgrass homolog of UDP-arabinose mutase, which converts UDP-Arap to UDP-Araf. Southern blot analysis revealed each transgenic line contained between one to at least seven T-DNA insertions, resulting in some cases, a 95% reduction of native PvUAM1 transcript in stem internodes. Transgenic plants had increased pigmentation in vascular tissues at nodes, but were otherwise similar in morphology to the non-transgenic control. Cell wall-associated arabinose was decreased in leaves and stems by over 50%, but there was an increase in cellulose. In addition, there was a commensurate change in arabinose side chain extension. Cell wall lignin composition was altered with a concurrent increase in lignin content and transcript abundance of lignin biosynthetic genes in mature tillers. Enzymatic saccharification efficiency was unchanged in the transgenic plants relative to the control. Plants with attenuated PvUAM1 transcript had increased cellulose and lignin in cell walls. A decrease in cell wall-associated arabinose was expected, which was likely caused by fewer Araf residues in the arabinoxylan. The decrease in arabinoxylan may cause a compensation response to maintain cell wall integrity by increasing cellulose and lignin biosynthesis. In cases in which increased lignin is desired, e.g., feedstocks for carbon fiber production, downregulated UAM1 coupled with altered expression of other arabinoxylan biosynthesis genes might result in even higher production of lignin in biomass.« less

Primary iris stromal cyst with rapid growth.

PubMed

Xiao, Yang; Wang, Yu-Hong; Niu, Gai-Ling; Gao, Min

2009-11-01

To describe the clinical features and the surgical management of primary iris stromal cyst with rapid growth. A 14-year-old Chinese-Mongolian girl was referred to us with a 1-month history of obstructed vision and photophobia. On an examination, a semitransparent cyst with a densely pigmented posterior wall was revealed in the anterior chamber of the left eye. The information regarding the location and extent of the cyst was further analyzed by anterior segment optical coherence tomography and ultrasound biomicroscopy. It arose within the iris stroma, measuring 7.52 x 3.60 mm. Blood vessels on the surface of the lesion were revealed by iris angiography. There was no history of amniocentesis, birth trauma, antecedent ocular injury, or maternal illness during gestation. The diagnosis of primary iris stromal cyst was made. A combination of needle aspiration, piecemeal resection of cyst wall, cryotherapy, and argon laser photocoagulation with overlapped spots was used. Histopathology of the cyst wall revealed nonkeratinized, multilayered, stratified squamous epithelium with clusters of goblet cells. Complete resolution of the cyst was successfully achieved. The visual acuity improved to 20/25 from counting fingers. At 6 months of follow-up, there was no recurrence. Complete eradication and devitalization of any remaining epithelial cells are the key factors for preventing recurrence and diffuse epithelialization of the anterior chamber.

Dramatic performance of Clostridium thermocellum explained by its wide range of cellulase modalities

DOE PAGES

Xu, Qi; Resch, Michael G.; Podkaminer, Kara; ...

2016-02-05

Clostridium thermocellum is the most efficient microorganism for solubilizing lignocellulosic biomass known to date. Its high cellulose digestion capability is attributed to efficient cellulases consisting of both a free-enzyme system and a tethered cellulosomal system wherein carbohydrate active enzymes (CAZymes) are organized by primary and secondary scaffoldin proteins to generate large protein complexes attached to the bacterial cell wall. This study demonstrates that C. thermocellum also uses a type of cellulosomal system not bound to the bacterial cell wall, called the “cell-free” cellulosomal system. The cell-free cellulosome complex can be seen as a “long range cellulosome” because it can diffusemore » away from the cell and degrade polysaccharide substrates remotely from the bacterial cell. The contribution of these two types of cellulosomal systems in C. thermocellum was elucidated by characterization of mutants with different combinations of scaffoldin gene deletions. The primary scaffoldin, CipA, was found to play the most important role in cellulose degradation by C. thermocellum, whereas the secondary scaffoldins have less important roles. Additionally, the distinct and efficient mode of action of the C. thermocellum exoproteome, wherein the cellulosomes splay or divide biomass particles, changes when either the primary or secondary scaffolds are removed, showing that the intact wild-type cellulosomal system is necessary for this essential mode of action. As a result, this new transcriptional and proteomic evidence shows that a functional primary scaffoldin plays a more important role compared to secondary scaffoldins in the proper regulation of CAZyme genes, cellodextrin transport, and other cellular functions.« less

Dramatic performance of Clostridium thermocellum explained by its wide range of cellulase modalities

PubMed Central

Xu, Qi; Resch, Michael G.; Podkaminer, Kara; Yang, Shihui; Baker, John O.; Donohoe, Bryon S.; Wilson, Charlotte; Klingeman, Dawn M.; Olson, Daniel G.; Decker, Stephen R.; Giannone, Richard J.; Hettich, Robert L.; Brown, Steven D.; Lynd, Lee R.; Bayer, Edward A.; Himmel, Michael E.; Bomble, Yannick J.

2016-01-01

Clostridium thermocellum is the most efficient microorganism for solubilizing lignocellulosic biomass known to date. Its high cellulose digestion capability is attributed to efficient cellulases consisting of both a free-enzyme system and a tethered cellulosomal system wherein carbohydrate active enzymes (CAZymes) are organized by primary and secondary scaffoldin proteins to generate large protein complexes attached to the bacterial cell wall. This study demonstrates that C. thermocellum also uses a type of cellulosomal system not bound to the bacterial cell wall, called the “cell-free” cellulosomal system. The cell-free cellulosome complex can be seen as a “long range cellulosome” because it can diffuse away from the cell and degrade polysaccharide substrates remotely from the bacterial cell. The contribution of these two types of cellulosomal systems in C. thermocellum was elucidated by characterization of mutants with different combinations of scaffoldin gene deletions. The primary scaffoldin, CipA, was found to play the most important role in cellulose degradation by C. thermocellum, whereas the secondary scaffoldins have less important roles. Additionally, the distinct and efficient mode of action of the C. thermocellum exoproteome, wherein the cellulosomes splay or divide biomass particles, changes when either the primary or secondary scaffolds are removed, showing that the intact wild-type cellulosomal system is necessary for this essential mode of action. This new transcriptional and proteomic evidence shows that a functional primary scaffoldin plays a more important role compared to secondary scaffoldins in the proper regulation of CAZyme genes, cellodextrin transport, and other cellular functions. PMID:26989779

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mort, Andrew

At the beginning of this project we hypothesized that pectin, which is a major polysaccharide in primary plant cell walls, is composed of various distinct structural regions covalently linked together into a high molecular weight complex polymer. We also hypothesized that a considerable portion of xyloglucan, the major hemicellulose in most primary cell walls, is linked to the pectin. Our goal was to determine if these interconnections exist and to characterize the exact nature of the interactions. It seems imperative that we have a complete knowledge of the structure of pectin to be able to propose realistic models of cellmore » walls. There is a lot of interest in the biosynthesis of pectin. I do not think it will be possible to completely understand the biosynthesis of pectin without knowing the structure of pectin and thus the sequence of reactions needed to put each sugar or ester in its correct position in the polymer. We made considerable progress in determining the detailed structure of pectin and within a year or so will be able to put forward a comprehensive model of it.« less

Optimal 3D culture of primary articular chondrocytes for use in the rotating wall vessel bioreactor.

PubMed

Mellor, Liliana F; Baker, Travis L; Brown, Raquel J; Catlin, Lindsey W; Oxford, Julia Thom

2014-08-01

Reliable culturing methods for primary articular chondrocytes are essential to study the effects of loading and unloading on joint tissue at the cellular level. Due to the limited proliferation capacity of primary chondrocytes and their tendency to dedifferentiate in conventional culture conditions, long-term culturing conditions of primary chondrocytes can be challenging. The goal of this study was to develop a suspension culturing technique that not only would retain the cellular morphology, but also maintain the gene expression characteristics of primary articular chondrocytes. Three-dimensional culturing methods were compared and optimized for primary articular chondrocytes in the rotating wall vessel bioreactor, which changes the mechanical culture conditions to provide a form of suspension culture optimized for low shear and turbulence. We performed gene expression analysis and morphological characterization of cells cultured in alginate beads, Cytopore-2 microcarriers, primary monolayer culture, and passaged monolayer cultures using reverse transcription-PCR and laser scanning confocal microscopy. Primary chondrocytes grown on Cytopore-2 microcarriers maintained the phenotypical morphology and gene expression pattern observed in primary bovine articular chondrocytes, and retained these characteristics for up to 9 d. Our results provide a novel and alternative culturing technique for primary chondrocytes suitable for studies that require suspension such as those using the rotating wall vessel bioreactor. In addition, we provide an alternative culturing technique for primary chondrocytes that can impact future mechanistic studies of osteoarthritis progression, treatments for cartilage damage and repair, and cartilage tissue engineering.

Plant Fibre: Molecular Structure and Biomechanical Properties, of a Complex Living Material, Influencing Its Deconstruction towards a Biobased Composite

PubMed Central

Sorieul, Mathias; Dickson, Alan; Hill, Stefan J.; Pearson, Hamish

2016-01-01

Plant cell walls form an organic complex composite material that fulfils various functions. The hierarchical structure of this material is generated from the integration of its elementary components. This review provides an overview of wood as a composite material followed by its deconstruction into fibres that can then be incorporated into biobased composites. Firstly, the fibres are defined, and their various origins are discussed. Then, the organisation of cell walls and their components are described. The emphasis is on the molecular interactions of the cellulose microfibrils, lignin and hemicelluloses in planta. Hemicelluloses of diverse species and cell walls are described. Details of their organisation in the primary cell wall are provided, as understanding of the role of hemicellulose has recently evolved and is likely to affect our perception and future study of their secondary cell wall homologs. The importance of the presence of water on wood mechanical properties is also discussed. These sections provide the basis for understanding the molecular arrangements and interactions of the components and how they influence changes in fibre properties once isolated. A range of pulping processes can be used to individualise wood fibres, but these can cause damage to the fibres. Therefore, issues relating to fibre production are discussed along with the dispersion of wood fibres during extrusion. The final section explores various ways to improve fibres obtained from wood. PMID:28773739

Plant Fibre: Molecular Structure and Biomechanical Properties, of a Complex Living Material, Influencing Its Deconstruction towards a Biobased Composite.

PubMed

Sorieul, Mathias; Dickson, Alan; Hill, Stefan J; Pearson, Hamish

2016-07-26

Plant cell walls form an organic complex composite material that fulfils various functions. The hierarchical structure of this material is generated from the integration of its elementary components. This review provides an overview of wood as a composite material followed by its deconstruction into fibres that can then be incorporated into biobased composites. Firstly, the fibres are defined, and their various origins are discussed. Then, the organisation of cell walls and their components are described. The emphasis is on the molecular interactions of the cellulose microfibrils, lignin and hemicelluloses in planta . Hemicelluloses of diverse species and cell walls are described. Details of their organisation in the primary cell wall are provided, as understanding of the role of hemicellulose has recently evolved and is likely to affect our perception and future study of their secondary cell wall homologs. The importance of the presence of water on wood mechanical properties is also discussed. These sections provide the basis for understanding the molecular arrangements and interactions of the components and how they influence changes in fibre properties once isolated. A range of pulping processes can be used to individualise wood fibres, but these can cause damage to the fibres. Therefore, issues relating to fibre production are discussed along with the dispersion of wood fibres during extrusion. The final section explores various ways to improve fibres obtained from wood.

Progressive Inhibition by Water Deficit of Cell Wall Extensibility and Growth along the Elongation Zone of Maize Roots Is Related to Increased Lignin Metabolism and Progressive Stelar Accumulation of Wall Phenolics1

PubMed Central

Fan, Ling; Linker, Raphael; Gepstein, Shimon; Tanimoto, Eiichi; Yamamoto, Ryoichi; Neumann, Peter M.

2006-01-01

Water deficit caused by addition of polyethylene glycol 6000 at −0.5 MPa water potential to well-aerated nutrient solution for 48 h inhibited the elongation of maize (Zea mays) seedling primary roots. Segmental growth rates in the root elongation zone were maintained 0 to 3 mm behind the tip, but in comparison with well-watered control roots, progressive growth inhibition was initiated by water deficit as expanding cells crossed the region 3 to 9 mm behind the tip. The mechanical extensibility of the cell walls was also progressively inhibited. We investigated the possible involvement in root growth inhibition by water deficit of alterations in metabolism and accumulation of wall-linked phenolic substances. Water deficit increased expression in the root elongation zone of transcripts of two genes involved in lignin biosynthesis, cinnamoyl-CoA reductase 1 and 2, after only 1 h, i.e. before decreases in wall extensibility. Further increases in transcript expression and increased lignin staining were detected after 48 h. Progressive stress-induced increases in wall-linked phenolics at 3 to 6 and 6 to 9 mm behind the root tip were detected by comparing Fourier transform infrared spectra and UV-fluorescence images of isolated cell walls from water deficit and control roots. Increased UV fluorescence and lignin staining colocated to vascular tissues in the stele. Longitudinal bisection of the elongation zone resulted in inward curvature, suggesting that inner, stelar tissues were also rate limiting for root growth. We suggest that spatially localized changes in wall-phenolic metabolism are involved in the progressive inhibition of wall extensibility and root growth and may facilitate root acclimation to drying environments. PMID:16384904

N-acetylglucosamine-6-phosphate deacetylase (NagA) of Listeria monocytogenes EGD, an essential enzyme for the metabolism and recycling of amino sugars.

PubMed

Popowska, Magdalena; Osińska, Magdalena; Rzeczkowska, Magdalena

2012-04-01

The main aim of our study was to determine the physiological function of NagA enzyme in the Listeria monocytogenes cell. The primary structure of the murein of L. monocytogenes is very similar to that of Escherichia coli, the main differences being amidation of diaminopimelic acid and partial de-N-acetylation of glucosamine residues. NagA is needed for the deacetylation of N-acetyl-glucosamine-6 phosphate to glucosamine-6 phosphate and acetate. Analysis of the L. monocytogenes genome reveals the presence of two proteins with NagA domain, Lmo0956 and Lmo2108, which are cytoplasmic putative proteins. We introduced independent mutations into the structural genes for the two proteins. In-depth characterization of one of these mutants, MN1, deficient in protein Lmo0956 revealed strikingly altered cell morphology, strongly reduced cell wall murein content and decreased sensitivity to cell wall hydrolase, mutanolysin and peptide antibiotic, colistin. The gene products of operon 150, consisting of three genes: lmo0956, lmo0957, and lmo0958, are necessary for the cytosolic steps of the amino-sugar-recycling pathway. The cytoplasmic de-N-acetylase Lmo0956 of L. monocytogenes is required for cell wall peptidoglycan and teichoic acid biosynthesis and is also essential for bacterial cell growth, cell division, and sensitivity to cell wall hydrolases and peptide antibiotics.

Production and characterization of monoclonal antibodies to wall-localized peroxidases from corn seedlings

NASA Technical Reports Server (NTRS)

Kim, S. H.; Terry, M. E.; Hoops, P.; Dauwalder, M.; Roux, S. J.

1988-01-01

A library of 22 hybridomas, which make antibodies to soluble wall antigens from the coleoptiles and primary leaves of etiolated corn (Zea mays L.) seedlings, was raised and cloned three times by limit dilution to assure monoclonal growth and stability. Two of these hybridomas made immunoglobulin G antibodies, designated mWP3 and mWP19, which both effectively immunoprecipitated peroxidase activity from crude and partially purified preparations of wall peroxidases. Direct peroxidase-binding assays revealed that both antibodies bound enzymes with peroxidase activity. As judged by immunoblot analyses, mWP3 recognized a Mr 98,000 wall peroxidase with an isoelectric point near 4.2, and mWP19 recognized a Mr 58,000 wall peroxidase. Immunogold localization studies showed both peroxidases are predominately in cell walls.

Laccase Down-Regulation Causes Alterations in Phenolic Metabolism and Cell Wall Structure in Poplar1

PubMed Central

Ranocha, Philippe; Chabannes, Matthieu; Chamayou, Simon; Danoun, Saïda; Jauneau, Alain; Boudet, Alain-M.; Goffner, Deborah

2002-01-01

Laccases are encoded by multigene families in plants. Previously, we reported the cloning and characterization of five divergent laccase genes from poplar (Populus trichocarpa) xylem. To investigate the role of individual laccase genes in plant development, and more particularly in lignification, three independent populations of antisense poplar plants, lac3AS, lac90AS, and lac110AS with significantly reduced levels of laccase expression were generated. A repression of laccase gene expression had no effect on overall growth and development. Moreover, neither lignin content nor composition was significantly altered as a result of laccase suppression. However, one of the transgenic populations, lac3AS, exhibited a 2- to 3-fold increase in total soluble phenolic content. As indicated by toluidine blue staining, these phenolics preferentially accumulate in xylem ray parenchyma cells. In addition, light and electron microscopic observations of lac3AS stems indicated that lac3 gene suppression led to a dramatic alteration of xylem fiber cell walls. Individual fiber cells were severely deformed, exhibiting modifications in fluorescence emission at the primary wall/middle lamella region and frequent sites of cell wall detachment. Although a direct correlation between laccase gene expression and lignification could not be assigned, we show that the gene product of lac3 is essential for normal cell wall structure and integrity in xylem fibers. lac3AS plants provide a unique opportunity to explore laccase function in plants. PMID:12011346

In vitro versus in vivo cellulose microfibrils from plant primary wall synthases: structural differences.

PubMed

Lai-Kee-Him, Joséphine; Chanzy, Henri; Müller, Martin; Putaux, Jean-Luc; Imai, Tomoya; Bulone, Vincent

2002-10-04

Detergent extracts of microsomal fractions from suspension cultured cells of Rubus fruticosus (blackberry) were tested for their ability to synthesize in vitro sizable quantities of cellulose from UDP-glucose. Both Brij 58 and taurocholate were effective and yielded a substantial percentage of cellulose microfibrils together with (1-->3)-beta-d-glucan (callose). The taurocholate extracts, which did not require the addition of Mg(2+), were the most efficient, yielding roughly 20% of cellulose. This cellulose was characterized after callose removal by methylation analysis, electron microscopy, and electron and x-ray synchrotron diffractions; its resistance toward the acid Updegraff reagent was also evaluated. The cellulose microfibrils synthesized in vitro had the same diameter as the endogenous microfibrils isolated from primary cell walls. Both polymers diffracted as cellulose IV(I), a disorganized form of cellulose I. Besides these similarities, the in vitro microfibrils had a higher perfection and crystallinity as well as a better resistance toward the Updegraff reagent. These differences can be attributed to the mode of synthesis of the in vitro microfibrils that are able to grow independently in a neighbor-free environment, as opposed to the cellulose in the parent cell walls where new microfibrils have to interweave with the already laid polymers, with the result of a number of structural defects.

Transcript profiling by microarray and marker analysis of the short cotton (Gossypium hirsutum L.) fiber mutant Ligon lintless-1 (Li1).

PubMed

Gilbert, Matthew K; Turley, Rickie B; Kim, Hee Jin; Li, Ping; Thyssen, Gregory; Tang, Yuhong; Delhom, Christopher D; Naoumkina, Marina; Fang, David D

2013-06-17

Cotton fiber length is very important to the quality of textiles. Understanding the genetics and physiology of cotton fiber elongation can provide valuable tools to the cotton industry by targeting genes or other molecules responsible for fiber elongation. Ligon Lintless-1 (Li1) is a monogenic mutant in Upland cotton (Gossypium hirsutum) which exhibits an early cessation of fiber elongation resulting in very short fibers (< 6 mm) at maturity. This presents an excellent model system for studying the underlying molecular and cellular processes involved with cotton fiber elongation. Previous reports have characterized Li1 at early cell wall elongation and during later secondary cell wall synthesis, however there has been very limited analysis of the transition period between these developmental time points. Physical and morphological measurements of the Li1 mutant fibers were conducted, including measurement of the cellulose content during development. Affymetrix microarrays were used to analyze transcript profiles at the critical developmental time points of 3 days post anthesis (DPA), the late elongation stage of 12 DPA and the early secondary cell wall synthesis stage of 16 DPA. The results indicated severe disruption to key hormonal and other pathways related to fiber development, especially pertaining to the transition stage from elongation to secondary cell wall synthesis. Gene Ontology enrichment analysis identified several key pathways at the transition stage that exhibited altered regulation. Genes involved in ethylene biosynthesis and primary cell wall rearrangement were affected, and a primary cell wall-related cellulose synthase was transcriptionally repressed. Linkage mapping using a population of 2,553 F2 individuals identified SSR markers associated with the Li1 genetic locus on chromosome 22. Linkage mapping in combination with utilizing the diploid G. raimondii genome sequences permitted additional analysis of the region containing the Li1 gene. The early termination of fiber elongation in the Li1 mutant is likely controlled by an early upstream regulatory factor resulting in the altered regulation of hundreds of downstream genes. Several elongation-related genes that exhibited altered expression profiles in the Li1 mutant were identified. Molecular markers closely associated with the Li1 locus were developed. Results presented here will lay the foundation for further investigation of the genetic and molecular mechanisms of fiber elongation.

Comparison of four glycosyl residue composition methods for effectiveness in detecting sugars from cell walls of dicot and grass tissues.

PubMed

Biswal, Ajaya K; Tan, Li; Atmodjo, Melani A; DeMartini, Jaclyn; Gelineo-Albersheim, Ivana; Hunt, Kimberly; Black, Ian M; Mohanty, Sushree S; Ryno, David; Wyman, Charles E; Mohnen, Debra

2017-01-01

The effective use of plant biomass for biofuel and bioproduct production requires a comprehensive glycosyl residue composition analysis to understand the different cell wall polysaccharides present in the different biomass sources. Here we compared four methods side-by-side for their ability to measure the neutral and acidic sugar composition of cell walls from herbaceous, grass, and woody model plants and bioenergy feedstocks. Arabidopsis, Populus , rice, and switchgrass leaf cell walls, as well as cell walls from Populus wood, rice stems, and switchgrass tillers, were analyzed by (1) gas chromatography-mass spectrometry (GC-MS) of alditol acetates combined with a total uronic acid assay; (2) carbodiimide reduction of uronic acids followed by GC-MS of alditol acetates; (3) GC-MS of trimethylsilyl (TMS) derivatives; and (4) high-pressure, anion-exchange chromatography (HPAEC). All four methods gave comparable abundance ranking of the seven neutral sugars, and three of the methods were able to quantify unique acidic sugars. The TMS, HPAEC, and carbodiimide methods provided comparable quantitative results for the specific neutral and acidic sugar content of the biomass, with the TMS method providing slightly greater yield of specific acidic sugars and high total sugar yields. The alditol acetate method, while providing comparable information on the major neutral sugars, did not provide the requisite quantitative information on the specific acidic sugars in plant biomass. Thus, the alditol acetate method is the least informative of the four methods. This work provides a side-by-side comparison of the efficacy of four different established glycosyl residue composition analysis methods in the analysis of the glycosyl residue composition of cell walls from both dicot (Arabidopsis and Populus ) and grass (rice and switchgrass) species. Both primary wall-enriched leaf tissues and secondary wall-enriched wood/stem tissues were analyzed for mol% and mass yield of the non-cellulosic sugars. The TMS, HPAEC, and carbodiimide methods were shown to provide comparable quantitative data on the nine neutral and acidic sugars present in all plant cell walls.

Histology and cell wall biochemistry of stone cells in the physical defence of conifers against insects.

PubMed

Whitehill, Justin G A; Henderson, Hannah; Schuetz, Mathias; Skyba, Oleksandr; Yuen, Macaire Man Saint; King, John; Samuels, A Lacey; Mansfield, Shawn D; Bohlmann, Jörg

2016-08-01

Conifers possess an array of physical and chemical defences against stem-boring insects. Stone cells provide a physical defence associated with resistance against bark beetles and weevils. In Sitka spruce (Picea sitchensis), abundance of stone cells in the cortex of apical shoots is positively correlated with resistance to white pine weevil (Pissodes strobi). We identified histological, biochemical and molecular differences in the stone cell phenotype of weevil resistant (R) or susceptible (S) Sitka spruce genotypes. R trees displayed significantly higher quantities of cortical stone cells near the apical shoot node, the primary site for weevil feeding. Lignin, cellulose, xylan and mannan were the most abundant components of stone cell secondary walls, respectively. Lignin composition of stone cells isolated from R trees contained a higher percentage of G-lignin compared with S trees. Transcript profiling revealed higher transcript abundance in the R genotype of coumarate 3-hydroxylase, a key monolignol biosynthetic gene. Developing stone cells in current year apical shoots incorporated fluorescent-tagged monolignol into the secondary cell wall, while mature stone cells of previous year apical shoots did not. Stone cell development is an ephemeral process, and fortification of shoot tips in R trees is an effective strategy against insect feeding. © 2015 John Wiley & Sons Ltd.

Use of Chemical Fractionation and Proton Nuclear Magnetic Resonance to Probe the Physical Structure of the Primary Plant Cell Wall 1

PubMed Central

Taylor, Iain E. P.; Wallace, Julia C.; MacKay, Alex L.; Volke, Frank

1990-01-01

Proton magnetic resonance has been used to monitor the microscopic physical properties of etiolated hypocotyl cell walls from Phaseolus vulgaris L. at all stages in a series of chemical fractionations with ammonium oxalate and potassium hydroxide. Solid echo measurements indicate that 75% of the polymers in the intact cell wall, including the cellulose and most of the hemicelluloses, are arranged such that there is almost complete restraint of molecular motion. The chemical fractionations generally altered the physical structures of the remaining cell wall components. Digestion with 0.25% ammonium oxalate/oxalic acid solubilized the pectin and increased the mobility of the hemicellulose I component. Extraction with 4% potassium hydroxide removed the hemicellulose I component and loosened the hemicellulose II. Further extraction with 24% potassium hydroxide removed the hemicellulose II and loosened some of the cellulose. The cellulose crystallinity, as monitored by Jeener echo measurements decreased from 83% to 63% during these fractionations. We conclude that, while hemicellulose I is firmly attached to hemicellulose II, it is not in a closely packed structure. Hemicellulose II is strongly bound to cellulose and has a much more closely packed structure. PMID:16667683

High-resolution confocal imaging of wall ingrowth deposition in plant transfer cells: Semi-quantitative analysis of phloem parenchyma transfer cell development in leaf minor veins of Arabidopsis.

PubMed

Nguyen, Suong T T; McCurdy, David W

2015-04-23

Transfer cells (TCs) are trans-differentiated versions of existing cell types designed to facilitate enhanced membrane transport of nutrients at symplasmic/apoplasmic interfaces. This transport capacity is conferred by intricate wall ingrowths deposited secondarily on the inner face of the primary cell wall, hence promoting the potential trans-membrane flux of solutes and consequently assigning TCs as having key roles in plant growth and productivity. However, TCs are typically positioned deep within tissues and have been studied mostly by electron microscopy. Recent advances in fluorophore labelling of plant cell walls using a modified pseudo-Schiff-propidium iodide (mPS-PI) staining procedure in combination with high-resolution confocal microscopy have allowed visualization of cellular details of individual tissue layers in whole mounts, hence enabling study of tissue and cellular architecture without the need for tissue sectioning. Here we apply a simplified version of the mPS-PI procedure for confocal imaging of cellulose-enriched wall ingrowths in vascular TCs at the whole tissue level. The simplified mPS-PI staining procedure produced high-resolution three-dimensional images of individual cell types in vascular bundles and, importantly, wall ingrowths in phloem parenchyma (PP) TCs in minor veins of Arabidopsis leaves and companion cell TCs in pea. More efficient staining of tissues was obtained by replacing complex clearing procedures with a simple post-fixation bleaching step. We used this modified procedure to survey the presence of PP TCs in other tissues of Arabidopsis including cotyledons, cauline leaves and sepals. This high-resolution imaging enabled us to classify different stages of wall ingrowth development in Arabidopsis leaves, hence enabling semi-quantitative assessment of the extent of wall ingrowth deposition in PP TCs at the whole leaf level. Finally, we conducted a defoliation experiment as an example of using this approach to statistically analyze responses of PP TC development to leaf ablation. Use of a modified mPS-PI staining technique resulted in high-resolution confocal imaging of polarized wall ingrowth deposition in TCs. This technique can be used in place of conventional electron microscopy and opens new possibilities to study mechanisms determining polarized deposition of wall ingrowths and use reverse genetics to identify regulatory genes controlling TC trans-differentiation.

A synchronous increase in hydraulic conductive capacity and mechanical support in conifers with relatively uniform xylem structure.

PubMed

Jagels, Richard; Visscher, George E

2006-02-01

The dual function provided by longitudinal tracheids in conifers has led to a generally held trade-off concept that increasing wall thickness and/or volume of latewood tracheids improves mechanical support, while increasing cell diameter and/or volume of earlywood tracheids enhances conductive potential. Yet, some conifers have either uniform cell structure across the growth ring or, at most, a small amount of latewood. How do these trees accomplish the needs for increasing support and conduction with height growth? We examined Metasequoia glyptostroboides, a species that we previously demonstrated improves its mechanical properties with increasing age without a change in specific gravity or secondary wall microfibril angle. In this paper, we showed that lignin and extractive contents are not contributing factors, and through composite structure analysis, we eliminated a role for tracheid length. Using micromorphometric analysis, we demonstrated that as cell diameter increases, total primary wall decreases, secondary wall increases, and strength and conductive capacity increase with no change in specific gravity. Meta-analysis using other species of Cupressaceae, Podocarpaceae, and Araucariaceae provided strong corroborative evidence for this design strategy.

Primary events regulating stem growth at low water potentials.

PubMed

Nonami, H; Boyer, J S

1990-08-01

Cell enlargement is inhibited by inadequate water. As a first step toward understanding the mechanism, all the physical parameters affecting enlargement were monitored to identify those that changed first, particularly in coincidence with the inhibition. The osmotic potential, turgor, yield threshold turgor, growth-induced water potential, wall extensibility, and conductance to water were measured in the elongating region, and the water potential was measured in the xylem of stems of dark-grown soybean (Glycine max [L.] Merr.) seedlings. A stepdown in water potential was achieved around the roots by transplanting the seedlings to vermiculite of low water content, and each of the parameters was measured simultaneously in the same plants while intact or within a few minutes of being intact using a newly developed guillotine psychrometer. The gradient of decreasing water potential from the xylem to the enlarging cells (growth-induced water potential) was the first of the parameters to decrease to a growth-limiting level. The kinetics were the same as for the inhibition of growth. The decreased gradient was caused mostly by a decreased water potential of the xylem. This was followed after 5 to 10 hours by a similar decrease in cell wall extensibility and tissue conductance for water. Later, the growth-induced water potential recovered as a result of osmotic adjustment and a rise in the water potential of the xylem. Still later, moderate growth resumed at a rate apparently determined by the low wall extensibility and tissue conductance for water. The turgor did not change significantly during the experiment. These results indicate that the primary event during the growth inhibition was the change in the growth-induced water potential. Because the growth limitation subsequently shifted to the low wall extensibility and tissue conductance for water, the initial change in potential may have set in motion subsequent metabolic changes that altered the characteristics of the wall and cell membranes.

Primary Events Regulating Stem Growth at Low Water Potentials 1

PubMed Central

Nonami, Hiroshi; Boyer, John S.

1990-01-01

Cell enlargement is inhibited by inadequate water. As a first step toward understanding the mechanism, all the physical parameters affecting enlargement were monitored to identify those that changed first, particularly in coincidence with the inhibition. The osmotic potential, turgor, yield threshold turgor, growth-induced water potential, wall extensibility, and conductance to water were measured in the elongating region, and the water potential was measured in the xylem of stems of dark-grown soybean (Glycine max [L.] Merr.) seedlings. A stepdown in water potential was achieved around the roots by transplanting the seedlings to vermiculite of low water content, and each of the parameters was measured simultaneously in the same plants while intact or within a few minutes of being intact using a newly developed guillotine psychrometer. The gradient of decreasing water potential from the xylem to the enlarging cells (growth-induced water potential) was the first of the parameters to decrease to a growth-limiting level. The kinetics were the same as for the inhibition of growth. The decreased gradient was caused mostly by a decreased water potential of the xylem. This was followed after 5 to 10 hours by a similar decrease in cell wall extensibility and tissue conductance for water. Later, the growth-induced water potential recovered as a result of osmotic adjustment and a rise in the water potential of the xylem. Still later, moderate growth resumed at a rate apparently determined by the low wall extensibility and tissue conductance for water. The turgor did not change significantly during the experiment. These results indicate that the primary event during the growth inhibition was the change in the growth-induced water potential. Because the growth limitation subsequently shifted to the low wall extensibility and tissue conductance for water, the initial change in potential may have set in motion subsequent metabolic changes that altered the characteristics of the wall and cell membranes. PMID:16667663

Chitinase-like (CTL) and cellulose synthase (CESA) gene expression in gelatinous-type cellulosic walls of flax (Linum usitatissimum L.) bast fibers.

PubMed

Mokshina, Natalia; Gorshkova, Tatyana; Deyholos, Michael K

2014-01-01

Plant chitinases (EC 3.2.1.14) and chitinase-like (CTL) proteins have diverse functions including cell wall biosynthesis and disease resistance. We analyzed the expression of 34 chitinase and chitinase-like genes of flax (collectively referred to as LusCTLs), belonging to glycoside hydrolase family 19 (GH19). Analysis of the transcript expression patterns of LusCTLs in the stem and other tissues identified three transcripts (LusCTL19, LusCTL20, LusCTL21) that were highly enriched in developing bast fibers, which form cellulose-rich gelatinous-type cell walls. The same three genes had low relative expression in tissues with primary cell walls and in xylem, which forms a xylan type of secondary cell wall. Phylogenetic analysis of the LusCTLs identified a flax-specific sub-group that was not represented in any of other genomes queried. To provide further context for the gene expression analysis, we also conducted phylogenetic and expression analysis of the cellulose synthase (CESA) family genes of flax, and found that expression of secondary wall-type LusCESAs (LusCESA4, LusCESA7 and LusCESA8) was correlated with the expression of two LusCTLs (LusCTL1, LusCTL2) that were the most highly enriched in xylem. The expression of LusCTL19, LusCTL20, and LusCTL21 was not correlated with that of any CESA subgroup. These results defined a distinct type of CTLs that may have novel functions specific to the development of the gelatinous (G-type) cellulosic walls.

Mechanisms for Ductile Rupture - FY16 ESC Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyce, Brad L.; Carroll, Jay D.; Noell, Phillip

2017-01-01

Ductile rupture in metals is generally a multi-step process of void nucleation, growth, and coalescence. Particle decohesion and particle fracture are generally invoked as the primary microstructural mechanisms for room-temperature void nucleation. However, because high-purity materials also fail by void nucleation and coalescence, other microstructural features must also act as sites for void nucleation. Early studies of void initiation in high-purity materials, which included post-mortem fracture surface characterization using scanning electron microscopy (SEM) and high-voltage electron microscopy (HVEM) and in-situ HVEM observations of fracture, established the presence of dislocation cell walls as void initiation sites in high-purity materials. Direct experimentalmore » evidence for this contention was obtained during in-situ HVEM tensile tests of Be single crystals. Voids between 0.2 and 1 μm long appeared suddenly along dislocation cell walls during tensile straining. However, subsequent attempts to replicate these results in other materials, particularly α -Fe single crystals, were unsuccessful because of the small size of the dislocation cells, and these remain the only published in-situ HVEM observations of void nucleation at dislocation cell walls in the absence of a growing macrocrack. Despite this challenge, other approaches to studying void nucleation in high-purity metals also indicate that dislocation cell walls are nucleation sites for voids.« less

POLYGALACTURONASE INVOLVED IN EXPANSION1 functions in cell elongation and flower development in Arabidopsis.

PubMed

Xiao, Chaowen; Somerville, Chris; Anderson, Charles T

2014-03-01

Pectins are acidic carbohydrates that comprise a significant fraction of the primary walls of eudicotyledonous plant cells. They influence wall porosity and extensibility, thus controlling cell and organ growth during plant development. The regulated degradation of pectins is required for many cell separation events in plants, but the role of pectin degradation in cell expansion is poorly defined. Using an activation tag screen designed to isolate genes involved in wall expansion, we identified a gene encoding a putative polygalacturonase that, when overexpressed, resulted in enhanced hypocotyl elongation in etiolated Arabidopsis thaliana seedlings. We named this gene POLYGALACTURONASE INVOLVED IN EXPANSION1 (PGX1). Plants lacking PGX1 display reduced hypocotyl elongation that is complemented by transgenic PGX1 expression. PGX1 is expressed in expanding tissues throughout development, including seedlings, roots, leaves, and flowers. PGX1-GFP (green fluorescent protein) localizes to the apoplast, and heterologously expressed PGX1 displays in vitro polygalacturonase activity, supporting a function for this protein in apoplastic pectin degradation. Plants either overexpressing or lacking PGX1 display alterations in total polygalacturonase activity, pectin molecular mass, and wall composition and also display higher proportions of flowers with extra petals, suggesting PGX1's involvement in floral organ patterning. These results reveal new roles for polygalacturonases in plant development.

Boron reduces aluminum-induced growth inhibition, oxidative damage and alterations in the cell wall components in the roots of trifoliate orange.

PubMed

Riaz, Muhammad; Yan, Lei; Wu, Xiuwen; Hussain, Saddam; Aziz, Omar; Imran, Muhammad; Rana, Muhammad Shoaib; Jiang, Cuncang

2018-05-30

Aluminum (Al) toxicity is a major restriction for crops production on acidic soils. The primary symptom of aluminum toxicity is visible in the roots of plants. Recently, several studies reported the alleviation of Al toxicity by the application of Boron (B), however, the information how B alleviates Al toxicity is not well understood. Thus, we investigated the ameliorative response of B on Al-induced growth inhibition, oxidative damages, and variations in the cell wall components in trifoliate orange roots. The results indicated that plants under Al stress experienced a substantial decrement in root length and overall plant growth. The supply of B improved the root elongation by eliminating oxidative stress, membrane peroxidation, membrane leakage, and cell death produced under Al toxicity. Moreover, accumulation of Al on the cell wall and alteration in the cell wall components might be one of the causes resulting in the quick inhibition of root elongation under B-starvation circumstances by providing susceptible negative charges on pectin matrix for binding of Al. The results provide a useful understanding of the insight into mechanisms of B-induced mitigation of Al toxicity especially in the trifoliate orange that might be helpful in the production of crops on acidic soils. Copyright © 2018 Elsevier Inc. All rights reserved.

Molecular deformation mechanisms of the wood cell wall material.

PubMed

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

2015-02-01

Wood is a biological material with outstanding mechanical properties resulting from its hierarchical structure across different scales. Although earlier work has shown that the cellular structure of wood is a key factor that renders it excellent mechanical properties at light weight, the mechanical properties of the wood cell wall material itself still needs to be understood comprehensively. The wood cell wall material features a fiber reinforced composite structure, where cellulose fibrils act as stiff fibers, and hemicellulose and lignin molecules act as soft matrix. The angle between the fiber direction and the loading direction has been found to be the key factor controlling the mechanical properties. However, how the interactions between theses constitutive molecules contribute to the overall properties is still unclear, although the shearing between fibers has been proposed as a primary deformation mechanism. Here we report a molecular model of the wood cell wall material with atomistic resolution, used to assess the mechanical behavior under shear loading in order to understand the deformation mechanisms at the molecular level. The model includes an explicit description of cellulose crystals, hemicellulose, as well as lignin molecules arranged in a layered nanocomposite. The results obtained using this model show that the wood cell wall material under shear loading deforms in an elastic and then plastic manner. The plastic regime can be divided into two parts according to the different deformation mechanisms: yielding of the matrix and sliding of matrix along the cellulose surface. Our molecular dynamics study provides insights of the mechanical behavior of wood cell wall material at the molecular level, and paves a way for the multi-scale understanding of the mechanical properties of wood. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of multivalent cations on cell wall-associated acid phosphatase activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tu, S.I.; Brouillette, J.N.; Nagahashi, G.

1988-09-01

Primary cell walls, free from cytoplasmic contamination were prepared from corn (Zea mays L.) roots and potato (Solanum tuberosum) tubers. After EDTA treatment, the bound acid phosphatase activities were measured in the presence of various multivalent cations. Under the conditions of minimized Donnan effect and at pH 4.2, the bound enzyme activity of potato tuber cell walls (PCW) was stimulated by Cu/sup 2 +/, Mg/sup 2 +/, Za/sup 2 +/, and Mn/sup 2 +/; unaffected by Ba/sup 2 +/, Cd/sup 2 +/, and Pb/sup 2 +/; and inhibited by Al/sup 3 +/. The bound acid phosphatase of PCW was stimulatedmore » by a low concentration but inhibited by a higher concentration of Hg/sup 2 +/. On the other hand, in the case of corn root cells walls (CCW), only inhibition of the bound acid phosphatase by Al/sup 3 +/ and Hg/sup 2 +/ was observed. Kinetic analyses revealed that PCW acid phosphatase exhibited a negative cooperativity under all employed experimental conditions except in the presence of Mg/sup 2 +/. In contrast, CCW acid phosphatase showed no cooperative behavior. The presence of Ca/sup 2 +/ significantly reduced the effects of Hg/sup 2 +/ or Al/sup 3 +/, but not Mg/sup 2 +/, to the bound cell wall acid phosphatases. The salt solubilized (free) acid phosphatases from both PCW and CCW were not affected by the presence of tested cations except for Hg/sup 2 +/ or Al/sup 3 +/ which caused a Ca/sup 2 +/-insensitive inhibition of the enzymes. The induced stimulation or inhibition of bound acid phosphatases was quantitatively related to cation binding in the cell wall structure.« less

Two tomato GDP-D-mannose epimerase isoforms involved in ascorbate biosynthesis play specific roles in cell wall biosynthesis and development.

PubMed

Mounet-Gilbert, Louise; Dumont, Marie; Ferrand, Carine; Bournonville, Céline; Monier, Antoine; Jorly, Joana; Lemaire-Chamley, Martine; Mori, Kentaro; Atienza, Isabelle; Hernould, Michel; Stevens, Rebecca; Lehner, Arnaud; Mollet, Jean Claude; Rothan, Christophe; Lerouge, Patrice; Baldet, Pierre

2016-08-01

GDP-D-mannose epimerase (GME, EC 5.1.3.18) converts GDP-D-mannose to GDP-L-galactose, and is considered to be a central enzyme connecting the major ascorbate biosynthesis pathway to primary cell wall metabolism in higher plants. Our previous work demonstrated that GME is crucial for both ascorbate and cell wall biosynthesis in tomato. The aim of the present study was to investigate the respective role in ascorbate and cell wall biosynthesis of the two SlGME genes present in tomato by targeting each of them through an RNAi-silencing approach. Taken individually SlGME1 and SlGME2 allowed normal ascorbate accumulation in the leaf and fruits, thus suggesting the same function regarding ascorbate. However, SlGME1 and SlGME2 were shown to play distinct roles in cell wall biosynthesis, depending on the tissue considered. The RNAi-SlGME1 plants harbored small and poorly seeded fruits resulting from alterations of pollen development and of pollination process. In contrast, the RNAi-SlGME2 plants exhibited vegetative growth delay while fruits remained unaffected. Analysis of SlGME1- and SlGME2-silenced seeds and seedlings further showed that the dimerization state of pectin rhamnogalacturonan-II (RG-II) was altered only in the RNAi-SlGME2 lines. Taken together with the preferential expression of each SlGME gene in different tomato tissues, these results suggest sub-functionalization of SlGME1 and SlGME2 and their specialization for cell wall biosynthesis in specific tomato tissues. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

The Effects of High Steady State Auxin Levels on Root Cell Elongation in Brachypodium[OPEN

PubMed Central

Pacheco-Villalobos, David; Tamaki, Takayuki; Gujas, Bojan; Jaspert, Nina; Oecking, Claudia; Bulone, Vincent; Hardtke, Christian S.

2016-01-01

The long-standing Acid Growth Theory of plant cell elongation posits that auxin promotes cell elongation by stimulating cell wall acidification and thus expansin action. To date, the paucity of pertinent genetic materials has precluded thorough analysis of the importance of this concept in roots. The recent isolation of mutants of the model grass species Brachypodium distachyon with dramatically enhanced root cell elongation due to increased cellular auxin levels has allowed us to address this question. We found that the primary transcriptomic effect associated with elevated steady state auxin concentration in elongating root cells is upregulation of cell wall remodeling factors, notably expansins, while plant hormone signaling pathways maintain remarkable homeostasis. These changes are specifically accompanied by reduced cell wall arabinogalactan complexity but not by increased proton excretion. On the contrary, we observed a tendency for decreased rather than increased proton extrusion from root elongation zones with higher cellular auxin levels. Moreover, similar to Brachypodium, root cell elongation is, in general, robustly buffered against external pH fluctuation in Arabidopsis thaliana. However, forced acidification through artificial proton pump activation inhibits root cell elongation. Thus, the interplay between auxin, proton pump activation, and expansin action may be more flexible in roots than in shoots. PMID:27169463

AtERF38 (At2g35700), an AP2/ERF family transcription factor gene from Arabidopsis thaliana, is expressed in specific cell types of roots, stems and seeds that undergo suberization.

PubMed

Lasserre, Eric; Jobet, Edouard; Llauro, Christel; Delseny, Michel

2008-12-01

An inverse genetic approach was used to gain insight into the role of AP2/ERF-type transcription factors genes during plant development in Arabidopsis thaliana. Here we show that the expression pattern of AtERF38, which is, among the organs tested, more intensively expressed in mature siliques and floral stems, is closely associated with tissues that undergo secondary cell wall modifications. Firstly, public microarray data sets analysis indicates that AtERF38 is coregulated with several genes involved in secondary wall thickening. Secondly, this was experimentally confirmed in different types of cells expressing a Pro(AtERF38)::GUS fusion: histochemical analysis revealed strong and specific GUS activity in outer integument cells of mature seeds, endodermal cells of the roots in the primary developmental stage and some sclerified cells of mature inflorescence stems. All of these cells are known or shown here to be characterized by a reinforced wall. The latter, which have not been well characterized to date in Arabidopsis and may be suberized, could benefit of the use of AtERF38 as a specific marker. We were not able to detect any phenotype in an insertion line in which ectopic expression of AtERF38 is caused by the insertion of a T-DNA in its promoter. Nevertheless, AtERF28 may be considered as a candidate regulator of secondary wall metabolism in particular cell types that are not reinforced by the typical deposition of lignin and cellulose, but that have at least in common accumulation of suberin-like lipid polyesters in their walls.

WallGen, software to construct layered cellulose-hemicellulose networks and predict their small deformation mechanics.

PubMed

Kha, Hung; Tuble, Sigrid C; Kalyanasundaram, Shankar; Williamson, Richard E

2010-02-01

We understand few details about how the arrangement and interactions of cell wall polymers produce the mechanical properties of primary cell walls. Consequently, we cannot quantitatively assess if proposed wall structures are mechanically reasonable or assess the effectiveness of proposed mechanisms to change mechanical properties. As a step to remedying this, we developed WallGen, a Fortran program (available on request) building virtual cellulose-hemicellulose networks by stochastic self-assembly whose mechanical properties can be predicted by finite element analysis. The thousands of mechanical elements in the virtual wall are intended to have one-to-one spatial and mechanical correspondence with their real wall counterparts of cellulose microfibrils and hemicellulose chains. User-defined inputs set the properties of the two polymer types (elastic moduli, dimensions of microfibrils and hemicellulose chains, hemicellulose molecular weight) and their population properties (microfibril alignment and volume fraction, polymer weight percentages in the network). This allows exploration of the mechanical consequences of variations in nanostructure that might occur in vivo and provides estimates of how uncertainties regarding certain inputs will affect WallGen's mechanical predictions. We summarize WallGen's operation and the choice of values for user-defined inputs and show that predicted values for the elastic moduli of multinet walls subject to small displacements overlap measured values. "Design of experiment" methods provide systematic exploration of how changed input values affect mechanical properties and suggest that changing microfibril orientation and/or the number of hemicellulose cross-bridges could change wall mechanical anisotropy.

