Changing Roles of Homeotic Gene Functions in Arthropod Limb Development
The extensive diversification of limb morphologies during arthropod evolution has aided the spread of new species to distant locations and adaptation for distinct niches. Functional evolution of homeotic genes is thought to have played a key role in this diversification process, but the molecular mechanisms underlying this process remain to be elucidated. Insects and crustaceans are close relatives within arthropods and possess a variety of diversities in the shape of their limbs. Comparison of genetic circuitries underlying the formation of insect and crustacean limbs should reveal the genetic history of their morphological evolution. We have recently analyzed the functional role of ANTENNAPEDIA (ANTP) homeotic protein of the crustacean Daphnia magna and compared its properties to its weil studied counterpart, the insect Drosophila melanogaster.Our results suggest that highly restricted expression of ANTP in the first leg of Daphnia specifies its morphology. Furthermore, while the core ANTP function of specifying thoracic identity is conserved, changes in the protein region outside of the homeodomain altered the target gene specificity. Based on these findings, we discuss the role of homeotic gene evolution in diversification of arthropod limb morphology.
KeywordsHomeotic Gene Limb Development Thoracic Limb Homeotic Protein Denticle Belt
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