Genetic Variation Analysis Of Catsper1 And ACTG2 Genes And Its Association With Sperm Quality In Bulls

Catsper, a cation channel of sperm which was discovered recently, was exclusively expressed in testis and epididymis and which plays a role of regulation in sperm hyperactivation. Compared to non-hyperactivated sperm, there was a significantly higher mean percentage of normal forms and significantly lower percentage with small acrosome, large head and tail defects in hyperactivated spermatozoa. Actin is one of the most abundant and conservative proteins in cells. Being a major structural component of the cytoskeleton, actin has very important cytologic physiological function in eukaryotes. In recent year,γ-actin(ACTG2) was investigated as candidate genes on the basis of its known functions in boar, for its possible association with sperm concention, motility, abnormal sperm rate and the fertility traits, non-return rate and number of piglets born alive.With the PCR-SSCP (polymerease chain reaction-Single Strand Conformation Polymorphism), genetic polymorphism of Catsper1 gene's 4 sites and ACTG2 gene's 2 sites in 40 bulls were detected in this study. Polymorphism fragmrents of Catsper1 gene and ACTG2 gene were cloned and sequenced in order to axcertain variant loction of mutational sites and base type. The correlativity between these polymorphism sites and bovine semen quality traits was analysed with records of semen quality determination, which purpose is to providing foundation of mocular biology for breeding selection.The results based on PCR-SSCP revealed that five mutational sites of Catsper1 gene and three mutational sites of ACTG2 gene in the population of Simmental and Charolais. The results of cloning and sequencing indicated that, in the Catsper1 gene, Exon-1-1 sites polymorphism was dued to base mutation of C to T in position -65 and base mutation of T to C in position -286 in the region of 5'UTR. Exon-1-2 is G to A in position 144 which lead to the amino acid substitution of G (Gly) for S (Ser) in the reigon of exon-1 and these mutations were linked together. Intron-1 is C to T in position 167 in the reigon of intron-1. 3'UTR is C to T in position 167 in the reigon of 3'UTR. In the ACTG2 gene, exon-5 sites polymorphism was dued to base mutation of C to T in position 6 and base mutation of A to G in position 102 in the reigon of intron-5. Exon-6 is A to G in position 110 in the reigon of exon-6. Correlativity between Catsper1 gene and ACTG2 gene's genetic polymorphism and semen quality traits was analysed with SPSS 12.0 software. The results indicated that, in Catsper1 gene, the fresh sperm motility, frozen sperm motility, percentage of acrosome integrity in fresh semen, and percentage of acrosome integrity in frozen semen between type-AA and type-AB were significantly different rate on 5'UTR site(P<0.05). On exon-1-2 site, the fresh sperm motility, frozen sperm motility, percentage of acrosome integrity in fresh semen, and percentage of acrosome integrity in frozen semen between type-CC and type-CD were significantly different rate. On the intron-1 site, the ejaculate volume and percentage of deformity in frozen semen had a significantly different rate between type-EE and type-EF(P<0.05). The sperm concentration and percentage of living in fresh semen with type-aa were significiently different with type-ab on 3'UTR site(P<0.05). In ACTG2 gene, the sperm concentration, fresh sperm motility, percentage of deformity in fresh semen and percentage of living in fresh semen with type-ee were significiently different with type-ff and type-ef (P<0.05), and the percentage of living in frozen semen with type-ee had a extreme significant difference with type-ff and type-ef(P<0.01) on exon-6 site. It coult be preliminarily deduced that Catsper1 gene and ACTG2 gene were probably major genes or QTL linked genes which associated with semen quality traits in bulls.