title: Apoptosis ensures spacing pattern formation of Drosophila sensory organs.
abstract: BACKGROUND
  In both vertebrates and invertebrates, developing organs and tissues must be precisely patterned. One patterning mechanism is Notch/Delta-mediated lateral inhibition. Through the process of lateral inhibition, Drosophila sensory organ precursors (SOPs) are selected and sensory bristles form into a regular pattern. SOP cell fate is determined by high Delta expression and following expression of neurogenic genes like neuralized. SOP selection is spatially and temporally regulated; however, the dynamic process of precise pattern formation is not clearly understood.
  
  
  RESULTS
  In this study, using live-imaging analysis, we show that the appearance of neuralized-positive cells is random in both timing and position. Excess neuralized-positive cells are produced by developmental errors at several steps preceding and accompanying lateral inhibition. About 20% of the neuralized-positive cells show aberrant cell characteristics and high Notch activation, which not only suppress neural differentiation but also induce caspase-dependent cell death. These cells never develop into sensory organs, nor do they disturb bristle patterning.
  
  
  CONCLUSIONS
  Our study reveals the incidence of developmental errors that produce excess neuralized-positive cells during sensory organ development. Notch activation in neuralized-positive cells determines aberrant cell fate and typically induces caspase-dependent cell death. Apoptosis is utilized as a mechanism to remove cells that start neural differentiation at aberrant positions and timing and to ensure robust spacing pattern formation.
authors.affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Koto
authors.forename: Erina
authors.initials: E
authors.lastname: Kuranaga
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miura
mesh_terms: D000818:Animals; D000906:Antibodies; D017209:Apoptosis / Q000502:physiology*; D019521:Body Patterning / Q000502:physiology*; D004330:Drosophila / Q000254:growth & development*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D011679:Pupa / Q000254:growth & development; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D012679:Sense Organs / Q000254:growth & development*
chemical_list: D000906:Antibodies; D029721:Drosophila Proteins; C497759:N protein, Drosophila; D051880:Receptors, Notch