SEQUENCING STUDIES OF ICR-170 MUTAGENIC SPECIFICITY IN THE am (NADP-SPECIFIC GLUTAMATE DEHYDROGENASE) GENE OF NEUROSPORA CRASSA

Philip A. Burns ¹, Jane H. Kinnaird ², Brian J. Kilbey ², and John R. S. Fincham ³

¹ Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada
² Department of Genetics, University of Edinburgh, King's Buildings, Edinburgh EH9 3JN, Scotland
³ Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, England

The acridine half-mustard ICR-170-induced reversion of the mutant am15, which has a single base-pair deletion, at a frequency of between 9 and 28 x 10^-6. In each of three classes of revertants, the mutagen had induced the insertion of a (see PDF) base pair at a (see PDF) site. The mutant am6, which has a single base pair insertion, is known to be revertible, with UV light, by deletion of a (see PDF) base pair at a (see PDF) site. This mutant reverted with ICR-170 at a frequency of 0.1 x 10^-6. These results show that ICR-170 is able to induce addition frameshifts in Neurospora crassa within short, monotonous runs of G:C base pairs, but indicate a lack of deletion activity at such sequences.