Selective Individual Primary Cell Capture Using Locally Bio-Functionalized Micropores

PubMed Central

Liu, Jie; Bombera, Radoslaw; Leroy, Loïc; Roupioz, Yoann; Baganizi, Dieudonné R.; Marche, Patrice N.; Haguet, Vincent; Mailley, Pascal; Livache, Thierry

2013-01-01

Background Solid-state micropores have been widely employed for 6 decades to recognize and size flowing unlabeled cells. However, the resistive-pulse technique presents limitations when the cells to be differentiated have overlapping dimension ranges such as B and T lymphocytes. An alternative approach would be to specifically capture cells by solid-state micropores. Here, the inner wall of 15-µm pores made in 10 µm-thick silicon membranes was covered with antibodies specific to cell surface proteins of B or T lymphocytes. The selective trapping of individual unlabeled cells in a bio-functionalized micropore makes them recognizable just using optical microscopy. Methodology/Principal Findings We locally deposited oligodeoxynucleotide (ODN) and ODN-conjugated antibody probes on the inner wall of the micropores by forming thin films of polypyrrole-ODN copolymers using contactless electro-functionalization. The trapping capabilities of the bio-functionalized micropores were validated using optical microscopy and the resistive-pulse technique by selectively capturing polystyrene microbeads coated with complementary ODN. B or T lymphocytes from a mouse splenocyte suspension were specifically immobilized on micropore walls functionalized with complementary ODN-conjugated antibodies targeting cell surface proteins. Conclusions/Significance The results showed that locally bio-functionalized micropores can isolate target cells from a suspension during their translocation throughout the pore, including among cells of similar dimensions in complex mixtures. PMID:23469221

Flying saucer1 is a transmembrane RING E3 ubiquitin ligase that regulates the degree of pectin methylesterification in Arabidopsis seed mucilage.

PubMed

Voiniciuc, Catalin; Dean, Gillian H; Griffiths, Jonathan S; Kirchsteiger, Kerstin; Hwang, Yeen Ting; Gillett, Alan; Dow, Graham; Western, Tamara L; Estelle, Mark; Haughn, George W

2013-03-01

Pectins are complex polysaccharides that form the gel matrix of the primary cell wall and are abundant in the middle lamella that holds plant cells together. Their degree of methylesterification (DM) impacts wall strength and cell adhesion since unesterified pectin regions can cross-link via Ca(2+) ions to form stronger gels. Here, we characterize flying saucer1 (fly1), a novel Arabidopsis thaliana seed coat mutant, which displays primary wall detachment, reduced mucilage extrusion, and increased mucilage adherence. These defects appear to result from a lower DM in mucilage and are enhanced by the addition of Ca(2+) or completely rescued using alkaline Ca(2+) chelators. FLY1 encodes a transmembrane protein with a RING-H2 domain that has in vitro E3 ubiquitin ligase activity. FLY1 is orthologous to TRANSMEMBRANE UBIQUITIN LIGASE1, a Golgi-localized E3 ligase involved in the quality control of membrane proteins in yeast. However, FLY1-yellow fluorescent protein (YFP) fusions are localized in punctae that are predominantly distinct from the Golgi and the trans-Golgi network/early endosome in the seed coat epidermis. Wortmannin treatment, which induces the fusion of late endosomes in plants, resulted in enlarged FLY1-YFP bodies. We propose that FLY1 regulates the DM of pectin in mucilage, potentially by recycling pectin methylesterase enzymes in the endomembrane system of seed coat epidermal cells.

FLYING SAUCER1 Is a Transmembrane RING E3 Ubiquitin Ligase That Regulates the Degree of Pectin Methylesterification in Arabidopsis Seed Mucilage[W

PubMed Central

Voiniciuc, Cătălin; Dean, Gillian H.; Griffiths, Jonathan S.; Kirchsteiger, Kerstin; Hwang, Yeen Ting; Gillett, Alan; Dow, Graham; Western, Tamara L.; Estelle, Mark; Haughn, George W.

2013-01-01

Pectins are complex polysaccharides that form the gel matrix of the primary cell wall and are abundant in the middle lamella that holds plant cells together. Their degree of methylesterification (DM) impacts wall strength and cell adhesion since unesterified pectin regions can cross-link via Ca2+ ions to form stronger gels. Here, we characterize flying saucer1 (fly1), a novel Arabidopsis thaliana seed coat mutant, which displays primary wall detachment, reduced mucilage extrusion, and increased mucilage adherence. These defects appear to result from a lower DM in mucilage and are enhanced by the addition of Ca2+ or completely rescued using alkaline Ca2+ chelators. FLY1 encodes a transmembrane protein with a RING-H2 domain that has in vitro E3 ubiquitin ligase activity. FLY1 is orthologous to TRANSMEMBRANE UBIQUITIN LIGASE1, a Golgi-localized E3 ligase involved in the quality control of membrane proteins in yeast. However, FLY1–yellow fluorescent protein (YFP) fusions are localized in punctae that are predominantly distinct from the Golgi and the trans-Golgi network/early endosome in the seed coat epidermis. Wortmannin treatment, which induces the fusion of late endosomes in plants, resulted in enlarged FLY1-YFP bodies. We propose that FLY1 regulates the DM of pectin in mucilage, potentially by recycling pectin methylesterase enzymes in the endomembrane system of seed coat epidermal cells. PMID:23482858

Biophysical basis of growth promotion in primary leaves of Phaseolus vulgaris L. by hormones versus light: solute accumulation and the growth potential

NASA Technical Reports Server (NTRS)

Brock, T. G.; Cleland, R. E.

1990-01-01

Rapid cell enlargement in primary leaves of bean is induced by bright white light (WL), gibberellic acid (GA3) or the cytokinin N6-benzyladenine (BA). In previous studies it has been show that all three agents cause an increase in wall extensibility, although by different mechanisms. Here we examine the effects of the three growth promoters on the osmotic potential difference (delta Psi), the accumulation of solutes (delta TSC), the wall yield threshold (Y) and the growth potential (delta Psi -Y). With GA3 and BA, but not WL, there was a rapid decline in delta Psi as measured by the osmotic concentration of expressed sap. Unlike WL, neither GA3 nor BA promoted the accumulation of osmotic solutes. The decline in delta Psi, however, was apparently counteracted by a decline in Y since the growth potential, as measured by the external-osmoticum method, remained unchanged. It is concluded that WL, GA3 and BA all promote cell enlargement of bean leaves by increasing one cellular growth parameter, wall extensibility. Only WL, however, promotes osmotic adjustment during growth.

Isolation and characterization of beta-glucan synthase: A potential biochemical regulator of gravistimulated differential cell wall loosening

NASA Technical Reports Server (NTRS)

Kuzmanoff, K. M.

1984-01-01

In plants, gravity stimulates differential growth in the upper and lower halves of horizontally oriented organs. Auxin regulation of cell wall loosening and elongation is the basis for most models of this phenomenon. Auxin treatment of pea stem tissue rapidly increases the activity of Golgi-localized Beta-1,4-glucan synthase, an enzyme involved in biosynthesis of wall xyloglucan which apparently constitutes the substrate for the wall loosening process. The primary objective is to determine if auxin induces de novo formation of Golgi glucan synthase and increases the level of this glucan synthase mRNA. This shall be accomplished by (a) preparation of a monoclonal antibody to the synthase, (b) isolation, and characterization of the glucan synthase, and (c) examination for cross reactivity between the antibody and translation products of auxin induced mRNAs in pea tissue. The antibody will also be used to localize the glucan synthase in upper and lower halves of pea stem tissue before, during and after the response to gravity.

Functional characterization of two distinct xyoglucanases from rumenal microbes

USDA-ARS?s Scientific Manuscript database

Xyloglucans are known to function by binding to cellulose microfibrils, crosslinking adjacent fibers forming cellulose-XG networks important for modulation of rigidity and extensibility of the primary cell wall of plants. Enzymatic hydrolysis and modification of xyloglucans has received considerabl...

Towards a Viscous Wall Model for Immersed Boundary Methods

NASA Technical Reports Server (NTRS)

Brehm, Christoph; Barad, Michael F.; Kiris, Cetin C.

2016-01-01

Immersed boundary methods are frequently employed for simulating flows at low Reynolds numbers or for applications where viscous boundary layer effects can be neglected. The primary shortcoming of Cartesian mesh immersed boundary methods is the inability of efficiently resolving thin turbulent boundary layers in high-Reynolds number flow application. The inefficiency of resolving the thin boundary is associated with the use of constant aspect ratio Cartesian grid cells. Conventional CFD approaches can efficiently resolve the large wall normal gradients by utilizing large aspect ratio cells near the wall. This paper presents different approaches for immersed boundary methods to account for the viscous boundary layer interaction with the flow-field away from the walls. Different wall modeling approaches proposed in previous research studies are addressed and compared to a new integral boundary layer based approach. In contrast to common wall-modeling approaches that usually only utilize local flow information, the integral boundary layer based approach keeps the streamwise history of the boundary layer. This allows the method to remain effective at much larger y+ values than local wall modeling approaches. After a theoretical discussion of the different approaches, the method is applied to increasingly more challenging flow fields including fully attached, separated, and shock-induced separated (laminar and turbulent) flows.

[A very rare submucosal tumour of the rectum - primary endometrioid adenocarcinoma of the rectum wall].

PubMed

Vogel, Y; Ginsbach, C; Ende, M; Schwering, H; Golz, N; Rieker, O; Hildenbrand, R

2013-01-01

A 56-year-old female, with a past history of hysterectomy 13 years previously due to uterine myomata, presented with complaints of pain around the anus of a few months duration. Three years previously she underwent a colonoscopy, which was found to be unremarkable. A high suspicion of a submucosal tumour of the rectum in endoscopic examinations was confirmed by endoscopic ultrasound. The biopsy could not specify the tumour characteristics. Based on the diagnosis of a 4 cm submucosal tumour with infiltration of bowel wall and regional lymph nodes the affected segment was resected. Histolopathology revealed an adenocarcinoma involving tissue from the outer bowel wall to the submucosa. However, immunohistochemistry revealed an endometrioid adenocarcinoma, suspicious for primary endometrioid adenocarcinoma of the ovary with rectum metastasis in the absence of a uterus. But this assumption could not be confirmed in the excised ovary. The tumour cells were immunopositive for cytokeratin 7, CA 12 - 5, vimentin and oestrogen receptor, but negative for cytokeratin 20 and CDX-2. Ultimately, we report a very rare case of primary endometrioid adenocarcinoma arising in endometriosis in the rectum wall and presenting as a submucosal tumour. © Georg Thieme Verlag KG Stuttgart · New York.

Extraction and characterization of pectins from primary cell walls of edible açaí (Euterpe oleraceae) berries, fruits of a monocotyledon palm.

PubMed

Cantu-Jungles, Thaisa Moro; Iacomini, Marcello; Cipriani, Thales R; Cordeiro, Lucimara M C

2017-02-20

Açaí berries (Euterpe oleracea) are greatly consumed in Brazil and exported to other countries as a nutritional supplement, due to health benefits attributed to its consumption. However, the complete chemical structure of bioactive polysaccharides was not fully elucidated yet. In this work, we characterize pectic polysaccharides from açaí berries through monosaccharide composition, HPSEC, methylation and 13 C and 1 H/ 13 C HSQC-DEPT-NMR analyses. A highly methoxylated homogalacturonan with a DM of 88% and Mw of 22kDa together with small amounts of a mannoglucan were found. Moreover, a type II arabinogalactan (Mw=45kDa) containing a backbone with high portions of 6-O-linked and 3,6-O-linked Galp chains rather than 3-O-linked Galp was also isolated and structurally characterized. The type II arabinogalactan was found as a side chain of a type I rhamnogalacturonan. These findings contribute to correlate the fine chemical structure with the previously reported action of açaí polysaccharides on innate immune response. Moreover, from the taxonomic point of view, the results bring new information about polysaccharide composition of primary cell walls of palms (Arecaceae), that despite being commelinid monocots, have a distinct cell wall composition. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rhizobium cellulase CelC2 is essential for primary symbiotic infection of legume host roots

PubMed Central

Robledo, M.; Jiménez-Zurdo, J. I.; Velázquez, E.; Trujillo, M. E.; Zurdo-Piñeiro, J. L.; Ramírez-Bahena, M. H.; Ramos, B.; Díaz-Mínguez, J. M.; Dazzo, F.; Martínez-Molina, E.; Mateos, P. F.

2008-01-01

The rhizobia–legume, root-nodule symbiosis provides the most efficient source of biologically fixed ammonia fertilizer for agricultural crops. Its development involves pathways of specificity, infectivity, and effectivity resulting from expressed traits of the bacterium and host plant. A key event of the infection process required for development of this root-nodule symbiosis is a highly localized, complete erosion of the plant cell wall through which the bacterial symbiont penetrates to establish a nitrogen-fixing, intracellular endosymbiotic state within the host. This process of wall degradation must be delicately balanced to avoid lysis and destruction of the host cell. Here, we describe the purification, biochemical characterization, molecular genetic analysis, biological activity, and symbiotic function of a cell-bound bacterial cellulase (CelC2) enzyme from Rhizobium leguminosarum bv. trifolii, the clover-nodulating endosymbiont. The purified enzyme can erode the noncrystalline tip of the white clover host root hair wall, making a localized hole of sufficient size to allow wild-type microsymbiont penetration. This CelC2 enzyme is not active on root hairs of the nonhost legume alfalfa. Microscopy analysis of the symbiotic phenotypes of the ANU843 wild type and CelC2 knockout mutant derivative revealed that this enzyme fulfils an essential role in the primary infection process required for development of the canonical nitrogen-fixing R. leguminosarum bv. trifolii-white clover symbiosis. PMID:18458328

Inhibition of phenylpropanoid biosynthesis increases cell wall digestibility, protoplast isolation, and facilitates sustained cell division in American elm (Ulmus americana).

PubMed

Jones, A Maxwell P; Chattopadhyay, Abhishek; Shukla, Mukund; Zoń, Jerzy; Saxena, Praveen K

2012-05-30

Protoplast technologies offer unique opportunities for fundamental research and to develop novel germplasm through somatic hybridization, organelle transfer, protoclonal variation, and direct insertion of DNA. Applying protoplast technologies to develop Dutch elm disease resistant American elms (Ulmus americana L.) was proposed over 30 years ago, but has not been achieved. A primary factor restricting protoplast technology to American elm is the resistance of the cell walls to enzymatic degradation and a long lag phase prior to cell wall re-synthesis and cell division. This study suggests that resistance to enzymatic degradation in American elm was due to water soluble phenylpropanoids. Incubating tobacco (Nicotiana tabacum L.) leaf tissue, an easily digestible species, in aqueous elm extract inhibits cell wall digestion in a dose dependent manner. This can be mimicked by p-coumaric or ferulic acid, phenylpropanoids known to re-enforce cell walls. Culturing American elm tissue in the presence of 2-aminoindane-2-phosphonic acid (AIP; 10-150 μM), an inhibitor of phenylalanine ammonia lyase (PAL), reduced flavonoid content, decreased tissue browning, and increased isolation rates significantly from 11.8% (±3.27) in controls to 65.3% (±4.60). Protoplasts isolated from callus grown in 100 μM AIP developed cell walls by day 2, had a division rate of 28.5% (±3.59) by day 6, and proliferated into callus by day 14. Heterokaryons were successfully produced using electrofusion and fused protoplasts remained viable when embedded in agarose. This study describes a novel approach of modifying phenylpropanoid biosynthesis to facilitate efficient protoplast isolation which has historically been problematic for American elm. This isolation system has facilitated recovery of viable protoplasts capable of rapid cell wall re-synthesis and sustained cell division to form callus. Further, isolated protoplasts survived electrofusion and viable heterokaryons were produced. Together, these results provide the first evidence of sustained cell division, callus regeneration, and potential application of somatic cell fusion in American elm, suggesting that this source of protoplasts may be ideal for genetic manipulation of this species. The technological advance made with American elm in this study has potential implications in other woody species for fundamental and applied research which require availability of viable protoplasts.

Inhibition of phenylpropanoid biosynthesis increases cell wall digestibility, protoplast isolation, and facilitates sustained cell division in American elm (Ulmus americana)

PubMed Central

2012-01-01

Background Protoplast technologies offer unique opportunities for fundamental research and to develop novel germplasm through somatic hybridization, organelle transfer, protoclonal variation, and direct insertion of DNA. Applying protoplast technologies to develop Dutch elm disease resistant American elms (Ulmus americana L.) was proposed over 30 years ago, but has not been achieved. A primary factor restricting protoplast technology to American elm is the resistance of the cell walls to enzymatic degradation and a long lag phase prior to cell wall re-synthesis and cell division. Results This study suggests that resistance to enzymatic degradation in American elm was due to water soluble phenylpropanoids. Incubating tobacco (Nicotiana tabacum L.) leaf tissue, an easily digestible species, in aqueous elm extract inhibits cell wall digestion in a dose dependent manner. This can be mimicked by p-coumaric or ferulic acid, phenylpropanoids known to re-enforce cell walls. Culturing American elm tissue in the presence of 2-aminoindane-2-phosphonic acid (AIP; 10-150 μM), an inhibitor of phenylalanine ammonia lyase (PAL), reduced flavonoid content, decreased tissue browning, and increased isolation rates significantly from 11.8% (±3.27) in controls to 65.3% (±4.60). Protoplasts isolated from callus grown in 100 μM AIP developed cell walls by day 2, had a division rate of 28.5% (±3.59) by day 6, and proliferated into callus by day 14. Heterokaryons were successfully produced using electrofusion and fused protoplasts remained viable when embedded in agarose. Conclusions This study describes a novel approach of modifying phenylpropanoid biosynthesis to facilitate efficient protoplast isolation which has historically been problematic for American elm. This isolation system has facilitated recovery of viable protoplasts capable of rapid cell wall re-synthesis and sustained cell division to form callus. Further, isolated protoplasts survived electrofusion and viable heterokaryons were produced. Together, these results provide the first evidence of sustained cell division, callus regeneration, and potential application of somatic cell fusion in American elm, suggesting that this source of protoplasts may be ideal for genetic manipulation of this species. The technological advance made with American elm in this study has potential implications in other woody species for fundamental and applied research which require availability of viable protoplasts. PMID:22646730

Dehydration induced loss of photosynthesis in Arabidopsis leaves during senescence is accompanied by the reversible enhancement in the activity of cell wall β-glucosidase.

PubMed

Patro, Lichita; Mohapatra, Pranab Kishor; Biswal, Udaya Chand; Biswal, Basanti

2014-08-01

The physiology of loss of photosynthetic production of sugar and the consequent cellular sugar reprogramming during senescence of leaves experiencing environmental stress largely remains unclear. We have shown that leaf senescence in Arabidopsis thaliana causes a significant reduction in the rate of oxygen evolution and net photosynthetic rate (Pn). The decline in photosynthesis is further aggravated by dehydration. During dehydration, primary photochemical reaction of thylakoids and net photosynthesis decrease in parallel with the increase in water deficit. Senescence induced loss in photosynthesis is accompanied by a significant increase in the activity of cell wall hydrolyzing enzyme such as β-glucosidase associated with cell wall catabolism. The activity of this enzyme is further enhanced when the senescing leaves experience dehydration stress. It is possible that both senescence and stress separately or in combination result in the loss in photosynthesis which could be a signal for an enhancement in the activity of β-glucosidase that breaks down cell wall polysaccharides to sugar to sustain respiration for metabolic activities of plants experiencing stress. Thus dehydration response of cell wall hydrolases of senescing leaves is considered as plants' strategy to have cell wall polysaccharides as an alternative energy source for completion of energy requiring senescence process, stress survival and maintenance of recovery potential of energy deficit cells in the background of loss in photosynthesis. Withdrawal of stress (rehydration) distinctly exhibits recovery of photosynthesis and suppression of enzyme activity. Retention of the signaling for sugar reprogramming through breakdown of cell wall polysaccharides in the senescing leaves exposed to severe drought stress suggests that senescing leaves like mature ones possess potential for stress recovery. The precise mechanism of stress adaptation of senescing leaves is yet to be known. A significant accumulation of anthocyanin and flavonoids may be an indicator of stress adaptation of senescing leaves. In addition, stress induced enhancement of nonphotochemical quenching (NPQ), a stress protection provision in green plants, also suggests the potential of the leaves to develop adaptational mechanism to counter the dehydration stress. Copyright © 2014 Elsevier B.V. All rights reserved.

Primary structure of the wall peptidoglycan of leprosy-derived corynebacteria.

PubMed Central

Janczura, E; Leyh-Bouille, M; Cocito, C; Ghuysen, J M

1981-01-01

The cell walls isolated from axenically grown leprosy-derived corynebacteria were submitted to various chemical and enzymatic degradations. The glycan strands of the wall peptidoglycan are essentially composed of N-acetylglycosaminyl-N-acetylmuramic acid disaccharide units. Small amounts of N-acetylglycosaminyl-N-glycolylmuramic acid (less than 10%) were also detected. The muramic acid residues of adjacent glycan strands are substituted by amidated tetrapeptide units which, in turn, are cross-linked through direct linkages extending between the C-terminal D-alanine residue of one tetrapeptide and the mesodiaminopimelic acid residue of another tetrapeptide. Such a structure is very similar to that of the wall peptidoglycan found in the taxonomically related microorganisms of the Corynebacterium, Mycobacterium, and Nocardia groups. PMID:7462160

The proliferative ventricular zone in adult vertebrates: a comparative study using reptiles, birds, and mammals.

PubMed

García-Verdugo, Jose Manuel; Ferrón, Sacri; Flames, Nuria; Collado, Lucía; Desfilis, Ester; Font, Enrique

2002-04-01

Although evidence accumulated during the last decades has advanced our understanding of adult neurogenesis in the vertebrate brain, many aspects of this intriguing phenomenon remain controversial. Here we review the organization and cellular composition of the ventricular wall of reptiles, birds, and mammals in an effort to identify differences and commonalities among these vertebrate classes. Three major cell types have been identified in the ventricular zone of reptiles and birds: migrating (Type A) cells, radial glial (Type B) cells, and ependymal (Type E) cells. Cells similar anatomically and functionally to Types A, B, and E have also been described in the ventricular wall of mammals, which contains an additional cell type (Type C) not found in reptiles or birds. The bulk of the evidence points to a role of Type B cells as primary neural precursors (stem cells) in the three classes of living amniotic vertebrates. This finding may have implications for the development of strategies for the possible treatment of human neurological disorders.

Role of cellular compartmentalization in the trophic transfer of mercury species in a freshwater plant-crustacean food chain.

PubMed

Beauvais-Flück, Rebecca; Chaumot, Arnaud; Gimbert, Frédéric; Quéau, Hervé; Geffard, Olivier; Slaveykova, Vera I; Cosio, Claudia

2016-12-15

Mercury (Hg) represents an important risk for human health through the food webs contamination. Macrophytes bioaccumulate Hg and play a role in Hg transfer to food webs in shallow aquatic ecosystems. Nevertheless, the compartmentalization of Hg within macrophytes, notably major accumulation in the cell wall and its impact on trophic transfer to primary consumers are overlooked. The present work focusses on the trophic transfer of inorganic Hg (IHg) and monomethyl-Hg (MMHg) from the intracellular and cell wall compartments of the macrophyte Elodea nuttallii - considered a good candidate for phytoremediation - to the crustacean Gammarus fossarum. The results demonstrated that Hg accumulated in both compartments was trophically bioavailable to gammarids. Besides IHg from both compartments were similarly transferred to G. fossarum, while for MMHg, uptake rates were ∼2.5-fold higher in G. fossarum fed with the cell wall vs the intracellular compartment. During the depuration phase, Hg concentrations in G. fossarum varied insignificantly suggesting that both IHg and MMHg were strongly bound to biological ligands in the crustacean. Our data imply that cell walls have to be considered as an important source of Hg to consumers in freshwater food webs when developing procedures for enhancing aquatic environment protection during phytoremediation programs. Copyright © 2016 Elsevier B.V. All rights reserved.

Bioinformatics-Based Identification of Candidate Genes from QTLs Associated with Cell Wall Traits in Populus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ranjan, Priya; Yin, Tongming; Zhang, Xinye

2009-11-01

Quantitative trait locus (QTL) studies are an integral part of plant research and are used to characterize the genetic basis of phenotypic variation observed in structured populations and inform marker-assisted breeding efforts. These QTL intervals can span large physical regions on a chromosome comprising hundreds of genes, thereby hampering candidate gene identification. Genome history, evolution, and expression evidence can be used to narrow the genes in the interval to a smaller list that is manageable for detailed downstream functional genomics characterization. Our primary motivation for the present study was to address the need for a research methodology that identifies candidatemore » genes within a broad QTL interval. Here we present a bioinformatics-based approach for subdividing candidate genes within QTL intervals into alternate groups of high probability candidates. Application of this approach in the context of studying cell wall traits, specifically lignin content and S/G ratios of stem and root in Populus plants, resulted in manageable sets of genes of both known and putative cell wall biosynthetic function. These results provide a roadmap for future experimental work leading to identification of new genes controlling cell wall recalcitrance and, ultimately, in the utility of plant biomass as an energy feedstock.« less

Primary intraosseous squamous cell carcinoma in odontogenic keratocyst: A rare entity

PubMed Central

Saxena, Chitrapriya; Aggarwal, Pooja; Wadhwan, Vijay; Bansal, Vishal

2015-01-01

Squamous cell carcinoma (SCC) arising from the wall of an odontogenic cyst (also known as primary intraosseous carcinoma) is a rare tumor which occurs only in jaw bones. This tumor was first described by Loos in 1913 as a central epidermoid carcinoma of the jaw. Primary intraosseous carcinomas (PIOC) may theoretically arise from the lining of an odontogenic cyst or de novo from presumed odontogenic cell rests. According to the new histological classification of tumors of the World Health Organization, odontogenic keratocyst is nowadays considered a specific odontogenic tumor and the PIOC derived from it is considered as a specific entity which is different from other PIOCs derived from the odontogenic cysts. The following report describes a case of such extremely rare entity that is primary intraosseous SCC of the mandible derived from an OKC in a 60-year-old male patient with brief review of literature. PMID:26980976

γ-Aminobutyric acid transaminase deficiency impairs central carbon metabolism and leads to cell wall defects during salt stress in Arabidopsis roots.

PubMed

Renault, Hugues; El Amrani, Abdelhak; Berger, Adeline; Mouille, Grégory; Soubigou-Taconnat, Ludivine; Bouchereau, Alain; Deleu, Carole

2013-05-01

Environmental constraints challenge cell homeostasis and thus require a tight regulation of metabolic activity. We have previously reported that the γ-aminobutyric acid (GABA) metabolism is crucial for Arabidopsis salt tolerance as revealed by the NaCl hypersensitivity of the GABA transaminase (GABA-T, At3g22200) gaba-t/pop2-1 mutant. In this study, we demonstrate that GABA-T deficiency during salt stress causes root and hypocotyl developmental defects and alterations of cell wall composition. A comparative genome-wide transcriptional analysis revealed that expression levels of genes involved in carbon metabolism, particularly sucrose and starch catabolism, were found to increase upon the loss of GABA-T function under salt stress conditions. Consistent with the altered mutant cell wall composition, a number of cell wall-related genes were also found differentially expressed. A targeted quantitative analysis of primary metabolites revealed that glutamate (GABA precursor) accumulated while succinate (the final product of GABA metabolism) significantly decreased in mutant roots after 1 d of NaCl treatment. Furthermore, sugar concentration was twofold reduced in gaba-t/pop2-1 mutant roots compared with wild type. Together, our results provide strong evidence that GABA metabolism is a major route for succinate production in roots and identify GABA as a major player of central carbon adjustment during salt stress. © 2012 Blackwell Publishing Ltd.

Cellular uptake mechanisms of functionalised multi-walled carbon nanotubes by 3D electron tomography imaging

NASA Astrophysics Data System (ADS)

Al-Jamal, Khuloud T.; Nerl, Hannah; Müller, Karin H.; Ali-Boucetta, Hanene; Li, Shouping; Haynes, Peter D.; Jinschek, Joerg R.; Prato, Maurizio; Bianco, Alberto; Kostarelos, Kostas; Porter, Alexandra E.

2011-06-01

Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between carbon nanotubes and the plasma membrane to investigate the mechanisms involved in the cellular uptake of shortened, functionalised multi-walled carbon nanotubes (MWNT-NH3+). Both human lung epithelial (A549) cells, that are almost incapable of phagocytosis and primary macrophages, capable of extremely efficient phagocytosis, were used. We observed that MWNT-NH3+ were internalised in both phagocytic and non-phagocytic cells by any one of three mechanisms: (a) individually via membrane wrapping; (b) individually by direct membrane translocation; and (c) in clusters within vesicular compartments. At early time points following intracellular translocation, we noticed accumulation of nanotube material within various intracellular compartments, while a long-term (14-day) study using primary human macrophages revealed that MWNT-NH3+ were able to escape vesicular (phagosome) entrapment by translocating directly into the cytoplasm.Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between carbon nanotubes and the plasma membrane to investigate the mechanisms involved in the cellular uptake of shortened, functionalised multi-walled carbon nanotubes (MWNT-NH3+). Both human lung epithelial (A549) cells, that are almost incapable of phagocytosis and primary macrophages, capable of extremely efficient phagocytosis, were used. We observed that MWNT-NH3+ were internalised in both phagocytic and non-phagocytic cells by any one of three mechanisms: (a) individually via membrane wrapping; (b) individually by direct membrane translocation; and (c) in clusters within vesicular compartments. At early time points following intracellular translocation, we noticed accumulation of nanotube material within various intracellular compartments, while a long-term (14-day) study using primary human macrophages revealed that MWNT-NH3+ were able to escape vesicular (phagosome) entrapment by translocating directly into the cytoplasm. Electronic supplementary information (ESI) available: See DOI: 10.1039/c1nr10080g

Petrographic and anatomical characteristics of plant material from two peat deposits of Holocene and Miocene age, Kalimantan, Indonesia

USGS Publications Warehouse

Moore, T.A.; Hilbert, R.E.

1992-01-01

Samples from two peat-forming environments of Holocene and Miocene age in Kalimantan (Borneo), Indonesia, were studied petrographically using nearly identical sample preparation and microscopic methodologies. Both deposits consist of two basic types of organic material: plant organs/tissues and fine-grained matrix. There are seven predominant types of plant organs and tissues: roots possessing only primary growth, stems possessing only primary growth, leaves, stems/roots with secondary growth, secondary xylem fragments, fragments of cork cells, and macerated tissue of undetermined origin. The fine-grained matrix consists of fragments of cell walls and cell fillings, fungal remains, spores and pollen grains, and resin. Some of the matrix material does not have distinct grain boundaries (at ??500) and this material is designated amorphous matrix. The major difference between the Holocene peat and Miocene lignite in reflected light, oil immersion is a loss of red coloration in the cell walls of tissue in the lignite, presumably due to loss of cellulosic compounds. In addition, cortex and phloem tissue (hence primary roots and stems) are difficult to recognize in the lignite, probably because these large, thin-walled tissues are more susceptible to microbial degradation and compaction. Particle size in both peat and lignite samples display a bimodal distribution when measurements are transformed to a - log2 or phi (??), scale. Most plant parts have modes of 2-3?? (0.25 - 0.125 mm), whereas the finer-grained particulate matrix has modes of 7-9?? (0.008-0.002 mm). This similarity suggest certain degradative processes. The 2-3?? range may be a "stable" size for plant parts (regardless of origin) because this is a characteristics of a substrate which is most suitable for plant growth in peat. The finer-grained matrix material (7-9??) probably results from fungal decay which causes plant material to weaken and with slight physical pressure to shatter into its component parts, i.e. fragments of cell walls and fillings. The absence of differences in particle size between the peat and lignite also indicate little compaction of organic components; rather an extreme loss in water content and pore space has occurred from between the particles of organic material. ?? 1992.

Cellular and Pectin Dynamics during Abscission Zone Development and Ripe Fruit Abscission of the Monocot Oil Palm

PubMed Central

Roongsattham, Peerapat; Morcillo, Fabienne; Fooyontphanich, Kim; Jantasuriyarat, Chatchawan; Tragoonrung, Somvong; Amblard, Philippe; Collin, Myriam; Mouille, Gregory; Verdeil, Jean-Luc; Tranbarger, Timothy J.

2016-01-01

The oil palm (Elaeis guineensis Jacq.) fruit primary abscission zone (AZ) is a multi-cell layered boundary region between the pedicel (P) and mesocarp (M) tissues. To examine the cellular processes that occur during the development and function of the AZ cell layers, we employed multiple histological and immunohistochemical methods combined with confocal, electron and Fourier-transform infrared (FT-IR) microspectroscopy approaches. During early fruit development and differentiation of the AZ, the orientation of cell divisions in the AZ was periclinal compared with anticlinal divisions in the P and M. AZ cell wall width increased earlier during development suggesting cell wall assembly occurred more rapidly in the AZ than the adjacent P and M tissues. The developing fruit AZ contain numerous intra-AZ cell layer plasmodesmata (PD), but very few inter-AZ cell layer PD. In the AZ of ripening fruit, PD were less frequent, wider, and mainly intra-AZ cell layer localized. Furthermore, DAPI staining revealed nuclei are located adjacent to PD and are remarkably aligned within AZ layer cells, and remain aligned and intact after cell separation. The polarized accumulation of ribosomes, rough endoplasmic reticulum, mitochondria, and vesicles suggested active secretion at the tip of AZ cells occurred during development which may contribute to the striated cell wall patterns in the AZ cell layers. AZ cells accumulated intracellular pectin during development, which appear to be released and/or degraded during cell separation. The signal for the JIM5 epitope, that recognizes low methylesterified and un-methylesterified homogalacturonan (HG), increased in the AZ layer cell walls prior to separation and dramatically increased on the separated AZ cell surfaces. Finally, FT-IR microspectroscopy analysis indicated a decrease in methylesterified HG occurred in AZ cell walls during separation, which may partially explain an increase in the JIM5 epitope signal. The results obtained through a multi-imaging approach allow an integrated view of the dynamic developmental processes that occur in a multi-layered boundary AZ and provide evidence for distinct regulatory mechanisms that underlie oil palm fruit AZ development and function. PMID:27200017

Primary Uterine Peripheral T-cell Lymphoma

PubMed Central

Gong, Jing; Dong, Aisheng; Wang, Yang; Zhang, Xuefeng; Yang, Panpan; Wang, Li; Jing, Wei

2016-01-01

Abstract Primary uterine non-Hodgkin's lymphoma is extremely rare accounting for <1% of all extranodal non-Hodgkin's lymphomas. Imaging findings of primary uterine lymphoma have rarely been reported before. We present magnetic resonance imaging (MRI) and fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/CT findings in a patient with primary uterine peripheral T-cell lymphoma. A 27-year-old female presented with intermittent fever with neutropenia for 7 months. MRI showed an ill-defined mass involved both the uterine corpus and cervix, resulting in diffuse enlargement of the uterus. This mass showed inhomogeneous hypointensity on unenhanced T1-weighted images, hyperintensity on diffusion-weighted imaging, relative hypointensity compared to the surrounding myometrium on T2-weighted images and lower enhancement than the surrounding myometrium on enhanced T1-weighted images. FDG PET/CT showed intense FDG uptake in the thickened wall of the uterine corpus and cervix with SUVmax of 26.9. There were multiple hypermetabolic lymph nodes in the pelvis and retroperitoneum. Uterine curettage and CT-guided biopsy of the uterine mass revealed peripheral T-cell lymphoma. Bone marrow biopsy revealed no evidence of lymphomatous involvement. The imaging and pathologic findings were consistent with primary uterine lymphoma. After 3 circles of chemotherapy, follow-up enhanced MRI showed decreased thickness of the uterine wall. Despite its rarity, primary uterine non-Hodgkin's lymphoma should be taken into consideration when a uterine tumor shows large size, relative hypointesity on both T2-weighted images and enhanced T1-weighted images compared to the surrounding myometrium, and intense FDG uptake on PET/CT. MRI may be helpful for describing the relationship between the tumor and adjacent structures. FDG PET/CT may be useful for tumor detection and staging. PMID:27124063

Microgravity

NASA Image and Video Library

1998-10-10

Human primary breast tumor cells after 49 days of growth in a NASA Bioreactor. Tumor cells aggregate on microcarrier beads (indicated by arrow). NASA's Marshall Space Flight Center (MSFC) is sponsoring research with Bioreactors, rotating wall vessels designed to grow tissue samples in space, to understand how breast cancer works. This ground-based work studies the growth and assembly of human mammary epithelial cell (HMEC) from breast cancer susceptible tissue. Radiation can make the cells cancerous, thus allowing better comparisons of healthy vs. tunorous tissue. Credit: Dr. Jearne Becker, University of South Florida

Applications of optical manipulation in plant biology

NASA Astrophysics Data System (ADS)

Buer, Charles S.

Measuring small forces in biology is important for determining basic physiological parameters of a cell. The plant cell wall provides a primary defense and presents a barrier to research. Magnitudes of small forces are impossible to measure with mechanical transducers, glass needles, atomic force microscopy, or micropipet-based force transduction due to the cell wall. Therefore, a noninvasive method of breaching the plant cell wall to access the symplastic region of the cell is required. Laser light provides sub-micrometer positioning, particle manipulation without mechanical contact, and piconewton force determination. Consequently, the extension of laser microsurgery to expand an experimental tool for plant biology encompassed the overall objective. A protocol was developed for precisely inserting microscopic objects into the periplasmic region of plant callus cells using laser microsurgery. Ginkgo biloba and Agrobacterium rhizogenes were used as the model system for developing the optical tweezers and scalpel techniques. Better than 95% survival was achieved after plasmolyzing G. biloba cells, ablating a 2-4 μm hole through the cell wall using a pulsed UV laser beam, trapping and manipulating bacteria into the periplasmic region, and deplasmolyzing the cells. Optical trapping experiments implied a difference existed between the bacteria models. Determining the optical trapping efficiency of Agrobacterium rhizogenes and A. tumefaciens strains indicated the A. rhizogenes strain, ATCC 11325, was significantly less efficiently trapped than strains A4 and ATCC 15834 and the A. tumefaciens strain LBA4404. Differences were also found in capsule generation, growth media viscosity, and transmission electron microscopy negative staining implying that a difference in surface structure exists. Calcofluor fluorescence suggests the difference involves an exopolysaccharide. Callus cell plasmolysis revealed Hechtian strands interconnecting the plasma membrane and the cell wall. The spring tension of these strands was measured in normal and cold-hardened G. biloba and N. tabacum callus cells. There was little change in flexibility between the groups of cultured cells in either species studied. Microspheres were attached to Hechtian strands in normal cultured Nicotiana tabacum and the cells were deplasmolyzed and replasmolyzed to determine the fate of Hechtian strands. The microspheres either moved to the plasma membrane and adhered or moved to the cell wall and adhered. The attached microspheres occasionally moved independently on the same strand. Inserted microspheres provided a visual probe to follow physiological events within a plant cell.

The rhizotoxicity of metal cations is related to their strength of binding to hard ligands.

PubMed

Kopittke, Peter M; Menzies, Neal W; Wang, Peng; McKenna, Brigid A; Wehr, J Bernhard; Lombi, Enzo; Kinraide, Thomas B; Blamey, F Pax C

2014-02-01

Mechanisms whereby metal cations are toxic to plant roots remain largely unknown. Aluminum, for example, has been recognized as rhizotoxic for approximately 100 yr, but there is no consensus on its mode of action. The authors contend that the primary mechanism of rhizotoxicity of many metal cations is nonspecific and that the magnitude of toxic effects is positively related to the strength with which they bind to hard ligands, especially carboxylate ligands of the cell-wall pectic matrix. Specifically, the authors propose that metal cations have a common toxic mechanism through inhibiting the controlled relaxation of the cell wall as required for elongation. Metal cations such as Al(3+) and Hg(2+), which bind strongly to hard ligands, are toxic at relatively low concentrations because they bind strongly to the walls of cells in the rhizodermis and outer cortex of the root elongation zone with little movement into the inner tissues. In contrast, metal cations such as Ca(2+), Na(+), Mn(2+), and Zn(2+) , which bind weakly to hard ligands, bind only weakly to the cell wall and move farther into the root cylinder. Only at high concentrations is their weak binding sufficient to inhibit the relaxation of the cell wall. Finally, different mechanisms would explain why certain metal cations (for example, Tl(+), Ag(+), Cs(+), and Cu(2+)) are sometimes more toxic than expected through binding to hard ligands. The data presented in the present study demonstrate the importance of strength of binding to hard ligands in influencing a range of important physiological processes within roots through nonspecific mechanisms. © 2013 SETAC.

Boron Supply Enhances Aluminum Tolerance in Root Border Cells of Pea (Pisum sativum) by Interacting with Cell Wall Pectins

PubMed Central

Fang, Jing; Tao, Lin; Shen, Ren Fang; Li, Ya Lin; Xiao, Hong Dong; Feng, Ying Ming; Wen, Hai Xiang; Guan, Jia Hua; Wu, Li Shu; He, Yong Ming; Goldbach, Heiner E.; Yu, Min

2017-01-01

Aluminum (Al) toxicity is the primary factor limiting crop growth in acidic soils. Boron (B) alleviates Al toxicity in plants, which is mainly considered to be due to the formation of Rhamnogalacturonan II-B (RGII-B) complexes, which helps to stabilize the cytoskeleton. It is unclear yet whether this is due to the increasing of net negative charges and/or further mechanisms. Kinetics of Al accumulation and adsorption were investigated using entire cells, cell wall and pectin of root border cells (RBCs) of pea (Pisum sativum), to reveal the mechanism of B in interacting with alkali-soluble and chelator-soluble pectin for an increased Al tolerance in RBCs. The results show that B could rescue RBCs from Al-induced cell death by accumulating more Al in the cell wall, predominately in alkali-soluble pectin. Boron also promotes Al3+ adsorption and inhibits Al3+ desorption from alkali-soluble pectin. Thus, more Al3+ is immobilized within the alkali-soluble pectin fraction and less in the chelator-soluble pectin, rendering Al3+ less mobile. Boron induces an increase of RG-II (KDO,2-keto-3-deoxyoctonic acid) content for forming more borate-RGII complexes, and the decrease of pectin methyl-esterification, thus creates more negative charges to immobilize Al3+ in cell wall pectin. The study provides evidence that abundant B supply enhances the immobilization of Al in alkali-soluble pectin, thus most likely reducing the entry of Al3+ into the symplast from the surroundings. PMID:28533794

Shading Contributes to the Reduction of Stem Mechanical Strength by Decreasing Cell Wall Synthesis in Japonica Rice (Oryza sativa L.).

PubMed

Wu, Longmei; Zhang, Wujun; Ding, Yanfeng; Zhang, Jianwei; Cambula, Elidio D; Weng, Fei; Liu, Zhenghui; Ding, Chengqiang; Tang, She; Chen, Lin; Wang, Shaohua; Li, Ganghua

2017-01-01

Low solar radiation caused by industrial development and solar dimming has become a limitation in crop production in China. It is widely accepted that low solar radiation influences many aspects of plant development, including slender, weak stems and susceptibility to lodging. However, the underlying mechanisms are not well understood. To clarify how low solar radiation affects stem mechanical strength formation and lodging resistance, the japonica rice cultivars Wuyunjing23 (lodging-resistant) and W3668 (lodging-susceptible) were grown under field conditions with normal light (Control) and shading (the incident light was reduced by 60%) with a black nylon net. The yield and yield components, plant morphological characteristics, the stem mechanical strength, cell wall components, culm microstructure, gene expression correlated with cellulose and lignin biosynthesis were measured. The results showed that shading significantly reduced grain yield attributed to reduction of spikelets per panicles and grain weight. The stem-breaking strength decreased significantly under shading treatment; consequently, resulting in higher lodging index in rice plant in both varieties, as revealed by decreased by culm diameter, culm wall thickness and increased plant height, gravity center height. Compared with control, cell wall components including non-structural carbohydrate, sucrose, cellulose, and lignin reduced quite higher. With histochemical straining, shading largely reduced lignin deposition in the sclerenchyma cells and vascular bundle cells compared with control, and decreased cellulose deposition in the parenchyma cells of culm tissue in both Wuyunjing23 and W3668. And under shading condition, gene expression involved in secondary cell wall synthesis, OsPAL, OsCOMT, OsCCoAOMT, OsCCR , and OsCAD2 , and primary cell wall synthesis, OsCesA1, OsCesA3 , and OsCesA8 were decreased significantly. These results suggest that gene expression involved in the reduction of lignin and cellulose in both sclerenchyma and parenchyma cells, which attribute to lignin and cellulose in culm tissue and weak mechanical tissue, consequently, result in poor stem strength and higher lodging risks. Highlights : (1) Shading decreases the stem mechanical strength of japonica rice by decreasing non-structural carbohydrate, sucrose, lignin, and cellulose accumulation in culms. (2) The decrease of carbon source under shading condition is the cause for the lower lignin and cellulose accumulation in culm. (3) The expression of genes involved in lignin and primarily cell wall cellulose biosynthesis ( OsCesA1, OsCesA3 , and OsCesA8 ) at the stem formation stage are down-regulated under shading condition, inducing defective cell wall development and poor lodging resistance.

Induced compression wood formation in Douglas fir (Pseudotsuga menziesii) in microgravity

NASA Technical Reports Server (NTRS)

Kwon, M.; Bedgar, D. L.; Piastuch, W.; Davin, L. B.; Lewis, N. G.

2001-01-01

In the microgravity environment of the Space Shuttle Columbia (Life and Microgravity Mission STS-78), were grown 1-year-old Douglas fir and loblolly pine plants in a NASA plant growth facility. Several plants were harnessed (at 45 degrees ) to establish if compression wood biosynthesis, involving altered cellulose and lignin deposition and cell wall structure would occur under those conditions of induced mechanical stress. Selected plants were harnessed at day 2 in orbit, with stem sections of specific plants harvested and fixed for subsequent microscopic analyses on days 8, 10 and 15. At the end of the total space mission period (17 days), the remaining healthy harnessed plants and their vertical (upright) controls were harvested and fixed on earth. All harnessed (at 45 degrees ) plant specimens, whether grown at 1 g or in microgravity, formed compression wood. Moreover, not only the cambial cells but also the developing tracheid cells underwent significant morphological changes. This indicated that the developing tracheids from the primary cell wall expansion stage to the fully lignified maturation stage are involved in the perception and transduction of the stimuli stipulating the need for alteration of cell wall architecture. It is thus apparent that, even in a microgravity environment, woody plants can make appropriate corrections to compensate for stress gradients introduced by mechanical bending, thereby enabling compression wood to be formed. The evolutionary implications of these findings are discussed in terms of "variability" in cell wall biosynthesis.

Synchronous Microscopic Epstein-Barr Virus-Positive Diffuse Large B-Cell Lymphoma of the Adrenal and Lymphoplasmacytic Lymphoma: De Novo Disease or Transformation?

PubMed

Moonim, Mufaddal T; Nasir, Alia; Hubbard, Jonathan; Ketley, Nicholas; Fields, Paul

2017-06-01

Lymphomas arising in the adrenal are rare, and to our knowledge, 2 cases of Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphomas (DLBCL) in an adrenal pseudocyst have been reported. We report an incidental EBV-positive DLBCL arising in an adrenal pseudocyst in a 58-year-old man with a 7-year history of lymphoplasmacytic lymphoma (LPL). The DLBCL was present in the fibrinous exudate, while the LPL resided in the cyst wall. The patient underwent de-roofing of the same cyst 3 years previously; review of histology revealed foci of LPL in the cyst wall, but not of DLBCL. There have been reports of similar microscopic EBV-positive DLBCLs within enclosed cystic spaces. However, all these cases were incidental extranodal primary DLBCLs. Since residual LPL was present alongside DLBCL, with similar light chain restriction, we propose that this may represent transformation, rather than a de novo primary EBV-driven lymphoma.

Arabinan-rich pectic polysaccharides from buriti (Mauritia flexuosa): an Amazonian edible palm fruit.

