L., 2007). In both dPob4 and dPobeSatoh et al. eLife 2015;4:e06306. DOI: 10.7554/eLife.11 ofResearch articleCell biologyFigure 9. Unfolded protein response (UPR) induced in dPob4 photoreceptor. (A) Projection image from the Z-series section with a 1 m interval of dPob4 mosaic retina expressing RFP (magenta) as a wild-type cell marker and Xbp1: GFP as a UPR sensor. The Xbp1:GFP signal (green) is Trisodium citrate dihydrate Autophagy enhanced by immunostaining utilizing anti-GFP antibody. Asterisks show dPob4 homozygous photoreceptors. (B) Immunostaining of a dPob4 mosaic retina expressing RFP (magenta) as a wild-type cell marker. Phosphorylated eukaryotic translation Initiation Element two is shown in green. Asterisks show dPob4 homozygous photoreceptors. DOI: 10.7554/eLife.06306.mutant mosaic retinas expressed Xbp1:GFP sensor in all R1-6 photoreceptors, and Xbp1:GFP fusion proteins had been detected inside the dPob mutant photoreceptors but not within the wild-type (Figure 9A and data not shown). Next, we examined the amount of eukaryotic translation Initiation Factor 2 (eIF2) Eniluracil Inhibitor phosphorylation simply because UPR is well known to induce eIF2 phosphorylation to attenuate protein translation around the ER membrane within a transduction pathway independent from IreI/Xbp1 (Ron and Walter, 2007; Cao and Kaufman, 2012). Anti-phospho-eIF2 signals were stronger in both dPob4 and dPobe02662 photoreceptors than in wild-type photoreceptors (Figure 9B and data not shown). These outcomes indicate that UPR is induced inside the dPob-deficient photoreceptors, similar to EMC mutant.Rhabdomere improvement and degeneration in dPob null mutantBecause the synthesis of lots of membrane proteins was affected in dPob mutant cells, we observed the phenotype of dPob mutant throughout the developmental processes of photoreceptors. In spite of the lack of a lot of membrane proteins, ommatidial formation was not impacted in dPob4 photoreceptors in mosaic retina; adherence junctions formed commonly (Figure 6E) along with the apical membrane was properly differentiated into stalks and rhabdomeres (identified with Crb and phosphorylated moesin, respectively) (Figure 6B and information not shown) (Karagiosis and Ready, 2004). The IRS was formed generally and rhabdomeres were nonetheless separated by IRSs (Figure 8A ). We observed dPob4 mosaic retinas at 58 and 75 pupal development (pd) by electron microscopy (Figure 10A,B). The wild-type photoreceptors at 58 pd had currently begun to amplify the rhabdomere membranes. The rhabdomeres have been shorter in dPob4 photoreceptors than in wild-Satoh et al. eLife 2015;four:e06306. DOI: ten.7554/eLife.12 ofResearch articleCell biologyFigure 10. Development and degeneration of dPob4 photoreceptor rhabdomeres. Electron microscopy of pupal and adult dPob4 mosaic retinas. Asterisks show dPob4 homozygous photoreceptors. Scale bar: 1 m. (A, B) dPob4 mosaic ommatidia from 58 pupal development (A) and 73 pupal improvement (B) below continuous light (L) condition. (C ) dPob4 mosaic ommatidia from flies reared in full darkness (D) (C, E) or beneath 12 hr light/12 hr dark situations (D, F). Ommatidia from 3-day-old (C, D) and 17-day-old (E, F) flies. (D, inset) dPob4 R5 photoreceptor rhabdomere at higher magnification. DOI: ten.7554/eLife.06306.Satoh et al. eLife 2015;four:e06306. DOI: ten.7554/eLife.13 ofResearch articleCell biologytype photoreceptors, but the distinction in their appearance was subtle at this stage. Until 75 pd, the microvilli of wild-type rhabdomeres have been 0.5 m extended and packed tightly. Nonetheless, the microvilli of dPob4 rhabdomeres at 73 pd re.