Mutagenic activity of the plant preparation KAC-81]

Mutagenic activity of vegetative preparation KAC-81 containing extracts of common wormwood and pine buds using crepis root seedlings, unicellular green alga of Chlorella indicator strains of Salmonellas TA 100, TA 1534, TA 1537, TA 50 and TA 98 as well as white mice and white rats has been studied. It is shown that the preparation caused a weak mutagenic effect on Crepis seedlings and Chlorella and no mutagenic effects on the indicator strains of salmonellas, in sex and somatic cells of mammals under single peroral action in maximally endured doses.     

Evaluation of potential mutagenic effect of the liquid smoke preparation UTP in vivo: cytogenetic analysis of mouse bone marrow

The effect of the liquid smoke preparation (UTP) on chromosomes of mouse bone marrow cells was evaluated by cytogenetic analysis. UTP Was administered to male and female mice in four concentrations: 100, 10, 1 and 0.1 ml UTP/1000 ml of drinking water continuously during 4 weeks ad libitum. The UTP concentrations used did not show any mutagenic effect during these testing conditions.     

Cytogenetic effects of 1,4-dihydropyridine in various test systems

Cytogenetic effect of 1,4-dihydropyridine was studied in different test-systems. The preparation is shown to decrease the level of complete sex-chromosome losses in Drosophila and chromosome aberration frequency in Allium fistulosum seedlings. The preparation does not affect spontaneous mutability of bone marrow cells in mice, high doses of the preparation have no mutagenic potential. Thus, 1,4-dihydropyridine shows antimutagenic activity reducing the chromosome mutation level in sex and somatic cells of eucaryotic organisms. Absence of the effect on mice chromosomes may testify to the specificity of 1,4-dihydropyridine action.     

Genotoxic effects of heavy metals and their salts in an experiment on Drosophila and mammals

Analysis of data on the influence of different metals (cadmium, cobalt, molybdenum) on the Drosophila melanogaster cells has revealed a considerable genotoxic effect of cadmium salts which manifests in the high percentage of cells elimination at the early stages of spermatogenesis--the premeiotic cells. The modifying effect of molybdenum in the combination with cadmium and molybdenum decreasing the percentage of the progeny fall may be induced by activation of the reparation systems. In the bone marrow cells of mice Cd ions modify cytogenetic effects of the AB preparation, intensifying its mutagenic activity in some cases.     

Determination of the mutagenic potential of an environmental pollutant, mercuric chloride

The effect of mercury chloride on the culture of rat fibroblast cells was studied for the test of DNA-breaks formation, for the survival and mutability of pox-virus vaccine and for the formation of dominant mutations in rats. The preparation had generally toxic, embryotoxic and mutagenic effects. To determine the genetic effects of environmental pollutants it was necessary to use some special methodological approaches.     

The mutagenicity of a new multicomponent vaccine made from the antigens of Klebsiella pneumoniae, Staphylococcus aureus, Proteus vulgaris and Escherichia coli

Inactivated bacterial vaccine, containing K. pneumoniae, S. aureus, P. vulgaris and E. coli antigenic complexes were tested for mutagenicity in the test described by Ames et al. and in vivo, in experiments on mice. In Salmonella typhimurium cells, strain TA-98 and TA-100, the preparation (5-75 mg/ml) did not increase the frequency of reversions and histidine-independence either in direct experiments or after metabolic activation with rat liver homogenate. In experiments on mice the vaccine (3.3 mg/kg and 33 mg/kg) did not induce chromosomal anomalies in spermatogonia. In all experiments the mutagens used for positive control produced a mutagenic effect.     

Aphidicolin allows a rapid and simple evaluation of DNA-repair synthesis in damaged human cells

