Freeze-etch study of the cell envelope of cowpea rhizobia: compartmentalization of the periplasmic space in relation to polysaccharide excretion

1990 ◽  
Vol 36 (6) ◽  
pp. 373-383 ◽  
Author(s):  
Bina Mody ◽  
Rustom Mody ◽  
Vinod Modi
Keyword(s):  
Outer Membrane ◽  
Cell Envelope ◽  
Ruthenium Red ◽  
Distinctive Features ◽  
Rhizobium Strains ◽  
Cytoplasmic Membranes ◽  
Rigid Cell Wall ◽  
Freeze Etching ◽  
Ruthenium Red Staining ◽  
Cowpea Rhizobia

Freeze-etching electron microscopy of free-living cowpea rhizobia revealed distinctive features of the cell envelope of this bacteria. The topology of the outer and cytoplasmic membranes was comparable with that described for other Gram-negative bacteria. In cowpea Rhizobium strains JLn(c) and NC-92, the rigid cell wall almost invariably cleaved away from the outer membrane, thus exposing two distinct fracture faces in the outer membrane, which to date have been ill defined in rhizobia. Cross-fractured cells showed enlargement of the periplasmic region as a result of invagination of the cytoplasmic membrane near one end of the cell. This feature was consistent in all exponential and stationary phase cells. Ruthenium red staining of cells in various growth phases showed unipolar initiation of the capsule. A unique structure seen within the enlarged periplasm was the presence of a smooth lipidic vesicle. Key words: Rhizobium, freeze-etch, membrane, polysaccharide, vesicle.

Acidity and calcium interaction affecting cell envelope stability inRhizobium

1998 ◽  
Vol 44 (6) ◽  
pp. 582-587 ◽  
Author(s):  
Karen G Ballen ◽  
Peter H Graham ◽  
Roger K Jones ◽  
John H Bowers
Keyword(s):  
Outer Membrane ◽  
Antimicrobial Agents ◽  
Cell Envelope ◽  
Outer Membrane Proteins ◽  
Acid Methyl Ester ◽  
Acid Soils ◽  
Rhizobium Tropici ◽  
Ph Tolerance ◽  
Rhizobium Strains ◽  
Effects Of Ph

Calcium improves the ability of many rhizobia to survive and persist in acid soils, but the mechanism responsible for this phenomenon has not been studied in detail. Here, we present data examining the combined effects of pH and calcium on the cell envelope of Rhizobium strains that differ in pH tolerance. The effect of pH and calcium on solute uptake was demonstrated by a change in the resistance to selected antimicrobial agents. When grown at pH 5.0, all strains exhibited fatty acid methyl ester profiles that were significantly different from those obtained using cells grown at pH 7.0. These differences included changes in the C16:C18 ratio and the percentage of 19:0 cyclopropane in the membrane. Both pH and calcium level had marked effects on Rhizobium etli UMR1632 lipopolysaccharide-banding patterns, but there was little evidence of a change in lipopolysaccharides with pH and calcium in Rhizobium tropici UMR1899. Both pH and calcium influenced expression of outer membrane proteins in all strains.Key words: Rhizobium, acidity, calcium, lipopolysaccharide, cell envelope, outer membrane protein.

Fine structure and distribution of extracellular polymer surrounding selected aerobic bacteria

1975 ◽  
Vol 21 (3) ◽  
pp. 395-408 ◽  
Author(s):  
Gerald D. Cagle
Keyword(s):  
Fine Structure ◽  
Acinetobacter Calcoaceticus ◽  
Ruthenium Red ◽  
Aerobic Bacteria ◽  
Staining Procedure ◽  
Streptococcus Salivarius ◽  
Critical Point Drying ◽  
Freeze Etching ◽  
Ruthenium Red Staining ◽  
Extracellular Polymer

The structure and distribution of extracellular polymer surrounding Bacillus circulans, Diplococcus (Streptococcus) pneumoniae, Streptococcus salivarius, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Herellea vaginacola (Acinetobacter calcoaceticus), and Agrobacterium tumefaciens were studied by electron microscopy. A modified ruthenium red staining procedure was used to examine the fine structure of capsule and slime. Freeze-etching and critical-point drying were used to examine the quantity of unaltered exocellular material. Comparative data demonstrate that fibrillar extracellular polymer surrounding B. circulans, D. pneumoniae, and K. pneumoniae is capsule (cell wall attached) which is characteristic of the producing organism. Capsular polymer generally appeared fibrillar, although globular polymer consisted of capsular subunits bound to S. salivarius and H. vaginacola. Exocellular slime was present about S. aureus, P. aeruginosa, and A. tumefaciens.

Ultrastructure of the cell wall of a Synechocystis strain

1980 ◽  
Vol 26 (2) ◽  
pp. 204-208 ◽  
Author(s):  
K. Lounatmaa ◽  
T. Vaara ◽  
K. Österlund ◽  
M. Vaara
Keyword(s):  
Cell Wall ◽  
Outer Membrane ◽  
Wall Layer ◽  
Ruthenium Red ◽  
Electron Microscopic ◽  
External Wall ◽  
Membrane Complex ◽  
Additional Layer ◽  
Hexagonal Arrangement ◽  
Ruthenium Red Staining

The ultrastructure of the cell wall of a Synechocystis strain, isolated from the Gulf of Finland, was studied using several electron microscopic techniques. This cyanobacterium has numerous projections which were observed to penetrate the cell wall complex. An additional layer (AL) was associated with the outer membrane. An additional external wall layer (EL) was connected to the outer membrane complex by thin fibers as revealed by ruthenium red staining. A hexagonal arrangement of the subunits in the additional external wall layer with a lattice constant of 15.5 nm was found.

