| Cricetulus barabensis are widely distributed in China and have strong reproductive ability. The species have been considered as deleterious animals for agriculture and industry, which is a serious threat to people'normal production and life. In recent years, C. barabensis as the dominant rodent species in North of China has evoked more and more concerns among the academic circles, and many researches outcomes spring. In these experiments the author investigate from the viewpoint of molecular biology.The obese gene (OB) mainly expressed in adipose tissue. Leptin is the expression product of obese gene which is a peptide hormone discovered recently. Leptin plays an important role in animal physiology function such as ingestion, energy metabolism, reproduction activity, fat storage, fetal growth, puberty development, tumour cell proliferation, hemopoiesis, neuroimmunoendocrine and so on. It is of the most important biological significance for the survival and reproduction.In order to investigation the population hereditary constitution of C. barabensis, in this thesis, the partial sequence of obese gene was amplifid and sequenced.1665bp of OB of the species in Shandong Province was amplified by polymerase chain reaction for the first time. The primers were designed on the basis of the homologous species from GenBank consisting of mice, rat and human. The sequence of OB covers partial exon2, total intron2 and partial exon3. The sequence were then cloned and sequenced in 3 geographic populations in Shandong Province: Yinan, Linqu and Qufu. A total of 19 SNPs were examined, including lindels Insert/Deletion and the ratio of conversion to transversion was 15/4.34 haplotypes were defined in 103 samples, The sequence numbers submitted to the GenBank were:HM100043～HM100076. The sequence numbers submitted to the GenBank were～.The nucleotide diversity (π), number of haplotye (H), haplotype diversity (Hd), average number of nucleotide differences (K), number of polymorphic sites (S) and theta from S (θw) of OB of Yinan, Linqu and Qufu populations were calculated with DnaSPv5.0 software, which showed that the genetic diversity of the three populations arrayed as (from high to low):Linqu,Yinan, Qufu. In addition, Fst, Nm and Dxy proved the genetic differentiation among the three populations existed in a low level. The result of Gst analysis among three populations arrayed from 0.00455 to 0.06523, which meant that above 93% mutation existed in each population while few mutation existed among populations. NJ analysis showed that the genetic differentiation among the three populations was not distinct. The research showed that OB on C. barabensis from Qufu,Yinan and Linqu was rich in haplotype diversity and nucleotide diversity. The genetic differentiation among the three populations:Qufu,Yinan,Linqu of C. barabensis are small. In the study, by analyzing the sequence of OB on C. barabensi with different body fat percent we found three cSNPs in coding section:C/T, A/G and A/G, all of them are samesense mutation. We analized the coding section of OB in 66 samples, then found 4 haplotypes. The data were analyzed statistically with SPSS17.0. The result shows that there is significant difference of body fat percent among 4 haplotypes. Because these mutations couldn't change the sequence of Amino Acids Production, the protein activity wasn't affected, and obvious trait variation didn't appeared on animals, so I think gene mutation was not the main reason for trait variation. Any other reasons may lead to the significant difference among body fat percent of different haplotype of C. barabensis. And in this study, the relationships between different haplotype and body fat percent, the genetic effect of OB on body fat deposition are needed to be further studied by enlarging the samples. Besides, concerning the correlation on gene level between OB and functions such as breeding and immunity of Striped Hamster, further research is also needed. |
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