Environmental and Molecular Mutagenesis via MedWorm.com

Genotoxicity of pesticide mixtures present in the diet of the French population

Environmental and Molecular Mutagenesis — Wed, 04 Jan 2012 05:00:00 +0100

AbstractConsumers may be simultaneously exposed to several pesticide residues in their diet. A previous study identified the seven most common pesticide mixtures to which the French population was exposed through food consumption in 2006. The aim of this study was to investigate if the seven mixtures are potentially cytotoxic and genotoxic and if so, whether compounds in a same mixture have a combined effect. The cytotoxicity and genotoxicity of the seven mixtures were investigated with a new assay (γ‐H2AX) using four human cell lines (ACHN, SH‐SY5Y, LS‐174T, and HepG2). Mixtures were tested at equimolar concentrations and also at concentrations reflecting their actual proportion in the diet. Irrespective of the cell line tested, parallel cytotoxicity of the seven mixtures was obser...

Uncoupling of RAD51 focus formation and cell survival after replication fork stalling in RAD51D null CHO cells

Environmental and Molecular Mutagenesis — Wed, 04 Jan 2012 05:00:00 +0100

AbstractIn vertebrate cells, the five RAD51 paralogs (XRCC2/3 and RAD51B/C/D) enhance the efficiency of homologous recombination repair (HRR). Stalling and breakage of DNA replication forks is a common event, especially in the large genomes of higher eukaryotes. When cells are exposed to agents that arrest DNA replication, such as hydroxyurea or aphidicolin, fork breakage can lead to chromosomal aberrations and cell killing. We assessed the contribution of the HRR protein RAD51D in resistance to killing by replication‐associated DSBs. In response to hydroxyurea, the isogenic rad51d null CHO mutant fails to show any indication of HRR initiation, as assessed by induction RAD51 foci, as expected. Surprisingly, these cells have normal resistance to killing by replication inhibition from eith...

DNA damage profiles induced by sunlight at different latitudes

Environmental and Molecular Mutagenesis — Sun, 01 Jan 2012 05:00:00 +0100

AbstractDespite growing knowledge on the biological effects of ultraviolet (UV) radiation on human health and ecosystems, it is still difficult to predict the negative impacts of the increasing incidence of solar UV radiation in a scenario of global warming and climate changes. Hence, the development and application of DNA‐based biological sensors to monitor the solar UV radiation under different environmental conditions is of increasing importance. With a mind to rendering a molecular view‐point of the genotoxic impact of sunlight, field experiments were undertaken with a DNA‐dosimeter system in parallel with physical photometry of solar UVB/UVA radiation, at various latitudes in South America. Onapplying biochemical and immunological approaches based on specific DNA‐repair enzyme...

International round‐robin study on the Ames fluctuation test

Environmental and Molecular Mutagenesis — Sun, 01 Jan 2012 05:00:00 +0100

AbstractAn international round‐robin study on the Ames fluctuation test [ISO 11350, 2012], a microplate version of the classic plate‐incorporation method for the detection of mutagenicity in water, wastewater and chemicals was performed by 18 laboratories from seven countries. Such a round‐robin study is a precondition for both the finalization of the ISO standardization process and a possible regulatory implementation in water legislation. The laboratories tested four water samples (spiked/nonspiked) and two chemical mixtures with and without supplementation of a S9‐mix. Validity criteria (acceptable spontaneous and positive control‐induced mutation counts) were fulfilled by 92–100%, depending on the test conditions. A two‐step method for statistical evaluation of the test r...

BRCA1 requirement for the fidelity of plasmid DNA double‐strand break repair in cultured breast epithelial cells

Environmental and Molecular Mutagenesis — Thu, 15 Dec 2011 05:00:00 +0100

We examined the frequency of microhomology‐mediated end joining (MMEJ) and the fidelity of DSB repair relative to BRCA1 protein levels in both control and tumorigenic breast epithelial cells. In addition to altered BRCA1 protein levels, we tested the effects of cellular exposure to mirin, an inhibitor of meiotic recombination enzyme 11 (Mre11) 3′–5′‐exonuclease activity. Knockdown or loss of BRCA1 protein resulted in an increased frequency of overall plasmid DNA mutagenesis and MMEJ following a DSB. Inhibition of Mre11‐exonuclease activity with mirin significantly decreased the occurrence of MMEJ, but did not considerably affect the overall mutagenic frequency of plasmid DSB repair. The results suggest that BRCA1 protects DNA from mutagenesis during nonhomologous DSB repair in ...

Polymorphisms in complement system genes and risk of non‐Hodgkin lymphoma

Environmental and Molecular Mutagenesis — Thu, 01 Dec 2011 05:00:00 +0100

AbstractThe complement system plays an important role in inflammatory and immune responses, and recent evidence has suggested that it may also play a role in lymphomagenesis. We evaluated the association between genetic variation in complement system genes and risk of non‐Hodgkin lymphoma (NHL) in a population‐based case–control study conducted among women in Connecticut. Tag SNPs in 30 complement genes were genotyped in 432 Caucasian incident cases and 494 frequency‐matched controls. A gene‐based analysis that adjusted for the number of tag SNPs genotyped in each gene showed a significant association with NHL overall (P = 0.04) as well as with diffuse large B‐cell lymphoma (DLBCL) (P = 0.01) for the C1RL gene. A SNP‐based analysis showed that a C>T base substitution for C...

Adapting the buccal micronucleus cytome assay for use in wild birds: Age and sex affect background frequency in pigeons

Environmental and Molecular Mutagenesis — Sat, 26 Nov 2011 10:49:23 +0100

AbstractMicronucleus (MN) formation has been used extensively as a biomarker of damage from genotoxic exposures. The Buccal MN Cytome (BMCyt) assay provides a noninvasive means of quantifying MN frequency in humans, but it has not been developed for use in wildlife. We adapted the BMCyt assay for use in wild birds, with a focus on feral pigeons (Columba livia) as a potential indicator species. Five of six urban bird species sampled using oral cavity swabs produced sufficient buccal cells for the BMCyt assay. The body size of species sampled ranged almost 100‐fold (∼60 to 5,000 g), but was a not major factor influencing the number of buccal cells collected. Pigeon cells were stained and scored following published BMCyt assay protocols for humans, but with a modified fixation approach us...

Roles of human sulfotransferases in genotoxicity of carcinogens using genetically engineered umu test strains

Environmental and Molecular Mutagenesis — Fri, 11 Nov 2011 10:29:16 +0100

AbstractHuman sulfotransferase (SULT) 1A1, 1A2, and 1A3 cDNA genes were subcloned separately into the pTrc99AKM vector. The generated plasmids were introduced into the Salmonella typhimuriumO‐acetyltransferase‐deficient strain NM6000 (TA1538/1,8‐DNP/pSK1002), resulting in the new strains NM7001, NM7002, and NM7003. We compared the sensitivities of these three strains with the parental strain NM7000 against 51 chemicals including aromatic amines, nitroarenes, alkenylbenzenes, estrogens‐like chemicals, and other compounds with and without S9 mix by making use of the umu test system that is based on the bacterial SOS induction. 2‐Amino‐6‐methyl‐dipyrido[1,2‐α:3′,2′‐d]imidazole, 3‐methoxy‐4‐aminoazobenzene, 3‐nitrobenzanthrone, 5‐nitroacenaphthene, and 3,9‐...

Comparison of Comet assay dose‐response for ethyl methanesulfonate using freshly prepared versus cryopreserved tissues

Environmental and Molecular Mutagenesis — Tue, 08 Nov 2011 05:00:00 +0100

AbstractThe National Toxicology Program (NTP) is using the Comet assay to evaluate genotoxic potential, and is investigating the integration of this assay into repeat‐dose toxicity studies. To reduce sample‐to‐sample variability, address logistical concerns associated with evaluating multiple tissues from many animals, and accommodate sample collection at geographically distant testing facilities, tissue samples collected for Comet analysis by the NTP are routinely flash‐frozen in liquid nitrogen and stored in a –80°C freezer until evaluation. To compare data obtained from frozen tissues to data from freshly isolated tissues, we conducted a dose‐response study in male Sprague Dawley rats. Rats (5 per treatment group) were administered ethyl methanesulfonate (EMS; 0, 25, 50, 10...

Investigations on cytotoxic and genotoxic effects of laser printer emissions in human epithelial A549 lung cells using an air/liquid exposure system

Environmental and Molecular Mutagenesis — Tue, 08 Nov 2011 05:00:00 +0100

AbstractExposure to emissions from laser printers during the printing process is commonplace worldwide, both in the home and workplace environment. In the present study, cytotoxic and genotoxic effects of the emission from five low to medium‐throughput laser printers were investigated with respect to the release of ozone (O3), volatile organic compounds (VOC), particulate matter (PM), and submicrometer particles (SMP) during standby and operation. Experiments were conducted in a 1 m3 emission chamber connected to a Vitrocell® exposure system. Cytotoxicity was determined by the WST‐1 assay and genotoxicity by the micronucleus test in human A549 lung cells. The five laser printers emitted varying but generally small amounts of O3, VOC, and PM. VOC emissions included 13 compounds with to...

Simultaneous measurement of benzo[a]pyrene‐induced Pig‐a and lacZ mutations, micronuclei and dna adducts in mutaTMmouse

Environmental and Molecular Mutagenesis — Fri, 04 Nov 2011 20:17:46 +0100

In this study we compared the response of the Pig‐a gene mutation assay to that of the lacZ transgenic rodent mutation assay, and demonstrated that multiple endpoints can be measured in a 28‐day repeat dose study. Muta™Mouse were dosed daily for 28 days with benzo[a]pyrene (BaP; 0, 25, 50 and 75 mg/kg body weight/day) by oral gavage. Micronucleus (MN) frequency was determined in reticulocytes (RETs) 48 hr following the last dose. 72 h following the last dose, mice were euthanized, and tissues (glandular stomach, small intestine, bone marrow and liver) were collected for lacZ mutation and DNA adduct analysis, and blood was evaluated for Pig‐a mutants. BaP‐derived DNA adducts were detected in all tissues examined and significant dose‐dependent increases in mutant Pig‐a phenotyp...

Intracellular and extracellular factors influencing Cr(VI and Cr(III) genotoxicity

Environmental and Molecular Mutagenesis — Fri, 21 Oct 2011 04:00:00 +0100

This study examines the molecular mechanism of Cr(VI) and Cr(III) genotoxicity in an intact cell. A system screening for DNA deletions (DEL assay) was used to compare induction of chromosomal rearrangements in the yeast Saccharomycescerevisiae following Cr(VI) and Cr(III) exposure. Both forms of chromium induced DNA deletions albeit with different dose‐response curves. N‐acetylcysteine had a protective effect against Cr(VI) genotoxicity at high exposure doses but had no protective effect at lower doses or against Cr(III). An oxidative DNA damage repair mutant was hypersensitive to Cr(VI) only at high exposure and the mutant was not hypersensitive to Cr(III) exposure. These data imply that oxidative stress is involved in Cr(VI) genotoxicity at high exposure concentrations and not so in ...

Report on stage III Pig‐a mutation assays using N‐ethyl‐N‐nitrosourea – comparison with other in vivo genotoxicity endpoints

Environmental and Molecular Mutagenesis — Wed, 05 Oct 2011 04:00:00 +0100

AbstractN‐Ethyl‐N‐nitrosourea (ENU) was evaluated as part of the Stage III trial for the rat Pig‐a gene mutation assay. Groups of six‐ to eight‐week‐old male Sprague Dawley (SD) or Fischer 344 (F344) rats were given 28 daily doses of the phosphate buffered saline vehicle, or 2.5, 5, or 10 mg/kg ENU, and evaluated for a variety of genotoxicity endpoints in peripheral blood, spleen, liver, and colon. Blood was sampled predose (Day‐1) and at various time points up to Day 57. Pig‐a mutant frequencies were determined in total red blood cells (RBCs) and reticulocytes (RETs) as RBCCD59− and RETCD59− frequencies. Consistent with the results from a reference laboratory, RBCCD59− and RETCD59− frequencies increased in a dose‐ and time‐dependent manner, producing signific...

In vitro toxicity and genotoxicity assessment of disinfection by‐products, organic N‐chloramines

Environmental and Molecular Mutagenesis — Wed, 05 Oct 2011 04:00:00 +0100

In this study, we investigated 16 organic N‐chloramines produced by chlorination of model amino acids and amines. It was found that within the drinking water‐relevant micromolar concentration range, four compounds were both cytotoxic and genotoxic to mammalian cells. A small reduction of cellular GSH was also observed in the treatment with these four compounds, but not of a magnitude to account for the cytotoxicity and genotoxicity. The results presented in this study demonstrate that some organic N‐chloramines, at low concentrations that might be present in disinfected water, can be harmful to mammalian cells. © Environ. Mol. Mutagen. 2011. Published 2011 Wiley‐Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Flexible use of qsar models in predictive toxicology: A case study on aromatic amines

Environmental and Molecular Mutagenesis — Wed, 05 Oct 2011 04:00:00 +0100

AbstractOver the last years, predictive toxicology approaches based on Structure–Activity Relationships have emerged as fundamental tools in the regulatory assessments of chemicals, especially in those programs where regulatory constraints and assessment schemes limit the amount of data available from experimental test methods. Both the qualitative (e.g., Structural Alerts) and the quantitative (Quantitative Structure–Activity Relationships, QSAR) approach can play important roles. However, the two approaches are not familiar to the same extent to the regulators that most often use only the qualitative approach, so that the potentiality of the more sophisticated QSAR approach is neglected. In fact, QSAR is a very flexible tool that allows the user to modulate its response according to ...

