Evidence for a multi-allelic heterokaryon incompatibility (het) locus detected by hybridization among three heterokaryon- compatibility (h–c) groups of Aspergillus nidulans

Dales, R. B. G.; Moorhouse, J; Croft, J. H.

doi:10.1038/hdy.1993.77

Cited by 17 publications

(12 citation statements)

References 9 publications

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“…Based on TINC's high sequence similarity to Het-C, 25 A. nidulans isolates representing 21 heterokaryon compatibility groups (1,7,8) were sequenced at the tinC locus to determine whether tinC was multiallelic and potentially involved in heterokaryon incompatibility reactions in Aspergillus (data not shown). This sequencing identified no significant sequence differences at the tinC locus, suggesting that TINC may not participate in heterokaryon compatibility determination in Aspergillus.…”

Section: Resultsmentioning

confidence: 99%

Potential Link between the NIMA Mitotic Kinase and Nuclear Membrane Fission during Mitotic Exit inAspergillus nidulans

et al. 2004

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We have isolated TINC as a NIMA-interacting protein by using the yeast two-hybrid system and have confirmed that TINC interacts with NIMA in Aspergillus nidulans. The TINC-NIMA interaction is stabilized in the absence of phosphatase inhibitors and in the presence of kinase-inactive NIMA, suggesting that the interaction is enhanced when NIMA is not fully activated. TINC is a cytoplasmic protein. TINC homologues and a TINC-like protein (A. nidulans HETC) are conserved in other filamentous fungi. Neither deletion of tinC nor deletion of both tinC and A. nidulans hetC is lethal, but deletion of tinC does produce cold sensitivity as well as osmotic sensitivity. Expression of an amino-terminal-truncated form of TINC (⌬N-TINC) inhibits colony growth in Aspergillus and localizes to membrane-like structures within the cell. Examination of cell cycle progression in these cells reveals that they progress through multiple defective mitoses. Many cells contain large polyploid single nuclei, while some appear to have separated masses of DNA. Examination of the nuclear envelopes of cells containing more than one DNA mass reveals that both DNA masses are contained within a single nuclear envelope, indicating that nuclear membrane fission is defective. The ability of these cells to separate DNA segregation from nuclear membrane fission suggests that this coordination is normally a regulated process in A. nidulans. Additional experiments demonstrate that expression of ⌬N-TINC results in premature NIMA disappearance in mitotic samples. We propose that TINC's interaction with NIMA and the cell cycle defects produced by ⌬N-TINC expression suggest possible roles for TINC and NIMA during nuclear membrane fission.Entry into mitosis represents the irreversible commitment by a cell to segregate duplicated DNA equally to form two independent nuclei. Entry into mitosis with damaged DNA or incompletely replicated DNA, failure to establish a proper bipolar spindle, and premature exit from mitosis can all have disastrous consequences for the cell. As such, entry into, progression through, and exit from mitosis are all highly regulated cell cycle transitions. In all eukaryotes, one of the central triggers for mitotic entry is the activation of the cyclin-dependent kinase CDC2 (12,21,30). In Aspergillus nidulans, the NIMA (never in mitosis A) kinase is also required for mitotic entry, as cells with active CDC2 and inactive NIMA are unable to enter mitosis (32).Two lines of evidence suggest that a NIMA pathway of cell cycle regulation exists in a wide range of organisms. Ectopic expression of NIMA in metazoan cells can induce some of the hallmarks of mitotic onset, including DNA condensation and germinal vesicle breakdown (25). Also, NIMA-related kinases (Nek) have been identified in a range of organisms, including yeast, flies, frogs, mice, and humans (29). Additionally, mitotic regulatory roles have been identified for the Fin1p kinase (15,16,22,23) from Schizosaccharomyces pombe as well as for a number of mammalian Nek kinases, including Nek2...

