New approach for time encoding mechanisms by the brain

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K22425
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 44:Biology at cellular to organismal levels, and related fields
• Research Institution: Osaka University
• Principal Investigator: Shiga Sakiko 大阪大学, 理学研究科, 教授 (90254383)
• Co-Investigator(Kenkyū-buntansha): 濱中 良隆 大阪大学, 理学研究科, 助教 (10647572) ; 長谷部 政治 大阪大学, 理学研究科, 助教 (40802822)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Keywords: 二日リズム / 光周性 / Holotrichia parallela / Salcophaga similis / Drosophila melanogaster

Outline of Final Research Achievements

We hypothesized that a circadian clock mechanism is involved in the day counting shared by photoperiodism and circa’bi’dian rhythm in insects. We anatomically identified clock cells and their network in the brain of Sarcophaga similis (photoperoidism) and Holotrichia parallela (circabidian rhythm). The encoding of day-length information for 3 days in Drosophila melanogaster and the circabidian rhythm in H. parallela are suggested commonly to involve clock cells located in the lateral part of the brain. Oscillations of clock gene expression in the brain showed a possibility that mechanisms of the two-day counting may involve certain types of clock genes in H. parallela. Based on these, we will be able to explore the molecular and cellular mechanisms of time encoding involved in day counting in the future.

Free Research Field

神経生物学、時間生物学

Academic Significance and Societal Importance of the Research Achievements

生物は、細胞、組織、個体、社会いずれの階層においても「時間」と言う尺度を用い、総体として活動の調和を取っている。しかし、数日やそれ以上の長い時間を脳で符号化する具体的なメカニズムはわかっていない。本研究では、数日間の日長情報や二日リズムの形成に時計細胞が関わる可能性を示した。これは、今後、数日という時間が脳で符号化され、時間を認知するメカニズムの解明につながり得る。