Figure 1. The yR7 subtype is lost in spineless mutants.

a, Three subtypes can be identified on the basis of molecular markers: ‘pale’ (blue), ‘yellow’ (yellow) and DRA (pink) ommatidia together form the wild-type retinal mosaic (schematic representation;dorsal is to the top). b, Schematic representation of the ss phenotype in R7 cells. c, Transverse section through a wild-type (WT) adult eye (left panel; dorsal is to the left). The arrow denotes the DRA. Ratio of R7 opsins in a wild-type whole-mount adult retina (right panel; dorsal is to the top) stained for Rh3 (red) and Rh4 (cyan). d, Transverse section through a ss^D115.7 whole-mutant adult eye (left panel). Rh3 (red) is expanded and Rh4 (cyan) is completely lost. Opsin expression in a mutant whole-mount adult retina is also shown (right panel). e, Whole-mount retina with mitotic clones lacking Spineless (marked by the absence of expression of the armadillo-lacZ (Arm-Z) construct, blue). Rh4 (green) is always absent from mutant clones. Rh3 expression is shown in red. f, Whole-mount retina with MARCM clones lacking Spineless (marked by the presence of GFP, green). Every GFP-positive cell expresses Rh3 (red), whereas Rh4 (blue) is always absent from mutant cells.