scholarly journals Brassinosteroids Influence Arabidopsis Hypocotyl Graviresponses through Changes in Mannans and Cellulose

2021 ◽  
Author(s):  
Marc Somssich ◽  
Filip Vandenbussche ◽  
Alexander Ivakov ◽  
Norma Funke ◽  
Colin Ruprecht ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cellulose Fibre ◽  
Soil Surface ◽  
Cellular Growth ◽  
Upright Posture ◽  
Cellulose Fibres ◽  
Negative Effect ◽  
Biochemical Analyses ◽  
Plant Shoots ◽  
Cell Wall Mechanics

Abstract The force of gravity is a constant environmental factor. Plant shoots respond to gravity through negative gravitropism and gravity resistance. These responses are essential for plants to direct the growth of aerial organs away from the soil surface after germination and to keep an upright posture above ground. We took advantage of the effect of brassinosteroids (BRs) on the two types of graviresponses in Arabidopsis thaliana hypocotyls to disentangle functions of cell wall polymers during etiolated shoot growth. The ability of etiolated Arabidopsis seedlings to grow upward was suppressed in the presence of 24-epibrassinolide (EBL) but enhanced in the presence of brassinazole (BRZ), an inhibitor of BR biosynthesis. These effects were accompanied by changes in cell wall mechanics and composition. Cell wall biochemical analyses, confocal microscopy of the cellulose-specific pontamine S4B dye and cellular growth analyses revealed that the EBL and BRZ treatments correlated with changes in cellulose fibre organization, cell expansion at the hypocotyl base and mannan content. Indeed, a longitudinal reorientation of cellulose fibres and growth inhibition at the base of hypocotyls supported their upright posture whereas the presence of mannans reduced gravitropic bending. The negative effect of mannans on gravitropism is a new function for this class of hemicelluloses. We also found that EBL interferes with upright growth of hypocotyls through their uneven thickening at the base.

scholarly journals Brassinosteroids Influence Arabidopsis Hypocotyl Graviresponses Through Changes In Mannans And Cellulose

2019 ◽  
Author(s):  
Marc Somssich ◽  
Filip Vandenbussche ◽  
Alexander Ivakov ◽  
Norma Funke ◽  
Colin Ruprecht ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cellulose Fibre ◽  
Soil Surface ◽  
Terrestrial Plants ◽  
Cellulose Fibres ◽  
Negative Effect ◽  
Biochemical Analyses ◽  
Plant Shoots ◽  
Negative Gravitropism ◽  
Cell Wall Mechanics

AbstractThe force of gravity is a constant environmental factor. Plant shoots respond to gravity through negative gravitropism and gravity resistance. These responses are essential for plants to direct the growth of aerial organs away from the soil surface after germination and to keep an upright posture above ground. We took advantage of the effect of brassinosteroids on the two types of graviresponses in Arabidopsis thaliana hypocotyls to disentangle functions of cell wall polymers during etiolated shoot growth. The ability of etiolated Arabidopsis seedlings to grow upwards was suppressed in the presence of 24-epibrassinolide (EBL) but enhanced in the presence of brassinazole (BRZ), an inhibitor of brassinosteroid biosynthesis. These effects were accompanied by changes in cell wall mechanics and composition. Cell wall biochemical analyses and confocal microscopy of the cellulose-specific pontamine S4B dye revealed that the EBL and BRZ treatments correlated with changes in cellulose fibre organization and mannan content. Indeed, a longitudinal re-orientation of cellulose fibres supported upright growth whereas the presence of mannans reduced gravitropic bending. The negative effect of mannans on gravitropism is a new function for this class of hemicelluloses, highlighting evolutionary adaptations by which aquatic ancestors of terrestrial plants colonized land.

scholarly journals Even Visually Intact Cell Walls in Waterlogged Archaeological Wood Are Chemically Deteriorated and Mechanically Fragile: A Case of a 170 Year-Old Shipwreck

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1113 ◽  
Author(s):  
Liuyang Han ◽  
Xingling Tian ◽  
Tobias Keplinger ◽  
Haibin Zhou ◽  
Ren Li ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Intact Cell ◽  
Nitrogen Adsorption ◽  
Wet Chemistry ◽  
Archaeological Wood ◽  
Waterlogged Archaeological Wood ◽  
X Ray Scattering ◽  
Crystallite Structure ◽  
Cell Wall Mechanics