PubMed

Cantu-Jungles, Thaisa Moro; Almeida, Carolina Pierobom de; Iacomini, Marcello; Cipriani, Thales R; Cordeiro, Lucimara M C

2015-05-20

Primary cell wall polysaccharides from aqueous extract of buriti fruit pulp (Mauritia flexuosa, an exotic tropical palm) were isolated and characterized. After freeze-thaw and α-amylase treatments, extracted polysaccharides were purified by sequential ultrafiltration through membranes. Two homogeneous fractions were obtained, SBW-100R and SBW-30R (Mw of 126 kDa and 20 kDa, respectively). Monosaccharide composition, methylation and (13)C NMR analysis showed that fraction SBW-100R contained a (1 → 5)-linked arabinan, branched at O-3 and O-2 positions, linked to a type I rhamnogalacturonan. Low amounts of these polymers were also present in fraction SBW-30R according to (13)C NMR analysis and monosaccharide composition. However, a high methyl esterified homogalacturonan (HG) was present in higher proportions. These results reinforce previous findings present in literature data which indicate that pectic polysaccharides are found in high amounts in primary cell walls of palms, which are commelinid monocotyledons. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mechanosensory Genes Pkd1 and Pkd2 Contribute to the Planar Polarization of Brain Ventricular Epithelium

PubMed Central

Herranz-Pérez, Vicente; Nakatani, Jin; Boletta, Alessandra; García-Verdugo, José Manuel

2015-01-01

Directional beating of ependymal (E) cells' cilia in the walls of the ventricles in the brain is essential for proper CSF flow. E cells display two forms of planar cell polarity (PCP): rotational polarity of individual cilium and translational polarity (asymmetric positioning of cilia in the apical area). The orientation of individual E cells varies according to their location in the ventricular wall (location-specific PCP). It has been hypothesized that hydrodynamic forces on the apical surface of radial glia cells (RGCs), the embryonic precursors of E cells, could guide location-specific PCP in the ventricular epithelium. However, the detection mechanisms for these hydrodynamic forces have not been identified. Here, we show that the mechanosensory proteins polycystic kidney disease 1 (Pkd1) and Pkd2 are present in primary cilia of RGCs. Ablation of Pkd1 or Pkd2 in Nestin-Cre;Pkd1flox/flox or Nestin-Cre;Pkd2flox/flox mice, affected PCP development in RGCs and E cells. Early shear forces on the ventricular epithelium may activate Pkd1 and Pkd2 in primary cilia of RGCs to properly polarize RGCs and E cells. Consistently, Pkd1, Pkd2, or primary cilia on RGCs were required for the proper asymmetric localization of the PCP protein Vangl2 in E cells' apical area. Analyses of single- and double-heterozygous mutants for Pkd1 and/or Vangl2 suggest that these genes function in the same pathway to establish E cells' PCP. We conclude that Pkd1 and Pkd2 mechanosensory proteins contribute to the development of brain PCP and prevention of hydrocephalus. SIGNIFICANCE STATEMENT This study identifies key molecules in the development of planar cell polarity (PCP) in the brain and prevention of hydrocephalus. Multiciliated ependymal (E) cells within the brain ventricular epithelium generate CSF flow through ciliary beating. E cells display location-specific PCP in the orientation and asymmetric positioning of their cilia. Defects in this PCP can result in hydrocephalus. Hydrodynamic forces on radial glial cells (RGCs), the embryonic progenitors of E cells, have been suggested to guide PCP. We show that the mechanosensory proteins Pkd1 and Pkd2 localize to primary cilia in RGCs, and their ablation disrupts the development of PCP in E cells. Early shear forces on RGCs may activate Pkd1 and Pkd2 in RGCs' primary cilia to properly orient E cells. This study identifies key molecules in the development of brain PCP and prevention of hydrocephalus. PMID:26245976

Multi-walled carbon nanotube length as a critical determinant of bioreactivity with primary human pulmonary alveolar cells

PubMed Central

Sweeney, Sinbad; Berhanu, Deborah; Misra, Superb K.; Thorley, Andrew J.; Valsami-Jones, Eugenia; Tetley, Teresa D.

2015-01-01

Multiwalled carbon nanotube (MWCNT) length is suggested to critically determine their pulmonary toxicity. This stems from in vitro and in vivo rodent studies and in vitro human studies using cell lines (typically cancerous). There is little data using primary human lung cells. We addressed this knowledge gap, using highly relevant, primary human alveolar cell models exposed to precisely synthesized and thoroughly characterized MWCNTs. In this work, transformed human alveolar type-I-like epithelial cells (TT1), primary human alveolar type-II epithelial cells (ATII) and alveolar macrophages (AM) were treated with increasing concentrations of MWCNTs before measuring cytotoxicity, inflammatory mediator release and MAP kinase signalling. Strikingly, we observed that short MWCNTs (~0.6 µm in length) induced significantly greater responses from the epithelial cells, whilst AM were particularly susceptible to long MWCNTs (~20 µm). These differences in the pattern of mediator release were associated with alternative profiles of JNK, p38 and ERK1/2 MAP kinase signal transduction within each cell type. This study, using highly relevant target human alveolar cells and well defined and characterized MWCNTs, shows marked cellular responses to the MWCNTs that vary according to the target cell type, as well as the aspect ratio of the MWCNT. PMID:25780270

Galactoglucomannans increase cell population density and alter the protoxylem/metaxylem tracheary element ratio in xylogenic cultures of Zinnia.

PubMed

Benová-Kákosová, Anna; Digonnet, Catherine; Goubet, Florence; Ranocha, Philippe; Jauneau, Alain; Pesquet, Edouard; Barbier, Odile; Zhang, Zhinong; Capek, Peter; Dupree, Paul; Lisková, Desana; Goffner, Deborah

2006-10-01

Xylogenic cultures of zinnia (Zinnia elegans) provide a unique opportunity to study signaling pathways of tracheary element (TE) differentiation. In vitro TEs differentiate into either protoxylem (PX)-like TEs characterized by annular/helical secondary wall thickening or metaxylem (MX)-like TEs with reticulate/scalariform/pitted thickening. The factors that determine these different cell fates are largely unknown. We show here that supplementing zinnia cultures with exogenous galactoglucomannan oligosaccharides (GGMOs) derived from spruce (Picea abies) xylem had two major effects: an increase in cell population density and a decrease in the ratio of PX to MX TEs. In an attempt to link these two effects, the consequence of the plane of cell division on PX-MX differentiation was assessed. Although GGMOs did not affect the plane of cell division per se, they significantly increased the proportion of longitudinally divided cells differentiating into MX. To test the biological significance of these findings, we have determined the presence of mannan-containing oligosaccharides in zinnia cultures in vitro. Immunoblot assays indicated that beta-1,4-mannosyl epitopes accumulate specifically in TE-inductive media. These epitopes were homogeneously distributed within the thickened secondary walls of TEs when the primary cell wall was weakly labeled. Using polysaccharide analysis carbohydrate gel electrophoresis, glucomannans were specifically detected in cell walls of differentiating zinnia cultures. Finally, zinnia macroarrays probed with cDNAs from cells cultured in the presence or absence of GGMOs indicated that significantly more genes were down-regulated rather than up-regulated by GGMOs. This study constitutes a major step in the elucidation of signaling mechanisms of PX- and MX-specific genetic programs in zinnia.

Frequency-selective REDOR and spin-diffusion relays in uniformly labeled whole cells.

PubMed

Rice, David M; Romaniuk, Joseph A H; Cegelski, Lynette

2015-11-01

Solid-state NMR is a powerful and non-perturbative method to measure and define chemical composition and architecture in bacterial cell walls, even in the context of whole cells. Most NMR studies on whole cells have used selectively labeled samples. Here, we introduce an NMR sequence relay using frequency-selective REDOR (fsREDOR) and spin diffusion elements to probe a unique amine contribution in uniformly (13)C- and (15)N-labeled Staphylococcus aureus whole cells that we attribute to the d-alanine of teichoic acid. In addition to the primary peptidoglycan structural scaffold, cell walls can contain significant amounts of teichoic acid that contribute to cell-wall function. When incorporated into teichoic acid, d-alanine is present as an ester, connected via its carbonyl to a ribitol carbon, and thus has a free amine. Teichoic acid d-Ala is removed during cell-wall isolations and can only be detected in the context of whole cells. The sequence presented here begins with fsREDOR and a chemical shift evolution period for 2D data acquisition, followed by DARR spin diffusion and then an additional fsREDOR period. fsREDOR elements were used for (13)C observation to avoid complications from (13)C-(13)C couplings due to uniform labeling and for (15)N dephasing to achieve selectivity in the nitrogens serving as dephasers. The results show that the selected amine nitrogen of interest is near to teichoic acid ribitol carbons and also the methyl group carbon associated with alanine. In addition, its carbonyl is not significantly dephased by amide nitrogens, consistent with the expected microenvironment around teichoic acid. Copyright © 2015 Elsevier Inc. All rights reserved.

Expression of the high-affinity choline transporter CHT1 in rat and human arteries.

PubMed

Lips, Katrin S; Pfeil, Uwe; Reiners, Katja; Rimasch, Christoph; Kuchelmeister, Klaus; Braun-Dullaeus, Ruediger C; Haberberger, Rainer V; Schmidt, Rupert; Kummer, Wolfgang

2003-12-01

The arterial vascular wall contains a non-neuronal intrinsic cholinergic system. The rate-limiting step in acetylcholine (ACh) synthesis is choline uptake. A high-affinity choline transporter, CHT1, has recently been cloned from neural tissue and has been identified in epithelial cholinergic cells. Here we investigated its presence in rat and human arteries and in primary cell cultures of rat vascular cells (endothelial cells, smooth muscle cells, fibroblasts). CHT1-mRNA was detected in the arterial wall and in all isolated cell types by RT-PCR using five different CHT1-specific primer pairs. Antisera raised against amino acids 29-40 of the rat sequence labeled a single band (50 kD) in Western blots of rat aorta, and an additional higher molecular weight band appeared in the hippocampus. Immunohistochemistry demonstrated CHT1 immunoreactivity in endothelial and smooth muscle cells in situ and in all cultured cell types. A high-affinity [3H]-choline uptake mechanism sharing characteristics with neuronal high-affinity choline uptake, i.e., sensitivity to hemicholinium-3 and dependence on sodium, was demonstrated in rat thoracic aortic segments by microimager autoradiography. Expression of the high-affinity choline transporter CHT1 is a novel component of the intrinsic non-neuronal cholinergic system of the arterial vascular wall, predominantly in the intimal and medial layers.

Light-stimulated cell expansion in bean (Phaseolus vulgaris L.) leaves. I. Growth can occur without photosynthesis

NASA Technical Reports Server (NTRS)

Van Volkenburgh, E.; Cleland, R. E.

1990-01-01

Cell expansion in dicotyledonous leaves is strongly stimulated by bright white light (WL), at least in part as a result of light-induced acidification of the cell walls. It has been proposed that photosynthetic reactions are required for light-stimulated transport processes across plasma membranes of leaf cells, including proton excretion. The involvement of photosynthesis in growth and wall acidification of primary leaves of bean has been tested by inhibiting photosynthesis in two ways: by reducing chlorophyll content of intact plants with tentoxin (TX) and by treating leaf discs with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Exposure to bright WL stimulated growth of intact leaves of TX-treated plants. Discs excised from green as well as from TX-or DCMU-treated leaves also responded by growing faster in WL, as long as exogenous sucrose was supplied to the photosynthetically inhibited tissues. The WL caused acidification of the epidermal surface of intact TX-leaves, but acidification of the incubation medium by mesophyll cells only occurred when photosynthesis was not inhibited. It is concluded that light-stimulated cell enlargement of bean leaves, and the necessary acidification of epidermal cell walls, are mediated by a pigment other than chlorophyll. Light-induced proton excretion by mesophyll cells, on the other hand, may require both a photosynthetic product (or exogenous sugars) and a non-photosynthetic light effect.

[A case of group G Streptococcus sepsis, chest wall abscess, and vertebral osteomyelitis mimicking a primary lung cancer with bone metastasis].

PubMed

Hayashi, Yumeko; Ishii, Yoshiki; Arai, Ryo; Obara, Kazuki; Kamada, Aya; Takizawa, Hidenori; Hase, Isano; Mashio, Kazuki; Yamada, Issei; Takemasa, Akihiro; Sugiyama, Kumiya; Fukushima, Yasutsugu; Fukuda, Takeshi

2007-01-01

A 73-year-old woman who had been followed in our department of gynecology because of ovarian cancer since 2002, was admitted with liver dysfunction and complaining of back pain and light precordial chest pain. The chest radiograph on admission revealed a tumor in her left upper lung field, and chest CT revealed a tumor adjacent to the chest wall and mediastinum. FDG-positron emission tomography (PET) showed abnormal uptake in the tumor and Th6/7, and the subaortic lymph nodes. On the basis of these findings, primary lung cancer with bone metastasis was suspected. She had a high grade fever on admission, and blood cultures were positive for group G streptococcus. The treatment with intravenous penicillin was started. Percutaneous biopsy of the tumor in her left chest showed an abscess wall in the chest wall, but no evidence of malignancy. Transbronchial lung biopsy and CT-guided biopsy also showed no malignant cells. Since the tumor decreased in size and back pain improved gradually by only antibiotic treatment, a diagnosis of sepsis of group G streptococcus, chest wall abscess, and vertebral osteomyelitis was made. She was treated with intravenous penicillin for 4 weeks and oral amoxicillin for another 4 weeks. After 60 days of antibiotic treatment, the tumor vanished.

The ectopic expression of a pectin methyl esterase inhibitor increases pectin methyl esterification and limits fungal diseases in wheat.

PubMed

Volpi, Chiara; Janni, Michela; Lionetti, Vincenzo; Bellincampi, Daniela; Favaron, Francesco; D'Ovidio, Renato

2011-09-01

Cell wall pectin methyl esterification can influence plant resistance because highly methyl-esterified pectin can be less susceptible to the hydrolysis by pectic enzymes such as fungal endopolygalacturonases (PG). Pectin is secreted into the cell wall in a highly methyl-esterified form and, here, is de-methyl esterified by pectin methyl esterase (PME). The activity of PME is controlled by specific protein inhibitors called PMEI; consequently, an increased inhibition of PME by PMEI might modify the pectin methyl esterification. In order to test the possibility of improving wheat resistance by modifying the methyl esterification of pectin cell wall, we have produced durum wheat transgenic lines expressing the PMEI from Actinidia chinensis (AcPMEI). The expression of AcPMEI endows wheat with a reduced endogenous PME activity, and transgenic lines expressing a high level of the inhibitor showed a significant increase in the degree of methyl esterification. These lines showed a significant reduction of disease symptoms caused by the fungal pathogens Bipolaris sorokiniana or Fusarium graminearum. This increased resistance was related to the impaired ability of these fungal pathogens to grow on methyl-esterified pectin and to a reduced activity of the fungal PG to hydrolyze methyl-esterified pectin. In addition to their importance for wheat improvement, these results highlight the primary role of pectin despite its low content in the wheat cell wall.

Characterization of primary cilia in human airway smooth muscle cells.

PubMed

Wu, Jun; Du, Hui; Wang, Xiangling; Mei, Changlin; Sieck, Gary C; Qian, Qi

2009-08-01

Considerable evidence indicates a key role for primary cilia of mammalian cells in mechanochemical sensing. Dysfunctions of primary cilia have been linked to the pathogenesis of several human diseases. However, cilia-related research has been limited to a few cell and tissue types; to our knowledge, no literature exists on primary cilia in airway smooth muscle (ASM). The aim of this study was to characterize primary cilia in human ASM. Primary cilia of human bronchial smooth muscle cells (HBSMCs) were examined using immunofluorescence confocal microscopy, and scanning and transmission electron microscopy. HBSMC migration and injury repair were examined by scratch-wound and epidermal growth factor (EGF)-induced migration assays. Cross-sectional images of normal human bronchi revealed that primary cilia of HBSMCs within each ASM bundle aggregated at the same horizontal level, forming a "cilium layer." Individual cilia of HBSMCs projected into extracellular matrix and exhibited varying degrees of deflection. Mechanochemical sensing molecules, polycystins, and alpha2-, alpha5-, and beta1-integrins were enriched in cilia, as was EGF receptor, known to activate jointly with integrins during cell migration. Migration assays demonstrated a ciliary contribution to HBSMC migration and wound repair. The primary cilia of ASM cells exert a role in sensing and transducing extracellular mechanochemical signals and in ASM injury repair. Defects in ASM ciliary function could potentially affect airway wall maintenance and/or remodeling, possibly relating to the genesis of bronchiectasis in autosomal dominant polycystic kidney disease, a disease of ciliopathy.

Cell wall-anchored nuclease of Streptococcus sanguinis contributes to escape from neutrophil extracellular trap-mediated bacteriocidal activity.

PubMed

Morita, Chisato; Sumioka, Ryuichi; Nakata, Masanobu; Okahashi, Nobuo; Wada, Satoshi; Yamashiro, Takashi; Hayashi, Mikako; Hamada, Shigeyuki; Sumitomo, Tomoko; Kawabata, Shigetada

2014-01-01

Streptococcus sanguinis, a member of the commensal mitis group of streptococci, is a primary colonizer of the tooth surface, and has been implicated in infectious complications including bacteremia and infective endocarditis. During disease progression, S. sanguinis may utilize various cell surface molecules to evade the host immune system to survive in blood. In the present study, we discovered a novel cell surface nuclease with a cell-wall anchor domain, termed SWAN (streptococcal wall-anchored nuclease), and investigated its contribution to bacterial resistance against the bacteriocidal activity of neutrophil extracellular traps (NETs). Recombinant SWAN protein (rSWAN) digested multiple forms of DNA including NET DNA and human RNA, which required both Mg(2+) and Ca(2+) for optimum activity. Furthermore, DNase activity of S. sanguinis was detected around growing colonies on agar plates containing DNA. In-frame deletion of the swan gene mostly reduced that activity. These findings indicated that SWAN is a major nuclease displayed on the surface, which was further confirmed by immuno-detection of SWAN in the cell wall fraction. The sensitivity of S. sanguinis to NET killing was reduced by swan gene deletion. Moreover, heterologous expression of the swan gene rendered a Lactococcus lactis strain more resistant to NET killing. Our results suggest that the SWAN nuclease on the bacterial surface contributes to survival in the potential situation of S. sanguinis encountering NETs during the course of disease progression.

Cell Wall-Anchored Nuclease of Streptococcus sanguinis Contributes to Escape from Neutrophil Extracellular Trap-Mediated Bacteriocidal Activity

PubMed Central

Nakata, Masanobu; Okahashi, Nobuo; Wada, Satoshi; Yamashiro, Takashi; Hayashi, Mikako; Hamada, Shigeyuki; Sumitomo, Tomoko; Kawabata, Shigetada

2014-01-01

Streptococcus sanguinis, a member of the commensal mitis group of streptococci, is a primary colonizer of the tooth surface, and has been implicated in infectious complications including bacteremia and infective endocarditis. During disease progression, S. sanguinis may utilize various cell surface molecules to evade the host immune system to survive in blood. In the present study, we discovered a novel cell surface nuclease with a cell-wall anchor domain, termed SWAN (streptococcal wall-anchored nuclease), and investigated its contribution to bacterial resistance against the bacteriocidal activity of neutrophil extracellular traps (NETs). Recombinant SWAN protein (rSWAN) digested multiple forms of DNA including NET DNA and human RNA, which required both Mg2+ and Ca2+ for optimum activity. Furthermore, DNase activity of S. sanguinis was detected around growing colonies on agar plates containing DNA. In-frame deletion of the swan gene mostly reduced that activity. These findings indicated that SWAN is a major nuclease displayed on the surface, which was further confirmed by immuno-detection of SWAN in the cell wall fraction. The sensitivity of S. sanguinis to NET killing was reduced by swan gene deletion. Moreover, heterologous expression of the swan gene rendered a Lactococcus lactis strain more resistant to NET killing. Our results suggest that the SWAN nuclease on the bacterial surface contributes to survival in the potential situation of S. sanguinis encountering NETs during the course of disease progression. PMID:25084357

Infrared nanospectroscopy reveals the chemical nature of pit membranes in water-conducting cells of the plant xylem.

PubMed

Pereira, Luciano; Flores-Borges, Denisele; Bittencourt, Paulo; Mayer, Juliana; Kiyota, Eduardo; Araújo, Pedro; Jansen, Steven; Freitas, Raul; Oliveira, Rafael; Mazzafera, Paulo

2018-06-05

In the xylem of angiosperm plants, microscopic pits through the secondary cell walls connect the water-conducting vessels. Cellulosic meshes originated from primary walls and middle lamella between adjacent vessels, called pit membrane, separates one conduit from another. The intricate structure of the nano-sized pores in pit membranes enables the passage of water under negative pressure without hydraulic failure due to obstruction by gas bubbles (i.e., embolism) under normal conditions or mild drought stress. Since the chemical composition of pit membranes affects embolism formation and bubble behavior, we directly measured pit membrane composition in Populus nigra wood. Here, we characterized the chemical composition of cell wall structures by synchrotron infrared nanospectroscopy and atomic force microscopy-infrared nanospectroscopy with high spatial resolution. Characteristic peaks of cellulose, phenolic compounds, and proteins were found in the intervessel pit membrane of P. nigra wood. In addition, vessel to parenchyma pit membranes and developing cell walls of the vascular cambium showed clear signals of cellulose, proteins, and pectin. We did not find a distinct peak of lignin and other compounds in these structures. Our investigation of the complex chemical composition of intervessel pit membranes furthers our understanding of the flow of water and bubbles between neighboring conduits. The advances presented here pave the way for further label-free studies related to the nano-chemistry of plant cell components. {copyright, serif} 2018 American Society of Plant Biologists. All rights reserved.

Effects of Fe and Mn deficiencies on the protein profiles of tomato (Solanum lycopersicum) xylem sap as revealed by shotgun analyses.

PubMed

Ceballos-Laita, Laura; Gutierrez-Carbonell, Elain; Takahashi, Daisuke; Abadía, Anunciación; Uemura, Matsuo; Abadía, Javier; López-Millán, Ana Flor

2018-01-06

The aim of this work was to study the effects of Fe and Mn deficiencies on the xylem sap proteome of tomato using a shotgun proteomic approach, with the final goal of elucidating plant response mechanisms to these stresses. This approach yielded 643 proteins reliably identified and quantified with 70% of them predicted as secretory. Iron and Mn deficiencies caused statistically significant and biologically relevant abundance changes in 119 and 118 xylem sap proteins, respectively. In both deficiencies, metabolic pathways most affected were protein metabolism, stress/oxidoreductases and cell wall modifications. First, results suggest that Fe deficiency elicited more stress responses than Mn deficiency, based on the changes in oxidative and proteolytic enzymes. Second, both nutrient deficiencies affect the secondary cell wall metabolism, with changes in Fe deficiency occurring via peroxidase activity, and in Mn deficiency involving peroxidase, Cu-oxidase and fasciclin-like arabinogalactan proteins. Third, the primary cell wall metabolism was affected by both nutrient deficiencies, with changes following opposite directions as judged from the abundances of several glycoside-hydrolases with endo-glycolytic activities and pectin esterases. Fourth, signaling pathways via xylem involving CLE and/or lipids as well as changes in phosphorylation and N-glycosylation also play a role in the responses to these stresses. Biological significance In spite of being essential for the delivery of nutrients to the shoots, our knowledge of xylem responses to nutrient deficiencies is very limited. The present work applies a shotgun proteomic approach to unravel the effects of Fe and Mn deficiencies on the xylem sap proteome. Overall, Fe deficiency seems to elicit more stress in the xylem sap proteome than Mn deficiency, based on the changes measured in proteolytic and oxido-reductase proteins, whereas both nutrients exert modifications in the composition of the primary and secondary cell wall. Cell wall modifications could affect the mechanical and permeability properties of the xylem sap vessels, and therefore ultimately affect solute transport and distribution to the leaves. Results also suggest that signaling cascades involving lipid and peptides might play a role in nutrient stress signaling and pinpoint interesting candidates for future studies. Finally, both nutrient deficiencies seem to affect phosphorylation and glycosylation processes, again following an opposite pattern. Copyright © 2017 Elsevier B.V. All rights reserved.

Evidence for in vitro binding of pectin side chains to cellulose.

PubMed

Zykwinska, Agata W; Ralet, Marie-Christine J; Garnier, Catherine D; Thibault, Jean-François J

2005-09-01

Pectins of varying structures were tested for their ability to interact with cellulose in comparison to the well-known adsorption of xyloglucan. Our results reveal that sugar beet (Beta vulgaris) and potato (Solanum tuberosum) pectins, which are rich in neutral sugar side chains, can bind in vitro to cellulose. The extent of binding varies with respect to the nature and structure of the side chains. Additionally, branched arabinans (Br-Arabinans) or debranched arabinans (Deb-Arabinans; isolated from sugar beet) and galactans (isolated from potato) were shown bind to cellulose microfibrils. The adsorption of Br-Arabinan and galactan was lower than that of Deb-Arabinan. The maximum adsorption affinity of Deb-Arabinan to cellulose was comparable to that of xyloglucan. The study of sugar beet and potato alkali-treated cell walls supports the hypothesis of pectin-cellulose interaction. Natural composites enriched in arabinans or galactans and cellulose were recovered. The binding of pectins to cellulose microfibrils may be of considerable significance in the modeling of primary cell walls of plants as well as in the process of cell wall assembly.

Dynamics of biomass partitioning, stem gene expression, cell wall biosynthesis, and sucrose accumulation during development of Sorghum bicolor.

PubMed

McKinley, Brian; Rooney, William; Wilkerson, Curtis; Mullet, John

2016-11-01

Biomass accumulated preferentially in leaves of the sweet sorghum Della until floral initiation, then stems until anthesis, followed by panicles until grain maturity, and apical tillers. Sorghum stem RNA-seq transcriptome profiles and composition data were collected for approximately 100 days of development beginning at floral initiation. The analysis identified >200 differentially expressed genes involved in stem growth, cell wall biology, and sucrose accumulation. Genes encoding expansins and xyloglucan endotransglucosylase/hydrolases were differentially expressed in growing stem internodes. Genes encoding enzymes involved in the synthesis of cellulose, lignin, and glucuronoarabinoxylan were expressed at elevated levels in stems until approximately 7 days before anthesis and then down-regulated. CESA genes involved in primary and secondary cell wall synthesis showed different temporal patterns of expression. Following floral initiation, the level of sucrose and other non-structural carbohydrates increased to approximately 50% of the stem's dry weight. Stem sucrose accumulation was inversely correlated with >100-fold down-regulation of SbVIN1, a gene encoding a vacuolar invertase. Accumulation of stem sucrose was also correlated with cessation of leaf and stem growth at anthesis, decreased expression of genes involved in stem cell wall synthesis, and approximately 10-fold lower expression of SbSUS4, a gene encoding sucrose synthase that generates UDP-glucose from sucrose for cell wall biosynthesis. Genes for mixed linkage glucan synthesis (CSLF) and turnover were expressed at high levels in stems throughout development. Overall, the stem transcription profile resource and the genes and regulatory dynamics identified in this study will be useful for engineering sorghum stem composition for improved conversion to biofuels and bio-products. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

Isolation and Proteomic Characterization of the Arabidopsis Golgi Defines Functional and Novel Components Involved in Plant Cell Wall Biosynthesis1[W][OA

PubMed Central

Parsons, Harriet T.; Christiansen, Katy; Knierim, Bernhard; Carroll, Andrew; Ito, Jun; Batth, Tanveer S.; Smith-Moritz, Andreia M.; Morrison, Stephanie; McInerney, Peter; Hadi, Masood Z.; Auer, Manfred; Mukhopadhyay, Aindrila; Petzold, Christopher J.; Scheller, Henrik V.; Loqué, Dominique; Heazlewood, Joshua L.

2012-01-01

The plant Golgi plays a pivotal role in the biosynthesis of cell wall matrix polysaccharides, protein glycosylation, and vesicle trafficking. Golgi-localized proteins have become prospective targets for reengineering cell wall biosynthetic pathways for the efficient production of biofuels from plant cell walls. However, proteomic characterization of the Golgi has so far been limited, owing to the technical challenges inherent in Golgi purification. In this study, a combination of density centrifugation and surface charge separation techniques have allowed the reproducible isolation of Golgi membranes from Arabidopsis (Arabidopsis thaliana) at sufficiently high purity levels for in-depth proteomic analysis. Quantitative proteomic analysis, immunoblotting, enzyme activity assays, and electron microscopy all confirm high purity levels. A composition analysis indicated that approximately 19% of proteins were likely derived from contaminating compartments and ribosomes. The localization of 13 newly assigned proteins to the Golgi using transient fluorescent markers further validated the proteome. A collection of 371 proteins consistently identified in all replicates has been proposed to represent the Golgi proteome, marking an appreciable advancement in numbers of Golgi-localized proteins. A significant proportion of proteins likely involved in matrix polysaccharide biosynthesis were identified. The potential within this proteome for advances in understanding Golgi processes has been demonstrated by the identification and functional characterization of the first plant Golgi-resident nucleoside diphosphatase, using a yeast complementation assay. Overall, these data show key proteins involved in primary cell wall synthesis and include a mixture of well-characterized and unknown proteins whose biological roles and importance as targets for future research can now be realized. PMID:22430844

Hoxb2 and hoxb4 act together to specify ventral body wall formation.

PubMed

Manley, N R; Barrow, J R; Zhang, T; Capecchi, M R

2001-09-01

Three different alleles of the Hoxb4 locus were generated by gene targeting in mice. Two alleles contain insertions of a selectable marker in the first exon in either orientation, and, in the third, the selectable marker was removed, resulting in premature termination of the protein. Presence and orientation of the selectable marker correlated with the severity of the phenotype, indicating that the selectable marker induces cis effects on neighboring genes that influence the phenotype. Homozygous mutants of all alleles had cervical skeletal defects similar to those previously reported for Hoxb4 mutant mice. In the most severe allele, Hoxb4(PolII), homozygous mutants died either in utero at approximately E15.5 or immediately after birth, with a severe defect in ventral body wall formation. Analysis of embryos showed thinning of the primary ventral body wall in mutants relative to control animals at E11.5, before secondary body wall formation. Prior to this defect, both Alx3 and Alx4 were specifically down regulated in the most ventral part of the primary body wall in Hoxb4(PolII) mutants. Hoxb4(loxp) mutants in which the neo gene has been removed did not have body wall or sternum defects. In contrast, both the Hoxb4(PolII) and the previously described Hoxb2(PolII) alleles that have body wall defects have been shown to disrupt the expression of both Hoxb2 and Hoxb4 in cell types that contribute to body wall formation. Our results are consistent with a model in which defects in ventral body wall formation require the simultaneous loss of at least Hoxb2 and Hoxb4, and may involve Alx3 and Alx4. Copyright 2001 Academic Press.

Towards Mechanistic Understanding of Mercury Availability and Toxicity to Aquatic Primary Producers.

PubMed

Dranguet, Perrine; Flück, Rebecca; Regier, Nicole; Cosio, Claudia; Le Faucheur, Séverine; Slaveykova, Vera I

2014-11-01

The present article reviews current knowledge and recent progress on the bioavailability and toxicity of mercury to aquatic primary producers. Mercury is a ubiquitous toxic trace element of global concern. At the base of the food web, primary producers are central for mercury incorporation into the food web. Here, the emphasis is on key, but still poorly understood, processes governing the interactions between mercury species and phytoplankton, and macrophytes, two representatives of primary producers. Mass transfer to biota surface, adsorption to cell wall, internalization and release from cells, as well as underlying toxicity mechanisms of both inorganic mercury and methylmercury are discussed critically. In addition, the intracellular distribution and transformation processes, their importance for mercury toxicity, species-sensitivity differences and trophic transfer are presented. The mini-review is illustrated with examples of our own research.

Ellipsoidal cell flow system

DOEpatents

Salzman, Gary C.; Mullaney, Paul F.

1976-01-01

The disclosure relates to a system incorporating an ellipsoidal flow chamber having light reflective walls for low level light detection in practicing cellular analysis. The system increases signal-to-noise ratio by a factor of ten over prior art systems. In operation, laser light passes through the primary focus of the ellipsoid. A controlled flow of cells simultaneously passes through this focus so that the laser light impinges on the cells and is modulated by the cells. The reflective walls of the ellipsoid reflect the cell-modulated light to the secondary focus of the ellipsoid. A tapered light guide at the secondary focus picks up a substantial portion of modulated reflective light and directs it onto a light detector to produce a signal. The signal is processed to obtain the intensity distribution of the modulated light and hence sought after characteristics of the cells. In addition, cells may be dyed so as to fluoresce in response to the laser light and their fluorescence may be processed as cell-modulated light above described. A light discriminating filter would be used to distinguish reflected modulated laser light from reflected fluorescent light.

Breast Cancer Research at NASA

NASA Technical Reports Server (NTRS)

1998-01-01

Human primary breast tumor cells after 49 days of growth in a NASA Bioreactor. Tumor cells aggregate on microcarrier beads (indicated by arrow). NASA's Marshall Space Flight Center (MSFC) is sponsoring research with Bioreactors, rotating wall vessels designed to grow tissue samples in space, to understand how breast cancer works. This ground-based work studies the growth and assembly of human mammary epithelial cell (HMEC) from breast cancer susceptible tissue. Radiation can make the cells cancerous, thus allowing better comparisons of healthy vs. tunorous tissue. Credit: Dr. Jearne Becker, University of South Florida

Architecture of dermatophyte cell Walls: Electron microscopic and biochemical analysis

NASA Technical Reports Server (NTRS)

Nozawa, Y.; Kitajima, Y.

1984-01-01

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

Engineering secondary cell wall deposition in plants

PubMed Central

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

2013-01-01

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

Neutron Scattering Studies of Nano-Scale Wood-Water Interactions

NASA Astrophysics Data System (ADS)

Plaza Rodriguez, Nayomi Z.

Understanding and controlling water in wood is critical to both improving forest products moisture durability and developing new sustainable forest products-based technologies. While wood is known to be hygroscopic, there is still a lack of understanding on the nanoscale wood-water interactions necessary for increased moisture-durability and dimensional stability. My PhD thesis focuses on the development and implementation of neutron scattering methods that can provide insight on both the structural and dynamical changes associated with these interactions so that products with improved moisture durability can be developed efficiently. Using small angle neutron scattering (SANS) and a custom-built in situ relative humidity chamber I studied the anisotropic moisture-induced swelling of wood nanostructure. First, I studied the effects of sample preparation by comparing SANS patterns of wiley milled wood and intact latewood cell walls, and found that scattering from intact wood provide more information about the spatial arrangement of the wood nanostructures inside the cell wall. Comparisons between SANS patterns from earlywood and latewood, also showed that the higher cell wall density of latewood cell walls results in patterns with more pronounced anisotropic features. Then, by measuring latewood loblolly pine sections obtained from the same growth ring and prepared in each of the primary wood planes, I tracked the cellulose elementary fibril spacing as a function of humidity in both intact and partially cut cell walls. These studies showed that even though swelling at the elementary fibril spacing is responsible for the majority of the transverse swelling observed at the S2 level, it is not primary plane dependent. Additionally, there were no differences in the elementary fibril spacing between partially-cut and intact cell walls, except at high humidity where the spacing in partially-cut cells was higher. SANS was also used to study the effects of two chemical modifications, namely, adhesive infiltration and acetylation, on the wood nanostructure as well as its moisture-induced swelling. Tangential-longitudinal latewood loblolly pine 0.5 mm thick sections were acetylated or treated with an adhesive (Phenol-formaldehyde (PF) or polymeric methylene diisocyanate (pMDI)) using deuterated or hydrogenated chemicals. Contrast variation experiments on wood modified with deuterated chemicals revealed that PF can infiltrate the regions between the elementary fibrils, while acetylation does not. The moisture-induced swelling of the chemically modified wood was studied, by studying the samples modified with hydrogenated chemicals using SANS and the previously built humidity chamber. These studies revealed that while both PF and pMDI can infiltrate the microfibrils, only PF reduced significantly the swelling at both the elementary fibril and bulk levels. In acetylated samples, the elementary fibril spacing was proportional to the moisture-content of the sample, which was reduced with increasing acetylation. This suggested that the acetylation treatment did not reduce the swelling at the elementary fibril but prevented water from entering the microfibril by modifying the regions surrounding the elementary fibrils. Using quasi-elastic neutron scattering (QENS) and a custom-built in situ relative humidity sample environment I measured experimentally the (5 - 400 ps) water dynamics inside wood cell walls for the first time and found that there are two types of bound water in the cell wall, namely, slow and fast water. The motion of both water types is well described by a jump-diffusion model, which corresponds to water molecules whose movement follows a stop and go process. Here, the slow water corresponds to water molecules that are highly associated to the wood polymers, whereas the fast water corresponds to water confined inside nanopores within the wood cell wall.

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

PubMed Central

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

2016-01-01

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

Turning the Table: Plants Consume Microbes as a Source of Nutrients

PubMed Central

Paungfoo-Lonhienne, Chanyarat; Rentsch, Doris; Robatzek, Silke; Webb, Richard I.; Sagulenko, Evgeny; Näsholm, Torgny

2010-01-01

Interactions between plants and microbes in soil, the final frontier of ecology, determine the availability of nutrients to plants and thereby primary production of terrestrial ecosystems. Nutrient cycling in soils is considered a battle between autotrophs and heterotrophs in which the latter usually outcompete the former, although recent studies have questioned the unconditional reign of microbes on nutrient cycles and the plants' dependence on microbes for breakdown of organic matter. Here we present evidence indicative of a more active role of plants in nutrient cycling than currently considered. Using fluorescent-labeled non-pathogenic and non-symbiotic strains of a bacterium and a fungus (Escherichia coli and Saccharomyces cerevisiae, respectively), we demonstrate that microbes enter root cells and are subsequently digested to release nitrogen that is used in shoots. Extensive modifications of root cell walls, as substantiated by cell wall outgrowth and induction of genes encoding cell wall synthesizing, loosening and degrading enzymes, may facilitate the uptake of microbes into root cells. Our study provides further evidence that the autotrophy of plants has a heterotrophic constituent which could explain the presence of root-inhabiting microbes of unknown ecological function. Our discovery has implications for soil ecology and applications including future sustainable agriculture with efficient nutrient cycles. PMID:20689833

Transcriptome profiling of Pinus radiata juvenile wood with contrasting stiffness identifies putative candidate genes involved in microfibril orientation and cell wall mechanics

PubMed Central

2011-01-01

Background The mechanical properties of wood are largely determined by the orientation of cellulose microfibrils in secondary cell walls. Several genes and their allelic variants have previously been found to affect microfibril angle (MFA) and wood stiffness; however, the molecular mechanisms controlling microfibril orientation and mechanical strength are largely uncharacterised. In the present study, cDNA microarrays were used to compare gene expression in developing xylem with contrasting stiffness and MFA in juvenile Pinus radiata trees in order to gain further insights into the molecular mechanisms underlying microfibril orientation and cell wall mechanics. Results Juvenile radiata pine trees with higher stiffness (HS) had lower MFA in the earlywood and latewood of each ring compared to low stiffness (LS) trees. Approximately 3.4 to 14.5% out of 3, 320 xylem unigenes on cDNA microarrays were differentially regulated in juvenile wood with contrasting stiffness and MFA. Greater variation in MFA and stiffness was observed in earlywood compared to latewood, suggesting earlywood contributes most to differences in stiffness; however, 3-4 times more genes were differentially regulated in latewood than in earlywood. A total of 108 xylem unigenes were differentially regulated in juvenile wood with HS and LS in at least two seasons, including 43 unigenes with unknown functions. Many genes involved in cytoskeleton development and secondary wall formation (cellulose and lignin biosynthesis) were preferentially transcribed in wood with HS and low MFA. In contrast, several genes involved in cell division and primary wall synthesis were more abundantly transcribed in LS wood with high MFA. Conclusions Microarray expression profiles in Pinus radiata juvenile wood with contrasting stiffness has shed more light on the transcriptional control of microfibril orientation and the mechanical properties of wood. The identified candidate genes provide an invaluable resource for further gene function and association genetics studies aimed at deepening our understanding of cell wall biomechanics with a view to improving the mechanical properties of wood. PMID:21962175

Characterization of the Sclerotinia sclerotiorum cell wall proteome.

PubMed

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.

Microgravity

NASA Image and Video Library

1998-10-10

High magnification view of human primary breast tumor cells after 56 days of culture in a NASA Bioreactor. The arrow points to bead surface indicating breast cancer cells (as noted by the staining of tumor cell intermediate filaments). NASA's Marshall Space Flight Center (MSFC) is sponsoring research with Bioreactors, rotating wall vessels designed to grow tissue samples in space, to understand how breast cancer works. This ground-based work studies the growth and assembly of human mammary epithelial cell (HMEC) from breast cancer susceptible tissue. Radiation can make the cells cancerous, thus allowing better comparisons of healthy vs. tunorous tissue. Credit: Dr. Jearne Becker, University of South Florida

Three-dimensional wet-electrospun poly(lactic acid)/multi-wall carbon nanotubes scaffold induces differentiation of human menstrual blood-derived stem cells into germ-like cells.

PubMed

Eyni, Hossein; Ghorbani, Sadegh; Shirazi, Reza; Salari Asl, Leila; P Beiranvand, Shahram; Soleimani, Masoud

2017-09-01

Infertility caused by the disruption or absence of germ cells is a major and largely incurable medical problem. Germ cells (i.e., sperm or egg) play a key role in the transmission of genetic and epigenetic information across generations. Generation of gametes derived in vitro from stem cells hold promising prospects which could potentially help infertile men and women. Menstrual blood-derived stem cells are a unique stem cell source. Evidence suggests that menstrual blood-derived stem cells exhibit a multi-lineage potential and have attracted extensive attention in regenerative medicine. To maintain the three-dimensional structure of natural extra cellular matrices in vitro, scaffolds can do this favor and mimic a microenvironment for cell proliferation and differentiation. According to previous studies, poly(lactic acid) and multi-wall carbon nanotubes have been introduced as novel and promising biomaterials for the proliferation and differentiation of stem cells. Some cell types have been successfully grown on a matrix containing carbon nanotubes in tissue engineering but there is no report for this material to support stem cells differentiation into germ cells lineage. This study designed a 3D wet-electrospun poly(lactic acid) and poly(lactic acid)/multi-wall carbon nanotubes composite scaffold to compare infiltration, proliferation, and differentiation potential of menstrual blood-derived stem cells toward germ cell lineage with 2D culture. Our primary data revealed that the fabricated scaffold has mechanical and biological suitable qualities for supporting and attachments of stem cells. The differentiated menstrual blood-derived stem cells tracking in scaffolds using scanning electron microscopy confirmed cell attachment, aggregation, and distribution on the porous scaffold. Based on the differentiation assay by RT-PCR analysis, stem cells and germ-like cells markers were expressed in 3D groups as well as 2D one. It seems that poly(lactic acid)/multi-wall carbon nanotubes scaffold-seeded menstrual blood-derived stem cells could be viewed as a novel, safe, and accessible construct for these cells, as they enhance germ-like generation from menstrual blood-derived stem cells.

The Role of Auxin in Cell Wall Expansion

PubMed Central

2018-01-01

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. PMID:29565829

The Role of Auxin in Cell Wall Expansion.

PubMed

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.

Cell Wall Remodeling Enzymes Modulate Fungal Cell Wall Elasticity and Osmotic Stress Resistance

PubMed Central

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

2015-01-01

ABSTRACT The fungal cell wall confers cell morphology and protection against environmental insults. For fungal pathogens, the cell wall is a key immunological modulator and an ideal therapeutic target. Yeast cell walls possess an inner matrix of interlinked β-glucan and chitin that is thought to provide tensile strength and rigidity. Yeast cells remodel their walls over time in response to environmental change, a process controlled by evolutionarily conserved stress (Hog1) and cell integrity (Mkc1, Cek1) signaling pathways. These mitogen-activated protein kinase (MAPK) pathways modulate cell wall gene expression, leading to the construction of a new, modified cell wall. We show that the cell wall is not rigid but elastic, displaying rapid structural realignments that impact survival following osmotic shock. Lactate-grown Candida albicans cells are more resistant to hyperosmotic shock than glucose-grown cells. We show that this elevated resistance is not dependent on Hog1 or Mkc1 signaling and that most cell death occurs within 10 min of osmotic shock. Sudden decreases in cell volume drive rapid increases in cell wall thickness. The elevated stress resistance of lactate-grown cells correlates with reduced cell wall elasticity, reflected in slower changes in cell volume following hyperosmotic shock. The cell wall elasticity of lactate-grown cells is increased by a triple mutation that inactivates the Crh family of cell wall cross-linking enzymes, leading to increased sensitivity to hyperosmotic shock. Overexpressing Crh family members in glucose-grown cells reduces cell wall elasticity, providing partial protection against hyperosmotic shock. These changes correlate with structural realignment of the cell wall and with the ability of cells to withstand osmotic shock. PMID:26220968

The growing outer epidermal wall: design and physiological role of a composite structure.

PubMed

Kutschera, U

2008-04-01

The cells of growing plant organs secrete an extracellular fibrous composite (the primary wall) that allows the turgid protoplasts to expand irreversibly via wall-yielding events, which are regulated by processes within the cytoplasm. The role of the epidermis in the control of stem elongation is described with special reference to the outer epidermal wall (OEW), which forms a 'tensile skin'. The OEW is much thicker and less extensible than the walls of the inner tissues. Moreover, in the OEW the amount of cellulose per unit wall mass is considerably greater than in the inner tissues. Ultrastructural studies have shown that the expanding OEW is composed of a highly ordered internal and a diffuse outer half, with helicoidally organized cellulose microfibrils in the inner (load-bearing) region of this tension-stressed organ wall. The structural and mechanical backbone of the wall consists of helicoids, i.e. layers of parallel, inextensible cellulose microfibrils. These 'plywood laminates' contain crystalline 'cables' orientated in all directions with respect to the axis of elongation (isotropic material). Cessation of cell elongation is accompanied by a loss of order, i.e. the OEW is a dynamic structure. Helicoidally arranged extracellular polymers have also been found in certain bacteria, algae, fungi and animals. In the insect cuticle crystalline cutin nanofibrils form characteristic 'OEW-like' herringbone patterns. Theoretical considerations, in vitro studies and computer simulations suggest that extracellular biological helicoids form by directed self-assembly of the crystalline biopolymers. This spontaneous generation of complex design 'without an intelligent designer' evolved independently in the protective 'skin' of plants, animals and many other organisms.

Application of the 2-cyanoacetamide method for spectrophotometric assay of cellulase enzyme activity

USDA-ARS?s Scientific Manuscript database

Cellulose is the most abundant form of carbon on the planet. Breakdown of cellulose microfibrils in the plant cell wall is a means by which microbes gain ingress into their respective hosts. Cellulose degradation is also important for global carbon recycling and is the primary substrate for producti...

Cell Wall Remodeling Enzymes Modulate Fungal Cell Wall Elasticity and Osmotic Stress Resistance.

PubMed

Ene, Iuliana V; Walker, Louise A; Schiavone, Marion; Lee, Keunsook K; Martin-Yken, Hélène; Dague, Etienne; Gow, Neil A R; Munro, Carol A; Brown, Alistair J P

2015-07-28

The fungal cell wall confers cell morphology and protection against environmental insults. For fungal pathogens, the cell wall is a key immunological modulator and an ideal therapeutic target. Yeast cell walls possess an inner matrix of interlinked β-glucan and chitin that is thought to provide tensile strength and rigidity. Yeast cells remodel their walls over time in response to environmental change, a process controlled by evolutionarily conserved stress (Hog1) and cell integrity (Mkc1, Cek1) signaling pathways. These mitogen-activated protein kinase (MAPK) pathways modulate cell wall gene expression, leading to the construction of a new, modified cell wall. We show that the cell wall is not rigid but elastic, displaying rapid structural realignments that impact survival following osmotic shock. Lactate-grown Candida albicans cells are more resistant to hyperosmotic shock than glucose-grown cells. We show that this elevated resistance is not dependent on Hog1 or Mkc1 signaling and that most cell death occurs within 10 min of osmotic shock. Sudden decreases in cell volume drive rapid increases in cell wall thickness. The elevated stress resistance of lactate-grown cells correlates with reduced cell wall elasticity, reflected in slower changes in cell volume following hyperosmotic shock. The cell wall elasticity of lactate-grown cells is increased by a triple mutation that inactivates the Crh family of cell wall cross-linking enzymes, leading to increased sensitivity to hyperosmotic shock. Overexpressing Crh family members in glucose-grown cells reduces cell wall elasticity, providing partial protection against hyperosmotic shock. These changes correlate with structural realignment of the cell wall and with the ability of cells to withstand osmotic shock. The C. albicans cell wall is the first line of defense against external insults, the site of immune recognition by the host, and an attractive target for antifungal therapy. Its tensile strength is conferred by a network of cell wall polysaccharides, which are remodeled in response to growth conditions and environmental stress. However, little is known about how cell wall elasticity is regulated and how it affects adaptation to stresses such as sudden changes in osmolarity. We show that elasticity is critical for survival under conditions of osmotic shock, before stress signaling pathways have time to induce gene expression and drive glycerol accumulation. Critical cell wall remodeling enzymes control cell wall flexibility, and its regulation is strongly dependent on host nutritional inputs. We also demonstrate an entirely new level of cell wall dynamism, where significant architectural changes and structural realignment occur within seconds of an osmotic shock. Copyright © 2015 Ene et al.

Synchronous gallbladder squamous cell carcinoma and adenocarcinoma, both as primary tumors in one patient.

