CRISPR/Cas9-mediated mstnb1 disruption enhances growth in rainbow trout

The effects of clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated disruption of the myostatin gene (mstnb1) on the growth performance of rainbow trout (Oncorhynchus mykiss) were evaluated. Two specific guide RNAs (gRNAs) targeting the first exon of the target gene were co-injected into fertilized eggs. While the survival rate of the injected embryos at the swim-up stage was 23.5%, Sanger sequencing of F0 individuals confirmed the successful generation of mutations. During a 10-month growing period, quantifiable phenotypic data revealed a significant enhancement in macroscopic somatic growth. The mstnb1-F0 mosaic fish exhibited an approximate 56% increase in body weight compared to the wild-type (WT) control group. Specifically, the mutant group reached an average weight of 825.0 ± 12.3 g, significantly outperforming the WT group, which reached 464.1 ± 9.2 g. Our results demonstrate that disruption of the mstnb1 gene using CRISPR/Cas9 technology induces a striking somatic weight gain rather than merely altering microscopic muscle fiber characteristics, demonstrating high biotechnological potential for shortening production time and reducing unit costs in sustainable rainbow trout aquaculture.