Structural and chemical deterioration and its impact on cell wall mechanics were investigated for visually intact cell walls (VICWs) in waterlogged archaeological wood (WAW). Cell wall mechanical properties were examined by nanoindentation without prior embedding. WAW showed more than 25% decrease of both hardness and elastic modulus. Changes of cell wall composition, cellulose crystallite structure and porosity were investigated by ATR-FTIR imaging, Raman imaging, wet chemistry, 13C-solid state NMR, pyrolysis-GC/MS, wide angle X-ray scattering, and N2 nitrogen adsorption. VICWs in WAW possessed a cleavage of carboxyl in side chains of xylan, a serious loss of polysaccharides, and a partial breakage of β-O-4 interlinks in lignin. This was accompanied by a higher amount of mesopores in cell walls. Even VICWs in WAW were severely deteriorated at the nanoscale with impact on mechanics, which has strong implications for the conservation of archaeological shipwrecks.

scholarly journals Position of O-Acetylation within the Capsular Repeat Unit Impacts the Biological Properties of Pneumococcal Serotypes 33A and 33F

2017 ◽  
Vol 85 (7) ◽  
Author(s):  
Brady L. Spencer ◽  
Jamil S. Saad ◽  
Anukul T. Shenoy ◽  
Carlos J. Orihuela ◽  
Moon H. Nahm
Keyword(s):  
Cell Wall ◽  
Repeat Unit ◽  
Biological Properties ◽  
Immune Recognition ◽  
Content Type ◽  
Pneumococcal Serotype ◽  
Membrane Bound ◽  
Biochemical Analyses ◽  
Opsonophagocytic Killing ◽  
Small Chemical

ABSTRACT Streptococcus pneumoniae (pneumococcus) produces many capsule types that differ in their abilities to evade host immune recognition. To explain these serotype-dependent protective capacities, many studies have investigated capsular thickness or the interaction of the capsule with complement proteins, but the effects of small chemical modifications of the capsule on its function have not been studied. One small chemical modification found frequently among pneumococcal capsules is O-acetylation. Pneumococcal serotype 33A has two membrane-bound O-acetyltransferase genes, wciG and wcjE. A 33A wcjE-deficient variant, 33F, occurs naturally and is increasing in prevalence in the wake of widespread conjugate vaccine use, but no wciG-deficient variants have been reported. To study the biological consequence of the loss of O-acetylation, we created wciG-deficient variants in both serotypes 33A and 33F, which we named 33X1 (ΔwciG) and 33X2 (ΔwciG ΔwcjE). Serotypes 33X1 and 33X2 express novel capsule types based on serological and biochemical analyses. We found that loss of WcjE-mediated O-acetylation appears not to affect cell wall shielding, since serotypes 33A and 33F exhibit comparable nonspecific opsonophagocytic killing, biofilm production, and adhesion to nasopharyngeal cells, though serotype 33F survived short-term drying better than serotype 33A. Loss of WciG-mediated O-acetylation in serotypes 33X1 and 33X2, however, resulted in a phenotype resembling that of nonencapsulated strains: increased cell wall accessibility, increased nonspecific opsonophagocytic killing, enhanced biofilm formation, and increased adhesion to nasopharyngeal cells. We conclude that WciG-mediated, but not WcjE-mediated, O-acetylation is important for producing protective capsules in 33A and that small chemical changes to the capsule can drastically affect its biological properties.

