Gene structure, expression and function analysis of the MyoD gene in the Pacific white shrimp Litopenaeus vannamei

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.