PUBLICATION

The zebrafish diwanka gene controls multiple aspects of motor axon migration

Authors
Schneider, V., Zeller, J., and Granato, M.
ID
ZDB-PUB-021017-65
Date
2002
Source
Developmental Biology   247(2): 497 (Abstract)
Registered Authors
Granato, Michael, Schneider, Valerie, Zeller, Joerg
Keywords
none
MeSH Terms
none
PubMed
none
Abstract
During development, axons rely upon surrounding tissues to provide guidance cues necessary for their migration to appropriate targets. Our previous studies showed that primary motor neurons require diwanka activity provided by adaxial cells (1). We have now extended our analysis of the roles of diwanka and adaxial cells to secondary motor neurons, whose axons migrate along the same pathways, but at later developmental stages. Using transgenic lines that express GFP in different populations of secondary motor neurons, we find that in diwanka embryos, secondary motor axons exhibit migration defects both similar to, and distinct from, those of primary motor axons. Like primary motor neurons, secondary nerves that normally project dorsally stall at spinal cord exit points. In contrast, ventral projecting nerves exit, but often at ectopic locations, are poorly fasiculated and frequently extend inappropriately into adjacent somites. To determine whether adaxial cell cues also play a role in secondary motor axon migration, we have analyzed you-too embryos, which lack this cell population. We find that, in contrast to diwanka embryos, the exit of all classes of secondary motor axons from the spinal cord is impaired in you-too embryos. Furthermore, the migration of secondary motor axons that do exit the spinal cord is frequently arrested prematurely. Our results suggest that adaxial cells are likely to be the source of multiple guidance cues that control different aspects of secondary motor axon migration. We will present evidence supporting this hypothesis and our progress in the cloning of diwanka. 1. Zeller and Granato, 1999, Development 126, 3461–3472.
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