scholarly journals Paws, pads and plants: the enhanced elasticity of cell-filled load-bearing structures

2015 ◽  
Vol 471 (2178) ◽  
pp. 20150107 ◽  
Author(s):  
L. Angela Mihai ◽  
Khulud Alayyash ◽  
Alain Goriely
Keyword(s):  
Cell Wall ◽  
Elastic Modulus ◽  
Cell Walls ◽  
Large Strain ◽  
Strain Energy Function ◽  
Material Design ◽  
Wall Material ◽  
Solid Core ◽  
Internal Cell ◽  
Wide Range

Paws, fat pads and plants share a remarkable structure made up of closed cells with elastic cell walls capable of supporting large loads and deformations. A key challenge is to understand how the function of these structures is enhanced by their geometric and material design. To do so, we compare different elastic models operating in large strain deformation when the cells are empty or filled with an incompressible liquid or solid core. We demonstrate theoretically, for three different cell geometries, that the elastic modulus in a direction associated with the change of curvature in the cell wall (i) is greater when the cell is filled; (ii) increases as the internal cell pressure increases; and (iii) increases also as the thickness of the cell wall increases or when the wall is multi-layer. As these results do not depend on the choice of the strain-energy function describing the cell-wall material, they are valid for a wide range of structures made from different elastic materials. For multiple cells deforming together due to external forces, the increase in elastic modulus of the cell walls under increasing core pressure is found numerically throughout the structure.

Synchrotron infrared microspectroscopy reveals the response of Sphagnum cell wall material to its aqueous chemical environment

2018 ◽  
Vol 15 (8) ◽  
pp. 513
Author(s):  
Ewen Silvester ◽  
Annaleise R. Klein ◽  
Kerry L. Whitworth ◽  
Ljiljana Puskar ◽  
Mark J. Tobin
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Chemical Environment ◽  
Wall Material ◽  
Organic Soils ◽  
Cell Wall Material ◽  
Acid Base ◽  
Widespread Species ◽  
Flowing Liquid ◽  
Infrared Microspectroscopy

Environmental contextSphagnum moss is a widespread species in peatlands globally and responsible for a large fraction of carbon storage in these systems. We used synchrotron infrared microspectroscopy to characterise the acid-base properties of Sphagnum moss and the conditions under which calcium uptake can occur (essential for plant tissue integrity). The work allows a chemical model for Sphagnum distribution in the landscape to be proposed. AbstractSphagnum is one the major moss types responsible for the deposition of organic soils in peatland systems. The cell walls of this moss have a high proportion of carboxylated polysaccharides (polygalacturonic acids), which act as ion exchangers and are likely to be important for the structural integrity of the cell walls. We used synchrotron light source infrared microspectroscopy to characterise the acid-base and calcium complexation properties of the cell walls of Sphagnum cristatum stems, using freshly sectioned tissue confined in a flowing liquid cell with both normal water and D2O media. The Fourier transform infrared spectra of acid and base forms are consistent with those expected for protonated and deprotonated aliphatic carboxylic acids (such as uronic acids). Spectral deconvolution shows that the dominant aliphatic carboxylic groups in this material behave as a monoprotic acid (pKa=4.97–6.04). The cell wall material shows a high affinity for calcium, with a binding constant (K) in the range 103.9–104.7 (1:1 complex). The chemical complexation model developed here allows for the prediction of the chemical environment (e.g. pH, ionic content) under which Ca2+ uptake can occur, and provides an improved understanding for the observed distribution of Sphagnum in the landscape.

