Tissue Expression,polymorphism Of GnRH,FSH,LH And Their Receptors Gene And Their Association With Prolificacy In Sheep

Reproductive traits are one of the most important economic traits of sheep.Increasing the number of lambs per litter is an important way to improve economic efficiency.To study candidate genes about sheep prolificacy has important theoretical and practical significance for improving lamb traits in sheep.With the advancement of science and technology,many candidate genes related to sheep prolificacys have been discovered one after another,making it possible to use molecular markers to select sheep traits in production.The real-time fluorescence quantitative PCR(qPCR)method was used to detect the expression of the GnRH,FSH,LH and its receptor genes in reproductive tissues and brain tissues of six Small Tail Han sheep(three polytocous and three monotocous ewes from the FecB ++ genotype)in this study.The 380 Small Tail Han sheep and total 380 for Small Tail Han sheep,Tan,Sunite,Cele Black,Hu and Prairie Tibetan sheep were selected and Sequenom MassARRAY?SNP assay was applied to genotype 10 single nucleotide polymorphism sites(SNPs)of GnRH,GnRHR and LHR genes.Then the association was analyzed between GnRH,GnRHR and LHR and litter size in Small Tail Han sheep.The results were as followings:1.The results showed that GnRH gene was expressed in the hypothalamus,ovary and uterus tissues.Among them,GnRH was highly expressed in hypothalamus;GnRHR gene was expressed in the brain,cerebellum,hypothalamus,ovary,uterus and pituitary tissues.Among them,GnRHR was highly expressed in pituitary.The expression of GnRH gene in ovary,hypothalamus and uterus of polytocous Small Tail Han ewes was extremely significant higher(P<0.01)than that of monotocous ewes;The expression of GnRHR gene in cerebellum,hypothalamus,ovary,uterus and pituitary of polytocous Small Tail Han ewes was extremely significant higher(P<0.01)than that of monotocous ewes.FSHβ gene was expressed in brain,cerebellum,hypothalamus,ovary,uterus,oviduct and pituitary tissues.Among them,FSHβ was highly expressed in hypothalamus and ovary;FSHR gene was expressed in the brain,ovary and pituitary tissues.Among them,FSHR was highly expressed in ovary.The expression of FSHβ gene in hypothalamus,ovary,uterus,oviduct and pituitary of polytocous Small Tail Han ewes was extremely significant higher(P<0.01)than that of monotocous ewes,the expression of FSHR gene in ovary and pituitary of polytocous Small Tail Han ewes was extremely significant higher(P<0.01)than that of monotocous ewes.LHβ gene was expressed in brain,cerebellum,hypothalamus,ovary,uterus,oviduct and pituitary tissues.Among them,LHβ was highly expressed in pituitary;LHR gene was expressed in the brain,hypothalamus and ovary tissues,and highly expressed in ovary.The expression of LHβ gene in hypothalamus,ovary,uterus,oviduct,pituitary,cerebellum and brain of polytocous Small Tail Han ewes was extremely significant higher(P<0.01)than that of monotocous ewes.The expression of LHR gene in ovary,brain and hypothalamus of polytocous Small Tail Han ewes was extremely significant higher(P<0.01)than that of monotocous ewes.2.From genotyping,we found the genotype frequencies and allele frequencies of the g.40001529C>T and g.40001530A>G SNPs in the GnRH gene and g.83379464C>G SNP in the GnRHR gene were not significantly different between uniparous and multiparous sheep(P>0.05);The genotype frequencies and allele frequencies of the g.75747646C>T 、 g.75748150A>G 、 g.75748191A>T and g.75748200T>A SNPs in the LHR were high significantly different between monotocous and polytocous sheep breeds(P<0.01);g.40001529C>T and g.40001530A>G SNPs in the GnRH gene showed low polymorphism in all sheep breeds(PIC<0.25);g.83379464C>G in the GnRHR showed moderate polymorphism(0.25<PIC<0.5)in Cele Black Sheep and low polymorphism in other sheep breeds(PIC<0.25);7 SNPs in the LHR gene showed moderate polymorphism in most sheep breeds(0.25<PIC<0.5),and the result of chi-square test showed that all of SNPs in the 3 genes were at Hardy-Weinberg equilibrium in most sheep breeds(P>0.05).3.Association analysis showed that these 3 SNPs in GnRH and GnRHR genes were not significantly correlated with litter size in Small Tail Han sheep(P>0.05).g.75741060A>C SNPs in the LHR gene was significantly correlated with litter size in Small Tail Han sheep(P<0.05),and g.75747421A>C and g.75748150A>G SNP were extremely significantly correlated with litter size in Small Tail Han sheep(P<0.01).Conclusion: The expression profiles of GnRH,FSH,LH and its receptor genes in the reproductive axis of Small Tail Han sheep were obtained;The population genetic structure of 10 candidate SNPs(g.40001529C>T、g.40001530A>G、g.83379464C>G、g.75741060A>C 、 g.75747399C>G 、 g.75747421A>C 、 g.75747646C>T 、g.75748150A>G、g.75748191A>T 和 g.75748200T>A)in GnRH,GnRHR and LHR genes in different sheep breeds was studied.Association analysis showed that LHR gene g.75741060A>C,g.75747421A>C and g.75748150A>G SNPs were significantly associated with reproductive traits in sheep;it lays a foundation for the further development of molecular genetic markers for the development of good traits in sheep.