Ultrastructural studies of Sphaerophoms varius and the infective process of an associated bacteriophage

1972 ◽  
Vol 18 (7) ◽  
pp. 1103-1111 ◽  
Author(s):  
David E. Bradley
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Cell Envelope ◽  
Host Organism ◽  
Viral Origin ◽  
Gram Negative ◽  
Ultrastructural Studies ◽  
Phage Assembly ◽  
Membrane Bound ◽  
Characteristic Features

The anaerobe Sphaerophoms varius was found by electron microscopy to be a typical Gram-negative organism in its ultrastructural anatomy. However, the following additional characteristic features were observed; small (25–100 nm), membrane-bound dark bodies, groups of thin, rod-shaped inclusions, and pointed poles. An associated bacteriophage was found to consist of an octahedron with a very short tail like coliphage T3. It proved to be temperate and was released in large quantities by the mitomycin C induction of a lysogenized clone of the host organism. Induction also produced rods (identified with those in sections), and empty capsids believed to be of viral origin. Electron microscopy showed that the virulent infective process caused structural changes in the nucleoplasm before phage assembly and release; this was achieved by a single break in the cell envelope. It was concluded that S. varius was able to support at least two different plasmids, a bacteriophage and a probable bacteriocin.

Ultrastructural studies of Chondromyces crocatus vegetative cells

1975 ◽  
Vol 21 (11) ◽  
pp. 1815-1826 ◽  
Author(s):  
Thomas H. MacRae ◽  
Howard D. McCurdy
Keyword(s):  
Electron Microscopy ◽  
Cell Envelope ◽  
Thin Sections ◽  
Gram Negative ◽  
Ultrastructural Studies ◽  
Negative Cell ◽  
Slime Layer ◽  
Movement Characteristic ◽  
Gliding Movement

Electron microscopy of sectioned, chemically fixed Chondromyces crocatus revealed a microorganism with a typical gram-negative cell envelope. The cytoplasm contained, in addition to tubules and two types of granules, a membrane-associated structure (MAS) that, although less extensive, bears some resemblance to polar membranes observed in flagellated bacteria. Examination of swarming cells negatively stained in situ, as well as thin sections, established that cell division occurs by septum formation and that well-defined mesosomes are associated with the process. Polar pili and a compact, amorphous slime layer surrounding the cells were evident in shadowed preparations of in situ cells. The slime layer and pili, by providing cell-to-cell interconnections, may influence the organized gliding movement characteristic of C. crocatus and other myxobacteria.

Conformational characterization of nucleosome structure by Electron Microscopy

1993 ◽  
Vol 51 ◽  
pp. 194-195
Author(s):  
Gregory J. Czarnota
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Physiological State ◽  
Gene Activation ◽  
Three Dimensional ◽  
Macromolecular Complex ◽  
Ultrastructural Studies ◽  
Ionic Environment ◽  
Nucleosome Structure ◽  
Dimensional Reconstruction

Chromatin structure at the fundamental level of the nucleosome is important in vital cellular processes. Recent biochemical and genetic analyses show that nucleosome structure and structural changes are very active participants in gene expression, facilitating or inhibiting transcription and reflecting the physiological state of the cell. Structural states and transitions for this macromolecular complex, composed of DNA wound about a heterotypic octamer of variously modified histone proteins, have been measured by physico-chemical techniques and by enzyme-accessibility and are recognized to occur with various post-translational modifications, gene activation, transformation and with ionic-environment. In spite of studies which indicate various forms of nucleosome structure, all current x-ray and neutron diffraction studies have consistently resulted in only one structure, suggestive of a static conformation. In contrast, two-dimensional electron microscopy studies and three-dimensional reconstruction techniques have yielded different structures. These fundamental differences between EM and other ultrastructural studies have created a long standing quandary, which I have addressed and resolved using spectroscopic electron microscopy and statistical analyses of nucleosome images in a study of nucleosome structure with ionic environment.

Fine structural observations of Desulfovibrio desulfuricans

1973 ◽  
Vol 19 (6) ◽  
pp. 753-756
Author(s):  
Terrence M. Hammill ◽  
Geno J. Germano
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
Cell Envelope ◽  
Desulfovibrio Desulfuricans ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Ultrathin Sections ◽  
Basal Apparatus ◽  
Specialized Region ◽  
Whole Mounts

Glutaraldehyde-fixed, platinum-carbon-shadowed whole mounts, and ultrathin sections of glutaraldehyde-OsO4-fixed cells of Desulfovibrio desulfuricans were observed by electron microscopy. The preparations demonstrated a typical Vibrio form with a single polar flagellum. The cell envelope and the formation of external blebs were shown to be similar to other gram-negative bacteria. The protoplast, apparently devoid of mesosomes or other membranous structures, was densely packed with ribosomes and contained a fibrous nucleoid. A specialized region near the flagellar end of the cell was commonly observed and termed the basal apparatus. Cell division appeared to be by constriction.

