bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of induced sister chromatid exchange levels in chinese hamster ovary cells and cultured human lymphocytes
Authors: Morgan William F. , Crossen Peter E.
Published: February 2007

Human lymphocytes and Chinese hamster ovary cells were exposed to DNA damaging agents for two cell cycles, and the induced sister chromatid exchange (SCE) rate was compared. CHO cells showed a significant increase in SCE following treatment with bleomycin and vincristine whereas human lymphocytes did not. Both CHO cells and lymphocytes showed an increase in SCE with 5‐bromode‐oxyuridine (BrdUrd) and tritiated uridine (3H‐Urd) but the increase was greater in CHO cells. SCE levels were similar after exposure to proflavine and colcemid did not increase the exchange frequency in either cell type. Apparently CHO cells are more sensitive than human lymphocytes to the actions of bleomycin, vincristine, BrdUrd, and 3H‐Urd. SCE analysis in response to mutagens and carcinogens should therefore be based on more than one cell type.
Metabolic activation of 3‐methylcholanthrene and benzo(a)pyrene to mutagens in the L5178Y/TK assay by cultured embryonic rodent cells
Authors: Amacher David E. , Paillet Simone C. , Zelljadt Inna
Published: February 2007

Early passage cultured rodent cells obtained from mouse, rat, or Syrian hamster embryos were cocultivated with L5178Y/TK+/‐ cells in the presence of benzo(a)pyrene (B(a)P) or 3‐methylcholanthrene (3MCA) for 6 hr to determine if active metabolic intermediates could be detected in this cell‐mediated assay through the induction of TK+/‐ mutants. Neither chemical was directly active as a mutagen when tested with L5178Y/TK+/‐ cells alone. As a mutagen, 3MCA was slightly active in the presence of mouse or rat embryo cells and clearly active when tested with hamster embryo cells. B(a)P was active only in the presence of hamster embryo cells when tested at concentrations that would be mutagenic in the presence of rodent liver microsomal preparations. These results indicate the utility of L5178Y/TK+/‐ plus hamster embryo cell combinations in a cell‐mediated mutation assay for the detection of these two polycyclic hydrocarbon carcinogens.
Sister chromatid exchanges induced in rabbit lymphocytes by ethylene oxide after inhalation exposure
Authors: Yager Janice W. , Benz R. Daniel
Published: February 2007

Ethylene oxide, which is the simplest epoxide and an extremely important commercial compound, has been used by many investigators as a model compound to study mutagenicity by alkylation of DNA. Knowledge of in vivo dose‐effect relations under experimental conditions may provide further insight into the dynamics of the sister chromatid exchange (SCE) response. It may also provide information on temporal aspects of sampling design for human worker populations. Groups of four male New Zealand white rabbits were exposed in inhalation chambers to 0, 10, 50, and 250 parts per million (ppm) ethylene oxide for 6 hr a day, 5 days a week, for 12 weeks. Peripheral blood samples were taken before the start of exposure, at intervals during exposure, and up to 15 weeks after the end of exposure to measure SCE rates in peripheral lymphocytes as well as standard hematological endpoints. Additionally, the level of reduced glutathione (GSH) in liver and blood was measured in a set of concurrently exposed animals at the end of the 12‐week exposure. Results show that exposure to 10 ppm does not cause a detectable increase in SCE rates. However, exposure to 50 and 250 ppm does cause an increase in SCEs that decreases after exposure ends, but still remains above baseline levels 15 weeks after exposure. Hematological and GSH measurements did not differ between control and exposed groups. These results indicate that inhalation exposure to the mutagenic alkylating agent ethylene oxide results in a dose‐related SCE effect, and that SCE is a more sensitive indicator of exposure than either standard hematological end points or GSH levels.
Mutagenicity in salmonella typhimurium and structure‐activity relationships of wastewater components emanating from the manufacture of trinitrotoluene
Authors: Spanggord Ronald J. , Mortelmans Kristien E. , Griffin Ann F. , Simmon Vincent F.
Published: February 2007

The mutagenicity of 36 polynitroaromatic compounds was investigated with five strains of Salmonella typhimurium. Isomeric trinitrotoluenes (TNT), with the exception of 2,4,6‐TNT and 2,3,4‐TNT, exhibit mutagenicity independently of nitroreductase enzymes, but isomeric aminodinitrotoluenes (ADNT) and isomeric dinitrotoluenes (DNT) need nitroreductase to induce mutation. Within groups of isomeric TNTs, DNTs, and ADNTs, mutagenic response was enhanced by a para orientation of nitro groups. The mutagenic response of isomeric DNTs was found to correlate with the compound's ability to undergo charge‐transfer complexation with reductive enzymes, whereas further complexation (such as a Janovsky complex) appears to be required for inducing mutation in dinitrobenzenes. These results indicate that polynitroaromatic compounds in TNT wastewaters possess a significant potential for biologic activity.
Induction of sister chromatid exchanges and inhibition of cellular proliferation in vitro. I. caffeine
Authors: Guglielmi Gwen E. , Vogt Thomas F. , Tice Raymond R.
Published: February 2007

