The Experts below are selected from a list of 2094 Experts worldwide ranked by ideXlab platform
Michael G. Milgroom - One of the best experts on this subject based on the ideXlab platform.
-
Heterokaryons and parasexual recombinants of cryphonectria parasitica in two clonal populations in southeastern europe
Fungal Genetics and Biology, 2009Co-Authors: Michael G. Milgroom, Kiril Sotirovski, Mihajlo Risteski, Marin Talbot BrewerAbstract:Evidence for parasexuality in natural populations of haploid fungi requires the demonstration of diploids or Heterokaryons and recombinant genotypes in the absence of sex. We studied clonal populations of the chestnut blight fungus, Cryphonectria parasitica, in southeastern Europe and found evidence of parasexuality in two locations. In Osoj, Macedonia, we found one isolate (Os05-66) that had two alleles at six codominant loci, giving a haplotype that was a composite of two clones in this population. Six single-conidial isolates from Os05-66 had two alleles at some loci, suggesting partial diploidy or aneuploidy, and we found four recombinant haplotypes among single-conidial isolates from hyphal-tip isolates of the same isolate. In Teano, Italy, we found two Heterokaryon isolates that were partial composites of two dominant clones. Single-conidial isolates from hyphal-tip isolates had recombinant haplotypes. These results provide evidence that is consistent with the hypothesis of parasexuality in C. parasitica in Europe, similar to an earlier report in a natural population in the USA.
-
Heterokaryon incompatibility function of barrage associated vegetative incompatibility genes vic in cryphonectria parasitica
Mycologia, 2006Co-Authors: Myron L. Smith, Carmen C Gibbs, Michael G. MilgroomAbstract:Six vegetative incompatibility (vic) loci have been identified in Cryphonectria parasitica based on barrage formation during mycelial interactions. We used hygromycin B- and benomyl-resistance as forcing markers in C. parasitica strains to test whether heteroallelism at each vic locus prevents Heterokaryon formation following mycelial interactions. Paired strains that had allelic differences at any of vic1, 2, 3, 6 or 7 but not vic4 displayed Heterokaryon incompatibility function, as recognized by slow growth or aberrant morphology. While clearly forming barrages in mycelial interactions, paired strains with different alleles at vic4 formed stable Heterokaryons. With examples from other fungi, this inconsistency at vic4 suggests that barrage formation and Heterokaryon incompatibility are not different manifestations of the same process. Rather, the evidence indicates that Heterokaryon incompatibility represents a component of a vegetative incompatibility system that may also use cell-surface or extracellular factors to trigger programmed cell death to modulate nonself recognition in fungi.
-
Heterokaryon formation and parasexual recombination between vegetatively incompatible lineages in a population of the chestnut blight fungus cryphonectria parasitica
Molecular Ecology, 2005Co-Authors: I C Mcguire, J E Davis, M L Double, W L Macdonald, Jason T Rauscher, S Mccawley, Michael G. MilgroomAbstract:Heterokaryosis was recently reported in the chestnut blight fungus, Cryphonectria parasitica , in which individuals contain nuclei that are isogenic except at the mating-type locus ( MAT ). MAT Heterokaryons were found in several natural populations, including a putatively clonal population in West Salem, Wisconsin, providing an opportunity to address the question of how Heterokaryons arise. We represented relationships among RFLP fingerprint haplotypes as networks in which loop formation is considered evidence of recombination. From 1990 to 1995, this population was clonal, as indicated by a simple haplotype network without loops, and the correlation of vegetative compatibility (vc) types and mating types with haplotype lineages. By 1999, we observed loops in the haplotype network involving isolates of two vc types (WS-2 and WS-3). Isolates with haplotypes in the loops were either MAT Heterokaryons, carried the opposite mating type from other isolates of the same vc type, and/or had two alleles at two or more codominant SCAR (sequence-characterized amplified region) loci. Segregation of markers and recombination were evident among single-spore isolates from one Heterokaryon; these single-spore isolates had novel fingerprint haplotypes, also within the loops. In contrast, vc type WS-1, which comprises 85% of the population, was represented by a simple network with no loops, indicating a clonal lineage varying only by mutation. Almost all isolates of WS-1 had the same mating type; the exceptions were five isolates that were MAT Heterokaryons. These results are consistent with the hypothesis that Heterokaryons formed between vegetatively incompatible individuals, and recombination occurred by a parasexual process.
