Control of mating type heterokaryon incompatibility by the tol gene in Neurospora crassa and N. tetrasperma

Genome ◽  
1992 ◽  
Vol 35 (2) ◽  
pp. 347-353 ◽  
Author(s):  
David J. Jacobson
Keyword(s):  
Sexual Reproduction ◽  
Neurospora Crassa ◽  
Mating Type ◽  
Genetic System ◽  
Dual Function ◽  
Wild Type Allele ◽  
Wild Type ◽  
Type Allele ◽  
Heterokaryon Incompatibility ◽  
Active Allele

The mating-type of Neurospora crassa (A and a) have a dual function: A and a individuals are required for sexual reproduction, but only strains of the same mating type will form a stable vegetative heterokaryon. Neurospora tetrasperma, in contrast, is a naturally occurring A + a heterokaryon. It was shown previously that the mating-type genes of both species are functionally the same and are not responsible for this difference in heterokaryon incompatibility. This suggests that a separate genetic system determines the heterokaryon incompatibility function of mating type. The mutant tolerant (tol) in N. crassa, unlinked to mating type, acts as a specific suppressor of A + a heterokaryon incompatibility. In the present study, the wild-type alleles at the tol locus were introgressed reciprocally, from N. crassa into N. tetrasperma and from N. tetrasperma into N. crassa, to investigate the action of these alleles in the A + a heterokaryon incompatibility systems of these species. The wild-type allele from N. tetrasperma (tolT) acts as a recessive suppressor of A + a heterokaryon incompatibility in N. crassa. Furthermore, the wild-type allele from N. crassa (tolC) causes A and a to become heterokaryon incompatible in N. tetrasperma, while having no effect on the sexual reproduction. Therefore, the tol gene plays a major role in determining the heterokaryon compatibility of mating type in these species: tolC is an active allele that causes incompatibility and tolT an inactive allele that suppresses incompatibility by its inactivity.Key words: heterokaryon incompatibility, vegetative incompatibility, Neurospora, suppressors, mating type.

scholarly journals DOMINANCE MODIFIERS IN NEUROSPORA CRASSA: PHENOCOPY SELECTION AND INFLUENCE ON CERTAIN ASCUS MUTANTS

Genetics ◽  
1972 ◽  
Vol 71 (2) ◽  
pp. 233-245
Author(s):  
Peter J Russell ◽  
Adrian M Srb
Keyword(s):  
Neurospora Crassa ◽  
Mutant Allele ◽  
Detectable Effect ◽  
Wild Type Allele ◽  
Wild Type ◽  
Group V ◽  
Type Allele ◽  
Dominance Relationships ◽  
Mutant Strains ◽  
Dominant Peak

ABSTRACT When homozygous in zygotes, mutant alleles at the peak locus in linkage group V of Neurospora crassa initiate aberrant asci that are nonlinear, in contrast to the linear asci characteristic of wild type. Most mutant alleles are recessive, inasmuch as crosses of the mutant strains with wild type give linear asci. However, five different mutant alleles, when heterozygous with the wild-type allele, act in varying degrees as zygote dominants, initiating both linear and nonlinear asci, the relative proportions depending on the allele. Five modifiers that act on the dominance relationships of at least one of the five possible heterozygotes of a dominant peak and its wild-type allele have been characterized, four of them having been obtained by selection directed against a phenocopy of these mutants induced by treatment of wild type with l-sorbose. The pattern of modifier specificity observed among the various dominant peak heterozygotes indicates that the phenotypic effects are produced by a complex relationship between the modifiers and the dominant peak alleles in relation to their wild-type allele. In all but two cases the direction of modification, where present, is towards decreasing the dominance of the mutant allele in the heterozygote, evidenced by an increase in the percentage of linear asci when compared with control data. The modifiers exert their maximum modification when they themselves are heterozygous with their wild-type alleles and when the dominant peak allele is heterozygous with its wild-type allele. No modification occurs when heterozygous modifiers are included in zygotes homozygous for a dominant peak allele, reinforcing the notion that the modifiers act on the dominance relationship existent between a dominant peak allele and its wild-type allele, rather than influencing some activity of the mutant allele itself. The modifiers have no detectable effect of their own on ascus morphology, since homozygous modifier zygotes initiate entirely linear asci when only wild-type alleles of peak are present in the zygotes. Their only detectable effect, other than dominance modification, appears to be in conferring sorbose resistance to the mycelium. The modifiers are unlinked to the peak locus, and, except for two of them, they are nonallelic.

