Environmental and Molecular Mutagenesis via MedWorm.com

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...

Induction of lacZ mutations in MutaTMMouse primary hepatocytes

Environmental and Molecular Mutagenesis — Wed, 02 Dec 2009 00:00:00 +0100

We have developed an in vitro mutation assay using primary hepatocytes from the transgenic MutaTMMouse. Primary hepatocytes were isolated using a two-step perfusion method with purification by Percoll, cultured, and treated with benzo[a]pyrene (BaP), 2-amino-1-methyl-6-phenyl- imidazo[4,5-b]pyridine (PhIP), 3-nitrobenzoanthrone (3-NBA), and cigarette smoke condensate (CSC). The mean lacZ mutant frequency (MF) for the solvent control was approximately twofold greater than the spontaneous MF observed in liver tissue. A concentration-dependent increase in MF (up to 3.7-fold above control) was observed following exposure to BaP. Fourfold and twofold increases in mutant frequency were observed for 3-NBA and PhIP exposures, respectively, without the addition of any exogenous metabolic activation...

High content flow cytometric micronucleus scoring method is applicable to attachment cell lines

Environmental and Molecular Mutagenesis — Tue, 01 Dec 2009 00:00:00 +0100

A flow cytometric method for analyzing suspension cell cultures for micronucleus content has been previously reported (Avlasevich et al. [2006]: Environ Mol Mutagen 47: 56-66). The experiments described herein were undertaken to evaluate the compatibility of this method (In Vitro MicroFlow®) with attachment cells. Initially, CHO-K1 cells were studied in nine independent experiments using mitomycin C and cyclophosphamide. The results demonstrated the effectiveness of the cell processing procedure, and also provided historical control data that were useful for setting criteria for making positive calls. Subsequently, CHO-K1 cells were treated with methyl methanesulfonate, mitomycin C, etoposide, vinblastine sulfate, dexamethasone, and sodium chloride. Whereas the four genotoxicants were eac...

Cytogenetic status in newborns and their parents in Madrid: The BioMadrid study

Environmental and Molecular Mutagenesis — Mon, 30 Nov 2009 00:00:00 +0100

Monitoring cytogenetic damage is frequently used to assess population exposure to environmental mutagens. The cytokinesis-block micronucleus assay is one of the most widely used methods employed in these studies. In the present study we used this assay to assess the baseline frequency of micronuclei in a healthy population of father-pregnant woman-newborn trios drawn from two Madrid areas. We also investigated the association between micronucleus frequency and specific socioeconomic, environmental, and demographic factors collected by questionnaire. Mercury, arsenic, lead, and cadmium blood levels were measured by atomic absorption spectrometry. The association between micronucleated cell frequency and the variables collected by questionnaire, as well as, the risk associated with the prese...

Flow cytometry peripheral blood micronucleus test in vivo: Determination of potential thresholds for aneuploidy induced by spindle poisons

Environmental and Molecular Mutagenesis — Mon, 30 Nov 2009 00:00:00 +0100

Non-DNA binding genotoxins (e.g., aneugens), unlike DNA-binding genotoxins, are theoretically expected to show thresholded concentration-effect response curves. This is a major issue in genetic toxicology testing because the identification of thresholds in vivo can provide a safety margin for exposure to a particular compound. In the current study we measured micronucleus induction by flow cytometry to determine the dose-response curves for tubulin interacting agents, a specific class of aneugens. All experiments with aneugens, which include colchicine, vinblastine, vincristine, as well as the clastogen cyclophosphamide (CP) were performed in mice to avoid the splenic elimination of micronucleated reticulocytes, which has been described in rats. Flow cytometry analysis revealed a non-linea...

Antigenotoxic potential of Gymnema montanum leaves on DNA damage in human peripheral blood lymphocytes and HL-60 cell line

Environmental and Molecular Mutagenesis — Mon, 30 Nov 2009 00:00:00 +0100

In this study we have evaluated the genoprotective effect of the ethanol extract of Gymnema montanum (GLEt) leaves in human peripheral blood lymphocytes and HL-60 cell line in vitro using the comet assay. DNA damage was induced by treating the cells with H2O2 and methyl methane sulphonate (MMS). GLEt treatment effectively protected the lymphocytes and HL-60 cell line from H2O2-induced oxidative DNA damage in a dose-dependent manner whereas it was not effective against alkylative DNA damage caused by MMS. The global percent repair efficiency also showed that both pre- and post- GLEt treatment provided effective protection against H2O2 induced DNA damage but not as effective against MMS. At 200 [mu]g ml-1 level, its repair capacity against H2O2 induced DNA damage was comparable to that of vi...

Genotoxicity of a freshwater cyanotoxin, cylindrospermopsin, in two human cell lines: Caco-2 and HepaRG

Environmental and Molecular Mutagenesis — Tue, 10 Nov 2009 00:00:00 +0100

Cylindrospermopsin (CYN), a cyanotoxin produced by certain freshwater cyanobacteria, causes human intoxications and animal mortalities. CYN is a potent inhibitor of protein- and glutathione-synthesis. Preliminary evidence for in vivo tumor initiation has been found in mice but the mechanism remains unclear. Several in vitro and in vivo studies demonstrate that CYN is genotoxic and requires metabolic activation. In the present study, the genotoxicity of CYN was assessed in human hepatocyte and enterocyte cell lines, which are models for CYN target organs. The cytokinesis-block micronucleus assay was conducted on liver-derived HepaRG cells and colon-derived Caco-2 cells. Each cell-type was exposed to CYN in both the differentiated and the undifferentiated states, and both with and without th...

Effect of O6-chloroethylguanine DNA lesions on the kinetics and mechanism of micronucleus induction in vivo

Environmental and Molecular Mutagenesis — Tue, 20 Oct 2009 23:00:00 +0100

We examined groups of five mice treated with (i) dimethylsulfoxide (DMSO), (ii) O6BG in DMSO, (iii) BCNU, or (iv) O6BG in DMSO plus BCNU. The data indicate that O6BG pretreatment causes: (i) ían increase in MN-PCEs induced by BCNU, (ii) a delay in the time of maximal MN-PCE induction produced by the different BCNU doses, and (iii) an increase in cytotoxicity. These data confirm that O6-ChlEt-G is a lesion involved in DNA break induction and in the subsequent production of micronuclei, and also that these lesions seem to be stoichiometrically reduced by MGMT. These data also show that induction of MN-PCEs by BCNU is delayed by pretreatment with O6BG for more than 6 hr, perhaps due to the time required for repair of crosslinks derived from O6-ChlEt-G and/or for DNA duplication, which is req...

Excretion characteristics of urinary 8-hydroxydeoxyguanosine after dietary exposure to polycyclic aromatic hydrocarbons

Environmental and Molecular Mutagenesis — Mon, 19 Oct 2009 23:00:00 +0100

Urinary 8-hydroxydeoxyguanosine (8-OHdG) is considered a noninvasive marker for oxidative stress and also a marker of carcinogenic potential for compounds such as polycyclic aromatic hydrocarbons (PAHs). Although human studies have investigated urinary 8-OHdG concentrations in PAH-exposed workers and the general population, the background level and excretion kinetics of urinary 8-OHdG in humans remain unclear. Two feeding experiments (consumption of barbecued meat of 15 and 30 g/kg for Experiments 1 and 2, respectively) were conducted to examine the excretion characteristics of urinary 8-OHdG. All urine voided over 7 days was collected, but only first morning ([sim]8 A.M.) and last afternoon ([sim]5 P.M.) samples were analyzed for 8-OHdG. Mean background urinary 8-OHdG concentration was 4....

DNA damage and oxidative stress in human liver cell L-02 caused by surface water extracts during drinking water treatment in a waterworks in China

Environmental and Molecular Mutagenesis — Mon, 19 Oct 2009 23:00:00 +0100

Because of the daily and life-long exposure to disinfection by-products formed during drinking water treatment, potential adverse human health risk of drinking water disinfection is of great concern. Toxicological studies have shown that drinking water treatment increases the genotoxicity of surface water. Drinking water treatment is comprised of different potabilization steps, which greatly influence the levels of genotoxic products in the surface water and thus may alter the toxicity and genotoxicity of surface water. The aim of the present study was to understand the influence of specific steps on toxicity and genotoxicity during the treatment of surface water in a water treatment plant using liquid chlorine as the disinfectant in China. An integrated approach of the comet and oxidative...

Formaldehyde and leukemia: Epidemiology, potential mechanisms, and implications for risk assessment

Environmental and Molecular Mutagenesis — Tue, 29 Sep 2009 23:00:00 +0100

Formaldehyde is widely used in the United States and other countries. Occupational and environmental exposures to formaldehyde may be associated with an increased risk of leukemia in exposed individuals. However, risk assessment of formaldehyde and leukemia has been challenging due to inconsistencies in human and animal studies and the lack of a known mechanism for leukemia induction. Here, we provide a summary of the symposium at the Environmental Mutagen Society Meeting in 2008, which focused on the epidemiology of formaldehyde and leukemia, potential mechanisms, and implication for risk assessment, with emphasis on future directions in multidisciplinary formaldehyde research. Updated results of two of the three largest industrial cohort studies of formaldehyde-exposed workers have shown...

Flow cytometric scoring of micronucleated reticulocytes as a possible high-throughput radiation biodosimeter

Environmental and Molecular Mutagenesis — Mon, 28 Sep 2009 23:00:00 +0100

Micronucleated reticulocyte (MN-RET) scoring by flow cytometry (FCM) has been used in assessment of the clastogenic effects of chemicals. However, its dose-response to acute whole body irradiation (WBI) at moderate dose rates remains to be established. We show that FCM scoring of MN-RET in peripheral blood from male ICR mice exposed to WBI X-ray doses of 0.5-5 Gy at a dose rate of 0.488 Gy/min exhibits a linear dose-response relationship 24, 48, and 72 hr following WBI. Parallel microscopic counting of micronucleated polychromatic erythrocytes (MN-PCE) in bone marrow smears from the same animals showed similar linear dose-response patterns at the same time points. Indeed, MN-RET and MN-PCE were highly correlated at all doses and time points. In view of the speed and accuracy of this method...

Cytogenetic genotoxicity of amoxicillin

Environmental and Molecular Mutagenesis — Mon, 28 Sep 2009 23:00:00 +0100

In this study, AMO did not induce SCEs or CAs in human peripheral blood lymphocytes both in the presence and absence of the metabolic activator. AMO concentration-dependently decreased the proliferation index (PI) in the absence of the metabolic activation for 24-hr treatment period. Mitotic index (MI) was generally found to have been reduced when compared with the negative control but not with the solvent control in cultures treated with AMO for 24 hr. AMO did not decrease the PI and MI in the presence of the metabolic activator. Furthermore, AMO neither induced the formation of MN nor decreased the nuclear division index in human peripheral blood lymphocytes both in the presence and absence of the metabolic activator. According to the present results, we suggest that AMO does not pose ge...

Centrosome structure and function under normal and pathological conditions

Environmental and Molecular Mutagenesis — Tue, 22 Sep 2009 23:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Induction of aneuploidy by single-walled carbon nanotubes

Environmental and Molecular Mutagenesis — Mon, 21 Sep 2009 23:00:00 +0100

Engineered carbon nanotubes are newly emerging manufactured particles with potential applications in electronics, computers, aerospace, and medicine. The low density and small size of these biologically persistent particles makes respiratory exposures to workers likely during the production or use of commercial products. The narrow diameter and great length of single-walled carbon nanotubes (SWCNT) suggest the potential to interact with critical biological structures. To examine the potential of nanotubes to induce genetic damage in normal lung cells, cultured primary and immortalized human airway epithelial cells were exposed to SWCNT or a positive control, vanadium pentoxide. After 24 hr of exposure to either SWCNT or vanadium pentoxide, fragmented centrosomes, multiple mitotic spindle p...

Aurora A, centrosome structure, and the centrosome cycle

Environmental and Molecular Mutagenesis — Mon, 21 Sep 2009 23:00:00 +0100

The centrosome, also known as the microtubule organizing center of the cell, is a membrane-less organelle composed of a pair of barrel-shaped centrioles surrounded by electron-dense pericentriolar material. The centrosome progresses through the centrosome cycle in step with the cell cycle such that centrosomes are duplicated in time to serve as the spindle poles during mitosis and that each resultant daughter cell contains a single centrosome. Regulation of the centrosome cycle with relation to the cell cycle is an essential process to maintain the ratio of one centrosome per new daughter cell. Numerous mitosis-specific kinases have been implicated in this regulation, and phosphorlyation plays an important role in coordinating the centrosome and cell cycles. Centrosome amplification can oc...

Nucleation capacity and presence of centrioles define a distinct category of centrosome abnormalities that induces multipolar mitoses in cancer cells

Environmental and Molecular Mutagenesis — Sun, 20 Sep 2009 23:00:00 +0100

Analysis of centrosome number and structure has become one means of assessing the potential for aberrant chromosome segregation and aneuploidy in tumor cells. Centrosome amplification directly causes multipolar catastrophic mitoses in mouse embryonic fibroblasts (MEFs) deficient for the tumor suppressor genes Brca1 or Trp53. We observed supernumerary centrosomes in cell lines established from aneuploid, but not from diploid, colorectal carcinomas; however, multipolar mitoses were never observed. This discrepancy prompted us to thoroughly characterize the centrosome abnormalities in these and other cancer cell lines with respect to both structure and function. The most striking result was that supernumerary centrosomes in aneuploid colorectal cancer cell lines were unable to nucleate microt...

