Transcriptome Sequencing And Characterization Analysis Of MiRNA And MRNA In Longissimus Dorsi Muscle Between Luchuan And Landrace Pigs

As a local excellent breed of pigs in Guangxi,Luchuan pig has the advantages of strong fecundity,stable heredity,high intramuscular fat content,fresh and tender meat,but it has a long feeding cycle and low lean ratio.Landrace pig have the characteristics of fast growth and high lean ratio,but their meat quality and flavor are not good enough.Therefore,it is of great significance for meat quality improvement to investigate the present potential action mechanisms of mi RNAs and m RNAs that affect meat quality and muscle development in Luchuan and Landrace pigs.In this study,selected the longissimus dorsi muscle tissues of 8-month-old Luchuan and Landrace pigs as the research material,routine paraffin section and HE staining were performed,and used high-throughput sequencing technology to sequence analysis mi RNA and m RNA in longissimus dorsi muscle of Luchuan and Landrace pigs,screen differentially expressed mi RNA and m RNA,and the differentially expressed mi RNA target genes and m RNA were analysed by GO and KEGG,q RT-PCR was used to verify the reliability of the sequencing results.The results of study are as follows:1.Histological characteristics of longissimus dorsi muscle in Luchuan and Landrace pigsBy paraffin section compared the morphological difference of muscle fibers between Luchuan and Landrace pigs,the results showed that the average muscle fiber diameter of Luchuan pig was 36.30 μm,and the average muscle fiber diameter of Landrace pig was 47.77 μm,the muscle fiber diameter of Luchuan pig was significantly lower than that Landrace pig(P<0.05);The average muscle fiber density of Luchuan pig was 321.76per/mm~2,and the average density of muscle fibers in Landrace pig was 217.66per/mm~2,the muscle fiber density of Luchuan pig was significantly higher than that Landrace pig(P<0.05).2.Sequencing and characterization of mi RNA in longissimus dorsi muscle between Luchuan and Landrace pigsBy high throughput sequencing analysis,a total of 311 known mi RNAs were identified,and 383 novel mi RNAs were predicted.62 differentially expressed mi RNAs(P<0.05)were screened,compared with Landrace pig,26 mi RNAs were upregulated and 36 mi RNAs were downregulated in Luchuan pig.The mi RNA lengths of the two kinds of pigs,mainly cluster at 18-24 nt,and most cluster at 22 nt.Through GO and KEGG enrichment analysis of differentially expressed mi RNA target genes,it was found that the biological processes significantly involved were cell adhesion,positive regulation of transcription from RNA polymerase II promoter,and significantly enriched in PI3K-Akt,Rap1,calcium and other signaling pathways related to muscle growth and development.Five differentially expressed mi RNAs were randomly selected for q RT-PCR verification,and the results were basically consistent as the high-throughput sequencing.3.Sequencing and characterization of m RNA in longissimus dorsi muscle between Luchuan and Landrace pigsBy high throughput sequencing analysis,a total of 459 differentially expressed m RNA(P<0.05)were screened,compared with Landrace pig,270 m RNA were upregulated and 189 m RNA were downregulated in Luchuan pig.Through GO and KEGG enrichment analysis of differentially expressed m RNA,it was found that the biological processes significantly involved were multicellular organism development,anatomical structure development,developmental process,and significantly enriched in PI3K-Akt,c GMP-PKG,Insulin,Wnt and other signaling pathways related to muscle growth and development.Five differentially expressed m RNAs were randomly selected for q RT-PCR validation,and the results were basically consistent as the high-throughput sequencing.To summarize,the study obtained differentially expressed mi RNA and m RNA in longissimus dorsi muscle of two breeds of pigs,as well as some signaling pathways related to muscle development.These results suggest that the differentially expressed mi RNAs and m RNAs may be involved in the process of muscle growth and development,and provide a data reference for the improvement breeding of local breed pig.