title: Genesis of rods in the zebrafish retina occurs in a microenvironment provided by polysialic acid-expressing Müller glia.
abstract: Polysialic acid (polySia) is a posttranslational modification of the neural cell adhesion molecule NCAM, which in the vertebrate brain is dynamically regulated during development and crucially involved in developmental and adult neurogenesis. In the fish retina, new neurons are persistently generated, but the possible contribution of polySia has not yet been addressed. Here we used immunohistochemistry with NCAM- and polySia-specific antibodies to study spatiotemporal expression patterns of NCAM and polySia in the developing and mature zebrafish retina. As early as 2.3 days postfertilization (dpf), NCAM but not polySia was detected on cell somata and fibers of the developing retina. At 4.3 dpf polySia immunoreactivity first appeared in the ventral retina and was localized to the nascent outer nuclear layer (ONL). In mature zebrafish, polySia immunoreactivity in the ONL extended to the entire retina. Colocalization with rhodopsin-EGFP in transgenic zebrafish or the Müller glia-specific protein cellular retinaldehyde-binding protein (CRALBP) revealed that polySia immunoreactivity was confined to the compartment of radial Müller glia processes crossing the ONL and to a small band of processes positioned proximal to the horizontal cell layer of the mature retina. As shown by 5-bromo-2-deoxyuridine (BrdU) labeling, both newly generated rod precursors within the mature ONL and precursors of the marginal zone were polySia-negative. Thus, polySia-negative rod precursors of the mature zebrafish retina face a polySia-NCAM-positive microenvironment presented by radial Müller glia. In view of the prominent role of polySia in other neurogenic systems, this pattern indicates that polySia provides environmental cues that are relevant for the generation of new rods.
authors.affiliation: Centre for Ophthalmology, Tübingen, Germany. stefan.kustermann@roche.com
authors.forename: Stefan
authors.initials: S
authors.lastname: Kustermann
authors.forename: Herbert
authors.initials: H
authors.lastname: Hildebrandt
authors.forename: Sylvia
authors.initials: S
authors.lastname: Bolz
authors.forename: Katja
authors.initials: K
authors.lastname: Dengler
authors.forename: Konrad
authors.initials: K
authors.lastname: Kohler
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D001973:Bromodeoxyuridine; D002352:Carrier Proteins / Q000378:metabolism; D049109:Cell Proliferation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012160:Retina / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000378:metabolism*; D012243:Rhodopsin / Q000378:metabolism; D012794:Sialic Acids / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000378:metabolism
chemical_list: C020932:11-cis-retinal-binding protein; D002352:Carrier Proteins; D019006:Neural Cell Adhesion Molecules; D011993:Recombinant Fusion Proteins; D012794:Sialic Acids; D029961:Zebrafish Proteins; C485184:enhanced green fluorescent protein; C435270:ncam1a protein, zebrafish; C021319:polysialic acid; D049452:Green Fluorescent Proteins; D012243:Rhodopsin; D001973:Bromodeoxyuridine