Whole Mitochondrial Genome Sequence And Analysis Of Genetic Diversity Of Pseudecheneis Sulcata Of Brahmaputra In Tibet

In this study,whole mitochondrial DNA sequence of Pseudecheneis sulcata Distributed in Brahmaputra was Analyzed.Sequence phylogenetic tree of 9 species was built.Furthermore,the Cyt b gene and D-loop region were treated as marker and genetic diversity of 2 populations of Pseudecheneis sulcata Distributed in Lilong and Motuo area of Brahmaputra was analyzed respectively,the sample size is 60 and main conclusions of our study were listed below.The whole mitochondrial DNA sequence of Pseudecheneis sulcata is 16,535 bp,purines show a bias proportion at 53.98%.The sequence shows a high consistency with most teleost species and includes 37 genes compromising 13 coding sequences,22tRNA genes and 2 rRNA genes.Besides,two non-coding regions were found.NAD6and 8 tRNA including tRNA-Gln,tRNA-Ala,tRNA-Asn,t RNA-Cys,tRNA-Tyr,tRNA-Ser,tRNA-Glu and tRNA-Pro were located on L chain,the rest genes were verified on H chain.There exist 2 initial codons(ATG,GTG),4 groups of stop codons(TAA,TAG,TA-,T--)and 34 preference codons in all coding sequences.The genes of tRNA and rRNA can form secondary structures and the rRNA genes are relatively conservative.According to built phylogenetic tree,data showed that Pseudecheneis sulcata was located at base.Pareuchiloglanis,Creteuchiloglanis and Glyptothorax have formed monophyletic group.Glaridoglanis and Glyptosternum is sistergroup with each other,and the relationship of Creteuchiloglanis and Pareuchiloglanis is close.Cyt b gene and D-loop region were chosen to evaluate the genetic diversity of Pseudecheneis sulcata.1060 bp of Cyt b and 833 bp of D-loop were analyzed.Data shows that both populations in Lilong and Motuo area of Brahmaputra have high haplotype diversity value,but the diversity of nucleotide is low.A high frequency of haplotype 1 and haplotype 2 was observed in both populations,which indicates that their ancestor is haplotype.Meanwhile,the two populations also have their unique haplotype.AMOVA analysis of Cyt b shows that the genetic variations were generated among the population,and the genetic differentiation between populations had not reached a significant level.Neutral test(Tajima's D and Fu's F_s)and nucleotide mismatch analysis(SSD and Hir)revealed that Pseudecheneis sulcata have not experienced population expansion.AMOVA analysis of D-loop and combined genes shows that the genetic variations were generated among the population,and the genetic differentiation between populations had reached a significant level.Neutral test(Tajima's D and Fu's Fs)and nucleotide mismatch analysis(SSD and Hir)revealed that Pseudecheneis sulcata have experienced population expansion.This study indicated that there were barriers in gene flow between the two populations of P.sulcata.The geographical barriers such as altitude difference and hydrological situation of the Brahmaputra Grand Canyon can be the main causes.