Abstract：
The Pacific white shrimp Litopenaeus vannamei is a representative species of decapod crustacean and an economically important marine aquaculture species worldwide. However, research on the genes involved in muscle growth and development in shrimp is still lacking. MyoD is recognized as a crucial regulator of myogenesis and plays an essential role in muscle growth and differentiation in various animals. Nonetheless, little information is available concerning the function of this gene among crustaceans. In this study, we identified a sequence of the MyoD gene (LvMyoD) with a conserved bHLH domain in the L. vannamei genome. Phylogenetic analysis revealed that both the overall protein sequence and specific functional sites of LvMyoD are highly conserved with those of other crustacean species and that they are evolutionarily closely related to vertebrate MyoD and Myf5. LvMyoD expression is initially high during early muscle development in shrimp and gradually decreases after 40 days post-larval development. In adults, the muscle-specific expression of LvMyoD was confirmed through RT-qPCR analysis. Knockdown of LvMyoD inhibited the growth of the shrimp in body length and weight. Histological observation and transcriptome sequencing of muscle samples after RNA interference (RNAi) revealed nuclear agglutination and looseness in muscle fibers. Additionally, we observed significant effects on the expression of genes involved in heat shock proteins, myosins, actins, protein synthesis, and glucose metabolism. These findings suggest that LvMyoD plays a critical role in regulating muscle protein synthesis and muscle cell differentiation. Overall, this study highlights the involvement of LvMyoD in myogenesis and muscle growth, suggesting that it is a potentially important regulatory target for shrimp breeding efforts.
摘要：
太平洋白虾凡纳滨对虾是十足类甲壳动物的代表种，也是世界范围内重要的海洋水产养殖物种。然而,对虾肌肉生长发育相关基因的研究尚缺乏。MyoD被认为是肌肉形成的关键调节因子，在各种动物的肌肉生长和分化中起着至关重要的作用。尽管如此，关于该基因在甲壳类动物中的功能的信息很少。在这项研究中,我们确定了MyoD基因（LvMyoD）的序列，在凡纳滨对虾乳杆菌基因组中具有保守的bHLH结构域。系统发育分析表明，LvMyoD的整体蛋白质序列和特定功能位点与其他甲壳类物种高度保守，并且在进化上与脊椎动物MyoD和Myf5密切相关。LvMyoD表达最初在虾的早期肌肉发育过程中很高，在幼虫发育后40天后逐渐降低。在成年人中,通过RT-qPCR分析证实了LvMyoD的肌肉特异性表达。敲除LvMyoD抑制了虾的体长和体重的生长。RNA干扰（RNAi）后肌肉样品的组织学观察和转录组测序显示肌纤维中的核凝集和松弛。此外,我们观察到对热休克蛋白相关基因表达的显著影响，肌球蛋白,actins,蛋白质合成，和葡萄糖代谢。这些发现表明LvMyoD在调节肌肉蛋白质合成和肌肉细胞分化中起关键作用。总的来说,这项研究强调了LvMyoD参与肌生成和肌肉生长，这表明它是虾育种工作的潜在重要调控目标。
