bluuebunny/crossref_metadata_2025 huggingface dataset:
The mutagenic effect of cis‐diamminedichloroplatinum (II) and its degradation products in the ames microbial assay
Authors: Peer Richard L. , Litz Deborah A.
Published: February 2007

Cis‐Diamminedichloroplatinum (II), an antitumor compound which exhibits mutagenic activity, and its degradation products platin B salt, magnus red, and magnus red anion salt were tested in the Ames microbial mutagenicity assay. The purpose of this investigation was to determine if the positive mutagenic response of the platinum compound could be due to, or enhanced by, the presence of degradation products. Results indicate that platinum degradation complexes are weak mutagens which are capable of inducing both base pair and frameshift‐type mutations.
Sister chromatid exchange induction and cell cycle inhibition by aniline and its metabolites in human fibroblasts
Authors: Wilmer James L. , Kligerman Andrew D. , Erexson Gregory L.
Published: February 2007

Sister chromatid exchange (SCE) and cell cycle analyses in human fibroblasts were used to ascertain the relative genotoxicity and cytotoxicity of aniline and its metabolites. Fibroblasts were allowed to attach to plastic petri dishes for 4 hr and exposed in serum‐free medium for 2 hr to the following: aniline HCl (0.05–10.0 mM), acetanilide (0.1–10.0 mM), o‐hydroxyacetanilide (0.01–2.0 mM), p‐hydroxyacetanilide (0.1–10.0 mM), o‐aminophenol (0.01–0.3 mM), p‐aminophenol (0.005–0.2 mM), N‐phenylhydroxylamine (0.001–0.5 mM). Triethylenemelamine (TEM; 0.25 and 0.49 μM) was used as a positive control. The treatment medium was replaced with complete medium containing 5‐bromo‐deoxyuridine (10 μM), and cells were allowed to grow for 48 hr with Colcemid present for the final 4.5 hr. Cell cycle analyses (percentage of cells in first, second, or third division) revealed that p‐hydroxyacetanilide (10mM), p‐aminophenol (≥0.1 mM), o‐aminophenol (≥0.1 mM), N‐phenylhydroxylamine (≥ mM), and TEM (0.49 μM) inhibited cell proliferation. Cell death was seen at doses of 0.5 mM N‐phenylhydroxylamine, 0.2 mM p‐aminophenol, and 0.3 mM o‐aminophenol. Significant increases (P0.05) in SCE frequencies were found with aniline HCl, o‐aminophenol, N‐phenylhydroxylamine, and TEM. On an SCE/mmole basis at the highest concentrations examined, o‐aminophenol was 270 times more potent than aniline in inducing SCE, whereas TEM was about 390 times more potent than o‐aminophenol. Furthermore, fibroblasts treated with o‐aminophenol responded in a dose‐dependent fashion and exhibited a 2‐fold increase in SCE frequency. N‐phenylhydroxylamine induced a less clear‐cut, dose‐related increase in SCE frequency with a 1.4‐fold elevation. Only marginal increases in SCE were observed with aniline at the highest doses. Using these data, we propose that aniline may exert its tumorigenic potential in rats through the production of both genotoxic and cytotoxic metabolites.
Cytogenetic effects of two antimonial antibilharzial drugs: Tartar emetic and bilharcid
Authors: Nahas Soheir El , Temtamy Samia A. , De Hondt H. A.
Published: February 2007

The effects of tartar emetic and bilharcid, two antimonial antibilharzial drugs, on the chromosomes of laboratory rats are studied. The drugs were administered intraperitoneally in three doses—clinical, intermediate, and maximum tolerated — both acutely (6, 24, and 48 hours) and subacutely. The two drugs produced the same types of chromosomal aberrations with tartar emetic, inducing a higher rate of incidence. No significant differences in the number of cells with chromosomal aberrations were generally observed among the 6, 24, and 48 hours of the acute treatment with both tartar emetic and bilharcid. The dose‐response relationship was examined for both the acute and the subacute treatments. Whereas the acute treatment of tartar emetic showed a dose‐dependent linear increase in the number of cells with chromosomal aberrations, the subacute treatment of tartar emetic and the acute and subacute treatments of bilharcid displayed their maximum effects at an intermediate dose.
Characterization of sister chromatid exchange induction by hydrogen peroxide
Authors: Speit G. , Vogel W. , Wolf M.
Published: February 2007

Hydrogen peroxide (H2O2) induces SCEs in V‐79 Chinese hamster cells. The incorporation of BrdUrd sensitizes the cells to the action of H2O2, but damage leading to the formation of SCEs can also be induced in DNA not substitued with BrdUrd. Catalase leads to a complete reduction of the SCE‐producing as well as the toxic effect. The amino acid L‐cysteine does not reduce the H2O2‐induced SCE‐frequencies. The results yield information about the relevance of SCE investigations in vitro for the determination of DNA‐damaging substances and about the effects of antimutagenic SH‐compounds.
Variations among species and cell types in the effects of caffeine on mutagen‐induced cytotoxicity and postreplication repair of DNA
Authors: Sivak Andrew , Rudenko Larisa , Teague Linda Gaudio
Published: February 2007

