Induce Base-pair Substitutions Research Articles

Oxidative stress, mutagenic effects, and cell death induced by retene

Retene (RET) is the most abundant polycyclic aromatic hydrocarbon (PAH) released upon burning of cellulose, although it is not considered as one of the priority PAHs and is not included for risk assessments by the US Environmental Protection Agency (US-EPA). There are only a few studies concerning the toxic effects of RET. To the best of our knowledge, this study is the first one to examine whether RET, in an environmental concentration, plays a crucial role in the induction of oxidative stress in A549 lung cell line, and its consequence as such as mutagenicity and cell death. Our results revealed that RET was able to significantly decrease cell viability only at 72 h of exposure, increase oxidative stress, mitochondrial membrane potential and mitochondrial contents, leading an increased reactive oxygen species (ROS) production. Mutagenic activity was not detected in Salmonella strains, suggesting that RET does not induce base-pair substitution (TA100), frameshift (TA98 and TA97a) and transition/transversion (TA102) mutations. However, exposure to RET led to a significant increase in micronuclei (MN), nucleoplasmic bridges (NPBs), and nuclear buds (NBUDs) frequency, as well as cell death, mainly due to necrosis. Taken together, the results of our study provide new evidence suggesting that RET promotes oxidative stress, contributes to the processes of genomic instability, and favors necrosis. Thus, we highlight the importance of including RET in routine environmental analyses in the future as a potential risk factor involved in complex diseases and carcinogenesis.

Gamma-Decanolactone Improves Biochemical Parameters Associated with Pilocarpine-Induced Seizures in Male Mice.

Gamma-decanolactone (GD) is a monoterpene effective against seizures induced by pentylenetetrazole. The mechanism of action of GD is likely to be via glutamate antagonism. GD also inhibits intracellular reactive oxygen species (ROS) generation and the lipopolysaccharide-induced expression of inducible nitric oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-α) in vitro. Considering the neuropharmacological profile of GD studied so far, we investigated the effect of intraperitoneal administration of GD 100 and 300 mg/kg on pilocarpine (PIL)-induced status epilepticus (SE) in mice. GD was administered 30 min before PIL. Behavioral (latency to first seizure and the percentage of clonic forelimb seizures), biochemical, and oxidative stress parameters were evaluated. DNA damage in the cerebral cortex of mice was assessed using the comet assay and mutagenic activity of GD was evaluated using Salmonella/microsome assay in TA100, TA98, TA97a, TA102, and TA1535 strains, with and without metabolic activation (S9 mix). The behavioral results showed that only the latency to the first clonic seizure increased in the groups treated with GD 300 mg/kg, but not when the animals received GD 100 mg/kg. Both GD doses were able to increase superoxide dismutase and catalase activities, inducing a decrease in ROS and nitrite production and in DNA damage in the cerebral cortex. GD was not able to induce base pair substitution and frameshift mutations in the absence or in the presence of metabolic activation. These findings demonstrate that GD does not improve behavioral parameters in the PIL model, but it was able to protect seizure-related oxidative stress and DNA damage in mice, without inducing gene mutations.

AN INVESTIGATION OF MUTAGENIC ACTIVITIES OF SOME 9- SUBSTITUEDPHENANTHRENE DERIVATIVES WITH AMES / SALMONELLA / MICROSOME TEST

In this study, three different 9-Substituted phenantrene derivatives that were synthesized to be used as basic matter for drugs were tested for their mutagenic potency in strains TA 98 and TA 100 of Salmonella typhimurium by using Ames test. Therefore, both strains were tested in the absence or presence of S9 metabolic activation, for five different doses of each test substances in two paralel independent experiments. In the absence of metabolic activation, while only one of the compounds were causing frame-shift mutations, two of them were determined to induce base pair substitution mutations. In the presence of metabolic activation, while two of the compounds were mutagenic for TA 98, base pair substitution mutations were not detected for any of the substances. Each of the compounds tested were found to be mutagenic for at least one strain in the presence or absence of S9.

