Gradients of cell wall nano-mechanical properties along and across elongating primary roots of maize

2020 ◽  
Author(s):  
Anna Petrova ◽  
Tatyana Gorshkova ◽  
Liudmila Kozlova
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Cell Walls ◽  
Computational Simulation ◽  
Turgor Pressure ◽  
Apical Part ◽  
Elastic Response ◽  
Elongation Zone ◽  
Inner Cortex

Abstract To test the hypothesis that particular tissues can control root growth, we analysed mechanical properties of cell walls belonging to different tissues of the apical part of maize root using atomic-force microscopy. The dynamics of properties during elongation growth were characterised in four consecutive zones of the root. The extensive immunochemical characterization and quantification were used to establish the polysaccharide motif(s) related to changes in cell wall mechanics. Cell transition from division to elongation was coupled to the decrease in the elasticity modulus in all root tissues. Low values of moduli were retained in the elongation zone and increased in late elongation zone. No relationship between the immunolabelling pattern and mechanical properties of the cell walls was revealed. When measured values of elasticity moduli and turgor pressure were used in the computational simulation, this resulted in an elastic response of modelled root and the distribution of stress and strain similar with those observed in vivo. In all analysed root zones, cell walls of the inner cortex displayed moduli of elasticity that were maximal or comparable to the maximal values among all tissues. Thus, we propose that the inner cortex serves as a growth-limiting tissue in maize roots.

scholarly journals Protocol for mapping the spatial variability in cell wall mechanical bending behavior in living leaf pavement cells

2021 ◽  
Author(s):  
Wenlong Li ◽  
Sedighe Keynia ◽  
Samuel A. Belteton ◽  
Faezeh Afshar-Hatam ◽  
Daniel B. Szymanski ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Elastic Modulus ◽  
Cell Walls ◽  
Turgor Pressure ◽  
Plant Cell Walls ◽  
Pavement Cells ◽  
Elastic Bending ◽  
Entire Thickness ◽  
Bending Behavior

AbstractAn integrated, experimental-computational approach is presented to analyze the variation of elastic bending behavior in the primary cell wall of living Arabidopsis thaliana pavement cells and to measure turgor pressure in the cells quantitatively under different osmotic conditions. Mechanical properties, size and geometry of cells and internal turgor pressure greatly influence their morphogenesis. Computational models of plant morphogenesis require values for wall elastic modulus and turgor pressure but very few experiments were designed to validate the results using measurements that deform the entire thickness of the cell wall. Because new wall material is deposited from inside the cell, full-thickness deformations are needed to quantify relevant changes associated with cell development. The approach here uses laser scanning confocal microscopy to measure the three-dimensional geometry of a single pavement cell, and indentation experiments equipped with high magnification objective lens to probe the local mechanical responses across the same cell wall. These experimental results are matched iteratively using a finite element model of the experiment to determine the local mechanical properties, turgor pressure, and cell height. The resulting modulus distribution along the periclinal wall is shown to be nonuniform. These results are consistent with the characteristics of plant cell walls which have a heterogeneous organization. This research and the resulting model will provide a reference for future work associated with the heterogeneity and anisotropy of mechanical properties of plant cell walls in order to understand morphogenesis of the primary cell walls during growth and to predict quantitatively the magnitudes/directions of cell wall forces.One sentence summaryThe distribution of elastic modulus of the periclinal cell walls of livingArabidopsis epidermis is nonuniform as measured by bending the entire thickness of the wall.HighlightsExperimental characterization of the spatial distribution of elastic bending behavior across the periclinal wallQuantification of the turgor pressure of the living plant epidermal cells validated with osmotic treatmentsQuantification of the effect of cell geometry on the measured mechanical responseGraphical abstract

scholarly journals An imaged-based inverse finite element method to determine in-vivo mechanical properties of the human trabecular meshwork

2017 ◽  
Vol 1 (3) ◽  
pp. 100-111
Author(s):  
Anup D. Pant ◽  
Larry Kagemann ◽  
Joel S. Schuman ◽  
Ian A. Sigal ◽  
Rouzbeh Amini
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Shear Modulus ◽  
Trabecular Meshwork ◽  
Computational Simulation ◽  
Optimization Technique ◽  
Schlemm’S Canal ◽  
Aqueous Humor Outflow ◽  
Schlemm's Canal

