sktl mutants suppress the effects of increased Pld activity TEM analysis of photoreceptors. (A–D) Wild-type (A), sktl^Δ20/sktl^Δ1-1 (B), Pld alone (C), and Pld in a sktl^Δ20/sktl^Δ1-1 background (D) are shown. (E) Quantitation of rhabdomere biogenesis defects. Genotypes are marked. The x axis shows bins for ommatidia with a given number of rhabdomeres developed. The y axis shows the frequency of rhabdomeres falling within a given bin for each of the genotypes. (F–I) Overexpression of sktl in developing photoreceptors is shown. (F and G) TEM images of a single ommatidium from a fly expressing wild-type (F) and kinase-dead (G) sktl using GMR-GAL4. A massive block in rhabdomere biogenesis is seen when the wild-type transgene is expressed. (H and I) In contrast, when an Rh1-GAL4 driver is used to express wild-type (H) or kinase-dead (I) sktl, no defect in rhabdomere biogenesis is seen. Bars, 2 µm.