Journal Article

How drosophila appendages develop

Morata, Ginés

2001

Overview

Key Points Drosophila appendages (legs, antennae, mouthparts, analia, wings and halteres) arise from imaginal discs in specific segments. The critical event that permits embryonic cells to develop into the appendage primordia is expression of a homeobox gene called Distal-less ( Dll ). All imaginal discs subdivide into anterior and posterior compartments. The wing also subdivides into dorsal and ventral compartments in later stages in development. Cells at compartment borders produce morphogens — secreted signalling molecules such as hedgehog (Hh), wingless (Wg) and decapentaplegic (Dpp) — that pattern appendages by forming gradients. Cells respond to these morphogens by activating different patterns of gene expression, depending on the level of morphogen. Trunk cells become separated from appendage cells by mutual antagonism between Hh/Wg/Dpp at the centre of the disc, and the homeobox genes homothorax ( hth ) and extradenticle ( exd ), at the periphery. The response to the gradient of Wg and Dpp signals generates distinct genetic domains along the proximodistal axis of the appendage: high Wg and Dpp levels in the centre of the disc (which becomes the distal appendage) activate Dll , whereas moderate levels in the intermediate zone (which becomes the more proximal appendage) activate dachshund ( dac ). Appendage identity is specified by a combination of homeobox gene expression, which specifies the segment, and Dpp or Wg response genes, which specify dorsal or ventral properties. The mechanisms used in Drosophila to segregate the cells fated to form appendages and the genes involved are conserved in vertebrates. Just a glance at the body of the fruitfly Drosophila reveals that it has a main body part — the trunk — and a number of specialized appendages such as legs, wings, halteres and antennae. How do Drosophila appendages develop, what gives each appendage its unique identity, and what can the fruitfly teach us about appendage development in vertebrates?

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: Animals / Biochemistry / Biomedical and Life Sciences / Cancer Research / Cell Biology / Cloning / dachshund (dac) gene / decapentaplegic protein / Developmental Biology / Distal-less (DII) gene / Drosophila / Drosophila - growth & development / extradenticle (exd) gene / Fruits / Genes / Genes, Homeobox / hedgehog protein / homothorax (hth) gene / Insects / Life Sciences / Mutation / Proteins / review-article / Stem Cells / Vertebrates / wingless protein