Identificated Candidate Genes Related To Muscle Development In Hanper Sheep Based On RNA Sequencing Technology

As one of the most important meat producing animals in the world,sheep plays an important role in animal husbandry.At present,there is a lack of specialized breeds of mutton sheep in China,and the production of mutton sheep is mainly in the form of crossbreeding,which limits the production efficiency and unit yielded level to mutton sheep.Hanper sheep is Dorper×Small Tailed Han crossbred sheep,which is bred almost ten years using molecular marker-assisted selection and formed a new flock.Hanper sheep has high carcass weight,net meat weight and slaughter rate.At present,there are few reports about the molecular mechanism of meat quality and meat yield in different growth stages about Hanper sheep.Therefore,the preset study carried out the following work:Through the comparative analysis of the meat quality of 1-month（M1）,7-month（M7）and 13-month（M13）Hanper sheep,it was found that the pH₂₄ of M13 was significantly higher than that of M1 and M7（P<0.01）,but there was no significant difference in the rate of cooked meat among different months（P>0.05）.About the rate of water loss,there was no significant difference between M7 and M13（P>0.05）,but both of them were significantly higher than M1（P<0.01）.Shear to force increased from the age growth,the index of meat color between different months showed that the diverse in L（brightness）was significantly difference（P<0.01）,but a（redness）,b（yellowness）,c（chroma）were not（P>0.05）.With the increase in the age,the muscle fiber area increased significantly（P<0.01）.RNA-seq was used to sequence and analyze the transcriptome of the longissimus dorsi muscle of 1-month（M1）,7-month（M7）and 13-month（M13）Hanper sheeps.A total of 143GB data were obtained,and the average GC content was 54.65%.We then determined differentially expressed mRNAs among the three different stages.963differentially expressed genes were identified by comparative analysis of the three stages（FDR<0.05）.In a comparison of M1 and M7 muscle libraries,357 mRNAs were significantly differentially expressed,while 446 mRNAs were significantly differentially expressed between the M1 and M13 muscle libraries.A total of 160mRNAs in M7 were significantly differentially expressed compared to M13.RT-qPCR was used to verify the results of RNA-seq.The trend of gene expression was consistent,indicating that the results of RNA-seq were accurate and reliable.Enrichment analysis of GO and KEGG pathway functions was conducted.Compared with M7,the significantly up-regulated genes in M1 were mainly enriched in amino acid synthesis and metabolism related signaling pathways,and the up-regulated genes in M7 were mainly enriched in AMPK signaling pathway and cGMP-PKG signaling pathway,which were related to muscle growth and development.Compared with M13,the up-regulated genes in M1 were mainly enriched in glycine,serine and threonine metabolic pathways,while the up-regulated genes in M13 were mainly enriched in hormone metabolism and immune related pathways.According to transcriptomic sequencing screening results and literature review,we verified that TMOD4,FHL3 and MYBPC1 were important candidate genes through physicochemical properties analysis,RT-QPCR and Western Blot,but their specific regulatory mechanisms need further study.