Gene polymorphism in a population of Charolais beef cattle using DNA-markers

Abstract

Aim. To study the polymorphism of genes, associated with resistance to different diseases (TLR1, TLR4, SLC11A1, TLR1, TLR4, IFNGR2, SLC11A1, TNFα, and MBL1) in the population of Charolais beef cattle. Methods. The studies were conducted using the methods of polymerase chain reaction and the restriction fragment length polymorphism (PCR-RFLP); the artificially created restriction site-PCR (ACRS-PCR) was used to study the polymorphism of gene MBL1. Results. In the population (n = 100) of Charolais cattle, genes TLR1, IFNGR2, SLC11A1, TNFα, and MBL1 were polymorphic, while TLR4 was found to be monomorphic by three mutant variants (8732G>A, 8834G>C, and 2021C>T). BclI-polymorphism of the first exon was used to determine the excess of heterozygous animals (81.8 %); there were no animals homozygous by allele A. By polymorphism of locus SLC11A1 for SNP6 (7808A>T), we deter- mined complete domination of the frequency of allele A over T (0.985 vs 0.015), no animals, homozygous by allele TT, were found. As for SNP5 7400C>G, there were no animals homozygous for allele G; the ratio of alleles C and G was 0.79 and 0.21, respectively. By locus IFNGR2 (1008A>G), we determined the prevalence of the frequency of al- lele A over G (0.745 vs 0.255); the animals with genotype AA were the most common. As for gene TNFα (–824A>G), we determined a two-fold prevalence of the frequency of allele G over A due to a higher number of animals with geno- type GG (39 %). Some 50 % of the animals were heterozygous for this gene.By locus MBL1,we found the prevalence of the frequency of allele G (StyI-) as compared to A (StyI+) due to a considerable number of homozygous animals GG (64 %). The percentage of homozygous animals was 37.8 %. Conclusions. General characteristics of genetic variability of the Charolais beef cattle population were determined for the loci TLR1, TLR4, IFNGR2, SLC11A1, TNFα, and MBL1. As for SNP6 7808A>T of locus SLC11A1, we have determined the final stage of allele A fixation, by the results of which the gene will become completely monomorphic by this mutation. The results of the analysis of the ratio between the frequencies of alleles and genotypes by the revealed polymorphic markers demonstrated that it is unreasonable to use animals with different allelic variants of genes TLR1, IFNGR2, SLC11A1 in further studies on the search for associations with the manifestation of economically valuable traits in Charolais beef cows of the experimental population due to insufficient number of animals with different genotypes. For loci TNFα and MBL1, we found enough animals with different genotypes to conduct further association studies. The deviation from the genetic Hardy-Weinberg equilibrium was observed for the loci TLR1, SLC11A1 (7400C>G), and MBL1 in the population.