Manifestation and persistence of Pig‐a mutant red blood cells in C57BL/6 mice following single and split doses of N‐ethyl‐N‐nitrosourea

Environmental and Molecular Mutagenesis — Wed, 05 Oct 2011 04:00:00 +0100

AbstractTreating rats with single doses of N‐ethyl‐N‐nitrosourea (ENU) results in a time‐dependent accumulation of Pig‐a‐mutant phenotype peripheral red blood cells (RBCs), reaching a plateau at about 6‐weeks posttreatment, with the response persisting for at least 26 weeks. In the present study, groups of 5 C57BL/6 male mice were administered single i.p. doses of up to 140 mg/kg ENU, and blood samples were collected up to 26 weeks posttreatment. The samples were analyzed by flow cytometry for the frequency of CD24‐deficient (presumed Pig‐a mutant) reticulocytes (RETs) and total RBCs; micronucleated RET frequencies were evaluated at 1 day posttreatment. Mean Pig‐a mutant frequencies and micronucleated RET frequencies increased in a dose‐responsive manner, with maximum...

Further development of the rat Pig‐a mutation assay: Measuring rat Pig‐a mutant bone marrow erythroids and a high throughput assay for mutant peripheral blood reticulocytes

Environmental and Molecular Mutagenesis — Wed, 05 Oct 2011 04:00:00 +0100

AbstractRecent studies indicate that the Pig‐a assay is a promising tool for evaluating in vivo mutagenicity. We have developed novel rat Pig‐a assays that facilitate measuring mutant frequencies in two early arising populations of blood cells, bone marrow erythroids (BMEs) and peripheral blood (PB) reticulocytes (RETs). In these assays, bone marrow cells of erythroid origin and PB red blood cells (RBCs) were identified using an antibody against rat erythroid‐specific marker HIS49. In addition, RETs were selectivity enriched from PB using magnetic separation of cells positive for CD71, a transferrin receptor expressed on the surface of BMEs and RETs, but not on the surface of mature RBCs. With magnetic enrichment, more than 1 × 106 CD71‐positive RETs could be evaluated by flow cyt...

International Pig‐a gene mutation assay trial (Stage III): Results with N‐methyl‐N‐nitrosourea

Environmental and Molecular Mutagenesis — Wed, 05 Oct 2011 04:00:00 +0100

AbstractN‐methyl‐N‐nitrosourea (MNU) was evaluated in the in vivo Pig‐a mutation assay as part of an International Collaborative Trial to investigate laboratory reproducibility, 28‐day study integration, and comparative analysis with micronucleus (MN), comet, and clinical pathology endpoints. Male Sprague Dawley rats were treated for 28 days with doses of 0, 2.5, 5, and 10 mg MNU/kg/day in two independent laboratories, GlaxoSmithKline (GSK) and Bristol Myers Squibb (BMS). Additional studies investigated the low‐dose region (<2.5 mg/kg/day). Reticulocytes were evaluated for Pig‐a phenotypic mutation, CD59‐negative reticulocytes/erythrocytes (RETsCD59−/ RBCsCD59−) on Days 1, 4, 15, 29, 43, and 57, and for micronucleated reticulocytes (MN‐RETs) on Days 4 and 29. Comet...

Lower levels of oxidative DNA damage and apoptosis in lymphocytes from patients undergoing surgery with propofol anesthesia

Environmental and Molecular Mutagenesis — Wed, 05 Oct 2011 04:00:00 +0100

In conclusion, patients undergoing non‐invasive surgery under propofol anesthesia presented lower levels of oxidized purines and apoptosis of T helper lymphocytes. Furthermore, anesthesia with propofol did not directly influence the expression of the DNA repair genes hOGG1 and XRCC1 in blood cells. © Environ. Mol. Mutagen. 2011. Published 2011 Wiley‐Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Re‐evaluation of the big blue® mouse assay of propiconazole suggests lack of mutagenicity

Environmental and Molecular Mutagenesis — Wed, 05 Oct 2011 04:00:00 +0100

AbstractPropiconazole (PPZ) is a conazole fungicide that is not mutagenic, clastogenic, or DNA damaging in standard in vitro and in vivo genetic toxicity tests for gene mutations, chromosome aberrations, DNA damage, and cell transformation. However, it was demonstrated to be a male mouse liver carcinogen when administered in food for 24 months only at a concentration of 2,500 ppm that exceeded the maximum tolerated dose based on increased mortality, decreased body weight gain, and the presence of liver necrosis. PPZ was subsequently tested for mutagenicity in the Big Blue® transgenic mouse assay at the 2,500 ppm dose, and the result was reported as positive by Ross et al. ([2009]: Mutagenesis 24:149‐152). Subsets of the mutants from the control and PPZ‐exposed groups were sequenced to...

Assessment of genotoxicity induced by 7,12‐dimethylbenz(a)anthracene or diethylnitrosamine in the Pig‐a, micronucleus and Comet assays integrated into 28‐day repeat dose studies

Environmental and Molecular Mutagenesis — Tue, 04 Oct 2011 04:00:00 +0100

AbstractAs part of the Stage 3 of the Pig‐a international trial, we evaluated 7,12‐dimethylbenz(a)anthracene (DMBA) for induction of Pig‐a gene mutation using a 28‐day repeat dose study design in Sprague‐Dawley rats. In the same study, chromosomal damage in peripheral blood and primary DNA damage in liver were also investigated by the micronucleus (MN) assay and the Comet assay, respectively. In agreement with previously published data (Dertinger et al., [2010]: Toxicol Sci 115:401‐411), DMBA induced dose‐dependent increases of CD59‐negative erythrocytes/reticulocytes and micronucleated reticulocytes (MN‐RETs). However, there was no significant increase in DNA damage in the liver cells when tested up to 10 mg/kg/day, which appears to be below the maximum tolerated dose. W...

An alternative linear trend analysis for assessing the results of the mouse lymphoma assay

Environmental and Molecular Mutagenesis — Tue, 04 Oct 2011 04:00:00 +0100

AbstractAs recommended by the mouse lymphoma assay (MLA) Workgroup of the International Workshop on Genotoxicity Testing (Aberdeen, 2003), a trend test is critical if an induced mutant frequency (MF) of at least 126 × 10−6 (global evaluation factor, GEF) is achieved at one or more test concentrations. Only those responses that both achieve the GEF and a significant trend are biologically relevant. While no specific trend test was recommended by the Workshop, a trend test was recommended by the UK Environmental Mutagen Society (1989). The test uses MF (untransformed) averaged over replicate cultures following a consistency test (against a historical heterogeneity factor) in a weighted linear regression with chi‐square (χ2) test for slope and returns significant results in virtually al...

Need and potential value of the Pig‐ain vivo mutation assay—A hesi perspective

Environmental and Molecular Mutagenesis — Tue, 04 Oct 2011 04:00:00 +0100

AbstractThe Health and Environmental Sciences Institute (HESI), a global branch of the International Life Sciences Institute (ILSI), initiated a project committee entitled “Relevance and Follow‐up of Positive Results from In Vitro Genetic Toxicity Testing (IVGT)” with the overall objective of improving the scientific basis for the interpretation of results from genetic toxicology testing. The IVGT committee has also recognized the need to develop follow‐up strategies for determining the relevance of in vitro test results to human health, and moving genetic toxicology testing from the sole purpose of hazard identification toward a more quantitative risk assessment approach. In this context, a group of experts evaluated the potential utility of the emerging in vivo mutational assessm...

Simultaneous measurement of benzo[a]pyrene‐induced Pig‐a and lacZ mutations, micronuclei and DNA adducts in mutaTM mouse

Environmental and Molecular Mutagenesis — Tue, 04 Oct 2011 04:00:00 +0100

Integration of Pig‐a, micronucleus, chromosome aberration, and comet assay endpoints in a 28‐day rodent toxicity study with 4‐nitroquinoline‐1‐oxide

Environmental and Molecular Mutagenesis — Sat, 01 Oct 2011 04:00:00 +0100

AbstractAs part of the Stage III Pig‐a multilaboratory validation trial, we examined the induction of CD59‐negative reticulocytes and total red blood cells (RETCD59− and RBCCD59−, respectively) in male Sprague Dawley® rats treated with 4‐nitroquinoline‐1‐oxide (4NQO), for 28 consecutive days by oral gavage, at doses of 1.25, 2.50, 3.75, 5.00, and 7.50 mg kg−1 day−1 (the high dose group was sacrificed on Day 15 due to excessive morbidity/mortality). Animals also were evaluated for: micronucleated reticulocytes (mnRET) by flow cytometry; DNA damage in peripheral blood, liver, and stomach using the Comet assay; and chromosome aberrations (CAb) in peripheral blood lymphocytes (PBL). All endpoints were analyzed at two or more timepoints where possible. Mortality, body and org...

EGFR mutations in non‐small‐cell lung cancer among smokers and non‐smokers: A meta‐analysis

Environmental and Molecular Mutagenesis — Sun, 28 Aug 2011 23:00:00 +0100

AbstractMounting evidence has suggested somatic mutations in the EGFR gene are associated with better responsiveness to EGFR tyrosine kinase inhibitors (TKIs) in patients with non‐small‐cell lung cancer (NSCLC). Some, but not all, studies have reported that the mutations were more frequently observed in patients without a smoking history. To comprehensively address this issue, we performed a meta‐analysis to evaluate the association between cigarette‐smoking history and mutation of the EGFR gene in NSCLC. Twenty‐six studies, involving 3,688 patients with NSCLC were included in the analysis. The pooled analysis shows that the incidence of EGFR mutations in NSCLC differs according to cigarette‐smoking history. The odds ratio (OR) for the EGFR mutation in non‐smokers relative to...

Assessment of micronucleus frequency in the peripheral blood of female rats in persistent estrus treated with selective estrogen receptor modulators

Environmental and Molecular Mutagenesis — Sun, 28 Aug 2011 23:00:00 +0100

AbstractThe aim of this study was to evaluate micronucleus (MN) frequency in polychromatic erythrocytes (PCE) of female rats in persistent estrus (a model developed to mimic polycystic ovary syndrome) treated with selective estrogen receptor modulators (SERMs, tamoxifen, and raloxifene). Forty female Wistar‐Hannover rats were divided into four groups of 10 animals each: Group I (normally cycling rats) and Group II (persistent estrus) both received only vehicle, while Group III (persistent estrus) was treated with tamoxifen (250 μg/animal/day) and Group IV (persistent estrus) was treated with raloxifene (750 μg/animal/day). Tamoxifen and raloxifene were given by oral gavage beginning on postnatal day 90 and continuing for 30 consecutive days. Peripheral blood samples were collected from...

Report on stage III Pig‐a mutation assays using benzo[a]pyrene

Environmental and Molecular Mutagenesis — Sun, 28 Aug 2011 23:00:00 +0100

AbstractGenotoxicity assays were conducted on rats treated with benzo[a]pyrene (BaP) as part of Stage III of a validation study on the Pig‐a gene mutation assay. Assays were performed at the U.S. FDA‐NCTR and Bayer‐Germany. Starting on Day 1, groups of five 6‐ to 7‐week‐old male Fischer 344 (F344, used at FDA‐NCTR) and Han Wistar rats (Bayer) were given 28 daily doses of 0, 37.5, 75, or 150 mg/kg BaP; blood was sampled on Days −1, 4, 15, 29, and 56. Pig‐a mutant frequencies were determined on Days −1, 15, 29, and 56 in total red blood cells (RBCs) and reticulocytes (RETs) as RBCCD59− and RETCD59− frequencies; percent micronucleated‐RETs (%MN‐RET) were measured on Days 4 and 29. RBCCD59− and RETCD59− frequencies increased in a dose‐ and time‐dependent man...

Chromodomain helicase DNA‐binding protein 2 affects the repair of X‐ray and UV‐Induced DNA damage

Environmental and Molecular Mutagenesis — Sun, 28 Aug 2011 23:00:00 +0100

In this study, we present evidence that the Chd2 mutant cells are defective in their ability to repair DNA damage induced by ionizing and ultraviolet radiation. Consistent with the role of Chd2 in regulating DNA damage responses, the Chd2 mutant cells are also sensitive to DNA damaging agents in clonogenic assays. In summary, our data suggest that the Chd2 protein is involved in regulating the DNA damage responses at the chromatin level. Environ. Mol. Mutagen. 2011. © 2011 Wiley‐Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Trimethoprim‐sulfamethoxazole increase micronuclei formation in peripheral blood from weanling well‐nourished and malnourished rats

Environmental and Molecular Mutagenesis — Sun, 07 Aug 2011 23:00:00 +0100

In this study, we have evaluated the frequency of spontaneous and TMP‐SMX‐induced micronuclei in the peripheral blood of weanling (21 days of age) rats using a flow cytometric analysis technique. The spontaneous frequency of micronucleated reticulocytes (MN‐RETs) was 2.7 times greater in the UN rats than in the WN rats. In rats that were not treated with TMP‐SMX, the percentage of reticulocytes was significantly lower (41.1%) in the UN rats than the WN controls. A therapeutic dose of TMP‐SMX (80 mg/kg (TMP), 400 mg/kg (SMX) for 48 hr) increased MN‐RETs in the WN and in the UN rats. The data demonstrate the genotoxic effect of this drug. The results indicate that severe protein‐calorie restriction and drug treatment enhance DNA damage in rat peripheral blood reticulocytes, pot...

