Temporal Separation in the Specification of Primary and Secondary Motoneurons in Zebrafish

Temporal Separation in the Specification of Primary and Secondary Motoneurons in Zebrafish In zebrafish there are two populations of motoneurons, primary and secondary, that are temporally separate in their development. To determine if midline cells play a role in the specification of these neurons, we analyzed both secondary and primary motoneurons in mutants lacking floor plate, notochord, or both floor plate and notochord. Our data show that the specification of secondary motoneurons, those most similar to motoneurons in birds and mammals, depends on the presence of either a differentiated floor plate or notochord. In the absence of both of these structures, secondary motoneurons fail to form. In contrast, primary motoneurons, early developing motoneurons found in fish and amphibians, can develop in the absence of both floor plate and notochord. A spatial correspondence is found between secondary motoneurons and sonic hedgehog -expressing floor plate and notochord. In contrast, primary motoneuronal specification depends on the presence of sonic hedgehog in gastrula axial mesoderm, the tissue that will give rise to the notochord. These results suggest that both primary and secondary motoneurons are specified by signals from midline tissues, but at very different stages of embryonic development. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Developmental Biology Elsevier

Temporal Separation in the Specification of Primary and Secondary Motoneurons in Zebrafish

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Publisher
Elsevier
Copyright
Copyright © 1997 Academic Press
ISSN
0012-1606
eISSN
1095-564X
DOI
10.1006/dbio.1997.8604
Publisher site
See Article on Publisher Site

Abstract

In zebrafish there are two populations of motoneurons, primary and secondary, that are temporally separate in their development. To determine if midline cells play a role in the specification of these neurons, we analyzed both secondary and primary motoneurons in mutants lacking floor plate, notochord, or both floor plate and notochord. Our data show that the specification of secondary motoneurons, those most similar to motoneurons in birds and mammals, depends on the presence of either a differentiated floor plate or notochord. In the absence of both of these structures, secondary motoneurons fail to form. In contrast, primary motoneurons, early developing motoneurons found in fish and amphibians, can develop in the absence of both floor plate and notochord. A spatial correspondence is found between secondary motoneurons and sonic hedgehog -expressing floor plate and notochord. In contrast, primary motoneuronal specification depends on the presence of sonic hedgehog in gastrula axial mesoderm, the tissue that will give rise to the notochord. These results suggest that both primary and secondary motoneurons are specified by signals from midline tissues, but at very different stages of embryonic development.

Journal

Developmental BiologyElsevier

Published: Jul 15, 1997

References

  • Patterning activities of vertebrate hedgehog proteins in the developing eye and brain
    Ekker, S.C.; Ungar, R.R.; Greenstein, P.; von Kessler, D.P.; Porter, J.A.; Moon, R.T.; Beachy, P.A.
  • Developmental regulation of Islet-1
    Inoue, A.; Takahashi, M.; Hatta, K.; Hotta, Y.; Okamoto, H.
  • Induction of motor neurons by Sonic hedgehog is independent of floor plate differentiation
    Tanabe, Y.; Roelink, H.; Jessell, T.M.
  • Molecular heterogeneity among primary motoneurons and within myotomes revealed by the differential mRNA expression of novel islet-1
    Tokumoto, M.; Gong, Z.; Tsubokawa, T.; Hew, C.L.; Uyemura, K.; Hotta, Y.; Okamoto, H.
  • Expression of a type II collagen
    Yan, Y.-L.; Hatta, K.; Riggleman, B.; Postlethwait, J.H.

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