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 A Role of Calcium Signaling Genes in Heterokaryon Incompatibility in Neurospora crassa

2015 ◽  
Vol 3 (4) ◽  
pp. 668-679
Author(s):  
Ravi Gedela ◽  
Ranjan Tamuli
Keyword(s):  
Neurospora Crassa ◽  
Mating Type ◽  
Gene Deletion ◽  
Deletion Mutants ◽  
Gene Products ◽  
Wild Type ◽  
Heterokaryon Incompatibility ◽  
Knockout Mutants ◽  
Wild Type Control

We have studied the Ca2+-signaling knockout mutants for their role in mating-type-associated heterokaryon incompatibility in Neurospora crassa.  The found results showed on heterokaryons homokaryosis for DNCU05225, DNCU06366, DNCU06650, DNCU07075, and ∆NCU07966 Ca2+-signaling knockout mutants (Neurospora crassa unit number, NCU) displayed heterokaryon het compatibility; however heterokaryons heterokaryosis for DNCU05225, DNCU063665, DNCU06650, DNCU07075, and ∆NCU07966 mutants displayed het incompatibility like the wild-type control.  In addition to that Two Ca2+-signaling knockout mutants DNCU02283, and DNCU09655 were tested for mating-type-associated heterokaryon incompatibility; these results showed, heterokaryons homokaryosis and heterokaryons heterokaryosis for DNCU02283, DNCU09655 mutants displayed het incompatibility.  Cell death and hyphal compartmentation due to mating type associated incompatibility were confirmed by uptake of vital dye Evan’s blue.  Thus, these results of NCU05225, NCU06366, NCU06650, NCU07075, and NCU07966 Ca2+-signaling gene products could play a role in mating-type-associated heterokaryon incompatibility in N. crassa.  In this article, we are reporting initially screened Ca2+-signaling gene deletion mutants of these five acts as recessive suppressors of mating type associated vegetative incompatibility in N. crassa.Int J Appl Sci Biotechnol, Vol 3(4): 668-679

scholarly journals CYP2C19 Polymorphisms in Indonesia: Comparison among Ethnicities and the Association with Clinical Outcomes

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 300
Author(s):  
Muhammad Miftahussurur ◽  
Dalla Doohan ◽  
Ari Fahrial Syam ◽  
Iswan Abbas Nusi ◽  
Phawinee Subsomwong ◽  
...  
Keyword(s):  
Proton Pump Inhibitor ◽  
Clinical Outcomes ◽  
Proton Pump ◽  
Poor Metabolizers ◽  
Wild Type Allele ◽  
Wild Type ◽  
Type Allele ◽  
Sydney System ◽  
Intermediate Metabolizers ◽  
Cyp2c19 Polymorphisms

CYP2C19 polymorphisms are important factors for proton pump inhibitor-based therapy. We examined the CYP2C19 genotypes and analyzed the distribution among ethnicities and clinical outcomes in Indonesia. We employed the polymerase chain reaction-restriction fragment length polymorphism method to determine the CYP2C19 genotypes and evaluated inflammation severity with the updated Sydney system. For CYP2C19*2, 46.4% were the homozygous wild-type allele, 14.5% were the homozygous mutated allele, and 39.2% were the heterozygous allele. For CYP2C19*3, 88.6% were the homozygous wild-type allele, 2.4% were the homozygous mutated allele, and 9.0% were the heterozygous allele. Overall, the prevalence of rapid, intermediate, and poor metabolizers in Indonesia was 38.5, 41.6, and 19.9%, respectively. In the poor metabolizer group, the frequency of allele *2 (78.8%) was higher than the frequency of allele *3 (21.2%). The Papuan had a significantly higher likelihood of possessing poor metabolizers than the Balinese (OR 11.0; P = 0.002). The prevalence of poor metabolizers was lower compared with the rapid and intermediate metabolizers among patients with gastritis and gastroesophageal reflux disease. Intermediate metabolizers had the highest prevalence, followed by rapid metabolizers and poor metabolizers. Dosage adjustment should therefore be considered when administering proton pump inhibitor-based therapy in Indonesia.

