E. A. Navajas

Genomic variation and population structure detected by single nucleotide polymorphism arrays in Corriedale, Merino and Creole sheep

The aim of this study was to investigate the genetic diversity within and among three breeds of sheep: Corriedale, Merino and Creole. Sheep from the three breeds (Merino n = 110, Corriedale n = 108 and Creole n = 10) were genotyped using the Illumina Ovine SNP50 beadchip®. Genetic diversity was evaluated by comparing the minor allele frequency (MAF) among breeds. Population structure and genetic differentiation were assessed using STRUCTURE software, principal component analysis (PCA) and fixation index (FST). Fixed markers (MAF = 0) that were different among breeds were identified as specific breed markers. Using a subset of 18,181 single nucleotide polymorphisms (SNPs), PCA and STUCTURE analysis were able to explain population stratification within breeds. Merino and Corriedale divergent lines showed high levels of polymorphism (89.4% and 86% of polymorphic SNPs, respectively) and moderate genetic differentiation (FST = 0.08) between them. In contrast, Creole had only 69% polymorphic SNPs and showed greater genetic differentiation from the other two breeds (FST = 0.17 for both breeds). Hence, a subset of molecular markers present in the OvineSNP50 is informative enough for breed assignment and population structure analysis of commercial and Creole breeds.

Evaluación de panel SNP en genes candidatos de vías metabólicas para carne en Hereford

The phenotype-genotype associations of a panel of SNP markers selected from candidate genes related to the growth hormone GH/IGF1endocrine axis and the fatty acid synthesis and desaturation SCD/SREBP1 pathways, were examined. Phenotypes of interest were carcass composition, meat quality and fatty acid profiles of intramuscular fat in Hereford steers under different feeding treatments during the growth and finishing stages. Variables were adjusted for the effect of eight nutritional treatments and residual values were used in the association analysis with the SNP markers. A total of 11 696 genotypes of 237 steers were determined using a panel of 58 tag-SNP in the GHR, IGF1, IGFBP6, PMCH, SOCS2, STAT6, SCD1, SCD5, SREBP1, SCAP, INSIG1, INSIG2, MBTPS1, MBTPS2 and SRPR genes. A total of 11 polymorphic SNP were significantly asso-ciated with traits of interest: GHR_ rs41639262 on EGSu and MARBL; IGF1_ rs136251088 on PCC, PCE and PISTOLA; PMCH_ rs135033882 on OMEGA36; SOCS2_ ss252841026 on Terneza2d; STAT6_ rs109171041 on Terneza2d; STAT6_ rs110097583 on Terneza2d; INSIG1_ rs109314460 on Terneza21d; INSIG1_ ss252452220 on OMEGA36; SCD5_ ss252452202 on PUFA and Terneza2d; SCD5_ rs43687655 on EGSu and OMEGA36; SRPR_ rs42178091 on GRASAINTR, SFA, MUFA, PCC, PCE and PISTOLA. Additional studies could validate the marker-trait association effects that would make it possible to use these genetic markers to improve carcass and meat quality of animals under different feeding regimes.