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1.
The effect of nitrosoguanidine on the induction of three types of mutagenic changes inMycobacterium phlei PA was studied. The mutagenic changes included: change of prototrophy to auxotrophy, conversion of sensitivity to isoniazide
to resistańce and sensitivity to streptomycin to resistance. The induction of auxotrophic mutants was successful especially
when using NTG at a concentration of 1000 μg/ml. A total of 100 auxotrophs was obtained out of which only 13 were sufficiently
stable to be used in further studies. Amino acid requirements especially the glycine−(serine−) type characterized more than half of all auxotrophic mutants obtained. A group of mutants requiring purines also included
a high number of mutants. A considerable spontaneous reversion frequency was found in both groups of auxotrophs. The kinetics
of the induction of INH-resistant mutants by nitrosoguanidine at a concentration of 1000 μg/ml was studied and a high induction
of these mutants, particularly at high lethal effect of the mutagen found. The mutability of the STMr marker was relatively low in the present model microorganism as compared with the two markers mentioned earlier. 相似文献
2.
The mutagenic effect of 0.05m and 1m HA onMycobacterium phlei PA was investigated. To establish the mutagenic effect the inactivating effect was studied under the same experimental conditions.
Hydroxylamine at a higher concentration (1m) exhibited relatively high mutagenic effect. This was indicated by about 100-fold and 10-fold higher frequency of INHr and STMr mutants, respectively (as compared with spontaneous mutations) and induction of auxotrophic mutants. On the other hand, the
mutagenic effect of 0.05m hydroxylamine was low under the same experimental conditions.
The inactivating effect of a higher HA concentration (1m under given experimental conditions) was considerably higher when using the given model microorganism than that of the lower
one (0.05m under the same experimental conditions). This finding does not agree with literature data obtained in other experimental
models. 相似文献
3.
Lethal and mutagenic effects of nitrous acid and UV radiation onMycobacterium phlei were studied Three auxotrophic strains of the PA strain ofMycobacterium phlei were obtained: ala-, his-, and gly- (ser-) INHr Bods of the his- strain grown in liquid media are longer to filamentous as compared with cells of the prototrophic PA strain grown in the
same media, whereas cells of the gly- (ser-) INHr mutant are shorter to coccobacillary. Cells of the ala- strain are characterized by their various length from normal to coccobacillary. The auxotrophic strains obtained differ from
each other by a frequency of spontaneous reversions to prototrophy. The his- strain is the most stable, a frequency of spontaneous reversions to prototrophy being 10-9. The gly- (ser-) INHr strain reverts spontaneously to prototrophy with a frequency of 10-8 to 10-7. The ala- strain spontaneously reverting with a frequency of 10-5 is the most labile. The auxotrophic mutants obtained do not differ from the original prototrophic strain in the other properties
studied.
A change in a frequency of INH and STM-resistant mutants was also studied. It was found that under the influence of UV radiation
a frequency of INH-resistant mutants increases 43 to 80 fold as compared with a frequency of spontaneous mutations, this latter
being about 2.6 × 10-6. No substantial increase in a frequency of STM-resistant mutants was found using UV irradiation under the given experimental
conditions; their spontaneous frequency equals to 9.0 × 10-9 to 2.0 X 10-8. 相似文献
4.
The mutability of the PN strain ofMycobacterium phlei was examined after induction of auxotrophic mutants and of STM and VM-resistant mutants, by UV irradiation. A total of 30 auxotrophic mutants were isolated, most of them amino acid-dependent five purine-dependent, and one uracil-dependent. To induce the mutants higher UV doses had to be used so that the survival of cells in the original suspension would not exceed a few per cent. For further genetic work use can be made of 8 auxotrophic mutants (PN try?ura?, PN arg?ura?, PN ileu?val?, PN ileu?, PN leu?, PN lys?, PN lys?-VMr, PN val?), these showing a low frequency of spontaneous reversions. No spontaneous auxotrophic mutants have been found. The frequency of STM and VM-resistant mutants is increased upon UV irradiation, a post-irradiation incubation in a liquid medium without the drug being essential for their phenotypic expression. The highest increase of the number of these mutants is attained after 48 h of post-irradiation incubation and it has been found that, within a certain experimental scatter, the same frequency increase is found on using a complete or a minimal liquid medium. The frequency of spontaneous STM-resistant mutants lies within 5.8×10?6–8.8×10?6, of those VM-resistant between 3.1×10?5 and 4.1×10?5. The highest frequency of induced STM-resistant mutants lies between 3.0×10?5 and 9.3×10?5 and of VM-resistant mutants between 1.1×10?4 and 2.2×10?4 相似文献
5.
Rifampicin was found to inhibit the growth and incorporation of14C-adenine,14C-leucine and14C-glycine in exponentially growing cells ofM. smegmatis cultivated in Merrill’s synthetic medium. Increasing concentrations of the antibiotic inhibited respiration in resting cells,
in the presence of glucose or 2-oxoglutarate as substrates in particular. In addition to the well-known interference of rifampicin
with the biosynthesis of RNA, the effect on the energy metabolism should also be considered. 相似文献
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《Mutation Research/Genetic Toxicology》1976,40(4):305-307
The mutagenicity of an antidepressant drug, nialamide, was studied with Salmonella typhimurium TA1535-8. Nialamide was mutagenic for strain TA1535 in the absence of rat liver extracts. 相似文献
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Mutagenic effect of benomyl on Fusarium oxysporum 总被引:1,自引:0,他引:1
12.