Human cell toxicogenomic analysis of bromoacetic acid: A regulated drinking water disinfection by-product

Environmental and Molecular Mutagenesis — Mon, 14 Sep 2009 23:00:00 +0100

The objective of this research was to integrate in vitro toxicology with focused toxicogenomic analysis of the regulated DBP, bromoacetic acid (BAA) and to evaluate modulation of gene expression involved in DNA damage/repair and toxic responses, with nontransformed human cells. We generated transcriptome profiles for 168 genes with 30 min and 4 hr exposure times that did not induce acute cytotoxicity. Using qRT-PCR gene arrays, the levels of 25 transcripts were modulated to a statistically significant degree in response to a 30 min treatment with BAA (16 transcripts upregulated and nine downregulated). The largest changes were observed for RAD9A and BRCA1. The majority of the altered transcript profiles are genes involved in DNA repair, especially the repair of double strand DNA breaks, an...

Centrosomes and myeloma; Aneuploidy and proliferation

Environmental and Molecular Mutagenesis — Tue, 08 Sep 2009 23:00:00 +0100

Multiple myeloma is the second most common hematological malignancy in the United States. The disease is characterized by an accumulation of clonal plasma cells. Clinically, patients present with anemia, lytic bone lesions, hypercalcaemia, or renal impairment. The genome of the malignant plasma cells is extremely unstable and is typically aneuploid and characterized by a complex combination of structure and numerical abnormalities. The basis of the genomic instability underlying myeloma is unclear. In this regard, centrosome amplification is present in about a third of myeloma and may represent a mechanism leading to genomic instability in myeloma. Centrosome amplification is associated with high-risk features and poor prognosis. Understanding the underlying etiology of centrosome amplific...

Homage to Theodor Boveri (1862-1915): Boveri's theory of cancer as a disease of the chromosomes, and the landscape of genomic imbalances in human carcinomas

Environmental and Molecular Mutagenesis — Mon, 07 Sep 2009 23:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Synergistic genotoxicity caused by low concentration of titanium dioxide nanoparticles and p,p[prime]-DDT in human hepatocytes

Environmental and Molecular Mutagenesis — Tue, 25 Aug 2009 23:00:00 +0100

The use of titanium dioxide nanoparticles (nano-TiO2) for the degradation of dichlorodiphenyltrichloroethane (p,p[prime]-DDT) increases the risk of exposure to trace nano-TiO2 and p,p[prime]-DDT mixtures. The interaction of p,p[prime]-DDT and nano-TiO2 at low concentrations may alter toxic response relative to nano-TiO2 or p,p[prime]-DDT alone. In this work, the combined genotoxicity of trace nano-TiO2 and p,p[prime]-DDT on human embryo L-02 hepatocytes without photoactivation was studied. Nano-TiO2 (0.1 g/L) was mixed with 0.01-1 mmol/L p,p[prime]-DDT to determine adsorption isotherms. L-02 cells were exposed to different levels of p,p[prime]-DDT (0, 0.001, 0.01, and 0.1 [mu]mol/L) and nano-TiO2 (0, 0.01, 0.1, and 1 [mu]g/mL) respectively. The adsorption of p,p[prime]-DDT by nano-TiO2 was...

Mutagenicity of blue rayon extracts of fish bile as a biomarker in a field study

Environmental and Molecular Mutagenesis — Mon, 24 Aug 2009 23:00:00 +0100

Blue rayon (BR) in combination with the Salmonella/microsome assay was used to evaluate the mutagenicity of fish bile samples. Specimens of Mugil curema from two sites were collected over a 1-year period. Piaçaguera channel contains high concentrations of total polycyclic aromatic hydrocarbons (PAHs) and other contaminants, while Bertioga channel was considered the reference sites in this study. Bile was extracted with BR and tested with TA98, TA100, and YG1041 strains with and without S9 in dose response experiments. PAH metabolite equivalents were analyzed using reverse-phase high performance liquid chromatography /fluorescence. Higher mutagenic responses were observed for the contaminated site; YG1041 with S9 was the most sensitive strain/condition. Mutagenicity ranged from 3,900 to 14...

An evaluation of the mode of action framework for mutagenic carcinogens case study II: Chromium (VI)

Environmental and Molecular Mutagenesis — Mon, 24 Aug 2009 23:00:00 +0100

In response to the 2005 revised U.S Environmental Protection Agency's (EPA) Cancer Guidelines, a strategy is being developed to include all mutagenicity and other genotoxicity data with additional information to determine whether the initiating step in carcinogenesis is through a mutagenic mode of action (MOA). This information is necessary to decide if age-dependent adjustment factors (ADAFs) should be applied to the risk assessment. Chromium (VI) [Cr (VI)], a carcinogen in animals and humans via inhalation, was reassessed by the National Toxicology Program (NTP) in 2-year drinking water studies in rodents. From these data, NTP concluded that the results with Cr (VI) showed clear evidence of carcinogenicity in male and female mice and rats. Cr (VI) is also mutagenic, in numerous in vitro ...

Micronucleus assay for mouse alveolar Type II and Clara cells

Environmental and Molecular Mutagenesis — Mon, 24 Aug 2009 23:00:00 +0100

The objective of our study was to develop a micronucleus (MN) assay for detecting genotoxic damage after inhalation exposure in mouse alveolar Type II and Clara cells, potential target cells for lung carcinogens. Ten male C57BL/6J mice were exposed to ethylene oxide (630 mg/m3) for 4 hr via inhalation; 10 unexposed mice serving as controls. 72 hr after the exposure, Clara cells and alveolar Type II cells were isolated using two different methods. Method 1 included a 15-min trypsin lavage and a 2-hr incubation of cell suspension. Method 2 involved a 30-min trypsin lavage, Percoll gradient centrifugation, and a 48-hr incubation for cell attachment. Nitro blue tetrazolium (NBT) -staining was applied to distinguish Clara cells. The frequency of micronuclei (MNi) was scored in NBT-negative cell...

The human lung cell line A549 does not develop adaptive protection against the DNA-damaging action of formaldehyde

Environmental and Molecular Mutagenesis — Thu, 20 Aug 2009 23:00:00 +0100

The alkaline comet assay was used to further characterize the induction of DNA-protein crosslinks (DPX) by formaldehyde (FA) and their removal in the human lung cell line A549. DPX were indirectly measured as the reduction of gamma ray-induced DNA migration. Repeated treatments of A549 cells with low FA concentrations (up to 100 [mu]M) did not lead to significant differences in the induction of DPX in comparison with a single treatment. Pretreatment with higher FA-concentrations (200 [mu]M and above) enhanced the crosslinking effect. There was no indication for an adaptive protection against the induction of DPX by FA. These findings are in agreement with RT-PCR measurements of the expression of genes that encode the main enzymes involved in FA detoxification. A549 cells exposed to FA (50-...

Environmental Mutagen Society 40th Annual Meeting Abstracts

Environmental and Molecular Mutagenesis — Mon, 10 Aug 2009 23:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Flow cytometric detection of Pig-A mutant red blood cells using an erythroid-specific antibody: Application of the method for evaluating the in vivo genotoxicity of methylphenidate in adolescent rats

Environmental and Molecular Mutagenesis — Wed, 05 Aug 2009 23:00:00 +0100

A modified flow cytometry assay for Pig-A mutant rat red blood cells (RBCs) was developed using an antibody that positively identifies rat RBCs (monoclonal antibody HIS49). The assay was used in conjunction with a flow cytometric micronucleus (MN) assay to evaluate gene mutation and clastogenicity/aneugenicity in adolescent male and female rats treated with methylphenidate hydrochloride (MPH). Sprague-Dawley rats were treated orally with 3 mg/kg MPH (70/sex) or water (40/sex) 3 × /day on postnatal days (PNDs) 29-50. Eight additional rats (4/sex) were injected i.p. with N-ethyl-N-nitrosourea (ENU) on PND 28. Blood was collected on PNDs 29, 50, and 90, and used for determining serum MPH levels and/or conducting genotoxicity assays. On the first and last days of MPH treatment (PNDs 29 and 50...

K-Ras mutant fraction in A/J mouse lung increases as a function of benzo[a]pyrene dose

Environmental and Molecular Mutagenesis — Tue, 04 Aug 2009 23:00:00 +0100

K-Ras mutant fraction (MF) was measured to examine the default assumption of low-dose linearity in the benzo[a]pyrene (B[a]P) mutational response. Groups of 10 male A/J mice (7- to 9-weeks old) received a single i.p. injection of 0, 0.05, 0.5, 5, or 50 mg/kg B[a]P and were sacrificed 28 days after treatment. K-Ras codon 12 TGT and GAT MFs in lung DNAs were measured using Allele-specific Competitive Blocker-PCR (ACB-PCR). The K-Ras codon 12 TGT geometric mean MF was 3.88 × 10-4 in controls, indicating an average of 1 mutation in every [sim]1,288 lung cells. The K-Ras codon 12 TGT geometric mean MFs were as follows: 3.56 × 10-4; 6.19 × 10-4; 2.02 × 10-3, and 3.50 × 10-3 for the 0.05, 0.5, 5, and 50 mg/kg B[a]P treatment groups, respectively. The 5 and 50 mg/kg dose groups had TGT MFs si...

Differential mutagenicity of aflatoxin B1 in the liver of neonatal and adult mice

Environmental and Molecular Mutagenesis — Wed, 29 Jul 2009 23:00:00 +0100

In this study, we have evaluated the effect of age on the mutagenicity of the fungal toxin and liver carcinogen aflatoxin B1 (AFB1). Neonatal Big Blue transgenic mice were treated with 6 mg/kg AFB1, a treatment that produces liver tumors, while adult mice were treated with 6 and 60 mg/kg AFB1, treatments that do not result in tumors. The cII liver mutant frequency (MF) in mice treated with AFB1 as neonates was 22-fold higher than in control neonatal mice, whereas the treatment of adult mice with either dose of AFB1 did not significantly increase the liver MF over the controls. In AFB1-treated neonatal mice, the frequency of G:C [rarr] T:A transversion, a major type of mutation induced by AFB1, was about 82-fold higher than for the control and 31-fold higher than for adult mice treated with...

DNA adduct kinetics in reproductive tissues of DNA repair proficient and deficient male mice after oral exposure to benzo(a)pyrene

Environmental and Molecular Mutagenesis — Fri, 24 Jul 2009 23:00:00 +0100

Benzo(a)pyrene (B[a]P) can induce somatic mutations, whereas its potential to induce germ cell mutations is unclear. There is circumstantial evidence that paternal exposure to B[a]P can result in germ cell mutations. Since DNA adducts are thought to be a prerequisite for B[a]P induced mutations, we studied DNA adduct kinetics by 32P-postlabeling in sperm, testes and lung tissues of male mice after a single exposure to B[a]P (13 mg/kg bw, by gavage). To investigate DNA adduct formation at different stages of spermatogenesis, mice were sacrificed at Day 1, 4, 7, 10, 14, 21, 32, and 42 after exposure. In addition, DNA repair deficient (Xpc-/-) mice were used to study the contribution of nucleotide excision repair in DNA damage removal. DNA adducts were detectable with highest levels in lung f...

No increases in biomarkers of genetic damage or pathological changes in heart and brain tissues in male rats administered methylphenidate hydrochloride (Ritalin) for 28 days

Environmental and Molecular Mutagenesis — Thu, 23 Jul 2009 23:00:00 +0100

Following a 2005 report of chromosomal damage in children with attention deficit/hyperactivity disorder (ADHD) who were treated with the commonly prescribed medication methylphenidate (MPH), numerous studies have been conducted to clarify the risk for MPH-induced genetic damage. Although most of these studies reported no changes in genetic damage endpoints associated with exposure to MPH, one recent study (Andreazza et al. []: Prog Neuropsychopharmacol Biol Psychiatry 31:1282-1288) reported an increase in DNA damage detected by the Comet assay in blood and brain cells of Wistar rats treated by intraperitoneal injection with 1, 2, or 10 mg/kg MPH; no increases in micronucleated lymphocyte frequencies were observed in these rats. To clarify these findings, we treated adult male Wistar Han ra...

Expression of caspase and apoptotic signal pathway induced by sulfur dioxide

Environmental and Molecular Mutagenesis — Mon, 20 Jul 2009 23:00:00 +0100

Sulfur dioxide (SO2) is a common air pollutant that is released in low concentrations into the atmosphere and in higher concentrations in some work places. In the present study, male Wistar rats were housed in exposure chambers and treated with 14.00 ± 1.01, 28.00 ± 1.77, and 56.00 ± 3.44 mg/m3 SO2 for 7 days (6 hr/day), while control rats were exposed to filtered air under the same conditions. The mRNA and protein levels of caspase-3, caspase-8, and caspase-9 were analyzed using a real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) assay and an immunohistochemistry method. Activities of caspases were detected using colorimetric and fluorescent assays. Chromatin degradation and cell morphological changes were investigated by TUNEL assay and H&E staining in liver...

Mutagen structure and transcriptional response: Induction of distinct transcriptional profiles in Salmonella TA100 by the drinking-water mutagen MX and its homologues

Environmental and Molecular Mutagenesis — Mon, 13 Jul 2009 23:00:00 +0100

The relationship between chemical structure and biological activity has been examined for various compounds and endpoints for decades. To explore this question relative to global gene expression, we performed microarray analysis of Salmonella TA100 after treatment under conditions of mutagenesis by the drinking-water mutagen MX and two of its structural homologues, BA-1, and BA-4. Approximately 50% of the genes expressed differentially following MX treatment were unique to MX; the corresponding percentages for BA-1 and BA-4 were 91 and 80, respectively. Among these mutagens, there was no overlap of altered Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways or RegulonDB regulons. Among the 25 Comprehensive Microbial Resource functions altered by these mutagens, only four were altered b...