Monoallelic Expression of Pax5: A Paradigm for the Haploinsufficiency of Mammalian Pax Genes?

1999 ◽  
Vol 380 (6) ◽  
Author(s):  
S.L. Nutt ◽  
M. Busslinger
Keyword(s):  
Human Disease ◽  
Mouse Genome ◽  
Monoallelic Expression ◽  
Wild Type Allele ◽  
Loss Of Function ◽  
Wild Type ◽  
Type Allele ◽  
Pax Genes ◽  
Default State ◽  
Mammalian Genes

AbstractIt is generally assumed that most mammalian genes are transcribed from both alleles. Hence, the diploid state of the genome offers the advantage that a loss-of-function mutation in one allele can be compensated for by the remaining wild-type allele of the same gene. Indeed, the vast majority of human disease syndromes and engineered mutations in the mouse genome are recessive, indicating that recessiveness is the ‘default’ state. However, a minority of genes are semi-dominant, as heterozygous loss-of-function mutation in these genes leads to phenotypic abnormalities. This condition, known as haploinsufficiency, has been described for five of the nine mammalian

ESCAPE FROM MATING-TYPE INCOMPATIBILITY IN BISEXUAL (A + a) NEUROSPORA HETEROKARYONS

1975 ◽  
Vol 17 (3) ◽  
pp. 441-449 ◽  
Author(s):  
A. M. DeLange ◽  
A. J. F. Griffiths
Keyword(s):  
Mating Type ◽  
Loss Of Function ◽  
Wild Type ◽  
Opposite Mating Type ◽  
Type Locus ◽  
Heterokaryon Incompatibility ◽  
Recessive Mutant ◽  
Type Rate ◽  
Wild Type Rate ◽  
Incompatibility Locus

In Neurospora crassa, strains of opposite mating type generally do not form stable heterokaryons because the mating type locus acts as a heterokaryon incompatibility locus. However, when one A and one a strain, having complementing auxotrophic mutants, are placed together on minimal medium, growth may occur, although the growth is generally slow. In this study, escape from such slow growth to that at a wild type or near-wild type rate was observed. The escaped cultures are stable heterokaryons, mostly having lost the mating type allele function from one component nucleus, so that the nuclear types are heterokaryon compatible. Either A or a mating type can be lost. This loss of function has been attributed to deletion since only one nuclear type could be recovered in all heterokaryons except one, but deletion spanning adjacent loci has been directly demonstrated in a minority of cases. Alternatively when one component strain is tol and the other tol+ (tol being a recessive mutant suppressing the heterokaryon incompatibility associated with mating type), escape may occur by the deletion or mutation of tol+, also resulting in heterokaryon compatibility. An induction mechanism for escape is speculated upon.

Multiple Congenital Ocular Anomalies in a silver coat Missouri Fox Trotter stallion

2021 ◽  
Vol 49 (05) ◽  
pp. 350-354
Author(s):  
Verena Maria Herb ◽  
Verena Zehetner ◽  
Klaas-Ole Blohm
Keyword(s):  
Missense Mutation ◽  
Coat Color ◽  
Incidental Finding ◽  
Unknown Origin ◽  
Allelic Frequency ◽  
Cystic Lesions ◽  
Wild Type Allele ◽  
Wild Type ◽  
Type Allele ◽  
Phenotype Characterization

AbstractThis is the first description of Multiple Congenital Ocular Anomalies (MCOA) in a silver coat Missouri Fox Trotter determined to be heterozygous for the Silver PMEL17 missense mutation associated with MCOA and a silver coat in other breeds. The stallion was treated for meningoencephalitis and bilateral uveitis of unknown origin. A complete ophthalmic examination and ocular ultrasonography were performed. As an incidental finding, the patient exhibited bilateral cystic lesions restricted to the temporal anterior uvea consistent with the Cyst phenotype and was genotyped heterozygous for the Silver mutation. Additionally, 4 other non-silver colored Missouri Fox Trotters were genotyped homozygous for the wild-type allele. Screening for PMEL17 mutation in Missouri Fox Trotters accompanied by ophthalmic phenotype characterization is recommended to determine the allelic frequency and facilitate informed breeding decisions since the silver coat color is particularly popular.

