GAL4/UAS system [27 (link)] drivers used were btl-GAL4 [44 ], e22c-GAL4 [45 (link)], ppk-GAL4 [32 (link)], and da-GAL4 [24 (link)]. GFP and DsRed transgenes are referenced in
The photoshop mutations were obtained by mutagenesis of an isogenized y w FRT19A chromosome [22 (link)] with 25 mM ethane methyl sulfonate overnight [47 ] in a tracheal mutant screen (to be described elsewhere). The mutations used were on this chromosome unless otherwise noted. To generate homozygous mutant clones, 2- to 6-h-old embryos were collected at 25 °C from a cross of y w * FRT19A/FM7 females to gal80 FRT19A, hsFLP122/Y; btl-GAL4, UAS-GFP males. After a 45-min heat shock at 38 °C to induce FLP expression, embryos were returned to 25 °C to continue development. L3 larvae of genotype y w * FRT19A/gal80 FRT19A, hsFLP122; btl-GAL4, UAS-GFP/+ were identified by GFP mosaicism within the tracheal system and scored for the photoshop phenotype.
The original Smg132AP chromosome (designated 32AP†) carried lethal mutations not associated with the photoshop phenotype. Lethals were removed by crossing 32AP†/y w FRT19A females to w/Y; btl-GAL4, UAS-GFP males and identifying L3 larvae with enhanced GFP throughout their tracheal systems. These Smg132AP/Y; btl-GAL4, UAS-GFP/+ larvae developed into viable adult males. We also found a viable wing morphology mutation on 32AP† that is allelic to wavy. Existing wavy alleles do not show a photoshop phenotype, and the wing phenotype is separable from the photoshop phenotype, so wavy does not seem to contribute to the photoshop phenotype.
The Upf229AA chromosome carries a linked lethal mutation. When recombined away from Upf229AA, the mutation had no effect on tracheal development or reporter expression. However, we have not obtained a recombinant containing Upf229AA without the extraneous mutation.
For complementation tests of Upf2, we used genomic rescue transgenes located on the autosomes to generate males of genotype y w Upf214J v g f FRT19A/Y; P{w+, Upf2+}/+ and crossed these to y w * FRT19A/FM7c females, where the asterisk indicates the tested mutation. Absence of Bar+, white-eyed female progeny indicated failure to complement. For complementation tests of Upf1, we used the Y-linked duplication Dp(1;Y)BSC1, y+, which covers the Upf1 locus. Males of genotype Upf113D/Dp(1;Y)BSC1, y+ were crossed to Upf126A/FM7c females, and the absence of female Bar+ progeny indicated a failure to complement.