Fig. 5. The expression and function of Notum in the eye periphery. (A-A") A notum-Gal4, UAS-lacZ pupal retina (34 hours APF) doubly stained for lacZ (green) and Escargot (red). Notum and Escargot expression coincides in the HC (arrowheads), PR and some 2°/3° pigment cells. (B-B") A notum-Gal4, UAS-lacZ pupal retina (32 hours APF) stained for lacZ (green), Cut (red) and Elav (blue). Notum expression is detected only in the cone (green) and not photoreceptor cells (blue). The more interior cone cells (B') are not visible at this focal plane. (C-C") A notum clone in the pupal eye (32 hours APF) marked black by the absence of GFP (green) showing precocious expression of Escargot (red) in the cone cells of peripheral ommatidia (arrowheads). (D,D') Patterning defects in notum clones (absence of green in D'') of 40 hours APF retinas. At this stage, the ommatidial death is in process, and degenerate cone cells (blue) and photoreceptors (red) can be observed in the second interior row of ommatidia that would not normally be affected (arrows). (E,E') A notum clone in the pupal eye (32 hours APF) marked black by the absence of GFP (green) showing an expansion of the Wg protein expression domain (blue, arrowhead). (F) Schematic summary of Notum expression in the marginal eye structures when compared with Wg expression (see also a summary of Escargot expression in Fig. 2G).