Post-transcriptional silencing of myostatin-1 in the spotted rose snapper (Lutjanus guttatus) promotes muscle hypertrophy.

Muscle growth is regulated by several factors including the growth differentiation factor 8, known as myostatin, an inhibitor of myocyte differentiation and proliferation. Research on myostatin regulation was already conducted to improve growth rates in farmed animals, including aquatic species. To explore the effects of myostatin inactivation in a commercial marine fish (spotted rose snapper, Lutjanus guttatus) in vivo, we induced post-transcriptional silencing (knockdown) of myostatin-1 (mstn-1) by injecting dsiRNA directly into the muscle of juvenile fish (87 days post-hatch) using a commercial polymer as vehicle. Results show a significant decrease in mstn-1 expression starting at 2 days after injection and for up to 5 days. Knockdown of mstn-1 caused muscle fiber hypertrophy (but not hyperplasia); however, there were no significant changes in weight or length. Although still experimental, this study provides evidence that temporary knockdown of mstn-1 in a commercial marine fish in vivo promotes fiber hypertrophy and therefore could potentially help grow-out programmes in fish aquaculture.