Disruption of scale development by Delta-1 misexpression

Notch and its ligands are molecules known to be involved in many cell fate decisions. Due to the proposed role of this signaling system in the choice between feather and smooth skin fate in the embryonic chick, we sought to test whether Notch signaling may also play a role in determining scale fate. Notch-1 and -2, Serrate-1 and -2, and Delta-1 are expressed in the scales throughout their development. Misexpression of chick Delta-1 using a replication-competent retrovirus results in regions of scale loss. In addition, feather buds are often observed on some of the scuta scales. These results suggest a model in which Delta can act as an inhibitor of skin appendage fate as well as a promoter of feather fate.