A Distalless-responsive enhancer of the Hox gene Sex combs reduced is required for segment- and sex-specific sensory organ development in Drosophila
Fig 2
The upstream Scr enhancer is required for development of the T1 leg TBRs and SCBs.
In all leg images, proximal is up and the ventral surface is to the left. A. Wild-type adult male T1 leg with TBRs (arrowhead designates one TBR) and sex comb (arrow) located on the anterior surface. B. CRISPR deletion of the upstream enhancer results in a reduction of sex comb bristle number in heterozygote males (ScrΔCRE(upA-B)/+), as observed in legs heterozygous for Scr null alleles (29). C. Males homozygote for the CRISPR deletion (ScrΔCRE(upA-B)/ (ScrΔCRE(upA-B)/+) completely lack TBRs and SCBs on their T1 legs. Arrow designates ectopic spur bristles typical of T2 legs. D. Stereotypical pattern of sensory organs on the wild-type T2 leg. Note the similarities between the homozygote CRISPR deletion line (C) and a wild-type T2 leg, including the formation of spur bristles on the T1 leg tibia (arrow in C), as observed in legs with reduced Scr function [34]. E. Wild-type female T1 leg with TBRs located on the anterior surface. F. Homozygote CRISPR deletion of the upstream enhancer results in loss of TBRs in female T1 legs.