Loss of v100 causes slow, adult-onset neurodegeneration. (A and B) ERG recordings of 1-wk-old flies. Note that mutant ERGs lack the on transient (arrows) but display normal depolarization. (C and D) Eyes from 1-wk-old WT and v100 mutant flies labeled with the photoreceptor-specific rhabdomere marker chaoptin (green) and the nuclear marker Toto-3 (blue). (E and F) ERG recordings from 2–3-wk-old flies show a slight reduction in depolarization. (G and H) 2–3-wk-old WT and v100 mutant eyes. (I–L) ERGs and immunolabeling of 5-wk-old WT and mutant eyes reveal progressive degeneration. (M–P) ERG recordings and immunolabelings from 5-wk-old flies kept in the dark show attenuated mutant phenotypes. (Q) Quantification for ERG depolarizations. Ctrl, control. Error bars indicate SEM. Bar, 10 µm.