Ruthenium Red Staining of Human Hard Keratin Fibers

1982 ◽  
Vol 40 ◽  
pp. 278-279
Author(s):  
M. C. Buhrer ◽  
R. A. Mathews
Keyword(s):  
Human Hair ◽  
Ruthenium Red ◽  
Acid Mucopolysaccharides ◽  
Biochemical Studies ◽  
Keratin Fibers ◽  
Ruthenium Red Staining ◽  
Extracellular Materials

Ruthenium red has been used as a stain to demonstrate a variety of extracellular materials, especially acid mucopolysaccharides. It also reacts with certain intracellular and extracellular lipids. Since biochemical studies in our laboratory demonstrated the presence of a variety of monosaccharides in human hair ruthenium red staining procedures were adopted in order to evaluate the presence and morphological location of acid oligosaccharides in the keratinized aspect of hair.

scholarly journals Stress-Based High-Throughput Screening Assays to Identify Inhibitors of Cell Envelope Biogenesis

Antibiotics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 808
Author(s):  
Maurice Steenhuis ◽  
Corinne M. ten Hagen-Jongman ◽  
Peter van Ulsen ◽  
Joen Luirink
Keyword(s):  
Outer Membrane ◽  
High Throughput ◽  
Stress Responses ◽  
High Throughput Screening ◽  
Structural Integrity ◽  
Cell Envelope ◽  
Screening Assay ◽  
High Throughput Screening Assay ◽  
Compound Screening ◽  
Outer Membrane Biogenesis

The structural integrity of the Gram-negative cell envelope is guarded by several stress responses, such as the σE, Cpx and Rcs systems. Here, we report on assays that monitor these responses in E. coli upon addition of antibacterial compounds. Interestingly, compromised peptidoglycan synthesis, outer membrane biogenesis and LPS integrity predominantly activated the Rcs response, which we developed into a robust HTS (high-throughput screening) assay that is suited for phenotypic compound screening. Furthermore, by interrogating all three cell envelope stress reporters, and a reporter for the cytosolic heat-shock response as control, we found that inhibitors of specific envelope targets induce stress reporter profiles that are distinct in quality, amplitude and kinetics. Finally, we show that by using a host strain with a more permeable outer membrane, large-scaffold antibiotics can also be identified by the reporter assays. Together, the data suggest that stress profiling is a useful first filter for HTS aimed at inhibitors of cell envelope processes.

Structure, properties and enhanced expression of galactose-binding C-type lectins in mucous cells of gills from freshwater Japanese eels (Anguilla japonica)

2001 ◽  
Vol 360 (1) ◽  
pp. 107-115 ◽  
Author(s):  
Abinash Chandra MISTRY ◽  
Shinji HONDA ◽  
Shigehisa HIROSE
Keyword(s):  
Ruthenium Red ◽  
Anguilla Japonica ◽  
Amino Acid Residues ◽  
Mucous Cells ◽  
Cdna Subtraction ◽  
Competitive Binding Assay ◽  
Enhanced Expression ◽  
Ruthenium Red Staining ◽  
High Level ◽  
Cdna Subtraction Library

Using a Japanese-eel (Anguilla japonica) gill cDNA subtraction library, two novel β-d-galactose-binding lectins were identified that belong to group VII of the animal C-type lectin family. The eel C-type lectins, termed eCL-1 and eCL-2, are simple lectins composed of 163 amino acid residues, including a 22-residue signal peptide for secretion and a single carbohydrate-recognition domain (CRD) of ∼ 130 residues typical of C-type lectins. The galactose specificity of the CRD was suggested by the presence of a QPD motif and confirmed by a competitive binding assay. Using Ruthenium Red staining, the lectins were shown to bind Ca2+ ions. SDS/PAGE showed that native eCL-1 and eCL-2have an SDS-resistant octameric structure (a tetramer of disulphide-linked dimers). Northern and Western blot analyses demonstrated high-level expression of eCL-1 and eCL-2 mRNAs and their protein products in gills from freshwater eels, which decreased markedly when the eels were transferred from freshwater to seawater. Immunohistochemistry showed that the eel lectins are localized in the exocrine mucous cells of the gill.

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.

Morphology and ultrastructure of oral strains of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus

1980 ◽  
Vol 30 (2) ◽  
pp. 588-600
Author(s):  
S C Holt ◽  
A C Tanner ◽  
S S Socransky
Keyword(s):  
Electron Microscopy ◽  
Ruthenium Red ◽  
Actinobacillus Actinomycetemcomitans ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Large Numbers ◽  
Haemophilus Aphrophilus ◽  
Ruthenium Red Staining ◽  
Amorphous Surface ◽  
Scanning Electron

Selected human oral and nonoral strains of the genera Actinobacillus and Haemophilus were examined by transmission and scanning electron microscopy. The strains examined were morphologically identical to recognized Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, and Haemophilus paraphrophilus. By transmission electron microscopy, the cells were typically gram negative in morphology, with several strains possessing some extracellular ruthenium red-staining polymeric material. Numerous vesicular structures, morphologically identical to lipopolysaccharide vesicles, were seen to originate from and be continuous with the surface of the outer membrane. Large numbers of these vesicles were also found in the external environment. Scanning electron microscopic observations revealed that both actinobacilli and haemophili possessed surface projections and an amorphous surface material which connected and covered adjacent cells.

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