title: Metamorphosis of an identified serotonergic neuron in the Drosophila olfactory system.
abstract: BACKGROUND
  Odors are detected by sensory neurons that carry information to the olfactory lobe where they connect to projection neurons and local interneurons in glomeruli: anatomically well-characterized structures that collect, integrate and relay information to higher centers. Recent studies have revealed that the sensitivity of such networks can be modulated by wide-field feedback neurons. The connectivity and function of such feedback neurons are themselves subject to alteration by external cues, such as hormones, stress, or experience. Very little is known about how this class of central neurons changes its anatomical properties to perform functions in altered developmental contexts. A mechanistic understanding of how central neurons change their anatomy to meet new functional requirements will benefit greatly from the establishment of a model preparation where cellular and molecular changes can be examined in an identified central neuron.
  
  
  RESULTS
  In this study, we examine a wide-field serotonergic neuron in the Drosophila olfactory pathway and map the dramatic changes that it undergoes from larva to adult. We show that expression of a dominant-negative form of the ecdysterone receptor prevents remodeling. We further use different transgenic constructs to silence neuronal activity and report defects in the morphology of the adult-specific dendritic trees. The branching of the presynaptic axonal arbors is regulated by mechanisms that affect axon growth and retrograde transport. The neuron develops its normal morphology in the absence of sensory input to the antennal lobe, or of the mushroom bodies. However, ablation of its presumptive postsynaptic partners, the projection neurons and/or local interneurons, affects the growth and branching of terminal arbors.
  
  
  CONCLUSIONS
  Our studies establish a cellular system for studying remodeling of a central neuromodulatory feedback neuron and also identify key elements in this process. Understanding the morphogenesis of such neurons, which have been shown in other systems to modulate the sensitivity and directionality of response to odors, links anatomy to the development of olfactory behavior.
authors.affiliation: National Centre for Biological Sciences, TIFR, GKVK PO, Bangalore 560065, India. broy@ncbs.res.in
authors.forename: Bidisha
authors.initials: B
authors.lastname: Roy
authors.forename: Ajeet P
authors.initials: AP
authors.lastname: Singh
authors.forename: Chetak
authors.initials: C
authors.lastname: Shetty
authors.forename: Varun
authors.initials: V
authors.lastname: Chaudhary
authors.forename: Annemarie
authors.initials: A
authors.lastname: North
authors.forename: Matthias
authors.initials: M
authors.lastname: Landgraf
authors.forename: K
authors.initials: K
authors.lastname: Vijayraghavan
authors.forename: Veronica
authors.initials: V
authors.lastname: Rodrigues
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D048430:Cell Shape / Q000235:genetics; D002490:Central Nervous System / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D004441:Ecdysterone / Q000378:metabolism; D005246:Feedback / Q000502:physiology; D020439:Growth Cones / Q000378:metabolism / Q000648:ultrastructure; D019044:Image Cytometry; D007814:Larva / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D008675:Metamorphosis, Biological / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D024521:Mushroom Bodies / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D009415:Nerve Net / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D009473:Neuronal Plasticity / Q000235:genetics; D009833:Olfactory Pathways / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D011987:Receptors, Steroid / Q000235:genetics / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000166:cytology / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D012903:Smell / Q000235:genetics
chemical_list: C105393:DCTN1-p150 protein, Drosophila; D029721:Drosophila Proteins; D008869:Microtubule-Associated Proteins; D011987:Receptors, Steroid; C034808:ecdysteroid receptor; D012701:Serotonin; D004441:Ecdysterone