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Hiroyuki Sekimoto - One of the best experts on this subject based on the ideXlab platform.
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identification of a new mating group and reproductive isolation in the closterium peracerosum strigosum littorale complex
Journal of Plant Research, 2018Co-Authors: Yuki Tsuchikane, Hiroka Kobayashi, Machi Kato, Juri Watanabe, Hiroyuki SekimotoAbstract:Reproductive isolation is essential for the process of speciation. In order to understand speciation, it is necessary to compare one mating group with other phylogenetically related but reproductively isolated groups. The Closterium peracerosum-strigosum-littorale (C. psl.) complex is a unicellular isogamous zygnematophycean alga, which is believed to share a close phylogenetic relationship with the land plants. In this study, we identified a new mating group, named group G, of C. psl. complex and compared its physiological and biochemical characteristics with the mating group I-E, which was closely related to the mating group G. Zygospores are typically formed as a result of conjugation between mating-type plus (mt+) and mating-type minus (mt-) cells in the same mating group during sexual reproduction. Crossing experiments revealed mating groups G and I-E were reproductively isolated from each other, but the release of lone protoplasts from mt- cells of mating group G was induced in the presence of mt+ cells of mating group I-E. In fact, the sex pheromone, protoplast-release-inducing protein of mating group I-E induced the release of protoplasts from mt- cells of mating group G. When mt+ and mt- cells of both mating groups I-E and G were co-cultured (multiple-choice matings), the Zygospore formation of mating group G, but not that of mating group I-E, was inhibited. Based on these results, we propose a possible mechanism of reproductive isolation between the two mating groups and suggest the presence of sexual interference between mating group G and mating group I-E.
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Zygospore formation between homothallic and heterothallic strains of Closterium
Sexual Plant Reproduction, 2012Co-Authors: Yuki Tsuchikane, Hisayoshi Nozaki, Miki Tsuchiya, František Hindák, Hiroyuki SekimotoAbstract:Zygospore formation in different strains of the Closterium peracerosum - strigosum - littorale complex was examined in this unicellular isogamous charophycean alga to shed light on gametic mating strains in this taxon, which is believed to share a close phylogenetic relationship with land plants. Zygospores typically form as a result of conjugation between mating-type plus (mt^+) and mating-type minus (mt^−) cells during sexual reproduction in the heterothallic strain, similar to Chlamydomonas . However, within clonal cells, Zygospores are formed within homothallic strains, and the majority of these Zygospores originate as a result of conjugation of two recently divided sister gametangial cells derived from one vegetative cell. In this study, we analyzed conjugation of homothallic cells in the presence of phylogenetically closely related heterothallic cells to characterize the reproductive function of homothallic sister gametangial cells. The relative ratio of non-sister Zygospores to sister Zygospores increased in the presence of heterothallic mt^+ cells, compared with that in the homothallic strain alone and in a coculture with mt^− cells. Heterothallic cells were surface labeled with calcofluor white, permitting fusions with homothallic cells to be identified and confirming the formation of hybrid Zygospores between the homothallic cells and heterothallic mt^+ cells. These results show that at least some of the homothallic gametangial cells possess heterothallic mt^−-like characters. This finding supports speculation that division of one vegetative cell into two sister gametangial cells is a segregative process capable of producing complementary mating types.
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Conjugation processes of Penium margaritaceum (Zygnemophyceae, Charophyta)
Phycological Research, 2010Co-Authors: Yuki Tsuchikane, Miki Tsuchiya, Yume Kokubun, Jun Abe, Hiroyuki SekimotoAbstract:SUMMARY Detailed conjugation processes in Penium, a unicellular conjugating green alga, are described for the first time. A homothallic strain of Penium margaritaceum (Ehrenb.) Breb. (Designation, izu84-10) was isolated from a rice paddy field in Japan. The species was identified based on its morphology, and a molecular phylogeny confirmed that izu84-10 was closely related to another identified strain of this species. Using time-lapse photography, the conjugation processes in P. margaritaceum were observed and then categorized into the following six stages: (1) cell division, resulting in the formation of two sister gametangial cells from one vegetative cell; (2) formation of a sexual pair between the two sister gametangial cells (or between gametangial cells of another nearby individual); (3) formation of conjugation papillae by elongation of the cell wall; (4) release of a gamete from one of the pair members; (5) release of a gamete from the other pair member; and (6) formation of the Zygospore by gamete fusion. By alcian blue staining, possible involvement of mucilage to facilitate this cell adhesion and cell–cell communication was suggested.
