Desenvolvimento de teste de DNA para detecção da mutação Q204X no gene MSTN em bovinos da raça Bonsmara

Abstract

Double muscle syndrome (DM) is observed in different cattle breeds and is characterized by muscular hypertrophy, recognized by the increase in muscles, especially in the hindquarter region. DM manifests itself when mutations occur in the MSTN (Myostatin) gene, responsible for encoding the myostatin protein, a negative regulator of muscle development. Thus, the objective was to prospect for polymorphisms in the MSTN gene through sequencing, aiming to develop a DNA test that allows the early identification of Bonsmara animals that carry the mutated allele. For this, biological samples were collected from families in which the DM phenotype was segregating, based only on visual observations. For sequencing, eight pairs of primers were used and the electropherograms generated were edited and analyzed using the Unipro UGENE Software (version 49.1). The sequences obtained were aligned against the reference sequence of the bovine genome and the consensus sequences were compared to identify mutations. In exon 2, the Q204X mutation was found, a disruptive mutation caused by a transition from cytosine to thymine at nucleotide 610. To develop the DNA test, four pairs of specific primers were synthesized to detect this mutation. These primers were used to genotype 818 animals, using the ARMS-PCR (Amplification Refractory Mutation System-Polymerase Chain Reaction) technique. The results showed that in Bonsmara the presence of at least one Q204X mutated allele is associated with an increase in calf weight at birth, in muscularity and an increase in the harmony score, with harmony being the main phenotypic characteristic used by producers to select the animals.