Cytogenetic assay systems based on the detection of sister chromatid exchanges (SCE) are widely advocated as a sensitive screening method for assessing genotoxic potential. While many agents have been examined for their ability to induce SCE's, complete dose‐response information has often been lacking. We have reexamined the ability of one such compound — caffeine — to induce SCEs and also to inhibit cellular proliferation in human peripheral lymphocytes in vitro. An acute exposure to caffeine prior to the DNA synthetic period did not affect either SCE frequency or the rate of cellular proliferation. Chronic exposure to caffeine throughout the culture period lead to both a dose‐dependent increase in SCEs (SCEd or doubling dose = 2.4 mM; SCE10 or the dose capable of inducing 10 SCE = 1.4 mM) and a dose‐dependent inhibition of cellular proliferation (IC50 or the 50% inhibition concentration = 2.6 mM). The relative proportion of first generation metaphase cells, an assessment of proliferative inhibition, increased linearly with increasing caffeine concentrations. However, SCE frequency increased nonlinearly over the same range of caffeine concentrations. Examination of the ratio of nonsymmetrical to symmetrical SCEs in third generation metaphase cells indicated that caffeine induced SCEs in equal frequency in each of three successive generations. The dependency of SCE induction and cellular proliferative inhibition on caffeine's presence during the DNA synthetic period suggests that caffeine may act as an antimetabolite in normal human cells. The significance of these results in regard to both caffeine's genotoxic potential and to the reliability of the SCE assay system are discussed.
Mithramycin‐ and triethylene melamine‐induced sperm abnormalities in lakeview hamsters
Authors: Singh H. , Newton Deborah
Published: February 2007

The sperm abnormality‐inducing action of two potential mutagenic agents, mithramycin and triethylene melamine (TEM), in inbred Lakeview hamsters was studied and results compared with similar investigations in mouse. Test hamsters received subacute intraperitoneal exposures ranging from 0.01 to 0.25 mg/kg body weight with either agent for 5 consecutive days. Testis weights, epididymal sperm numbers, and body weights were also monitored at weeks 1, 4, and 10 after treatment. Mithramycin‐treated hamsters showed 21 times more sperm abnormalities than control (25% vs. 1.2%) whereas TEM elevated sperm abnormalities by eight fold. The frequency and type of aberrant sperm varied with dose and time, being the highest at weeks 1 or 4, rather than week 10, with either agent. Sperm number and testis weights remained depressed considerably from 4 to 10 weeks after treatment with either agent. Body weights in chemically treated hamsters remained within 28% of control for the test period. Even though our findings were in general agreement with those reported for mouse, the magnitude of the response and the stage of spermatogenic sensitivity in the chemical induction of sperm abnormalities in the two species were different.
Microbial detection of mutagenic nitro‐organic compounds in filtrates of coal fly ash
Authors: Wei Cheng‐I , Raabe Otto G. , Rosenblatt Leon S.
Published: February 2007

The presence of mutagenic nitro‐organic compounds on coal fly ash was indicated by the greatly reduced microbial mutagenicity of the ash filtrates with nitroreductase‐deficient strains of Salmonella typhimurium compared to their corresponding parental strains. Addition of the liver S‐9 microsomal enzyme preparation significantly increased the mutagenic activities of the ash extracts. Extracts of fly ash mutagens were prepared with horse serum, dimethyl sulfoxide, or azeotropic benzene/methanol mixture. The data were normalized to net revertants per 108 Salmonella typhimurium cells per milligram of ash used. This normalization procedure is essential for interpretation of comparative results. Both four‐way and three‐way analyses of variance were used to simultaneously evaluate the differences between solvent extracts, fly ash mutagen, S‐9 activation, and nitroreductase‐deficient strains and their parental strains. Of the three extraction systems tested, benzene/methanol azeotropic mixture was generally found to have the highest extraction power, and horse serum was the lowest. The results show that overall 87.5% (± 1.8 SE) of the mutagenic activity of the fly ash was associated with nitro‐organic compounds.
Structure‐activity studies on the mutagenicity of tris(2,3‐dibromopropyl) phosphate (tris‐BP) and its metabolites in salmonella
Authors: Zeiger Errol , Pagano Dennis A. , Nomeir Amin A.
Published: February 2007

A series of methylated metabolites of the flame retardant tris(2,3‐dibromopropyl) phosphate (Tris‐BP) were tested for mutagenicity in Salmonella, along with the parent chemical and other structurally related chemicals. The metabolites produced a gradient of mutagenic responses in TA1535 in the same dose range and up to the same magnitude as the Tris‐BP response. None of the metabolites tested appeared to be the ultimate mutagen, since they all required S‐9 for their mutagenic activity.
Cytotoxic and mutagenic properties of shale oil byproducts II. Comparison of mutagenic effects at five genetic markers induced by retort process water plus near ultraviolet light in chinese hamster ovary cells
Authors: Chen David Jen‐Chi , Strniste Gary F.
Published: February 2007

A chinese hamster ovary (CHO) cell line heterozygous at the adenine phosphoribosyl transferase (APRT) locus was used for selection of induced mutants resistant to 8‐azaadenine (8AA), 6‐thioguanine (6TG), ouabain (OUA), emetine (EMT) and diphtheria toxin (DIP). The expression times necessary for optimizing the number of mutants recovered at the different loci have been determined using the know direct acting mutagen, far ultraviolet light (FUV), and a complex aqueous organic mixture (shale oil process water) activated with near ultraviolet light (NUV). Our results indicate that optimal expression times following treatment with either mutagen was between 2 and 8 days (depending on the genetic marker examined). For CHO cells treated with shale oil process water and subsequently exposed to NUV a linear dose response for mutant induction was observed for all five genetic loci. At 10% surviving fraction of cells, between 35‐ and 130‐fold increases above background mutation frequencies were observed for the various markers examined. Among the five genetic loci tested, OUAR was the most sensitive marker tested.
Chromosome analysis of preimplantation embryos after cadmium treatment of oocytes at meiosis I
Authors: Watanabe Toshiaki , Endo Akira
Published: February 2007

