Origins and Evolution of Chordates: Studies of Comparative Genomics and Evolutionary Developmental Biology

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04824
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Evolutionary biology
• Research Institution: Okinawa Institute of Science and Technology Graduate University
• Principal Investigator: SATOH NORIYUKI 沖縄科学技術大学院大学, マリンゲノミックスユニット, 教授 (30025481)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 脊索動物の起源と進化 / 脊索 / 体節 / 遺伝子重複 / セルロース合成遺伝子 / 水平伝播

Outline of Final Research Achievements

In order to understand the origin and evolution of chordates, comparative analyses of orthologous genes that are involved in the formation of fish-like larvae are essential. In this study, we developed a new web tool named "ORTHOSCOPE". Taking advantage of this tool, the present study has explored following things. (a) Fish-like larvae develop somite muscle, which is not found in non-chordate deuterostomes. The ORTHOSCOPE analysis indicated that duplications of genes that encode actin or myosin heavy-chain resulted in the formation of muscle-type protein genes, which are involved in chordate-type muscle formation. (b) Tunicates are only animal group that can synthesize cellulose by themselves. The ORTHOSCOPE analysis indicated that CesA (cellulose synthase genes) are only found in tunicate genomes but not in other animal genomes. This strongly suggests that horizontal gene transfer of CesA occurred in the ancestor of tunicates and allowed tunicates to evolve as a specific group.

Free Research Field

動物比較ゲノム科学

Academic Significance and Societal Importance of the Research Achievements

脊索動物の起源と進化の問題に対して、比較ゲノム科学的にチャレンジした。そのための前提として、脊索動物およびその近縁の棘皮動物・半索動物のゲノムを解読する必要があり、それらを解読した上でこの研究に臨んでいるところに本研究の大きな特徴がある。そして遺伝子の比較を容易にするために、まずORTHOSCOPEというウエッブ・ツールを開発した。そしてこの方法によって、脊索動物を特徴付ける脊索や筋肉がどのように生まれたのかの遺伝子的基盤を明らかにした。また、これまで亜門とされてきた脊索動物の３群、頭索動物、尾索動物、脊椎動物を門として提唱するという段階にまで至ったことの学術的意義は大きい。