We used meiotic recombination to place medial P{RS5} insertions onto an attached-XY chromosome called C(1;Y)N12.

C(1;Y)N12 is marked with B[S] at the tip of its Y chromosome. Its X chromosome carries all X-linked genes except the heterochromatic bobbed gene.

A P{RS3} insertion near the distal X tip was then placed on each chromosome using meiotic recombination.

Each chromosome was combined with a genomic source of FLP recombinase to induce internal rearrangements within the P{RS3} and P{RS5} elements.  This disrupted the miniwhite markers.

Each chromosome was combined with a genomic source of FLP recombinase again to induce chromosomal inversions and reconstitute miniwhite at the distal inversion breakpoint.

We made most of the inversion + attached-XY chromosomes as shown above, but a few were made by an alternative, more efficient method. Internal rearrangements were induced in the progenitor P{RS3} and P{RS5} insertions to disrupt the miniwhite marker, as illustrated above. The rearranged insertions were combined in females where meiotic recombination could occur to place the insertions in cis. These females were crossed to males carrying a genomic source of FLP recombinase. FLP recombinase-expressing progeny bearing recombinant chromosomes were identified from their red mitotic eye clones. In most cases, inversions were recovered directly from these individuals as red-eyed progeny. Once inversions were recovered, they were placed on C(1;Y)N12 by meiotic recombination.