Environmental and Molecular Mutagenesis
1098-2280
0893-6692
Mỹ
Cơ quản chủ quản: WILEY , Wiley-Liss Inc.
Lĩnh vực:
EpidemiologyGenetics (clinical)Health, Toxicology and Mutagenesis
Các bài báo tiêu biểu
Meat‐related mutagens/carcinogens in the etiology of colorectal cancer Abstract Diets containing substantial amounts of red or preserved meats may increase the risk of various cancers, including colorectal cancer. This association may be due to a combination of factors such as the content of fat, protein, iron, and/or meat preparation (e.g., cooking or preserving methods). Red meat may be associated with colorectal cancer by contributing to N ‐nitroso compound (NOC) exposure. Humans can be exposed to NOCs by exogenous routes (from processed meats in particular) and by endogenous routes. Endogenous exposure to NOCs is dose‐dependently related to the amount of red meat in the diet. Laboratory results have shown that meats cooked at high temperatures contain other potential mutagens in the form of heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). To investigate the role of these compounds, we have created separate databases for HCAs and PAHs, which we have used in conjunction with a validated meat‐cooking food frequency questionnaire. The role of meat type, cooking methods, doneness levels, and meat‐cooking mutagens has been examined in both case‐control studies and prospective cohort studies, with mixed results. Here, we review the current epidemiologic knowledge of meat‐related mutagens, and evaluate the types of studies that may be required in the future to clarify the association between meat consumption and colorectal cancer. Environ. Mol. Mutagen. 44:44–55, 2004. Published 2004 Wiley‐Liss, Inc.
Tập 44 Số 1 - Trang 44-55 - 2004
Analysis of <i>Salmonella typhimurium hisD3052</i> revertants: The use of oligodeoxyribonucleotide colony hybridization, PCR, and direct sequencing in mutational analysis Abstract A rapid method for determining the DNA sequences of Salmonella typhimurium hisD3052 revertants is presented. DNA colony hybridization was used to analyze revertants previously studied by Isono and Yourno [Proc Natl Acad Sci USA 71:1612–1617, 1974]. Synthetic oligodeoxy‐ribonucleotide probes (18‐mers) were able to distinguish sequences that differed by a single base pair. Mutant his sequences not identified by probing analysis were amplified using polymerase chain reaction (PCR) and directly sequenced. The combined use of DNA‐colony hybridization and direct sequencing offers a precise and rapid means for the molecular characterization of hisD3052 revertants.
Tập 18 Số 4 - Trang 224-230 - 1991
Mutations induced by (−)‐<i>anti</i>‐11<i>R</i>,12<i>S</i>‐dihydrodiol 13<i>S</i>,14<i>R</i>‐epoxide of dibenzo[<i>a,l</i>]pyrene in the coding region of the hypoxanthine phosphoribosyltransferase (<i>Hprt</i>) gene in Chinese hamster V79 cells Abstract The polycyclic aromatic hydrocarbon dibenzo[a,l ]pyrene (DB[a,l ]P) is an exceptionally potent carcinogen. Its direct DNA‐reactive metabolite, the fjord region (−)‐anti ‐11R ,12S ‐dihydrodiol 13S ,14R ‐epoxide [(−)‐anti ‐DB[a,l ]PDE], was used to investigate induction of mutations in the coding region of the hypoxanthine phosphoribosyltransferase (Hprt ) gene in Chinese hamster V79 cells. Cells exposed to 1–10 nM (−)‐anti ‐DB[a,l ]PDE exhibited a close dose‐responsive increase in the frequency of mutant clones resistant to 6‐thioguanine. RNA was isolated from mutant clones and cDNAs were prepared by reverse transcription. The coding region of the cDNA of the Hprt gene was amplified by polymerase chain reaction and sequenced. Analysis of the DNA base sequence changes induced by (−)‐anti ‐DB[a,l ]PDE indicated that base substitutions were the most prevalent mutations, followed by exon deletions. Among the groups of V79 cells treated with low concentrations of (−)‐anti ‐DB[a,l ]PDE, most displayed high selectivity for both A:T→T:A transversions and A:T→G:C transitions, while cells exposed to a higher dose (10 nM) formed predominantly G:C→T:A transversions. Also, the number of base substitutions per mutant clone increased with dose. In general, the mutation profiles induced by (−)‐anti ‐DB[a,l ]PDE exhibited a wide spectrum; in addition to base substitutions, deletions, insertions, frameshift mutations, as well as tandem mutations were detected. Analysis of the DNA adduct levels induced by (−)‐anti ‐DB[a,l ]PDE revealed that a concentration‐dependent increase in the level of adduct formation preceded the concentration‐dependent increase in mutational events in these cells and that an increasing proportion of DNA adducts at deoxyadenosine were formed with dose. The results of this study demonstrate a correspondence between the concentration and types of DNA adducts and the frequency and types of mutations induced by (−)‐anti ‐DB[a,l ]PDE in V79 cells. Environ. Mol. Mutagen. 41:131–139, 2003. © 2003 Wiley‐Liss, Inc.