Methods to quantify primary plant cell wall mechanics

2019 ◽  
Vol 70 (14) ◽  
pp. 3615-3648 ◽  
Author(s):  
Amir J Bidhendi ◽  
Anja Geitmann
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Polymer Network ◽  
Plant Cells ◽  
Tensile Tests ◽  
Mechanical Modeling ◽  
Experimental Conditions ◽  
Testing Techniques ◽  
Cell Wall Mechanics

Abstract The primary plant cell wall is a dynamically regulated composite material of multiple biopolymers that forms a scaffold enclosing the plant cells. The mechanochemical make-up of this polymer network regulates growth, morphogenesis, and stability at the cell and tissue scales. To understand the dynamics of cell wall mechanics, and how it correlates with cellular activities, several experimental frameworks have been deployed in recent years to quantify the mechanical properties of plant cells and tissues. Here we critically review the application of biomechanical tool sets pertinent to plant cell mechanics and outline some of their findings, relevance, and limitations. We also discuss methods that are less explored but hold great potential for the field, including multiscale in silico mechanical modeling that will enable a unified understanding of the mechanical behavior across the scales. Our overview reveals significant differences between the results of different mechanical testing techniques on plant material. Specifically, indentation techniques seem to consistently report lower values compared with tensile tests. Such differences may in part be due to inherent differences among the technical approaches and consequently the wall properties that they measure, and partly due to differences between experimental conditions.

scholarly journals Ultrastructural and biochemical analyses reveal cell wall remodelling in lichen-forming microalgae submitted to cyclic desiccation–rehydration

2019 ◽  
Vol 125 (3) ◽  
pp. 459-469 ◽  
Author(s):  
María González-Hourcade ◽  
Marcia R Braga ◽  
Eva M del Campo ◽  
Carmen Ascaso ◽  
Cristina Patiño ◽  
...  
Keyword(s):  
Cell Wall ◽  
Close Contact ◽  
Freeze Substitution ◽  
Water Soluble ◽  
Hot Water ◽  
Cell Shrinkage ◽  
Distinctive Features ◽  
Biochemical Analyses ◽  
Species Specific ◽  
Environmental Sem

Abstract Background and Aims One of the most distinctive features of desiccation-tolerant plants is their high cell wall (CW) flexibility. Most lichen microalgae can tolerate drastic dehydration–rehydration (D/R) conditions; however, their mechanisms of D/R tolerance are scarcely understood. We tested the hypothesis that D/R-tolerant microalgae would have flexible CWs due to species-specific CW ultrastructure and biochemical composition, which could be remodelled by exposure to cyclic D/R. Methods Two lichen microalgae, Trebouxia sp. TR9 (TR9, adapted to rapid D/R cycles) and Coccomyxa simplex (Csol, adapted to seasonal dry periods) were exposed to no or four cycles of desiccation [25–30 % RH (TR9) or 55–60 % RH (Csol)] and 16 h of rehydration (100 % RH). Low-temperature SEM, environmental SEM and freeze-substitution TEM were employed to visualize structural alterations induced by D/R. In addition, CWs were extracted and sequentially fractionated with hot water and KOH, and the gel permeation profile of polysaccharides was analysed in each fraction. The glycosyl composition and linkage of the main polysaccharides of each CW fraction were analysed by GC–MS. Key Results All ultrastructural analyses consistently showed that desiccation caused progressive cell shrinkage and deformation in both microalgae, which could be rapidly reversed when water availability increased. Notably, the plasma membrane of TR9 and Csol remained in close contact with the deformed CW. Exposure to D/R strongly altered the size distribution of TR9 hot-water-soluble polysaccharides, composed mainly of a β-3-linked rhamnogalactofuranan and Csol KOH-soluble β-glucans. Conclusions Cyclic D/R induces biochemical remodelling of the CW that could increase CW flexibility, allowing regulated shrinkage and expansion of D/R-tolerant microalgae.

scholarly journals Piezo-Sensitive Fabrics from Carbon Black Containing Conductive Cellulose Fibres for Flexible Pressure Sensors

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5150
Author(s):  
Julia Ullrich ◽  
Martin Eisenreich ◽  
Yvonne Zimmermann ◽  
Dominik Mayer ◽  
Nina Koehne ◽  
...  
Keyword(s):  
Carbon Black ◽  
Pressure Sensors ◽  
Cellulose Fibre ◽  
Nonwoven Material ◽  
Regenerated Cellulose ◽  
Textile Processing ◽  
Cellulose Fibres ◽  
Decisive Importance ◽  
Flexible Pressure Sensors ◽  
Regenerated Cellulose Fibres

