ABSTRACT
The PPARGC1A gene (peroxysome proliferator-activated receptor-gamma coactivator 1alpha gene) controls muscle fiber type and brown adipocyte differentiation; therefore, it is a candidate gene for beef quality traits (tenderness and fat content). Two SNPs (Single Nucleotide Polymorphisms) were identified within exon 8 by multiple alignment of DNA sequences obtained from 24 bulls: a transition G/A (SNP 1181) and a transversion A/T (SNP 1299). The SNP 1181 is a novel SNP, corresponding to a non-conservative substitution (AGT/AAT) that could be the cause of amino acid substitution ((364)Serine/(364)Asparagine). A Mismatch PCR method was designed to determine genotypes of 73 bulls and 268 steers for SNP 1181. Growth, slaughter and meat quality information were available for the group of steers. Allele A of SNP 1181 was not found in Angus. In 243 steers, no significant differences (P > 0.05) were found for either final live body weight, gain in backfat thickness in Spring, kidney fat weight, kidney fat percentage, Warner-Bratzler shear force at 7 days postmortem, intramuscular fat percentage or meat colour between genotype GG and AG. This SNP could be included in breed composition and population admixture analyses because there are marked differences in allelic frequencies between Bos taurus and Bos indicus breeds.
Subject(s)
Cattle/genetics , Polymorphism, Single Nucleotide , Transcription Factors/genetics , Animals , Base Sequence , Body Weight/genetics , Cattle/classification , Cattle/growth & development , Female , Gene Frequency , Genetic Variation , Genotype , Male , Meat/standards , Molecular Sequence Data , Phenotype , Polymerase Chain Reaction/methods , Sequence Analysis, DNA , Sequence Homology, Amino AcidABSTRACT
Leptin is a hormone that affects the regulation of feed intake, energy balance and body composition in mammals. Several polymorphisms in the bovine leptin gene have been associated with phenotypic variance of these traits. We evaluated two known single nucleotide polymorphisms (SNPs) in the leptin gene of 253 grazing Brangus steers. Brangus is a 5/8 Angus-3/8 Brahman composite. Data were collected during two consecutive growth/fattening cycles from two farms in southeast Buenos Aires province, Argentina. One of the markers is in the promoter region of the gene (SNP1) and the other is a non-synonymous polymorphism in exon 2 (SNP2). The traits that we evaluated were live weight gain in the spring, gain in backfat thickness in the spring, final live weight, final ultrasound backfat thickness, final ultrasound rib eye area, carcass weight and length, carcass yield, kidney fat, kidney fat percentage, backfat thickness, rib eye area, and intramuscular fat percentage. Both markers affected some meat traits; though the only significant associations were of SNP1 with ultrasound rib eye area and of SNP2 with carcass yield and backfat thickness. Under the same conditions as in the present study, leptin markers could be of help only as part of a larger genotyping panel including other relevant genes.
