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Hiroyuki Sekimoto - One of the best experts on this subject based on the ideXlab platform.
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The genus Closterium, a new model organism to study sexual reproduction in streptophytes
The New phytologist, 2018Co-Authors: Yuki Tsuchikane, Hiroyuki SekimotoAbstract:Contents Summary 99 I. Introduction 99 II. Life cycle of Closterium 100 III. Sexual reproductive processes in the heterothallic Closterium peracerosum-strigosum-littorale complex 101 IV. Homothallism in the C. psl. complex 102 V. Sexual reproduction and inheritance of mating types in Closterium ehrenbergii 102 VI. mt-determining gene of the C. psl. complex 103 VII. Future perspectives 103 Acknowledgements 103 References 103 SUMMARY: Closterium occupies a key phylogenetic position as an ancestor of land plants and is the best-characterized Charophycean alga in terms of the process of sexual reproduction. Zygospores form as a result of sexual reproduction between genetically determined mating type plus (mt+ ) and mating type minus (mt- ) cells in heterothallic strains, or between clonal cells in homothallic strains. Here we review knowledge on the intercellular communication and mating type determination for successful sexual reproduction in Closterium. Using genomic information and transgenic techniques, the genus could be a model organism to study the mechanisms and evolution of sexual reproduction in streptophytes.
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Characterization and molecular cloning of conjugation-regulating sex pheromones in homothallic Closterium.
Plant & cell physiology, 2010Co-Authors: Yuki Tsuchikane, Yume Kokubun, Hiroyuki SekimotoAbstract:Conjugation-regulating pheromones were analyzed in homothallic Closterium for the fi rst time. Members of the Closterium peracerosum–strigosum–littorale complex are unicellular charophycean algae in which there are two modes of zygospore formation: heterothallism and homothallism. A homothallic strain of Closterium (designation, kodama20) forms selfi ng zygospores via the conjugation of two sister gametangial cells derived from one vegetative cell. Conjugation-promoting and -suppressing activities, against cells at very low (1 × 10 2 cells ml − 1 ) and normal (1 × 10 4 cells ml − 1 ) cell density, respectively, were detected in the medium in which cells of a normal density had been cultured. Pheromone activities decreased to 20 % after incubation at 60 ° C for 10 min. The release and action of the pheromones was dependent on light. The culture medium was subjected to gel fi ltration, and both active substances had an apparent molecular mass of 17 kDa; this was similar to that previously reported for the heterothallic sex-specifi c pheromone protoplast-release-inducing protein (PR-IP) Inducer. cDNAs encoding the orthologs of PR-IP Inducer were isolated from the homothallic strain. Recombinant PR-IP Inducers produced by yeast cells showed conjugationpromoting activity. These results indicate that conjugation of the homothallic strain is regulated by an ortholog of a heterothallic sex-specifi c pheromone.
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CLONING AND CHARACTERIZATION OF A cDNA ENCODING A SEXUAL CELL DIVISION-INDUCING PHEROMONE FROM A UNICELLULAR GREEN ALGA Closterium EHRENBERGII (CHLOROPHYTA)
Journal of Phycology, 2003Co-Authors: Ryo-hei Fukumoto, Tadashi Fujii, Hiroyuki SekimotoAbstract:A full-length cDNA encoding a sexual cell division-inducing pheromone (SCD-IP) was isolated from a heterothallic green alga, Closterium ehrenbergii Menegh. ex Ralfs, using the rapid amplification of cDNA ends-PCR method. The cDNA was 907 bp in length and coded for a protein of 209 amino acids with a deduced molecular mass of M r 23,186. The predicted protein had a possible glycosylation site and a hydrophobic signal peptide for extracellular secretion. Transcripts of the SCD-IP gene were detected only in mating type minus (mt - ) cells and remarkably increased when mt - cells were cocultured with mating type plus (mt + ) cells. By contrast, the gene for SCD-IP was detected in both mating type cells as multicopy genes by Southern blot analysis. Continuous dark conditions and supplementation of a nitrogen source to the culture medium suppressed SCD-IP expression. The deduced amino acid sequences encoded by genes for SCD-IP and protoplast-release-inducing protein (PR-IP) Inducer, a sex pheromone isolated from another Closterium species, appeared to share significant homology, suggesting that these sex pheromones were diversified from a single ancestral Closterium pheromone.
