The existence of two subclasses of revertants has been demonstrated among the revertant populations produced by [3H]thymidine, [3H]uracil, and [3H]histidine decays in Escherichia coli. The majority of the total revertant population is composed of dependent revertants which give rise to revertant colonies in the presence of nutrient fortification. In addition, there are some independent revertants that form colonies in the absence of nutrient fortification. The relative mutagenic efficiencies for production of independent revertants are in the order: [3H]thymidine, [3H]uracil, and [3H]histidine (in relative magnitudes 3.0, 1.4, 1.0, respectively). The disproportionately low yield of revertants in the independent subclass produced by one of the 3H compounds ([3H]uracil) infers that there are at least two molecular alterations that can mediate the reversion of a bacterial mutant by 3H decay, and thet the specificity of the 3H compounds used is sufficient to effect differentially the propertions of these two alterations.
|Original language||English (US)|
|Number of pages||8|
|Journal||Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis|
|State||Published - Dec 15 1964|
ASJC Scopus subject areas
- Molecular Biology
- Health, Toxicology and Mutagenesis