Variantes da região cromossômica do gene da miostatina e suas relações com linhagens, desempenho e medidas corporais na raça Quarto de Milha
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2017-10-11
Autores
Matteis, Rafael de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Ao longo de várias décadas a raça Quarto de Milha foi selecionada para diferentes objetivos, formando grupos com aptidões ou habilidades distintas, como a linhagem de corrida, que apresenta melhor desempenho que qualquer outra linhagem ou raça em corridas de curta distância e a linhagem de trabalho, utilizada no manejo de bovinos a campo e em provas de caráter funcional. Considerando as diferenças nas medidas corporais e na musculatura que ocorrem entre as linhagens de corrida e de trabalho da raça Quarto de Milha, o objetivo deste trabalho foi analisar a ocorrência de relações entre alelos de polimorfismos da região cromossômica do gene da miostatina MSTN (ECA18), um regulador negativo do desenvolvimento muscular, e as duas linhagens da raça. Outro objetivo foi realizar análises de associação de polimorfismos dessa região cromossômica com valor genético estimado (EBV) do desempenho em corridas, dado pelo índice de velocidade máximo (IV max), e EBVs da altura à cernelha (AC), perímetro torácico (PT) e comprimento corporal (CC) na linhagem de corrida, e com EBVs da AC, PT e CC na linhagem de trabalho. Foram utilizadas informações genômicas, fenotípicas e de pedigree de 420 equinos, de ambos os sexos, registrados na associação Brasileira de criadores (ABQM), sendo 352 da linhagem de corrida e 68 da de trabalho. Na região genômica estudada (gene MSTN ± 2Mb), foram identificados 46 SNPs e 1 SINE – ERE1 comuns às linhagens de trabalho e de corrida, dos quais 32 SNPs e 1 SINE apresentaram alelos com frequências significativamente diferentes entre às mesmas. Também foi constatado que a porção dessa região mais próxima ao gene MSTN (± 1Mb) é menos polimórfica na linhagem de corrida em relação à de trabalho, o que pode ser consequência de maior pressão de seleção sobre essa região na linhagem de corrida e/ou em função do uso de animais da raça Puro Sangue Inglês na mesma. Em relação aos polimorfismos associados à fenótipos (p não ajustado < 0,05), destacaram-se os relacionados à altura de cernelha na linhagem de corrida devido ao seu grande número (p não ajustado < 0,05) e alto desequilíbrio de ligação. Ademais estes marcadores apresentaram frequências do alelo favorável significativamente maiores em relação à linhagem de trabalho. Tendo se em vista a possibilidade de associação genética entre características morfológicas e desempenho em equinos, esse resultado é de grande importância, fornecendo informações para futuros estudos de melhoramento genético animal.
For several decades the Quarter Horse breed was selected for different purposes, forming groups with different abilities, such as the racing line, which performs better than any other lineage or breed in short distance races and the lineage of work, used in the management of field cattle and in functional tests. Considering the differences in body measurements and musculature that occur between racing and working strains of the Quarter-Mile breed, the objective of this study was to analyse the occurrence of relations between polymorphic alleles of the chromosomal region of the myostatin (MSTN) gene (ECA18), a negative regulator of muscle development, and the two lineages of the breed. Other objective was to perform association analyses of these polymorphisms with estimated genetic value (EBV) of the performance in lineages, given by the maximum velocity index (IV max), and EBVs of height at withers (HW), heart girth (HG) and body length (BL) in the racing line, and with EBVs of AC, PT and CC in the working line. We used genomic, phenotypic and pedigree information from 420 horses of both sexes, recorded in the Brazilian breeders' association (ABQM), 352 and 68 of the racing and working line, respectively. In the studied genomic region (MSTN gene ± 2Mb), 46 SNPs and 1 SINE - ERE1 were identified, common to the working and running strains, of which 32 SNPs and one SINE presented alleles with significantly different frequencies between them. It has also been found that the portion of this region closest to the MSTN gene (± 1Mb) is less polymorphic in the racing versus the working strain, which may be a consequence of higher selection pressure on that region in the racing line and / or due to the use of purebred English animals in it. In relation to the polymorphisms associated with the phenotypes (p not adjusted <0.05), those related to the height of the withers in the race line due to their large number (p not adjusted <0.05) and high linkage disequilibrium were the most prominent. In addition, these markers presented frequencies of the favorable allele significantly higher in relation to the working lineage. Considering the possibility of genetic association between morphological characteristics and performance in equines, this is a result of great importance, providing information for future animal breeding studies.
For several decades the Quarter Horse breed was selected for different purposes, forming groups with different abilities, such as the racing line, which performs better than any other lineage or breed in short distance races and the lineage of work, used in the management of field cattle and in functional tests. Considering the differences in body measurements and musculature that occur between racing and working strains of the Quarter-Mile breed, the objective of this study was to analyse the occurrence of relations between polymorphic alleles of the chromosomal region of the myostatin (MSTN) gene (ECA18), a negative regulator of muscle development, and the two lineages of the breed. Other objective was to perform association analyses of these polymorphisms with estimated genetic value (EBV) of the performance in lineages, given by the maximum velocity index (IV max), and EBVs of height at withers (HW), heart girth (HG) and body length (BL) in the racing line, and with EBVs of AC, PT and CC in the working line. We used genomic, phenotypic and pedigree information from 420 horses of both sexes, recorded in the Brazilian breeders' association (ABQM), 352 and 68 of the racing and working line, respectively. In the studied genomic region (MSTN gene ± 2Mb), 46 SNPs and 1 SINE - ERE1 were identified, common to the working and running strains, of which 32 SNPs and one SINE presented alleles with significantly different frequencies between them. It has also been found that the portion of this region closest to the MSTN gene (± 1Mb) is less polymorphic in the racing versus the working strain, which may be a consequence of higher selection pressure on that region in the racing line and / or due to the use of purebred English animals in it. In relation to the polymorphisms associated with the phenotypes (p not adjusted <0.05), those related to the height of the withers in the race line due to their large number (p not adjusted <0.05) and high linkage disequilibrium were the most prominent. In addition, these markers presented frequencies of the favorable allele significantly higher in relation to the working lineage. Considering the possibility of genetic association between morphological characteristics and performance in equines, this is a result of great importance, providing information for future animal breeding studies.
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Palavras-chave
equino, ERE1, marcadores moleculares, QTL, SNP, velocidade, equine, molecular markers, speed