Physiological and morphological effects of phenethyl alcohol upon a gram-negative marine pseudomonad

1972 ◽  
Vol 18 (6) ◽  
pp. 841-852 ◽  
Author(s):  
J. Thompson ◽  
I. W. DeVoe
Keyword(s):  
Structural Changes ◽  
Cytoplasmic Membrane ◽  
Cell Envelope ◽  
Gram Negative ◽  
Phenethyl Alcohol ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Uptake Medium ◽  
Subsequent Addition ◽  
Acid Exchange

Phenethyl alcohol (PEA) at 0.15% (v/v) inhibited the growth of a gram-negative marine pseudomonad. After removal of the alcohol, the cells remained viable even when pre-exposed to PEA concentrations as high as 0.25% (v/v). Phenethyl alcohol inhibited uptake of α-aminoisobutyric acid (AIB) and also prevented amino acid exchange. At PEA concentrations of 0.25% or less, inhibition of AIB uptake was completely reversible and, provided K+ was added to the uptake medium, the treated cells could accumulate AIB to the same extent as control cells. If K+ was omitted from the medium, the capacity of the cells to accumulate AIB was found to be proportional to the length of time that the cells had been exposed to the alcohol. Phenethyl alcohol caused a rapid efflux of intracellular K+ and AIB-14C from previously loaded cells, and such cells were noticeably smaller than normal cells and had a plasmolyzed or irregular outline when observed by phase contrast. Thin section electron microscopy, and freeze-etch studies, showed that the plasmolyzed appearance of these cells was due to local invagination of the cytoplasmic membrane. After removal of the alcohol, the subsequent addition of K+ to the incubation medium caused the cells to become deplasmolyzed. It seems likely that the inhibition of cell growth by PEA is due to two major causes: (1) direct interference of the compound with the normal physiological functions of the cytoplasmic membrane and, (2) PEA induced structural changes occurring within the cell envelope.

Cell envelope analysis of Coxiella Burneti phase I and phase II

1974 ◽  
Vol 20 (10) ◽  
pp. 1465-1470 ◽  
Author(s):  
T. R. Jerrells ◽  
David J. Hinrichs ◽  
L. P. Mallavia
Keyword(s):  
Electron Microscopy ◽  
Phase I ◽  
Phase Ii ◽  
Cell Envelope ◽  
Diaminopimelic Acid ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Carbohydrate Concentration ◽  
Morphological Studies ◽  
Cell Envelopes

Cell envelopes of Coxiella burneti, Nine Mile, phase I and phase II were examined by electron microscopy and analyzed chemically in an attempt to characterize the phase phenomenon noted in this organism. Electron microscopy of intact organisms as well as cell envelope fractions revealed a morphology similar to many gram-negative bacteria and other rickettsiae. Morphological studies revealed no differences between C. burneti in phase I or II. Chemical analyses revealed a basic composition similar to that reported for members of the genus Rickettsia and many gram-negative bacteria. Cell envelopes of both phase types of this organism (I and II) contained similar amounts of extractable lipid, similar amino acid composition, and the amino sugars glucosamine and muramic acid. Diaminopimelic acid (DAP) was demonstrated in the cell envelope of both phase types. Coxiella burneti phase I differed from the phase II form in carbohydrate composition as well as protein and carbohydrate concentration. Glucuronic acid, glucose, and galactose were found in C. burneti phase I envelopes, whereas only glucose and galactose were present in phase II envelopes.

Isolation and characterization of a new acidophilic Thiobacillus species (T. albertis)

1983 ◽  
Vol 29 (9) ◽  
pp. 1159-1170 ◽  
Author(s):  
R. D. Bryant ◽  
K. M. McGroarty ◽  
J. W. Costerton ◽  
E. J. Laishley
Keyword(s):  
Inclusion Bodies ◽  
Cell Envelope ◽  
Ultrastructural Studies ◽  
Isolation And Characterization ◽  
Sulfur Granule ◽  
Stabilization Procedure ◽  
Membrane Bound ◽  
Sulfur Oxidizing ◽  
Ph Range

An acidophilic, rod-shaped, sulfur-oxidizing bacterium was isolated from extremely acidic soil adjacent to a sulfur stockpile at Fox Creek, Alta. This isolate was found to grow only autotrophically by oxidizing S° and reduced inorganic sulfur compounds (S2O32− and S4O62−), placing it in the genus Thiobacillus. Aerobic growth was observed over a pH range of 2.0 to 4.5 with optimum growth at 3.5 to 4.0. Analysis of its DNA revealed a mol% G + C content of 61.5. Ultrastructural studies showed that the isolate possessed a tuft of polar flagella. A glycocalyx was observed only after the antiserum stabilization procedure, which showed it extending outwards from the outer membrane of the bacterial cell envelope. Cleavage planes of this cell showed a typical Gram-negative cell wall. The cytoplasm contained two types of inclusion bodies, carboxysomes and a single large membrane-bound sulfur granule. This isolate had morphological and physiological characteristics which were not totally comparable with other known acidiophilic thiobacilli demonstrating this bacterium to be a new Thiobacillus sp. named T.albertis.