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Purification and characterization of a pheromone that induces sexual cell division in the unicellular green alga Closterium ehrenbergii
Plant Physiology and Biochemistry, 2002Co-Authors: Ryo-hei Fukumoto, Naoshi Dohmae, Kouji Takio, Shinobu Satoh, Tadashi Fujii, Hiroyuki SekimotoAbstract:Abstract Closterium ehrenbergii is a unicellular charophycean alga consisting of two sexes: mating type plus (mt + ) and minus (mt – ). The sexual reproductive process consists of five steps: formation of sexual pairs, cell division of each member of a pair, formation of conjugation papillae, release of protoplasts from gametangial cells, and fusion of protoplasts to form a zygote. The second step, called sexual cell division (SCD), produces two gametangial cells from one vegetative mother cell. The SCD of mt + cell is mediated by a diffusible sex pheromone, named SCD-inducing pheromone (SCD-IP). This pheromone is released from mt – cells in the light, and the presence of mt + cells stimulates its secretion from mt – cells. SCD-IP was purified by sequential column-chromatographic fractionation from culture medium in which both mating type cells had been co-cultured. Purified SCD-IP is a glycoprotein with an apparent molecular mass of 20 kDa. The molecular mass of the SCD-IP was estimated to be 18 kDa by mass spectrometry. Amino-terminal and two internal amino acid sequences of the pheromone revealed significant similarity to another Closterium pheromone, protoplast release-inducing protein (PR-IP) inducer of Closterium peracerosum-strigosum-littorale complex ( C. pslc ). These two pheromones induced different morphological reactions in each Closterium species. Based on these results, the diversity of sex pheromones is discussed.
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Intercellular Communication During Sexual Reproduction of Closterium (Conjugatophyceae)
Journal of Plant Research, 2000Co-Authors: Hiroyuki SekimotoAbstract:were reviewed. In the case of Closterium peracerosum-strigosum-littorale complex, two sex-specific pheromones and their receptors were involved in sexual reproduction. These pheromones were glycoproteins and the expression of corresponding genes was critically regulated by the sex and environmental conditions. In the case of Closterium ehrenbergii, chemotactic and sexual cell division-inducing activities for mating-type plus cells were detected and characterized. Although many processes remain to be elucidated, the present results will be helpful for understanding not only the mode of sexual reproduction in Closterium but also the variety of intercellular communication in the plant kingdom especially during sexual reproduction.
Ryo-hei Fukumoto - One of the best experts on this subject based on the ideXlab platform.
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CLONING AND CHARACTERIZATION OF A cDNA ENCODING A SEXUAL CELL DIVISION-INDUCING PHEROMONE FROM A UNICELLULAR GREEN ALGA Closterium EHRENBERGII (CHLOROPHYTA)
Journal of Phycology, 2003Co-Authors: Ryo-hei Fukumoto, Tadashi Fujii, Hiroyuki SekimotoAbstract:A full-length cDNA encoding a sexual cell division-inducing pheromone (SCD-IP) was isolated from a heterothallic green alga, Closterium ehrenbergii Menegh. ex Ralfs, using the rapid amplification of cDNA ends-PCR method. The cDNA was 907 bp in length and coded for a protein of 209 amino acids with a deduced molecular mass of M r 23,186. The predicted protein had a possible glycosylation site and a hydrophobic signal peptide for extracellular secretion. Transcripts of the SCD-IP gene were detected only in mating type minus (mt - ) cells and remarkably increased when mt - cells were cocultured with mating type plus (mt + ) cells. By contrast, the gene for SCD-IP was detected in both mating type cells as multicopy genes by Southern blot analysis. Continuous dark conditions and supplementation of a nitrogen source to the culture medium suppressed SCD-IP expression. The deduced amino acid sequences encoded by genes for SCD-IP and protoplast-release-inducing protein (PR-IP) Inducer, a sex pheromone isolated from another Closterium species, appeared to share significant homology, suggesting that these sex pheromones were diversified from a single ancestral Closterium pheromone.
