鶏のZ染色体とヒトのX染色体の収束進化は,膨張と遺伝子獲得によるものである

Daniel W Bellott¹, Helen Skaletsky, Tatyana Pyntikova

¹Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, Massachusetts 02142, USA.

Nature

|July 13, 2010

まとめ

鳥や哺乳類の性染色体は,Z染色体やX染色体のように,収束して進化した. 彼らは独立して丸で発現する遺伝子を獲得し,遺伝子間の領域を拡張し,進化に関する以前の仮定に異議を唱えました.

科学分野:

ゲノミクスゲノミクスとは
進化生物学の進化生物学について
比較ゲノミクスとは

背景:

鳥 (ZZ雄,ZW雌) と哺乳類 (XY雄,XX雌) の性決定には,異なる性染色体が含まれています.
両性にも存在するZ染色体とX染色体は,自己染色体の起源からわずかに異なったと考えられていた.
一つの性のみに存在するW染色体とY染色体は,性染色体進化の主要な部位と考えられていた.

研究の目的:

鶏のZ染色体の進化軌道を調査し,ヒトのX染色体と比較する.
Z染色体とX染色体がオートソームとわずかに異なったという仮定に異議を唱えるために.
鳥類と哺乳類の性染色体間の共通の特徴と進化パターンを特定する.

主な方法:

鶏のZ染色体の配列決定.
鶏のZ染色体と人間のX染色体配列の包括的な比較分析.
遺伝子密度,遺伝子複製,および遺伝子間領域の拡大のバイオ情報分析.

主要な成果:

鶏のZ染色体はオートソームよりも遺伝子密度が低く,丸で発現する遺伝子が重複している.
鶏のZ染色体と人間のX染色体は,異なる祖先のゲノム領域から独立して進化した.
Z染色体とX染色体の両方が収束進化を示し,丸で発現する遺伝子の増幅と拡張されたインタージェニック領域によって特徴付けられ,オートソームと区別されます.

結論:

Z染色体とX染色体の進化は,異なった異婚系システムにもかかわらず,類似した特徴の収束的獲得を伴う.
鳥類と哺乳類の性染色体進化は,性特異性染色体における遺伝子喪失と,両性共通の染色体における遺伝子増殖/拡張によって特徴付けられています.
Z染色体とX染色体は,オートソームから分岐した後にユニークな特性を獲得し,単純分岐を超えた活発な進化過程を示しています.

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