The influence of caffeine on cytotoxicity and postreplication repair of DNA was examined following exposure of several cell types to physical and chemical agents known to damage DNA. The cell types used in this study were normal human fibroblasts (HS‐WP), human xeroderma pigmentosum fibroblasts (SGL), Chinese hamster V79 cells, mouse BALB/c‐3T3 cells, and secondary Syrian hamster embryo cells. The DNA damaging agents were ultraviolet light (UV), N‐2‐acetoxyfluorenylacetamide (AFAA), nitroquinoline‐N‐oxide (NQO) and N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG). Induction of cytotoxicity in Chinese hamster V79 cells due to ultraviolet light or AFAA exposure was enhanced by caffeine at a concentration of 1.0 mM in the culture medium, but not at 0.2 or 0.05 mM. Caffeine also inhibited postreplication repair in these cells at the same concentrations. In contrast, postreplication repair was not affected by caffeine at concentrations up to 1.0 mM in normal human fibroblasts (HS‐WP), human xeroderma pigmentosum fibroblasts (SGL), secondary Syrian hamster embryo cells, and mouse BALB/c‐3T3 cells following treatment with ultraviolet light, AFAA, NQO, or MNNG. Cytotoxicity in BALB/c‐3T3 cells following exposure to ultraviolet light or AFAA was enhanced in the presence of caffeine at 1.0 or 0.2 mM, although these concentrations of caffeine had no effect on postreplication repair in these cells. The inhibitory effect of caffeine on postreplication repair was found only in Chinese hamster V79 cells among the five cell types used in this study. Both normal and xeroderma pigmentosum human cells repaired mutagen‐induced DNA damage equally well in the absence or presence of caffeine at concentrations of 1.0 mM or less.
Ph stability of some mutagens produced by aqueous chlorination of organic compounds
Authors: Nazar Mark A. , Rapson W. Howard
Published: February 2007

Aqueous chlorination of many organic substances has been found to produce substantial mutagenicity in Salmonella typhimurium TA100. An effective way to decrease such mutagenicity is to raise the pH of the solutions to neutrality or higher. The effect of pH on the mutagenicity of the filtrate from the chlorination of unbleached kraft wood pulp and of certain mutagens found in such filtrates has been investigated. The decay of mutagenicity of the known mutagens has been shown to proceed by cleavage of organically bound chlorine by hydroxide ion. Caution is recommended with respect to the practice of raising the pH of solutions for mutagenesis assays.
Mutagenicity screening of foods I. Results with beverages
Authors: Stoltz D. R. , Stavric B. , Krewski D. , Klassen R. , Bendall R. , Junkins B.
Published: February 2007

Following a number of recent reports on the presence of mutagens in certain foods, a general survey of the mutagenic potential of a wide variety of food products has been initiated. Here, results for samples of 28 widely consumed beverages from 13 general categories are reported. Each sample was concentrated and fractionated by polarity and solubility to give up to seven fractions, each of which was assayed for mutagenic potential with Salmonella typhimurium TA98 and TA100 ± fortified liver homogenate. Fractions showing evidence of either mutagenicity or toxicity were retested at the same and lower concentrations. The utility of the fractionation procedure and the sensitivity of the screening strategy were established by assaying six beverages spiked with known mutagens prior to fractionation. Statistical analysis of the data resulted in positive findings for seven beverages, although confirmation of these results through analysis of a second sample was obtained only for red wine, grape juice, and instant coffee. The remaining 21 beverages showed no strong evidence of mutagenic activity. For those foods for which the variation among replicate plates was largest, the false‐positive rate for the two‐stage screening procedure employed was estimated to be less than 1% while the false‐negative rate for a beverage inducing a threefold increase in the background mutation rate was conservatively estimated to be limited to 14%.
The longevity of chemically induced sister chromatid exchanges in chinese hamster ovary cells
Authors: Muscarella Donna E. , Bloom Stephen E.
Published: February 2007

The persistence of the lesions leading to sister chromatid exchanges (SCEs) following acute exposure of Chinese hamster ovary (CHO) cells to direct‐acting chemical mutagens was measured. The results revealed that these lesions (and consequently SCEs) are rapidly eliminated from cells. SCE levels fell to near control values by the third or fourth day (six and eight cell cycles, respectively) following exposure of CHO cells to quinacrine mustard (QM) and mitomycin C (MMC). In contrast, cells exposed to methyl methanesulfonate (MMS) showed a small but significant increase in SCE level over control up to and including the fifth day following exposure (approximately ten cell cycles), suggesting that the behavior of these lesions in cells is influenced, at least in part, by the mechanism by which a specific agent interacts with DNA. The possibility that the decline in SCE level was due to the loss of cell populations with high numbers of exchanges was eliminated by the assessment of cloning efficiencies of treated and control cultures.
The solvent dimethylsulfoxide (DMSO) does not induce aneuploidy in oocytes of drosophila melanogaster
Authors: Traut H.
Published: February 2007

Both with a conventional method and with the “aneuploidy pattern method” we tested whether the solvent dimethylsulfoxide (DMSO) is able to induce aneuploidy (numerical chromosome aberrations) in oocytes of Drosophila melanogaster. DMSO was fed as a 2% solution to Drosophila females. No evidence for a mutagenic activity was obtained. This finding and the negative results reported by other authors for other types of mutation in Drosophila show that DMSO can be used as a solvent for chemical agents in mutagenicity screening in Drosophila melanogaster.
Chromosome damage and SCE induced by the cytostatic factor homo‐aza‐steroidal ester of P‐bis (2‐chloro‐ethyl) amino phenyl acetic acid in CHO cells in culture
Authors: Athanasiou Kyriacos , Demopoulos Nicos A. , Catsoulacos Panayiotis
Published: February 2007