The design of flexible sensors which can be incorporated in textile structures is of decisive importance for the future development of wearables. In addition to their technical functionality, the materials chosen to construct the sensor should be nontoxic, affordable, and compatible with future recycling. Conductive fibres were produced by incorporation of carbon black into regenerated cellulose fibres. By incorporation of 23 wt.% and 27 wt.% carbon black, the surface resistance of the fibres reduced from 1.3 × 1010 Ω·cm for standard viscose fibres to 2.7 × 103 and 475 Ω·cm, respectively. Fibre tenacity reduced to 30–50% of a standard viscose; however, it was sufficient to allow processing of the material in standard textile operations. A fibre blend of the conductive viscose fibres with polyester fibres was used to produce a needle-punched nonwoven material with piezo-electric properties, which was used as a pressure sensor in the very low pressure range of 400–1000 Pa. The durability of the sensor was demonstrated in repetitive load/relaxation cycles. As a regenerated cellulose fibre, the carbon-black-incorporated cellulose fibre is compatible with standard textile processing operations and, thus, will be of high interest as a functional element in future wearables.

Immunolocalization of fimbrial epitopes in thin sections of Microbotryum violaceum

1997 ◽  
Vol 43 (2) ◽  
pp. 136-142 ◽  
Author(s):  
Martina Celerin ◽  
Alan W. Day ◽  
Ronald J. Smith ◽  
David E. Laudenbach
Keyword(s):  
Extracellular Matrix ◽  
Cell Wall ◽  
Plasma Membranes ◽  
Microbotryum Violaceum ◽  
Thin Sections ◽  
Present Evidence ◽  
Biochemical Analyses ◽  
Protein Moiety ◽  
Peripheral Cytoplasm

Fungal fimbriae are long (0.5–20 μm), narrow (7 nm) surface appendages that have been observed on most members of the Mycota. Biochemical analyses have determined that fimbriae from Microbotryum violaceum are composed of 74-kDa glycoproteinaceous subunits in which the protein moiety is fungal collagen. We present evidence for the localization of fimbrial subunits prior to their exportation from the cell. We term these internal, likely nonpolymerized fimbriae "pro-fimbriae" and demonstrate the location of the reserves within the peripheral cytoplasm. Also, we show that fimbriae may not traverse the cell wall as previously believed, but may instead originate from within the outer lamella of the cell wall, possibly being anchored to the cell wall via other molecules. This model is analogous to the animal extracellular matrix arrangement in which collagens are anchored to plasma membranes via other proteins such as fibronectin.Key words: fungus, immunolocalization, fimbriae, Microbotryum, Ustilago.

Leaf and stem nutritive value of timothy grown with varying N nutrition in spring and summer

1999 ◽  
Vol 79 (2) ◽  
pp. 223-229 ◽  
Author(s):  
G. Bélanger ◽  
R. E. McQueen
Keyword(s):  
Cell Wall ◽  
Nutritive Value ◽  
Nitrogen Deficiency ◽  
Phleum Pratense ◽  
Shoot Biomass ◽  
Negative Effect ◽  
N Deficiency ◽  
Rate Of Decline ◽  
Phleum Pratense L

Nitrogen fertilization is known to have a limited effect on the digestibility of grasses. In a previous paper, however, we reported that N deficiency increased the proportion of leaves in the shoot biomass, and hence, indirectly increased the digestibility of timothy (Phleum pratense L). This was mitigated by the direct negative effect of N deficiency on the digestibility of leaves or stems or both early in the regrowth. The objective of this study was to determine the direct effect of N deficiency on three parameters of nutritive value of leaves and stems of timothy cv. Champ. The evolution of leaf and stem in vitro true digestibility (IVTD), in vitro cell wall digestibility (IVCWD), and neutral detergent fiber (NDF) concentration of field-grown timothy fertilized with four rates of N was studied during a spring and summer regrowth cycle by sampling at weekly intervals. The rate of decline in leaf nutritive value in spring was greater than that in summer, and was less than the rate of decline in stem nutritive value during spring. Nitrogen deficiency consistently increased the NDF concentration of leaves but had a lesser effect on the NDF concentration of stems. Nitrogen deficiency decreased leaf IVCWD when the leaf-to-weight ratio (LWR) was high early in the spring and summer regrowth cycles. At the end of regrowth when LWR values were low, leaf IVCWD was greatest when no N was applied. As a result, the negative effect of N deficiency on the leaf IVTD during the early part of the spring and summer regrowth cycles diminished as the regrowth cycles progressed. Nitrogen deficiency had a limited effect on stem IVCWD. We concluded that the direct negative effect of N deficiency on the digestibility of the timothy shoot biomass can be attributed primarily to its effect on the NDF concentration and cell wall digestibility of leaves. Key words: Phleum pratense L., grasses, digestibility, cell wall, nitrogen

