Effect of MYOG genotypes on growth rate and production traits in Hungarian large white pigs

Interaction of MyoD and MyoG with Myoz2 gene in bovine myoblast differentiation

This study aims to explore the functional role of Myoz2 in myoblast differentiation, and elucidate the potential factors interact with Myoz2 in promoter transcriptional regulation. The temporal-spatial expression results showed that the bovine Myoz2 gene was highest expressed in longissimus dorsi, and in individual growth stages and myoblast differentiation stages. Knockdown of Myoz2 inhibited the differentiation of myoblast, and negative effect of MyoD, MyoG, MyH and MEF2A expression on mRNA levels. Subsequently, the promoter region of bovine Myoz2 gene with 1.7 Kb sequence was extracted, and then it was set as eight series of deleted fragments, which were ligated into pGL3-basic to detect core promoter regions of Myoz2 gene in myoblasts and myotubes. Transcription factors MyoD and MyoG were identified as important cis-acting elements in the core promoter region (-159/+1). Also, it was highly conserved in different species based on dual-luciferase analysis and multiple sequence alignment analysis, respectively. Furthermore, a chromatin immunoprecipitation (ChIP) analysis combined with site-directed mutation and siRNA interference and overexpression confirmed that the combination of MyoD and MyoG occurred in region -159/+1, and played an important role in the regulation of bovine Myoz2 gene. These findings explored the regulatory network mechanism of Myoz2 gene during the development of bovine skeletal muscle.

Polymorphisms in coding and non-coding regions of rabbit (Oryctolagus cuniculus) myogenin (MyoG) gene

In animal breeding, selection based on growth is very often used, as this trait affects the profitability of animal production. Identification of  polymorphisms within the genes affecting the growth process seems to be very important. Therefore, we decided to analyse rabbit myogenin (<em>MyoG</em> gene) for potential polymorphic sites and their association with growth and carcass traits in Termond White (TER), Belgian Giant Grey (BGG) and crossbred New Zealand White×Belgian Giant Grey (NZW×BGG) rabbits. We found three single nucleotide polymorphisms (SNPs) – in 5’ upstream sequence g.68679476 C&gt;T, in exon 1 – silent mutation g.68680096 T&gt;C and g.68680097 G&gt;A resulting in change of GTG triplet (valine) into ATG triplet (methionine). Association analysis showed that GG genotype weaning weight was statistically higher compared to GA in TER population (<em>P</em>=0.005), and that the hind parts for GG genotypes were heavier compared to those of GA (<em>P</em>=0.024), but association analysis of dissectible parts showed this was caused by higher bone weight (<em>P</em>=0.015). For g.68679476 C&gt;T in NZW×BGG population, the CC genotypes for fore (678±35) and hind part (615±29) weights were heavier compared to CT (588±16 and 549±13, respectively); moreover, association analysis of dissectible parts showed that weight of dissectible meat in hind part. Unfortunately, we did not find similar associations for other analysed breeds. For g.68679476 C&gt;T in NZWxBGG musculus longissimus lumborum pH leg after 24 h chilling (pH24L) were statistically lower for CC genotypes compared to CT (<em>P</em>=0.027). For g.68680097 G&gt;A in Termond White population L* value on the hind leg after 24 h chilling (L*24H) was higher for GA genotypes compared to GG (<em>P</em>=0.03), while for g.68679476 C&gt;T for musculus longissimus lumborum L* value after 24 h (L*24L) CC genotypes had higher value compared to CT (<em>P</em>=0.016) in BGG population. Moreover, in BGG population CT genotypes had higher weaning weight compared to CC (<em>P</em>=0.018). Our results show that SNPs within the <em>MyoG </em>gene may influence growth traits in some rabbit breeds, but the evolutionary conserved sequence may not be favourable for changes within coding sequences. For a better understanding thereof, additional analysis is required.

The phylogeny analysis of MyoG gene in different pig breeds

Ten different pig breeds with different genetic origin (they are eight Chinese Domestic breeds, one recently Developed breed and one Introduced breed respectively) were utilized in this study to analyze the phylogeny of MyoG gene. 63 individuals were sequenced to get their complete nucleotide sequences of MyoG gene. Different methods and software were used and 6 phylogenetic trees were got based on the complete nucleotide sequence. To test the validation of these phylogenetic trees, the topologic structure differences between different trees were compared. The results indicate that the Neighbour Joining tree of the MyoG gene (Figure 2, NJ tree) has the best topological structure. In this NJ tree, 6 Chinese Domestic breeds cluster in one branch, Dahe and Wuzhishan pig constructed a new branch, Dahewu pig, Duroc and Standard MyoG gene sequence (Genbank accession number X89007) are clustered in one branch, the results are concord with the breeding history of these breeds and can reflect their true genetic background. Same topologic structure and parameters were found between different phylogenetic trees got by different methods. The same parameters of these trees confirmed the fact that the MyoG gene is very conservative and there are very few mutation sites between different breeds.

Characterization of microRNAs from sheep (Ovis aries) using computational and experimental analyses

Ovis aries is one of the most important agricultural livestock for meat production, and also is an ideal model organism for biological and comparative genomics studies. Many miRNAs have been reported for their important roles in developmental processes in various animals, but there is limited information about O. aries miRNAs. In this study, combining a computational method based on expressed sequence tag (EST) analysis with experimental identification based on small RNA cDNA library, we identified 31 miRNAs belong to 24 families in sheep, 2 of which were novel miRNAs which had never been previously identified in any species. Especially, we cloned 12 miRNAs from the sheep skeletal muscle, which were good candidate miRNAs to be studied about the miRNA-dependant regulated process of muscle development, and we identified four pairs of miRNA/miRNA and one pair of miRNA-3p/miRNA-5p from sheep EST sequences. Expression analysis indicated that some miRNAs were expressed in a specific tissue, and the pair of miRNA-3p/miRNA-5p and one pair of miRNA/miRNA had a similar relative expression pattern in some tissues, respectively. Further, we predicted 120 potential target genes of 31 oar-miRNAs on the 3'UTR of O. aries genes. Gene ontology analysis showed that most of these genes took part in the cellular process and metabolic process. Our results enriched the O. aries miRNA database and provided useful information for investigating biological functions of miRNAs and miRNA in sheep.