An abnormal growth form in the fungus Schizophyllum commune is described that interferes with the development of reproductive structures. The abnormality, which takes the form of relatively large, compact, hemispherical bodies, depends on a dominant Mendelian gene, mound, for its expression. When mound is expressed in a mycelium that has the potential to form fruiting bodies, the fruiting response is affected and the effect is variable within a replicate series: fruiting bodies may be normal or abnormal, abort at various stages, or not develop at all. Occasionally, fruit bodies are overgrown and are completely enveloped by the hemispherical bodies. When hyphae from hemispherical bodies are subcultured, a seemingly normal mycelium forms that eventually differentiates hemispherical structures, but the ability to form fruiting bodies in not expressed. Continuous mycelial subculture has shown this loss of fruiting expression to be a permanent transformation, which is demonstrated to be a characteristic of hemispherical bodies. (+info)
Mucoid impaction caused by monokaryotic mycelium of Schizophyllum commune in association with bronchiectasis.
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A 51-year-old female was admitted to our hospital because of fever, cough, and hemoptysis. A chest radiograph showed a partial collapse of the left upper division and infected bullae in the left upper lobe. Bronchoscopic examination showed thick mucous plugs in the left upper bronchus. The isolates of the plugs proved to be Schizophyllum commune. Neither accumulation of eosinophils nor Charcot-Leyden crystals were present in the plugs. Mild ectatic changes of the left upper bronchus had been observed 17 years previously. We describe the first case of mucoid impaction, which was independent of the immunological reactions, caused by S. commune in association with bronchiectasis. (+info)
Scooter, a new active transposon in Schizophyllum commune, has disrupted two genes regulating signal transduction.
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Two copies of scooter, a DNA-mediated transposon in the basidiomycetous fungus Schizophyllum commune, were characterized. Scooter is the first transposon isolated from S. commune. Scooter creates 8-bp target site duplications, comparable to members of the hAT superfamily, and has 32-bp terminal inverted repeats. Both copies of scooter are nonautonomous elements capable of movement. Southern blot hybridizations show that scooter-related sequences are present in all S. commune strains tested. Scooter-1 was identified initially as an insertion in the Bbeta2 pheromone receptor gene, bbr2, leading to a partial defect in mating. Scooter-2 spontaneously disrupted a gene to produce the frequently occurring morphological mutant phenotype known as thin. The scooter-2 insert permitted cloning of the disrupted gene, thn1, which encodes a putative regulator of G protein signaling (RGS) protein. Spontaneous insertion of scooter into genes with identifiable mutant phenotypes constitutes the first evidence of active transposition of a DNA-mediated transposon in a basidiomycete. (+info)
Effect of introns and AT-rich sequences on expression of the bacterial hygromycin B resistance gene in the basidiomycete Schizophyllum commune.
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Previously, it was shown that introns are required for efficient mRNA accumulation in Schizophyllum commune and that the presence of AT-rich sequences in the coding region of genes can result in truncation of transcripts in this homobasidiomycete. Here we show that intron-dependent mRNA accumulation and truncation of transcripts are two independent events that both affect expression of the bacterial hygromycin B resistance gene in S. commune. (+info)
Polymorphism at the ribosomal DNA spacers and its relation to breeding structure of the widespread mushroom Schizophyllum commune.
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The common split-gilled mushroom Schizophyllum commune is found throughout the world on woody substrates. This study addresses the dispersal and population structure of this fungal species by studying the phylogeny and evolutionary dynamics of ribosomal DNA (rDNA) spacer regions. Extensive sampling (n = 195) of sequences of the intergenic spacer region (IGS1) revealed a large number of unique haplotypes (n = 143). The phylogeny of these IGS1 sequences revealed strong geographic patterns and supported three evolutionarily distinct lineages within the global population. The same three geographic lineages were found in phylogenetic analysis of both other rDNA spacer regions (IGS2 and ITS). However, nested clade analysis of the IGS1 phylogeny suggested the population structure of S. commune has undergone recent changes, such as a long distance colonization of western North America from Europe as well as a recent range expansion in the Caribbean. Among all spacer regions, variation in length and nucleotide sequence was observed between but not within the tandem rDNA repeats (arrays). This pattern is consistent with strong within-array and weak among-array homogenizing forces. We present evidence for the suppression of recombination between rDNA arrays on homologous chromosomes that may account for this pattern of concerted evolution. (+info)
Colonization with Schizophyllum commune of localized honeycomb lung with mucus.
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We report a surgical case involving localized honeycomb lung with mucus, caused by colonization of a Schizophyllum commune, which displayed a tumorous shadow in the right upper mediastinum. A 74-year-old male with a history of tuberculosis in the 1970s was referred to Chiba University Hospital (Chiba, Japan) with an abnormal shadow evident in the chest roentgenogram. A transbronchial biopsy failed to yield a definite diagnosis. We resected the right upper lobe, which was found to contain a consolidative lesion filled with viscous mucus in the right upper lobe adjacent to the right upper mediastinum. Microscopic examination revealed a honeycomb lung formation with mucus in the destroyed space. Culture of the mucus yielded a whitish filamentous fungus, positively identified as S. commune. This is the first report of S. commune leading to a deposit of mucus and the formation of a consolidative lesion in the destroyed lung. (+info)
Development of molecular methods for identification of Schizophyllum commune from clinical samples.
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In the last 50 years, to our knowledge, only 16 cases of diseases caused by Schizophyllum commune in humans have been reported. Within only 6 months, we found four isolates of this basidiomycetous fungus, obtained from patients suffering from chronic sinusitis. The cultures of the isolated fungi showed neither clamp connections nor fruiting bodies (basidiocarps), which are distinctive features for S. commune, but fast-growing cottony white mycelium only. This was harvested, and DNA was extracted. The internal transcribed spacer region of the ribosomal DNA (rDNA) was amplified with fungus-specific primers, and the PCR products were sequenced. Two strains of S. commune, collected from branches of a European hornbeam (Carpinus betulus) and a tree of heaven (Ailanthus altissima), respectively; four specimens from the herbarium of the Institute of Botany, Karl-Franzens-University Graz; and two strains from internationally known culture collections (CBS 340.81 [ATCC 44201] and CBS 405.96) were investigated in the same way. The sequence data of all strains were compared and showed homology of over 99% in this 660-bp-long fragment of rDNA. With these results, a map of restriction enzyme cutting sites and a primer set specific for S. commune were created for reliable identification of this human pathogenic fungus. (+info)
Changes in mate recognition through alterations of pheromones and receptors in the multisexual mushroom fungus Schizophyllum commune.
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Schizophyllum commune has thousands of mating types defined in part by numerous lipopeptide pheromones and their G-protein-coupled receptors. These molecules are encoded within multiple versions of two redundantly functioning B mating-type loci, B alpha and B beta. Compatible combinations of pheromones and receptors, produced by individuals of different B mating types, trigger a pathway of fertilization required for sexual development. Analysis of the B beta 2 mating-type locus revealed a large cluster of genes encoding a single pheromone receptor and eight different pheromones. Phenotypic effects of mutations within these genes indicated that small changes in both types of molecules could significantly alter their specificity of interaction. For example, a conservative amino acid substitution in a pheromone resulted in a gain of function toward one receptor and a loss of function with another. A two-amino-acid deletion from a receptor precluded the mutant pheromone from activating the mutant receptor, yet this receptor was activated by other pheromones. Sequence comparisons provided clues toward understanding how so many variants of these multigenic loci could have evolved through duplication and mutational divergence. A three-step model for the origin of new variants comparable to those found in nature is presented. (+info)