Studies On Polymorphism In Exon2of The BLB Gene Of The Yellow-bellied Tragopan(Tragopan Caboti) And Adaptive Evolution Of The BLB Gene In Six Species In Phasianidae

The yellow-bellied tragopan(Tragopan caboti) distribution is relatively narrow in our country,and the scale of population is decreasing sharply,The yellow-bellied tragopan has been listed as a first-grade state protected animal in China.By obtaining the major histocompatibility complex genetic polymorphism of this gene to reveal the genetic background of the species,which can provide the basis for the development of conservation strategies.So far has not seen the report about the polymorphism of BLB exon2in the yellow-bellied tragopan,also any report about the BLB exonl-4in the silver pheasant(Lophura nycthemera),the Reeves’s Pheasant(Syrmaticus reevesii),the Lady Amherst’s Pheasant(Chrysolophus amherstiae),the Crimson-bellied Tragopan(Tragopan temminckii),the Chinese Barred-backed Pheasant(Syrmaticus ellioti).MHC genes of these species for disease resistance and fertility has great relevance.The research firstly obtained BLB exon2gene sequences from the yellow-bellied tragopan(Tragopan caboti),the BLB exonl-4from the above of birds,and by using the biolo-gical software analysed these nucleotide sequences,to further study the function of the birds MHC gene families lay the foundation.It also can provide theoretical basis for species conser-vation and breeding for disease resistance.The results are as follows:1.14allele sequences of BLB gene are obtained from164clone sequences in10individuals of the yellow-bellied tragopan. The nucleotide mutation analysis shows that mutations are mainly in the transversion. It shows that the ratio of average non-synonymous substitution rate (dN=0.1593) and average synonymous substitution rate (dS=0.1448) is1.100,>1, positive selection.It shows that dN/dS>1in the silver pheasant,the Golden Pheasant,the Reeves’s Pheasant,the Lady Amherst’s Pheasant,the Crimson-bellied Tragopan,positive selection;but the dN/dS<lin the Chinese Barred-backed Pheasant,negative selection.2.The analysis of genetic diversity of the yellow-bellied tragopan by14alleles of BLB exon2sequence shows that the genetic diversity is low and the species has weak disease resistance.3.According to phylogenetic trees, network diagrams and genotypes show that there are at least three BLB loci in the yellow-bellied tragopan.4.22haplotypes of BLB exonl-4are defined from86sequences from11individuals in6species of phasianidae birds.The length of coding region is629bp,four exons and3introns.5. The phylogenetic tree reveals the evolve in a species-species and not a locue-specific manner based on BLB exon2in6species of Phasianidae birds,but intron2is.6.Phylogenetic trees of BLB exon2genes from fourteen species in Galliformes and BLB exon2-4genes from eleve species in Phasianidae show that BLB genes in Galliformes birds have transspecies evolutionary phenomena.