The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Michael A. Borowitzka - One of the best experts on this subject based on the ideXlab platform.
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Coccolithophorid algae culture in closed photobioreactors.
Biotechnology and Bioengineering, 2011Co-Authors: Navid R. Moheimani, Andreas Isdepsky, Jan Lisec, Eric J Raes, Michael A. BorowitzkaAbstract:The feasibility of growth, calcium carbonate and lipid production of the coccolithophorid algae (Prymnesiophyceae), Pleurochrysis carterae, Emiliania huxleyi, and Gephyrocapsa oceanica, was investigated in plate, carboy, airlift, and tubular photobioreactors. The plate photobioreactor was the most promising closed cultivation system. All species could be grown in the carboy photobioreactor. However, P. carterae was the only species which grew in an airlift photobioreactor. Despite several attempts to grow these coccolithophorid species in the tubular photobioreactor (Biocoil), including modification of the airlift and sparger design, no net growth could be achieved. The shear produced by turbulence and bubble effects are the most likely reasons for this failure to grow in the Biocoil. The highest total dry weight, lipid and calcium carbonate productivities achieved by P. carterae in the plate photobioreactors were 0.54, 0.12, and 0.06gL-1day-1 respectively. Irrespective of the type of photobioreactor, the productivities were P. carterae>E. huxleyi>G. oceanica. Pleurochrysis carterae lipid (20-25% of dry weight) and calcium carbonate (11-12% of dry weight) contents were also the highest of all species tested.
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Increased CO2 and the effect of pH on growth and calcification of Pleurochrysis carterae and Emiliania huxleyi (Haptophyta) in semicontinuous cultures
Applied microbiology and biotechnology, 2011Co-Authors: Navid R. Moheimani, Michael A. BorowitzkaAbstract:The effects of changes in CO2 and pH on biomass productivity and carbon uptake of Pleurochrysis carterae and Emiliania huxleyi in open raceway ponds and a plate photobioreactor were studied. The pH of P. carterae cultures increased during day and decreased at night, whereas the pH of E. huxleyi cultures showed no significant diurnal changes. P. carterae coccolith production occurs during the dark period, whereas in E. huxleyi, coccolith production is mainly during the day. Addition of CO2 at constant pH (pH-stat) resulted in an increase in P. carterae biomass and coccolith productivity, while CO2 addition lowered E. huxleyi biomass and coccolith production. Neither of these algae could grow at less than pH 7.5. Species-specific diurnal pH and pCO2 variations could be indicative of significant differences in carbon uptake between these two species. While E. huxleyi has been suggested to be predominantly a bicarbonate user, our results indicate that P. carterae may be using CO2 as the main C source for photosynthesis and calcification.
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limits to productivity of the alga Pleurochrysis carterae haptophyta grown in outdoor raceway ponds
Biotechnology and Bioengineering, 2007Co-Authors: Navid R. Moheimani, Michael A. BorowitzkaAbstract:This study examined the effects of oxygen concentration, pond temperature and irradiance on pro- ductivity and CaCO3 formation of the coccolith-forming alga, Pleurochrysis carterae CCMP647 grown in semi-con- tinuous culture in outdoor raceway ponds. During the day the oxygen content of the pond increases markedly and P. carterae photosynthesis is inhibited by these high O2 con- centrations with the inhibition increasing with increasing temperature. The high irradiance outdoors presents less of a problem to photosynthesis and productivity as the algae can acclimate well to high irradiances over a period of several weeks. Pond depth also effects productivity and this effect varies with season. During autumn, productivities were highest at depths of 13 to 16 cm, and decreased when the depth was increased. During summer productivity was much lower at 13 cm pond depth and increased when the depth was increased to 16, 18 and 21 cm. Heating the ponds in the morning by approximately 3 to 58C improves pro- ductivity by 11%-21%, presumably because this allows the algae to photosynthesise faster in the conditions of low (O2) which occur in the early morning. Biotechnol. Bioeng. 2007;96: 27-36.
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The long-term culture of the coccolithophore Pleurochrysis carterae (Haptophyta) in outdoor raceway ponds
Journal of Applied Phycology, 2006Co-Authors: Navid R. Moheimani, Michael A. BorowitzkaAbstract:The calcareous marine haptophyte algae, the coccolithophorids, are of global environmental significance because of the impact of their blooms on the carbon cycle. The coccolithophorid, Pleurochrysis carterae was grown semi-continuously in paddlewheel-driven outdoor raceway ponds over a period of 13 months in Perth, Western Australia. The mean total dry weight productivity of P. carterae was 0.19 g.L^−1.d^−1 with cell lipid and CaCO_3 contents of up to 33% and 10% of dry weight respectively, equivalent to an annual total biomass productivity of about 60 t.ha^−1.y^−1 and 21.9 t.ha^−1.y^−1 total lipid and 5.5 t.ha^−1.y^−1 total calcium carbonate production. Throughout the culture period there was little protozoan contamination or contamination by other algae. The pH of the growth medium increased to pH 11 during the day and was found to be a useful variable for monitoring the state of the culture. A comparison of the growth of P. carterae and Dunaliella salina in the raceway ponds showed no significant differences between these two species with regard to areal total dry weight productivity and lipid content.
