scholarly journals The Campylobacter jejuni Response Regulator and Cyclic-Di-GMP Binding CbrR Is a Novel Regulator of Flagellar Motility

2021 ◽  
Vol 10 (1) ◽  
pp. 86
Author(s):  
Claudia A. Cox ◽  
Marek Bogacz ◽  
Faiha M. El Abbar ◽  
Darren D. Browning ◽  
Brian Y. Hsueh ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Campylobacter Jejuni ◽  
Response Regulator ◽  
Negative Regulator ◽  
Flagellar Motility ◽  
E Coli ◽  
Transmission Electron ◽  
Liquid Chromatography Tandem Mass ◽  
Bacterial Gastroenteritis ◽  
Low Levels

A leading cause of bacterial gastroenteritis, Campylobacter jejuni is also associated with broad sequelae, including extragastrointestinal conditions such as reactive arthritis and Guillain-Barré Syndrome (GBS). CbrR is a C. jejuni response regulator that is annotated as a diguanylate cyclase (DGC), an enzyme that catalyzes the synthesis of c-di-GMP, a universal bacterial second messenger, from GTP. In C. jejuni DRH212, we constructed an unmarked deletion mutant, cbrR−, and complemented mutant, cbrR+. Motility assays indicated a hyper-motile phenotype associated with cbrR−, whereas motility was deficient in cbrR+. The overexpression of CbrR in cbrR+ was accompanied by a reduction in expression of FlaA, the major flagellin. Biofilm assays and scanning electron microscopy demonstrated similarities between DRH212 and cbrR−; however, cbrR+ was unable to form significant biofilms. Transmission electron microscopy showed similar cell morphology between the three strains; however, cbrR+ cells lacked flagella. Differential radial capillary action of ligand assays (DRaCALA) showed that CbrR binds GTP and c-di-GMP. Liquid chromatography tandem mass spectrometry detected low levels of c-di-GMP in C. jejuni and in E. coli expressing CbrR. CbrR is therefore a negative regulator of FlaA expression and motility, a critical virulence factor in C. jejuni pathogenesis.

An Ultrastructural Study of Chronic Pyelonephritis in Macaca Arctoides

1976 ◽  
Vol 34 ◽  
pp. 310-311
Author(s):  
T.W. Smith ◽  
J.A. Roberts ◽  
B.J. Martin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ultrastructural Study ◽  
Effective Means ◽  
Chronic Pyelonephritis ◽  
Macaca Arctoides ◽  
Left Ureter ◽  
E Coli ◽  
Transmission Electron ◽  
Sizeable Number

Chronic pyelonephritis is one of the most common diseases of the kidney and accounts for a sizeable number of cases of renal insufficiency in man, however its pathogenesis requires further elucidation. Transmission electron microscopy may serve as a uniquely effective means of observing details of the nature of this disease. The present paper describes preliminary results of an ultrastructural study of chronic pyelonephritis in Macaca arctoides (stumptail monkey).The infection was induced in these experiments in a retrograde fashion by means of a unilateral catheterization of the left ureter whereby an innoculum of 10 cc of broth containing approximately 2 billion E. coli per cc and radio-opaque dye were injected under pressure (mimicing vesico-ureteric reflux).

Imaging sub-micron objects with light microscopy: Visualization of the T-4 bacteriophage

1989 ◽  
Vol 47 ◽  
pp. 834-835
Author(s):  
Malcolm Brown ◽  
Reynolds M. Delgado ◽  
Michael J. Fink
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Focal Plane ◽  
Phase Contrast ◽  
Dark Field ◽  
E Coli ◽  
Polystyrene Beads ◽  
Television Camera ◽  
Transmission Electron ◽  
Universal Microscope

While light microscopy has been used to image sub-micron objects, numerous problems with diffraction-limitations often preclude extraction of useful information. Using conventional dark-field and phase contrast light microscopy coupled with image processing, we have studied the following objects: (a) polystyrene beads (88nm, 264nm, and 557mn); (b) frustules of the diatom, Pleurosigma angulatum, and the T-4 bacteriophage attached to its host, E. coli or free in the medium. Equivalent images of the same areas of polystyrene beads and T-4 bacteriophages were produced using transmission electron microscopy.For light microscopy, we used a Zeiss universal microscope. For phase contrast observations a 100X Neofluar objective (N.A.=1.3) was applied. With dark-field, a 100X planachromat objective (N.A.=1.25) in combination with an ultra-condenser (N.A.=1.25) was employed. An intermediate magnifier (Optivar) was available to conveniently give magnification settings of 1.25, 1.6, and 2.0. The image was projected onto the back focal plane of a film or television camera with a Carl Zeiss Jena 18X Compens ocular.

