scholarly journals ELECTRON MICROSCOPY OF SPORES OF BACILLUS MEGATERIUM WITH SPECIAL REFERENCE TO THE EFFECTS OF FIXATION AND THIN SECTIONING

1962 ◽  
Vol 13 (3) ◽  
pp. 423-435 ◽  
Author(s):  
L. J. Rode ◽  
C. Willard Lewis ◽  
J. W. Foster
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Special Reference ◽  
Bacillus Megaterium ◽  
Normal State ◽  
Dipicolinic Acid ◽  
Indirect Evidence ◽  
Outer Edge ◽  
Thin Sectioning ◽  
Resting Spores

Resting spores of Bacillus megaterium appear uniformly opaque and undifferentiated under the electron microscope. Germinated spores and spores which have lost their dipicolinic acid underwent characteristic changes in structure. Spores fixed with KMnO4 lose their dipicolinic acid. Spores fixed with OsO4 under certain conditions retain their dipicolinic acid. When conventional sectioning procedures are used with either method of fixation, abnormal spore structure is produced as a result of the solution of cellular constitutents. Dry sections of unfixed spores embedded in methacrylate reveal the spore structure in a more normal state. Indirect evidence has been obtained for the existence of a penetration barrier at or near the outer edge of the cortex.

Albumins as Embedding Media for Electron Microscopy

1969 ◽  
Vol 27 ◽  
pp. 422-423 ◽  
Author(s):  
J. L. Farrant ◽  
J. D. McLean
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Temperature ◽  
Biological Material ◽  
Globular Proteins ◽  
The Past ◽  
Antibody Staining ◽  
Thin Sectioning ◽  
Embedding Medium

For electron microscope techniques such as ferritin-labeled antibody staining it would be advantageous to have available a simple means of thin sectioning biological material without subjecting it to lipid solvents, impregnation with plastic monomers and their subsequent polymerization. With this aim in view we have re-examined the use of protein as an embedding medium. Gelatin which has been used in the past is not very satisfactory both because of its fibrous nature and the high temperature necessary to keep its solutions fluid. We have found that globular proteins such as the serum and egg albumins can be cross-linked so as to yield blocks which are suitable for ultrathin sectioning.

scholarly journals ELECTRON MICROSCOPY OF THE NUCLEAR MEMBRANE OF AMOEBA PROTEUS

1956 ◽  
Vol 2 (4) ◽  
pp. 445-448 ◽  
Author(s):  
Marie H. Greider ◽  
Wencel J. Kostir ◽  
Walter J. Frajola
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Nuclear Membrane ◽  
Outer Layer ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Cell Types ◽  
Amoeba Proteus ◽  
Nuclear Membranes ◽  
Thin Sectioning

An electron microscope study of the nuclear membrane of Amoeba proteus by thin sectioning techniques has revealed an ultrastructure in the outer layer of the membrane that is homologous to the pores and annuli observed in the nuclear membranes of many other cell types studied by these techniques. An inner honeycombed layer apparently unique to Amoeba proteus is also described.

Thin sectioning for cryo transmission electron microscopy (cryo TEM)

1986 ◽  
Vol 44 ◽  
pp. 102-103
Author(s):  
A.W. McDowall ◽  
J.M. Smith ◽  
J. Dubochet
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Structural Integrity ◽  
Specimen Preparation ◽  
Structural Alterations ◽  
Whole Cells ◽  
Transmission Electron ◽  
Thin Sectioning

Processing whole cells and tissues for conventional TEM is known to cause structural alterations. Much effort has been devoted, therefore, to developing techniques which avoid specimen preparation artefacts. Recently, research using a cryo-electron microscope has shown that biological suspensions embedded in vitreous ice retain their structural integrity, and when compared with conventionally prepared TEM specimens, are free from many of the classical artefacts. In order to extend the advantage of cryo TEM to whole cells and tissues, we have developed a method of thin sectioning vitrified material.

Scanning electron microscopy of the sporosorus in Polymyxa betae (Plasmodiophoromycetes)

1988 ◽  
Vol 66 (12) ◽  
pp. 2518-2522 ◽  
Author(s):  
G. Clafardini ◽  
B. Marotta
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Direct Contact ◽  
Host Cells ◽  
Polymyxa Betae ◽  
Resting Spores ◽  
The Individual ◽  
Scanning Electron

Results are reported for observations of sporosori of Polymyxa betae Keskin made with the scanning electron microscope on sugar-beet roots. Sporosori were extracted from the host cells 15, 20, and 30 days after inoculation, purified, and observed with the scanning electron microscope. The morphology of sporosori differs, depending on their stage of maturation. Immature resting spores (cysts) are polyhedral and characterized by a wall rich in folds that converge towards the upper portion in six ridges arranged regularly in a spoke fashion. During maturation the walls of the individual resting spores unfold and come into direct contact with each other. Towards the end of maturation the resting spores become rounded and, after their walls split, germination takes place. After germination the sporosori still conserve their structure as a result of the effect of a cementing substance that keeps the walls united. Details are given of the system used to extract and purify the sporosori for observation using the scanning electron microscope.

