Transgenic construct in which y is used as a reporter in an enhancer blocking assay; used in a study to determine whether combinations of insulators can interact. Contains the y^+t7.7 minigene, which includes wing and body enhancers upstream of the transcription start site and a bristle enhancer in the intron. gypsy insulator sequence (bp 647-1077 of the transposon, contains 12 su(Hw) protein-binding sites) has been inserted downstream of the body enhancer, at -893bp relative to the y transcription start site.