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. A 1.2 kb PstI-ApaI Fab-7 insulator fragment (nucleotides 83,666-84,897 of GenBank:U31961, does not include Polycomb response elements) has been inserted downstream of the body enhancer, at -893bp relative to the y transcription start site.