Force extension analysis of Avena coleoptile cell walls

Planta ◽  
1965 ◽  
Vol 66 (2) ◽  
pp. 126-134 ◽  
Author(s):  
Alfred C. Olson ◽  
James Bonner ◽  
D. James Morr�
Keyword(s):  
Cell Walls ◽  
Force Extension ◽  
Avena Coleoptile ◽  
Extension Analysis

THE ABSENCE OF ELASTIC DEFORMATION IN DRIED BENT CELLULOSE MICROFIBRILS IN PLANT CELL WALLS

1965 ◽  
Vol 43 (3) ◽  
pp. 339-343
Author(s):  
J. Ross Colvin
Keyword(s):  
Elastic Deformation ◽  
Plant Cell ◽  
Cell Walls ◽  
Cold Water ◽  
Hot Water ◽  
Cellulose Microfibrils ◽  
Plant Cell Walls ◽  
Avena Coleoptile ◽  
Parenchyma Cells ◽  
Embedding Medium

A small fraction of individual cellulose microfibrils in plant cell walls show appreciable bending along a portion of their length in a plane tangential to the cell surface. Segments of such curved microfibrils from transverse sections of Avena coleoptile epidermal or parenchyma cells do not straighten when they are freed from the constraints imposed by adjacent microfibrils, amorphous cell wall constituents, or the embedding medium. The curvature of these segments is not affected by immersion in cold water for 30 minutes, in hot water for 10 minutes, or in steam at 100° for 10 minutes. The results indicate that there is no elastic deformation of bent cellulose microfibrils in dried plant cell walls. The curvature of the microfibrils in the absence of elastic deformation suggests either (a) that cellulose microfibrils may be synthesized in a bent strain-free condition or (b) that cellulose microfibrils are synthesized in a straight form, followed by elastic deformation with subsequent release of strain by recrystallization on drying.

scholarly journals Pectin methylesterase selectively softens the onion epidermal wall yet reduces acid-induced creep

2020 ◽  
Vol 71 (9) ◽  
pp. 2629-2640 ◽  
Author(s):  
Xuan Wang ◽  
Liza Wilson ◽  
Daniel J Cosgrove
Keyword(s):  
Cell Walls ◽  
Tensile Force ◽  
Pectin Methylesterase ◽  
Tensile Tests ◽  
Indentation Modulus ◽  
Force Extension ◽  
Biological Responses ◽  
Physical Consequences ◽  
Living Tissues ◽  
Pectin Gels

Abstract De-esterification of homogalacturonan (HG) is thought to stiffen pectin gels and primary cell walls by increasing calcium cross-linking between HG chains. Contrary to this idea, recent studies found that HG de-esterification correlated with reduced stiffness of living tissues, measured by surface indentation. The physical basis of such apparent wall softening is unclear, but possibly involves complex biological responses to HG modification. To assess the direct physical consequences of HG de-esterification on wall mechanics without such complications, we treated isolated onion (Allium cepa) epidermal walls with pectin methylesterase (PME) and assessed wall biomechanics with indentation and tensile tests. In nanoindentation assays, PME action softened the wall (reduced the indentation modulus). In tensile force/extension assays, PME increased plasticity, but not elasticity. These softening effects are attributed, at least in part, to increased electrostatic repulsion and swelling of the wall after PME treatment. Despite softening and swelling upon HG de-esterification, PME treatment alone failed to induce cell wall creep. Instead, acid-induced creep, mediated by endogenous α-expansin, was reduced. We conclude that HG de-esterification physically softens the onion wall, yet reduces expansin-mediated wall extensibility.

Changes in the hemicellulosic polysaccharides of Avena coleoptile cell walls during growth of intact seedlings

1988 ◽  
Vol 66 (5) ◽  
pp. 949-954 ◽  
Author(s):  
M. Teresa Herrera ◽  
Ignacio Zarra
Keyword(s):  
Molecular Weight ◽  
Avena Sativa ◽  
Cell Walls ◽  
Average Molecular Weight ◽  
Relative Content ◽  
The Other ◽  
Polysaccharide Fraction ◽  
Avena Coleoptile ◽  
Main Component ◽  
Soluble Part

The variations taking place in the major polysaccharides of the cell wall of Avena sativa L. cv. Victory coleoptiles were studied during growth. Two fractions were obtained, one corresponding to cellulose and the other to the hemicelluloses. The relative content of cellulose was greater in the basal regions of the coleoptiles and the proportion of this polysaccharide fraction increased in all regions during growth. The hemicellulosic fraction was composed of two parts, an insoluble one designated the HC A hemicellulosic fraction, whose main component was seen to be an insoluble xyloglucan, and a soluble part designated the HC B hemicellulosic fraction, composed of an arabinoxylan and a (β1-3)- or (β1-4)-glucan. This latter was degraded during the growth of the coleoptiles. The average molecular weight of hemicelluloses HC A and HC B decreased from the sub-apical zones to the basal zones of the coleoptiles; this was related to the growth capacity of each of the regions into which the coleoptiles were divided.