The decrease in microbial mutagenicity of N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) and N-methyl-N-nitrosourea (MNU) was compared in an animal mediation with rats and in direct incubation with human as well as rat blood and blood components. The mutagenic activity was assayed by reverse mutation from streptomycin (SM) dependence to non-dependence in Escherichia coli, strain Sd-B (TC). The mutagenic response curves of both MNNG and MNU were approximately linear and parallel at non-cytotoxic concentrations. However, the mutagenic capabilities of MNNG were estimated to be 10-fold more potent than those of MNU. The mutagenic activity in blood and liver preparations from rats killed immediately after intravenous injection of MNNG, 50 mg/kg, was negative. Results with MNU, 100 mg/kg, were positive in both cases.For the detection of mutagenicity, blood was diluted 50 times for the final testing mixture (1 ml) to avoid bactericidal effects of the blood itself. When a larger amount of liver preparation was used in the tests, and diluted 8 times, mutagenic activity was still detected 15 min after injection of MNU, 80 mg/kg. Comparisons of the diminished rate of mutagenicity between MNNG and MNU during certain periods of incubation with blood indicated that MNNG was inactivated much more rapidly than MNU with both human and rat blood. Plasma showed a moderate inactivating effect on both MNNG and MNU. Red blood cells inactivated MNNG at a remarkably rapid rate similar to that of whole blood, but was less effective on MNU. In further experiments with red- cell components, the cell contents inactivated both MNNG and MNU at rates similar to those with red cells, but cell membrane had absolutely no effect in decreasing the mutagenicity in either MNNG or MNU.     

Cross-resistance studies with V79 Chinese hamster cells adapted to the mutagenic or clastogenic effect of N-methyl-N′-nitro-N-nitrosoguanidine

When V79 cells are exposed to a single low dose of MNNG or MNU they acquire resistance to the mutagenic or to the clastogenic effect of the agents. Here the effect of MNNG pretreatment on mutagenesis (6-thioguanine resistance) and aberration formation in cells challenged with various mutagens/clastogens is reported. MNNG-adapted cells were resistant to the mutagenic effects of MNU and, to a lower extent, of EMS. No mutagenic adaptation was observed when MNNG-pretreated cells were challenged with MMS, ENU, MMC or UV.

Cells pretreated with a dose of MNNG which makes them resistant to the clastogenic effect of this compound were also resistant to the clastogenic activity of other methylating agents (MNU, MMS), but not so with respect to ethylating agents (EMS, ENU). Cycloheximide abolished the aberration-reducing effect of pretreatment. However, when given before the challenge dose of MNNG, MNU or MMS, it drastically enhanced the aberration frequency in both pretreated and non-pretreated cells. No significant enhancement of aberration frequency by cycloheximide was found for ethylating agents.

The results indicate that clastogenic adaptation is due to inducible cellular functions. It is concluded that mutagenic and clastogenic adaptation are probably caused by different adaptive repair pathways.     

Analysis of toxic and mutagenic activities of antiherpesvirus nucleosides against HeLa cells and herpes simplex virus type 1.

The toxic and mutagenic activities of five antiherpesvirus agents to HeLa cells and herpes simplex virus type 1 (HSV-1) were investigated. 5-Iodo-2'-deoxyuridine (IDU) and 9-beta-D-arabinofuranosyl-adenine (araA) showed very potent inhibitory effects on cell growth and the cloning efficiency of HeLa cells, whereas 1-beta-D-arabinofuranosyl-E-5-(2-bromovinyl)uracil (BV-araU), E-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) and 9-(2-hydroxyethoxymethyl)guanine (ACV) showed less inhibitory effect. 50% inhibitory doses of BV-araU and BVDU for cell growth were 657 and 253 micrograms/ml, respectively. Although the growth inhibitory activity of BVDU was very weak, as above, the mutagenic activity of this drug to the cells, estimated by induction of colchicine-resistant mutants, was observed to be 4 micrograms/ml, which was a markedly smaller dose than the inhibitory dose for cell growth, and the highest frequency of mutation of the cells was shown at 100 micrograms/ml of BVDU. This activity was more potent than that of IDU. No mutagenic activity of BV-araU, araA and ACV to cells was observed within the concentration range of 1-800 micrograms/ml. IDU showed high mutagenic activity to HSV-1 growing in human embryo lung fibroblasts, and IDU-resistant mutants were induced at a high frequency. BVDU also induced a small amount of BVDU-resistant mutant virus, although this drug induced many mutant cells. No mutagenic activity of BV-araU, araA and ACV to HSV-1 was observed.     

