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At least 19 recordsLinked to original sources
PubMed1992

Mutagenicity testing of protein-containing and biological samples using the Ames/Salmonella plate incorporation test and the fluctuation test.

Mutagenicity testing of biological samples and proteins is complicated by the presence of histidine and histidine-related growth factors which may produce a false positive result in the Ames/Salmonella plate incorporation test. A bioassay method, utilizing an automated dispenser-photometer and Salmonella typhimurium strain TA1535 as the indicator bacteria, was used to estimate the presence of histidine-related growth factors in three enzyme solutions submitted for mutagenicity testing. One of the solutions was clearly positive in the Ames/Salmonella test and also contained the highest amount of L-histidine-HCl-equivalents. The two other solutions, with low or undetectable amounts of L-histidine-HCl-equivalents, gave equivocal and negative results, respectively, in the Ames/Salmonella test. Studies were also performed with strains TA98, TA100 and TA1535 to determine the amount of added L-histidine-HCl that would result in a 'positive' result in the Ames/Salmonella test. Because the minimum amount of L-histidine-HCl required to double the number of revertant colonies was 150 nmol/plate, and the maximum amount of L-histidine-HCl-equivalents supplied by the enzyme preparations was 40 nmol/plate at the highest tested dose, the mutagenicity test results of the enzyme solutions cannot be explained solely by histidine or related compounds. Smokers' and non-smokers' urines, concentrated with liquid extraction (CHCl3) and adsorbent (XAD-2 and XAD-2/Sep-Pak C18) techniques, were studied to reveal differences in efficiencies to extract histidine and histidine-related compounds in the urines. Amounts of 'histidine' in concentrates of urine were measured using the bioassay method and a chemical method employing derivatization with fluorescamine. The fluorescamine method also efficiently detected 3-methyl-L-histidine, a product of muscle metabolism excreted in urine, which was found to be unable to support auxotrophic growth in TA1535, leading to exaggerated estimations of the auxotrophic growth enhancing properties of urine extracts. The urine extracts, and pure L-histidine-HCl, were tested using a two-step fluctuation test to estimate auxotrophic growth factor effects in this type of test. Because of a strong dilution effect when adding the histidine-free selection medium, the fluctuation test employed in this study was not found to be particularly sensitive to growth factors. The results of this study indicate that use of a bioassay, employing the same indicator bacteria as the mutagenicity test themselves, is a reliable way to measure histidine-related growth factors in biological samples.(ABSTRACT TRUNCATED AT 400 WORDS)

Enzymes↗
PubMed1982

[Problems concerned with microbial mutagenicity tests].

Mutagenicity tests using microorganisms are the Salmonella-typhimurium test (Ames), the test with a polymerase A deficient Escherichia coli, the Saccharomyces cerevisiae D3 system and the Neurospora crassa test. Differences in results of Ames-test may be due to differences preserving the tester strains, the choice of solvent and the dosage of the test compounds, last not least is the production of S-9. The polymerase A deficient Escherichia coli system seems easier to handle than the Saccharomyces cerevisiae- or Neurospora crassa-test. The metabolic activation with different forms of S-9 is needed in the Salmonella- and the Escherichia coli-system. Nevertheless it is not possible to decide if a substance is carcinogenic for human beings or animals with microbial mutagenicity tests only.

Carcinogens↗
PubMed1993

Genotoxicity testing of the herbicide Roundup and its active ingredient glyphosate isopropylamine using the mouse bone marrow micronucleus test, Salmonella mutagenicity test, and Allium anaphase-telophase test.

The genotoxic potential of the herbicide Roundup and its active agent, glyphosate isopropylamine salt, was studied in three different assays. No clastogenic effects were found in the mouse bone marrow micronucleus test for either of the two agents. In the Salmonella assay only Roundup was tested. It showed a weak mutagenic effect for the concentrations 360 micrograms/plate in TA98 (without S9) and 720 micrograms/plate in TA100 (with S9). These concentrations are close to the toxic level. The anaphase-telophase Allium test showed no effect for the glyphosate isopropylamine salt, but a significant increase in chromosome aberrations appeared after treatment with Roundup at concentrations of 1.44 and 2.88 mg/l when calculated as glyphosate isopropylamine. The most frequent aberrations observed could be characterized as disturbances of the spindle.