scholarly journals Plasmodiophora brassicae in its environment-effects of temperature and light on resting spore survival in soil

2019 ◽  
Author(s):  
Kher Zahr ◽  
Alian Sarkes ◽  
Yalong Yang ◽  
Qixing Zhou ◽  
David Feindel ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Uv Light ◽  
Quantitative Polymerase Chain Reaction ◽  
Soil Surface ◽  
Spore Viability ◽  
Resting Spore ◽  
Infected Root ◽  
Resting Spores ◽  
Negative Effect ◽  
C 30

AbstractClubroot caused by Plasmodiophora brassicae is an important disease on cruciferous crops worldwide. Management of clubroot has been challenging, due largely to the millions of resting spores produced within an infected root that can survive dormant in the soil for many years. This study was conducted to investigate some of the environmental conditions that may affect the survival of resting spores in the soil. Soil samples containing clubroot resting spores (1 × 107 spores g-1 soil) were stored at various temperatures for two years. Additionally, other samples were buried in soil, or kept on the soil surface in the field. The content of P. brassicae DNA and the numbers of viable spores in the samples were assessed by quantitative polymerase chain reaction (qPCR) and pathogenicity bioassays, respectively. The results indicated that 4°C, 20°C and being buried in the soil were better conditions for spore survival than were −20°C, 30°C and at the soil surface. Most of the spores kept on the soil surface were killed, suggesting the negative effect of light on spore viability. Additional experiments confirmed that ultraviolet (UV) light contributed a large negative effect on spore viability as lower pathogenicity and less DNA content were observed from the 2-and 3-hour UV light treated spores compared to the untreated control. Finally, this work demonstrated that DNA-based quantification methods such as qPCR can be poor predictors of P. brassicae disease potential due to the presence and persistence of DNA from dead spores.

scholarly journals Plasmodiophora brassicae in its environment-effects of temperature and light on resting spore survival in soil.

2021 ◽  
Author(s):  
Kher Zahr ◽  
Alian Sarkes ◽  
Yalong Yang ◽  
Hafiz Ahmed ◽  
Qixing Zhou ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Uv Light ◽  
Quantitative Polymerase Chain Reaction ◽  
Soil Surface ◽  
Spore Viability ◽  
Resting Spore ◽  
Infected Root ◽  
Resting Spores ◽  
Negative Effect ◽  
C 30

Clubroot caused by Plasmodiophora brassicae is an important disease on cruciferous crops worldwide. Management of clubroot is challenging, largely due to the millions of resting spores produced within an infected root that can survive dormant in the soil for many years. This study was conducted to investigate some of the environmental conditions that may affect the survival of resting spores in the soil. Soil samples containing clubroot resting spores (1 × 107 spores/g soil) were stored at various temperatures for two years. Additionally, other samples were buried in soil, or kept on the soil surface in the field. The content of P. brassicae DNA and the numbers of viable spores in the samples were assessed by quantitative polymerase chain reaction (qPCR) and pathogenicity bioassays, respectively. The results indicated that 4°C, 20°C, and being buried in the soil were more conductive conditions for spore survival compared to -20°C, 30°C, and at the soil surface. 99.99% of the spores kept on the soil surface were non-viable, suggesting a negative effect of light on spore viability. Additional experiments confirmed the negative effect of UV light on spore viability as spores receiving 2- and 3-hour UV light exhibited lower disease potential and contained less DNA content compared to the untreated control. Finally, this work confirmed that DNA-based quantification methods such as qPCR can be poor predictors of P. brassicae disease potential due to the presence and persistence of DNA from dead spores.

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