TY  - JOUR
A1  - Wang, Wen
A1  - Zheng, Hongkun
A1  - Yang, Shuang
A1  - Yu, Haijing
A1  - Li, Jun
A1  - Jiang, Huifeng
A1  - Su, Jianning
A1  - Yang, Lei
A1  - Zhang, Jianguo
A1  - McDermott, Jason
A1  - Samudrala, Ram
A1  - Wang, Jian
A1  - Yang, Huanming
A1  - Yu, Jun
A1  - Kristiansen, Karsten
A1  - Wong, Gane Ka-Shu
A1  - Wang, Jun
T1  - Origin and evolution of new exons in rodents
Y1  - 2005/09/01 
JF  - Genome Research 
JO  - Genome Research 
SP  - 1258 
EP  - 1264 
DO  - 10.1101/gr.3929705 
VL  - 15 
IS  - 9 
UR  - http://genome.cshlp.org/content/15/9/1258.abstract 
N2  - Gene number difference among organisms demonstrates that new gene origination is a fundamental biological process in evolution. Exon shuffling has been universally observed in the formation of new genes. Yet to be learned are the ways new exons originate and evolve, and how often new exons appear. To address these questions, we identified 2695 newly evolved exons in the mouse and rat by comparing the expressed sequences of 12,419 orthologous genes between human and mouse, using 743,856 pig ESTs as the outgroup. The new exon origination rate is about 2.71 × 10-3 per gene per million years. These new exons have markedly accelerated rates both of nonsynonymous substitutions and of insertions/deletions (indels). A much higher proportion of new exons have Ka/Ks ratios >1 (where Ka is the nonsynonymous substitution rate and Ks is the synonymous substitution rate) than do the old exons shared by human and mouse, implying a role of positive selection in the rapid evolution. The majority of these new exons have sequences unique in the genome, suggesting that most new exons might originate through “exonization” of intronic sequences. Most of the new exons appear to be alternative exons that are expressed at low levels. 
ER  -