| 摘要: |
| 为全面揭示尾索动物线粒体基因组的基本特征,作者系统分析了12 种尾索动物的线粒体基因组全序列, 尾索动物线粒体基因组所有的基因均在同一链上编码, 这与脊椎动物、头索动物线粒体基因组的基因分布特征显著不同。与后生动物线粒体基因组标准的基因组成相比, 尾索动物线粒体基因组存在转运RNA 基因的增加以及部分物种atp8 基因的缺失。在尾索动物线粒体基因组中发生了大规模的基因重排, 即使在同属物种的线粒体基因组中, 也存在主编码基因的基因重排及基因缺失。尾索动物线粒体基因组蛋白质编码基因的起始密码子、终止密码子及氨基酸长度存在明显差异。2 个玻璃海鞘(Ciona intestinalis 和C. savignyi)线粒体基因组12 个蛋白质编码基因的Ka/Ks 比值都低于1(0.0927～0.6752), 显示出一定的负选择。在所有的主编码基因中, nad5 基因和nad4 基因的变异位点最多, 可以作为备选的分子标记, 用于分析尾索动物不同物种之间的生物多样性。基于线粒体基因组的系统发育分析, 支持尾索动物在科级的亲缘关系为: (((柄海鞘科Pyuridae+芋海鞘科Styelidae)+(((三段海鞘科Polyclinidae+星骨海鞘科Didemnidae)+簇海鞘科Clavelinidae)+玻璃海鞘科Cionidae))+长纹海鞘科Ascidiidae)+海樽科Doliolidae。 |
| 关键词: 尾索动物 线粒体基因组 基因排列 分子标记 分子系统发育 |
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| 基金项目:国家自然科学基金资助项目(40906067); 中国博士后科学基金项目(2012M510054); 中央财政支持地方高校发展专项资金项目(CXTD04、CXTD01); 江苏省海洋生物技术重点实验室资助项目(2009HS13、2011HS009); 江苏省“青蓝工程”人才基金资助项目(苏教师[2010]27 号) |
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| Comparison on characteristics of tunicates mitochondrial genomes and molecular phylogeny |
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| Abstract: |
| In this paper, a comprehensive analysis based on 12 tunicates mitochondrial genomes has been done and the basic characteristics of tunicates mitochondrial genomes are fully revealed. In tunicates mitochondrial genomes, all genes are encoded on the same DNA strand, which is significantly different with the genes distribution feature of vertebrates and amphioxus mitochondrial genomes. Compared with typical gene composition of metazoan mitochondrial genomes, there are increase of transfer RNA genes and missing of atp8 gene in some tunicates species. Gene order is extremely rearranged among tunicates mitochondrial genomes, there are gene rearrangement and gene loss of major genes even in same genus. There are differences in the start codon, stop codon and amino-acid number in protein-coding genes of tunicates mitochondrial genomes. The ratio of Ka/Ks of 12 protein-coding genes from 2 Ciona mitochondrial genomes is less than 1 (between 0.0927 and 0.6752), indicating a negative selection. In major coding genes, nad5 and nad4 genes have the largest number of different loci, which can be used as alternative molecular markers to analyze biodiversity among different tunicates species. The phylogenetic trees based on mitochondrial genomes support the relationship at family level: (((Pyuridae+Styelidae)+(((Polyclinidae+Didemnidae)+Clavelinidae)+Cionidae))+ Ascidiidae)+Doliolidae. |
| Key words: tunicates mitochondrial genome gene order molecular marker molecular phylogeny |
