We studied molecular effects (RNAseq and qPCR) of first feeding prey types (copepods or rotifers/Artemia) on skeletal muscle myogenesis and growth dynamics (proliferation, differentiation), metabolism (glycolysis, gluconeogenesis, oxidative phosphorylation), and antioxidant defense system (production/regulation of reactive oxygen species (ROS) in cod (Gadus morhua) larval skeletal muscle. Larval somatic growth rates were significantly higher in copepod fed larvae, although shifts in gene expressions related to muscle growth dynamics between hypertrophy and hyperplasia and generation and regulation of ROS mostly occurred around 5-, 10-, and 15-mm standard length (SL) for both groups. Gene expression for cell membrane proteins (such as nox1 and igf1r) peaked at 7 mm SL in all larvae, corresponding with increased ROS expressions in cod muscle during the exponential stratified hyperplasia phase from 7 mm SL. Expression for muscle differentiation (mef2a) occurred continuously (strongest from 10 mm SL). Expressions for muscle proliferation (pcna) and hydrogen peroxide (H₂O₂) generation (sod1 and sod2) occurred in the 5 - 15 mm SL range, peaking at 10 mm SL in all larvae. A downregulation of sod1 and sod2 in skeletal muscle from 15 mm SL indicated the first response of the defense antioxidant system. Gene expressions related to glucose metabolism (slc2A11, pfk, fpb2, ldha) was 3 - 10 times higher in copepod-fed larvae than in rotifer/Artemia-fed larvae between 7 – 10 mm (live prey period). Copepods move faster than rotifers, and cod larvae will also gradually increase their active swimming periods, due to less viscous forces. Active swimming during the strongest muscle stratified hyperplasia phase (7 – 10 mm SL) could promote a better delivery and transport across the muscle membrane and intracellular flux through glycolysis and oxidative phosphorylation and would contribute to the observed earlier and more effective glucose metabolism in the larvae fed copepods. We suggest that active swimming is an important factor promoting cod larval muscle growth, especially during the strongest muscle hyperplasia phase between 7 and 10 mm SL. The rapid movements of copepods and better nutritional composition could play important roles in stabilizing ROS levels, promoting high swimming activities and enhancing long-term muscle growth in cod.

我们研究了第一种捕食猎物类型（桡足类或轮虫类）的分子效应（RNAseq 和 qPCR）卤虫) 对骨骼肌肌生成和生长动力学（增殖、分化）、新陈代谢（糖酵解、糖异生、氧化磷酸化）和抗氧化防御系统（鳕鱼中活性氧 (ROS) 的产生/调节虎杖) 幼虫骨骼肌。尽管与肥大和增生之间的肌肉生长动力学以及 ROS 的产生和调节相关的基因表达的变化主要发生在 5、10 和 15 毫米标准长度 (SL) 附近，但摄食桡足类幼虫的幼虫体细胞生长率明显更高对于两组。细胞膜蛋白的基因表达（如氮氧化物1和igf1r）在所有幼虫的 7 mm SL 处达到峰值，对应于从 7 mm SL 开始的指数分层增生期鳕鱼肌肉中 ROS 表达的增加。肌肉分化的表达 (mef2a) 连续发生（从 10 毫米 SL 开始最强）。肌肉增殖的表达式 (pcna) 和过氧化氢 (H ₂ O ₂ ) 生成 (草皮1和草皮2) 发生在 5-15 毫米 SL 范围内，所有幼虫在 10 毫米 SL 处达到峰值。下调草皮1和草皮2在 15 mm SL 的骨骼肌中，表明防御抗氧化系统的第一个反应。与糖代谢相关的基因表达 (slc2A11,pfk,fpb2,乳酸菌) 在桡足类喂养的幼虫中比在轮虫中高 3 - 10 倍/卤虫- 喂食 7 – 10 毫米之间的幼虫（活猎物期）。桡足类的移动速度比轮虫快，鳕鱼幼虫的活跃游泳时间也会逐渐增加，因为粘性力较小。在最强的肌肉分层增生阶段（7 - 10 mm SL）进行主动游泳可以通过糖酵解和氧化磷酸化促进更好的肌肉膜传递和转运以及细胞内通量，并有助于观察到幼虫更早和更有效的葡萄糖代谢喂桡足类。我们认为，主动游泳是促进鳕鱼幼体肌肉生长的重要因素，尤其是在 7 至 10 毫米 SL 之间的最强肌肉增生阶段。桡足类的快速运动和更好的营养成分可以在稳定 ROS 水平方面发挥重要作用，