A THREE-DIMENSIONAL COMPUTER MODEL OF THE TRACHEID CELL WALL AS A TOOL FOR INTERPRETATION OF WOOD CELL WALL ULTRASTRUCTURE

IAWA Journal ◽  
2001 ◽  
Vol 22 (3) ◽  
pp. 213-233 ◽  
Author(s):  
L.A. Donaldson
Keyword(s):  
Cell Wall ◽  
Electron Micrographs ◽  
Cell Walls ◽  
Three Dimensional ◽  
Transmission Electron Micrographs ◽  
Direct Result ◽  
Thin Sections ◽  
Transmission Electron ◽  
Wall Ultrastructure ◽  
Random Patterns

Three-dimensional computer models were used to simulate transmission electron micrographs in order to determine the effects of changes in microfibril orientation and arrangement on the appearance of ultrastructural images based on thin sections. It is shown that the tangential fibrillar texture commonly associated with wood cell walls results not from individual microfibrils arranged in tangential lamellae but from overlapping of adjacent microfibrils irrespective of their arrangement. The tangential lamellae observed in transmission electron micrographs of wood cell walls do not necessarily reflect the underlying nanostructure of the wall. Tangential textures can occur irrespective of the arrangement of microfibrils in tangential, radial or random patterns as a direct result of the helical organisation of the cell wall. Comparison between model images and high resolution micrographs suggests that microfibrils are arranged randomly in weakly defined clusters, with perhaps varying amounts of tangential or radial organisation.

LYSOZYME SENSITIVITY OF THE CELL WALL OF PSEUDO-MONAS AERUGINOSA: FURTHER EVIDENCE FOR THE ROLE OF THE NON-PEPTIDOGLYCAN COMPONENTS IN CELL WALL RIGIDITY

1966 ◽  
Vol 12 (1) ◽  
pp. 105-108 ◽  
Author(s):  
K. Jane Carson ◽  
R. G. Eagon
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Wall ◽  
Electron Micrographs ◽  
Cell Walls ◽  
Gram Negative Bacteria ◽  
Normal Cells ◽  
Thin Sections ◽  
Gram Negative ◽  
Cell Wall Rigidity

Electron micrographs of thin sections of normal cells of Pseudomonas aeruginosa showed the cell walls to be convoluted and to be composed of two distinct layers. Electron micrographs of thin sections of lysozyme-treated cells of P. aeruginosa showed (a) that the cell walls lost much of their convoluted nature; (b) that the layers of the cell walls became diffuse and less distinct; and (c) that the cell walls became separated from the protoplasts over extensive cellular areas. These results suggest that the peptidoglycan component of the unaltered cell walls of P. aeruginosa is sensitive to lysozyme. Furthermore, it appears that the peptidoglycan component is not solely responsible for the rigidity of the cell walls of Gram-negative bacteria.

scholarly journals Differences in cell wall of thin and thick filaments of cyanobacterium Aphanizomenon gracile SAG 31.79 and their implications for different resistance to Daphnia grazing

2016 ◽  
Author(s):  
Lukasz Wejnerowski ◽  
Slawek Cerbin ◽  
Maria K. Wojciechowicz ◽  
Marcin K. Dziuba
Keyword(s):  
Cell Wall ◽  
Wall Thickness ◽  
Cell Walls ◽  
Cell Wall Thickness ◽  
Filamentous Cyanobacterium ◽  
Thin Sections ◽  
Thick Filaments ◽  
Transmission Electron ◽  
The Difference ◽  
Aphanizomenon Gracile

<p>Recent studies have shown that the filamentous cyanobacterium <em>Aphanizomenon gracile</em> Lemmermann, strain SAG 31.79, consists of two types of filaments that differ in thickness. These two types are known to vary in resistance to <em>Daphnia</em> <em>magna</em> grazing: thin filaments (&lt;2.5 µm) are more vulnerable to grazing than the thick ones (&gt;2.5 µm). In this study, we investigated whether the difference in the vulnerability to grazing of thin and thick filaments is a result of different thickness of their cell walls, a filament stiffness determinant. We expected thick filaments to have thicker cell walls than the thin ones. Additionally, we analysed whether cell wall thickness correlates with filament thickness regardless of the filament type. A morphometric analysis of cell walls was performed using transmission electron micrographs of ultra-thin sections of the batch-cultured cyanobacterial material.  Our study revealed that the thin type of filaments had thinner cell walls than the thick filaments. Moreover, cell wall thickness was positively correlated with filament thickness. TEM (transmission electron microscopy) observations also revealed that the thin type of filaments was often at different stages of autocatalytic cell destruction, which was mainly manifested in the increase in cell vacuolization and degradation of the cytoplasm content. Based on our findings, we assume that previously reported higher resistance of thick filaments to <em>Daphnia</em> grazing results from greater stiffness and excellent physiological conditions of thick filaments. </p>

Ultrastructure and cytology of pycnia, aecia, and aeciospores of Gymnosporangium clavipes

1975 ◽  
Vol 53 (10) ◽  
pp. 972-977 ◽  
Author(s):  
Frank Kozar ◽  
Hans J. Netolitzky
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Light Microscopy ◽  
Electron Micrographs ◽  
Transmission Electron Micrographs ◽  
Dense Cytoplasm ◽  
Transmission Electron ◽  
Inner Surface ◽  
Scanning Electron

Aeciospores of Gymnosporangium clavipes Cooke & Peck have a surface characterized by a dense covering of baculate projections. Transmission electron micrographs (TEM) reveal a thick non-striated cell wall and a dense cytoplasm. Peridial cells have an inner surface studded with clavate projections. Scanning electron microscope (SEM) microgaphs confirmed earlier light microscopy studies of the existence of fiexious hyphae.