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Section: Resultsmentioning

confidence: 99%

Potential Link between the NIMA Mitotic Kinase and Nuclear Membrane Fission during Mitotic Exit inAspergillus nidulans

et al. 2004

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“…When two strains have a different allele for a partial-het gene they are partially somatically incompatible (Coenen et al, 1994). Most pairs of A. nidulans isolates are somatically incompatible (Grindle, 1963 a, b ;Croft & Jinks, 1977 ;Anwar et al, 1993 ;Dales et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

Factors affecting the spread of double-stranded RNA viruses in Aspergillus nidulans

Coenen¹,

Kevei²,

Hoekstra³

1997

Genet. Res.

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SummaryViruses are common in asexual Aspergilli but not in sexual Aspergilli. We found no viruses in 112 isolates of the sexual Aspergillus nidulans. We have investigated factors that could play a role in preventing the spread of mycoviruses through populations of A. nidulans. Experiments were performed with A. nidulans strains infected with viruses originating from A. niger. Horizontal virus transmission was restricted but not prevented by somatic incompatibility. Viruses were transmitted vertically via conidiospores but not via ascospores. Competition experiments revealed no effect of virus infection on host fitness. Outcrossing was found to limit the spread of viruses significantly more than selfing. It is concluded that the exclusion of viruses from sexual Aspergilli could be due to the formation of new somatic incompatibility groups by sexual recombination.

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“…In comparison with strains of h-cGL, strains of h-cA were found to differ at six het loci (Dales & Croft, 1990;Dales et al, 1993), h-cB strains at two loci , and h-cQ strains at five loci . A sexual crossing programme between strains of h-cA and h-cB has shown that these two groups differ at seven het loci (Dales et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

“…A sexual crossing programme between strains of h-cA and h-cB has shown that these two groups differ at seven het loci (Dales et al, 1993). Seven het loci is the minimum 0001-7927 0 1993 SGM M .…”

Section: Introductionmentioning

confidence: 99%

“…Diploid strains were haploidized and the progenies analysed for the segregation of compatibility determinants , 1990. The sexual approach is not impeded in any significant way by the heterokaryon incompatibility system (Jinks et al, 1966;Butcher, 1968;Dales et al, 1993) as hybrid cleistothecia can be isolated readily from heterokaryon incompatible parents and ascospore samples analysed for compatibility segregation.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of heterokaryon incompatibility between heterokaryon-compatibility (h-c) groups R and GL provides evidence that at least eight het loci control somatic incompatibility in Aspergillus nidulans

Anwar

Croft²,

Dales³

1993

Journal of General Microbiology

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Protoplast fusion was used to hybridize strains 99-6 (h-cR) and 7-141 (h-cGL) in the Birmingham collection ofAspergillus nidulans. A sparsely conidiating, brown-pigmented diploid strain (MA7) was isolated. Inocula from MA7 were haploidized on medium containing Benlate and a haploid progeny sample collected. Heterokaryon compatibility testing of selected progeny strains assayed each linkage group in turn and established that h-cR and h-cGL were hetero-allelic for heterokaryon incompatibility (het) loci located on linkage groups I11 and V. Two selected MA7 progeny strains were sexually crossed to an h-cGL strain. Compatibility classification of the progenies of these crosses indicated that three het genes were located on linkage group I11 and two on linkage group V. Combination of these results with previous work using h-c groups A, B and Q in comparison with h-cGL indicates that a minimum number of eight and a maximum number of 18 het loci, spread over five linkage groups, are necessary to explain the compatibility relationships among these five h-c groups.

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Evidence for a multi-allelic heterokaryon incompatibility (het) locus detected by hybridization among three heterokaryon- compatibility (h–c) groups of Aspergillus nidulans

Cited by 17 publications

References 9 publications

Potential Link between the NIMA Mitotic Kinase and Nuclear Membrane Fission during Mitotic Exit inAspergillus nidulans

Potential Link between the NIMA Mitotic Kinase and Nuclear Membrane Fission during Mitotic Exit inAspergillus nidulans

Factors affecting the spread of double-stranded RNA viruses in Aspergillus nidulans

Analysis of heterokaryon incompatibility between heterokaryon-compatibility (h-c) groups R and GL provides evidence that at least eight het loci control somatic incompatibility in Aspergillus nidulans

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