The cytogenetic effects of homo‐aza‐steroidal ester (ASE) on Chinese hamster ovary (CHO) cells in vitro are reported. It was found that treatment of cells with a dose as low as 0.025 μg/ml of ASE causes a significant number of abnormal metaphases containing mostly chromatid‐type aberrations. Similarly, significant frequencies of SCE were induced with only 0.075 μg/ml of ASE.
Review: Putative mutagens and carcinogens in foods. IV. Malonaldehyde (malondialdehyde)
Authors: Hartman Philip E.
Published: February 2007

Malonaldehyde or malondialdehyde (MA) is an ubiquitous dietary constituent formed by the peroxidation of unsaturated fatty acids and of the food additive, sorbate. The average US citizen consumes between 0.2 and 0.6 μg of MA each day from fresh and processed meats alone. This figure might have been considerably higher in past decades when meat was packaged and stored under less optimal circumstances. No studies seem to have been performed to determine if free MA is released under physiological conditions, such as in simulated gastric juice. Although pure enzymologically synthesized MA is a weak mutagen for a new Salmonella frameshift tester strain containing a polyadenine sequence, reports of more pronounced mutagenicity and carcinogenicity are very likely erroneous. The impure chemically synthesized MA samples used in the strongly positive tests for genotoxic activity were contaminated with mutagenic methoxy‐and ethoxyacroleins that would not be expected to constitute important components of foodstuffs. Thus, the greatest importance of MA and other carbonyls in foodstuffs may be their ability to catalyze nitrosation reactions in the presence of free nitrite and as indicators of the presence of other lipid oxidation products.
Mutagenicity testing of two tropical plant materials with pesticidal potential in salmonella typhimurium: Phytolacca dodecandra berries and oil from seeds of azadirachta indica
Authors: Jongen W. M. F. , Koeman J. H.
Published: February 2007

In this study the mutagenic potential of two tropical plant materials was investigated in Salmonella typhimurium strains TA98 and TA 100. The oil extract from seeds of Azadirachta indica showed no mutagenic activity in either strain with or without addition of metabolizing systems.

When extracts of Phytolacca dodecandra berries were tested, only the butanol extract caused direct mutagenicity in TA98. After addition of rat liver homogenate, again only the butanol extract was positive in TA98. Addition of gut flora extract as metabolizing system generated positive effects in both the methanol extract and the butanol extract. The water extract showed only a slight positive effect, which can most probably be ascribed to the presence of histidine in the sample.
Statistical analysis and sample‐size determinations for mutagenicity experiments with binomial responses
Authors: Margolin Barry H. , Collings Bruce J. , Mason James M.
Published: February 2007

Two statistical analyses are studied for their applicability to mutagenicity experiments that produce binomial responses from a control group and a single treated group. Attention is focused on experiments with (1) group sample sizes greater than 500 and (2) a probability less than .05 for a binary observation from any experimental unit being “positive.” In addition, it is assumed that historical control data will not be included in the statistical analysis. The first analysis is a conditional binomial test, which has been tabulated extensively by Kastenbaum and Bowman [1970], while the second is based on a standard normal approximation to the distribution of the difference between two sample proportions. A formula is presented for each analysis that relates the associated probability of detecting a mutagen to the mutant frequencies and sample sizes of the two groups. Based on extensive numerical results, the conclusion is drawn that the normal test is the preferred analysis for experiments in which the ratio of the two sample sizes is between 0.80 and 1.25. On the further assumption that an experiment is to be conducted with equal experimental group sample sizes, recommendations are offered for values of this common sample size needed to achieve a specified power, ie, a degree of assurance of detecting a postulated level of mutagenic effect.
Optimal phenotypic expression times for HPRT mutants induced in foreskin‐, skin‐, and lung‐derived human diploid fibroblasts
Authors: Jacobs Lois , Bean Christian L. , Marx James A.
Published: February 2007

A series of paired lung‐ and skin‐derived fibroblast cultures has been established from human embryonic tissues under carefully controlled, identical conditions, providing the unique opportunity to study differences between normal diploid fibroblast populations from skin and lung without the confusion of genetic differences between donors. To reliably assess differences in the induced mutation frequencies observed among different cell populations, optimal phenotypic expression times in the HPRT mutagenesis system were determined for neonatal foreskin, fetal skin, and fetal lung cultures. Cell populations were mutagenized with several doses of N‐methyl‐N'‐nitro‐N‐nitrosoguanidine and were replated in 6‐thioguanine selective medium at intervals over 14 days. Survivals following MNNG exposure ranged from 1.6% to 45.5%. For all doses and survivals tested a 7‐day expression period was the optimal value for cultures from the three different tissue sources in six independent experiments. Mutant frequency data derived from untreated control populations confirmed that spontaneous mutations during the expression period contributed negligibly to the final mutant frequency. Differences between the mutation frequencies obtained using an in situ and a replating protocol were approximately twofold for lung‐, skin‐, and foreskin‐derived cultures.
Contribution of nitropyrene to the mutagenic activity of coal fly ash
Authors: Harris Wesley R. , Chess Edward K. , Okamoto Deborah , Remsen Joyce F. , Later Douglas W.
Published: February 2007

Stack‐collected coal fly ash from western low‐sulfur coal was extracted with 60:40 benzene/methanol. This extract was fractionated by preparative‐scale high performance liquid chromatography (HPLC) and the mutagenic activity of 14 fractions was evaluated by microbial assay with Salmonella typhimurium TA1538. A widespread distribution of direct‐acting mutagens, which probably includes both mono‐ and dinitroaromatics, was detected.

