网纹蟒非入侵式采样和线粒体基因组分析

Non-invasive sampling and mitochondrial genome analysis in Python reticulatus

采用非入侵式采样,提取网纹蟒Python reticulatus粪便和新鲜蛇蜕的基因组,探讨非入侵式采样在蛇类研究中的可能性。利用聚合酶链式反应(PCR)测定和拼接网纹蟒线粒体基因组全序列,结合GenBank中蟒科Pythonidae线粒体基因组全序列,对蟒科物种进行比较分析。结果发现:蛇蜕中提取的DNA优于粪便,液氮处理能提高DNA质量浓度。网纹蟒线粒体基因组全长17 641 bp,基因排布和结构同蟒科物种一致,但部分基因起始密码子和终止密码子存在差异。根据系统发育树分析推测,与蚺科Boidae相比,蟒科和闪鳞蛇科Xenopeltidae进化关系更接近。对蛇类物种进化过程的分析发现:热点区域存在2个相似度非常高的控制区,系统树上的拓扑结构呈簇状排列,推测2个控制区的结构来源于一个祖先。这种种内进化的模式为协同进化。

To explore the possibility of non-invasive sampling in snake research, feces and fresh snake sloughs for genome extraction from Python reticulatus(reticulated python) were used. Furthermore, Polymerase Chain Reaction(PCR) was taken, and the full sequence of mitochondrial genome was analyzed with mitochondrial genome dates in GenBank. Results showed that(1) the quality of DNA extracted from snake sloughs was better than that of feces, and the concentration of DNA extracted by liquid nitrogen treatment was higher.(2) The complete sequence of the mitochondrial genome was obtained for a length of 17 641 bp with gene arrangement and structure being consistent with the Pythonidae species. However, there were differences in the start codons and stop codons of some genes.(3) Inferred from the phylogenetic tree analysis, the evolutionary relationship was speculated as(Pythonidae, Xenopeltidae and Boidae).(4) Analysis of the hotspots in species evolution showed that similarity was very high in the two control regions, and they were clustered by species in the phylogenetic tree. Thus, it was presumed the structures of the two control regions originated from the same ancestor, and this intraspecific evolution was due to co-evolution.[Ch, 3 fig. 2 tab. 15 ref.].