Fig. 9. Comparison of CRISPR-Cas9 somatic mosaic knockouts at the Alba candidate locus.

The top row illustrates the phenotypic effect of mosaic deletions in the second exon of BarH1 (downward pointing red arrows onto second exon in blue), in a single representative Alba female wing and eye, made by Woronik et al. (28). The bottom row illustrates the result of mosaic deletions at the Alba locus made in this study, which is >25 kbp downstream of the BarH1 gene. In the middle row, the target locations of the CRISPR-Cas9 gRNAs used in both studies to generate double-stranded breaks are depicted (red arrows) relative to the BarH1 gene model (blue, exonic) and the 1200-bp Alba locus (pink, and the same window as in Fig. 4, with deletions indicated in red). Because deletions in the Alba locus cause similar changes in wing color to deletions in the BarH1 coding region, while aberrations in the eye are only seen in the latter, we conclude that the Alba locus harbors a tissue-specific CRE necessary for the Alba wing color phenotype.