SINGLE-DOSE ORAL ACUTE TOXICITY AND MUTAGENIC EFFECTS OF METHANOL EXTRACTS OF CIRSIUM JAPONICUM

ABSTRACT The purpose of this study was to evaluate safety on Cirsium japonicum extracts containing flavones by examining acute oral toxicity, bacterial reverse mutation and the chromosome aberration test. Mutagenicity of extracts were evaluated by a bacterial reverse mutation assay using Salmonella typhimurium TA98, TA100, TA102, TA1535, TA1537 and Escherichia coli (WP2uvrA) with and without metabolic activation. An in vitro chromosome aberration test in Chinese hamster lung cells was conducted at the concentrations of 0, 1,250, 2,500 and 5,000 µg/mL. No significant adverse effects on body weight, mortality and gross findings were observed for 15 days after a single dose (2,000 mg of extracts/kg body weight) of administration. In the bacterial reverse mutation assay, C. japonicum extracts ranging from 156 to 5,000 µg/plate did not induce base-pair substitution or frame shift. Any significant increase in structural aberration as well as reduction of cell cycle progression was not observed in the chromosome. PRACTICAL APPLICATIONS Cirsium japonicum extracts are being developed as functional ingredients in dietary supplements due to their biological activities. However, studies on their safety evaluation are limited. In this study, we revealed that methanol extracts ofC. japonicum including apigenin and luteolin did not induce acute toxicity and mutagenicity. All of the results suggest that methanol extracts of C. japonicum may be useful substances for application of dietary supplements.

Mycotoxin T-2 of Fusarium tricinctum and chromosome changes in Chinese hamster bone marrow.

HereditasVolume 93, Issue 2 p. 329-332 Open Access Mycotoxin T-2 of Fusarium tricinctum and chromosome changes in Chinese hamster bone marrow HANNU NORPPA, HANNU NORPPA Institute of Occupational Health, Helsinki, FinlandSearch for more papers by this authorMERJA PENTTILÄ, MERJA PENTTILÄ Institute of Occupational Health, Helsinki, FinlandSearch for more papers by this authorMARJA SORSA, Corresponding Author MARJA SORSA Institute of Occupational Health, Helsinki, FinlandInstitute of Occupational Health, Haartmaninkatu I, SF-00290 Helsinki 29, FinlandSearch for more papers by this authorEEVA-LIISA HINTIKKA, EEVA-LIISA HINTIKKA College of Veterinary Medicine, Helsinki, FinlandSearch for more papers by this authorTAINA ILUS, TAINA ILUS Technical Research Centre of Finland, Helsinki, FinlandSearch for more papers by this author HANNU NORPPA, HANNU NORPPA Institute of Occupational Health, Helsinki, FinlandSearch for more papers by this authorMERJA PENTTILÄ, MERJA PENTTILÄ Institute of Occupational Health, Helsinki, FinlandSearch for more papers by this authorMARJA SORSA, Corresponding Author MARJA SORSA Institute of Occupational Health, Helsinki, FinlandInstitute of Occupational Health, Haartmaninkatu I, SF-00290 Helsinki 29, FinlandSearch for more papers by this authorEEVA-LIISA HINTIKKA, EEVA-LIISA HINTIKKA College of Veterinary Medicine, Helsinki, FinlandSearch for more papers by this authorTAINA ILUS, TAINA ILUS Technical Research Centre of Finland, Helsinki, FinlandSearch for more papers by this author First published: December 1980 https://doi.org/10.1111/j.1601-5223.1980.tb01372.xAboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume93, Issue2December 1980Pages 329-332 ReferencesRelatedInformation

Induction of frameshift and base pair substitution mutations by the major DNA adduct of the endogenous carcinogen malondialdehyde.

