Characterization of mat A-2, mat A-3 and ΔmatA Mating-Type Mutants of Neurospora crassa

Genetics ◽  
1998 ◽  
Vol 148 (3) ◽  
pp. 1069-1079 ◽  
Author(s):  
Adlane V-B Ferreira ◽  
Zhiqiang An ◽  
Robert L Metzenberg ◽  
N Louise Glass
Keyword(s):  
Neurospora Crassa ◽  
Mating Type ◽  
Sexual Development ◽  
Vegetative Growth ◽  
Double Mutant ◽  
Sexual Cycle ◽  
Wild Type ◽  
Type Locus ◽  
Isolation And Characterization

AbstractThe mating-type locus of Neurospora crassa regulates mating identity and entry into the sexual cycle. The mat A idiomorph encodes three genes, mat A-1, mat A-2, and mat A-3. Mutations in mat A-1 result in strains that have lost mating identity and vegetative incompatibility with mat a strains. A strain containing mutations in both mat A-2 and mat A-3 is able to mate, but forms few ascospores. In this study, we describe the isolation and characterization of a mutant deleted for mat (ΔmatA), as well as mutants in either mat A-2 or mat A-3. The ΔmatA strain is morphologically wild type during vegetative growth, but it is sterile and heterokaryon compatible with both mat A and mat a strains. The mat A-2 and mat A-3 mutants are also normal during vegetative growth, mate as a mat A strain, and produce abundant biparental asci in crosses with mat a, and are thus indistinguishable from a wild-type mat A strain. These data and the fact that the mat A-2 mat A-3 double mutant makes few asci with ascospores indicate that MAT A-2 and MAT A-3 are redundant and may function in the same pathway. Analysis of the expression of two genes (sdv-1 and sdv-4) in the various mat mutants suggests that the mat A polypeptides function in concert to regulate the expression of some sexual development genes.

scholarly journals Molecular Characterization of tol, a Mediator of Mating-Type-Associated Vegetative Incompatibility in Neurospora crassa

Genetics ◽  
1999 ◽  
Vol 151 (2) ◽  
pp. 545-555 ◽  
Author(s):  
Patrick Ka Tai Shiu ◽  
N Louise Glass
Keyword(s):  
Sexual Reproduction ◽  
Neurospora Crassa ◽  
Mating Type ◽  
Vegetative Growth ◽  
Point Mutations ◽  
Coiled Coil ◽  
Wild Type ◽  
Opposite Mating Type ◽  
Type Locus

Abstract The mating-type locus in the haploid filamentous fungus, Neurospora crassa, controls mating and sexual development. The fusion of reproductive structures of opposite mating type, A and a, is required to initiate sexual reproduction. However, the fusion of hyphae of opposite mating type during vegetative growth results in growth inhibition and cell death, a process that is mediated by the tol locus. Mutations in tol are recessive and suppress mating-type-associated heterokaryon incompatibility. In this study, we describe the cloning and characterization of tol. The tol gene encodes a putative 1011-amino-acid polypeptide with a coiled-coil domain and a leucine-rich repeat. Both regions are required for tol activity. Repeat-induced point mutations in tol result in mutants that are wild type during vegetative growth and sexual reproduction, but that allow opposite mating-type individuals to form a vigorous heterokaryon. Transcript analyses show that tol mRNA is present during vegetative growth but absent during a cross. These data suggest that tol transcription is repressed to allow the coexistence of opposite mating-type nuclei during the sexual reproductive phase. tol is expressed in a mat A, mat a, A/a partial diploid and in a mating-type deletion strain, indicating that MAT A-1 and MAT a-1 are not absolutely required for transcription or repression of tol. These data suggest that TOL may rather interact with MAT A-1 and/or MAT a-1 (or downstream products) to form a death-triggering complex.

scholarly journals REGULATION OF PHOSPHATE METABOLISM IN NEUROSPORA CRASSA. CHARACTERIZATION OF REGULATORY MUTANTS

Genetics ◽  
1973 ◽  
Vol 75 (1) ◽  
pp. 61-73
Author(s):  
John F Lehman ◽  
Mary K Gleason ◽  
Sandra K Ahlgren ◽  
Robert L Metzenberg
Keyword(s):  
Alkaline Phosphatase ◽  
Neurospora Crassa ◽  
Control Systems ◽  
Double Mutant ◽  
Phosphorus Metabolism ◽  
Phosphate Metabolism ◽  
Wild Type Allele ◽  
Wild Type ◽  
High Affinity

ABSTRACT A mutant of Neurospora crassa, called UW-6, differs from wild type in being partially constitutive for synthesis of a species of alkaline phosphatase, and also for a species of phosphate permease that has a high affinity for phosphate at high pH. UW-6 is possibly allelic with a mutant called nuc-2 that was previously isolated by Ishikawa. nuc-2 has the converse phenotype, in that it cannot be derepressed for either of these two activities. UW-6 is co-dominant with its wild-type allele in heterokaryons and in partial diploids. An unlinked mutant, nuc-1, is like nuc-2 in that it fails to make the alkaline phosphatase or the permease referred to above. nuc-1 is epistatic to UW-6 in the double mutant. The control of phosphorus metabolism is discussed, and is compared with some other control systems in filamentous fungi.

