双翅目昆虫与脊椎动物内含子丢失和获得的比较分析

Comparative analysis of intron loss and gain between Diptera and Vertebrata

内含子插入和丢失的进化动力及机制尚存有许多疑问。我们拟通过对真核生物的604个同源基因的蛋白高度保守区域内含子-外显子的结构研究,对人Homosapiens、大鼠Rattus norvegicus、小鼠Mus musculus、黑腹果蝇Drosophila melanogaster、冈比亚按蚊Anopheles gambiae和拟南芥Arabidopsis thaliana中的12585个内含子、3074个保守内含子进行分析,推断出不同系统中内含子进化趋势。结果显示在进化中双翅目昆虫丢失了约850多个内含子,脊椎动物获得了1600多个内含子,而双翅目昆虫获得的内含子及脊椎动物丢失的内含子则较少。在内含子分布上,除酵母有明显5′末端倾向性外,双翅目昆虫也显示出内含子分布倾向于基因的5′端,而在脊椎动物及拟南芥中则没有这种分布的倾向性。这可能是由于双翅目昆虫丢失的内含子大多位于基因的3′端造成的。通过对现在脊椎动物内含子分布及获得的内含子的插入相的研究,发现内含子的获得可能在一定程度上导致了现存基因的内含子中插入相0的内含子最多这一倾向。

The mechanisms and evolutionary dynamics of intron insertion and loss in eukaryotic genes remain poorly known. A total of 604 protein-coding genes,which contain 12 585 introns and 3 074 conserved introns in distinct amino acid alignment sequences in orthologous genes from Vertebrata （Mus musculus,Rattus norvegicus and Homo sapiens）,Diptera （Anopheles gambiae） and plant （Arabidopsis thaliana） were analyzed using systematic methods to assess the causes of present-day distribution of introns in different lineages. The results demonstrated that more than 850 introns lost in Diptera evolution and more than 1 600 introns gained in Vertebrata evolution,but the intron gain in Diptera evolution and intron loss in Vertebrata evolution are relatively less. Additionally,along with yeast,the distribution of introns in Diptera exhibits a bit more prevalent in the 5＇ end of genes,which was not found in vertebrates and plants. This may be due to intron loss mostly occurring in 3＇ end of genes in Diptera evolution. Meanwhile statistical results indicate that phase 0 intron is most common in the three species in Vertebrata,and this might be the consequence of that phase 0 intron was the most frequently gained intron type in evolution.