Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, Shandong, China.
Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology, Qingdao, Shandong, China.
PeerJ. 2022 Mar 30;10:e12720. doi: 10.7717/peerj.12720. eCollection 2022.
Fast-twitch and slow-twitch muscles are the two principal skeletal muscle types in teleost with obvious differences in metabolic and contractile phenotypes. The molecular mechanisms that control and maintain the different muscle types remain unclear yet. is a highly mobile active pelagic fish with distinctly differentiated fast-twitch and slow-twitch muscles. Meanwhile, has become a potential target species for deep-sea aquaculture because of its considerable economic value. To elucidate the molecular characteristics in the two muscle types of , we generated 122 million and 130 million clean reads from fast-twitch and slow-witch muscles using RNA-Seq, respectively. Comparative transcriptome analysis revealed that 2,862 genes were differentially expressed. According to GO and KEGG analysis, the differentially expressed genes (DEGs) were mainly enriched in energy metabolism and skeletal muscle structure related pathways. Difference in the expression levels of specific genes for glycolytic and lipolysis provided molecular evidence for the differences in energy metabolic pathway between fast-twitch and slow-twitch muscles of . Numerous genes encoding key enzymes of mitochondrial oxidative phosphorylation pathway were significantly upregulated at the mRNA expression level suggested slow-twitch muscle had a higher oxidative phosphorylation to ensure more energy supply. Meanwhile, expression patterns of the main skeletal muscle developmental genes were characterized, and the expression signatures of , , , , and five insulin-like growth factors indicated that more myogenic cells of fast-twitch muscle in the differentiating state. The analysis of important skeletal muscle structural genes showed that muscle type-specific expression of , and may lead to the phenotypic structure differentiation. RT-qPCR analysis of twelve DEGs showed a good correlation with the transcriptome data and confirmed the reliability of the results presented in the study. The large-scale transcriptomic data generated in this study provided an overall insight into the thorough gene expression profiles of skeletal muscle in a highly mobile active pelagic fish, which could be valuable for further studies on molecular mechanisms responsible for the diversity and function of skeletal muscle.
快肌和慢肌是硬骨鱼类的两种主要骨骼肌类型，它们在代谢和收缩表型上有明显的差异。然而，控制和维持不同肌肉类型的分子机制尚不清楚。 是一种高度洄游的主动洄游鱼类，具有明显分化的快肌和慢肌。同时， 由于其巨大的经济价值，已成为深海养殖的潜在目标物种。为了阐明 的两种肌肉类型的分子特征，我们分别使用 RNA-Seq 从快肌和慢肌中生成了 1.22 亿和 1.30 亿个清洁读数。比较转录组分析显示，有 2862 个基因差异表达。根据 GO 和 KEGG 分析，差异表达基因（DEGs）主要富集在能量代谢和骨骼肌结构相关途径中。糖酵解和脂肪分解特定基因表达水平的差异为快肌和慢肌之间能量代谢途径的差异提供了分子证据。大量编码线粒体氧化磷酸化途径关键酶的基因在 mRNA 表达水平上显著上调，表明慢肌具有更高的氧化磷酸化作用，以确保更多的能量供应。同时，还对主要骨骼肌发育基因的表达模式进行了表征，并对 、 、 、 和五种胰岛素样生长因子的表达特征进行了分析，表明快肌中的更多肌原细胞处于分化状态。重要骨骼肌结构基因的分析表明， 、 和 的肌肉类型特异性表达可能导致表型结构的分化。十二种差异表达基因的 RT-qPCR 分析与转录组数据具有良好的相关性，证实了本研究结果的可靠性。本研究中产生的大规模转录组数据提供了对高度洄游主动洄游鱼类骨骼肌全面基因表达谱的深入了解，这对于进一步研究骨骼肌多样性和功能的分子机制可能具有重要价值。
