Partial rescue of dEsyt ^KO phenotypes by dEsyt ^CaBM . TEM images of a single ommatidium from photoreceptors of flies reared in dark (* - R7 photoreceptor). (A) (i) dEsyt^KO- day 1 (iii) dEsyt^KO - day 14. (B) (i) Rh1>dEsyt::GFP; dEsyt^KO - day 1 (iii) Rh1>dEsyt::GFP; dEsyt^KO - day 14. (C) (i) Rh1>dEsyt^CaBM::GFP; dEsyt^KO - day 1. (iii) Rh1>dEsyt^CaBM::GFP; dEsyt^KO - day 14. (Ai, iii, Biii, and Ci, iii) Scale bar: 1 µm; (Bi) Scale bar: 2 µm. (A-ii, iv, B-ii, iv, and C-ii, iv) Magnified image showing a single photoreceptor from the ommatidium image shown on the left. (Bii) Scale bar: 200 nm; (Aii, iv, Biv, and Cii, iv) Scale bar: 500 nm. (D) Quantification of the number of MCS per photoreceptor of day-1-old dark-reared flies, X-axis indicates the genotype and Y-axis indicates the number of MCS/photoreceptor, n = 25 photoreceptors from three separate flies (R1–R6). [N = 3; n = 25]. (E) Quantification of the number of MCS per photoreceptor of flies reared in 14 Day CD (Constant Dark), X-axis indicates the genotype and age of the flies and Y-axis indicates the number of MCS/photoreceptor, n = 25 photoreceptors from three separate flies (R1–R6). [N = 3; n = 25]. (D and E) Violin plots with mean ± SD are shown. Statistical tests: One-way ANOVA with post hoc Tukey’s multiple pairwise comparison. **P value <0.01; ***P value <0.001; ****P value <0.0001.