Instability of repetitive sequences is a hallmark of human cancer, and its enhancement has been linked to oxidative stress. Malondialdehyde is an endogenous product of oxidative stress that reacts with guanine to form the exocyclic adduct, pyrimido[1,2- alpha]purin-10(3H)-one (M1G). We used site-specifically modified single- and double-stranded vectors to investigate the mutagenic potential of M1G in bacteria and mammalian cells. M1G induced frameshift mutations (-1 and -2) when positioned in a reiterated (CpG)4 sequence but not when positioned in a nonreiterated sequence in Escherichia coli and in COS-7 cells. The frequency of frameshift mutations was highest when M1G was placed at the third G in the sequence. M1G induced base pair substitutions at comparable frequencies in both sequence contexts in COS-7 cells. These studies indicate that M1G, an endogenously generated product of oxidative stress, induces sequence-dependent frameshift mutations and base pair substitutions in bacteria and in mammalian cells. This finding suggests a potential role for the M1G lesion in the induction of mutations commonly associated with human diseases.

Rapid analysis of base-pair substitutions induced by mutagenic drugs through their oxygen radical or epoxide derivatives

Among the drugs that induce base-pair substitution mutations in the Salmonella reversion assay are the nitric oxide (NO)-delivery drug, diethylamine NONOate (DeaNO), and the ovarian cancer chemotherapeutic drug, treosulphan (TE). The present study compared the mutation spectra generated by DeaNO and TE in the hisG46 strains, TA1535 and TA100, the hisG428 strain, TA102, and the six Ames II™ 7000 series strains. Using these strains, it was feasible to conduct rapid analysis of the type and magnitude of induced mutation without resorting to DNA amplification and sequencing. A putative hydrolysis product of TE, 1,2:3,4-diepoxybutane (DEB), and hydrogen peroxide (H 2O 2) were included in the study to allow for further comparisons between epoxide-induced damage and that induced by the hydroxyl radical. TE (0.93 μmole/pl) induced 16.8-fold-over-background reversion or a mutagenicity ratio (MR) of 16.8 in TA1535. The response was weaker in TA100 (MR of 3), and negative in strain TA102. Only two Ames II™ strains demonstrated sensitivity to TE, and they were TA7004 (CG:AT) and TA7005 (GC:AT). Like TE, DeaNO (33 μmole/pl) was mutagenic in TA1535 (MR of 24.6), TA100 (MR of 5.3), TA7004 (MR of 13.7), and TA7005 (MR of 7.7), and non-mutagenic in TA102. These results showed a preferential sensitivity to reversion of the CCC target in TA100 and TA1535, and a lack of sensitivity to reversion of the TAA target in TA102. In addition, they elucidated the selectivity of the Ames II™ strains, with AT targets showing little or no sensitivity to reversion. The TE-epoxide derivative DEB was mutagenic in TA1535 and TA7004, but in contrast to TE, DEB was mutagenic in TA102. Interestingly, TA102 was reverted by DEB and H 2O 2 but not by TE or DeaNO. This study showed that analysis of mutations is achievable using the battery of strains listed above. The fact that DNA damage can be detected by reversion at specific bases offers a tool for understanding the mechanisms through which drugs may exert their DNA and cellular damage.

Activation of arylamines to mutagenic product(s) by two in vitro plant systems

Plant activation of three isomers of phenylenediamine, o-, m- and p-phenylenediamine, has been studied. Two in vitro plant systems have been used: Persea americana S117 with mixed-function oxidase (MFO) and peroxidase activities, and Zea mays S9 which contains only peroxidase activity. As genetic endpoint, the classical Salmonella tester strains, TA98 and TA100, their derivatives with high O-acetyltransferase levels (YG1024 and YG1029, respectively) and TA98/1,8-DNP 6, deficient in this enzyme, have been assayed. Of the three isomers studied, only m-PDA was activated to mutagenic product(s) by both plant systems. This activation required the bacterial O-acetyltransferase activity to give frameshift mutagenic product(s), detected in TA98 and YG1024 strains. In all the assays the P. americana system was more potent than the Z. mays system in activating m-PDA. A slight increase of the number of YG1029 revertants was detected when m-PDA was activated by P. americana, suggesting that this compound can be also converted into ultimate mutagenic product(s) that induce base-pair substitutions. m-PDA activation by Z. mays was dependent on the peroxidase activity of this system, but the activation produced by P. americana was totally dependent on MFOs, because a total inhibition of the mutagenic response was found when these activities were inhibited. In addition, the P. americana system was more potent in generating proximal mutagenic forms from m-PDA than S9 from non-induced rat liver, although S9 from Aroclor 1254-induced Sprague-Dawley male rats was the most potent system in the m-PDA activation. These results indicate that the P. americana system can be useful in determining the role of mixed-function oxidases in plant activation of xenobiotics.

