Symbiosis and Cell Evolution Laboratory

Miyagishima Group

Evolutionary integration of two independent organisms by endosymbioses

Faculty

MIYAGISHIMA, Shin-ya
Professor

smiyagis@nig.ac.jp

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FUJIWARA, Takayuki
Assistant Professor

tkfujiwara@nig.ac.jp

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HIROOKA, Shunsuke
Project Assistant Professor

shirooka@nig.ac.jp

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Lab HP

Research Summary

Mitochondria and chloroplasts, energy-converting organ-elles in eukaryotic cells, are relicts of ancient bacterial endosym-bionts. In addition to these particular organelles, there are many other endosymbiotic events which have integrated new functions into eukaryotic host cells. In order to maintain a permanent en-dosymbiotic relationship, a host cell and an endosymbiotic cell coordinate their proliferation. The major goal of our study is to understand how organelle (or other endosymbiotic cell) division is controlled by host cells and how host cells proliferate depend-ing on chemical energy that are supplied by organelles (or otherendosymbiotic cells).

Reminiscent of their cyanobacterial(A) ancestor, chloroplasts replicate by binary division (B, unicellular alga; C, land plant cells). Chloroplast division is performed by the division ring (D) which involves cyanobacterial FtsZ and eukaryotic dynamin (E).

Selected Publications

  • 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. Sexual life cycle establishes the unicellular red algae Cyanidiophyceae as a genetically tractable model lineage for eukaryotic evolution. Plant Cell. 2026;in press.
  • Okada K, Fujiwara T, Hirooka S, Kobayashi Y, Onuma R, Miyagishima SY. The closed nutrient recycling system in the Paramecium-Chlorella photosymbiosis contributes to survival under oligotrophic conditions. Sci Adv. 2025 Oct 31;11(44):eadz0004.
  • Miyagishima SY. Taming the perils of photosynthesis by eukaryotes: constraints on endosymbiotic evolution in aquatic ecosystems. Commun Biol. 2023 Nov 11;6(1):1150.
  • Hirooka S, Itabashi T, Ichinose TM, Onuma R, Fujiwara T, Yamashita S, Jong LW, Tomita R, Iwane AH, Miyagishima SY. Life cycle and functional genomics of the unicellular red alga Galdieria for elucidating algal and plant evolution and industrial use. Proc Natl Acad Sci U S A. 2022 Oct 11;119(41):e2210665119.