Étude cytochimique ultrastructurale de la dégradation des lignines dans les résidus pariétaux de bois d'épicéa et de peuplier par le Reticulitermes lucifugus var. santonensis (Rhinotermitidae, Isoptera)

1992 ◽  
Vol 70 (5) ◽  
pp. 933-941 ◽  
Author(s):  
E. Garnier-Sillam ◽  
I. Grech ◽  
Y. Czaninski ◽  
M.-T. Tollier ◽  
B. Monties
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Periodic Acid ◽  
Mechanical Action ◽  
Free Cell ◽  
Uranyl Acetate ◽  
Picea Sitchensis ◽  
Wall Material ◽  
Before And After ◽  
Acetate Lead

Free cell-wall residues were prepared by extracting wood samples of spruce (Populus euramericana cv. Fidzi Pauley) and poplar (Picea sitchensis). These species were chosen for their lignin types: guaiacyl in spruce and guaiacyl–syringyl in poplar. The parietal residues obtained were used as the sole food for the xylophagous termite Reticulitermes lucifugus var. santonensis and were compared before and after ingestion and transit in the digestive tracts. Differences due to the mechanical action of the gizzard were found in association with chemical changes. Polysaccharides were unmasked after digestion and could clearly be observed after reaction with periodic acid – thiocarbohydrazide – silver proteinate. A fibrillary meshwork was also observed inside the lignified cell walls. Biodegradation of cell wall material was particularly clear in poplar where granules formed an electron-dense plasma when uranyl acetate – lead citrate or periodic acid – thiocarbohydrazide – silver proteinate was used as a contrast medium. A selective biodegradation of syringyl monomers in poplar parietal residues was indicated by thioacidolysis but requires confirmation. Breakdown of lignified cell walls begins with a biodegradation of the lignin network associated with or followed by the digestion of polysaccharides. Syringyl-rich lignin fractions seemed to break down faster. Whether the enzymic pathway leading to ligninolysis originates from the termite digestive cells or from the endosymbionts present in their digestive tract lumen remains to be defined. Key words: Isoptera, Reticulitermes lucifugus var. santonensis, wood, lignin, spruce, poplar.

Ultrastructure des parois de cerises Bigarreau Burlat de textures différentes au cours de la maturation

1996 ◽  
Vol 74 (12) ◽  
pp. 1974-1981 ◽  
Author(s):  
C. Batisse ◽  
P. J. Coulomb ◽  
C. Coulomb ◽  
M. Buret
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Middle Lamella ◽  
Primary Cell ◽  
Wall Material ◽  
Cell Wall Degradation ◽  
Composition And Structure ◽  
Cell Wall Texture ◽  
Synthesis And Degradation ◽  
Soft Fruits

The changes in texture of fruits during ripening are linked to cell wall degradation involving synthesis and degradation of polymers. An increase in pectin solubility leads to cell sliding and an elastic aspect of tissues. The biochemical cell wall process differs between soft and crisp fruits originating from a same cultivar but cultivated under different agroclimatic conditions. Although the proportions of cell wall material are similar, the composition and structure of the two cell walls are very different at maturity. A solubilization of the middle lamella and a restructuration of the primary cell walls arising from the cells separation is observed in crisp fruits. In contrast, the middle lamella of the soft fruits is better preserved and the primary cell walls are thin and show degradation bags delimited by residual membrane formations. In addition, the macroendocytosis process by endosome individualization is more important in soft fruits. In conclusion, the fruit texture depends on the extent of the links between cell wall polymers. Keywords: cherry, cell wall, texture, ultrastructural study.

THE EFFECT OF PENICILLIN ON THE STRUCTURE OF STAPHYLOCOCCAL CELL WALLS

1959 ◽  
Vol 5 (6) ◽  
pp. 641-648 ◽  
Author(s):  
R. G. E. Murray ◽  
W. H. Francombe ◽  
B. H. Mayall
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Untreated Control ◽  
Osmium Tetroxide ◽  
Wall Material ◽  
Cell Wall Material ◽  
Cell Wall Synthesis ◽  
Cell Wall Component ◽  
A Cell ◽  
Resistant Strains

