Differential transcription of nonrepeated DNAs in Neurospora crassa mutants.

Transcriptional properties of an "albino" mutant, a "slime" mutant and a wild type strain of Neurospora crassa have been compared by quantitative estimates of DNA:RNA hybridization. The RNAs isolated from these strains were incubated with 32P-DNA of the wild type strain. The DNA:RNA hybrids were isolated by chromatography on hydroxyapatite. 29--34% of the wild type 32P-DNA hybridized with RNA from all of the strains used. The DNA sequences which gave a primary reaction with wild type RNA (tr-DNA) were recovered and again reacted with different RNAs. The tr-DNA sequences reacted to the extent of 92% with the wild type RNA, but only 78% with slime mutant RNA and 85% with the RNA isolated from the albino mutant. The use of tr-DNA sequences thus isolated, proved to have increased the specificity of the hybridization reactions, these were useful indicators for identification of transcriptional differences among wild type and mutant strains of N. crassa.