Allium↗
PubMed1979

A combined testing protocol approach for mutagenicity testing.

The antischistosomal agent, hycanthone methanesulfonate (HMS), was employed to illustrate the utility of carrying out several mutagenicity tests in a single concurrent animal experiment. Several commonly used procedures that were successfully integrated into a multiple testing protocol included (1) metaphase analysis in bone marrow, (2) micronucleus test in bone marrow, (3) analysis of the urine for mutagenic constituents, and (4) the host-mediated assay using Salmonella typhimurium. In addition to these animal studies, in vitro mutagenicity testing with and without activation was carried out using S. typhimurium. HMS produced positive, dose--response effects in in vitro tests, metaphase analysis, micronucleus test, and urine analysis, but not in the host-mediated assay. The results of these integrated techniques suggest that such a protocol may be a benefit to those concerned with mutagenicity testing of chemicals.

Animals↗
PubMed1983

Criteria for the standardization of Salmonella mutagenicity tests: results of a collaborative study. II. Studies to investigate the effect of bacterial liquid culture preparation conditions on Salmonella mutagenicity test results.

The influence of various parameters and growth conditions in the "overnight culture" of Salmonella typhimurium strains on mutagenicity test results was investigated. A number of factors were first suspected to be of some importance for the quantitative outcome of the mutagenicity test. None of them, however, was found to influence the results to such a marked extent as to be a major source of variability. Only the brand of nutrient broth used for the propagation of the bacteria proved finally to have a certain effect on the number of (spontaneous and induced) revertant colonies, although no precise and quantitative statements can be made with regard to a possible standardization of this experimental segment in the Salmonella mutagenicity test. The occurrence of such unpredictable but noticeable influences is, however, evidence for the importance of an intralaboratory optimization and standardization of all parts of the test procedure.

Animals↗
PubMed1981

Flow cytometric measurement of nuclear DNA content variations as a potential in vivo mutagenicity test.

Mutagen-induced variations of the cellular DNA content have been studied in mouse bone marrow cells in vivo using high resolution flow cytometric techniques. During the first days after a single injection of the chemical mutagen cyclophosphamide an increased coefficient of variation in the G1 peak of the flow histograms was observed. The magnitude and duration of this effect were dose-dependent. The reproducibility of the measurements was high, indicating that individual variability between animals and instrumental dispersion is small. The results demonstrate that on the basis of the flow cytometric measurement of cellular DNA content, a short-term in vivo test for mutagenicity can be established which is much faster than conventional cytogenetic methods.

Animals↗
PubMed1983

Criteria for the standardization of Salmonella mutagenicity tests: results of a collaborative study. IV. Relationship between the number of his- bacteria plated and number of his+ revertants scored in the Salmonella mutagenicity test.

Five laboratories participated in a joint ring study to investigate the role of bacterial cell number in the Salmonella mutagenicity test. A strictly standardized protocol, using sodium azide and TA 1535, was developed and employed to test the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) with different dilutions of Salmonella typhimurium TA-100 and TA-1535 cultures. All laboratories detected the mutagenic activity of sodium azide with only a 2-fold variation of test results. For MNNG the interlaboratory variation was approximately 5-fold. Decreasing numbers of test bacteria employed resulted in lower numbers of MNNG-induced revertants in all laboratories. The number of preexisting revertants decreased in direct proportion to the reduced cell content, whereas the number of spontaneous revertants was not as greatly affected. A critical amount of test bacteria was required in order to obtain numbers of induced revertants which were equal to twice the number of spontaneous revertants. Two evaluation parameters which may be employed to describe the mutagenicity of a compound are compared.

Animals↗
PubMed1983

Criteria for the standardization of Salmonella mutagenicity tests: results of a collaborative study. III. The influence of the composition and preparation of the minimal medium in the Salmonella mutagenicity test.

The influence of factors connected with the preparation of the minimal medium for the Ames test has been investigated. Faulty sterilization procedures can lead to the generation of toxic and/or mutagenic by-products in the minimal medium. Changes in histidine concentration affect not only the number of spontaneously arising colonies on the plate, but also the number of induced mutants. Although the number of spontaneous mutants increases slightly with increasing histidine concentration, the influence on the number of induced mutants depends on the nature of the mutagen tested.