Female mice were given a single subcutaneous injection of cadmium chloride (1.5 mg or 3.0 mg/kg body weight) at the metaphase I stage of oogenesis. The incidences of blastocysts with trisomies and triploidies were significantly increased in the cadmium‐treated groups. Chromosome analysis of preimplantation embryos may be one of the useful in vivo methods for screening for chromosome anomalies induced in mammalian germ cells.
Sister chromatid exchanges in chines hamster cells treated with seventeen organophosphorus compounds in the presence of a metabolic activation system
Authors: Chen H. H. , Sirianni S. R. , Huang C. C.
Published: February 2007

The mutagenicity of several organophosphorus pesticides (OPP) has been demonstrated by Wild [1975] in microorganisms. However, the results as reported in the literature of cytogenic, mutagenic, and carcinogenic tests using mammalian cells or experimental animals were scanty and inconclusive [Huang, 1973; Wild, 1975]. This may be partly due to the high toxicity and rapid degradation of these compounds by mammalian cells both in vitro and in vivo [Wild, 1975]. Since sister chromatid exchange (SCE) has proved to be a highly sensitive indicator of genetic damage [Latt, 1975] and for certain chemicals there was a good correlation between the induction of SCE and point mutations in mammalian cells [Carrano et al, 1978; Sirianni and Huang, 1980], we have studied and reported the effect of a total of 17 OPP on induction of sister chromatid exchange and cell cycle delay in an in vitro system using V79 cells without metabolic activation [Chen et al, 1981, 1982]. Among the 17 OPP tested, 8 were able to induce increased SCE frequencies and the other 9 caused no increase in SCE as compared to the control values. The OPP that proved to be positive SCE inducers were methyl‐parathion, demeton, trichlorfon, dimethoate, malathion, methidathion, oxydemeton methyl, and fenthion. The other nine that caused no SCE increase were diazinion, disyston, amaze, azinphosmethyl, bolstar, DEF, fensulfothion, monitor, and nemacur. In addition, cell cycle delay in various degrees was observed after treatment of V79 cells with all the OPP except for fensulfothion and oxydemeton methyl. However, for all experiments there was no clear correlation between the degree of cell cycle delay and induction of SCE.
Effect of selection cell density on the recovery of mutagen‐induced 6‐thioguanine‐resistant cells (CHO/HGPRT system)
Authors: O'Neill J. P. , Bowman K. O.
Published: February 2007

The relationship between the cell density utilized in the selection for 6‐thioguaninine‐resistant mutants induced by ethyl methanesulfonate and the recovery of mutant colonies was determined in Chinese hamster ovary cells. After an adequate phenotypic expression time of 9 days post mutagen treatment, cultures were plated in selection medium at cell densities ranging from 5 × 104 to 2 × 106 cells/100 mm dish (0.9 to 36.0 × 103 cells/cm2). A decline in the frequency of mutant colonies was observed with increasing cell density, and analysis of the data showed that the loss was independent of the frequency of mutants in the cell population. This loss occurred in an exponential fashion, consistent with a random‐target effect. Regression analysis of the data points yielded a best‐fit line defined by the equation log(y) = 2.01 ‐ 0.26(10−6) x, where y = percentage recovery and × = selection cell density (cells per 100 mm dish). This study defines the cell densitydependent loss of mutants under selection conditions, and provides a basis for further study of the influence of agents on cell contact‐mediated crossfeeding and possible effects on mutation induction determinations. These results also demonstrate the importance of the use of appropriate cell densities in mutant selections.
Adult toxicity and dominant lethals induced by ozone at specific stages in spermatogenesis in drosophila virilis
Authors: Erdman H. E. , Hernandez T.
Published: February 2007

Ozone, a highly reactive three‐atom allotrope of oxygen, is formed in high concentrations in various kinds of microenvironments, including electron microscopes, office copy machines, and X‐ray devices. Mutagenicity and action modus operandi of ozone suggest its radiomimetic property. In order to test for ozone‐induced dominant lethals in Drosophila virilis, we determined that four‐hr and longer exposures to 30 ± 2 ppm ozone were lethal on or before day 25 postexpo‐sure. Accordingly, we used a three‐hr ozone exposure to investigate dominant lethals induced at specific spermatogenic stages. Ozone increased the percentage of dominant lethals in the stages of spermatogenesis which were investigated. Under the conditions of this experiment, the sperm‐sperm bundle stage showed the greatest percentage of dominant lethals induced by ozone. Meiotic cells were the least sensitive to ozone mutagenicity. The induction of dominant lethals is discussed on the basis of chemical reactions from the molecular decomposition of water by radiations and/or ozone. Alternative explanations are presented due to the definition of induced dominant lethals and to associated modifications from ozone exposure.
Detection of DNA damage in primary cultures of rat hepatocytes following in vivo and in vitro exposure to genotoxic agents
Authors: Bermudez E. , Mirsalis J. C. , Eales H. C.
Published: February 2007

A simplified method for the quantitation of DNA damage in nonlabeled hepatocytes, using a fluorometric technique for the quantitation of DNA in conjunction with a modification of the alkaline elution technique of Kohn et al [1976], following chemical treatment in vitro and in vivo, is described. Freshly isolated hepatocytes were treated in vitro with 2‐acetylaminofluorene, aflatoxin B1, and dimethylnitrosamine, then examined for DNA damage. Exposure to each of these compounds resulted in DNA damage. Hepatocytes isolated from rats treated with the hepatocarcinogens 2‐acetylaminofluorene, benzidine, azoxymethane, dimethylhydrazine, dimethylnitrosamine, and diethylnitrosamine sustained DNA damage as evidenced by increased alkaline elution. DNA damage in hepatocytes was also observed as a result of treatment with methylmethanesulfonate and azaserine. The hepatotoxin carbon tetrachloride did not induce DNA damage in hepatocytes isolated from treated animals. A comparison of the induction of DNA damage and of unscheduled DNA synthesis in hepatocytes from the same animals revealed that in most cases the extent of elution of DNA from filters was proportional to the induction of DNA repair.
Mutagenicity test of extracts of airborne dust from the municipal incinerator of trieste
Authors: Pani B. , Laureni U. , Babudri N. , Collareta A. , Venturini S. , Ferri R. , Carrozzi M. , Burlini F. , Monti‐Bragadin C.
Published: February 2007