Maintenance of bivalve hemocytes for the purpose of delayed DNA strand break assessment using the comet assay

Environmental and Molecular Mutagenesis — Fri, 10 Jul 2009 23:00:00 +0100

The lack of appropriate methods for storing intact and viable cells for the purpose of delayed DNA strand break analysis has hitherto limited the application of the Comet assay to in vitro or in vivo laboratory studies and restricted ecologically more relevant field-collected samples to sites in proximity to suitable laboratory facilities. In the present article, osmotically corrected cell culture media Hanks Balanced Salt Solution (HBSS) and Leibovitz Media (L-15) were assessed for their suitability as temporary storage media of blue mussel (Mytilus edulis) hemocytes. It was found that hemocytes maintained in either HBSS or L-15 could be stored for at least 7 days at 4°C without any significant deterioration in cell viability (Trypan blue) or increase in DNA strand breaks, expressed as %...

Centrosome abnormalities during porcine oocyte aging

Environmental and Molecular Mutagenesis — Thu, 09 Jul 2009 23:00:00 +0100

This study reports the dynamic changes of centrosomes and the microtubule cytoskeleton in porcine oocytes during aging and treatment by caffeine to restore spindle integrity in aging oocytes. We tested the effects of caffeine on the MII spindle with focus on microtubules and on the centrosome proteins [gamma]-tubulin and NuMA (nuclear mitotic apparatus protein). The results revealed that in porcine oocytes aged for 48 hr, centrosomes were absent and spindles became abnormal and disorganized; however, caffeine could prevent these changes or restore centrosome integrity in the meiotic spindle poles and displayed similar MII spindles as those seen in fresh oocytes. Environ. Mol. Mutagen., 2009. © 2009 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Role of the CYP2D6, EPHX1, MPO, and NQO1 genes in the susceptibility to acute lymphoblastic leukemia in Brazilian children

Environmental and Molecular Mutagenesis — Thu, 09 Jul 2009 23:00:00 +0100

The objective of the present study was to evaluate the effect of the polymorphisms of debrisoquine hydroxylase (CYP2D6), epoxide hydrolase (EPHX1), myeloperoxidase (MPO), and quinone-oxoreductase (NQO1), which have been implicated in xenobiotic metabolism, on the risk of childhood acute lymphoblastic leukemia (ALL). We evaluated the frequency of polymorphisms in the CYP2D6 (*3 and *4), EPHX1 (*2 and *3), MPO (*2), and NQO1 (*2) genes in 206 patients with childhood ALL and in 364 healthy individuals matched for age and gender from a Brazilian population separated by ethnicity (European ancestry and African ancestry), using the PCR-RFLP method. The CYP2D6 polymorphism variants were associated with an increased risk of ALL. The EPHX1, NQO1, and MPO variant genotypes were significantly associa...

Neutrophil oxidative metabolism in Down syndrome patients with congenital heart defects

Environmental and Molecular Mutagenesis — Thu, 09 Jul 2009 23:00:00 +0100

Down syndrome (DS) occurs when an individual has three, rather than two, copies of the 21st chromosome. Cytosolic superoxide dismutase (SOD-1) is encoded by a gene on chromosome 21 and thus, SOD-1 activity is elevated in patients with DS. Forty percent of all cases with DS are associated with congenital heart defects (CHD). Although the contribution of SOD1 to disease phenotype is unknown, it is considered to be a "molecular marker" of the disease. It was hypothesized herein that the presence of CHD may alter the expression of SOD1 and oxidative metabolism in patients with DS. This hypothesis was tested via four experimental groups as follows: patients with DS without CHD, DS patients with CHD, CHD patients without DS and controls. Expression and activity of superoxide dismutase (SOD), glu...

Hypothesis: Bifunctional mitochondrial proteins have centrosomal functions

Environmental and Molecular Mutagenesis — Mon, 29 Jun 2009 23:00:00 +0100

Mitochondria are dynamic organelles that are involved in a number of diverse processes. Most often the mitochondrion is associated with energy generation, but other important processes occur in this organelle such as fatty acid synthesis and amino acid metabolism. Although mitochondria encode less than 40 genes, all of the other [sim]1,000 genes required for their function are nuclear encoded. The protein products from these nuclear encoded genes are subsequently translocated to the mitochondria and utilized in the variety of processes within the organelle. Is it possible then that any of these nuclear encoded proteins could be translocated to other areas of the cell to participate in functions not normally attributed to the mitochondria? There is growing evidence that mitochondrial protei...

Centrosome amplification induced by the antiretroviral nucleoside reverse transcriptase inhibitors lamivudine, stavudine, and didanosine

Environmental and Molecular Mutagenesis — Fri, 26 Jun 2009 23:00:00 +0100

In cultured cells, exposure to the nucleoside reverse transcriptase inhibitor (NRTI) zidovudine (AZT) induces genomic instability, cell cycle arrest, micronuclei, sister chromatid exchanges, and shortened telomeres. In previous studies, we demonstrated AZT-induced centrosome amplification (>2 centrosomes/cell). Here, we investigate centrosome amplification in cells exposed to other commonly used NRTIs. Experiments were performed using Chinese Hamster ovary (CHO) cells, and two normal human mammary epithelial cell (NHMEC) strains: M99005 and M98040, which are high and low incorporators of AZT into DNA, respectively. Cells were exposed for 24 hr to lamivudine (3TC), stavudine (d4T), didanosine (ddI), and thymidine, and stained with anti-pericentrin antibody. Dose response curves were perform...

Concordance analysis of an in vitro micronucleus screening assay and the regulatory chromosome aberration assay using pharmaceutical drug candidates

Environmental and Molecular Mutagenesis — Wed, 24 Jun 2009 23:00:00 +0100

The in vitro micronucleus assay is under consideration by regulatory agencies as a suitable alternative to the in vitro chromosome aberration (CA) assay. At Pfizer, we utilized a non-Good Laboratory practices cytokinesis-block in vitro micronucleus (CBMN) assay in CHO cells as a screen to predict the regulatory outcome of the human lymphocyte CA assay, and we have retrospectively analyzed a highly select set of 112 internal drug candidates to measure concordance. Overall, our exploratory CBMN correctly classified 97 of 112 (86.6%) compounds in the CA assay. Specificity was high with 87 of 92 (94.6%) CA negative compounds correctly classified by CBMN. Sensitivity was low at 50% with 10 of 20 CA positive compounds correctly classified by CBMN; this may be attributed to the low number of CA p...

Analysis of genomic dose-response information on arsenic to inform key events in a mode of action for carcinogenicity

Environmental and Molecular Mutagenesis — Mon, 22 Jun 2009 23:00:00 +0100

A comprehensive literature search was conducted to identify information on gene expression changes following exposures to inorganic arsenic compounds. This information was organized by compound, exposure, dose/concentration, species, tissue, and cell type. A concentration-related hierarchy of responses was observed, beginning with changes in gene/protein expression associated with adaptive responses (e.g., preinflammatory responses, delay of apoptosis). Between 0.1 and 10 [mu]M, additional gene/protein expression changes related to oxidative stress, proteotoxicity, inflammation, and proliferative signaling occur along with those related to DNA repair, cell cycle G2/M checkpoint control, and induction of apoptosis. At higher concentrations (10-100 [mu]M), changes in apoptotic genes dominate...

Comparison of the Salmonella/microsome microsuspension assay with the new microplate fluctuation protocol for testing the mutagenicity of environmental samples

Environmental and Molecular Mutagenesis — Sun, 31 May 2009 04:00:00 +0100

The objective of this study was to compare the responses of the Salmonella/microsome microsuspension assay with the new microplate fluctuation protocol (MPF) for the evaluation of the mutagenic activity of environmental samples. Organic extracts of total particulate atmospheric air samples, surface waters, and effluents were tested in dose-response experiments. The assays were performed with strain TA98 in the absence and presence of S9 mix. Both protocols produced similar results, despite the fact that the maximum score of the MPF is limited to 48 wells, whereas in the regular plate assay it is possible to count up to 1,500 colonies using an automatic counter. Similar sensitivities based on the lowest dose that resulted in a positive response were obtained for both assays. The MPF procedu...

Human cytochrome P450 2E1 and sulfotransferase 1A1 coexpressed in Chinese hamster V79 cells enhance spontaneous mutagenesis

Environmental and Molecular Mutagenesis — Fri, 29 May 2009 04:00:00 +0100

Genetic engineering of target cells for investigating the genotoxicity associated with specific xenobiotic-metabolizing enzymes is useful for elucidating metabolic activation and inactivation processes. We constructed a V79-derived cell line expressing both human cytochrome P450 (CYP) 2E1 and human sulfotransferase (SULT) 1A1. We previously reported that this cell line (V79-hCYP2E1-hSULT1A1) efficiently activates various important pro-genotoxicants. Here we present data on the expression level and stability of the heterologous enzymes, measured by immunoblotting, enzyme activities, and mutagenic responses to CYP2E1- and SULT1A1-dependent promutagens. Unexpectedly, these cells demonstrated greatly elevated spontaneous gene mutation frequencies (determined at the Hprt locus), and elevated fr...

Effect of O6-alkylguanine-DNA alkyltransferase on genotoxicity of epihalohydrins

Environmental and Molecular Mutagenesis — Thu, 28 May 2009 04:00:00 +0100

The effect of O6-alkylguanine-DNA alkyltransferase (AGT) on the toxicity and mutagenicity of epihalohydrins was studied. AGT is a DNA repair protein that protects cells from agents that produce genotoxic O6-alkylguanine lesions by transferring the alkyl group to an internal cysteine residue (Cys145 in human AGT) in a single-step. This cysteine acceptor site is highly reactive and epihalohydrins reacted readily with AGT at this site with a halide order of reactivity of Br > Cl > F. AGT expression in bacterial cells caused a very large increase in the mutagenicity and cytotoxicity of epibromohydrin. The mutations were almost all G:C to A:T transitions. Epichlorohydrin also augmented AGT-mediated mutagenesis but to a lesser extent than epibromohydrin. In vitro experiments showed that AGT was ...

Arsenate and dimethylarsinic acid in drinking water did not affect DNA damage repair in urinary bladder transitional cells or micronuclei in bone marrow

Environmental and Molecular Mutagenesis — Tue, 26 May 2009 04:00:00 +0100

Arsenic is a human skin, lung, and urinary bladder carcinogen, and may act as a cocarcinogen in the skin and urinary bladder. Possible modes of action of arsenic carcinogenesis/cocarcinogenesis include oxidative stress induction and inhibition of DNA damage repair. We investigated the effects of arsenic in drinking water on DNA damage repair in urinary bladder transitional cells and on micronucleus formation in bone marrow. F344 rats were given 100 ppm arsenate [As(V)] or dimethylarsinic acid [DMA(V)] in drinking water for 1 week. The in vivo repair of cyclophosphamide (CP)-induced DNA damage resulting from a single oral gavage of CP, and the in vitro repair of hydrogen peroxide (H2O2)- or formaldehyde-induced DNA damage, resulting from adding H2O2 or formaldehyde into cell medium, were me...

Suppression of the mouse double minute 4 gene causes changes in cell cycle control in a human mesothelial cell line responsive to ultraviolet radiation exposure

Environmental and Molecular Mutagenesis — Tue, 26 May 2009 04:00:00 +0100

The TP53 tumor suppressor gene is the most frequently inactivated gene in human cancer identified to date. However, TP53 mutations are rare in human mesotheliomas, as well as in many other types of cancer, suggesting that aberrant TP53 function may be due to alterations in its regulatory pathways. Mouse double minute 4 (MDM4) has been shown to be a key regulator of TP53 activity, both independently as well as in concert with its structural homolog, Mouse Double Minute 2 (MDM2). The purpose of this study was to characterize the effects of MDM4 suppression on TP53 and other proteins involved in cell cycle control before and after ultraviolet (UV) exposure in MeT5a cells, a nonmalignant human mesothelial line. Short hairpin RNA (shRNA) was used to investigate the impact of MDM4 on TP53 functi...

Radioprotective effects of Daflon against genotoxicity induced by gamma irradiation in human cultured lymphocytes

Environmental and Molecular Mutagenesis — Tue, 26 May 2009 04:00:00 +0100

The ability of Daflon to protect against genotoxicity induced by gamma irradiation has been investigated in vivo and in vitro in cultured lymphocytes from healthy human volunteers. Peripheral human blood samples were collected predose (10 min before) and 1, 2, and 3 hr after a single oral ingestion of 1000 mg of Daflon. At each time point, whole blood was exposed in vitro to 150 cGy of cobalt-60 gamma rays, and then the lymphocytes were cultured with mitogenic stimulation to determine the micronuclei in cytokinesis-blocked binucleated cells. For each volunteer, the results showed a significant increase in the incidence of micronuclei after exposure to gamma irradiation as compared to control unexposed samples. As early as 1 hr after Daflon administration, a significant decrease in the inci...