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sexual processes and phylogenetic relationships of a homothallic strain in the closterium peracerosum strigosum littorale complex zygnematales charophyceae 1
Journal of Phycology, 2010Co-Authors: Yuki Tsuchikane, Hisayoshi Nozaki, Yume Kokubun, Machiko Sato, Tomoko Ootaki, Hiroyuki SekimotoAbstract:Members of the Closterium peracerosum–strigosum–littorale (C. psl.) complex are unicellular charophycean algae in which there are two modes of Zygospore formation, heterothallic and homothallic. A homothallic strain of Closterium (designation, kodama20) was isolated from a Japanese rice paddy field. Based on alignment of the 1506 group-I introns, which interrupt nuclear SSU rDNAs, homothallic kodama20 is most closely related to the heterothallic mating group II-B, which is partially sexually isolated from group II-A. Time-lapse photography of the conjugation process in kodama20 revealed that most of the observed Zygospores originated from one vegetative cell. The sexual conjugation process consisted of five stages: (1) cell division resulting in the formation of two sister gametangial cells from one vegetative cell, (2) formation of a sexual pair between the two sister gametangial cells (or between gametangial cells of another adjoined individual), (3) formation of conjugation papillae, (4) release of gametic protoplasts from both members of a pair, and (5) formation of the Zygospore by protoplast fusion. For conjugation to progress, the cell density and light condition in the culture was critical. We suggested the presence of a conjugation promotion factor.
Yuki Tsuchikane - One of the best experts on this subject based on the ideXlab platform.
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identification of a new mating group and reproductive isolation in the closterium peracerosum strigosum littorale complex
Journal of Plant Research, 2018Co-Authors: Yuki Tsuchikane, Hiroka Kobayashi, Machi Kato, Juri Watanabe, Hiroyuki SekimotoAbstract:Reproductive isolation is essential for the process of speciation. In order to understand speciation, it is necessary to compare one mating group with other phylogenetically related but reproductively isolated groups. The Closterium peracerosum-strigosum-littorale (C. psl.) complex is a unicellular isogamous zygnematophycean alga, which is believed to share a close phylogenetic relationship with the land plants. In this study, we identified a new mating group, named group G, of C. psl. complex and compared its physiological and biochemical characteristics with the mating group I-E, which was closely related to the mating group G. Zygospores are typically formed as a result of conjugation between mating-type plus (mt+) and mating-type minus (mt-) cells in the same mating group during sexual reproduction. Crossing experiments revealed mating groups G and I-E were reproductively isolated from each other, but the release of lone protoplasts from mt- cells of mating group G was induced in the presence of mt+ cells of mating group I-E. In fact, the sex pheromone, protoplast-release-inducing protein of mating group I-E induced the release of protoplasts from mt- cells of mating group G. When mt+ and mt- cells of both mating groups I-E and G were co-cultured (multiple-choice matings), the Zygospore formation of mating group G, but not that of mating group I-E, was inhibited. Based on these results, we propose a possible mechanism of reproductive isolation between the two mating groups and suggest the presence of sexual interference between mating group G and mating group I-E.
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Zygospore formation between homothallic and heterothallic strains of Closterium
Sexual Plant Reproduction, 2012Co-Authors: Yuki Tsuchikane, Hisayoshi Nozaki, Miki Tsuchiya, František Hindák, Hiroyuki SekimotoAbstract:Zygospore formation in different strains of the Closterium peracerosum - strigosum - littorale complex was examined in this unicellular isogamous charophycean alga to shed light on gametic mating strains in this taxon, which is believed to share a close phylogenetic relationship with land plants. Zygospores typically form as a result of conjugation between mating-type plus (mt^+) and mating-type minus (mt^−) cells during sexual reproduction in the heterothallic strain, similar to Chlamydomonas . However, within clonal cells, Zygospores are formed within homothallic strains, and the majority of these Zygospores originate as a result of conjugation of two recently divided sister gametangial cells derived from one vegetative cell. In this study, we analyzed conjugation of homothallic cells in the presence of phylogenetically closely related heterothallic cells to characterize the reproductive function of homothallic sister gametangial cells. The relative ratio of non-sister Zygospores to sister Zygospores increased in the presence of heterothallic mt^+ cells, compared with that in the homothallic strain alone and in a coculture with mt^− cells. Heterothallic cells were surface labeled with calcofluor white, permitting fusions with homothallic cells to be identified and confirming the formation of hybrid Zygospores between the homothallic cells and heterothallic mt^+ cells. These results show that at least some of the homothallic gametangial cells possess heterothallic mt^−-like characters. This finding supports speculation that division of one vegetative cell into two sister gametangial cells is a segregative process capable of producing complementary mating types.
