Yagisawa Fumi

写真a

Title

Associate Professor

Researcher Number(JSPS Kakenhi)

70757658
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Current Affiliation Organization 【 display / non-display 】

  • Concurrently   University of the Ryukyus   Graduate School of Engineering and Science   Chemistry, Biology and Marine Science   Associate Professor  

  • Duty   University of the Ryukyus   Research Facility Center   Associate Professor  

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External Career 【 display / non-display 】

  • 2015.04
    　
    　

    University of the Ryukyus, Instrumental Research Center, Associate Professor  

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Research Areas 【 display / non-display 】

  • Life Science / Cell biology

  • Life Science / Morphology and anatomical structure

  • Life Science / Evolutionary biology

  • Life Science / Plant molecular biology and physiology

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Published Papers 【 display / non-display 】

  • Sexual life cycle establishes the unicellular red algae Cyanidiophyceae as a genetically tractable model for eukaryotic evolution.

    Hirooka S, Fujiwara T, Seger M, Inagaki S, Yamashita S, Tsujino D, Onuma R, Kanesaki Y, Watanabe S, Hirose Y, Ohbayashi R, Takusagawa M, Zhou B, Tomita R, Yagisawa F, Lammers P, Iwane AH, Miyagishima SY

    The Plant cell   38 ( 7 )   2026.06 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

  • A high-yield protein expression platform in the unicellular red alga Cyanidioschyzon merolae.

    Mogi Y, Tsushima S, Nagai S, Gima S, Yagisawa F, Yoshida Y

    Journal of cell science   139 ( 4 )   2026.01 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

    　View Summary

    The production of engineered proteins in transgenic cells is widely used in research, medicine and industry. However, conventional cell-based production systems still face challenges in cost, scalability and biosafety. Here, we present a recombinant protein expression platform with simplified purification based on the photosynthetic unicellular red alga Cyanidioschyzon merolae, which can be cultivated under highly acidic conditions using only inorganic nutrients, air, water and light. We first identified a promoter that drives high-level constitutive gene expression throughout the cell cycle, resulting in substantial mRNA accumulation in C. merolae. A stable transformant expressing His-tagged mVenus under the control of this promoter accumulated the recombinant protein to more than 1% of total soluble protein. The simple cellular architecture of C. merolae, including the absence of a cell wall, enables efficient protein extraction via a single freeze-thaw cycle, followed by purification using immobilized metal affinity chromatography (IMAC), yielding ∼13.9 mg of functional recombinant protein per gram of total soluble protein. Owing to its low cost, scalability, operational simplicity and minimal risk of contamination, this Cyanidioschyzon-based platform offers a practical and promising approach to recombinant protein production in a photosynthetic eukaryote.

  • Temperature-dependent photostasis and nitrogen limitation in streamlined-genome red algae Cyanidiophyceae from natural habitats.

    Tsujino D, Fujiwara T, Yamashita S, Tamashiro K, Izumi J, Yagisawa F, Zhou B, Hirooka S, Sunada Y, Sonoike K, Miyagishima SY

    The ISME journal ( Oxford University Press (OUP) )  20 ( 1 )   2026.01 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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    Abstract Photosynthetic microorganisms must continuously balance light energy absorption with metabolic demand to maintain photostasis under fluctuating environments. Cyanidiophyceae, unicellular red algae from acidic hot springs with highly streamlined genomes (9–18 Mb), nevertheless thrive across a wide temperature range (20–56°C), posing the question of how such minimalist eukaryotic cells sustain photostasis in nature. Here, we combined field observations of natural mats in sulfuric hot springs in Japan with laboratory experiments under habitat-mimicking conditions. Spring-water chemistry remained nearly constant year-round, characterized by low nitrogen availability (<30 μM), whereas temperature varied spatially and seasonally. Growth increased with temperature (up to 47°C) and nearly ceased at 20–25°C, yet photosynthetic pigment levels and apparatus components remained largely unchanged, indicating sustained light absorption even under conditions of minimal growth. At low temperatures, photosystem efficiency and regulated energy dissipation decreased, whereas non-regulated dissipation and reactive oxygen species (ROS) increased, indicating excess excitation energy was mainly dissipated through non-regulated pathways. Proteomic and transcriptomic analyses showed accumulation of ROS scavengers and chromosome maintenance/repair proteins at low temperature, suggesting that excess reducing power/ATP, even after partial energy dissipation, was redirected toward stress mitigation rather than growth. At higher temperatures, nitrogen-deficiency responses emerged, reflecting nitrogen limitation relative to elevated demand for rapid growth. Together, these results reveal a temperature-dependent trade-off in Cyanidiophyceae in natural habitats: oxidative stress at low temperature versus nitrogen limitation at high temperature. Overall, our findings highlight a simple yet robust photostasis strategy and provide environmental and omics resources for studies of this model lineage.

