title: Antimutagenic specificity against spontaneous and nitrofurazone-induced mutations in Escherichia coli K12ND160.
abstract: Escherichia coli K12ND-160 possesses characteristics which make it highly suitable for studies on mutagenic/antimutagenic specificity and has been used to investigate such effects for several agents. Nitrofurazone (NFZ) was used as a mutagen at non-lethal concentrations; it causes mutation from fucose sensitivity to resistance (FucS----FucR) and from inability to utilize melibiose to melibiose utilization (Mel(-)----Mel+), but does not induce mutations from deoxygalactose sensitivity to resistance (DGAS----DGAR). Caffeine is mutagenic for reversions from lactose non-utilization to utilization (Lac(-)----Lac+) and mutations from FucS----FucR, but it is antimutagenic for mutations from 6-azauracil sensitivity to resistance (AzaUS----AzaUR) and Mel(-)----Mel+ reversions and produces no effect on spontaneous DGAS----DGAR mutations. Added guanosine and cytidine (G + C at 100 micrograms/ml each) exert antimutagenic activity against spontaneous Lac(-)----Lac+ reversion, but not against caffeine-induced Lac(-)----Lac+ reversions; a strong antimutagenic effect on spontaneous Mel(-)----Mel+ reversion is also observed. The addition of G + C does not result in either mutagenic or antimutagenic effects against spontaneous or NFZ-induced FucS----FucR or DGAS----DGAR mutations; it is, however, strongly mutagenic for AzaUS----AzaUR mutations. The 'natural antimutagen', chlorophyllin, is antimutagenic for DGAS----DGAR mutations, but fails to demonstrate such activity against spontaneous or caffeine-induced Lac(-)----Lac+ reversion, spontaneous or NFZ-induced Mel(-)----Mel+ reversion, or spontaneous or NFZ-induced FucS----FucR mutation.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich, UK.
authors.forename: C H
authors.initials: CH
authors.lastname: Clarke
authors.forename: D M
authors.initials: DM
authors.lastname: Shankel
mesh_terms: D002110:Caffeine / Q000633:toxicity; D003035:Cobalt / Q000633:toxicity; D015169:Colony Count, Microbial; D003562:Cytidine / Q000633:toxicity; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D005819:Genetic Markers; D006151:Guanosine / Q000633:toxicity; D009152:Mutagenicity Tests; D009153:Mutagens / Q000633:toxicity*; D009154:Mutation; D009583:Nitrofurazone / Q000633:toxicity; D011796:Quinacrine / Q000633:toxicity; D013096:Spermine / Q000633:toxicity
chemical_list: D005819:Genetic Markers; D009153:Mutagens; D006151:Guanosine; D013096:Spermine; D003035:Cobalt; D002110:Caffeine; D003562:Cytidine; D011796:Quinacrine; D009583:Nitrofurazone