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Yasuo Ohnishi - One of the best experts on this subject based on the ideXlab platform.
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regulation of Sporangium formation spore dormancy and Sporangium dehiscence by a hybrid sensor histidine kinase in actinoplanes missouriensis relationship with the global transcriptional regulator tcra
2020Co-Authors: Yuichiro Hashiguchi, Takeaki Tezuka, Yoshihiro Mouri, Kenji Konishi, Azusa Fujita, Aiko Hirata, Yasuo OhnishiAbstract:ABSTRACT The rare actinomycete Actinoplanes missouriensis forms terminal sporangia containing a few hundred flagellated spores. In response to water, the sporangia open and release the spores into external environments. The orphan response regulator TcrA functions as a global transcriptional activator during Sporangium formation and dehiscence. Here, we report the characterization of an orphan hybrid histidine kinase, HhkA. Sporangia of an hhkA deletion mutant contained many distorted or ectopically germinated spores and scarcely opened to release the spores under Sporangium dehiscence-inducing conditions. These phenotypic changes are quite similar to those observed in a tcrA deletion mutant. Comparative RNA sequencing analysis showed that genes controlled by HhkA mostly overlap TcrA-regulated genes. The direct interaction between HhkA and TcrA was suggested by a bacterial two-hybrid assay, but this was not conclusive. The phosphorylation of TcrA using acetyl phosphate as a phosphate donor markedly enhanced its affinity for the TcrA box sequences in the electrophoretic mobility shift assay. Taking these observations together with other results, we proposed that HhkA and TcrA compose a cognate two-component regulatory system, which controls the transcription of the genes involved in many aspects of morphological development, including Sporangium formation, spore dormancy, and Sporangium dehiscence in A. missouriensis. IMPORTANCEActinoplanes missouriensis goes through complex morphological differentiation, including formation of flagellated spore-containing sporangia, Sporangium dehiscence, swimming of zoospores, and germination of zoospores to filamentous growth. Although the orphan response regulator TcrA globally activates many genes required for Sporangium formation, spore dormancy, and Sporangium dehiscence, its partner histidine kinase remained unknown. Here, we analyzed the function of an orphan hybrid histidine kinase, HhkA, and proposed that HhkA constitutes a cognate two-component regulatory system with TcrA. That HhkA and TcrA homologues are highly conserved among the genus Actinoplanes and several closely related rare actinomycetes indicates that this possible two-component regulatory system is employed for complex morphological development in Sporangium- and/or zoospore-forming rare actinomycetes.
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involvement of three flia family sigma factors in the Sporangium formation spore dormancy and Sporangium dehiscence in actinoplanes missouriensis
2020Co-Authors: Yuichiro Hashiguchi, Takeaki Tezuka, Yasuo OhnishiAbstract:: The rare actinomycete Actinoplanes missouriensis forms sporangia, which open up and release zoospores in response to water. Here, we report a genetic and functional analysis of four FliA-family sigma factors, FliA1, FliA2, FliA3 and FliA4. Transcription of fliA1, fliA2 and fliA3 was directly activated by the global transcriptional activator TcrA during Sporangium formation and dehiscence, while fliA4 was almost always transcribed at low levels. Gene disruption analysis showed that (a) deletion of fliA2 reduced the zoospore swimming speed by half, (b) the fliA1-fliA2 double-deletion mutant formed abnormal sporangia in which mutant spores ectopically germinated and (c) deletion of fliA3 induced no phenotypic changes in the wild-type and mutant strains of fliA1 and/or fliA2. Comparative RNA-Seq analyses among the wild-type and gene deletion mutant strains showed probable targets of each FliA-family sigma factor, indicating that FliA1- and FliA2-dependent promoters are quite similar to each other, while the FliA3-dependent promoter is somewhat different. Gene complementation experiments also indicated that the FliA1 regulon overlaps with the FliA2 regulon. These results demonstrate that A. missouriensis has developed a complex transcriptional regulatory network involving multiple FliA-family sigma factors for the accomplishment of its characteristic reproduction process, including Sporangium formation, spore dormancy and Sporangium dehiscence.
