Analysis of horse myostatin gene and identification of single nucleotide polymorphisms in breeds of different morphological types

Abstract

Myostatin (MSTN) is a negative modulator of muscle mass. We characterized the horse (Equus caballus) MSTN gene and identified and analysed single nucleotide polymorphisms (SNPs) in breeds of different morphological types. Sequencing of coding, untranslated, intronic, and regulatory regions of MSTN gene in 12 horses from 10 breeds revealed seven SNPs: two in the promoter, four in intron 1, and one in intron 2. The SNPs of the promoter (GQ183900:g.26T>C and GQ183900:g.156T>C, the latter located within a conserved TATA-box like motif) were screened in 396 horses from 16 breeds. The g.26C and the g.156C alleles presented higher frequency in heavy (brachymorphic type) than in light breeds (dolichomorphic type such as Italian Trotter breed). The significant difference of allele frequencies for the SNPs at the promoter and analysis of molecular variance (AMOVA) on haplotypes indicates that these polymorphisms could be associated with variability of morphology traits in horse breeds.

Figure 1

Horses of extreme and opposite morphological types:(a) Rapid Heavy Draft (brachymorphic type or heavy) and (b) Italian Trotter (dolichomorphic type or light).

Figure 2

Genomic organization of the horse MSTN gene. Exons are shown as boxes. Solid boxes indicate protein coding regions. Untranslated regions are shown as striped boxes. Size of the sequenced regions of the promoter, exons, and introns is reported. Polymorphisms, indicated according to GenBank accession number GQ183900, are reported on the genomic organization of the gene.

Figure 3

Sequence analysis of the proximal promoter region and 5′-UTR of MSTN gene. Approximately 670 bp of the MSTN 5′-flanking region and 5′-UTR from horse, cattle, goat, human, mouse, pig, and sheep is shown. The consensus for transcription factor binding motives is shown in bold text and underlined. Numbering of the horse sequence is relative to the ATG start codon. Numbering of E-boxes is relative to the horse sequence. The two identified SNPs of horse MSTN gene are indicated with Y (T or C according to the IUPAC nomenclature) and in red.

Figure 3

Sequence analysis of the proximal promoter region and 5′-UTR of MSTN gene. Approximately 670 bp of the MSTN 5′-flanking region and 5′-UTR from horse, cattle, goat, human, mouse, pig, and sheep is shown. The consensus for transcription factor binding motives is shown in bold text and underlined. Numbering of the horse sequence is relative to the ATG start codon. Numbering of E-boxes is relative to the horse sequence. The two identified SNPs of horse MSTN gene are indicated with Y (T or C according to the IUPAC nomenclature) and in red.