Cultures of sensitive stains of Staphylococcus aureus were fixed with osmium tetroxide after 1–5 hours' exposure to various does of pencillin and were embedded in methacrylate for sectioning and electron microscopy. They were compared with untreated, control cultures. The contrast of the cell wall material was untreated, control cultures. The contrast of the cell wall material was increased, by cutting the section of lanthanum nitrate.The cells increased in size and the surrounding cell wall was thinner than normal. The main lesions appeared in the developing cell wall septa, which showed a loss in density and gross irregularity of shape. Some questionable inclusions were seen in the cytoplasm. Lysis was prevented in a medium containing 0.3 M sucrose and the stable spheroplasts retained a recognizable cell wall after 24 hours' exposure to penicillin. However, the septa could not be demonstrated in the cells treated in sucrose medium.Two resistant strains were exposed to penicillin. In one, the cells showed no morphological effects; in the other, there was temporary damage to the cell septa with complete recovery.The observations support the hypothesis that penicillin interferes with the synthesis of a cell wall component and indicate that the main point of cell wall synthesis is at the site of septum formation.

scholarly journals (472) Yeast Expressed Tomato β-Galactosidases 1, 4, and 5 Have Activity against Synthetic and Plant-derived Cell Wall Substrates

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1092B-1092 ◽  
Author(s):  
Megumi Ishimaru ◽  
David L. Smith ◽  
Kenneth C. Gross
Keyword(s):  
Cell Wall ◽  
Tomato Fruit ◽  
Wall Material ◽  
Wall Structure ◽  
Fruit Softening ◽  
Pectic Polysaccharides ◽  
Wide Range ◽  
Fruit Pericarp ◽  
Galactosyl Residues

Fruit softening occurs by several mechanisms, including modifications of cell wall structure by wall degrading enzymes. The most prominent change in tomato fruit pericarp wall composition is the loss of galactosyl residues throughout development and especially during ripening. In order to understand the role of galactosyl turnover in fruit softening, we successfully produced three recombinant tomato β-galactosidase/exo-galactanase (TBG) fusion proteins in yeast. TBG1, 4 and 5 enzyme properties and substrate specificities were assessed. Optimum pH of TBG1, 4 and 5 was 5.0, 4.0, and 4.5 and optimum temperature was 40∼50, 40, and 40 °C, respectively. The K ms for TBG1, 4 and 5 were 7.99, 0.09, and 2.42 mm, respectively, using p-nitrophenyl-β-D-galactopyranoside as substrate. Using synthetic and plant-derived substrates, TBG1 and 5 released galactosyl residues from 1 → 4 linkages. TBG4 released galactosyl residues from a wide range of plant-derived oligosaccharides and polysaccharides. Using tomato fruit cell wall material, TBG1, TBG4 and TBG5 released galactosyl residues from a variety of fruit stages and cell wall fractions. TBG4 released the most galactosyl residues from the ASP fraction and especially the ASP fraction from fruit at the turning stage. Interestingly, even though walls from Turning fruit stage contain less total galactosyl residues than at the Mature Green stage, TBG4 released 3–4 fold more galactose from the CSP and ASP fractions from Turning fruit. These results suggest that changes in structure of wall pectic polysaccharides leading up to the Turning stage may cause the wall to become more susceptible to hydrolysis by the TBG4 product.

scholarly journals Mutations in a single signaling pathway allow growth on a different solvent than water

2019 ◽  
Author(s):  
Caroline Kampmeyer ◽  
Jens V. Johansen ◽  
Christian Holmberg ◽  
Magnus Karlson ◽  
Sarah K. Gersing ◽  
...  
Keyword(s):  
Cell Wall ◽  
Morphological Changes ◽  
Biological Effects ◽  
Control Cell ◽  
Wall Material ◽  
Cell Integrity ◽  
Prolonged Incubation ◽  
Altered Glucose ◽  
Wide Range ◽  
The Impact