HPLC methods were also used to isolate 1‐nitropyrene from the total benzene/methanol extract. The identification of 1‐nitropyrene was based on gas chromatographic and HPLC retention measurements and mass spectral data. The concentration of 1‐nitropyrene in the ash extract was determined by quantitative HPLC analyses. Mutagenicity assays of the total extract and an authentic 1‐nitropyrene standard with Salmonella strains TA1538, TA100, and TA98 indicated that the 1‐nitropyrene accounts for approximately 0.03‐0.16% of the total mutagenic activity of the extract.
Mutagenicity of some benzidine congeners and their N‐acetylated and N,N′‐diacetylated derivatives in different strains of Salmonella typhimurium
Authors: Reid Thomas M. , Wang Ching Y. , King Charles M. , Morton Kenneth C.
Published: February 2007

The Ames Salmonella/microsome test was used to compare the mutagenic response of Salmonella typhimurium TA100, TA98, TA1538, and TA1535 to 12 benzidine derivatives, ie, benzidine, 3,3′‐dimethoxybenzidine, 3,3′‐dimethylbenzidine, 3,3′‐dichlorobenzidine, and the corresponding N‐ and W,W‐diacetylated derivatives. With a few exceptions, the mutagenic response to this series of compounds varied in the order TA98 > TA1538 > TA100 > TA1535 = 0, and the N‐monoacetylated derivatives were more mutagenic than either the parent diamines or the N,N′‐diacetyl derivatives. The relative mutagenicities of the parent amines for TA98 were 3,3′‐dichlorobenzidine > > 3,3′‐dimethoxybenzidine > benzidine > 3,3′‐dimethylbenzidine.
Reduction of sister chromatid exchange frequency with time after mutagen exposure in chinese hamster ovary cells in the presence of 3‐aminobenzamide
Authors: Schwartz Jeffrey L. , Morgan William F. , Wolff Sheldon
Published: February 2007

3‐Aminobenzamide (3AB) is a potent inhibitor of poly(ADP‐ribose) synthesis and has been reported to inhibit DNA repair. Inhibition of poly(ADP‐ribose) synthesis by 3AB results in a potentiation of the cytotoxic effects of alkylating agents and synergistically increases the frequency of sister chromatid exchanges (SCEs) induced in Chinese hamster ovary cells by methyl methanesulfonate (MMS). Experiments were carried out to determine if this synergism was related to an inhibition of the repair or the removal of SCE‐forming lesions by 3AB. Cells were treated with MMS or ethyl nitrosourea (ENU) and either held in a nonproliferative state or maintained in exponential growth for up to 48 hr before SCE frequencies were measured. During this time, the SCE frequency decreased greatly. 3AB did not affect this decrease in either cycling or noncycling cells. Furthermore, 3AB appears to exert its effect only in cycling cells when bromodeoxyuridine is present. Therefore, the synergism between 3AB and alkylating agents in the induction of SCEs is unrelated to effects of 3AB on the repair or removal of SCE‐forming lesions.
DNA‐damaging potential of diethylstilbestrol evaluated in the germ cell unscheduled dna synthesis assay
Authors: Racine R. R. , Schmid B. P.
Published: February 2007

Despite the fact that the nonsteroidal estrogen diethylstilbestrol (DES) exerts its toxic effects primarily on the reproductive system, little is known about the possible interference of this compound with germ cell DNA. The measurement of unscheduled DNA synthesis (UDS) in spermatocytes and early spermatids of mice germ‐cells is a valid indicator for the DNA‐damaging potential of a compound. UDS occurrence was thus determined after IP administration of 10, 30, 60 or 180 mg/kg DES to male mice. Tritiated thymidine ([3H]dThd) was then injected into the testes, the spermatozoa were serially collected, the sperm heads isolated, and UDS determined by the amount of [3H]dThd incorporation.

[3H]dThd measurements in germ cells of mice which were treated with 10 mg/kg DES were comparable to those of the controls. Higher incorporation of [3H]dThd, indicating UDS, was measured in sperm cells which had been spermatocytes at the time of treatment with 30 and 60 mg/kg DES; this increase was statistically significant at 60 mg/kg. Administration of 180 mg/kg DES caused [3H]dThd incorporation which was comparable to that of the controls, suggesting that DES interfered with repair mechanisms or delayed spermatogenic cycles at high dose levels. General toxicity was manifested in a dose‐dependent decrease of the sperm cell numbers in the spermatogenic stages investigated.

This study provides evidence that DES, or its metabolite(s), reached the germ cells of adult mice in sufficient amounts to produce DNA damage. The levels of radioactivity measured were comparable to those measured after cyclophosphamide treatment, but [3H]dThd incorporation was about 10 times less than in methylmethane sulfonate‐treated animals.
Comparative studies of dose‐response curves for recessive lethal mutations induced by ethylnitrosourea in spermatogonia and in spermatozoa of Drosophila melanogaster
Authors: Yoshikawa Isao , Ayaki Toshikazu , Ohshima Kayoko
Published: February 2007

Induction of recessive lethal mutations by N‐ethyl‐N‐nitrosourea (ENU) was studied for the second chromosome of spermatogonia and spermatozoa in Drosophila melanogaster. ENU (0.03,0.3, and 1.0 mM) was given to flies by dissolving it in feeding sucrose solution. Since flies are known to show increased avoidance of the feeding solution with increase in ENU concentration, the absorbed doses of ENU by flies were estimated from the previously determined empirical data for relation of ENU concentration in the feeding solution and the intake volumes of the solution by flies as measured indirectly via intake radioactivities of 3H‐labeled sucrose added to the solution. When plotted against absorbed doses of ENU, the observed frequencies of recessive lethals showed a linear relationship for induction in spermatozoa but a sigmoidal relationship for induction in spermatogonia. These results suggest that in spermatogonia ENU‐induced mutational damage is more repairable in a lower dose range of ENU. Mosaic lethal mutations were induced by ENU but not in spermatogonia.
Different effects of mutagens on sister chromatid exchange induction in three chinese hamster cell lines
Authors: Mehnert Karl , Vogel Walther , Benz Reiner , Speit Günter
Published: February 2007

