The phylogeny analysis of MyoG gene in different pig breeds

Positive selection signatures in Anqing six-end-white pig population based on reduced-representation genome sequencing data

Anqing six-end-white (AQ) pig performs well on resistance to coarse fodder and disease, reproduction and meat quality, offering high potential for exploitation. Environmental conditions and strict selections from local farmers have cultivated the AQ pig to be an outstanding and unique local pig breed. Thus we aim to detect genetic positive selection signatures within the AQ pig population to explore underlying genetic mechanisms. A relative extended haplotype homozygosity (REHH) test was performed in the population of 79 AQ pigs to seek evidence demonstrating that selective actions have left an imprint on the whole genome. In total, 430 500 REHH tests were performed on 53 067 core regions with average REHH tests of 8.11, average lengths of 11.50 kb and an overall length of 610.38 Mb which accounted for 26.94% of the whole genome. Finally, a total of 1819 core haplotypes (P < 0.01) and 586 candidate genes were obtained. These genes were mainly related to meat quality (MYOG, SNX19), resistance to disease (CRISPLD2, CD14) and reproduction traits (ERBB2, NRP2). A panel of genes within the 30 top significant REHH tests was mainly categorized to traits of meat quality and disease resistance. Among 13 KEGG pathways, MAPK, GnRH and Oxytocin signaling pathways, associated with the biological processes of crucial economic traits, were noteworthy. The excellent characteristics of the AQ pig benefited from the combination of natural and human factors. We provide a sketch map that shows the distribution of selection footprints on the whole genome of AQ pig and found potential genes for future studies.

MyoD and Myf6 gene expression patterns in skeletal muscle during embryonic and posthatch development in the domestic duck (Anas platyrhynchos domestica)

The MyoD and Myf6 genes, which are muscle regulatory factors (MRFs), play major roles in muscle growth and development and initiate muscle fibre formation via the regulation of muscle-specific gene translation. Therefore, MyoD and Myf6 are potential candidate genes for meat production traits in animals and poultry. The objective of this study was to evaluate MyoD and Myf6 gene expression patterns in the skeletal muscle during early developmental stage of ducks. Gene expression levels were detected using the quantitative RT-PCR method in the breast muscle (BM) and leg muscle (LM) at embryonic days 13, 17, 21, 25, 27, as well as at 1 week posthatching in Gaoyou and Jinding ducks (Anas platyrhynchos domestica). The MyoD and Myf6 gene profiles in the two duck breeds were consistent during early development, and MyoD gene expression showed a 'wave' trend in BM and an approximate 'anti-√' trend in LM. Myf6 gene expression in BM showed the highest level at embryonic day 21, which subsequently decreased, although remained relatively high, while levels at embryonic days 13, 17 and 21 were higher in LM. The results of correlation analysis showed that MyoD and Myf6 gene expression levels were more strongly correlated in LM than in BM in both duck breeds. These results indicated that different expression patterns of the MyoD and Myf6 genes in BM and LM may be related to muscle development and differentiation, suggesting that MyoD and Myf6 are integral to skeletal muscle development.

The expression pattern of myogenic regulatory factors MyoD, Myf6 and Pax7 in postnatal porcine skeletal muscles

The MyoD, Myf6 genes, which belong to the family of muscle regulatory factors (MRFs) play a major role in muscle growth and development. Therefore, they are considered as candidate genes for meat production traits in pigs. These basic helix-loop-helix (bHLH) transcription factors regulate myogenesis: they initiate the formation of muscle fibres and regulate the transcription of muscle specific genes. The paired-box transcription factor Pax7 plays critical roles during fetal development and this protein is essential for renewal and maintenance of muscle stem cells. In particular, expression of Pax7 and MyoD is correlated with presence of active satellite cells, important in hyperplastic and hypertrophic growth in skeletal muscle. The objective of the study was to investigate the level of expression of MyoD, Myf6 and Pax7 genes in porcine skeletal muscles (m. semimembranosus, m. biceps femoris, m. gracilis) in breeds differing in muscularity. Moreover, we investigated expression profile of these genes during ontogenesis in Polish Large White (PLW) and Pietrain pigs in the largest ham muscle (m.semimembranosus). Analysis of several ham muscles showed higher expression of MyoD in the Polish Landrace (PL) breed than in Pietrain and PLW pigs (m. semimembranosus P<0.001; m. biceps femoris P<0.05 and P<0.01, respectively; m. gracilisP<0.01). The level of Pax7 transcript depended on type of muscle and breed. The highest expression was in m. gracilis in Pietrain and the lowest in Polish Landrace. Our results indicate that MyoD and Pax7 genes had higher expression levels in the early stages of development in both investigated breeds. The total expression profile of MyoD and Pax7 genes suggests that higher muscularity in Pietrain pigs is associated with the presence of a greater number of active satellite stem cells compared to other breeds. The expression level of Myf6 gene does not indicate significant differences between muscles, ages and breeds.