In vivo assessment of Pig‐a gene mutation—recent developments and assay validation

Environmental and Molecular Mutagenesis — Mon, 01 Aug 2011 04:00:00 +0100

(Source: Environmental and Molecular Mutagenesis)

Hepatic mRNA, microRNA, and miR‐34a‐Target responses in mice after 28 days exposure to doses of benzo(a)pyrene that elicit DNA damage and mutation

Environmental and Molecular Mutagenesis — Mon, 01 Aug 2011 04:00:00 +0100

In this study, we found a significant 2.0 and 3.6‐fold increase following exposure to 50 and 75 mg/kg/day BaP, respectively, relative to controls for miR‐34a. This miRNA is involved in p53 response. No other significant changes in miRNAs were observed. The protein levels of five experimentally confirmed miR‐34a targets were examined, and no major down‐regulation was present. The results suggest that liver miRNAs are largely unresponsive to BaP doses that cause both DNA adducts and mutations. In summary, the validated miRNA and mRNA expression profiles following 28 day BaP exposure reflect a DNA damage response and effects on the cell cycle, consistent with the observed increases in DNA adducts and mutations. Environ. Mol. Mutagen., 2011. © 2011 Crown in the right of Canada (Source...

International Pig‐a gene mutation assay trial: Evaluation of transferability across 14 laboratories

Environmental and Molecular Mutagenesis — Mon, 01 Aug 2011 04:00:00 +0100

AbstractA collaborative international trial was conducted to evaluate the reproducibility and transferability of an in vivo mutation assay based on the enumeration of CD59‐negative rat erythrocytes, a phenotype that is indicative of Pig‐a gene mutation. Fourteen laboratories participated in this study, where anti‐CD59‐PE, SYTO 13 dye, and flow cytometry were used to determine the frequency of CD59‐negative erythrocytes (RBCCD59−) and CD59‐negative reticulocytes (RETCD59−). To provide samples with a range of mutant phenotype cell frequencies, male rats were exposed to N‐ethyl‐N‐nitrosourea (ENU) via oral gavage for three consecutive days (Days 1–3). Each laboratory studied 0, 20, and 40 mg ENU/kg/day (n = 5 per group). Three sites also evaluated 4 mg/kg/day. At a min...

Interlaboratory Pig‐a gene mutation assay trial: Studies of 1,3‐propane sultone with immunomagnetic enrichment of mutant erythrocytes

Environmental and Molecular Mutagenesis — Sun, 31 Jul 2011 23:00:00 +0100

AbstractAn international collaborative trial was established to systematically investigate the merits and limitations of a rat in vivo Pig‐a gene mutation assay. The product of this gene is essential for anchoring CD59 to the plasma membrane, and mutations in this gene are identified by flow cytometric quantification of circulating erythrocytes without cell surface CD59 expression. Initial interlaboratory data from rats treated with several potent mutagens have been informative, but the time required for those flow cytometric analyses (∼20 min per sample) limited the number of cells that could be interrogated for the mutant phenotype. Thus, it was desirable to establish a new higher throughput scoring approach before expanding the trial to include weak mutagens or nongenotoxicants. An ...

Differences in the frequencies of K‐ras c12–13 genotypes by gender and pathologic phenotypes in colorectal tumors measured using the allele discrimination method

Environmental and Molecular Mutagenesis — Sun, 31 Jul 2011 23:00:00 +0100

In conclusion, allele discrimination, with no additional amplification step, is a fast and reliable genotyping method for detecting K‐ras c12–13 mutations. Using this method, we demonstrate differences in the frequencies of K‐ras genotypes by gender and pathologic phenotypes of CRC. Environ. Mol. Mutagen., 2011. © 2011 Wiley‐Liss,Inc. (Source: Environmental and Molecular Mutagenesis)

Monitoring humans for somatic mutation in the endogenous pig‐a gene using red blood cells

Environmental and Molecular Mutagenesis — Sun, 31 Jul 2011 23:00:00 +0100

AbstractThe endogenous X‐linked PIG‐A gene is involved in the synthesis of glycosyl phosphatidyl inositol (GPI) anchors that tether specific protein markers to the exterior of mammalian cell cytoplasmic membranes. Earlier studies in rodent models indicate that Pig‐a mutant red blood cells (RBCs) can be induced in animals treated with genotoxic agents, and that flow cytometry can be used to identify rare RBCs deficient in the GPI‐anchored protein, CD59, as a marker of Pig‐a gene mutation. We investigated if a similar approach could be used for detecting gene mutation in humans. We first determined the frequency of spontaneous CD59‐deficient RBCs (presumed PIG‐A mutants) in 97 self‐identified healthy volunteers. For most subjects, the frequency of CD59‐deficient RBCs was lo...

Induction of DNA damage signaling genes in benzidine‐treated HepG2 cells

Environmental and Molecular Mutagenesis — Sun, 31 Jul 2011 23:00:00 +0100

We examined genotoxicity and DNA damage response in HepG2 cells following exposure to benzidine. Using the Comet assay, we showed that benzidine (50–200 μM) induces DNA damage in HepG2 cells. DNA damage signaling pathway‐based PCR arrays were used to investigate expression changes in genes involved in cell‐cycle arrest, apoptosis, and DNA repair and showed upregulation of 23 genes and downregulation of one gene in benzidine‐treated cells. Induction of G2/M arrest and apoptosis was confirmed at the protein level. Real‐time PCR and Western blots were used to demonstrate the expression of select DNA repair‐associated genes from the PCR array. Upregulation of the p53 protein in benzidine‐treated cells suggests the induction of the p53 DNA damage signaling pathway. Collectively, ...

Radiation exposure differentially affects songbird 8‐hydroxy‐2′‐deoxyguanosine plasma profiles: Ionizing radiation damage response in songbirds

Environmental and Molecular Mutagenesis — Sun, 31 Jul 2011 23:00:00 +0100

This study demonstrates that in a controlled experiment, in isolation from other sources of genotoxicity, radiation exposure significantly affects songbirds. Our results suggest future research examining the effects of radiation on songbirds must consider using multiple species to assess the biological effects of radiation, as different species can show strikingly differentresponses to radiation dosage across time. Environ. Mol. Mutagen., 2011. © 2011 Wiley‐Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Genotoxicity of 7H‐dibenzo[c,g]carbazole and its tissue‐specific derivatives in human hepatoma HepG2 cells is related to CYP1A1/1A2 expression

Environmental and Molecular Mutagenesis — Sun, 31 Jul 2011 23:00:00 +0100

AbstractThe goal of this study was to investigate the genotoxicity of 7H‐dibenzo[c,g]carbazole (DBC), a ubiquitous environmental pollutant, and its methyl derivatives, 5,9‐dimethylDBC (DiMeDBC), a strict hepatocarcinogen, and N‐methylDBC (N‐MeDBC), a specific sarcomagen in human hepatoma HepG2 cells, and to infer potential mechanisms underlying the biological activity of particular carcinogen. All dibenzocarbazoles, regardless the tissue specificity, induced significant DNA strand break levels and micronuclei in HepG2 cells; though a mitotic spindle dysfunction rather than a chromosome breakage was implicated in N‐MeDBC‐mediated micronucleus formation. While DBC and N‐MeDBC produced stable DNA adducts followed with p53 protein phosphorylation at Ser‐15, DiMeDBC failed. A si...

Antigenotoxic activity of naturally occurring furanocoumarins

Environmental and Molecular Mutagenesis — Thu, 21 Jul 2011 23:00:00 +0100

This study was designed to investigate the antigenotoxic effects of a series of naturally occurring furanocoumarins (NOFs) including isoimperatorin, imperatorin, (+)‐oxypeucedanin, (+)‐byakangelicol, and (+)‐byakangelicine on antigenotoxic activities against genotoxicity induced by carcinogens [furylfuramide and N‐methyl‐N′‐nitro‐N‐nitrosoguanidine], and procarcinogens 2‐[2‐(acetylamino)−4‐amino‐5‐methoxyphenyl]−5‐amino‐7‐bromo‐4‐chloro‐2H‐benzotriazole (PBTA‐4) and 2‐amino‐3,4‐dimethyl‐3H‐imidazo‐[4,5‐f] quinoline (MeIQ)] to genotoxic metabolites catalyzed by rat S9 or rat and human recombinant cytochrome P450 (CYP) 1As by using the umu test based on SOS response. Five different NOFs, which were found in the human diets, strong...

XRCC1 coordinates disparate responses and multiprotein repair complexes depending on the nature and context of the DNA damage

Environmental and Molecular Mutagenesis — Thu, 21 Jul 2011 23:00:00 +0100

AbstractXRCC1 is a scaffold protein capable of interacting with several DNA repair proteins. Here we provide evidence for the presence of XRCC1 in different complexes of sizes from 200 to 1500 kDa, and we show that immunoprecipitates using XRCC1 as bait are capable of complete repair of AP sites via both short patch (SP) and long patch (LP) base excision repair (BER). We show that POLβ and PNK colocalize with XRCC1 in replication foci and that POLβ and PNK, but not PCNA, colocalize with constitutively present XRCC1‐foci as well as damage‐induced foci when low doses of a DNA‐damaging agent are applied. We demonstrate that the laser dose used for introducing DNA damage determines the repertoire of DNA repair proteins recruited. Furthermore, we demonstrate that recruitment of POLβ an...

Key studies used to support cancer risk assessment questioned

Environmental and Molecular Mutagenesis — Thu, 21 Jul 2011 23:00:00 +0100

AbstractThis paper reassessed studies conducted under the leadership of Drosophila geneticist Curt Stern which played a pivotal role in the acceptance of the linear dose‐response model by the U.S. National Academy of Sciences Biological Effects of Atomic Radiation (BEAR) I Committee and the subsequent generalization of their recommendations on the linearity dose‐response paradigm for ionizing radiation and chemically induced cancer. The analysis finds serious concerns and flaws in important aspects of these experiments, their assessment, and interpretation. Of particular concern was the failure of Stern's group to provide the necessary and promised experimental documentation to support the findings of three critical summarized experiments published as a brief technical note in Science....

Repetitive exposure to zinc oxide nanoparticles induces dna damage in human nasal mucosa mini organ cultures

Environmental and Molecular Mutagenesis — Thu, 21 Jul 2011 23:00:00 +0100

AbstractData on the toxicological properties of zinc oxide nanoparticles (ZnO‐NPs) is incomplete. ZnO‐NPs may enter humans via inhalation or ingestion. The aim of the current study was to evaluate ZnO‐NP‐induced genotoxicity in three‐dimensional (3D) mini organ cultures (MOCs) of human nasal mucosa following repeated exposure to ZnO‐NP and regeneration. Nasal MOCs of 10 patients and ZnO‐NPs were cultivated for one week and then characterized by electron microscopy. Nasal MOCs were partially covered by ciliated epithelium after one week of cultivation. ZnO‐NPs were distributed to the cytoplasm and the nucleus. MOCs were exposed once, twice, or three times to 0.1 or 5 μg/ml of ZnO‐NPs for 1 hr per exposure and were then evaluated for cytotoxicity and genotoxicity. MOCs wer...

In vitro evaluation of the genotoxic and cytotoxic effects of artesunate, an antimalarial drug, in human lymphocytes

Environmental and Molecular Mutagenesis — Sun, 03 Jul 2011 23:00:00 +0100

AbstractArtesunate is one of the main antimalarial drugs used in several countries. It is a semisynthetic compound derived from artemisinin, a substance extracted from the Chinese plant, Artemisia annua L. Despite the widespread use of artesunate as an antimalarial drug, there is a lack of data regarding its genotoxic effects in human lymphocytes. Therefore, in this study, we used the comet assay and micronucleus test to evaluate the possible genotoxic effects of artesunate in cultured human lymphocytes. In addition, cell death by necrosis and apoptosis was also assessed. Cells exposed to different concentrations of artesunate showed a significant concentration‐dependent increase (P < 0.05) in DNA damage index and micronuclei frequency. A significant increase in the frequency of apopt...

Chronic exposure to nanosized, anatase titanium dioxide is not cyto‐ or genotoxic to Chinese hamster ovary cells

Environmental and Molecular Mutagenesis — Thu, 30 Jun 2011 23:00:00 +0100

We examined cyto‐ and genotoxicity in CHO‐K1 cells following 60 days of continuous exposure to defined levels of nano‐TiO2 (0, 10, 20, or 40 μg/ml). Oxidative stress increased in a concentration‐dependent manner in short‐ (2 days) and long‐term cultures, but long‐term cultures had lower levels of oxidative stress. The primary reactive oxygen species appeared to be superoxide, and ROS indicators were lowered with the addition of superoxide dismutase (SOD). No cyto‐ or genotoxic effects were apparent using the XTT, trypan‐blue exclusion, and colony‐forming assays for viability and the Comet and Hprt gene mutation assays for genotoxicity. Nano‐TiO2 increased the percentage of cells in the G2/M phase of the cell cycle, but this effect did not appear to influence cell via...

