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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

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

Significance of mutagenicity testing on pesticides.

Our mutagenicity screening studies on pesticides totalling 165 have newly revealed microbial mutagenic activity in the following four compounds: 2,4-dinitrophenyl thiocyanate (NBT), sodium p-dimethylamino-azobenzene diazosulfonate (DAPA), 5-nitro-1-napthonitrile (NNN) and N-(1,1,2,2-tetrachloroethylthio)-4-cyclohexene-1, 2-dicarboximide (Captafol). Significance of mutagenicity testing on pesticides is discussed from the toxicological point of view. No definite relationship has been proven among mutagenicity, carcinogenicity and teratogenicity of pesticides although there are some correlations in these activities of several pesticides. Further studies are needed to clarify the significance of mutagenicity testing in toxicological areas.

Animals

Mutagenicity test of dyes used in cosmetics with the Salmonella/mammalian-microsome test.

37 dyes including 3 anthraquinone, 22 azo; 5 xanthene, 5 fluorandiol, and 2 thioindigo dyes, were tested for mutagenic potential with the Salmonella/mammalian-microsome test. Two frame-shift histidine mutants (TA1537 and TA98) and two base-pair substituted histidine mutants (TA1535 and TA100) of Salmonella typhimurium were employed. Both the spot test and the plate-incorporation assay indicated that one azo dye, D&C Orange No. 17, was mutagenic with three of the bacterial test strains. The mutagenic response of D&C Orange No. 17 was depressed by the addition of the microsomal fractions from rat livers. Of the chemicals used to synthesize D&C Orange No; 17 was depressed by the addition of the microsomal fractions from rat livers. Of the chemicals used to synthesize D&C Orange No. 17, beta-naphthol was not mutagenic but 2,4-dinitroaniline was mutagenic to the same Salmonella strains as D&C Orange No. 17 . Dimethyl sulfoxide extracts of lipsticks of similar formula but without D&C Orange No. 17 were tested in the plate incorporation assay. Only those containing D&C Orange No. 17 were mutagenic and the dye was mutagenic at concentrations consumed in normal daily use.

Animals

Mutagenicity testing of benomyl, methyl-2-benzimidazole carbamate, streptozotocin and N-methyl-N'-nitro-N-nitrosoguanidine in Salmonella typhimurium in vitro and in rodent host-mediated assays.

The fungicide benomyl and its commercial preparations Fundazol 50WP and Benlate 50WP and the benomyl metabolite methyl-2-benzimidazole carbamate and its commercial preparation MBC 50WP were tested for mutagenicity in in vitro spot tests, in microsomal plate assay, in liquid-culture treatments, or in rodent host-mediated assay. The base-pair substitution Salmonella typhimurium mutant hisG46 and the hisG46-bearing uvrB excision-repair-deficient mutants TA100, TA1530, TA1535 or TA1950 were used as test organisms. Complete genotypic information of these mutants is given in Ames et al. [2]. Captain 50WP, streptozotocin (SZN), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 2-aminopurine and N-acetylaminofluorene were used as positive control compounds. In nonoverlay spot tests Benlate 50WP was not mutagenic over a dose range of 50-5000 microgram/spot in hisG46 and TA1535. In overlay spot tests 50 or 100 microgram/spot Benomyl, MBC, Fundazol 50WP, Benlate 50WP and MBC 50WP were tested in hisG46, TA1530 or TA1950. Only a non-commercial MBC sample at 100 microgram/spot showed weak mutagenic activity in hisG46. In microsomal activation plate assay MBC, benomyl, Fundazol 50WP and Benlate 50WP were tested in TA100 over a dose range of 50-2000 microgram/plate. None of the compounds showed mutagenicity. In a 20-h liquid-culture treatment 10, 100, 1000 and 10 000 microgram/ml Fundazol 50WP were not mutagenic in TA 30. In 1-h liquid-culture treatments benomyl, Benlate 50WP or Fundazol 50WP failed to induce mutations in hisG46, TA100 or TA1950 over a dose range of 0.25-1000 microgram/ml. Appropriate positive controls were mutagenic in each experiment. The consistently negative results in this study with commercial MBC and benomyl preparations are contrary to positive results reported earlier with similar methods and similar commercial preparations. Possible reasons to explain the different results are presented. The alkylating agents SZN and MNNG induced fewer mutations in TA1530 and TA1950 uvrB excision-repair-deficient strains than in the hisG46 excision-proficient strain, indicating that with these mutagens excision-repair is also a mutation-prone process. In rodent host-mediated assays with Fundazol 50WP in mice 3 consecutive subcutaneous hourly doses of 500 mg/kg in hisG46 and TA1950 and in rats or mice an oral dose of 4000 mg/kg in TA1950 were not mutagenic. The positive control SZN was mutagenic.

Animals

Determination of halogenated organic compounds and mutagenicity testing of spent bleach liquors.

