Ultrastructure of the cell envelope and septation process in Caryophanon latum as revealed by thin section and freeze-etching techniques

1974 ◽  
Vol 20 (10) ◽  
pp. 1435-1442 ◽  
Author(s):  
W. C. Trentini ◽  
H. E. Gilleland Jr.
Keyword(s):  
Cytoplasmic Membrane ◽  
External Surface ◽  
Cell Envelope ◽  
Optimal Conditions ◽  
Structural Detail ◽  
Cross Sectional ◽  
External Wall ◽  
Thin Sectioning ◽  
Freeze Etching ◽  
Peptidoglycan Layer

With optimal conditions of thin-sectioning and freeze-etching, the cell wall of Caryophanon latum was composed of a thick peptidoglycan layer plus two external wall layers. The freeze-etched appearance of the external surface of the outer layer was smooth and lacked structural detail. The numerous cross septa within a trichome were formed by the symmetrical and concurrent ingrowth of the cytoplasmic membrane and the peptidoglycan layer. The site of septum initiation was identifiable by a dart-shaped ingrowth of the peptidoglycan layer rather than by the presence of a mesosome. However, small simple mesosomes were occasionally seen associated with the developing septum. The peptidoglycan in the septum had thickened to at least double the thickness of the wall peptidoglycan layer by the time of septum completion. The external wall layers did not participate in septum formation but did participate in trichome separation. The separation of the septal peptidoglycan was completed during the early ingrowth of the external wall layers. A unique cross-sectional view of a developing septum closing like an iris diaphragm as seen in a freeze-etched preparation was observed.

Comparative ultrastructure of selected oral streptococci: thin-sectioning and freeze-etching studies

1976 ◽  
Vol 22 (4) ◽  
pp. 475-485 ◽  
Author(s):  
Stanley C. Holt ◽  
E. R. Leadbetter
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Cytoplasmic Membrane ◽  
Close Association ◽  
Oral Streptococci ◽  
Outermost Layer ◽  
Thin Sectioning ◽  
Freeze Etching ◽  
Comparative Ultrastructure ◽  
Crystalline Array

The ultrastructure of Streptococcus mutans, serotypes a–e, S. sanguis, S. mitis, and S. salivarius HHT, were examined by the techniques of thin-sectioning and freeze-etching. The cell walls varied in width between 15 and 46 nm and were covered with an electron-dense fibrillar or fuzz layer. The cytoplasmic membrane was in close association with numerous mesosomes which were, in turn, either closely associated or in contact with the bacterial chromosome. In freeze-etch replicas, the outermost layer of the cell wall was fibrous, and the cytoplasmic membrane was covered with particles composed of several subunits. Both particle-clusters and particle-free areas occurred on the surfaces of the cytoplasmic membrane, as well as a crystalline array in the ground plasm of the cell.

Ultrastructure of Staphylococcus epidermidis after freeze-etching and thin sectioning

1973 ◽  
Vol 19 (2) ◽  
pp. 294-295
Author(s):  
James E. Gilchrist ◽  
Irving W. DeVoe
Keyword(s):  
Staphylococcus Aureus ◽  
Outer Layer ◽  
Staphylococcus Epidermidis ◽  
Cell Walls ◽  
Cytoplasmic Membrane ◽  
Middle Layer ◽  
Dense Layer ◽  
Thin Sections ◽  
Thin Sectioning ◽  
Freeze Etching

A considerable quantity of information is now available on the ultrastructure of Staphylococcus (1, 2, 4, 7, 8, 10, 11, 12). Cell walls of these organisms in thin sections have been shown to consist of three layers: a dense outer layer, a rather electron translucent middle layer, and a very dense layer next to the cytoplasmic membrane (2, 7, 11, 12). Bulger and Bulger (2) have pointed out the presence of circumferential substructure in the middle layer of the wall in a strain of Staphylococcus aureus isolated as the causative agent in fatal pneumonia.Numerous mesosomes of both the vesicular and laminar types are evident in thin sections of staphylococci from several studies (1, 4, 7, 11). Moreover, single vesicular structures that appear to be invaginations of the trilaminar cytoplasmic membrane have been pointed out by Suganuma (11) and Beaton (1).