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regulation of Sporangium formation by the orphan response regulator tcra in the rare actinomycete actinoplanes missouriensis
2018Co-Authors: Yoshihiro Mouri, Takeaki Tezuka, Kenji Konishi, Aiko Hirata, Moonsun Jang, Yasuo OhnishiAbstract:The rare actinomycete Actinoplanes missouriensis forms terminal sporangia containing a few hundred flagellated spores, which can swim in aquatic environments after release from Sporangium. However, gene regulation for its characteristic morphological development is largely unknown. Here, we report the functional analysis of an orphan response regulator, TcrA, which is encoded next to the chemotaxis-flagellar gene cluster. The tcrA null (ΔtcrA) mutant formed Sporangium, in which sporulation proceeded. However, many distorted spores were produced and some spores ectopically germinated in the mutant sporangia. In addition, spores were hardly released from the mutant sporangia. A comparative RNA-Seq analysis between the wild-type and ΔtcrA strains showed that TcrA upregulated the transcription of more than 263 genes, which were integrated into 185 transcriptional units. In silico searches identified a 21-bp direct repeat sequence, 5'-nnGCA(A/C)CCG-n4 -GCA(A/C)CCGn-3', as the TcrA box, which was confirmed by electrophoretic mobility shift assays. Finally, we identified 34 transcriptional units as the TcrA regulon. TcrA seems to regulate a few hundred genes through the transcriptional activation of three FliA-family sigma factor genes besides its own regulon. We concluded that TcrA is a global transcriptional activator that controls many aspects of Sporangium formation, including flagellar biogenesis, spore dormancy and Sporangium dehiscence.
Ming Thau Sheu - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE Mycelial Mattress from a Sporangia Formation-Delayed Mutant of Rhizopus stolonifer as Wound Healing-Enhancing
2016Co-Authors: Mei Yin Chien, Ling Chun Chen, Ying Chen Chen, Ming Thau Sheu, Ya Chi TsaiAbstract:Amycelial mattress of Rhizopus stolonifer obtained from a liquid static culture was utilized for wound dressing and biomedical use. Following screening of mutants induced by UV radiation, F6, exhibiting delayed Sporangium formation was selected because its sporan-gium maturation exhibited a 5-day delay without significant loss of mycelial weight com-pared to the wild type. The Sporangium-free mycelial mattress from the sporangiospore culture of F6 was treated with 1N sodium hydroxide NaOH at 85°C for 2 h to produce a sponge-like membrane named Rhizochitin. The trifluoroacetic acid hydrolysate of Rhizochi-tin contained 36 % N-acetylglucosamine and 53 % hexose respectively detected by the Elson-Morgen and phenol-sulfuric acid methods. Results indicated the wound area in rats covered with Rhizochitin was 40 % less than that of the uncovered group. Rhizochitin decreased the expression of PDGF in the proliferation stage, increased the expression of TGF-β in the inflammation and proliferation stages, and increased the expression of VEGF in the inflammation and proliferation stages. Rhizochitin inhibited secretion of matrix metal-loproteinase-9 on days 1, 7, 9, and 12 and matrix metalloproteinase-2 on days 3, 7, 9, and 12. It was concluded that Rhizochitin has beneficial properties of biocompatible, biodegrad-able, and wound healing
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mycelial mattress from a sporangia formation delayed mutant of rhizopus stolonifer as wound healing enhancing biomaterial
2015Co-Authors: Mei Yin Chien, Ling Chun Chen, Ying Chen Chen, Ming Thau Sheu, Ya Chi Tsai, Hsiu O Ho, Chinghua SuAbstract:A mycelial mattress of Rhizopus stolonifer obtained from a liquid static culture was utilized for wound dressing and biomedical use. Following screening of mutants induced by UV radiation, F6, exhibiting delayed Sporangium formation was selected because its Sporangium maturation exhibited a 5-day delay without significant loss of mycelial weight compared to the wild type. The Sporangium-free mycelial mattress from the sporangiospore culture of F6 was treated with 1N sodium hydroxide NaOH at 85°C for 2 h to produce a sponge-like membrane named Rhizochitin. The trifluoroacetic acid hydrolysate of Rhizochitin contained 36% N-acetylglucosamine and 53% hexose respectively detected by the Elson-Morgen and phenol-sulfuric acid methods. Results indicated the wound area in rats covered with Rhizochitin was 40% less than that of the uncovered group. Rhizochitin decreased the expression of PDGF in the proliferation stage, increased the expression of TGF-β in the inflammation and proliferation stages, and increased the expression of VEGF in the inflammation and proliferation stages. Rhizochitin inhibited secretion of matrix metalloproteinase-9 on days 1, 7, 9, and 12 and matrix metalloproteinase-2 on days 3, 7, 9, and 12. It was concluded that Rhizochitin has beneficial properties of biocompatible, biodegradable, and wound healing.
