Figure 4.

dsRNA-mediated interference of TcUbx and Tcabd-A expression results in the production of legs on abdominal segments. (A) Fluorescent micrograph of the cuticle of a wild-type first instar larva. Note the absence of any appendages on the abdomen. (B–D) SEM showing the ventro-lateral aspect of the A1 segment in a larval-stage wild-type animal (B), a larval-stage animal that had been injected during embryogenesis with TcUbx-RNAi (C), and a larval-stage animal that had been injected during embryogenesis with Tcabd-A-RNAi. In the wild type, the cuticle of the A1 segment is smooth and no outgrowth is visible. In the TcUbx-RNAi injected animal, an appendage is present on the transformed A1 segment that is similar in appearance to that observed in a Utx^m115 mutant. Note the subterminal claw located roughly at the midpoint of the proximal-distal axis (arrow). In the Tcabd-A-RNAi animal, a small outgrowth is observed on the transformed A1 segment (arrow) as well as on the more posterior abdominal segments (not shown). (E) Fluorescent micrograph of the cuticle of a first instar larva injected with TcUbx-RNAi and Tcabd-A-RNAi. In this animal, thoracic-like limbs are present on the transformed abdominal segments A1–A8.