Iron substitution in aluminosilicate sols synthesized at low pH

Clay Minerals ◽  
1984 ◽  
Vol 19 (1) ◽  
pp. 1-8 ◽  
Author(s):  
M. B. McBride ◽  
V. C. Farmer ◽  
J. D. Russell ◽  
J. M. Tait ◽  
B. A. Goodman
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ir Spectroscopy ◽  
Esr Spectroscopy ◽  
Spectroscopic Analysis ◽  
Low Ph ◽  
Transmission Electron ◽  
Low Levels ◽  
Aluminosilicate Mineral ◽  
Tubular Morphology

AbstractThe procedure for synthesizing proto-imogolite (an acid-soluble hydroxy-aluminium orthosilicate complex) and imogolite (a tubular aluminosilicate mineral) was used to produce ferruginous aluminosilicates over a range of Al/Fe ratios to determine whether Fe3+ can be incorporated in the imogolite structure. Analysis of the synthesized products by transmission electron microscopy, electron diffraction, and IR spectroscopy indicated that, while imogolite was formed in the presence of iron, increased Fe3+ in the systems caused the formation of ferrihydrite and poorly-organized aluminosilicates resembling proto-imogolite allophane. Treatment of these materials with Na-citrate/dithionite/bicarbonate dissolved the ferrihydrite and poorly-organized aluminosilicate, and concentrated products with tubular morphology. Analysis of the structural Fe3+ by ESR spectroscopy suggested that little or no Fe3+ was incorporated in the structure of imogolite, although the less crystalline proto-imogolite allophane may have accommodated some structural Fe3+. A separate iron-rich product, identified as ferrihydrite, was formed at low Al/Fe ratios. Mössbauer spectroscopic analysis of 57Fe3+ doped at very low levels into proto-imogolite and imogolite indicated that the sites of substitution were better defined in the latter. At least part of this Fe3+ may have been incorporated in the structure of boehmite, an impurity formed during synthesis.

scholarly journals Antimicrobial Properties of a Chitosan Dextran-Based Hydrogel for Surgical Use

2011 ◽  
Vol 56 (1) ◽  
pp. 280-287 ◽  
Author(s):  
Manal A. Aziz ◽  
Jaydee D. Cabral ◽  
Heather J. L. Brooks ◽  
Stephen C. Moratti ◽  
Lyall R. Hanton
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Bacterial Species ◽  
Antimicrobial Properties ◽  
Sinus Surgery ◽  
Peptide Bonds ◽  
Content Type ◽  
E Coli ◽  
Transmission Electron

ABSTRACTA chitosan dextran-based (CD) hydrogel, developed for use in endoscopic sinus surgery, was tested for antimicrobial activityin vitroagainst a range of pathogenic microorganisms. The microdilution technique was used to determine minimum inhibitory, minimum bactericidal, and minimum fungicidal concentrations. In addition, the time-kill efficacy of CD hydrogel was determined for two bacterial species. Scanning and transmission electron microscopy were carried out to elucidate the antimicrobial mechanism of this compound. CD hydrogel was found to be effective againstStaphylococcus aureus,Streptococcus pyogenes,Escherichia coli, andClostridium perfringensat its surgical concentration of 50,000 mg/liter. Minimum bactericidal concentrations ranged from 2,000 to 50,000 mg/liter. Dextran aldehyde (DA) was found to be the antimicrobial component of the CD hydrogel with MBC ranging from 2,000 to 32,000 mg/liter.S. aureusappeared to be killed at a slightly faster rate thanE. coli. Candida albicansandPseudomonas aeruginosawere more resistant to CD hydrogel and DA. Scanning and transmission electron microscopy ofE. coliandS. aureusincubated with CD hydrogel and DA alone revealed morphological damage, disrupted cell walls, and loss of cytosolic contents, compatible with the proposed mode of action involving binding to cell wall proteins and disruption of peptide bonds. Motility and chemotaxis tests showedE. colito be inhibited when incubated with DA. The antibacterial activity of CD hydrogel may make it a useful postsurgical aid at other body sites, especially where there is a risk of Gram-positive infections.

