動物生理学 動物生理学 バンブーを食べる巨大パンダの日々のエネルギー消費量は例外的に低い
Yonggang Nie1, John R Speakman2, Qi Wu1
1Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
まとめ
巨大なパンダは,ユニークな適応により,非常に低いエネルギー消費量を持っています. これには,より小さな臓器,活動低下,甲状腺ホルモンのレベルが低下し,竹の食生活で生存することが含まれます.
科学分野:
- 動物学 動物学
- 比較生理学 比較生理学とは
- 遺伝学 遺伝学とは
背景:
- 巨大パンダ (Ailuropoda melanoleuca) は,消化器系がうまく適応していないにもかかわらず,竹の特化した食生活を営んでいます.
- この食事の専門化は生理学的課題であり,エネルギー保存のためのユニークな適応が必要である.
研究 の 目的:
- 巨大パンダの低エネルギー消費の背後にある生理学的および遺伝的メカニズムを調査する.
- これらの適応が栄養価が低い竹の食生活で生存を可能にする方法を決定する.
主な方法:
- 飼育されているパンダと野生のパンダの計測された日々のエネルギー消費量 (DEE).
- 同じサイズの哺乳類の予測値とDEEを比較した.
- 臓器のサイズ,身体活動のレベル,および循環中の甲状腺ホルモン濃度 (T4およびT3) を評価した.
- 甲状腺ホルモンの合成に潜在的に影響する突然変異のためにDUOX2遺伝子を分析しました.
主要な成果:
- 巨大パンダは,他の哺乳類と比較してDEE (平均5.2MJ/日,予測の37.7%) が著しく低かった.
- 野生のパンダもDEEの減少を示した (6.2MJ/日,予想の45%).
- 重要な臓器のサイズが小さくなり,身体活動が少なくなり,チロキシン (T4) とトリヨドチロニン (T3) の循環レベルが著しく低下することが観察されました.
- DUOX2遺伝子のユニークな突然変異が特定され,低甲状腺ホルモンレベルを説明する可能性がある.
結論:
- 巨大パンダは,形態学,行動学,生理学,遺伝学的な適応を重ねて,エネルギー消費を大幅に削減しています.
- 甲状腺ホルモンに影響を与えるユニークなDUOX2変異を含むこれらの適応は,竹ベースの食事で生存するために不可欠です.
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