Tập 41 Số 2 - Trang 131-139 - 2003
mutation spectra in salmonella of complex mixtures: Comparison of urban air to benzo[a]pyrene Abstract We used an ion‐exchange procedure coupled to the Salmonella assay to fractionate the dichlo‐romethane‐extractable particulate organics from an urban air sample collected in Boise, ldaho. A resulting base/neutral fraction contained 81% of the mutagenic activity but only 36% of the mass of the unfractionated sample. Chemical analysis showed that polycyclic aromatic hydrocarbons (PAHs) accounted for much of the mutagenic activity of the air sample. Colony probe hybridization, PCR, and DNA sequence analysis were then used to determine the mutations induced by the complex mixtures and a model PAH, benzo[a]pyrene (BAP) in ∼900 revertants of the frameshift hisD3052 allele and ∼400 revertants of the base‐substitution hisG46 allele. The majority (93–94%) of the mutations induced at the frameshift allele in strain TA98 by the whole or base/neutral fraction of the urban air sample was a hotspot 2‐base deletion of a CG or GC within the sequence CGCGCGCG. The remaining mutations were complex frame‐shifts that consisted of −2 or +1 frameshifts associated with a flanking base substitution. BAP induced a somewhat similar pattern of mutations, with 70% being the hotspot mutation, 23% being complex frameshifts, and the remaining being deletions. The inferred base‐substitution specificity associated with the complex frame‐shifts at the hisD3052 allele (primarily G · C→T · A transversions) was consistent with the observation that this same transversion was the primary mutation induced by the whole urban air sample and BAP at the base‐substitution allele in strain TA100. At the frameshift allele, adducts that promote correct incorporation/slippage could account for hotspot mutations, whereas those that promote misincorporation/slippage could account for complex frameshifts. At the base‐substitution allele, a mixture of adducts or of adducts with multiple conformations could account for the observed proportion of transitions and transversions. Combined with the bioassay‐directed chemical analysis, these results from the first mutation spectra of a complex mixture suggest that such spectra reflect the dominance of particular classes of chemical mutagens within the mixture. © 1994 Wiley‐Liss, Inc.
Tập 24 Số 4 - Trang 262-275 - 1994
Assessment of multiple types of DNA damage in human placentas from smoking and nonsmoking women in the Czech Republic Abstract Three classes of DNA damage were assessed in human placentas collected (2000–2004) from 51 women living in the Teplice region of the Czech Republic, a mining area considered to have some of the worst environmental pollution in Europe in the 1980s. Polycyclic aromatic hydrocarbon (PAH)‐DNA adducts were localized and semiquantified using immunohistochemistry (IHC) and the Automated Cellular Imaging System (ACIS). More generalized DNA damage was measured both by 32 P‐postlabeling and by abasic (AB) site analysis. Placenta stained with antiserum elicited against DNA modified with 7β,8α‐dihydroxy‐9α,10α‐epoxy‐7,8,9,10‐tetrahydro‐benzo[a ]pyrene (BPDE) revealed PAH‐DNA adduct localization in nuclei of the cytotrophoblast (CT) cells and syncytiotrophoblast (ST) knots lining the chorionic villi. The highest levels of DNA damage, 49‐312 PAH‐DNA adducts/108 nucleotides, were found by IHC/ACIS in 14 immediately fixed placenta samples. An additional 37 placenta samples were stored frozen before fixation and embedding, and because PAH‐DNA adducts were largely undetectable in these samples, freezing was implicated in the loss of IHC signal. The same placentas (n = 37) contained 1.7–8.6 stable/bulky DNA adducts/108 nucleotides and 0.6–47.2 AB sites/105 nucleotides. For all methods, there was no correlation among types of DNA damage and no difference in extent of DNA damage between smokers and nonsmokers. Therefore, the data show that DNA from placentas obtained in Teplice contained multiple types of DNA damage, which likely arose from various environmental exposures. In addition, PAH‐DNA adducts were present at high concentrations in the CT cells and ST knots of the chorionic villi. Environ. Mol. Mutagen. 52:58–68, 2011. © 2010 Wiley‐Liss, Inc.