AbstractSince life is completely dependent on water, it is difficult to gauge the impact of solvent change. To analyze the role of water as a solvent in biology, we replaced water with heavy water (D2O), and investigated the biological effects by a wide range of techniques, using the fission yeast Schizosaccharomyces pombe as model organism. We show that high concentrations of D2O lead to altered glucose metabolism, growth retardation, and inhibition of meiosis. However, mitosis and overall cell viability were only slightly affected. After prolonged incubation in D2O, cells displayed gross morphological changes, thickened cell walls as well as aberrant septa and cytoskeletal organization. RNA sequencing revealed that D2O causes a strong downregulation of most tRNAs and triggers activation of the general stress response pathway. Genetic screens identified several D2O sensitive mutants, while mutants compromised in the cell integrity pathway, including the protein kinase genes pmk1, mkh1, pek1 and pck2, that control cell wall biogenesis, were more tolerant to D2O. We speculate that D2O affects the phospholipid membrane or cell wall glycans causing an activation of the cell integrity pathway. In conclusion, the effects of solvent replacement are pleiotropic but the D2O-triggered activation of the cell integrity pathway and subsequent increased deposition of cell wall material and septation problems appear most critical for the cell growth defects.

Cellular Characteristics of Dinitroaniline Herbicide-Resistant Goosegrass (Eleusine indica)

Weed Science ◽  
1991 ◽  
Vol 39 (1) ◽  
pp. 6-12 ◽  
Author(s):  
Bernal E. Valverde ◽  
Arnold P. Appleby ◽  
Steven R. Radosevich ◽  
Alfred Soeldner
Keyword(s):  
North Carolina ◽  
Cell Wall ◽  
South Carolina ◽  
Cell Walls ◽  
Primary Root ◽  
Wall Material ◽  
Root Cells ◽  
Eleusine Indica ◽  
Herbicide Resistant ◽  
Transmission Electron

Primary root cells from five dinitroaniline-resistant (R) and three susceptible (S) goosegrass biotypes from North Carolina and South Carolina were observed by transmission electron microscopy to determine whether resistance was associated with changes in cell wall formation. Cell wall malformations were found in some cells from two of the R-biotypes and in one of the S-biotypes. Malformations consisted of partially deposited cell walls and the inclusion of cell wall material in the cytoplasm. Some of the affected cells also had abnormal, lobed nuclei and malformed mitochondria. There seems to be little or no correlation between dinitroaniline resistance and cell wall malformations.

Role of Golgi Apparatus in the Formation of Plant Slimes, Cuticles and Extraneous Wall Material

1974 ◽  
Vol 32 ◽  
pp. 86-87
Author(s):  
Hilton H. Mollenhauer
Keyword(s):  
Cell Wall ◽  
Golgi Apparatus ◽  
Cell Walls ◽  
Growth And Development ◽  
Characteristic Property ◽  
Plant Cells ◽  
Plant Biology ◽  
Wall Material ◽  
Wall Properties

Cell walls are fundamentally involved in many aspects of plant biology including the morphology, growth, and development of plant cells and the interactions between plant hosts and their pathogens. Intuitively, one can recognize that these wall properties result from the sum total of the various components of which the wall is composed and that there are classes of substances each of which impart a characteristic property to the cell wall.

Surface charge and morphogenesis of regular arrays of macromolecules on bacterial cell walls

1978 ◽  
Vol 36 (2) ◽  
pp. 346-347 ◽  
Author(s):  
U. B. Sleytr ◽  
G. P. Friers
Keyword(s):  
Cell Wall ◽  
Surface Charge ◽  
Bacterial Cell ◽  
Cell Walls ◽  
Surface Layers ◽  
Regular Surface ◽  
Wide Range ◽  
Freeze Etching ◽  
Regular Arrays ◽  
Peptidoglycan Layer

Regular arrays of macromolecules can be demonstrated on the surface of a wide range of bacteria by negative staining and freeze-etching techniques. The isolated subunits of the regular surface layers (S-layers) examined in this study have shown to consist of protein or glycoprotein and to possess the ability to assemble spontaneously under certain conditions to form regular arrays with the same dimensions as those seen on intact bacteria. In appropriate conditions the isolated subunits reattach to the cell wall from which they have been removed. Analysis of the orientation of the reconstituted S-layers have shown that the pattern of the regular arrays seem to be determined only by the directional bonds between the subunits and not by any order in the underlying (peptidoglycan) layer.

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