Fig. 5. Hox gene expression in wild-type, Tc'Kr^jaws and Tc'gt RNAi embryos. (A-D) Tc'Dfd (purple) and Tc'Ubx (blue) in situ double staining in stage-matched wild-type (A,B) and Tc'Kr^jaws mutant (C,D) embryos. In the mutant (D), the anterior boundary of the Tc'Ubx domain recedes towards the posterior. Tc'Dfd is expressed in three strong and one weak domain of double segmental periodicity. The two ectopic domains with stronger expression correspond to the ectopic maxillary segments in Tc'Kr^jaws. (E-J) Tc'Scr (purple) and Tc'Antp (blue) staining of wild-type (E-G) and Tc'Kr^jaws mutant (H-J) embryos. Tc'Scr is also strongly expressed in two ectopic domains with double-segmental periodicity, corresponding to the two ectopic labial segments (J). In contrast to Tc'Ubx, Tc'Antp expression is not shifted in Tc'Kr^jaws germbands (H-J). (K,L) Tc'Scr (brown) and Tc'Antp (blue) in Tc'gt RNAi embryos. Tc'Antp expands towards anterior by two segments, which correlates with the fact that the maxillary and labial segments attain thoracic appearance in Tc'gt RNAi embryos. High-level expression of Tc'Scr in the labial segment is repressed in these embryos. Weak Tc'Scr expression in the maxillary segment of older embryos (L) probably corresponds to the weak expression seen in the prothoracic segment in wild type (G).