Mutagenic effect of the new herbicide titus has been studied by the tests of chromosome aberration and gene mutations in maize. It has been shown that the preparation in question possesses a definite mutagenic activity, which sometimes 5-7 times exceeded the level of spontaneous mutating. Therefore, when recommending it for application in agriculture it is necessary strict following recommended doses, because even slight excess may result in considerable genetic consequences. It is also of great importance to apply this herbicide during the recommended stage. The application of titus for maize in hybridization plots as well as in nurseries for reproduction of elite and super elite lines is not recommended. 相似文献
13.
Mutagenic effect of BUdR in diploid human fibroblasts 总被引:2,自引:0,他引:2
It has only recently been possible to demonstrate the expected mutagenic effect of 5-bromodeoxyuridine (BUdR) in heteroploid hamster cells in culture. We have now extended this observation to diploid human fibroblasts utilizing techniques adapted from the work of Albertini and DeMars on X-ray mutagenesis at the hypoxanthine-guanine phosphoribosyltransferase (HGPRT) locus in these cells. In four separate experiments, fibroblasts from a female donor were exposed to 500 micrograms/ml ethylmethane sulfonate (EMS) or 3 micrograms/ml BUdR yielding survivals of 9% and 5%, respectively. After a 6-day expression period, survivors were plated in selection medium containing 0.3 micrograms/ml 8-azaguanine (8-AG). After 3-5 weeks, azaguanine-resistant colonies were isolated for characterization or stained for counting. The average spontaneous mutation rate/cell/generation was 0.6.10(-6). The average induced mutation rates for EMS and BUdR were 7.8.10(-6) and 6.3.10(-6)/cell/generation, respectively. Similar results were obtained in two experiments with an additional fibroblast line. Mutant colonies isolated following BUdR treatment demonstrated from 1.4 to 61.5% of the HGPRT activity of the parental line and showed at least 8% Barr bodies, excluding the possibility of contamination by Lesch-Nyhan cells. This demonstration of a BUdR effect comparable to that of an alkylating agent or X-irradiation opens the study of mutation due to base-analog substitution in diploid human cells. 相似文献
14.
The possible mutagenicity of the organic solvent dichloromethane was investigated with the mutation test as described by Ames et al. The compound was mutagenic in both tester strains used, namely TA98 and TA100. The administration of rat-liver homogenate did not appear to be essential though it slightly increased the number of mutations. 相似文献
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Ethyl methanesulfonate was used for the induction of three types of mutants in a non-acidfast strain ofMycobacterium phlei. A total of 20 auxotrophie mutants was isolated. The mutants were isolated mostly when using doses yielding higher survival
of the cells of the basic suspension. The auxotrophic mutants isolated required mostly amino acids, two mutants required purines
and three mutants required vitamins. By determining the frequency of spontaneous reversions, it was found that 9 auxotrophic
mutants could be used for further genetic studies. These included the following phenotypes: isoleucine−, leucine−, lysine−, nicotinic acid−, pyridoxine−, and xanthine−. Seven scotochromogenic mutants were isolated after ethyl methanesulfonate treatment. One was ochre, the remaining six were
orange. Six achromogenic mutants were detected. Spontaneous auxotrophic mutants, scotochromogenic and achromogenic mutants
were not isolated. The treatment with 0.2m ethyl methanesulfonate resulted in an increase in the frequency of STM-resistant mutants, the maximum phenotypic expression
taking place after 72 hours cultivation in a liquid medium without the drug. The frequency of induced STM-resistant mutants
varied within the range of 8.6.10−5–1.0.10−4 as compared with the frequency of spontaneous mutants 5.8.10−6–8.8.10−6. 相似文献
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Mutagenic action of 3,7-diamino-4,9-dioxy-5,10-dioxo-4,5,9,10-tetrahydro-4,9-diazapiren (DDDTDP) was shown using indicator strains Salmonella typhimurium TA 1534, TA 1536, TA 1537, TA 1538. The drug-induced mutations in strains TA 1534 and TA 1538, and it can be used as a positive control in testing mutagens capable of inducing frameshift mutations. No significant differences was observed between DDDTDP effects on strains TA 1534 and TA 1538 which did or did not bear rfa mutation causing defects of cell wall lypopolysacharide complex. Within the range of concentrations tested DDDTDP had mutagenic effect without causing essential killing of bacteria. The mutagenic effect was decreased in the in vitro system of metabolic activation (Ames' plate test in Salmonella microsomes). 相似文献
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《Mutation Research/Genetic Toxicology》1976,40(2):119-124
Effect of sodium nitrite on cultured FM3A cells, a C3H mouse mammary carcinoma cell line, was examined. The chromosomal preparations demonstrated that severe aberrations were induced in more than 80% of the mitotic plates at 10−2 M and in nearly 40% at 10−2.5 M after 24 and 48 h treatment. According to the results of alkaline sucrose gradient analysis sedimentation profiles of cell DNA treated at as high as 10−1 M for 24 h scarcely changed from that of control cell DNA. Induction of 8-azaguanine-resistant mutation was demonstrated above 10−3 M sodium nitrite. 相似文献