The Iroquois homeobox genes function as dorsal selectors in the Drosophila head.
The Iroquois complex (Iro-C) genes are expressed in the dorsal compartment of the Drosophila eye/antenna imaginal disc. Previous work has shown that the Iro-C homeoproteins are essential for establishing a dorsoventral pattern organizing center necessary for eye development. Here we show that, in addition, the Iro-C products are required for the specification of dorsal head structures. In mosaic animals, the removal of the Iro-C transforms the dorsal head capsule into ventral structures, namely, ptilinum, prefrons and suborbital bristles. Moreover, the Iro-C(-) cells can give rise to an ectopic antenna and maxillary palpus, the main derivatives of the antenna part of the imaginal disc. These transformations are cell-autonomous, which indicates that the descendants of a dorsal Iro-C(-) cell can give rise to essentially all the ventral derivatives of the eye/antenna disc. These results support a role of the Iro-C as a dorsal selector in the eye and head capsule. Moreover, they reinforce the idea that developmental cues inherited from the distinct embryonic segments from which the eye/antenna disc originates play a minimal role in the patterning of this disc.
Cavodeassi
F
F
Centro de Biología Molecular Severo Ochoa, CSIC and UAM Cantoblanco, Spain.
Modolell
J
J
Campuzano
S
S
D000818:Animals; D019521:Body Patterning / Q000235:genetics; D002999:Clone Cells; D004330:Drosophila / Q000196:embryology* / Q000235:genetics; D029721:Drosophila Proteins; D005123:Eye / Q000196:embryology* / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D017344:Genes, Insect; D006257:Head / Q000196:embryology*; D006651:Histocytochemistry; D018398:Homeodomain Proteins / Q000378:metabolism; D007763:Lac Operon; D008855:Microscopy, Electron, Scanning; D014157:Transcription Factors
D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D014157:Transcription Factors; C117261:distal-less protein, insect; C108704:hth protein, Drosophila