Polymorphism Of GDF9 Gene And The Relationship With Prolificacy In Guizhou White Goat

Livestock breeding trait is one of important economic traits,hence the litter size is crucial to successful reproduction in livestock,It's difficult to improve the properties according traditional methods because the number of goat lambing is low genetic traits(only 0.10),So finding control mechanism for ovulation rate and litter size of the major genes(or mutation) aroused widespread concern of breeding goat jurists throughout the world.In recent years,some major genes controlling prolificacy in parts of sheep are fond,but their precision position and genetics function in most of sheep and goat species have no reports,and Still need to penetrating research.The menthods of gene engineering are used to colone the fragment of exon 2 in GDF9 of Guizhou White goats.The length of exon 2 in GDF9 of Guizhou White goats is 965bp,which coden 321 amino acids containing 135 mature peptide.By comparing to similar Jining qing goat,sheep,human,and opossum sequences,the deduced aminoacid(AA) sequence is respectively 99%,99%,84%and 74% homologous to the known mammalian sequences above,the homology in Guizhou White goats is highest.The polymorphism of GDF9 gene of Guizhou White goats were detected by restriction fragment length polymorphism(RFLP),the results showed that FecG~H mutation(S77F) was not detected in all of the samples.The polymorphism of mature peptide encodeed by exon 2 of GDF9 gene in Guizhou White goats was detected by SSCP.The results showed that heterozygous AB genotype was detected in exon 2 ofGDF9 gene from five female and three male goats by SSCP.All of the five female goats had record of more than three lambs at one pregnancy.Sequencing results confirmed that all of the eight AB genotype contain a mutation at 1189bp(G/A) in the coding region of GDF9 gene.The G/A mutation caused the substitution of valine to isoleucine at residue 79 of the coding region for mature peptide(V79I),which is only two residues away from the site of FecG~H mutation(S77F).It suggested that the mutation of G1189A in GDF9 gene might relate to the prolificacy of Guizhou White goats.