The composition of the effluents from incineration plants has been studied by several authors, and some chemical compounds have been identified as hazardous to the health of the people living in the environs of such plants. On the other hand, very little is known about the chemical risks for the people working inside the incineration plants. In the present paper, an evaluation of these risks has been attempted by testing for the mutagenic activity of the extracts of airborne particulates collected inside the working area of the Municipal Incinerator of Trieste. Most samples of dust were proved to be mutagenic by the Ames test, indicating that the environment is heavily polluted with incompletely burnt materials. In fact, when a sample of settled dust was heated at high temperatures, its mutagenic activity disappeared. In addition, samples of solid residues collected at the end of the combustion process showed only weak, if any, mutagenic response.
A comparative cytogenetic study on cases of induced abortions in tcdd‐exposed and nonexposed women
Authors: Tenchini M. L. , Crimaudo C. , Pacchetti G. , Mottura A. , Agosti S. , de Carli L.
Published: February 2007

In order to evaluate the cytogenetic findings previously obtained on induced abortions in women exposed to 2,3,7,8 tetrachlorodibenzo‐p‐Dioxim (TCDD) after the Seveso accident, chromosome analyses were carried out on a comparable control sample. The frequencies of aberrant cells, the relative proportions of individual types of chromosome aberration, the average number of lesions per damaged cell, and the frequencies of polyploids do not differ significantly in maternal blood and placenta in the two samples. A highly significant increase in the frequencies of aberrant cells and in the average number of aberrations per damaged cell was found in the fetal tissues in the group of exposed pregnancies. A noticeable feature of the data on the frequencies of cells with aberrations is the marked variability among individuals within tissues and within samples. On the basis of these results, the authors point to the need to continue cytogenetic investigations on interrupted pregnancies in TCDD‐exposed and nonexposed women.
Some findings on mutagenicity in airborne particulate pollutants
Authors: Tokiwa Hiroshi , Kitamori Shigeji , Horikawa Kazumi , Nakagawa Reiko
Published: February 2007

Mutagenic activity in particulate airborne pollutants in several samples collected in a wide variety of industrial, residential, and small‐scale factory districts over the past seven years was detected by the Ames test. The particulate air samples that were not contaminated with several chemicals such as NO (<0.001 ppm), NO2 (<0.001 ppm), and SO2 (<0.001 ppm) showed only low mutagenic activity (1 revenant /m ) when they were tested with Salmonella typhimurium strain TA98 in the presence of S9 mix. However, most of the samples polluted by particulate matters showed high mutagenicity, with responses varying from 2.4 to 445 revertants per m3: 67 samples from an industrial area induced an average of 44 revertants per m3; 60 from a residential area, 16.2; and 10 from a small‐scale factory area, 72.1. For assessing the mutagenic potential of the pollution in the atmosphere, the frequency of mutation determined with strain TA98 in the presence of S9 mix was used to divide the samples tentatively into five groups (A‐E) on the basis of the normal logarithmic distribution curve of 137 samples. Air samples belonging to group A gave less than 2.3 revenants per m3 of air (1.12 ± 0.12, no pollution); those of group B gave a range of 2.4 to 8.6 (5.93 ± 1.91, slight pollution); those of group C gave a range of 8.7 to 30.2 (16.0 ± 5.36, moderate pollution); those of group D gave a range of 30.3 to 115 (56.7 ± 20.1, considerable pollution); and those of group E gave more than 116 (234 ± 119, heavy pollution). Of the 137 samples tested, 6 samples (4.4%) were assigned to group A, 38 (27.7%) to group B, 52 (38.0%) to group C, 34 (24.8%) to group D, and 7 (5.1%) to group E. Furthermore, the samples in an industrial area were classified in the order of group C (35.8%), group B (26.9%), group D (22.4%), group E (8.96%), and group A (5.97%), and those in a residential area in the order of group C (46.7%), group B (33.3%), group D (18.3%), and group A (1.67%).
Tradescantia‐micronucleus (trad‐MCN) test on the genotoxicity of malathion
Authors: Ma Te‐Hsiu , Anderson Van A. , Harris Mary M. , Bare Janie L.
Published: February 2007

The Tradescantia‐Micronucleus (Trad‐MCN) bioassay was utilized to determine the genotoxicity of Malathion, a common insecticide. Four different treatment procedures were applied: a) absorption of Malathion/water mixture (with or without DMSO and/or S‐9) through the stem, b) spraying a Malathion/water mixture onto the plant cuttings in enclosed chambers, c) spraying a Malathion/ water mixture on an open population of plants in the greenhouse, and d) absorption of Malathion fumes through the leaves and buds. Most treatments were administered for 6 hr, followed by a 24‐hr recovery time. Slides were prepared from the samples and scored for micronucleus (MCN) frequencies. Results of 16 experiments indicated that the genotoxicity of liquid Malathion absorbed through the stem was very low and often masked by high toxicity, causing dead cells in the stem, leaves, and meiocytes. Malathion spray at the dosage of 0.435% in an enclosed chamber or on an open population of plants yielded negative responses. Malathion fumes at dosages of 0.15–0.25% induced signficantly higher (0.05) MCN frequencies above the controls and altered the nuclear structure to form unequal sized nuclei and multiple breaks in each of the four cells of a tetrads. It also caused degeneration of nuclei, “protrusions on nuclei,” and inhibition of cell growth. Higher dosages (above 0.25%) were toxic.
Chromosome aberrations and sister chromatid exchanges in styrene‐exposed workers with reference to their smoking habits
Authors: Watanabe Toshiaki , Endo Akira , Kumai Miho , Ikeda Masayuki
Published: February 2007

