The interactive effect of ultraviolet irradiation and 5-bromouracil at the rib-1 locus in Neurospora crassa.

5-Bromouracil (5-BU) was shown to enhance reverse mutation rates when added to conidia of a rib-1 strain of Neurospora crassa previously irradiated with ultraviolet light. A comparison is presented between various incubation intervals in the presence and absence of 5-BU while varying the UV dose. An increase in mutation frequency ranging from 0.028 - 2.05 X 10(2) times greater than the spontaneous frequency, UV frequency alone or 5-BU frequency alone was observed when UV irradiation and 5-BU were combined.