Mikio Tsuzuki - One of the best experts on this subject based on the ideXlab platform.
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Pleurochrysome: A Web Database of Pleurochrysis Transcripts and Orthologs Among Heterogeneous Algae
2015Co-Authors: Naoki Yamamoto, Shoko Fujiwara, Yasutaka Hirokawa, Mikio Tsuzuki, Toru Kudo, Yukiko Takatsuka, Tomoyuki Takano, Masaaki Kobayashi, Kunihiro Suda, Erika AsamizuAbstract:Pleurochrysis is a coccolithophorid genus, which belongs to the Coccolithales in the Haptophyta. The genus has been used extensively for biological research, together with Emiliania in the Isochrysidales, to understand distinctive fea-tures between the two coccolithophorid-including orders. However, molecular biological research on Pleurochrysis such as elucidation of the molecular mechanism behind coccolith formation has not made great progress at least in part because of lack of comprehensive gene information. To provide such information to the research community, we built an open web database, the Pleurochrysom
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Localization and Associative Strength of Acid Polysaccharides in Coccoliths of Pleurochrysis haptonemofera (Haptophyta) Predicted from Their Extractability from Partially Decalcified Coccoliths
Open Journal of Marine Science, 2013Co-Authors: Yasutaka Hirokawa, Shoko Fujiwara, Noriaki Ozaki, Hiromichi Nagasawa, Satoru Matsuzuka, Sho Itayama, Tatsuya Uchida, Mikio TsuzukiAbstract:The coccolithophorids have calcified scales called coccoliths on their surface that include abundant acid polysaccharides. To determine the localization and associative strength of acid polysaccharides Ph-PS-1, -2, and -3 incoccoliths of Pleurochrysis haptonemofera, we analyzed the acid polysaccharides extracted with urea from partially decalcified coccoliths. On treatment of coccoliths with8.0 Murea at pH8.0 inboiling water, Ph-PS-2 was not extracted, but parts of Ph-PS-1 and -3 were from the surface without the crystal morphology being affected. When coccoliths were partially decalcified at various pHs (pH 8.0 - 5.0), Ph-PS-1, -3, and -2 were extracted with urea in that order as the calcite crystals dissolved. Detection of the acid polysaccharides using fluorescein-isothiocyanate-labeled lectin (ConA) and anti-Ph-PS-2 antibodies demonstrated that Ph-PS-2 exists on the surfaces of both untreated and urea-treated coccoliths. Moreover, NaClO-treatment under moderate conditions extracted only Ph-PS-1, -3, and part of Ph-PS-2 from coccoliths, without separation of the crystal units, suggesting that at least some part of Ph-PS-2 acts as a glue connecting crystal units and/or a crystal unit and a base plate inside coccoliths. These results suggest that Ph-PS-2 exists not only on the surface but also inside of the coccoliths, most of it being strongly bound to coccoliths, while Ph-PS-1 and -3 are weakly associated close to the coccolith surface, in that order from the surface. This strongly supports a scheme in which PS-2 type acid polysaccharides play an important role in the crystal nucleation and PS-3 type functions during crystal growth.
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Structural and physiological studies on the storage β-polyglucan of haptophyte Pleurochrysis haptonemofera
Planta, 2008Co-Authors: Yasutaka Hirokawa, Shoko Fujiwara, Motoya Suzuki, Tomoka Akiyama, Minako Sakamoto, Saori Kobayashi, Mikio TsuzukiAbstract:The storage β-polyglucan and catabolic enzyme activities of the haptophyte Pleurochrysis haptonemofera were characterized. The storage β-polyglucan was prepared by the dimethylsulfoxide-extraction method. ^13C- and ^1H-NMR spectroscopy revealed that the polyglucan consists of β-(1→3)- and β-(1→6)-linked glucose polymers, with a β-(1→6)- to β-(1→3)-linkage ratio of 1.5. Gel permeation chromatography showed that the molecular weight of the polyglucan is 1.1–8.4 × 10^4 Da, with a peak at 3.4 × 10^4 Da. The degree of polymerization, which was estimated from the amounts of total carbohydrate and reduced ends, was 203, corresponding to 3.3 × 10^4 Da. A method for measurement of the β-polyglucan in a small amount of liquid culture involving a mixture of β-glucanases, Westase, was established. The β-polyglucan was localized in the soluble fraction of cells. The amount of β-polyglucan per cell increased at the stationary phase under continuous illumination and decreased in the dark, like those of storage α-polyglucans, starch of green algae and glycogen of cyanobacteria. The activities of β-1,3- and β-1,6-glucanases involved in the degradation of the storage β-polyglucan were assayed in vitro, both being optimal at pH 5.0. The β-1,3-glucanase activity, which was detected on active staining after native polyacrylamide gel electrophoresis, was partially purified by ammonium sulfate precipitation and anion exchange chromatography.
