3种沼虾的16S rRNA基因序列分析

为从分子角度理解3种沼虾,即罗氏沼虾、日本沼虾和祁连沼虾的遗传差异,为沼虾资源的管理、保护和合理开发利用提供理论基础,采集了每种沼虾各2尾样本,采用PCR的方法扩增了其线粒体16S rRNA基因片断并测序。比对后共获得了3种沼虾的297 bp的16S rRNA片断序列,共检测到47个变异位点,总变异率为15.8%。3种沼虾的平均碱基含量分别为T(37.7%)、C(10.9%)、A(29.8%)和G(21.6%)。罗氏沼虾种内个体间序列差异为3%。祁连沼虾和日本沼虾种内个体间差异均为0.7%,且两者种间差异很小,为0～0.7%。罗氏沼虾与祁连沼虾、日本沼虾之间的序列差异在13.1%～14.8%之间,种间差异明显。系统进化树显示罗氏沼虾自成一枝,而日本沼虾和祁连沼虾共同构成另一枝,日本沼虾和祁连沼虾的遗传距离小于5%,结果提示日本沼虾和祁连沼虾有很近的亲缘关系,两者也许是亚种关系。

Sequence Analysis of Mitochondrial 16S Rrna Gene of Three Species of Macrobrachium

In order to understand the molecular genetic differences among three species of Macrobrachium,i.e.,M.rosenbergii,M.nipponensis,and M.qilianensis,2 individuals of each species were collected and their mitochondrial 16S rRNA gene segment sequences were obtained by using the method of PCR amplification and sequencing.After alignment,297 base pairs of consensus sequences of 16S rRNA were used.Fourty-seven variable sites were detected,accounting for 15.8% of total sequence.The average base pair contents of three species of Macrobrachium are T(37.7%),C(10.9%),A(29.8%),and G(21.6%),respectively.The individual difference is 3% within M.rosenbergii,and is 0.7% within M.nipponensis and M.qilianensis.The species differences are between 0 and 0.7% for M.nipponensis and M.qilianensis,but for M.rosenbergii,the values are between 13.1% and 14.8% for M.nipponensis and M.qilianensis.Phylogenetic tree(NJ) shows that M.rosenbergii constitutes one monophyletic group,but M.nipponensis and M.qilianensis constitutes the other monophyletic group.This result suggested that M.nipponensis and M.qilianensis are close related species,and their difference may be at subspecies level.