Fig. 7

Melanised scales that become white scales acquire pterin pigment granules visible under scanning electron microscopy. Individual P. canidia scales were removed from wild-type black and white regions, as well as from spalt mKO, and Distal-less mKO affected regions. A SEM images of a black scale and a white scale removed from the forewing of wild-type P. canidia. Close-up of a black scale showing no pigment granules present along the cross-ribs of the scale. Pigment granules are present in great numbers in white scales. B SEM images of black scales and white scales removed from a Dll crispant. This crispant had greatly reduced spots on its hindwing. Scales that lost melanin pigments showed a morphology resembling that of WT white scales. C SEM images of black and white scales removed from a spalt crispant. The SEM image labelled as spalt mKO showed a close-up view of a scale (originally black) removed from the CRISPR/Cas9 mosaic knock-out area. Black scales converted into white scales with pigment granules, resembling those of wild-type white scales. D SEM images of a spalt mutant that displayed an intermediate scale phenotype with less melanised scales in the black spot region. The morphology of these grey scales resembles that of WT black scales, but windows of these scales were not fully opened and there remains residues of the upper lamina. Scale bars: 2 μm