Tập 52 Số 1 - Trang 58-68 - 2011
Enhanced mutagenesis of <i>Salmonella</i> tester strains due to deletion of genes other than <i>uvrB</i> Abstract The standard Salmonella mutagenicity (Ames) tester strains are missing 15–119 genes due to the extended Δ(gal‐bio‐uvrB ) mutations that render the strains excision‐repair deficient (ΔuvrB ). We constructed strains of Salmonella that are homologous to tester strains TA98 and TA100 except that in place of the uvrB deletion, they contain single‐gene defects in either uvrB, moaA, moeA, or both uvrB and moeA . We then tested the following mutagens in these strains: 2‐acetylaminofluorene, Glu‐P‐1, 4‐aminobiphenyl, benzo[a ]pyrene, MX, 1‐nitropyrene, 6‐hydroxylaminopurine (HAP), and 2‐amino‐6‐hydroxylaminopurine (AHAP). We confirmed in Salmonella a previous finding in Escherichia coli that the enhanced mutagenicity of the purine analogues HAP and AHAP is not due to the deletion of the uvrB gene but due to the deletion of moeA and/or moaA , which are involved in molybdenum cofactor biosynthesis. The spontaneous mutant frequency and induced mutagenic potency of mutagens due to the extended ΔuvrB mutation are due largely to the deletion of uvrB and to some extent of moeA/moaA at the frameshift hisD3052 allele of TA98 but involve other genes in addition to uvrB and moeA/moaA at the base‐substitution hisG46 allele of TA100. The extended ΔuvrB mutation does not prevent the detection of mutagens that would have been detected in a strain containing a single uvrB defect. Because of the deletion of moeA/moaA , the extended uvrB deletion generally enhanced spontaneous and induced mutagenicity, especially at the base‐substitution allele. This enhanced sensitivity may underlay the severe health effects in humans who have mutations in molybdenum cofactor biosynthesis genes. Environ. Mol. Mutagen., 2007. © 2007 Wiley‐Liss, Inc.
Tập 48 Số 8 - Trang 694-705 - 2007
Mice exposed in situ to urban air pollution exhibit pulmonary alterations in gene expression in the lipid droplet synthesis pathways It is clear that particulate air pollution poses a serious risk to human health; however, the underlying mechanisms are not completely understood. We investigated pulmonary transcriptional responses in mice following in‐situ exposure to ambient air in a heavily industrialized urban environment. Mature C57BL/CBA male mice were caged in sheds near two working steel mills and a major highway in Hamilton, Ontario, Canada in the spring/summer of 2004. Control mice were housed in the same environment, but received only high‐efficiency particle filtered air (HEPA). Whole lung tissues were collected from mice exposed for 3, 10, or for 10 weeks followed by 6 weeks recovery in the laboratory (16 weeks). DNA microarrays were used to profile changes in pulmonary gene expression. Transcriptional profiling revealed changes in the expression of genes implicated in the lipid droplet synthesis (Plin I, Dgat2, Lpl, S3‐12, andAgpat2 ), and antioxidant defense (Ucp1 ) pathways in mice breathing unfiltered air. We postulate that exposure to urban air, containing an abundance of particulate matter adsorbed with polycyclic aromatic hydrocarbons, triggers lipid droplet (holding depots for lipids and malformed/excess proteins tagged for degradation) synthesis in the lungs, which may act to sequester particulates. Increased lipid droplet synthesis could lead to endogenous/stressor‐induced production of reactive oxygen species and activation of antioxidant mechanisms. Further investigation into the stimulation of lipid droplet synthesis in the lung in response to air pollution and the resulting health implications is warranted. Environ. Mol. Mutagen. 54:240–249, 2013. © 2013 Wiley Periodicals, Inc.
