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.

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.

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.

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.

scholarly journals Three-dimensional electron microscopy of ribosomal chromatin in two higher plants: a cytochemical, immunocytochemical, and in situ hybridization approach.

1991 ◽  
Vol 39 (11) ◽  
pp. 1495-1506 ◽  
Author(s):  
P M Motte ◽  
R Loppes ◽  
M Menager ◽  
R Deltour
Keyword(s):  
Electron Microscopy ◽  
In Situ Hybridization ◽  
Spatial Organization ◽  
Higher Plants ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Thin Sections ◽  
Cytoplasmic Dna ◽  
Immunocytochemical Techniques

We report the 3-D arrangement of DNA within the nucleolar subcomponents from two evolutionary distant higher plants, Zea mays and Sinapis alba. These species are particularly convenient to study the spatial organization of plant intranucleolar DNA, since their nucleoli have been previously reconstructed in 3-D from serial ultra-thin sections. We used the osmium ammine-B complex (a specific DNA stain) on thick sections of Lowicryl-embedded root fragments. Immunocytochemical techniques using anti-DNA antibodies and rDNA/rDNA in situ hybridization were also applied on ultra-thin sections. We showed on tilted images that the OA-B stains DNA throughout the whole thickness of the section. In addition, very low quantities of cytoplasmic DNA were stained by this complex, which is now the best DNA stain used in electron microscopy. Within the nucleoli the DNA was localized in the fibrillar centers, where large clumps of dense chromatin were also visible. In the two plant species intranucleolar chromatin forms a complex network with strands partially linked to chromosomal nucleolar-organizing regions identified by in situ hybridization. This study describes for the first time the spatial arrangement of the intranucleolar chromatin in nucleoli of higher plants using high-resolution techniques.

The Gram‐negative cell envelope ‘springs’ to life: coiled‐coil trans‐envelope proteins

1996 ◽  
Vol 19 (3) ◽  
pp. 643-645 ◽  
Author(s):  
Andréa Pimenta ◽  
Mark Blight ◽  
David Clarke ◽  
I. Barry Holland
Keyword(s):  
Cell Envelope ◽  
Coiled Coil ◽  
Envelope Proteins ◽  
Gram Negative ◽  
Negative Cell

Ultrastructure of the in situ adherence of Mobiluncus to vaginal epithelial cells

1988 ◽  
Vol 34 (6) ◽  
pp. 757-766 ◽  
Author(s):  
Jan M. De Boer ◽  
Friso H. F. Plantema
Keyword(s):  
Electron Microscopy ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Surface ◽  
Bacterial Vaginosis ◽  
Vaginal Fluid ◽  
Thin Sections ◽  
Epithelial Cell Surface ◽  
Curved Rods

From patients with bacterial vaginosis motile, anaerobic, comma-shaped bacteria can be isolated, which have recently been placed into the new genus Mobiluncus. In this study, electron microscopy was used to examine the in situ adherence of these motile curved rods to detached epithelial cells (comma cells) in vaginal fluid from two patients with bacterial vaginosis. Thin sections showed that the curved rods attached both directly to the epithelial cell surface and at various distances from it. It is concluded that after initial attachment these motile bacteria can grow at the epithelial cell surface in sessile microcolonies. Ruthenium red staining demonstrated a coating of precipitated glycocalyx material both on the surface of the curved rods and on their flagella. This may indicate that in situ the adherent curved rods were enclosed in a very hydrated matrix of exopolysaccharides. Conspicuous was the ability of the curved rods to attach to the epithelial cell surface via their cell tips. However, in situ no specialized bacterial cell surface structures were seen that might explain this polar attachment. Electron microscopy of pure cultures demonstrated that both Mobiluncus curtisii subsp. curtisii and Mobiluncus mulieris can produce a glycocalyx in vitro.

A comparison of isolated and in situ thick filaments from smooth muscle

1986 ◽  
Vol 44 ◽  
pp. 156-157
Author(s):  
E.L. Buhle ◽  
A.V. Somlyo ◽  
A.P. Somlyo
Keyword(s):  
Smooth Muscle ◽  
Actin Filaments ◽  
Muscle Actin ◽  
Thin Sections ◽  
Ultrastructural Studies ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
Rabbit Portal Vein ◽  
Stable Structures

Early ultrastructural studies of smooth muscle are consistent with the sliding filament mechanism of contraction. Myosin filaments are stable structures in situ and can be found in both relaxed and contracted muscle. Actin filaments can be decorated with SI subfragments of myosin to show a polarity similar to the Z-lines of skeletal muscle. The work presented here is a comparison of isolated thick filaments from relaxed chick amnion with thick filaments obtained in situ from longitudinal thin sections (∽50nm thick) of rabbit portal vein in rigor.

Homeostasis of the Gram-negative cell envelope

2021 ◽  
Vol 61 ◽  
pp. 99-106
Author(s):  
Shreya Saha ◽  
Sarah R Lach ◽  
Anna Konovalova
Keyword(s):  
Cell Envelope ◽  
Gram Negative ◽  
Negative Cell

Bactericidal effect of gentamicin-induced membrane vesicles derived fromPseudomonas aeruginosaPAO1 on gram-positive bacteria

2002 ◽  
Vol 48 (9) ◽  
pp. 810-820 ◽  
Author(s):  
Kelly L MacDonald ◽  
Terry J Beveridge
Keyword(s):  
Electron Microscopy ◽  
Therapeutic Potential ◽  
Hydrophobic Interaction Chromatography ◽  
Membrane Vesicles ◽  
Bactericidal Effect ◽  
Gram Positive ◽  
Thin Sections ◽  
Gram Negative ◽  
Induced Membrane ◽  
Gram Positive Bacteria

Previous studies have shown that gentamicin-induced membrane vesicles (g-MVs) from Pseudomonas aeruginosa PAO1 possess both the antibiotic (gentamicin) and a potent peptidoglycan hydrolase (PGase; autolysin) that is effective in killing gram-negative pathogens. This present study evaluated the therapeutic potential of g-MVs against four gram-positive bacteria. Bactericidal assays and electron microscopy of thin sections revealed that Bacillus subtilis 168 and Staphylococcus aureus D2C were susceptible to killing mediated by g-MVs, Listeria monocytogenes ATCC 19113 was slightly susceptible, whereas Enterococcus hirae ATCC 9790 was unaffected. g-MVs were generally more effective against the bacteria than was soluble gentamicin, suggesting they could have more killing power than natural membrane vesicles containing no antibiotic. Electron microscopy and hydrophobic interaction chromatography showed that more membrane vesicles (MVs) initially attached to B. subtilis (hydrophilic) than to predominantly hydrophobic E. hirae, L. monocytogenes, and S. aureus. Zymograms containing murein sacculi as an enzyme substrate illustrated that all organisms except E. hirae were sensitive to the 26-kDa autolysin to varying degrees. Peptidoglycan O-acetylation did not influence susceptibility to MV-mediated lysis. Though not universally effective, the g-MV delivery system remains a promising therapeutic alternative for specific gram-positive infections.Key words: gram-negative membrane vesicles, gentamicin, autolysin.

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