The Genetic Diversity Analysis Of Sry Gene On Y Chromosome In Chinese House Mice (Mus Musculus)

House mice(Mus musculus)are belonging to Mammalia,Rodentia,Muridae,Mus.It is a kind of human commensals that distribute all over the world.The derived laboratory inbred strains of house mice have become an important model species that have been applied extensively in both biological and biomedical researches.As a kind of human commensals,the biogeographic and population genetic patterns of house mice are closely associated with human migration history,trade links,cultural exchanges,and development of agriculture.China has a vast territory,and complex terrain,and house mice distribute throughout the whole country.The population genetic structure of Chinese house mice,especially the genetic diversity of Y chromosome,has not been investigated systematically.In this thesis,we explored the biogeographic and genetic evolution pattern of Chinese house mice with Sry on Y chromosome which represents the paternal inheritance.A total of 212 male mice individuals were collected from 23 localities of 15 provinces and genomic DNA were extracted,and sequences of Sry gene segments were obtained with PCR and sequencing techniques.Then,the genetic diversity(base compositions,haplotypes)of these sequences were analyzed,and the Network of haplotypes and Bayesian phylogenetic tree were constructed.The average length of the amplified Sry segments was 856 bp,and the average base composition was A 27.5%,T 30.7%,G 22.5%,and C 19.3%.The sequences showed obvious bias to A+T(58.2%).There were 73 polymorphic loci sitesand 22 informative sites,which indicated the gene diversity was low.The average nucleotide diversity was 0.00356,and the values of nucleotide diversity of different localities ranged from 0.00096(Zhoukou)to 0.00657(Nanning).The Hd(haplotype diversity)of all sequences was 0.729,and the Hd of different localities ranged from 0.249(Shanghai)to 0.833(Nanning).A total of 28 haplotypes were defined in 212 sequences by DAMBE software.117 individuals from 16 localities contained haplotype S1,and 62 individuals from 12 localities contained haplotype S2.The proportion of S1 and S2 accounted for 50.5% and 29.7%,respectively,and the proportion of other 26 haplotype accounted for 19.8%.Sequence alignment showed that there were little differences among sequences from different regions and different haplotypes,and the genetic distances were small.The results indicated that the Sry gene in Chinese house mice was quiet conservative,and its genetic polymorphism was low.The haplotype Network showed that haplotype S1 and S2 were central haplotypesdisplay has been collected as the center to S1 haplotype,S2 as the center of divergence distribution.The Bayesian phylogenetic tree based on Sry gene oshows that the tdid not show two divergent clades corresponding to the results of mitochondrial markers,which indicated that,as paternal inheritance marker,Sry was more conservative,and there was no significant divergent between two mitochondrial lineages.Our study has laid a good foundation for the further study of the paternal genetic characteristics of Chinese house mice and the evolution of Sry gene.