Growth Performance After Agouti-Signaling Protein 1 () Overexpression in Transgenic Zebrafish.

The melanocortin system is a key structure in the regulation of energy balance. Overexpression of inverse agonists, agouti-signaling protein (ASIP), and agouti-related protein (AGRP) results in increased food intake, linear growth, and body weight. ASIP regulates dorsal-ventral pigment polarity through melanocortin 1 receptor (MC1R) and overexpression induces obesity in mice by binding to central MC4R. overexpression in transgenic zebrafish (-Tg) enhances growth, yet experiments show fish overexpressing do not develop obesity even under severe feeding regimes. -Tg fish do not need to eat more to grow larger and faster; thus, increased food efficiency can be observed. In addition, -Tg fish reared at high density are able to grow far more than wild-type (WT) fish reared at low density, although -Tg fish seem to be more sensitive to crowding stress than WT fish, thus making the melanocortin system a target for sustainable aquaculture, especially as the U.S. Food and Drug Association has recently approved transgenic fish trading.