Figure 1

Generating molecularly defined deletions using Exelixis FRT -bearing transposon insertions. (a) The structure of the P{XP}, PBac{RB}and PBac{WH} constructs. The miniwhite-marked P element or piggyBac (PBac) constructs carry one or two FRT sequences with the indicated orientations. (miniwhite is a version of the white gene engineered for compact size.) P{XP} and PBac{WH} constructs also carry UAS sequences oriented to allow GAL4-induced expression of genes near the genomic insertion sites of the constructs. One UAS sequence in P{XP} can be removed by FLP-mediated recombination and it is likely that this cassette is absent from most deletion chromosomes, though we did not assay for it in our deletion chromosomes. (b-d) Simplified diagrams of FLP-mediated recombination events generating deletion chromosomes with different miniwhite copy numbers. (b) Our most frequently used screening strategy, where deletions are identified based on loss of miniwhite and the resulting white eye color. (c) The alternative strategy of identifying deletions based on increased miniwhite copy number relative to progenitor chromosomes and the resulting darker eye color. (d) Deletions can be recovered without a decrease or increase in miniwhite copy number, though we did not undertake such screens.