Chinghua Su - One of the best experts on this subject based on the ideXlab platform.
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mycelial mattress from a sporangia formation delayed mutant of rhizopus stolonifer as wound healing enhancing biomaterial
2015Co-Authors: Mei Yin Chien, Ling Chun Chen, Ying Chen Chen, Ming Thau Sheu, Ya Chi Tsai, Hsiu O Ho, Chinghua SuAbstract:A mycelial mattress of Rhizopus stolonifer obtained from a liquid static culture was utilized for wound dressing and biomedical use. Following screening of mutants induced by UV radiation, F6, exhibiting delayed Sporangium formation was selected because its Sporangium maturation exhibited a 5-day delay without significant loss of mycelial weight compared to the wild type. The Sporangium-free mycelial mattress from the sporangiospore culture of F6 was treated with 1N sodium hydroxide NaOH at 85°C for 2 h to produce a sponge-like membrane named Rhizochitin. The trifluoroacetic acid hydrolysate of Rhizochitin contained 36% N-acetylglucosamine and 53% hexose respectively detected by the Elson-Morgen and phenol-sulfuric acid methods. Results indicated the wound area in rats covered with Rhizochitin was 40% less than that of the uncovered group. Rhizochitin decreased the expression of PDGF in the proliferation stage, increased the expression of TGF-β in the inflammation and proliferation stages, and increased the expression of VEGF in the inflammation and proliferation stages. Rhizochitin inhibited secretion of matrix metalloproteinase-9 on days 1, 7, 9, and 12 and matrix metalloproteinase-2 on days 3, 7, 9, and 12. It was concluded that Rhizochitin has beneficial properties of biocompatible, biodegradable, and wound healing.
G H M Jaworski - One of the best experts on this subject based on the ideXlab platform.
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Sporangium differentiation and zoospore fine structure of the chytrid rhizophydium planktonicum a fungal parasite of asterionella formosa
1993Co-Authors: Gordon W Beakes, Hilda M Canter, G H M JaworskiAbstract:Sporangium development in the fungal parasite Rhizophydium planktonicum has been followed by electron microscopy using dual clonal cultures. Following zoospore encystment on Asterionella , a fine germ-hypha is produced which penetrates the host via the girdle lamella. The Sporangium develops directly from the cyst and becomes delimited from the germ-hypha by the formation of a septum. The pre-cleavage Sporangium develops a thickened apical wall (a papilla) which ultimately gives rise to a vesicle which surrounds the emerging zoospores. This pattern of vesicle formation differs significantly from that so far described in other chytrid species. The nucleus undergoes mitosis before the Sporangium cytoplasm becomes cleaved into uninucleate zoospore initials by the formation of an internal furrow system. Specialized zoospore organelles such as the lipid-associated rumposome and paracrystalline bodies are not formed until zoospore initial delimitation is almost completed. The fine-structure of the mature zoospore was used to evaluate the current taxonomic status of this species, particularly in relation to two other chytrid parasites of this host ( Zygorhizidium affluens and Z. planktonicum ). In zoospores of R. planktonicum , the ribosome aggregates typical of this genus are not delimited by endoplasmic reticulum. Zoospores of this species also contain paracrystalline bodies and dense occlusions in the region where the flagellum enters the spore body. These features have previously only been noted in other genera and therefore it is concluded that this species is probably not closely related to other Rhizophydium spp.
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ultrastructural study of operculation discharge apparatus and zoospore discharge in zoosporangia of zygorhizidium affluens and z planktonicum chytrid parasites of the diatom asterionella formosa
1992Co-Authors: Gordon W Beakes, Hilda M Canter, G H M JaworskiAbstract:The development of opercula in sporangia of two monocentric chytrids, Zygorhizidium affluens and Z. planktonicum , is one of the earliest specialized events during zoosporogenesis. The mode of operculum differentiation is significantly different in the two species. In Z. affluens the clearly demarked lid-like operculum differentiates by the annular rupture of the Sporangium wall, which remains sealed by an underlying pad of amorphous material. In Z. planktonicum , the operculum shows no obvious structural differentiation from the rest of the Sporangium wall and develops at the top of an apical papilla. At the time of zoospore discharge in Z. affluens the pad of sealing wall material presumably erodes allowing the operculum lid to spring open. In Z. planktonicum , the operculum wall disintegrates around its rim and eventually tears open to release the zoospores. Fully differentiated zoospores of Z. planktonicum are surrounded by a loose fibrillar matrix, which probably binds the liberated spores together for a minute or two before dispersing and allowing the spores to swim away.
