title: Mutagenesis at the ad-3A and ad-3B loci in haploid UV-sensitive strains of Neurospora crassa. VI. Genetic characterization of ad-3 mutants provides evidence for qualitative differences in the spectrum of genetic alterations between wild-type and nucleotide excision-repair-deficient strains.
abstract: Genetic characterization of ad-3B mutants induced in wild-type and UV-sensitive strains has revealed qualitative differences between the spectra of genetic alterations at the molecular level. Ad-3B mutants induced in the two nucleotide excision-repair-deficient strains upr-1 and uvs-2 (Worthy and Epler, 1973) had significantly lower frequencies of nonpolarized complementation patterns and higher frequencies of noncomplementing mutants than ad-3B mutants induced in the wild-type strain in samples induced by either UV, gamma-rays, 4NQO or MNNG. In these same samples ad-3B mutants induced in uvs-4, uvs-5 or uvs-6 did not differ significantly from those induced in the wild-type strain. After ICR-170 treatment, ad-3B mutants induced in the UV-sensitive strains did not differ significantly from those induced in wild-type. The comparisons in the present and previous studies demonstrate that the process of mutation-induction in the ad-3 region is under the control of other loci that not only alter mutant recovery quantitatively (de Serres, 1980; Schüpbach and de Serres, 1981; Inoue et al., 1981a, b) but also qualitatively. These data have important implications for comparative chemical mutagenesis, since the spectrum of genetic alterations produced by a given agent can be modified markedly as a result of defects in DNA repair.
mesh_terms: D015112:4-Nitroquinoline-1-oxide / Q000494:pharmacology; D000609:Aminoacridines; D004260:DNA Repair; D004271:DNA, Fungal / Q000235:genetics; D005720:Gamma Rays; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D009154:Mutation; D009491:Neurospora / Q000235:genetics*; D009492:Neurospora crassa / Q000235:genetics* / Q000528:radiation effects; D009588:Nitrogen Mustard Compounds / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D000609:Aminoacridines; D004271:DNA, Fungal; D009588:Nitrogen Mustard Compounds; C091910:acridine mustard; D008769:Methylnitronitrosoguanidine; D015112:4-Nitroquinoline-1-oxide