Folate deficiency in human peripheral blood lymphocytes induces chromosome 8 aneuploidy but this effect is not modified by riboflavin

Environmental and Molecular Mutagenesis — Tue, 26 May 2009 04:00:00 +0100

Chromosome 8 aneuploidy is a common event in certain cancers but whether folate (F) deficiency induces chromosome 8 aneuploidy is not known. Furthermore the impact of riboflavin (R) deficiency, which may alter activity of a key enzyme in folate metabolism, on these events is unknown. Therefore, the aim of our research was to test the following hypotheses: (a) F deficiency induces chromosome 8 aneuploidy; (b) chromosome 8 aneuploidy is affected by F deficiency to a similar degree as chromosome 17 and (c) R deficiency aggravates the risk of aneuploidy caused by F deficiency. These hypotheses were tested in long-term cultures of lymphocytes from twenty female healthy volunteers (aged 30-48 years). Lymphocytes were cultured in each of the four possible combinations of low (L) and high (H) F (L...

Evaluation of a suitable DNA damage biomarker for human biomonitoring of exposed workers

Environmental and Molecular Mutagenesis — Sat, 16 May 2009 04:00:00 +0100

The objective of this study was to identify a sensitive and noninvasive biomarker of early genotoxic effects, for health risk assessment of workers exposed to mixtures of low doses of xenobiotics. We studied 30 workers exposed to antineoplastic drugs, 57 workers exposed to different mixtures of polycyclic aromatic hydrocarbons (PAHs) (41 airport workers and 16 paving workers) and 76 controls. Comet and micronucleus (MN) tests were performed on lymphocytes and exfoliated buccal cells. The MN assay on lymphocytes did not show significant differences between exposed and controls, while the MN assay on exfoliated buccal cells showed higher values in workers exposed to antineoplastics as compared with controls (0.85 vs. 0.48, P = 0.042). The comet assay on lymphocytes showed a higher comet perc...

Mutagenic potency of MMS-induced 1meA/3meC lesions in E. coli

Environmental and Molecular Mutagenesis — Fri, 15 May 2009 04:00:00 +0100

In this report, special attention is focused on the mutagenic properties of 1meA/3meC which, by the activity of AlkB-dioxygenase, are quickly and efficiently converted to natural A/C bases in the DNA of E. coli alkB+ strains, preventing 1meA/3meC-induced mutations. We have found that in the absence of AlkB-mediated repair, MMS treatment results in an increased frequency of four types of base substitutions: GC[rarr]CG, GC[rarr]TA, AT[rarr]CG, and AT[rarr]TA, whereas overproduction of PolV in CC101-106 alkB-/pRW134 strains leads to a markedly elevated level of GC[rarr]TA, GC[rarr]CG, and AT[rarr]TA transversions. It has been observed that in the case of AB1157 alkB- strains, the MMS-induced and 1meA/3meC-dependent argE3[rarr]Arg+ reversion occurs efficiently, whereas lacZ-[rarr] Lac+ reversi...

The role of catechols and free radicals in benzene toxicity: An oxidative DNA damage pathway

Environmental and Molecular Mutagenesis — Fri, 15 May 2009 04:00:00 +0100

Benzene is a widespread volatile compound and an environmental contaminant. Since it causes important toxic effects in workers exposed to low levels, long-term exposure to this compound has been extensively studied. Leukemia, blood disorders, bone marrow depression, and some types of cancer are directly related to benzene-initiated toxicity. Bioactivation of benzene can lead to the formation of hazardous metabolites such as phenol, hydroquinone, and catechol. Catechol forms semiquinones and reactive quinones that are presumed to play an important role in the generation of reactive oxygen species (ROS). ROS formation can directly induce single and double strand breaks in the DNA, oxidized nucleotides, and hyper-recombination, and consequently produces deleterious genetic changes. In this re...

The functional significance of centrosomes in mammalian meiosis, fertilization, development, nuclear transfer, and stem cell differentiation

Environmental and Molecular Mutagenesis — Wed, 29 Apr 2009 04:00:00 +0100

Centrosomes had been discovered in germ cells and germ cells continue to provide excellent but also challenging material in which to study complex centrosomal dynamics. The present review highlights the importance of centrosomes for meiotic spindle integrity and the susceptibility of meiotic spindle centrosomes to aging and drugs or toxic agents which may be associated with female infertility, aneuploidy, and developmental abnormalities. We discuss cell and molecular aspects of centrosomes during fertilization, a critical stage in which centrosomes play crucial roles in precisely organizing the sperm aster that allows apposition of male and female genomes followed by formation of the zygote aster that is important for the formation of the bipolar spindle apparatus during cell division. Dev...

The role of paraoxonase polymorphisms in the induction of micronucleus in paraoxon-treated human lymphocytes

Environmental and Molecular Mutagenesis — Tue, 28 Apr 2009 04:00:00 +0100

Human paraoxonase-1 (PON1) is a high-density lipoprotein-associated enzyme that has a role in the detoxification of organophosphorus compounds by hydrolyzing the bioactive oxons. PON1 polymorphims are responsible, at least in part, for the variation in the catalytic activity and expression of the enzyme and have been associated with susceptibility to organophosphorus pesticide toxicity, mainly neurotoxicity. The aim of this study was to determine whether paraoxon induced micronuclei and to examine the role of PON1 polymorphism in paraoxon's genotoxic potential. First, dose finding cytogenetic experiments were performed on lymphocyte cultures from three donors and a range of paraoxon concentration (1-25 [mu]M) were tested. In a second set of experiments, 5 [mu]M paraoxon was added to blood ...

Dependence of DNA double strand break repair pathways on cell cycle phase in human lymphoblastoid cells

Environmental and Molecular Mutagenesis — Tue, 28 Apr 2009 04:00:00 +0100

DNA double-strand breaks (DSBs) are usually repaired by nonhomologous end-joining (NHEJ) or homologous recombination (HR). NHEJ is thought to be the predominant pathway operating in mammalian cells functioning in all phases of the cell cycle, while HR works in the late-S and G2 phases. However, relative contribution, competition, and dependence on cell cycle phases are not fully understood. We previously developed a system to trace the fate of DSBs in the human genome by introducing the homing endonuclease I-SceI site into the thymidine kinase (TK) gene of human lymphoblastoid TK6 cells. Here, we use this system to investigate the relative contribution of HR and NHEJ for repairing I-SceI-induced DSBs under various conditions. We used a novel transfection system, AmaxaTM nucleofector, which...

Effect of annatto on micronuclei induction by direct and indirect mutagens in HepG2 cells

Environmental and Molecular Mutagenesis — Tue, 28 Apr 2009 04:00:00 +0100

In this study, we evaluated the ability of AN to protect human hepatoma cells (HepG2) from micronucleus (MN) induction against three different mutagens: benzo(a)pyrene (B(a)P), doxorubicin (DXR), and methyl methanesulfonate (MMS). In an attempt to clarify the possible mechanism of antimutagenicity of AN, three protocols of treatment were applied (pretreatment; simultaneous treatment, and post-treatment with AN following treatment with the mutagens). Also, cells exposed only to AN were assayed for cytotoxicity and mutagenicity. A dosage up to 10 [mu]g/ml of AN was devoid of mutagenic activity. Protective effects were seen on micronuclei induced by B(a)P and DXR using pre and simultaneous treatment, but AN had no significant effect on MN induction by MMS in any of the protocols. Our results ...

Evaluation of genome damage and its relation to oxidative stress induced by glyphosate in human lymphocytes in vitro

Environmental and Molecular Mutagenesis — Tue, 28 Apr 2009 04:00:00 +0100

In the present study we evaluated the genotoxic and oxidative potential of glyphosate on human lymphocytes at concentrations likely to be encountered in residential and occupational exposure. Testing was done with and without metabolic activation (S9). Ferric-reducing ability of plasma (FRAP), thiobarbituric acid reactive substances (TBARS) and the hOGG1 modified comet assay were used to measure glyphosate's oxidative potential and its impact on DNA. Genotoxicity was evaluated by alkaline comet and analysis of micronuclei and other nuclear instabilities applying centromere probes. The alkaline comet assay showed significantly increased tail length (20.39 [mu]m) and intensity (2.19%) for 580 [mu]g/ml, and increased tail intensity (1.88%) at 92.8 [mu]g/ml, compared to control values of 18.15...

Increased consumption of wheat biofortified with selenium does not modify biomarkers of cancer risk, oxidative stress, or immune function in healthy Australian males

Environmental and Molecular Mutagenesis — Sat, 18 Apr 2009 04:00:00 +0100

This study aimed to investigate whether improving Se status, by increased dietary intake of Se-biofortified wheat, affects biomarkers of cancer risk, cardiovascular disease risk, oxidative stress, and immune function in healthy South Australian men. A 24-week placebo-controlled double-blind intervention was performed in healthy older men (n = 62), with increased dose of Se intake every 8 weeks. Wheat was provided as 1, 2, and 3 puffed wheat biscuits, during weeks 1-8, 9-16, and 17-24, respectively. Blood was collected to measure a wide range of disease risk biomarkers. Consumption of Se-biofortified wheat was found to increase plasma Se concentration from a baseline level of 122 to 192 [mu]g/L following intake of three biscuits/day, which provided 267 [mu]g Se. Platelet glutathione peroxid...

Antigenotoxic effects of Citrus aurentium L. fruit peel oil on mutagenicity of two alkylating agents and two metals in the Drosophila wing spot test

Environmental and Molecular Mutagenesis — Mon, 06 Apr 2009 04:00:00 +0100

Antigenotoxic effects of Citrus aurentium L. (Rutaceae) fruit peel oil (CPO) in combination with mutagenic metals and alkylating agents were studied using the wing spot test of D. melanogaster. The four reference mutagens, potassium dichromate (K2Cr2O7), cobalt chloride (CoCl2), ethylmethanesulfonate (EMS), and N-ethyl-N-nitrosourea (ENU) were clearly genotoxic. CPO alone at doses from 0.1 to 0.5% in Tween 80 was not mutagenic and did not enhance the mutagenic effect of the reference mutagens. However, antigenotoxic effects of CPO were clearly demonstrated in chronic cotreatments with mutagens and oil, by a significant decrease in wing spots induced by all four mutagens. The D. melanogaster wing spot test was found to be a suitable assay for detecting antigenotoxic effects in vivo. Environ...

WR1065 mitigates AZT-ddI-induced mutagenesis and inhibits viral replication

Environmental and Molecular Mutagenesis — Mon, 30 Mar 2009 04:00:00 +0100

The success of nucleoside reverse transcriptase inhibitors (NRTIs) in treating HIV-1 infection and reducing mother-to-child transmission of the virus during pregnancy is accompanied by evidence that NRTIs cause long-term health risks for cancer and mitochondrial disease. Thus, agents that mitigate toxicities of the current combination drug therapies are needed. Previous work had shown that the NRTI-drug pair zidovudine (AZT)-didanosine (ddI) was highly cytotoxic and mutagenic; thus, we conducted preliminary studies to investigate the ability of the active moiety of amifostine, WR1065, to protect against the deleterious effects of this NRTI-drug pair. In TK6 cells exposed to 100 [mu]M AZT-ddI (equimolar) for 3 days with or without 150 [mu]M WR1065, WR1065 enhanced long-term cell survival an...

An update on the genotoxicity and carcinogenicity of marketed pharmaceuticals with reference to in silico predictivity

Environmental and Molecular Mutagenesis — Mon, 30 Mar 2009 04:00:00 +0100

Information from the 1999 through 2008 Physicians' Desk Reference (PDR) was used to evaluate the genotoxicity of marketed drugs. Where available, data regarding the rodent carcinogenicity results were included (PDR and Gold potency database). In addition, computational predictivity of genotoxicity (DEREK, MC4PC) is included and expanded upon from two previous reviews. The present paper contains genotoxicity data on 545 marketed drugs. Excluded from analysis were most cytotoxic anti-cancer and antiviral drugs, nucleosides (all with known mechanistic genotoxicity), steroids with class-specific genotoxicity and biologicals or peptide-based drugs. Per assay type, the percentage of positive drugs was: Bacterial mutagenesis assay: 38/525 (7.1%), in vitro chromosome aberrations: 88/380 (26.1%); m...

Cytochrome P450 2E1 and head and neck cancer: Interaction with genetic and environmental risk factors

Environmental and Molecular Mutagenesis — Mon, 30 Mar 2009 04:00:00 +0100

The present case-control study investigates the association of polymorphisms in cytochrome P450 2E1 (CYP2E1), involved in the metabolism of tobacco carcinogens and alcohol, with Head and Neck Squamous Cell Carcinoma (HNSCC). In addition, the interaction of CYP2E1 (CYP2E1*5B and CYP2E1*6) with other genetic factors (null genotype of glutathione-S-Transferase M1, GSTM1, X-Ray Repair Cross Complementing Group I, XRCC1 (Arg194Trp), and environmental risk factors such as alcohol and tobacco in modifying HNSCC risk were investigated. Genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay in a total of 350 male cases of HNSCC and an equal number of healthy male controls. Statistical analysis showed a significant increase in HNSCC risk ...

