CRISPR/Cas9-mediated myostatin disruption elevates the expression of genes associated with myofiber composition and growth in Exopalaemon carinicauda.

Myostatin (MSTN) is a negative regulator of skeletal muscle development and growth in vertebrates, but its role in crustaceans remains debated. To explore the functional role of MSTN in Exopalaemon carinicauda (EcMSTN) and to facilitate the development of new strains with enhanced growth rates, we investigated the molecular characteristics, expression patterns and functional implications of EcMSTN. We employed CRISPR/Cas9-mediated gene editing technology to generate EcMSTN knockout (EcMSTN-KO) prawns and subsequently monitored their hatching rate, survival rate and growth performance. The findings revealed that the hatching rate in the EcMSTN-KO group was only 11%, significantly lower than the 50% in the control group (P<0.05). In comparison to their wild-type (WT) siblings (1.212±0.114 cm), the EcMSTN-KO prawns (1.481±0.192) demonstrated a markedly enhanced body length (P<0.001). The expression of genes associated with myofiber composition and growth, including myosin heavy chain 2 (EcMHC2) and myosin light chain 1 (EcMLC1), exhibited a highly significant increase (P<0.001) in EcMSTN-KO prawns. Additionally, the expression of ecdysone receptor (EcEcR), a molt-related gene, was significantly elevated (P<0.001), while the expression of retinoid X receptor (EcRXR) showed no significant difference (P>0.05). The above studies indicate that EcMSTN functions as a negative regulator of muscle growth in E. carinicauda. Moreover, EcMSTN may play a role in molting. These results underscore the significant potential of MSTN as a genetic target for improving crustacean aquaculture, particularly through gene editing technologies aimed at enhancing growth traits.