Association Between Polymorphisms Of PRL And POU1F1 Genes And Milk Production Traits In Chinese Holstein Cattles

POU1F1,a member of the POU family,activates gene expression for thyrotropin (TSH)and prolactin (PRL) and growth hormone (GH) but also has a role in pituitary cell differentiation and proliferation. Mutations in the POU1F1 lead to anterior pituitary hypoplasia. The inhibition of POU1F1 synthesis leads to a marked decrease in expression of PRL and GH and to a dramatic decrease in proliferation of cell lines producing PRL and GH. Because PRL and GH are essential for mammary gland development and milk yield, POU1F1 has potential as a marker for genetic variation in yield traits. Prolactin has 300 different biological functions.In mammals,prolactin regulates mammogenesis,lactation,development of sexual gland,immune function,body stress action and somatic cell division and proliferation and so on. PRL and POU1F1 are potential candidate genes for bovine milk performance traits. SNPs in PRL and POU1F1 may have effects on milk performance traits.The study try to detect the novel SNPs in PRL and POU1F1, to find the possible association of the polymorphism and milk performance trait and also to investigate the possible association of the polymorphism at PRL and POU1F1 loci with milk performance traits.The study included 1000 DNA samples of Chinese Holstein cows. We amplied primers by nested PCR technique, all genotyping were identified by the methods of PCR-RFLP and CRS-RFLP. Software Primer Premier 5.0 and Oligo 5.0 were used to design all the primers.The associations between variants of the genes and milk performance traits were analyzed by the GLM procedure (SAS 8.1).G/C SNP were identified at nucleotide 1178 in exon2 of POU1F1 gene, it can be digested by restriction endonuclease Hha1,GG,GC and CC three genotypes were detected, The genotype frequencies of GG,GC and CC were 93.054%, 2.554% and 4.392% respectively in 979 cattles, the gene frequencies of G and C were 94.331% and 5.669% separately. The cows with genotype GC showed higher milk yield,higher fat yield and higher protein than those with genotypes CC(P < 0.01). There were no significant differences between the individuals of GC and CC for fat percentage and protein percentage (P>0.05).Two novel SNPs were identified in 5?-flanking regulatory region of PRL(GenBank acc. no. X16641.1), there is a A/G transition at position 906, a A/T transition at position 1134. Applied Hha1 restriction endonuclease, we got three genotypes:AA,AG,GG.The genotype frequencies of AA,AGand GG were 32.80%, 46.12% and 21.07% respectively in 719 cattles, the gene frequencies of A and G were 55.86% and 44.14% separately. The cows with genotype AA showed higher milk yield than those with genotypes GG (P < 0.05), but the cows with genotype GG showed higher protein percentage than those with genotypes AA(P < 0.05). There were no significant differences between the individuals of GG and AA for fat yield and protein yield (P>0.05).The results did not provide evidence of association of PRL and POU1F1 polymorphisms with the evaluated traits.