高変異率のコストと利益:マウスの腸内細菌の適応的進化

A Giraud¹, I Matic, O Tenaillon

¹E9916, Institut National de la Santé et de la Recherche Médicale, Faculté de Médicine "Necker Enfants Malades," Université René Descartes-Paris V, 156 Rue de Vaugirard, 75015 Paris, France.

Science (New York, N.Y.)

|April 3, 2001

まとめ

バクテリアの突然変異率は,腸の植民地化中に変化します. 高変異率は初期適応を助長するが,長期的に不利な影響を及ぼし,自然界におけるその流行を説明する.

科学分野:

微生物遺伝学微生物遺伝学
進化生物学の進化生物学について
マイクロバイオームの研究

背景:

バクテリアの突然変異率は,様々です.
高変異率の適応的意義は完全に理解されていません.
変異細菌を理解することは,微生物の進化の鍵です.

研究の目的:

ホストの植民地化中に細菌の変異率がどのように変化するかを調査する.
高変異率の適応的メリットとデメリットを in vivo で決定する.
変異細菌の生態学的持続性を説明するために.

主な方法:

マウスの腸を細菌で実験的に植え付けました.
バクテリアの変異率を時間とともに監視する.
主要・次要環境における細菌の競争力の評価.

主要な成果:

細菌の変異率は,マウスの腸の植民地化中に変化することが観察されました.
当初,高い突然変異率は,適応上の優位性をもたらした.
この利点は適応後に減少し,突然変異は新しい環境で有害であることが判明した.
変異した細菌は,新しい宿主への感染時に競争力が低下したことを示した.

結論:

高変異率は,適応に短期的な利点をもたらしますが,長期的なリスクを伴います.
蓄積された突然変異は,異なる生態学的ニッチで有害である可能性があります.
短期的利益と長期的コストのバランスは,自然集団における変異性細菌の頻度に影響を与える.

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