A new strain of yellow catfish carrying genome edited myostatin alleles exhibits double muscling phenotype with hyperplasia

The yellow catfish (Pelteobagrus fulvidraco Richardson) is an important commercial freshwater aquaculture species in China. To generate a new strain of yellow catfish featured with good production traits, we knocked out mstna, an orthologue of mammalian myostatin gene (Mstn) encoding a negative regulator of skeletal muscle development and growth, using zinc finger nucleases. Similar to livestock carrying mutated Mstn, the genome-edited-mstna yellow catfish grew and bred normally, and both the male and female homozygous mutants displayed double muscling phenotype with two obvious muscle mass sticking out between head and dorsal fin when they reached 1-month-old and become more obvious with growth. The body weight of mstna null yellow catfish was heavier than (1.27- to 1.37-fold of) their wild-type siblings at 80 dpf (days post fertilization) and 210 dpf, respectively. Histological analysis revealed that the mstna knockout yellow catfish had increasing muscle fiber number but decreasing muscle fiber size in the skeletal muscle. Our results demonstrated that genome editing technology is a good choice for us to breed a new strain of yellow catfish with accelerated growth and more muscle mass.