-
mating type heterokaryosis and selfing in cryphonectria parasitica
Fungal Genetics and Biology, 2004Co-Authors: Cristina I Mcguire, Robert E Marra, Michael G. MilgroomAbstract:Abstract Selfing in the chestnut blight fungus, Cryphonectria parasitica , occurs by two different genetic mechanisms. Most self-fertile isolates of C. parasitica are heterokaryotic for mating type, and the progeny from selfing segregate for mating type. Further, we resolved mating-type ( MAT ) Heterokaryons into homokaryons of both mating types by isolating uninucleate asexual spores (conidia). However, because ascospore progeny, with rare exceptions, are not MAT Heterokaryons, C. parasitica must lack a regular mechanism to maintain heterokaryosis by selfing. We hypothesize that Heterokaryon formation may occur either because of recurrent biparental inbreeding, or by mating-type switching, possibly one involving some kind of parasexual process. The second mechanism found for selfing in C. parasitica occurred less frequently. Three single-conidial isolates ( MAT-1 and MAT-2 ) selfed and produced progeny that did not segregate for mating type. It is currently not known if meiosis occurs during ascospore formation by this mechanism. Index descriptors: Cryphonectria parasitica , Heterokaryosis, MAT , Mating type, Self-fertility, Self-incompatibility, Self-sterility
Neil J Scolding - One of the best experts on this subject based on the ideXlab platform.
-
purkinje cell fusion and binucleate Heterokaryon formation in multiple sclerosis cerebellum
Brain, 2012Co-Authors: Kevin C Kemp, Elizabeth Gray, Alastair Wilkins, Neil J ScoldingAbstract:A major conceptual consideration in both endogenous and therapeutic central nervous system repair is how damaged (or senescent) neurons, given their often enormously complex and extensive network of connections, can possibly be replaced. The recent observation of fusion of circulating bone marrow cells with, in particular, cerebellar Purkinje cells, as well as the subsequent formation of stable Heterokaryons, offers a tantalizing potential solution to this difficulty. Here, we have explored Purkinje cell fusion and Heterokaryon formation in the human brain and the influence of central nervous system inflammation. We analysed post-mortem cerebellum tissue from patients who had multiple sclerosis and from appropriate controls. Purkinje cells were analysed for Heterokaryon formation using immunohistochemistry techniques and chromosome composition using fluorescence in situ hybridization. For the first time in humans we show a disease-related increase in Purkinje cell fusion and Heterokaryon formation. We have shown that Heterokaryon formation takes place in control subjects, and that the frequency of this event is considerably increased in patients with multiple sclerosis, the prototypical inflammatory brain disease, with ∼0.4% of Purkinje cells being binucleate Heterokaryons. No mononucleate polyploid Purkinje cell Heterokaryons were found. The observation that Heterokaryon formation in the cerebellum occurs as part of the central nervous system inflammatory reaction suggests a potential mechanism of neural repair. It also suggests an exciting new avenue for therapeutic intervention, as enhancement or manipulation of fusion events may have a therapeutic role in cellular protection in multiple sclerosis. * Abbreviations : DAPI : 4′,6′-diamidino-2-phenylindole MBP : myelin basic protein
-
purkinje cell fusion and binucleate Heterokaryon formation in multiple sclerosis cerebellum
Brain, 2012Co-Authors: Kevin C Kemp, Elizabeth Gray, Alastair Wilkins, Neil J ScoldingAbstract:A major conceptual consideration in both endogenous and therapeutic central nervous system repair is how damaged (or senescent) neurons, given their often enormously complex and extensive network of connections, can possibly be replaced. The recent observation of fusion of circulating bone marrow cells with, in particular, cerebellar Purkinje cells, as well as the subsequent formation of stable Heterokaryons, offers a tantalizing potential solution to this difficulty. Here, we have explored Purkinje cell fusion and Heterokaryon formation in the human brain and the influence of central nervous system inflammation. We analysed post-mortem cerebellum tissue from patients who had multiple sclerosis and from appropriate controls. Purkinje cells were analysed for Heterokaryon formation using immunohistochemistry techniques and chromosome composition using fluorescence in situ hybridization. For the first time in humans we show a disease-related increase in Purkinje cell fusion