Avaliação dos efeitos de polimorfismos e da origem parental do alelo na expressão de genes candidatos à característica maciez da carne em bovinos da raça Nelore

Abstract

Tenderness is the main trait appreciated by consumers of bovine meat, however Nellore animals that comprise the largest part of Brazilian cattle, have lower tenderness when compared with European animals. In this way, it is essential understand the variability of genes associated to tenderness as well as their mechanisms of allelic expression, considering that deviations of expression depending on the parental origin of the allele have been described for some genes, and these phenomena must be understood to be incorporated in animal breeding programs. Therefore, the aim of this study was to evaluate the variability of SNPs in candidate genes for tenderness and investigate the expression pattern of their alleles. For this purpose, genotypes of SNPs in CAST, CAPN1, DGAT1, leptin, KCNJ11 and IGFBP3 genes were determined in 30 sires, in which the genes DGAT1, leptin and IGFBP3 were not polymorphic. After this, polymorphic SNPs in population of sires were genotyped in their offspring by TaqMan® assay in real time PCR, followed by allelic expression analysis. In the expression analysis, to discriminate each allele of the gene it was utilized one SNP, or two in the case of KCNJ11. All genes presented biallelic expression in adult muscular tissue. However, with exception of CAPN1 for which the allelic expression difference was not significant, the allelic expression ratio was significantly different of 1 for SNP of CAST (1.3±0.03) and the two SNPs of KCNJ11 SNP 2126T>C (1.2±0.04) and SNP 2942C>T (1.46±0.04). Differential allelic expression (DAE) found in SNP 2126T>C of KCNJ11 and in CAST were not influenced by parental origin of allele, but the differences in allelic expression for SNP 2942C>T of gene KCNJ11 showed parental origin effect and influence by genotype of the other SNP of KCNJ11. It was conclude that the CAST, CAPN1 and KCNJ11 are polymorphic in this population, they are not imprinted, but CAST and KCNJ11 showed differential allelic expression.