Hox regulation of the <i>sna-rg</i> enhancer.

Expression of sna-rg-R2P2 minimal enhancer in a Dfd Scr double mutant (A) or in a hthP2 mutant (B). (C) Hox binding site modifications introduced in the sna-rg A1+A2proximal constructs beside a heat map indicating their SELEX-seq DNA-binding affinity preferences. (D) Embryo expressing simultaneously a sna-rg-mCherry construct (D” red) and sna-rg A1+A2proxHoxNull-GFP (D’ green) where the putative DNA binding site has been changed to a sequence not recognised by Hox-Exd-Hth in vitro. The expression of the sna-rg A1+A2proxHoxNull-GFP construct in the ring gland is not affected by the putative binding site mutation as well as maintaining the ectopic ventral expansion normal to a sna-rg A1+A2prox reporter. (E) sna-rg A1+A2prox strong class3Hox-GFP. (F) sna-rg A1+A2prox strong class2Hox-GFP. (G) sna-rg A1+A2prox strong class1Hox-GFP. Mutant embryos in (E-G) show strong expression in the maxilla and labium and the expression in other segments is barely affected. Panel C is modified from [40]. Embryos in (A) are also stained with anti-Scr to recognise the homozygous mutants. Scale bars 50 μm. (TIF)