祖先の脊椎動物の脳の複雑な地域化に関するサイクロストームからの証拠
Fumiaki Sugahara1,2, Juan Pascual-Anaya1, Yasuhiro Oisi3
1Evolutionary Morphology Laboratory, RIKEN, Kobe 650-0047, Japan.
Nature
|February 16, 2016
まとめ
脊椎動物 の 脳
科学分野:
- 進化的発達生物学
- 神経科学
- 比較ゲノミクス
背景:
- 複雑な脊椎動物の脳の進化的起源はよく理解されていません.
- ランプリの胚性脳は 欠落した発達の遺伝子発現領域が原因で 祖先の状態を表していると考えられていた.
- エッジホッグとNkx2.1ドメインの欠如は,中枢のギャングリオン突起の喪失と関連していた.
研究 の 目的:
- 脊椎動物における脳の地域化の進化史を調査する
- 早期の脊椎動物の系統に 重要な脳の発達領域が保存されているかどうかを判断する.
- 脊椎動物の脳を再評価する
主な方法:
- ハグフィッシュとランプリの胚性脳の発達を比較した分析
- サイクロストームの脳の遺伝子発現パターンの分析
- 脳構造の組織学的な検査
主要な成果:
- ハグフィッシュの脳は,グナトストームに似た,中央のギャングリオン突起とロムビックリップに相当する領域を示しています.
- ランプレイの幼虫は以前は欠けていたと考えられていた 発達領域を持っています
- これらの発見は 脳の地域化パターンが 保存されていることを示唆しています
結論:
- 主要な脳地域化の特徴は,グナトストームに特有するものではありません.
- ハグフィッシュとランプリの脳の発達領域は 古代の起源を示しています
- 複雑な脳地域化は 5億年以上前のサイクロストームとグナトストームの分断に先立ちます
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