A study of the genotoxic potential of flavonoids using short-term bacterial assays.

Genotoxic activities of flavonoids (quercetin, rhamnetin, isorhamnetin, apigenin, luteolin) were investigated using two short-term bacterial assays. In the "repair test" in Salmonella typhimurium (strains TA1538 uvrB- and TA1978 uvrB+) the flavonoids studied did not introduce any damage into the DNA recognized by UvrABC nuclease (correndonuclease II). The results of the SOS-Chromotest in Escherichia coli K-12 strains PQ37 (tag+, alk+) and PQ243 (tagA, alkA) indicated that flavonoids only weakly induced the SOS system. The addition of a liver activation system (S9 mix) did not increase the mutagenic effect of the flavonoids tested. Two compounds: rhamnetin, isorhamnetin and their putative metabolites formed in the presence of the S9 mix did not alkylate DNA at N-3 of adenine.

Download Full-text

Comparison of lipopolysaccharide biosynthesis genes rfaK, rfaL, rfaY, and rfaZ of Escherichia coli K-12 and Salmonella typhimurium.

Journal of Bacteriology ◽

10.1128/jb.174.14.4746-4752.1992 ◽

1992 ◽

Vol 174 (14) ◽

pp. 4746-4752 ◽

Cited By ~ 29

Author(s):

J D Klena ◽

E Pradel ◽

C A Schnaitman

Keyword(s):

Escherichia Coli ◽

Salmonella Typhimurium ◽

Lipopolysaccharide Biosynthesis ◽

K 12

Download Full-text

Nucleotide sequence of the metH gene of Escherichia coli K-12 and comparison with that of Salmonella typhimurium LT2

Gene ◽

10.1016/0378-1119(90)90490-i ◽

1990 ◽

Vol 87 (1) ◽

pp. 15-21 ◽

Cited By ~ 21

Author(s):

Iain G. Old ◽

Danielle Margarita ◽

Robert E. Glass ◽

Isabelle Saint Girons

Keyword(s):

Escherichia Coli ◽

Nucleotide Sequence ◽

Salmonella Typhimurium ◽

K 12

Download Full-text

Transcriptional Responses of Escherichia coli K-12 and O157:H7 Associated with Lettuce Leaves

Applied and Environmental Microbiology ◽

10.1128/aem.07454-11 ◽

2012 ◽

Vol 78 (6) ◽

pp. 1752-1764 ◽

Cited By ~ 64

Author(s):

Ryan C. Fink ◽

Elaine P. Black ◽

Zhe Hou ◽

Masayuki Sugawara ◽

Michael J. Sadowsky ◽

...

Keyword(s):

Escherichia Coli ◽

Molecular Mechanisms ◽

Leaf Surface ◽

Short Term ◽

Transcriptional Responses ◽

Content Type ◽

E Coli ◽

Leaf Surfaces ◽

K 12

ABSTRACTAn increasing number of outbreaks of gastroenteritis recently caused byEscherichia coliO157:H7 have been linked to the consumption of leafy green vegetables. Although it is known thatE. colisurvives and grows in the phyllosphere of lettuce plants, the molecular mechanisms by which this bacterium associates with plants are largely unknown. The goal of this study was to identifyE. coligenes relevant to its interaction, survival, or attachment to lettuce leaf surfaces, comparingE. coliK-12, a model system, andE. coliO157:H7, a pathogen associated with a large number of outbreaks. Using microarrays, we found that upon interaction with intact leaves, 10.1% and 8.7% of the 3,798 shared genes were differentially expressed in K-12 and O157:H7, respectively, whereas 3.1% changed transcript levels in both. The largest group of genes downregulated consisted of those involved in energy metabolism, includingtnaA(33-fold change), encoding a tryptophanase that converts tryptophan into indole. Genes involved in biofilm modulation (bhsAandybiM) and curli production (csgAandcsgB) were significantly upregulated inE. coliK-12 and O157:H7. BothcsgAandbhsA(ycfR) mutants were impaired in the long-term colonization of the leaf surface, but onlycsgAmutants had diminished ability in short-term attachment experiments. Our data suggested that the interaction ofE. coliK-12 and O157:H7 with undamaged lettuce leaves likely is initiated via attachment to the leaf surface using curli fibers, a downward shift in their metabolism, and the suppression of biofilm formation.

Download Full-text

Studies of error-prone DNA repair in Escherichia coli K-12 and Ames Salmonella typhimurium strains using a model alkylating agent

Mutagenesis ◽

10.1093/mutage/4.2.90 ◽

1989 ◽

Vol 4 (2) ◽

pp. 90-94 ◽

Cited By ~ 6

Author(s):

C.A. Little ◽

D.J. Tweats ◽

R.J. Pinney

Keyword(s):

Escherichia Coli ◽

Dna Repair ◽

Salmonella Typhimurium ◽

Alkylating Agent ◽

K 12

Download Full-text

Plasmid studies ofSalmonella typhimuriumphage type 179 resistant to ampicillin, tetracycline, sulphonamides and trimethoprim

Journal of Hygiene ◽

10.1017/s0022172400063336 ◽

1980 ◽

Vol 85 (2) ◽

pp. 293-300 ◽

Cited By ~ 9

Author(s):

D. M. Anderson

Keyword(s):

Escherichia Coli ◽

Molecular Weight ◽

New Zealand ◽

Salmonella Typhimurium ◽

National Health ◽

Gel Electrophoresis ◽

Phage Type ◽

Agarose Gel ◽

Agarose Gel Electrophoresis ◽

K 12

SUMMARYSixteen strains ofSalmonella typhimuriumphage type 179 were referred to the National Health Institute, Wellington, New Zealand, from 1977 to 1979. This phage type had not been observed here before 1977. All strains were resistant to ampicillin, several were also resistant to tetracycline, and several were resistant to ampicillin, tetracycline, sulphafurazele and trimethoprim. All resistances could be transferred toEscherichia coliK 12. Plasmids from these strains and their transconjugants were characterized by agarose gel electrophoresis. It appears that resistance to sulphafurazole and trimethoprim is carried on a plasmid with a molecular weight of 5·2 Mdal and that resistance to ampicillin and tetracycline is carried on a plasmid with a molecular weight of approximately 60 Mdal.

Download Full-text