In wild-type S. cerevisiae, diploid cells must be heterozygous at the matingtype locus in order to sporulate. In the preceding paper, we described a number of mutants (CSP mutants), isolated from nonsporulating aa and aa parent strains, in which sporulation appeared to be uncoupled from control by mating type. The characterization of one of these mutants (CSPI) is now extended to other processe...

introduction to define the clinical features, biochemical and histological findings and outcome of three forms of autoimmune hepatitis.   materials and methods in a cross sectional study between november 2001 to january 2008 in tehran and mashhad university of medical sciences, 61 children who diagnosed as aih (40 girls and 21 boys) have been analyzed for their clinical, serological, and histol...

Different mating systems have evolved in the fungal kingdom, including a tetrapolar multiallelic mating system in many basidiomycetes. In tetrapolar species, the presence of different alleles at two mating loci (MAT A and MAT B) is necessary for mating to occur. The tetrapolar fungus Serpula lacrymans causes wood-decay in buildings in temperate regions worldwide and is present in Europe with a ...

Acremonium chrysogenum, the fungal producer of the pharmaceutically relevant beta-lactam antibiotic cephalosporin C, is classified as asexual because no direct observation of mating or meiosis has yet been reported. To assess the potential of A. chrysogenum for sexual reproduction, we screened an expressed sequence tag library from A. chrysogenum for the expression of mating type (MAT) genes, w...

The a mating-type region of Neurospora crassa controls several major events in both the sexual and asexual phases of the fungal life cycle. This 3235-base-pair DNA segment is not homologous to the comparable genetic region of the A mating type. The unique a and A regions are bordered by nearly identical DNA sequences. The a genetic region contains at least two functional segments. One segment e...

Mating among the immediate products of meiosis (intratetrad mating) is a common feature of many organisms with parthenogenesis or with mating-type determination in the haploid phase. Using a three-locus deterministic model we show that intratetrad mating, unlike other systems of mating, allows sheltering of deleterious recessive alleles even if there is only partial linkage between a mating loc...

The study of quantitative traits provides a window on the interactions between multiple unlinked genetic loci. The interaction between hosts and pathogenic microbes, such as fungi, involves aspects of quantitative genetics for both partners in this dynamic equilibrium. One important pathogenic fungus is Cryptococcus neoformans, a basidiomycete yeast that can infect the human brain and whose mat...

G E N E T I C analyses of the controlling systems for homothallism uersus heterothallism in Saccharomyces revealed several striking features, i.e., the epistatic effect of a homothallic gene in relation to the heterothallic mating type alleles ( WINGE and ROBERTS 1949), the complementary interaction of homothallic genes ( TAKAHASHI 1958) and the mating type allele-specific conversion of heterot...

Naturally-occurring variation in virulence was studied in the opportunistic fungal pathogens, Aspergillus nidulans and Aspergillus fumigatus. I measured variation in growth on Neiland's solid agar medium and virulence in an insect model host, Galleria mellonella, in 92 A. nidulans recombinant strains generated by a cross between two wild type strains. A weak positive correlation was found betwe...