Origin of establishment of symbiotic relationship between radiolarians and the symbionts and evolution of the shell components based on the molecular phylogeny and the ultrastructural observations.

• Project/Area Number: 15K05326
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Stratigraphy/Paleontology
• Research Institution: Tokyo Gakugei University
• Principal Investigator: TAKAHASHI Osamu 東京学芸大学, 教育学部, 准教授 (20242232)
• Co-Investigator(Renkei-kenkyūsha): MAYAMA Shigeki 東京学芸大学, 教育学部, 教授 (40199914) ; MATSUOKA Atsushi 新潟大学, 理学部, 教授 (00183947) ; TAKEMURA Akihiro 琉球大学, 理学部, 教授 (40222103)
• Research Collaborator: Bjørklund K. R. オスロ大学
• Project Period (FY): 2015-04-01 – 2018-03-31
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000); Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2015: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
• Keywords: 放散虫 / 共生 / 系統解析 / 渦鞭毛藻 / ハプト藻 / 緑藻 / 遊走子 / リプロダクション / シアノバクテリア / 分子系統 / 共生藻 / ポリキスティネア / アカンサリア / 硫酸ストロンチウム

Outline of Final Research Achievements

SEM, TEM and molecular phylogenetic analysis were carried out confirming the reproductive stages of some polycystines and acantharean radiolarian species. We concluded that the radiolarian swarmer size is several micrometers. Those are smaller than the size of their symbiotic algae and it is impossible to get the symbiotic algae in the sexual reproduction. In addition, at least four kinds of symbionts, haptophyte, dinoflagellates, green algae and cyanobacteria have been confirmed in radiolarians, and this time we described Gymnoxantella radiolariae as a new species of dinoflagellate in symbiosis with radiolarians. It suggests that radiolarians are selected out from the environment after being adulted and acquire symbionts in situ in the same area.

Research Products

• [Int'l Joint Research] オスロ大学(ノルウェー)
• [Int'l Joint Research] オスロ大学(ノルウェー)
• [Int'l Joint Research] オスロ大学(ノルウェー)
• [Journal Article] Light and electron microscopic observations of the reproductive swarmer cells of nassellarian and spumellarian polycystines (Radiolaria) (2016)
  • Author(s): Tomoko Yuasa, Osamu Takahashi
  • Journal Title: European Journal of Protistology Volume: 54 Pages: 19-32
  • DOI: 10.1016/j.ejop.2016.02.007
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] GYMNOXANTHELLA RADIOLARIAE GEN. ET SP. NOV. (DINOPHYCEAE), A DINOFLAGELLATE SYMBIONT FROM SOLITARY POLYCYSTINE RADIOLARIANS (2016)
  • Author(s): T. Yuasa, T. Horiguchi, S. Mayama, O. Takahashi
  • Journal Title: Journal of Phycology Volume: 52 Issue: 1 Pages: 89-104
  • DOI: 10.1111/jpy.12371
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Presentation] Observations of the reproductive swarmer cells of polycystine and acantharian radiolarians in the east China Sea. (2017)
  • Author(s): Tomoko YUASA and Osamu TAKAHASHI
  • Organizer: InterRad XV
  • Int'l Joint Research