scholarly journals β-d-Glucan of Avena Coleoptile Cell Walls

1977 ◽  
Vol 60 (4) ◽  
pp. 617-621 ◽  
Author(s):  
Donald J. Nevins ◽  
Donald J. Huber ◽  
Ryoichi Yamamoto ◽  
Wayne H. Loescher
Keyword(s):  
Cell Walls ◽  
Avena Coleoptile

scholarly journals Binding of Enzymes to Avena Coleoptile Cell Walls

1960 ◽  
Vol 35 (5) ◽  
pp. 567-574 ◽  
Author(s):  
Eugene F. Jansen ◽  
Rosie Jang ◽  
James Bonner
Keyword(s):  
Cell Walls ◽  
Avena Coleoptile

scholarly journals Pectin methylesterase selectively softens the onion epidermal wall yet reduces acid-induced creep

2019 ◽  
Author(s):  
Xuan Wang ◽  
Liza Wilson ◽  
Daniel J. Cosgrove
Keyword(s):  
Cell Walls ◽  
Tensile Force ◽  
Pectin Methylesterase ◽  
Tensile Tests ◽  
Indentation Modulus ◽  
Force Extension ◽  
Biological Responses ◽  
Physical Consequences ◽  
Living Tissues ◽  
Pectin Gels

AbstractDe-esterification of homogalacturonan (HG) is thought to stiffen pectin gels and primary cell walls by increasing calcium crosslinking between HG chains. Contrary to this idea, recent studies found that HG de-esterification correlated with reduced stiffness of living tissues, measured by surface indentation. The physical basis of such apparent wall softening is unclear, but possibly involves complex biological responses to HG modification. To assess the direct physical consequences of HG de-esterification on wall mechanics without such complications, we treated isolated onion (Allium cepa) epidermal walls with pectin methylesterase (PME) and assessed wall biomechanics with indentation and tensile tests. In nanoindentation assays, PME action softened the wall (reduced the indentation modulus). In tensile force/extension assays, PME increased plasticity, but not elasticity. These softening effects are attributed, at least in part, to increased electrostatic repulsion and swelling of the wall after PME treatment. Despite softening and swelling upon HG de-esterification, PME treatment alone failed to induce cell wall creep. Instead, acid-induced creep, mediated by endogenous α expansin, was reduced. We conclude that HG de-esterification physically softens the onion wall, yet reduces expansin-mediated wall extensibility.HighlightAfter enzymatic de-esterification without added calcium, the onion epidermal wall swells and becomes softer, as assessed by nanoindentation and tensile plasticity tests, yet exhibits reduced expansin-mediated creep.

FINE STRUCTURE OF GUARD-CELL WALLS IN AVENA COLEOPTILE

1957 ◽  
Vol 35 (5) ◽  
pp. 791-793 ◽  
Author(s):  
George Setterfield
Keyword(s):  
Fine Structure ◽  
Guard Cell ◽  
Cell Walls ◽  
Avena Coleoptile

not available

Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

1973 ◽  
Vol 31 ◽  
pp. 468-469
Author(s):  
N.C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Electron Microscopy ◽  
Acetic Acid ◽  
Nitric Acid ◽  
Oxalic Acid ◽  
Light Microscopy ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Plant Viruses ◽  
Plant Leaves ◽  
Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

An ultrastructural study of vegetative incompatibility in plants

1978 ◽  
Vol 36 (2) ◽  
pp. 436-437
Author(s):  
Randy Moore
Keyword(s):  
Ultrastructural Study ◽  
Cell Walls ◽  
Growth And Development ◽  
Solanum Pennellii ◽  
Initial Product ◽  
Basic Aspect ◽  
Tissue Interactions ◽  
Graft Interface ◽  
Antigen Antibody ◽  
Standard Fixation

Cell and tissue interactions are a basic aspect of eukaryotic growth and development. While cell-to-cell interactions involving recognition and incompatibility have been studied extensively in animals, there is no known antigen-antibody reaction in plants and the recognition mechanisms operating in plant grafts have been virtually neglected.An ultrastructural study of the Sedum telephoides/Solanum pennellii graft was undertaken to define possible mechanisms of plant graft incompatibility. Grafts were surgically dissected from greenhouse grown plants at various times over 1-4 weeks and prepared for EM employing variations in the standard fixation and embedding procedure. Stock and scion adhere within 6 days after grafting. Following progressive cell senescence in both Sedum and Solanum, the graft interface appears as a band of 8-11 crushed cells after 2 weeks (Fig. 1, I). Trapped between the buckled cell walls are densely staining cytoplasmic remnants and residual starch grains, an initial product of wound reactions in plants.

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

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