Mutagenic analysis of 2,3-diaminophenazine and 2-amino-3-hydroxyphenazine in Salmonella strains expressing different levels of O-acetyltransferase with and without plant and mammalian activation

2,3-Diaminophenazine (DAP) and 2-amino-3-hydroxyphenazine (AHP) are products generated from oxidative-type phenylenediamine hair dyes and are also present in pesticide formulations as contaminants. Earlier studies demonstrated that DAP and AHP were mutagenic in Salmonella typhimurium strains after mammalian microsomal activation. Plant systems can activate structurally similar arylamines. S. typhimurium strains have been developed that express elevated levels of acetyl-CoA: N-hydroxyarylamine O-acetyltransferase (OAT). O-acetyltransferase expression is necessary for the generation of the ultimate arylamine promutagen after plant activation. A number of arylamines including 2-aminofluorene, benzidine and 4-aminobiphenyl were activated by plant cells into mutagens in the OAT over-expressing S. typhimurium strain, YG1024. The objectives of this research were to examine the mutagenicity of DAP and AHP with mammalian or plant activation in Salmonella strains with different acetyltransferase activities. The hypothesis tested was whether and to what degree a metabolite of DAP or AHP could serve as a substrate for bacterial O-acetyltransferase and induce mutation in Salmonella. DAP and AHP without activation induced both frameshift and base pair substitution mutations in S. typhimurium strains that exhibited elevated levels of O-acetyltransferase activity. The mutagenicity of DAP and AHP were greatly enhanced with mammalian hepatic microsomal activation resulting in a preferential induction of frameshift mutations. With the hisD3052 allele as the gene target, S9-activated DAP induced frameshift mutations in YG1024 and TA98 as well as the OAT deficient strain TA98/1,8-DNP 6. S9-activated AHP induced mutation only in the OAT over-expressing strain, YG1024. With the hisG46 allele, O-acetyltransferase activity was necessary for the metabolism of DAP and AHP to products that induce base pair substitution mutations. An intriguing finding of this work was the

Comparative study on Salmonella mutagenicity and on cytogenetic and antineoplastic effects induced by cyclophosphamide and 3-aminobenzamide in cells of three transplantable tumours in vivo

Synergistically enhanced sister chromatid exchange (SCE) frequency by cyclophosphamide (CP) was observed when L1210 lymphoid tumor cells were exposed in vivo to a non-toxic concentration of 3-aminobenzamide (3-AB). Additive effects in SCE induction in vivo were observed when either Ehrlich ascites tumor (EAT) cells or P388 lymphocytic leukemia cells treated with CP were exposed to 3-AB in vivo. 3-AB enhanced the survival time of L1210 tumor bearing BDF1 mice treated with CP. However, the combined CP plus 3-AB treatment did not increase the survival of either EAT BALB/c- or P388 BDF1-tumor bearing mice compared with the effect on survival by CP alone. Therefore the in vivo differential antitumor effect, by CP in conjunction with 3-AB, appears to correlate well with the in vivo differential effect on cytogenetic damage caused by the combined CP plus 3-AB treatment. In the Salmonella typhimurium/mammalian microsome test CP appears to have a dose dependent ability to induce base-pair substitutions in strains TA 100 and TA 1535 and frameshift mutations in strains TA 98 and TA 1537. Both types of mutation were synergistically increased in the presence of 3-AB.