scholarly journals ISOLATION AND CHARACTERIZATION OF NEUROSPORA MUTANTS AFFECTED IN INVERTASE SYNTHESIS

Genetics ◽  
1984 ◽  
Vol 106 (4) ◽  
pp. 591-599
Author(s):  
Deborah B Lee ◽  
Stephen J Free
Keyword(s):  
Neurospora Crassa ◽  
Large Scale ◽  
Invertase Activity ◽  
Free Medium ◽  
Wild Type ◽  
Isolation And Characterization ◽  
Normal Enzyme ◽  
Enzyme Molecules ◽  
Large Scale Screening

ABSTRACT We have outlined a procedure that allows the large-scale screening of mutagenized Neurospora crassa populations for invertaseless mutants. We have isolated and characterized three mutations, inv(DBL1), inv(DBL9) and inv(DBL14), which have been mapped at or near the invertase structural gene. One of these, inv(DBL1), is particularly interesting. Our experiments indicate that the reduced level of invertase activity in the inv(DBL1)-containing cell can be explained as the result of a reduced number of normal enzyme molecules. We also show that wild-type Neurospora is able to respond rapidly to a change of medium and can dramatically increase its production of invertase within 20 min after a transfer to a carbon-free medium.

Isolation and characterization of the mating type locus of Mycosphaerella fijiensis, the causal agent of black leaf streak disease of banana

2007 ◽  
Vol 8 (1) ◽  
pp. 111-120 ◽  
Author(s):  
LAURA CONDE-FERRÁEZ ◽  
CEES WAALWIJK ◽  
BLONDY B. CANTO-CANCHÉ ◽  
GERT H. J. KEMA ◽  
PEDRO W. CROUS ◽  
...  
Keyword(s):  
Mating Type ◽  
Causal Agent ◽  
Mycosphaerella Fijiensis ◽  
Type Locus ◽  
Mating Type Locus ◽  
Isolation And Characterization ◽  
Black Leaf Streak ◽  
Black Leaf Streak Disease

scholarly journals A Putative Rhamnogalacturonase Required for Sexual Development of Neurospora crassa

Genetics ◽  
1997 ◽  
Vol 146 (2) ◽  
pp. 531-540 ◽  
Author(s):  
Mary Anne Nelson ◽  
Sandra T Merino ◽  
Robert L Metzenberg
Keyword(s):  
Neurospora Crassa ◽  
Filamentous Fungus ◽  
Sexual Development ◽  
Mitotic Division ◽  
Sexual Cycle ◽  
Wild Type ◽  
Aspergillus Aculeatus ◽  
Large Numbers ◽  
Sexual Progeny

In previous work, the asd-1 (ascus development) gene of the filamentous fungus Neurospora crassa was identified as a gene expressed preferentially during the sexual cycle and shown to be essential for normal sexual development. The asd-1 gene has been sequenced and further characterized. It contains two introns, the first of which is in-frame and inefficiently or differentially spliced. The predicted ASD-1 protein has extensive homology with rhamnogalacturonase B of Aspergillus aculeatus, which cleaves the backbone within the ramified hairy regions of pectin. In homozygous asd-1 crosses, sexual development is initiated and large numbers of normal-sized asci are formed. Ascospore delineation does not occur, however, and no sexual progeny are produced. As most asd-1 asci contain eight nuclei, the two meiotic divisions and subsequent mitotic division typical of normal crosses seem to occur, but the haploid nuclei are not partitioned into ascospores. In wild-type crosses, the ASD-1 protein is present in large amounts in croziers and young asci, but it is only faintly detectable in more mature asci containing developing ascospores. Models to explain the possible role of a rhamnogalacturonase in sexual development are presented.

scholarly journals Isolation and Characterization of a Temperature-Sensitive Circadian Clock Mutant of Neurospora crassa

Genetics ◽  
1997 ◽  
Vol 146 (2) ◽  
pp. 525-530 ◽  
Author(s):  
Louis W Morgan ◽  
Jerry F Feldman
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Mutant Strain ◽  
Double Mutant ◽  
Period Length ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Isolation And Characterization ◽  
Double Mutant Strain ◽  
Clock Mutant

A new circadian clock mutant has been isolated in Neurospora crassa. This new mutation, called period-6 (pd-6), has two features novel to known clock mutations. First, the mutation is temperature sensitive. At restrictive temperatures (above 21°) the mutation shortens circadian period length from a wild-type value of 21.5 hr to 18 hr. At permissive temperatures (below 21°) the mutant has a 20.5-hr period length close to that of the wild-type strain. Second, the prd-6 mutation is epistatic to the previously isolated clock mutation period-2 (prd-2). This epistasis is unusual in that the prd-2 prd-6 double mutant strain has an 18-hr period length at both the restrictive and permissive temperatures. That is, the temperature-sensitive aspect of the phenotype of the prd-6 strain is lost in the prd-2 prd-6 double mutant strain. This suggests that the gene products of the prd-2 and prd-6 loci may interact physically and that the presence of a normal prd-2+ protein is required for low temperature to “rescue” the prd-6 mutant phenotype. These results, combined with our recent finding that prd-2 and some alleles of the frq gene show genetic synergy, suggest that it may be possible to establish a more comprehensive model of the Neurospora circadian clock.

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