Effects of antimutagens on prophage induction in E coli lysogenic for lambda

Abstract

The effects of caffeine, acriflavine, spermine, quinacrine, and adenosine on spontaneous and UV-induced prophage induction in repair-proficient and -deficient strains of lysogenic Escherichia coli were examined. Caffeine caused a coinducing effect on UV induction in KMBL 160 (repair proficient) and KMBL 163 (uvrA), an anti-inducing effect in KMBL 161 (uvrE), and had no detectable effect in KMBL 164 (uvrC). Acriflavine increased UV induction in KMBL 160 and decreased it in all three repair-deficient mutant strains. Spontaneous induction was reduced by acriflavine in all four strains. Spermine caused a decrease in UV induction in KMBL 160 and KMBL 164, while it had limited effect in KMBL 161 and KMBL 163. For spontaneous induction spermine caused an increase in KMBL 160 and KMBL 163, a decrease in KMBL 164 and no detectable effect in KMBL 161. Quinacrine had no significant effect on spontaneous induction in KMBL 160 and KMBL 164, but caused a decrease in spontaneous induction in KMBL 161 and KMBL 163. Quinacrine produced no effect on UV induction in KMBL 160; however, it decreased UV induction in the three repair-deficient strains to some extent. A significant increase in spontaneous induction in KMBL 160 was caused by adenosine, while it had little effect in the repair-deficient strains. UV induction was not affected by adenosine.

Effect of ozone on prophage induction in different strains of Escherichia coli K-12 lysogenic for lambda

“…To compare the potential induction capacity of these two agents, the percent induction of total cells plated (Persons and Shankel 1983), the percent induction of survivors (Persons and Shankel 1983), and the induction index (Heinemann 1971) were calculated.…”

“…The cell sus~ensions (5 mL) were either untreated, to determine the spontaneous prophage induction, UV irradiated, or ozonated. The cell suspensions were irradiated with an American Ultraviolet CE-30 germicidal lamp emitting mainly at a 254-nm wavelength and at an incident dose rate of 1.54 J mp2 s-' for 30-60 s as described elsewhere (Witkin 1974;Dubeau and Chung 1982;Persons and Shankel 1983). For ozonation, the test suspensions were exposed to 50 ppm of ozone for 15-30 min as previously described (Hamelin and Chung 1974~).…”

“…The remaining cells of untreated, UV-irradiated, or ozonated suspensions "UV irradiation: 1.54 J m-2 s-'. "Percent induction of total cells plated: percentage of total cells plated that were induced (number of infectious centers per number of lysogenic cells plated) (Persons and Shankel 1983).…”

“…"Percent induction of survivors: percentage of cells that survived the UV irradiation that were induced (number of infectious centers per number of cells surviving the irradiation) (Persons and Shankel 1983).…”

Effect of five dietary antimutagens on the genotoxicity of six mutagens in the microscreen prophage-induction assay

“…Because the Microscreen prophage-induction assay appears to offer advantages for the detection of genotoxicants, I considered whether it might also be useful in antimutagenicity studies. In the literature, however, I found only one antimutagenicity study using this assay [Persons and Shankel, 1983]. In this study, I report the use of this assay to determine the effect of five known dietary antimutagens on the genotoxicity of six mutagenic chemicals.…”