Impact of inorganic nutrients on maintenance of genomic stability

Environmental and Molecular Mutagenesis — Sun, 29 Mar 2009 03:16:53 +0100

This article focuses on roles of inorganic trace nutrients, including selenium, copper, zinc, and iron, in the redox regulation of genome stability and how they relate to the pathologies of genomic instability syndromes and cancer. Environ. Mol. Mutagen. 2009. © 2009 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Centrosome overduplication, chromosomal instability, and human papillomavirus oncoproteins

Environmental and Molecular Mutagenesis — Thu, 26 Mar 2009 04:00:00 +0100

Centrosome aberrations are a frequent finding in human tumors. However, very little is known about the molecular mechanisms leading to disruption of centrosome duplication control and the functional consequences of aberrant centrosome numbers. The high-risk human papillomavirus Type 16 (HPV-16) E6 and E7 oncoproteins are overexpressed in HPV-associated malignancies of the anogenital tract and have been instrumental in delineating different pathways of centrosome amplification. Whereas the E6 oncoprotein was found to provoke centrosome accumulation, the HPV-16 E7 oncoprotein triggers a genuine disruption of the centrosome duplication cycle. Importantly, the E7 oncoprotein can rapidly cause centrosome overduplication through a pathway that involves the concurrent formation of multiple daught...

Genotoxicity analysis of two hydroxyfuranones, byproducts of water disinfection, in human cells treated in vitro

Environmental and Molecular Mutagenesis — Thu, 26 Mar 2009 04:00:00 +0100

In general, water for human consumption is chemically disinfected, usually by adding chlorine. As well as producing safe drinking water however, the chlorine treatment, also results in a number of disinfection byproducts (DBPs). One important class of these DBPs is made up of hydroxyfuranones (HFs). In this article, we report the results of a recent investigation to assess the genotoxicity of two HFs, namely mucobromic acid (MBA) and mucochloric acid (MCA), in cultured human cells. The comet assay is used to measure the induction of primary DNA damage and to determine the DNA repair kinetics and the ability of the tested compounds to cause oxidative damage. In addition, the micronucleus (MN) assay is applied to evaluate chromosome damage. The results of the comet assay reveal that both HFs...

Viral transformation and aneuploidy

Environmental and Molecular Mutagenesis — Thu, 26 Mar 2009 04:00:00 +0100

Human tumor viruses are associated with a variety of human malignancies, and it is estimated that 15% of all human cancers have a viral etiology. An abnormality in chromosomal ploidy or aneuploidy is a hallmark of cancers. In normal cells, euploidy is governed by several factors including an intact spindle assembly checkpoint, accurate centrosome duplication, and proper cytokinesis. Viral oncoproteins are suggested to perturb the cellular machineries for chromosomal segregation creating aneuploidy which can lead to the malignant transformation of infected cells. Here, we review in brief some of the mechanisms used by viruses that can cause cellular aneuploidy. Environ. Mol. Mutagen. 2009. © 2009 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Lifetime history of alcohol consumption and K-ras mutations in pancreatic ductal adenocarcinoma

Environmental and Molecular Mutagenesis — Thu, 26 Mar 2009 04:00:00 +0100

In pancreatic ductal adenocarcinoma (PDA), evidence on the etiopathogenic role of alcohol consumption in the occurrence of K-ras mutations is scant, and the role of alcohol in pancreatic carcinogenesis is not well established. We analyzed the relation between lifetime consumption of alcohol and mutations in codon 12 of the K-ras oncogene in patients with PDA.Incident cases of PDA were prospectively identified and interviewed face-to-face during hospital admission about lifetime alcohol consumption and other lifestyle factors. Logistic regression was used to compare PDA cases (N = 107) with mutated and wild-type K-ras tumors (case-case study).Mutated cases were moderate or heavy drinkers more frequently than wild-type cases: the odds ratio adjusted by age, sex, smoking, and history of pancr...

Comparative mutagenic effects of structurally similar flavonoids quercetin and taxifolin on tester strains Salmonella typhimurium TA102 and Escherichia coli WP-2 uvrA

Environmental and Molecular Mutagenesis — Thu, 26 Mar 2009 04:00:00 +0100

Quercetin (QT) and Taxifolin (TF) are structurally similar plant polyphenols. Both have been reported to have therapeutic potential as anti-cancer drugs and antioxidants. Mutagenic effects of QT and TF were evaluated using Salmonella typhimurium TA102 and Escherichia coli WP-2 uvrA tester strains. Either in the presence or absence of S9 mix, QT was mutagenic to TA102 and WP2 uvrA. However, the mutagenicity of QT was significantly enhanced in the presence of S9 mix. Likewise, in the presence of Iron (Fe2+) and NADPH generating system (NGS) and absence of S9 mix, QT induced significantly high mutations in both TA102 and WP-2 uvrA. Mutagenicity of QT decreased in both strains in the presence of Iron (Fe2+) or NGS alone. TF was not mutagenic in the presence or absence of S9 mix in both TA102 a...

Exposure of HepG2 cells to low levels of PAH-containing extracts from contaminated soils results in unpredictable genotoxic stress responses

Environmental and Molecular Mutagenesis — Sun, 22 Mar 2009 04:00:00 +0100

Contaminated soil is a serious environmental problem, constituting a risk to humans and the environment. Polycyclic aromatic hydrocarbons (PAHs) are often present at contaminated sites. However, risk levels are difficult to estimate because of the complexity of contaminants present. Here, we compare cellular effects of extracts from contaminated soils collected at six industrial settings in Sweden. Chemical analysis showed that all soils contained complex mixtures of PAHs and oxy-PAHs. Western blotting and immunocytochemistry were used to investigate DNA damage signaling in HepG2 cells exposed to extracts from these soils. The effects on phosphorylated Mdm2, p53, Erk, H2AX, 53BP1, and Chk2, cell cycle regulating proteins (cyclin D1 and p21), and cell proliferation were compared. We found t...

Centriole separation in DNA damage-induced centrosome amplification

Environmental and Molecular Mutagenesis — Fri, 13 Mar 2009 04:00:00 +0100

Altered centrosome numbers are seen in tumor cells in response to DNA damaging treatments and are hypothesised to contribute to cancer development. The mechanism by which the centrosome and chromosome cycles become disconnected after DNA damage is not yet clear. Here, we show that centrosome amplification occurs after ionising radiation (IR) in chicken DT40 cells that lack DNA-PK, Ku70, H2AX, Xpa, and Scc1, demonstrating that these activities are not required for centrosome amplification. We show that inhibition of topoisomerase II induces Chk1-dependent centrosome amplification, a similar response to that seen after IR. In the immortalised, nontransformed hTERT-RPE1 line, we observed centriole splitting, followed by dose-dependent centrosome amplification, after IR. We found that IR resul...

Mutagenicity of an aged gasworks soil during bioslurry treatment

Environmental and Molecular Mutagenesis — Mon, 09 Mar 2009 04:00:00 +0100

This study investigated changes in the mutagenic activity of organic fractions from soil contaminated with polycyclic aromatic hydrocarbons (PAHs) during pilot-scale bioslurry remediation. Slurry samples were previously analyzed for changes in PAH and polycyclic aromatic compound content, and this study examined the correspondence between the chemical and toxicological metrics. Nonpolar neutral and semipolar aromatic fractions of samples obtained on days 0, 3, 7, 24, and 29 of treatment were assayed for mutagenicity using the Salmonella mutation assay. Most samples elicited a significant positive response on Salmonella strains TA98, YG1041, and YG1042 with and without S9 metabolic activation; however, TA100 failed to detect mutagenicity in any sample. Changes in the mutagenic activity of t...

The BRCA1-dependent ubiquitin ligase, [gamma]-tubulin, and centrosomes

Environmental and Molecular Mutagenesis — Mon, 09 Mar 2009 04:00:00 +0100

Mutation of the breast and ovarian cancer specific tumor suppressor, BRCA1, results in supernumerary and hyperactive centrosomes, which in turn likely contribute to the aneuploidy evident in breast cancer cells. The BRCA1-dependent ubiquitin ligase activity is required for the regulation of centrosome function, and among its substrates is [gamma]-tubulin. Data suggest that during S and G2 phases of the cell cycle, the normal function of BRCA1 directs the ubiquitination of [gamma]-tubulin, resulting in inhibition of centrosome microtubule nucleation function and blocking of centrosome reduplication. Loss of BRCA1 activity, as occurs in breast cancer cells, would result in centrosomes that are unrestrained, leading to the hyperactive and over-duplicated centrosomes often observed in breast c...

Mps1 as a link between centrosomes and genomic instability

Environmental and Molecular Mutagenesis — Mon, 09 Mar 2009 04:00:00 +0100

Centrosomes are microtubule-organizing centers that must be precisely duplicated before mitosis. Centrosomes regulate mitotic spindle assembly, and the presence of excess centrosomes leads to the production of aberrant mitotic spindles which generate chromosome segregation errors. Many human tumors possess excess centrosomes that lead to the production of abnormal spindles in situ. In some tumors, these extra centrosomes appear before aneuploidy, suggesting that defects in centrosome duplication might promote genomic instability and tumorigenesis. The Mps1 protein kinase is required for centrosome duplication, and preventing the proteasome-dependent degradation of Mps1 at centrosomes increases its local concentration and causes the production of excess centrosomes during a prolonged S-phas...

Biological properties of garlic and garlic-derived organosulfur compounds

Environmental and Molecular Mutagenesis — Sat, 28 Feb 2009 05:00:00 +0100

Medicinal properties of garlic (Allium sativum) have been widely known and used since ancient times till the present. Garlic enhances immune functions and has antibacterial, antifungal and antivirus activities. It is known to prevent platelet aggregation, and to have hypotensive and cholesterol- and triglyceride-lowering properties, although the latter features have been questioned. This review is focused on anticancer efficacy of Allium sativum, and attempts to explain the mechanisms of this action. Medicinal properties of garlic rely upon organosulfur compounds mostly derived from alliin. Organosulfur compounds originating from garlic inhibit carcinogen activation, boost phase 2 detoxifying processes, cause cell cycle arrest mostly in G2/M phase, stimulate the mitochondrial apoptotic pat...

Three structurally homologous isothiocyanates exert "Janus" characteristics in human HepG2 cells

Environmental and Molecular Mutagenesis — Fri, 27 Feb 2009 05:00:00 +0100

In this study, we used the single cell gel electrophoresis (SCGE) assay and the micronucleus (MN) test to investigate the DNA damaging effects and the antigenotoxic potencies of three structurally related ITCs in human HepG2 cells. The results show that all three ITCs possess the characteristic of a "Janus" compound, i.e., they exert both significant genotoxicity and antigenotoxicity, depending on the concentrations used in the test systems applied. Regression line analysis of the results derived by SCGE analysis showed genotoxic potency of the ITCs in the following order: 3-methylthiopropyl ITC (MTPITC) > 4-methylthiobutyl ITC (MTBITC) > 5-methylthiopentyl ITC (MTPeITC); however, this order in genotoxic potency was not confirmed by MN analysis. Additionally, the MN test showed significant...

Sulphur-containing compounds in food plants: Kinetics, biological activity, and mechanisms of action

Environmental and Molecular Mutagenesis — Fri, 27 Feb 2009 05:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Particulate hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale (Eubalaena glacialis) lung and skin fibroblasts

Environmental and Molecular Mutagenesis — Fri, 20 Feb 2009 05:00:00 +0100

Hexavalent chromium compounds are present in the atmosphere and oceans and are established mutagens and carcinogens in human and terrestrial mammals. However, the adverse effects of these toxicants in marine mammals are uncertain. Previously, we reported that North Atlantic right whales, one of the most endangered great whales, have tissue chromium levels that are high, levels that may pose a risk to the whale's health. Furthermore, the study suggested that inhalation may be an important exposure route. Exposure to chromium through inhalation is mainly because of particulate compounds. However, the toxicity of particulate chromium compounds in marine mammal cells is unknown. Accordingly, in this study, we tested the cytotoxic and genotoxic effects of particulate hexavalent chromium in prim...

Cloning and characterization of DNA polymerase [eta] from Trypanosoma cruzi: Roles for translesion bypass of oxidative damage

Environmental and Molecular Mutagenesis — Thu, 19 Feb 2009 05:00:00 +0100

We report the cloning and characterization of the DNA polymerase [eta] gene from Trypanosoma cruzi (TcPol[eta]), the causative agent of Chagas disease. This protein, which can bypass cyclobutane pyrimidine dimers, contains motifs that are conserved between Y family polymerases. In vitro assays showed that the recombinant protein is capable of synthesizing DNA in undamaged primer-templates. Intriguingly, T. cruzi overexpressing TcPol[eta] does not increase its resistance to UV-light (with or without caffeine) or cisplatin, despite the ability of the protein to enhance UV resistance in a RAD30 mutant of Saccharomyces cerevisiae. Parasites overexpressing TcPol[eta] are also unable to restore growth after treatment with zeocin or gamma irradiation. T. cruzi overexpressing TcPol[eta] are more r...

Use of centromeric and telomeric DNA probes in in situ hybridization for differentiation of micronuclei induced by lomefloxacin

Environmental and Molecular Mutagenesis — Thu, 19 Feb 2009 05:00:00 +0100

Classification of micronuclei induced by lomefloxacin, a difluorinated quinolone bactericidal agent, in mouse bone marrow was performed by fluorescence in situ hybridization using DNA probes for the centromere repeated minor satellite DNA and the telomeric hexamer repeat (5[prime]-TTAGGG-3[prime]). Colchicine and mitomycin C were used as a positive control aneugen and clastogen, respectively, and these compounds produced the expected responses. Single doses of 40, 80, 160, or 320 mg/kg lomefloxacin were given via oral intubations and bone marrow was sampled at 24 and 48 hr after treatment. The micronuclei showed significant increases in both sampling times after doses of 320 mg/kg. A statistically significant increase of micronuclei frequency was also detected for 160 mg/kg lomefloxacin at...

