The ΔuvrB mutations in the Ames strains of Salmonella span 15 to 119 genes

Takamune²,

et al. 2013

Genes and Environment

We present here a mutation assay with little bias which incorporates high-throughput DNA sequencing technology. Our strategy is simple: 1) expose cells to a test compound, 2) isolate colonies, and 3) carry out whole-genome sequencing of the clones. In this pilot study, we used Salmonella typhimurium TA100 as a tester strain and successfully detected mutations induced by the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide (AF-2). We believe that this new mutation assay will be a very useful tool in hazard assessment of chemicals.

Section: Resultssupporting

confidence: 90%

“…Assuming we are able to determine the`real' spontaneous mutation frequency, we could then calculate the probability that all of the observed mutations are spontaneous mutations. Spontaneous mutation is rare event and occurs randomly, so that it follows the Poisson distribution [1] shown below:…”

Section: Resultsmentioning

confidence: 99%

A Pilot Study for the Mutation Assay Using a High-throughput DNA Sequencer

Takamune²,

et al. 2013

Genes and Environment

Proc. Natl. Acad. Sci. U.S.A.

“…S. enterica serovar Typhimurium DNA microarrays were prepared by printing PCR amplicons representing Ϸ99% of the genome onto aminosilanecoated slides by using GeneMachine OmniGrid Array Maker (Genomic Instrumentation Services, San Carlos, CA), as described previously (14). Each DNA sample was printed in triplicate on each slide.…”

Section: Methodsmentioning

confidence: 99%

Microarray analysis identifies Salmonella genes belonging to the low-shear modeled microgravity regulon

Wilson

Ramamurthy

Porwollik

et al. 2002

Self Cite

152

191

The low-shear environment of optimized rotation suspension culture allows both eukaryotic and prokaryotic cells to assume physiologically relevant phenotypes that have led to significant advances in fundamental investigations of medical and biological importance. This culture environment has also been used to model microgravity for ground-based studies regarding the impact of space flight on eukaryotic and prokaryotic physiology. We have previously demonstrated that low-shear modeled microgravity (LSMMG) under optimized rotation suspension culture is a novel environmental signal that regulates the virulence, stress resistance, and protein expression levels of Salmonella enterica serovar Typhimurium. However, the mechanisms used by the cells of any species, including Salmonella, to sense and respond to LSMMG and identities of the genes involved are unknown. In this study, we used DNA microarrays to elucidate the global transcriptional response of Salmonella to LSMMG. When compared with identical growth conditions under normal gravity (1 ؋ g), LSMMG differentially regulated the expression of 163 genes distributed throughout the chromosome, representing functionally diverse groups including transcriptional regulators, virulence factors, lipopolysaccharide biosynthetic enzymes, iron-utilization enzymes, and proteins of unknown function. Many of the LSMMG-regulated genes were organized in clusters or operons. The microarray results were further validated by RT-PCR and phenotypic analyses, and they indicate that the ferric uptake regulator is involved in the LSMMG response. The results provide important insight about the Salmonella LSMMG response and could provide clues for the functioning of known Salmonella virulence systems or the identification of uncharacterized bacterial virulence strategies.

Mutation Research/Fundamental and Molecular Mechanisms of Mutag

“…The nucleotide repair-deficient (NER − ) strain NR11634 harbors a point mutation in the uvrB gene (uvrB5) rather than the large deletion in the region of the uvrB and bio genes found in Salmonella TA98, TA100, and TA104 [20]. NR11634 is a gal + revertant of NR10234 (galK2), which has been described [21], and was tested for UV sensitivity.…”

Section: Bacterial Strainsmentioning

confidence: 99%

Inhibition of spontaneous mutagenesis by vanillin and cinnamaldehyde in Escherichia coli: Dependence on recombinational repair

Shaughnessy

Schaaper

Umbach

et al. 2006

Self Cite

Vanillin (VAN) and cinnamaldehyde (CIN) are dietary antimutagens that effectively inhibit both induced and spontaneous mutations. We have shown previously that VAN and CIN reduced the spontaneous mutant frequency in Salmonella TA104 (hisG428, rfa, ΔuvrB, pKM101) by approximately 50% and that both compounds significantly reduced mutations at GC sites but not at AT sites. Previous studies have suggested that VAN and CIN may reduce mutations in bacterial model systems by modulating DNA repair pathways, particularly by enhancing recombinational repair. To further explore the basis for inhibition of spontaneous mutation by VAN and CIN, we have determined the effects of these compounds on survival and mutant frequency in five Escherichia coli strains derived from the wild-type strain NR9102 with different DNA repair backgrounds. At nontoxic doses, both VAN and CIN significantly reduced mutant frequency in the wild-type strain NR9102, in the nucleotide excision repair-deficient strain NR11634 (uvrB), and in the recombination-proficient but SOS-deficient strain NR11475 (recA430). In contrast, in the recombination-deficient and SOS-deficient strain NR11317 (recA56), both VAN and CIN not only failed to inhibit the spontaneous mutant frequency but actually increased the mutant frequency. In the mismatch repair-defective strain NR9319 (mutL), only CIN was antimutagenic. Our results show that the antimutagenicity of VAN and CIN against spontaneous mutation required the RecA recombination function but was independent of the SOS and nucleotide excision repair pathways. Thus, we propose the counterintuitive notion that these antimutagens actually produce a type of DNA damage that elicits recombinational repair (but not mismatch, SOS, or nucleotide excision repair), which then repairs not only the damage induced by VAN and CIN but also other DNA damageresulting in an antimutagenic effect on spontaneous mutation.