PubMed

Vahedi, Amir; Azimpouran, Mahzad; Ghavidel, Ali; Karbasi, Mahsa; Farhadi, Mehrdad

2018-01-01

Synchronous primary carcinomas of gallbladder are extremely rare. In this paper, we report a case of double primary carcinomas in gallbladder CASE REPORT: A 65 year old male was admitted to the hospital for surgical removal of gallbladder, which was diagnosed as cholecystitis in ultrasonography. Macroscopic examination disclosed a single whitish mass in gallbladder neck and another distinct mass in the fundus as wall thickening. Pathologic findings revealed squamous cell carcinoma of the neck and adenocarcinoma in the fundus. This study represents an example of misdiagnosis. Being cautious is mandatory in order to manage the patient properly. Synchronous primary carcinomas of gallbladder are rare. However this diagnosis should be taken into account in patients with cholecystitis features in order to seeking for the best surgical approach. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Activation tagging of Arabidopsis POLYGALACTURONASE INVOLVED IN EXPANSION2 promotes hypocotyl elongation, leaf expansion, stem lignification, mechanical stiffening, and lodging.

PubMed

Xiao, Chaowen; Barnes, William J; Zamil, M Shafayet; Yi, Hojae; Puri, Virendra M; Anderson, Charles T

2017-03-01

Pectin is the most abundant component of primary cell walls in eudicot plants. The modification and degradation of pectin affects multiple processes during plant development, including cell expansion, organ initiation, and cell separation. However, the extent to which pectin degradation by polygalacturonases affects stem development and secondary wall formation remains unclear. Using an activation tag screen, we identified a transgenic Arabidopsis thaliana line with longer etiolated hypocotyls, which overexpresses a gene encoding a polygalacturonase. We designated this gene as POLYGALACTURONASE INVOLVED IN EXPANSION2 (PGX2), and the corresponding activation tagged line as PGX2 AT . PGX2 is widely expressed in young seedlings and in roots, stems, leaves, flowers, and siliques of adult plants. PGX2-GFP localizes to the cell wall, and PGX2 AT plants show higher total polygalacturonase activity and smaller pectin molecular masses than wild-type controls, supporting a function for this protein in apoplastic pectin degradation. A heterologously expressed, truncated version of PGX2 also displays polygalacturonase activity in vitro. Like previously identified PGX1 AT plants, PGX2 AT plants have longer hypocotyls and larger rosette leaves, but they also uniquely display early flowering, earlier stem lignification, and lodging stems with enhanced mechanical stiffness that is possibly due to decreased stem thickness. Together, these results indicate that PGX2 both functions in cell expansion and influences secondary wall formation, providing a possible link between these two developmental processes. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

A single heterologously expressed plant cellulose synthase isoform is sufficient for cellulose microfibril formation in vitro

PubMed Central

Purushotham, Pallinti; Cho, Sung Hyun; Díaz-Moreno, Sara M.; Kumar, Manish; Nixon, B. Tracy; Bulone, Vincent; Zimmer, Jochen

2016-01-01

Plant cell walls are a composite material of polysaccharides, proteins, and other noncarbohydrate polymers. In the majority of plant tissues, the most abundant polysaccharide is cellulose, a linear polymer of glucose molecules. As the load-bearing component of the cell wall, individual cellulose chains are frequently bundled into micro and macrofibrils and are wrapped around the cell. Cellulose is synthesized by membrane-integrated and processive glycosyltransferases that polymerize UDP-activated glucose and secrete the nascent polymer through a channel formed by their own transmembrane regions. Plants express several different cellulose synthase isoforms during primary and secondary cell wall formation; however, so far, none has been functionally reconstituted in vitro for detailed biochemical analyses. Here we report the heterologous expression, purification, and functional reconstitution of Populus tremula x tremuloides CesA8 (PttCesA8), implicated in secondary cell wall formation. The recombinant enzyme polymerizes UDP-activated glucose to cellulose, as determined by enzyme degradation, permethylation glycosyl linkage analysis, electron microscopy, and mutagenesis studies. Catalytic activity is dependent on the presence of a lipid bilayer environment and divalent manganese cations. Further, electron microscopy analyses reveal that PttCesA8 produces cellulose fibers several micrometers long that occasionally are capped by globular particles, likely representing PttCesA8 complexes. Deletion of the enzyme’s N-terminal RING-finger domain almost completely abolishes fiber formation but not cellulose biosynthetic activity. Our results demonstrate that reconstituted PttCesA8 is not only sufficient for cellulose biosynthesis in vitro but also suffices to bundle individual glucan chains into cellulose microfibrils. PMID:27647898

A single heterologously expressed plant cellulose synthase isoform is sufficient for cellulose microfibril formation in vitro.

PubMed

Purushotham, Pallinti; Cho, Sung Hyun; Díaz-Moreno, Sara M; Kumar, Manish; Nixon, B Tracy; Bulone, Vincent; Zimmer, Jochen

2016-10-04

Plant cell walls are a composite material of polysaccharides, proteins, and other noncarbohydrate polymers. In the majority of plant tissues, the most abundant polysaccharide is cellulose, a linear polymer of glucose molecules. As the load-bearing component of the cell wall, individual cellulose chains are frequently bundled into micro and macrofibrils and are wrapped around the cell. Cellulose is synthesized by membrane-integrated and processive glycosyltransferases that polymerize UDP-activated glucose and secrete the nascent polymer through a channel formed by their own transmembrane regions. Plants express several different cellulose synthase isoforms during primary and secondary cell wall formation; however, so far, none has been functionally reconstituted in vitro for detailed biochemical analyses. Here we report the heterologous expression, purification, and functional reconstitution of Populus tremula x tremuloides CesA8 (PttCesA8), implicated in secondary cell wall formation. The recombinant enzyme polymerizes UDP-activated glucose to cellulose, as determined by enzyme degradation, permethylation glycosyl linkage analysis, electron microscopy, and mutagenesis studies. Catalytic activity is dependent on the presence of a lipid bilayer environment and divalent manganese cations. Further, electron microscopy analyses reveal that PttCesA8 produces cellulose fibers several micrometers long that occasionally are capped by globular particles, likely representing PttCesA8 complexes. Deletion of the enzyme's N-terminal RING-finger domain almost completely abolishes fiber formation but not cellulose biosynthetic activity. Our results demonstrate that reconstituted PttCesA8 is not only sufficient for cellulose biosynthesis in vitro but also suffices to bundle individual glucan chains into cellulose microfibrils.

Functional analyses of cellulose synthase genes in flax (Linum usitatissimum) by virus-induced gene silencing.

PubMed

Chantreau, Maxime; Chabbert, Brigitte; Billiard, Sylvain; Hawkins, Simon; Neutelings, Godfrey

2015-12-01

Flax (Linum usitatissimum) bast fibres are located in the stem cortex where they play an important role in mechanical support. They contain high amounts of cellulose and so are used for linen textiles and in the composite industry. In this study, we screened the annotated flax genome and identified 14 distinct cellulose synthase (CESA) genes using orthologous sequences previously identified. Transcriptomics of 'primary cell wall' and 'secondary cell wall' flax CESA genes showed that some were preferentially expressed in different organs and stem tissues providing clues as to their biological role(s) in planta. The development for the first time in flax of a virus-induced gene silencing (VIGS) approach was used to functionally evaluate the biological role of different CESA genes in stem tissues. Quantification of transcript accumulation showed that in many cases, silencing not only affected targeted CESA clades, but also had an impact on other CESA genes. Whatever the targeted clade, inactivation by VIGS affected plant growth. In contrast, only clade 1- and clade 6-targeted plants showed modifications in outer-stem tissue organization and secondary cell wall formation. In these plants, bast fibre number and structure were severely impacted, suggesting that the targeted genes may play an important role in the establishment of the fibre cell wall. Our results provide new fundamental information about cellulose biosynthesis in flax that should facilitate future plant improvement/engineering. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

Differential histone modification and protein expression associated with cell wall removal and regeneration in rice (Oryza sativa).

PubMed

Tan, Feng; Zhang, Kangling; Mujahid, Hana; Verma, Desh Pal S; Peng, Zhaohua

2011-02-04

The cell wall is a critical extracellular structure that provides protection and structural support in plant cells. To study the biological function of the cell wall and the regulation of cell wall resynthesis, we examined cellular responses to enzymatic removal of the cell wall in rice (Oryza sativa) suspension cells using proteomic approaches. We find that removal of cell wall stimulates cell wall synthesis from multiple sites in protoplasts instead of from a single site as in cytokinesis. Nucleus DAPI stain and MNase digestion further show that removal of the cell wall is concomitant with substantial chromatin reorganization. Histone post-translational modification studies using both Western blots and isotope labeling assisted quantitative mass spectrometry analyses reveal that substantial histone modification changes, particularly H3K18(AC) and H3K23(AC), are associated with the removal and regeneration of the cell wall. Label-free quantitative proteome analyses further reveal that chromatin associated proteins undergo dramatic changes upon removal of the cell wall, along with cytoskeleton, cell wall metabolism, and stress-response proteins. This study demonstrates that cell wall removal is associated with substantial chromatin change and may lead to stimulation of cell wall synthesis using a novel mechanism.

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

PubMed

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.

Down-regulation of POLYGALACTURONASE1 alters firmness, tensile strength and water loss in apple (Malus x domestica) fruit.

PubMed

Atkinson, Ross G; Sutherland, Paul W; Johnston, Sarah L; Gunaseelan, Kularajathevan; Hallett, Ian C; Mitra, Deepali; Brummell, David A; Schröder, Roswitha; Johnston, Jason W; Schaffer, Robert J

2012-08-02

While there is now a significant body of research correlating apple (Malus x domestica) fruit softening with the cell wall hydrolase ENDO-POLYGALACTURONASE1 (PG1), there is currently little knowledge of its physiological effects in planta. This study examined the effect of down regulation of PG1 expression in 'Royal Gala' apples, a cultivar that typically has high levels of PG1, and softens during fruit ripening. PG1-suppressed 'Royal Gala' apples harvested from multiple seasons were firmer than controls after ripening, and intercellular adhesion was higher. Cell wall analyses indicated changes in yield and composition of pectin, and a higher molecular weight distribution of CDTA-soluble pectin. Structural analyses revealed more ruptured cells and free juice in pulled apart sections, suggesting improved integrity of intercellular connections and consequent cell rupture due to failure of the primary cell walls under stress. PG1-suppressed lines also had reduced expansion of cells in the hypodermis of ripe apples, resulting in more densely packed cells in this layer. This change in morphology appears to be linked with reduced transpirational water loss in the fruit. These findings confirm PG1's role in apple fruit softening and suggests that this is achieved in part by reducing cellular adhesion. This is consistent with previous studies carried out in strawberry but not with those performed in tomato. In apple PG1 also appears to influence other fruit texture characters such as juiciness and water loss.

The N-Linked Outer Chain Mannans and the Dfg5p and Dcw1p Endo-α-1,6-Mannanases Are Needed for Incorporation of Candida albicans Glycoproteins into the Cell Wall

PubMed Central

Ao, Jie; Chinnici, Jennifer L.; Maddi, Abhiram

2015-01-01

A biochemical pathway for the incorporation of cell wall protein into the cell wall of Neurospora crassa was recently proposed. In this pathway, the DFG-5 and DCW-1 endo-α-1,6-mannanases function to covalently cross-link cell wall protein-associated N-linked galactomannans, which are structurally related to the yeast outer chain mannans, into the cell wall glucan-chitin matrix. In this report, we demonstrate that the mannosyltransferase enzyme Och1p, which is needed for the synthesis of the N-linked outer chain mannan, is essential for the incorporation of cell wall glycoproteins into the Candida albicans cell wall. Using endoglycosidases, we show that C. albicans cell wall proteins are cross-linked into the cell wall via their N-linked outer chain mannans. We further demonstrate that the Dfg5p and Dcw1p α-1,6-mannanases are needed for the incorporation of cell wall glycoproteins into the C. albicans cell wall. Our results support the hypothesis that the Dfg5p and Dcw1p α-1,6-mannanases incorporate cell wall glycoproteins into the C. albicans cell wall by cross-linking outer chain mannans into the cell wall glucan-chitin matrix. PMID:26048011

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

PubMed Central

Levin, David E.

2011-01-01

The yeast cell wall is a strong, but elastic, structure that is essential not only for the maintenance of cell shape and integrity, but also for progression through the cell cycle. During growth and morphogenesis, and in response to environmental challenges, the cell wall is remodeled in a highly regulated and polarized manner, a process that is principally under the control of the cell wall integrity (CWI) signaling pathway. This pathway transmits wall stress signals from the cell surface to the Rho1 GTPase, which mobilizes a physiologic response through a variety of effectors. Activation of CWI signaling regulates the production of various carbohydrate polymers of the cell wall, as well as their polarized delivery to the site of cell wall remodeling. This review article centers on CWI signaling in Saccharomyces cerevisiae through the cell cycle and in response to cell wall stress. The interface of this signaling pathway with other pathways that contribute to the maintenance of cell wall integrity is also discussed. PMID:22174182

Anatomical structure of Camellia oleifera shell.

PubMed

Hu, Jinbo; Shi, Yang; Liu, Yuan; Chang, Shanshan

2018-06-04

The main product of Camellia oleifera is edible oil made from the seeds, but huge quantities of agro-waste are produced in the form of shells. The primary components of C. oleifera fruit shell are cellulose, hemicellulose, and lignin, which probably make it a good eco-friendly non-wood material. Understanding the structure of the shell is however a prerequisite to making full use of it. The anatomical structure of C. oleifera fruit shells was investigated from macroscopic to ultrastructural scale by stereoscopic, optical, and scanning electron microscopy. The main cell morphology in the different parts of the shell was observed and measured using the tissue segregation method. The density of the cross section of the shell was also obtained using an X-ray CT scanner to check the change in texture. The C. oleifera fruit pericarp was made up of exocarp, mesocarp, and endocarp. The main types of exocarp cells were stone cells, spiral vessels, and parenchyma cells. The mesocarp accounted for most of the shell and consisted of parenchyma, tracheids, and some stone cells. The endocarp was basically made up of cells with a thickened cell wall that were modified tracheid or parenchyma cells with secondary wall thickening. The most important ultrastructure in these cells was the pits in the cell wall of stone and vessel cells that give the shell a conducting, mechanical, and protective role. The density of the shell gradually decreased from exocarp to endocarp. Tracheid cells are one of the main cell types in the shell, but their low slenderness (length to width) ratio makes them unsuitable for the manufacture of paper. Further research should be conducted on composite shell-plastic panels (or other reinforced materials) to make better use of this agro-waste.

Effect of surface functionalizations of multi-walled carbon nanotubes on neoplastic transformation potential in primary human lung epithelial cells.

PubMed

Stueckle, Todd A; Davidson, Donna C; Derk, Ray; Wang, Peng; Friend, Sherri; Schwegler-Berry, Diane; Zheng, Peng; Wu, Nianqiang; Castranova, Vince; Rojanasakul, Yon; Wang, Liying

2017-06-01

Functionalized multi-walled carbon nanotube (fMWCNT) development has been intensified to improve their surface activity for numerous applications, and potentially reduce toxic effects. Although MWCNT exposures are associated with lung tumorigenesis in vivo, adverse responses associated with exposure to different fMWCNTs in human lung epithelium are presently unknown. This study hypothesized that different plasma-coating functional groups determine MWCNT neoplastic transformation potential. Using our established model, human primary small airway epithelial cells (pSAECs) were continuously exposed for 8 and 12 weeks at 0.06 μg/cm 2 to three-month aged as-prepared-(pMWCNT), carboxylated-(MW-COOH), and aminated-MWCNTs (MW-NH x ). Ultrafine carbon black (UFCB) and crocidolite asbestos (ASB) served as particle controls. fMWCNTs were characterized during storage, and exposed cells were assessed for several established cancer cell hallmarks. Characterization analyses conducted at 0 and 2 months of aging detected a loss of surface functional groups over time due to atmospheric oxidation, with MW-NH x possessing less oxygen and greater lung surfactant binding affinity. Following 8 weeks of exposure, all fMWCNT-exposed cells exhibited significant increased proliferation compared to controls at 7 d post-treatment, while UFCB- and ASB-exposed cells did not differ significantly from controls. UFCB, pMWCNT, and MW-COOH exposure stimulated significant transient invasion behavior. Conversely, aged MW-NH x -exposed cells displayed moderate increases in soft agar colony formation and morphological transformation potential, while UFCB cells showed a minimal effect compared to all other treatments. In summary, surface properties of aged fMWCNTs can impact cell transformation events in vitro following continuous, occupationally relevant exposures.

Structural diversity of alkali-soluble polysaccharides from the fruit cell walls of tucumã (Astrocaryum aculeatum), a commelinid monocotyledon from the family Arecaceae.

PubMed

Cantu-Jungles, Thaisa Moro; Iacomini, Marcello; Cipriani, Thales R; Cordeiro, Lucimara M C

2017-09-01

The polysaccharide compositions of primary and secondary cell walls of members of the family Arecaceae in the commelinid clade of monocotyledonous plants have previously been found to be distinguishable from other commelinid families, and to be more similar to those of non-commelinids. However, few studies have been conducted. We aimed to extract and characterize the main cell-wall polysaccharides in the fruit pulp of tucumã (Astrocaryum aculeatum), a member of Arecaceae family. Hemicellulosic polysaccharides extracted by alkali from the fruit pulp were present in greater proportions (6.4% yield) than water-extracted ones (3.0% yield). Thus, the former was analyzed using monosaccharide composition, methylation, molecular weight determination and 13 C-NMR data. The tucumã alkaline extract presented a highly ramified acidic galactoarabinoxylan (53.7%), a linear (1 → 5)-linked α-L-arabinan (27.8%), a low branched glucuronoxylan (14.1%) and small portions of a xyloglucan (4.4%). The major polysaccharide found in A. aculeatum (acidic galactoarabinoxylan) is similar to those found in other commelinid plants such as grasses and cereals. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

A distinct role of pectate lyases in the formation of feeding structures induced by cyst and root-knot nematodes.

PubMed

Wieczorek, K; Elashry, A; Quentin, M; Grundler, F M W; Favery, B; Seifert, G J; Bohlmann, H

2014-09-01

Pectin in the primary plant cell wall is thought to be responsible for its porosity, charge density, and microfibril spacing and is the main component of the middle lamella. Plant-parasitic nematodes secrete cell wall-degrading enzymes that macerate the plant tissue, facilitating the penetration and migration within the roots. In sedentary endoparasitic nematodes, these enzymes are released only during the migration of infective juveniles through the root. Later, nematodes manipulate the expression of host plant genes, including various cell wall enzymes, in order to induce specific feeding sites. In this study, we investigated expression of two Arabidopsis pectate lyase-like genes (PLL), PLL18 (At3g27400) and PLL19 (At4g24780), together with pectic epitopes with different degrees of methylesterification in both syncytia induced by the cyst nematode Heterodera schachtii and giant cells induced by the root-knot nematode Meloidogyne incognita. We confirmed upregulation of PLL18 and PLL19 in both types of feeding sites with quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and in situ RT-PCR. Furthermore, the functional analysis of mutants demonstrated the important role of both PLL genes in the development and maintenance of syncytia but not giant cells. Our results show that both enzymes play distinct roles in different infected root tissues as well as during parasitism of different nematodes.

Acetylesterase-Mediated Deacetylation of Pectin Impairs Cell Elongation, Pollen Germination, and Plant Reproduction[C][W

PubMed Central

Gou, Jin-Ying; Miller, Lisa M.; Hou, Guichuan; Yu, Xiao-Hong; Chen, Xiao-Ya; Liu, Chang-Jun

2012-01-01

Pectin is a major component of the primary cell wall of higher plants. Some galacturonyl residues in the backbone of pectinaceous polysaccharides are often O-acetylated at the C-2 or C-3 position, and the resulting acetylesters change dynamically during the growth and development of plants. The processes involve both enzymatic acetylation and deacetylation. Through genomic sequence analysis, we identified a pectin acetylesterase (PAE1) from black cottonwood (Populus trichocarpa). Recombinant Pt PAE1 exhibited preferential activity in releasing the acetate moiety from sugar beet (Beta vulgaris) and potato (Solanum tuberosum) pectin in vitro. Overexpressing Pt PAE1 in tobacco (Nicotiana tabacum) decreased the level of acetyl esters of pectin but not of xylan. Deacetylation engendered differential changes in the composition and/or structure of cell wall polysaccharides that subsequently impaired the cellular elongation of floral styles and filaments, the germination of pollen grains, and the growth of pollen tubes. Consequently, plants overexpressing PAE1 exhibited severe male sterility. Furthermore, in contrast to the conventional view, PAE1-mediated deacetylation substantially lowered the digestibility of pectin. Our data suggest that pectin acetylesterase functions as an important structural regulator in planta by modulating the precise status of pectin acetylation to affect the remodeling and physiochemical properties of the cell wall's polysaccharides, thereby affecting cell extensibility. PMID:22247250

Acetylesterase-Mediated Deacetylation of Pectin Impairs Cell Elongation, Pollen Germination, and Plant Reproduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gou J. Y.; Liu C.; Miller, L. M.

Pectin is a major component of the primary cell wall of higher plants. Some galacturonyl residues in the backbone of pectinaceous polysaccharides are often O-acetylated at the C-2 or C-3 position, and the resulting acetylesters change dynamically during the growth and development of plants. The processes involve both enzymatic acetylation and deacetylation. Through genomic sequence analysis, we identified a pectin acetylesterase (PAE1) from black cottonwood (Populus trichocarpa). Recombinant Pt PAE1 exhibited preferential activity in releasing the acetate moiety from sugar beet (Beta vulgaris) and potato (Solanum tuberosum) pectin in vitro. Overexpressing Pt PAE1 in tobacco (Nicotiana tabacum) decreased the levelmore » of acetyl esters of pectin but not of xylan. Deacetylation engendered differential changes in the composition and/or structure of cell wall polysaccharides that subsequently impaired the cellular elongation of floral styles and filaments, the germination of pollen grains, and the growth of pollen tubes. Consequently, plants overexpressing PAE1 exhibited severe male sterility. Furthermore, in contrast to the conventional view, PAE1-mediated deacetylation substantially lowered the digestibility of pectin. Our data suggest that pectin acetylesterase functions as an important structural regulator in planta by modulating the precise status of pectin acetylation to affect the remodeling and physiochemical properties of the cell wall's polysaccharides, thereby affecting cell extensibility.« less

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

PubMed

Huberman, Lori B; Murray, Andrew W

2014-01-01

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

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

PubMed Central

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

Major Histopathologic Diagnoses of Chronic Wounds.

PubMed

Turi, George K; Donovan, Virginia; DiGregorio, Julie; Criscitelli, Theresa M; Kashan, Benjamin; Barrientos, Stephan; Balingcongan, Jose Ramon; Gorenstein, Scott; Brem, Harold

2016-08-01

To clarify the histopathology of acute osteomyelitis, chronic osteomyelitis, primary vasculitis, and secondary-type vasculitis. This continuing education activity is intended for physicians and nurses with an interest in skin and wound care. After participating in this educational activity, the participant should be better able to:1. Describe the parameters and significance of this study.2. Identify chronic wound diagnosis and treatment.3. Differentiate the histopathology of osteomyelitis and vasculitis. The presence of a chronic wound can result in significant morbidity/mortality. Understanding the pathological alterations of wound tissue that are refractory to standard wound therapy is essential for effective wound management and healing. The authors describe 4 wound etiologies, specifically, acute osteomyelitis, chronic osteomyelitis, primary vasculitis, and secondary-type vasculitis. A tertiary care hospital. A retrospective review of 1392 wound operations performed during a 24-month period at a tertiary care hospital was conducted. Tissue specimens reviewed included soft tissue infections of the lower extremity, sacrum, hip/pelvis, trunk, perineum, and buttocks. Acute osteomyelitis is defined as bone tissue with a predominance of polymorphonuclear leukocytes, evidence of osteoclast bone resorption with scalloping of the cortical bone edges, and bone detritus. Chronic osteomyelitis is defined as bone tissue with a significant amount of fibrosis surrounding devitalized tissue and heavy infiltration of lymphocytes and plasma cells. Primary-type vasculitis is defined primarily as inflammation and necrosis of blood vessel walls. In cutaneous lesions of granulomatosis with polyangiitis, ulceration with numerous inflammatory granulomas is seen in the papillary dermis. Secondary vasculitis is defined by vessel wall infiltration by inflammatory cells and fibrinoid necrosis of the small vessel wall. Pathologies of these 4 types of wounds can complicate standard algorithms designed for diagnosis and treatment, and accurate diagnosis through histopathologic analysis can help tailor targeted treatment.

A study of the native cell wall structures of the marine alga Ventricaria ventricosa (Siphonocladales, Chlorophyceae) using atomic force microscopy.

PubMed

Eslick, Enid M; Beilby, Mary J; Moon, Anthony R

2014-04-01

A substantial proportion of the architecture of the plant cell wall remains unknown with a few cell wall models being proposed. Moreover, even less is known about the green algal cell wall. Techniques that allow direct visualization of the cell wall in as near to its native state are of importance in unravelling the spatial arrangement of cell wall structures and hence in the development of cell wall models. Atomic force microscopy (AFM) was used to image the native cell wall of living cells of Ventricaria ventricosa (V. ventricosa) at high resolution under physiological conditions. The cell wall polymers were identified mainly qualitatively via their structural appearance. The cellulose microfibrils (CMFs) were easily recognizable and the imaging results indicate that the V. ventricosa cell wall has a cross-fibrillar structure throughout. We found the native wall to be abundant in matrix polysaccharides existing in different curing states. The soft phase matrix polysaccharides susceptible by the AFM scanning tip existed as a glutinous fibrillar meshwork, possibly incorporating both the pectic- and hemicellulosic-type substances. The hard phase matrix producing clearer images, revealed coiled fibrillar structures associated with CMFs, sometimes being resolved as globular structures by the AFM tip. The coiling fibrillar structures were also seen in the images of isolated cell wall fragments. The mucilaginous component of the wall was discernible from the gelatinous cell wall matrix as it formed microstructural domains over the surface. AFM has been successful in imaging the native cell wall and revealing novel findings such as the 'coiling fibrillar structures' and cell wall components which have previously not been seen, that is, the gelatinous matrix phase.

Breast Cancer Research at NASA

NASA Technical Reports Server (NTRS)

1998-01-01

High magnification view of human primary breast tumor cells after 56 days of culture in a NASA Bioreactor. The arrow points to bead surface indicating breast cancer cells (as noted by the staining of tumor cell intermediate filaments). NASA's Marshall Space Flight Center (MSFC) is sponsoring research with Bioreactors, rotating wall vessels designed to grow tissue samples in space, to understand how breast cancer works. This ground-based work studies the growth and assembly of human mammary epithelial cell (HMEC) from breast cancer susceptible tissue. Radiation can make the cells cancerous, thus allowing better comparisons of healthy vs. tunorous tissue. Credit: Dr. Jearne Becker, University of South Florida

[Glandular squamous cell carcinoma of the urinary bladder].

PubMed

Kovylina, M V; Pushkar', D Iu; Zaĭrat'iants, O V; Rasner, P I

2006-01-01

The paper gives a clinical observation of a 52 year-old male with a rare histological urinary bladder tumor primary grandular-squamous-cell carcinoma (pT3N IM0). The tumor is represented by two components large acinic-cell adenocarcinoma and squamous-cell carcinoma with keratinization, which smoothly pass one into another; the tumor has grown through all layers of the urinary bladder wall but it has failed to grow into the peritoneum. A microscopic study has indicated that the urachus is intact. Metastases were found in 3 of 8 lymph nodes: one showed high-grade adenocarcinoma and two others displayed average-grade squamous-cell carcinoma.

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

PubMed

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.

Altered Cell Wall Plasticity Can Restrict Plant Growth under Ammonium Nutrition

PubMed Central

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 (NO3–) and ammonium (NH4+). However, the composition of the N source is important, because excess of NH4+ promotes morphological disorders. Plants cultured on NH4+ as the sole N source exhibit serious growth inhibition, commonly referred to as “ammonium toxicity syndrome.” NH4+-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 NH4+ nutrition may trigger growth retardation in plants, properties of their cell walls were analyzed. We found that Arabidopsis thaliana using NH4+ 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, NH4+ 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 NH4+-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. PMID:28848567

Induction of low-level hydrogen peroxide generation by unbleached cotton nonwovens as potential or wound healing applications

USDA-ARS?s Scientific Manuscript database

Greige cotton is an intact plant fiber. The cuticle and primary cell wall near the outer surface of the cotton fiber contains pectin, peroxidases, superoxide dismutase (SOD), and trace metals, which are associated with hydrogen peroxide (H2O2) generation during cotton fiber development. The compon...

Monitoring the Effectiveness of Measures to Contain the Primary Sources of Mercury Pollution on the Site of a Former Chlor-Akali Plant in Kazakhstan

EPA Science Inventory

An extensive sampling campaign was conducted in 2005-2007 to monitor the effectiveness of remedial measures to contain mercury pollution at the site of a former mercury cell chlor-alkali plant in Pavlodar, Kazakhstan. Containment measures consisted of cutoff walls and capping of ...

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

PubMed

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.

Cell Wall Composition and Candidate Biosynthesis Gene Expression During Rice Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Fan; Manisseri, Chithra; Fagerström, Alexandra

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 18more » 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.« less

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

PubMed

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.

Method and apparatus for constructing an underground barrier wall structure

DOEpatents

Dwyer, Brian P.; Stewart, Willis E.; Dwyer, Stephen F.

2002-01-01

A method and apparatus for constructing a underground barrier wall structure using a jet grout injector subassembly comprising a pair of primary nozzles and a plurality of secondary nozzles, the secondary nozzles having a smaller diameter than the primary nozzles, for injecting grout in directions other than the primary direction, which creates a barrier wall panel having a substantially uniform wall thickess. This invention addresses the problem of the weak "bow-tie" shape that is formed during conventional jet injection when using only a pair of primary nozzles. The improvement is accomplished by using at least four secondary nozzles, of smaller diameter, located on both sides of the primary nozzles. These additional secondary nozzles spray grout or permeable reactive materials in other directions optimized to fill in the thin regions of the bow-tie shape. The result is a panel with increased strength and substantially uniform wall thickness.

Developmental distribution of the plasma membrane-enriched proteome in the maize primary root growth zone.

PubMed

Zhang, Zhe; Voothuluru, Priyamvada; Yamaguchi, Mineo; Sharp, Robert E; Peck, Scott C

2013-01-01

Within the growth zone of the maize primary root, there are well-defined patterns of spatial and temporal organization of cell division and elongation. However, the processes underlying this organization remain poorly understood. To gain additional insights into the differences amongst the defined regions, we performed a proteomic analysis focusing on fractions enriched for plasma membrane (PM) proteins. The PM is the interface between the plant cell and the apoplast and/or extracellular space. As such, it is a key structure involved in the exchange of nutrients and other molecules as well as in the integration of signals that regulate growth and development. Despite the important functions of PM-localized proteins in mediating these processes, a full understanding of dynamic changes in PM proteomes is often impeded by low relative concentrations relative to total proteins. Using a relatively simple strategy of treating microsomal fractions with Brij-58 detergent to enrich for PM proteins, we compared the developmental distribution of proteins within the root growth zone which revealed a number of previously known as well as novel proteins with interesting patterns of abundance. For instance, the quantitative proteomic analysis detected a gradient of PM aquaporin proteins similar to that previously reported using immunoblot analyses, confirming the veracity of this strategy. Cellulose synthases increased in abundance with increasing distance from the root apex, consistent with expected locations of cell wall deposition. The similar distribution pattern for Brittle-stalk-2-like protein implicates that this protein may also have cell wall related functions. These results show that the simplified PM enrichment method previously demonstrated in Arabidopsis can be successfully applied to completely unrelated plant tissues and provide insights into differences in the PM proteome throughout growth and development zones of the maize primary root.

Endoplasmic reticulum-derived reactive oxygen species (ROS) is involved in toxicity of cell wall stress to Candida albicans.

PubMed

Yu, Qilin; Zhang, Bing; Li, Jianrong; Zhang, Biao; Wang, Honggang; Li, Mingchun

2016-10-01

The cell wall is an important cell structure in both fungi and bacteria, and hence becomes a common antimicrobial target. The cell wall-perturbing agents disrupt synthesis and function of cell wall components, leading to cell wall stress and consequent cell death. However, little is known about the detailed mechanisms by which cell wall stress renders fungal cell death. In this study, we found that ROS scavengers drastically attenuated the antifungal effect of cell wall-perturbing agents to the model fungal pathogen Candida albicans, and these agents caused remarkable ROS accumulation and activation of oxidative stress response (OSR) in this fungus. Interestingly, cell wall stress did not cause mitochondrial dysfunction and elevation of mitochondrial superoxide levels. Furthermore, the iron chelator 2,2'-bipyridyl (BIP) and the hydroxyl radical scavengers could not attenuate cell wall stress-caused growth inhibition and ROS accumulation. However, cell wall stress up-regulated expression of unfold protein response (UPR) genes, enhanced protein secretion and promoted protein folding-related oxidation of Ero1, an important source of ROS production. These results indicated that oxidation of Ero1 in the endoplasmic reticulum (ER), rather than mitochondrial electron transport and Fenton reaction, contributed to cell wall stress-related ROS accumulation and consequent growth inhibition. Our findings uncover a novel link between cell wall integrity (CWI), ER function and ROS production in fungal cells, and shed novel light on development of strategies promoting the antifungal efficacy of cell wall-perturbing agents against fungal infections. Copyright © 2016 Elsevier Inc. All rights reserved.

Anisotropic Cell Expansion Is Affected through the Bidirectional Mobility of Cellulose Synthase Complexes and Phosphorylation at Two Critical Residues on CESA31[OPEN

PubMed Central

Liu, Yanmei; Bauer, Stefan

2016-01-01

Here we report that phosphorylation status of S211 and T212 of the CESA3 component of Arabidopsis (Arabidopsis thaliana) cellulose synthase impacts the regulation of anisotropic cell expansion as well as cellulose synthesis and deposition and microtubule-dependent bidirectional mobility of CESA complexes. Mutation of S211 to Ala caused a significant decrease in the length of etiolated hypocotyls and primary roots, while root hairs were not significantly affected. By contrast, the S211E mutation stunted the growth of root hairs, but primary roots were not significantly affected. Similarly, T212E caused a decrease in the length of root hairs but not root length. However, T212E stunted the growth of etiolated hypocotyls. Live-cell imaging of fluorescently labeled CESA showed that the rate of movement of CESA particles was directionally asymmetric in etiolated hypocotyls of S211A and T212E mutants, while similar bidirectional velocities were observed with the wild-type control and S211E and T212A mutant lines. Analysis of cell wall composition and the innermost layer of cell wall suggests a role for phosphorylation of CESA3 S211 and T212 in cellulose aggregation into fibrillar bundles. These results suggest that microtubule-guided bidirectional mobility of CESA complexes is fine-tuned by phosphorylation of CESA3 S211 and T212, which may, in turn, modulate cellulose synthesis and organization, resulting in or contributing to the observed defects of anisotropic cell expansion. PMID:26969722

Regulation of cell wall biosynthesis.

PubMed

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.

Relating Nanoscale Accessibility within Plant Cell Walls to Improved Enzyme Hydrolysis Yields in Corn Stover Subjected to Diverse Pretreatments.

PubMed

Crowe, Jacob D; Zarger, Rachael A; Hodge, David B

2017-10-04

Simultaneous chemical modification and physical reorganization of plant cell walls via alkaline hydrogen peroxide or liquid hot water pretreatment can alter cell wall structural properties impacting nanoscale porosity. Nanoscale porosity was characterized using solute exclusion to assess accessible pore volumes, water retention value as a proxy for accessible water-cell walls surface area, and solute-induced cell wall swelling to measure cell wall rigidity. Key findings concluded that delignification by alkaline hydrogen peroxide pretreatment decreased cell wall rigidity and that the subsequent cell wall swelling resulted increased nanoscale porosity and improved enzyme binding and hydrolysis compared to limited swelling and increased accessible surface areas observed in liquid hot water pretreated biomass. The volume accessible to a 90 Å dextran probe within the cell wall was found to be correlated to both enzyme binding and glucose hydrolysis yields, indicating cell wall porosity is a key contributor to effective hydrolysis yields.

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

PubMed

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

2015-03-18

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

Effect of Compliant Walls on Secondary Instabilities in Boundary-Layer Transition

NASA Technical Reports Server (NTRS)

Joslin, Ronald D.; Morris, Philip J.

1991-01-01

For aerodynamic and hydrodynamic vehicles, it is highly desirable to reduce drag and noise levels. A reduction in drag leads to fuel savings. In particular for submersible vehicles, a decrease in noise levels inhibits detection. A suggested means to obtain these reduction goals is by delaying the transition from laminar to turbulent flow in external boundary layers. For hydrodynamic applications, a passive device which shows promise for transition delays is the compliant coating. In previous studies with a simple mechanical model representing the compliant wall, coatings were found that provided transition delays as predicted from the semi-empirical e(sup n) method. Those studies were concerned with the linear stage of transition where the instability of concern is referred to as the primary instability. For the flat-plate boundary layer, the Tollmien-Schlichting (TS) wave is the primary instability. In one of those studies, it was shown that three-dimensional (3-D) primary instabilities, or oblique waves, could dominate transition over the coatings considered. From the primary instability, the stretching and tilting of vorticity in the shear flow leads to a secondary instability mechanism. This has been theoretical described by Herbert based on Floquet theory. In the present study, Herbert's theory is used to predict the development of secondary instabilities over isotropic and non-isotropic compliant walls. Since oblique waves may be dominant over compliant walls, a secondary theory extention is made to allow for these 3-D primary instabilities. The effect of variations in primary amplitude, spanwise wavenumber, and Reynolds number on the secondary instabilities are examined. As in the rigid wall case, over compliant walls the subharmonic mode of secondary instability dominates for low-amplitude primary disturbances. Both isotropic and non-isotropic compliant walls lead to reduced secondary growth rates compared to the rigid wall results. For high frequencies, the non-isotropic wall suppresses the amplification of the secondary instabilities, while instabilities over the isotropic wall may grow with an explosive rate similar to the rigid wall results. For the more important lower frequencies, both isotropic and non-isotropic compliant walls suppress the amplification of secondary instabilities compared to the rigid wall results. The twofold major discovery and demonstration of the present investigation are: (1) the use of passive devices, such as compliant walls, can lead to significant reductions in the secondary instability growth rates and amplification; (2) suppressing the primary growth rates and subsequent amplification enable delays in the growth of the explosive secondary instability mechanism.

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

PubMed

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.

Concurrent primary carcinoid tumor arising within mature teratoma and clear cell renal cell carcinoma in the horseshoe kidney: report of a rare case and review of the literature.

PubMed

Sun, Ke; You, Qihan; Zhao, Ming; Yao, Hongtian; Xiang, Hua; Wang, Lijun

2013-01-01

Primary carcinoid tumor arising in a mature teratoma of the horseshoe kidney is exceptionally rare and only 4 such cases have been reported in the world literature to date. The simultaneous occurrence of different subtypes of renal cell carcinoma (RCC) or RCC coexistence with non-RCC neoplasms from the same kidney is unusual and infrequently reported. Herein we report a case of primary carcinoid tumor arising within mature teratoma, concurrent with a clear cell RCC in the horseshoe kidney of a 37-year-old man. Histologically, both the carcinoid tumor and clear cell RCC demonstrated the characteristic morphology in their classic forms. In addition to the carcinoid tumor, the mature teratoma consisted of variably sized, large cystic spaces lined by cytologically bland mucinous columnar epithelium, pseudostratified columnar epithelium, ciliated epithelium and mature smooth muscle fibers were also identified within the cystic wall. Furthermore, foci of round, small nodules composed of mature prostatic acinus were noted in the teratoma which was confirmed by exhibiting strong immunoreactivity for prostate specific antigen. The present case serves to expand the histologic component that may be encountered in the mature terotoma of the kidney and further broadens the spectrum of primary tumors occurring in the horseshoe kidney.

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

PubMed

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.

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

PubMed

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.

Breast Cancer Research at NASA

NASA Technical Reports Server (NTRS)

1998-01-01

Human primary breast tumor cells after 56 days of culture in a NASA Bioreactor. A cross-section of a construct, grown from surgical specimens of brease cancer, stained for microscopic examination, reveals areas of tumor cells dispersed throughout the non-epithelial cell background. The arrow denotes the foci of breast cancer cells. NASA's Marshall Space Flight Center (MSFC) is sponsoring research with Bioreactors, rotating wall vessels designed to grow tissue samples in space, to understand how breast cancer works. This ground-based work studies the growth and assembly of human mammary epithelial cell (HMEC) from breast cancer susceptible tissue. Radiation can make the cells cancerous, thus allowing better comparisons of healthy vs. tunorous tissue. Credit: Dr. Jearne Becker, University of South Florida

Microgravity

NASA Image and Video Library

1998-10-10

Human primary breast tumor cells after 56 days of culture in a NASA Bioreactor. A cross-section of a construct, grown from surgical specimens of brease cancer, stained for microscopic examination, reveals areas of tumor cells dispersed throughout the non-epithelial cell background. The arrow denotes the foci of breast cancer cells. NASA's Marshall Space Flight Center (MSFC) is sponsoring research with Bioreactors, rotating wall vessels designed to grow tissue samples in space, to understand how breast cancer works. This ground-based work studies the growth and assembly of human mammary epithelial cell (HMEC) from breast cancer susceptible tissue. Radiation can make the cells cancerous, thus allowing better comparisons of healthy vs. tunorous tissue. Credit: Dr. Jearne Becker, University of South Florida

The valine and lysine residues in the conserved FxVTxK motif are important for the function of phylogenetically distant plant cellulose synthases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slabaugh, Erin; Scavuzzo-Duggan, Tess; Chaves, Arielle

2015-12-08

Cellulose synthases (CESAs) synthesize the β-1,4-glucan chains that coalesce to form cellulose microfibrils in plant cell walls. In addition to a large cytosolic (catalytic) domain, CESAs have eight predicted transmembrane helices (TMHs). However, analogous to the structure of BcsA, a bacterial CESA, predicted TMH5 in CESA may instead be an interfacial helix. This would place the conserved FxVTxK motif in the plant cell cytosol where it could function as a substrate-gating loop as occurs in BcsA. To define the functional importance of the CESA region containing FxVTxK, we tested five parallel mutations in Arabidopsis thaliana CESA1 and Physcomitrella patens CESA5more » in complementation assays of the relevant cesa mutants. In both organisms, the substitution of the valine or lysine residues in FxVTxK severely affected CESA function. In Arabidopsis roots, both changes were correlated with lower cellulose anisotropy, as revealed by Pontamine Fast Scarlet. Analysis of hypocotyl inner cell wall layers by atomic force microscopy showed that two altered versions of Atcesa1 could rescue cell wall phenotypes observed in the mutant background line. Overall, the data show that the FxVTxK motif is functionally important in two phylogenetically distant plant CESAs. The results show that Physcomitrella provides an efficient model for assessing the effects of engineered CESA mutations affecting primary cell wall synthesis and that diverse testing systems can lead to nuanced insights into CESA structure–function relationships. Although CESA membrane topology needs to be experimentally determined, the results support the possibility that the FxVTxK region functions similarly in CESA and BcsA.« less

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

PubMed Central

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

2014-01-01

The nanoscale mechanical properties of live Staphylococcus aureus cells during different phases of growth were studied by atomic force microscopy. Indentation to different depths provided access to both local cell wall mechanical properties and whole-cell properties, including a component related to cell turgor pressure. Local cell wall properties were found to change in a characteristic manner throughout the division cycle. Splitting of the cell into two daughter cells followed a local softening of the cell wall along the division circumference, with the cell wall on either side of the division circumference becoming stiffer. Once exposed, the newly formed septum was found to be stiffer than the surrounding, older cell wall. Deeper indentations, which were affected by cell turgor pressure, did not show a change in stiffness throughout the division cycle, implying that enzymatic cell wall remodeling and local variations in wall properties are responsible for the evolution of cell shape through division. PMID:25468333

Probiotic metabolites from Bacillus coagulans GanedenBC30TM support maturation of antigen-presenting cells in vitro

PubMed Central

Benson, Kathleen F; Redman, Kimberlee A; Carter, Steve G; Keller, David; Farmer, Sean; Endres, John R; Jensen, Gitte S

2012-01-01

AIM: To study the effects of probiotic metabolites on maturation stage of antigen-presenting immune cells. METHODS: Ganeden Bacillus coagulans 30 (GBC30) bacterial cultures in log phase were used to isolate the secreted metabolite (MET) fraction. A second fraction was made to generate a crude cell-wall-enriched fraction, by centrifugation and lysis, followed by washing. A preparation of MET was subjected to size exclusion centrifugation, generating three fractions: < 3 kDa, 3-30 kDa, and 30-200 kDa and activities were tested in comparison to crude MET and cell wall in primary cultures of human peripheral blood mononuclear cell (PBMC) as a source of antigen-presenting mononuclear phagocytes. The maturation status of mononuclear phagocytes was evaluated by staining with monoclonal antibodies towards CD14, CD16, CD80 and CD86 and analyzed by flow cytometry. RESULTS: Treatment of PBMC with MET supported maturation of mononuclear phagocytes toward both macrophage and dendritic cell phenotypes. The biological activity unique to the metabolites included a reduction of CD14+ CD16+ pro-inflammatory cells, and this property was associated with the high molecular weight metabolite fraction. Changes were also seen for the dendritic cell maturation markers CD80 and CD86. On CD14dim cells, an increase in both CD80 and CD86 expression was seen, in contrast to a selective increase in CD86 expression on CD14bright cells. The co-expression of CD80 and CD86 indicates effective antigen presentation to T cells and support of T helper cell differentiation. The selective expression of CD86 in the absence of CD80 points to a role in generating T regulatory cells. CONCLUSION: The data show that a primary mechanism of action of GBC30 metabolites involves support of more mature phenotypes of antigen-presenting cells, important for immunological decision-making. PMID:22563167

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

PubMed Central

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

2016-01-01

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

Cell walls of the dimorphic fungal pathogens Sporothrix schenckii and Sporothrix brasiliensis exhibit bilaminate structures and sloughing of extensive and intact layers

PubMed Central

Walker, Louise A.; Niño-Vega, Gustavo; Mora-Montes, Héctor M.; Neves, Gabriela W. P.; Villalobos-Duno, Hector; Barreto, Laura; Garcia, Karina; Franco, Bernardo; Martínez-Álvarez, José A.; Munro, Carol A.; Gow, Neil A. R.

2018-01-01

Sporotrichosis is a subcutaneous mycosis caused by pathogenic species of the Sporothrix genus. A new emerging species, Sporothrix brasiliensis, is related to cat-transmitted sporotrichosis and has severe clinical manifestations. The cell wall of pathogenic fungi is a unique structure and impacts directly on the host immune response. We reveal and compare the cell wall structures of Sporothrix schenckii and S. brasiliensis using high-pressure freezing electron microscopy to study the cell wall organization of both species. To analyze the components of the cell wall, we also used infrared and 13C and 1H NMR spectroscopy and the sugar composition was determined by quantitative high-performance anion-exchange chromatography. Our ultrastructural data revealed a bi-layered cell wall structure for both species, including an external microfibrillar layer and an inner electron-dense layer. The inner and outer layers of the S. brasiliensis cell wall were thicker than those of S. schenckii, correlating with an increase in the chitin and rhamnose contents. Moreover, the outer microfibrillar layer of the S. brasiliensis cell wall had longer microfibrils interconnecting yeast cells. Distinct from those of other dimorphic fungi, the cell wall of Sporothrix spp. lacked α-glucan component. Interestingly, glycogen α-particles were identified in the cytoplasm close to the cell wall and the plasma membrane. The cell wall structure as well as the presence of glycogen α-particles varied over time during cell culture. The structural differences observed in the cell wall of these Sporothrix species seemed to impact its uptake by monocyte-derived human macrophages. The data presented here show a unique cell wall structure of S. brasiliensis and S. schenckii during the yeast parasitic phase. A new cell wall model for Sporothrix spp. is therefore proposed that suggests that these fungi molt sheets of intact cell wall layers. This observation may have significant effects on localized and disseminated immunopathology. PMID:29522522

Cell Wall-Degrading Enzymes Enlarge the Pore Size of Intervessel Pit Membranes in Healthy and Xylella fastidiosa-Infected Grapevines1[C][W][OA

PubMed Central

Pérez-Donoso, Alonso G.; Sun, Qiang; Roper, M. Caroline; Greve, L. Carl; Kirkpatrick, Bruce; Labavitch, John M.

