| Cystic Echinococcosis (CE) is a serious disease caused by the larvae of Echinococcus granulosus living autoeciously in human and ungulate. Cystic Echinococcosis is especially prevalent in Qinghai-Tibet Plateau. Cystic Echinococcosis seriously affected the health of local human and the development of graziery. Becaues of the rich genetic variation of Echinococcus granulosus, antiparasite drug is not usefull and the prevention and control of Echinococcosis become difficult. Therefore, the study concentrates on the population genetic structure of Echinococcus granulosusof Qinghai-Tibet Plateau.1. Population genetic structure studies of Qinghai-Tibet Plateau based on mtDNA12S geneThe aim of the current study was to investigate the population genetic structure of Echinococcus granulosus obtained from Qinghai-Tibet Plateau, and provide the foundational data for prevention and control of echinococcus disease. The complete sequence of mitochondrial DNA12S genes of98isolates which came from different areas and different hosts were sequenced. The result of sequences analyse was that all of98isolates were E. granulosus sensu stricio(gtnotype G1-G3). There were13haplotypes (ES1-ES13) and15nucleotide variation sites. Haplolypes diversity and nucleotide diversity were0.381and0.00092, respectively. The nucleotide diversity and genetic distanc of Sichuan population were the highest one of three populations. By AMOVA it was shown that97.36%of the total genetic variability is found among haplotype groups. NJ tree and Mrbayes tree were same basicly. Network showed that EA1was the main haplotype, and others arounded it. The points of Nm and FST showed that there was not significant genetic differentiation between populations. The result showed that Echinococcus granulosus of genotype G1-G3were found in Qinghai-Tibet Plateau. Genetic diversity existed in and among the populations of Qinghai-Tibet Plateau, and the genetic diversity of Sichuan population was more than that of other populations; Thevartration which happened in the population lead the intraspecific vartration. Geography cluster was not found, and the genetic divergence was not significant.2. Population genetic structure studies of Qinghai-Tibet Plateau based on mtDNA nadl gene and atp6geneIn order to the further research of population genetic structure of Echinococcus granulosus, this study adopted DNA sequencing technique to analyze the gene sequence of mtDNA nad1and mtDNA atp6of E. granulosus, and detected accurately E. granulosus genotypes, genetic diversity and population genetic structure. E. granulosus gene fragment size of nadl and atp6has been subjected in this experiment was894bp and513bp, respectively. According to the polyphone gene which included the complete nadl gene andthe complete atp6gene, we found that there were2genotypes(Gl, G3), and28haplotypes of E. granulosus in the98strains(22human strains,49sheep strains and13yak strains) of Qinghai-Tibet Plateau. Two strains (G3) were from human. G1genotype(sheep strain)of E. granulosus was the most prevalent genotype in Qinghai-Tibet Plateau. Haplotypes diversity and nucleotide diversity were0.864and0.00158, respectively. The genetic distance in population was between0.00140and0.00178, and that among the population was between0.00150and0.00168. By AMOVA it was shown that80.92%of the total genetic variability is found among haplotype groups. Phylogenetic analyses showed that there were two main groups. The points of Nm and FST revealed that there was not significant genetic differentiation between populations. Consequently, Echinococcus granulosus of genotype G1and genotype G3were found in Qinghai-Tibet Plateau, and genotype G1was the main genotype. Genetic diversity existed in and among the populations of Qinghai-Tibet Plateau, and the genetic diversity of Sichuan population was more than that of other populations; Thevartration which happened in the population lead the intraspecific vartration. the Genetic divergence was not significant, and geography cluster was not found. |
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