Mitomycin mutagenic activity

The mutagenic activity of chemical substances can be assessed by means of the Ames test [109]. In analogy to this test which is based on the reversion of certain changes in the phenotype of mutants caused by the mutagen, one can use the reversion of a dark variant of Photobacterium leiognathi to the luminous one by mutagens, such as mitomycin C. This can be detected in nanogram amounts [110]. 

As for mitomycin C, whose action on DNA has been widely studied and whose mutagenic and carcinogenic activity is well known (17), our experiments confirm its effects on the bases (greater flexibility of DNA), the induction of cross-links (renaturation data) and DNA--protein links (greater viscosity after "in vivo" treatments). 

The limits of the sensitivity of the standard pol A procedure (lowest effective dose) for a number of chemicals have been compared to the dose required to give a positive test in the Salmonella mutagenicity assay (Table 5). For the chemicals selected that are active in both systems, it was found that there was no definite trend. The Salmonella assay was exquisitely sensitive to some chemicals (e.g., aflatoxin Bi), while the pol A system responded to low levels of others (e.g., mitomycin C). 

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