Transgenic construct used to study the mechanism of action of the gypsy insulator. Contains a reporter composed of four copies of the yolk protein fat body enhancer (FBE1) element upstream of the Yp2 promoter and 5' untranslated region fused to the lacZ coding region. A natural gypsy insulator (contains 12 su(Hw) protein binding sites) has been inserted between the FBE1 elements and the Yp2 promoter.