The sister chromatid exchange (SCE) induction of mutagens with different mechanisms of action was comparatively investigated on permanent cell lines of the Chinese hamster (CHO, V‐79, and DON) with and without exogenous metabolic activation and with the use of various experimental protocols. CHO and V‐79 cells were treated with ethylmethanesulfonate (EMS), a direct mutagen; with the two indirect mutagens cyclophosphamide (CP) and benzo[a]pyrene (BP); as well as with the radical former hydrogen peroxide (H2O2) and hydroxyurea (HU), an inhibitor of DNA synthesis. Aside from an increased basal SCE level and a higher bromodeoxyuridine (Brdurd) sensitivity, there was no decisive difference betwen CHO and V‐79 cells. However, there was a distinct relationship between SCE induction and the experimental protocol used, which was most pronounced after HU treatment. Neither cell line was able to metabolize the indirect mutagen BP. Only in CHO cells did CP lead to increased SCE frequencies. However, in all cases, the simultaneous application of S9 mix produced a distinct SCE induction. In contrast, BP caused SCE induction in DON cells, whereas CP was not metabolized. The reason for these findings must obviously be sought in the metabolization of CP and BP via different monooxygenase systems, whose activity can differ in these permanent cell lines. One notable finding was that the number of SCE induced by H2O2 could be distinctly reduced by the simultaneous application of S9 mix. This effect can be explained by the fact that S9 mix contains H2O2‐degrading enzymes. The results indicate that closely related cell lines differ in their capability for inducing SCE and that investigations of SCE inductions performed on only one cell line do not necessarily produce a representative response.
Correlative genotoxicity studies of airborne particles in Salmonella typhimurium and cultured human lymphocytes
Authors: Krishna G. , Nath J. , Ong T.
Published: February 2007

The acetone extracts of ambient air particulates collected locally were tested for their capacity to induce sister chromatid exchanges (SCEs) and chromosomal aberrations (CAs) in human lymphocytes, and to induce gene mutations (GMs) in Salmonella typhimurium. The extracts caused dose‐related clastogenic/mutagenic responses in all three assay systems. With the same concentration, it seems that the Ames Salmonella/microsomal assay with TA98 gave the highest, and the chromosomal aberration assay with human lymphocytes the lowest, mutagenic/ clastogenic responses, respectively. Because high frequencies of SCEs were induced by solvent extracts of airborne particles, this study further indicated the usefulness of SCE assay in human lymphocytes for genotoxicity studies of airborne particles.
Spontaneous mutation frequencies in Salmonella: Enhancement of G/C to A/T transitions and depression of deletion and frameshift mutation frequencies afforded by anoxic incubation
Authors: Hartman Zlata , Hartman Philip E. , Barnes Wayne M. , Tuley Elodee
Published: February 2007

Incubation of Salmonella typhimurium under anoxic conditions (0.1 % oxygen or less) results in a substantial decrease in small (3‐and 6‐basepair) deletions in an A/T‐rich region of the hisG gene in the hisG428 ochre mutant and also decreases the frequency of minus frameshift mutations in G/C‐rich sequences in the hisD3052 and hisC3076 mutants. In contrast, the frequency of G/C→ A/T transition mutations increases substantially during anoxic growth of hisG46. Growth of revertants of strains carrying accessory deletions in the uvrB region of the Salmonella chromosome is drastically impaired on glucose minimal medium when oxygen partial pressures are below 0.1% oxygen.
Mutagenic 1‐nitropyrene in wastewater from oil‐water separating tanks of gasoline stations and in used crankcase oil
Authors: Manabe Yoshiki , Kinouchi Takemi , Wakisaka Kazumi , Tahara Isao , Ohnishi Yoshinari
Published: February 2007

Wastewater collected from oil‐water separating tanks of ten gasoline stations for a year was fractionated into diethyl ether‐soluble neutral, acidic, and basic fractions. Mutagenicity of these fractions was measured with Salmonella typhimurium strains TA98 and TA100 in the presence or absence of S9 mix. The neutral fractions showed high mutagenicity in the absence of S9 mix. Each neutral fraction was subjected to high‐performance liquid chromatography (HPLC) and fractionated. A 1‐nitropyrene(1‐NP)‐corresponding fraction was collected and analyzed by gas chromatography‐mass spectrometry (GC‐MS) and HPLC to prove that wastewater contains 1‐NP and to quantitate 1‐NP in wastewater. GC‐MS patterns showed the following molecular and fragment ion peaks of 1‐NP: 247, 217, 201, and 189. The amount of 1‐NP in 36 samples of wastewater was 4.2–25,600 ng per liter of wastewater, and 1‐NP accounted for O.3–58.5% of the total mutagenicity of the neutral fractions. The other 19 samples of wastewater did not contain any detectable 1‐NP. The mutagenicity of wastewater may be due to water from car washing and contamination by used crankcase oil.