Measures of genotoxicity in Gulf war I veterans exposed to depleted uranium

Environmental and Molecular Mutagenesis — Thu, 30 Jun 2011 23:00:00 +0100

This study provides a comprehensive evaluation of a human population chronically exposed to DU and demonstrates a relatively weak genotoxic effect of the DU exposure. These results may explain the lack of clear epidemiologic evidence for U carcinogenicity in humans. Environ. Mol. Mutagen., 2011. © 2011 Wiley‐Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Analysis of mutations in the Pig‐a gene of spleen T‐cells from N‐ethyl‐N‐nitrosourea‐treated fisher 344 rats

Environmental and Molecular Mutagenesis — Mon, 02 May 2011 23:00:00 +0100

AbstractA rapid in vivo somatic cell gene mutation assay is being developed that measures mutation in the endogenous X‐linked phosphatidylinositol glycan, class A gene (Pig‐a). The assay detects Pig‐a mutants by flow cytometric identification of cells deficient in glycosylphosphatidyl inositol (GPI) anchor synthesis. GPI‐deficient, presumed Pig‐a mutant cells also can be detected in a cloning assay that uses proaerolysin (ProAER) selection. Previously, we demonstrated that ProAER‐resistant (ProAERr) rat spleen T‐cells have mutations in the Pig‐a gene. In the present study, we report on a more complete analysis of ProAERr rat spleen T‐cell mutants and describe a mutation spectrum for mutants isolated from rats 4 weeks after treatment with three consecutive doses of 35.6 mg...

Can carcinogenic potency be predicted from in vivo genotoxicity data? a meta‐analysis of historical data

Environmental and Molecular Mutagenesis — Sat, 30 Apr 2011 23:00:00 +0100

AbstractGenotoxicity is generally a parameter used for hazard identification, however, the applicability of using in vivo genotoxicity tests for hazard characterization has never been thoroughly investigated in a quantitative manner. Genotoxicity assays could be useful for the determination of cancer potency parameters given that genotoxicty tests measure mutations and/or chromosomal aberrations which are strongly associated with carcinogenesis. A detailed literature survey was performed in search for dose‐response data in various in vivo genotoxicity and carcinogenicity studies. The benchmark dose (BMD) approach was applied using the dose‐response modeling program PROAST. Dose‐response data were available from 18 compounds in the micronucleus assay (MN), the in vivo transgenic roden...

Genetic toxicology in the 21st century: Reflections and future directions

Environmental and Molecular Mutagenesis — Thu, 28 Apr 2011 23:48:05 +0100

This article summarizes the presentations and provides a perspective on the future. An abbreviated history is presented, highlighting the current standard battery of genotoxicity assays and persistent challenges. Application of computational toxicology to safety testing within a regulatory setting is discussed as a means for reducing the need for animal testing and human clinical trials, and current approaches and applications of in silico genotoxicity screening approaches across the pharmaceutical industry were surveyed and are reported here. The expanded use of toxicogenomics to illuminate mechanisms and bridge genotoxicity and carcinogenicity, and new public efforts to use high‐throughput screening technologies to address lack of toxicity evaluation for the backlog of thousands of ind...

Effects of potential dietary inhibitors of endogenous DNA damage on mutagenesis and lipid peroxidation in lacZ mice

Environmental and Molecular Mutagenesis — Thu, 28 Apr 2011 03:47:18 +0100

AbstractThe effects of a nine month administration of dietary: (1) 3H‐1,2‐dithiole‐3‐thione (D3T), (2) N‐acetylcysteine (NAC), (3) antioxidant vitamin mix, (vitamin C+E), (4) free radical scavenger, amifostine, and (5) calorie restriction, (CR), on mutagenesis and lipid peroxidation in lung, kidney, spleen and liver of lacZ transgenic mice were examined. These agents/diets were chosen because they might inhibit certain proposed mechanisms of endogenous damage to DNA. The agents were added to a high fat, reduced antioxidant AIN‐76 diet, to better approximate a Western style diet than the conventional AIN‐76 diet. As the lacZ gene is not expressed, mutations in that gene are neutral, and simply accumulate over time. The mutant fractions in control mice increased about 50–100%...

Analysis of genomic instability in the offspring of fathers exposed to low doses of ionizing radiation

Environmental and Molecular Mutagenesis — Wed, 27 Apr 2011 23:00:00 +0100

AbstractTransgenerational genomic instability was studied in nonirradiated children born from fathers who were irradiated with low doses of ionizing radiation while working as clean‐up workers at the Chernobyl Nuclear Power Plant (liquidators) and nonirradiated mothers from nuclear families. Aberrant cell frequencies (ACFs), chromosomal type aberration frequencies, and chromatid break frequencies (CBFs) in the lymphocytes of fathers‐liquidators, and their children were significantly higher when compared with the control group (P < 0.05). Individual ACFs, aberration frequencies, and CBFs were independent of the time between irradiation of the father and conception of the child (1 month to 18 years). Chromosomes were categorized into seven groups (A through G). Analysis of aberrant ch...

DNA damage and nucleotide excision repair capacity in healthy individuals

Environmental and Molecular Mutagenesis — Wed, 27 Apr 2011 00:20:31 +0100

AbstractInterindividual differences in DNA repair capacity (DRC) represent an important source of variability in genome integrity and thus influence health risk. In the last decade, DRC measurement has attracted attention as a potential biomarker in cancer prediction. Aim of the present exploratory study was to characterize the variability in DNA damage and DRC on 100 healthy individuals and to identify biological, lifestyle, or genetic factors modulating these parameters. The ultimate goal was to obtain reference data from cancer‐free population, which may constitute background for further investigations on cancer patients. The endogenous DNA damage was measured as a level of DNA single‐strand breaks and DRC, specific for nucleotide excision repair (NER), was evaluated using modified ...

Characterization of environmental chemicals with potential for DNA damage using isogenic DNA repair‐deficient chicken DT40 cell lines

Environmental and Molecular Mutagenesis — Tue, 26 Apr 2011 23:00:00 +0100

AbstractIncluded among the quantitative high throughput screens (qHTS) conducted in support of the US Tox21 program are those being evaluated for the detection of genotoxic compounds. One such screen is based on the induction of increased cytotoxicity in seven isogenic chicken DT40 cell lines deficient in DNA repair pathways compared to the parental DNA repair‐proficient cell line. To characterize the utility of this approach for detecting genotoxic compounds and identifying the type(s) of DNA damage induced, we evaluated nine of 42 compounds identified as positive for differential cytotoxicity in qHTS (actinomycin D, adriamycin, alachlor, benzotrichloride, diglycidyl resorcinol ether, lovastatin, melphalan, trans‐1,4‐dichloro‐2‐butene, tris(2,3‐epoxypropyl)isocyanurate) and on...

Fenthion and terbufos induce DNA damage, the expression of tumor‐related genes, and apoptosis in HEPG2 cells

Environmental and Molecular Mutagenesis — Tue, 26 Apr 2011 23:00:00 +0100

This study investigates the effects of fenthion and terbufos, two organophosphorous pesticides, on DNA damage, tumor‐related gene expression, and apoptosis in HepG2 cells. We found that exposure to concentrations ranging from 50 to 200 μM of fenthion and terbufos for 2 hr caused significant death in HepG2 cells. Both compounds induced DNA damage in a concentration‐dependent manner as measured using the alkaline comet assay. Tumor‐related genes (jun, myc, and fos) and apoptosis‐related genes (socs3, tnfaip3, ppp1r15a, and nr4a1) were up‐regulated by both compounds. Finally, both compounds induced apoptosis. The results demonstrate that both terbufos and fenthion induce DNA damage and should be considered potentially hazardous to humans. Environ. Mol. Mutagen., 2011. © 2011 Wiley...

Malathion and fenvalerate induce micronuclei in mouse bone marrow cells

Environmental and Molecular Mutagenesis — Tue, 26 Apr 2011 23:00:00 +0100

In this study, the genotoxic effects of two commonly‐used pesticides, malathion, and fenvalerate, were investigated in mice in vivo. Induction of micronuclei in bone marrow cells was used as the test parameter following exposure to 2.5, 5 or 10 mg/kg malathion by intraperitoneal (i.p.) or per oral (p.o.) exposure. Exposure by both routes was found to cause a significant increase in micronucleated polychromatic erythrocytes (PCEs) in a dose‐dependent manner (r = 0.9769; P < 0.05). The highest dose (10 mg/kg) induced significant (P < 0.05) cytotoxicity. In contrast, fenvalerate caused an increase in micronucleated PCEs only at higher doses (10 and 20 mg/kg) via i.p. injection, and was not associated with cytotoxicity. A significant dose‐response correlation was not observed in th...

Long‐lasting genomic instability following arsenite exposure in mammalian cells: The role of reactive oxygen species

Environmental and Molecular Mutagenesis — Sun, 24 Apr 2011 23:00:00 +0100

AbstractPreviously, we reported that the progeny of mammalian cells, which has been exposed to sodium arsenite for two cell cycles, exhibited chromosomal instability and concurrent DNA hypomethylation, when they were subsequently investigated after two months of subculturing (about 120 cell generations) in arsenite‐free medium. In this work, we continued our investigations of the long‐lasting arsenite‐induced genomic instability by analyzing additional endpoints at several time points during the cell expanded growth. In addition to the progressive increase of aneuploid cells, we also noted micronucleated and multinucleated cells that continued to accumulate up to the 50th cell generation, as well as dicentric chromosomes and/or telomeric associations and other complex chromosome rear...

MicroRNAs and their predicted target messenger RNAs are deregulated by Exposure to a Carcinogenic Dose of Comfrey in Rat Liver

Environmental and Molecular Mutagenesis — Wed, 02 Mar 2011 00:00:00 +0100

In this study, we analyzed miRNA and mRNA expression in the livers of rats treated with a carcinogenic dose of comfrey (Symphytum officinale) for 12 weeks. Groups of six rats were fed a normal diet or a diet containing 8% comfrey root. The animals were sacrificed 1 day after the last treatment and the livers were isolated for miRNA expression analysis using LC Sciences miRNA microarrays and for mRNA expression analysis using Affymetrix rat genome microarrays. MiRNA expression levels were significantly changed by comfrey treatment. The treated samples were separated clearly from the control samples in both principal component analysis (PCA) and hierarchical clustering analysis (HCA). Quantitative measurements of seven miRNAs using TaqMan real‐time PCR were consistent with the microarray r...

Accumulation of K‐Ras codon 12 mutations in the F344 rat distal colon following azoxymethane exposure

Environmental and Molecular Mutagenesis — Wed, 02 Mar 2011 00:00:00 +0100

AbstractAzoxymethane (AOM) administration to F344 male rats is a widely used model of human colon carcinogenesis. The current study investigates quantitatively the accumulation of K‐Ras codon 12 mutations following AOM exposure. Male, 6‐week‐old F344 rats were treated subcutaneously with 30 mg/kg body weight of AOM, and colon tissue was collected at 1, 8, 24, and 32 weeks after treatment. The K‐Ras codon 12 GGT to GAT and GGT to GTT mutant fractions (MFs) were measured using allele‐specific competitive blocker polymerase chain reaction (ACB‐PCR). Between 1 and 32 weeks after AOM treatment, the K‐Ras codon 12 GGT to GAT geometric mean MF in the rat colon increased significantly from 12.9 × 10−5 to 145 × 10−5, and the GGT to GTT geometric mean MF increased significantly f...

The human carcinogen aristolochic acid i is activated to form DNA adducts by human NAD(P)H:quinone oxidoreductase without the contribution of acetyltransferases or sulfotransferases

Environmental and Molecular Mutagenesis — Wed, 02 Mar 2011 00:00:00 +0100

AbstractIngestion of aristolochic acid (AA) is associated with development of urothelial tumors linked with AA nephropathy and is implicated in the development of Balkan endemic nephropathy‐associated urothelial tumors. We investigated the efficiency of human NAD(P)H:quinone oxidoreductase (NQO1) to activate aristolochic acid I (AAI) and used in silico docking, using soft–soft (flexible) docking procedure, to study the interactions of AAI with the active site of human NQO1. AAI binds to the active site of NQO1 indicating that the binding orientation allows for direct hydride transfer (i.e., two electron reductions) to the nitro group of AAI. NQO1 activated AAI, generating DNA adduct patterns reproducing those found in urothelial tissues from humans exposed to AA. Because reduced aromat...

Micronuclei and other nuclear abnormalities in mussels (Mytilus galloprovincialis) as biomarkers of cyto‐genotoxic pollution in mediterranean waters

Environmental and Molecular Mutagenesis — Wed, 02 Mar 2011 00:00:00 +0100

AbstractEnvironmental genotoxicity and cytotoxicity along the Spanish Mediterranean coast was investigated through the determination of levels of micronuclei (MN) and other nuclear abnormalities (NAs) such as nuclear buds (NB) and binucleated cells (BN) in gills of wild mussels, Mytilus galloprovincialis, from 17 study sites. The results obtained were studied in relation to the exposure to main pollutants (metals, PAHs, PCBs and DDTs), gill antioxidant enzyme activities and environmental variables (temperature and salinity). The highest MN and NB levels were found in mussels from metal‐polluted sites, such as Cartagena (MN: 11.6‰, NB: 4.6‰) and Portman (MN: 8.0‰, NB: 3.5‰), where genotoxicity seemed to be related to the oxidative stress generated by exposure to metals. High frequ...