Mutagenicity of four homo-aza-steroidal esters of m- N, N-bis(2-chloroethyl)aminocinnamic acid in the Ames test

Four new chemicals, the homo-aza-steroidal esters of m- N, N-bis(2-chloroethyl)aminocinnamic acid, originaly synthesized to be used as antineoplastic agents, were tested for their mutagenic activity in the Ames test. 3β-Hydroxy-13α-amino-13,17-seco-5-androsten-17-oic-13,17-lactam ester (ACALE3) and 3α-hydroxy-13α-amino-13,17-seco-5α-androstan-17-oic-13,17-lactam ester of m- N, N-bis(2-chloroethyl)aminocinnamic acid (ACALE4) were found to induce base-pair substitutions, causing dose-dependent increases in his + revertants in strains TA100 and TA1535, while no dose-dependent relations were established when 3β-hydroxy-13α-amino-13,17-seco-5α-androstan-17-oic-13,17-lactam ester (ACALE1) and 17β-hydroxy-3-aza-A-homo-4α-androsten-4-one ester of m- N, N-bis(2-chloroethyl)aminocinnamic acid (ACALE2) were tested. The presence of metabolic activation enzymes in the test system had no effect in his + revertants in strains TA100 and TA1535. The chemicals tested although having the same alkylating moiety and a similar chemical structure exhibited different mutagenic activities.

Comparative study on the mutagenicity of three structurally related substituted aniline mustards in the Salmonella/microsome assay

The ortho, meta and para isomers of N, N-bis(2-chloroethyl)aminocinnamic acid were tested for their ability to mutate Salmonella typhimurium strains in the Salmonella/microsome mutagenicity test. The aim of the work was to establish a structure-activity relationship between these three isomers. The drugs were found to induce base-pair substitutions, causing dose-dependent increases in his + revertants, in strains TA100 and TA1535. The study showed that the position of the substituent groups influenced the mutagenic activity of the compounds. The ortho isomer exhibited a poorer mutagenic effect than meta and this was found to be a weaker mutagen than para. The presence of metabolic activation enzymes in the test system induced a further increase in his + revertants, in strains TA100 and TA1535, which is consistent with the findings for melphalan, a cancer chemotherapeutic agent with a chemical structure similar to that of the isomers tested.

Mutagenic activity of the antitumour agent homo-aza-steroidal ester of p-N,N-bis(2-chloroethyl)aminophenoxyacetic acid (NSC 294859) in the Salmonella/microsome assay.

The mutagenic activity of the new antitumour agent 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam- p-N,N-bis(2-chloroethyl)aminophenoxyacetate (NSC 294859) was studied in the Salmonella/microsome assay. It was found to induce base pair substitutions, causing dose-dependent increases in his+ revertants in strains TA100 and TA1535. The alkylating moiety, p-N,N-bis(2-chloroethyl)-aminophenoxyacetic acid, was shown to be less effective than the parent compound, while the modified steroid moiety, 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam, showed no mutagenic effect in all strains used. The presence of metabolic activation enzymes in the test system induced a further increase in his+ revertants in strains TA100 and TA1535, in both the parent compound and the alkylating moiety of the parent compound, while it had no effect in the case of the steroidal lactam.

Mutation spectra of the two guanine adducts of the carcinogen 4-nitroquinoline 1-oxide in Escherichia coli. Influence of neighbouring base sequence on mutagenesis.

When the chemical carcinogen 4-nitroquinoline 1-oxide binds to DNA in vitro, two major adducts are formed, both at guanine residues, but at different positions, i.e. the C8 or the N2 position. Well-defined adducts (either C8 or N2 guanine adducts) can be formed in vitro by reacting DNA with 4-actoxyaminoquinoline 1-oxide (Ac-4HAQO) under different reaction conditions. Forward mutations induced by each of both main 4NQO adducts in the tetracycline resistance gene of pBR322 were determined. In total, 30 independent 4NQO-induced mutations were characterized, showing mainly base-pair substitution mutations and some frameshift mutations. We have observed that the 5' neighbouring base influences the specificity of dGuo-N2-AQO induced base-pair substitutions mutagenesis; a similar effect does not occur with dGuo-C8-AQO. This study reveals the importance of the N2 guanine adduct in the mutagenesis induced by 4NQO in vivo.

