Practice question

Thoracic segment identity depends on Antennapedia complex genes Sex combs reduced, Antennapedia, and adjacent Ultrabithorax. Antennapedia specifies second thoracic segment by promoting leg and dorsal mesothorax formation, while repressing head development programs in trunk. In Antepedia mutants, T2 transforms toward antenna or head fate; in gain-of-function, antenna becomes leg. Nanos governs posterior abdominal development, Gurken and Pipe control dorsal-ventral polarity, unrelated to thoracic identity. Therefore Antennapedia serves as thoracic selector gene interpreting segmentation cues and executing thoracic morphogenetic programs via activation of thoracic-specific effectors like apterous, vestigial, and decapentaplegic signaling modulators required for leg patterning and wing induction.