Agar↗
PubMed1984

Development of an in situ microbial mutagenicity test system for airborne workplace mutagens: laboratory evaluation.

A simple on-site Salmonella mutagenicity test system for the detection of airborne mutagens in the workplace is being developed. The system permits entrapment of mutagenic airborne particles and vapors by impinging unfiltered ambient air into trapping medium containing bacterial tester cells. The trapping device consists mainly of a pump, an impinger and a cyclone. The impinging air flow generated by the pump is approximately 3 1/min. New Salmonella typhimurium testers which are resistant to streptomycin (Str) and 8-azaguanine (AG) were derived from the Ames testers TA98 and TA100 and the arabinose-resistant tester SV50, and were used as mutation indicators. Microbial contamination was sufficiently controlled by addition of ampicillin, Str, AG, and cycloheximide to the trapping and plating media. New tester strains retained a high mutagenic sensitivity from their parent strains. Laboratory studies with volatile mutagens (methyl methanesulfonate, ethyl methanesulfonate, and dimethylnitrosamine) showed that the vapor trapping of this system is promising. The study with suspended silica particles coated with a known mutagen (2,4,7-trinitro-9-fluorenone) indicated that the particle trapping of the system is satisfactory. Incorporation of metabolic activation into the trapping medium by confining S9 mix and tester cells in dialysis tubing enabled this system to detect promutagens. This in situ system may be useful for mutagenic monitoring in the workplace.

Air Pollutants, Occupational↗
PubMed1984

A comparison between different high volume sampling systems for collecting ambient airborne particles for mutagenicity testing and for analysis of organic compounds.

Samples of urban air were collected simultaneously using different sampling systems, including electrostatic precipitation (ESP) and high volume filtration (HVF) on various filters for particle sampling and absorption on activated carbon and organic polymers for sampling of volatiles. Acetone extracts of the samples were analyzed for polycyclic aromatic hydrocarbons (PAH) and tested for mutagenicity with the Ames Salmonella/microsome assay. The results show that the concentrations of PAH found in the various particle-samples were in good agreement, whereas the mutagenic activity of these samples showed large variations. The highest mutagenic activity was found in the samples collected by ESP and on the teflon-coated glassfibre filters, whereas samples collected by high volume filtration with size-fractionation showed the lowest mutagenic activity. We do not know whether the higher activity in samples from the teflon-coated filters compared to those from ordinary glassfibre filters represent filter artifacts or if it represents a more pronounced degradation of mutagenic compounds on the non-coated glassfibre filters. Extracts from filter blanks seemed to interfere with the expression of the mutagenic activity of the positive controls, benzo[a]pyrene and nitropyrene. When sampling volatile compounds, two organic polymers, polyurethane (PUR) and XAD-2, were found suitable for collecting PAH, whereas no PAH could be detected in extracts from the activated carbon. The XAD-2 adsorbent was the most effective for sampling bicyclic PAH. None of the adsorbents yielded extracts well suited for mutagenicity testing, since blank extracts were toxic to the test bacteria. Some extracts of the PUR blanks were weakly mutagenic as well. More emphasis should be placed upon developing more efficient and unreactive adsorbents and on the adaptation of such adsorbents in samplers suited for routine use.

Air Pollutants↗
PubMed1983

Advantages of and problems with short-term mutagenicity tests for the assessment of mutagenic and carcinogenic risk.

The Salmonella microsomal assay has become an indispensible tool for the screening of mutagens and carcinogens, particularly when a large number of samples have to be tested, as in the present context for the screening of air pollution. However, for a more definite identification of potential carcinogens, a verification of the results from bacterial tests has to be performed with a battery of other tests, including point mutations and chromosomal aberrations in eukoaryotic systems. While there is a close qualitative correlation between the mutagenic and carcinogenic property of chemicals, a corresponding quantitative correlation between the mutagenic and carcinogenic potency is not always found. One reason for this lack of quantitative correlation presumably depends on the fact that cancer is induced in two steps, of which only the initiating, but not the promoting, step constitutes a mutational event, which is reflected by mutagenicity tests. Present mutagenicity tests have concentrated on discrete major mutations, while mutations of polygenes, acting on quantitative characters, have largely been omitted. Mutational data from Drosophila indicate, however, that polygenes mutate at a considerably higher rate than major genes and that they have a comparatively strong effect in heterozygous condition. It seems of great importance to develop appropriate methods to study induced mutations of polygenic systems and to get a better understanding of the properties of these genetic systems and an evaluation of the risk connected with induced mutations in polygenes.

