title: Fate map of the distal portion of Drosophila proboscis as inferred from the expression and mutations of basic patterning genes.
abstract: The late-third-instar labial disc is comprised of two disc-proper cell layers, one representing mainly the ventral half of the anterior compartment (L-layer) and the other, the dorsal half of the anterior compartment and most, if not all, of the posterior compartment (M-layer). In the L-layer, Distal-less represses homothorax whereas no Distal-less-dependent homothorax repression occurs in the M-layer where Distal-less is coexpressed with homothorax. In wild-type labial discs, clawless, one of the two homeobox genes expressed in distal cells receiving maximum (Decapentaplegic+Wingless) signaling activity in leg and antennal discs, is specifically repressed by proboscipedia. A fate map, inferred from data on basic patterning gene expression in larval and pupal stages and mutant phenotypes, indicates the inner surface of the labial palpus, which includes the pseudotracheal region, to be a derivative of the distal portion of the M-layer expressing wingless, patched, Distal-less and homothorax. The outer surface of the labial palpus with more than 30 taste bristles derives from an L-layer area consisting of dorsal portions of the anterior and posterior compartments, each expressing Distal-less. Our analysis also indicates that, in adults and pupae, the anterior-posterior boundary, dividing roughly equally the outer surface of the distiproboscis, runs along the outer circumference of the inner surface of distiproboscis.
authors.affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Yasunaga
authors.forename: Kaoru
authors.initials: K
authors.lastname: Saigo
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kojima
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D004330:Drosophila / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development*; D029721:Drosophila Proteins / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D018398:Homeodomain Proteins / Q000235:genetics; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D051155:Wnt1 Protein
chemical_list: D029721:Drosophila Proteins; C063459:En protein, Drosophila; D018398:Homeodomain Proteins; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D051155:Wnt1 Protein; C064196:dpp protein, Drosophila; C074622:wg protein, Drosophila