Evaluation of the genotoxicity of Fusarium mycotoxin moniliformin in human peripheral blood lymphocytes

Environmental and Molecular Mutagenesis — Thu, 19 Feb 2009 05:00:00 +0100

Mycotoxins are fungal secondary metabolites that can be found in contaminated food and feed. There is some evidence to suggest that certain mycotoxins may be mutagenic. Here, we investigate the genotoxicity of the mycotoxin moniliformin (MON) (3-hydroxycyclobut-3-ene-1,2-dione) in human peripheral blood lymphocytes using chromosomal aberration (CA), sister-chromatid exchange (SCE), and micronucleus (MN) analysis. Lymphocyte cultures were treated for 48 h with six different concentrations of MON between 2.5 and 25 [mu]M. CA, SCE, and MN frequencies were significantly increased in a dose-dependent manner compared with the negative control. The mitotic, replication, and cytokinesis-block proliferation indices were not affected by treatment with MON. The results provide evidence to demonstrate...

Analysis of cellular response to isocyanate using N-succinimidyl N-methylcarbamate exposure in cultured mammalian cells

Environmental and Molecular Mutagenesis — Sun, 08 Feb 2009 05:00:00 +0100

Isocyanates (R[bond]N[double bond]C[double bond]O), one of the highly reactive industrial intermediates, possess the capability to modulate the bio-molecules by forming toxic metabolites and adducts which may cause adverse health effects. Some of their toxic degradations have previously been unknown and overlooked; of which, molecular repercussions underlying their genetic hazards upon occupational/accidental exposures still remain as an intricate issue and are hitherto unknown. To assess the genotoxic potential of methyl isocyanate in cultured mammalian cells after in vitro exposure, we performed a study in three different normal cell lines MM55.K (mouse kidney epithelial), B/CMBA.Ov (mouse ovarian epithelial), and NIH/3T3 (primary mouse embryonic fibroblast). Cellular DNA damage response...

Modulation of histone deacetylase activity by dietary isothiocyanates and allyl sulfides: Studies with sulforaphane and garlic organosulfur compounds

Environmental and Molecular Mutagenesis — Thu, 05 Feb 2009 05:00:00 +0100

Histone deacetylase (HDAC) inhibitors reactivate epigenetically-silenced genes in cancer cells, triggering cell cycle arrest and apoptosis. Recent evidence suggests that dietary constituents can act as HDAC inhibitors, such as the isothiocyanates found in cruciferous vegetables and the allyl compounds present in garlic. Broccoli sprouts are a rich source of sulforaphane (SFN), an isothiocyanate that is metabolized via the mercapturic acid pathway and inhibits HDAC activity in human colon, prostate, and breast cancer cells. In mouse preclinical models, SFN inhibited HDAC activity and induced histone hyperacetylation coincident with tumor suppression. Inhibition of HDAC activity also was observed in circulating peripheral blood mononuclear cells obtained from people who consumed a single ser...

Vascular endothelial growth factor gene polymorphisms are associated with the risk of developing adenomyosis

Environmental and Molecular Mutagenesis — Thu, 05 Feb 2009 05:00:00 +0100

Vascular endothelial growth factor (VEGF), a major mediator of angiogenesis and vascular permeability, may play a key role in the development of adenomyosis. The aim of this study was to investigate whether these four VEGF polymorphisms (-2578C/A, -1154G/A, -460C/T, and +936C/T) were associated with the risk of adenomyosis development. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay in 174 adenomyosis patients and 199 frequency-matched control women. There were significant differences between patients and control group in allele frequencies and genotype distributions of the -2578C/A polymorphisms (P = 0.010 and 0.044, respectively). Compared with the C/C genotype, the A/A + C/A genotype could significantly modify the risk of ...

GST polymorphism and excretion of heterocyclic aromatic amine and isothiocyanate metabolites after Brassica consumption

Environmental and Molecular Mutagenesis — Thu, 05 Feb 2009 05:00:00 +0100

Brassica vegetable intake has been associated with decreased risk and well-done meat intake has been associated with increased risk of cancers at multiple organ sites in epidemiologic studies. Experimental studies suggest a role of modulation of phase I and phase II metabolizing enzymes as one mechanism for these associations. Heterocyclic aromatic amines (HAAs) are carcinogens formed in meat that has been cooked to well-done and at high temperatures. Phase I metabolizing enzymes catalyze the activation of HAAs, and phase II metabolizing enzymes serve to detoxify the active carcinogens. The glutathione S-transferases (GSTs) are a family of phase II metabolizing enzymes that are induced by, and act to conjugate, isothiocyanates (ITCs), phytochemicals found in Brassica vegetables. This revie...

Requirement of the Saccharomyces cerevisiae APN1 gene for the repair of mitochondrial DNA alkylation damage

Environmental and Molecular Mutagenesis — Thu, 05 Feb 2009 05:00:00 +0100

The Saccharomyces cerevisiae APN1 gene that participates in base excision repair has been localized both in the nucleus and the mitochondria. APN1 deficient cells (apn1[Delta]) show increased mutation frequencies in mitochondrial DNA (mtDNA) suggesting that APN1 is also important for mtDNA stability. To understand APN1-dependent mtDNA repair processes we studied the formation and repair of mtDNA lesions in cells exposed to methyl methanesulfonate (MMS). We show that MMS induces mtDNA damage in a dose-dependent fashion and that deletion of the APN1 gene enhances the susceptibility of mtDNA to MMS. Repair kinetic experiments demonstrate that in wild-type cells (WT) it takes 4 hr to repair the damage induced by 0.1% MMS, whereas in the apn1[Delta] strain there is a lag in mtDNA repair that re...

Areca nut-induced micronuclei and cytokinesis failure in Chinese hamster ovary cells is related to reactive oxygen species production and actin filament deregulation

Environmental and Molecular Mutagenesis — Thu, 05 Feb 2009 05:00:00 +0100

In this study, we found that AN extract (ANE) inhibited the growth of Chinese hamster ovary cells (CHO-K1) in a dose- and time-dependent manner. Intracellular reactive oxygen species (ROS) levels and micronuclei (MN) frequency were significantly increased following ANE treatment in CHO-K1 cells. Addition of catalase markedly inhibited ANE-induced MN formation, indicating that ANE-induced genotoxicity was correlated with intracellular H2O2. Incubation of CHO-K1 cells with ANE (400-800 [mu]g/ml) for 24 hr caused G2/M arrest, and prolonged exposure to ANE (800 [mu]g/ml) significantly induced cell death. Surprisingly, ANE itself caused cytokinesis failure and subsequent increase in binucleated cell formation. Coexposure to catalase (2,000 U/ml) and ANE (800 [mu]g/ml) reduced the generation of ...

Apoptosis induction in human lung adenocarcinoma cells by oil-soluble allyl sulfides: Triggers, pathways, and modulators

Environmental and Molecular Mutagenesis — Thu, 05 Feb 2009 05:00:00 +0100

In this study, we report that OASs DADS and DATS induce significant apoptosis in human lung adenocarcinoma A549 cells, whereas DAS does not. Differential modulation of reactive oxygen intermediates (ROI) and mitochondria membrane potential (MMP) may account for the apoptotic effects of DADS and DATS. The underlying molecular mechanisms of apoptosis induction by both compounds include activation of C-Jun N-terminal kinase (JNK), up-regulation of p53, and down-regulation of bcl-2 expression. In our test series, up-regulation of extracellular signal-regulated protein kinase (ERK) was dispensable for apoptosis induction; DAS, DADS, or DATS did not modify expression of MAPK p38, bax, and bcl-xL. Further investigation revealed that the specific JNK inhibitor SP600125 and the antioxidant NAC bloc...

Antioxidant and pro-oxidant capacities of ITCs

Environmental and Molecular Mutagenesis — Thu, 05 Feb 2009 05:00:00 +0100

Isothiocyanates (ITCs) are breakdown products of glucosinolates contained in cruciciferous vegetables. This heterogeneous family of molecules has the [bond]N[double bond]C[double bond]S group as its common structural feature and possesses important cytoprotective properties. Their biological interactions are strongly related to modulation of cellular redox status, and a number of studies have documented their indirect antioxidant properties, particularly related to induction of phase-2 enzymes. On the other hand, some direct antioxidant behavior has also been observed for a limited number of ITCs. Paradoxically relevant pro-oxidant properties have also been documented, possibly related to the simultaneous induction of phase-1 enzymes. In this review, we will summarize and discuss the preva...

Chromosomal aberrations in railroad transit workers: Effect of genetic polymorphisms

Environmental and Molecular Mutagenesis — Thu, 29 Jan 2009 05:00:00 +0100

Complex chemical mixtures are transported by train from Russia to Finland for further shipment. Here, we studied if exposure to genotoxic components among these substances could affect chromosomal aberrations (CAs) in peripheral lymphocytes of workers handling the tank cars. An initial survey among 48 railroad workers and 39 referents (male smokers and nonsmokers) showed an elevation of CAs. A campaign was started to reduce exposures through preventive measures. Five years later, 51 tank car workers and 40 age-matched referents (all nonsmoking men) were studied for CAs and genetic polymorphisms of xenobiotic metabolism (EPHX1, GSTM1, GSTP1, GSTT1, NAT1, NAT2), DNA repair (ERCC2, ERCC5, XPA, XPC, XRCC1, XRCC3), and folate metabolism (MTHFR, MTR). No increase in CAs was seen in the exposed g...

In vitro genotoxic assessment of xenobiotic diacylglycerols in an in vitro micronucleus assay

Environmental and Molecular Mutagenesis — Wed, 28 Jan 2009 05:00:00 +0100

This study shows that xeno-DGs, which have been neglected in the past for their possible link to any pathological disorders, need serious assessment of their mutagenic potential. Environ. Mal. Mutagen. 2009. © 2009 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

MTBITC mediates cell cycle arrest and apoptosis induction in human HepG2 cells despite its rapid degradation kinetics in the in vitro model

Environmental and Molecular Mutagenesis — Wed, 28 Jan 2009 05:00:00 +0100

This study shows for the first time the inhibitory potency of MTBITC on metabolically competent hepatoma cells, whereas the loss of reduced glutathione and its impact on mitochondria seem to be the major processes involved in the initiation and execution of the apoptotic cell death. The results of this study also showed that irrespective of the intense degradation kinetics of MTBITC, the strong cytostatic effect of the ITC was not markedly affected by it and suggests that although ITCs are only present at maximum concentrations in a living system for a rather short time, this might be sufficient to exert their therapeutic effects. Environ. Mal. Mutagen. 2009. © 2009 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

DNA damage in peripheral blood leukocytes of physically active individuals as measured by the alkaline single cell gel electrophoresis assay

Environmental and Molecular Mutagenesis — Wed, 28 Jan 2009 05:00:00 +0100

DNA damage induced by physical activity and/or exercise has been reported under different conditions but not for individuals maintaining physical fitness by regular strenuous exercise. Therefore, we compared levels of DNA damage in blood leukocytes of 40 healthy individuals (35 males, 5 females) who regularly exercised in gymnasiums / health clubs and 15 healthy sedentary controls who had never exercised. The former group was selected (after informed consent) on the basis of how long they had been exercising on a regular basis as well as their exercise schedule and regimen. The length of time since starting a regular exercise regimen ranged from 2 months to 9 years, whereas the daily exercise duration ranged from 40 min to 3 hrs and warm-up sessions ranged from none to 90 min. The length o...

Polymorphisms in innate immunity genes and lung cancer risk in Xuanwei, China

Environmental and Molecular Mutagenesis — Sat, 24 Jan 2009 05:00:00 +0100

The high incidence of lung cancer in Xuanwei County, China has been attributed to exposure to indoor smoky coal emissions that contain polycyclic aromatic hydrocarbons (PAHs). The inflammatory response induced by coal smoke components may promote lung tumor development. We studied the association between single nucleotide polymorphisms (SNPs) in genes involved in innate immunity and lung cancer risk in a population-based case-control study (122 cases and 122 controls) in Xuanwei. A total of 1,360 tag SNPs in 149 gene regions were included in the analysis. FCER2 rs7249320 was the most significant SNP (OR: 0.30; 95% CI: 0.16-0.55; P: 0.0001; false discovery rate value, 0.13) for variant carriers. The gene regions ALOX12B/ALOX15B and KLK2 were associated with increased lung cancer risk global...

Apoptosis induction by sulfur-containing compounds in malignant and nonmalignant human cells

Environmental and Molecular Mutagenesis — Fri, 23 Jan 2009 05:00:00 +0100

Plants have traditionally represented a main source for the discovery of many biologically active substances with therapeutic values. Sulfur-containing compounds exhibit pleiotropic biological effects supporting their potential use in multitargeted cancer prevention and treatment. As potential anti-cancer agents, they have been shown to inhibit or retard the growth of various cancer cells in culture and implanted tumors in vivo. The compounds significantly inhibit experimental tumorigenesis in a wide range of animal models. A critical and well-elucidated cellular mechanism involved in the anticancer activities of sulfur-containing compounds is the induction of apoptosis through the fine-tuning of orchestrated intracellular signal transduction. This review summarizes the established proapop...

