421 bp of upstream sequence drives expression similar to the wild-type salm transcript expression pattern in the blastoderm, in the "anterior" (parasegments 1-3), "horse shoe-shaped" (acron anlagen and the procephalic neurogenic region), and the "posterior" (parasegments 14, 15, and part of the hindgut primordium) domains. Additional ectopic expression is seen between the anterior and horse shoe-shaped domains.