A EcollacZ construct driven by 2.2 kb ofsna upstream sequence is expressed in the mesoderm, and in theprecursors and postmitotic neurons of the PNS, but not in the CNS.
A 2.2 kb snapromoter directs EcollacZ expression in a pattern similar toexpression directed by longer promoter constructs. Staining is strong in thepresumptive mesoderm and poles, but the lateral limits of expressionare fuzzier and slightly narrower than expression seen with longer constructs.