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Purification and characterization of a pheromone that induces sexual cell division in the unicellular green alga Closterium ehrenbergii
Plant Physiology and Biochemistry, 2002Co-Authors: Ryo-hei Fukumoto, Naoshi Dohmae, Kouji Takio, Shinobu Satoh, Tadashi Fujii, Hiroyuki SekimotoAbstract:Abstract Closterium ehrenbergii is a unicellular charophycean alga consisting of two sexes: mating type plus (mt + ) and minus (mt – ). The sexual reproductive process consists of five steps: formation of sexual pairs, cell division of each member of a pair, formation of conjugation papillae, release of protoplasts from gametangial cells, and fusion of protoplasts to form a zygote. The second step, called sexual cell division (SCD), produces two gametangial cells from one vegetative mother cell. The SCD of mt + cell is mediated by a diffusible sex pheromone, named SCD-inducing pheromone (SCD-IP). This pheromone is released from mt – cells in the light, and the presence of mt + cells stimulates its secretion from mt – cells. SCD-IP was purified by sequential column-chromatographic fractionation from culture medium in which both mating type cells had been co-cultured. Purified SCD-IP is a glycoprotein with an apparent molecular mass of 20 kDa. The molecular mass of the SCD-IP was estimated to be 18 kDa by mass spectrometry. Amino-terminal and two internal amino acid sequences of the pheromone revealed significant similarity to another Closterium pheromone, protoplast release-inducing protein (PR-IP) inducer of Closterium peracerosum-strigosum-littorale complex ( C. pslc ). These two pheromones induced different morphological reactions in each Closterium species. Based on these results, the diversity of sex pheromones is discussed.
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Detection and evaluation of a novel sexual pheromone that induces sexual cell division of Closterium ehrenbergii (Chlorophyta)
Journal of Phycology, 1997Co-Authors: Ryo-hei Fukumoto, Tadashi Fujii, Hiroyuki SekimotoAbstract:Mating type-plus (mt+; NIES-228) cells of Closterium ehrenbergii undergo a division to form gamete-shaped cells. This cell division is induced by a substance produced by mating type-minus (mt−; NIES-229) cells. Light and the presence of mt+ cells enhanced production of the substance. The active substance is heat labile and has an apparent molecular mass of 20 kDa. From these results, we conclude that the substance is a novel, proteinaceous sexual pheromone involved in reproduction of Closterium ehrenbergii.
Xiulin Wang - One of the best experts on this subject based on the ideXlab platform.
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effects of ph on the growth and nh4 n uptake of skeletonema costatum and nitzschia Closterium
Marine Pollution Bulletin, 2017Co-Authors: Xingyan Gu, Kai Pang, Keqiang Li, Xiulin WangAbstract:Abstract Ocean acidification (OA) and eutrophication intensifies in coastal sea under anthropogenic impact. OA coupled with the NH4-N source effect in coastal water is likely to affect the planktonic ecosystem. In this work, Skeletonema costatum and Nitzschia Closterium were chosen as typical species of diatom in Chinese coastal ecosystems to test the potential effect of OA and NH4-N. Results showed that the growth and NH4-N uptake of S. costatum and N. Closterium were significantly inhibited by pH decline. The maximum uptake rate is higher than the maximum growth rate, implying that NH4-N was assimilated faster for S. costatum and N. Closterium with decreasing pH. Therefore, the inhibition rate of the growth of the two diatoms by the coupling effect of OA and eutrophication (pH 7.45) is higher that than in the coastal sea by the end of the 21st century (pH 7.71).
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Effects of pH on the growth and NH 4-N uptake of Skeletonema costatum and Nitzschia Closterium
Marine pollution bulletin, 2017Co-Authors: Kai Pang, Xiulin WangAbstract:Ocean acidification (OA) and eutrophication intensifies in coastal sea under anthropogenic impact. OA coupled with the NH4-N source effect in coastal water is likely to affect the planktonic ecosystem. In this work, Skeletonema costatum and Nitzschia Closterium were chosen as typical species of diatom in Chinese coastal ecosystems to test the potential effect of OA and NH4-N. Results showed that the growth and NH4-N uptake of S. costatum and N. Closterium were significantly inhibited by pH decline. The maximum uptake rate is higher than the maximum growth rate, implying that NH4-N was assimilated faster for S. costatum and N. Closterium with decreasing pH. Therefore, the inhibition rate of the growth of the two diatoms by the coupling effect of OA and eutrophication (pH7.45) is higher that than in the coastal sea by the end of the 21st century (pH7.71).
