Adaptive response of Bacillus subtilis to N-methyl-N'-nitro-N-nitrosoguanidine

Adaptive response of Bacillus subtilis to N-methyl-N'-nitro-N-nitrosoguanidine.

Cell extracts of Bacillus subtilis contain a methyltransferase that appears to remove the O6-methyl group from O6-methylguanine in DNA in situ. This reaction proceeds in a stoichiometric fashion, as in Escherichia coli. However, the basal level of the enzyme (approximately 240 molecules per cell) is significantly higher in B. subtilis than in E. coli. In addition, the methyltransferase level in...

Adaptive response and enhancement of N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis by chloramphenicol in Streptomyces fradiae.

Streptomyces fradiae expressed an adaptive response to treatment with small doses of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) that caused a reduction in mutagenesis by treatment with larger doses of MNNG. Treatment of S. fradiae with high levels of MNNG in the presence of chloramphenicol caused enhancement of mutagenesis, independent of the adaptive response.

N-methyl-N'-nitro-N-nitrosoguanidine: reactions of possible significance to biological activity with mammalian cells.

Ossification of the N-methyl-N'-nitro-N-nitrosoguanidine-induced small intestine adenocarcinomas in rats.

Eighty rats out of 233 developed malignant tumors in the stomach and small intestine by administration of 100 micrograms/ml N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in drinking water for 28 weeks. Fifteen lesions (30%) among the 50 small intestinal carcinomas showed ossification in the tumor, while none in the sarcomas (12 lesions) or gastric adenocarcinomas (59 lesions) showed ossification....

Chemical modification of viral RNA. VI. The action of N-methyl-N'-nitro-N-nitrosoguanidine.

N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG, "nitrosoguanidine") has been extensively used as an effective mutagen for DNA-containing organisms and virusesl-4 but appears not to have been used with RNA viruses. Nothing definitive seems to have been reported about its mode of action. This paper deals with the effects of MNNG on the infectivity, mutation frequency, and base composition of tobacco ...