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.

scholarly journals Cytoplasmic surface structure in postsynaptic membranes from electric tissue visualized by tannic-acid-mediated negative contrasting.

1982 ◽  
Vol 92 (2) ◽  
pp. 514-522 ◽  
Author(s):  
R Sealock
Keyword(s):  
Acetylcholine Receptor ◽  
Tannic Acid ◽  
Cytoplasmic Membrane ◽  
Membrane Surfaces ◽  
Peripheral Membrane Proteins ◽  
Cytoplasmic Surface ◽  
Thin Section Electron Microscopy ◽  
Surface Image ◽  
Section Electron ◽  
Hydrophobic Portion

In this study, acetylcholine receptor-rich postsynaptic membranes from electric tissues of the electric rays Narcine brasiliensis and Torpedo californica are negatively contrasted for thin-section electron microscopy through the use of tannic acid. Both outer (extracellular) and inner (cytoplasmic) membrane surfaces are negatively contrasted, and can be studied together in transverse sections. The hydrophobic portion of the membrane appears as a thin (approximately 2 nm), strongly contrasted band. This band is the only image given by membrane regions which are devoid of acetylcholine receptor. In regions of high receptor density, however, both surfaces of the membrane are seen to bear or be associated with material which extends approximately 6.5 nm beyond the center of the bilayer. The material on the outer surface can be identified with the well-known extracellular portion of the receptor molecule. A major portion of the inner surface image is eliminated by extraction of the membranes at pH 11 to remove peripheral membrane proteins, principally the 43,000 Mr (43K) protein. The images thus suggest a cytoplasmic localization of the 43K protein, with its distribution being coextensive with that of the receptor. They also suggest that the 43K protein extends farther from the cytoplasmic surface than does the receptor.

Induced morphological changes in the stainable layers of the cell envelope of a gram-negative bacterium

1972 ◽  
Vol 18 (6) ◽  
pp. 937-940
Author(s):  
J. W. Costerton ◽  
J. Thompson
Keyword(s):  
Cytoplasmic Membrane ◽  
Morphological Changes ◽  
Cell Envelope ◽  
Physical Nature ◽  
Ion Concentration ◽  
Negative Bacterium ◽  
Gram Negative ◽  
Double Track ◽  
Peptidoglycan Layer

Manipulation of ion concentration can be used to produce profound changes in the morphology of both the cytoplasmic membrane and the outer double-track layer of the cell envelope of the marine pseudomonad studied here. The fact that these layers are deformable, without any changes in the morphology of the rigid peptidoglycan layer, suggests that both have a "plastic" physical nature.

scholarly journals ELECTRON MICROSCOPY OF CULTURED SPHERULES OF COCCIDIOIDES IMMITIS

1961 ◽  
Vol 9 (3) ◽  
pp. 627-637 ◽  
Author(s):  
Abraham M. Breslau ◽  
Thomas J. Hensley ◽  
John O. Erickson
Keyword(s):  
Electron Microscopy ◽  
Cytoplasmic Membrane ◽  
Coccidioides Immitis ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Ca 50 ◽  
Hyphal Wall ◽  
Section Electron Microscopy ◽  
Peripheral Cytoplasm

Spherules of C. immitis have been grown in vitro in modified Roessler's medium under CO2 tension and continuous cultures now maintained for over 18 months. Transformation of hyphae and development of the spherule form have been studied by thin section electron microscopy. Cells of organisms in the hyphal stage have thin (ca. 50 mµ), apparently structureless walls and a cytoplasmic membrane. Many nuclei, elongated mitochrondria with both transverse and longitudinal cristae, and lipid particles are present. The hyphal wall thickens and the cell transforms into spherules. A large central accumulation of electrontransparent polysaccharide appears in the spherule. The peripheral cytoplasm contains nuclei, each enclosed in a double-layered membrane, mitochondria, and small dense particles. Prior to cleavage the polysaccharide droplets are lost, while mitochrondria become small and spherical. Endospores are formed and liberated when the spherule wall breaks. These begin to grow and repeat the cleavage cycle.

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.

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

Deformation of Yeast Plasma Membrane by Ethidium Bromide

1988 ◽  
Vol 46 ◽  
pp. 254-255
Author(s):  
E. Keyhani
Keyword(s):  
Plasma Membrane ◽  
Thin Section ◽  
Ethidium Bromide ◽  
Freeze Fracture ◽  
Mutagenic Effect ◽  
Yeast Cells ◽  
Hydrophobic Region ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Deep Pits

The mutagenic effect of ethidium bromide on the mitochondrial DNA is well established. Using thin section electron microscopy, it was shown that when yeast cells were grown in the presence of ethidium bromide, besides alterations in the mitochondria, the plasma membrane also showed alterations consisting of 75 to 110 nm-deep pits. Furthermore, ethidium bromide induced an increase in the length and number of endoplasmic reticulum and in the number of intracytoplasmic vesicles.Freeze-fracture, by splitting the hydrophobic region of the membrane, allows the visualization of the surface view of the membrane, and consequently, any alteration induced by ethidium bromide on the membrane can be better examined by this method than by the thin section method.Yeast cells, Candida utilis. were grown in the presence of 35 μM ethidium bromide. Cells were harvested and freeze-fractured according to the procedure previously described.