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.

scholarly journals GENETIC ANALYSIS OF THREE DOMINANT FEMALE-STERILE MUTATIONS LOCATED ON THE X CHROMOSOME OF DROSOPHILA MELANOGASTER

Genetics ◽  
1983 ◽  
Vol 105 (2) ◽  
pp. 309-325
Author(s):  
D Busson ◽  
M Gans ◽  
K Komitopoulou ◽  
M Masson
Keyword(s):  
X Chromosome ◽  
Germ Line ◽  
Female Sterility ◽  
Recessive Mutation ◽  
Wild Type Allele ◽  
Wild Type ◽  
Allelic Series ◽  
Type Allele ◽  
Dominant Female ◽  
Female Germ Line

ABSTRACT Three dominant female-sterile mutations were isolated following ethyl methanesulfonate (EMS) mutagenesis. Females heterozygous for two of these mutations show atrophy of the ovaries and produce no eggs (ovoD  1) or few eggs (ovoD  2); females heterozygous for the third mutation, ovoD  3, lay flaccid eggs. All three mutations are germ line-dependent and map to the cytological region 4D-E on the X chromosome; they represent a single allelic series. Two doses of the wild-type allele restore fertility to females carrying ovoD  3 and ovoD  2, but females carrying ovoD  1 and three doses of the wild-type allele remain sterile. The three mutations are stable in males but are capable of reversion in females; reversion of the dominant mutations is accompanied by the appearance, in the same region, of a recessive mutation causing female sterility. We discuss the utility of these mutations as markers of clones induced in the female germ line by mitotic recombination as well as the nature of the mutations.

scholarly journals Short and sweet: foreleg abnormalities in Havanese and the role of the FGF4 retrogene

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Kim K. L. Bellamy ◽  
Frode Lingaas
Keyword(s):  
Mutant Allele ◽  
Large Degree ◽  
Population Increase ◽  
Wild Type Allele ◽  
Wild Type ◽  
Gradual Decline ◽  
Type Allele ◽  
Population Frequency ◽  
Welfare Implications

Abstract Background Cases of foreleg deformities, characterized by varying degrees of shortened and bowed forelegs, have been reported in the Havanese breed. Because the health and welfare implications are severe in some of the affected dogs, further efforts should be made to investigate the genetic background of the trait. A FGF4-retrogene on CFA18 is known to cause chondrodystrophy in dogs. In most breeds, either the wild type allele or the mutant allele is fixed. However, the large degree of genetic diversity reported in Havanese, could entail that both the wild type and the mutant allele segregate in this breed. We hypothesize that the shortened and bowed forelegs seen in some Havanese could be a consequence of FGF4RG-associated chondrodystrophy. Here we study the population prevalence of the wild type and mutant allele, as well as effect on phenotype. We also investigate how the prevalence of the allele associated with chondrodystrophy have changed over time. We hypothesize that recent selection, may have led to a gradual decline in the population frequency of the lower-risk, wild type allele. Results We studied the FGF4-retrogene on CFA18 in 355 Havanese and found variation in the presence/absence of the retrogene. The prevalence of the non-chondrodystrophic wild type is low, with allele frequencies of 0.025 and 0.975 for the wild type and mutant allele, respectively (linked marker). We found that carriers of the beneficial wild type allele were significantly taller at the shoulder than mutant allele homozygotes, with average heights of 31.3 cm and 26.4 cm, respectively. We further found that wild type carriers were born on average 4.7 years earlier than mutant allele homozygotes and that there has been a gradual decline in the population frequency of the wild type allele during the past two decades. Conclusions Our results indicate that FGF4RG-associated chondrodystrophy may contribute to the shortened forelegs found in some Havanese and that both the wild type and mutant allele segregate in the breed. The population frequency of the wild type allele is low and appear to be decreasing. Efforts should be made to preserve the healthier wild type in the population, increase the prevalence of a more moderate phenotype and possibly reduce the risk of foreleg pathology.

Sign in / Sign up

Export Citation Format

Share Document