Study of ultra structure during embryogenesis in lampreys

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K06787
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 45020:Evolutionary biology-related
• Research Institution: University of Fukui
• Principal Investigator: Onai Takayuki 福井大学, 学術研究院医学系部門, 助教 (20617279)
• Co-Investigator(Kenkyū-buntansha): 菅原 文昭 兵庫医科大学, 医学部, 准教授 (00611005)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 脊椎動物 / 中胚葉 / 分節性 / ナメクジウオ / ギボシムシ / ロゼッタ / 体節

Outline of Final Research Achievements

How vertebrate heads evolved from their ancestors is a mystery. One hypothesis has been that the somites of amphioxus were present in the heads of vertebrates. Recent molecular embryological studies challenge this hypothesis. However, lack of embryological knowledge of the lamprey has prevented any conclusions. Using laser scanning microscopy and scanning electron microscopy serial section analysis (SBF-SEM), we found that the lamprey head mesoderm contains several distinct cell populations. These cells did not have a rosette pattern like somites and were not genetically related to the formation of body segments. This suggests that vertebrate heads were new and diversified during early evolution.

Free Research Field

進化発生学

Academic Significance and Societal Importance of the Research Achievements

本研究では、これまで比較形態学の分野で最大の謎であった、頭部分節性問題の根幹に迫った。円口類ヤツメウナギの頭部の組織学的解析は1902年以降行われていなかった。そこで我々は、最先端の技術を導入し、この研究を進めた。その結果、これまで言われていた様な頭部に体節は存在しないとを証明した。さらにユニークな細胞集団を複数見つけたことで、脊椎動物の初期進化がこれまで以上に多様性に富んでいたことを明らかにした。