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

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.