日本沼虾三群体线粒体16S rRNA基因片段序列的差异与系统进化

通过对日本沼虾(Macrobrachium nipponense)3个群体线粒体DNA 16S rRNA基因片段进行扩增和测定,得到长度为495bp的片段,其碱基A、T、G和C的平均含量分别为28.6%、36.1%、22.7%和12.5%,AT含量明显高于GC含量。通过对日本沼虾16SrRNA基因片段遗传特征的研究发现其种内变异很小,在3个群体中只有5个位点发生转换。另外,利用其454bp的同源序列,以中国明对虾(Fenneropenaeus chinensis)为外群探讨了沼虾属日本沼虾、罗氏沼虾(M.rosenbergii)等8种沼虾的系统进化关系。用MEGA3.1软件中的NJ法构建的分子进化树,日本沼虾3个群体先聚在一起后与海南沼虾聚在一起;另外,罗氏沼虾与马氏沼虾、短腕沼虾与贪食沼虾亲缘关系较近先聚在一起,然后再与大臂沼虾和等齿沼虾聚在一起,最后才与外群中国明对虾聚在一起。

Sequence Analysis and Molecular Phylogeny of Mitochondrial 16S rRNA Gene Fragments in Three Populations of Macrobrachium nipponense

Mitochondrial 16S rRNA gene fragments of wild Macrobrachium nipponense were amplified with PCR,then the PCR products were purified and sequenced,and 495 bp nucleotide sequences were obtained.The A,T,G and C contents in this fragment were 28.6%,36.1%,22.7% and 12.5%,respectively; the AT content was higher than the GC content.Little sequence variation was observed in 16S rRNA gene fragments within species,and transition in only 5 loci was revealed in three populations.Furthermore,454 bp fragment of the sequence was used to discuss the phylogenetic relationship among M.nipponense,M.rosenbergii,M.hainanense,M.malcolmsonii, M.lar,M.latimanus,M.carcinus and M.equidens using Fenneropenaeus chinensis as the out-group.The molecular phylogenetic tree was constructed by NJ method using software MEGA 3.1,and three populations of M.nipponense were clustered first and then clustered with M.hainanense; M.rosenbergii and M.malcolmsonii,as well as M.lar and M.latimanus had a closer genetic relationship and were clustered first,then they were clustered with M.carcinus and M.equidens,and finally with Fenneropenaeus chinensis.