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Conjugation processes of Penium margaritaceum (Zygnemophyceae, Charophyta)
Phycological Research, 2010Co-Authors: Yuki Tsuchikane, Miki Tsuchiya, Yume Kokubun, Jun Abe, Hiroyuki SekimotoAbstract:SUMMARY Detailed conjugation processes in Penium, a unicellular conjugating green alga, are described for the first time. A homothallic strain of Penium margaritaceum (Ehrenb.) Breb. (Designation, izu84-10) was isolated from a rice paddy field in Japan. The species was identified based on its morphology, and a molecular phylogeny confirmed that izu84-10 was closely related to another identified strain of this species. Using time-lapse photography, the conjugation processes in P. margaritaceum were observed and then categorized into the following six stages: (1) cell division, resulting in the formation of two sister gametangial cells from one vegetative cell; (2) formation of a sexual pair between the two sister gametangial cells (or between gametangial cells of another nearby individual); (3) formation of conjugation papillae by elongation of the cell wall; (4) release of a gamete from one of the pair members; (5) release of a gamete from the other pair member; and (6) formation of the Zygospore by gamete fusion. By alcian blue staining, possible involvement of mucilage to facilitate this cell adhesion and cell–cell communication was suggested.
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sexual processes and phylogenetic relationships of a homothallic strain in the closterium peracerosum strigosum littorale complex zygnematales charophyceae 1
Journal of Phycology, 2010Co-Authors: Yuki Tsuchikane, Hisayoshi Nozaki, Yume Kokubun, Machiko Sato, Tomoko Ootaki, Hiroyuki SekimotoAbstract:Members of the Closterium peracerosum–strigosum–littorale (C. psl.) complex are unicellular charophycean algae in which there are two modes of Zygospore formation, heterothallic and homothallic. A homothallic strain of Closterium (designation, kodama20) was isolated from a Japanese rice paddy field. Based on alignment of the 1506 group-I introns, which interrupt nuclear SSU rDNAs, homothallic kodama20 is most closely related to the heterothallic mating group II-B, which is partially sexually isolated from group II-A. Time-lapse photography of the conjugation process in kodama20 revealed that most of the observed Zygospores originated from one vegetative cell. The sexual conjugation process consisted of five stages: (1) cell division resulting in the formation of two sister gametangial cells from one vegetative cell, (2) formation of a sexual pair between the two sister gametangial cells (or between gametangial cells of another adjoined individual), (3) formation of conjugation papillae, (4) release of gametic protoplasts from both members of a pair, and (5) formation of the Zygospore by protoplast fusion. For conjugation to progress, the cell density and light condition in the culture was critical. We suggested the presence of a conjugation promotion factor.
P Kotzekidou - One of the best experts on this subject based on the ideXlab platform.
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production of beta carotene from synthetic medium by blakeslea trispora in fed batch culture
Food Biotechnology, 2004Co-Authors: Fani Mantzouridou, T Roukas, P KotzekidouAbstract:Abstract The production of β-carotene from a synthetic medium by Blakeslea trispora in fed-batch culture was investigated. A maximum β-carotene concentration of 85.0 mg L−1 with productivity of 0.16 mg L−1 h−1 and specific β-carotene production rate of 0.01 mg g−1 h−1 was obtained by feeding the cells constantly with olive oil, cottonseed oil, soybean oil, antioxidant, and low concentration of growth factors at feeding rate of 4.2 mL h−1 from the beginning of the fermentation. In this case, the fed-batch culture supported high values of biomass dry weight (11.0 g L−1) and sugar utilization (0.976 g g−1). The morphology of the fungus was studied during growth in fed-batch fermentation system using an image analysis system. Zygospores are the morphological forms, which are responsible for the production of the pigment. The highest percentage of Zygospores (11.44%) was correlated with the highest percentage of intracellular β-carotene (0.72%) in the total biomass dry weight. Moreover, high percentages of vac...
