Effect of a Photoshop Mutation on Expression of GFP Transgenes

<p>Pairs of larvae of genotypes <i>Upf2^25G/Y; e22c-GAL4, UAS-nls:DsRed2/UAS-GFP</i> (<i>Upf2^25G</i> mutant, left in each panel) and <i>w/Y; e22c-GAL4, UAS-nls:DsRed2/UAS-GFP</i> (<i>Upf2⁺</i> control, right in each panel). The <i>DsRed2</i> (internal control) transgene contains an SV40 3′ UTR and was the same in all larvae, whereas the <i>GFP</i> test transgene differed in reporter and 3′ UTR sequences as indicated. DsRed channel (A–G) shows effect of <i>Upf2^25G</i> on the internal control <i>DsRed2</i> transgene. GFP channel (A′–G′) shows effect of <i>Upf2^25G</i> on the <i>GFP</i> test transgenes indicated. Photographic exposures were the same and images were processed identically to facilitate comparison. Similar results were obtained for at least two independent insertions of each <i>eGFP</i>-variant transgene. The ratio of GFP expression for each transgene in <i>Upf2^25G</i> versus <i>Upf2⁺</i> larvae was quantitated by GFP fluorescence measurements of micrographs of pairs of <i>Upf2^25G</i> and <i>Upf2⁺</i> larvae, and the fluorescence ratio (average ± standard deviation, <i>n</i> = 2 independent insertions for each <i>eGFP</i> transgene) is shown. (The expression ratio of the <i>DsRed2</i> internal control construct in <i>Upf2^25G</i> versus <i>Upf2⁺</i> larvae was 4.7 ± 0.7). Only <i>GFP</i> transgenes with an SV40 3′ UTR were enhanced in <i>Upf2^25G</i> mutants, independent of the intron in this UTR. Transgenes with a 3′ UTR derived from <i>hsp70</i> were not enhanced. eGFP, enhanced GFP reporter; + I, with added synthetic intron; ΔI, SV40 intron deleted; pUAST.h, pUAST with <i>hsp70</i> 3′ UTR replacing SV40 3′ UTR. Bar, 1 mm.