Studies On Deficiency Detection And SNPs Of Exon 12 Of Plasma Thromboplastin Antecedent Gene In Bovine

Plasma thromboplastin antecedent(FXI)made by liver and thromboblast was a glycoprotein in which saccharide content was 5%.FXI expressed little in pancreatic gland, nephridial tissue and thromboplastid.It played important role in animal endosomatic blood clotting metabolism process.To detect FXI gene deficiency,162 heistein cows were chosen.Based on the FXI gene sequence in GenBank,a pair of primers was designed for cloning exon 12,SNPs in exon 12 were tested by PCR-SSCP,and the different genotypes associated with milk output,K ionic concentration,body-cell number in milk were analyzed.The results showed as follows:1.Partial fragment of exon 12 was cloned and sequenced.The results showed that there were 2 genotype carriers in 162 cows,in which mutant gene carrier was caused by 76bp inserted sequence[AT(A)(28)TAAAG(A)(26)GGAAATAATAATTCA]at 188bp site.The mature plasma thromboplastin antecedent XI protein in mutant gene carrier lacked amino acids encodedby exon 13,14 and 15 so as to lack of FXI activity.2.SNPs in exon 12 of FXI gene were tested by PCR-SSCP.There were 3 genotypes (AA,AB and BB)in 162 Holstein cows.Sequencing revealed that a A→T mutation at 131 bp in exon 12 of FXI gene compared B with A.This mutation resulted in amino acid Asn→Ile,which resulted in the hydrophilicity weaken,surface probability of amino acids degraded,and average charge was unchanged.3.Homologies of FXIgene among other 7 species were analyzed using DNAStar 5.01.The results indicated homology between cow and dog was 81.5%,lowest with house mouse.The homologies between another inwestigated animal were from 47%to 70%.4.Genotype frequencies of AA,AB and BB in Holstein cows were 0.3580,0.3087 and 0.3333,frequencies of allele A and B were 0.5123 and 0.4877 respectively.Population heterozygosis degree was 0.4997,effective allele number was 1.9988,and polymorphic information content was 0.3749.5.Relative analysis between genotypes and milk output indicated that average milk outputs of 4 months among different genotypes differed significantly,In the 162 cows,the milk output with genotype AA had 1.647(P＜0.05)or 1.257(P＜0.05)more than those with genotype AB or BB,respectively;the milk output with genotype BB had 0.390(P＞0.05) more than those with genotype AB.K ionic concentration and body-cell number among different genotypes were not significant.