Study On Inhibin β_A And Inhibin β_B As Candidate Genes Of Prolificacy In Sheep

Inhibins are dimeric glycoproteins that have primarily been studied for their roles in antagonism of activin-mediated release of follicle-stimulating hormone (FSH) from gonadotropes of the anterior pituitary. Inhibins were shown to be disulphide-linked dimers which shared a common α-subunit and differed on the basis of a β-subunit.Inhibin β_A (INHBA) gene was studied as a candidate gene on the prolificacy of Small Tail Han sheep. Single nucleotide polymorphisms of INHBA gene were detected in both high fecundity sheep breeds (Small Tail Han sheep and Hu sheep) and low fecundity sheep breeds (Dorset sheep, Texel sheep and German Mutton Merino sheep) by PCR-SSCP. The results indicated that there were polymorphisms in the amplified region for three primer pairs, no polymorphism in the amplified region for other four primer pairs. The result of x~2 fitness test of primer INHBA2-2 indicated that Small Tail Han sheep, Texel sheep all kept in Hardy-Weinberg equilibrium (P>0.05), but Hu sheep were significantly biased from Hardy-Weinberg equilibrium (P<0.05), German Mutton Merino sheep were high significantly biased from Hardy-Weinberg equilibrium (P<0.01). There was no polymorphism in Dorset sheep. For primer INHBA1-2, there was a mutation (G→ A) at 50 bp of the amplification region of primer INHBA 1-2 of the INHBA gene in BB genotype compared with AA genotype. This mutation did not result in amino acid change. The ewes with genotype BB had 0.26 (p>0.05) lambs more than those with genotype AA in Small Tail Han sheep.The result of x~2 fitness test of primer INHBA2-2 indicated that Dorset sheep was kept in Hardy-Weinberg equilibrium (P>0.05), but German Mutton Merino sheep were high significantly biased from Hardy-Weinberg equilibrium (P<0.01). There was no polymorphism in Small Tail Han sheep, Hu sheep and Texel sheep. For primer INHBA2-2, there was a mutation (C→ T) at 142 bp of the amplification region of primer INHBA2-2 of the INHBA gene in HH genotype compared with GG genotype. This mutation resulted in amino acid change (serine→ leucine). Only genotype GG was detected in prolific Small Tail Han sheep and Hu sheep and Texel sheep of low fecundity, three genotypes (GG, GH, HH) were detected in Dorset sheep and German Mutton Merino sheep of low fecundity.The result of x~2 fitness test of primer INHBA2-4 indicated that Small Tail Han sheep, Hu sheep and Texel sheep was kept in Hardy-Weinberg equilibrium (P>0.05), but Dorset sheep and German Mutton Merino sheep were high significantly biased from...