title: Expression of the Drosophila homeobox gene, Distal-less, supports an ancestral role in neural development.
abstract: BACKGROUND
  Distal-less (Dll) encodes a homeodomain transcription factor expressed in developing appendages of organisms throughout metazoan phylogeny. Based on earlier observations in the limbless nematode Caenorhabditis elegans and the primitive chordate amphioxus, it was proposed that Dll had an ancestral function in nervous system development. Consistent with this hypothesis, Dll is necessary for the development of both peripheral and central components of the Drosophila olfactory system. Furthermore, vertebrate homologs of Dll, the Dlx genes, play critical roles in mammalian brain development.
  
  
  RESULTS
  Using fluorescent immunohistochemistry of fixed samples and multiphoton microscopy of living Drosophila embryos, we show that Dll is expressed in the embryonic, larval and adult central nervous system and peripheral nervous system (PNS) in embryonic and larval neurons, brain and ventral nerve cord glia, as well as in PNS structures associated with chemosensation. In adult flies, Dll expression is expressed in the optic lobes, central brain regions and the antennal lobes.
  
  
  CONCLUSIONS
  Characterization of Dll expression in the developing nervous system supports a role of Dll in neural development and function and establishes an important basis for determining the specific functional roles of Dll in Drosophila development and for comparative studies of Drosophila Dll functions with those of its vertebrate counterparts.
authors.affiliation: Neuroscience Training Program, University of Wisconsin-Madison.|School of Pharmacy, University of Wisconsin-Madison.
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Plavicki
authors.affiliation: Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison.
authors.forename: Jayne M
authors.initials: JM
authors.lastname: Squirrell
authors.affiliation: Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison.|Department of Biomedical Engineering, University of Wisconsin-Madison.
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Eliceiri
authors.affiliation: Neuroscience Training Program, University of Wisconsin-Madison.|Department of Cell and Regenerative Biology, University of Wisconsin-Madison.
authors.forename: Grace
authors.initials: G
authors.lastname: Boekhoff-Falk
mesh_terms: D000818:Animals; D001921:Brain / Q000196:embryology* / Q000378:metabolism; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D055495:Neurogenesis / Q000235:genetics*; D013116:Spinal Cord / Q000196:embryology / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D014157:Transcription Factors; C117261:distal-less protein, insect
keywords: Dll; Dlx; nervous system; olfaction; sensory system