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production of beta carotene from beet molasses by blakeslea trispora in stirred tank and bubble column reactors development of a mathematical modeling
Applied Biochemistry and Biotechnology, 2004Co-Authors: Yekta Goksungur, Fani Mantzouridou, T Roukas, P KotzekidouAbstract:The effect of aeration rate and agitation speed on β-carotene production from molasses by Blakeslea trispora in a stirred-tank fermentor and optimization of the production of the pigment in a bubble column reactor were investigated. In addition, a central composite design was employed to determine the maximum β-carotene concentration at optimum values for the process variables (aeration rate, sugar concentration, linoleic acid, kerosene). By image analysis of the morphology of the fungus, a quantitative characterization of the hyphae and Zygospores formed was obtained. The hyphae were differentiated to intacthyphae, vacuolated hyphae, evacuated cells and degenerated hyphae. An increased proportion of Zygospores was correlated to high β-carotene production. In the stirred-tank fermentor, the highest concentration of the carotenoid pigment (92.0 mg/L) was obtained at an aeration rate of 1.5 vvm and agitation speed of 60 rpm. In the bubble column reactor, the aeration rate and concentration of sugars, linoleic acid, kerosene, and antioxidant significantly affected the production of β-carotene. In all cases, the fit of the model was found to be good. Aeration rate, sugar concentration, linoleic acid, and kerosene had a strong positive linear effect on β-carotene concentration. Moreover, the concentration of the pigment was significantly influenced by the negative quadratic effects of the given variables and by their positive or negative interactions. Maximum β-carotene concentration (360.2 mg/L) was obtained in culture grown in molasses solution containing 5% (w/v) sugar supplemented with linoleic acid (37.59 g/L), kerosene (39.11 g/L), and antioxidant (1.0 g/L).
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effect of the aeration rate and agitation speed on β carotene production and morphology of blakeslea trispora in a stirred tank reactor mathematical modeling
Biochemical Engineering Journal, 2002Co-Authors: Fani Mantzouridou, T Roukas, P KotzekidouAbstract:Abstract The effect of aeration rate and agitation speed on β-carotene production and morphology of Blakeslea trispora in a stirred tank reactor was investigated. B. trispora formed hyphae, zygophores and Zygospores during the fermentation. The Zygospores were the morphological form responsible for β-carotene production. Both aeration and agitation significantly affected β-carotene concentration, productivity, biomass and the volumetric mass transfer coefficient ( K L a ). The highest β-carotene concentration (1.5 kg m −3 ) and the highest productivity (0.08 kg m −3 per day) were obtained at low impeller speed (150 rpm) and high aeration rate (1.5 vvm). Also, maximum productivity (0.08 kg m −3 per day) and biomass dry weight (26.4 kg m −3 ) were achieved at high agitation speed (500 rpm) and moderate aeration rate (1.0 vvm). Conversely, the highest value of K L a (0.33 s −1 ) was observed at high agitation speed (500 rpm) and high aeration rate (1.5 vvm). The experiments were arranged according to a central composite statistical design. Response surface methodology was used to describe the effect of impeller speed and aeration rate on the most important fermentation parameters. In all cases, the fit of the model was found to be good. All fermentation parameters (except biomass concentration) were strongly affected by the interactions among the operation variables. β-Carotene concentration and productivity were significantly influenced by the aeration, agitation, and by the positive or negative quadratic effect of the aeration rate. Biomass concentration was principally related to the aeration rate, agitation speed, and the positive or negative quadratic effect of the impeller speed and aeration rate, respectively. Finally, the volumetric mass transfer coefficient was characterized by the significant effect of the agitation speed, while the aeration rate had a small effect on K L a .
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optimization of β carotene production from synthetic medium by blakeslea trispora in a stirred tank reactor and relationship between morphological changes and pigment formation
Food Biotechnology, 2002Co-Authors: Fani Mantzouridou, T Roukas, P KotzekidouAbstract:ABSTRACT The effect of linoleic acid, kerosene, antioxidant and a mixture of natural oils (olive oil, soybean oil, and cottonseed oil) on the production of β-carotene by Blakeslea trispora and the morphological characteristics of the fungus in a stirred tank reactor were investigated. The mixture of linoleic acid and antioxidant improved slightly the production of β-carotene, while the addition of linoleic acid, kerosene or antioxidant alone to the medium had an inhibiting effect on β-carotene production. The addition to the medium of a mixture of natural oils and antioxidant increased significantly the concentration of the pigment. B. trispora formed hyphae, zygophores and Zygospores during β-carotene production. Morphology of the fungus was studied during growth in submerged culture in a stirred tank reactor under different compositions of the production medium using an image analysis system. Zygospores are the morphological forms, which are responsible for pigment production. Maximum β-carotene concent...