Structural motifs modulating the carcinogenic risk of aromatic amines

Environmental and Molecular Mutagenesis — Sat, 17 Jan 2009 05:00:00 +0100

The structure alerts (SA) for carcinogenicity/mutagenicity are a repository of the science on chemical biological interactions; in addition, they have a crucial role in practical applications for risk assessment. In predictive toxicology, it is crucial that knowledge of SAs is accompanied by knowledge of the structural motifs that modulate their effects. Recently, we have compiled an updated list of SAs implemented in the expert system Toxtree 1.50 (open source, freely available). These SAs are aimed at discriminating between active and inactive chemicals, and include only modulating factors with a high probability of eliminating completely the effect of the SA. Here we have examined the factors that modulate carcinogenic potency: this is an additional piece of information that can have a ...

Inappropriate cytotoxicity measurements

Environmental and Molecular Mutagenesis — Fri, 16 Jan 2009 05:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Chlorophyllin significantly reduces benzo[a]pyrene-DNA adduct formation and alters cytochrome P450 1A1 and 1B1 expression and EROD activity in normal human mammary epithelial cells

Environmental and Molecular Mutagenesis — Fri, 16 Jan 2009 05:00:00 +0100

We hypothesized that chlorophyllin (CHLN) would reduce benzo[a]pyrene-DNA (BP-DNA) adduct levels. Using normal human mammary epithelial cells (NHMECs) exposed to 4 [mu]M BP for 24 hr in the presence or absence of 5 [mu]M CHLN, we measured BP-DNA adducts by chemiluminescence immunoassay (CIA). The protocol included the following experimental groups: BP alone, BP given simultaneously with CHLN (BP+CHLN) for 24 hr, CHLN given for 24 hr followed by BP for 24 hr (preCHLN, postBP), and CHLN given for 48 hr with BP added for the last 24 hr (preCHLN, postBP+CHLN). Incubation with CHLN decreased BPdG levels in all groups, with 87% inhibition in the preCHLN, postBP+CHLN group. To examine metabolic mechanisms, we monitored expression by Affymetrix microarray (U133A), and found BP-induced up-regulatio...

Molecular cytogenetic evaluation of the mechanism of micronuclei formation induced by camptothecin, topotecan, and irinotecan

Environmental and Molecular Mutagenesis — Fri, 16 Jan 2009 05:00:00 +0100

We used the conventional bone marrow micronucleus test complemented with the fluorescent in situ hybridization with the minor satellite DNA probe to investigate the mechanisms of induction of micronuclei in mice treated with camptothecin and its clinical antineoplastic analogues topotecan and irinotecan. All experiments were performed with male Swiss albino mice. Single doses of 1 mg/kg camptothecin or 0.6 mg/kg topotecan were injected intraperitoneally and bone marrow was sampled at 30 hr (camptothecin) or 24 hr (topotecan) after treatment. A dose of 60 mg/kg irinotecan was injected intravenously, once every fourth day for 13 days and bone marrow was sampled 24 hr after the last treatment. In animals treated with camptothecin, a total of 1.07% micronuclei were found and 70% of them were c...

Comment on "Evaluation of evidence for infection as the mode of action for induction of rat lymphoma" by Caldwell et al. [2008]

Environmental and Molecular Mutagenesis — Wed, 24 Dec 2008 05:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Evaluation of frequencies of HPRT mutant lymphocytes in butadiene polymer workers in a Southeast Texas facility

Environmental and Molecular Mutagenesis — Tue, 23 Dec 2008 05:00:00 +0100

We examined the frequency of mutant lymphocytes (VFs) in workers (n = 30) occupationally exposed to the petrochemical, 1,3-butadiene (BD), using the autoradiographic HPRT mutant lymphocyte assay. Current exposures were determined with organic vapor monitors that had a 12-hr method detection limit (MDL) of 2.5 parts per billion (ppb). HPRT VFs were analyzed with respect to current exposure estimates, age in years, and occupational longevity (OL; defined as years working in the BD industry at this facility). Current exposures were low (mean 93.5 ppb, median 2.5 ppb) with only one individual's estimate (1683.5 ppb) exceeding the Occupational Safety and Health Administration's permissible exposure limit of 1,000 ppb. The majority (>50%) of current exposures were below the MDL. HPRT VFs were no...

Urinary levels of oxidative DNA and RNA damage among workers exposed to polycyclic aromatic hydrocarbons in silicon production: Comparison with 1-hydroxypyrene

Environmental and Molecular Mutagenesis — Tue, 23 Dec 2008 05:00:00 +0100

Polycyclic aromatic hydrocarbons (PAH) are ubiquitous occupational and environmental pollutants and the urinary excretion of 1-hydroxypyrene (1-OHP) is classically measured for the determination of PAH exposure internal dose. Some of PAH are tumorigenic due to their metabolites ability to generate DNA adducts and oxidative DNA damage through the production of reactive oxygen species during metabolism. 8-hydroxy-7,8-dihydro-2[prime]-deoxyguanosine (8-OHdGuo) is one of the major oxidative DNA lesions and its use as a potential biomarker of genotoxic PAH occupational exposure should be evaluated. Indeed conflicting results are frequently reported in occupational studies in terms of correlation between 8-OHdGuo urinary levels and PAH exposure. The aim of our study was therefore to determine th...

Radiation-induced bystander effects in vivo are epigenetically regulated in a tissue-specific manner

Environmental and Molecular Mutagenesis — Tue, 23 Dec 2008 05:00:00 +0100

Exposure of animal body parts to ionizing radiation (IR) can lead to molecular changes in distant shielded "bystander" tissues and organs. Nevertheless, tissue specificity of bystander responses within the same organism has not been examined in detail. Studies on in vivo bystander effect conducted so far analyzed changes induced by single-dose exposure. The potential of fractionated irradiation to induce bystander effects in vivo has never been studied. We analyzed changes in global DNA methylation and microRNAome in skin and spleen of animals subjected to single-dose (acute or fractionated) whole-body or cranial exposure to 0.5 Gy of X-rays. We found that IR-induced DNA methylation changes in bystander spleen and skin were distinct. Acute radiation exposure resulted in a significant loss ...

Cigarette smoke extract induces expression of cell adhesion molecules in HUVEC via actin filament reorganization

Environmental and Molecular Mutagenesis — Tue, 23 Dec 2008 05:00:00 +0100

Epidemiologic studies have shown a strong association between cigarette smoking and cardiovascular diseases. Various oxidative species and free radicals are produced during cigarette smoking and these lead to endothelial dysfunction and inflammation. Expression of adhesion molecules, such as intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1, and adhesion of leukocytes are present in atherosclerosis. We showed previously that a nonfractionated cigarette smoke extract (CSE) induces surface expression of ICAM-1 and E-selectin in human umbilical vein endothelial cells (HUVEC). We then investigated the role of the MAPKs (ERK1/2, JNK, and p38) and AP-1 and the role of actin cytoskeleton reorganization in the CSE-induced expression of ICAM-1 and E-selec...

A novel germline mutation in Big Blue® mice

Environmental and Molecular Mutagenesis — Tue, 23 Dec 2008 05:00:00 +0100

The Big Blue® lacI mutation detection assay is well validated and has permitted detailed analysis of spontaneous mutations in individual tissues over the lifespan of the mouse. In a recent assay of spontaneous mutations, a novel lacI mutation (C354T) recurred in six of seven mutants with a second mutation. The frequency of spontaneous doublets (mutants with two nontandem mutations) was elevated 2.7-fold over that previously reported (Hill KA et al., []: Mutat Res 554:223-240) for normal tissues (6.3 × 10-7 herein vs. 2.36 × 10-7). The average spacing between mutations in the doublets (237 bp) was greater than previously reported for spontaneous doublets. The frequency of C354T as a "hitchhiker" mutation in doublets was consistent with a germline mutation in one of 38 mutation targets in...

Investigation of the genotoxic effect of pesticides on greenhouse workers' lymphocytes

Environmental and Molecular Mutagenesis — Tue, 23 Dec 2008 05:00:00 +0100

In conclusion, our results indicate that the greenhouse workers who participated in this study had no detectable increased DNA damage or alteration in their cellular response to DNA damage in comparison to our control population. Environ. Mol. Mutagen., 2009. © 2008 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

NAT2 fast acetylator genotype and MGMT promoter methylation may contribute to gender difference in K-RAS mutation occurrence in Taiwanese colorectal cancer

Environmental and Molecular Mutagenesis — Tue, 23 Dec 2008 05:00:00 +0100

In conclusion, Taiwanese women with the NAT2 fast acetylator genotype may exhibit a higher risk of CRC with increased occurrence of K-RAS mutation. Detection of NAT2 genotypes and MGMT promoter methylation may be useful in the risk assessment for CRC in Taiwanese women. Environ. Mol. Mutagen., 2009. © 2008 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Sheldon Wolff 1928-2008

Environmental and Molecular Mutagenesis — Tue, 23 Dec 2008 05:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Response to letters to the editor: Caldwell et al. [2008]

Environmental and Molecular Mutagenesis — Tue, 23 Dec 2008 05:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Mycoplasma pulmonis and lymphoma

Environmental and Molecular Mutagenesis — Tue, 23 Dec 2008 05:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Mutational analysis of the mitochondrial tRNA genes and flanking regions in umbilical cord tissue from uninfected infants receiving AZT-based therapies for prophylaxis of HIV-1

Environmental and Molecular Mutagenesis — Sun, 23 Nov 2008 05:00:00 +0100

A sensitive vertical denaturing gradient gel electrophoresis (DGGE) method, using 13 unipolar psoralen-clamped PCR primer pairs, was developed for detecting sequence variants in the 22 tRNA genes and flanking regions (together spanning [sim]21%) of the human mitochondrial genome. A study was conducted to determine (i) if mitochondrial DNA (mtDNA) polymorphisms and/or mutations were detectable in healthy newborns and (ii) if prepartum 3[prime]-azido-2[prime],3[prime]-dideoxythymidine (AZT) based HIV-1 prophylaxis was associated with significant increases in mtDNA mutations and changes in the degree of heteroplasmy of sequence variants in uninfected infants born to HIV-1-infected mothers. DGGE analysis of umbilical cord tissue (where vascular endothelium and smooth muscle cells are the major...

Genetic signature for human risk assessment: Lessons from trichloroethylene

Environmental and Molecular Mutagenesis — Thu, 20 Nov 2008 05:00:00 +0100

Trichloroethylene (TCE), an organic solvent commonly used for metal degreasing and as a chemical additive, is a significant environmental contaminant that poses health concerns in humans. The US Environmental Protection Agency (EPA) is currently revising the 2001 TCE human risk assessment draft. The next draft is expected to be ready in 2008. TCE metabolites are detectable in humans and carry varying potencies for induction of cancers in animals. Genomic mechanisms have been explored in animals and humans to link TCE to carcinogenesis. DNA analysis provides an opportunity for detection of unique genetic alterations representing a signature of TCE exposure. These alterations can arise from genotoxic and nongenotoxic pathways at multiple points throughout tumorigenesis. Although fixation of ...

The in vitro genotoxic effects of a commercial formulation of [alpha]-cypermethrin in human peripheral blood lymphocytes

Environmental and Molecular Mutagenesis — Thu, 20 Nov 2008 05:00:00 +0100

[alpha]-Cypermethrin, a highly active pyrethroid insecticide, is effective against a wide range of insects encountered in agriculture and animal husbandry. The potential genotoxicity of a commercial formulation of [alpha]-cypermethrin (Fastac 100 EC, containing 10% [alpha]-cypermethrin as the active ingredient) on human peripheral lymphocytes was examined in vitro by sister chromatid exchange (SCE), chromosomal aberrations (CAs), and micronucleus (MN) tests. The human lymphocytes were treated with 5, 10, 15, and 20 [mu]g/ml of [alpha]-cypermethrin for 24- and 48-hr. [alpha]-Cypermethrin induced SCEs and CAs significantly at all concentrations and treatment times and MN formation was significantly induced at 5 and 10 [mu]g/ml of [alpha]-cypermethrin when compared with both the control and s...

DNA damage in Pakistani agricultural workers exposed to mixture of pesticides

Environmental and Molecular Mutagenesis — Thu, 20 Nov 2008 05:00:00 +0100

A cross-sectional study was designed to determine whether occupational exposure to a complex mixture of pesticides results in a significant increase of DNA damage in farmers chronically exposed to pesticides in open fields. Leukocytes from 47 agriculture workers exposed to pesticides and 50 controls were evaluated with comet assay. Workers recruitment was based on their exposure to pesticides during the spraying season on cotton crop. Serum from these individuals was also analyzed for pesticides presence using high performance liquid chromatography. Statistically significant difference (P < 0.001) in DNA damage of exposed individuals (mean ± S.D 14.80 ± 3.04 [mu]m) was observed when compared with control group (6.54 ± 1.73 [mu]m) as studied on the basis of comet tail length. Smokers had...

Genotoxic and reproductive effects of an industrially contaminated soil on the earthworm Eisenia Fetida

Environmental and Molecular Mutagenesis — Thu, 20 Nov 2008 05:00:00 +0100

Polluted soil sampled from a former coking plant in Lorraine (France) was studied for its genotoxicity and reproductive effects on the Eisenia fetida earthworm. Genotoxicity was investigated by means of the single-cell gel electrophoresis (comet) assay on the coelomocytes of earthworms after 4 and 10 days of exposure to the soil. DNA damage and a decline in the number of coelomocytes extruded from earthworms were observed at coking plant soil concentrations of 20 and 40% (w/w) in ISO soil. These soil concentrations had previously been shown to significantly reduce cocoon and juvenile productions after 28 and 56 days of earthworm exposure, respectively. The results showed that genotoxic pollutants in the tested soil were still bioavailable despite the age of the contaminated soil. Similar v...