Role of DNA polymerase beta in the genotoxicity of arsenic

Environmental and Molecular Mutagenesis — Wed, 02 Mar 2011 00:00:00 +0100

In conclusion, our results indicate an important role for Pol β in repairing arsenite‐induced DNA damage and maintaining chromosomal integrity and further suggest deficiency of BER may be involved in arsenic genotoxicity and carcinogenicity. Environ. Mol. Mutagen., 2011. © 2011 Wiley‐Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Biomonitoring of rural workers exposed to a complex mixture of pesticides in the municipalities of Tianguá and Ubajara (Ceará state, Brazil): Genotoxic and cytogenetic studies

Environmental and Molecular Mutagenesis — Wed, 02 Mar 2011 00:00:00 +0100

AbstractIn recent years, the use of pesticides in agriculture has been steadily increasing, and associations between exposure to agricultural chemicals and DNA damage and cancer have been reported. Brazil is one of the world leaders in pesticide use; however, studies that evaluate the impact of pesticide exposure on cancer incidence and mortality are very scarce in the Brazilian population. The alkaline comet assay and the chromosome aberration (CA) test were used to evaluate primary DNA damage in the peripheral blood lymphocytes of workers exposed to a complex mixture of pesticides in two small rural communities in the municipalities of Tianguá and Ubajara, located in the western part of Ceará State (Northeast Brazil), which are among the largest agricultural areas of the state. The com...

Cytogenetic biomonitoring on a group of petroleum refinery workers

Environmental and Molecular Mutagenesis — Tue, 01 Mar 2011 00:00:00 +0100

In conclusion, our results are indicative of a potential genotoxic risk related to the complex occupational exposure in petroleum refineries, despite the measures adopted in the plants, and corroborate the need to increase safety measures to avoid exposure to chemical agents. Environ. Mol. Mutagen. 2011. © 2011 Wiley‐Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Pulmonary response to surface‐coated nanotitanium dioxide particles includes induction of acute phase response genes, inflammatory cascades, and changes in microRNAs: A toxicogenomic study

Environmental and Molecular Mutagenesis — Fri, 21 Jan 2011 00:00:00 +0100

In this study, the effects of inhaled surface‐coated nanoTiO2 on pulmonary global messenger RNA (mRNA) and microRNA (miRNA) expression in mouse were characterized to provide insight into the molecular response. Female C57BL/6BomTac mice were exposed for 1 hr daily to 42.4 ± 2.9 (SEM) mg surface‐coated nanoTiO2/m3 for 11 consecutive days by inhalation and were sacrificed 5 days following the last exposure. Physicochemical properties of the particles were determined. Pulmonary response to nanoTiO2 was characterized using DNA microarrays and pathway‐specific PCR arrays and related to data on pulmonary inflammation from bronchial lavages. NanoTiO2 exposure resulted in increased levels of mRNA for acute phase markers serum amyloid A‐1 (Saa1) and serum amyloid A‐3 (Saa3), several C‐...

Memorial for Udo H. Ehling (1928–2010)

Environmental and Molecular Mutagenesis — Thu, 06 Jan 2011 00:00:00 +0100

(Source: Environmental and Molecular Mutagenesis)

Assessment of heritable genetic effects using new genetic tools and sentinels in an era of personalized medicine

Environmental and Molecular Mutagenesis — Thu, 06 Jan 2011 00:00:00 +0100

AbstractThe challenge of estimating human health effects from damage to the germ line may be met in the genomic era. Understanding the genetic, as opposed to postconception developmental basis of birth defects is critical to their use in monitoring heritable genetic damage. The causes of common birth defects are analyzed here: mendelian genetic, multigenic, developmental, inherited, or combinational. Only a small fraction of these (noninherited, mendelian genetic) are likely to be informative relative to germ cell mutagenesis, and these won't be discernible against the general background of birth defects. Targeted genetic testing as part of personalized medicine could be integrated into a strategy for assessing germ cell alterations in populations. Thus, “sentinel mutations,” as origin...

Identification of mutagens in freshwater sediments by the Ames‐fluctuation assay using nitroreductase and acetyltransferase overproducing test strains

Environmental and Molecular Mutagenesis — Wed, 22 Dec 2010 00:00:00 +0100

AbstractExtracts of sediments from an area of concern in the Elbe river basins (Spittelwasser creek) were analyzed with the Ames‐fluctuation test and in parallel with gas chromatography/mass spectrometry for compound identification. The standard test strains TA 98 and TA 100 showed mutagenicity mainly in medium‐polar fractions of the sediment extracts. PAHs contribute to the overall mutagenic potential of the sample. Especially, cyclopenta[c,d]pyrene that was previously not defined as a priority hazardous substance has to be considered as well. The addition of metabolically competent test strains, which overexpress nitroreductase and acetyltransferase (e.g., YG1041 and YG1042) to the test battery, increased significantly the sensitivity of the Ames test for medium polar to polar genoto...

A study of DNA damage recognition and repair gene polymorphisms in relation to cancer predisposition and G2 chromosomal radiosensitivity

Environmental and Molecular Mutagenesis — Sun, 28 Nov 2010 00:00:00 +0100

AbstractThe previously reported association of the APEX Asp148Glu single nucleotide polymorphism (SNP) with cancer, and the suggestion of associations of the XRCC3 Thr241Met and hOGG1 Ser326Cys SNP sites with G2 chromosomal radiosensitivity were investigated in a new study of 30 childhood and young adult cancer survivors, their 30 partners, and 55 offspring. An additional SNP, hOGG1 Arg46Gln was also analyzed. Data on G2 chromosomal radiosensitivity was available on 29 of the families including 53 offspring. No significant associations of genotype with cancer or G2 chromosomal radiosensitivity were observed. Environ. Mol. Mutagen., 2010. © 2010 Wiley‐Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Tp53 codon‐72 polymorphisms identify different radiation sensitivities to g2‐chromosome breakage in human lymphoblast cells

Environmental and Molecular Mutagenesis — Thu, 30 Sep 2010 23:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Mutation spectrum in FE1‐MUTATMMouse lung epithelial cells exposed to nanoparticulate carbon black

Environmental and Molecular Mutagenesis — Thu, 30 Sep 2010 23:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Miniaturized flow cytometry‐based CHO‐K1 micronucleus assay discriminates aneugenic and clastogenic modes of action

Environmental and Molecular Mutagenesis — Sat, 31 Jul 2010 23:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

The 40th anniversary of the Environmental Mutagen Society

Environmental and Molecular Mutagenesis — Sat, 31 Jul 2010 23:00:00 +0100

(Source: Environmental and Molecular Mutagenesis)

The DNA damage response—Repair or despair?

Environmental and Molecular Mutagenesis — Sat, 31 Jul 2010 23:00:00 +0100

(Source: Environmental and Molecular Mutagenesis)

Genotoxicity testing: Moving beyond qualitative “screen and bin” approach towards characterization of dose‐response and thresholds

Environmental and Molecular Mutagenesis — Sat, 31 Jul 2010 23:00:00 +0100

(Source: Environmental and Molecular Mutagenesis)

Dietary influences on mutagenesis—Where is this field going?

Environmental and Molecular Mutagenesis — Sat, 31 Jul 2010 23:00:00 +0100

(Source: Environmental and Molecular Mutagenesis)

Environmental Mutagen Society 41st Annual Meeting Abstracts

Environmental and Molecular Mutagenesis — Sat, 31 Jul 2010 23:00:00 +0100

(Source: Environmental and Molecular Mutagenesis)

Environmental Mutagen Society 41st Annual Meeting Agenda

Environmental and Molecular Mutagenesis — Sat, 31 Jul 2010 23:00:00 +0100

(Source: Environmental and Molecular Mutagenesis)

DNA cross‐link induced by trans‐4‐hydroxynonenal

Environmental and Molecular Mutagenesis — Wed, 30 Jun 2010 23:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Initiation of DNA interstrand cross‐link repair in mammalian cells

Environmental and Molecular Mutagenesis — Wed, 30 Jun 2010 23:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Multiple roles of ERCC1‐XPF in mammalian interstrand crosslink repair

Environmental and Molecular Mutagenesis — Wed, 30 Jun 2010 23:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Repair of DNA interstrand cross‐links during S phase of the mammalian cell cycle

Environmental and Molecular Mutagenesis — Wed, 30 Jun 2010 23:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Targeting and processing of site‐specific DNA interstrand crosslinks

Environmental and Molecular Mutagenesis — Wed, 30 Jun 2010 23:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

The Fanconi anemia pathway promotes DNA glycosylase‐dependent excision of interstrand DNA crosslinks

Environmental and Molecular Mutagenesis — Wed, 30 Jun 2010 23:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Convenient, multi‐well plate‐based DNA damage response analysis using DT40 mutants is applicable to a High‐throughput genotoxicity assay with characterization of modes of action

Environmental and Molecular Mutagenesis — Wed, 30 Jun 2010 23:00:00 +0100

(Source: Environmental and Molecular Mutagenesis)

Interstrand crosslink inducing agents in pretransplant conditioning therapy for hematologic malignancies

Environmental and Molecular Mutagenesis — Wed, 23 Jun 2010 23:00:00 +0100

In this report, we review pre-clinical evidence for synergistic antileukemic activity when nucleoside analog(s) and DNA-alkylating agent(s) are combined in the most appropriate manner(s), without a measurable decrease in clinical efficacy compared with the more established alkylating agent combinations. Data from our own laboratory using combinations of fludarabine, clofarabine, and busulfan as prototype representatives for these respective classes of cytotoxic agents are combined with information from other investigators to explain how the observed molecular events will result in greatly enhanced synergistic cytotoxicity. We further present possible mechanistic pathways for such desirable cytotoxic synergism. Finally, we propose how this information-backed hypothesis can be incorporated i...

DNA interstrand crosslinks: Repair, cell signaling, and therapeutic implications

Environmental and Molecular Mutagenesis — Tue, 22 Jun 2010 23:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

DNA cross-link induced by trans-4-hydroxynonenal

Environmental and Molecular Mutagenesis — Tue, 22 Jun 2010 23:00:00 +0100

Trans-4-Hydroxynonenal (HNE) is a peroxidation product of [omega]-6 polyunsaturated fatty acids. Michael addition of HNE to deoxyguanosine yields four diastereomeric 1,N2-dG adducts. The adduct of (6S,8R,11S) stereochemistry forms interstrand N2-dG:N2-dG cross-links in the 5[prime]-CpG-3[prime] sequence. It has been compared with the (6R,8S,11R) adduct, incorporated into 5[prime]-d(GCTAGCXAGTCC)-3' · 5'-d(GGACTCGCTAGC)-3[prime], containing the 5[prime]-CpG-3[prime] sequence (X = HNE-dG). Both adducts rearrange in DNA to N2-dG aldehydes. These aldehydes exist in equilibrium with diastereomeric cyclic hemiacetals, in which the latter predominate at equilibrium. These cyclic hemiacetals mask the aldehydes, explaining why DNA cross-linking is slow compared to related 1,N2-dG adducts formed by...

Convenient, multi-well plate-based DNA damage response analysis using DT40 mutants is applicable to a High-throughput genotoxicity assay with characterization of modes of action

Environmental and Molecular Mutagenesis — Wed, 26 May 2010 23:00:00 +0100

Chemists continually synthesize myriad new chemicals ([sim]2,000/year), some of which make their way into the environment or otherwise pose possible threats to humans who potentially become exposed to the compounds. Regulators must determine whether these, along with the glut ([sim]80,000) of existing, chemicals are toxic and at what exposure levels. An important component of this determination is to ascertain the mode of action (MOA) of each compound as it relates to the pathway the compound uses to induce genotoxicity. Several assays have traditionally been used to reveal these effects to the genome: the Ames test, tests with yeast and mammalian cell lines, and animal studies. Previously, we described a new multi-well plate-based method which makes use of the DT40 isogenic cell line and ...

Involvement of E2F1 transcriptional activity in cadmium-induced cell-cycle arrest at G1 in human lung fibroblasts

Environmental and Molecular Mutagenesis — Tue, 18 May 2010 23:00:00 +0100

Human cadmium (Cd) exposure is associated with cancers of the lung and kidney. Using cDNA microarray analysis, we have recently reported that the expression of E2F1 is reduced by Cd in human lung fibroblasts, indicating the possibility of G1-phase arrest. To test this hypothesis, we investigated the effects of Cd on the cyclin-dependent kinase (CDK2) and retinoblastoma protein (Rb) regulatory pathways in WI38 human lung fibroblasts. We demonstrate here that G1-phase accumulation was induced by Cd in WI38 (wild-type for p53 and Rb), but not in the SV40 large T antigen-transformed variant WI38-VA13 (p53- and Rb-defective). Cd-induced cell-cycle arrest was associated with a decrease in CDK2 protein and with increase in p21 expression and p53 phosphorylation. Cd treatment caused a distinct inc...

Mitochondrial DNA mutations in disease and aging

Environmental and Molecular Mutagenesis — Fri, 14 May 2010 23:00:00 +0100

The human mitochondrial genome involves over 1,000 genes, dispersed across the maternally inherited mitochondrial DNA (mtDNA) and the biparentally inherited nuclear DNA (nDNA). The mtDNA encodes 13 core proteins that determine the efficiency of the mitochondrial energy-generating system, oxidative phosphorylation (OXPHOS), plus the RNA genes for their translation within the mitochondrion. The mtDNA has a very high mutation rate, which results in three classes of clinically relevant mtDNA mutations: recently deleterious germline line mutations resulting in mitochondrial disease; ancient regional variants, a subset of which permitted humans to adapt to differences in their energetic environments; and somatic mutations that accumulate with age eroding mitochondrial energy production and provi...

