scholarly journals Effect of Ciprofloxacin on Shiga Toxin Production and Translocation across an Intestinal Epithelial Monolayer

1999 ◽  
Vol 45 (4, Part 2 of 2) ◽  
pp. 163A-163A
Author(s):  
Jenifer L Jaeger ◽  
David Acheson
Keyword(s):  
Shiga Toxin ◽  
Toxin Production ◽  
Intestinal Epithelial ◽  
Epithelial Monolayer

scholarly journals Comparative Genomics and Characterization of the Late Promoter pR’ from Shiga Toxin Prophages in Escherichia coli

Viruses ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 595 ◽  
Author(s):  
Ling Zhang ◽  
David Simpson ◽  
Lynn McMullen ◽  
Michael Gänzle
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Toxin Production ◽  
Late Promoter ◽  
Regulatory Systems ◽  
Human Illness ◽  
Late Transcription ◽  
Native Strains ◽  
Native Host

Shiga-toxin producing Escherichia coli (STEC) causes human illness ranging from mild diarrhea to death. The bacteriophage encoded stx genes are located in the late transcription region, downstream of the antiterminator Q. The transcription of the stx genes is directly under the control of the late promoter pR’, thus the sequence diversity of the region between Q and stx, here termed the pR’ region, may affect Stx toxin production. Here, we compared the gene structure of the pR’ region and the stx subtypes of nineteen STECs. The sequence alignment and phylogenetic analysis suggested that the pR’ region tends to be more heterogeneous than the promoter itself, even if the prophages harbor the same stx subtype. Furthermore, we established and validated transcriptional fusions of the pR’ region to the DsRed reporter gene using mitomycin C (MMC) induction. Finally, these constructs were transformed into native and non-native strains and examined with flow cytometry. The results showed that induction levels changed when pR’ regions were placed under different regulatory systems. Moreover, not every stx gene could be induced in its native host bacteria. In addition to the functional genes, the diversity of the pR’ region plays an important role in determining the level of toxin induction.

scholarly journals Inhibition of Matriptase Activity Results in Decreased Intestinal Epithelial Monolayer Integrity In Vitro

PLoS ONE ◽  
2015 ◽  
Vol 10 (10) ◽  
pp. e0141077 ◽  
Author(s):  
E. Pászti-Gere ◽  
S. McManus ◽  
N. Meggyesházi ◽  
P. Balla ◽  
P. Gálfi ◽  
...  
Keyword(s):  
Intestinal Epithelial ◽  
Epithelial Monolayer

Influence of Cultural Conditions on Cytotoxin Production by Salmonella enteritidis

1992 ◽  
Vol 55 (1) ◽  
pp. 28-33 ◽  
Author(s):  
RATIH DEWANTI ◽  
MICHAEL P. DOYLE
Keyword(s):  
Shiga Toxin ◽  
Salmonella Enteritidis ◽  
Incubation Temperature ◽  
Vero Cells ◽  
Toxin Production ◽  
Growth Media ◽  
Optimal Conditions ◽  
Early Stationary Phase ◽  
Cultural Conditions ◽  
Optimal Ph

The ability of Salmonella enteritidis strain 11013 to produce cytotoxic activity against Vero cells was determined under different cultural conditions. The toxin, which was not neutralizable with antiserum to Shiga toxin or Escherichia coli verotoxin-1 or verotoxin-2, was principally cell-associated and was produced primarily during the early stationary phase of growth. Trypticase soy broth was the best of three media evaluated for toxin production. Bacteria produced toxin in the range of pH 4.5 to 8.0 and at 12 to 42°C, with the optimal pH and temperature for toxin production at pH 7.0 and 37°C, respectively. Release of cellular cytotoxin into growth media was induced by growing salmonellae at extremes of pH (4.5 or 8.0) or at high incubation temperature (42°C). The Vero cell CD50 of S. enteritidis lysates of cells grown under optimal conditions was a titer of 150 ± 50 per mg of lysate protein. Although the significance of ingesting preformed Salmonella cytotoxin in human disease is unknown, it can be implied from these results that toxin would not be produced in foods held refrigerated at ≤7°C or acidified at ≤pH 4.0.

