ABSTRACT
Blue light is necessary for initiation of mushroom formation in Schizophyllum commune. The genome of this basidiomycete contains homologues of the blue light receptor genes wc-1 and wc-2 of Neurospora crassa. Here, it is shown that inactivation of either or both of these genes in S. commune results in a blind phenotype. Mushroom formation was abolished in dikaryons and they formed symmetrical instead of asymmetrical colonies. Development was restored in a temperature dependent way in a Δwc-2Δwc-2 strain by introducing a construct encompassing the wc-2 gene under control of the promoter of the heat shock gene hsp3. A genome-wide expression analysis showed that the transcription factor genes c2h2 and hom1 as well as many hydrophobin genes are downregulated in light-grown colonies of the Δwc-2Δwc-2 mutant when compared with the wild-type dikaryon. Inactivation of wc-1 and/or wc-2 also resulted in sensitivity of the mycelium to intense light. Monokaryotic mutant strains only survived exposure to 6500 lux of light by growing into the agar. Expression analysis indicates that the photosensitivity of the Δwc-1 and Δwc-2 strains is due to lower levels of photolyase and ferrochelatase.
Subject(s)
Dermatitis, Phototoxic/genetics , Fungal Proteins/genetics , Fungal Proteins/metabolism , Schizophyllum/physiology , Schizophyllum/radiation effects , Agaricales/genetics , Agaricales/growth & development , Dermatitis, Phototoxic/metabolism , Gene Deletion , Gene Expression Profiling , Gene Expression Regulation, Fungal , Genome, Fungal , Schizophyllum/genetics , Schizophyllum/growth & development , Schizophyllum/metabolism , Ultraviolet RaysABSTRACT
A strain with an elevated level of spontaneous mutations and an especially high rate of reversion at a specific locus (pab-) was identified. The mutator trait is recessive. UV sensitivity and the absence of a UV-specific endonucleolytic activity were associated with the enhancement of the mutation rate in mutator strains. The endonuclease associated with the regulation of the mutation rate also acted on single-stranded DNA. The molecular weight of this enzyme is about 38000 daltons.
Subject(s)
Agaricales/genetics , Endodeoxyribonucleases , Mutation , N-Glycosyl Hydrolases , Schizophyllum/genetics , Crosses, Genetic , DNA, Single-Stranded/radiation effects , Genes, Recessive , Kinetics , Molecular Weight , Multienzyme Complexes/metabolism , Schizophyllum/radiation effects , Species Specificity , Ultraviolet RaysABSTRACT
Primary mutations in the alleles of alpha 1 and beta 7 of the B incompatibility factor of Schizophyllum were induced with X rays. An additional mutation unlinked to the B factor and affecting its regulatory function was detected. This mutation is effective in monokaryons with most B-factor specificities. The spectra of induced mutations in different alleles is discussed in reference to a polarity in the expression of the recognition function and the regulatory function by each locus of the B incompatibility factor.
Subject(s)
Agaricales/genetics , Alleles , Genes, Regulator , Schizophyllum/genetics , Mutation , Phenotype , Schizophyllum/radiation effects , X-RaysABSTRACT
The basidiomycete fungus Schizophyllum commune was found to have both photo-repair and dark-repair systems for UV-induced damage. Three UV-sensitive mutants were isolated and characterized for ability to repair UV-induced damage in light and dark, and for cross-sensitivity to caffeine and methyl methanesulfonate. Two of the mutants were damaged, to different extents, in their capacity for excision repair; one of these mutants was also probably damaged in post-replication repair. The third mutant was damaged only in post-replication repair.
Subject(s)
DNA Repair , DNA/radiation effects , Caffeine/pharmacology , DNA Repair/drug effects , Light , Methyl Methanesulfonate/pharmacology , Mutation , Schizophyllum/genetics , Schizophyllum/radiation effects , Ultraviolet RaysABSTRACT
The difference in lethality to cycloheximide between actively dividing and non-dividing cells was exploited to enhance detection of auxotrophic and UV-sensitive mutants in the fungi Schizophyllum commune and Saccharomyces cerevisiae.
