一个拟议的途径,通过该途径,哺乳动物X和Y染色体中常见的基因进化成为X失活的染色体
1Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge 02142, USA.
Nature
|September 2, 1998
概括
对于特定的X-Y基因,X无活化是独立进化的,而不仅仅是区域性的. 这一过程适应了同源Y链基因的丧失,如ZFX,RPS4X和SMCX基因进化中所见.
科学领域:
- 遗传学 是一个遗传学.
- 进化生物学 进化生物学
- 基因组学就是基因组学.
背景情况:
- 哺乳动物X和Y染色体起源于一个自体组对,Y染色体失去大多数祖先基因.
- 人们通常认为X无活化,即女性的一个X染色体的沉默,是一种广泛的染色体或区域过程.
- X-Y基因的进化及其在X染色体上的剂量补偿仍然不完全理解.
研究的目的:
- 研究X染色体和Y染色体 (X-Y基因) 分享的特定基因的X无活化的独立进化.
- 检查各种哺乳动物物种中ZFX,RPS4X和SMCX基因X失活逃逸的进化轨迹.
- 提出一种新的X无活化进化模型,与Y链接同源基因的衰变相关.
主要方法:
- 在各种物种中测试ZFX,RPS4X和SMCX基因中的CpG岛甲基化,以监测X无活化.
- 对X-Y基因对及其不同哺乳动物系的无活化状态进行比较基因组分析.
- 基因失活模式的遗传学重建,以推断进化历史.
主要成果:
- 在原始eutherians和大多数现存的订单中,ZFX逃脱了X无活化,除了肌形动物的例外,这表明了独立的进化.
- 从X无活化中脱离RPS4X似乎是一个灵长类动物特有的现象.
- SMCX表现出可变的X无活化逃脱模式,在灵长类动物和肌形动物中不存在,但在其他血统中存在,进一步支持独立的基因进化.
结论:
- 对于个体基因来说,X无活化可以独立地演变,这挑战了纯粹区域或染色体机制的概念.
- 观察到的模式表明,X无活化是对同源Y链基因的逐渐丧失或衰变的适应性反应.
- 这项研究提供了X-Y基因多步进化路径的证据,导致X染色体上的剂量补偿.
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