Effect of catamine AB on the generative function and chromosome apparatus of the bone marrow cells in white rats

In a chronic experiment (6 months) performed on non-inbred white rats effect of cationic superficially active substance catamin AB on the structure and function of male and female gonads, state of the offspring and on the chromosome apparatus of the bone marrow cells has been studied. The preparation is intragastrically injected in doses 10, 1, 0.1 mg/kg. Catamin AB in the dose of 10 mg/kg produces an essential decrease in the specific mass of the testes, reduce in the spermatogenic index, increase in the canaliculi number with exfoliated epithelium, lowered mobility and diminished amount of alive spermatozoa. In the ovary amount of mature follicles becomes less and the number of atresic corpuscles and atresing follicles rises; plethora of the medullary substance occurs in the organ with signs of stasis in the venous bed. In the dose 1 mg/kg catamin AB results in less pronounced changes in the testes and does not produce any pathological disturbances in the ovaries. The preparation does not influence on mating in the test animals, but in the dose 10 mg/kg results in a decreasing fertility because of pre- and postimplantational death of embryos. The changes mentioned are connected with a total toxical effect of the preparation. Catamin AB does not possess any mutagenic effect in the doses tested.     

Induction of 6-thioguanine-resistant mutants by hyperoxia and gamma-irradiation: effect of compromising cellular antioxidant systems

Hyperoxia and gamma-irradiation were found to be mutagenic in a transformed Syrian hamster cell line in a dose-dependent manner. The frequency of resistance to 6-thioguanine increased from 10 per 10(6) survivors after 48 h of growth in 70% O2 to 32.6 (highly significant) after 75 h. Increasing the oxygen tension to 95% resulted in a significant mutagenic response in only 44 h. At equitoxic doses, gamma-irradiation was 4 times more mutagenic than 70% O2. After growth in hyperoxia, the cells showed an enhancement of catalase activity, glutathione peroxidase activity and glutathione levels but there was little effect on superoxide dismutase activity. Diethyldithiocarbamate (3 mM, 1.5 h) was mutagenic in normoxia and potentiated the mutagenic activity of both gamma-irradiation and hyperoxia. Cells thus treated showed an 855 reduction in superoxide dismutase activity. When diethyldithiocarbamate was used in conjunction with a direct-acting alkylating agent, the mutagenic response was only additive. Depletion of cellular glutathione with buthionine sulfoximine (0.2 mM) or inhibition of catalase activity with aminotriazole (100 mM) was also effective in potentiating the mutagenic response of gamma-irradiation and hyperoxia. The data demonstrates that endogenously produced activated oxygen species are mutagenic to hamster cells in culture and suggest that aerobic organisms are subject to an unavoidable background risk due to living in an oxygen atmosphere.     

Genotoxicity of aminohydroxynaphthoquinones in bacteria, yeast, and Chinese hamster lung fibroblast cells

There are few studies on the biological activity of aminohydroxy derivates of 1,4-naphthoquinone (1,4-NQ) on prokaryotic and eukaryotic cells. We determined the mutagenic activity of 5-amino-8-hydroxy-1,4-naphthoquinone (ANQ) and 5-amino-2,8-dihydroxy-1,4-naphthoquinone (ANQ-OH) as compared to the unsubstituted 1,4-NQ in Salmonella/microsome assay. Potential mutagenic and recombinogenic effects and cytotoxicity were analyzed in haploid and diploid cultures of the yeast Saccharomyces cerevisiae. In Salmonella/microsome assay, 1,4-NQ was not mutagenic, whereas aminohydroxynaphthoquinones were weakly mutagenic in TA98 and TA102 strains. In haploid yeast in stationary growth phase (STAT), mutagenic response was only observed for the hom3 locus at the highest dose. In diploid yeast, aminohydroxynaphthoquinones did not induce any recombinogenic events, but 1,4-NQ was shown to be a recombinogenic agent. These results suggest that aminohydroxynaphthoquinones are weak mutagenic agents only in prokaryotic cells. The cytotoxicity of 1,4-NQ in yeast stationary cells was more significant in diploid cells as compared to that observed in haploid cells. However, ANQ and ANQOH were slightly cytotoxic in all treatments. Genotoxicity of these naphthoquinone compounds was also determined in V79 Chinese hamster lung fibroblast cells using standard Comet, as well as modified Comet assay with the bacterial enzymes formamidopyrimidine DNA-glycosylase (FPG) and endonuclease III (ENDOIII). Both 1,4-NQ and ANQ induced pronounced DNA damage in the standard Comet assay. The genotoxic effect of ANQ-OH was observed only at the highest dose. In presence of metabolic activation all substances showed genotoxic effects on V79 cells. Post-treatment of V79 cells with ENDOIII and FPG proteins did not have a significant effect on ANQ-OH-induced oxidative DNA damage as compared to standard alkaline Comet assay. However, all naphthoquinones were genotoxic in V79 cells in the presence of metabolic activation and post-treatment with enzymes, indicating that all compounds induced oxidative DNA damage in V79 cells. Our data suggest that aminohydroxynaphthoquinone pro-oxidant activity, together with their capability of DNA intercalation, have an important role in mutagenic and genotoxic activities.     

