Belshaw R, Bensasson D
Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
Heredity (Edinb). 2006 Mar;96(3):208-13. doi: 10.1038/sj.hdy.6800791.
There has been a lively debate over the evolution of eukaryote introns: at what point in the tree of life did they appear and from where, and what has been their subsequent pattern of loss and gain? A diverse range of recent research papers is relevant to this debate, and it is timely to bring them together. The absence of introns that are not self-splicing in prokaryotes and several other lines of evidence suggest an ancient eukaryotic origin for these introns, and the subsequent gain and loss of introns appears to be an ongoing process in many organisms. Some introns are now functionally important and there have been suggestions that invoke natural selection for the ancient and recent gain of introns, but it is also possible that fixation and loss of introns can occur in the absence of positive selection.
它们在生命之树的哪个节点出现，来自何处，以及随后它们的丢失和获得模式是怎样的？最近一系列不同的研究论文都与这场争论相关，将它们汇集在一起正逢其时。原核生物中不存在非自我剪接的内含子以及其他一些证据表明这些内含子起源于古老的真核生物，而且内含子随后的获得和丢失在许多生物体中似乎是一个持续的过程。一些内含子现在具有重要的功能，有人提出自然选择导致了内含子在古代和近期的获得，但内含子的固定和丢失也可能在没有正选择的情况下发生。