  • Sexual life cycle establishes the unicellular red algae Cyanidiophyceae as a genetically tractable model lineage for eukaryotic evolution

    Shunsuke Hirooka, Takayuki Fujiwara, Mark Seger, Soichi Inagaki, Shota Yamashita, Dai Tsujino, Ryo Onuma, Yu Kanesaki, Satoru Watanabe, Yuu Hirose, Ryudo Ohbayashi, Mari Takusagawa, Baifeng Zhou, Reiko Tomita, Fumi Yagisawa, Peter Lammers, Atsuko H. Iwane, Shin-ya Miyagishima

    ( Cold Spring Harbor Laboratory )    2025.10 [ Peer Review Accepted ]

    Type of publication: Research paper (other science council materials etc.)

    　View Summary

    Abstract The thermo-acidophilic unicellular algal class Cyanidiophyceae is the earliest-branching lineage in red algae, which diverged from Viridiplantae lineage (green algae and land plants) soon after chloroplast establishment in the common ancestor of Archaeplastida. Cyanidiophyceae possess extremely simple genomes (8.7–17.8 Mb; approximately 4,800– 7,800 genes), and the cell-wall-less, genetically tractable strain Cyanidioschyzon merolae 10D has served as a model organism. However, its unknown sexual life cycle has limited its utility in studies of evolution and genetics. Inspired by the recent discovery of sexual reproduction in the cyanidiophycean genus Galdieria, we identified similar life cycles in the other cyanidiophycean genera Cyanidioschyzon, Cyanidiococcus, and Cyanidium. In these genera, the cell-walled diploid form, exclusively observed in nature, produces a cell-wall-less haploid form when the culture pH is lowered, and both proliferate asexually. In addition, the cell-wall-less Cyanidioschyzon merolae 10D strain has been shown to be a haploid clone that forms a cell-walled diploid through mating with other haploid clones. Building on these findings, we generated high-quality genomic resources with phase-specific transcriptomes and developed genetic manipulation systems using the cell-wall-less haploids of these genera. We further uncovered phase-specific distribution of histone H3 lysine 27 trimethylation linked to haploid- and diploid-specific gene expression, including transcription factors involved in differentiation associated with sexual reproduction in plants. Additionally, biparental inheritance of organelle DNA occurs following isogamous mating of haploid cells but resolves into uniparental inheritance during diploid proliferation. These advances position Cyanidiophyceae as a powerful model lineage for studying early Archaeplastida evolution, the shared mechanisms of photosynthetic eukaryotes, and their environmental adaptation.

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      DOI Open Access

  • Costs of photosynthesis and cellular remodeling in trophic transitions of the unicellular red alga Galdieria partita.

    Yamashita S, Hirooka S, Fujiwara T, Zhou B, Yagisawa F, Tamashiro K, Murakami H, Awai K, Miyagishima SY

    Communications biology   8 ( 1 ) 891   2025.06 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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Books 【 display / non-display 】

  • Cyanidioschyzon merolae: A New Model Eukaryote for Cell and Organelle Biology

    Yagisawa F, Imoto Y, Fujiwara T, Miyagishima S ( Part: Multiple Authorship ,  16. Single-Membrane-Bound organelles: Division and Inheritance )

    Springer  2018.02

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Other Papers 【 display / non-display 】

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Grant-in-Aid for Scientific Research 【 display / non-display 】

  • Grant-in-Aid for Scientific Research(C)

    Project Year: 2025.04  -  2028.03 

    Direct: 3,600,000 (YEN)  Overheads: 4,680,000 (YEN)  Total: 1,080,000 (YEN)

  • Grant-in-Aid for Scientific Research(C)

    Project Year: 2022.04  -  2025.03 

    Direct: 3,200,000 (YEN)  Overheads: 960,000 (YEN) 

  • Elucidating the basis of plant cells based on the organelle division mechanism of microalgae

    Grant-in-Aid for Scientific Research(B)

    Project Year: 2022.04  -  2025.03 

    Direct: 13,600,000 (YEN)  Overheads: 17,680,000 (YEN)  Total: 4,080,000 (YEN)

  • Grant-in-Aid for Scientific Research(C)

    Project Year: 2022.04  -  2025.03 

    Direct: 3,200,000 (YEN)  Overheads: 4,160,000 (YEN)  Total: 960,000 (YEN)

  • Elucidating the basis of plant cells based on the organelle division mechanism of microalgae

    Grant-in-Aid for Scientific Research(B)

    Project Year: 2019.04  -  2022.03 

    Investigator(s): KUROIWA Tsuneyoshi 

    Direct: 13,100,000 (YEN)  Overheads: 17,030,000 (YEN)  Total: 3,930,000 (YEN)

    　View Summary

    Dynamics of organelle division / proliferation, etc. in eukaryotic cell proliferation, and the mechanism that leads the information to the cell nucleus and cytokinesis was studied using the primitive red alga C. merolae as a material. Each organelle divides sequentially using a division device, and each division. The constituents of the device were confirmed. It was revealed that TOP (kinesin-like substance) acts on the distribution of divided organelles and then is involved in cell fission. Subsequently, the cell membrane contractile substance (EF1α) functioned, and then molecules involved in central cell membrane disruption (ESCRT-III, ALIX, VPS4, etc.) appeared and divided. ESCR-III was presumed to form a complex with an "electron-dense ring" and cause final fragmentation, and similar rings were also observed in Medakamo. In addition, a metaphase chromosomal structure was confirmed in Schyzon.

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