利用mtDNA 16S rRNA序列差异鉴定江西青岚湖的河蚌物种

THE SPECIES IDENTIFICATION OF MUSSELS IN QING LAN LAKE (JIANGXI PROVINCE)BASED ON SEQUENCE DIFFERENCES OF MITOCHONDIRIAL 16S rRNA GENE

对从青岚湖采集的 10属 14种河蚌的 19个样本进行了 16SrRNA的序列测定 ,并同GenBank中鄱阳湖流域相同物种河蚌的序列比较 ,分析了基于Kimura 2 parameter模型参数得到的遗传距离 ,并构建了它们的UPGMA树。结果显示 ,所有用于比较的河蚌种间遗传距离变化范围在 0 .0 2 74— 0 .2 2 90 ,平均为 0 .132 5 ,种内遗传距离在0 .0 0 34— 0 .0 0 6 8之间 ,平均为 0 .0 0 4 5 ,种间遗传距离远大于种内距离。表明以 16SrRNA作为遗传标记 ,可以在物种水平上对青岚湖的河蚌进行准确的鉴定。

Generally,the identification of freshwater mollusk is mainly baesd on shell differences,but shells are greatly variable under different environmental conditions and hence usually result in taxonomic confusion.To clarify these problems,many studies on morphology,ecology,anatomy and physiology have been carried out in the past years,such as the researches on marsupia,glochidium,sensory hairs and spines.However,they have not shown any conclusive evidence for definite identification. In order to identify the mussel species correctly,we employed the molecular systematic method.The mitochondrial 16S ribosomal RNA gene has been used in the pyhlogenetic studies of mussels successfully. In the present study,the 16S rRNA gene fragments were sequenced to 19 individuals of mussels,which belong to 14 species of 10 genera,and were from the Qing Lan Lake (Jiangxi province,where the water quality is excellent and the species of fishes and mussels are abundant).The target fragments of 16S rRAN were isolated by PCR amplification to the samples.Thirty five cycles of PCR(94℃,1min denatruing,57℃,30s annealing,72℃,1min extension) were performed.Some sequenees of mussels from Poyang Lake were downloaded from GenBank for comparison.Alignments were manipulated using Clustal X and refined manually where necessary.Sequence analysis was performed using MEGA (Version 2.1)software.Genetic distances were calculated based on Kimura 2 parameter model.The largest intraspecific genetic distance is 0.0068,much lower than the average interspecific distance,which has a value of 0.1325,and still much lower than the shortest interspecific distance,0.0274,suggesting that 16S rRNA is a useful genetic marker for identification of mussel species clearly.