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Size-dependent growth rate of Nitzschia Closterium at different concentrations of petroleum hydrocarbon
Journal of Ocean University of China, 2009Co-Authors: Rujun Yang, Hongjie Tang, Yu Xin, Xiulin WangAbstract:The maximum growth rate of Nitzschia Closterium at various concentrations of petroleum hydrocarbon was studied. The influence of petroleum hydrocarbon on cell size as a function of concentration was discussed. The relationship between maximum growth rate of Nitzschia Closterium and cell median equivalent spherical diameter (MESD) was also carefully studied. The experimental results showed that the growth rate of Nitzschia Closterium was generally suppressed by petroleum hydrocarbon, which had greater effects at both low and high concentrations than at intermediate concentrations. No significant changes in cell size distribution were observed during the growth period of Nitzschia Closterium. The Gaussian function could give a clear description of the cell size distribution of Nitzschia Closterium, and the MESD value ranged from 2.71 to 6.82 μm. The MESD decreased when the cell was exposed to petroleum hydrocarbon, and the reduction of cell MESD was much more significant at both relatively high and low hydrocarbon concentrations. The presence of petroleum hydrocarbon changed the relationship between μmax and MESD from an allometric function to a U-shaped curve. When the MESD was below 5.07 μm, μmax decreased along with increased MESD, whereas when MESD was above 5.07 μm, μmax increased along with MESD, which deviated from the allometric model.
Kai Pang - One of the best experts on this subject based on the ideXlab platform.
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Effects of pH and nitrogen form on Nitzschia Closterium growth by linking dynamic with enzyme activity.
Chemosphere, 2020Co-Authors: Kai PangAbstract:Abstract In this study, Nitzschia Closterium was incubated in seawater at different pH values (8.10, 7.71, and 7.45) and using different nitrogen forms (NO3–N and NH4–N) in the laboratory. The results showed that the growth of N. Closterium was inhibited by ocean acidification, with individuals under lower pH levels showing lower growth rates and lower nitrogen uptake rates for both nitrogen forms. The Vmax/Ks ratio decreased with decreasing pH, indicating the inhibition of nitrogen uptake, whereas the ratios for NH4–N cultures were higher than those for NO3–N cultures, implying the highly competitive position of NH4–N. Acidification might induce reactive oxygen species based on the result that the maximum enzyme activities of SuperOxide Dismutase (SOD) and CATalase (CAT) increased under lower pH levels. The SOD and CAT activities for the NO3–N cultures were higher than those for NH4–N cultures at the low pH level, indicating that acidification might cause more oxidative stress for NO3–N cultures than for NH4–N cultures. Thus, ocean acidification might have a more detrimental effect on the growth of N. Closterium under NO3–N conditions than NH4–N conditions, with a lower ratio (γ) of the maximum growth rate to the maximum nutrient uptake rate, and a drop in nitrate reductase activity under lower pH levels.
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Effects of pH on the growth and NH 4-N uptake of Skeletonema costatum and Nitzschia Closterium
Marine pollution bulletin, 2017Co-Authors: Kai Pang, Xiulin WangAbstract:Ocean acidification (OA) and eutrophication intensifies in coastal sea under anthropogenic impact. OA coupled with the NH4-N source effect in coastal water is likely to affect the planktonic ecosystem. In this work, Skeletonema costatum and Nitzschia Closterium were chosen as typical species of diatom in Chinese coastal ecosystems to test the potential effect of OA and NH4-N. Results showed that the growth and NH4-N uptake of S. costatum and N. Closterium were significantly inhibited by pH decline. The maximum uptake rate is higher than the maximum growth rate, implying that NH4-N was assimilated faster for S. costatum and N. Closterium with decreasing pH. Therefore, the inhibition rate of the growth of the two diatoms by the coupling effect of OA and eutrophication (pH7.45) is higher that than in the coastal sea by the end of the 21st century (pH7.71).
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effects of ph on the growth and nh4 n uptake of skeletonema costatum and nitzschia Closterium
Marine Pollution Bulletin, 2017Co-Authors: Xingyan Gu, Kai Pang, Keqiang Li, Xiulin WangAbstract:Abstract Ocean acidification (OA) and eutrophication intensifies in coastal sea under anthropogenic impact. OA coupled with the NH4-N source effect in coastal water is likely to affect the planktonic ecosystem. In this work, Skeletonema costatum and Nitzschia Closterium were chosen as typical species of diatom in Chinese coastal ecosystems to test the potential effect of OA and NH4-N. Results showed that the growth and NH4-N uptake of S. costatum and N. Closterium were significantly inhibited by pH decline. The maximum uptake rate is higher than the maximum growth rate, implying that NH4-N was assimilated faster for S. costatum and N. Closterium with decreasing pH. Therefore, the inhibition rate of the growth of the two diatoms by the coupling effect of OA and eutrophication (pH 7.45) is higher that than in the coastal sea by the end of the 21st century (pH 7.71).