A Soxhlet extract of crankcase oil used in a gasoline engine was fractionated into three fractions as above. Mutagenicity was measured with strains TA98, TA100, TA98NR, and TA98/1,8‐DNP6 in the absence or presence of S9 mix. The neutral fraction showed the highest mutagenicity with strain TA98 in the absence of S9 mix, and its mutagenicity was decreased in strains TA98NR and TA98/1,8DNP6. The latter result indicates that the used engine‐oil contained 1‐NP and dinitropyrenes. Actually, the amounts of 1‐NP and 1,6‐diNP in used crankcase oil were 138 and 2.0 ng per ml of oil, respectively, and these concentrations accounted for 0.45 and 2.7%, respectively, of the total mutagenicity of the neutral fraction with strain TA98 in the absence of S9 mix. Moreover, the concentrations of 1‐NP and 1,6‐diNP in used crankcase oil of a diesel engine were 349 and 31 ng per ml of oil, respectively, accounting for 0.9 and 12%, respectively, of the total mutagenicity of the neutral fraction in the same assay system.
Suppressive effects of chemicals in mixture on the Salmonella plate test response in the absence of apparent toxicity
Authors: Zeiger Errol , Pagano Dennis A.
Published: February 2007

There are chemicals that affect the number of his + revertant colonies of Salmonella in the plate test at doses that are apparently nontoxic, but may be causing nonlethal, toxic effects. When mixed with mutagens, these chemicals reduce the numbers of his+ revertant colonies on the plate with no accompanying visible toxic effect on the background lawn. Some of these plates are indistinguishable from spontaneous control plates, leading to the possibility that the mutagens under test would be evaluated as nonmutagenic, or that the mutagenic response would be underestimated. The reduction in mutagen‐induced revertant colonies in most cases is equivalent to the reduction in spontaneous revertants in the absence of mutagen. A spot test that permits a rapid screen of chemicals for inhibitory effects has been developed; a plate incorporation assay is used to confirm the effect. Toxic effects can be seen in the background lawns of plates examined at magnifications of 100 X or greater.
Mutagenic activity of airborne particles inside and outside homes
Authors: Van Houdt J. J. , Jongen W. M. F. , Alink G. M. , Boleij J. S. M.
Published: February 2007

Indoor concentrations of total suspended particles often exceed outdoor concentrations. Although it is known that particulate matter may contain mutagenic compounds and that several sources in the home produce mutagens, virtually no data concerning the mutagenicity of indoor particulate matter are available.

In this study, experiments were carried out to determine the contribution of indoor and outdoor sources to the mutagenicity of indoor particles. Using six samplers, particles in kitchens, living rooms, and outdoors were collected simultaneously. Methanol extracts of the material obtained were tested in the Salmonella/microsome assay. An increase in mutagenic activity was shown in the presence of a metabolizing system in all indoor and outdoor samples but one. The data presented suggest that mutagenic components of indoor particulate matter are different from those found in outdoor particles. Indoor samples show a higher mutagenic activity after metabolic activation, while direct mutagenic activity of indoor particles was lower than that of outdoor particles. Furthermore, only indoor samples showed cytotoxic effects. Our findings suggest that, with respect to the mutagenic activity of particulate matter, cigarette smoke is the most important contaminant of indoor air. Kitchen samples also show mutagenic activity, probably as a result of volatilization of cooking products. No contribution of outdoor sources to mutagenicity of indoor particles was observed.
The use of carcinogen‐DNA adduct antisera for quantitation and localization of genomic damage in animal models and the human population
Authors: Poirier Miriam C.
Published: February 2007

The use of antibodies to detect chemical carcinogen‐induced DNA damage involves quantitative determination and morphological localization utilizing antisera specific for carcinogen‐DNA adducts. In recent years a large number of polyclonal and monoclonal antisera have been produced against individual adducts and modified DNAs with addition products varying in structure from ethyl and methyl groups to aromatic amines, polycyclic aromatic hydrocarbons, aflatoxins, and platinum‐ammine complexes. The quantitative assays developed through the use of these antisera are able to detect attomole (10−18 M) adduct concentrations, corresponding to one adduct in 108 nucleotides or a few hundreds of modifications per mammalian cell genome. This review focuses on data generated during the past 3 yr utilizing this immunotechnology as a tool to probe mechanisms of carcinogen‐DNA interactions in various model systems and in the human population. Areas discussed in depth include quantitative and morphological studies involving detection of 2‐acetylaminofluorene‐DNA adducts in rat liver, O6‐ethyl and O6‐methyl deoxyguanosine adducts in rat brain, benzo[a]pyrene‐DNA adducts in mouse skin and cis‐diamminedichloroplatinum (II)‐DNA adducts in peripheral nucleated blood cells of cancer patients.
Induction of forward mutation at the yg2 locus in maize by ethylnitrosourea
Authors: Schy William E. , Plewa Michael J.
Published: February 2007

We analyzed the kinetics of mutation induction at the yg2 locus in Zea mays by N‐ethyl‐N‐nitrosourea (ENU). ENU concentrations ranged from O.l to 10.7 mM and a linear, concentration‐dependent response was observed for the induction of yg2 sectors in leaf 4 and leaf 5. For both leaf 4 and leaf 5 ENU exhibited one‐hit kinetics consistent with either a point‐mutational or chromosome‐breakage mechanism of mutation induction. The mean induced mutation rate/mM ENU for the combined leaf 4 and leaf 5 data was 6.77 × 10−4 mutations/locus/mM ENU. This value was used to compare the mutagenic effectiveness of ENU with ethyl methanesulfonate (EMS) and to calculate a rad equivalent for ENU. ENU was found to be 3.8‐fold more effective than EMS. Based on their respective chemical reactivities with DNA, we propose that ENU predominantly induces point mutations at the yg2 locus. One rad of gamma radiation induced the same rate of mutation as an 8‐hr exposure to a 6.71 × 10−6 M concentration of ENU at 20°C.
Solvent interactions with test compounds and recommendations for testing to avoid artifacts
Authors: Nestmann Earle R. , Douglas George R. , Kowbel David J. , Harrington Tina R.
Published: February 2007

