Fedorov Alexei, Roy Scott, Fedorova Larisa, Gilbert Walter
Department of Medicine, Medical College of Ohio, Toledo, Ohio 43614, USA.
Genome Res. 2003 Oct;13(10):2236-41. doi: 10.1101/gr.1029803. Epub 2003 Sep 15.
For nearly 15 years, it has been widely believed that many introns were recently acquired by the genes of multicellular organisms. However, the mechanism of acquisition has yet to be described for a single animal intron. Here, we report a large-scale computational analysis of the human, Drosophila melanogaster, Caenorhabditis elegans, and Arabidopsis thaliana genomes. We divided 147,796 human intron sequences into batches of similar lengths and aligned them with each other. Different types of homologies between introns were found, but none showed evidence of simple intron transposition. Also, 106,902 plant, 39,624 Drosophila, and 6021 C. elegans introns were examined. No single case of homologous introns in nonhomologous genes was detected. Thus, we found no example of transposition of introns in the last 50 million years in humans, in 3 million years in Drosophila and C. elegans, or in 5 million years in Arabidopsis. Either new introns do not arise via transposition of other introns or intron transposition must have occurred so early in evolution that all traces of homology have been lost.
近15年来，人们普遍认为多细胞生物的基因最近获得了许多内含子。然而，单个动物内含子的获得机制仍未得到描述。在这里，我们报告了对人类、黑腹果蝇、秀丽隐杆线虫和拟南芥基因组的大规模计算分析。我们将147,796个人类内含子序列分成长度相似的批次，并相互比对。在这些内含子之间发现了不同类型的同源性，但没有一个显示出简单内含子转座的证据。此外，还检查了106,902个植物内含子、39,624个果蝇内含子和6021个秀丽隐杆线虫内含子。未检测到非同源基因中同源内含子的单一案例。因此，我们发现在过去5000万年的人类、300万年的果蝇和秀丽隐杆线虫或500万年的拟南芥中，都没有内含子转座的例子。要么新的内含子不是通过其他内含子的转座产生的，要么内含子转座一定发生在进化的早期，以至于所有同源性的痕迹都已消失。