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Gene Expression Profiling of Coccolith-Bearing Cells and Naked Cells in Haptophyte Pleurochrysis haptonemofera with a cDNA Macroarray System
Marine Biotechnology, 2007Co-Authors: Shoko Fujiwara, Yasutaka Hirokawa, Yukiko Takatsuka, Kunihiro Suda, Erika Asamizu, Takatoshi Takayanagi, Daisuke Shibata, Satoshi Tabata, Mikio TsuzukiAbstract:Pleurochrysis haptonemofera is a unicellular marine coccolithophorid that has calcified scales, coccoliths, on the cell surface. Some coccolithophorids including P. haptonemofera have a coccolith-bearing stage and a naked stage in their life cycles. To characterize genes involved in the coccolithogenesis, we generated a total of 9550 expressed sequence tags (EST) from a normalized cDNA library that was prepared using both coccolith-bearing cells (C-cells) and naked cells (N-cells), constructed a cDNA macroarray using the EST clones, and then analyzed the gene expression specificity in C-cells and N-cells. When cDNA clones whose expression ratio exceeded 3-fold were selected, as many as 180 clones were identified as C-cell-specific ones, while only 12 were found to be N-cell-specific ones. These clones were sequenced, assembled, and homology-searched against a public nonredundant protein database. As a result, they were grouped into 54 C-cell-specific and 6 N-cell-specific genes, and 59% and 50% of these genes exhibited significant similarity to those of other known proteins, respectively. To assess mRNA expression further, Northern hybridization was performed for 12 of the C-cell-specific genes and one of the N-cell-specific ones. These clones, together with the new cDNA macroarray, will provide a powerful tool for the future genome-wide functional analysis of uncharacterized genes related to the regulation of the calcification and life cycle of coccolithophorids.
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three types of acidic polysaccharides associated with coccolith of Pleurochrysis haptonemofera comparison with Pleurochrysis carterae and analysis using fluorescein isothiocyanate labeled lectins
Marine Biotechnology, 2005Co-Authors: Yasutaka Hirokawa, Shoko Fujiwara, Mikio TsuzukiAbstract:In the coccolithophorid microalgae acidic polysaccharides are considered to be involved in the formation of the calcified scale, coccolith. Characteristics of the acidic polysaccharides extracted from the cell surface of the coccolithophorid Pleurochrysis haptonemofera were analyzed. The acidic polysaccharides on the cell surface can be detected by measuring fluorescence of cells after fluorescein-isothiocyanate-labeled lectin staining by flow cytometry. Flow cytometric analyses revealed that the acidic polysaccharides remained on the cell surface even after CaCO3 in the coccolith was dissolved by lowering pH, but they were extracted by subsequent EDTA or EGTA treatment, suggesting that they are bound not into the CaCO3 crystals of the coccolith, but onto the surface via Ca2+. Analyses of the acidic polysaccharides by anion exchange chromatography, colloidal precipitation with divalent cations, and polyacrylamide gel electrophoresis (PAGE) revealed that P. haptonemofera has 3 types of acidic polysaccharides (Ph-PS-l, -2, and -3). The PAGE patterns suggested that Ph-PS-2 has a repeated structure with a broad range of molecular weight, as in Pleurochrysis carterae, while Ph-PS-1 and -3 contain several minor components in addition to a major component, respectively. The minor components in Ph-PS-1 and -3 that have not been found in P. carterae might be characteristic of P. haptonemofera. Analyses of both the cell surface treated by various concentrations of EDTA and EGTA and the extracts suggested that Ph-PS-2, which is distinguishable by a higher affinity to concanavalin A, is bound onto the coccolith surface more intensely than the other two types of acidic polysaccharides.
Navid R. Moheimani - One of the best experts on this subject based on the ideXlab platform.
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Coccolithophorid algae culture in closed photobioreactors.
