Figure 4.

dPIS is required for photoreceptor cell survival. A, Scheme for generation of the dpis knock-out by gene targeting. The organization of the dpis locus (top), the targeting construct (middle), and the expected structure of the targeted gene (bottom) are shown. A scale bar (kilobases) and the positions of the DNA primers used for PCR (short horizontal lines with arrowheads) are indicated. B, PCR product obtained on successful gene targeting. Shown are the results of PCR reactions using the primers indicated in A and genomic DNAs prepared from wild-type (wt), P[pw35–dpis], and dpis¹ flies. The positive PCR product is 3.8 kb and a 1 kb DNA size ladder (SM0313; Fermentas Life Sciences, Burlington, Ontario, Canada) is shown to the left. The bottom shows the 4.2 kb product generated using primers to the trp gene and the same genomic DNAs used as in the top. C–F, Scanning electron micrographs of compound eyes. C, The dpis⁺ flies were of the following genotype: GMR-hid P[neoFRT]19A/P[neoFRT]19A;EGUF. D, The dpis¹ flies were of the following genotype: GMR-hid P[neoFRT]19A/dpis¹ P[neoFRT]19A;EGUF. E, dpis¹;P[dpis]. F, dpis¹;P[hpis]. G, H, Transmission EMs of cross sections from the distal region of the compound eyes. G, The dpis⁺ flies were of the following genotype: GMR-hid P[neoFRT]19A/P[neoFRT]19A;EGUF. Scale bar, 10 μm. H, The dpis¹ flies were of the following genotype: GMR-hid P[neoFRT]19A/dpis¹ P[neoFRT]19A;EGUF.