Aryl-monoalkyl and cyclic triazenes: direct-acting mutagens

An aryl-monoalkyl triazene, methyl-p-tolyl triazene (MTT) and a cyclic triazene (delta2-triazoline) are direct-acting mutagens for Salmonella typhimurium bacteria and for cell-free Hemophilus influenzae DNA. MTT causes reversion of the hisG46 base-substitution mutation, but no reversion of the hisD3052 frameshift mutation. Induced mutation frequency is not strongly influenced by modifications in the genetic background of the S. typhimurium Ames tester strains, but is mildly enhanced by the addition of a pool of amino acids to the plating medium and is strongly enhanced by liquid preincubation before plating.