Possible roles of excess tryptophan metabolites in cancer

Environmental and Molecular Mutagenesis — Thu, 13 May 2010 23:00:00 +0100

Tryptophan is metabolized through serotonin, indole, and kynurenine (KN) pathways. Uptake of an excess amount of tryptophan accompanied with vitamin B6 deficiency may result in the accumulation of higher concentrations of metabolites mainly from the KN pathways in the bladder. These metabolites could interact with nitrite to become mutagenic nitrosamines. They could be a promoter in the initiator-promoter model of carcinogenesis. They produced bladder cancer when implanted in the bladder. They also interact with transition metals copper or iron to form reactive radicals or reactive oxygen species (ROS). Some metabolites, 3-hydroxy-anthranilic acid, were autooxidized to mutagenic cinnabarinic and anthranilyl radical intermediates. These radical intermediates could also be ligands that inter...

Potentiation of the mutagenicity and recombinagenicity of bleomycin in yeast by unconventional intercalating agents

Environmental and Molecular Mutagenesis — Mon, 10 May 2010 23:00:00 +0100

In this study, the amplification of BLM activity was explored in yeast using known intercalators, compounds structurally related to known intercalators, and unconventional intercalators that were identified on the basis of computer modeling or results in the Chinese hamster BLM amplification assay. As shown in previous studies, the classical intercalator 9-aminoacridine (9AA) caused dose-dependent enhancement of BLM activity. Other compounds found to enhance the induction of mitotic recombination and point mutations in strain D7 were chlorpromazine, chloroquine, mefloquine, tamoxifen, diphenhydramine, benzophenone, and 3-hydroxybenzophenone. The increased activity was detectable by cotreatment of yeast with BLM and the modulator compound in growth medium or by separate interaction of the i...

The hunt for the epiallele

Environmental and Molecular Mutagenesis — Sun, 09 May 2010 23:00:00 +0100

Understanding the origin of phenotypic variation remains one of the principle challenges of contemporary biology. Recent genome-wide association studies have identified association between common genetic variants and complex phenotype; however, the minimal effect sizes observed in such studies highlight the potential for other causal factors to be involved in phenotypic variation. The epigenetic state of an organism (or 'epigenome') incorporates a landscape of complex and plastic molecular events that may underlie the 'missing link' that integrates genotype with phenotype. The nature of these processes has been the subject of intense scientific study over the recent years, and characterisation of epigenetic variation, in the form of 'epialleles', is providing fascinating insight into how t...

Delayed effects of exposure to a moderate radiation dose on transcription profiles in human primary fibroblasts

Environmental and Molecular Mutagenesis — Fri, 07 May 2010 23:00:00 +0100

Ionizing radiation (IR) is used in a wide variety of medical and nonmedical applications and poses a potential threat to human health. Knowledge of changes in gene expression in irradiated cells may be helpful for the establishment of effective paradigms for radiation protection. IR-induced DNA damage triggers a complex cascade of signal transduction. Recently, genome-wide approaches have allowed the detection of alterations in gene expression across a wide range of radiation doses. However, the delayed or long-term biological effects of mild-doses of IR remain largely unknown. The main objective of the present study was to investigate the effects of a moderate dose of gamma-rays (50 cGy) on gene expression 6 days post-irradiation. Gene expression using cDNA microarrays revealed statistica...

Generation, function, and prognostic utility of somatic mitochondrial DNA mutations in cancer

Environmental and Molecular Mutagenesis — Wed, 05 May 2010 23:00:00 +0100

Exciting new studies are increasingly strengthening the link between mitochondrial mutagenesis and tumor progression. Here we provide a comprehensive review and meta-analysis of studies reporting on mitochondrial DNA mutations in common human cancers. We discuss possible mechanisms by which mitochondrial DNA mutations may influence carcinogenesis, outline important caveats for interpreting the detected mutations - particularly differentiating causality from association-and suggest how new mutational assays may help resolve fundamental controversies in the field and delineate the origin and expansion of neoplastic cell lineages. Finally, we discuss the potential clinical utility of mtDNA mutations for improving the sensitivity of early cancer diagnosis, rapidly detecting cancer recurrence, ...

A European perspective on the role of EMS societies. How do they help public health and research and the development of regulations?

Environmental and Molecular Mutagenesis — Tue, 04 May 2010 23:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Multiple roles of ERCC1-XPF in mammalian interstrand crosslink repair

Environmental and Molecular Mutagenesis — Wed, 28 Apr 2010 23:00:00 +0100

DNA interstrand crosslinks (ICLs) are among the most deleterious cytotoxic lesions encountered by cells, mainly due to the covalent linkage these lesions create between the two strands of DNA which effectively blocks replication and transcription. Although ICL repair in mammalian cells is not fully understood, processing of these lesions is thought to begin by "unhooking" at the site of the damaged base accompanied by the generation of a double strand break and ultimately repair through translesion synthesis and homologous recombination. A key player in this repair process is the heterodimeric protein complex ERCC1-XPF. Although some models of ICL repair restrict ERCC1-XPF activity to the unhooking step, recent data suggest that this protein complex acts in additional downstream steps. Her...

The genotoxicity of particulate and soluble chromate in sperm whale (Physeter macrocephalus) skin fibroblasts

Environmental and Molecular Mutagenesis — Tue, 27 Apr 2010 23:00:00 +0100

This study investigated the cytotoxic and genotoxic effects of soluble and particulate hexavalent chromium in sperm whale skin fibroblasts. Both forms of hexavalent chromium induced concentration-dependent increases in cytotoxicity and genotoxicity indicating that these compounds can be a health risk if the whales are exposed to them. These data support a hypothesis that chromium is a concern in the marine environment in general and for the health of sperm whales in particular. Environ. Mol. Mutagen., 2010. © 2010 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Time-course of micronucleated erythrocytes in response to whole-body gamma irradiation in a model mammalian species, the bank vole (Clethrionomys glareolus, Schreber)

Environmental and Molecular Mutagenesis — Tue, 27 Apr 2010 23:00:00 +0100

The time course of the formation of micronucleated polychromatic (MNPCEs) and normochromatic erythrocytes (MNNCEs) in the bone marrow of the bank vole (Clethrionomys glareolus, Schreber), a model mouse-like species, was studied using the standard micronucleus test at 0, 6, 12, 18, 24, 30, 36 and 48 hr following whole-body acute [gamma]-irradiation at a dose of 0.5 Gy. Based on the existing literature on laboratory mice, it was suggested that such a dose will not have significant effect on erythroid cell proliferation in the bank vole and hence on the time course of the rise of micronucleated cells. In total, [sim]905,000 polychromatic (PCEs) and normochromatic erythrocytes (NCEs) from 82 adult bank voles were analyzed. Although the mean frequencies of MNNCEs were too low to allow for the c...

Assessment of multiple types of DNA damage in human placentas from smoking and nonsmoking women in the Czech Republic

Environmental and Molecular Mutagenesis — Tue, 27 Apr 2010 23:00:00 +0100

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 32P-postlabeling and by abasic (AB) site analysis. Placenta stained with antiserum elicited against DNA modified with 7[beta],8[alpha]-dihydroxy-9[alpha],10[alpha]-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 t...

The mitochondrial genome: Dynamics, mechanisms of repair, and a target in disease and therapy

Environmental and Molecular Mutagenesis — Tue, 27 Apr 2010 23:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Mammalian cell cytotoxicity and genotoxicity of the haloacetic acids, a major class of drinking water disinfection by-products

Environmental and Molecular Mutagenesis — Tue, 27 Apr 2010 23:00:00 +0100

We present a comparative systematic analysis of chronic cytotoxicity and acute genomic DNA damaging capacity of 12 individual HAAs in mammalian cells. In addition to the HAA5, we analyzed iodoacetic acid (IAA), diiodoacetic acid (DiAA), bromoiodoacetic acid (BIAA), tribromoacetic acid (TBAA), chlorodibromoacetic acid (CDBAA), bromodichloroacetic acid (BDCAA), and bromochloroacetic acid (BCAA). Their rank order of chronic cytotoxicity in Chinese hamster ovary cells was IAA > BAA > TBAA > CDBAA > DIAA > DBAA > BDCAA > BCAA > CAA > BIAA > TCAA > DCAA. The rank order for genotoxicity was IAA > BAA > CAA > DBAA > DIAA > TBAA > BCAA > BIAA > CDBAA. DCAA, TCAA, and BDCAA were not genotoxic. The trend for both cytotoxicity and genotoxicity is iodinated HAAs > brominated HAAs > chlorinated HAAs. Th...

Genotoxicity of lavender oil, linalyl acetate, and linalool on human lymphocytes in vitro

Environmental and Molecular Mutagenesis — Tue, 27 Apr 2010 23:00:00 +0100

The potential genotoxicity of lavender essential oil and its major components, linalool, and linalyl acetate, was evaluated in vitro by the micronucleus test on peripheral human lymphocytes. In the range of non-toxic concentrations (0.5-100 [mu]g/ml), linalyl acetate increased the frequency of micronuclei significantly and in concentration-dependent manner; lavender oil did so only at the highest concentration tested, whereas linalool was devoid of genotoxicity. None of the tested substances led to an increase in nucleoplasmic bridges or nuclear buds frequency. These findings suggest that the mutagenic activity of lavender oil can be related to the presence of linalyl acetate, which seems to have a profile of an aneugenic agent. Environ. Mol. Mutagen., 2010. © 2010 Wiley-Liss, Inc. (Sourc...

Reflections on the origins and evolution of genetic toxicology and the Environmental Mutagen Society

Environmental and Molecular Mutagenesis — Tue, 27 Apr 2010 23:00:00 +0100

This article traces the development of the field of mutagenesis and its metamorphosis into the research area we now call genetic toxicology. In 1969, this transitional event led to the founding of the Environmental Mutagen Society (EMS). The charter of this new Society was to "encourage interest in and study of mutagens in the human environment, particularly as these may be of concern to public health." As the mutagenesis field unfolded and expanded, new wording appeared to better describe this evolving area of research. The term "genetic toxicology" was coined and became an important subspecialty of the broad area of toxicology. Genetic toxicology is now set for a thorough reappraisal of its methods, goals, and priorities to meet the challenges of the 21st Century. To better understand th...

The mitochondrial proteome: A dynamic functional program in tissues and disease states

Environmental and Molecular Mutagenesis — Fri, 16 Apr 2010 23:00:00 +0100

The nuclear DNA transcriptional programming of the mitochondria proteome varies dramatically between tissues depending on its functional requirements. This programming generally regulates all of the proteins associated with a metabolic or biosynthetic pathway associated with a given function, essentially regulating the maximum rate of the pathway while keeping the enzymes at the same molar ratio. This may permit the same regulatory mechanisms to function at low- and high-flux capacity situations. This alteration in total protein content results in rather dramatic changes in the mitochondria proteome between tissues. A tissues mitochondria proteome also changes with disease state, in Type 1 diabetes the liver mitochondrial proteome shifts to support ATP production, urea synthesis, and fatty...

Assessing the link between BACH1/FANCJ and MLH1 in DNA crosslink repair

Environmental and Molecular Mutagenesis — Thu, 15 Apr 2010 23:00:00 +0100

FANCJ (also known as BRIP1 or BACH1) is a DNA helicase that was originally identified by its direct interaction with the hereditary breast cancer protein, BRCA1. Similar to BRCA1, FANCJ function is essential for DNA repair and breast cancer suppression. FANCJ is also mutated in the cancer prone syndrome Fanconi anemia, for which patient cells are characterized by extreme sensitivity to agents that generate DNA interstand crosslinks. Unexpectedly, correction of the interstrand crosslink sensitivity of FANCJ-null patient cells did not require the FANCJ/BRCA1 interaction. Instead, FANCJ binding to the mismatch repair protein, MLH1 was required. Given this finding, we address the role of FANCJ and MLH1 in DNA crosslink processing and how their functions could be linked in checkpoint and/or rec...

Role of homologous recombination in DNA interstrand crosslink repair

Environmental and Molecular Mutagenesis — Thu, 15 Apr 2010 23:00:00 +0100

Homologous recombination repair (HRR) encompasses mechanisms that employ homologous DNA sequences as templates for repair or tolerance of a wide range of DNA lesions that inhibit DNA replication in S phase. Arguably the most imposing of these DNA lesions is that of the interstrand crosslink (ICL), consisting of a covalently attached chemical bridge between opposing DNA strands. ICL repair requires the coordinated activities of HRR and a number of proteins from other DNA repair and damage response systems, including nucleotide excision repair, base excision repair, mismatch repair, and translesion DNA synthesis (TLS). Interestingly, different organisms favor alternative methods of HRR in the ICL repair process. E. coli perform ICL repair using a homology-driven damage bypass mechanism analo...