and Heterokaryon formation. We have shown that Heterokaryon formation takes place in control subjects, and that the frequency of this event is considerably increased in patients with multiple sclerosis, the prototypical inflammatory brain disease, with ~0.4% of Purkinje cells being binucleate Heterokaryons. No mononucleate polyploid Purkinje cell Heterokaryons were found. The observation that Heterokaryon formation in the cerebellum occurs as part of the central nervous system inflammatory reaction suggests a potential mechanism of neural repair. It also suggests an exciting new avenue for therapeutic intervention, as enhancement or manipulation of fusion events may have a therapeutic role in cellular protection in multiple sclerosis.
Katsuhiko Kitamoto - One of the best experts on this subject based on the ideXlab platform.
-
bifc based visualisation system reveals cell fusion morphology and Heterokaryon incompatibility in the filamentous fungus aspergillus oryzae
Scientific Reports, 2018Co-Authors: Tomoya Okabe, Katsuhiko Kitamoto, Takuya Katayama, Taoning Mo, Noriko Mori, Ikuo Fujii, Kazuhiro Iwashita, Jun-ichi MaruyamaAbstract:Aspergillus oryzae is an industrially important filamentous fungus used for Japanese traditional food fermentation and heterologous protein production. Although cell fusion is important for Heterokaryon formation and sexual/parasexual reproduction required for cross breeding, knowledge on cell fusion and Heterokaryon incompatibility in A. oryzae is limited because of low cell fusion frequency. Therefore, we aimed to develop a BiFC system to specifically visualise fused cells and facilitate the analysis of cell fusion in A. oryzae. The cell fusion ability and morphology of 15 A. oryzae strains were investigated using heterodimerising proteins LZA and LZB fused with split green fluorescence protein. Morphological investigation of fused cells revealed that cell fusion occurred mainly as conidial anastomosis during the early growth stage. Self-fusion abilities were detected in most industrial A. oryzae strains, but only a few strain pairs showed non-self fusion. Protoplast fusion assay demonstrated that almost all the pairs capable of non-self fusion were capable of Heterokaryon formation and vice versa, thus providing the first evidence of Heterokaryon incompatibility in A. oryzae. The BiFC system developed in this study provides an effective method in studying morphology of fused cells and Heterokaryon incompatibility in the filamentous fungal species with low cell fusion efficiency.
-
Efficient formation of heterokaryotic sclerotia in the filamentous fungus Aspergillus oryzae.
Applied microbiology and biotechnology, 2013Co-Authors: Ryuta Wada, Feng Jie Jin, Yasuji Koyama, Jun-ichi Maruyama, Katsuhiko KitamotoAbstract:Heterokaryon formation by hyphal fusion occurs during a sexual/parasexual cycle in filamentous fungi, and therefore, it is biotechnologically important for crossbreeding. In the industrial filamentous fungus Aspergillus oryzae, a parasexual cycle has been reported, and it was recently suggested that sexual reproduction should be possible. However, as A. oryzae enters into hyphal fusion with a much lower frequency than Neurospora crassa, the process of Heterokaryon formation has not been extensively characterized in A. oryzae. Here, we developed a detection system for Heterokaryon formation by expressing red or green fluorescent proteins in nuclei and conferring uridine/uracil or adenine auxotrophy to MAT1-1 and MAT1-2 strains of A. oryzae. The Heterokaryon formation of A. oryzae was investigated in paired culture using the genetically modified strains. No sclerotial formation was observed in the hyphal contact regions of the two strains with the same auxotrophy, whereas numerous sclerotia were formed between the strains with different auxotrophies. In most of the formed sclerotia, the uridine/uracil and adenine auxotrophies were complemented, and both red and green fluorescence were detected, indicating that heterokaryotic fusants were formed by hyphal fusion before or during sclerotial formation. Moreover, overexpressing the sclR gene, which encodes a transcription factor promoting sclerotial formation, increased the number of heterokaryotic sclerotia formed between the two auxotrophic strains. Notably, these effects in sclerotial formation of heterokaryotic fusants were observed independently of the mating type pairing combinations. Taken together, these findings demonstrated that paring of different auxotrophs and sclR overexpression promote the formation of heterokaryotic sclerotia in A. oryzae.
