エシェリキア・コライにおけるクローン分岐は,突然変異ではなく再結合の結果である

D S Guttman¹, D E Dykhuizen

¹Department of Ecology and Evolution, State University of New York, Stony Brook 11794.

Science (New York, N.Y.)

|November 25, 1994

まとめ

変異ではなく再結合が,Escherichia coli A群の菌株の進化を牽引しています. この過程は,変異より50倍も頻繁に行われ,細菌集団を形成する.

科学分野:

微生物学微生物学とは
進化生物学の進化生物学について
人口遺伝学人口遺伝学

背景:

エシェリキア・コライは,バクテリアの集団動態を研究するための重要なモデル生物です.
バクテリアのゲノムを形成する進化的力を理解することは,公衆衛生とバイオテクノロジーにとって極めて重要です.
以前の研究では,細菌の進化における突然変異と再結合の両方の役割が強調されています.

研究の目的:

変異と再結合が,Escherichia coli.の天然の単離物の分岐に与える相対的な貢献を調査する.
特定のE. coli菌株の再結合率とその影響が集団構造に及ぼす影響を決定する.

主な方法:

12種類の天然のEscherichia coli単離物の核酸配列分析.
4つの染色体の位置を近接して調べる.
進化的出来事を推論するための遺伝子系譜の比較.

主要な成果:

ECORグループAのサブセットでは,共通の祖先からの分岐から3つの再結合イベントが特定されました.
このサブセットでは同じ期間に有意な突然変異の差異は観察されなかった.
ECORグループAサブセットの共通の祖先は,過去2400年以内に存在していました.
リコンビネーション率は,世代ごとに核酸1つあたり5.0×10−9の変化で推定され,これは変異率の50倍以上であった.

結論:

再結合は,ECORグループAのEscherichia coli菌株におけるクローン分岐を駆動する進化の支配的な力である.
再結合は,大腸菌の集団を著しく構造化し,その遺伝的多様性と適応に影響を与えます.
再結合率が高いことから,バクテリアの進化と適応において重要な役割を果たしていることが示唆される.

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