Antennapedia

regulatory region of this gene result in the development of the second leg pair into ectopic antennae. By contrast gain-of-function alleles convert antennae into ectopic legs.^[1]

metazoan era. It is suggested that Antennapedia arose from Evx, a non-Hox family of genes. This duplication event of Evx into the Antp-class probably occurred prior to cnidarian divergence, as there are Cnidarians with Evx and without Hox class genes and vice versa.^[2]

down-regulation of the Antp gene in Parasteatoda tepidariorum leads to the development of a pair of ectopic legs, resulting in 10-legged mutant spiders. Drosophila Antp is thought to play an important role in the role of ectopic leg or antenna placement, but not in abdominal leg suppression. However, recent research supported that leg suppression was indeed performed by Antp in arachnids.^[3] This suggests that spiders and insects may have separately developed strategies of the leg suppression via the evolutionary pressure of convergence. Arachnids' Antp gene is different from other Antp Hox clusters, suggesting that it has evolved via a divergence event leading to the development on the leg suppression function. This example suggests how the functions of homeobox genes including Antp have evolved over time to account for different lineages' needs.^[3]

transcriptional processes, not all of their actions and functions have been discovered. Recent studies observed Antp and the Hox ortholog HoxC6 in Xenopus in order to further distinguish the evolution of these orthologues. HoxC6 was found to play an important role in gastrulation in the vertebrate Xenopus. However, gastrulation was also a target in the Drosophila Antp gene. The anterior–posterior pattern mechanism is highly conserved in these genes, as its function in Xenopus is clear, but it is unclear why it would be a target in Drosophila. The similarities continuously observed between Hox genes in vertebrates and Drosophila suggests a complex evolutionary history of the Antp Hox gene cluster, as well as reaffirms the importance of the conservation of this gene cluster in the evolution of body morphology.^[4]