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Nature:基因复制与新功能演化的关系

作者: 来源:Nature 2018-03-07 我要评论( )

专题: Nature报道 基因复制为演化上的新功能提供一个重要模板,尽管这些新功能是在基因复制之前还是之后出现的仍是一个激烈争论的话题。很多基因是在它们积累有害突变时从基因组中

专题:Nature报道

Nature:基因复制与新功能演化的关系nmousewheel="return bbimg(this)" height=249 src="http://www.jiyinwang.com/skin/default1/image/lazy.gif" class="lazy" original="http://www.jiyinwang.com/file/upload/201803/07/163437881.jpg" width=185 onload=resizepic(this) border=0>

基因复制为演化上的新功能提供一个重要模板,尽管这些新功能是在基因复制之前还是之后出现的仍是一个激烈争论的话题。很多基因是在它们积累有害突变时从基因组中消失的,但其中一些通过分割它们的先祖功能或增添新功能逃过这一命运。基因复制产物的一个有趣、但尚未证实的命运是,分开的基因版本中先祖功能有所改进,推动这种改进的是正选择。David Des Marais 和Mark Rausher发现,这一过程发生在一个为植物花青素通道中一个关键酶编码的基因中,而且他们提出,这一过程比以前所认为的更普遍。

生物谷推荐原始出处:

Nature 454, 762-765 (7 August 2008) | doi:10.1038/nature07092

Escape from adaptive conflict after duplication in an anthocyanin pathway GENE

David L. Des Marais & Mark D. Rausher

Department of Biology and University Program in genetics and Genomics, Box 90338, Duke University, Durham, North Carolina 27708-0338, USA

Gene duplications have been recognized as an important source of evolutionary innovation and adaptation since at least Haldane1, and their varying fates may partly explain the vast disparity in observed genome sizes2. The expected fates of most gene duplications involve primarily non-adaptive substitutions leading to either non-functionalization of one duplicate copy or subfunctionalization3, neither of which yields novel function. A significant evolutionary problem is thus elucidating the mechanisms of adaptive evolutionary change leading to evolutionary novelty. Currently, the most widely recognized adaptive process involving gene duplication is neo-functionalization (NEO-F), in which one copy undergoes directional selection to perform a novel function after duplication4. An alternative, but understudied, adaptive fate that has been proposed is escape from adaptive conflict (EAC), in which a single-copy gene is selected to perform a novel function while maintaining its ancestral function5, 6. This gene is constrained from improving either novel or ancestral function because of detrimental pleiotropic effects on the other function. After duplication, one copy is free to improve novel function, whereas the other is selected to improve ancestral function. Here we first present two criteria that can be used to distinguish NEO-F from EAC. Using both tests for positive selection and assays of enzyme function, we then demonstrate that adaptive evolutionary change in a duplicated gene of the anthocyanin biosynthetic pathway in morning glories (Ipomoea) is best interpreted as EAC. Finally, we argue that this phenomenon likely occurs more often than has been previously believed and may thus represent an important mechanism in generating evolutionary novelty.


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