| The single nucleotide polymorphisms(SNPs) within the coding regions of CXCR1&CXCR2 gene in Holstein cattle were investigated by nested-PCR,DNA sequencing and CRS-PCR.Sequencing results verified that three SNPs had been identified, which they were 735(C/G),816(C/A) and 819(G/A).At the same time,five new SNPs 980(G/A),995(G/A),1008(C/T),938(C/T) and 959(C/T) that in CXCR1 & CXCR2 coding region have been found.But only three of them resulted in amino acids alteration in CXCR1,which were 735(C/G) Arg422His,980(G/A) Arg327Lys,995(G/A) Arg332His.Genetic polymorphism testing found that the 8 loci in Holstein cattle showed moderate polymorphism(0.25＜PIC＜0.5),and polymorphic information content of the groups is distributed more evenly;only 995(G/A) loci of Yellow cattle performance low polymorphism(PIC=0.2257).Hardy-Weinberg testing showed that both 816(A/C) and 995(A/G) loci of the Holstein cattle do not meet Hardy-Weinberg equilibrium(P＜0.05), which indicated this two loci impaction by mutations drift,selection or migration,so the groups need further stabilization.The 819(A/G),980(A/G) and 959(C/T) loci in Yellow Cattle were not balanceable(P＜0.05).In Black cattle only the 959(C/T) loci did not did not balanceable perform(P＜0.05).The association of CXCR1 & CXCR2 gene polymorphism with SCS in Chinese Holstein cattle was significant,and the 3 loci of 735(C/G),816(C/A),819(G/A) had a significant correlation with somatic cell score,which are approximate with the conclusions of Youngerman.At the same time,the loci 938(C/T),959(C/T) of CXCR2 gene had a significant relation with the somatic cell score in dairy cattle.The locus 735(C/G), 816(C/A),980(G/A),1008(C/T),938(C/T) and 959(C/T) significantly or extremely significantly affected 305d milk yield.Genotype comparison of CXCR1 gene mutation with corresponding factors found that SCS of CC,CG genotype cattle was significantly lower than GG genotype in 735(C/G)loci.The comparison of 305d milk yield found that CC genotype was significantly higher than GG genotype cattle.The SCS of AA genotype was significantly higher than AC and CC genotypes in 816(C/A) locus of dairy cattle; corresponding to 305d milk yield,can be found AA genotype was significantly lower than the other two genotypes.The somatic cell score of heterozygote AG cattle was significantly higher than the GG genotype in the 819(A/G) locus,without significant difference in milk yield.In CXCR2 gene,the SCS of CC genotype was significantly higher than CT and TT genotypes cattle in 938(C/T) loci,305d milk yield was extremely significantly lower than CT and TT genotypes in dairy cattle.In 959(C/T) locus,CC genotype cattle had a significantly higher SCS than CT genotype cattle,and CT genotype cattle had a significantly higher 305d milk yield than CC and TT genotypes cattle.Using Phase as a haplotype frequency analysis software tool,45 kinds of haplotypes in Holstein cattle was found in the CXCR1 gene,4 kinds of haplotypes exist in CXCR2 gene,and 149 haplotypes were found in combination analysis of the both genes. |