2010-01-01

The pit membrane (PM) is a primary cell wall barrier that separates adjacent xylem water conduits, limiting the spread of xylem-localized pathogens and air embolisms from one conduit to the next. This paper provides a characterization of the size of the pores in the PMs of grapevine (Vitis vinifera). The PM porosity (PMP) of stems infected with the bacterium Xylella fastidiosa was compared with the PMP of healthy stems. Stems were infused with pressurized water and flow rates were determined; gold particles of known size were introduced with the water to assist in determining the size of PM pores. The effect of introducing trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CDTA), oligogalacturonides, and polygalacturonic acid into stems on water flux via the xylem was also measured. The possibility that cell wall-degrading enzymes could alter the pore sizes, thus facilitating the ability of X. fastidiosa to cross the PMs, was tested. Two cell wall-degrading enzymes likely to be produced by X. fastidiosa (polygalactuoronase and endo-1,4- β -glucanase) were infused into stems, and particle passage tests were performed to check for changes in PMP. Scanning electron microscopy of control and enzyme-infused stem segments revealed that the combination of enzymes opened holes in PMs, probably explaining enzyme impacts on PMP and how a small X. fastidiosa population, introduced into grapevines by insect vectors, can multiply and spread throughout the vine and cause Pierce's disease. PMID:20107028

Surface proteins and the formation of biofilms by Staphylococcus aureus.

PubMed

Kim, Sung Joon; Chang, James; Rimal, Binayak; Yang, Hao; Schaefer, Jacob

2018-03-01

Staphylococcus aureus biofilms pose a serious clinical threat as reservoirs for persistent infections. Despite this clinical significance, the composition and mechanism of formation of S. aureus biofilms are unknown. To address these problems, we used solid-state NMR to examine S. aureus (SA113), a strong biofilm-forming strain. We labeled whole cells and cell walls of planktonic cells, young biofilms formed for 12-24h after stationary phase, and more mature biofilms formed for up to 60h after stationary phase. All samples were labeled either by (i) [ 15 N]glycine and l-[1- 13 C]threonine, or in separate experiments, by (ii) l-[2- 13 C, 15 N]leucine. We then measured 13 C- 15 N direct bonds by C{N} rotational-echo double resonance (REDOR). The increase in peptidoglycan stems that have bridges connected to a surface protein was determined directly by a cell-wall double difference (biofilm REDOR difference minus planktonic REDOR difference). This procedure eliminates errors arising from differences in 15 N isotopic enrichments and from the routing of 13 C label from threonine degradation to glycine. For both planktonic cells and the mature biofilm, 20% of pentaglycyl bridges are not cross-linked and are potential surface-protein attachment sites. None of these sites has a surface protein attached in the planktonic cells, but one-fourth have a surface protein attached in the mature biofilm. Moreover, the leucine-label shows that the concentration of β-strands in leucine-rich regions doubles in the mature biofilm. Thus, a primary event in establishing a S. aureus biofilm is extensive decoration of the cell surface with surface proteins that are linked covalently to the cell wall and promote cell-cell adhesion. Copyright © 2017 Elsevier B.V. All rights reserved.

Loss of Proliferation and Antigen Presentation Activity following Internalization of Polydispersed Carbon Nanotubes by Primary Lung Epithelial Cells

PubMed Central

Kumari, Mandavi; Sachar, Sumedha; Saxena, Rajiv K.

2012-01-01

Interactions between poly-dispersed acid functionalized single walled carbon nanotubes (AF-SWCNTs) and primary lung epithelial (PLE) cells were studied. Peritoneal macrophages (PMs, known phagocytic cells) were used as positive controls in this study. Recovery of live cells from cultures of PLE cells and PMs was significantly reduced in the presence of AF-SWCNTs, in a time and dose dependent manner. Both PLE cells as well as PMs could take up fluorescence tagged AF-SWCNTs in a time dependent manner and this uptake was significantly blocked by cytochalasin D, an agent that blocks the activity of acto-myosin fibers and therefore the phagocytic activity of cells. Confocal microscopic studies confirmed that AF-SWCNTs were internalized by both PLE cells and PMs. Intra-trachially instilled AF-SWCNTs could also be taken up by lung epithelial cells as well as alveolar macrophages. Freshly isolated PLE cells had significant cell division activity and cell cycling studies indicated that treatment with AF-SWCNTs resulted in a marked reduction in S-phase of the cell cycle. In a previously standardized system to study BCG antigen presentation by PLE cells and PMs to sensitized T helper cells, AF-SWCNTs could significantly lower the antigen presentation ability of both cell types. These results show that mouse primary lung epithelial cells can efficiently internalize AF-SWCNTs and the uptake of nanotubes interfered with biological functions of PLE cells including their ability to present BCG antigens to sensitized T helper cells. PMID:22384094

Spatio-temporal diversification of the cell wall matrix materials in the developing stomatal complexes of Zea mays.

PubMed

Giannoutsou, E; Apostolakos, P; Galatis, B

2016-11-01

The matrix cell wall materials, in developing Zea mays stomatal complexes are asymmetrically distributed, a phenomenon appearing related to the local cell wall expansion and deformation, the establishment of cell polarity, and determination of the cell division plane. In cells of developing Zea mays stomatal complexes, definite cell wall regions expand determinately and become locally deformed. This differential cell wall behavior is obvious in the guard cell mother cells (GMCs) and the subsidiary cell mother cells (SMCs) that locally protrude towards the adjacent GMCs. The latter, emitting a morphogenetic stimulus, induce polarization/asymmetrical division in SMCs. Examination of immunolabeled specimens revealed that homogalacturonans (HGAs) with a high degree of de-esterification (2F4- and JIM5-HGA epitopes) and arabinogalactan proteins are selectively distributed in the extending and deformed cell wall regions, while their margins are enriched with rhamnogalacturonans (RGAs) containing highly branched arabinans (LM6-RGA epitope). In SMCs, the local cell wall matrix differentiation constitutes the first structural event, indicating the establishment of cell polarity. Moreover, in the premitotic GMCs and SMCs, non-esterified HGAs (2F4-HGA epitope) are preferentially localized in the cell wall areas outlining the cytoplasm where the preprophase band is formed. In these areas, the forthcoming cell plate fuses with the parent cell walls. These data suggest that the described heterogeneity in matrix cell wall materials is probably involved in: (a) local cell wall expansion and deformation, (b) the transduction of the inductive GMC stimulus, and (c) the determination of the division plane in GMCs and SMCs.

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

PubMed Central

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

Building a plant cell wall at a glance.

PubMed

Lampugnani, Edwin R; Khan, Ghazanfar Abbas; Somssich, Marc; Persson, Staffan

2018-01-29

Plant cells are surrounded by a strong polysaccharide-rich cell wall that aids in determining the overall form, growth and development of the plant body. Indeed, the unique shapes of the 40-odd cell types in plants are determined by their walls, as removal of the cell wall results in spherical protoplasts that are amorphic. Hence, assembly and remodeling of the wall is essential in plant development. Most plant cell walls are composed of a framework of cellulose microfibrils that are cross-linked to each other by heteropolysaccharides. The cell walls are highly dynamic and adapt to the changing requirements of the plant during growth. However, despite the importance of plant cell walls for plant growth and for applications that we use in our daily life such as food, feed and fuel, comparatively little is known about how they are synthesized and modified. In this Cell Science at a Glance article and accompanying poster, we aim to illustrate the underpinning cell biology of the synthesis of wall carbohydrates, and their incorporation into the wall, in the model plant Arabidopsis . © 2018. Published by The Company of Biologists Ltd.

Cell wall evolution and diversity

PubMed Central

Fangel, Jonatan U.; Ulvskov, Peter; Knox, J. P.; Mikkelsen, Maria D.; Harholt, Jesper; Popper, Zoë A.; Willats, William G.T.

2012-01-01

Plant cell walls display a considerable degree of diversity in their compositions and molecular architectures. In some cases the functional significance of a particular cell wall type appears to be easy to discern: secondary cells walls are often reinforced with lignin that provides durability; the thin cell walls of pollen tubes have particular compositions that enable their tip growth; lupin seed cell walls are characteristically thickened with galactan used as a storage polysaccharide. However, more frequently the evolutionary mechanisms and selection pressures that underpin cell wall diversity and evolution are unclear. For diverse green plants (chlorophytes and streptophytes) the rapidly increasing availability of transcriptome and genome data sets, the development of methods for cell wall analyses which require less material for analysis, and expansion of molecular probe sets, are providing new insights into the diversity and occurrence of cell wall polysaccharides and associated biosynthetic genes. Such research is important for refining our understanding of some of the fundamental processes that enabled plants to colonize land and to subsequently radiate so comprehensively. The study of cell wall structural diversity is also an important aspect of the industrial utilization of global polysaccharide bio-resources. PMID:22783271

The life of phi: the development of phi thickenings in roots of the orchids of the genus Miltoniopsis.

PubMed

Idris, Nurul A; Collings, David A

2015-02-01

Phi thickenings, bands of secondary wall thickenings that reinforce the primary wall of root cortical cells in a wide range of species, are described for the first time in the epiphytic orchid Miltoniopsis. As with phi thickenings found in other plants, the phi thickenings in Miltoniopsis contain highly aligned cellulose running along the lengths of the thickenings, and are lignified but not suberized. Using a combination of histological and immunocytochemical techniques, thickening development can be categorized into three different stages. Microtubules align lengthwise along the thickening during early and intermediate stages of development, and callose is deposited within the thickening in a pattern similar to the microtubules. These developing thickenings also label with the fluorescently tagged lectin wheat germ agglutinin (WGA). These associations with microtubules and callose, and the WGA labeling, all disappear when the phi thickenings are mature. This pattern of callose and WGA deposition show changes in the thickened cell wall composition and may shed light on the function of phi thickenings in plant roots, a role for which has yet to be established.

A case of nodal malignant lymphoma presenting with arterial bleeding related to its duodenal penetration.

PubMed

Miyake, Takakazu; Iida, Tomoya; Masaki, Yoshiharu; Onodera, Kei; Kubo, Toshiyuki; Yamashita, Kentaro; Yamano, Hiroo; Nakase, Hiroshi

2018-06-01

A 62-year-old man with a chief complaint of dysphagia visited our hospital. Enhanced computed tomography showed the tumor near the duodenal wall and lymphadenopathy in the left supraclavicular fossa and para-aortic lymph node. Upper gastrointestinal endoscopy showed an ulcer accompanied with a fistula in the anterior wall of duodenal bulb, suggesting that the tumor penetrated into duodenal wall. Biopsy from the lymph node in the left supraclavicular fossa indicated diffuse large B-cell lymphoma. Although chemotherapy was planned, massive arterial bleeding occurred from the part of duodenal penetration. Endoscopic hemostasis was unsuccessfully performed. Therefore, we performed transcathether arterial embolization for hemostasis. After the procedure, the patient received six cycles of chemotherapy, and he achieved complete response. He has been alive 5 years without recurrence. There were many cases of gastrointestinal bleeding from primary gastrointestinal lymphomas, while there were few cases with nodal involvement by malignant lymphoma resulting in bleeding from gastrointestinal tract. We herein report a case of duodenal bleeding by nodal involvement of diffuse large B-cell lymphoma with review of literature.

The Identification of Two Arabinosyltransferases from Tomato Reveals Functional Equivalency of Xyloglucan Side Chain Substituents1[W][OPEN

PubMed Central

Schultink, Alex; Cheng, Kun; Park, Yong Bum; Cosgrove, Daniel J.; Pauly, Markus

2013-01-01

Xyloglucan (XyG) is the dominant hemicellulose present in the primary cell walls of dicotyledonous plants. Unlike Arabidopsis (Arabidopsis thaliana) XyG, which contains galactosyl and fucosyl substituents, tomato (Solanum lycopersicum) XyG contains arabinofuranosyl residues. To investigate the biological function of these differing substituents, we used a functional complementation approach. Candidate glycosyltransferases were identified from tomato by using comparative genomics with known XyG galactosyltransferase genes from Arabidopsis. These candidate genes were expressed in an Arabidopsis mutant lacking XyG galactosylation, and two of them resulted in the production of arabinosylated XyG, a structure not previously found in this plant species. These genes may therefore encode XyG arabinofuranosyltransferases. Moreover, the addition of arabinofuranosyl residues to the XyG of this Arabidopsis mutant rescued a growth and cell wall biomechanics phenotype, demonstrating that the function of XyG in plant growth, development, and mechanics has considerable flexibility in terms of the specific residues in the side chains. These experiments also highlight the potential of reengineering the sugar substituents on plant wall polysaccharides without compromising growth or viability. PMID:23893172

Down-regulation of POLYGALACTURONASE1 alters firmness, tensile strength and water loss in apple (Malus x domestica) fruit

PubMed Central

2012-01-01

Background While there is now a significant body of research correlating apple (Malus x domestica) fruit softening with the cell wall hydrolase ENDO-POLYGALACTURONASE1 (PG1), there is currently little knowledge of its physiological effects in planta. This study examined the effect of down regulation of PG1 expression in ‘Royal Gala’ apples, a cultivar that typically has high levels of PG1, and softens during fruit ripening. Results PG1-suppressed ‘Royal Gala’ apples harvested from multiple seasons were firmer than controls after ripening, and intercellular adhesion was higher. Cell wall analyses indicated changes in yield and composition of pectin, and a higher molecular weight distribution of CDTA-soluble pectin. Structural analyses revealed more ruptured cells and free juice in pulled apart sections, suggesting improved integrity of intercellular connections and consequent cell rupture due to failure of the primary cell walls under stress. PG1-suppressed lines also had reduced expansion of cells in the hypodermis of ripe apples, resulting in more densely packed cells in this layer. This change in morphology appears to be linked with reduced transpirational water loss in the fruit. Conclusions These findings confirm PG1’s role in apple fruit softening and suggests that this is achieved in part by reducing cellular adhesion. This is consistent with previous studies carried out in strawberry but not with those performed in tomato. In apple PG1 also appears to influence other fruit texture characters such as juiciness and water loss. PMID:22856470

Simultaneous bond degradation and bond formation during phenol-formaldehyde curing with wood

Treesearch

Daniel J. Yelle; John Ralph

2016-01-01

Bonding of wood using phenol–formaldehyde adhesive develops highly durable bonds. Phenol– formaldehyde is believed to form primary bonds with wood cell wall polymers (e.g., lignin). However, it is unclear how this adhesive interacts and bonds to lignin. Through wood solubilisation methodologies, earlywood and latewood bonded assemblies were characterized using two-...

Changes in ultrastructure and histochemistry of two red macroalgae strains of Kappaphycus alvarezii (Rhodophyta, Gigartinales), as a consequence of ultraviolet B radiation exposure.

PubMed

Schmidt, Eder Carlos; Scariot, Lidiane Angela; Rover, Ticiane; Bouzon, Zenilda Laurita

2009-12-01

Ultraviolet radiation (UVR) affects macroalgae in many important ways, including reduced growth rate, reduction of primary productivity and changes in cell biology and ultrastructure. Among red macroalgae, Kappaphycus alvarezii is of economic interest by its production of kappa carrageenan. Only a few reports have examined the changes in macroalgae ultrastructure and cell biology resulting from UVB radiation exposure. Therefore, we examined two strains of K. alvarezii (green and red) exposed to UVB for 3 h per day during 28 days and then processed them for histochemical and electron microscopy analysis. Reaction with Toluidine Blue showed an increase in the thickness of the cell wall and Periodic Acid-Schiff stain showed a decrease in the number of starch grains. UVBR also caused changes in the ultrastructure of cortical and subcortical cells, which included increased thickness of the cell wall and number of free ribosomes and plastoglobuli, reduced intracellular spaces, changes in the cell contour, and destruction of chloroplast internal organization. Based on these lines of evidence, it was evident by the ultrastructural changes observed that UVBR negatively affects intertidal macroalgae and, by extension, their economic viability.

Utilization of Microgravity Bioreactor for Differentiation and Growth of Human Vascular Endothelial Cells

NASA Technical Reports Server (NTRS)

Chen, Chu-Huang; Pellis, Neal R.

1997-01-01

The goal was to delineate mechanisms of genetic responses to angiogenic stimulation of human coronary arterial and dermal microvascular endothelial cells during exposure to microgravity. The NASA-designed rotating-wall vessel was used to create a three-dimensional culture environment with low shear-stress and microgravity simulating that in space. The primary specific aim was to determine whether simulated microgravity enhances endothelial cell growth and whether the growth enhancement is associated by augmented expression of Basic Fibroblast Growth Factor (BFGF) and c-fos, an immediate early gene and component of the transcription factor AP-1.

Metabolic profiling reveals altered sugar and secondary metabolism in response to UGPase overexpression in Populus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Payyavula, Raja S.; Tschaplinski, Timothy J.; Jawdy, Sara

Background: UDP-glucose pyrophopharylase (UGPase) is a sugar metabolizing enzyme (E.C. 2.7.7.9) that catalyzes a reversible reaction of UDP-glucose and pyrophosphate from glucose-1-phosphate and uridine triphosphate glucose. UDP-glucose is a key intermediate sugar that is channeled to multiple metabolic pathways. The functional role of UGPase in woody plants such as Populus is poorly understood. Results: We characterized the functional role of UGPase in Populus deltoides by overexpressing a native gene. Overexpression of the native gene resulted in increased leaf area and leaf-to-shoot biomass ratio but decreased shoot and root growth. Metabolomic analyses showed that manipulation of UGPase results in perturbations inmore » primary as well as secondary metabolism resulting in reduced sugar and starch levels and increased phenolics such as caffeoyl- and feruloyl conjugates. While cellulose and lignin levels in the cell walls were not significantly altered, the syringyl-to-guaiacyl ratio was significantly reduced. Conclusions: These results demonstrate that UGPase plays a key role in the tightly coupled primary and secondary metabolic pathways and perturbation in its function results in pronounced effects on growth and metabolism outside of cell wall biosynthesis of Populus.« less

Metabolic profiling reveals altered sugar and secondary metabolism in response to UGPase overexpression in Populus

DOE PAGES

Payyavula, Raja S.; Tschaplinski, Timothy J.; Jawdy, Sara; ...

2014-10-07

Background: UDP-glucose pyrophopharylase (UGPase) is a sugar metabolizing enzyme (E.C. 2.7.7.9) that catalyzes a reversible reaction of UDP-glucose and pyrophosphate from glucose-1-phosphate and uridine triphosphate glucose. UDP-glucose is a key intermediate sugar that is channeled to multiple metabolic pathways. The functional role of UGPase in woody plants such as Populus is poorly understood. Results: We characterized the functional role of UGPase in Populus deltoides by overexpressing a native gene. Overexpression of the native gene resulted in increased leaf area and leaf-to-shoot biomass ratio but decreased shoot and root growth. Metabolomic analyses showed that manipulation of UGPase results in perturbations inmore » primary as well as secondary metabolism resulting in reduced sugar and starch levels and increased phenolics such as caffeoyl- and feruloyl conjugates. While cellulose and lignin levels in the cell walls were not significantly altered, the syringyl-to-guaiacyl ratio was significantly reduced. Conclusions: These results demonstrate that UGPase plays a key role in the tightly coupled primary and secondary metabolic pathways and perturbation in its function results in pronounced effects on growth and metabolism outside of cell wall biosynthesis of Populus.« less

Distribution of alginate and cellulose and regulatory role of calcium in the cell wall of the brown alga Ectocarpus siliculosus (Ectocarpales, Phaeophyceae).

PubMed

Terauchi, Makoto; Nagasato, Chikako; Inoue, Akira; Ito, Toshiaki; Motomura, Taizo

2016-08-01

This work investigated a correlation between the three-dimensional architecture and compound-components of the brown algal cell wall. Calcium greatly contributes to the cell wall integrity. Brown algae have a unique cell wall consisting of alginate, cellulose, and sulfated polysaccharides. However, the relationship between the architecture and the composition of the cell wall is poorly understood. Here, we investigated the architecture of the cell wall and the effect of extracellular calcium in the sporophyte and gametophyte of the model brown alga, Ectocarpus siliculosus (Dillwyn) Lyngbye, using transmission electron microscopy, histochemical, and immunohistochemical studies. The lateral cell wall of vegetative cells of the sporophyte thalli had multilayered architecture containing electron-dense and negatively stained fibrils. Electron tomographic analysis showed that the amount of the electron-dense fibrils and the junctions was different between inner and outer layers, and between the perpendicular and tangential directions of the cell wall. By immersing the gametophyte thalli in the low-calcium (one-eighth of the normal concentration) artificial seawater medium, the fibrous layers of the lateral cell wall of vegetative cells became swollen. Destruction of cell wall integrity was also induced by the addition of sorbitol. The results demonstrated that electron-dense fibrils were composed of alginate-calcium fibrous gels, and electron negatively stained fibrils were crystalline cellulose microfibrils. It was concluded that the spatial arrangement of electron-dense fibrils was different between the layers and between the directions of the cell wall, and calcium was necessary for maintaining the fibrous layers in the cell wall. This study provides insights into the design principle of the brown algal cell wall.

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

PubMed

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

2016-10-01

Cell walls of grasses, including cereal crops and biofuel grasses, comprise the majority of plant biomass and intimately influence plant growth, development and physiology. However, the functions of many cell wall synthesis genes, and the relationships among and the functions of cell wall components remain obscure. To better understand the patterns of cell wall accumulation and identify genes that act in grass cell wall biosynthesis, we characterized 30 samples from aerial organs of rice (Oryza sativa cv. Kitaake) at 10 developmental time points, 3-100 d post-germination. Within these samples, we measured 15 cell wall chemical components, enzymatic digestibility and 18 cell wall polysaccharide epitopes/ligands. We also used quantitative reverse transcription-PCR to measure expression of 50 glycosyltransferases, 15 acyltransferases and eight phenylpropanoid genes, many of which had previously been identified as being highly expressed in rice. Most cell wall components vary significantly during development, and correlations among them support current understanding of cell walls. We identified 92 significant correlations between cell wall components and gene expression and establish nine strong hypotheses for genes that synthesize xylans, mixed linkage glucan and pectin components. This work provides an extensive analysis of cell wall composition throughout rice development, identifies genes likely to synthesize grass cell walls, and provides a framework for development of genetically improved grasses for use in lignocellulosic biofuel production and agriculture. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Peptidoglycan turnover and recycling in Gram-positive bacteria.

PubMed

Reith, Jan; Mayer, Christoph

2011-10-01

Bacterial cells are protected by an exoskeleton, the stabilizing and shape-maintaining cell wall, consisting of the complex macromolecule peptidoglycan. In view of its function, it could be assumed that the cell wall is a static structure. In truth, however, it is steadily broken down by peptidoglycan-cleaving enzymes during cell growth. In this process, named cell wall turnover, in one generation up to half of the preexisting peptidoglycan of a bacterial cell is released from the wall. This would result in a massive loss of cell material, if turnover products were not be taken up and recovered. Indeed, in the Gram-negative model organism Escherichia coli, peptidoglycan recovery has been recognized as a complex pathway, named cell wall recycling. It involves about a dozen dedicated recycling enzymes that convey cell wall turnover products to peptidoglycan synthesis or energy pathways. Whether Gram-positive bacteria also recover their cell wall is currently questioned. Given the much larger portion of peptidoglycan in the cell wall of Gram-positive bacteria, however, recovery of the wall material would provide an even greater benefit in these organisms compared to Gram-negatives. Consistently, in many Gram-positives, orthologs of recycling enzymes were identified, indicating that the cell wall may also be recycled in these organisms. This mini-review provides a compilation of information about cell wall turnover and recycling in Gram-positive bacteria during cell growth and division, including recent findings relating to muropeptide recovery in Bacillus subtilis and Clostridium acetobutylicum from our group. Furthermore, the impact of cell wall turnover and recycling on biotechnological processes is discussed.

RADIOAUTOGRAPHIC STUDY OF CELL WALL DEPOSITION IN GROWING PLANT CELLS

PubMed Central

Ray, Peter M.

1967-01-01

Segments cut from growing oat coleoptiles and pea stems were fed glucose-3H in presence and absence of the growth hormone indoleacetic acid (IAA). By means of electron microscope radioautography it was demonstrated that new cell wall material is deposited both at the wall surface (apposition) and within the preexisting wall structure (internally). Quantitative profiles for the distribution of incorporation with position through the thickness of the wall were obtained for the thick outer wall of epidermal cells. With both oat coleoptile and pea stem epidermal outer walls, it was found that a larger proportion of the newly synthesized wall material appeared to become incorporated within the wall in the presence of IAA. Extraction experiments on coleoptile tissue showed that activity that had been incorporated into the cell wall interior represented noncellulosic constituents, mainly hemicelluloses, whereas cellulose was deposited largely or entirely by apposition. It seems possible that internal incorporation of hemicelluloses plays a role in the cell wall expansion process that is involved in cell growth. PMID:6064369

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

PubMed

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

2015-09-02

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

Genotoxicity of multi-walled carbon nanotubes at occupationally relevant doses

PubMed Central

2014-01-01

Carbon nanotubes are commercially-important products of nanotechnology; however, their low density and small size makes carbon nanotube respiratory exposures likely during their production or processing. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to single-walled carbon nanotubes (SWCNT). In this study, we examined whether multi-walled carbon nanotubes (MWCNT) cause mitotic spindle damage in cultured cells at doses equivalent to 34 years of exposure at the NIOSH Recommended Exposure Limit (REL). MWCNT induced a dose responsive increase in disrupted centrosomes, abnormal mitotic spindles and aneuploid chromosome number 24 hours after exposure to 0.024, 0.24, 2.4 and 24 μg/cm2 MWCNT. Monopolar mitotic spindles comprised 95% of disrupted mitoses. Three-dimensional reconstructions of 0.1 μm optical sections showed carbon nanotubes integrated with microtubules, DNA and within the centrosome structure. Cell cycle analysis demonstrated a greater number of cells in S-phase and fewer cells in the G2 phase in MWCNT-treated compared to diluent control, indicating a G1/S block in the cell cycle. The monopolar phenotype of the disrupted mitotic spindles and the G1/S block in the cell cycle is in sharp contrast to the multi-polar spindle and G2 block in the cell cycle previously observed following exposure to SWCNT. One month following exposure to MWCNT there was a dramatic increase in both size and number of colonies compared to diluent control cultures, indicating a potential to pass the genetic damage to daughter cells. Our results demonstrate significant disruption of the mitotic spindle by MWCNT at occupationally relevant exposure levels. PMID:24479647

A PI 4. 6 peroxidase that specifically crosslinks extensin precursors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upham, B.L; Alizadeh, H.; Ryan, K.J.

1991-05-01

The primary cell wall is a microcomposite of cellulose, pectin, hemicellulose and protein. The warp-weft model of the primary cell wall hypothesize that extensin monomers are intermolecularly crosslinked orthogonal to the cellulose microfibril thus mechanically coupling the major load-bearing polymer: cellulose. Media of tomato cell cultures contains heat labile, peroxide dependent crosslinking activity, as determined by the rate of decrease in monomer concentration analyzed via Superose-6. Isoelectric focusing of tomato cell culture media indicated crosslinking was predominantly in the acidic peroxidase fraction (pI4.6). This peroxidase was partially purified by ultracentrifugation, DEAE-Trisacryl and HPLC-DEAE chromatography techniques resulting in a 90 foldmore » purification and 45% yield. A second acidic peroxidase eluted from the HPLC-DEAE column had 25% of the crosslinking activity of the pI 4.6 peroxidase. Purified basic peroxidase had only 0.7% of the activity of the pI 4.6 peroxidase. The specific activity of the pI 4.6 peroxidase was 5,473 mg extensin crosslinked/min/mg peroxidase. The pI 4.6 peroxidase crosslinked the following extensins: tomato I and II, carrot, Ginkgo II and did not crosslink Ginkgo I, Douglas Fir, Maize, Asparagus I and II, and sugarbeet extensins as well as bovine serum albumin. Comparison of motifs common to extensins that are crosslinked by the pI 4.6 peroxidase may help identify the crosslink domain(s) of extension.« less

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

PubMed

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.

Plant and algal cell walls: diversity and functionality

PubMed Central

Popper, Zoë A.; Ralet, Marie-Christine; Domozych, David S.

2014-01-01

Background Although plants and many algae (e.g. the Phaeophyceae, brown, and Rhodophyceae, red) are only very distantly related they are united in their possession of carbohydrate-rich cell walls, which are of integral importance being involved in many physiological processes. Furthermore, wall components have applications within food, fuel, pharmaceuticals, fibres (e.g. for textiles and paper) and building materials and have long been an active topic of research. As shown in the 27 papers in this Special Issue, as the major deposit of photosynthetically fixed carbon, and therefore energy investment, cell walls are of undisputed importance to the organisms that possess them, the photosynthetic eukaryotes (plants and algae). The complexities of cell wall components along with their interactions with the biotic and abiotic environment are becoming increasingly revealed. Scope The importance of plant and algal cell walls and their individual components to the function and survival of the organism, and for a number of industrial applications, are illustrated by the breadth of topics covered in this issue, which includes papers concentrating on various plants and algae, developmental stages, organs, cell wall components, and techniques. Although we acknowledge that there are many alternative ways in which the papers could be categorized (and many would fit within several topics), we have organized them as follows: (1) cell wall biosynthesis and remodelling, (2) cell wall diversity, and (3) application of new technologies to cell walls. Finally, we will consider future directions within plant cell wall research. Expansion of the industrial uses of cell walls and potentially novel uses of cell wall components are both avenues likely to direct future research activities. Fundamentally, it is the continued progression from characterization (structure, metabolism, properties and localization) of individual cell wall components through to defining their roles in almost every aspect of plant and algal physiology that will present many of the major challenges in future cell wall research. PMID:25453142

Plant and algal cell walls: diversity and functionality.

PubMed

Popper, Zoë A; Ralet, Marie-Christine; Domozych, David S

2014-10-01

Although plants and many algae (e.g. the Phaeophyceae, brown, and Rhodophyceae, red) are only very distantly related they are united in their possession of carbohydrate-rich cell walls, which are of integral importance being involved in many physiological processes. Furthermore,wall components have applications within food, fuel, pharmaceuticals, fibres (e.g. for textiles and paper) and building materials and have long been an active topic of research. As shown in the 27 papers in this Special Issue, as the major deposit of photosynthetically fixed carbon, and therefore energy investment, cell walls are of undisputed importance to the organisms that possess them, the photosynthetic eukaryotes ( plants and algae). The complexities of cell wall components along with their interactions with the biotic and abiotic environment are becoming increasingly revealed. The importance of plant and algal cell walls and their individual components to the function and survival of the organism, and for a number of industrial applications, are illustrated by the breadth of topics covered in this issue, which includes papers concentrating on various plants and algae, developmental stages, organs, cell wall components, and techniques. Although we acknowledge that there are many alternative ways in which the papers could be categorized (and many would fit within several topics), we have organized them as follows: (1) cell wall biosynthesis and remodelling, (2) cell wall diversity, and (3) application of new technologies to cell walls. Finally, we will consider future directions within plant cell wall research. Expansion of the industrial uses of cell walls and potentially novel uses of cell wall components are both avenues likely to direct future research activities. Fundamentally, it is the continued progression from characterization (structure, metabolism, properties and localization) of individual cell wall components through to defining their roles in almost every aspect of plant and algal physiology that will present many of the major challenges in future cell wall research.

Genetic diversity of root anatomy in wild and cultivated Manihot species.

PubMed

Bomfim, N N; Graciano-Ribeiro, D; Nassar, N M A

2011-04-05

An anatomical study of roots was conducted on two wild Manihot species, namely M. glaziovii and M. fortalezensis, and two cassava varieties, M. esculenta Crantz variety UnB 201 and M. esculenta variety UnB 122, to identify taxonomic differences in primary growth. Anatomical characters of cassava roots have been rarely investigated. Their study may help cassava breeders to identify varieties with economically important characters, such as tolerance to drought. We investigated tap and lateral adventitious roots of two specimens of each clone or species. Free-hand cross-sections of roots were drawn; these had been clarified with 20% sodium hypochlorite solution, stained with 1% safranin-alcian blue ethanolic solution, dehydrated in ethanol series and butyl acetate and mounted in synthetic resin. Anatomical differences among Manihot species and varieties were found in the epidermal and exodermal cell shape and wall thickness, content of cortical parenchyma, and number of xylem poles. Wall thickness of the epidermis and exodermis of tap root were similar in all species, while in the lateral root there were differences in cell shape and wall thickness. Epidermal cells with thick walls were found in the tap root of all species and in lateral roots of cassava varieties. This character is apparently associated with tolerance to drought and disease. The variation in the number of xylem poles of cassava varieties was larger (4-8) than in wild species (4-6), and appears to support the hybrid origin of cassava.

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

NASA Astrophysics Data System (ADS)

Wang, Siyuan

2012-02-01

Bacteria come in a variety of shapes. While the peptidoglycan (PG) cell wall serves as an exoskeleton that defines the static cell shape, the internal bacterial cytoskeleton mediates cell shape by recruiting PG synthesis machinery and thus defining the pattern of cell-wall synthesis. While much is known about the chemistry and biology of the cytoskeleton and cell wall, much of their biophysics, including essential aspects of the functionality, dynamics, and organization, remain unknown. This dissertation aims to elucidate the detailed biophysical mechanisms of cytoskeleton guided wall synthesis. First, I find that the bacterial cytoskeleton MreB contributes nearly as much to the rigidity of an Escherichia coli cell as the cell wall. This conclusion implies that the cytoskeletal polymer MreB applies meaningful force to the cell wall, an idea favored by theoretical modeling of wall growth, and suggests an evolutionary origin of cytoskeleton-governed cell rigidity. Second, I observe that MreB rotates around the long axis of E. coli, and the motion depends on wall synthesis. This is the first discovery of a cell-wall assembly driven molecular motor in bacteria. Third, I prove that both cell-wall synthesis and the PG network have chiral ordering, which is established by the spatial pattern of MreB. This work links the molecular structure of the cytoskeleton and of the cell wall with organismal-scale behavior. Finally, I develop a mathematical model of cytoskeleton-cell membrane interactions, which explains the preferential orientation of different cytoskeleton components in bacteria.

Wall effects in continuous microfluidic magneto-affinity cell separation.

PubMed

Wu, Liqun; Zhang, Yong; Palaniapan, Moorthi; Roy, Partha

2010-05-01

Continuous microfluidic magneto-affinity cell separator combines unique microscale flow phenomenon with advantageous nanobead properties, to isolate cells with high specificity. Owing to the comparable size of the cell-bead complexes and the microchannels, the walls of the microchannel exert a strong influence on the separation of cells by this method. We present a theoretical and experimental study that provides a quantitative description of hydrodynamic wall interactions and wall rolling velocity of cells. A transient convection model describes the transport of cells in two-phase microfluidic flow under the influence of an external magnetic field. Transport of cells along the microchannel walls is also considered via an additional equation. Results show the variation of cell flux in the fluid phases and the wall as a function of a dimensionless parameter arising in the equations. Our results suggest that conditions may be optimized to maximize cell separation while minimizing contact with the wall surfaces. Experimentally measured cell rolling velocities on the wall indicate the presence of other near-wall forces in addition to fluid shear forces. Separation of a human colon carcinoma cell line from a mixture of red blood cells, with folic acid conjugated 1 microm and 200 nm beads, is reported.

Screen for agents that induce autolysis in Bacillus subtilis.

PubMed

Lacriola, Christopher J; Falk, Shaun P; Weisblum, Bernard

2013-01-01

The growing prevalence of antibiotic-resistant infections underscores the need to discover new antibiotics and to use them with maximum effectiveness. In response to these needs, we describe a screening protocol for the discovery of autolysis-inducing agents that uses two Bacillus subtilis reporter strains, SH-536 and BAU-102. To screen chemical libraries, autolysis-inducing agents were first identified with a BAU-102-based screen and then subdivided with SH-536 into two major groups: those that induce autolysis by their direct action on the cell membrane and those that induce autolysis secondary to inhibition of cell wall synthesis. SH-536 distinguishes between the two groups of autolysis-inducing agents by synthesizing and then releasing β-galactosidase (β-Gal) in late stationary phase at a time that cells have nearly stopped growing and are therefore tolerant of cell wall synthesis inhibitors. Four hits, named compound 2, compound 3, compound 5, and compound 24, obtained previously as inducers of autolysis by screening a 10,080-compound discovery library with BAU-102, were probed with SH-536 and found to release β-Gal, indicating that their mode of action was to permeabilize the B. subtilis cell membrane. The four primary hits inhibited growth in Staphylococcus aureus, Enterococcus faecium, Bacillus subtilis, and Bacillus anthracis, with MICs in the 12.5- to 25-μg/ml (20 to 60 μM) range. The four primary hits were further used to probe B. subtilis, and their action was partially characterized with respect to the dependence of induced autolysis on specific autolysins.

Screen for Agents That Induce Autolysis in Bacillus subtilis

PubMed Central

Lacriola, Christopher J.; Falk, Shaun P.

2013-01-01

The growing prevalence of antibiotic-resistant infections underscores the need to discover new antibiotics and to use them with maximum effectiveness. In response to these needs, we describe a screening protocol for the discovery of autolysis-inducing agents that uses two Bacillus subtilis reporter strains, SH-536 and BAU-102. To screen chemical libraries, autolysis-inducing agents were first identified with a BAU-102-based screen and then subdivided with SH-536 into two major groups: those that induce autolysis by their direct action on the cell membrane and those that induce autolysis secondary to inhibition of cell wall synthesis. SH-536 distinguishes between the two groups of autolysis-inducing agents by synthesizing and then releasing β-galactosidase (β-Gal) in late stationary phase at a time that cells have nearly stopped growing and are therefore tolerant of cell wall synthesis inhibitors. Four hits, named compound 2, compound 3, compound 5, and compound 24, obtained previously as inducers of autolysis by screening a 10,080-compound discovery library with BAU-102, were probed with SH-536 and found to release β-Gal, indicating that their mode of action was to permeabilize the B. subtilis cell membrane. The four primary hits inhibited growth in Staphylococcus aureus, Enterococcus faecium, Bacillus subtilis, and Bacillus anthracis, with MICs in the 12.5- to 25-μg/ml (20 to 60 μM) range. The four primary hits were further used to probe B. subtilis, and their action was partially characterized with respect to the dependence of induced autolysis on specific autolysins. PMID:23089762

Genome wide comprehensive analysis and web resource development on cell wall degrading enzymes from phyto-parasitic nematodes.

PubMed

Rai, Krishan Mohan; Balasubramanian, Vimal Kumar; Welker, Cassie Marie; Pang, Mingxiong; Hii, Mei Mei; Mendu, Venugopal

2015-08-01

The plant cell wall serves as a primary barrier against pathogen invasion. The success of a plant pathogen largely depends on its ability to overcome this barrier. During the infection process, plant parasitic nematodes secrete cell wall degrading enzymes (CWDEs) apart from piercing with their stylet, a sharp and hard mouthpart used for successful infection. CWDEs typically consist of cellulases, hemicellulases, and pectinases, which help the nematode to infect and establish the feeding structure or form a cyst. The study of nematode cell wall degrading enzymes not only enhance our understanding of the interaction between nematodes and their host, but also provides information on a novel source of enzymes for their potential use in biomass based biofuel/bioproduct industries. Although there is comprehensive information available on genome wide analysis of CWDEs for bacteria, fungi, termites and plants, but no comprehensive information available for plant pathogenic nematodes. Herein we have performed a genome wide analysis of CWDEs from the genome sequenced phyto pathogenic nematode species and developed a comprehensive publicly available database. In the present study, we have performed a genome wide analysis for the presence of CWDEs from five plant parasitic nematode species with fully sequenced genomes covering three genera viz. Bursaphelenchus, Glorodera and Meloidogyne. Using the Hidden Markov Models (HMM) conserved domain profiles of the respective gene families, we have identified 530 genes encoding CWDEs that are distributed among 24 gene families of glycoside hydrolases (412) and polysaccharide lyases (118). Furthermore, expression profiles of these genes were analyzed across the life cycle of a potato cyst nematode. Most genes were found to have moderate to high expression from early to late infectious stages, while some clusters were invasion stage specific, indicating the role of these enzymes in the nematode's infection and establishment process. Additionally, we have also developed a Nematode's Plant Cell Wall Degrading Enzyme (NCWDE) database as a platform to provide a comprehensive outcome of the present study. Our study provides collective information about different families of CWDEs from five different sequenced plant pathogenic nematode species. The outcomes of this study will help in developing better strategies to curtail the nematode infection, as well as help in identification of novel cell wall degrading enzymes for biofuel/bioproduct industries.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dugger, W.M.; Bartnicki-Garcia, S.

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

Architecture and Biosynthesis of the Saccharomyces cerevisiae Cell Wall

PubMed Central

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

Retention of Proanthocyanidin in Wine-like Solution Is Conferred by a Dynamic Interaction between Soluble and Insoluble Grape Cell Wall Components.

PubMed

Bindon, Keren A; Li, Sijing; Kassara, Stella; Smith, Paul A

2016-11-09

For better understanding of the factors that impact proanthocyanidin (PA) adsorption by insoluble cell walls or interaction with soluble cell wall-derived components, application of a commercial polygalacturonase enzyme preparation was investigated to modify grape cell wall structure. Soluble and insoluble cell wall material was isolated from the skin and mesocarp components of Vitis vinifera Shiraz grapes. It was observed that significant depolymerization of the insoluble grape cell wall occurred following enzyme application to both grape cell wall fractions, with increased solubilization of rhamnogalacturonan-enriched, low molecular weight polysaccharides. However, in the case of grape mesocarp, the solubilization of protein from cell walls (in buffer) was significant and increased only slightly by the enzyme treatment. Enzyme treatment significantly reduced the adsorption of PA by insoluble cell walls, but this effect was observed only when material solubilized from grape cell walls had been removed. The loss of PA through interaction with the soluble cell wall fraction was observed to be greater for mesocarp than skin cell walls. Subsequent experiments on the soluble mesocarp cell wall fraction confirmed a role for protein in the precipitation of PA. This identified a potential mechanism by which extracted grape PA may be lost from wine during vinification, as a precipitate with solubilized grape mesocarp proteins. Although protein was a minor component in terms of total concentration, losses of PA via precipitation with proteins were in the order of 50% of available PA. PA-induced precipitation could proceed until all protein was removed from solution and may account for the very low levels of residual protein observed in red wines. The results point to a dynamic interaction of grape insoluble and soluble components in modulating PA retention in wine.

Genome-wide transcriptome analysis of the transition from primary to secondary stem development in Populus trichocarpa

PubMed Central

2010-01-01

Background With its genome sequence and other experimental attributes, Populus trichocarpa has become the model species for genomic studies of wood development. Wood is derived from secondary growth of tree stems, and begins with the development of a ring of vascular cambium in the young developing stem. The terminal region of the developing shoot provides a steep developmental gradient from primary to secondary growth that facilitates identification of genes that play specialized functions during each of these phases of growth. Results Using a genomic microarray representing the majority of the transcriptome, we profiled gene expression in stem segments that spanned primary to secondary growth. We found 3,016 genes that were differentially expressed during stem development (Q-value ≤ 0.05; >2-fold expression variation), and 15% of these genes encode proteins with no significant identities to known genes. We identified all gene family members putatively involved in secondary growth for carbohydrate active enzymes, tubulins, actins, actin depolymerizing factors, fasciclin-like AGPs, and vascular development-associated transcription factors. Almost 70% of expressed transcription factors were upregulated during the transition to secondary growth. The primary shoot elongation region of the stem contained specific carbohydrate active enzyme and expansin family members that are likely to function in primary cell wall synthesis and modification. Genes involved in plant defense and protective functions were also dominant in the primary growth region. Conclusion Our results describe the global patterns of gene expression that occur during the transition from primary to secondary stem growth. We were able to identify three major patterns of gene expression and over-represented gene ontology categories during stem development. The new regulatory factors and cell wall biogenesis genes that we identified provide candidate genes for further functional characterization, as well as new tools for molecular breeding and biotechnology aimed at improvement of tree growth rate, crown form, and wood quality. PMID:20199690

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

PubMed

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.

Bacterial cell-wall recycling

PubMed Central

Johnson, Jarrod W.; Fisher, Jed F.; Mobashery, Shahriar

2012-01-01

Many Gram-negative and Gram-positive bacteria recycle a significant proportion of the peptidoglycan components of their cell walls during their growth and septation. In many—and quite possibly all—bacteria, the peptidoglycan fragments are recovered and recycled. While cell-wall recycling is beneficial for the recovery of resources, it also serves as a mechanism to detect cell-wall–targeting antibiotics and to regulate resistance mechanisms. In several Gram-negative pathogens, anhydro-MurNAc-peptide cell-wall fragments regulate AmpC β-lactamase induction. In some Gram-positive organisms, short peptides derived from the cell wall regulate the induction of both β-lactamase and β-lactam-resistant penicillin-binding proteins. The involvement of peptidoglycan recycling with resistance regulation suggests that inhibitors of the enzymes involved in the recycling might synergize with cell-wall-targeted antibiotics. Indeed, such inhibitors improve the potency of β-lactams in vitro against inducible AmpC β-lactamase-producing bacteria. We describe the key steps of cell-wall remodeling and recycling, the regulation of resistance mechanisms by cell-wall recycling, and recent advances toward the discovery of cell-wall recycling inhibitors. PMID:23163477

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

PubMed Central

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

Wall relaxation and the driving forces for cell expansive growth

NASA Technical Reports Server (NTRS)

Cosgrove, D. J.

1987-01-01

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

Two endogenous proteins that induce cell wall extension in plants

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

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

PubMed

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

2016-07-01

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

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

PubMed

Ao, Jie; Free, Stephen J

2017-04-01

The Neurospora crassa genome encodes five GH72 family transglycosylases, and four of these enzymes (GEL-1, GEL-2, GEL-3 and GEL-5) have been found to be present in the cell wall proteome. We carried out an extensive genetic analysis on the role of these four transglycosylases in cell wall biogenesis and demonstrated that the transglycosylases are required for the formation of a normal cell wall. As suggested by the proteomic analysis, we found that multiple transglycosylases were being expressed in N. crassa cells and that different combinations of the enzymes are required in different cell types. The combination of GEL-1, GEL-2 and GEL-5 is required for the growth of vegetative hyphae, while the GEL-1, GEL-2, GEL-3 combination is needed for the production of aerial hyphae and conidia. Our data demonstrates that the enzymes are redundant with partially overlapping enzymatic activities, which provides the fungus with a robust cell wall biosynthetic system. Characterization of the transglycosylase-deficient mutants demonstrated that the incorporation of cell wall proteins was severely compromised. Interestingly, we found that the transglycosylase-deficient mutant cell walls contained more β-1,3-glucan than the wild type cell wall. Our results demonstrate that the GH72 transglycosylases are not needed for the incorporation of β-1,3-glucan into the cell wall, but they are required for the incorporation of cell wall glycoprotein into the cell wall. Copyright © 2017 Elsevier Inc. All rights reserved.

Label-free in situ Imaging of Lignification in Plant Cell Walls

PubMed Central

Schmidt, Martin; Perera, Pradeep; Schwartzberg, Adam M.; Adams, Paul D.; Schuck, P. James

2010-01-01

Meeting growing energy demands safely and efficiently is a pressing global challenge. Therefore, research into biofuels production that seeks to find cost-effective and sustainable solutions has become a topical and critical task. Lignocellulosic biomass is poised to become the primary source of biomass for the conversion to liquid biofuels1-6. However, the recalcitrance of these plant cell wall materials to cost-effective and efficient degradation presents a major impediment for their use in the production of biofuels and chemicals4. In particular, lignin, a complex and irregular poly-phenylpropanoid heteropolymer, becomes problematic to the postharvest deconstruction of lignocellulosic biomass. For example in biomass conversion for biofuels, it inhibits saccharification in processes aimed at producing simple sugars for fermentation7. The effective use of plant biomass for industrial purposes is in fact largely dependent on the extent to which the plant cell wall is lignified. The removal of lignin is a costly and limiting factor8 and lignin has therefore become a key plant breeding and genetic engineering target in order to improve cell wall conversion. Analytical tools that permit the accurate rapid characterization of lignification of plant cell walls become increasingly important for evaluating a large number of breeding populations. Extractive procedures for the isolation of native components such as lignin are inevitably destructive, bringing about significant chemical and structural modifications9-11. Analytical chemical in situ methods are thus invaluable tools for the compositional and structural characterization of lignocellulosic materials. Raman microscopy is a technique that relies on inelastic or Raman scattering of monochromatic light, like that from a laser, where the shift in energy of the laser photons is related to molecular vibrations and presents an intrinsic label-free molecular "fingerprint" of the sample. Raman microscopy can afford non-destructive and comparatively inexpensive measurements with minimal sample preparation, giving insights into chemical composition and molecular structure in a close to native state. Chemical imaging by confocal Raman microscopy has been previously used for the visualization of the spatial distribution of cellulose and lignin in wood cell walls12-14. Based on these earlier results, we have recently adopted this method to compare lignification in wild type and lignin-deficient transgenic Populus trichocarpa (black cottonwood) stem wood15. Analyzing the lignin Raman bands16,17 in the spectral region between 1,600 and 1,700 cm-1, lignin signal intensity and localization were mapped in situ. Our approach visualized differences in lignin content, localization, and chemical composition. Most recently, we demonstrated Raman imaging of cell wall polymers in Arabidopsis thaliana with lateral resolution that is sub-μm18. Here, this method is presented affording visualization of lignin in plant cell walls and comparison of lignification in different tissues, samples or species without staining or labeling of the tissues. PMID:21085100

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

PubMed

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.

