Transcriptome analysis identifies potential molecular mechanisms for growth of fast muscle in Chinese perch juvenile

Chinese perch (Siniperca chuatsi) is an important commercial fish species in China. Understanding the molecular mechanisms of growth and development of skeletal muscle is helpful for selection breeding and improving the growth rate of Chinese perch. We analyzed histological and transcriptomic differences in fast muscle of Chinese perch between 30 days post hatching (dph) and 60 dph using histological sections and high-throughput RNA-Seq. The results showed that the diameter of muscle fibers in 30 dph Chinese perch was mainly distributed in range of 30 - 40 μm, and that of 60 dph was primarily in the range of 40 - 50 μm. 34 differentially expressed genes (DEGs) were identified in the fast muscle of Chinese perch between 30 and 60 dph, of which 9 were up-regulated and 25 were down-regulated (60 dph vs 30 dph). The DEGs, including MYH4, ENO3, Bag3, krt13 and krt18, are associated with muscle cell differentiation and fusion in Chinese perch. The analysis of the protein-protein interaction network of DEGs revealed that FOS, junb and EGR1 may involve in the development of fast muscle. KEGG enrichment results showed that the up-regulated genes in the 60 dph were associated with several pathways related to metabolism and protein synthesis, such as glycosphingolipid biosynthesis and aminoacyl-tRNA biosynthesis. The results suggest that the development of fast muscle in Chinese perch from 30 to 60 dph is accompanied by an increase in muscle fiber diameter and changes in gene expression related to muscle cell differentiation and protein synthesis. Abbreviations: DEGs, differentially expressed genes; dph, days post hatching; FC, fold change; FDR, False Discovery Rate; GO, Gene Ontology; KEGG, Kyoto Encyclopedia of Genes and Genomes; MyHCs, Myosin heavy chains; qRT-PCR, quantitative real-time PCR.