title: Ultrabithorax confers spatial identity in a context-specific manner in the Drosophila postembryonic ventral nervous system.
abstract: BACKGROUND
  In holometabolous insects such as Drosophila melanogaster, neuroblasts produce an initial population of diverse neurons during embryogenesis and a much larger set of adult-specific neurons during larval life. In the ventral CNS, many of these secondary neuronal lineages differ significantly from one body segment to another, suggesting a role for anteroposterior patterning genes.
  
  
  RESULTS
  Here we systematically characterize the expression pattern and function of the Hox gene Ultrabithorax (Ubx) in all 25 postembryonic lineages. We find that Ubx is expressed in a segment-, lineage-, and hemilineage-specific manner in the thoracic and anterior abdominal segments. When Ubx is removed from neuroblasts via mitotic recombination, neurons in these segments exhibit the morphologies and survival patterns of their anterior thoracic counterparts. Conversely, when Ubx is ectopically expressed in anterior thoracic segments, neurons exhibit complementary posterior transformation phenotypes.
  
  
  CONCLUSIONS
  Our findings demonstrate that Ubx plays a critical role in conferring segment-appropriate morphology and survival on individual neurons in the adult-specific ventral CNS. Moreover, while always conferring spatial identity in some sense, Ubx has been co-opted during evolution for distinct and even opposite functions in different neuronal hemilineages.
authors.affiliation: Biology Department, Bucknell University, Lewisburg, PA, USA. em031@bucknell.edu
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Marin
authors.forename: Katie E
authors.initials: KE
authors.lastname: Dry
authors.forename: Danielle R
authors.initials: DR
authors.lastname: Alaimo
authors.forename: Kirstin T
authors.initials: KT
authors.lastname: Rudd
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Cillo
authors.forename: Michael E
authors.initials: ME
authors.lastname: Clenshaw
authors.forename: Nicolas
authors.initials: N
authors.lastname: Negre
authors.forename: Kevin P
authors.initials: KP
authors.lastname: White
authors.forename: James W
authors.initials: JW
authors.lastname: Truman
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D016923:Cell Death / Q000235:genetics; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007814:Larva; D009420:Nervous System / Q000254:growth & development* / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D014157:Transcription Factors; C066177:Ubx protein, Drosophila