Plant cell wall signalling and receptor-like kinases.

PubMed

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.

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

PubMed

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.

Designer biomass for next-generation biorefineries: leveraging recent insights into xylan structure and biosynthesis.

PubMed

Smith, Peter J; Wang, Hsin-Tzu; York, William S; Peña, Maria J; Urbanowicz, Breeanna R

2017-01-01

Xylans are the most abundant noncellulosic polysaccharides in lignified secondary cell walls of woody dicots and in both primary and secondary cell walls of grasses. These polysaccharides, which comprise 20-35% of terrestrial biomass, present major challenges for the efficient microbial bioconversion of lignocellulosic feedstocks to fuels and other value-added products. Xylans play a significant role in the recalcitrance of biomass to degradation, and their bioconversion requires metabolic pathways that are distinct from those used to metabolize cellulose. In this review, we discuss the key differences in the structural features of xylans across diverse plant species, how these features affect their interactions with cellulose and lignin, and recent developments in understanding their biosynthesis. In particular, we focus on how the combined structural and biosynthetic knowledge can be used as a basis for biomass engineering aimed at developing crops that are better suited as feedstocks for the bioconversion industry.

Characterization of the SOS meta-regulon in the human gut microbiome.

PubMed

Cornish, Joseph P; Sanchez-Alberola, Neus; O'Neill, Patrick K; O'Keefe, Ronald; Gheba, Jameel; Erill, Ivan

2014-05-01

Data from metagenomics projects remain largely untapped for the analysis of transcriptional regulatory networks. Here, we provide proof-of-concept that metagenomic data can be effectively leveraged to analyze regulatory networks by characterizing the SOS meta-regulon in the human gut microbiome. We combine well-established in silico and in vitro techniques to mine the human gut microbiome data and determine the relative composition of the SOS network in a natural setting. Our analysis highlights the importance of translesion synthesis as a primary function of the SOS response. We predict the association of this network with three novel protein clusters involved in cell wall biogenesis, chromosome partitioning and restriction modification, and we confirm binding of the SOS response transcriptional repressor to sites in the promoter of a cell wall biogenesis enzyme, a phage integrase and a death-on-curing protein. We discuss the implications of these findings and the potential for this approach for metagenome analysis.

Remarkable proanthocyanidin adsorption properties of monastrell pomace cell wall material highlight its potential use as an alternative fining agent in red wine production.

PubMed

Bautista-Ortín, Ana Belén; Ruiz-García, Yolanda; Marín, Fátima; Molero, Noelia; Apolinar-Valiente, Rafael; Gómez-Plaza, Encarna

2015-01-21

The existence of interactions between the polysaccharides of vegetal cell walls and proanthocyanins makes this cell wall material an interesting option for its use as a fining agent to reduce the level of proanthocyanins in wines. Pomace wastes from the winery are widely available and a source of cell wall material, and the identification of varieties whose pomace cell walls present high proanthocyanin binding capacity and of processing methods that could enhance their adsorption properties could be of great interest. This study compared the proanthocyanin adsorption properties of pomace cell wall material from three different grape varieties (Monastrell, Cabernet Sauvignon, and Syrah), and the results were compared with those obtained using fresh grape cell walls. Also, the effect of the vinification method has been studied. Analysis of the proanthocyanidins in the solution after reaction with the cell wall material, using phloroglucinolysis and size exclusion chromatography, provided quantitative and qualitative information on the adsorbed and nonadsorbed compounds. A highlight of this study was the observation that Monastrell pomace cell wall material showed a strong affinity for proanthocyanidins, with values similar to that obtained for fresh grapes cell walls, and a preferential binding of high molecular mass proanthocyanidins, so these pomace cell walls could be used in wines to reduce astringency. The use of maceration enzymes during vinification had little effect on the retention capacity of the pomace cell walls obtained from this vinification, although an increase in the retention of low molecular mass proanthocyanidins was observed, and this might have implications for wine sensory properties.

Visualizing chemical functionality in plant cell walls

DOE PAGES

Zeng, Yining; Himmel, Michael E.; Ding, Shi-You

2017-11-30

Understanding plant cell wall cross-linking chemistry and polymeric architecture is key to the efficient utilization of biomass in all prospects from rational genetic modification to downstream chemical and biological conversion to produce fuels and value chemicals. In fact, the bulk properties of cell wall recalcitrance are collectively determined by its chemical features over a wide range of length scales from tissue, cellular to polymeric architectures. Microscopic visualization of cell walls from the nanometer to the micrometer scale offers an in situ approach to study their chemical functionality considering its spatial and chemical complexity, particularly the capabilities of characterizing biomass non-destructivelymore » and in real-time during conversion processes. Microscopic characterization has revealed heterogeneity in the distribution of chemical features, which would otherwise be hidden in bulk analysis. Key microscopic features include cell wall type, wall layering, and wall composition - especially cellulose and lignin distributions. Microscopic tools, such as atomic force microscopy, stimulated Raman scattering microscopy, and fluorescence microscopy, have been applied to investigations of cell wall structure and chemistry from the native wall to wall treated by thermal chemical pretreatment and enzymatic hydrolysis. While advancing our current understanding of plant cell wall recalcitrance and deconstruction, microscopic tools with improved spatial resolution will steadily enhance our fundamental understanding of cell wall function.« less

Visualizing chemical functionality in plant cell walls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeng, Yining; Himmel, Michael E.; Ding, Shi-You

Understanding plant cell wall cross-linking chemistry and polymeric architecture is key to the efficient utilization of biomass in all prospects from rational genetic modification to downstream chemical and biological conversion to produce fuels and value chemicals. In fact, the bulk properties of cell wall recalcitrance are collectively determined by its chemical features over a wide range of length scales from tissue, cellular to polymeric architectures. Microscopic visualization of cell walls from the nanometer to the micrometer scale offers an in situ approach to study their chemical functionality considering its spatial and chemical complexity, particularly the capabilities of characterizing biomass non-destructivelymore » and in real-time during conversion processes. Microscopic characterization has revealed heterogeneity in the distribution of chemical features, which would otherwise be hidden in bulk analysis. Key microscopic features include cell wall type, wall layering, and wall composition - especially cellulose and lignin distributions. Microscopic tools, such as atomic force microscopy, stimulated Raman scattering microscopy, and fluorescence microscopy, have been applied to investigations of cell wall structure and chemistry from the native wall to wall treated by thermal chemical pretreatment and enzymatic hydrolysis. While advancing our current understanding of plant cell wall recalcitrance and deconstruction, microscopic tools with improved spatial resolution will steadily enhance our fundamental understanding of cell wall function.« less

Visualizing chemical functionality in plant cell walls.

PubMed

Zeng, Yining; Himmel, Michael E; Ding, Shi-You

2017-01-01

Understanding plant cell wall cross-linking chemistry and polymeric architecture is key to the efficient utilization of biomass in all prospects from rational genetic modification to downstream chemical and biological conversion to produce fuels and value chemicals. In fact, the bulk properties of cell wall recalcitrance are collectively determined by its chemical features over a wide range of length scales from tissue, cellular to polymeric architectures. Microscopic visualization of cell walls from the nanometer to the micrometer scale offers an in situ approach to study their chemical functionality considering its spatial and chemical complexity, particularly the capabilities of characterizing biomass non-destructively and in real-time during conversion processes. Microscopic characterization has revealed heterogeneity in the distribution of chemical features, which would otherwise be hidden in bulk analysis. Key microscopic features include cell wall type, wall layering, and wall composition-especially cellulose and lignin distributions. Microscopic tools, such as atomic force microscopy, stimulated Raman scattering microscopy, and fluorescence microscopy, have been applied to investigations of cell wall structure and chemistry from the native wall to wall treated by thermal chemical pretreatment and enzymatic hydrolysis. While advancing our current understanding of plant cell wall recalcitrance and deconstruction, microscopic tools with improved spatial resolution will steadily enhance our fundamental understanding of cell wall function.

[Primary central nervous system lymphoma mimicking ventriculitis].

PubMed

Yamamoto, Shiro; Nagano, Seiji; Shibata, Sumiya; Kunieda, Takeharu; Imai, Yukihiro; Kohara, Nobuo

2013-01-01

A 66-year-old man presented with deteriorated bradykinesia, gait disturbance, disorientation, and urinary incontinence for three weeks. Magnetic resonance imaging (MRI) showed dilatation of the ventricles. Cerebrospinal fluid (CSF) examination demonstrated lymphocytic pleocytosis, elevation of protein levels, and decreased of glucose levels. A gadolinium-enhanced MRI revealed lesions in the ventricular wall and choroid plexus, mimicking ventriculitis. No evidence of bacterial, fungal, mycobacterial, or viral infections were observed in the CSF. Flow cytometry of CSF showed predominance of CD20+, λ+ cells. PCR examination of CSF revealed positive IgH gene rearrangement, suggesting B cell lymphoma. Endoscopic brain biopsy showed diffuse large B cell lymphoma. As the patient had no evidence of lymphoma in the other organs, we made a diagnosed of primary central nervous system lymphoma (PCNSL). A limited intraventricular spread of PCNSL is rare but important as one of differential diagnosis of ventriculitis.

Seasonal and clonal variation in cellulose microfibril orientation during cell wall formation of tracheids in Cryptomeria japonica.

PubMed

Jyske, Tuula; Fujiwara, Takeshi; Kuroda, Katsushi; Iki, Taiichi; Zhang, Chunhua; Jyske, Tuomas K; Abe, Hisashi

2014-08-01

To investigate the biological mechanism by which trees control the changes in microfibril (MF) orientation among secondary cell wall layers of conifer tracheids, we studied seasonal variation in the orientation of newly deposited MFs during tracheid cell wall development in Japanese cedar (Cryptomeria japonica D. Don) trees growing in Central Japan (36°36'N, 140°39'E). Sample blocks were repeatedly collected from four 16-year-old clones of different origins during the growing season of 2010 to investigate the hypotheses that changes in cellulose MF orientation between wall layers exhibited seasonal and clonal differences. The progressive change in the orientation of newly deposited MFs on the primary and secondary cell wall layers of tracheids was detected by field-emission-scanning electron microscopy. Tracheid production and differentiation was studied by light microscopy. We observed a decreasing trend in the orientation of deposited MFs from earlywood to latewood in the S2 and S1 layers, where MFs appeared in a Z-helix. In contrast, no seasonal pattern in the orientation of the MFs in the S-helix was observed. Minor clonal variation was observed in the phenology of tracheid production and differentiation. We concluded that a seasonal decreasing trend in the orientation of the MFs in the Z-helix in S1 and S2 was present, whereas the MFs in other layers exhibited minor random variations. Thus, the orientation of the MFs in S2 was affected by seasonal factors, whereas the MFs in other layers were more intrinsically controlled. The within-ring variations in the MF orientation and thus the resulting average MF angle might also be related to genotypic differences in the tracheid production and differentiation rate. However, our results do not exclude other intrinsic and environmental regulations in the change in MF orientation, which remains a topic for future studies. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Developmental Localization and Methylesterification of Pectin Epitopes during Somatic Embryogenesis of Banana (Musa spp. AAA)

PubMed Central

Xu, Chunxiang; Zhao, Lu; Pan, Xiao; Šamaj, Jozef

2011-01-01

Background The plant cell walls play an important role in somatic embryogenesis and plant development. Pectins are major chemical components of primary cell walls while homogalacturonan (HG) is the most abundant pectin polysaccharide. Developmental regulation of HG methyl-esterification degree is important for cell adhesion, division and expansion, and in general for proper organ and plant development. Methodology/Principal Findings Developmental localization of pectic homogalacturonan (HG) epitopes and the (1→4)-β-D-galactan epitope of rhamnogalacturonan I (RG-I) and degree of pectin methyl-esterification (DM) were studied during somatic embryogenesis of banana (Musa spp. AAA). Histological analysis documented all major developmental stages including embryogenic cells (ECs), pre-globular, globular, pear-shaped and cotyledonary somatic embryos. Histochemical staining of extracellularly secreted pectins with ruthenium red showed the most intense staining at the surface of pre-globular, globular and pear-shaped somatic embryos. Biochemical analysis revealed developmental regulation of galacturonic acid content and DM in diverse embryogenic stages. Immunodots and immunolabeling on tissue sections revealed developmental regulation of highly methyl-esterified HG epitopes recognized by JIM7 and LM20 antibodies during somatic embryogenesis. Cell walls of pre-globular/globular and late-stage embryos contained both low methyl-esterified HG epitopes as well as partially and highly methyl-esterified ones. Extracellular matrix which covered surface of early developing embryos contained pectin epitopes recognized by 2F4, LM18, JIM5, JIM7 and LM5 antibodies. De-esterification of cell wall pectins by NaOH caused a decrease or an elimination of immunolabeling in the case of highly methyl-esterified HG epitopes. However, immunolabeling of some low methyl-esterified epitopes appeared stronger after this base treatment. Conclusions/Significance These data suggest that both low- and highly-methyl-esterified HG epitopes are developmentally regulated in diverse embryogenic stages during somatic embryogenesis. This study provides new information about pectin composition, HG methyl-esterification and developmental localization of pectin epitopes during somatic embryogenesis of banana. PMID:21826225

Fruit softening and pectin disassembly: an overview of nanostructural pectin modifications assessed by atomic force microscopy

PubMed Central

Paniagua, Candelas; Posé, Sara; Morris, Victor J.; Kirby, Andrew R.; Quesada, Miguel A.; Mercado, José A.

2014-01-01

Background One of the main factors that reduce fruit quality and lead to economically important losses is oversoftening. Textural changes during fruit ripening are mainly due to the dissolution of the middle lamella, the reduction of cell-to-cell adhesion and the weakening of parenchyma cell walls as a result of the action of cell wall modifying enzymes. Pectins, major components of fruit cell walls, are extensively modified during ripening. These changes include solubilization, depolymerization and the loss of neutral side chains. Recent evidence in strawberry and apple, fruits with a soft or crisp texture at ripening, suggests that pectin disassembly is a key factor in textural changes. In both these fruits, softening was reduced as result of antisense downregulation of polygalacturonase genes. Changes in pectic polymer size, composition and structure have traditionally been studied by conventional techniques, most of them relying on bulk analysis of a population of polysaccharides, and studies focusing on modifications at the nanostructural level are scarce. Atomic force microscopy (AFM) allows the study of individual polymers at high magnification and with minimal sample preparation; however, AFM has rarely been employed to analyse pectin disassembly during fruit ripening. Scope In this review, the main features of the pectin disassembly process during fruit ripening are first discussed, and then the nanostructural characterization of fruit pectins by AFM and its relationship with texture and postharvest fruit shelf life is reviewed. In general, fruit pectins are visualized under AFM as linear chains, a few of which show long branches, and aggregates. Number- and weight-average values obtained from these images are in good agreement with chromatographic analyses. Most AFM studies indicate reductions in the length of individual pectin chains and the frequency of aggregates as the fruits ripen. Pectins extracted with sodium carbonate, supposedly located within the primary cell wall, are the most affected. PMID:25063934

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

PubMed

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.

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

PubMed

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.

Unexpected features of exponentially growing Tobacco Bright Yellow-2 cell suspension culture in relation to excreted extracellular polysaccharides and cell wall composition.

PubMed

Issawi, Mohammad; Muhieddine, Mohammad; Girard, Celine; Sol, Vincent; Riou, Catherine

2017-10-01

This article presents a new insight about TBY-2 cells; from extracellular polysaccharides secretion to cell wall composition during cell suspension culture. In the medium of cells taken 2 days after dilution (end of lag phase), a two unit pH decrease from 5.38 to 3.45 was observed and linked to a high uronic acid (UA) amount secretion (47.8%) while, in 4 and 7 day-old spent media, pH increased and UA amounts decreased 35.6 and 42.3% UA, respectively. To attain deeper knowledge of the putative link between extracellular polysaccharide excretion and cell wall composition, we determined cell wall UA and neutral sugar composition of cells from D2 to D12 cultures. While cell walls from D2 and D3 cells contained a large amount of uronic acid (twice as much as the other analysed cell walls), similar amounts of neutral sugar were detected in cells from lag to end of exponential phase cells suggesting an enriched pectin network in young cultures. Indeed, monosaccharide composition analysis leads to an estimated percentage of pectins of 56% for D3 cell wall against 45% D7 cell walls indicating that the cells at the mid-exponential growth phase re-organized their cell wall linked to a decrease in secreted UA that finally led to a stabilization of the spent medium pH to 5.4. In conclusion, TBY-2 cell suspension from lag to stationary phase showed cell wall remodeling that could be of interest in drug interaction and internalization study.

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

NASA Astrophysics Data System (ADS)

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, alkaline hydrogen peroxide and liquid hot water pretreatments were shown to alter structural properties impacting nanoscale porosity in corn stover. Delignification by alkaline hydrogen peroxide pretreatment decreased cell wall rigidity, with subsequent cell wall swelling resulting in increased nanoscale porosity and improved enzymatic hydrolysis compared to limited swelling and increased accessible surface areas observed in liquid hot water pretreated biomass. The volume accessible to a 90 A dextran probe within the cell wall was found to be positively correlated to both enzyme binding and glucose hydrolysis yields, indicating cell wall porosity is a key contributor to effective hydrolysis yields. In the third study, the effect of altered xylan content and structure was investigated in irregular xylem (irx) Arabidopsis thaliana mutants to understand the role xylan plays in secondary cell wall development and organization. Higher xylan extractability and lower cellulose crystallinity observed in irx9 and irx15 irx15-L mutants compared to wild type indicated altered xylan integration into the secondary cell wall. Nanoscale cell wall organization observed using multiple microscopy techniques was impacted to some extent in all irx mutants, with disorganized cellulose microfibril layers in sclerenchyma secondary cell walls likely resulting from irregular xylan structure and content. Irregular secondary cell wall microfibril layers showed heterogeneous nanomechanical properties compared to wild type, which translated to mechanical deficiencies observed in stem tensile tests. These results suggest nanoscale defects in cell wall strength can correspond to macroscale phenotypes.

Synthesis and Self-Assembly of Cellulose Microfibrils from Reconstituted Cellulose Synthase.

PubMed

Cho, Sung Hyun; Purushotham, Pallinti; Fang, Chao; Maranas, Cassandra; Díaz-Moreno, Sara M; Bulone, Vincent; Zimmer, Jochen; Kumar, Manish; Nixon, B Tracy

2017-09-01

Cellulose, the major component of plant cell walls, can be converted to bioethanol and is thus highly studied. In plants, cellulose is produced by cellulose synthase, a processive family-2 glycosyltransferase. In plant cell walls, individual β-1,4-glucan chains polymerized by CesA are assembled into microfibrils that are frequently bundled into macrofibrils. An in vitro system in which cellulose is synthesized and assembled into fibrils would facilitate detailed study of this process. Here, we report the heterologous expression and partial purification of His-tagged CesA5 from Physcomitrella patens Immunoblot analysis and mass spectrometry confirmed enrichment of PpCesA5. The recombinant protein was functional when reconstituted into liposomes made from yeast total lipid extract. The functional studies included incorporation of radiolabeled Glc, linkage analysis, and imaging of cellulose microfibril formation using transmission electron microscopy. Several microfibrils were observed either inside or on the outer surface of proteoliposomes, and strikingly, several thinner fibrils formed ordered bundles that either covered the surfaces of proteoliposomes or were spawned from liposome surfaces. We also report this arrangement of fibrils made by proteoliposomes bearing CesA8 from hybrid aspen. These observations describe minimal systems of membrane-reconstituted CesAs that polymerize β-1,4-glucan chains that coalesce to form microfibrils and higher-ordered macrofibrils. How these micro- and macrofibrils relate to those found in primary and secondary plant cell walls is uncertain, but their presence enables further study of the mechanisms that govern the formation and assembly of fibrillar cellulosic structures and cell wall composites during or after the polymerization process controlled by CesA proteins. © 2017 American Society of Plant Biologists. All Rights Reserved.

Synthesis and Self-Assembly of Cellulose Microfibrils from Reconstituted Cellulose Synthase1[OPEN

PubMed Central

Purushotham, Pallinti; Fang, Chao; Maranas, Cassandra; Bulone, Vincent

2017-01-01

Cellulose, the major component of plant cell walls, can be converted to bioethanol and is thus highly studied. In plants, cellulose is produced by cellulose synthase, a processive family-2 glycosyltransferase. In plant cell walls, individual β-1,4-glucan chains polymerized by CesA are assembled into microfibrils that are frequently bundled into macrofibrils. An in vitro system in which cellulose is synthesized and assembled into fibrils would facilitate detailed study of this process. Here, we report the heterologous expression and partial purification of His-tagged CesA5 from Physcomitrella patens. Immunoblot analysis and mass spectrometry confirmed enrichment of PpCesA5. The recombinant protein was functional when reconstituted into liposomes made from yeast total lipid extract. The functional studies included incorporation of radiolabeled Glc, linkage analysis, and imaging of cellulose microfibril formation using transmission electron microscopy. Several microfibrils were observed either inside or on the outer surface of proteoliposomes, and strikingly, several thinner fibrils formed ordered bundles that either covered the surfaces of proteoliposomes or were spawned from liposome surfaces. We also report this arrangement of fibrils made by proteoliposomes bearing CesA8 from hybrid aspen. These observations describe minimal systems of membrane-reconstituted CesAs that polymerize β-1,4-glucan chains that coalesce to form microfibrils and higher-ordered macrofibrils. How these micro- and macrofibrils relate to those found in primary and secondary plant cell walls is uncertain, but their presence enables further study of the mechanisms that govern the formation and assembly of fibrillar cellulosic structures and cell wall composites during or after the polymerization process controlled by CesA proteins. PMID:28768815

Identification and suppression of the p-coumaroyl CoA:hydroxycinnamyl alcohol transferase in Zea mays L.

PubMed Central

Marita, Jane M; Hatfield, Ronald D; Rancour, David M; Frost, Kenneth E

2014-01-01

Grasses, such as Zea mays L. (maize), contain relatively high levels of p-coumarates (pCA) within their cell walls. Incorporation of pCA into cell walls is believed to be due to a hydroxycinnamyl transferase that couples pCA to monolignols. To understand the role of pCA in maize development, the p-coumaroyl CoA:hydroxycinnamyl alcohol transferase (pCAT) was isolated and purified from maize stems. Purified pCAT was subjected to partial trypsin digestion, and peptides were sequenced by tandem mass spectrometry. TBLASTN analysis of the acquired peptide sequences identified a single full-length maize cDNA clone encoding all the peptide sequences obtained from the purified enzyme. The cDNA clone was obtained and used to generate an RNAi construct for suppressing pCAT expression in maize. Here we describe the effects of suppression of pCAT in maize. Primary screening of transgenic maize seedling leaves using a new rapid analytical platform was used to identify plants with decreased amounts of pCA. Using this screening method, mature leaves from fully developed plants were analyzed, confirming reduced pCA levels throughout plant development. Complete analysis of isolated cell walls from mature transgenic stems and leaves revealed that lignin levels did not change, but pCA levels decreased and the lignin composition was altered. Transgenic plants with the lowest levels of pCA had decreased levels of syringyl units in the lignin. Thus, altering the levels of pCAT expression in maize leads to altered lignin composition, but does not appear to alter the total amount of lignin present in the cell walls. PMID:24654730

Identification and suppression of the p-coumaroyl CoA:hydroxycinnamyl alcohol transferase in Zea mays L.

PubMed

Marita, Jane M; Hatfield, Ronald D; Rancour, David M; Frost, Kenneth E

2014-06-01

Grasses, such as Zea mays L. (maize), contain relatively high levels of p-coumarates (pCA) within their cell walls. Incorporation of pCA into cell walls is believed to be due to a hydroxycinnamyl transferase that couples pCA to monolignols. To understand the role of pCA in maize development, the p-coumaroyl CoA:hydroxycinnamyl alcohol transferase (pCAT) was isolated and purified from maize stems. Purified pCAT was subjected to partial trypsin digestion, and peptides were sequenced by tandem mass spectrometry. TBLASTN analysis of the acquired peptide sequences identified a single full-length maize cDNA clone encoding all the peptide sequences obtained from the purified enzyme. The cDNA clone was obtained and used to generate an RNAi construct for suppressing pCAT expression in maize. Here we describe the effects of suppression of pCAT in maize. Primary screening of transgenic maize seedling leaves using a new rapid analytical platform was used to identify plants with decreased amounts of pCA. Using this screening method, mature leaves from fully developed plants were analyzed, confirming reduced pCA levels throughout plant development. Complete analysis of isolated cell walls from mature transgenic stems and leaves revealed that lignin levels did not change, but pCA levels decreased and the lignin composition was altered. Transgenic plants with the lowest levels of pCA had decreased levels of syringyl units in the lignin. Thus, altering the levels of pCAT expression in maize leads to altered lignin composition, but does not appear to alter the total amount of lignin present in the cell walls. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

Combined enzymatic and metabolic analysis of grapevine cell responses to elicitors.

PubMed

Krzyzaniak, Yuko; Negrel, Jonathan; Lemaitre-Guillier, Christelle; Clément, Gilles; Mouille, Grégory; Klinguer, Agnès; Trouvelot, Sophie; Héloir, Marie-Claire; Adrian, Marielle

2018-02-01

Elicitors trigger plant defense responses, including phytoalexin production and cell-wall reinforcement. Primary metabolism plays an important role in these responses as it fuels the associated energetic costs and provides precursors for the synthesis of the numerous secondary metabolites involved in defenses against pathogens. In this context, we aimed to determine whether oligosaccharidic elicitors differing in their capacity to activate defense-associated secondary metabolism in grapevine would differently impact primary metabolism. To answer this question, cell suspensions were treated with two elicitors: an oligogalacturonide, and the β-glucan laminarin. Enzymatic activity assays together with targeted (HPLC) and global (GC-MS) analyses of metabolites were next performed to compare their impact on plant primary or secondary metabolism. The results showed that the oligogalacturonide, which induced the highest level of the phytoalexin resveratrol and the highest activity of stilbene synthase, also induced the highest activity of shikimate hydroxycinnamoyltransferase, a key enzyme involved in the synthesis of lignin. The oligogalacturonide-induced defenses had a significant impact on primary metabolism 24 h following elicitor treatment, with a reduced abundance of pyruvate and 2-oxoglutarate, together with an increase of a set of metabolites including carbohydrates and amino acids. Interestingly, an accumulation of galacturonate and gentiobiose was observed in the oligogalacturonide- and laminarin-treated cells, respectively, suggesting that both elicitors are rapidly hydrolyzed in grapevine cell suspension cultures. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pattathil, Sivakumar; Ingwers, Miles W.; Victoriano, Olivia L.

The composition, integrity, and architecture of the macromolecular matrix of cell walls, collectively referred to as cell wall ultrastructure, exhibits variation across species and organs and among cell types within organs. Indirect approaches have suggested that modifications to cell wall ultrastructure occur in response to abiotic stress; however, modifications have not been directly observed. Glycome profiling was used to study cell wall ultrastructure by examining variation in composition and extractability of non-cellulosic glycans in cell walls of stem wood, roots, and needles of loblolly pine saplings exposed to high and low soil moisture. Soil moisture influenced physiological processes and themore » overall composition and extractability of cell wall components differed as a function of soil moisture treatments. The strongest response of cell wall ultrastructure to soil moisture was increased extractability of pectic backbone epitopes in the low soil moisture treatment. The higher abundance of these pectic backbone epitopes in the oxalate extract indicate that the loosening of cell wall pectic components could be associated with the release of pectic signals as a stress response. The increased extractability of pectic backbone epitopes in response to low soil moisture availability was more pronounced in stem wood than in roots or needles. Additional responses to low soil moisture availability were observed in lignin associated carbohydrates released in chlorite extracts of stem wood, including an increased abundance of pectic arabinogalactan epitopes. Overall, these results indicate that cell walls of loblolly pine organs undergo changes in their ultrastructural composition and extractability as a response to soil moisture availability and that cell walls of the stem wood are more responsive to low soil moisture availability compared to cell walls of roots and needles. In conclusion, to our knowledge, this is the first direct evidence, delineated by glycomic analyses, that abiotic stress affects cell wall ultrastructure. This study is also unique in that glycome profiling of pine needles has never before been reported.« less

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

PubMed

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

2016-01-01

The composition, integrity, and architecture of the macromolecular matrix of cell walls, collectively referred to as cell wall ultrastructure, exhibits variation across species and organs and among cell types within organs. Indirect approaches have suggested that modifications to cell wall ultrastructure occur in response to abiotic stress; however, modifications have not been directly observed. Glycome profiling was used to study cell wall ultrastructure by examining variation in composition and extractability of non-cellulosic glycans in cell walls of stem wood, roots, and needles of loblolly pine saplings exposed to high and low soil moisture. Soil moisture influenced physiological processes and the overall composition and extractability of cell wall components differed as a function of soil moisture treatments. The strongest response of cell wall ultrastructure to soil moisture was increased extractability of pectic backbone epitopes in the low soil moisture treatment. The higher abundance of these pectic backbone epitopes in the oxalate extract indicate that the loosening of cell wall pectic components could be associated with the release of pectic signals as a stress response. The increased extractability of pectic backbone epitopes in response to low soil moisture availability was more pronounced in stem wood than in roots or needles. Additional responses to low soil moisture availability were observed in lignin-associated carbohydrates released in chlorite extracts of stem wood, including an increased abundance of pectic arabinogalactan epitopes. Overall, these results indicate that cell walls of loblolly pine organs undergo changes in their ultrastructural composition and extractability as a response to soil moisture availability and that cell walls of the stem wood are more responsive to low soil moisture availability compared to cell walls of roots and needles. To our knowledge, this is the first direct evidence, delineated by glycomic analyses, that abiotic stress affects cell wall ultrastructure. This study is also unique in that glycome profiling of pine needles has never before been reported.

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

DOE PAGES

Pattathil, Sivakumar; Ingwers, Miles W.; Victoriano, Olivia L.; ...

2016-06-24

The composition, integrity, and architecture of the macromolecular matrix of cell walls, collectively referred to as cell wall ultrastructure, exhibits variation across species and organs and among cell types within organs. Indirect approaches have suggested that modifications to cell wall ultrastructure occur in response to abiotic stress; however, modifications have not been directly observed. Glycome profiling was used to study cell wall ultrastructure by examining variation in composition and extractability of non-cellulosic glycans in cell walls of stem wood, roots, and needles of loblolly pine saplings exposed to high and low soil moisture. Soil moisture influenced physiological processes and themore » overall composition and extractability of cell wall components differed as a function of soil moisture treatments. The strongest response of cell wall ultrastructure to soil moisture was increased extractability of pectic backbone epitopes in the low soil moisture treatment. The higher abundance of these pectic backbone epitopes in the oxalate extract indicate that the loosening of cell wall pectic components could be associated with the release of pectic signals as a stress response. The increased extractability of pectic backbone epitopes in response to low soil moisture availability was more pronounced in stem wood than in roots or needles. Additional responses to low soil moisture availability were observed in lignin associated carbohydrates released in chlorite extracts of stem wood, including an increased abundance of pectic arabinogalactan epitopes. Overall, these results indicate that cell walls of loblolly pine organs undergo changes in their ultrastructural composition and extractability as a response to soil moisture availability and that cell walls of the stem wood are more responsive to low soil moisture availability compared to cell walls of roots and needles. In conclusion, to our knowledge, this is the first direct evidence, delineated by glycomic analyses, that abiotic stress affects cell wall ultrastructure. This study is also unique in that glycome profiling of pine needles has never before been reported.« less

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

PubMed

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

2015-09-01

Cut Iris flowers (Iris x hollandica, cv. Blue Magic) show visible senescence about two days after full opening. Epidermal cells of the outer tepals collapse due to programmed cell death (PCD). Transmission electron microscopy (TEM) showed irregular swelling of the cell walls, starting prior to cell collapse. Compared to cells in flowers that had just opened, wall thickness increased up to tenfold prior to cell death. Fibrils were visible in the swollen walls. After cell death very little of the cell wall remained. Prior to and during visible wall swelling, vesicles (paramural bodies) were observed between the plasma membrane and the cell walls. The vesicles were also found in groups and were accompanied by amorphous substance. They usually showed a single membrane, and had a variety of diameters and electron densities. Cut Dendrobium hybrid cv. Lucky Duan flowers exhibited visible senescence about 14 days after full flower opening. Paramural bodies were also found in Dendrobium tepal epidermis and mesophyll cells, related to wall swelling and degradation. Although alternative explanations are well possible, it is hypothesized that paramural bodies carry enzymes involved in cell wall breakdown. The literature has not yet reported such bodies in association with senescence/PCD. Copyright © 2015 Elsevier GmbH. All rights reserved.

Modelling cell wall growth using a fibre-reinforced hyperelastic-viscoplastic constitutive law

NASA Astrophysics Data System (ADS)

Huang, R.; Becker, A. A.; Jones, I. A.

2012-04-01

A fibre-reinforced hyperelastic-viscoplastic model using a finite strain Finite Element (FE) analysis is presented to study the expansive growth of cell walls. Based on the connections between biological concepts and plasticity theory, e.g. wall-loosening and plastic yield, wall-stiffening and plastic hardening, the modelling of cell wall growth is established within a framework of anisotropic viscoplasticity aiming to represent the corresponding biology-controlled behaviour of a cell wall. In order to model in vivo growth, special attention is paid to the differences between a living cell and an isolated wall. The proposed hyperelastic-viscoplastic theory provides a unique framework to clarify the interplay between cellulose microfibrils and cell wall matrix and how this interplay regulates sustainable growth in a particular direction while maintaining the mechanical strength of the cell walls by new material deposition. Moreover, the effect of temperature is taken into account. A numerical scheme is suggested and FE case studies are presented and compared with experimental data.

(Hydroxyproline-rich glycoproteins of the plant cell wall)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varner, J.E.

1990-01-01

We are studying the chemistry and architecture of plant cells walls, the extracellular matrices that taken together shape the plant and provide mechanical support for the plant. Cell walls are dynamic structures that regulate, or are the site of, many physiological processes, in addition to being the cells' first line of defense against invading pathogens. In the past year we have examined the role of the cell wall enzyme ascorbic acid oxidase as related to the structure of the wall and its possible interactions with hydroxyproline-rich glycoproteins of the wall.

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.

PubMed

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.

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

PubMed

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.

Tuberculosis of the Chest Wall with Massive Tuberculous Pleural Effusion.

PubMed

Monteiro, Mongressa V; Keny, Sanjivani J; Lawande, Durga J; Kakodkar, Uday C

2016-01-01

Primary tuberculosis of components of the chest wall is a rare entity. Involvement of skeletal muscle by tuberculosis without any primary focus is also rare. Here, we report a case of tuberculosis of chest wall without pulmonary or bone involvement, that invaded into the pleural space leading to a massive pleural effusion.

Do plant cell walls have a code?

PubMed

Tavares, Eveline Q P; Buckeridge, Marcos S

2015-12-01

A code is a set of rules that establish correspondence between two worlds, signs (consisting of encrypted information) and meaning (of the decrypted message). A third element, the adaptor, connects both worlds, assigning meaning to a code. We propose that a Glycomic Code exists in plant cell walls where signs are represented by monosaccharides and phenylpropanoids and meaning is cell wall architecture with its highly complex association of polymers. Cell wall biosynthetic mechanisms, structure, architecture and properties are addressed according to Code Biology perspective, focusing on how they oppose to cell wall deconstruction. Cell wall hydrolysis is mainly focused as a mechanism of decryption of the Glycomic Code. Evidence for encoded information in cell wall polymers fine structure is highlighted and the implications of the existence of the Glycomic Code are discussed. Aspects related to fine structure are responsible for polysaccharide packing and polymer-polymer interactions, affecting the final cell wall architecture. The question whether polymers assembly within a wall display similar properties as other biological macromolecules (i.e. proteins, DNA, histones) is addressed, i.e. do they display a code? Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

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

PubMed Central

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

2016-01-01

The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. PMID:26975195

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

PubMed

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.

Synchrotron Time-Lapse Imaging of Lignocellulosic Biomass Hydrolysis: Tracking Enzyme Localization by Protein Autofluorescence and Biochemical Modification of Cell Walls by Microfluidic Infrared Microspectroscopy

PubMed Central

Devaux, Marie-Françoise; Jamme, Frédéric; André, William; Bouchet, Brigitte; Alvarado, Camille; Durand, Sylvie; Robert, Paul; Saulnier, Luc; Bonnin, Estelle; Guillon, Fabienne

2018-01-01

Tracking enzyme localization and following the local biochemical modification of the substrate should help explain the recalcitrance of lignocellulosic plant cell walls to enzymatic degradation. Time-lapse studies using conventional imaging require enzyme labeling and following the biochemical modifications of biopolymers found in plant cell walls, which cannot be easily achieved. In the present work, synchrotron facilities have been used to image the enzymatic degradation of lignocellulosic biomass without labeling the enzyme or the cell walls. Multichannel autofluorescence imaging of the protein and phenolic compounds after excitation at 275 nm highlighted the presence or absence of enzymes on cell walls and made it possible to track them during the reaction. Image analysis was used to quantify the fluorescence intensity variations. Consistent variations in the enzyme concentration were found locally for cell cavities and their surrounding cell walls. Microfluidic FT-IR microspectroscopy allowed for time-lapse tracking of local changes in the polysaccharides in cell walls during degradation. Hemicellulose degradation was found to occur prior to cellulose degradation using a Celluclast® preparation. Combining the fluorescence and FT-IR information yielded the conclusion that enzymes did not bind to lignified cell walls, which were consequently not degraded. Fluorescence multiscale imaging and FT-IR microspectroscopy showed an unexpected variability both in the initial biochemical composition and the degradation pattern, highlighting micro-domains in the cell wall of a given cell. Fluorescence intensity quantification showed that the enzymes were not evenly distributed, and their amount increased progressively on degradable cell walls. During degradation, adjacent cells were separated and the cell wall fragmented until complete degradation. PMID:29515611

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

PubMed

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.

Cooperation between Paxillin-like Protein Pxl1 and Glucan Synthase Bgs1 Is Essential for Actomyosin Ring Stability and Septum Formation in Fission Yeast

PubMed Central

G. Cortés, Juan C.; Pujol, Nuria; Sato, Mamiko; Pinar, Mario; Ramos, Mariona; Moreno, Belén; Osumi, Masako; Ribas, Juan Carlos; Pérez, Pilar

2015-01-01

In fungal cells cytokinesis requires coordinated closure of a contractile actomyosin ring (CAR) and synthesis of a special cell wall structure known as the division septum. Many CAR proteins have been identified and characterized, but how these molecules interact with the septum synthesis enzymes to form the septum remains unclear. Our genetic study using fission yeast shows that cooperation between the paxillin homolog Pxl1, required for ring integrity, and Bgs1, the enzyme responsible for linear β(1,3)glucan synthesis and primary septum formation, is required for stable anchorage of the CAR to the plasma membrane before septation onset, and for cleavage furrow formation. Thus, lack of Pxl1 in combination with Bgs1 depletion, causes failure of ring contraction and lateral cell wall overgrowth towards the cell lumen without septum formation. We also describe here that Pxl1 concentration at the CAR increases during cytokinesis and that this increase depends on the SH3 domain of the F-BAR protein Cdc15. In consequence, Bgs1 depletion in cells carrying a cdc15ΔSH3 allele causes ring disassembly and septation blockage, as it does in cells lacking Pxl1. On the other hand, the absence of Pxl1 is lethal when Cdc15 function is affected, generating a large sliding of the CAR with deposition of septum wall material along the cell cortex, and suggesting additional functions for both Pxl1 and Cdc15 proteins. In conclusion, our findings indicate that CAR anchorage to the plasma membrane through Cdc15 and Pxl1, and concomitant Bgs1 activity, are necessary for CAR maintenance and septum formation in fission yeast. PMID:26132084

Cooperation between Paxillin-like Protein Pxl1 and Glucan Synthase Bgs1 Is Essential for Actomyosin Ring Stability and Septum Formation in Fission Yeast.

PubMed

Cortés, Juan C G; Pujol, Nuria; Sato, Mamiko; Pinar, Mario; Ramos, Mariona; Moreno, Belén; Osumi, Masako; Ribas, Juan Carlos; Pérez, Pilar

2015-07-01

In fungal cells cytokinesis requires coordinated closure of a contractile actomyosin ring (CAR) and synthesis of a special cell wall structure known as the division septum. Many CAR proteins have been identified and characterized, but how these molecules interact with the septum synthesis enzymes to form the septum remains unclear. Our genetic study using fission yeast shows that cooperation between the paxillin homolog Pxl1, required for ring integrity, and Bgs1, the enzyme responsible for linear β(1,3)glucan synthesis and primary septum formation, is required for stable anchorage of the CAR to the plasma membrane before septation onset, and for cleavage furrow formation. Thus, lack of Pxl1 in combination with Bgs1 depletion, causes failure of ring contraction and lateral cell wall overgrowth towards the cell lumen without septum formation. We also describe here that Pxl1 concentration at the CAR increases during cytokinesis and that this increase depends on the SH3 domain of the F-BAR protein Cdc15. In consequence, Bgs1 depletion in cells carrying a cdc15ΔSH3 allele causes ring disassembly and septation blockage, as it does in cells lacking Pxl1. On the other hand, the absence of Pxl1 is lethal when Cdc15 function is affected, generating a large sliding of the CAR with deposition of septum wall material along the cell cortex, and suggesting additional functions for both Pxl1 and Cdc15 proteins. In conclusion, our findings indicate that CAR anchorage to the plasma membrane through Cdc15 and Pxl1, and concomitant Bgs1 activity, are necessary for CAR maintenance and septum formation in fission yeast.

A unified wall function for compressible turbulence modelling

NASA Astrophysics Data System (ADS)

Ong, K. C.; Chan, A.

2018-05-01

Turbulence modelling near the wall often requires a high mesh density clustered around the wall and the first cells adjacent to the wall to be placed in the viscous sublayer. As a result, the numerical stability is constrained by the smallest cell size and hence requires high computational overhead. In the present study, a unified wall function is developed which is valid for viscous sublayer, buffer sublayer and inertial sublayer, as well as including effects of compressibility, heat transfer and pressure gradient. The resulting wall function applies to compressible turbulence modelling for both isothermal and adiabatic wall boundary conditions with the non-zero pressure gradient. Two simple wall function algorithms are implemented for practical computation of isothermal and adiabatic wall boundary conditions. The numerical results show that the wall function evaluates the wall shear stress and turbulent quantities of wall adjacent cells at wide range of non-dimensional wall distance and alleviate the number and size of cells required.

Growth and cell wall changes in stem organs under microgravity and hypergravity conditions

NASA Astrophysics Data System (ADS)

Hoson, Takayuki; Soga, Kouichi; Wakabayashi, Kazuyuki; Kamisaka, Seiichiro

Gravity strongly influences plant growth and development, which is fundamentally brought about by modifications to the properties of the cell wall. We have examined the changes in growth and cell wall properties in seedling organs under hypergravity conditions produced by centrifugation and under microgravity conditions in space. Hypergravity stimuli have been shown to decrease the growth rate of various seedling organs. When hypergravity suppressed elongation growth, a decrease in cell wall extensibility (an increase in cell wall rigidity) was induced. Hypergravity has also been shown to increase cell wall thickness in various mate-rials. In addition, a polymerization of certain matrix polysaccharides was brought about by hypergravity: in dicotyledons hypergravity increased the molecular size of xyloglucans, whereas hypergravity increased that of 1,3,1,4-β-glucans in monocotyledonous Gramineae. These mod-ifications to cell wall metabolism may be responsible for a decrease in cell wall extensibility, leading to growth suppression under hypergravity conditions. How then does microgravity in-fluence growth and cell wall properties? Here, there was a possibility that microgravity might induce changes similar to those by hypergravity, because plants have evolved and adapted to 1 g condition for more than 400 million years. However, the changes observed under microgravity conditions in space were just opposite to those induced by hypergravity: stimulation of elonga-tion growth, an increase in cell wall extensibility, and a decrease in cell wall thickness as well as depolymerization of cell wall polysaccharides were brought about in space. Furthermore, growth and cell wall properties varied in proportion to the logarithm of the magnitude of grav-ity in the range from microgravity to hypergravity, as shown in the dose-response relation in light and hormonal responses. Thus, microgravity may be a `stress-less' environment for plant seedlings to grow and develop. Preliminary results obtained by recent Space Seed experiment in the Kibo Module on the International Space Station (PI: S. Kamisaka) suggest that this hypothesis is also applicable to mature Arabidopsis plants.

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

PubMed

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

2015-09-23

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

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

PubMed

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.

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

PubMed

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.

Antimicrobial Properties of 2D MnO2 and MoS2 Nanomaterials Vertically Aligned on Graphene Materials and Ti3C2 MXene.

PubMed

Alimohammadi, Farbod; Sharifian Gh, Mohammad; Attanayake, Nuwan H; Thenuwara, Akila C; Gogotsi, Yury; Anasori, Babak; Strongin, Daniel R

2018-06-07

Two-dimensional (2D) nanomaterials have attracted considerable attention in biomedical and environmental applications due to their antimicrobial activity. In the interest of investigating the primary antimicrobial mode-of-action of 2D nanomaterials, we studied the antimicrobial properties of MnO 2 and MoS 2 , toward Gram-positive and Gram-negative bacteria. Bacillus subtilis and Escherichia coli bacteria were treated individually with 100 μg/mL of randomly oriented and vertically aligned nanomaterials for ∼3 h in the dark. The vertically aligned 2D MnO 2 and MoS 2 were grown on 2D sheets of graphene oxide, reduced graphene oxide, and Ti 3 C 2 MXene. Measurements to determine the viability of bacteria in the presence of the 2D nanomaterials performed by using two complementary techniques, flow cytometry, and fluorescence imaging showed that, while MnO 2 and MoS 2 nanosheets show different antibacterial activities, in both cases, Gram-positive bacteria show a higher loss in membrane integrity. Scanning electron microscopy images suggest that the 2D nanomaterials, which have a detrimental effect on bacteria viability, compromise the cell wall, leading to significant morphological changes. We propose that the peptidoglycan mesh (PM) in the bacterial wall is likely the primary target of the 2D nanomaterials. Vertically aligned 2D MnO 2 nanosheets showed the highest antimicrobial activity, suggesting that the edges of the nanosheets were likely compromising the cell walls upon contact.

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

PubMed

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.

Cell wall of pathogenic yeasts and implications for antimycotic therapy.

PubMed

Cassone, A

1986-01-01

Yeast cell wall is a complex, multilayered structure where amorphous, granular and fibrillar components interact with each other to confer both the specific cell shape and osmotic protection against lysis. Thus it is widely recognized that as is the case with bacteria, yeast cell wall is a major potential target for selective chemotherapeutic drugs. Despite intensive research, very few such drugs have been discovered and none has found substantial application in human diseases to date. Among the different cell wall components, beta-glucan and chitin are the fibrillar materials playing a fundamental role in the overall rigidity and resistance of the wall. Inhibition of the metabolism of these polymers, therefore, should promptly lead to lysis. This indeed occurs and aculeacin, echinocandin and polyoxins are examples of agents producing such an action. Particular attention should be focused on chitin synthesis. Although quantitatively a minor cell wall component, chitin is important in the mechanism of dimorphic transition, especially in Candida albicans, a major human opportunistic pathogen. This transition is associated with increased invasiveness and general virulence of the fungus. Yeast cell wall may also limit the effect of antifungals which owe their action to disturbance of the cytoplasmic membrane or of cell metabolism. Indeed, the cell wall may hinder access to the cell interior both under growing conditions and, particularly, during cell ageing in the stationary phase, when important structural changes occur in the cell wall due to unbalanced wall growth (phenotypic drug resistance).