Mechanism of the lethal and mutagenic effects of phenoxyacetic acids in Saccharomyces cerevisiae

MCPA and salicylic acid, two compounds with similar structures and almost the same dissociation pattern, were tested for lethal and mutagenic effects on, and uptake by, cells of Saccharomyces cerevisiae strain red18. The results obtained with the two compounds were similar, suggesting a common mechanism of action. It is proposed that they act by increasing the concentration of hydrogen ions within the cell, so that killing and mutation occur. Mutations were induced only when killing reached 95–99%. The compounds are considered weak mutagens for yeast cells. The methyl ester of MCPA also induced killing and reverse mutation, but only at concentrations about 100 times higher than for the undissociated acid. MCPA methyl ester did not increase the number of revertants in the Salmonella/liver microsome test. It is suggested that the effects of the methyl ester of MCPA depends on the ester being hydrolysed to the acid by yeast cells and the liver microsome preparation.     

Mutagenic effect of chemical compounds on laboratory mice]

Mutagenic effect of thioTEPA applied at a dose of 1.25 mg/kg was studied in late spermatids of C57BL/L male mice. The mutagen induced dominant lethal mutations in germ cells (39%) and symmetric translocations in 33.5% of F1 male offspring. The common frequency of sperms with chromosome mutations was 60%, that is ten times as much as the mutagenic effect in bone marrow cells. 39% of embryos at 3.5 days of development died or delayed their development at 2--22 blastomers stages. Structure chromosome aberrations were found in the cells of such embryos. The scheme of genetical screening of chemical compounds in laboratory mice, based on the data obtained early and in the present experiment, is proposed.     

Mutagenic activity of the fungicide captan

A complex study of mutagenic activity of captan (a fungicide) in a series of standard test-systems has shown that the preparation induces gene mutations in certain Salmonella indicator strains (without metabolic activation), increases the frequency of mitotic crossing-over and gene conversion in yeasts (Saccharomyces), possesses a weak cytogenetic action on bone marrow cells in experimental animals, manifests no cytogenetic effect in the lymphocyte culture of human peripheral blood (including a system of microsomal activation). Genetic activity of captan cannot be a limiting criterion of its harmfulness.     

Mutagenicity and cytotoxicity of 2-butoxyethanol and its metabolite, 2-butoxyacetaldehyde,in Chinese hamster ovary (CHO-AS52) cells

2-Methoxyethanol (2-ME) is being substituted by 2-butoxyethanol (2-BE) as a solvent for the preparation of industrial and consumer products. Since we have shown that a metabolite of 2-methoxyethanol, methoxyacetaldehyde (MALD), is mutagenic in a subline of Chinese hamster ovary cells (CHO-AS52), we have conducted a similar study using 2-BE and its metabolite, butoxyacetaldehyde (BALD). The results indicate that 2-BE and BALD are not mutagenic to CHO-AS52 cells. However, 2-BE is more cytotoxic than 2-ME. In comparison of our study with others on glycol ethers, the data indicate that, for glycol ethers, cytotoxicity increased with chain length of the alkyl groups. For their metabolites, mutagenicity increases with reduced chain length. Therefore, we suggest that safer solvents should be developed for use in preparation of products.     

Genotoxicity of aminohydroxynaphthoquinones in bacteria, yeast, and Chinese hamster lung fibroblast cells