Reports in the literature describing artifactual results owing to interactions of test materials with solvents are becoming more frequent. The present study was initiated to examine possible interactions of 1,1,3‐trichloro‐, 1,1,3,3‐tetrachloro‐, pentachloro‐ and hexachloroacetones with different solvents, since certain solvent effects with the last compound have been shown previously. Quantitative differences in levels of mutagenic potency were found for tri‐, tetra‐, and pentachloroacetone, dissolved in acetone or dimethyl sulfoxide (DMSO). On the other hand, hexachloroacetone without solvent was mutagenic, and this activity was enhanced when it was dissolved in DMSO; in acetone it was not mutagenic. A time‐dependent reaction of hexachloroacetone with DMSO was the only test material‐solvent interaction found in this study. The results show clearly that DMSO is not an appropriate solvent for hexachloroacetone. On the basis of these and previous results, we recommend consideration of the following strategy to help prevent reporting of artifactual results owing to interaction with solvents: (1) Results from initial screening experiments should be confirmed in repeat experiments using a different solvent; and (2) a different solvent should be used in confirming the findings of other investigators. Differences in results would indicate a need for further study.
Mutagenesis assays of human amniotic fluid
Authors: Everson Richard B. , Milne Karen L. , Warburton Dorothy , McClamrock Howard D. , Buchanan Philip D.
Published: February 2007

Extracts of amniocentesis samples from 144 women were tested for the presence of mutagenic substances using tester strain TA 1538 in the Ames Salmonella/ mammalian‐microsome mutagenicity test. Because the volume of amniotic fluid in these samples was limited (generally less than 10 ml), we investigated modifications of this mutagenesis assay that could increase its ability to detect effects from small quantities of test material. Using mutagenicity in samples of urine from smokers as a model, it appeared that improved ability to detect small amounts of mutagen could be obtained by reducing volumes of media and reagents while keeping the amount of test sample constant. This modification resulted in a test procedure capable of readily detecting mutagenicity in volumes of urine from smokers that were smaller than the volumes of amniotic fluid available. Tests of amniotic fluid extracts by this modified procedure showed small increases in revertants, about 50% above dimethylsulfoxide solvent control values. Results of procedures to control for technical factors possibly contributing to these increases suggested that the increased values could not be readily explained by contamination of test samples with mutagens during the extraction procedure. They also were not explained by alterations in spontaneous numbers of revertants associated with changes in the density of bacterial lawn growth. The increases suggest the presence of small amounts of mutagenic material in many of the amniotic fluid samples. At the doses employed, mutagenic activity in these samples was not associated with maternal smoking.
Niridazole: Evidence for promutagenic events involving guanine‐cytosine and adenine‐thymine base pairs
Authors: Speck William T. , Carr Howard S. , Rosenkranz Herbert S.
Published: February 2007

Niridazole, a widely used antiprotozoan agent, is mutagenic for Salmonella typhimurium strains that contain guanine‐cytosine as well as adenine‐thymine base pairs at their mutational sites. The mutagenic activity for both types of targets depends upon nitroreduction.
A selective screen for transposable element mobilization in drosophila melanogaster
Authors: Clark S. H. , Chovnick A.
Published: February 2007

A selective system is described that provides a simple and sensitive assay for the detection and analysis of induced mobile element transpositions in Drosophila melanogaster. The system will detect a single event in samples greater than 106 and thus provides a eucaryotic assay system for monitoring the induction of transposition by a variety of agents including, but not limited to, chemical carcinogens and toxins, ionizing radiation, and various environmental pollutants. The experimental system focuses on an X‐linked rosy+ transposon and a conditional lethal system that permits the detection of a single transposition event in very large samples. The results of a pilot experiment utilizing this system are presented.
Metabolic activation of organic extracts from diesel, coke oven, roofing tar, and cigarette smoke emissions in the ames assay
Authors: Williams Katherine , Lewtas Joellen
Published: February 2007

Four environmental emissions samples were ranked by their genotoxic potency in several bioassays. Although the relative potency of a series of automotive emissions (diesel and gasoline) in the Ames assay correlated well with the relative potency in mammalian cell and mouse skin, this was not the case for the coke oven, roofing tar, and cigarette smoke condensate (CSC) emissions. This study examines the role of metabolic activation in determining the difference between a microbial and a mammalian bioassay in ranking the genotoxic potency of these environmental emissions. Uninduced and Aroclor 1254‐induced S9 from both rat and hamster liver were compared as the metabolic activator in the Ames assay with Salmonella typhimurium TA98. The diesel emissions sample was directacting while the other samples required activation. The standard S9 concentration (only Aroclor‐induced rat, approximately 1.25 mg protein/plate) also produced the maximum mutagenic activity. Induced S9s produced higher mutagenic activity than uninduced. The hamster S9 gave significantly higher mutagenic activities than rat S9 for the coke oven and CSC. The relative potency of these four samples was not significantly different between the microbial (Ames), mammalian cell (mouse lymphoma), and tumor initiation (mouse skin) assays. These results suggest that the differences observed between the relative mutagenic activity of these emissions in the mammalian cell and microbial assays was not due to a lack of optimization of the S9 system but may be inherent in the different response of the indicator cells to different chemical classes.
Mutagenesis at the ouabain‐resistance locus of 3.7.2c l5178y cells by chromosomal mutagens
Authors: Amacher David E. , Dunn Emily M.
Published: February 2007

