| OBJECTIVE:The purpose of comparatively analyzing the genetic basis of the data between the two tree shrew populations which were originally from Guangxi and Yunnan respectively is to promote the cultivation of tree shrews superior strains and provide the potential genetic information for studying the difference of infection efficiency of tree shrews hepatitis model between different groups.METHODS:A total of 64 blood samples extracted genes DNA were collected, 32 of which were from the tree shrews of Guangxi population and the other 32 from Yunnan population. PCR amplification products of the nine fluorescent labeling simple sequence repeat (SSR) markers were coarsely screened with 1% agarose, then the capillary electrophoresis technique was utilized to detect the purpose fragment and various of bioinformatics software were applied to analyze genetic diversity of the two tree shrew populations (Guangxi group and Yunnan group), such as the number of alleles per marker (Na), effective number of alleles (Ne), observed heterozygosity (Ho), expected heterozygosity (He), polymorphism information content (PIC), Shannon index (Ⅰ), the F-statistics, genetic distance and so on. STRUCTURE was also used to explore the potential genetic structure between the two populations.RESULTS:1. The nine microsatellite loci showed significant genetic variation:62 alleles were identified among the 64 individuals. The average number of observed alleles (Na) per locus was 6.889, ranging from 3 alleles to 14 alleles. The average number of effective alleles (Ne) per locus was 4.392, ranging from 1.314 to 10.002. Means and ranges for other genetic diversity indicators were as follows:Ho, mean 0.484, ranging from 0.141 to 1.000, He, 0.703, from 0.241 to 0.907, PIC,0.725, from 0.541 to 0.895, AR,6.388, from 2.995 to 12.824, and Shannon index,1.490, from 0.484 to 2.419.2. The mean number of effective alleles, expected heterozygosity, polymorphism information content and shannon index were slightly higher in Guangxi group than that in Yunnan group (2.742 vs 2.294,0.586 vs 0.484,0.520 vs 0.420 and 1.068 vs 0.861 respectively), but the differences of which were not statistically significant (PNe=0.232, PHe=0.193, PPic=0.197and PI=0.232 respectively). In addition, the average number of expected heterozygosity and polymorphism information content among the 9 microsatellite loci of the two groups were 0.703 and 0.725 respectively, indicating that the two tree shrew populations were with high genetic diversity.3. The mean value of Fis was positive in both populations, suggesting that individuals within each population might have some inbreeding phenomenon, while the mean value of Fst was 0.235, implying a high genetic differentiation. The results of the tests on all the loci with Hardy-Weinberg Equilibrium and Linkage Disequilibrium showed that four loci (CCBL1B, CCDC61, EDA1 and OPA3) in the two populations exhibited significant deviations (p<0.001), probably resulted from the influence of inbreeding, selection and mutation, which demonstrated the genetic structure of two tree shrew populations was unstable, while no evidence of linkage disequilibrium among loci was evaluated.4. The study also found the genetic similarity between the two populations was 0.28, while the genetic distance and unbiased genetic distance were 1.277 and 1.268 respectively. The results from AMOVA analysis showed that 61.57% of genetic variation occurred within populations and 38.43% occurred among populations. Furthermore, analysis on STRUCTURE showed that individuals in this study were divided into two theoretical populations, namely, the tree shrews in Guangxi group are a single subspecies, while the tree shrews in Yunnan group probably belong to another subspecies, which not only provide reliable genetic data for the further study of tree shrew, but also can offer constructive suggestions to assess the different infection effect among different subspecies of tree shrew when we conduct hepatitis tree shrews model.CONCLUSIONS:Results from this study consistently indicate high genetic diversity of the two tree shrew populations. There is a distinctly genetic difference and obvious genetic differentiation between two groups, which further illustrate the two tree shrew populations were divided into two different subspecies. In addition, genetic variation was derived mainly from the individuals, but the genetic variability between populations cannot be ignored. This study not only can promote the cultivation of tree shrews superior strains, but also offer the potential genetic information to study the difference of infection efficiency of tree shrews hepatitis model between different populations. |
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