Jun-ichi Maruyama - One of the best experts on this subject based on the ideXlab platform.
-
bifc based visualisation system reveals cell fusion morphology and Heterokaryon incompatibility in the filamentous fungus aspergillus oryzae
Scientific Reports, 2018Co-Authors: Tomoya Okabe, Katsuhiko Kitamoto, Takuya Katayama, Taoning Mo, Noriko Mori, Ikuo Fujii, Kazuhiro Iwashita, Jun-ichi MaruyamaAbstract:Aspergillus oryzae is an industrially important filamentous fungus used for Japanese traditional food fermentation and heterologous protein production. Although cell fusion is important for Heterokaryon formation and sexual/parasexual reproduction required for cross breeding, knowledge on cell fusion and Heterokaryon incompatibility in A. oryzae is limited because of low cell fusion frequency. Therefore, we aimed to develop a BiFC system to specifically visualise fused cells and facilitate the analysis of cell fusion in A. oryzae. The cell fusion ability and morphology of 15 A. oryzae strains were investigated using heterodimerising proteins LZA and LZB fused with split green fluorescence protein. Morphological investigation of fused cells revealed that cell fusion occurred mainly as conidial anastomosis during the early growth stage. Self-fusion abilities were detected in most industrial A. oryzae strains, but only a few strain pairs showed non-self fusion. Protoplast fusion assay demonstrated that almost all the pairs capable of non-self fusion were capable of Heterokaryon formation and vice versa, thus providing the first evidence of Heterokaryon incompatibility in A. oryzae. The BiFC system developed in this study provides an effective method in studying morphology of fused cells and Heterokaryon incompatibility in the filamentous fungal species with low cell fusion efficiency.
-
Efficient formation of heterokaryotic sclerotia in the filamentous fungus Aspergillus oryzae.
Applied microbiology and biotechnology, 2013Co-Authors: Ryuta Wada, Feng Jie Jin, Yasuji Koyama, Jun-ichi Maruyama, Katsuhiko KitamotoAbstract:Heterokaryon formation by hyphal fusion occurs during a sexual/parasexual cycle in filamentous fungi, and therefore, it is biotechnologically important for crossbreeding. In the industrial filamentous fungus Aspergillus oryzae, a parasexual cycle has been reported, and it was recently suggested that sexual reproduction should be possible. However, as A. oryzae enters into hyphal fusion with a much lower frequency than Neurospora crassa, the process of Heterokaryon formation has not been extensively characterized in A. oryzae. Here, we developed a detection system for Heterokaryon formation by expressing red or green fluorescent proteins in nuclei and conferring uridine/uracil or adenine auxotrophy to MAT1-1 and MAT1-2 strains of A. oryzae. The Heterokaryon formation of A. oryzae was investigated in paired culture using the genetically modified strains. No sclerotial formation was observed in the hyphal contact regions of the two strains with the same auxotrophy, whereas numerous sclerotia were formed between the strains with different auxotrophies. In most of the formed sclerotia, the uridine/uracil and adenine auxotrophies were complemented, and both red and green fluorescence were detected, indicating that heterokaryotic fusants were formed by hyphal fusion before or during sclerotial formation. Moreover, overexpressing the sclR gene, which encodes a transcription factor promoting sclerotial formation, increased the number of heterokaryotic sclerotia formed between the two auxotrophic strains. Notably, these effects in sclerotial formation of heterokaryotic fusants were observed independently of the mating type pairing combinations. Taken together, these findings demonstrated that paring of different auxotrophs and sclR overexpression promote the formation of heterokaryotic sclerotia in A. oryzae.
