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. Six copies of the third su(Hw) protein binding site of the gypsy insulator have been inserted between the FBE1 elements and the Yp2 promoter.