摘要：

Summary Recombinationless mutant cells ofBacillus subtilis are more sensitive to the cell-killing action of typical chemical mutagens, such as ethyl methanesulfonate, hydroxylamine, mitomycinC,N-methyl-N′-nitrosoguanidine or4-nitroquinoline-N-oxide than are the wild-type bacteria. Based on this relation, a simple method was devised for screening new chemical mutagens by examining their increased lethal action on Rec− over Rec+ bacteria instead of assessing their mutagenic capacities directly. We call this method “rec-assay”. When it was applied to a number of dyes, phloxine was found to be positive. Though this rec-assay procedure did not show the mutagenicity of phloxine directly, successive experiments usingE. coli cells showed that this dye really was mutagenic. Thus a correlation between the rec-assay result and the genetic data was confirmed. The rec-assay was also carried out in the peritoneal cavity of mice that had received intramuscular injections of phloxine.

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