Transcriptome Analysis Identifies Potential Molecular Mechanisms for Fast Muscle Growth in Chinese Perch Juvenile

Chinese perch (Siniperca chuatsi) is one of the commercially important fish species. Understanding the molecular mechanisms of skeletal muscle growth and development is helpful for selection breeding and improving the growth rate of Chinese perch. In this study, the histological and transcriptome differences in fast muscle of Chinese perch between 30 days post hatching (dph) and 60 dph were analyzed using histological section and high-throughput RNA-Seq. The results showed that the diameter of muscle fibers was primarily distributed in the range of 30-40 μm at 30 dph Chinese perch, whereas the diameter of muscle fibers was primarily distributed in the range of 40-50 μm at 60 dph, indicating that the diameter of muscle fibers was increased at 60 dph. A total of 465 differentially expressed genes (DEGs) were identified, including 136 up-regulated and 329 down-regulated genes. The down-regulated genes including Myh4, Eno3, Fos and Igfn1 are associated with muscle cell differentiation and fusion in Chinese perch. The up-regulated gene Tnni2 is closely related to fast muscle growth and development, and may be an important gene in regulating fast muscle growth of Chinese perch during 30 dph to 60 dph. The analysis of the protein-protein interaction network of DEGs also revealed that Fos, Junb and Egr1 may involve in the development of fast muscle in Chinese perch. The KEGG enrichment results showed that the significantly up-regulated genes in the 60 dph group were involved in several pathways related to fast muscle metabolism and protein synthesis, such as glycosphingolipid biosynthesis-globo and isoglobo series, glycosphingolipid biosynthesis-ganglio series and aminoacyl-tRNA biosynthesis. The transcriptome analysis suggests that the accumulation of proteins in the cytoplasm may be the main reason for the increase in fast muscle diameter in Chinese perch from 30 dph to 60 dph.