The P{FRT(HF.ry+)lacZ.UAS.T7.FRT} construct contains two excisable FRT cassettes. The 5' cassette contains a 6.7kb 'homing fragment' from the bithorax complex (from the region between the bxd and iab-2 regulatory regions) plus the ry+t7.2 marker allele. The homing fragment causes the P{FRT(HF.ry+)lacZ.UAS.T7.FRT} element to insert preferentially into or near the bithorax complex. The 3' cassette contains, 1: UAS regulatory sequences (with a minimal TATA promoter) fused upstream of sequence encoding a lacZ reporter, 2: two tandem 49bp T7\RpT7 promoters (oriented towards the outside of the element). The construct is designed to study DNA accessibility, which can be assayed by measuring 1: activation of the UAS-lacZ reporter by a GAL4 driver 2: transcription by T7 RNA polymerase from the T7\RpT7 promoters and 3: excision of the FRT cassette(s) by FLP recombinase. In the absence of a GAL4 driver, the construct can also act as an enhancer trap, with expression of the lacZ reporter being influenced by neighbouring enhancer sequences (the expression may also be influenced in a negative manner by genomic silencing sequences).
Construct: A 6.7kb fragment from the region between the bxd and iab-2 regulatory regions.
Contains an Scer\FRT cassette containing HF-BXC6.7 and ry+t7.2. This is followed by Ecol\lacZHF.Scer\UAS and two tandem 49bp T7 promoters (oriented towards the outside of the P-element). Finally a third Scer\FRT site is present.