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非ランダム変異率の証拠は,進化的なリスク管理戦略を示唆しています
Iñigo Martincorena1, Aswin S N Seshasayee, Nicholas M Luscombe
1EMBL-European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SD, UK. martinco@ebi.ac.uk
Nature
|April 24, 2012
まとめ
バクテリアのゲノム全体で突然変異率は大きく異なるが,高度に発現している遺伝子は突然変異が少ない. これは,有害な遺伝的変化を最小限に抑えるための進化的最適化を示唆しています.
科学分野:
- 進化生物学の進化生物学について
- 遺伝学 遺伝学とは
- 分子生物学は分子生物学である.
背景:
- 進化論の中心的な原則は,ランダムな突然変異を仮定し,その運命を決定する選択である.
- 理論的なモデルは,選択が突然変異率に影響を与える可能性があることを示唆していますが,測定上の課題のため,経験的証拠は限られています.
- ゲノム全体の突然変異率の変動を理解することは,進化論の研究にとって極めて重要です.
研究 の 目的:
- 異なるゲノムサイトにおける中性変異率の変動を調査する.
- 遺伝子発現レベルと選択によって突然変異率の変動が影響されているかどうかを判断する.
- 進化的圧力への反応として突然変異率を調節する新しいメカニズムを探求する.
主な方法:
- 34 Escherichia coli のゲノムを比較したゲノミクス分析.
- 系統遺伝学と集団遺伝学の技術を統合する.
- 何千もの遺伝子における中性変異率の定量化.
主要な成果:
- 2,659の遺伝子の間では,数値を上回る突然変異率の変動が観察されました.
- 数キロベースに及ぶ突然変異の"熱い"と"冷たい"スポットが特定されました.
- 高度に発現する遺伝子や強い浄化選択を受けている遺伝子において,著しく低い突然変異率を検出した.
結論:
- 変異率の変動は非ランダムで,有害な変異を減らすために進化的に最適化されているように見える.
- 変異率調節の既存のモデル (例えば,転写結合修復) は,観察されたパターンを完全に説明できません.
- 新しいメカニズムは,観察された突然変異率の調節に寄与し,進化の軌道を影響する可能性がある.
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