Analysis Of Digital Gene Expression Profiles And Identification Of Some Differentially Expressed Genes In The Skeletal Muscle Of Pigs

With the improvement of people’s living standards, the percentage of high lean meat and the high growth rate can not meet the requirements of the people on pork quality, so improving meat and regulating the development of the pig breeding from the molecular level has becoming a new direction. Research has shown that the histological features of muscle fibers are closely related to meat tenderness, flavor and juicy traits. The Northeast Min pig (NM) and Changbaishan wild boar(CW)are the characteristics of pigs in the Northeast, meat quality of the two pigs are different, and the two breeds also different in skeletal muscle growth and development characteristics.While rare the reports on early development of the histological features of skeletal muscle growth about NM and CW. In this study, the technology of paraffin section and the digital imaging optical microscopy was conducted to observe and analyse the morphological characteristics of skeletal muscle fibers, conducting a preliminary analysis of digital gene expression profiles of the longissimus of the two pigs by bioinformatics methods,then the expressed differentlial genes were selected.In this study, the muscle fiber diameters and densities of the longissimus dorsi, the biceps femoris, the quadriceps and deltoid from two breeds of30tested pigs at40-day-age were determined and analyzed respectively. This result reveals that in the four kind of skeletal muscle tissues, the diameters of muscle fibers in NM were significantly larger than those of CW breed (P<0.05), the fiber densities of NM were significantly thinner than those of CW (P<0.05); For the same breed, the diameter difference and density differences between different gender individuals were not significant (P>0.05) in the same kind of skeletal tissues, respectively. For the same kind of skeletal tissues from the same gender, both the muscle fiber diameter difference and density differences between different porcine breeds were significantly different (P <0.05), respectively. The muscle fiber diameters and densities of both CW and NM were significantly negatively correlated. Above all, the postnatal growth and development of the diameters and densities of the pigs’skeletal muscle fiber were considerably affected by breed effects, but the gender effect was not significant.Muscle fiber diameter and density of CW and NM were significantly negatively correlated. The longissimus dorsi muscle cDNA library of the two breeds of pigs were respectively constructed by using the technology of high-throughput Solexa/Illumina, and then the experiment used application of digital gene expression profiling (DGE) analysis and differential expression of genetic testing to selecte the4522differentially expressed gene,4176up-regulated genes and346down-regulated genes.To further verify the function of these genes, we analysis Gene Ontology (GO) and Pathway. The results showed that the differentially expressed genes were involved in198pathways, enrichment of cellular location and molecular function and biological processes involved are:membrance-bounded organelle, cytoplasm, endoplasmic reticulum, nucleus, intracellular organelle lumen; protein binding, coenzyme binding, catalytic activity, nucleic acid binding, purine ribonucleotide binding, transferase activity; RNA splicing, protein transport, metabolic processes, immune response, macromolecule catabolic process, RNA metabolic process and cellulr metabolic process.In order to verify the reliability of the differentially expressed genes were selected by DGE, the functional genes of STXBP2, RASp21, FBXO32, TBX15, LAG-3, CLN3, PPP3CA, PPP3R1were randomly selected from the differentially expressed genes for q-PCR confirmation.The results show that8genes expression in longissimus dorsi of the two breeds of pigs were significant(P<0.05).And these genes were widely expressed in skeletal muscle and visceral tissues of the two breeds of pigs, in addition to the expression of TBX15gene in liver tissue, the expression of PPP3R1in biceps femoris and quadriceps tissue, the expression of STXBP2and RASA4in trapezius of the two breeds of pigs were not significant(P>0.05), the rest were significantly different(P<0.05), this results can prove the digital gene expression profiles is a reliable means of differentially expressed genes in a specific organization.