Fig. 2. tsh is required for Wg-mediated repression of the Ubx midgut enhancer. Side views of 12- to 14-h-old embryos bearing Ubx B, stained with antibody against lacZ to visualize enhancer activity. Anterior to the left, dorsal up. (A and D) wild type; (B) UAS.Wg/24B.Gal4; (C) tsh⁸/tsh⁸; UAS.Wg/24B.Gal4; (E) UAS.ArmS10; 24B.Gal4; (F) UAS.ArmS10, tsh⁸/tsh⁸; 24B.Gal4. Transcriptional repression due to high Wg signalling is indicated by open triangles, and transcriptional activation by arrowheads. Note the absence of repression in the tsh mutants. The positions of the second midgut constrictions (if present) is indicated by vertical lines.