Biotechnology and Bioengineering, 2011Co-Authors: Navid R. Moheimani, Andreas Isdepsky, Jan Lisec, Eric J Raes, Michael A. BorowitzkaAbstract:The feasibility of growth, calcium carbonate and lipid production of the coccolithophorid algae (Prymnesiophyceae), Pleurochrysis carterae, Emiliania huxleyi, and Gephyrocapsa oceanica, was investigated in plate, carboy, airlift, and tubular photobioreactors. The plate photobioreactor was the most promising closed cultivation system. All species could be grown in the carboy photobioreactor. However, P. carterae was the only species which grew in an airlift photobioreactor. Despite several attempts to grow these coccolithophorid species in the tubular photobioreactor (Biocoil), including modification of the airlift and sparger design, no net growth could be achieved. The shear produced by turbulence and bubble effects are the most likely reasons for this failure to grow in the Biocoil. The highest total dry weight, lipid and calcium carbonate productivities achieved by P. carterae in the plate photobioreactors were 0.54, 0.12, and 0.06gL-1day-1 respectively. Irrespective of the type of photobioreactor, the productivities were P. carterae>E. huxleyi>G. oceanica. Pleurochrysis carterae lipid (20-25% of dry weight) and calcium carbonate (11-12% of dry weight) contents were also the highest of all species tested.
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Increased CO2 and the effect of pH on growth and calcification of Pleurochrysis carterae and Emiliania huxleyi (Haptophyta) in semicontinuous cultures
Applied microbiology and biotechnology, 2011Co-Authors: Navid R. Moheimani, Michael A. BorowitzkaAbstract:The effects of changes in CO2 and pH on biomass productivity and carbon uptake of Pleurochrysis carterae and Emiliania huxleyi in open raceway ponds and a plate photobioreactor were studied. The pH of P. carterae cultures increased during day and decreased at night, whereas the pH of E. huxleyi cultures showed no significant diurnal changes. P. carterae coccolith production occurs during the dark period, whereas in E. huxleyi, coccolith production is mainly during the day. Addition of CO2 at constant pH (pH-stat) resulted in an increase in P. carterae biomass and coccolith productivity, while CO2 addition lowered E. huxleyi biomass and coccolith production. Neither of these algae could grow at less than pH 7.5. Species-specific diurnal pH and pCO2 variations could be indicative of significant differences in carbon uptake between these two species. While E. huxleyi has been suggested to be predominantly a bicarbonate user, our results indicate that P. carterae may be using CO2 as the main C source for photosynthesis and calcification.
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Coccolithophorid algae culture in closed photobioreactors
'Wiley', 2011Co-Authors: Navid R. Moheimani, Isdepsky A, Lisec J, Raes EAbstract:The feasibility of growth, calcium carbonate and lipid production of the coccolithophorid algae (Prymnesiophyceae), Pleurochrysis carterae, Emiliania huxleyi, and Gephyrocapsa oceanica, was investigated in plate, carboy, airlift, and tubular photobioreactors. The plate photobioreactor was the most promising closed cultivation system. All species could be grown in the carboy photobioreactor. However, P. carterae was the only species which grew in an airlift photobioreactor. Despite several attempts to grow these coccolithophorid species in the tubular photobioreactor (Biocoil), including modification of the airlift and sparger design, no net growth could be achieved. The shear produced by turbulence and bubble effects are the most likely reasons for this failure to grow in the Biocoil. The highest total dry weight, lipid and calcium carbonate productivities achieved by P. carterae in the plate photobioreactors were 0.54, 0.12, and 0.06gL-1day-1 respectively. Irrespective of the type of photobioreactor, the productivities were P. carterae>E. huxleyi>G. oceanica. Pleurochrysis carterae lipid (20-25% of dry weight) and calcium carbonate (11-12% of dry weight) contents were also the highest of all species tested. © 2011 Wiley Periodicals, Inc
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limits to productivity of the alga Pleurochrysis carterae haptophyta grown in outdoor raceway ponds
Biotechnology and Bioengineering, 2007Co-Authors: Navid R. Moheimani, Michael A. BorowitzkaAbstract:This study examined the effects of oxygen concentration, pond temperature and irradiance on pro- ductivity and CaCO3 formation of the coccolith-forming alga, Pleurochrysis carterae CCMP647 grown in semi-con- tinuous culture in outdoor raceway ponds. During the day the oxygen content of the pond increases markedly and P. carterae photosynthesis is inhibited by these high O2 con- centrations with the inhibition increasing with increasing temperature. The high irradiance outdoors presents less of a problem to photosynthesis and productivity as the algae can acclimate well to high irradiances over a period of several weeks. Pond depth also effects productivity and this effect varies with season. During autumn, productivities were highest at depths of 13 to 16 cm, and decreased when the depth was increased. During summer productivity was much lower at 13 cm pond depth and increased when the depth was increased to 16, 18 and 21 cm. Heating the ponds in the morning by approximately 3 to 58C improves pro- ductivity by 11%-21%, presumably because this allows the algae to photosynthesise faster in the conditions of low (O2) which occur in the early morning. Biotechnol. Bioeng. 2007;96: 27-36.