Mitochondrial dysfunction in neurodegenerative diseases and cancer

Environmental and Molecular Mutagenesis — Tue, 13 Apr 2010 23:00:00 +0100

This article reviews how dysfunctional mitochondria contribute to Alzheimer's disease, Parkinson's disease, Huntington's disease, and several human cancers. Environ. Mol. Mutagen., 2010. © 2010 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Translesion DNA synthesis polymerases in DNA interstrand crosslink repair

Environmental and Molecular Mutagenesis — Mon, 12 Apr 2010 23:00:00 +0100

DNA interstrand crosslinks (ICLs) are induced by a number of bifunctional antitumor drugs such as cisplatin, mitomycin C, or the nitrogen mustards as well as endogenous agents formed by lipid peroxidation. The repair of ICLs requires the coordinated interplay of a number of genome maintenance pathways, leading to the removal of ICLs through at least two distinct mechanisms. The major pathway of ICL repair is dependent on replication, homologous recombination, and the Fanconi anemia (FA) pathway, whereas a minor, G0/G1-specific and recombination-independent pathway depends on nucleotide excision repair. A central step in both pathways in vertebrates is translesion synthesis (TLS) and mutants in the TLS polymerases Rev1 and Pol [zeta] are exquisitely sensitive to crosslinking agents. Here, w...

DNA repair in mammalian mitochondria: Much more than we thought?

Environmental and Molecular Mutagenesis — Mon, 12 Apr 2010 23:00:00 +0100

For many years, the repair of most damage in mitochondrial DNA (mtDNA) was thought limited to short-patch base excision repair (SP-BER), which replaces a single nucleotide by the sequential action of DNA glycosylases, an apurinic/apyrimidinic (AP) endonuclease, the mitochondrial DNA polymerase [gamma], an abasic lyase activity, and mitochondrial DNA ligase. However, the likely array of lesions inflicted on mtDNA by oxygen radicals and the possibility of replication errors and disruptions indicated that such a restricted repair repertoire would be inadequate. Recent studies have considerably expanded our knowledge of mtDNA repair to include long-patch base excision repair (LP-BER), mismatch repair, and homologous recombination and nonhomologous end-joining. In addition, elimination of mutag...

Exercise-induced lipid peroxidation: Implications for deoxyribonucleic acid damage and systemic free radical generation

Environmental and Molecular Mutagenesis — Sun, 11 Apr 2010 23:00:00 +0100

This study tested the hypothesis that high-intensity exercise has the ability to produce free radicals that may be capable of causing DNA damage. Twelve apparently healthy male subjects (age: 23 ± 4 years; stature: 181 ± 8 cm; body mass: 80 ± 9 kg; and VO2max: 49 ± 5 ml/kg/min) performed three 5 min consecutive and incremental stages (40, 70, and 100% of VO2max) of aerobic exercise with a 15-min period separating each stage. Blood was drawn after each bout of exercise for the determination of ex vivo free radicals, DNA damage, protein carbonyls, lipid hydroperoxide (LOOH) concentration, and a range of lipid-soluble antioxidants. Lipid-derived oxygen-centered free radicals (hyperfine coupling constants aNitrogen = 13.7 Gauss (G) and a[beta]Hydrogen = 1.8 G) increased as a result of acut...

A compendium of human mitochondrial gene expression machinery with links to disease

Environmental and Molecular Mutagenesis — Fri, 02 Apr 2010 23:00:00 +0100

Mammalian mitochondrial DNA encodes 37 essential genes required for ATP production via oxidative phosphorylation, instability or misregulation of which is associated with human diseases and aging. Other than the mtDNA-encoded RNA species (13 mRNAs, 12S and 16S rRNAs, and 22 tRNAs), the remaining factors needed for mitochondrial gene expression (i.e., transcription, RNA processing/modification, and translation), including a dedicated set of mitochondrial ribosomal proteins, are products of nuclear genes that are imported into the mitochondrial matrix. Herein, we inventory the human mitochondrial gene expression machinery, and, while doing so, we highlight specific associations of these regulatory factors with human disease. Major new breakthroughs have been made recently in this burgeoning ...

The approaches for manipulating mitochondrial proteome

Environmental and Molecular Mutagenesis — Thu, 01 Apr 2010 23:00:00 +0100

Over the past decade a large volume of research data has accumulated which has established a fundamental role for mitochondria in normal cellular functioning, as well as in various pathologies. Mitochondria play a pivotal role in metabolism and energy production, and are one of the key players involved in programmed cell death. On the other hand, mitochondrial dysfunction is implicated, directly or indirectly in numerous pathological conditions including inherited mitochondrial disorders, diabetes, cardiovascular and neurodegenerative diseases, and a variety of malignancies. The ability to modulate mitochondrial function by altering the diverse protein component of this organelle may be of great value for developing future therapeutic interventions. This review will discuss approaches used...

Reactive species and mitochondrial dysfunction: Mechanistic significance of 4-hydroxynonenal

Environmental and Molecular Mutagenesis — Sat, 27 Mar 2010 00:00:00 +0100

Mitochondrial dysfunction is a global term used in the context of "unhealthy" mitochondria. In practical terms, mitochondria are extremely complex and highly adaptive in structure, chemical and enzymatic composition, subcellular distribution and functional interaction with other components of cells. Consequently, altered mitochondrial properties that are used in experimental studies as measures of mitochondrial dysfunction often provide little or no distinction between adaptive and maladaptive changes. This is especially a problem in terms of generation of oxidant species by mitochondria, wherein increased generation of superoxide anion radical (O2-·) or hydrogen peroxide (H2O2) is often considered synonymously with mitochondrial dysfunction. However, these oxidative species are signaling...

Initiation of DNA interstrand cross-link repair in mammalian cells

Environmental and Molecular Mutagenesis — Fri, 26 Mar 2010 00:00:00 +0100

Interstrand cross-links (ICLs) are among the most cytotoxic DNA lesions to cells because they prevent the two DNA strands from separating, thereby precluding replication and transcription. Even though chemotherapeutic cross-linking agents are well established in clinical use, and numerous repair proteins have been implicated in the initial events of mammalian ICL repair, the precise mechanistic details of these events remain to be elucidated. This review will summarize our current understanding of how ICL repair is initiated with an emphasis on the context (replicating, transcribed or quiescent DNA) in which the ICL is recognized, and how the chemical and physical properties of ICLs influence repair. Although most studies have focused on replication-dependent repair because of the relation...

GADD45[alpha] induction in the GreenScreen HC indicator assay does not occur independently of cytotoxicity

Environmental and Molecular Mutagenesis — Fri, 26 Mar 2010 00:00:00 +0100

Mammalian chromosomal integrity assays are influenced by cytotoxicity, a phenomenon which impacts data interpretation, assay specificity, and regulatory testing guidelines. Concordance of the GADD45[alpha] GreenScreen HC indicator assay to established in vitro and in vivo genetic toxicological assays has previously been described, yet a detailed description in the manner by which cytotoxicity influences its performance has not. Here we present a post-hoc analysis of a previously tested set of 91 proprietary and nonproprietary compounds investigating the influence of cytotoxicity on GADD45[alpha] induction and how varying assay cutoff criteria impacts assay performance. Significant cytotoxicity was identified to accompany the majority (72%) of compounds classified as genotoxic by GADD45[alp...

Repair of DNA interstrand cross-links during S phase of the mammalian cell cycle

Environmental and Molecular Mutagenesis — Fri, 26 Mar 2010 00:00:00 +0100

DNA interstrand cross-linking (ICL) agents are widely used in anticancer chemotherapy regimens, yet our understanding of the DNA repair mechanisms by which these lesions are removed from the genome remains incomplete. This is at least in part due to the enormously complicated nature and variety of the biochemical pathways that operate on these complex lesions. In this review, we have focused specifically on the S-phase pathway of ICL repair in mammalian cells, which appears to be the major mechanism by which these lesions are removed in cycling cells. The various stages and components of this pathway are discussed, and a putative molecular model is presented. In addition, we propose an explanation as to how this pathway can lead to the observed high levels of sister chromatid exchanges kno...

Effects of PON polymorphisms and haplotypes on molecular phenotype in Mexican-American mothers and children

Environmental and Molecular Mutagenesis — Fri, 26 Mar 2010 00:00:00 +0100

Paraoxonase 1 (PON1) prevents oxidation of low-density lipoproteins and inactivates toxic oxon derivatives of organophosphate pesticides (OPs). More than 250 SNPs have been previously identified in the PON1 gene, yet studies of PON1 genetic variation focus primarily on a few promoter SNPs (-108, -162) and coding SNPs (192, 55). We sequenced the PON1 gene in 30 subjects from a Mexican-American birth cohort and identified 94 polymorphisms with minor allele frequencies >5%, including several novel variants (six SNPs, one insertion, and two deletions). Variants of the PON1 gene and three SNPs from PON2 and PON3 were genotyped in 700 children and mothers from the same cohort. PON1 phenotype was established using two substrate-specific assays: arylesterase (AREase) and paraoxonase (POase). Twelv...

Mammalian nucleotide excision repair proteins and interstrand crosslink repair

Environmental and Molecular Mutagenesis — Fri, 26 Mar 2010 00:00:00 +0100

Although various schemes for interstrand crosslink (ICL) repair incorporate DNA recombination, replication, and double-strand break intermediate steps, action of the nucleotide excision repair (NER) system or some variation of it is a common feature of most models. In the bacterium Escherichia coli, the NER enzyme UvrABC can incise on either side of an ICL to unhook the crosslink, and can proceed via a subsequent recombination step. The relevance of NER to ICL repair in mammalian cells has been challenged. Of all NER mutants, it is clear that ERCC1 and XPF-defective cells show the most pronounced sensitivities to ICL-inducing agents, and defects in ICL repair. However, there is good evidence that cells defective in NER proteins including XPA and XPG are also more sensitive than normal to I...

Impact of EMS outreach: Successful developments in Latin America

Environmental and Molecular Mutagenesis — Tue, 09 Mar 2010 00:00:00 +0100

This collection of articles was inspired by the long-standing relationship between the Environmental Mutagen Society and Latin American scientists, and by the program for the 39th Environmental Mutagen Society meeting in Puerto Rico in 2008, which included a symposium featuring "South of the border" scientists. This collection, compiled by Graciela Spivak and Ofelia Olivero, both originally from Argentina, highlights scientists who work in or were trained in Latin American countries and in Puerto Rico in a variety of scientific specialties related to DNA repair and cancer susceptibility, genomic organization and stability, genetic diversity, and environmental contaminants. Environ. Mol. Mutagen. 2010. © 2010 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Targeting mitochondria for cancer therapy

Environmental and Molecular Mutagenesis — Mon, 08 Mar 2010 00:00:00 +0100

Several recent insights into the roles of mitochondria in cancer have renewed efforts to develop nongenotoxic therapies targeting mitochondrial proteins and functions. Mitochondria are central hubs for intrinsic apoptotic pathways that are activated by cellular stress and injury, and as a consequence, cancers often have defects in these pathways. Bcl-2, the first identified regulator of apoptotic cell deaths, was discovered as an oncogene in human cancers. BCL-2 inhibits mitochondrial pathways of apoptosis through local effects at mitochondrial and endoplasmic reticulum membranes. Increased expression of BCL-2 and the related antiapoptotic proteins BCL-XL, MCL-1, and BCL-W occurs in significant subsets of common cancer types (Table I) and is generally correlated with poor response. Althoug...

Chromosome translocations and assessing human exposure to adverse environmental agents

Environmental and Molecular Mutagenesis — Mon, 08 Mar 2010 00:00:00 +0100

This article discusses the use of chromosome translocations for assessing adverse environmental exposure in humans. Translocations are a persistent biomarker of exposure and a biomarker of effect, making them the endpoint of choice for certain human exposure studies because they indicate a potential relationship between exposure and adverse health outcomes, particularly cancer and birth defects. Presented here are the different types of translocations, their origins and persistence, the strengths and limitations of using translocations for exposure assessments, the current state of the art for quantifying exposure including the importance of confounding effects, and the use of model organisms. This article concludes with an assessment of the future of translocation analyses. Environ. Mol. ...

BER gene polymorphisms (OGG1 Ser326Cys and XRCC1 Arg194Trp) and modulation of DNA damage due to pesticides exposure

Environmental and Molecular Mutagenesis — Mon, 08 Mar 2010 00:00:00 +0100

This study evaluates if the two BER polymorphisms (XRCC1Arg194Trp and OGG1Ser326Cys) or the combined genotypes of these polymorphisms with PON1Gln192Arg could modify individual susceptibility to pesticide exposure in vineyard workers, as measured by micronucleus formation and DNA damage induction in peripheral leukocytes. The study population comprised 108 agricultural workers exposed to pesticides and 65 nonexposed. Our results demonstrate that individuals with the variant allele (OGG1Cys) showed higher DNA damage, detected by the comet assay, in relation to individuals carrying the wild-type OGG1Ser allele. Considering the combined influence of metabolizing PON1 and the DNA repair OGG1 genes, we observed significantly higher DNA damage in the comet assay in the exposed group when a less ...

Genotoxicity of acrylamide in vitro: Acrylamide is not metabolically activated in standard in vitro systems

Environmental and Molecular Mutagenesis — Sun, 07 Mar 2010 00:00:00 +0100

The recent finding that acrylamide (AA), a genotoxic rodent carcinogen, is formed during the frying or baking of a variety of foods raises human health concerns. AA is known to be metabolized by cytochrome P450 2E1 (CYP2E1) to glycidamide (GA), which is responsible for AA's in vivo genotoxicity and probable carcinogenicity. In in-vitro mammalian cell tests, however, AA genotoxicity is not enhanced by rat liver S9 or a human liver microsomal fraction. In an attempt to demonstrate the in vitro expression of AA genotoxicity, we employed Salmonella strains and human cell lines that overexpress human CYP2E1. In the umu test, however, AA was not genotoxic in the CYP2E1-expressing Salmonella strain or its parental strain. Moreover, a transgenic human lymphoblastoid cell line overexpressing CYP2E1...

