Study On The Relationship Between The Polymorphism Of Luteinizing Hormone β-subunit Gene And The High Productivity Of Xiaoweihanyang

Luteinizing hormone(LH) is an important gonadtropin,,LH plays a critical role in both male and female animal's productivity,especially,mammalian ovulation mainly relies on luteinizing hormone's action. Based on the genetic polymorphism of LH P gene,we try to link this candidate gene with the high productivity of Xiaoweihanyang(XWHY),to further provide scientific evidence for the basic genetic research on the XWHY'S high productivity.Applying the powerful PCR-SSCP technique and sequence to analyze the polymorphism of LH P gene,we divide our samples into 2 groups,one group is the blood sample of 243 XWHY with littering record;another group is the blood sample of 4 sheep breeds without littering record. The results are as the following:in the 709 bp 5'region,there are 2 loci,LHP5'-2 and LHP 5'-4,exhibit base difference. Locus LH P 5'-2 has 5 genotypes (AA AB,BB CC AC),3 alleles (A,BPC);Locus LHP 5'-4 has 3 genotypes (AA AB AC),also 3 alleles. Between the 2 exons (exon2 and exon3),exon 2 which has 2 genotypes (AA,AB ) and 2 alleles (A B ) has mutation. Among the sheep we tested,We don't do further polymorphism analysis on exon 1 as it only including a short untranslated region and partial signal peptide sequence. On the contrary,we cloned and sequenced fragments of 5'region which include 2 mutation loci and 1 exon which has 1 mutation locus. Our sequence results show that,in LHP5'-2,there are mutations A-G(-424)and T - C(-271);in LHP 5'-4,there are mutations G-A(-6)and C -G(+53);in exon2,there is 1 mutation G-C (+332) .By running a popular analysis tool TFSEARCH verl.3,we studied the potential 5' cis regulatory elements and factors binding to the 5'-region,and found the different regulatory elements of pre-mutation and post-mutation. The mutation caused the different potential binding transcription factors,especially the sites A -G(-424)and T- C(-271 )located in LH P 5'-2. Additionally,the mutation in exon 2 causes the Glycine being replaced by Alanine,but there is no difference in terms of the secondary structure between pre- and post-mutation.Among the XWHY with littering record,Least squares analysis show that the times of sheep produced had significant effects on the productive trait;different genotypes of LH P 5'-2 also have significant effects on productive trait. Among the 4 breeds of sheep,using X2 analysis show that different genotypes of loci LHP 5'-2 and exon2 reach significant level among the breeds. According to all of our results,we conclude that the polymorphism of LH P 5'-2 probably associate with the sheepXWHY productive trait.