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The long-term culture of the coccolithophore Pleurochrysis carterae (Haptophyta) in outdoor raceway ponds
Journal of Applied Phycology, 2006Co-Authors: Navid R. Moheimani, Michael A. BorowitzkaAbstract:The calcareous marine haptophyte algae, the coccolithophorids, are of global environmental significance because of the impact of their blooms on the carbon cycle. The coccolithophorid, Pleurochrysis carterae was grown semi-continuously in paddlewheel-driven outdoor raceway ponds over a period of 13 months in Perth, Western Australia. The mean total dry weight productivity of P. carterae was 0.19 g.L^−1.d^−1 with cell lipid and CaCO_3 contents of up to 33% and 10% of dry weight respectively, equivalent to an annual total biomass productivity of about 60 t.ha^−1.y^−1 and 21.9 t.ha^−1.y^−1 total lipid and 5.5 t.ha^−1.y^−1 total calcium carbonate production. Throughout the culture period there was little protozoan contamination or contamination by other algae. The pH of the growth medium increased to pH 11 during the day and was found to be a useful variable for monitoring the state of the culture. A comparison of the growth of P. carterae and Dunaliella salina in the raceway ponds showed no significant differences between these two species with regard to areal total dry weight productivity and lipid content.
Shoko Fujiwara - One of the best experts on this subject based on the ideXlab platform.
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Pleurochrysome: A Web Database of Pleurochrysis Transcripts and Orthologs Among Heterogeneous Algae
2015Co-Authors: Naoki Yamamoto, Shoko Fujiwara, Yasutaka Hirokawa, Mikio Tsuzuki, Toru Kudo, Yukiko Takatsuka, Tomoyuki Takano, Masaaki Kobayashi, Kunihiro Suda, Erika AsamizuAbstract:Pleurochrysis is a coccolithophorid genus, which belongs to the Coccolithales in the Haptophyta. The genus has been used extensively for biological research, together with Emiliania in the Isochrysidales, to understand distinctive fea-tures between the two coccolithophorid-including orders. However, molecular biological research on Pleurochrysis such as elucidation of the molecular mechanism behind coccolith formation has not made great progress at least in part because of lack of comprehensive gene information. To provide such information to the research community, we built an open web database, the Pleurochrysom
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Localization and Associative Strength of Acid Polysaccharides in Coccoliths of Pleurochrysis haptonemofera (Haptophyta) Predicted from Their Extractability from Partially Decalcified Coccoliths
Open Journal of Marine Science, 2013Co-Authors: Yasutaka Hirokawa, Shoko Fujiwara, Noriaki Ozaki, Hiromichi Nagasawa, Satoru Matsuzuka, Sho Itayama, Tatsuya Uchida, Mikio TsuzukiAbstract:The coccolithophorids have calcified scales called coccoliths on their surface that include abundant acid polysaccharides. To determine the localization and associative strength of acid polysaccharides Ph-PS-1, -2, and -3 incoccoliths of Pleurochrysis haptonemofera, we analyzed the acid polysaccharides extracted with urea from partially decalcified coccoliths. On treatment of coccoliths with8.0 Murea at pH8.0 inboiling water, Ph-PS-2 was not extracted, but parts of Ph-PS-1 and -3 were from the surface without the crystal morphology being affected. When coccoliths were partially decalcified at various pHs (pH 8.0 - 5.0), Ph-PS-1, -3, and -2 were extracted with urea in that order as the calcite crystals dissolved. Detection of the acid polysaccharides using fluorescein-isothiocyanate-labeled lectin (ConA) and anti-Ph-PS-2 antibodies demonstrated that Ph-PS-2 exists on the surfaces of both untreated and urea-treated coccoliths. Moreover, NaClO-treatment under moderate conditions extracted only Ph-PS-1, -3, and part of Ph-PS-2 from coccoliths, without separation of the crystal units, suggesting that at least some part of Ph-PS-2 acts as a glue connecting crystal units and/or a crystal unit and a base plate inside coccoliths. These results suggest that Ph-PS-2 exists not only on the surface but also inside of the coccoliths, most of it being strongly bound to coccoliths, while Ph-PS-1 and -3 are weakly associated close to the coccolith surface, in that order from the surface. This strongly supports a scheme in which PS-2 type acid polysaccharides play an important role in the crystal nucleation and PS-3 type functions during crystal growth.
