On the independence of barrage formation and heterokaryon incompatibility in Neurospora crassa

2003 ◽  
Vol 38 (2) ◽  
pp. 209-219 ◽  
Author(s):  
Cristina O Micali ◽  
Myron L Smith
Keyword(s):  
Neurospora Crassa ◽  
Heterokaryon Incompatibility

scholarly journals Isolation of Neurospora crassa A mating type mutants by repeat induced point (RIP) mutation.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 125-133 ◽  
Author(s):  
N L Glass ◽  
L Lee
Keyword(s):  
Neurospora Crassa ◽  
Mating Type ◽  
Single Copy ◽  
Open Reading Frame ◽  
Sexual Cycle ◽  
Reading Frame ◽  
Heterokaryon Incompatibility ◽  
Functional Regions ◽  
A Genome ◽  
Ascospore Formation

Abstract In the filamentous fungus, Neurospora crassa, mating type is regulated by a single locus with alternate alleles, termed A and a. The mating type alleles control entry into the sexual cycle, but during vegetative growth they function to elicit heterokaryon incompatibility, such that fusion of A and a hypha results in death of cells along the fusion point. Previous studies have shown that the A allele consists of 5301 bp and has no similarity to the a allele; it is found as a single copy and only within the A genome. The a allele is 3235 bp in length and it, too, is found as a single copy within the a genome. Within the A sequence, a single open reading frame (ORF) of 288 amino acids (mt A-1) is thought to confer fertility and heterokaryon incompatibility. In this study, we have used repeat induced point (RIP) mutation to identify functional regions of the A idiomorph. RIP mutations in mt A-1 resulted in the isolation of sterile, heterokaryon-compatible mutants, while RIP mutations generated in a region outside of mt A-1 resulted in the isolation of mutants capable of mating, but deficient in ascospore formation.

Characterization of hch , the Podospora anserina homolog of the het-c heterokaryon incompatibility gene of Neurospora crassa

2000 ◽  
Vol 38 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Sven J. Saupe ◽  
Corinne Clavé ◽  
Martine Sabourin ◽  
Joël Bégueret
Keyword(s):  
Neurospora Crassa ◽  
Podospora Anserina ◽  
Heterokaryon Incompatibility

Nuclear DNA degradation during heterokaryon incompatibility in Neurospora crassa

2003 ◽  
Vol 40 (2) ◽  
pp. 126-137 ◽  
Author(s):  
Stephen M. Marek ◽  
Jennifer Wu ◽  
N. Louise Glass ◽  
David G. Gilchrist ◽  
Richard M. Bostock
Keyword(s):  
Neurospora Crassa ◽  
Nuclear Dna ◽  
Dna Degradation ◽  
Heterokaryon Incompatibility

A SEARCH FOR COMPLEXITY AT THE MATING-TYPE LOCUS OF NEUROSPORA CRASSA

1973 ◽  
Vol 15 (3) ◽  
pp. 577-585 ◽  
Author(s):  
Dorothy Newmeyer ◽  
H. Branch Howe Jr. ◽  
Donna R. Galeazzi
Keyword(s):  
Neurospora Crassa ◽  
Mating Type ◽  
Adjacent Gene ◽  
Opposite Mating Type ◽  
Type Locus ◽  
Linked Gene ◽  
Heterokaryon Incompatibility ◽  
Mating Type Locus ◽  
Incompatibility Reaction ◽  
The Right

Evidence for complexity at the mating-type locus of Neurospora crassa was sought by selecting recombinants between closely linked markers on either side. All recombinants were tested for crossing ability, to test the hypothesis that the two mating-type alleles are actually closely linked self-sterile mutants; such tests should also detect subunits analogous to the α and β subunits of the A factor of Schizophyllum or Coprinus. No change in crossing ability was found among the 5,019 recombinants tested, representing 235,000 viable ascospores. The results indicate that if subunits exist, they are not more than 0.002 units apart. Twelve hundred and forty of the recombinants were tested in a way that should also have detected subunits analogous to the A and B factors of Schizophyllum and Coprinus, except that A and B would be closely linked. No such subunits were detected.N. crassa strains of opposite mating type are heterokaryon-incompatible during vegetative growth, and observations of various investigators have suggested that the heterokaryon incompatibility might be controlled by a separate closely-linked gene rather than by mating type itself. A sample of the recombinants was therefore tested for separation of the heterokaryon-incompatibility and crossing-compatibility functions. (Heterokaryon-incompatibility was scored by the presence of an incompatibility reaction in duplications heterozygous for mating type; this technique is simple and eliminates complications due to unlinked heterokaryon-incompatibility loci, several of which are known in N. crassa.) No separation was found. The results indicate that if an adjacent gene is responsible for the heterokaryon-incompatibility, it is not more than 0.0078 units from mating type, if on the left, and not more than 0.018 units from mating type, if on the right.

Suppressor mutants of Neurospora crassa that tolerate allelic differences at single or at multiple heterokaryon incompatibility loci.

Genetics ◽  
1994 ◽  
Vol 137 (3) ◽  
pp. 731-742 ◽  
Author(s):  
M T Arganoza ◽  
J Ohrnberger ◽  
J Min ◽  
R A Akins
Keyword(s):  
Neurospora Crassa ◽  
Integration Site ◽  
Pathogenic Fungi ◽  
Type Locus ◽  
Heterokaryon Incompatibility ◽  
Insertional Inactivation ◽  
Allelic Differences ◽  
Random Position ◽  
Suppressor Mutants ◽  
Spontaneous Mutants

Abstract Allelic differences at any one of at least 11 heterokaryon incompatibility (het) loci in Neurospora crassa trigger an incompatibility response: localized cell death at sites of hyphal anastomosis. We have isolated spontaneous and insertional suppressor mutants that are heterokaryon-compatible in spite of allelic differences at one or at several het loci. Some intra- and extragenic mutants tolerated allelic differences only at single het loci. Multi-tolerant spontaneous mutants were isolated by selecting simultaneously for tolerance of differences at het-c, -d and -e, or at each of these plus mating-type. Some suppressor mutants were specific for only one allele at the affected het locus; others suppressed both alleles. Insertional mutations were isolated from banks of transformants, each having a plasmid integrated into a random position in the chromosome. One mutant tolerated allelic differences at het-d. A homologous cosmid from a Neurospora genomic bank complemented the mutant phenotype. A second insertional inactivation mutant was tolerant of het-c differences. Inactivation of the wild-type locus corresponding to the integration site was accomplished by repeat-induced point mutation (RIP). The RIP progeny, like the original mutant, were tolerant of differences at het-c. It may be possible to use such suppressor mutants as universal donors of hypovirulence in pathogenic fungi.

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