Lena Norbäck Ivarsson - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE Zygomycetes in Vesicular Basanites from Vesteris Seamount, Greenland Basin – A New Type of Cryptoendolithic Fungi
2016Co-Authors: Magnus Ivarsson, Jörn Peckmann, Anders Tehler, Curt Broman, Wolfgang Bach, Katharina Behrens, Joachim Reitner, Michael E. Böttcher, Lena Norbäck IvarssonAbstract:Fungi have been recognized as a frequent colonizer of subseafloor basalt but a substantial understanding of their abundance, diversity and ecological role in this environment is still lacking. Here we report fossilized cryptoendolithic fungal communities represented by mainly Zygomycetes and minor Ascomycetes in vesicles of dredged volcanic rocks (basa-nites) from the Vesteris Seamount in the Greenland Basin. Zygomycetes had not been reported from subseafloor basalt previously. Different stages in Zygospore formation are documented in the studied samples, representing a reproduction cycle. Spore structures of both Zygomycetes and Ascomycetes are mineralized by romanechite-like Mn oxide phases, indicating an involvement in Mn(II) oxidation to form Mn(III,VI) oxides. Zygospores still exhibit a core of carbonaceous matter due to their resistance to degradation. The fungi are closely associated with fossiliferous marine sediments that have been introduced into the vesicles. At the contact to sediment infillings, fungi produced haustoria that penetrated and scavenged on the remains of fragmented marine organisms. It is most likely that such marine debris is the main carbon source for fungi in shallow volcanic rocks, which favore
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Zygomycetes in Vesicular Basanites from Vesteris Seamount, Greenland Basin--A New Type of Cryptoendolithic Fungi.
PloS one, 2015Co-Authors: Magnus Ivarsson, Jörn Peckmann, Anders Tehler, Curt Broman, Wolfgang Bach, Katharina Behrens, Joachim Reitner, Michael E. Böttcher, Lena Norbäck IvarssonAbstract:Fungi have been recognized as a frequent colonizer of subseafloor basalt but a substantial understanding of their abundance, diversity and ecological role in this environment is still lacking. Here we report fossilized cryptoendolithic fungal communities represented by mainly Zygomycetes and minor Ascomycetes in vesicles of dredged volcanic rocks (basanites) from the Vesteris Seamount in the Greenland Basin. Zygomycetes had not been reported from subseafloor basalt previously. Different stages in Zygospore formation are documented in the studied samples, representing a reproduction cycle. Spore structures of both Zygomycetes and Ascomycetes are mineralized by romanechite-like Mn oxide phases, indicating an involvement in Mn(II) oxidation to form Mn(III,VI) oxides. Zygospores still exhibit a core of carbonaceous matter due to their resistance to degradation. The fungi are closely associated with fossiliferous marine sediments that have been introduced into the vesicles. At the contact to sediment infillings, fungi produced haustoria that penetrated and scavenged on the remains of fragmented marine organisms. It is most likely that such marine debris is the main carbon source for fungi in shallow volcanic rocks, which favored the establishment of vital colonies.
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Microphotographs of Zygospores and a Zygomycetes reproduction cycle.
2015Co-Authors: Magnus Ivarsson, Jörn Peckmann, Anders Tehler, Curt Broman, Wolfgang Bach, Katharina Behrens, Joachim Reitner, Michael E. Böttcher, Lena Norbäck IvarssonAbstract:(A) Two zygophores approaching each other. (B,C) Fusion of two zygophores to form progametangia. Note how the zygophores are tightly appressed parallel to each other while fusing to form the progametangia. (D,E) Gametangia are separated by septa and a structure develops in between them that could represent early stage of zygote formation with fusion wall beginning to degrade. (F) Image showing a swollen, dark structure with a warty appearance that represents the last stages of the Zygospore formation, the zygote. For legends see caption of Fig 2.
Enrique Cerdaolmedo - One of the best experts on this subject based on the ideXlab platform.
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modification of sexual development and carotene production by acetate and other small carboxylic acids in blakeslea trispora and phycomyces blakesleeanus
Applied and Environmental Microbiology, 2006Co-Authors: Vera Kuzina, Enrique CerdaolmedoAbstract:In Phycomyces blakesleeanus and Blakeslea trispora (order Mucorales, class Zygomycetes), sexual interaction on solid substrates leads to Zygospore development and to increased carotene production (sexual carotenogenesis). Addition of small quantities of acetate, propionate, lactate, or leucine to mated cultures on minimal medium stimulated Zygospore production and inhibited sexual carotenogenesis in both Phycomyces and Blakeslea. In Blakeslea, the threshold acetate concentration was 7 mmol/liter for zygosporogenesis. The effects on Phycomyces were similar, but the concentrations of acetate had to be multiplied by ca. 3 to obtain the same results. Inhibition of sexual carotenogenesis by acetate occurred normally in Phycomyces mutants that cannot use acetate as a carbon source and in mutants whose dormant spores cannot be activated by acetate. Small carboxylic acids may be signals that, independent of their ability to trigger spore germination in Phycomyces, modify metabolism and development during the sexual cycle of Phycomyces and Blakeslea, uncoupling two processes that were thought to be linked and mediated by a common mechanism.
