When and how does medaka juveniles develop schooling behavior?

• Project/Area Number: 18K05833
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40040:Aquatic life science-related
• Research Institution: Kindai University
• Principal Investigator: KAGAWA Nao 近畿大学, 理工学部, 准教授 (80351568)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2020: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2018: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: 社会性の発現 / 群れ形成行動 / 成長 / 神経ペプチド / メダカ / 群れ行動 / 社会性行動

Outline of Final Research Achievements

Here, we determined when medaka juveniles display schooling behavior during the developmental stages after hatching. We also studied whether social isolated juvenile changes schooling behavior and whether social isolation affects the expression of neuropeptide hormone (AVT).
Juveniles exhibited schooling behavior at 2 weeks post-hatch (wph). After then, schooling behavior was increased until 8 wph. AVT expression was increased at 2 wph, and then, an increase of AVT expression was found until 12 wph. Schooling behavior in a juvenile isolated from 1 wph to 2 wph was decreased when isolated fish was introduced to grouped conspecifics. In isolated fish, AVT expression was slightly decreased. In the Avt gene knock-out medaka, the juveniles did not exhibit schooling behavior at 2 wph.
This study indicates that social interaction among juveniles is necessary for behavioral development in medaka fish. It also suggests that AVT are associated with behavioral development.

Academic Significance and Societal Importance of the Research Achievements

動物の発育に伴う社会性行動の発達に関する研究は、哺乳類では多いが、魚類では未だ充分ではない。本研究で得られた成果は、魚類において、１）発生の早い段階で社会性行動が発達すること、２）複数個体と発育することが社会性行動の発達に重要であること、３）神経ペプチドであるAVTが発育に伴う社会性行動の発現・発達に関与すること、などを明らかにしたものであり、学術的に有意義な成果と考える。
さらに、本研究で得られた成果は、水産有用種の適切な飼育条件検討等に有用な基礎的知見を提供しうるものであり、水産増養殖への貢献という点において社会的意義のある成果と考える。

Research Products

• [Journal Article] Physiological changes in response to social isolation in male medaka fish (2020)
  • Author(s): Airi Otsuka, Moeko Inahata, Yuki Shimomura, Nao Kagawa
  • Journal Title: Fisheries Science Volume: 86 Pages: 775-781
  • NAID: 40022347398
  • Peer Reviewed
• [Journal Article] Immediate early gene expression in brain regions associated with the social behavioral network after male competition in medaka fish (2020)
  • Author(s): Airi Otsuka, Chihomi Nomura, Kensuke Miura, Akira Honda, Nao Kagawa
  • Journal Title: Zoological Science Volume: 37 Pages: 391-398
  • NAID: 210000188061
  • Peer Reviewed
• [Journal Article] The presence of a conspecific induces risk‐taking behaviour and enlargement of somata size of dopaminergic neurons in the brain of male medaka fish (2020)
  • Author(s): Otsuka Airi、Shimomura Kenta、Niwa Haruka、Kagawa Nao
  • Journal Title: Journal of Fish Biology Volume: - Issue: 4 Pages: 1014-1023
  • DOI: 10.1111/jfb.14293
  • Peer Reviewed
• [Journal Article] Reduction of tryptophan hydroxylase expression in the brain of medaka fish after repeated heat stress (2019)
  • Author(s): Yuki Shimomura, Moeko Inahata, Mai Komori, Nao Kagawa
  • Journal Title: Zoological Science Volume: 印刷中 Issue: 3 Pages: 223-223
  • DOI: 10.2108/zs180135
  • NAID: 40021920313
  • Peer Reviewed
• [Presentation] メダカ稚魚の発育に伴う社会性行動と脳内vasotocin発現の変化 (2020)
  • Author(s): 加川 尚
  • Organizer: 日本水産学会
• [Presentation] d-rRメダカの明暗選好性を利用した不安様行動試験 (2019)
  • Author(s): 加川 尚
  • Organizer: 日本魚類学会
• [Presentation] 魚類の闘争行動の調節における神経ペプチドの役割 (2018)
  • Author(s): 加川 尚
  • Organizer: 2018年度日本魚類学会50周年記念シンポジウム
  • Invited
• [Book] 魚類学の百科事典 (2018)
  • Author(s): 一般社団法人日本魚類学会 編
  • Total Pages: 756
  • Publisher: 丸善出版
  • ISBN: 9784621303177