Growth cones utilize both widespread and local directional cues in the zebrafish brain.
The distribution of cues that provide directional information for specific growth cones in the zebrafish brain was functionally assayed by transplanting epiphysial neurons to ectopic locations in the embryonic brain followed by determining the pathways taken by the donor axons. Epiphysial axons normally first extend ventrally from their position in the dorsal diencephalon and then turn and extend anteriorly in the ventral diencephalon. When transplanted to ectopic sites at other axial levels of the brain, where in principle the axons could extend in any direction, epiphysial axons consistently extended ventrally. Furthermore, following initial ventral extension ectopic epiphysial axons turned randomly in the anterior and posterior directions. These results suggest that the cues for ventral extension are widely distributed along the rostrocaudal axis of the zebrafish brain, but the cues for subsequent anterior extension are restricted to the site where the epiphysial axons normally turn longitudinally.
Kanki
J P
JP
Department of Biology, University of Michigan, Ann Arbor, Michigan, 48109-1048, USA.
Kuwada
J Y
JY
D000818:Animals; D001369:Axons / Q000648:ultrastructure; D001921:Brain / Q000196:embryology* / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental; D020439:Growth Cones / Q000648:ultrastructure*; D018398:Homeodomain Proteins / Q000235:genetics; D017403:In Situ Hybridization; D047908:Intracellular Signaling Peptides and Proteins; D060850:LIM-Homeodomain Proteins; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics; D009434:Neural Pathways / Q000196:embryology; D009474:Neurons / Q000637:transplantation; D014157:Transcription Factors; D016212:Transforming Growth Factor beta / Q000235:genetics; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics; D029961:Zebrafish Proteins
D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D060850:LIM-Homeodomain Proteins; D009419:Nerve Tissue Proteins; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D029961:Zebrafish Proteins; C063843:insulin gene enhancer binding protein Isl-1; C512832:ndr2 protein, zebrafish