There are few studies on the biological activity of aminohydroxy derivates of 1,4-naphthoquinone (1,4-NQ) on prokaryotic and eukaryotic cells. We determined the mutagenic activity of 5-amino-8-hydroxy-1,4-naphthoquinone (ANQ) and 5-amino-2,8-dihydroxy-1,4-naphthoquinone (ANQ-OH) as compared to the unsubstituted 1,4-NQ in Salmonella/microsome assay. Potential mutagenic and recombinogenic effects and cytotoxicity were analyzed in haploid and diploid cultures of the yeast Saccharomyces cerevisiae. In Salmonella/microsome assay, 1,4-NQ was not mutagenic, whereas aminohydroxynaphthoquinones were weakly mutagenic in TA98 and TA102 strains. In haploid yeast in stationary growth phase (STAT), mutagenic response was only observed for the hom3 locus at the highest dose. In diploid yeast, aminohydroxynaphthoquinones did not induce any recombinogenic events, but 1,4-NQ was shown to be a recombinogenic agent. These results suggest that aminohydroxynaphthoquinones are weak mutagenic agents only in prokaryotic cells. The cytotoxicity of 1,4-NQ in yeast stationary cells was more significant in diploid cells as compared to that observed in haploid cells. However, ANQ and ANQOH were slightly cytotoxic in all treatments. Genotoxicity of these naphthoquinone compounds was also determined in V79 Chinese hamster lung fibroblast cells using standard Comet, as well as modified Comet assay with the bacterial enzymes formamidopyrimidine DNA-glycosylase (FPG) and endonuclease III (ENDOIII). Both 1,4-NQ and ANQ induced pronounced DNA damage in the standard Comet assay. The genotoxic effect of ANQ-OH was observed only at the highest dose. In presence of metabolic activation all substances showed genotoxic effects on V79 cells. Post-treatment of V79 cells with ENDOIII and FPG proteins did not have a significant effect on ANQ-OH-induced oxidative DNA damage as compared to standard alkaline Comet assay. However, all naphthoquinones were genotoxic in V79 cells in the presence of metabolic activation and post-treatment with enzymes, indicating that all compounds induced oxidative DNA damage in V79 cells. Our data suggest that aminohydroxynaphthoquinone pro-oxidant activity, together with their capability of DNA intercalation, have an important role in mutagenic and genotoxic activities.     

Mutagenic action of cadmium chloride in mammals

The mutagenic effect of cadmium chloride on somatic cells of F1 hybrid mice CBA X C57B1/6J in vivo and on an established line of CHO-ATZ-2 Chinese hamster cells in vitro has been studied. The induction of micronuclei has been demonstrated in mouse marrow cells as well as induction of point mutations at loci controlling the synthesis of hypoxanthine-phosphoribosyltransferase, thymidine kinase, adenine phosphoribosyltransferase and the resistance of Na+/K+ ATPase to ouabain in the cell line CHO-AT-2. A peak of mutagenic activity under the action of subtoxic doses of cadmium chloride has been revealed.     

Testing of some azo dyes and their reduction products for mutagenicity using Salmonella typhimurium TA 1538

A series of ten azo dyes as well as various single ring aromatic amines substituted on the benzene ring were tested for bacterial mutagenicity with Salmonella typhimurium TA 1538 using a soft-agar overlay method. Two dyes, sudan 2 and chrysoidin induced mutation but only in the presence of a rat liver preparation. Chrysoidin was the more active. Testing of its reduction products, aniline and 1,2,4-triaminobenzene showed a liver metabolite of the latter compound could be responsible for the mutagenic effect, having a comparable mutagenicity with 1,2-diamino-4-nitro-benzene, one of the mutagenic constituents of hair dyes. Structure-activity studies on a series of ring-substituted anilines indicated that mutagenic activity required at least two positions to be substituted with either amino or nitro groups, or one of each. The bacteria as well as the liver enzyme preparation may partake in the activation of these chemicals. The correlation between mutagenicity and carcinogenicity for this group of compounds is discussed.     

Role of the oncogene in the mutagenic activity of bovine adenovirus type 3

The mutagenic and carcinogenic effect of two EcoRI-fragments of bovine adenovirus type 3 (BAV-3) DNA inserted into pBR325 has been studied. The C fragment (located between 3,6 and 19,7 map units) contains the viral oncogene, the C fragment (between 44,3 and 63,7 map units) displays no transforming activity. It has been established that oncogene BAV-3 statistically true increases the yield of mutants resistant to 6-mercaptopurine (6MP) in Chinese hamster cells. The C fragment, pBR325 without viral sequences and DNA fragments of different molecular weights from normal Syrian hamster cells have no mutagenic effect. The control over tumor formation in syngenic mice after injection of C3H10T 1/2 and D. C fragments and pBR325 treatment exposed a parallelism between the mutagenic and transforming effect. The study of the combined effect of viral DNA fragments and the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) which increases the transforming activity of different carcinogens, shows that the promoter increases the frequency of mutants after viral oncogene treatment and does not induce mutagenic activity of those types of DNA which are unable to transform the cells.