Interaction of Gram-Negative Bacteria with the Lysosomal Fraction of Polymorphonuclear Leukocytes II. Changes in the Cell Envelope of Escherichia coli

1970 ◽  
Vol 1 (3) ◽  
pp. 311-318
Author(s):  
D. Friedberg ◽  
I. Friedberg ◽  
M. Shilo
Keyword(s):  
Escherichia Coli ◽  
Polymorphonuclear Leukocytes ◽  
Cytoplasmic Membrane ◽  
Morphological Changes ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Intact Cells ◽  
Lysosomal Fraction ◽  
E Coli ◽  
Absorbing Material

Interaction of lysosomal fraction with Escherichia coli caused damage to the cell envelope of these intact cells and to the cytoplasmic membrane of E. coli spheroplasts. The damage to the cytoplasmic membrane was manifested in the release of 260-nm absorbing material and β-galactosidase from the spheroplasts, and by increased permeability of cryptic cells to O -nitrophenyl-β- d -galactopyranoside; damage to the cell wall was measured by release of alkaline phosphatase. Microscope observation showed morphological changes in the cell envelope.

Fine structure of the heterochromatin of the kangaroo rat Dipidomys ordii, and examination of the possible role of actin and myosin in heterochromatin condensation

1976 ◽  
Vol 21 (3) ◽  
pp. 465-477
Author(s):  
D.E. Comings ◽  
T.A. Okada
Keyword(s):  
Constitutive Heterochromatin ◽  
Divalent Cations ◽  
Random Coils ◽  
Type Complex ◽  
Kangaroo Rat ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Liver Nuclei ◽  
The Brain

Biochemical studies have suggested that some actin and myosin may be present in the nucleus. This raises the possibility that heterochromatin condensation might be the result of an actin-myosin rigour type complex. Since ATP dissociates actin and myosin, this possibility could be examined by determining the effect of ATP on heterochromatin condensation. Thin-section electron microscopy showed large amounts of condensed constitutive heterochromatin in the kidney nuclei and somewhat less in the liver nuclei of the kangaroo rat, Dipidomys ordii. Surprisingly, there were some nuclei in the brain which contained no condensed heterochromatin despite the fact that this genome is composed of 50% satellite DNA. Although washing kidney nuclei with solutions of 10 mM Tris-ATP caused marked decondensation of the heterochromatin, when they were washed with Mg-ATP the heterochromatin was more condensed than in the controls. This suggests the decondensation by Tris-ATP is due to its ability to chelate divalent cations and provides no support for condensation of heterochromatin being the result of myosin-actin interaction. Despite being decondensed, the chromatin fibres of heterochromatin were distinct from those of euchromatin. The heterochromatin formed rod-like 19-5 nm fibres, the euchromatin formed random coils of 11-0-nm fibres.

Sensitivity of normal and mutant strains of Escherichia coli to actinomycin-D

1972 ◽  
Vol 18 (6) ◽  
pp. 909-915 ◽  
Author(s):  
A. P. Singh ◽  
K.-J. Cheng ◽  
J. W. Costerton ◽  
E. S. Idziak ◽  
J. M. Ingram
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Wild Type Strain ◽  
Actinomycin D ◽  
Cytoplasmic Membrane ◽  
Cell Envelope ◽  
Coli Strain ◽  
Wild Type ◽  
Mutant Strains ◽  
In The Wild

The site of the cell barrier to actinomycin-D uptake was studied using a wild-type Escherichia coli strain P and its cell envelope-defective filamentous mutants, strains 6γ and 12γ, both of which 'leak' β-galactosidase and alkaline phosphatase into the medium during growth indicating both membrane and cell-wall defects. Actinomycin-D entered the cells of these two mutant strains as evidenced by the inhibition of both 14C-uracil incorporation and synthesis of the induced β-galactosidase system. Under similar conditions, no inhibition occurred in the wild-type strain and its sucrose-lysozyme prepared spheroplasts. Actinomycin-D did, however, inhibit the above-mentioned systems in the wild-type sucrose-lysozyme spheroplasts prepared in the presence of 2 mM EDTA. The experimental data indicate that although the cell wall may act as a primary barrier or sieve to actinomycin-D, the cytoplasmic membrane should be considered the final and determinative barrier to this antibiotic.

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