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cosgrove, Daniel J.

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 potentialmore » 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.« less

My body is a cage: mechanisms and modulation of plant cell growth.

PubMed

Braidwood, Luke; Breuer, Christian; Sugimoto, Keiko

2014-01-01

388 I. 388 II. 389 III. 389 IV. 390 V. 391 VI. 393 VII. 394 VIII. 398 399 References 399 SUMMARY: The wall surrounding plant cells provides protection from abiotic and biotic stresses, and support through the action of turgor pressure. However, the presence of this strong elastic wall also prevents cell movement and resists cell growth. This growth can be likened to extending a house from the inside, using extremely high pressures to push out the walls. Plants must increase cell volume in order to explore their environment, acquire nutrients and reproduce. Cell wall material must stretch and flow in a controlled manner and, concomitantly, new cell wall material must be deposited at the correct rate and site to prevent wall and cell rupture. In this review, we examine biomechanics, cell wall structure and growth regulatory networks to provide a 'big picture' of plant cell growth. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

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

PubMed Central

Liu, Zengyu; Persson, Staffan; Zhang, Yi

2015-01-01

The cell wall provides external support of the plant cells, while the cytoskeletons including the microtubules and the actin filaments constitute an internal framework. The cytoskeletons contribute to the cell wall biosynthesis by spatially and temporarily regulating the transportation and deposition of cell wall components. This tight control is achieved by the dynamic behavior of the cytoskeletons, but also through the tethering of these structures to the plasma membrane. This tethering may also extend beyond the plasma membrane and impact on the cell wall, possibly in the form of a feedback loop. In this review, we discuss the linking components between the cytoskeletons and the plasma membrane, and/or the cell wall. We also discuss the prospective roles of these components in cell wall biosynthesis and modifications, and aim to provide a platform for further studies in this field. PMID:25693826

HtrA3 Is Downregulated in Cancer Cell Lines and Significantly Reduced in Primary Serous and Granulosa Cell Ovarian Tumors.

PubMed

Singh, Harmeet; Li, Ying; Fuller, Peter J; Harrison, Craig; Rao, Jyothsna; Stephens, Andrew N; Nie, Guiying

2013-01-01

Objective. The high temperature requirement factor A3 (HtrA3) is a serine protease homologous to bacterial HtrA. Four human HtrAs have been identified. HtrA1 and HtrA3 share a high degree of domain organization and are downregulated in a number of cancers, suggesting a widespread loss of these proteases in cancer. This study examined how extensively the HtrA (HtrA1-3) proteins are downregulated in commonly used cancer cell lines and primary ovarian tumors.Methods. RT-PCR was applied to various cancer cell lines (n=17) derived from the ovary, endometrium, testes, breast, prostate, and colon, and different subtypes of primary ovarian tumors [granulosa cell tumors (n=19), mucinous cystadenocarcinomas (n=6), serous cystadenocarcinomas (n=8)] and normal ovary (n = 9). HtrA3 protein was localized by immunohistochemistry.Results. HtrA3 was extensively downregulated in the cancer cell lines examined including the granulosa cell tumor-derived cell lines. In primary ovarian tumors, the HtrA3 was significantly lower in serous cystadenocarcinoma and granulosa cell tumors. In contrast, HtrA1 and HtrA2 were expressed in all samples with no significant differences between the control and tumors. In normal postmenopausal ovary, HtrA3 protein was localized to lutenizing stromal cells and corpus albicans. In serous cystadenocarcinoma, HtrA3 protein was absent in the papillae but detected in the mesenchymal cyst wall.Conclusion. HtrA3 is more extensively downregulated than HtrA1-2 in cancer cell lines. HtrA3, but not HtrA1 or HtrA2, was decreased in primary ovarian serous cystadenocarcinoma and granulosa cell tumors. This study provides evidence that HtrA3 may be the most relevant HtrA associated with ovarian malignancy.

Nuclear reactor having a polyhedral primary shield and removable vessel insulation

DOEpatents

Ekeroth, Douglas E.; Orr, Richard

1993-01-01

A nuclear reactor is provided having a generally cylindrical reactor vessel disposed within an opening in a primary shield. The opening in the primary shield is defined by a plurality of generally planar side walls forming a generally polyhedral-shaped opening. The reactor vessel is supported within the opening in the primary shield by reactor vessel supports which are in communication and aligned with central portions of some of the side walls. The reactor vessel is connected to the central portions of the reactor vessel supports. A thermal insulation polyhedron formed from a plurality of slidably insertable and removable generally planar insulation panels substantially surrounds at least a portion of the reactor vessel and is disposed between the reactor vessel and the side walls of the primary shield. The shape of the insulation polyhedron generally corresponds to the shape of the opening in the primary shield. Reactor monitoring instrumentation may be mounted in the corners of the opening in the primary shield between the side walls and the reactor vessel such that insulation is not disposed between the instrumentation and the reactor vessel.

Nuclear reactor having a polyhedral primary shield and removable vessel insulation

DOEpatents

Ekeroth, D.E.; Orr, R.

1993-12-07

A nuclear reactor is provided having a generally cylindrical reactor vessel disposed within an opening in a primary shield. The opening in the primary shield is defined by a plurality of generally planar side walls forming a generally polyhedral-shaped opening. The reactor vessel is supported within the opening in the primary shield by reactor vessel supports which are in communication and aligned with central portions of some of the side walls. The reactor vessel is connected to the central portions of the reactor vessel supports. A thermal insulation polyhedron formed from a plurality of slidably insertable and removable generally planar insulation panels substantially surrounds at least a portion of the reactor vessel and is disposed between the reactor vessel and the side walls of the primary shield. The shape of the insulation polyhedron generally corresponds to the shape of the opening in the primary shield. Reactor monitoring instrumentation may be mounted in the corners of the opening in the primary shield between the side walls and the reactor vessel such that insulation is not disposed between the instrumentation and the reactor vessel. 5 figures.

Identification of potential cell wall component that allows Taka-amylase A adsorption in submerged cultures of Aspergillus oryzae.

PubMed

Sato, Hiroki; Toyoshima, Yoshiyuki; Shintani, Takahiro; Gomi, Katsuya

2011-12-01

We observed that α-amylase (Taka-amylase A; TAA) activity in the culture broth disappeared in the later stage of submerged cultivation of Aspergillus oryzae. This disappearance was caused by adsorption of TAA onto the cell wall of A. oryzae and not due to protein degradation by extracellular proteolytic enzymes. To determine the cell wall component(s) that allows TAA adsorption efficiently, the cell wall was fractionated by stepwise alkali treatment and enzymatic digestion. Consequently, alkali-insoluble cell wall fractions exhibited high levels of TAA adsorption. In addition, this adsorption capacity was significantly enhanced by treatment of the alkali-insoluble fraction with β-glucanase, which resulted in the concomitant increase in the amount of chitin in the resulting fraction. In contrast, the adsorption capacity was diminished by treating the cell wall fraction with chitinase. These results suggest that the major component that allows TAA adsorption is chitin. However, both the mycelium and the cell wall demonstrated the inability to allow TAA adsorption in the early stage of cultivation, despite chitin content in the cell wall being identical in both early and late stages of cultivation. These results suggest the existence of unidentified factor(s) that could prevent the adsorption of TAA onto the cell wall. Such factor(s) is most likely removed or diminished from the cell wall following longer cultivation periods.

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

NASA Technical Reports Server (NTRS)

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

1998-01-01

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

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

PubMed Central

Romaniuk, Joseph A. H.; Cegelski, Lynette

2015-01-01

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

A Comparative Study of Sample Preparation for Staining and Immunodetection of Plant Cell Walls by Light Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verhertbruggen, Yves; Walker, Jesse L.; Guillon, Fabienne

Staining and immunodetection by light microscopy are methods widely used to investigate plant cell walls. The two techniques have been crucial to study the cell wall architecture in planta, its deconstruction by chemicals or cell wall-degrading enzymes. They have been instrumental in detecting the presence of cell types, in deciphering plant cell wall evolution and in characterizing plant mutants and transformants. The success of immunolabeling relies on how plant materials are embedded and sectioned. Agarose coating, wax and resin embedding are, respectively, associated with vibratome, microtome and ultramicrotome sectioning. Here, we have systematically carried out a comparative analysis of thesemore » three methods of sample preparation when they are applied for cell wall staining and cell wall immunomicroscopy. In order to help the plant community in understanding and selecting adequate methods of embedding and sectioning for cell wall immunodetection, we review in this article the advantages and limitations of these three methods. Moreover, we offer detailed protocols of embedding for studying plant materials through microscopy.« less

A Comparative Study of Sample Preparation for Staining and Immunodetection of Plant Cell Walls by Light Microscopy

DOE PAGES

Verhertbruggen, Yves; Walker, Jesse L.; Guillon, Fabienne; ...

2017-08-29

Staining and immunodetection by light microscopy are methods widely used to investigate plant cell walls. The two techniques have been crucial to study the cell wall architecture in planta, its deconstruction by chemicals or cell wall-degrading enzymes. They have been instrumental in detecting the presence of cell types, in deciphering plant cell wall evolution and in characterizing plant mutants and transformants. The success of immunolabeling relies on how plant materials are embedded and sectioned. Agarose coating, wax and resin embedding are, respectively, associated with vibratome, microtome and ultramicrotome sectioning. Here, we have systematically carried out a comparative analysis of thesemore » three methods of sample preparation when they are applied for cell wall staining and cell wall immunomicroscopy. In order to help the plant community in understanding and selecting adequate methods of embedding and sectioning for cell wall immunodetection, we review in this article the advantages and limitations of these three methods. Moreover, we offer detailed protocols of embedding for studying plant materials through microscopy.« less

A Comparative Study of Sample Preparation for Staining and Immunodetection of Plant Cell Walls by Light Microscopy

PubMed Central

Verhertbruggen, Yves; Walker, Jesse L.; Guillon, Fabienne; Scheller, Henrik V.

2017-01-01

Staining and immunodetection by light microscopy are methods widely used to investigate plant cell walls. The two techniques have been crucial to study the cell wall architecture in planta, its deconstruction by chemicals or cell wall-degrading enzymes. They have been instrumental in detecting the presence of cell types, in deciphering plant cell wall evolution and in characterizing plant mutants and transformants. The success of immunolabeling relies on how plant materials are embedded and sectioned. Agarose coating, wax and resin embedding are, respectively, associated with vibratome, microtome and ultramicrotome sectioning. Here, we have systematically carried out a comparative analysis of these three methods of sample preparation when they are applied for cell wall staining and cell wall immunomicroscopy. In order to help the plant community in understanding and selecting adequate methods of embedding and sectioning for cell wall immunodetection, we review in this article the advantages and limitations of these three methods. Moreover, we offer detailed protocols of embedding for studying plant materials through microscopy. PMID:28900439

Tissue and cell-specific transcriptomes in cotton reveal the subtleties of gene regulation underlying the diversity of plant secondary cell walls.

PubMed

MacMillan, Colleen P; Birke, Hannah; Chuah, Aaron; Brill, Elizabeth; Tsuji, Yukiko; Ralph, John; Dennis, Elizabeth S; Llewellyn, Danny; Pettolino, Filomena A

2017-07-18

Knowledge of plant secondary cell wall (SCW) regulation and deposition is mainly based on the Arabidopsis model of a 'typical' lignocellulosic SCW. However, SCWs in other plants can vary from this. The SCW of mature cotton seed fibres is highly cellulosic and lacks lignification whereas xylem SCWs are lignocellulosic. We used cotton as a model to study different SCWs and the expression of the genes involved in their formation via RNA deep sequencing and chemical analysis of stem and seed fibre. Transcriptome comparisons from cotton xylem and pith as well as from a developmental series of seed fibres revealed tissue-specific and developmentally regulated expression of several NAC transcription factors some of which are likely to be important as top tier regulators of SCW formation in xylem and/or seed fibre. A so far undescribed hierarchy was identified between the top tier NAC transcription factors SND1-like and NST1/2 in cotton. Key SCW MYB transcription factors, homologs of Arabidopsis MYB46/83, were practically absent in cotton stem xylem. Lack of expression of other lignin-specific MYBs in seed fibre relative to xylem could account for the lack of lignin deposition in seed fibre. Expression of a MYB103 homolog correlated with temporal expression of SCW CesAs and cellulose synthesis in seed fibres. FLAs were highly expressed and may be important structural components of seed fibre SCWs. Finally, we made the unexpected observation that cell walls in the pith of cotton stems contained lignin and had a higher S:G ratio than in xylem, despite that tissue's lacking many of the gene transcripts normally associated with lignin biosynthesis. Our study in cotton confirmed some features of the currently accepted gene regulatory cascade for 'typical' plant SCWs, but also revealed substantial differences, especially with key downstream NACs and MYBs. The lignocellulosic SCW of cotton xylem appears to be achieved differently from that in Arabidopsis. Pith cell walls in cotton stems are compositionally very different from that reported for other plant species, including Arabidopsis. The current definition of a 'typical' primary or secondary cell wall might not be applicable to all cell types in all plant species.

Comparative chemical characterization of pigmented and less pigmented cell walls of Alternaria tenuissima.

PubMed

Kishore, Kankipati Hara; Kanjilal, Sanjit; Misra, Sunil; Reddy, Chinnathimma Rajagopal; Murty, Upadyayula Suryanarayana

2005-12-01

Alternaria tenuissima, the parasitic fungus, was obtained from the pruned upper-cut surfaces of mulberry stems. This fungus contains dark pigment because of the presence of melanin in the cell wall. To obtain less-pigmented cell walls, this fungus was grown under dark condition. When the pigmented and less-pigmented cell walls were chemically analyzed, no differences were observed in amino-acid composition, hexoses, or pentoses. However, in pigmented cell walls, higher contents of melanin (2.6%) were found than in less-pigmented cell walls (0.3%). Interestingly, a significant difference was observed in the relative fatty-acid compositions between these two types of cell walls. Among the major fatty acids, there were increased concentrations of tetradecanoic acid (C14:0), hexadecanoic acid (C16:0), 9-hexadecenoic acid (C16: 1,Delta 9), and 9-octadecanoic acid (C18:1,Delta 9) and a concomitant decrease in 9,12-octadecadienoic acid (C18:2,Delta 9,12) in less-pigmented compared with pigmented cell walls. This difference in fatty-acid composition may be related to the higher percentage of melanin in the pigmented than the less-pigmented cell walls. Lesser amounts of 9,12-octadecadienoic acid in less-pigmented cell walls may have been caused by the growth of the fungus under environmental stress conditions. An interesting observation was the presence in pigmented cell walls only of methyl-substituted fatty acids with carbon numbers C14 to C17, but their occurrence could not be ascertained in the present study.

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

PubMed Central

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. PMID:26295574

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

PubMed

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.

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

PubMed

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.

Mating-Induced Shedding of Cell Walls, Removal of Walls from Vegetative Cells, and Osmotic Stress Induce Presumed Cell Wall Genes in Chlamydomonas1

PubMed Central

Hoffmann, Xenia-Katharina; Beck, Christoph F.

2005-01-01

The first step in sexual differentiation of the unicellular green alga Chlamydomonas reinhardtii is the formation of gametes. Three genes, GAS28, GAS30, and GAS31, encoding Hyp-rich glycoproteins that presumably are cell wall constituents, are expressed in the late phase of gametogenesis. These genes, in addition, are activated by zygote formation and cell wall removal and by the application of osmotic stress. The induction by zygote formation could be traced to cell wall shedding prior to gamete fusion since it was seen in mutants defective in cell fusion. However, it was absent in mutants defective in the initial steps of mating, i.e. in flagellar agglutination and in accumulation of adenosine 3′,5′-cyclic monophosphate in response to this agglutination. Induction of the three GAS genes was also observed when cultures were exposed to hypoosmotic or hyperosmotic stress. To address the question whether the induction seen upon cell wall removal from both gametes and vegetative cells was elicited by osmotic stress, cell wall removal was performed under isosmotic conditions. Also under such conditions an activation of the genes was observed, suggesting that the signaling pathway(s) is (are) activated by wall removal itself. PMID:16183845

Discovery of Novel Cell Wall-Active Compounds Using PywaC, a Sensitive Reporter of Cell Wall Stress, in the Model Gram-Positive Bacterium Bacillus subtilis

PubMed Central

Czarny, T. L.; Perri, A. L.; French, S.

2014-01-01

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. PMID:24687489

Modifying lignin to improve bioenergy feedstocks: strengthening the barrier against pathogens?

USDA-ARS?s Scientific Manuscript database

Lignin is a ubiquitous polymer present in cell walls of all vascular plants, where it rigidifies and strengthens the cell wall structure through covalent cross-linkages to cell wall polysaccharides. The presence of lignin makes the cell wall recalcitrant to conversion into fermentable sugars for bi...

Live-cell and super-resolution imaging reveal that the distribution of wall-associated protein A is correlated with the cell chain integrity of Streptococcus mutans.

PubMed

Li, Y; Liu, Z; Zhang, Y; Su, Q P; Xue, B; Shao, S; Zhu, Y; Xu, X; Wei, S; Sun, Y

2015-10-01

Streptococcus mutans is a primary pathogen responsible for dental caries. It has an outstanding ability to form biofilm, which is vital for virulence. Previous studies have shown that knockout of Wall-associated protein A (WapA) affects cell chain and biofilm formation of S. mutans. As a surface protein, the distribution of WapA remains unknown, but it is important to understand the mechanism underlying the function of WapA. This study applied the fluorescence protein mCherry as a reporter gene to characterize the dynamic distribution of WapA in S. mutans via time-lapse and super-resolution fluorescence imaging. The results revealed interesting subcellular distribution patterns of WapA in single, dividing and long chains of S. mutans cells. It appears at the middle of the cell and moves to the poles as the cell grows and divides. In a cell chain, after each round of cell division, such dynamic relocation results in WapA distribution at the previous cell division sites, resulting in a pattern where WapA is located at the boundary of two adjacent cell pairs. This WapA distribution pattern corresponds to the breaking segmentation of wapA deletion cell chains. The dynamic relocation of WapA through the cell cycle increases our understanding of the mechanism of WapA in maintaining cell chain integrity and biofilm formation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Brain size and limits to adult neurogenesis.

PubMed

Paredes, Mercedes F; Sorrells, Shawn F; Garcia-Verdugo, Jose M; Alvarez-Buylla, Arturo

2016-02-15

The walls of the cerebral ventricles in the developing embryo harbor the primary neural stem cells from which most neurons and glia derive. In many vertebrates, neurogenesis continues postnatally and into adulthood in this region. Adult neurogenesis at the ventricle has been most extensively studied in organisms with small brains, such as reptiles, birds, and rodents. In reptiles and birds, these progenitor cells give rise to young neurons that migrate into many regions of the forebrain. Neurogenesis in adult rodents is also relatively widespread along the lateral ventricles, but migration is largely restricted to the rostral migratory stream into the olfactory bulb. Recent work indicates that the wall of the lateral ventricle is highly regionalized, with progenitor cells giving rise to different types of neurons depending on their location. In species with larger brains, young neurons born in these spatially specified domains become dramatically separated from potential final destinations. Here we hypothesize that the increase in size and topographical complexity (e.g., intervening white matter tracts) in larger brains may severely limit the long-term contribution of new neurons born close to, or in, the ventricular wall. We compare the process of adult neuronal birth, migration, and integration across species with different brain sizes, and discuss how early regional specification of progenitor cells may interact with brain size and affect where and when new neurons are added. © 2015 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.

Lower cell wall pectin solubilisation and galactose loss during early fruit development in apple (Malus x domestica) cultivar 'Scifresh' are associated with slower softening rate.

PubMed

Ng, Jovyn K T; Schröder, Roswitha; Brummell, David A; Sutherland, Paul W; Hallett, Ian C; Smith, Bronwen G; Melton, Laurence D; Johnston, Jason W

2015-03-15

Substantial differences in softening behaviour can exist between fruit even within the same species. Apple cultivars 'Royal Gala' and 'Scifresh' soften at different rates despite having a similar genetic background and producing similar amounts of ethylene during ripening. An examination of cell wall metabolism from the fruitlet to the ripe stages showed that in both cultivars pectin solubilisation increased during cell expansion, declined at the mature stage and then increased again during ripening. This process was much less pronounced in the slower softening 'Scifresh' than in 'Royal Gala' at every developmental stage examined, consistent with less cell separation and softening in this cultivar. Both cultivars also exhibited a progressive loss of pectic galactan and arabinan side chains during development. The cell wall content of arabinose residues was similar in both cultivars, but the galactose residue content in 'Scifresh' remained higher than that of 'Royal Gala' at every developmental stage. The higher content of cell wall galactose residue in 'Scifresh' cell walls correlated with a lower β-galactosidase activity and more intense immunolabelling of RG-I galactan side chains in both microscopy sections and glycan microarrays. A high cell wall galactan content has been associated with reduced cell wall porosity, which may restrict access of cell wall-modifying enzymes and thus maintain better structural integrity later in development. The data suggest that the composition and structure of the cell wall at very early development stages may influence subsequent cell wall loosening, and may even predispose the wall's ensuing properties. Copyright © 2014 Elsevier GmbH. All rights reserved.

Cell wall integrity modulates RHO1 activity via the exchange factor ROM2.

PubMed Central

Bickle, M; Delley, P A; Schmidt, A; Hall, M N

1998-01-01

The essential phosphatidylinositol kinase homologue TOR2 of Saccharomyces cerevisiae controls the actin cytoskeleton by activating a GTPase switch consisting of RHO1 (GTPase), ROM2 (GEF) and SAC7 (GAP). We have identified two mutations, rot1-1 and rot2-1, that suppress the loss of TOR2 and are synthetic-lethal. The wild-type ROT1 and ROT2 genes and a multicopy suppressor, BIG1, were isolated by their ability to rescue the rot1-1 rot2-1 double mutant. ROT2 encodes glucosidase II, and ROT1 and BIG1 encode novel proteins. We present evidence that cell wall defects activate RHO1. First, rot1, rot2, big1, cwh41, gas1 and fks1 mutations all confer cell wall defects and suppress tor2(ts). Second, destabilizing the cell wall by supplementing the growth medium with 0.005% SDS also suppresses a tor2(ts) mutation. Third, disturbing the cell wall with SDS or a rot1, rot2, big1, cwh41, gas1 or fks1 mutation increases GDP/GTP exchange activity toward RHO1. These results suggest that cell wall defects suppress a tor2 mutation by activating RHO1 independently of TOR2, thereby inducing TOR2-independent polarization of the actin cytoskeleton and cell wall synthesis. Activation of RHO1, a subunit of the cell wall synthesis enzyme glucan synthase, by a cell wall alteration would ensure that cell wall synthesis occurs only when and where needed. The mechanism of RHO1 activation by a cell wall alteration is via the exchange factor ROM2 and could be analogous to signalling by integrin receptors in mammalian cells. PMID:9545237

DISTRIBUTION OF RADIOACTIVITY IN AUTOLYZED CELL WALL OF BACILLUS CEREUS DURING SPHEROPLAST FORMATION1

PubMed Central

Kronish, Donald P.; Mohan, Raam R.; Schwartz, Benjamin S.

1964-01-01

Kronish, Donald P. (Warner-Lambert Research Institute, Morris Plains, N.J.), Raam R. Mohan, and Benjamin S. Schwartz. Distribution of radioactivity in autolyzed cell wall of Bacillus cereus during spheroplast formation. J. Bacteriol. 87:581–587. 1964.—Spheroplasts of Bacillus cereus strain T were produced from cells grown in the presence of uniformly labeled C14-glucose. At regular intervals during spheroplast formation, enzymatically degraded cell wall was isolated by a new procedure. Radioactivity of solubilized cell wall in cell-free material increased from 2.5 to 42% of the total incorporated label during spheroplast formation. The rate of cell-wall degradation as measured by increase in radioactivity was biphasic with relative slopes of 2.0 and 5.0. During autolytic depolymerization of B. cereus cell wall, two major components were solubilized at different rates. Chemical fractionation revealed these to be a peptide and a mucopeptide. The possibility of two enzymes being involved in spheroplast formation and cell-wall degradation is discussed. Images PMID:14127573

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

PubMed Central

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

2015-01-01

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

Suppression of Hydroxycinnamate Network Formation in Cell Walls of Rice Shoots Grown under Microgravity Conditions in Space

PubMed Central

Wakabayashi, Kazuyuki; Soga, Kouichi; Hoson, Takayuki; Kotake, Toshihisa; Yamazaki, Takashi; Higashibata, Akira; Ishioka, Noriaki; Shimazu, Toru; Fukui, Keiji; Osada, Ikuko; Kasahara, Haruo; Kamada, Motoshi

2015-01-01

Network structures created by hydroxycinnamate cross-links within the cell wall architecture of gramineous plants make the cell wall resistant to the gravitational force of the earth. In this study, the effects of microgravity on the formation of cell wall-bound hydroxycinnamates were examined using etiolated rice shoots simultaneously grown under artificial 1 g and microgravity conditions in the Cell Biology Experiment Facility on the International Space Station. Measurement of the mechanical properties of cell walls showed that shoot cell walls became stiff during the growth period and that microgravity suppressed this stiffening. Amounts of cell wall polysaccharides, cell wall-bound phenolic acids, and lignin in rice shoots increased as the shoot grew. Microgravity did not influence changes in the amounts of cell wall polysaccharides or phenolic acid monomers such as ferulic acid (FA) and p-coumaric acid, but it suppressed increases in diferulic acid (DFA) isomers and lignin. Activities of the enzymes phenylalanine ammonia-lyase (PAL) and cell wall-bound peroxidase (CW-PRX) in shoots also increased as the shoot grew. PAL activity in microgravity-grown shoots was almost comparable to that in artificial 1 g-grown shoots, while CW-PRX activity increased less in microgravity-grown shoots than in artificial 1 g-grown shoots. Furthermore, the increases in expression levels of some class III peroxidase genes were reduced under microgravity conditions. These results suggest that a microgravity environment modifies the expression levels of certain class III peroxidase genes in rice shoots, that the resultant reduction of CW-PRX activity may be involved in suppressing DFA formation and lignin polymerization, and that this suppression may cause a decrease in cross-linkages within the cell wall architecture. The reduction in intra-network structures may contribute to keeping the cell wall loose under microgravity conditions. PMID:26378793

40 CFR 60.113a - Testing and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... every five years thereafter. All primary seal inspections or gap measurements which require the removal... the gap areas and maximum gap widths between the primary seal and the tank wall and between the secondary seal and the tank wall according to the following frequency: (A) For primary seals, gap...

40 CFR 60.113a - Testing and procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... every five years thereafter. All primary seal inspections or gap measurements which require the removal... the gap areas and maximum gap widths between the primary seal and the tank wall and between the secondary seal and the tank wall according to the following frequency: (A) For primary seals, gap...

Microanalysis of plant cell wall polysaccharides.

PubMed

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

2009-09-01

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

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

PubMed

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

2015-08-01

Host plant penetration is the gateway to survival for holoparasitic Cuscuta and requires host cell wall degradation. Compositional differences of cell walls may explain why some hosts are amenable to such degradation while others can resist infection. Antibody-based techniques for comprehensive profiling of cell wall epitopes and cell wall-modifying enzymes were applied to several susceptible hosts and a resistant host of Cuscuta reflexa and to the parasite itself. Infected tissue of Pelargonium zonale contained high concentrations of de-esterified homogalacturonans in the cell walls, particularly adjacent to the parasite's haustoria. High pectinolytic activity in haustorial extracts and high expression levels of pectate lyase genes suggest that the parasite contributes directly to wall remodeling. Mannan and xylan concentrations were low in P. zonale and in five susceptible tomato introgression lines, but high in the resistant Solanum lycopersicum cv M82, and in C. reflexa itself. Knowledge of the composition of resistant host cell walls and the parasite's own cell walls is useful in developing strategies to prevent infection by parasitic plants. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

The chaotrope-soluble glycoprotein GP1 is a constituent of the insoluble glycoprotein framework of the Chlamydomonas cell wall.

PubMed

Voigt, Jürgen; Frank, Ronald; Wöstemeyer, Johannes

2009-02-01

Chlamydomonas reinhardtii wild-type cells are surrounded by the insoluble cell wall component, a sac-like framework of cross-linked glycoproteins containing 22% hydroxyproline. The chaotrope-soluble cell wall glycoprotein GP1 is the only polypeptide with an even higher proportion of hydroxyproline (35%) occurring in vegetative C. reinhardtii cells. Mass spectrometric analyses of peptides released from the purified insoluble cell wall fraction by trypsin treatment and epitope analyses of polyclonal antibodies raised against different deglycosylation products of this particular wall fraction using 181 chemically synthesized GP1-derived pentadecapeptides revealed evidence that GP1 is indeed a constituent of the insoluble wall component.

Inhibition of intracellular bacterial replication in fibroblasts is dependent on the perforin-like protein (Perforin-2) encoded by macrophage expressed gene 1

PubMed Central

McCormack, Ryan; de Armas, Lesley R.; Shiratsuchi, Motoaki; Ramos, Jay; Podack, Eckhard R.

2013-01-01

Fibroblasts are known to eliminate intracellular bacteria, but the lethal hit of the bactericidal mechanism has not been defined. We show that primary embryonic and established fibroblasts can be induced by interferons or by intracellular bacterial infection to express a perforin-like mRNA previously described as macrophage expressed gene 1 (mpeg1). The presence and level of the perforin-like mRNA correlate with the ability of primary mouse embryonic fibroblasts (MEF) to eliminate intracellular bacteria. In addition, siRNA knock-down of the perforin-like molecule abolishes bactericidal activity and allows intracellular bacterial replication. Complementation of MEF in which the endogenous perforin-like molecule has been knocked down with an RFP-tagged version restores bactericidal activity. The perforin-like molecule has broad bactericidal specificity for pathogenic and non-pathogenic bacteria including Gram positive, Gram negative and acid fast bacteria. The perforin-like molecule renders previously lysozyme-resistant bacteria sensitive to lysis by lysozyme suggesting physical damage of the outer cell wall by the perforin-like protein. MEFs damage cell walls of intracellular bacteria by insertion, polymerization and pore-formation of the perforin-like protein, analogous to pore-formers of complement and Perforin-1 of cytolytic lymphocytes. We propose the name Perforin-2. PMID:23257510

Calcium deprivation disrupts enlargement of Chara corallina cells: further evidence for the calcium pectate cycle.

PubMed

Proseus, Timothy E; Boyer, John S

2012-06-01

Pectin is a normal constituent of cell walls of green plants. When supplied externally to live cells or walls isolated from the large-celled green alga Chara corallina, pectin removes calcium from load-bearing cross-links in the wall, loosening the structure and allowing it to deform more rapidly under the action of turgor pressure. New Ca(2+) enters the vacated positions in the wall and the externally supplied pectin binds to the wall, depositing new wall material that strengthens the wall. A calcium pectate cycle has been proposed for these sub-reactions. In the present work, the cycle was tested in C. corallina by depriving the wall of external Ca(2+) while allowing the cycle to run. The prediction is that growth would eventually be disrupted by a lack of adequate deposition of new wall. The test involved adding pectate or the calcium chelator EGTA to the Ca(2+)-containing culture medium to bind the calcium while the cycle ran in live cells. After growth accelerated, turgor and growth eventually decreased, followed by an abrupt turgor loss and growth cessation. The same experiment with isolated walls suggested the walls of live cells became unable to support the plasma membrane. If instead the pectate or EGTA was replaced with fresh Ca(2+)-containing culture medium during the initial acceleration in live cells, growth was not disrupted and returned to the original rates. The operation of the cycle was thus confirmed, providing further evidence that growth rates and wall biosynthesis are controlled by these sub-reactions in plant cell walls.

Branched Pectic Galactan in Phloem-Sieve-Element Cell Walls: Implications for Cell Mechanics.

PubMed

Torode, Thomas A; O'Neill, Rachel; Marcus, Susan E; Cornuault, Valérie; Pose, Sara; Lauder, Rebecca P; Kračun, Stjepan K; Rydahl, Maja Gro; Andersen, Mathias C F; Willats, William G T; Braybrook, Siobhan A; Townsend, Belinda J; Clausen, Mads H; Knox, J Paul

2018-02-01

A major question in plant biology concerns the specification and functional differentiation of cell types. This is in the context of constraints imposed by networks of cell walls that both adhere cells and contribute to the form and function of developing organs. Here, we report the identification of a glycan epitope that is specific to phloem sieve element cell walls in several systems. A monoclonal antibody, designated LM26, binds to the cell wall of phloem sieve elements in stems of Arabidopsis ( Arabidopsis thaliana ), Miscanthus x giganteus , and notably sugar beet ( Beta vulgaris ) roots where phloem identification is an important factor for the study of phloem unloading of Suc. Using microarrays of synthetic oligosaccharides, the LM26 epitope has been identified as a β-1,6-galactosyl substitution of β-1,4-galactan requiring more than three backbone residues for optimized recognition. This branched galactan structure has previously been identified in garlic ( Allium sativum ) 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 polysaccharides. In the phloem tissues of grass stems, the LM26 epitope has a complementary pattern to that of the LM5 linear β-1,4-galactan epitope, which is detected only in companion cell walls. Mechanical probing of transverse sections of M x giganteus stems and leaves by atomic force microscopy indicates that phloem sieve element cell walls have a lower indentation modulus (indicative of higher elasticity) than companion cell walls. © 2018 The author(s). All Rights Reserved.

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

PubMed

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.

Changes in levels of cell wall constituents in wheat seedlings grown under continuous hypergravity conditions

NASA Astrophysics Data System (ADS)

Wakabayashi, K.; Soga, K.; Kamisaka, S.; Hoson, T.

Effects of continuous hypergravity stimuli on the amounts and composition of cell wall constituents were investigated in wheat shoots. Hypergravity (300 g) treatment for three days after germination increased the net amount of cell wall polysaccharides such as hemicellulose and cellulose, but reduced the shoot elongation. As a result, the amount of cell wall polysaccharides per unit length of shoot increased under hypergravity. The hemicellulose fraction contained polysaccharides in the middle and low molecular mass range (5 kDa-1 MDa) and increased in response to hypergravity. Also, the amounts of arabinose (Ara) and xylose (Xyl), the major sugar components of the hemicellulose fraction, increased under hypergravity conditions. In addition to wall polysaccharides, hypergravity increased the amounts of cell wall-bound phenolic acids, such as ferulic acid (FA) and diferulic acid (DFA). Furthermore, the activity of phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) was enhanced under hypergravity conditions. These results suggest that continuous hypergravity stimulates the synthesis of cell wall constituents, especially hemicellulosic arabinoxylans and cell wall-bound FA and DFA in wheat shoots. The increased PAL activity may promote the formation of FA and DFA. These changes in cell wall architecture may be involved in making rigid and tough cell walls under hypergravity conditions and thereby contribute to the ability of plant to sustain their structures against gravitational stimuli.

Tools to Understand Structural Property Relationships for Wood Cell Walls

Treesearch

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

PubMed

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.

Building and degradation of secondary cell walls: are there common patterns of lamellar assembly of cellulose microfibrils and cell wall delamination?

PubMed

De Micco, Veronica; Ruel, Katia; Joseleau, Jean-Paul; Aronne, Giovanna

2010-08-01

During cell wall formation and degradation, it is possible to detect cellulose microfibrils assembled into thicker and thinner lamellar structures, respectively, following inverse parallel patterns. The aim of this study was to analyse such patterns of microfibril aggregation and cell wall delamination. The thickness of microfibrils and lamellae was measured on digital images of both growing and degrading cell walls viewed by means of transmission electron microscopy. To objectively detect, measure and classify microfibrils and lamellae into thickness classes, a method based on the application of computerized image analysis combined with graphical and statistical methods was developed. The method allowed common classes of microfibrils and lamellae in cell walls to be identified from different origins. During both the formation and degradation of cell walls, a preferential formation of structures with specific thickness was evidenced. The results obtained with the developed method allowed objective analysis of patterns of microfibril aggregation and evidenced a trend of doubling/halving lamellar structures, during cell wall formation/degradation in materials from different origin and which have undergone different treatments.

Ontogenetic characterization of sporangium and spore of Huperzia serrata: an anti-aging disease fern.

PubMed

Long, Hua; Li, Jing; Li, You-You; Xie, De-Yu; Peng, Qing-Zhong; Li, Li

2016-12-01

Huperzia serrata is a medicinal plant used in Traditional Chinese Medicine, which has been used to prevent against aging diseases. It is mainly propagated by spores and grows extremely slowly. Due to severe harvest, it is a highly endangered species. In this report, we characterize ontogenesis of sporangia and spores that are associated with propagation. A wild population of H. serrata plants is localized in western Hunan province, China and protected by Chinese Government to study its development (e.g. sporangia and spores) and ecology. Both field and microscopic observations were conducted for a few of years. The development of sporangia from their initiation to maturation took nearly 1 year. Microscopic observations showed that the sporangial walls were developed from epidermal cells via initiation, cell division, and maturation. The structure of the mature sporangial wall is composed of one layer of epidermis, two middle layers of cells, and one layer of tapetum. Therefore, the sporangium is the eusporangium type. Spore development is characterized into six stages, initiation from epidermal cell and formation of sporogenous cells, primary sporogenous cell, secondary sporogenous cell, spore mother cell, tetrad, and maturation. The sporangial development of H. serrata belongs to the eusporangium type. The development takes approximately 1 year period from the initiation to the maturation. These data are useful for improving propagation of this medicinal plant in the future.

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

PubMed

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.

The valine and lysine residues in the conserved FxVTxK motif are important for the function of phylogenetically distant plant cellulose synthases.

PubMed

Slabaugh, Erin; Scavuzzo-Duggan, Tess; Chaves, Arielle; Wilson, Liza; Wilson, Carmen; Davis, Jonathan K; Cosgrove, Daniel J; Anderson, Charles T; Roberts, Alison W; Haigler, Candace H

2016-05-01

Cellulose synthases (CESAs) synthesize the β-1,4-glucan chains that coalesce to form cellulose microfibrils in plant cell walls. In addition to a large cytosolic (catalytic) domain, CESAs have eight predicted transmembrane helices (TMHs). However, analogous to the structure of BcsA, a bacterial CESA, predicted TMH5 in CESA may instead be an interfacial helix. This would place the conserved FxVTxK motif in the plant cell cytosol where it could function as a substrate-gating loop as occurs in BcsA. To define the functional importance of the CESA region containing FxVTxK, we tested five parallel mutations in Arabidopsis thaliana CESA1 and Physcomitrella patens CESA5 in complementation assays of the relevant cesa mutants. In both organisms, the substitution of the valine or lysine residues in FxVTxK severely affected CESA function. In Arabidopsis roots, both changes were correlated with lower cellulose anisotropy, as revealed by Pontamine Fast Scarlet. Analysis of hypocotyl inner cell wall layers by atomic force microscopy showed that two altered versions of Atcesa1 could rescue cell wall phenotypes observed in the mutant background line. Overall, the data show that the FxVTxK motif is functionally important in two phylogenetically distant plant CESAs. The results show that Physcomitrella provides an efficient model for assessing the effects of engineered CESA mutations affecting primary cell wall synthesis and that diverse testing systems can lead to nuanced insights into CESA structure-function relationships. Although CESA membrane topology needs to be experimentally determined, the results support the possibility that the FxVTxK region functions similarly in CESA and BcsA. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Bacteria attenuation by iron electrocoagulation governed by interactions between bacterial phosphate groups and Fe(III) precipitates.

PubMed

Delaire, Caroline; van Genuchten, Case M; Amrose, Susan E; Gadgil, Ashok J

2016-10-15

Iron electrocoagulation (Fe-EC) is a low-cost process in which Fe(II) generated from an Fe(0) anode reacts with dissolved O2 to form (1) Fe(III) precipitates with an affinity for bacterial cell walls and (2) bactericidal reactive oxidants. Previous work suggests that Fe-EC is a promising treatment option for groundwater containing arsenic and bacterial contamination. However, the mechanisms of bacteria attenuation and the impact of major groundwater ions are not well understood. In this work, using the model indicator Escherichia coli (E. coli), we show that physical removal via enmeshment in EC precipitate flocs is the primary process of bacteria attenuation in the presence of HCO3(-), which significantly inhibits inactivation, possibly due to a reduction in the lifetime of reactive oxidants. We demonstrate that the adhesion of EC precipitates to cell walls, which results in bacteria encapsulation in flocs, is driven primarily by interactions between EC precipitates and phosphate functional groups on bacteria surfaces. In single solute electrolytes, both P (0.4 mM) and Ca/Mg (1-13 mM) inhibited the adhesion of EC precipitates to bacterial cell walls, whereas Si (0.4 mM) and ionic strength (2-200 mM) did not impact E. coli attenuation. Interestingly, P (0.4 mM) did not affect E. coli attenuation in electrolytes containing Ca/Mg, consistent with bivalent cation bridging between bacterial phosphate groups and inorganic P sorbed to EC precipitates. Finally, we found that EC precipitate adhesion is largely independent of cell wall composition, consistent with comparable densities of phosphate functional groups on Gram-positive and Gram-negative cells. Our results are critical to predict the performance of Fe-EC to eliminate bacterial contaminants from waters with diverse chemical compositions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Human primary myeloid dendritic cells interact with the opportunistic fungal pathogen Aspergillus fumigatus via the C-type lectin receptor Dectin-1.

PubMed

Hefter, Maike; Lother, Jasmin; Weiß, Esther; Schmitt, Anna Lena; Fliesser, Mirjam; Einsele, Hermann; Loeffler, Juergen

2017-07-01

Aspergillus fumigatus is an opportunistic fungal pathogen causing detrimental infections in immunocompromised individuals. Dendritic cells (DCs) are potent antigen-presenting cells and recognize the A. fumigatus cell wall component β-1,3 glucan via Dectin-1, followed by DC maturation and cytokine release. Here, we demonstrate that human primary myeloid DCs (mDCs) interact with different morphotypes of A. fumigatus. Dectin-1 is expressed on mDCs and is down-regulated after contact with A. fumigatus, indicating that mDCs recognize A. fumigatus via this receptor. Blocking of Dectin-1, followed by stimulation with depleted zymosan diminished the up-regulation of the T-cell co-stimulatory molecules CD40, CD80, HLA-DR and CCR7 on mDCs and led to decreased release of the cytokines TNF-α, IL-8, IL-1β and IL-10. © 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.

The Draft Genome of the Invasive Walking Stick, Medauroidea extradendata, Reveals Extensive Lineage-Specific Gene Family Expansions of Cell Wall Degrading Enzymes in Phasmatodea

PubMed Central

Brand, Philipp; Lin, Wei; Johnson, Brian R.

2018-01-01

Plant cell wall components are the most abundant macromolecules on Earth. The study of the breakdown of these molecules is thus a central question in biology. Surprisingly, plant cell wall breakdown by herbivores is relatively poorly understood, as nearly all early work focused on the mechanisms used by symbiotic microbes to breakdown plant cell walls in insects such as termites. Recently, however, it has been shown that many organisms make endogenous cellulases. Insects, and other arthropods, in particular have been shown to express a variety of plant cell wall degrading enzymes in many gene families with the ability to break down all the major components of the plant cell wall. Here we report the genome of a walking stick, Medauroidea extradentata, an obligate herbivore that makes uses of endogenously produced plant cell wall degrading enzymes. We present a draft of the 3.3Gbp genome along with an official gene set that contains a diversity of plant cell wall degrading enzymes. We show that at least one of the major families of plant cell wall degrading enzymes, the pectinases, have undergone a striking lineage-specific gene family expansion in the Phasmatodea. This genome will be a useful resource for comparative evolutionary studies with herbivores in many other clades and will help elucidate the mechanisms by which metazoans breakdown plant cell wall components. PMID:29588379

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

PubMed

Sarkar, Purbasha; Bosneaga, Elena; Auer, Manfred

2009-01-01

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

Differential growth of pavement cells of Arabidopsis thaliana leaf epidermis as revealed by microbead labeling.

PubMed

Elsner, Joanna; Lipowczan, Marcin; Kwiatkowska, Dorota

2018-02-01

In numerous vascular plants, pavement cells of the leaf epidermis are shaped like a jigsaw-puzzle piece. Knowledge about the subcellular pattern of growth that accompanies morphogenesis of such a complex shape is crucial for studies of the role of the cytoskeleton, cell wall and phytohormones in plant cell development. Because the detailed growth pattern of the anticlinal and periclinal cell walls remains unknown, our aim was to measure pavement cell growth at a subcellular resolution. Using fluorescent microbeads applied to the surface of the adaxial leaf epidermis of Arabidopsis thaliana as landmarks for growth computation, we directly assessed the growth rates for the outer periclinal and anticlinal cell walls at a subcellular scale. We observed complementary tendencies in the growth pattern of the outer periclinal and anticlinal cell walls. Central portions of periclinal walls were characterized by relatively slow growth, while growth of the other wall portions was heterogeneous. Local growth of the periclinal walls accompanying lobe development after initiation was relatively fast and anisotropic, with maximal extension usually in the direction along the lobe axis. This growth pattern of the periclinal walls was complemented by the extension of the anticlinal walls, which was faster on the lobe sides than at the tips. Growth of the anticlinal and outer periclinal walls of leaf pavement cells is heterogeneous. The growth of the lobes resembles cell elongation via diffuse growth rather than tip growth. © 2018 Botanical Society of America.

Liver stem/progenitor cells in the canals of Hering: cellular origin of hepatocellular carcinoma with bile duct tumor thrombi?

PubMed

Peng, Ningfu; Li, Lequn; Cai, Xiang; Tan, Shaozao; Wu, Ting

2010-12-01

It is generally believed that the invasion of hepatocellular carcinoma (HCC) into the biliary tree ultimately leads to the formation of bile duct tumor thrombi (BDTT). However, recent studies revealed that primary tumor might be small, even undetectable, and there was no histopathologic evidence of direct tumor invasion into bile duct wall in some patients. During the last decade, efforts on stem cell biology may shed light on the pathogenesis of BDTT. Presently, accumulating evidence supports the following notions: (1) the canals of Hering (CoH) are the most likely origin of liver stem/progenitor cells (LSPCs) in adult livers; (2) similar signalling pathways may regulate self-renewal in LSPCs and liver cancer cells, and a substantial proportion of liver tumors may often originate from the transformation of LSPCs; and (3) liver cancer contains rare cells with stem cell-like properties, which could derive from malignant transformation of LSPCs. Herein, we propose that HCC with BDTT, especially with small or undetectable primary lesion and/or no histopathologic evidence for bile duct invasion, might arise from LSPCs residing in the CoH and, possibly, some primary lesions are formed firstly within the intrahepatic biliary tree. When "tumor thrombi" extends mainly along bile duct, there might be "BDTT" alone; when it invades into surrounding parenchyma, there might often be small "primary tumor" with "BDTT". If this holds true, the putative type may be a particular subset of HCC, and most importantly it would facilitate our understanding of stem-cell origin of HCC.

Temperature modulates the cell wall mechanical properties of rice coleoptiles by altering the molecular mass of hemicellulosic polysaccharides

NASA Technical Reports Server (NTRS)

Nakamura, Yukiko; Wakabayashi, Kazuyuki; Hoson, Takayuki

2003-01-01

The present study was conducted to investigate the mechanism inducing the difference in the cell wall extensibility of rice (Oryza sativa L. cv. Koshihikari) coleoptiles grown under various temperature (10-50 degrees C) conditions. The growth rate and the cell wall extensibility of rice coleoptiles exhibited the maximum value at 30-40 degrees C, and became smaller as the growth temperature rose or dropped from this temperature range. The amounts of cell wall polysaccharides per unit length of coleoptile increased in coleoptiles grown at 40 degrees C, but not at other temperature conditions. On the other hand, the molecular size of hemicellulosic polysaccharides was small at temperatures where the cell wall extensibility was high (30-40 degrees C). The autolytic activities of cell walls obtained from coleoptiles grown at 30 and 40 degrees C were substantially higher than those grown at 10, 20 and 50 degrees C. Furthermore, the activities of (1-->3),(1-->4)-beta-glucanases extracted from coleoptile cell walls showed a similar tendency. When oat (1-->3),(1-->4)-beta-glucans with high molecular mass were incubated with the cell wall enzyme preparations from coleoptiles grown at various temperature conditions, the extensive molecular mass downshifts were brought about only by the cell wall enzymes obtained from coleoptiles grown at 30-40 degrees C. There were close correlations between the cell wall extensibility and the molecular mass of hemicellulosic polysaccharides or the activity of beta -glucanases. These results suggest that the environmental temperature regulates the cell wall extensibility of rice coleoptiles by modifying mainly the molecular mass of hemicellulosic polysaccharides. Modulation of the activity of beta-glucanases under various temperature conditions may be involved in the alteration of the molecular size of hemicellulosic polysaccharides.

