Comparison of Mitochondrial D-loop and Cyt b#br#
Sequences of Squaliobarbus curriculus
YANG Huirong；ZHAO Huihong；MONG Zining；LIU Li；LIN Quanzhuo
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Sequences of mitochondrial D-loop and Cyt b gene of 24 individuals of Squaliobarbus curriculus which were sampled from four populations in Yangtze River and Pearl River were determined. Using PCR amplification and sequencing, 598bp of D-loop partial sequences and 752 bp of Cyt b partial sequences were obtained. In D-loop sequences, a total of 67 polymorphic sites defined 18 distinct haplotypes. And 34 parsim-info, 40 transition, 15 transversion and 14 insert/lacuna loci were found. The average content of A, T, C and G was 33.7%, 35.1%, 17.5% and 13.7%, respectively. In Cyt b sequences, 72 polymorphic sites and 18 haplotypes were defined, and 68 parsim-info, 60 transition, 15 transversion and no insert/lacuna loci were found. The average content of A, T, C and G was 29.3%, 26.4%, 29.8% and 14.5%, respectively. The mean haplotype diversity (H), the average number of nucleotide difference (K) and nucleotide diversity (π) for D-loop sequences were 0.9638, 16.543 5 and 0.0284, respectively. Accordingly, the values for Cyt b were 0.971 0, 31.855 1 and 0.042 6, respectively. The results suggested that both D-loop and Cyt b genes showed high genetic diversity in S. curriculus, among which the majority existed within populations. Based on population pairwise genetic distances and FST, there were obvious genetic differences between Yangtze River and Pearl River for S.curriculus Molecular phylogenetic tree and analysis of molecular variance (AMOVA) also supported this result. The interpopulation genetic distances of Cyt b in the same water system were less than D-loop; while those in the different water system were more than D-loop. So for Cyt b, the more interpopulation genetic diversity was, the smaller genetic distances and FSTwere; the less interpopulation genetic diversity was, the larger genetic distances and FSTwere, which might be closely related to difference of evolutionary rate between D-loop and Cyt bgene.