Comparison of gene expression profiles in HepG2 cells exposed to arsenic, cadmium, nickel, and three model carcinogens for investigating the mechanisms of metal carcinogenesis

Environmental and Molecular Mutagenesis — Thu, 20 Nov 2008 05:00:00 +0100

In this study, we examined the gene expression alteration in human hepatoma cell line, HepG2, after exposing to two metals (cadmium and nickel), a metalloid (arsenic), and three model carcinogenic chemicals N-dimethylnitrosoamine (DMN), 12-O-tetradecanoylphorbol-13-acetate (TPA), and tetrachloroethylene (TCE) using DNA microarrays with 8,795 human genes. Of the genes altered by As, Cd, and Ni exposures, 31-55% were overlapped with those altered by three model carcinogenic chemical exposures in our experiments. In particular, the metals and metalloid shared certain characteristics with TPA and TCE in remarkable upregulations of the genes associated with progression of cell cycle, which might play a central role in As, Cd, and Ni carcinogenesis. This characteristic of gene expression alterat...

Diallyl trisulfide selectively causes Bax- and Bak-mediated apoptosis in human lung cancer cells

Environmental and Molecular Mutagenesis — Thu, 18 Sep 2008 04:00:00 +0100

In conclusion, the present study indicates that Bax and Bak proteins are critical targets of DATS-induced apoptosis in human lung cancer cells. Environ. Mol. Mutagen., 2008. © 2008 Wiley-Liss, Inc. (Source: Environmental and Molecular Mutagenesis)

Multipronged evaluation of genotoxicity in Indian petrol-pump workers

Environmental and Molecular Mutagenesis — Wed, 17 Sep 2008 04:00:00 +0100

This study used human biomonitoring to evaluate the genotoxic effects of exposure to benzene in petrol fumes in 100 Indian petrol-pump workers (PPWs) and an equal number of controls. The study was corroborated with in silico assessments of the Comet assay results from the human biomonitoring study. An in vitro study in human lymphocytes was also conducted to understand the genotoxicity of benzene and its metabolites. In a subset of the population studied, higher blood benzene levels were detected in the PPWs (n = 39; P < 0.01) than the controls (n = 18), and 100-250 ppb benzene was also detected in air samples from the petrol pumps. PPWs had higher levels of DNA damage than the controls (P < 0.01). In addition, the micronucleus assay was performed on lymphocytes from a subset of the subjec...

K-ras cancer gene mutations in lung tumors from female Swiss (CD-1) mice exposed transplacentally to 3[prime]-azido-3[prime]-deoxythymidine

Environmental and Molecular Mutagenesis — Wed, 17 Sep 2008 04:00:00 +0100

A transplacental carcinogenicity study was conducted by exposing pregnant Swiss (CD-1) mice to 0, 50, 100, 200, or 300 mg 3[prime]-azido-3[prime]-deoxythymidine (AZT)/kg body weight (BW) daily for the duration of gestation (18-19 days) [National Toxicology Program,]. The incidence of alveolar/bronchiolar adenomas and carcinomas in the 200 and 300 mg/kg groups was significantly higher (P = 0.027 and 0.007, respectively) in male offspring, but not in females (P = 0.338 and 0.315, respectively). The purpose of the present study was to evaluate K-ras mutation status in lung tumors from the female offspring in AZT exposed groups and to determine whether at the molecular level there were signature K-ras mutations in lung tumors that were different from spontaneous tumors. K-ras mutation was dete...

Effects of the XRCC1 gene-environment interactions on DNA damage in healthy Japanese workers

Environmental and Molecular Mutagenesis — Wed, 17 Sep 2008 04:00:00 +0100

X-ray repair crosscomplementing group 1 (XRCC1) has a central role in base excision repair (BER) and single-strand break repair (SSBR). XRCC1 gene polymorphisms (codons 194, 280, and 399) have been identified, and in some cases have been reported to contribute to variations in DNA repair capacity and susceptibility to cancer. To further characterize the effects of XRCC1 gene polymorphisms and their possible interactions with environmental factors on individual levels of DNA damage, we investigated the XRCC1 genotypes of 222 healthy Japanese workers and analyzed data with respect to smoking, drinking habits, age, and health practice index (HPI). Our results showed that poor HPI would associate with a higher level of tail moment (TM). Individuals with one or two XRCC1R280H variant alleles ex...

Induction of hypothermic conditions associated with increased micronuclei formation in sigma-1 receptor knockout mice after administration of the antipsychotic compound E-5842

Environmental and Molecular Mutagenesis — Wed, 17 Sep 2008 04:00:00 +0100

The antipsychotic sigma-1 ([sigma]1) receptor ligand E-5842 has been shown to increase micronucleated polychromatic erythrocyte (MNPCE) frequency in mouse bone marrow secondary to compound-induced hypothermia. Interaction with [sigma]1 receptor has been considered a plausible contributing factor for E-5842-induced hypothermia, raising concern for a possible class effect of sigma receptor ligands in the mouse micronucleus (MN) test. We assessed the potential of E-5842 (200 mg/kg, oral) to produce hypothermic conditions associated with increased micronuclei formation in [sigma]1 receptor knockout ([sigma]1R-KO) and wild type (WT) mice. After administration, animal's rectal temperature was recorded and peripheral blood and bone marrow samples were obtained (48 hr) and assessed for induction o...

Gene expression changes associated with xenobiotic metabolism pathways in mice exposed to acrylamide

Environmental and Molecular Mutagenesis — Wed, 17 Sep 2008 04:00:00 +0100

In this study, groups of male mice were administered 500 mg/L AA in drinking water for 3 weeks, and gene expression changes were evaluated in the livers of AA-treated mice within 24 hr of the last treatment. When a two-fold cutoff value and a P-value less than 0.05 were selected, 696 genes (233 up-regulated and 463 down-regulated) were identified as differentially expressed genes in AA-treated mice when compared with the controls. Gene ontology analysis revealed that the principle pathways affected by AA were xenobiotic metabolism by cytochrome P450 (CYPs) and glutathione metabolism, suggesting that drug and/or xenobiotic metabolism is most affected by exposure. The results provide more information about AA metabolism and further insight into the molecular mechanisms involved in AA-induced...

Kinetics of [gamma]-H2AX focus formation upon treatment of cells with UV light and alkylating agents

Environmental and Molecular Mutagenesis — Wed, 17 Sep 2008 04:00:00 +0100

Histone H2AX is rapidly phosphorylated in response to DNA double-strand breaks (DSBs) induced by ionizing radiation (IR). Here we show that DNA damage induced by alkylating agents [methyl methanesulfonate (MMS) and N-methyl-N[prime]-nitro-N-nitrosoguanidine (MNNG)] and ultraviolet light (UV-C) leads to a dose and time dependent accumulation of phosphorylated H2AX ([gamma]-H2AX). Time course experiments revealed that the number of [gamma]-H2AX foci reached peak levels 8 hr after MMS or MNNG treatment and declined to almost control values within 24 hr after exposure. Upon UV-C treatment, a biphasic response was observed with a maximum 12 hr after treatment. In 43-3B cells deficient in nucleotide excision repair (NER) the number of [gamma]-H2AX foci increased steadily. [gamma]-H2AX foci were ...

Chromosome aberrations in peripheral blood lymphocytes of high-risk HPV-infected women with HGSIL

Environmental and Molecular Mutagenesis — Wed, 20 Aug 2008 04:00:00 +0100

Genomic instability is one of the main characteristics of malignant tumors, including HPV-induced cervical cancer. The aim of this study was to explore the use of assessing chromosome aberrations (CA) in peripheral blood lymphocytes as a biomarker for genomic instability in high-risk HPV-infected women with high-grade squamous intraepithelial lesions (HGSIL). A total of 120 women were recruited for this study, following cytology/colposcopy evaluation and HPV DNA detection. The study groups consisted of 30 HPV(+) women with histologically confirmed cervical intraepithelial neoplasia grade 2/3 and 30 HPV(+) women with carcinoma in situ (CIS). Two control groups, including 30 women HPV(-) and 30 women HPV(+), were recruited among women who were reported as cytology negative. Lymphocyte cell c...

Clonal expansions of 6-thioguanine resistant T lymphocytes in the blood and tumor of melanoma patients

Environmental and Molecular Mutagenesis — Tue, 19 Aug 2008 04:00:00 +0100

The identification of specific lymphocyte populations that mediate tumor immune responses is required for elucidating the mechanisms underlying these responses and facilitating therapeutic interventions in humans with cancer. To this end, mutant hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficient (HPRT-) T-cells were used as probes to detect T-cell clonal amplifications and trafficking in vivo in patients with advanced melanoma. Mutant T-cells from peripheral blood were obtained as clonal isolates or in mass cultures in the presence of 6-thioguanine (TG) selection and from tumor-bearing lymph nodes (LNs) or metastatic melanoma tissues by TG-selected mass cultures. Nonmutant (wild-type) cells were obtained from all sites by analogous means, but without TG selection. cDNA sequenc...

Poster abstracts

Environmental and Molecular Mutagenesis — Tue, 12 Aug 2008 04:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Platform abstracts

Environmental and Molecular Mutagenesis — Tue, 12 Aug 2008 04:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Workshop abstracts

Environmental and Molecular Mutagenesis — Tue, 12 Aug 2008 04:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Topical review abstracts

Environmental and Molecular Mutagenesis — Tue, 12 Aug 2008 04:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Symposium abstracts

Environmental and Molecular Mutagenesis — Tue, 12 Aug 2008 04:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Environmental Mutagen Society 39th Annual Meeting

Environmental and Molecular Mutagenesis — Tue, 12 Aug 2008 04:00:00 +0100

No abstract. (Source: Environmental and Molecular Mutagenesis)

Comparison of metabolite profiles generated in Aroclor-induced rat liver and human liver subcellular fractions: Considerations for in vitro genotoxicity hazard assessment

Environmental and Molecular Mutagenesis — Tue, 15 Jul 2008 04:00:00 +0100

Because it is well known that metabolites of chemicals and drugs are frequently the ultimate species responsible for genotoxicity and carcinogenicity, in vitro testing to identify the human genotoxicity hazard potential of new chemicals and drugs routinely utilizes liver S-9 fraction from rats treated with Aroclor 1254 as a system that can generate metabolites. However, it is frequently questioned as to whether such an in vitro metabolite generation system is the most relevant for human risk, or whether the assay would be better served by using a human-derived in vitro system. To address this, 16 common drugs have been examined for profiles of metabolites in Aroclor-induced rat liver S-9 and pooled human liver S-9. Metabolite profiles were compared using high pressure liquid chromatography...

Faulty spindle checkpoint and cohesion protein activities predispose oocytes to premature chromosome separation and aneuploidy

Environmental and Molecular Mutagenesis — Mon, 14 Jul 2008 04:00:00 +0100

Aneuploidy accounts for a major proportion of human reproductive failures, mental and physical anomalies, and neoplasms. To heighten our understanding of normal and abnormal chromosome segregation, additional information is needed about the underlying molecular mechanisms of chromosome segregation. Although many hypotheses have been proposed for the etiology of human aneuploidy, there has not been general acceptance of any specific hypothesis. Moreover, it is important to recognize that many potential mechanisms exist whereby chromosome missegregation may occur. One area for investigating aneuploidy centers on the biochemical changes that take place during oocyte maturation. In this regard, recent results have shown that faulty mRNA of spindle-assembly checkpoint proteins and chromosome co...

Development of an in vivo gene mutation assay using the endogenous Pig-A gene: II. Selection of Pig-A mutant rat spleen T-cells with proaerolysin and sequencing Pig-A cDNA from the mutants

Environmental and Molecular Mutagenesis — Mon, 14 Jul 2008 04:00:00 +0100

We previously reported that rat spleen T-cells and peripheral red blood cells that are deficient in glycosylphosphatidylinositol (GPI) synthesis [presumed mutants for the phosphatidylinositol glycan complementation group A gene (Pig-A)] could be detected by flow cytometry (FCM) as cells negative for GPI-linked markers (CD48 and CD59, respectively). To establish this procedure as a rapid in vivo gene mutation assay, we have examined the Pig-A gene of GPI-deficient rat spleen T-cells for DNA sequence alterations. Splenocytes were isolated from male F344 rats, primed with ionomycin and phorbol-12-myristate-13-acetate, and seeded at limiting-dilution into 96-well plates. To select for GPI-deficient T-cells, the cells were cultured for 10 days in a medium containing rat T-STIM® and 2 nM proaer...

Development of an in vivo gene mutation assay using the endogenous Pig-A gene: I. Flow cytometric detection of CD59-negative peripheral red blood cells and CD48-negative spleen T-cells from the rat

Environmental and Molecular Mutagenesis — Mon, 14 Jul 2008 04:00:00 +0100

The product of the phosphatidylinositol glycan complementation group A gene (Pig-A) is involved in the synthesis of glycosylphosphatidylinositol (GPI) anchors that link various protein markers to the surface of several types of mammalian cells, including hematopoietic cells. Previous observations indicate that Pig-A mutation results in the lack of GPI synthesis and the absence of GPI-anchored proteins on the cell surface. As a first step in designing a rapid assay for measuring Pig-A mutation in the rat, we developed flow cytometry (FCM) strategies for detecting GPI-negative cells in rat peripheral blood and spleen. Anti-CD59 was used to detect GPI-anchored proteins on red blood cells (RBCs), and anti-CD48 was used to detect GPI-anchored proteins on spleen T-cells. The spontaneous frequenc...