scholarly journals Mating type switching in the tetrapolar basidiomycete Agrocybe aegerita.

Genetics ◽  
1992 ◽  
Vol 131 (2) ◽  
pp. 307-319 ◽  
Author(s):  
J Labarère ◽  
T Noël
Keyword(s):  
Filamentous Fungi ◽  
Mating Type ◽  
Wild Strain ◽  
Large Series ◽  
Mating Types ◽  
Genetic Analyses ◽  
Agrocybe Aegerita ◽  
Mating Type Switching ◽  
Type Factor ◽  
First Time

Abstract The study of fruiting in the basidiomycete Agrocybe aegerita has shown that some haploid homokaryotic strains can spontaneously switch their mating specificities at the two unlinked A and B mating type factors. This event causes the dikaryotisation of primary homokaryons without plasmogamy and leads to the differentiation of sporulating fruit-bodies (pseudo-homokaryotic fruiting). For each mating type factor, the genetic analyses have revealed that: (1) parental and switched mating types segregate meiotically as Mendelian markers, (2) a total of six switched mating type factors (two parental and four nonparental) were obtained from a wild strain, (3) most of the nonparental factors have specificities differing from those of a large series of wild factors, (4) strains with the same expressed mating type can generate different specificities, (5) switching is always restricted to the same mating type in a homokaryon, (6) nonparental types can switch again, and (7) meiosis fixes the specificities to which switching can occur. This suggests, for the first time in filamentous fungi, the existence of a mechanism analogous to the mating type switching in yeasts. We hypothese that both A and B mating type regions in A. aegerita are constituted of three loci, one specialized in expression and two other carrying silent information. Mating type switching in homokaryotic strains would occur by copy transposition of silent A and B information into the expression loci. Moreover, we propose that during meiosis the silent loci are substituted by copies of the expressed loci.

A SUPPRESSOR OF THE HETEROKARYON- INCOMPATIBILITY ASSOCIATED WITH MATING TYPE IN NEUROSPORA CRASSA

1970 ◽  
Vol 12 (4) ◽  
pp. 914-926 ◽  
Author(s):  
Dorothy Newmeyer
Keyword(s):  
Linkage Group ◽  
Neurospora Crassa ◽  
Mating Type ◽  
Vegetative Growth ◽  
Mode Of Action ◽  
Wild Strain ◽  
Group Iv ◽  
Mating Types ◽  
Vegetative Incompatibility ◽  
Opposite Mating Type

Neurospora crassa strains of opposite mating type are ordinarily heterokaryon-incompatible during vegetative growth. An unlinked mutant called tolerant (tol) is described, which suppresses the vegetative incompatibility of unlike mating types without affecting their ability to cross. The mutant tol was selected and studied by means of duplications heterozygous for mating type. Use of the duplication eliminates complications due to unlinked heterokaryon genes. The mode of action of tol has been confirmed by conventional heterokaryon tests. tol has been mapped in linkage group IV, close to tryp-4. A suppressor similar or identical to tolerant has been found in a wild strain from Panama, out of 14 different wild types which were tested. By using a different duplication which covers the unlinked heterokaryon-compatibility locus C, it was shown that tolerant does not suppress C/c incompatibility. The fact that tolerant suppresses only one of the two functions ascribed to mating type revives the question of whether 'mating-type' is one gene or two. However, the data strongly support Pittenger's (1957) conclusion that, if two genes are involved, they must be closely linked.

scholarly journals Molecular and Cellular Dissection of Mating-Type Switching Steps in Schizosaccharomyces pombe

2005 ◽  
Vol 25 (1) ◽  
pp. 303-311 ◽  
Author(s):  
Allyson M. Holmes ◽  
Atanas Kaykov ◽  
Benoit Arcangioli
Keyword(s):  
Cell Cycle ◽  
Single Cell ◽  
Mating Type ◽  
Replication Fork ◽  
S Phase ◽  
M Cell ◽  
Developmental Fate ◽  
Mating Type Switching ◽  
First Time ◽  
Replication Intermediates

ABSTRACT A strand-specific imprint (break) controls mating-type switching in fission yeast. By introducing a thiamine repressible promoter upstream of the mat1 locus, we can force transcription through the imprinted region, erasing the imprint and inhibiting further mating-type switching, in a reversible manner. Starting from a synchronized, virgin M-cell population, we show that the site- and strand-specific break is formed when DNA replication intermediates appear at mat1 during the first S phase. The formation of the break is concomitant with a replication fork pause and binding of the Swi1 protein at mat1 until early G2 and then rapidly disappears. Upon its formation, the break remains stable throughout the cell cycle and triggers mating-type switching during the second S phase. Finally, we have recreated the mating-type switching pedigree at the molecular and single-cell levels, allowing for the first time separation between the establishment of imprinting and its developmental fate.

scholarly journals INTERCONVERSION OF YEAST MATING TYPES III. ACTION OF THE HOMOTHALLISM (HO) GENE IN CELLS HOMOZYGOUS FOR THE MATING TYPE LOCUS

Genetics ◽  
1977 ◽  
Vol 85 (3) ◽  
pp. 395-405 ◽  
Author(s):  
James B Hicks ◽  
Jeffrey N Strathern ◽  
Ira Herskowitz
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Life Cycle ◽  
Gene Product ◽  
Direct Observation ◽  
Mating Type ◽  
Mating Types ◽  
Type Locus ◽  
Mating Type Locus ◽  
Mating Type Switching ◽  
Ho Gene

ABSTRACT Mating type interconversion in homothallic Saccharomyces cerevisiae has been studied in diploids homozygous for the mating type locus produced by sporulation of a/a/a/α and a/a/α/α tetraploid strains. Mating type switches have been analyzed by techniques including direct observation of cells for changes in α-factor sensitivity. Another method of following mating type switching exploits the observation that a/α cells exhibit polar budding and a/a and α/α cells exhibit medial budding.—These studies indicate the following: (1) The allele conferring the homothallic life cycle (HO) is dominant to the allele conferring the heterothallic life cycle (ho). (2) The action of the HO gene is controlled by the mating type locus—active in a/a and α/α cells but not in a/α cells. (3) The HO (or HO-controlled) gene product can act independently on two mating type alleles located on separate chromosomes in the same nucleus. (4) A switch in mating type is observed in pairs of cells, each of which has the same change.

