Hth and Exd downregulation by Abd-B in the posterior abdominal segments.

<p>(A–B) Hth and Abd-B expression in wild type embryos at stage 12 (A) and stage13 (B). Hth protein disappears from the dorsal area where the spiracles are formed (A′ and A″ show a close up of A rotated 180° to keep dorsal up and anterior left). Note that in the spiracle region only a cluster of 8 cells retain high Hth levels. (C) Abd-B mutant showing elevated levels of Hth in the dorsal region. (D) Wild type st14 embryo stained with anti-Exd (D, green) and anti-AbdB (D′, red). Exd protein localizes to the nucleus in anterior segments (T2 inset) while is cytoplasmic in the posterior domain where Abd-B is expressed (A8 insets). (E) Dorsal view of a st11 embryo overexpressing Exd and Hth. Insets in E′ show that although the posterior A8 segment has high levels of nuclear Exd/Hth expression (only Hth shown in E) Abd-B expression is normal (E′). White arrows point to the A8 segment. Anterior left in all panels, and dorsal up in A–C.