ABSTRACT
Some horse breeds are highly selected for athletic activities. The athletic potential of each animal can be measured by its performance in sports. High athletic performance depends on the animal capacity to produce energy through aerobic and anaerobic metabolic pathways, among other factors. Transmembrane proteins called monocarboxylate transporters, mainly the isoform 1 (MCT1) and its ancillary protein CD147, can help the organism to adapt to physiological stress caused by physical exercise, transporting lactate and H+ ions. Horse breeds are selected for different purposes so we might expect differences in the amount of those proteins and in the genotypic frequencies for genes that play a significant role in the performance of the animals. The study of MCT1 and CD147 gene polymorphisms, which can affect the formation of the proteins and transport of lactate and H+, can provide enough information to be used for selection of athletic horses increasingly resistant to intense exercise. Two other candidate genes, the PDK4 and DMRT3, have been associated with athletic potential and indicated as possible markers for performance in horses. The oxidation of fatty acids is highly effective in generating ATP and is controlled by the expression of PDK4 (pyruvate dehydrogenase kinase, isozyme 4) in skeletal muscle during and after exercise. The doublesex and mab-3 related transcription factor 3 (DMRT3) gene encodes an important transcription factor in the setting of spinal cord circuits controlling movement in vertebrates and may be associated with gait performance in horses. This review describes how the monocarboxylate transporters work during physical exercise in athletic horses and the influence of polymorphisms in candidate genes for athletic performance in horses.(AU)
Algumas raças de equinos são altamente selecionadas para atividades desportivas. O potencial atlético de cada animal pode ser medido pelo seu desempenho nas competições equestres. Um alto potencial atlético depende, entre outros fatores, da capacidade do animal de produzir energia através dos metabolismos aeróbio e anaeróbio. As proteínas transmembrana chamadas transportadores de monoxarboxilato, principalmente a isoforma 1 (MCT1) e sua proteína auxiliar CD147, podem ajudam o organismo a se adaptar ao estresse fisiológico causado pelo exercício físico, transportando íons lactato e H+. Algumas raças de equinos são selecionadas para diferentes objetivos, portanto é provável que existam diferenças nas quantidades de transportadores monocarboxilatos e na frequência genotípica dos seus respectivos genes. O estudo de polimorfismos nos genes das proteínas MCT1 e CD147, afetando a sua formação e o transporte dos íons lactato e H+, podem fornecer informações suficientes para a seleção de equinos com capacidade de serem altamente treinados e resistentes a intensos exercícios. Dois outros genes candidatos que têm sido relacionados com potencial atlético e utilizados como possíveis marcadores para desempenho em equinos são o PDK4 e o DMRT3. A oxidação de ácidos graxos é altamente efetiva para produção de ATP e é controlada pela expressão do gene PDK4 (pyruvate dehydrogenase kinase, isozyme 4) no musculo esquelético durante e após do exercício físico. O gene DMRT3 (doublesex and mab-3 related transcription factor 3) codifica um importante fator de transcrição no controle dos movimentos em vertebrados e pode ser associado com a marcha em algumas raças de equinos. Esta revisão descreve como agem os transportadores de monocarboxilatos durante o exercício físico em equinos atletas e qual a influência de alguns polimorfismos em genes candidatos para o desempenho atlético em equinos.(AU)
Subject(s)
Animals , Genetic Association Studies , Horses/genetics , Horses/physiology , Lactates/analysis , Muscle Fatigue , Polymorphism, Genetic , Stress, PhysiologicalABSTRACT
The aim of this study was to determine the extent (r2) of linkage disequilibrium (LD) in the genome of Nellore cattle, and to examine associations between single nucleotide polymorphisms (SNP) and age at first calving (AFC) and early pregnancy (EP) using a panel of high-density SNPs and data from 1182 Nellore females. A total of 13 contemporary groups (CG) were used consisting of farm, season, and year of birth. For genome-wide association analysis, SNPs with a minor allele frequency (MAF)<0.05 and animals with a call rate<0.90 were excluded, totaling 431,885 SNPs. For statistical analysis, a linear model was used for AFC and a threshold model for EP. To estimate the significance of the associations for the two traits, the model included the categorical fixed effects of CG, SNPs, and sire. In addition, the polygenic effect was included in the analysis. The additive effects and dominance deviations of Bonferroni-adjusted significant SNPs for AFC and EP were estimated using orthogonal contrasts. The average estimate of r2 for all autosomes was 0.18 at a distance of 4.8kb and the mean MAF was 0.25±0.13. The LD decreased as the distance between markers increased: 0.35 (1kb) to 0.12 (100kb). Eleven significant associations were detected in seven different chromosomes. Seven SNPs were associated with AFC and four were associated with EP. Three SNPs were significant for both traits. The identification of SNPs associated with AFC and EP may contribute for selecting sexually precocious animals.
