UASp regulatory sequences drive expression of the first 534 nucleotides of the osk mRNA (encoding the 5'UTR and the first 173 amino acids of the long osk isoform) fused to mGFP6. This is followed by the osk 3'UTR SL2a transport and anchoring signal (TAS). A deletion in the 3'UTR (Δ550-597) has been replaced with UCAC (forms a tetra-loop to stabilize the adjacent stem region). A synthetic extension has been added to the base of the stem.