The incidences of chromosome aberrations and the frequencies of sister chromatid exchanges (SCE) were investigated in cultured lymphocytes of 18 styrene‐exposed workers in comparison with six controls. There was a marginal increase in the incidence of structural chromosomal aberrations in first‐division metaphases in the styrene‐exposed workers, as compared with the nonexposed controls. However, there was no difference in SCE frequencies. When each group was divided into smokers and nonsmokers, styrene‐exposed smokers tended to have higher SCE frequencies than styrene‐exposed nonsmokers. Furthermore, cell proliferation was inhibited in styrene‐exposed workers (both smokers and nonsmokers) and control smokers.
The use of neurospora in the evaluation of the mutagenic activity of environmental chemicals
Authors: de Serres Frederick J.
Published: February 2007

The utility of various assay systems developed with Neurospora for hazard identification, hazard evaluation, and risk estimation is discussed. The use of the ad‐3 test system in a two‐component heterokaryon is discussed in relation to its utility for hazard evaluation and risk estimation. This ad‐3 assay provides information on those specific locus mutations that arise by multilocus deletions with regard to both frequency and relative size. Information on this class of specific locus mutations is particularly important because, as shown in Drosophila, mouse, and man, this type of damage can have immediate and undesirable effects on F1 progeny.
Effect of bacterial concentration on reversions induced in salmonella typhimurium TA1538 by N‐hydroxy‐2‐acetylaminofluorene
Authors: White G. L. , Beranek D. T. , Heflich R. H.
Published: February 2007

Reversions induced by N‐hydroxy‐2‐acetylaminofluorene (N‐OH‐AAF) were measured in the Salmonella/microsome quantitative plate assay using various concentrations of Salmonella typhimurium strain TA 1538. The number of induced revertants increased with an increasing number of bacteria/plate, but the variation in reversion frequency was not as great as the variation in bacterial concentration. The effects of bacterial concentration on reversion fixation, phenotypic expression, selection of his+ revertants, and the interaction of the mutagen with bacterial DNA were examined. Suspension cultures of TA 1538 were exposed to N‐OHAAF and various dilutions were prepared and assayed for revertants/108 bacteria. Reversion frequencies were very dependent on bacterial concentration between approximately 0.2 × 108 and 2 × 108 bacteria/plate. Revertants/108 TA 1538 were reduced above about 2 × 108 bacteria/plate, indicating that culture conditions limited reversion fixation, expression and/or selection at these concentrations. The number of spontaneous revertants/plate determined both from bacteria exposed to dimethyl sulfoxide in suspension culture and in the Salmonella/microsome assay were not greatly affected by bacterial concentration. To study the effect of bacterial concentration on the interaction of the mutagen with bacterial DNA, various concentrations of TA 1538 were exposed to the same dose of N‐OH‐AAF. Both revertants/108 TA 1538 and DNA adducts varied inversely with bacterial concentration. The effect of bacterial concentration on both reversion fixation and/or expression and on mutagen binding to DNA may influence reversion frequencies in the Salmonella/microsome assay.
Evaluation of di‐(2‐ethylhexyl)phthalate and its major metabolites in the ames test and L5178Y mouse lymphoma mutagenicity assay
Authors: Kirby P. E. , Pizzarello R. F. , Lawlor T. E. , Haworth S. R. , Hodgson J. R.
Published: February 2007

Di‐(2‐ethylhexyl)phthalate (DEHP) and its two major metabolites, mono‐(2‐ethylhexyl)phthalate (MEHP) and 2‐ethylhexanol (EH), were tested for genetic activity in both the Salmonella/mammalian microsome mutagenicity (Ames) assay and the L5178Y TK+/— mouse lymphoma cell mutagenicity assay. All chemicals were tested in both the presence and absence of Aroclor‐induced liver microsomes prepared from male Sprague‐Dawley rats. Dose levels for both assays were selected from preliminary toxicity studies for each chemical. Neither DEHP, MEHP, nor EH exhibited any significant mutagenic activity in strains TA‐98, TA‐100, TA‐1535, TA‐1537, and TA‐1538 in the Ames test or when tested in the L5178Y TK+/ — mouse lymphoma cell mutagenicity assay.
Methylmercury effects on Syrian hamster metaphase II oocyte chromosomes
Authors: Mailhes John B.
Published: February 2007

