Effect of Rifampicin on N-Methyl-N-Nitrosourea-Induced Mutation Frequency in Escherichia coli
Rifampicin enhances by 4–6 fold the in diced mutation frequency of N-methyl-N-nitrosourea (MNUA) in E.coli WP2. The magnitude of this increment is dependent on the time of addition of the antibiotic with respect to that of mutagen, and on the prior growth rate of the cells before treatment. It is not dependent on the uvrA + - or the recA + lexA +-dependent repair capacities of the cell, under specified growth conditions, but may be modulated by prior induction of the “adaptive response”. Rifampicin inhibits recovery of RNA and protein synthetic rates in post-incubated cells following MNUA treatment (Neale and Bacon, in press), and also retards, in vivo, the loss of O6-methyldeoxyguanosine (O6-MeG) residues from DNA of MNUA-treated E.coli. Chloramphenicol enhances the MNUAinduced mutation frequency by only 3 fold, and its effect on mutation is compared with that of rifampicin.
KeywordsMutation Frequency Genic Lesion Dice Mutation Prior Induction IARC Scientific Publication
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