Electron microscopy of endocardial cell populations

1978 ◽  
Vol 36 (2) ◽  
pp. 486-487
Author(s):  
T. G. Sarphie ◽  
C. R. Comer ◽  
D. J. Allen
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Cellular Transformation ◽  
Cell Populations ◽  
Cell Surfaces ◽  
Kb Cells ◽  
Dna Viruses ◽  
Cell Cycles ◽  
Ultrastructural Studies ◽  
Endocardial Cell

Previous ultrastructural studies have characterized surface morphology during norma cell cycles in an attempt to associate specific changes with specific metabolic processes occurring within the cell. It is now known that during the synthetic ("S") stage of the cycle, when DNA and other nuclear components are synthesized, a cel undergoes a doubling in volume that is accompanied by an increase in surface area whereby its plasma membrane is elaborated into a variety of processes originally referred to as microvilli. In addition, changes in the normal distribution of glycoproteins and polysaccharides derived from cell surfaces have been reported as depreciating after cellular transformation by RNA or DNA viruses and have been associated with the state of growth, irregardless of the rate of proliferation. More specifically, examination of the surface carbohydrate content of synchronous KB cells were shown to be markedly reduced as the cell population approached division Comparison of hamster kidney fibroblasts inhibited by vinblastin sulfate while in metaphase with those not in metaphase demonstrated an appreciable decrease in surface carbohydrate in the former.

Embedding Procedure for Water Swollen Samples

1970 ◽  
Vol 28 ◽  
pp. 504-505
Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Exchange ◽  
Structural Changes ◽  
Cross Linking ◽  
Ion Exchange Resins ◽  
Transmission Electron ◽  
First Pass ◽  
Exchange Resins

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.

Selection and Preparation of Specific Tissue Regions For Tem Using Large Epoxy-Embedded Blocks

1973 ◽  
Vol 31 ◽  
pp. 324-325 ◽  
Author(s):  
P. M. Lowrie ◽  
W. S. Tyler
Keyword(s):  
Electron Microscopy ◽  
Anatomical Structures ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Microscopic Evaluation ◽  
Embedded Blocks ◽  
Specific Tissue ◽  
Definition Of ◽  
Areas Of Interest ◽  
Selection Of

The importance of examining stained 1 to 2μ plastic sections by light microscopy has long been recognized, both for increased definition of many histologic features and for selection of specimen samples to be used in ultrastructural studies. Selection of specimens with specific orien ation relative to anatomical structures becomes of critical importance in ultrastructural investigations of organs such as the lung. The uantity of blocks necessary to locate special areas of interest by random sampling is large, however, and the method is lacking in precision. Several methods have been described for selection of specific areas for electron microscopy using light microscopic evaluation of paraffin, epoxy-infiltrated, or epoxy-embedded large blocks from which thick sections were cut. Selected areas from these thick sections were subsequently removed and re-embedded or attached to blank precasted blocks and resectioned for transmission electron microscopy (TEM).

Adenomatoid Tumor of the Testis, A Mesonephric Hamartoma

1971 ◽  
Vol 29 ◽  
pp. 318-319
Author(s):  
Raoul Fresco ◽  
Mary Chang-Lo
Keyword(s):  
Electron Microscopy ◽  
Epithelial Cells ◽  
Fibrous Tissue ◽  
Salient Feature ◽  
Luminal Surface ◽  
Adenomatoid Tumor ◽  
Ultrastructural Studies ◽  
Epithelial Origin ◽  
Brush Borders ◽  
Cell Processes

Confusion surrounds the nature of the “adenomatoid tumor” of the testis, as evidenced by the large number of synonyms which have been ascribed to it. Various authors have considered the tumor to be of endothelial, mesothelial or epithelial origin. There appears to be no controversy as to the stromal elements of the tumor, which consists mainly of smooth muscle and fibrous tissue. It is the irregular gland-like spaces which have given rise to the numerous theories as to its histogenesis, and even recent ultrastructural studies fail to agree on the origin of these structures.Electron microscopy of a typical intrascrotal adenomatoid tumor showed the gland-like spaces to be lined by epithelial cells (Fig. 1), rich in cytoplasmic tonofibrils and united to each other by numerous desmosomes (Fig. 2). The most salient feature of these epithelial cells was the presence on their luminal surface of numerous long and repeatedly branching microvillous structures of the type known as stereocilia (Fig. 3). These are extremely long slender cell processes which are as much as three to four times the length of those in brush borders.

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