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.

The Peptidoglycan Layer of the Reiter Treponeme as Revelaed by Thin Sectioning and Freeze-etching Techniques

Microscopy ◽  
1979 ◽  
Vol 28 (3) ◽  
pp. 189-192
Author(s):  
Hiroyuki MORIOKA ◽  
Hiroyuki OZASA ◽  
Tsunataro KISHIDA ◽  
Yoshitake YOKOTA ◽  
Atsushi SUGANUMA
Keyword(s):  
Thin Sectioning ◽  
Freeze Etching ◽  
Peptidoglycan Layer

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.

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.

scholarly journals ULTRASTRUCTURE AND CALCIUM TRANSPORT IN CRUSTACEAN MUSCLE MICROSOMES

1971 ◽  
Vol 48 (1) ◽  
pp. 49-60 ◽  
Author(s):  
R. J. Baskin
Keyword(s):  
Freeze Drying ◽  
Calcium Uptake ◽  
Membrane Thickness ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Crustacean Muscle ◽  
Thin Sectioning ◽  
Critical Point Drying ◽  
Freeze Etching ◽  
Microscopic Techniques

Fragmented sarcoplasmic reticulum (FSR) from crustacean muscle was examined following preparation by a variety of electron microscopic techniques. The 30–40 A particles which appeared on the outer surface of FSR vesicles following negative staining were not observed following preparation by freeze-drying, freeze-etching, thin sectioning, or critical-point drying. Crustacean FSR exhibited high values of calcium uptake and extensive nodular formation in the presence of oxalate. 80–90 A diameter membrane particles were seen in freeze-etch preparations of both intact lobster muscle and FSR vesicles. Thin sections of FSR vesicles revealed a membrane thickness of 60–70 A. The membrane appeared to be triple layered, each layer having a thickness of 20–25 A.

scholarly journals The Rcs Phosphorelay Is a Cell Envelope Stress Response Activated by Peptidoglycan Stress and Contributes to Intrinsic Antibiotic Resistance

2008 ◽  
Vol 190 (6) ◽  
pp. 2065-2074 ◽  
Author(s):  
Mary E. Laubacher ◽  
Sarah E. Ades
Keyword(s):  
Outer Membrane ◽  
Single Molecule ◽  
Stress Responses ◽  
Structural Integrity ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Intrinsic Resistance ◽  
Gram Negative ◽  
Envelope Stress ◽  
Peptidoglycan Layer

ABSTRACTGram-negative bacteria possess stress responses to maintain the integrity of the cell envelope. Stress sensors monitor outer membrane permeability, envelope protein folding, and energization of the inner membrane. The systems used by gram-negative bacteria to sense and combat stress resulting from disruption of the peptidoglycan layer are not well characterized. The peptidoglycan layer is a single molecule that completely surrounds the cell and ensures its structural integrity. During cell growth, new peptidoglycan subunits are incorporated into the peptidoglycan layer by a series of enzymes called the penicillin-binding proteins (PBPs). To explore how gram-negative bacteria respond to peptidoglycan stress, global gene expression analysis was used to identifyEscherichia colistress responses activated following inhibition of specific PBPs by the β-lactam antibiotics amdinocillin (mecillinam) and cefsulodin. Inhibition of PBPs with different roles in peptidoglycan synthesis has different consequences for cell morphology and viability, suggesting that not all perturbations to the peptidoglycan layer generate equivalent stresses. We demonstrate that inhibition of different PBPs resulted in both shared and unique stress responses. The regulation of capsular synthesis (Rcs) phosphorelay was activated by inhibition of all PBPs tested. Furthermore, we show that activation of the Rcs phosphorelay increased survival in the presence of these antibiotics, independently of capsule synthesis. Both activation of the phosphorelay and survival required signal transduction via the outer membrane lipoprotein RcsF and the response regulator RcsB. We propose that the Rcs pathway responds to peptidoglycan damage and contributes to the intrinsic resistance ofE. colito β-lactam antibiotics.

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