Figure 4.

Temporal control of FLP recombination. Frt-flanked cassettes can be efficiently excised by heat shock-induced FLP expression. (A) Schematic representation of experimental setup and (B) single confocal sections of adult heads. The first time the animals are heat shocked they express mCh::HIS-58 and FLP. The FLP recombinase excises the mCh::his-58 cassette but efficient expression of the downstream GFP::his-58 fusion gene requires a second heat shock, suggesting that recombination is completed after the transient activation of the hsp-16.41 promoter ends. Bar, 10 µm. Chr, chromosome; mCh, mCherry.