Methylmercury (MM) denatures DNA and can induce chromosomal aberrations. In addition, it destroys microtubules and increases the incidence of aneuploidy and mitotic arrest. Although MM is distributed to gonads, data relating the cytogenetic effects of MM on mammalian germ cells in vivo have not been found. To determine whether MM increases the incidence of cytogenetic damage in oocytes, Syrian hamsters were divided into three groups: (1) negative controls; (2) positive controls, 0.25 mg Trenimon (T)/kg; and (3) 10 mg methylmercury chloride (MMC)/kg. Superovulation was utilized and metaphase II oocytes analyzed for numerical and structural chromosome aberrations. A highly significant (P = .015, Fisher's exact test) difference in the incidence of hyperploid (N = 23) oocytes was obtained between negative controls (0/150) and the MMC group (6/ 150). The incidence of hypoploid (N = 21) oocytes in negative controls and the MMC group was 12/150 and 21/150, respectively (P = .069). Structural aberrations were not observed. Of 281 oocytes analyzed in the T group, 42.7% had structural aberrations. These results primarily indicate that MMC increases the incidence of hyperploidy and not structural aberrations.
Dinitro and mononitrobenzo(ghi)perylenes and mononitrocoronene are highly mutagenic in the ames salmonella assay
Authors: Vance William A. , Chan Raymond
Published: February 2007

Benzo(ghi)perylene (B(ghi))Per, (191–24–2)) and coronene (Cor, (191–07–1)) are major constituents of the polycyclic aromatic hydrocarbons (PAH) found in automobile exhaust and polluted air [eg, Grimmer et al, 1981]. Nitration of these PAH by NO2 and traces of HNO3, which are also formed in automobile exhaust, seems highly probable. To identify the presence of these nitroarenes in environmental samples and to examine their mutagenic potencies we synthesized and characterized nitro derivatives of both PAH. 5‐NO2B(ghi)Per (81316‐87‐2) and l‐NO2Cor (81316‐84‐9) produced 405 and 340 revertants/nmole respectively in TA98 in the presence of 0.6 mg of microsomal enzymes (S‐9) per plate in the Ames test. 5,8‐diNO2B(ghi)Per (83292‐25‐5) and 5,10‐diNO2B(ghi)Per (83292‐26‐6) produced 21,500 and 4,000 revertants/nmole in TA98 without microsomal activation. Mutagenicity for the dinitrobenzo(ghi)perylenes was also high in TA98NR and TA97 but was reduced by 97% in TA98‐1,8DNP. There is close similarity in the orientation and distances between reactive sites (nitrenium ion and carbocation) on the dinitrobenzo(ghi)perylenes and 1,6‐dinitropyrene (42397‐64‐8) and 1.8‐dinitropyrene (42397‐65‐9).
Comparison of the mutagenic responses of 12 anticancer drugs at the hypoxanthine‐guanine phosphoribosyl transferase and adenosine kinase loci in chinese hamster ovary cells
Authors: Singh Bhag , Gupta Radhey S.
Published: February 2007

The mutagenic responses of 12 anticancer drugs—lomustine, dacarbazine, mitomycin C, chlorambucil, cis‐diamminedichloroplatinum (II), busulfan, ellipticine, daunomycin, adriamycin, VM‐26, VP16‐213, and bleomycin—in Chinese hamster ovary (CHO) cells at two independent genetic loci which affect purine salvage pathway enzymes, hypoxanthine‐guanine phosphoribosyl transferase (HGPRT) and adenosine kinase (AK) have been compared within the same experiments. The cellular mutants which lack either HGPRT (HGPRT− mutants) or AK (AK−mutants) activity can be directly selected in CHO cells using 6‐thioguanine and 6‐methyl mercaptopurineriboside (6‐MeMPR) respectively, and optimal conditions for their selection have been described. Results of our studies show that all of the above drugs caused a concentration‐dependent increase in the frequencies of both 6‐thioguanine‐ and 6‐MeMPR‐resistant mutants. However, for a number of these drugs, namely adriamycin, daunomycin, bleomycin, and dacarbazine, which are only weakly mutagenic at the HGPRT locus, a relatively strong and clear mutagenic response was observed at the AK locus. In contrast, VM‐26 showed a more pronounced effect at the HGPRT locus. For the remaining compounds, the mutagenic responses of the two loci (as indicated by the slopes of the dose‐response curves) were comparable. The observed increase in the frequency of AK− mutants after treatment with various drugs, many of which predominantly induce frameshift and chromosome‐breakage type of genetic lesions, suggests that like the HGPRT locus the AK locus is also capable of detecting all the different types of genetic lesions. The favorable response of the AK locus as compared to that of HGPRT locus in these studies indicates that the selection system of AK− mutants should provide a very useful genetic marker for mutagenesis studies in CHO cells.
Distribution of extractable mutagenic activity in steel foundry air particulates of different sizes
Authors: McCalla D. R. , Kaiser‐Farrell C. , Kerr A. , Lockington J. N. , Gibson E. S.
Published: February 2007

An Andersen 2000 sampler was used to collect different size classes of airborne particulate matter in a large steel foundry. When extracts of these particles were assayed for mutagenicity using the Ames Salmonella/S‐9 assay, much of the mutagenic activity was found in particles of respirable size. Furthermore, mutagens requiring activation were distributed among the various size classes roughly in proportion to the total surface area of the particles with the smallest class (<1.1 μm) containing by far the largest amount of mutagenic activity. The distribution of direct‐acting mutagenic activity was more variable and in some samples the bulk of this activity was in the largest size class (>7.0 μm).
Germ cell comparative drosophila mutagenesis: Sensitivity and mutation pattern in chemically treated stem cells
Authors: Abrahamson S. , Houtchens K. , Jia X. Li , Foureman P.
Published: February 2007

Mutagenesis studies on Drosophila oogonial cells with methylnitrosourea, dimethylnitrosamine, and diethylnitrosamine revealed unexpectedly high rates of sex‐linked recessive lethals relative to other male and female germ cell stages. Indeed, the oogonial mutation rates with chemicals are higher than with massive X‐ray or neutron exposures of oogonia. Analysis of the distribution of lethals per treated female suggests most of the mutations recovered are of independent origin, with very small levels of clustering of identical mutations. In the male stem cell population (spermatogonia) on the other hand, the distribution of lethals is primarily nonrandom and highly clustered. The nature of the mutational endpoint and the different pattern of germ cell development in the two sexes are the probable causes of this difference.