The content of organohalogenated compounds in spent bleach liquor from different bleaching stages in a sulphate and a sulphite plant has been determined by a combination of glass capillary gas chromatography, gas-liquid chromatography/mass spectrometry and neutron activation analysis. Several compounds which have not been reported before have been identified including halogenated derivatives of dimethyl-propylnaphthalenes and alkylated catechols. The unconcentrated effluents, non-polar and total extracts were tested for mutagenic activity with Ames' Salmonella test. Spent bleach liquors from most bleaching stages as well as the total effluents contained mutagenic compounds. Addition of liver microsomes for metabolic activation reduced the mutagenic activity in all stages except for the first chlorination stage in the sulphate plant. Two isomers of chloro-, bromo-, and dichloro-p-cymene previously determined in effluents from bleaching plants were synthesized from the parent molecule. Both bromo- and dichloro-p-cymene exhibited weak mutagenic activity in the Salmonella test system. Liver microsomes reduced the effect slightly. The chlorinated cymenes were found to account for up to 18% of the total organically-bound chlorine in the non-polar extracts.

Chemical Industry

Mutagenicity testing of antischistosomal thioxanthenones and indazoles on yeast.

Two antischistosomal thioxanthenones, lucanthone and hycanthone, and four antischistosomal indazoles, IA-3, IA-4, IA-5, and IA-6, have been tested for mutagenicity on stationary phase cells of the yeast Saccharomyces cerevisiae. It was shown that, although there are some gaps in the data, hycanthone and IA-6 are mutagenic at pH 7.0, hycanthone is mutagenic at 5.9, and none of the other compounds is mutagenic at either pH. (Because mutagenicity of these compounds at pH 7.0 appears to be related to the presence of a methoxy group at position 5 of the polycyclic ring, it is possible that IA-4 will be mutagenic on yeast when it is tested at pH 7.0.) An excision-repair-deficient strain of yeast is no more sensitive than other strains. It was found from time-concentration studies on lethality that an inverse relation held: cells exposed to a mutagenic compound are more sensitive when time of exposure was varied and concentration of the compound was held constant, and cells exposed to a nonmutagenic compound are more sensitive when concentration is varied and time of exposure held constant. When the compounds were tested on growing cells of yeast in rich media, none of the compounds is mutagenic, although some are lethal. The kinetic behavior in reversion of yeast exposed to these compounds shows marked departures from similar reversion studies where yeast is exposed to radiation, implicating different physiological mechanisms for the alteration of responses of yeast cells exposed to the different mutagens.

Indazoles

[The urinary mutagenicity test in monitoring exposure to aromatic polycyclic hydrocarbons in workers in the aluminum industry].

The sensitivity of 3 urinary mutagenicity tests was assayed: the plate test, the fluctuation test and the micropreincubation test, in order to assess their possible use in monitoring human exposure to polycyclic aromatic hydrocarbons (PAH). Urine samples from workers of an anode production plant exposed to coal tar and from psoriatic patients undergoing treatment with coal-tar ointments were tested for mutagenic activity on strain TA98 Salmonella typhimurium, in the presence of the microsome fraction and deconjugating enzymes. Parallelly, the urinary concentration of PAH metabolites or one of their trace metabolites, 1-hydroxypyrene, was determined. Increased levels of PAH metabolites were observed in the urine of anode production workers after a work shift compared with controls. Results of the plate test and the fluctuation test performed on urine of exposed subjects, both smokers and nonsmokers, showed mutagenicity values similar to the controls. Much higher 1-hydroxypyrene concentrations were found in the urine of psoriatic patients treated with coal tar than in post-shift urine of anode production workers. The urine of the former was also mutagenic in the 3 mutagenicity tests used. The minimum mean dose of PAH metabolites was calculated, expressed as quantity of 1-hydroxypyrene, that would give a mutagenic response in the 3 tests: the micropreincubation test was found to be about 100 times more sensitive than the plate test and about 30 times more sensitive than the fluctuation test. The theoretical minimum urinary concentration of 1-hydroxypyrene detectable by each test was determined: the micropreincubation test was 15 times more sensitive than the plate test and 7 times more sensitive than the fluctuation test.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum

Mutagenicity tests of diflubenzuron in the micronucleus test in mice, the L5178Y mouse lymphoma forward mutation assay, and the Ames Salmonella reverse mutation test.

Diflubenzuron, one of a new class of pesticides believed to act via inhibition of chitin synthesis in the developing insect cuticle, was tested for possible mutagenic activity using the micronucleus test in mice, the L5178Y mouse lymphoma forward mutation test at the thymidine kinase locus, and the Ames Salmonella/microsome reverse mutation test. No mutagenic effect was found.

Animals

[Mutagenicity testing of irradiated laboratory animal feed in the 'host-mediated' assay with Salmonella typhimurium G 46].

Food irradiated with 10 MeV-electrons (dose: 4-5 Mrad) was tested for mutagenic effects, using the host-mediated assay. Irradiated 'Altomin' (a pelleted laboratory diet) was fed to mice for 9 to 44 days. After the 30th day of feeding, the animals additionally received irradiated glucose-solution instead of drinking water. Results did not indicate any mutagenic activity of the irradiated diet on the histidine-auxotroph strain of Salmonella typhimurium used in the assay.