Mitochondria as decision-makers in cell death

Environmental and Molecular Mutagenesis — Sat, 06 Mar 2010 00:00:00 +0100

Mitochondria play an essential role in both cell health and death. Increasing experimental evidence suggests that mitochondria are involved in active control of cell death processes at several levels including (1) mitochondrial membrane permeabilization and release of proapoptotic proteins, (2) post-cytochrome c regulation of caspase activation, and (3) supply of energy for execution of death program. The purpose of this review is to discuss the main mechanisms by which alterations in mitochondrial outer membrane permit the translocation of proapoptotic proteins into cytosol, how mitochondria "make decisions" on the mode of cell death, and how they regulate caspase activation by changing the redox state of cytosolic cytochrome c. The interventions into these processes may constitute an imp...

Mutagenic repair of DNA interstrand crosslinks

Environmental and Molecular Mutagenesis — Fri, 05 Mar 2010 00:00:00 +0100

Formation of DNA interstrand crosslinks (ICLs) in chromosomal DNA imposes acute obstruction of all essential DNA functions. For over 70 years bifunctional alkylators, also known as DNA crosslinkers, have been an important class of cancer chemotherapeutic regimens. The mechanisms of ICL repair remains largely elusive. Here, we review a eukaryotic mutagenic ICL repair pathway discovered by work from several laboratories. This repair pathway, alternatively termed recombination-independent ICL repair, involves the incision activities of the nucleotide excision repair (NER) mechanism and lesion bypass polymerase(s). Repair of the ICL is initiated by dual incisions flanking the ICL on one strand of the double helix; the resulting gap is filled in by lesion bypass polymerases. The remaining lesio...

Targeting and processing of site-specific DNA interstrand crosslinks

Environmental and Molecular Mutagenesis — Tue, 02 Mar 2010 00:00:00 +0100

DNA interstrand crosslinks (ICLs) are among the most cytotoxic types of DNA damage, and thus ICL-inducing agents such as cyclophosphamide, melphalan, cisplatin, psoralen, and mitomycin C have been used clinically as anticancer drugs for decades. ICLs can also be formed endogenously as a consequence of cellular metabolic processes. ICL-inducing agents continue to be among the most effective chemotherapeutic treatments for many cancers; however, treatment with these agents can lead to secondary malignancies, in part due to mutagenic processing of the DNA lesions. The mechanisms of ICL repair have been characterized more thoroughly in bacteria and yeast than in mammalian cells. Thus, a better understanding of the molecular mechanisms of ICL processing offers the potential to improve the effic...

Poly (ADP-ribose) polymerase-1 deficiency does not affect ethylnitrosourea mutagenicity in liver and testis of lacZ transgenic mice

Environmental and Molecular Mutagenesis — Mon, 01 Mar 2010 00:00:00 +0100

Poly (ADP-ribose) polymerase-1 (Parp1) has been implicated in DNA base excision repair, single- and double-strand break repair pathways, as well as in cell death by apoptosis or necrosis. We used Parp1-/- lacZ plasmid-based transgenic mice to investigate whether Parp1 deficiency influences the in vivo mutagenic and clastogenic response to the alkylating agent N-ethyl-N-Nitrosourea (ENU) in somatic and germ-cell tissues. The comparison of the lacZ mutant frequencies (MFs) between Parp1+/+ and Parp1-/- mice showed that the ablation of Parp1 does not affect the spontaneous or ENU-induced MFs in liver and testis. In addition, the spectrum of the ENU-induced mutations was not dependent on the Parp1 status, given that similar spectra, consisting mostly of point mutations and a small fraction of ...

The SNM1/Pso2 family of ICL repair nucleases: From yeast to man

Environmental and Molecular Mutagenesis — Sat, 20 Feb 2010 00:00:00 +0100

Efficient interstrand crosslink (ICL) repair in yeast depends on the Pso2/Snm1 protein. Pso2 is a member of the highly conserved metallo-[beta]-lactamase structural family of nucleases. Mammalian cells possess three SNM1/Pso2 related proteins, SNM1A, SNM1B/Apollo, and SNM1C/Artemis. Evidence that SNM1A and SNM1B contribute to ICL repair is mounting, whereas Artemis appears to primarily contribute to non-ICL repair pathways, particularly some double-strand break repair events. Yeast Pso2 and all three mammalian SNM1-family proteins have been shown to possess nuclease activity. Here, we review the biochemical, genetic, and cellular evidence for the SNM1 family as DNA repair factors, focusing on ICL repair. Environ. Mol. Mutagen. 2010. © 2010 Wiley-Liss, Inc. (Source: Environmental and Molec...

Mitochondria as a target in treatment

Environmental and Molecular Mutagenesis — Fri, 19 Feb 2010 00:00:00 +0100

Mitochondria are key organelles that perform essential cellular functions and play pivotal roles in cell death and survival signaling. Hence, they represent an attractive target for drugs to treat metabolic, degenerative, and hyperproliferative diseases. Targeting mitochondria with organelle-specific agents or prodrugs has proven to be an effective therapeutic strategy. More specifically, controlling the cellular ROS balance via selective delivery of an antioxidant "payload" into mitochondria is an elegant emerging therapeutic concept. Herein, we review the recent medicinal chemistry and clinical data of these exploratory strategies, which should point the way for future generations of therapeutics. Environ. Mol. Mutagen. 2010. © 2010 Wiley-Liss, Inc. (Source: Environmental and Molecular ...

Strategies for DNA interstrand crosslink repair: Insights from worms, flies, frogs, and slime molds

Environmental and Molecular Mutagenesis — Tue, 09 Feb 2010 00:00:00 +0100

DNA interstrand crosslinks (ICLs) are complex lesions that covalently link both strands of the DNA double helix and impede essential cellular processes such as DNA replication and transcription. Recent studies suggest that multiple repair pathways are involved in their removal. Elegant genetic analysis has demonstrated that at least three distinct sets of pathways cooperate in the repair and/or bypass of ICLs in budding yeast. Although the mechanisms of ICL repair in mammals appear similar to those in yeast, important differences have been documented. In addition, mammalian crosslink repair requires other repair factors, such as the Fanconi anemia proteins, whose functions are poorly understood. Because many of these proteins are conserved in simpler metazoans, nonmammalian models have bec...

DNA damages induced by trans, trans-2,4-decadienal (tt-DDE), a component of cooking oil fume, in human bronchial epithelial cells

Environmental and Molecular Mutagenesis — Mon, 08 Feb 2010 00:00:00 +0100

Epidemiological studies have demonstrated that cooking oil fumes (COF) are an environmental risk factor for the development of lung adenocarcinoma among nonsmoking females in Taiwan. Aside from polycyclic aromatic hydrocarbons, aldehydes, especially trans, trans-2,4-decadienal (tt-DDE) are found to be abundant in COF. Although there is indication that tt-DDE induces DNA damage, the precise role of tt-DDE in the induction of DNA damage in lung cells is still not clear. When we assessed DNA breaks with the Comet assay, we found that the DNA breaks induced by 1 [mu]M tt-DDE in human bronchial epithelial cells (BEAS-2B) could be significantly reduced by antioxidants, suggesting that oxidative stress was involved. Indeed, when tt-DDE-treated cells were coincubated with endonuclease III/formamid...

A novel Escherichia coli-derived mutation detected with the Big Blue® cII mutant selectable assay

Environmental and Molecular Mutagenesis — Sat, 30 Jan 2010 00:00:00 +0100

We report the first direct evidence of an E. coli-derived cII mutation identified among mutations recovered in the cII selective assay. An E. coli transposable 5 (Tn5) element IS50R inverted repeat (1,534 bp) was identified at base pair 414 in the cII transgene and the insertion generated a 9 bp target site duplication typical of this type of transposition. The bacterial transposition occurred only once in the assay of 25 × 106 plaque forming units and sequencing of 1,177 cII mutants. The observed frequency of this type of mutation is 4 × 10-8 in retrieved [lambda] phage and 8.5 × 10-4 in harvested cII mutants and thus a very rare occurrence in typical analyses of spontaneous in vivo mutations. Given that the frequency of transposition is equal to, or an order of magnitude higher, than ...

DNA damage and toxicogenomic analyses of hydrogen sulfide in human intestinal epithelial FHs 74 Int cells

Environmental and Molecular Mutagenesis — Fri, 29 Jan 2010 00:00:00 +0100

This study defined the early (30 min) and late (4 hr) response of nontransformed human intestinal epithelial cells (FHs 74 Int) to H2S. The genotoxicity of H2S was measured using the single-cell gel electrophoresis (comet) assay. Changes in gene expression were analyzed after exposure to a genotoxic, but not cytotoxic, concentration of H2S (500 [mu]M H2S) using pathway-specific quantitative RT-PCR gene arrays. H2S was genotoxic in a concentration range from 250 to 2,000 [mu]M, which is similar to concentrations found in the large intestine. Significant changes in gene expression were predominantly observed at 4 hr, with the greatest responses by PTGS2 (COX-2; 7.92-fold upregulated) and WNT2 (7.08-fold downregulated). COX-2 was the only gene upregulated at both 30 min and 4 hr. Overall, the...

32P-postlabeling analysis of DNA adducts formed by leukotriene A4 (LTA4)

Environmental and Molecular Mutagenesis — Fri, 29 Jan 2010 00:00:00 +0100

Leukotriene A4 (LTA4), a reactive electrophilic intermediate formed during the biosynthesis of inflammation-related lipid mediators, has been found to bind covalently to DNA. The major DNA adducts formed by LTA4 in vitro and human cells have been identified by mass spectrometry on the nucleoside level. Here we investigated whether the thin-layer chromatography (TLC) 32P-postlabeling method is suitable for the detection of LTA4-DNA adducts. The reaction of individual deoxynucleoside 3[prime]-monophosphates with LTA4 in aqueous basic solution yielded numerous adduct spots when analyzed by the two enrichment procedures of the 32P-postlabeling method - nuclease P1 digestion and butanol extraction. Highest LTA4-adduct levels were found with deoxyguanosine 3[prime]-phosphate (around one adduct p...

The Fanconi anemia pathway promotes DNA glycosylase-dependent excision of interstrand DNA crosslinks

Environmental and Molecular Mutagenesis — Fri, 29 Jan 2010 00:00:00 +0100

Fanconi anemia (FA) is a recessive cancer prone syndrome featuring bone marrow failure and hypersensitivity to DNA interstrand crosslinks (ICLs) and, to a milder extension, to ionizing radiation and oxidative stress. Recently, we reported that human oxidative DNA glycosylase, NEIL1 excises with high efficiency the unhooked crosslinked oligomer within three-stranded DNA repair intermediate induced by photoactivated psoralen exposure. Complete reconstitution of repair of the ICL within a three-stranded DNA structure shows that it is processed in the short-patch base excision repair (BER) pathway. To examine whether the DNA damage hypersensitivity in FA cells follows impaired BER activities, we measured DNA glycosylase and AP endonuclease activities in cell-free extracts from wild-type, FA, a...

Carbon nanotubes induce oxidative DNA damage in RAW 264.7 cells

Environmental and Molecular Mutagenesis — Wed, 20 Jan 2010 00:00:00 +0100

The induction of DNA and chromosome damage following in vitro exposure to carbon nanotubes (CNT) was assessed on the murine macrophage cell line RAW 264.7 by means of the micronucleus (MN) and the comet assays. Exposures to two CNT preparations (single-walled CNT (SWCNT > 90%) and multiwalled CNT (MWCNT > 90%) were performed in increasing mass concentrations (0.01-100 [mu]g/ml). The frequency of micronuclei was significantly increased in cells treated with SWCNT (at doses above 0.1 [mu]g/ml), whereas MWCNT had the same effect at higher concentrations (1 [mu]g/ml) (P < 0.05). The results of the comet assay revealed that the effects of treatment with SWCNT were detectable at all concentrations tested (1-100 [mu]g/ml); oxidized purines increased significantly, whereas pyrimidines showed a sig...

Bootstrap estimation of confidence intervals on mutation rate ratios

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Follow‐up actions from positive results of in vitro genetic toxicity testing

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Comparison of in vitro micronucleus and gene mutation assay results for p53‐competent versus p53‐deficient human lymphoblastoid cells

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

In vitro micronucleus screening of pharmaceutical candidates by flow cytometry in Chinese hamster V79 cells

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

A flow cytometry based in vitro micronucleus assay in TK6 cells—Validation using early stage pharmaceutical development compounds

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Selected technologies for measuring acquired genetic damage in humans

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Memorial for John Wassom

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

(Source: Environmental and Molecular Mutagenesis)

The rat gut micronucleus assay: A good choice for alternative in vivo genetic toxicology testing strategies

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

DNA repair and personalized breast cancer therapy

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Physical‐chemical and microbiological characterization, and mutagenic activity of airborne PM sampled in a biomass‐fueled electrical production facility

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Possible structural and functional determinants contributing to the clastogenicity of pharmaceuticals

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Determination of genetic damage and urinary metabolites in fuel filling station attendants

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)

Genotoxic effects of three selected black toner powders and their dimethyl sulfoxide extracts in cultured human epithelial A549 lung cells in vitro

Environmental and Molecular Mutagenesis — Fri, 01 Jan 2010 00:00:00 +0100

Abstract (Source: Environmental and Molecular Mutagenesis)