Genetic Variation Of Tree Shrews (Tupaia Belangeri) In Chinese Different Poplutions Based On Co? And MC1R Gene

Tree shrew,Tupaia belangeri(Scadentia,Tupaiidae,Tupaia genus)is a specific Oriental species.Because its similarity with the primates in physiological mechanism and psychological stress models,it is becoming an ideal experimental animal model for human metabolic and neurological diseases.However,because of its wide geographical distribution(including southwest of China and Hainan island),the genetic backgrounds and the genetic differentiation relationships among various geographic populations were not clear,which becomes an obstacle on the investigation of standard experimental animal models.In the present study,127 samples were collected from Yunnan,Guizhou,Sichuan,Guangxi and Hainan provinces of China,and those samples were used to analysis.1398 bp of CO? gene sequences and 954 bp of MC1 R gene sequences by PCR amplification were obtained.These gene sequences were used to analysis the genetic diversity in 12 geographic populations.The results were divided into two parts:1.Study of genetic differentiation in different populations based on CO? gene in the tree shrewThere are 127 CO? gene sequences were obtained from 12 geographical populations by PCR.The C(17.2%)of 1398 bp CO? fragment was significantly lower than that of the other three bases.It contained 326 variable sites,accounting for23.3% of the total sites,311 Parsim-info sites,accounting for 22.2% of the total sites.There was 71 haplotypes in 127 individuals,which had five common haplotypes(Hap3,Hap30,Hap32,Hap33,Hap35),accounting for 7.04% of the total haplotypes.The total haplotype diversity(Hd)was 0.9750,and the nucleotide diversity(Pi)was0.04486,which indicated that the genetic diversity of the CO? gene was abundant.The genetic variations among the 12 populations showed that the nucleotide ambiguity(Kxy)and nucleotide difference(Dxy)were between 0.00198-0.12480 and2.769-174.352,respectively.The genetic distance and the net genetic distance(Da)showed that genetic distance between the Daxin population,Hainan population,Pianma population and Tengchong population were higher than that of other populations(0.118 ~ 0.141).The FST and Nm indexs showed that Daxin population,Hainan population,Pianma population and Tengchong population were significantly different from other populations,and the difference of Nm value showed the similar results,which suggested that there was significant genetic differentiation between these populations and other populations.The results of molecular variance analysis(AMOVA)found that the variation of CO?gene occurred mainly among the populations(82.93%),and 17.61% variation happened within the populations.There was no significant difference between the distribution curves of mismatch and neutral test(Tajima's D and Fu's Fs),which indicated that the populations of tree shrews did not experienced population expansion during the course of history.Inferred from NJ and BI phylogenetic tree,the 127 samples and 71 haplotypes clustered into four groups,Clade?: Hainan population;Clade ?: Daxin population;Clade ?: Pianma and Tengchong population;Clade?: Dali,Kunming,Hekou,Mengla,Leye,Xichang,Leye,Xingyi and Luquan populations.2.Research on the differences among different geographic populations of tree shrews based on the analysis of MC1 R geneIn the present study,a total of 954 bp sequence of MC1 R gene were obtained,in which that the proportion of A,T,C and G were 13.4%,19.5%,38.3% and 28.8%,respectively.The GC contents were higher than that of AT.930 conserved sites were found,which accounted for 97.4% of the total number of points,there had 24 variable sites(12.6% of the total number of points).Ts/Tv was 6.28.954 bp sequence of MC1 R gene encoded a total of 317 amino acids,including 20 common amino acids.Meanwhile,the content of leucine amino acids was the highest,accounting for 18.2%,while the least was tryptophan(Trp),only accounting for 0.9%.The population diversity(Pi)varied from 0.00013(Kunming population)to0.00790(Tengchong population),and the population average was 0.00435.The FST,Nm and mean distance among populations showed that Daxin population,Hainan population,Tengchong and Pianma population were different from other populations.Inferred from ME and NJ phylogenetic tree,the 12 populations of tree shrews were obviously clustered into 4 clades: Clade ?(Daxin population),Clade ?(Hainan population),Clade ?(Pianma and Tengchong population),Clade?(other populations).Conclusion:The phylogenetic analysis showed that the tree shrews in 12 geographic populations could be clustered into four groups based on the CO? gene and the MC1R gene.The clustering result is connected with their survival geographical habits.Conjectured that the geogrephical isolation(rivers,mountains and the sea)may be the main factors of above mentioned results.The current study provided a theoretical basis for the study of subspecies status and selection of experimental strains by researching the genetic differentiation from 12 tree shrew populations.