Genomic basis of evolution of the head of vertebrates

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H03213
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 43050:Genome biology-related
• Research Institution: Konan University
• Principal Investigator: Kusakabe Takehiro 甲南大学, 理工学部, 教授 (40280862)
• Co-Investigator(Kenkyū-buntansha): 鈴木 穣 東京大学, 大学院新領域創成科学研究科, 教授 (40323646) ; 中井 謙太 東京大学, 医科学研究所, 教授 (60217643)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: ホヤ / メダカ / 頭部 / 脳 / 感覚器 / プラコード / グリア / 進化

Outline of Final Research Achievements

Vertebrates have the highly developed head containing a complex and highly organized brain and sensory organs. The tadpole larva of the ascidian, an invertebrate chordate, has a brain with sensory and motor control systems that shares many features with the vertebrate brain, including the retinal/hypothalamic territory, a locomotor central pattern generator, neural crests, and cranial placodes. We elucidated the processes and mechanisms in ascidians from fertilization to cell differentiation of major components of the nervous system such as dopaminergic, sensory, and motor neurons at the single cell level, and clarified the similarities and differences between ascidians and vertebrates. Furthermore, we discovered the activity of glial cells associated with larval movement, the mechanism that forms the early motor rhythm, and the universality of the developmental mechanism of the midline tissues, which play an important role in brain formation, and its evolutionary origin.

Free Research Field

発生生物学、神経生物学

Academic Significance and Societal Importance of the Research Achievements

脊椎動物に近縁なホヤ類の幼生は、微小だが脊椎動物と相同な中枢神経系（脳、脊髄）と感覚器をもつ。本研究では、ホヤと脊椎動物の間で中枢神経系や感覚器の発生過程と遺伝子発現の比較解析を行い、脊椎動物の発達した頭部が進化した背景を探った。ホヤの特徴を生かして、受精卵からドーパミン神経、感覚神経、運動神経回路などができる過程を明らかにし、脊椎動物との発生機構の共通性を見出すとともに、新たな現象を見出した。本研究の成果は、脊椎動物の発達した頭部の起源や成り立ち、脳機能の形成と制御機構を解明するための足がかりになると期待される。