Mating type in Neurospora and closely related ascomycetes: some current problems

1995 ◽  
Vol 73 (S1) ◽  
pp. 251-257 ◽  
Author(s):  
Robert L. Metzenberg ◽  
Thomas A. Randall
Keyword(s):  
Dna Sequence ◽  
Mating Type ◽  
Podospora Anserina ◽  
Mating Types ◽  
Hmg Proteins ◽  
Fruiting Body Formation ◽  
Unique Region ◽  
Mating Type Switching ◽  
Flanking Sequences ◽  
Relationship Of

Neurospora crassa and related ascomycetes such as Podospora anserina exist in two mating types, encoded in a unique region of one chromosome. Classical genetic analysis outlined the nature of the questions and provided important materials for further work. In the mating type region, there is little DNA sequence resemblance between the two mating types. They are, therefore, called idiomorphs rather than alleles. There are no silent copies of these sequences in the genome, so mating type switching is impossible. Cloning, sequence analysis, and complementation studies involving these idiomorphs has begun to shed light on their function. One of the idiomorphs contains three reading frames; one is essential for fertilization and fruiting body formation and the other two are involved in post-fertilization functions including ascus and ascospore formation. In various species of the genus Neurospora, the centromere-proximal flank of the idiomorphs is highly variable in DNA sequence among species, and in some cases, between mating types. The similarities and differences in these flanking sequences allow some conclusions to be drawn about the possible phylogenetic relationship of these species. Key words: Neurospora, ascomycetes, mating, evolution, compatibility, HMG proteins.

scholarly journals Differential Gene Expression between Fungal Mating Types Is Associated with Sequence Degeneration

2020 ◽  
Vol 12 (4) ◽  
pp. 243-258 ◽  
Author(s):  
Wen-Juan Ma ◽  
Fantin Carpentier ◽  
Tatiana Giraud ◽  
Michael E Hood
Keyword(s):  
Differential Expression ◽  
Differentially Expressed Genes ◽  
Mating Type ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Gc Content ◽  
Differentially Expressed ◽  
Mating Types ◽  
Sexual Antagonism ◽  
Recombination Suppression

Abstract Degenerative mutations in non-recombining regions, such as in sex chromosomes, may lead to differential expression between alleles if mutations occur stochastically in one or the other allele. Reduced allelic expression due to degeneration has indeed been suggested to occur in various sex-chromosome systems. However, whether an association occurs between specific signatures of degeneration and differential expression between alleles has not been extensively tested, and sexual antagonism can also cause differential expression on sex chromosomes. The anther-smut fungus Microbotryum lychnidis-dioicae is ideal for testing associations between specific degenerative signatures and differential expression because 1) there are multiple evolutionary strata on the mating-type chromosomes, reflecting successive recombination suppression linked to mating-type loci; 2) separate haploid cultures of opposite mating types help identify differential expression between alleles; and 3) there is no sexual antagonism as a confounding factor accounting for differential expression. We found that differentially expressed genes were enriched in the four oldest evolutionary strata compared with other genomic compartments, and that, within compartments, several signatures of sequence degeneration were greater for differentially expressed than non-differentially expressed genes. Two particular degenerative signatures were significantly associated with lower expression levels within differentially expressed allele pairs: upstream insertion of transposable elements and mutations truncating the protein length. Other degenerative mutations associated with differential expression included nonsynonymous substitutions and altered intron or GC content. The association between differential expression and allele degeneration is relevant for a broad range of taxa where mating compatibility or sex is determined by genes located in large regions where recombination is suppressed.

scholarly journals Deletion of the Schizophyllum commune Aα Locus: The Roles of Aα Y and Z Mating-Type Genes

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1437-1444
Author(s):  
C Ian Robertson ◽  
Kirk A Bartholomew ◽  
Charles P Novotny ◽  
Robert C Ullrich
Keyword(s):  
Mating Type ◽  
Sexual Development ◽  
Schizophyllum Commune ◽  
Mating Types ◽  
Developmental Pathway ◽  
Mating Type Gene ◽  
Mating Type Genes ◽  
Regulatory Loci ◽  
Type Gene

The Aα locus is one of four master regulatory loci that determine mating type and regulate sexual development in Schizophyllum commune. We have made a plasmid containing a URA1 gene disruption of the Aα Y1 gene. Y1 is the sole Aα gene in Aα1 strains. We used the plasmid construction to produce an Aα null (i.e., AαΔ) strain by replacing the genomic Y1 gene with URA1 in an Aα1 strain. To characterize the role of the Aα genes in the regulation of sexual development, we transformed various Aα Y and Z alleles into AαΔ strains and examined the acquired mating types and mating abilities of the transformants. These experiments demonstrate that the Aα Y gene is not essential for fungal viability and growth, that a solitary Z Aα mating-type gene does not itself activate development, that Aβ proteins are sufficient to activate the A developmental pathway in the absence of Aα proteins and confirm that Y and Z genes are the sole determinants of Aα mating type. The data from these experiments support and refine our model of the regulation of A-pathway events by Y and Z proteins.

Sign in / Sign up

Export Citation Format

Share Document