scholarly journals A Campylobacter jejuni znuA Orthologue Is Essential for Growth in Low-Zinc Environments and Chick Colonization

2008 ◽  
Vol 191 (5) ◽  
pp. 1631-1640 ◽  
Author(s):  
Lindsay M. Davis ◽  
Tsutomu Kakuda ◽  
Victor J. DiRita
Keyword(s):  
Campylobacter Jejuni ◽  
Transport System ◽  
The United States ◽  
Gram Negative Bacteria ◽  
Limited Growth ◽  
E Coli ◽  
Poultry Products ◽  
Abc Transport ◽  
Bacterial Gastroenteritis

ABSTRACT Campylobacter jejuni infection is a leading cause of bacterial gastroenteritis in the United States and is acquired primarily through the ingestion of contaminated poultry products. Here, we describe the C. jejuni orthologue of ZnuA in other gram-negative bacteria. ZnuA (Cj0143c) is the periplasmic component of a putative zinc ABC transport system and is encoded on a zinc-dependent operon with Cj0142c and Cj0141c, which encode the other two likely components of the transport system of C. jejuni. Transcription of these genes is zinc dependent. A mutant lacking Cj0143c is growth deficient in zinc-limiting media, as well as in the chick gastrointestinal tract. The protein is glycosylated at asparagine 28, but this modification is dispensable for zinc-limited growth and chick colonization. Affinity-purified FLAG-tagged Cj0143c binds zinc in vitro. Based on our findings and on its homology to E. coli ZnuA, we conclude that Cj0143c encodes the C. jejuni orthologue of ZnuA.

Determination of Bacterial Cell Dry Mass by Transmission Electron Microscopy and Densitometric Image Analysis

1998 ◽  
Vol 64 (2) ◽  
pp. 688-694 ◽  
Author(s):  
M. Loferer-Krößbacher ◽  
J. Klima ◽  
R. Psenner
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Image Analysis ◽  
Bacterial Biomass ◽  
Dry Weight ◽  
Dry Mass ◽  
Bacterial Cells ◽  
E Coli ◽  
Transmission Electron ◽  
Bacterial Assemblages

ABSTRACT We applied transmission electron microscopy and densitometric image analysis to measure the cell volume (V) and dry weight (DW) of single bacterial cells. The system was applied to measure the DW ofEscherichia coli DSM 613 at different growth phases and of natural bacterial assemblages of two lakes, Piburger See and Gossenköllesee. We found a functional allometric relationship between DW (in femtograms) and V (in cubic micrometers) of bacteria (DW = 435 · V 0.86); i.e., smaller bacteria had a higher ratio of DW to V than larger cells. The measured DW of E. coli cells ranged from 83 to 1,172 fg, and V ranged from 0.1 to 3.5 μm3(n = 678). Bacterial cells from Piburger See and Gossenköllesee (n = 465) had DWs from 3 fg (V = 0.003 μm3) to 1,177 fg (V = 3.5 μm3). Between 40 and 50% of the cells had a DW of less than 20 fg. By assuming that carbon comprises 50% of the DW, the ratio of carbon content to Vof individual cells varied from 466 fg of C μm−3 forVs of 0.001 to 0.01 μm3 to 397 fg of C μm−3 (0.01 to 0.1 μm3) and 288 fg of C μm−3 (0.1 to 1 μm3). Exponentially growing and stationary cells of E. coli DSM 613 showed conversion factors of 254 fg of C μm−3 (0.1 to 1 μm3) and 211 fg of C μm−3 (1 to 4 μm3), respectively. Our data suggest that bacterial biomass in aquatic environments is higher and more variable than previously assumed from volume-based measurements.

