| Artiodactyla(Phylum Chordata:Mammalia) have been a tremendous and thriving group in population quantity in Ungulata since Late Eocene. With the evolution of vetebrates, the wildlife are confronted with great challenge because of the emerging pathogens. Toll like receptors(TLRs), mediating the adaptive immune in post-infection by pathogens, are an important member of innate immune system. Investigating the evolutionary dynamics of TLRs in Artiodactyla will help understand how the natural pressure of the complicated field environment influence the subsistence of the wildlife.With the aid of standard PCR and sequencing technology, we sequenced the coding sequences of target genes from 8 species in Artiodactyla, including Argali (Ovis ammon), sika deer (Cervus nippon), impala (Naemorhedus goral), forest musk deer (Moschus berezovskii), sambar (Rusa unicolor), muntjac (Muntiacus reevesi), takin(Budorcas taxicolor) Concluding the sequences from the public databases, including Bactrian Camel (Camelus ferus), alpaca (Vicugna pacos), pigs (Sus scrofa), cattle (Bos taurus), goat (Capra hircus),sheep (Ovis aries), buffalo (Bubalus bubalis), yak (Bos mutus), Tibetan antelope (Tibetan Antelope),coding sequecnes of TLR1-4 from 17 species were obtained. The characteristics and homologies between sequences were counted and calculated using MEGA5.0 and Lasergene, respectively; The protein subdomain were predicted by SMART program; The neighbor joining(NJ) tree and maximum likelihood(ML) tree were reconstructed by the corresponding methods; The evolutionary dynamics of target genes within Artiodactyla were estimated by PAML.And we obtain the following main results:1) Coding sequences of TLR1-4, harboring 2196bp,2352bp,2715bp, and 2523bp, from 8 species were first reported; We Download and gained the sequences of other species in GenBank, But the sequence of Bactrian Camel and alpaca are different from the Other species;2) The analysis of homologysequences which have been measured by us,with the other species have been reported in GeneBank of the TLR receptor gene sequences,and found that all four genes are conserved and the similarities between sequences are above 85% in TLR4 but The homology of TLR1 and TLR3 gene between Two species of camel Branch and the other families is lower in about 70%;3) In TLR protein structure comparison, we selected the TLR 1-4 divisions of the various species to predicted its domains.And found The sub-domain prediction revealed that the number of LRRs varied between different species in the same gene, suggesting that the habitat environment may influence the number of LRRs. The difference of the number of LRRs in different genes of the same speices showed that the ligands number of each genes may contribute to the difference;4) Phylogenetic analysis by constructing the system ML tree and the N-J showed the same genes from different species were assemblied together. TLR1 and TLR2 are closed to each other in genetic relationship, and then separate with TLR3 and TLR4;5) dN/dS values of each branches estimated by PAML shows that selection pressure of TLR1,2,3, and 4 genes are different, which may be associated with their own functions. The overall tendency of selection pressure of target genes are domianted by purifying selection, but some branches were also found some relaxation of selective pressur. And the sites were identified by the TLR4 gene model has 13 amino acid sites occurred in positive selection.The study of innate immune-related genes in Artiodactyla exhibited adaptive evoluton from the perspective of molecular evolution. On the basis of biomedical, this study is to better understand the mechanisms of the development of different diseases. |
PDF Full Text Request