Long M, de Souza S J, Gilbert W
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
Curr Opin Genet Dev. 1995 Dec;5(6):774-8. doi: 10.1016/0959-437x(95)80010-3.
The origin and evolution of intron-exon structures continue to be controversial topics. Two alternative theories, the 'exon theory of genes' and the 'insertional theory of introns', debate the presence or absence of introns in primordial genes. Both sides of the argument have focused on the positions of introns with respect to protein and gene structures. A new approach has emerged in the study of the evolution of intron-exon structures: a population analysis of genes. One example is the statistical analysis of intron phases--the position of introns within or between codons. This analysis detected a significant signal of exon shuffling in the DNA sequence database containing both ancient and modern exon sequences: intron phase correlations, that is, the association together within genes of introns of the same phase. The results of this analysis suggest that exon shuffling played an important role in the origin of both ancient and modern genes.
内含子-外显子结构的起源与进化一直是颇具争议的话题。两种不同的理论，即“基因外显子理论”和“内含子插入理论”，对原始基因中内含子的有无展开了争论。争论双方都聚焦于内含子相对于蛋白质和基因结构的位置。在对内含子-外显子结构进化的研究中出现了一种新方法：对基因进行群体分析。一个例子是对内含子相位的统计分析——内含子在密码子内部或之间的位置。该分析在包含古代和现代外显子序列的DNA序列数据库中检测到了外显子重排的显著信号：内含子相位相关性，即同一相位的内含子在基因内共同出现的情况。这一分析结果表明，外显子重排在古代和现代基因的起源中都发挥了重要作用。
