Heritable Targeted Inactivation of Myostatin Gene in Yellow Catfish (Pelteobagrus fulvidraco) Using Engineered Zinc Finger Nucleases

Yellow catfish ( Pelteobagrus fulvidraco ) is one of the most important freshwater aquaculture species in China. However, its small size and lower meat yield limit its edible value. Myostatin (MSTN) is a negative regulator of mammalian muscle growth. But, the function of Mstn in fish remains elusive. To explore roles of mstn gene in fish growth and create a strain of yellow catfish with high amount of muscle mass, we performed targeted disruption of mstn in yellow catfish using engineered zinc-finger nucleases (ZFNs). Employing zebrafish embryos as a screening system to identify ZFN activity, we obtained one pair of ZFNs that can edit mstn in yellow catfish genome. Using the ZFNs, we successfully obtained two founders (Founder July29-7 and Founder July29-8) carrying mutated mstn gene in their germ cells. The mutated mstn allele inherited from Founder July29-7 was a null allele ( mstn nju6 ) containing a 4 bp insertion, predicted to encode function null Mstn. The mutated mstn inherited from Founder July29-8 was a complex type of mutation ( mstn nju7 ), predicted to encode a protein lacking two amino acids in the N-terminal secretory signal of Mstn. Totally, we obtained 6 mstn nju6/+ and 14 mstn nju7/+ yellow catfish. To our best knowledge, this is the first endogenous gene knockout in aquaculture fish. Our result will help in understanding the roles of mstn gene in fish.