Reversible disassembly of an intestinal epithelial monolayer by prolonged exposure to phorbol ester

1994 ◽  
Vol 266 (2) ◽  
pp. G214-G221 ◽  
Author(s):  
G. Hecht ◽  
B. Robinson ◽  
A. Koutsouris
Keyword(s):  
Tight Junction ◽  
Phorbol Ester ◽  
Barrier Function ◽  
Prolonged Exposure ◽  
Morphological Changes ◽  
Cell Types ◽  
Intestinal Epithelial ◽  
Epithelial Monolayer ◽  
Epithelial Barrier Function ◽  
Functional Changes

This article describes a model of reversible disassembly of a cultured human intestinal epithelial monolayer by prolonged exposure to the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). Prolonged phorbol ester exposure reduces protein kinase C (PKC) levels in numerous cell types including T84, as shown here. Under PKC-downregulated conditions, T84 monolayers, which simulate the highly organized structure of native intestinal crypt cells, become disassembled into 2 or 3 layers of rounded cells. Proliferation does not account for these morphological changes as assessed by thymidine incorporation studies. The effects of structural disorganization on epithelial barrier function was also examined. The permeability of disassembled monolayers was significantly greater than that of controls. Flux studies localized the permeability defect to the tight junction. PKC-associated alterations in the perijunctional ring of actin and myosin, one of the putative regulators of flow across the tight junction, were found to correlate with the observed functional changes. Most interesting was the fact that monolayer reassembly to the original columnar epithelial phenotype and reestablishment of barrier function occurred upon normalization of PKC levels. This model of reversible monolayer disassembly will allow investigation into the relationship between epithelial structure and function and examination of factors that govern monolayer formation.

scholarly journals Replication of plasmids derived from Shiga toxin-converting bacteriophages in starved Escherichia coli

Microbiology ◽  
2011 ◽  
Vol 157 (1) ◽  
pp. 220-233 ◽  
Author(s):  
Bożena Nejman ◽  
Beata Nadratowska-Wesołowska ◽  
Agnieszka Szalewska-Pałasz ◽  
Alicja Węgrzyn ◽  
Grzegorz Węgrzyn
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Transcriptional Activation ◽  
Stringent Response ◽  
Toxin Production ◽  
Replication Initiation ◽  
Host Cells ◽  
Regulation Of Transcription ◽  
E Coli ◽  
Dna Replication Initiation

The pathogenicity of Shiga toxin-producing Escherichia coli (STEC) depends on the expression of stx genes that are located on lambdoid prophages. Effective toxin production occurs only after prophage induction, and one may presume that replication of the phage genome is important for an increase in the dosage of stx genes, positively influencing their expression. We investigated the replication of plasmids derived from Shiga toxin (Stx)-converting bacteriophages in starved E. coli cells, as starvation conditions may be common in the intestine of infected humans. We found that, unlike plasmids derived from bacteriophage λ, the Shiga toxin phage-derived replicons did not replicate in amino acid-starved relA + and relA − cells (showing the stringent and relaxed responses to starvation, respectively). The presence of the stable fraction of the replication initiator O protein was detected in all tested replicons. However, while ppGpp, the stringent response effector, inhibited the activities of the λ P R promoter and its homologues from Shiga toxin-converting bacteriophages, these promoters, except for λ P R, were only weakly stimulated by the DksA protein. We suggest that this less efficient (relative to λ) positive regulation of transcription responsible for transcriptional activation of the origin contributes to the inhibition of DNA replication initiation of Shiga toxin-converting bacteriophages in starved host cells, even in the absence of ppGpp (as in starved relA − hosts). Possible clinical implications of these results are discussed.

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