Animals

[Mutagenicity test of antithyroid agent, methimazole--dominant lethal mutation test on male mice (author's transl)].

Mutagenicity test of Methimazole (MMI) was performed by means of dominant lethal mutation test in the male mice. Male mice were treated with a single s.c. injection of 45 mg/kg or 90 mg/kg MMI. Mean body weights were slightly decreased and mating rates were low immediately after treatment of MMI. Mean numbers of living implants at any periods examination up to 6 weeks after the treatment were compared with Salin Control, indicating lack of dominant lethality of MMI. On the other hand, EMS and MMC known mutagens and reference agents used in the present study, induced dominant lethalities at a single s.c. injection respectively.

Animals

Testing mutagenic properties with the dominant lethal test on the male mouse.

Mytagecity studies were carried out with fluorescent whitening agents (FWAs) using the dominant lethal test on male mice. Own tests with five FWAs, and those of KEPLINGER, et al. (Toxicol. Appl. Pharmacol.27: 494-506, 1974), with four FWAs, are described. In our tests, acute oral administration of five FWAs at a dose of 5000 mg/kg body weight gave no evidence of a mutagenic effect during 8 weeks' mating. The FWAs used were three bis(triazinylamino)stilbenedisulfonic acid derivatives and a 1,3-diphenyl-2-pyrazoline derivative. The results of the tests carried out by KEPLINGER, et al. showed that intraperitoneal injection of the four FWAs produced no mutagenic effect during six weeks' mating; the whiteners used were a triazolylstilbenemonosulfonic acid derivative (50 mg/kg), two bis(triazinylamino)stilbenedisulfonic acid derivatives (50 mg/kg) and a bis(sulfostyryl)biphenyl derivative (10 mg/kg).

Animals

Mutagenicity tests on anthelmintics: microsomal activation of viprynium embonate to a mutagen.

Eight anthelmintic preparations readily available in Australia were tested for mutagenicity in the Salmonella typhimurium test system. A slightly modified version of the procedure recommended by Ames et al. [2] was adopted, in that the test samples were placed in "wells" cut out of the agar of a plate previously seeded with the appropriate tester strain. Addition of a mixture of rat liver microsomal enzymes and appropriate co-factors ("S-9 mix") to one of the two wells on a single plate allowed a possible requirement for metabolic activation to be recognised. Using this procedure, viprynium embonate was found to be non-mutagenic. It was however, activated by the rat liver microsome preparation to a mutagen capable of causing both base-pair substitution (detected with strain TA100) and frameshift (detected with strain TA98) mutations. The other seven compounds tested all gave negative results in this system.

Animals

Salmonella mutagenicity tests: V. Results from the testing of 311 chemicals.

311 chemicals were tested under code, for mutagenicity, in Salmonella typhimurium; 35 of the chemicals were tested more than once in the same or different laboratories. The tests were conducted using a preincubation protocol in the absence of exogenous metabolic activation, and in the presence of liver S-9 from Aroclor-induced male Sprague-Dawley rats and Syrian hamsters. Some of the volatile chemicals were also tested in desiccators. A total of 120 chemicals were mutagenic or weakly mutagenic, 3 were judged questionable, and 172 were non-mutagenic. The remaining 16 chemicals produced different responses in the two or three laboratories in which they were tested. The results and data from these tests are presented.

Animals

Bile acids: co-mutagenic activity in the Salmonella-mammalian-microsome mutagenicity test: brief communication.

Of 30 bile acids tested, none was mutagenic in the Salmonella-mammalian-microsome test with indicator strains G46, TA1530, TA1535, TA1536, TA1537, TA1538, TA98, or TA100. However, when lithocholic acid or one of its conjugates was tested with suboptimal amounts of 2-aminoanthracene and phenobarbital-stimulated rat liver homogenate, enhancement and co-mutagenesis were observed if TA1538 was the indicator strain.

Animals

Comparative in vivo mutagenicity testing by SCE and micronucleus induction in mouse bone marrow.

The treatment of mice with repeated injections of BUdR and FUdR allows for the demonstration of differentially stained metaphases from bone marrow after FPG (fluorescence plus Giemsa; Perry and Wolff, 1974) treatment. Thus, it is possible to determine the number of SCE's under in vivo conditions, which appears as a very promising system for mutagenicity testing. We studied the response of this system in comparison to the micronucleus test using six mutagenic agents: triaziquone, cyclophosphamide (CP), dimethylphenyltriazene (PDMT), methylnitronitrosoguandine (MNNG), dimethylnitrosamine (DMNA), and diethylnitrosamine (DENA). With the exception of MNNG and DENA, all these agents induce both, SCE and micronuclei, MNNG and and DENA being ineffective in both systems. The most potent SCE-inducing agent was triaziquone, followed by PDMT, CP, and DMNA. The quantitative comparison indicates that SCE are induced at 1/10-1/100 of the concentrations which are required for the detection of micronuclei.

Animals