Polymorphisms Of TGF-β1 And GDF9 Genes And Their Relationships With Prolificacy In Little-tailed Han Sheep

Livestock breeding trait is one of important economic traits. It's difficult to improve the properties according traditional methods because the number of sheep lambing is low genetic traits (0.03-0.1).Finding control mechanism for ovulation rate and litter size of the major genes (or mutation) aroused widespread concern of breeding sheep jurists throughout the world. Gene is a significant factor affecting fetal sheep. Different genetic variation of sheep ovulation rate provide an ideal model for exploring the mechanism of regulating follicle development and revealing gene controled ovulation, which make it possible to identificate major genes affecting the ovulation rate.In this study, transforming growth factor beta 1 (TGF-β1) and growth differentiation factor 9 (GDF9) as candidate genes for the Little-tailed Han sheep were did polymorphic analysis, in order to reveal the relationship between two kinds of cell factors and the sheep reproduction performance. The experiment selects 196 sheep for materials including Little-tailed Han, Tong, Tan and Oula, analysised the hereditary for TGF-β1 and the GDF9 in different sheep by PCR-RFLP and PCR-SSCP technology. The results were as follows:Firstly, analysised amplification fragment for 2-5, 6-7 exons of TGF-β1 gene, there were a polymorphic locus in 805bp sequence of 6-7 exon by PCR-SSCP.6-7 exon region was cloned and sequenced,which showed a mutation and revealed a AGAC deletion in upstream 294 of exon 7 of TGF-β1 gene (site 14 201 in gi76871756). The statistical result of genotype and gene frequency in different breeds showed that the genotype AB dominated in the Little-tailed Han sheep. the genotype BB was in majority in low-fecudity sheep. All the populations were in intermediate polymorphism. Meanwhile we forecasted the control element and protein binding sites in mutation point, The results showed AB had three activated protein transcription factor AP-1 (activator protein 1) comparing than genotype of AA and BB. The relationship of least squares means for litter size was AB >BB> AA in Little-tailed Han sheep, but difference among the three genotypes haven't differ significantly (P>0.05).Secondly, 4 pairs primers were designed to amplify frangment and PCR-SSCP in exon 2 of GDF9 gene in sheep, only finding one polymorphic locus in P2 primer. There were two base mutations (T→C in 558 and T→C in 692) in P2 primers among Little- tailed Han, Tong, Tan and Oula. Which showed a new mutation of T→C in 558 and T→C in 692 in four sheep breeds. The mutation caused 231-amino acid leucine turn into threonine,. The mutation in four sheep breeds were low polymorphism. The Little- tailed Han sheep ewes with genotype CC had 0.63 (P<0.05) lambs more than those with genotype CD, which differ significantly.Lastly, we analysised the correlation for polymorphic locus of TGF-β1 and GDF9 gene combined with the litter size of Little-tailed Han sheep. There are notable correlation between TGF-β1 genotypes and litter size (R=0.26621), GDF9 genotype and litter size (R=0.28839), no notable correlation between TGF-β1 and GDF9 gene polymorphic locus (R=0.13054) .