Tập 54 Số 4 - Trang 240-249 - 2013
Redox state alters anti‐cancer effects of wedelolactone Abstract Wedelolactone is one of the active plant polyphenolic compounds. Anti‐tumor effects of this drug have been demonstrated recently. We have described that wedelolactone acts as catalytic inhibitor of DNA topoisomerase IIα. The aim of this study was to further characterize the mechanism of its anti‐tumor effects. We showed that wedelolactone inhibits binding of DNA topoisomerase IIα to plasmid DNA and antagonizes formation of etoposide‐induced DNA cleavage complex. The inhibition of topoisomerase IIα by wedelolactone is reversible by excess of the enzyme but not DNA. The in vitro inhibitory effect of wedelolactone on the topoisomerase IIα activity is redox‐dependent as it diminished in the presence of reducing agents. Cytotoxicity of wedelolactone was partially inhibited by N ‐acetylcysteine and glutathione ethyl ester in breast cancer MDA‐MB‐231 and MDA‐MB‐468 cells while the inhibitory effect of catalase was observed only in the former cell line. Finally, we found that wedelolactone can be oxidized in the presence of copper ions resulting in DNA strand break and abasic site formation in vitro . However, wedelolactone induced neither DNA damage in MDA‐MB‐231 cells nor mutations in bacterial cells detectable by Ames test suggesting that wedelolactone may not be an effective inducer of DNA damage. We conclude that the topoisomerase IIα inhibitory‐ and DNA damaging activities of wedelolactone in vitro depend on its redox state. Pro‐oxidant activity could, however, explain only part of wedelolactone‐induced cytotoxicity. Therefore, the major cellular target(s) of wedelolactone and the exact mechanism of wedelolactone‐induced cytotoxicity still remain to be identified. Environ. Mol. Mutagen. 2012. © 2012 Wiley Periodicals, Inc.
Tập 53 Số 7 - Trang 515-524 - 2012
Single‐strand breaks, chromosome aberrations, sister‐chromatid exchanges, and micronuclei in blood lymphocytes of workers exposed to styrene during the production of reinforced plastics Abstract Chromosome aberrations (CA), micronuclei (MN, cytokinesis‐block [CB] method), and sister‐chromatid exchanges (SCE) were analysed in blood lymphocytes of 17 workers and 17 control subjects. The mean urinary mandelic acid level (average 9.4 mmol/1) and styrene glycol in blood (average 2.5 μmol/1) implied exposure to about 300 mg/m3 of styrene in the plant. The number of CA was significantly higher in non‐smoking workers compared with nonsmoking controls. A significant correlation was observed between duration of exposure and individual CA level of all workers. No significant effects were observed in MN or SCE. Single‐strand breaks (SSB) in DNA of isolated lymphocytes were studied in nine of the workers and eight of the controls by the DNA‐unwinding technique. The results showed an increase in SSB among the exposed workers. The present findings support earlier reports on the increase of structural CA in blood lymphocytes of workers in the reinforced plastic industry, and also show that SSBs are elevated in such workers.
Tập 17 Số 1 - Trang 27-31 - 1991
Detection of ghost cells in the standard alkaline comet assay is not a good measure of apoptosis Abstract The single cell gel electrophoresis assay, or Comet assay, is a powerful tool for measurement of DNA strands breaks, oxidative damage, and alkali labile sites, and the assay was recently modified to detect DNA cross‐links. It has also been proposed as a measure of apoptosis since apoptotic cells are suspected to result in total migration of the DNA from the nucleus into the tail. Cells with this appearance are called ghost cells, clouds, hedgehogs, or NDCN (nondetectable cell nuclei). The aim of this study was to determine if ghost cells can be used to measure apoptosis in the standard alkaline comet assay. To answer this question, we made use of two cell lines: CTLL‐2 cells that can enter apoptosis upon addition of apoptosis stimuli or IL‐2 deprivation, and CTLL‐2 bcl2 cells that are protected from apoptosis due to the overexpression of the apoptosis inhibitor gene bcl2 . The two cell lines were treated with cytotoxins (nongenotoxic apoptosis inducers, nongenotoxic necrotic agents) or genotoxins. They were also subjected to growth factor withdrawal, which induced apoptosis in the CTLL‐2 cell line. The level of apoptosis was measured by the Annexin V‐FITC method in parallel with performing the Comet assay. The results obtained in the two cell lines suggest that apoptotic or necrotic death does not correlate well with the detection of ghost cells, presumably because these cells are lost upon electrophoresis. A variant of the alkaline Comet assay that was performed without electrophoresis (halo method) was able to efficiently detect cells undergoing apoptosis, but it was unable to clearly distinguish between apoptosis and genotoxic damage. Environ. Mol. Mutagen. 41:260–269, 2003. © 2003 Wiley‐Liss, Inc.
Tập 41 Số 4 - Trang 260-269 - 2003