The oogonial sensitivity to chemical mutagens may have important bearing on strategies for assessing human hazard.
Correlation between mixed‐function oxidase enzyme induction and aflatoxin B1‐induced unscheduled DNA synthesis in the chick embryo, in vivo
Authors: Hamilton Joshua W. , Bloom Stephen E.
Published: February 2007

The unscheduled DNA synthesis (UDS) technique has been adapted for use in the chick embryo, in vivo, to determine the relationship between induction of the mixed‐function oxidase (MFO) enzyme system and genetic damage from an indirect‐acting mutagen‐carcinogen. Embryos were injected at 6 days of incubation (DI) with either phenobarbital (PB), a specific inducer of P‐450‐associated enzyme activities, or 3,4,3′,4′‐tetrachlorobiphenyl (TCB), a specific inducer of P1‐450‐associated enzyme activities. Aflatoxin B1 (AFB1) was injected 24 hr later (7 DI), followed by a 5‐hr continuous 3H‐thymidine exposure. The livers were removed, prepared for autoradiography, and hepatocytes were scored for an increase in grains/nucleus, indicative of UDS. Aflatoxin B1 caused a dose‐related increase in UDS in all control and induction groups. Phenobarbital‐induced embryos had an increased UDS response while TCB‐induced embryos had a decreased UDS response, relative to noninduced embryos, for each dosage of AFB1. This suggests that the genotoxicity of an indirect‐acting mutagen‐carcinogen can be either increased or decreased, in vivo, depending on the inducer used. The chick embryo provides an excellent system for studying the effect of MFO induction on the genotoxicity of promutagen‐carcinogens in a developing system.
The genetic toxicology of metal compounds: I. Induction of λ prophage in E coli WP2S(λ)
Authors: Rossman T. G. , Molina M. , Meyer L. W.
Published: February 2007

A number of metal compounds have been shown to be human carcinogens. Others, while not proven human carcinogens, are able to cause tumors in laboratory animals. Short‐term bacterial assays for genotoxic effects have not been successful in predicting the carcinogenicity of metal compounds. We report here the ability of some metal compounds to cause the induction of λ prophage in E coli WP2S(λ). By far the strongest inducing ability was observed with K2CrO4, followed by Pb(N03)2 > MnCl2 > Ni(OOCCH3)2 > CrCl2 > NaWO4 > Na2MoO4 > KMnO4. With the exception of chromate, long‐term exposures in a narrow, subtoxic dose range were required in order to demonstrate phage induction. A new microtiter assay for λ prophage induction, which incorporates these features, is described. This system also was able to detect very small amounts of organic carcinogens.
Contribution of wood combustion to indoor air pollution as measured by mutagenicity in Salmonella and polycyclic aromatic hydrocarbon concentration
Authors: Alfheim Ingrid , Ramdahl Thomas
Published: February 2007

Samples of airborne particles have been collected in the same room when the room was heated by electricity and when heating was done by woodburning. These samples were compared with respect to mutagenic activity and concentration of polycyclic aromatic hydrocarbons (PAH). The effects of the various heating conditions were examined in the presence and absence of tobacco smoking.

Whereas wood heating in an “airtight” stove was found to cause only minor changes in the concentration of PAH and no measurable increase of mutagenic activity of the indoor air, both these parameters increased considerably when wood was burned in an open fireplace, yielding PAH concentrations comparable to those of ambient urban air. Relatively high concentrations of moderately polar polycyclic aromatic hydrocarbon derivatives were also found in the indoor air when wood was burned in an open fireplace. Woodburning in the closed stove did, however, result in increased concentrations of mutagenic compounds and PAH on particles sampled in the vicinity of the house.

The effects of wood burning in an open fireplace on the mutagenic activity of indoor air could still be considered moderate when compared to those resulting from tobacco smoking in the room. The extracts of particles collected when moderate smoking occurred were several times more mutagenic than samples from urban air collected close to streets with heavy traffic when measured in the Salmonella assay with strain TA98 with metabolic activation.
Chemical mutagenesis testing in Drosophila: I. Comparison of positive and negative control data for sex‐linked recessive lethal mutations and reciprocal translocations in three laboratories
Authors: Woodruff R. C. , Mason J. M. , Valencia R. , Zimmering S.
Published: February 2007

As part of the validation phase of the Drosophila melanogaster segment of the National Toxicology Program, a comparison has been made of positive and negative controls for sex‐linked recessive lethal mutations and reciprocal translocations from three laboratories. This comparison involves approximately 700,000 spontaneous recessive lethal mutation tests, 70,000 spontaneous translocation tests, and screens for genetic damage induced by N‐nitrosodimethylamine and β‐propiolactone. Spontaneous frequencies for lethal mutations and translocations were homogeneous in the laboratories regardless of solvent or broods sampled. Inhomogeneity was observed in induced frequencies among laboratories, but the variation was no greater than that found within a laboratory.
Effects of mutagenized X chromosomes of Drosophila melanogaster on viability and fitness in males
Authors: Simmons Michael J. , Raymond John D. , Anklesaria Farhad X. , Hawkins Elizabeth T. , Johnson Nancy A. , Cooper Jeffrey S. , Cox Nancy M.
Published: February 2007

