Transgenic construct used to study whether the gypsy insulator can protect DNA replication from position effects. Contains (5' to 3'): a gypsy insulator - the y+mDint2 marker - a 3.8kb SalI genomic fragment from the third chromosome chorion gene cluster (this includes the ACE3 amplification control element, the Cp18 transcription unit, the Ori-β origin of replication and the Cp15 transcription unit).