Nomenclature and location of bacterial mutations modifying the frequency of lysogenization of E. coli by lambdoid phages.
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Coliphages↗
Biomedical subjects
A Bailone
Publications and source records attributed to A Bailone.
Prophage lambda induction of Escherichia coli K12 envA uvrB: a highly sensitive test for potential carcinogens.
A simple, inexpensive, and sensitive test for potential carcinogens based upon the property of carcinogens to induce prophage lambda is described. By using chemicals activated with microsomal enzymes and E. coli K12 permeable (envA) tester bacteria also deficient in DNA repair (uvrB), the range of carcinogens detected in a lysogenic induction test (inductest) has been extended. We have provided the evidence that, after activation, carcinogenic polycyclic hydrocarbons such as benzo[a5pyrene and 7,12-dimethylbenz[a]anthracene induce prophage lambda. Three variants of the test have been developed (inductests I, II, and III), which are as sensitive as the mutagenicity test of Ames et al. [Ames, B. N., McCann, J. and Yamasaki, E. (1975) Mutat. Res. 31, 347-364]. Inductests II and III provide a quantitative estimation of the inducing activity of a carcinogen. With the latter test, one can determine: (i) the cellular toxic effect of a carcinogen and (ii) the kinetics of appearance and disappearance of active metabolites. For two series of chemicals, aflatoxins and benz[a]anthracenes, there is a good correlation between their carcinogenic activity in rodents and their prophage inducing activity in bacteria. The fact that the majority of the cell population is induced makes it possible to test the inducing activity of carcinogens at the biochemical level, e.g., by measuring lambda repressor inactivation.
Biotransformation↗
E. coli K12 inf: a mutant deficient in prophage lambda induction and cell filamentation.
The bacterial mutant inf-3 (lambda) is not inducible and does not form filaments following thymine starvation. Lysogenic induction is neither produced by ultraviolet light (UV) nor promoted by tif-1. This phenotype is due to a mutation infA3 located between 60 and 73 min on the E. coli K12 map. The inf mutant is resistant to X-ray and UV irradiation, in contrast to all other known non-inducible bacterial mutants. It is Rec+ and able to perform host cell reactivation as well as UV-reactivation of phage lambda. After exposure to UV light, its DNA is degraded more than that of the parent and the resumption of DNA synthesis is delayed by 30 min; nevertheless, the cell survival is analogous to that of the parent. The inf mutant is also resistant to thymine starvation, for at least 3 hours. Wild type phage lambda forms clear plaques on a lawn of non-lysogenic inf bacteria; a corresponding low level of lysogenization is found. The capacity of inf bacteria to reproduce phages lambda, T4 or T6 is impaired. No gross defect in DNA transcription has been detected. Nevertheless, this mutant might have a slight alteration in the transcription process or in any other process involved in gene expression. This alteration might affect the regulation of DNA replication and cell division as well as prophage lambda induction.
Bacteriophage lambda↗
[Phenotype of an E coli K 12 mutant resistant to thymine deficiency death].
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Coliphages↗