Procedures for three-dimensional reconstruction of spherical viruses by Fourier synthesis from electron micrographs

1971 ◽  
Vol 261 (837) ◽  
pp. 221-230 ◽  
Keyword(s):  
Electron Micrographs ◽  
Fourier Transforms ◽  
Three Dimensional ◽  
Transmission Electron Micrographs ◽  
Three Dimensional Reconstruction ◽  
Fourier Synthesis ◽  
Combine Data ◽  
Density Maps ◽  
Transmission Electron ◽  
Dimensional Reconstruction

An account is given of a method which has been developed for computing three-dimensional density maps from transmission electron micrographs using Fourier transforms. The reconstructions objectively combine data from several different views of one or more particles. The application to negatively stained tomato bushy stunt virus is described in detail and the resulting reconstruction presented. Projections of the reconstruction in the appropriate directions agree well with images of the virus taken from micrographs.

Identification of the three-dimensional gel microstructure from transmission electron micrographs

2007 ◽  
Vol 225 (1) ◽  
pp. 10-21 ◽  
Author(s):  
RASMUS NISSLERT ◽  
MATS KVARNSTRÖM ◽  
NIKLAS LORÉN ◽  
MAGNUS NYDÉN ◽  
MATS RUDEMO
Keyword(s):  
Electron Micrographs ◽  
Three Dimensional ◽  
Transmission Electron Micrographs ◽  
Transmission Electron

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

Ultrastructure of commercial recycled pulp fibers for the production of packaging paper

Holzforschung ◽  
2005 ◽  
Vol 59 (6) ◽  
pp. 675-680 ◽  
Author(s):  
Jonas Brändström ◽  
Jean-Paul Joseleau ◽  
Alain Cochaux ◽  
Nathalie Giraud-Telme ◽  
Katia Ruel
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Significant Proportion ◽  
Pulp Fibers ◽  
Chemical Pulp ◽  
Recycled Pulp ◽  
Transmission Electron ◽  
Large Heterogeneity ◽  
Recycled Fibers ◽  
Packaging Paper

Abstract Transmission electron microscopy was used to investigate the ultrastructure of recycled pulp fibers originating from a household collection plant and intended for the production of packaging paper. Three recovered paper grades and recycling processes, including pulping, screening, cleaning and refining, were assessed with emphasis on surface and internal fibrillation as well as xylan localization. Results showed a large heterogeneity with respect to fiber ultrastructure within and between the grades. Screening and cleaning steps had no detectable effects, but refining clearly increased cell-wall delamination and surface fibrillation. Immunolabeling of xylans showed that they were distributed rather evenly across the cell walls. They were also present on fines. Two different mechanisms for fiber delamination and surface fibrillation were found, one which implies that internal and external fibrillation take place simultaneously across the cell wall, and another which implies successive peeling of layers or sub-layers from the outside towards the inside. It is suggested that recycled fibers of chemical pulp origin undergo the former mechanism and recycled fibers that contain lignin binding the cell wall matrix give rise to the latter peeling mechanism. Because several recycled fibers were severely delaminated and almost fractured, we suggest that to produce a good packaging paper, it is important that recycled pulp should contain a significant proportion of fibers with high intrinsic strength.

scholarly journals FINE STRUCTURE OF THE GRAM-NEGATIVE BACTERIUM ACETOBACTER SUBOXYDANS

1964 ◽  
Vol 20 (2) ◽  
pp. 217-233 ◽  
Author(s):  
G. W. Claus ◽  
L. E. Roth
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Cell Walls ◽  
Negative Staining ◽  
Homogeneous Layer ◽  
Physical Treatment ◽  
Thin Sections ◽  
Gram Negative ◽  
Acetobacter Suboxydans ◽  
Negative Cell

The morphological features of the cell wall, plasma membrane, protoplasmic constituents, and flagella of Acetobacter suboxydans (ATCC 621) were studied by thin sectioning and negative staining. Thin sections of the cell wall demonstrate an outer membrane and an inner, more homogeneous layer. These observations are consistent with those of isolated, gram-negative cell-wall ghosts and the chemical analyses of gram-negative cell walls. Certain functional attributes of the cell-wall inner layer and the structural comparisons of gram-negative and gram-positive cell walls are considered. The plasma membrane is similar in appearance to the membrane of the cell wall and is occasionally found to be folded into the cytoplasm. Certain features of the protoplasm are described and discussed, including the diffuse states of the chromatinic material that appear to be correlated with the length of the cell and a polar differentiation in the area of expected flagellar attachment. Although the flagella appear hollow in thin sections, negative staining of isolated flagella does not substantiate this finding. Severe physical treatment occasionally produces a localized penetration into the central region of the flagellum, the diameter of which is much smaller then that expected from sections. A possible explanation of this apparent discrepancy is discussed.

scholarly journals Identifying Atoms in High Resolution Transmission Electron Micrographs Using a Deep Convolutional Neural Net

2018 ◽  
Vol 24 (S1) ◽  
pp. 512-513 ◽  
Author(s):  
Jakob Schiøtz ◽  
Jacob Madsen ◽  
Pei Liu ◽  
Ole Winther ◽  
Jens Kling ◽  
...  
Keyword(s):  
High Resolution ◽  
Electron Micrographs ◽  
Transmission Electron Micrographs ◽  
Neural Net ◽  
Transmission Electron
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