Fig 1. dMyc knockdown in the eye imaginal disc induces glia overmigration.

(A) Schematic of the L2 (top left) and L3 (bottom) eye imaginal disc with color-coded expression domains of the Gal4 drivers used in this work. Red: repo-Gal4; Blue: ey-Gal4; Pink: dppblk-Gal4; Yellow: hth-Gal4. A dashed line represents the Morphogenetic Furrow (MF). (B–C) Atonal expression assessed by the reporter ato-GFP in control (B) and ey>dMyc RNAi (C). (D–E) Transverse view of the eye imaginal disc showing glia nuclei (red) and photoreceptor axons (grey) in Control (D) and ey>dMyc RNAi (E). An arrowhead indicates MF. (F–G) Photoreceptor cells stained with Elav (neuronal marker) in control (F) and ey>dMyc RNAi (G). (H–I) Wrapping glial cells are labelled with β-galactosidase to detect sprouty-LacZ (Spy-Z) (green) in control (H) and ey>dMyc RNAi (I). Cyan dashed line represents the glia overmigration position. (J–O) Glial cell membranes were detected with repoLexA-LexAopCD2-GFP (green) in control (J–L) and ey>dMyc RNAi (M–O). J’, J”, M’ and M” are magnifications of the white inset shown in panel J and M respectively. K and N correspond to transversal section of the optic stalk where wrapped axons are visible. Arrows point towards region of wrapping glia. L and O are magnifications of the dashed inset shown in panel J and M, respectively, showing glia morphology at the edge of migration. (P–Q) Early L3 eye imaginal disc of control (P) and ey>dMyc RNAi (Q). Glial cells migrate before the onset of differentiation (shown by Hrp staining) in ey>dMyc RNAi. (R) Pi3K92E knockdown in the eye disc reduces tissue growth but does not affect glia overmigration. (S) hth>dMyc RNAi eye discs showing glia overmigration. (T) repo>dcr-2>dMyc RNAi eye discs have reduced numbers of glial cells. Glial cells stained with Repo are shown in red; Hrp or Elav are used to label photoreceptors in grey, and DAPI stains DNA in blue. A dashed line represents the MF. Scale bars correspond to 10 μm.