Genome analysis of symbiotic cyanobacteria seen in pelagic dinoflagellates

• Project/Area Number: 17K15164
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Evolutionary biology
• Research Institution: Tohoku University
• Principal Investigator: Nakayama Takuro 東北大学, 生命科学研究科, 助教 (70583508)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2019: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2017: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
• Keywords: シアノバクテリア / 渦鞭毛藻 / 共生 / メタゲノム / 進化 / 細胞共生 / 微生物生態 / 共生進化 / 比較ゲノム / 微細藻類 / 細胞共生進化 / オルカネラ起源

Outline of Final Research Achievements

Pelagic species of Dinophysiales dinoflagellates are known to host symbiotic cyanobacteria. In this study, in order to know the properties of cyanobacteria in symbiosis with those pelagic dinoflagellate, we analyzed the genomes of cyanobacterial symbionts of two Dinophysialse dinoflagellates, Ornithocercus magnificus and Histioneis depressa. Our analysis revealed that the two symbionts differ in their metabolic abilities (e.g., nitrogen-fixing capacity) and in their symbiotic status in the natural environments, suggesting that symbiotic cyanobacteria of dinoflagellates have diversity in their metabolic roles and the strength of their symbiotic relationships with the dinoflagellate hosts.

Academic Significance and Societal Importance of the Research Achievements

シアノバクテリアは海洋における重要な一次生産者の一つである。これまでその多様性や生態学的な特徴を把握するため数々の網羅的な解析が行われてきた。一方で本研究で明らかとなった渦鞭毛藻共生性シアノバクテリアは、これまでの海洋シアノバクテリアの多様性解析では認識されてこなかった系統であった。解析の結果を踏まえると、これまでの海洋シアノバクテリアの多様性解析は、本研究で対象としたような真核生物に共生するシアノバクテリアを見逃していた可能性がある。この知見は海洋におけるシアノバクテリアの生態および多様性をより正確に把握するために重要であると考えられる。

Research Products

• [Journal Article] Dinoflagellates with relic endosymbiont nuclei as models for elucidating organellogenesis (2020)
  • Author(s): Chihiro Sarai, Goro Tanifuji, Takuro Nakayama, Ryoma Kamikawa, Kazuo Takahashi, Euki Yazaki, Eriko Matsuo, Ken-ichiro Ishida, Mitsuhisa Iwataki, Yuji Inagaki
  • Journal Title: Proceedings of the National Academy of Sciences of the United States of America Volume: 117 Issue: 10 Pages: 5364-5375
  • DOI: 10.1073/pnas.1911884117
  • Peer Reviewed / Open Access
• [Journal Article] Single-cell genomics unveiled a cryptic cyanobacterial lineage with a worldwide distribution hidden by a dinoflagellate host (2019)
  • Author(s): Takuro Nakayama, Mami Nomura, Yoshihito Takano, Goro Tanifuji, Kogiku Shiba, Kazuo Inaba, Yuji Inagaki, Masakado Kawata
  • Journal Title: Proceedings of the National Academy of Sciences of the United States of America Volume: 116 Issue: 32 Pages: 15973-15978
  • DOI: 10.1073/pnas.1902538116
  • Peer Reviewed / Open Access
• [Presentation] Genome analysis of a symbiotic nitrogen-fixing cyanobacterium in a pelagic dinoflagellate, Histioneis depressa. (2019)
  • Author(s): Nakayama T, Takano Y, Nomura M, Shiba K, Inaba K, Tanifuji G, Inagaki Y, Kawata M
  • Organizer: XXII Meeting of the International Society of Evolutionary Protistology
  • Int'l Joint Research
• [Presentation] Genome analysis of a symbiotic cyanobacterium in a dinophysialean dinoflagellate, Ornithocercus magnificus (2018)
  • Author(s): Takuro Nakayama, Yoshihito Takano, Mami Nomura, Kogiku Shiba, Kazuo Inaba, Goro Tanifuji, Yuji Inagaki, Masakado Kawata
  • Organizer: XXII Meeting of the International Society of Evolutionary Protistology
  • Int'l Joint Research
• [Presentation] 外洋性渦鞭毛藻Ornithocercus magnificusに見られる共生シアノバクテリアのゲノム解析 (2018)
  • Author(s): 中山卓郎, 高野義人, 野村真未, 柴小菊, 稲葉一男, 谷藤吾朗, 河田雅圭, 稲垣祐司
  • Organizer: 日本藻類学会第42回大会