First characterization of the mutagenic specificity of 7-methoxy-2-nitronaphtho[2,1- b]furan (R7000) in Salmonella typhimurium

In order to investigate the mutational events induced by the very potent genotoxic agent 7-methoxy-2-nitronapthol[2,1- b]furan (R7000), we evaluated its mutagenic potency in a battery of his − mutants of Salmonella typhimurium designed to study mutagenic specificity (Levin and Ames, 1986). Using this system we could show that R7000 is able to induce base-pair substitutions, mainly GC → TA transversions and, perhaps to a lower extent, AT → TA transversions. In addition, our results suggest that this chemical may be a very efficient inducer of base-pair deletions/insertions resulting in frameshifts. Whereas the induction of base-pair susbtitutions by R7000 is dependent on the presence of plasmid pKM101 carrying the mucA,B operon, the induction of base-repair deletions/insertions is independent of the presence of the plasmid.

Genotoxicity studies on the organophosphorus insecticide chloracetophone

Chloracetophone ( O, O-dimethyl-2,2,2-trichloro-1-(chloroacetoxy)phosphonate), a new insecticide of the organophosphorus group of pesticides, was tested for genotoxicity in a variety of systems with different genetic end-points and varying parameters. The test systems included 2 microbial systems, Salmonella and Aspergillus for point mutations and mitotic segregation, respectively, and human lymphocyte cultures and mammalian bone marrow cells (from rats and hamsters treated acutely and subacutely) for chromosomal aberrations and micronuclei. Chloracetophone was negative in Aspergillus at concentrations of 1–500 μg/ml, in human lymphocyte cultures at concentrations of 2.5–40 μg/ml, in rats at doses of 420–21 mg/kg b.w. and in hamsters at doses of 210–42 mg/kg b.w. for chromosomal aberrations. It did not cause any increase of micronuclei in human lymphocytes and rat bone marrow cells but did cause a significant increase in hamster bone marrow cells. Chloracetophone induced base-pair substitutions in strain TA100 of Salmonella with and without metabolic activation at a concentration range of 2000 6000 μg/plate.

Bacterial genotoxicity of nitrosated famotidine.

Famotidine, a histamine H2-receptor antagonist, was devoid of mutagenic activity in seven his- Salmonella typhimurium strains (TA1535, TA1537, TA1538, TA97, TA98, TA100 and TA102) and was equitoxic in repair-proficient (WP2) and repair-deficient (WP2uvrA, WP67, CM561, CM571, WP100 and CM871) Escherichia coli strains, both in the presence and in the absence of S9 mix containing liver S9 fractions from Aroclor-treated rats. However, after a short pre-incubation step with nitrite in an acidic environment, the drug increased, by a direct mechanism, the number of his+ revertants in Salmonella strains TA100, TA102 and TA97 (a decrease of mutagenicity being conversely observed in TA1535) and of trp+ revertants in E. coli strains WP2uvrA and WP67. Moreover, it enhanced the induction of non-reparable DNA damage in E. coli strains simultaneously lacking the uvrA-dependent excision repair and the lexA post-replication repair pathways. The mutagenicity of acidified nitrite-famotidine mixtures was related to doses of both precursors, with a maximum production of mutagenic derivatives in a slight molar excess of nitrite. The optimal pH of the nitrosation reaction (2.0) was intermediate between the one required for cimetidine (1.5) and ranitidine (2.5). Potency of famotidine as a precursor of mutagenic derivatives was considerably lower than the one of the other two H2 blockers. The nitrosation products of all three drugs mainly induced base-pair substitutions in Salmonella DNA, to a greater extent at sites containing G.C base pairs (strain TA100) in the case of famotidine and cimetidine, and at sites containing A.T base pairs (TA102) in the case of ranitidine.(ABSTRACT TRUNCATED AT 250 WORDS)

On the genotoxicity of the pesticides Endodan and Kilacar in 6 different test systems