Aim/Purpose: Previous studies have shown that the trabecular meshwork (TM) is mechanically stiffer in glaucomatous eyes as compared to normal eyes. It is believed that elevated TM stiffness increases resistance to the aqueous humor outflow, producing increased intraocular pressure (IOP).It would be advantageous to measure TM mechanical properties in vivo, as these properties are believed to play an important role in the pathophysiology of glaucoma and could be useful for identifying potential risk factors.  The purpose of this study was to develop a method to estimate in-vivo TM mechanical properties using clinically available exams and computer simulations.Design: Inverse finite element simulationMethods: A finite element model of the TM was constructed from optical coherence tomography (OCT) images of a healthy volunteer before and during IOP elevation. An axisymmetric model of the TM was then constructed. Images of the TM at a baseline IOP level of 11, and elevated level of 23 mmHg were treated as the undeformed and deformed configurations, respectively. An inverse modeling technique was subsequently used to estimate the TM shear modulus (G). An optimization technique was used to find the shear modulus that minimized the difference between Schlemm’s canal area in the in-vivo images and simulations.Results: Upon completion of inverse finite element modeling, the simulated area of the Schlemm’s canal changed from 8,889 μm2 to 2,088 μm2, similar to the experimentally measured areal change of the canal (from 8,889 μm2 to 2,100 μm2). The calculated value of shear modulus was found to be 1.93 kPa,  (implying an approximate Young’s modulus of 5.75 kPa), which is consistent with previous ex-vivo measurements.Conclusion: The combined imaging and computational simulation technique provides a unique approach to calculate the mechanical properties of the TM in vivo without any surgical intervention. Quantification of such mechanical properties will help us examine the mechanistic role of TM biomechanics in the regulation of IOP in healthy and glaucomatous eyes. 

scholarly journals Changes in cell ultrastructure and morphology of Arabidopsis thaliana roots after coumarins treatment

2014 ◽  
Vol 70 (3) ◽  
pp. 187-198
Author(s):  
Ewa Kupidłowska
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Walls ◽  
Root Elongation ◽  
Inhibitory Effect ◽  
Cell Ultrastructure ◽  
Radial Expansion ◽  
Elongation Zone ◽  
Cortical Cells ◽  
Mother Cell Wall

The ultrastructure and morphology of roots treated with coumarin and umbelliferone as well as the reversibility of the coumarins effects caused by exogenous GA, were studied in <em>Arabidopsis thaliana</em>. Both coumarins suppressed root elongation and appreciably stimulated radial expansion of epidermal and cortical cells in the upper part of the meristem and in the elongation zone. The gibberellic acid applied simultaneously with coumarins decreased their inhibitory effect on root elongation and reduced cells swelling.Microscopic observation showed intensive vacuolization of cells and abnormalities in the structure of the Golgi stacks and the nuclear envelope. The detection of active acid phosphatase in the cytosol of swollen cells indicated increased membrane permeability. Significant abnormalities of newly formed cell walls, e.g. the discontinuity of cellulose layer, uncorrect position of walls and the lack of their bonds with the mother cell wall suggest that coumarins affected the cytoskeleton.

scholarly journals Investigation of the Mechanical Properties of Flax Cell Walls during Plant Development: The Relation between Performance and Cell Wall Structure

Fibers ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 6 ◽  
Author(s):  
Camille Goudenhooft ◽  
David Siniscalco ◽  
Olivier Arnould ◽  
Alain Bourmaud ◽  
Olivier Sire ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Plant Development ◽  
Cell Walls ◽  
Cell Wall Structure ◽  
Wall Structure

scholarly journals Structure and Biomechanics during Xylem Vessel Transdifferentiation in Arabidopsis thaliana

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1715
Author(s):  
Eleftheria Roumeli ◽  
Leah Ginsberg ◽  
Robin McDonald ◽  
Giada Spigolon ◽  
Rodinde Hendrickx ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Walls ◽  
Turgor Pressure ◽  
Plant Cells ◽  
Building Blocks ◽  
Xylem Vessel ◽  
Primary Cell Wall ◽  
Individual Plant ◽  
Vessel Elements