The Complex Cell Wall Composition of Syncytia Induced by Plant Parasitic Cyst Nematodes Reflects Both Function and Host Plant.

PubMed

Zhang, Li; Lilley, Catherine J; Imren, Mustafa; Knox, J Paul; Urwin, Peter E

2017-01-01

Plant-parasitic cyst nematodes induce the formation of specialized feeding structures, syncytia, within their host roots. These unique plant organs serve as the sole nutrient resource for development and reproduction throughout the biotrophic interaction. The multinucleate syncytium, which arises through local dissolution of cell walls and protoplast fusion of multiple adjacent cells, has dense cytoplasm containing numerous organelles, surrounded by thickened outer cell walls that must withstand high turgor pressure. However, little is known about how the constituents of the syncytial cell wall and their conformation support its role during nematode parasitism. We used a set of monoclonal antibodies, targeted to a range of plant cell wall components, to reveal the microstructures of syncytial cell walls induced by four of the most economically important cyst nematode species, Globodera pallida , Heterodera glycines , Heterodera avenae and Heterodera filipjevi , in their respective potato, soybean, and spring wheat host roots. In situ fluorescence analysis revealed highly similar cell wall composition of syncytia induced by G. pallida and H. glycines . Both consisted of abundant xyloglucan, methyl-esterified homogalacturonan and pectic arabinan. In contrast, the walls of syncytia induced in wheat roots by H. avenae and H. filipjevi contain little xyloglucan but are rich in feruloylated xylan and arabinan residues, with variable levels of mixed-linkage glucan. The overall chemical composition of syncytial cell walls reflected the general features of root cell walls of the different host plants. We relate specific components of syncytial cell walls, such as abundant arabinan, methyl-esterification status of pectic homogalacturonan and feruloylation of xylan, to their potential roles in forming a network to support both the strength and flexibility required for syncytium function.

The Complex Cell Wall Composition of Syncytia Induced by Plant Parasitic Cyst Nematodes Reflects Both Function and Host Plant

PubMed Central

Zhang, Li; Lilley, Catherine J.; Imren, Mustafa; Knox, J. Paul; Urwin, Peter E.

2017-01-01

Plant–parasitic cyst nematodes induce the formation of specialized feeding structures, syncytia, within their host roots. These unique plant organs serve as the sole nutrient resource for development and reproduction throughout the biotrophic interaction. The multinucleate syncytium, which arises through local dissolution of cell walls and protoplast fusion of multiple adjacent cells, has dense cytoplasm containing numerous organelles, surrounded by thickened outer cell walls that must withstand high turgor pressure. However, little is known about how the constituents of the syncytial cell wall and their conformation support its role during nematode parasitism. We used a set of monoclonal antibodies, targeted to a range of plant cell wall components, to reveal the microstructures of syncytial cell walls induced by four of the most economically important cyst nematode species, Globodera pallida, Heterodera glycines, Heterodera avenae and Heterodera filipjevi, in their respective potato, soybean, and spring wheat host roots. In situ fluorescence analysis revealed highly similar cell wall composition of syncytia induced by G. pallida and H. glycines. Both consisted of abundant xyloglucan, methyl-esterified homogalacturonan and pectic arabinan. In contrast, the walls of syncytia induced in wheat roots by H. avenae and H. filipjevi contain little xyloglucan but are rich in feruloylated xylan and arabinan residues, with variable levels of mixed-linkage glucan. The overall chemical composition of syncytial cell walls reflected the general features of root cell walls of the different host plants. We relate specific components of syncytial cell walls, such as abundant arabinan, methyl-esterification status of pectic homogalacturonan and feruloylation of xylan, to their potential roles in forming a network to support both the strength and flexibility required for syncytium function. PMID:28680436

Multiple cell radiation detector system, and method, and submersible sonde

DOEpatents

Johnson, Larry O.; McIsaac, Charles V.; Lawrence, Robert S.; Grafwallner, Ervin G.

2002-01-01

A multiple cell radiation detector includes a central cell having a first cylindrical wall providing a stopping power less than an upper threshold; an anode wire suspended along a cylindrical axis of the central cell; a second cell having a second cylindrical wall providing a stopping power greater than a lower threshold, the second cylindrical wall being mounted coaxially outside of the first cylindrical wall; a first end cap forming a gas-tight seal at first ends of the first and second cylindrical walls; a second end cap forming a gas-tight seal at second ends of the first and second cylindrical walls; and a first group of anode wires suspended between the first and second cylindrical walls.

Live Candida albicans suppresses production of reactive oxygen species in phagocytes.

PubMed

Wellington, Melanie; Dolan, Kristy; Krysan, Damian J

2009-01-01

Production of reactive oxygen species (ROS) is an important aspect of phagocyte-mediated host responses. Since phagocytes play a crucial role in the host response to Candida albicans, we examined the ability of Candida to modulate phagocyte ROS production. ROS production was measured in the murine macrophage cell line J774 and in primary phagocytes using luminol-enhanced chemiluminescence. J774 cells, murine polymorphonuclear leukocytes (PMN), human monocytes, and human PMN treated with live C. albicans produced significantly less ROS than phagocytes treated with heat-killed C. albicans. Live C. albicans also suppressed ROS production in murine bone marrow-derived macrophages from C57BL/6 mice, but not from BALB/c mice. Live C. albicans also suppressed ROS in response to external stimuli. C. albicans and Candida glabrata suppressed ROS production by phagocytes, whereas Saccharomyces cerevisiae stimulated ROS production. The cell wall is the initial point of contact between Candida and phagocytes, but isolated cell walls from both heat-killed and live C. albicans stimulated ROS production. Heat-killed C. albicans has increased surface exposure of 1,3-beta-glucan, a cell wall component that can stimulate phagocytes. To determine whether surface 1,3-beta-glucan exposure accounted for the difference in ROS production, live C. albicans cells were treated with a sublethal dose of caspofungin to increase surface 1,3-beta-glucan exposure. Caspofungin-treated C. albicans was fully able to suppress ROS production, indicating that suppression of ROS overrides stimulatory signals from 1,3-beta-glucan. These studies indicate that live C. albicans actively suppresses ROS production in phagocytes in vitro, which may represent an important immune evasion mechanism.

Live Candida albicans Suppresses Production of Reactive Oxygen Species in Phagocytes▿ †

PubMed Central

Wellington, Melanie; Dolan, Kristy; Krysan, Damian J.

2009-01-01

Production of reactive oxygen species (ROS) is an important aspect of phagocyte-mediated host responses. Since phagocytes play a crucial role in the host response to Candida albicans, we examined the ability of Candida to modulate phagocyte ROS production. ROS production was measured in the murine macrophage cell line J774 and in primary phagocytes using luminol-enhanced chemiluminescence. J774 cells, murine polymorphonuclear leukocytes (PMN), human monocytes, and human PMN treated with live C. albicans produced significantly less ROS than phagocytes treated with heat-killed C. albicans. Live C. albicans also suppressed ROS production in murine bone marrow-derived macrophages from C57BL/6 mice, but not from BALB/c mice. Live C. albicans also suppressed ROS in response to external stimuli. C. albicans and Candida glabrata suppressed ROS production by phagocytes, whereas Saccharomyces cerevisiae stimulated ROS production. The cell wall is the initial point of contact between Candida and phagocytes, but isolated cell walls from both heat-killed and live C. albicans stimulated ROS production. Heat-killed C. albicans has increased surface exposure of 1,3-β-glucan, a cell wall component that can stimulate phagocytes. To determine whether surface 1,3-β-glucan exposure accounted for the difference in ROS production, live C. albicans cells were treated with a sublethal dose of caspofungin to increase surface 1,3-β-glucan exposure. Caspofungin-treated C. albicans was fully able to suppress ROS production, indicating that suppression of ROS overrides stimulatory signals from 1,3-β-glucan. These studies indicate that live C. albicans actively suppresses ROS production in phagocytes in vitro, which may represent an important immune evasion mechanism. PMID:18981256

Profiling of the toxicity mechanisms of coated and uncoated silver nanoparticles to yeast Saccharomyces cerevisiae BY4741 using a set of its 9 single-gene deletion mutants defective in oxidative stress response, cell wall or membrane integrity and endocytosis.

PubMed

Käosaar, Sandra; Kahru, Anne; Mantecca, Paride; Kasemets, Kaja

2016-09-01

The widespread use of nanosilver in various antibacterial, antifungal, and antiviral products warrants the studies of the toxicity pathways of nanosilver-enabled materials toward microbes and viruses. We profiled the toxicity mechanisms of uncoated, casein-coated, and polyvinylpyrrolidone-coated silver nanoparticles (AgNPs) using Saccharomyces cerevisiae wild-type (wt) and its 9 single-gene deletion mutants defective in oxidative stress (OS) defense, cell wall/membrane integrity, and endocytosis. The 48-h growth inhibition assay in organic-rich growth medium and 24-h cell viability assay in deionized (DI) water were applied whereas AgNO3, H2O2, and SDS served as positive controls. Both coated AgNPs (primary size 8-12nm) were significantly more toxic than the uncoated (~85nm) AgNPs. All studied AgNPs were ~30 times more toxic if exposed to yeast cells in DI water than in the rich growth medium: the IC50 based on nominal concentration of AgNPs in the growth inhibition test ranged from 77 to 576mg Ag/L and in the cell viability test from 2.7 to 18.7mg Ag/L, respectively. Confocal microscopy showed that wt but not endocytosis mutant (end3Δ) internalized AgNPs. Comparison of toxicity patterns of wt and mutant strains defective in OS defense and membrane integrity revealed that the toxicity of the studied AgNPs to S. cerevisiae was not caused by the OS or cell wall/membrane permeabilization. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of electromagnetic pulse exposure on permeability of blood-testicle barrier in mice.

PubMed

Wang, Xiao-Wu; Ding, Gui-Rong; Shi, Chang-Hong; Zhao, Tao; Zhang, Jie; Zeng, Li-Hua; Guo, Guo-Zhen

2008-06-01

To study the effect of electromagnetic pulse (EMP) exposure on the permeability of blood-testicle barrier (BTB) in mice. Adult male BALB/c mice were exposed to EMP at 200 kV/m for 200 pulses with 2 seconds interval. The mice were injected with 2% Evans Blue solution through caudal vein at different time points after exposure, and the permeability of BTB was monitored using a fluorescence microscope. The testis sample for the transmission electron microscopy was prepared at 2 h after EMP exposure. The permeability of BTB in mice was observed by using Evans Blue tracer and lanthanum nitrate tracer. After exposure, cloudy Evans Blue was found in the testicle convoluted seminiferous tubule of mice. Lanthanum nitrate was observed not only between testicle spermatogonia near seminiferous tubule wall and sertoli cells, but also between sertoli cells and primary spermatocyte or secondary spermatocyte. In contrast, lanthanum nitrate in control group was only found in the testicle sertoli cells between seminiferous tubule and near seminiferous tubule wall. EMP exposure could increase the permeability of BTB in the mice.

Transmission electron microscopy, fluorescence microscopy, and confocal raman microscopic analysis of ultrastructural and compositional heterogeneity of Cornus alba L. wood cell wall.

PubMed

Ma, Jianfeng; Ji, Zhe; Zhou, Xia; Zhang, Zhiheng; Xu, Feng

2013-02-01

Transmission electron microscopy (TEM), fluorescence microscopy, and confocal Raman microscopy can be used to characterize ultrastructural and compositional heterogeneity of plant cell walls. In this study, TEM observations revealed the ultrastructural characterization of Cornus alba L. fiber, vessel, axial parenchyma, ray parenchyma, and pit membrane between cells, notably with the ray parenchyma consisting of two well-defined layers. Fluorescence microscopy evidenced that cell corner middle lamella was more lignified than adjacent compound middle lamella and secondary wall with variation in lignification level from cell to cell. In situ Raman images showed that the inhomogeneity in cell wall components (cellulose and lignin) among different cells and within morphologically distinct cell wall layers. As the significant precursors of lignin biosynthesis, the pattern of coniferyl alcohol and aldehyde (joint abbreviation Lignin-CAA for both structures) distribution in fiber cell wall was also identified by Raman images, with higher concentration occurring in the fiber secondary wall where there was the highest cellulose concentration. Moreover, noteworthy was the observation that higher concentration of lignin and very minor amounts of cellulose were visualized in the pit membrane areas. These complementary microanalytical methods provide more accurate and complete information with regard to ultrastructural and compositional characterization of plant cell walls.

Overexpression of PhEXPA1 increases cell size, modifies cell wall polymer composition and affects the timing of axillary meristem development in Petunia hybrida.

PubMed

Zenoni, Sara; Fasoli, Marianna; Tornielli, Giovanni Battista; Dal Santo, Silvia; Sanson, Andrea; de Groot, Peter; Sordo, Sara; Citterio, Sandra; Monti, Francesca; Pezzotti, Mario

2011-08-01

• Expansins are cell wall proteins required for cell enlargement and cell wall loosening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants. • PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein's subcellular localization was established by expressing a PhEXPA1-GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers. • The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed. • These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Tissue and cell-type co-expression networks of transcription factors and wood component genes in Populus trichocarpa.

PubMed

Shi, Rui; Wang, Jack P; Lin, Ying-Chung; Li, Quanzi; Sun, Ying-Hsuan; Chen, Hao; Sederoff, Ronald R; Chiang, Vincent L

2017-05-01

Co-expression networks based on transcriptomes of Populus trichocarpa major tissues and specific cell types suggest redundant control of cell wall component biosynthetic genes by transcription factors in wood formation. We analyzed the transcriptomes of five tissues (xylem, phloem, shoot, leaf, and root) and two wood forming cell types (fiber and vessel) of Populus trichocarpa to assemble gene co-expression subnetworks associated with wood formation. We identified 165 transcription factors (TFs) that showed xylem-, fiber-, and vessel-specific expression. Of these 165 TFs, 101 co-expressed (correlation coefficient, r > 0.7) with the 45 secondary cell wall cellulose, hemicellulose, and lignin biosynthetic genes. Each cell wall component gene co-expressed on average with 34 TFs, suggesting redundant control of the cell wall component gene expression. Co-expression analysis showed that the 101 TFs and the 45 cell wall component genes each has two distinct groups (groups 1 and 2), based on their co-expression patterns. The group 1 TFs (44 members) are predominantly xylem and fiber specific, and are all highly positively co-expressed with the group 1 cell wall component genes (30 members), suggesting their roles as major wood formation regulators. Group 1 TFs include a lateral organ boundary domain gene (LBD) that has the highest number of positively correlated cell wall component genes (36) and TFs (47). The group 2 TFs have 57 members, including 14 vessel-specific TFs, and are generally less correlated with the cell wall component genes. An exception is a vessel-specific basic helix-loop-helix (bHLH) gene that negatively correlates with 20 cell wall component genes, and may function as a key transcriptional suppressor. The co-expression networks revealed here suggest a well-structured transcriptional homeostasis for cell wall component biosynthesis during wood formation.

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

PubMed

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.

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

PubMed

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.

Deformation and failure mechanism of secondary cell wall in Spruce late wood

NASA Astrophysics Data System (ADS)

Adusumalli, Ramesh-Babu; Raghavan, Rejin; Ghisleni, Rudy; Zimmermann, Tanja; Michler, Johann

2010-08-01

The deformation and failure of the secondary cell wall of Spruce wood was studied by in-situ SEM compression of micropillars machined by the focused ion beam technique. The cell wall exhibited yield strength values of approximately 160 MPa and large scale plasticity. High resolution SEM imaging post compression revealed bulging of the pillars followed by shear failure. With additional aid of cross-sectional analysis of the micropillars post compression, a model for deformation and failure mechanism of the cell wall has been proposed. The cell wall consists of oriented cellulose microfibrils with high aspect ratio embedded in a hemicellulose-lignin matrix. The deformation of the secondary wall occurs by asymmetric out of plane bulging because of buckling of the microfibrils. Failure of the cell wall following the deformation occurs by the formation of a shear or kink band.

Catechol-Functional Chitosan/Silver Nanoparticle Composite as a Highly Effective Antibacterial Agent with Species-Specific Mechanisms.

PubMed

Huang, Xiaofei; Bao, Xiaojiong; Liu, Yalan; Wang, Zhengke; Hu, Qiaoling

2017-05-12

In this study, silver nanoparticles (Ag NPs) coated with catechol-conjugated chitosan (CSS) were prepared using green methods. Interestingly, we uncovered that CSS-coated Ag NPs (CSS-Ag NPs) exhibited a higher toxicity against gram-negative Escherichia coli (E. coli) bacteria than against gram-positive Staphylococcus aureus (S. aureus) bacteria. The differences revealed that the CSS-Ag NPs killed gram bacteria with distinct, species-specific mechanisms. The aim of this study is to further investigate these underlying mechanisms through a series of analyses. The ultrastructure and morphology of the bacteria before and after treatment with CSS-Ag NPs were observed. The results demonstrated the CSS-Ag NPs killed gram-positive bacteria through a disorganization of the cell wall and leakage of cytoplasmic content. In contrast, the primary mechanism of action on gram-negative bacteria was a change in membrane permeability, induced by adsorption of CSS-Ag NPs. The species-specific mechanisms are caused by structural differences in the cell walls of gram bacteria. Gram-positive bacteria are protected from CSS-Ag NPs by a thicker cell wall, while gram-negatives are more easily killed due to an interaction between a special outer membrane and the nanoparticles. Our study offers an in-depth understanding of the antibacterial behaviors of CSS-Ag NPs and provides insights into ultimately optimizing the design of Ag NPs for treatment of bacterial infections.

Cell Wall Localization of Two DUF642 Proteins, BIIDXI and TEEBE, during Meloidogyne incognita Early Inoculation

PubMed Central

Salazar-Iribe, Alexis; Zúñiga-Sánchez, Esther; Mejía, Emma Zavaleta; Gamboa-deBuen, Alicia

2017-01-01

The root-knot nematode Meloidogyne incognita infects a variety of plants, including Arabidopsis thaliana. During migration, root-knot nematodes secrete different proteins to modify cell walls, which include pectolytic enzymes. However, the contribution of host cell wall proteins has not been described during this process. The function of two DUF642 cell wall proteins, BIIDXI (BDX, At4g32460) and TEEBE (TEB, At2g41800), in plant development could be related to the regulation of pectin methyl esterification status in the cell walls of different tissues. Accordingly, the expression of these two genes is up-regulated by auxin. BDX and TEB were highly induced during early M. incognita inoculation. Moreover, cell wall localization of the proteins was also induced. The cell wall localization of BDX and TEB DUF642 proteins during M. incognita early inoculation suggested that these two proteins could be involved in the regulation of the degree of pectin methylation during cell separation. PMID:29238286

Mechanism of cassava tuber cell wall weakening by dilute sodium hydroxide steeping.

PubMed

Odoch, Martin; Buys, Elna M; Taylor, John R N

2017-08-01

Steeping of cassava root pieces in 0.75% NaOH in combination with wet milling was investigated to determine whether and how dilute NaOH modifies cassava cell walls. Gas chromatography data of cell wall constituent sugar composition and Fourier transform infrared (FTIR) data showed that NaOH steeping reduced the level of pectin in cassava cell walls. FTIR and wide-angle X-ray scattering spectroscopy also indicated that NaOH steeping combined with fine milling slightly reduced cellulose crystallinity. Scanning electron microscopy showed that NaOH steeping produced micropores in the cell walls and light microscopy revealed that NaOH steeping increased disaggregation of parenchyma cells. Steeping of ground cassava in NaOH resulted in a 12% decrease in large residue particles and approx. 4% greater starch yield with wet milling. Therefore dilute NaOH steeping can improve the effectiveness of wet milling in disintegrating cell walls through solubilisation of pectin, thereby reduced cell wall strength. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shifting foundations: the mechanical cell wall and development.

PubMed

Braybrook, Siobhan A; Jönsson, Henrik

2016-02-01

The cell wall has long been acknowledged as an important physical mediator of growth in plants. Recent experimental and modelling work has brought the importance of cell wall mechanics into the forefront again. These data have challenged existing dogmas that relate cell wall structure to cell/organ growth, that uncouple elasticity from extensibility, and those which treat the cell wall as a passive and non-stressed material. Within this review we describe experiments and models which have changed the ways in which we view the mechanical cell wall, leading to new hypotheses and research avenues. It has become increasingly apparent that while we often wish to simplify our systems, we now require more complex multi-scale experiments and models in order to gain further insight into growth mechanics. We are currently experiencing an exciting and challenging shift in the foundations of our understanding of cell wall mechanics in growth and development. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

30 years of battling the cell wall.

PubMed

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.

Propidium iodide competes with Ca(2+) to label pectin in pollen tubes and Arabidopsis root hairs.

PubMed

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

2011-09-01

We have used propidium iodide (PI) to investigate the dynamic properties of the primary cell wall at the apex of Arabidopsis (Arabidopsis thaliana) root hairs and pollen tubes and in lily (Lilium formosanum) pollen tubes. Our results show that in root hairs, as in pollen tubes, oscillatory peaks in PI fluorescence precede growth rate oscillations. Pectin forms the primary component of the cell wall at the tip of both root hairs and pollen tubes. Given the electronic structure of PI, we investigated whether PI binds to pectins in a manner analogous to Ca(2+) binding. We first show that Ca(2+) is able to abrogate PI growth inhibition in a dose-dependent manner. PI fluorescence itself also relies directly on the amount of Ca(2+) in the growth solution. Exogenous pectin methyl esterase treatment of pollen tubes, which demethoxylates pectins, freeing more Ca(2+)-binding sites, leads to a dramatic increase in PI fluorescence. Treatment with pectinase leads to a corresponding decrease in fluorescence. These results are consistent with the hypothesis that PI binds to demethoxylated pectins. Unlike other pectin stains, PI at low yet useful concentration is vital and specifically does not alter the tip-focused Ca(2+) gradient or growth oscillations. These data suggest that pectin secretion at the apex of tip-growing plant cells plays a critical role in regulating growth, and PI represents an excellent tool for examining the role of pectin and of Ca(2+) in tip growth.

A spinal cord fate map in the avian embryo: while regressing, Hensen's node lays down the notochord and floor plate thus joining the spinal cord lateral walls.

PubMed

Catala, M; Teillet, M A; De Robertis, E M; Le Douarin, M L

1996-09-01

The spinal cord of thoracic, lumbar and caudal levels is derived from a region designated as the sinus rhomboidalis in the 6-somite-stage embryo. Using quail/chick grafts performed in ovo, we show the following. (1) The floor plate and notochord derive from a common population of cells, located in Hensen's node, which is equivalent to the chordoneural hinge (CNH) as it was defined at the tail bud stage. (2) The lateral walls and the roof of the neural tube originate caudally and laterally to Hensen's node, during the regression of which the basal plate anlage is bisected by floor plate tissue. (3) Primary and secondary neurulations involve similar morphogenetic movements but, in contrast to primary neurulation, extensive bilateral cell mixing is observed on the dorsal side of the region of secondary neurulation. (4) The posterior midline of the sinus rhomboidalis gives rise to somitic mesoderm and not to spinal cord. Moreover, mesodermal progenitors are spatially arranged along the rest of the primitive streak, more caudal cells giving rise to more lateral embryonic structures. Together with the results reported in our study of tail bud development (Catala, M., Teillet, M.-A. and Le Douarin, N.M. (1995). Mech. Dev. 51, 51-65), these results show that the mechanisms that preside at axial elongation from the 6-somite stage onwards are fundamentally similar during the complete process of neurulation.

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.

PubMed

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.

Changes in Cell Wall Properties Coincide with Overexpression of Extensin Fusion Proteins in Suspension Cultured Tobacco Cells

DOE PAGES

Tan, Li; Pu, Yunqiao; Pattathil, Sivakumar; ...

2014-12-23

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 increasedmore » 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. In conclusion, these data indicate that overexpression of modified extensins may be a route to engineer plants for bioenergy and biomaterial production.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nielsen, Erik Etlar

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 followingmore » objective: Identification of the cell wall polysaccharide class that CSLD proteins synthesize.« less

Characterization and elimination of undesirable protein residues in plant cell walls for enhancing lignin analysis by solution-state 2D gel-NMR methods

USDA-ARS?s Scientific Manuscript database

Proteins exist in every plant cell wall. Certain protein residues interfere with lignin characterization and quantification. The current solution-state 2D-NMR technique (gel-NMR) for whole plant cell wall structural profiling provides detailed information regarding cell walls and proteins. However, ...

How do culture media influence in vitro perivascular cell behavior?

PubMed

Huber, Birgit; Volz, Ann-Cathrin; Kluger, Petra Juliane

2015-12-01

Perivascular cells are multilineage cells located around the vessel wall and important for wall stabilization. In this study, we evaluated a stem cell media and a perivascular cell-specific media for the culture of primary perivascular cells regarding their cell morphology, doubling time, stem cell properties, and expression of cell type-specific markers. When the two cell culture media were compared to each other, perivascular cells cultured in the stem cell medium had a more elongated morphology and a faster doubling rate and cells cultured in the pericyte medium had a more typical morphology, with several filopodia, and a slower doubling rate. To evaluate stem cell properties, perivascular cells, CD146(-) cells, and mesenchymal stem cells (MSCs) were differentiated into the adipogenic, osteogenic, and chondrogenic lineages. It was seen that perivascular cells, as well as CD146(-) cells and MSCs, cultured in stem cell medium showed greater differentiation than cells cultured in pericyte-specific medium. The expression of pericyte-specific markers CD146, neural/glial antigen 2 (NG2), platelet-derived growth factor receptor-β (PDGFR-β), myosin, and α-smooth muscle actin (α-SMA) could be found in both pericyte cultures, as well as to varying amounts in CD146(-) cells, MSCs, and endothelial cells. The here presented work shows that perivascular cells can adapt to their in vitro environment and cell culture conditions influence cell functionality, such as doubling rate or differentiation behavior. Pericyte-specific markers were shown to be expressed also from cells other than perivascular cells. We can further conclude that CD146(+) perivascular cells are inhomogeneous cell population probably containing stem cell subpopulations, which are located perivascular around capillaries. © 2015 International Federation for Cell Biology.

Cell Wall Structure in Cells Adapted to Growth on the Cellulose-Synthesis Inhibitor 2,6-Dichlorobenzonitrile 1

PubMed Central

Shedletzky, Esther; Shmuel, Miri; Trainin, Tali; Kalman, Sara; Delmer, Deborah

1992-01-01

Our previous work (E. Shedletzky, M. Shmuel, D.P. Delmer, D.T.A. Lamport [1990] Plant Physiol 94:980-987) showed that suspension-cultured tomato cells adapted to growth on the cellulose synthesis inhibitor 2,6-dichlorobenzonitrile (DCB) have a markedly altered cell wall composition, most notably a markedly reduced level of the cellulose-xyloglucan network. This study compares the adaptation to DCB of two cell lines from dicots (tomato [Lycopersicon esculentum] and tobacco [Nicotiana tabacum]) and a Graminaceous monocot (barley [Hordeum bulbosum] endosperm). The difference in wall structures between the dicots and the monocot is reflected in the very different types of wall modifications induced by growth on DCB. The dicots, having reduced levels of cellulose and xyloglucan, possess walls the major integrity of which is provided by Ca2+-bridged pectates because protoplasts can be prepared from these cells simply by treatment with divalent cation chelator and a purified endopolygalacturonase. The tensile strength of these walls is considerably less than walls from nonadapted cells, but wall porosity is not altered. In contrast, walls from adapted barley cells contain very little pectic material and normal to elevated levels of noncellulosic polysaccharides compared with walls from nonadapted cells. Surprisingly, they have tensile strengths higher than their nonadapted counterpart, although cellulose levels are reduced by 70%. Evidence is presented that these walls obtain their additional strength by an altered pattern of cross-linking of polymers involving phenolic components. Such cross-linking may also explain the observation that the porosity of these walls is also considerably reduced. Cells of adapted lines of both the dicots and barley are resistant to plasmolysis, suggesting that they possess very strong connections between the wall and the plasma membrane. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:16652933

Attachment of Salmonella strains to a plant cell wall model is modulated by surface characteristics and not by specific carbohydrate interactions.

PubMed

Tan, Michelle Sze-Fan; Moore, Sean C; Tabor, Rico F; Fegan, Narelle; Rahman, Sadequr; Dykes, Gary A

2016-09-15

Processing of fresh produce exposes cut surfaces of plant cell walls that then become vulnerable to human foodborne pathogen attachment and contamination, particularly by Salmonella enterica. Plant cell walls are mainly composed of the polysaccharides cellulose, pectin and hemicelluloses (predominantly xyloglucan). Our previous work used bacterial cellulose-based plant cell wall models to study the interaction between Salmonella and the various plant cell wall components. We demonstrated that Salmonella attachment was favoured in the presence of pectin while xyloglucan had no effect on its attachment. Xyloglucan significantly increased the attachment of Salmonella cells to the plant cell wall model only when it was in association with pectin. In this study, we investigate whether the plant cell wall polysaccharides mediate Salmonella attachment to the bacterial cellulose-based plant cell wall models through specific carbohydrate interactions or through the effects of carbohydrates on the physical characteristics of the attachment surface. We found that none of the monosaccharides that make up the plant cell wall polysaccharides specifically inhibit Salmonella attachment to the bacterial cellulose-based plant cell wall models. Confocal laser scanning microscopy showed that Salmonella cells can penetrate and attach within the tightly arranged bacterial cellulose network. Analysis of images obtained from atomic force microscopy revealed that the bacterial cellulose-pectin-xyloglucan composite with 0.3 % (w/v) xyloglucan, previously shown to have the highest number of Salmonella cells attached to it, had significantly thicker cellulose fibrils compared to other composites. Scanning electron microscopy images also showed that the bacterial cellulose and bacterial cellulose-xyloglucan composites were more porous when compared to the other composites containing pectin. Our study found that the attachment of Salmonella cells to cut plant cell walls was not mediated by specific carbohydrate interactions. This suggests that the attachment of Salmonella strains to the plant cell wall models were more dependent on the structural characteristics of the attachment surface. Pectin reduces the porosity and space between cellulose fibrils, which then forms a matrix that is able to retain Salmonella cells within the bacterial cellulose network. When present with pectin, xyloglucan provides a greater surface for Salmonella cells to attach through the thickening of cellulose fibrils.

[Gastric perforation caused by primary gastric diffuse large B cell lymphoma].

PubMed

Kim, Ju Seok; Rou, Woo Sun; Ahn, Byung Moo; Moon, Hee Seok; Kang, Sun Hyung; Sung, Jae Kyu; Jeong, Hyun Yong; Song, Kyu-Sang

2015-01-01

Spontaneous gastric perforation is a rare complication of gastric lymphoma that is potentially life threatening since it can progress to sepsis and multi-organ failure. Morbidity also increases due to prolonged hospitalization and delay in initiating chemotherapy. Therefore prompt diagnosis and appropriate treatment is critical to improve prognosis. A 64-year-old man presented to the emergency department with severe abdominal pain. Chest X-ray showed free air below the right diaphragm. Abdominal CT scan also demonstrated free air in the peritoneal cavity with large wall defect in the lesser curvature of gastric lower body. Therefore, the patient underwent emergency operation and primary closure was done. Pathologic specimen obtained during surgery was compatible to diffuse large B cell lymphoma. Fifteen days after primary closure, the patient received subtotal gastrectomy and chemotherapy was initiated after recovery. Patient is currently being followed-up at outpatient department without any particular complications. Herein, we report a rare case of gastric lymphoma that initially presented as peritonitis because of spontaneous gastric perforation.

Changes in Cell Wall Polysaccharides Associated With Growth 1

PubMed Central

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

A plant cell division algorithm based on cell biomechanics and ellipse-fitting.

PubMed

Abera, Metadel K; Verboven, Pieter; Defraeye, Thijs; Fanta, Solomon Workneh; Hertog, Maarten L A T M; Carmeliet, Jan; Nicolai, Bart M

2014-09-01

The importance of cell division models in cellular pattern studies has been acknowledged since the 19th century. Most of the available models developed to date are limited to symmetric cell division with isotropic growth. Often, the actual growth of the cell wall is either not considered or is updated intermittently on a separate time scale to the mechanics. This study presents a generic algorithm that accounts for both symmetrically and asymmetrically dividing cells with isotropic and anisotropic growth. Actual growth of the cell wall is simulated simultaneously with the mechanics. The cell is considered as a closed, thin-walled structure, maintained in tension by turgor pressure. The cell walls are represented as linear elastic elements that obey Hooke's law. Cell expansion is induced by turgor pressure acting on the yielding cell-wall material. A system of differential equations for the positions and velocities of the cell vertices as well as for the actual growth of the cell wall is established. Readiness to divide is determined based on cell size. An ellipse-fitting algorithm is used to determine the position and orientation of the dividing wall. The cell vertices, walls and cell connectivity are then updated and cell expansion resumes. Comparisons are made with experimental data from the literature. The generic plant cell division algorithm has been implemented successfully. It can handle both symmetrically and asymmetrically dividing cells coupled with isotropic and anisotropic growth modes. Development of the algorithm highlighted the importance of ellipse-fitting to produce randomness (biological variability) even in symmetrically dividing cells. Unlike previous models, a differential equation is formulated for the resting length of the cell wall to simulate actual biological growth and is solved simultaneously with the position and velocity of the vertices. The algorithm presented can produce different tissues varying in topological and geometrical properties. This flexibility to produce different tissue types gives the model great potential for use in investigations of plant cell division and growth in silico.

A glycosylphosphatidylinositol anchor is required for membrane localization but dispensable for cell wall association of chitin deacetylase 2 in Cryptococcus neoformans.

PubMed

Gilbert, Nicole M; Baker, Lorina G; Specht, Charles A; Lodge, Jennifer K

2012-01-01

Cell wall proteins (CWPs) mediate important cellular processes in fungi, including adhesion, invasion, biofilm formation, and flocculation. The current model of fungal cell wall organization includes a major class of CWPs covalently bound to β-1,6-glucan via a remnant of a glycosylphosphatidylinositol (GPI) anchor. This model was established by studies of ascomycetes more than a decade ago, and relatively little work has been done with other fungi, although the presumption has been that proteins identified in the cell wall which contain a predicted GPI anchor are covalently linked to cell wall glucans. The pathogenic basidiomycete Cryptococcus neoformans encodes >50 putatively GPI-anchored proteins, some of which have been identified in the cell wall. One of these proteins is chitin deacetylase 2 (Cda2), an enzyme responsible for converting chitin to chitosan, a cell wall polymer recently established as a virulence factor for C. neoformans infection of mammalian hosts. Using a combination of biochemistry, molecular biology, and genetics, we show that Cda2 is GPI anchored to membranes but noncovalently associated with the cell wall by means independent of both its GPI anchor and β-1,6-glucan. We also show that Cda2 produces chitosan when localized to the plasma membrane, but association with the cell wall is not essential for this process, thereby providing insight into the mechanism of chitosan biosynthesis. These results increase our understanding of the surface of C. neoformans and provide models of cell walls likely applicable to other undercharacterized basidiomycete pathogenic fungi. The surface of a pathogenic microbe is a major interface with its host. In fungi, the outer surface consists of a complex matrix known as the cell wall, which includes polysaccharides, proteins, and other molecules. The mammalian host recognizes many of these surface molecules and mounts appropriate responses to combat the microbial infection. Cryptococcus neoformans is a serious fungal pathogen that kills over 600,000 people annually. It converts most of its chitin, a cell wall polysaccharide, to chitosan, which is necessary for virulence. Chitin deacetylase enzymes have been identified in the cell wall, and our studies were undertaken to understand how the deacetylase is linked to the wall and where it has activity. Our results have implications for the current model of chitosan biosynthesis and further challenge the paradigm of covalent linkages between cell wall proteins and polysaccharides through a lipid modification of the protein.

Genetic modification of plant cell walls to enhance biomass yield and biofuel production in bioenergy crops.

PubMed

Wang, Yanting; Fan, Chunfen; Hu, Huizhen; Li, Ying; Sun, Dan; Wang, Youmei; Peng, Liangcai

2016-01-01

Plant cell walls represent an enormous biomass resource for the generation of biofuels and chemicals. As lignocellulose property principally determines biomass recalcitrance, the genetic modification of plant cell walls has been posed as a powerful solution. Here, we review recent progress in understanding the effects of distinct cell wall polymers (cellulose, hemicelluloses, lignin, pectin, wall proteins) on the enzymatic digestibility of biomass under various physical and chemical pretreatments in herbaceous grasses, major agronomic crops and fast-growing trees. We also compare the main factors of wall polymer features, including cellulose crystallinity (CrI), hemicellulosic Xyl/Ara ratio, monolignol proportion and uronic acid level. Furthermore, the review presents the main gene candidates, such as CesA, GH9, GH10, GT61, GT43 etc., for potential genetic cell wall modification towards enhancing both biomass yield and enzymatic saccharification in genetic mutants and transgenic plants. Regarding cell wall modification, it proposes a novel groove-like cell wall model that highlights to increase amorphous regions (density and depth) of the native cellulose microfibrils, providing a general strategy for bioenergy crop breeding and biofuel processing technology. Copyright © 2016 Elsevier Inc. All rights reserved.

Arabidopsis thaliana plants lacking the ARP2/3 complex show defects in cell wall assembly and auxin distribution.

PubMed

Pratap Sahi, Vaidurya; Cifrová, Petra; García-González, Judith; Kotannal Baby, Innu; Mouillé, Gregory; Gineau, Emilie; Müller, Karel; Baluška, František; Soukup, Aleš; Petrášek, Jan; Schwarzerová, Katerina

2017-12-25

The cytoskeleton plays an important role in the synthesis of plant cell walls. Both microtubules and actin cytoskeleton are known to be involved in the morphogenesis of plant cells through their role in cell wall building. The role of ARP2/3-nucleated actin cytoskeleton in the morphogenesis of cotyledon pavement cells has been described before. Seedlings of Arabidopsis mutants lacking a functional ARP2/3 complex display specific cell wall-associated defects. In three independent Arabidopsis mutant lines lacking subunits of the ARP2/3 complex, phenotypes associated with the loss of the complex were analysed throughout plant development. Organ size and anatomy, cell wall composition, and auxin distribution were investigated. ARP2/3-related phenotype is associated with changes in cell wall composition, and the phenotype is manifested especially in mature tissues. Cell walls of mature plants contain less cellulose and a higher amount of homogalacturonan, and display changes in cell wall lignification. Vascular bundles of mutant inflorescence stems show a changed pattern of AUX1-YFP expression. Plants lacking a functional ARP2/3 complex have decreased basipetal auxin transport. The results suggest that the ARP2/3 complex has a morphogenetic function related to cell wall synthesis and auxin transport. © The Author(s) 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

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

PubMed

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.

A new picture of cell wall protein dynamics in elongating cells of Arabidopsis thaliana: Confirmed actors and newcomers

PubMed Central

Irshad, Muhammad; Canut, Hervé; Borderies, Gisèle; Pont-Lezica, Rafael; Jamet, Elisabeth

2008-01-01

Background Cell elongation in plants requires addition and re-arrangements of cell wall components. Even if some protein families have been shown to play roles in these events, a global picture of proteins present in cell walls of elongating cells is still missing. A proteomic study was performed on etiolated hypocotyls of Arabidopsis used as model of cells undergoing elongation followed by growth arrest within a short time. Results Two developmental stages (active growth and after growth arrest) were compared. A new strategy consisting of high performance cation exchange chromatography and mono-dimensional electrophoresis was established for separation of cell wall proteins. This work allowed identification of 137 predicted secreted proteins, among which 51 had not been identified previously. Apart from expected proteins known to be involved in cell wall extension such as xyloglucan endotransglucosylase-hydrolases, expansins, polygalacturonases, pectin methylesterases and peroxidases, new proteins were identified such as proteases, proteins related to lipid metabolism and proteins of unknown function. Conclusion This work highlights the CWP dynamics that takes place between the two developmental stages. The presence of proteins known to be related to cell wall extension after growth arrest showed that these proteins may play other roles in cell walls. Finally, putative regulatory mechanisms of protein biological activity are discussed from this global view of cell wall proteins. PMID:18796151

Grass cell walls: A story of cross-linking

USDA-ARS?s Scientific Manuscript database

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

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

PubMed

Cosgrove, Daniel J

2016-01-01

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. © 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.

Critical cell wall hole size for lysis in Gram-positive bacteria

NASA Astrophysics Data System (ADS)

Mitchell, Gabriel; Wiesenfeld, Kurt; Nelson, Daniel; Weitz, Joshua

2013-03-01

Gram-positive bacteria transport molecules necessary for their survival through holes in their cell wall. The holes in cell walls need to be large enough to let critical nutrients pass through. However, the cell wall must also function to prevent the bacteria's membrane from protruding through a large hole into the environment and lysing the cell. As such, we hypothesize that there exists a range of cell wall hole sizes that allow for molecule transport but prevent membrane protrusion. Here we develop and analyze a biophysical theory of the response of a Gram-positive cell's membrane to the formation of a hole in the cell wall. We predict a critical hole size in the range 15-24nm beyond which lysis occurs. To test our theory, we measured hole sizes in Streptococcus pyogenes cells undergoing enzymatic lysis via transmission electron microscopy. The measured hole sizes are in strong agreement with our theoretical prediction. Together, the theory and experiments provide a means to quantify the mechanisms of death of Gram-positive cells via enzymatically mediated lysis and provides insight into the range of cell wall hole sizes compatible with bacterial homeostasis.

Elevated Cell Wall Serine in Pleiotropic Staphylococcal Mutants

PubMed Central

Korman, Ruth Z.

1966-01-01

Korman, Ruth Z. (Cornell University, Ithaca, N.Y.). Elevated cell wall serine in pleiotropic staphylococcal mutants. J. Bacteriol. 92:762–768. 1966.—Physically purified cell walls were prepared from two staphylococcal strains and from pleiotropic variants derived from them. The quantitative amino acid and amino sugar content of these walls is reported. The pleiotypes, which are identified culturally by their failure to elaborate coagulase, their resistance to bacteriophage, and their sensitivity to mannitol, have altered molar ratios of amino acids and amino sugars in their cell walls. In comparison with lysine content, the serine content of the mutant wall is elevated and the glycine content is reduced. The glucosamine content is reduced also. It is postulated that the pleiotropic mutants possess an altered cell wall biosynthetic pathway. Images PMID:5922547

Cell wall integrity signaling in plants: "To grow or not to grow that's the question".

PubMed

Voxeur, Aline; Höfte, Herman

2016-09-01

Plants, like yeast, have the ability to monitor alterations in the cell wall architecture that occur during normal growth or in changing environments and to trigger compensatory changes in the cell wall. We discuss how recent advances in our understanding of the cell wall architecture provide new insights into the role of cell wall integrity sensing in growth control. Next we review the properties of membrane receptor-like kinases that have roles in pH control, mechano-sensing and reactive oxygen species accumulation in growing cells and which may be the plant equivalents of the yeast cell wall integrity (CWI) sensors. Finally, we discuss recent findings showing an increasing role for CWI signaling in plant immunity and the adaptation to changes in the ionic environment of plant cells. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Mechanochemical Polarization of Contiguous Cell Walls Shapes Plant Pavement Cells.

PubMed

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.

Phylogenetic analysis of pectin-related gene families in Physcomitrella patens and nine other plant species yields evolutionary insights into cell walls

PubMed Central

2014-01-01

Background Pectins are acidic sugar-containing polysaccharides that are universally conserved components of the primary cell walls of plants and modulate both tip and diffuse cell growth. However, many of their specific functions and the evolution of the genes responsible for producing and modifying them are incompletely understood. The moss Physcomitrella patens is emerging as a powerful model system for the study of plant cell walls. To identify deeply conserved pectin-related genes in Physcomitrella, we generated phylogenetic trees for 16 pectin-related gene families using sequences from ten plant genomes and analyzed the evolutionary relationships within these families. Results Contrary to our initial hypothesis that a single ancestral gene was present for each pectin-related gene family in the common ancestor of land plants, five of the 16 gene families, including homogalacturonan galacturonosyltransferases, polygalacturonases, pectin methylesterases, homogalacturonan methyltransferases, and pectate lyase-like proteins, show evidence of multiple members in the early land plant that gave rise to the mosses and vascular plants. Seven of the gene families, the UDP-rhamnose synthases, UDP-glucuronic acid epimerases, homogalacturonan galacturonosyltransferase-like proteins, β-1,4-galactan β-1,4-galactosyltransferases, rhamnogalacturonan II xylosyltransferases, and pectin acetylesterases appear to have had a single member in the common ancestor of land plants. We detected no Physcomitrella members in the xylogalacturonan xylosyltransferase, rhamnogalacturonan I arabinosyltransferase, pectin methylesterase inhibitor, or polygalacturonase inhibitor protein families. Conclusions Several gene families related to the production and modification of pectins in plants appear to have multiple members that are conserved as far back as the common ancestor of mosses and vascular plants. The presence of multiple members of these families even before the divergence of other important cell wall-related genes, such as cellulose synthases, suggests a more complex role than previously suspected for pectins in the evolution of land plants. The presence of relatively small pectin-related gene families in Physcomitrella as compared to Arabidopsis makes it an attractive target for analysis of the functions of pectins in cell walls. In contrast, the absence of genes in Physcomitrella for some families suggests that certain pectin modifications, such as homogalacturonan xylosylation, arose later during land plant evolution. PMID:24666997

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

NASA Technical Reports Server (NTRS)

Cosgrove, D. J.

1993-01-01

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

Generation of hydroxyl radical in isolated pea root cell wall, and the role of cell wall-bound peroxidase, Mn-SOD and phenolics in their production.

PubMed

Kukavica, Biljana; Mojovic, Milos; Vuccinic, Zeljko; Maksimovic, Vuk; Takahama, Umeo; Jovanovic, Sonja Veljovic

2009-02-01

The hydroxyl radical produced in the apoplast has been demonstrated to facilitate cell wall loosening during cell elongation. Cell wall-bound peroxidases (PODs) have been implicated in hydroxyl radical formation. For this mechanism, the apoplast or cell walls should contain the electron donors for (i) H(2)O(2) formation from dioxygen; and (ii) the POD-catalyzed reduction of H(2)O(2) to the hydroxyl radical. The aim of the work was to identify the electron donors in these reactions. In this report, hydroxyl radical (.OH) generation in the cell wall isolated from pea roots was detected in the absence of any exogenous reductants, suggesting that the plant cell wall possesses the capacity to generate .OH in situ. Distinct POD and Mn-superoxide dismutase (Mn-SOD) isoforms different from other cellular isoforms were shown by native gel electropho-resis to be preferably bound to the cell walls. Electron paramagnetic resonance (EPR) spectroscopy of cell wall isolates containing the spin-trapping reagent, 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO), was used for detection of and differentiation between .OH and the superoxide radical (O(2)(-).). The data obtained using POD inhibitors confirmed that tightly bound cell wall PODs are involved in DEPMPO/OH adduct formation. A decrease in DEPMPO/OH adduct formation in the presence of H(2)O(2) scavengers demonstrated that this hydroxyl radical was derived from H(2)O(2). During the generation of .OH, the concentration of quinhydrone structures (as detected by EPR spectroscopy) increased, suggesting that the H(2)O(2) required for the formation of .OH in isolated cell walls is produced during the reduction of O(2) by hydroxycinnamic acids. Cell wall isolates in which the proteins have been denaturated (including the endogenous POD and SOD) did not produce .OH. Addition of exogenous H(2)O(2) again induced the production of .OH, and these were shown to originate from the Fenton reaction with tightly bound metal ions. However, the appearance of the DEPMPO/OOH adduct could also be observed, due to the production of O(2)(-). when endogenous SOD has been inactivated. Also, O(2)(-). was converted to .OH in an in vitro horseradish peroxidase (HRP)/H(2)O(2) system to which exogenous SOD has been added. Taken together with the discovery of the cell wall-bound Mn-SOD isoform, these results support the role of such a cell wall-bound SOD in the formation of .OH jointly with the cell wall-bound POD. According to the above findings, it seems that the hydroxycinnamic acids from the cell wall, acting as reductants, contribute to the formation of H(2)O(2) in the presence of O(2) in an autocatalytic manner, and that POD and Mn-SOD coupled together generate .OH from such H(2)O(2).