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Structural and physiological studies on the storage β-polyglucan of haptophyte Pleurochrysis haptonemofera
Planta, 2008Co-Authors: Yasutaka Hirokawa, Shoko Fujiwara, Motoya Suzuki, Tomoka Akiyama, Minako Sakamoto, Saori Kobayashi, Mikio TsuzukiAbstract:The storage β-polyglucan and catabolic enzyme activities of the haptophyte Pleurochrysis haptonemofera were characterized. The storage β-polyglucan was prepared by the dimethylsulfoxide-extraction method. ^13C- and ^1H-NMR spectroscopy revealed that the polyglucan consists of β-(1→3)- and β-(1→6)-linked glucose polymers, with a β-(1→6)- to β-(1→3)-linkage ratio of 1.5. Gel permeation chromatography showed that the molecular weight of the polyglucan is 1.1–8.4 × 10^4 Da, with a peak at 3.4 × 10^4 Da. The degree of polymerization, which was estimated from the amounts of total carbohydrate and reduced ends, was 203, corresponding to 3.3 × 10^4 Da. A method for measurement of the β-polyglucan in a small amount of liquid culture involving a mixture of β-glucanases, Westase, was established. The β-polyglucan was localized in the soluble fraction of cells. The amount of β-polyglucan per cell increased at the stationary phase under continuous illumination and decreased in the dark, like those of storage α-polyglucans, starch of green algae and glycogen of cyanobacteria. The activities of β-1,3- and β-1,6-glucanases involved in the degradation of the storage β-polyglucan were assayed in vitro, both being optimal at pH 5.0. The β-1,3-glucanase activity, which was detected on active staining after native polyacrylamide gel electrophoresis, was partially purified by ammonium sulfate precipitation and anion exchange chromatography.
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Gene Expression Profiling of Coccolith-Bearing Cells and Naked Cells in Haptophyte Pleurochrysis haptonemofera with a cDNA Macroarray System
Marine Biotechnology, 2007Co-Authors: Shoko Fujiwara, Yasutaka Hirokawa, Yukiko Takatsuka, Kunihiro Suda, Erika Asamizu, Takatoshi Takayanagi, Daisuke Shibata, Satoshi Tabata, Mikio TsuzukiAbstract:Pleurochrysis haptonemofera is a unicellular marine coccolithophorid that has calcified scales, coccoliths, on the cell surface. Some coccolithophorids including P. haptonemofera have a coccolith-bearing stage and a naked stage in their life cycles. To characterize genes involved in the coccolithogenesis, we generated a total of 9550 expressed sequence tags (EST) from a normalized cDNA library that was prepared using both coccolith-bearing cells (C-cells) and naked cells (N-cells), constructed a cDNA macroarray using the EST clones, and then analyzed the gene expression specificity in C-cells and N-cells. When cDNA clones whose expression ratio exceeded 3-fold were selected, as many as 180 clones were identified as C-cell-specific ones, while only 12 were found to be N-cell-specific ones. These clones were sequenced, assembled, and homology-searched against a public nonredundant protein database. As a result, they were grouped into 54 C-cell-specific and 6 N-cell-specific genes, and 59% and 50% of these genes exhibited significant similarity to those of other known proteins, respectively. To assess mRNA expression further, Northern hybridization was performed for 12 of the C-cell-specific genes and one of the N-cell-specific ones. These clones, together with the new cDNA macroarray, will provide a powerful tool for the future genome-wide functional analysis of uncharacterized genes related to the regulation of the calcification and life cycle of coccolithophorids.
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three types of acidic polysaccharides associated with coccolith of Pleurochrysis haptonemofera comparison with Pleurochrysis carterae and analysis using fluorescein isothiocyanate labeled lectins
Marine Biotechnology, 2005Co-Authors: Yasutaka Hirokawa, Shoko Fujiwara, Mikio TsuzukiAbstract:In the coccolithophorid microalgae acidic polysaccharides are considered to be involved in the formation of the calcified scale, coccolith. Characteristics of the acidic polysaccharides extracted from the cell surface of the coccolithophorid Pleurochrysis haptonemofera were analyzed. The acidic polysaccharides on the cell surface can be detected by measuring fluorescence of cells after fluorescein-isothiocyanate-labeled lectin staining by flow cytometry. Flow cytometric analyses revealed that the acidic polysaccharides remained on the cell surface even after CaCO3 in the coccolith was dissolved by lowering pH, but they were extracted by subsequent EDTA or EGTA treatment, suggesting that they are bound not into the CaCO3 crystals of the coccolith, but onto the surface via Ca2+. Analyses of the acidic polysaccharides by anion exchange chromatography, colloidal precipitation with divalent cations, and polyacrylamide gel electrophoresis (PAGE) revealed that P. haptonemofera has 3 types of acidic polysaccharides (Ph-PS-l, -2, and -3). The PAGE patterns suggested that Ph-PS-2 has a repeated structure with a broad range of molecular weight, as in Pleurochrysis carterae, while Ph-PS-1 and -3 contain several minor components in addition to a major component, respectively. The minor components in Ph-PS-1 and -3 that have not been found in P. carterae might be characteristic of P. haptonemofera. Analyses of both the cell surface treated by various concentrations of EDTA and EGTA and the extracts suggested that Ph-PS-2, which is distinguishable by a higher affinity to concanavalin A, is bound onto the coccolith surface more intensely than the other two types of acidic polysaccharides.
