Studies On Polymorphisms Analysis In 5'-flanking Region Of Bovine Prolactin Gene(bPRL) And Their Associations With Milk Traits In Chinese Holstein Dairy Cattle

Prolactin(PRL), a member of growth hormone/prolactin family,is anessential strand polypeptide type hormone secreted by animals'anteriorpituitary, PRL plays an important pole in promoting mammal mammary glanddevelopment, and milk production in the phase of lactation.Theirfore PRLgene can be chosen as a candidate gene for milk trait analysis in Holsteincows. The purpose of this study is to detect the genetic variations of the bovinePRL(bPRL) gene.Three hundred and thirty-seven Holstein cattles from Shandong and Beijing were used for the present experiment. PCR-SSCP andPCR-RFLP analysis were used to analyze genetic variations in PRL gene. Inaddition, 5'-flanking sequence including exon I and promoter region of bPRLgene had been cloned successfully.The relationship of bPRL genepolymorphism and milk traits was examined with General Linear Model(GLM)of SAS. The result were as follows:1. specific primer set P1 was designed to amplify a fragment of bPRL gene, aXbaI-RFLP polymorphism site was located in this 679bp fragment. This sitehad two alleles, designated as A and B. The G? C mutation was revealed bysequencing analysis. The distribution of different genotypes and alleles wereanalyzed in two populations. A chi-square analysis showed that the Shandongcattle population reached Hardy-Weinberg equilibrium(P>0.05), wherebyBeijing population was in disequilibrium(P<0.05).Both of them hadmiddle-level polymorphism(0.25山东农业大学硕士学位论文(2004)analysis showed that the Shandong cattle population reached Hardy-Weinbergequilibrium (P>0.05), whereby Beijing population was in disequilibrium(P<0.05). Both of them had intermediate polymorphism(0.25