Tadashi Fujii - One of the best experts on this subject based on the ideXlab platform.
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CLONING AND CHARACTERIZATION OF A cDNA ENCODING A SEXUAL CELL DIVISION-INDUCING PHEROMONE FROM A UNICELLULAR GREEN ALGA Closterium EHRENBERGII (CHLOROPHYTA)
Journal of Phycology, 2003Co-Authors: Ryo-hei Fukumoto, Tadashi Fujii, Hiroyuki SekimotoAbstract:A full-length cDNA encoding a sexual cell division-inducing pheromone (SCD-IP) was isolated from a heterothallic green alga, Closterium ehrenbergii Menegh. ex Ralfs, using the rapid amplification of cDNA ends-PCR method. The cDNA was 907 bp in length and coded for a protein of 209 amino acids with a deduced molecular mass of M r 23,186. The predicted protein had a possible glycosylation site and a hydrophobic signal peptide for extracellular secretion. Transcripts of the SCD-IP gene were detected only in mating type minus (mt - ) cells and remarkably increased when mt - cells were cocultured with mating type plus (mt + ) cells. By contrast, the gene for SCD-IP was detected in both mating type cells as multicopy genes by Southern blot analysis. Continuous dark conditions and supplementation of a nitrogen source to the culture medium suppressed SCD-IP expression. The deduced amino acid sequences encoded by genes for SCD-IP and protoplast-release-inducing protein (PR-IP) Inducer, a sex pheromone isolated from another Closterium species, appeared to share significant homology, suggesting that these sex pheromones were diversified from a single ancestral Closterium pheromone.
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Purification and characterization of a pheromone that induces sexual cell division in the unicellular green alga Closterium ehrenbergii
Plant Physiology and Biochemistry, 2002Co-Authors: Ryo-hei Fukumoto, Naoshi Dohmae, Kouji Takio, Shinobu Satoh, Tadashi Fujii, Hiroyuki SekimotoAbstract:Abstract Closterium ehrenbergii is a unicellular charophycean alga consisting of two sexes: mating type plus (mt + ) and minus (mt – ). The sexual reproductive process consists of five steps: formation of sexual pairs, cell division of each member of a pair, formation of conjugation papillae, release of protoplasts from gametangial cells, and fusion of protoplasts to form a zygote. The second step, called sexual cell division (SCD), produces two gametangial cells from one vegetative mother cell. The SCD of mt + cell is mediated by a diffusible sex pheromone, named SCD-inducing pheromone (SCD-IP). This pheromone is released from mt – cells in the light, and the presence of mt + cells stimulates its secretion from mt – cells. SCD-IP was purified by sequential column-chromatographic fractionation from culture medium in which both mating type cells had been co-cultured. Purified SCD-IP is a glycoprotein with an apparent molecular mass of 20 kDa. The molecular mass of the SCD-IP was estimated to be 18 kDa by mass spectrometry. Amino-terminal and two internal amino acid sequences of the pheromone revealed significant similarity to another Closterium pheromone, protoplast release-inducing protein (PR-IP) inducer of Closterium peracerosum-strigosum-littorale complex ( C. pslc ). These two pheromones induced different morphological reactions in each Closterium species. Based on these results, the diversity of sex pheromones is discussed.
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Detection and evaluation of a novel sexual pheromone that induces sexual cell division of Closterium ehrenbergii (Chlorophyta)
Journal of Phycology, 1997Co-Authors: Ryo-hei Fukumoto, Tadashi Fujii, Hiroyuki SekimotoAbstract:Mating type-plus (mt+; NIES-228) cells of Closterium ehrenbergii undergo a division to form gamete-shaped cells. This cell division is induced by a substance produced by mating type-minus (mt−; NIES-229) cells. Light and the presence of mt+ cells enhanced production of the substance. The active substance is heat labile and has an apparent molecular mass of 20 kDa. From these results, we conclude that the substance is a novel, proteinaceous sexual pheromone involved in reproduction of Closterium ehrenbergii.