Drosophila melanogaster males were treated with different doses of X‐rays or ethyl methanesulfonate (EMS) and mated so that mutagenized X chromosomes could be recovered and tested for lethal mutations and for less drastic mutations affecting viability and other aspects of fitness. The lethals were detected in standard X‐linked lethal tests. The less drastic mutations were detected in one generation tests for effects on viability and in multigeneration tests for effects on overall fitness. The Poisson‐corrected frequencies of the lethal mutations increased linearly with dose for both X‐rays and EMS. Based on the data, 1 Krad X‐rays given acutely induces the same number of lethals as 0.55 mM EMS administered by feeding. For some of the X‐ray and EMS doses, the mutagenized chromosomes that were nonlethal reduced the viability of their carriers by a small amount, but there was no discemable dose‐effect relationship. However in every case where a viability effect was seen, the percentage reduction was less than the corresponding frequency of lethals. All the groups of mutagenized nonlethal chromosomes reduced overall fitness by a significant percentage. Wherever a meaningful comparison was possible, this reduction was 2–3 times the reduction in viability, but, as in the viability data, no dose‐effect relationship was discernable.
Comparison of methods for detecting mitomycin C‐ and ethyl nitrosourea‐induced germ cell damage in mice: Sperm enzyme activities, sperm motility, testis weight
Authors: Ficsor Gyula , Oldford Gregory M. , Loughlin Karen R. , Panda Brahma B. , Dubien Janice L. , Ginsberg Leonard C.
Published: February 2007

Testes weights, sperm motility and enzyme activities in single sperm were compared with respect to their ability to detect either developmental or mutational damage to germ cells. Male mice were injected i.p. with 2.5 mg/kg mitomycin C (MC) or 50 or 100 mg/kg ethylnitrosourea (ENU) or saline and were then killed at times such that sperm derived from treated vas sperm (SZ), spermatids (ST), preleptotene‐late‐spermatogonial cells (PLSG), spermatogonial cells (SG), or spermatogonial stem cells (SGS) could be evaluated.

Testis weights decreased significantly as early as 1 wk after treatment, with the greatest decrease reached 3–4 wk after treatment, followed by recovery to normal levels 10–15 wk after treatment. We conclude that testis weight, which is easily obtained, is a sensitive indicator of germ cell damage by these agents.

Sperm from each animal were evaluated for sperm motility, acrosin activity, succinic dehydrogenase (SDH) activity with or without the competitive inhibitor malonate or after exposure to 60°C for 10 min. The latter two assays were to detect sperm enzymes resistant to the inhibitor or heat. The presence of the acrosin protein was also detected immunologically. Sperm motility decreased most from treatment of PLSG and SG. After MC or ENU treatment, the greatest loss of acrosin activity and of the acrosin protein was also noted in sperm derived from treated PLSG and SG. MC and ENU failed to induce SDH activity in single sperm resistant to 60°C heat inhibition or to inhibition by malonate. Of the sperm assays, acrosin activity proved to be the most sensitive indicator of germ cell damage and was the simplest to measure.
Induction of unscheduled DNA synthesis in primary cultures of rat pancreatic cells following in vivo and in vitro treatment with genotoxic agents
Authors: Steinmetz Karen L. , Mirsalis Jon C.
Published: February 2007

The pancreas is a key target tissue in human and animal carcinogenesis, yet few short‐term test systems measure genotoxicity in pancreatic cells. A method has been developed for the measurement of DNA repair as unscheduled DNA synthesis (UDS) in primary cultures of rat pancreatic cells (PRP) following in vitro or in vivo exposures to chemicals. PRP were isolated from female Sprague‐Dawley (SD) or male Fischer‐344 rats by mincing the pancreas in a collagenase solution followed by digestion in dispase. For in vitro exposures, PRP were incubated with 3H‐thymidine (3H‐TdR) in the presence of genotoxic agents for 18–22 hr. For in vivo exposures, male Fischer‐344 rats were treated with genotoxic agents 2 hr prior to sacrifice of the animals, and cells were incubated with 3H‐TdR. UDS was measured by quantitative autoradiography as net grains/nucleus (NG). Solvent controls ranged from −1.0 to −2.8 NG. Cells isolated from female SD rats and treated in vitro with methylmethane sulfonate (MMS), ethylmethane sulfonate (EMS), N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG), and the pancreatic carcinogen azaserine all yielded over 4.0 NG. Cells treated in vitro with the hepatocarcinogens 2‐acetylaminofluorene (2‐AAF) and dimethylnitrosamine (DMN) and with the multisite carcinogen benzo[a] pyrene (B[a]P) yielded between −1.0 and −3.3 NG. These results are consistent with the lack of carcinogenic activity of 2‐AAF, DMN, and B[a]P in the pancreas and indicate that pancreatic cells are incapable of metabolizing these compounds to genotoxic forms. In vivo treatment with MMS at 100 mg/kg yielded 1.9 NG and with azaserine at 100 mg/kg yielded 8.2 NG. This method should be useful in detecting agents that are genotoxic to the pancreas.
Mutagenicity screening of foods. II. Results with fruits and vegetables
Authors: Stoltz D. R. , Stavric B. , Stapley R. , Klassen R. , Bendall R. , Krewski D.
Published: February 2007

A survey of the mutagenic potential of a wide variety of food products has been initiated with results for 28 different beverages reported previously [Stoltz et al, 1982b]. Here, results for samples of 46 widely consumed fruits and vegetables from six general categories are given. Each sample was concentrated and fractionated by polarity and solubility to give five fractions, each of which was assayed for mutagenic potential withSalmonella typhimuriumTA98 and TA100. Although statistical analysis of the data resulted in positive findings for 22 fruit and vegetable samples, only six products (grapes, onions, peaches, raisins, raspberries, strawberries) demonstrated potent mutagenic activity.