Individual plant cells are the building blocks for all plantae and artificially constructed plant biomaterials, like biocomposites. Secondary cell walls (SCWs) are a key component for mediating mechanical strength and stiffness in both living vascular plants and biocomposite materials. In this paper, we study the structure and biomechanics of cultured plant cells during the cellular developmental stages associated with SCW formation. We use a model culture system that induces transdifferentiation of Arabidopsis thaliana cells to xylem vessel elements, upon treatment with dexamethasone (DEX). We group the transdifferentiation process into three distinct stages, based on morphological observations of the cell walls. The first stage includes cells with only a primary cell wall (PCW), the second covers cells that have formed a SCW, and the third stage includes cells with a ruptured tonoplast and partially or fully degraded PCW. We adopt a multi-scale approach to study the mechanical properties of cells in these three stages. We perform large-scale indentations with a micro-compression system in three different osmotic conditions. Atomic force microscopy (AFM) nanoscale indentations in water allow us to isolate the cell wall response. We propose a spring-based model to deconvolve the competing stiffness contributions from turgor pressure, PCW, SCW and cytoplasm in the stiffness of differentiating cells. Prior to triggering differentiation, cells in hypotonic pressure conditions are significantly stiffer than cells in isotonic or hypertonic conditions, highlighting the dominant role of turgor pressure. Plasmolyzed cells with a SCW reach similar levels of stiffness as cells with maximum turgor pressure. The stiffness of the PCW in all of these conditions is lower than the stiffness of the fully-formed SCW. Our results provide the first experimental characterization of the mechanics of SCW formation at single cell level.

scholarly journals Putative Role of β-1,3 Glucans in Candida albicans Biofilm Resistance

2006 ◽  
Vol 51 (2) ◽  
pp. 510-520 ◽  
Author(s):  
Jeniel Nett ◽  
Leslie Lincoln ◽  
Karen Marchillo ◽  
Randall Massey ◽  
Kathleen Holoyda ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Cell Viability ◽  
Amphotericin B ◽  
Cell Walls ◽  
Positive Impact ◽  
Indirect Evidence ◽  
Phenotypic Properties

ABSTRACT Biofilms are microbial communities, embedded in a polymeric matrix, growing attached to a surface. Nearly all device-associated infections involve growth in the biofilm life style. Biofilm communities have characteristic architecture and distinct phenotypic properties. The most clinically important phenotype involves extraordinary resistance to antimicrobial therapy, making biofilm infections very difficulty to cure without device removal. The current studies examine drug resistance in Candida albicans biofilms. Similar to previous reports, we observed marked fluconazole and amphotericin B resistance in a C. albicans biofilm both in vitro and in vivo. We identified biofilm-associated cell wall architectural changes and increased β-1,3 glucan content in C. albicans cell walls from a biofilm compared to planktonic organisms. Elevated β-1,3 glucan levels were also found in the surrounding biofilm milieu and as part of the matrix both from in vitro and in vivo biofilm models. We thus investigated the possible contribution of β-glucans to antimicrobial resistance in Candida albicans biofilms. Initial studies examined the ability of cell wall and cell supernatant from biofilm and planktonic C. albicans to bind fluconazole. The cell walls from both environmental conditions bound fluconazole; however, four- to fivefold more compound was bound to the biofilm cell walls. Culture supernatant from the biofilm, but not planktonic cells, bound a measurable amount of this antifungal agent. We next investigated the effect of enzymatic modification of β-1,3 glucans on biofilm cell viability and the susceptibility of biofilm cells to fluconazole and amphotericin B. We observed a dose-dependent killing of in vitro biofilm cells in the presence of three different β-glucanase preparations. These same concentrations had no impact on planktonic cell viability. β-1,3 Glucanase markedly enhanced the activity of both fluconazole and amphotericin B. These observations were corroborated with an in vivo biofilm model. Exogenous biofilm matrix and commercial β-1,3 glucan reduced the activity of fluconazole against planktonic C. albicans in vitro. In sum, the current investigation identified glucan changes associated with C. albicans biofilm cells, demonstrated preferential binding of these biofilm cell components to antifungals, and showed a positive impact of the modification of biofilm β-1,3 glucans on drug susceptibility. These results provide indirect evidence suggesting a role for glucans in biofilm resistance and present a strong rationale for further molecular dissection of this resistance mechanism to identify new drug targets to treat biofilm infections.

scholarly journals Multi-Scale Evaluation of the Effect of Phenol Formaldehyde Resin Impregnation on the Dimensional Stability and Mechanical Properties of Pinus Massoniana Lamb.

Forests ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 646 ◽  
Author(s):  
Wang ◽  
Chen ◽  
Xie ◽  
Cai ◽  
Yuan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Dimensional Stability ◽  
Cell Walls ◽  
Phenol Formaldehyde ◽  
Pinus Massoniana ◽  
Swelling Properties ◽  
Masson Pine ◽  
Pine Wood ◽  
Pinus Massoniana Lamb

