title: Experience-dependent versus experience-independent postembryonic development of distinct groups of zebrafish olfactory glomeruli.
abstract: Olfactory glomeruli are innervated with great precision by the axons of different olfactory sensory neuron types and act as functional units in odor information processing. Approximately 140 glomeruli are present in each olfactory bulb of adult zebrafish; these units consist of either highly stereotypic large glomeruli or smaller anatomically indistinguishable glomeruli. In the present study, we investigated developmental differences among these types of glomeruli. We observed that 10 large and individually identifiable glomeruli already developed before hatching, at 72 h after fertilization, in configurations that resembled their mature organization. However, the cross-sectional area of these glomeruli increased throughout larval development, and they eventually comprised the largest units in postlarval olfactory bulbs. In contrast, small and anatomically indistinguishable glomeruli formed only after hatching, apparently by segregating from five larger precursors that were identifiable during embryonic development. The differentiation of these small glomeruli proceeded with conspicuous variation in number and arrangement, both among larvae and between olfactory bulbs of the same individuals. To determine factors that might contribute to this variability, we investigated the effects of olfactory enrichment on the development of amino acid-responsive lateral glomeruli, which include both large and small units. Larvae reared in an amino acid-enriched environment had normal large lateral glomeruli, but the small lateral glomeruli were more numerous and displayed reduced cross-sectional areas compared with glomeruli in control animals. Our results suggest that large and small glomeruli mature via distinct developmental processes that may be differentially influenced by sensory experience.
authors.affiliation: Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.
authors.forename: Oliver R
authors.initials: OR
authors.lastname: Braubach
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Miyasaka
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Koide
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yoshihara
authors.forename: Roger P
authors.initials: RP
authors.lastname: Croll
authors.forename: Alan
authors.initials: A
authors.lastname: Fine
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D030801:Animals, Genetically Modified; D004625:Embryo, Nonmammalian; D019204:GTP-Binding Proteins / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006433:Hemocyanins / Q000378:metabolism; D007814:Larva; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009434:Neural Pathways / Q000196:embryology / Q000254:growth & development; D009830:Olfactory Bulb / Q000166:cytology / Q000196:embryology / Q000254:growth & development; D018034:Olfactory Receptor Neurons / Q000187:drug effects / Q000502:physiology*; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000596:Amino Acids; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D029961:Zebrafish Proteins; D049452:Green Fluorescent Proteins; D006433:Hemocyanins; D019204:GTP-Binding Proteins; C032808:keyhole-limpet hemocyanin