title: Topographic mapping in dorsoventral axis of the Xenopus retinotectal system depends on signaling through ephrin-B ligands.
abstract: Ephrin-B and EphB are distributed in matching dorsoventral gradients in the embryonic Xenopus visual system with retinal axons bearing high levels of ligand (dorsal) projecting to tectal regions with high receptor expression (ventral). In vitro stripe assays show that dorsal retinal axons prefer to grow on EphB receptor stripes supporting an attractive guidance mechanism. In vivo disruption of EphB/ephrin-B function by application of exogenous EphB or expression of dominant-negative ephrin-B ligand in dorsal retinal axons causes these axons to shift dorsally in the tectum, while misexpression of wild-type ephrin-B in ventral axons causes them to shift ventrally. These dorsoventral targeting errors are consistent with the hypothesis that an attractive mechanism that requires ephrin-B cytoplasmic domain is critical for retinotectal mapping in this axis.
authors.affiliation: Department of Anatomy, University of Cambridge, Downing Street, Cambridge CB2 3DY, United Kingdom. fm222@cam.ac.uk
authors.forename: Fanny
authors.initials: F
authors.lastname: Mann
authors.forename: Samiran
authors.initials: S
authors.lastname: Ray
authors.forename: William
authors.initials: W
authors.lastname: Harris
authors.forename: Christine
authors.initials: C
authors.lastname: Holt
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000502:physiology; D001931:Brain Mapping; D002450:Cell Communication / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D036387:Ephrin-B1; D036388:Ephrin-B2; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D020439:Growth Cones / Q000378:metabolism* / Q000648:ultrastructure; D008024:Ligands; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D016501:Neurites / Q000378:metabolism / Q000648:ultrastructure; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D036081:Receptors, Eph Family; D012160:Retina / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D003336:Tectum Mesencephali / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D014795:Visual Pathways / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology / Q000378:metabolism*
chemical_list: D036387:Ephrin-B1; D036388:Ephrin-B2; D008024:Ligands; D008565:Membrane Proteins; D012333:RNA, Messenger; D020794:Receptor Protein-Tyrosine Kinases; D036081:Receptors, Eph Family