Air Pollutants↗
PubMed1984

Mutagenicity testing of high performance liquid chromatography fractions from wood stove emission samples using a modified Salmonella assay requiring smaller sample volumes.

Organic extracts of emissions from wood combustion have been fractionated by high performance liquid chromatography (HPLC) into 25-28 fractions. Each fraction was tested for mutagenic activity in a modified Ames Salmonella/microsome bioassay requiring one-third of the test volumes needed for the ususal test. Direct mutagenic activity was noted predominantly in the most polar fractions, whereas indirect mutagenic activity was associated with the fractions containing polycyclic aromatic hydrocarbons (PAH) and with polar fractions probably consisting of aza-arenes and aromatic amines.

Air Pollutants↗
PubMed1981

Mutagenicity testing of some commonly used dyes.

Seventeen commonly used dyes and 16 of their metabolites or derivatives were tested in the Salmonella-mammalian microsome mutagenicity test. Mutagens active with and without added Aroclor-induced rat liver microsome preparations (S9) were 3-aminopyrene, lithol red, methylene blue (USP), methyl yellow, neutral red, and phenol red. Those mutagenic only with S9 activation were 4-aminopyrazolone, 2,4-dimethylaniline, N,N-dimethyl-p-phenylenediamine, methyl red, and 4-phenyl-azo-1-naphthylamine. Orange II was mutagenic only without added S9. Nonmutagenic azo dyes were allura red, amaranth, ponceau R, ponceau SX, sunset yellow, and tartrazine. Miscellaneous dyes not mutagenic were methyl green, methyl violet 2B, and nigrosin. Metabolites of the azo dyes that were not mutagenic were 1-amino-2-naphthol hydrochloride, aniline, anthranilic acid, cresidine salt, pyrazolone T,R-amino salt (1-amino-2-naphthol-3,6-disulfonic disodium salt), R-salt, Schaeffer's salt (2-naphthol-6-sulfonic acid, sodium salt), sodium naphthionate, sulfanilamide, and sulfanilic acid. 4-Amino-1-naphthalenesulfonic acid sodium salt was also not mutagenic. Fusobacterium sp. 2 could reductively cleave methyl yellow to N,N-dimethyl-p-phenylenediamine which was then activated to a mutagen.

Coloring Agents↗
PubMed1984

[Mutagenicity testing of commercially used strains of P. camemberti and P. roqueforti].

We tested the mutagenic potential of crude extracts of 18 strains of Penicillium camemberti and 6 strains of P. roqueforti, which are used commercially in the production of mould ripened cheese in Switzerland. No mutagenic activity could be detected in any of the extracts. Roquefortine, a mycotoxin of P. roqueforti, often found in Blue cheese, was negative in the Amestest. The results obtained do not lead reasons for experting undesired long term effects from the consumption of mould ripened cheese.

Animals↗
PubMed1987

Mutagenicity testing of human milk from smokers and non-smokers in the Salmonella/microsome test.

Human milk was tested in the Ames plate incorporation test using strain TA98. Pools from smokers and non-smokers respectively, as well as individual samples from 14 smokers and 15 controls were tested. No difference was found between milk from smokers and non-smokers in the concentrations and volumes used. Preliminary to this a cigarette smoke condensate (CSC) was tested. The CSC was then incubated with human milk which was fractionated, concentrated and the different fractions tested for mutagenic activity. 98% of the mutagenic effect added (measured as number of revertants caused by an equivalent volume of CSC) was recovered 52% of the revertant colonies were recovered from the fat fractions, 40% from the skimmed milk and 8% from a precipitate. Breast milk was also incubated with C14-benzo(a)pyrene and then fractionated by density gradient ultracentrifugation. 97% of the radioactivity was found in the lipid fraction.

Animals↗