Abstract:

【Objective】 Genetic polymorphisms of HSL gene in yak were detected in order to provide a theoretical foundation for further studying on revealing the genetic differentiation among yak populations, association analysis on yak meat quality traits and polymorphism, location and expression regulation of yak HSL gene, and so on. 【Method】 Polymorphisms of the partial exon I of HSL gene in 92 heads of yaks from 3 populations (Jiulong yak, Maiwa yak, and Bazhou yak) were analyzed by SmaⅠ-RFLP. The sizes of allele frequencies and genotype frequencies were calculated and the Chi-square test was analyzed by SPSS soft, and the genetic polymorphism parameters (including homozygosity, heterozygosity, the effective number of alleles and polymorphism information content) were analyzed on this loci. 【Result】 SmaⅠpolymorphism was observed in the partial exon I of yak HSL gene, and 3 genotypes (AA, BB, AB) were detected. AA and BB were observed in all the 3 populations, but BB genotype was only detected in Bazhou yak. AA was the genotype with highest frequency in Jiulong and Maiwa yak populations but it was AB genotype in Bazhou yak. The predominant allele was allele A, whose frequency was higher than B in all the 3 populations. Sequencing analysis showed that a mutation (G→A) occoured at the 70th site (numbering from the 5′ end of the PCR fragment) of exonⅠof HSL gene, which resulted in an amino acid change from Gly to Arg. Compatibility test indicated that Jiulong yak, Maiwa yak and Bazhou yak were all in the Hardy-Weinberg equilibrium at the SmaⅠsite. Independence test indicated that the genotype distribution was obviously different between Jiulong yak and Maiwa yak, and it was extremely obviously different between Jiulong yak and Bazhou yak, while it was not obvious between Maiwa yak and Bazhou yak. 【Conclusion】 SmaⅠpolymorphism was observed in the partial exon I of yak HSL gene, which resulted from a single base mutation (G→A), and the mutation resulted in an amino acid change from Gly to Arg. At the SmaⅠ site, Jiulong yak, Maiwa yak and Bazhou yak were all in the Hardy-Weinberg equilibrium, but the genotype distribution was obviously different between Jiulong yak and Maiwa yak, and it was extremely obviously different between Jiulong yak and Bazhou yak, while it was not obvious between Maiwa yak and Bazhou yak.

Key words: yak, HSL gene, PCR-RFLP