Two pesticides, the fungicide Endodan (ethylene thiuram monosulphide) and the insecticide-acaricide Kilacar (bis(parachlorophenyl)cyclopropyl methanol), produced or used in the neighbouring countries of Bulgaria and Greece were investigated in a coordinated research programme for their genotoxic effects in a variety of test systems. This included the Ames test, Aspergillus nidulans for mitotic segregation, in vitro human lymphocyte cell cultures for SCE and chromosomal aberrations, in vivo bone marrow cells in hamsters and rats and the dominant lethal test in rats. The genotoxicity of Endodan was found to range from negative to slightly positive in different test systems. At concentrations of 7.5 and 12.0 μg/plate together with S9 mix it induced base-pair substitutions in the TA100 strain of Salmonella typhimurium at a rather low level. At a dose of 93 mg/kg b.w. it also caused chromosomal aberrations in acutely treated hamster bone marrow cells. A significant increase of SCE was also found in human lymphocyte cultures at a concentration of 20.0 μg/ml. Endodan was found to be negative in A. nidulans for somatic segregation, lymphocyte cultures for chromosomal aberrations and mitotic activity and in rats for dominant lethals and chromosomal aberrations. Kilacar was found to be a weak mutagen in the TA97 strain of S. typhimurium at concentrations of 2.5 and 5.0 μg/plate together with S9 mix. At concentrations of 1.0, 1.5 and 2 μg/ml Kilacar increased the number of mitotic segregants in A. nidulans by 160%, 220% and 156% respectively over the control. In Syrian hamster bone marrow cells after acute administration at concentrations of 0, 40, 80 and 160 mg/kg, the MI was 5.50, 4.30, 3.10 and 1.30 respectively, and an increase in chromosomal aberrations of about 300% over the control was observed with a concentration of 80 mg/kg. In human lymphocytes no significant changes were observed in either MI or SCE. In the dominant lethal test after chronic treatment of male rats at doses of 5.1, 10.2 and 102.0 mg/kg b.w. no significant mutagenic effect was found although a decrease was shown in the percentage of females with implants mated with treated males in the first week.

Mutagenicity of some intercalating agents in Chinese hamster V79 cells

ICR 170 and ICR 191, but not 9-aminoacridine or chloroquine, induced both 6-thioguanine- and, to a smaller extent, ouabain-resistance in Chinese hamster V79 cells. These results indicate that covalent binding to DNA is necessary for intercalating agents to induce mutation in this cell line, and that this assay can distinguish potential carcinogens from non-carcinogenic analogues of this chemical type. The induction of ouabain-resistance by both ICR 170 and ICR 191 indicates that these frameshift mutagens induce base-pair substitution to some extent in V79 cells.

The capacity of some nitro- and amino-heterocyclic sulfur compounds to induce base-pair substitutions

The capacity of 27 heterocyclic sulfur compounds to induce base-pair substitutions was investigated with Klebsiella pneumoniae ur − pro − and Salmonella typhimurium TA100 as test organisms. Among the compounds tested, all sulfur compounds with nitro groups and some thiazoles with an amino group were mutagenic. Among the nitrothiazoles, the most potent mutagen was niridazole, followed by 2-acetamido-5-nitrothiazole, 2-bromo-5-nitrothiazole, N-(5-nitrothiazol-2-yl)benzamide, and 2-amino-5-nitrothiazole. Of the nitrothiophenes, 2-nitrothiophene was more mutagenic than 3-nitrothiophene and 2,4-dinitrothiophene. 4-Nitroisothiazole was also mutagenic. Of the aminothiazoles, 2-amino-5-bromothiazole and 2-amino-5-chlorothiazole were mutagenic to both test organisms. With 2-amino-5-( p-nitrophenylsulfonyl)thiazole, a mutagenic action was only found with Salmonella typhimurium TA100, whereas 2-aminothiazole and 2-amino-4-methylthiazole were only mutagenic with Klebsiella pneumoniae. With the other 13 compounds, no mutagenic activity was observed. Of the coccidiostatics, 2-acetamido-5-nitrothiazole was also mutagenic on Escherichia coli K12 and Saccharomyces cerevisiae D4 but non-mutagenic on Salmonella typhimurium TA1530, TA1535, TA1537 and TA98, while 2-amino-5-nitrothiazole was mutagenic on Escherichia coli K12, Salmonella typhimurium TA1530, TA1535 and TA98, and non-mutagenic on strain TA1537 and on Saccharomyces cerevisiae D4.