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  1. Article ; Online: Author Correction

    Takako Masuda / Keisuke Inomura / Naoto Takahata / Takuhei Shiozaki / Yuji Sano / Curtis Deutsch / Ondřej Prášil / Ken Furuya

    Communications Biology, Vol 6, Iss 1, Pp 1-

    Heterogeneous nitrogen fixation rates confer energetic advantage and expanded ecological niche of unicellular diazotroph populations

    2023  Volume 1

    Keywords Biology (General) ; QH301-705.5
    Language English
    Publishing date 2023-06-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Active nitrogen fixation by Crocosphaera expands their niche despite the presence of ammonium – A case study

    Keisuke Inomura / Takako Masuda / Julia M. Gauglitz

    Scientific Reports, Vol 9, Iss 1, Pp 1-

    2019  Volume 11

    Abstract: Abstract Unicellular nitrogen fixer Crocosphaera contributes substantially to nitrogen fixation in oligotrophic subtropical gyres. They fix nitrogen even when significant amounts of ammonium are available. This has been puzzling since fixing nitrogen is ... ...

    Abstract Abstract Unicellular nitrogen fixer Crocosphaera contributes substantially to nitrogen fixation in oligotrophic subtropical gyres. They fix nitrogen even when significant amounts of ammonium are available. This has been puzzling since fixing nitrogen is energetically inefficient compared with using available ammonium. Here we show that by fixing nitrogen, Crocosphaera can increase their population and expand their niche despite the presence of ammonium. We have developed a simple but mechanistic model of Crocosphaera based on their growth in steady state culture. The model shows that the growth of Crocosphaera can become nitrogen limited despite their capability to fix nitrogen. When they fix nitrogen, the population increases by up to 78% relative to the case without nitrogen fixation. When we simulate a simple ecological situation where Crocosphaera exists with non-nitrogen-fixing phytoplankton, the relative abundance of Crocosphaera increases with nitrogen fixation, while the population of non-nitrogen-fixing phytoplankton decreases since a larger fraction of fixed nitrogen is consumed by Crocosphaera. Our study quantitatively supports the benefit of nitrogen fixation despite the high electron/energy costs, even when an energetically efficient alternative is available. It demonstrates a competitive aspect of Crocosphaera, permitting them to be regionally significant nitrogen fixers.
    Keywords Medicine ; R ; Science ; Q
    Language English
    Publishing date 2019-10-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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    Inter-library loan at ZB MED

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  3. Article ; Online: Impact of Increased Nutrients and Lowered pH on Photosynthesis and Growth of Three Marine Phytoplankton Communities From the Coastal South West Atlantic (Patagonia, Argentina)

    Takako Masuda / Ondřej Prášil / Virginia E. Villafañe / Macarena S. Valiñas / Keisuke Inomura / E. Walter Helbling

    Frontiers in Marine Science, Vol

    2021  Volume 8

    Abstract: Effect of global change variables on the structure and photosynthesis of phytoplankton communities was evaluated in three different sites of the Patagonian coast of Argentina: enclosed bay (Puerto Madryn, PM), estuarine (Playa Unión, PU), and open waters ...

    Abstract Effect of global change variables on the structure and photosynthesis of phytoplankton communities was evaluated in three different sites of the Patagonian coast of Argentina: enclosed bay (Puerto Madryn, PM), estuarine (Playa Unión, PU), and open waters (Isla Escondida, IE). We exposed samples to two contrasting scenarios: Present (nutrients at in situ levels) vs. Future (with lowered pH and higher nutrients inputs), and determined growth and photosynthetic responses after 2 days of acclimation. Under the Future condition phytoplankton growth was higher in the estuarine site compared to those in PM and IE. This effect was the most pronounced on large diatoms. While the increase of photosynthetic activity was not always observed in the Future scenario, the lower photosynthetic electron requirement for carbon fixation (Φe,C = ETR/PmB) in this scenario compared to the Present, suggests a more effective energy utilization. Long-term experiments were also conducted to assess the responses along a 4 days acclimation period in PU. Diatoms benefited from the Future conditions and had significantly higher growth rates than in the Present. In addition, Φe,C was lower after the acclimation period in the Future scenario, compared to the Present. Our results suggest that the availability, frequency and amount of nutrients play a key role when evaluating the effects of global change on natural phytoplankton communities. The observed changes in diatom growth under the Future scenario in PU and IE and photosynthesis may have implications in the local trophodynamics by bottom up control.
    Keywords global change ; plankton community structure ; carbon incorporation ; oxygen production ; PSII photochemistry ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
    Subject code 333
    Language English
    Publishing date 2021-02-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: HPLC Separation of All Aldopentoses and Aldohexoses on an Anion-Exchange Stationary Phase Prepared from Polystyrene-Based Copolymer and Diamine

    Takako Masuda-Hanada / Kadumi Inoue / Sadao Arai / Yoshihiro Aikawa / Kei-ichi Kitahara

    Molecules, Vol 16, Iss 7, Pp 5905-

    The Effect of NaOH Eluent Concentration

    2011  Volume 5915

    Abstract: To investigate the separations of all aldopentoses (ribose, arabinose, xylose and lyxose) and aldohexoses (glucose, galactose, allose, altrose, mannose, gulose, idose and talose) on the D6 stationary phase prepared by the reaction of chloromethylated ... ...

    Abstract To investigate the separations of all aldopentoses (ribose, arabinose, xylose and lyxose) and aldohexoses (glucose, galactose, allose, altrose, mannose, gulose, idose and talose) on the D6 stationary phase prepared by the reaction of chloromethylated styrene-divinylbenzene copolymer and N,N,N’,N’-tetramethyl-1,6-diaminohexane, we examined the effect of varying the concentration of the NaOH eluent on the elution orders. Separations of these aldoses were achieved using a 20 mM NaOH eluent. The elution behaviors of the aldoses were probably due to not only the individual pKa values, but also the chemical structures of the cyclic aldoses.
    Keywords carbohydrate ; aldose ; aldopentose ; aldohexose ; high-performance anion-exchange chromatography ; Organic chemistry ; QD241-441
    Language English
    Publishing date 2011-07-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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    Inter-library loan at ZB MED

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