Yasutaka Hirokawa - One of the best experts on this subject based on the ideXlab platform.
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Pleurochrysome: A Web Database of Pleurochrysis Transcripts and Orthologs Among Heterogeneous Algae
2015Co-Authors: Naoki Yamamoto, Shoko Fujiwara, Yasutaka Hirokawa, Mikio Tsuzuki, Toru Kudo, Yukiko Takatsuka, Tomoyuki Takano, Masaaki Kobayashi, Kunihiro Suda, Erika AsamizuAbstract:Pleurochrysis is a coccolithophorid genus, which belongs to the Coccolithales in the Haptophyta. The genus has been used extensively for biological research, together with Emiliania in the Isochrysidales, to understand distinctive fea-tures between the two coccolithophorid-including orders. However, molecular biological research on Pleurochrysis such as elucidation of the molecular mechanism behind coccolith formation has not made great progress at least in part because of lack of comprehensive gene information. To provide such information to the research community, we built an open web database, the Pleurochrysom
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Localization and Associative Strength of Acid Polysaccharides in Coccoliths of Pleurochrysis haptonemofera (Haptophyta) Predicted from Their Extractability from Partially Decalcified Coccoliths
Open Journal of Marine Science, 2013Co-Authors: Yasutaka Hirokawa, Shoko Fujiwara, Noriaki Ozaki, Hiromichi Nagasawa, Satoru Matsuzuka, Sho Itayama, Tatsuya Uchida, Mikio TsuzukiAbstract:The coccolithophorids have calcified scales called coccoliths on their surface that include abundant acid polysaccharides. To determine the localization and associative strength of acid polysaccharides Ph-PS-1, -2, and -3 incoccoliths of Pleurochrysis haptonemofera, we analyzed the acid polysaccharides extracted with urea from partially decalcified coccoliths. On treatment of coccoliths with8.0 Murea at pH8.0 inboiling water, Ph-PS-2 was not extracted, but parts of Ph-PS-1 and -3 were from the surface without the crystal morphology being affected. When coccoliths were partially decalcified at various pHs (pH 8.0 - 5.0), Ph-PS-1, -3, and -2 were extracted with urea in that order as the calcite crystals dissolved. Detection of the acid polysaccharides using fluorescein-isothiocyanate-labeled lectin (ConA) and anti-Ph-PS-2 antibodies demonstrated that Ph-PS-2 exists on the surfaces of both untreated and urea-treated coccoliths. Moreover, NaClO-treatment under moderate conditions extracted only Ph-PS-1, -3, and part of Ph-PS-2 from coccoliths, without separation of the crystal units, suggesting that at least some part of Ph-PS-2 acts as a glue connecting crystal units and/or a crystal unit and a base plate inside coccoliths. These results suggest that Ph-PS-2 exists not only on the surface but also inside of the coccoliths, most of it being strongly bound to coccoliths, while Ph-PS-1 and -3 are weakly associated close to the coccolith surface, in that order from the surface. This strongly supports a scheme in which PS-2 type acid polysaccharides play an important role in the crystal nucleation and PS-3 type functions during crystal growth.