The local chemistry and mechanics of the control and phenol formaldehyde (PF) resin modified wood cell walls were analyzed to illustrate the modification mechanism of wood. Masson pine (Pinus massoniana Lamb.) is most widely distributed in the subtropical regions of China. However, the dimensional instability and low strength of the wood limits its use. Thus, the wood was modified by PF resin at concentrations of 15%, 20%, 25%, and 30%, respectively. The density, surface morphology, chemical structure, cell wall mechanics, shrinking and swelling properties, and macro-mechanical properties of Masson pine wood were analyzed to evaluate the modification effectiveness. The morphology and Raman spectra changes indicated that PF resin not only filled in the cell lumens, but also penetrated into cell walls and interacted with cell wall polymers. The filling and diffusing of resin in wood resulted in improved dimensional stability, such as lower swelling and shrinking coefficients, an increase in the elastic modulus (Er) and hardness (H) of wood cell walls, the hardness of the transverse section and compressive strength of the wood. Both the dimensional stability and mechanical properties improved as the PF concentration increased to 20%; that is, a PF concentration of 20% may be preferred to modify Masson pine wood.

scholarly journals Di-isodityrosine, a novel tetrametric derivative of tyrosine in plant cell wall proteins: a new potential cross-link

1996 ◽  
Vol 315 (1) ◽  
pp. 323-327 ◽  
Author(s):  
Jeffrey D. BRADY ◽  
Ian H. SADLER ◽  
Stephen C. FRY
Keyword(s):  
Cell Culture ◽  
Cell Wall ◽  
Amino Acid ◽  
Plant Cell ◽  
Cell Walls ◽  
Plant Cell Wall ◽  
Cell Wall Proteins ◽  
Cross Link ◽  
Nmr Spectrometry

A novel amino acid, di-isodityrosine, has been isolated from hydrolysates of cell walls of tomato cell culture. Analysis by UV spectrometry, partial derivatization with 2,4-dinitrofluorobenzene and mass and NMR spectrometry show that the compound is composed to two molecules of isodityrosine, joined by a biphenyl linkage. The possible reactions involved in the formation of this molecule in vivo are discussed, as is the possibility that it could form an interpolypeptide linkage between cell wall proteins such as extensin, and hence aid in the insolubilization of the protein in the wall.

scholarly journals The Implication of Benzene–Ethanol Extractive on Mechanical Properties of Waterborne Coating and Wood Cell Wall by Nanoindentation

Coatings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 449 ◽  
Author(s):  
Yan Wu ◽  
Yingchun Sun ◽  
Feng Yang ◽  
Haiqiao Zhang ◽  
Yajing Wang
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Wood Surface ◽  
Cell Walls ◽  
Wood Cell Wall ◽  
Coating Layer ◽  
Waterborne Coating ◽  
Average Value ◽  
Wood Surfaces ◽  
Extraction Treatment

The waterborne coating uses water as its solvent, which will partially dissolve wood extractives when it is applied to wood surfaces. This influences both the coating curing process and the mechanical properties of the cured coating. To investigate these influences, the mechanical properties of waterborne polyacrylic coating on control and extractive-free wood surfaces were investigated by nanoindentation. Reductions to elastic modulus (Er) and hardness (H) of the coating layer was observed in the wood cell walls adjacent to or away from coating layers. Extraction treatment resulted in significant decrease of the Er and H of the coating layer on extractive-free wood surface comparing with control wood, but the values slightly increased for extractive-free wood cell walls compared to a control. Er and H of coating in wood cell lumen were higher than the average value of coating layer on wood surface in both the control and extractive-free wood. The Er of wood cell wall without coating filled in lumen was significantly higher than those of filling with coating. However, there was no distinct difference of H. The Er and H of CCML in extractive-free wood were 15% and 6% lower than those in control ones, respectively.

Comparing Mechanical Properties of Normal and Compression Wood in Norway Spruce: The Role of Lignin in Compression Parallel to the Grain

Holzforschung ◽  
2002 ◽  
Vol 56 (4) ◽  
pp. 395-401 ◽  
Author(s):  
W. Gindl
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cell Wall ◽  
Mechanical Testing ◽  
Cell Walls ◽  
Compression Wood ◽  
Lignin Content ◽  
Microfibril Angle ◽  
Compression Failure

Summary Cell-wall lignin content and composition, as well as microfibril angle of normal and compression wood samples were determined prior to mechanical testing in compression parallel to the grain. No effect of increased lignin content on the Young's modulus in compression wood was discernible because of the dominating influence of microfibril angle. In contrast, compressive strength of compression wood was not negatively affected by the high microfibril angle. It is proposed that the observed high lignification in compression wood increases the resistance of the cell walls to compression failure. An increased percentage of p-hydroxyphenylpropane units observed in compression wood lignin may also contribute to the comparably high compressive strength of compression wood.

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