Protein-Coding Segments: Evolution of Exon-Intron Gene Structure

摘要: Many eukaryotic genes are disrupted by noncoding regions of deoxyribonucleic acid (DNA) variable sizes called introns, giving the an exon–intron structure. Origin and evolution introns is important, long-standing problem. The availability multiple, complete genome sequences allows one to address many fundamental evolutionary questions. Analysis orthologous from completely sequenced genomes revealed numerous shared intron positions in between animals, fungi, plants protists. data on were used as starting point for reconstruction with various phylogenetic methods. These methods reconstructed intron-rich ancestors but cases inferred lineage-specific high levels loss gain. results indicate that present already at earliest stages eukaryotes compatible hypothesis original, catastrophic invasion accompanied emergence cells. Key concepts: The gene structure highly dynamic. Orthologous distant species share up 25–30% positions. Intron gains losses might occur during limited time spans. The Last Eukaryotic Common Ancestor was intron-rich. In course evolution, splice signal shifts exons introns. The scenario origin best comparative genomics goes follows: self-splicing since life's followed spliceosomal invading emerging subsequent gain introns. Keywords: gene structure; molecular evolution; introns; exons