Gordon W Beakes - One of the best experts on this subject based on the ideXlab platform.
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the development ultrastructural cytology and molecular phylogeny of the basal oomycete eurychasma dicksonii infecting the filamentous phaeophyte algae ectocarpus siliculosus and pylaiella littoralis
2008Co-Authors: Satoshi Sekimoto, Claire M M Gachon, Frithjof C Kupper, Gordon W Beakes, Dieter G Muller, Daiske HondaAbstract:The morphological development, ultrastructural cytology, and molecular phylogeny of Eurychasma dicksonii, a holocarpic oomycete endoparasite of phaeophyte algae, were investigated in laboratory cultures. Infection of the host algae by E. dicksonii is initiated by an adhesorium-like infection apparatus. First non-walled, the parasite cell developed a cell wall and numerous large vacuoles once it had almost completely filled the infected host cell (foamy stage). Large-scale cytoplasmic changes led to the differentiation of a Sporangium with peripheral primary cysts. Secondary zoospores appeared to be liberated from the primary cysts in the internal space left after the peripheral spores differentiated. These zoospores contained two phases of peripheral vesicles, most likely homologous to the dorsal encystment vesicles and K-bodies observed in other oomycetes. Following zoospore liberation the walls of the empty cyst were left behind, forming the so-called net Sporangium, a distinctive morphological feature of this genus. The morphological and ultrastructural features of Eurychasma were discussed in relation to similarities with other oomycetes. Both SSU rRNA and COII trees pointed to a basal position of Eurychasma among the Oomycetes. The cox2 sequences also revealed that the UGA codon encoded tryptophan, constituting the first report of stop codon reassignment in an oomycete mitochondrion.
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Sporangium differentiation and zoospore fine structure of the chytrid rhizophydium planktonicum a fungal parasite of asterionella formosa
1993Co-Authors: Gordon W Beakes, Hilda M Canter, G H M JaworskiAbstract:Sporangium development in the fungal parasite Rhizophydium planktonicum has been followed by electron microscopy using dual clonal cultures. Following zoospore encystment on Asterionella , a fine germ-hypha is produced which penetrates the host via the girdle lamella. The Sporangium develops directly from the cyst and becomes delimited from the germ-hypha by the formation of a septum. The pre-cleavage Sporangium develops a thickened apical wall (a papilla) which ultimately gives rise to a vesicle which surrounds the emerging zoospores. This pattern of vesicle formation differs significantly from that so far described in other chytrid species. The nucleus undergoes mitosis before the Sporangium cytoplasm becomes cleaved into uninucleate zoospore initials by the formation of an internal furrow system. Specialized zoospore organelles such as the lipid-associated rumposome and paracrystalline bodies are not formed until zoospore initial delimitation is almost completed. The fine-structure of the mature zoospore was used to evaluate the current taxonomic status of this species, particularly in relation to two other chytrid parasites of this host ( Zygorhizidium affluens and Z. planktonicum ). In zoospores of R. planktonicum , the ribosome aggregates typical of this genus are not delimited by endoplasmic reticulum. Zoospores of this species also contain paracrystalline bodies and dense occlusions in the region where the flagellum enters the spore body. These features have previously only been noted in other genera and therefore it is concluded that this species is probably not closely related to other Rhizophydium spp.
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ultrastructural study of operculation discharge apparatus and zoospore discharge in zoosporangia of zygorhizidium affluens and z planktonicum chytrid parasites of the diatom asterionella formosa
1992Co-Authors: Gordon W Beakes, Hilda M Canter, G H M JaworskiAbstract:The development of opercula in sporangia of two monocentric chytrids, Zygorhizidium affluens and Z. planktonicum , is one of the earliest specialized events during zoosporogenesis. The mode of operculum differentiation is significantly different in the two species. In Z. affluens the clearly demarked lid-like operculum differentiates by the annular rupture of the Sporangium wall, which remains sealed by an underlying pad of amorphous material. In Z. planktonicum , the operculum shows no obvious structural differentiation from the rest of the Sporangium wall and develops at the top of an apical papilla. At the time of zoospore discharge in Z. affluens the pad of sealing wall material presumably erodes allowing the operculum lid to spring open. In Z. planktonicum , the operculum wall disintegrates around its rim and eventually tears open to release the zoospores. Fully differentiated zoospores of Z. planktonicum are surrounded by a loose fibrillar matrix, which probably binds the liberated spores together for a minute or two before dispersing and allowing the spores to swim away.
