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. 2019 Apr 4;212(2):489–508. doi: 10.1534/genetics.119.302165

Figure 4.

Figure 4

GIs, but not WIs, mediate transvection of e7 and 3xP3 enhancers to a heterologous, enhancerless hsp70 promoter (pH). Representative late larval wing disks and CNSs from the indicated genotypes are shown. (A–H) Projections of trans (GFP, green) and cis (LacZ red and DsRed blue, when present), expression from the same wing disk or CNS of each sample. ph-gfp produces no (cis) expression as a hemizygote (A and E), other than tracheal branch in the uninsulated version [white arrow in (E)], probably originating from enhancer trapping. The same is observed in the insulated version upon GI inactivation in the su(Hw)−/− background (F and G). Only combinations of transgenes with GIs in both homologs support transvection [GFP in AMPs and CNS in (B and C)], while congruency in white in the absence of GIs in one or both homologs does not (D and H). Depletion of Su(Hw) protein abolishes transvection [(F and G), which bear the same transgenes as (B and C), respectively]. Note a dotted pattern in the CNS in (C), manifested by the 3xP3 activity in cis (DsRed, in blue) and in trans (GFP, in green), which comes from a glial cell population (see blue pattern in Figure 1A). The artificial 3xP3 enhancer does not drive expression in wing disks.