Chemical mutagens including methyl methanesulfonate, N‐methyl‐N'‐nitro‐N‐nitrosoguanidine, iodomethane, and epichlorohydrin have been classified as “chromosomal mutagens” in the L5178Y/thymidine kinase (TK) gene mutation assay by Clive and coworkers [Mutat Res 59:61–108, 1979; and “The Predictive Value of Short‐Term Screening Tests in Carcinogenicity Evaluation.” Amsterdam: Elsevier/North Holland, pp 103–123, 1980] who observed mutagen‐dependent increases in small TK‐deficient mutant colonies with detectable damage to the chromosome (11) that carries the TK locus. In this study, we tested these four chemicals for the induction of gene mutations at the ouabain‐resistance (ouares) locus of 3.7.2C L5178Y cells to determine if presumptive chromosomal mutagens would go undetected at a gene locus that is unresponsive to chromosomal damage. A final concentration of 375 μg/ml ouabain in soft‐agar medium selected against the ouabain‐sensitive phenotype without loss of the mutagen‐induced ouabain‐resistant phenotype. Verification of the mutant phenotype was completed for six individual soft‐agar ouares colonies derived from mutagen‐treated cultures via growth for 10–11 days in nonselective medium followed by retesting for colony formation in selective soft‐agar medium. Dose‐related reproducible increases in the frequency of ouabain‐resistant mutants were observed for 3.7.2C L5178Y cells that had been exposed for 3 hr to 24–46 μg/ml epichlorohydrin, 1.9–3.6 μg/ml iodomethane, 0.006–0.011 μg/ml N‐methyl‐N'‐nitro‐N‐nitrosoguanidine and 2.0–5.4 μg/ml methyl methanesulfonate. Also, treatments with EMS, which induced sufficient numbers of ouares colonies to permit analysis of colony size distribution, showed the existence of a bimodal size distribution similar to those reported for TK‐deficient mutants. This discovery suggests that mutant colony size in this cell line may be independent of specific gene locus effects. We conclude that (1) chemicals that induce a high proportion of chromosomal mutants, as detected at the TK locus in earlier studies, also induce single gene mutations at the ouabain‐resistance locus and (2) a bimodal distribution of mutant colony sizes in soft‐agar.
Genetic drift and seasonal variation in spontaneous mutation frequencies in Drosophila
Authors: Mason J. M. , Valencia R. , Woodruff R. C. , Zimmering S.
Published: February 2007

Spontaneous sex‐linked recessive lethal mutation frequencies may vary with time. Examination of approximately 1.7 × 106 Drosophila melanogaster × chromosomes in three laboratories suggests two sources of variation in the spontaneous mutation frequency. First, the underlying mutation rate may change with time, suggesting genetic drift among the genes controlling the spontaneous mutation rate. In one set of experiments, the recessive lethal frequency increased from 0.2% to 0.4% in 6 years. Second, there may be seasonal variation in the mutation frequency even under apparently controlled conditions, suggesting that uncontrolled environmental factors may play an important role in determining the mutation frequency. Therefore, concurrent controls should be used in mutation experiments except in cases in which the frequency in the untreated control is so low as to be unmeasurable in a single experiment or the control frequency can be shown not to vary with time.
Significance of the genotoxic activities observed in vitro for 35 of 70 NTP noncarcinogens
Authors: Ashby John , Purchase I. F. H.
Published: February 2007

A speculative analysis is presented of the in vitro genotoxicity data reported by Shelby and Stasiewicz for 70 chemicals defined as noncarcinogenic to rodents by the National Toxicology Program. It is concluded that the genotoxic activities observed are probably subject to logical explanation. It is suggested that short‐term genotoxicity assays conducted in vivo on newly defined in vitro genotoxins may have a useful role to play in discriminating animal carcinogens from noncarcinogens. It is clear from the results reported that genotoxic activities observed in vitro for a new test chemical only provide evidence of its possible animal carcinogenicity; they are not definitive of carcinogenicity—the difference may be negligible in general but might prove unacceptable in the particular.
Studies in comparative chemical mutagenesis
Authors: Sobels F. H.
Published: February 2007

This paper presents a review of various collaborative studies in comparative mutagenesis. The following studies are briefly described: (1) the chemical mutagenesis programme of the European Community, (2) Drosophila studies with various alkylating agents of different s (Swain‐Scott) factors, (3) the evaluation by the International Commission for Protection against Environmental Mutagens and Carcinogens (ICPEMC) Committee 1, (4) the Environmental Protection Agency's Gene‐Tox Programme, (5) the first and second United Kingdom Environmental Mutagen Society (UKEMS) collaborative studies, and (6) the International Programme on Chemical Safety (IPCS) collaborative study on in vitro tests. The need for chemical dosimetry is emphasized. One of the main conclusions is that, of the mammalian point mutation assays, the L5178Y (TFTR, trifluorothymidine resistant) system showed greatest detection capability in the second UKEMS study. The consensus conclusion of the IPCS in vitro study was that chromosomal aberrations are considered to be the optimal assay for complementing the Salmonella assay and offer the additional advantage that aneuploidy, polyploidy, and sister chromatid exchanges can also be easily assessed.