Kevin C Kemp - One of the best experts on this subject based on the ideXlab platform.
-
purkinje cell fusion and binucleate Heterokaryon formation in multiple sclerosis cerebellum
Brain, 2012Co-Authors: Kevin C Kemp, Elizabeth Gray, Alastair Wilkins, Neil J ScoldingAbstract:A major conceptual consideration in both endogenous and therapeutic central nervous system repair is how damaged (or senescent) neurons, given their often enormously complex and extensive network of connections, can possibly be replaced. The recent observation of fusion of circulating bone marrow cells with, in particular, cerebellar Purkinje cells, as well as the subsequent formation of stable Heterokaryons, offers a tantalizing potential solution to this difficulty. Here, we have explored Purkinje cell fusion and Heterokaryon formation in the human brain and the influence of central nervous system inflammation. We analysed post-mortem cerebellum tissue from patients who had multiple sclerosis and from appropriate controls. Purkinje cells were analysed for Heterokaryon formation using immunohistochemistry techniques and chromosome composition using fluorescence in situ hybridization. For the first time in humans we show a disease-related increase in Purkinje cell fusion and Heterokaryon formation. We have shown that Heterokaryon formation takes place in control subjects, and that the frequency of this event is considerably increased in patients with multiple sclerosis, the prototypical inflammatory brain disease, with ∼0.4% of Purkinje cells being binucleate Heterokaryons. No mononucleate polyploid Purkinje cell Heterokaryons were found. The observation that Heterokaryon formation in the cerebellum occurs as part of the central nervous system inflammatory reaction suggests a potential mechanism of neural repair. It also suggests an exciting new avenue for therapeutic intervention, as enhancement or manipulation of fusion events may have a therapeutic role in cellular protection in multiple sclerosis. * Abbreviations : DAPI : 4′,6′-diamidino-2-phenylindole MBP : myelin basic protein
-
purkinje cell fusion and binucleate Heterokaryon formation in multiple sclerosis cerebellum
Brain, 2012Co-Authors: Kevin C Kemp, Elizabeth Gray, Alastair Wilkins, Neil J ScoldingAbstract:A major conceptual consideration in both endogenous and therapeutic central nervous system repair is how damaged (or senescent) neurons, given their often enormously complex and extensive network of connections, can possibly be replaced. The recent observation of fusion of circulating bone marrow cells with, in particular, cerebellar Purkinje cells, as well as the subsequent formation of stable Heterokaryons, offers a tantalizing potential solution to this difficulty. Here, we have explored Purkinje cell fusion and Heterokaryon formation in the human brain and the influence of central nervous system inflammation. We analysed post-mortem cerebellum tissue from patients who had multiple sclerosis and from appropriate controls. Purkinje cells were analysed for Heterokaryon formation using immunohistochemistry techniques and chromosome composition using fluorescence in situ hybridization. For the first time in humans we show a disease-related increase in Purkinje cell fusion and Heterokaryon formation. We have shown that Heterokaryon formation takes place in control subjects, and that the frequency of this event is considerably increased in patients with multiple sclerosis, the prototypical inflammatory brain disease, with ~0.4% of Purkinje cells being binucleate Heterokaryons. No mononucleate polyploid Purkinje cell Heterokaryons were found. The observation that Heterokaryon formation in the cerebellum occurs as part of the central nervous system inflammatory reaction suggests a potential mechanism of neural repair. It also suggests an exciting new avenue for therapeutic intervention, as enhancement or manipulation of fusion events may have a therapeutic role in cellular protection in multiple sclerosis.