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Structural and physiological studies on the storage β-polyglucan of haptophyte Pleurochrysis haptonemofera
Planta, 2008Co-Authors: Yasutaka Hirokawa, Shoko Fujiwara, Motoya Suzuki, Tomoka Akiyama, Minako Sakamoto, Saori Kobayashi, Mikio TsuzukiAbstract:The storage β-polyglucan and catabolic enzyme activities of the haptophyte Pleurochrysis haptonemofera were characterized. The storage β-polyglucan was prepared by the dimethylsulfoxide-extraction method. ^13C- and ^1H-NMR spectroscopy revealed that the polyglucan consists of β-(1→3)- and β-(1→6)-linked glucose polymers, with a β-(1→6)- to β-(1→3)-linkage ratio of 1.5. Gel permeation chromatography showed that the molecular weight of the polyglucan is 1.1–8.4 × 10^4 Da, with a peak at 3.4 × 10^4 Da. The degree of polymerization, which was estimated from the amounts of total carbohydrate and reduced ends, was 203, corresponding to 3.3 × 10^4 Da. A method for measurement of the β-polyglucan in a small amount of liquid culture involving a mixture of β-glucanases, Westase, was established. The β-polyglucan was localized in the soluble fraction of cells. The amount of β-polyglucan per cell increased at the stationary phase under continuous illumination and decreased in the dark, like those of storage α-polyglucans, starch of green algae and glycogen of cyanobacteria. The activities of β-1,3- and β-1,6-glucanases involved in the degradation of the storage β-polyglucan were assayed in vitro, both being optimal at pH 5.0. The β-1,3-glucanase activity, which was detected on active staining after native polyacrylamide gel electrophoresis, was partially purified by ammonium sulfate precipitation and anion exchange chromatography.
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Gene Expression Profiling of Coccolith-Bearing Cells and Naked Cells in Haptophyte Pleurochrysis haptonemofera with a cDNA Macroarray System
Marine Biotechnology, 2007Co-Authors: Shoko Fujiwara, Yasutaka Hirokawa, Yukiko Takatsuka, Kunihiro Suda, Erika Asamizu, Takatoshi Takayanagi, Daisuke Shibata, Satoshi Tabata, Mikio TsuzukiAbstract:Pleurochrysis haptonemofera is a unicellular marine coccolithophorid that has calcified scales, coccoliths, on the cell surface. Some coccolithophorids including P. haptonemofera have a coccolith-bearing stage and a naked stage in their life cycles. To characterize genes involved in the coccolithogenesis, we generated a total of 9550 expressed sequence tags (EST) from a normalized cDNA library that was prepared using both coccolith-bearing cells (C-cells) and naked cells (N-cells), constructed a cDNA macroarray using the EST clones, and then analyzed the gene expression specificity in C-cells and N-cells. When cDNA clones whose expression ratio exceeded 3-fold were selected, as many as 180 clones were identified as C-cell-specific ones, while only 12 were found to be N-cell-specific ones. These clones were sequenced, assembled, and homology-searched against a public nonredundant protein database. As a result, they were grouped into 54 C-cell-specific and 6 N-cell-specific genes, and 59% and 50% of these genes exhibited significant similarity to those of other known proteins, respectively. To assess mRNA expression further, Northern hybridization was performed for 12 of the C-cell-specific genes and one of the N-cell-specific ones. These clones, together with the new cDNA macroarray, will provide a powerful tool for the future genome-wide functional analysis of uncharacterized genes related to the regulation of the calcification and life cycle of coccolithophorids.
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three types of acidic polysaccharides associated with coccolith of Pleurochrysis haptonemofera comparison with Pleurochrysis carterae and analysis using fluorescein isothiocyanate labeled lectins
Marine Biotechnology, 2005Co-Authors: Yasutaka Hirokawa, Shoko Fujiwara, Mikio TsuzukiAbstract:In the coccolithophorid microalgae acidic polysaccharides are considered to be involved in the formation of the calcified scale, coccolith. Characteristics of the acidic polysaccharides extracted from the cell surface of the coccolithophorid Pleurochrysis haptonemofera were analyzed. The acidic polysaccharides on the cell surface can be detected by measuring fluorescence of cells after fluorescein-isothiocyanate-labeled lectin staining by flow cytometry. Flow cytometric analyses revealed that the acidic polysaccharides remained on the cell surface even after CaCO3 in the coccolith was dissolved by lowering pH, but they were extracted by subsequent EDTA or EGTA treatment, suggesting that they are bound not into the CaCO3 crystals of the coccolith, but onto the surface via Ca2+. Analyses of the acidic polysaccharides by anion exchange chromatography, colloidal precipitation with divalent cations, and polyacrylamide gel electrophoresis (PAGE) revealed that P. haptonemofera has 3 types of acidic polysaccharides (Ph-PS-l, -2, and -3). The PAGE patterns suggested that Ph-PS-2 has a repeated structure with a broad range of molecular weight, as in Pleurochrysis carterae, while Ph-PS-1 and -3 contain several minor components in addition to a major component, respectively. The minor components in Ph-PS-1 and -3 that have not been found in P. carterae might be characteristic of P. haptonemofera. Analyses of both the cell surface treated by various concentrations of EDTA and EGTA and the extracts suggested that Ph-PS-2, which is distinguishable by a higher affinity to concanavalin A, is bound onto the coccolith surface more intensely than the other two types of acidic polysaccharides.