Highly Efficient Photocatalytic Disinfection of Escherichia coli by Rose Bengal-Functionalized Graphene Oxide Nanosheets

2020 ◽  
Vol 20 (12) ◽  
pp. 7558-7568
Author(s):  
Fenping Chi ◽  
Pengpeng Chen ◽  
Changjie Mao
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Rose Bengal ◽  
Photoelectron Spectroscopy ◽  
Infrared Spectrometry ◽  
Ros Generation ◽  
Functionalized Graphene Oxide ◽  
E Coli ◽  
Transmission Electron ◽  
Sterilization Effect

Rose Bengal (RB) was used as a functional pigment and poly dimethyl diallyl ammonium chloride was used as a coupling agent to modify Graphene Oxide (GO) in order to enhance the light absorption and ROS generation of GO. GO, RB and the obtained RB-PDDA-GO were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry, thermogravimetric analysis, Raman spectroscopy, UV-visible spectrophotometry, and X-ray photoelectron spectroscopy. The oxidation of hydroquinone to p-benzoquinone was used to evaluate the oxidation ability. Three kinds of reactive oxygen species (O2·-, 1O2 and ·OH) produced by the materials under light irradiation were detected by the ESR method using TEMP (2,2,6,6-tetramethyl-4-piperidine) and DMPO (5,5-dimethyl-1-pyrroline-N-oxide) as capture agents. The results showed that RB-PDDA-GO produced more ROS under light than GO. Antibacterial experiments were carried out with E. coli as the target strain to detect the actual utility of ROS produced by the materials. The results showed that RB-PDDA-GO had a significant sterilization effect.

Screening of Condensed Tannins from Canadian Prairie Forages for Anti–Escherichia coli O157:H7 with an Emphasis on Purple Prairie Clover (Dalea purpurea Vent)†

2013 ◽  
Vol 76 (4) ◽  
pp. 560-567 ◽  
Author(s):  
Y. WANG ◽  
L. JIN ◽  
K. H. OMINSKI ◽  
M. HE ◽  
Z. XU ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Transmission Electron Microscopy ◽  
Condensed Tannins ◽  
Brown Seaweed ◽  
Coli Strain ◽  
Escherichia Coli O157 ◽  
Canadian Prairie ◽  
E Coli ◽  
Transmission Electron

Tannins from forages grown (n = 10) on the Canadian prairie, as well as from Quebracho, Rhus semialata, and brown seaweed (Ascophyllum nodosum), were screened for anti–Escherichia coli O157:H7 activity against E. coli O157:H7 strain 3081 at a concentration of 400 μg/ml for each tannin type, except for brown seaweed, which was at 50 μg/ml. Growth of the bacteria was assessed by measuring the optical density at 600 nm over 24 h. Tannin from seaweed at a concentration of 50 μg/ml inhibited growth of strain 3081. Among the terrestrial forages, only condensed tannins (CT) from purple prairie clover (Dalea purpurea Vent; PPC) increased (P < 0.05) the lag time and reduced (P < 0.05) the growth rate of E. coli O157:H7. The anti–E. coli O157:H7 activity of PPC CT was further assessed by culturing E. coli strain ATCC 25922 and eight strains of E. coli O157:H7 with PPC CT at 0, 25, 50, 100, or 200 μg/ml. Selected strains were enumerated after 0, 6, and 24 h of incubation, and fatty acid composition was determined after 24 h of incubation. E. coli strain 25922 was cultured with 0, 50, or 200 μg of CT per ml and harvested during the exponential growth phase for examination by transmission electron microscopy. Increasing CT concentration linearly increased (P < 0.001) the lag times of seven strains and linearly reduced (P < 0.001) the growth rates of eight E. coli O157:H7 strains. Proportions of unsaturated fatty acids in the total fatty acids were decreased (P < 0.01) by CT at 50 μg/ml. Transmission electron microscopy showed that CT disrupted the outer membrane structure. Anti–E. coli O157:H7 activity of PPC CT at levels of up to 200 μg/ml was bacteriostatic rather than bactericidal, and the mechanism of anti–E. coli activity may involve alteration in the fatty acid composition and disruption of the outer membrane of the cell.

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