The Complete Mitochondrial Genome Sequence Of The Chinese House Mice (Mus Musculus)

The house mouse has been attached with much attention for being an important modelorganism. Plentiful resources of house mice distribute in China, where many kinds oftopography exist in vast territory. However, the history of diffusion and migration of housemice has not been extensively studied, and the relationship between wild house mice andlaboratory strains was also less understood. In this work, we determined the completemitochondrial genome sequence of20Chinese wild house mice by sequencing and assemblyof fragments amplified by PCR. The entire sequence was16,299-16,301bp in length, whichincluded13protein-coding genes,22tRNA genes, two rRNA genes, and two non-codingregions (the origin of light chain replication and a control region). Among them,8tRNAgenes and a protein-coding gene were coded in light chain, whereas the others were in heavychain. The genome shows AT preference with an AT content of63.1%. Specifically, ETAS1,ETAS2and CSB1-3exist in the control region and most of tRNA genes were predicated to befolded into tertiary structure. The MCMC tree was built with MCMC method, which revealedtwo routes for house mice migrating into China. One was the route of M.m.musculus: enteredChina from Kazakhstan, passed though Hefeng, Urumqi, and Hanzhong, Changzhi, diffusedto northeast China at last; the other one was M.m.castaneus’s migration route, M.m.castaneuscame into China Yunnan province from Viet Nam, and migrated to Guangxi, Guizhou andJiangxi province. The divergence time was also estimated from the tree, with divergence timeof wild M.m.musculus18,100years, the wild M.m.castaneus11,750years, and the laboratorystrains of M.m.domesticus’s75-100years. A phylogenetic analysis using Bayesian methodsrevealed the laboratory strains’ maternity, which derived principally from M.m.domesticus,with a smaller contribution from M.m.musculus and M.m.castaneus. The analysis alsorevealed M.m.domesticus diverged at the earliest, with M.m.musculus and M.m.castaneusshowed more close relationship. The result also determined that M.m.demesticus was the mainmaternal origin of laboratory strains. Finally, we did a comparative analysis of thecharacteristics of the mitochondrial genome of wild and lab mice, the result showed that thehuge differences in living conditions and effective number of groups led to a tremendousdifference in their evolutionary rate of protein-coding genes and the sequence polymorphisms.Our research provided a conclusive experimental evidence for the migratory history of Chinese house mice, and also showed an important research data of the comparative analysisof the mitochondrial genome of wild and lab mice.