| Myogenesis of skeletal muscle is a cascade of development.Myostatin(MSTN)and myogenic regulatory factors(MRFs)both play an important role in muscle development.MSTN is a negative regulator of skeletal muscle growth and Myf5 and MyoG from the MRFs family are involved in the proliferation and differentiation of myoblasts,respectively.Studying the expression patterns of MSTN,Myf5 and MyoG genes is helpful to understand the regulatory mechanism of muscle growth and development in domestic pigeons.In this research,we constructed a tissue expression profile of the pigeon MSTN gene in eight tissues and spatio-temporal expression profiles of the MSTN,Myf5 and MyoG gene in the pectoral muscle using qRT-PCR method.The pectoralis muscle fiber traits during pigeon post hatching stages at 1 d,7 d,14 d,21 d and 28 d were analyzed through the paraffin sections.Then the correlations between the muscle fiber diameter,cross-sectional area,density and the expression of MSTN in the pectoral muscle were analyzed.Results showed that MSTN mRNA was mainly expressed in breast muscle,heart,spleen and kidney and almost unexpressed in the liver and lungs.Moreover,the MSTN mRNA expression level in breast muscle was significantly higher than that in other tissues(P<0.05),and showed an interesting trend that it decreased in the first week and then increased with age.Meanwhile,decrease of myostatin transcripts was accompanied by the down-regulation of Myf5 and the up-regulation of MyoG during the first week post hatching.In addition,the paraffin sections analysis results revealed that the diameter and cross-sectional area of pectoralis muscle fiber significantly increased with age(P<0.05),and a significant positive correlation was shown between the MSTN gene expression level and muscle fiber diameter(P<0.05).The improvements in muscle growth rate and meat quality are the major breeding aims in pigeon industry.Liver and muscle are recognized as important sites for fatty acid metabolism,understanding the role of specific transcripts in the breast muscle and liver might lead to the elucidation of interrelated biological processes.In this study,RNA-Sequencing(RNA-Seq)was applied to compare the transcriptomes of breast muscle and liver tissues among pigeons at 5 developmental periods(0,1,2,3,4 weeks post-hatching)to identify candidate genes related to muscle growth and lipid metabolism.There were 3,142 differentially expressed genes(DEGs)identified in the breast muscle libraries.A total of 1,323 DEGs were acquired from the liver libraries.By GO annotation and KEGG pathway enrichment analysis,a set of significantly enriched pathways were identified for the DEGs,which are potentially involved in GO terms such as ATP metabolic process,cell cycle process,mitochondrial inner membrane,microtubule binding,hydrogen ion transmembrane transporter activity,ATP binding and KEGG pathways such as oxidative phosphorylation,citrate cycle,glycolysis/gluconeogenesis,biosynthesis of amino acids,insulin signaling pathway,ECM-receptor interaction,cell cycle,fatty acid degradation,p53 signaling pathway and biosynthesis of unsaturated fatty acids.Some candidate genes related to muscle growth and lipid metabolism of pigeons,such as ATP5B,PPP1R3B,ACOX3,were provided.qRT-PCR was used to analyze the expression of 16 genes from 8 comparison groups(2 genes per group)for data validation.It was found that the qPCR result was consistent with the gene expression pattern obtained by RNA-sequencing,indicating that the sequencing data was reliable.The results of this study are helpful to further understand the growth and development of muscle fiberst and the role of MSTN,Myf5 and MyoG gene in the post hatching muscle fiber development in pigeon.At the same time,the transcriptome sequencing results could contribute to future investigations of muscle growth and lipid metabolism mechanism and establish molecular approaches to improve muscle growth rate and meat quality in domestic pigeon breeding. |
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