Immune electron microscopy of haemocyanins from two southern african whelks

1978 ◽  
Vol 36 (2) ◽  
pp. 158-159
Author(s):  
Linda M. Stannard ◽  
Margaret Lennon
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Outer Ring ◽  
Immune Electron Microscopy ◽  
Intertidal Zones ◽  
Central Belt ◽  
Cape Peninsula ◽  
Circular Contour

Burnupena cincta and Fusus verruculatus are two whelks which inhabit the intertidal zones of the Cape Peninsula shore. Their respiratory pigments, or haemocyanins, are morphologically similar in structure (Figs. 1 and 2) and appear in the electron microscope as short cylindrical rods about 34 nm in diameter and 36 nm high. Viewed side-on the molecules show regular banding suggesting a structure composed of six equidistant rings of sub-units. Occasionally the particles have the appearance of possessing a central “belt” in the position of the 3rd and 4th rows of sub-units. End-on views of the haemocyanin molecules show a circular contour with a dense outer ring and a less dense inner ring in which 10 definite sub-units may frequently be distinguished. A number of molecules display an extra central inner component which appears either as a diffuse plug or as a discrete ring-shaped core ± 8 nm in diameter.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Preparatory Procedures for Electron Microscopic Analysis at the Molecular Level of Resolution

1978 ◽  
Vol 36 (3) ◽  
pp. 516-520
Author(s):  
F.J. Sjostrand
Keyword(s):  
Electron Microscope ◽  
Molecular Level ◽  
Microscopic Analysis ◽  
Resolving Power ◽  
Cellular Structures ◽  
Electron Microscopic ◽  
Systematic Analysis ◽  
Technical Developments ◽  
Thin Sectioning ◽  
Obvious Reason

In the 1940's and 1950's electron microscopy conferences were attended with everybody interested in learning about the latest technical developments for one very obvious reason. There was the electron microscope with its outstanding performance but nobody could make very much use of it because we were lacking proper techniques to prepare biological specimens. The development of the thin sectioning technique with its perfectioning in 1952 changed the situation and systematic analysis of the structure of cells could now be pursued. Since then electron microscopists have in general become satisfied with the level of resolution at which cellular structures can be analyzed when applying this technique. There has been little interest in trying to push the limit of resolution closer to that determined by the resolving power of the electron microscope.

Lead aspartate: a new en bloc stain for electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 34-35
Author(s):  
J.R. Walton
Keyword(s):  
Electron Microscopy ◽  
Calcium Ion ◽  
Enzyme Reaction ◽  
Lead Citrate ◽  
Reaction Products ◽  
En Bloc ◽  
Thin Sections ◽  
Lead Salts ◽  
Thin Sectioning ◽  
High Alkalinity

In electron microscopy, lead is the metal most widely used for enhancing specimen contrast. Lead citrate requires a pH of 12 to stain thin sections of epoxy-embedded material rapidly and intensively. However, this high alkalinity tends to leach out enzyme reaction products, making lead citrate unsuitable for many cytochemical studies. Substitution of the chelator aspartate for citrate allows staining to be carried out at pH 6 or 7 without apparent effect on cytochemical products. Moreover, due to the low, controlled level of free lead ions, contamination-free staining can be carried out en bloc, prior to dehydration and embedding. En bloc use of lead aspartate permits the grid-staining step to be bypassed, allowing samples to be examined immediately after thin-sectioning.Procedures. To prevent precipitation of lead salts, double- or glass-distilled H20 used in the stain and rinses should be boiled to drive off carbon dioxide and glassware should be carefully rinsed to remove any persisting traces of calcium ion.

Application of Scanning Electron Microscopy to Medical Research

1969 ◽  
Vol 27 ◽  
pp. 12-13
Author(s):  
J. D. Hutchison
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Medical Research ◽  
Prosthetic Heart Valve ◽  
School Of Medicine ◽  
Transmission Electron ◽  
Definition Of ◽  
Mechanism Of Failure ◽  
The Brain ◽  
Scanning Electron

When the transmission electron microscope was commercially introduced a few years ago, it was heralded as one of the most significant aids to medical research of the century. It continues to occupy that niche; however, the scanning electron microscope is gaining rapidly in relative importance as it fills the gap between conventional optical microscopy and transmission electron microscopy.IBM Boulder is conducting three major programs in cooperation with the Colorado School of Medicine. These are the study of the mechanism of failure of the prosthetic heart valve, the study of the ultrastructure of lung tissue, and the definition of the function of the cilia of the ventricular ependyma of the brain.

Transfer Technique for Electron Microscopy of Membrance Filter Samples

1974 ◽  
Vol 32 ◽  
pp. 554-555
Author(s):  
Lawrence W. Ortiz ◽  
Bonnie L. Isom
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Pore Size ◽  
Membrane Filters ◽  
Size Dependent

A procedure is described for the quantitative transfer of fibers and particulates collected on membrane filters to electron microscope (EM) grids. Various Millipore MF filters (Millipore AA, HA, GS, and VM; 0.8, 0.45, 0.22 and 0.05 μm mean pore size) have been used with success. Observed particle losses have not been size dependent and have not exceeded 10%. With fibers (glass or asbestos) as the collected media this observed loss is approximately 3%.

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