NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Xwnt-8 and lithium can act upon either dorsal mesodermal or neurectodermal cells to cause a loss of forebrain in Xenopus embryosWhen Xenopus gastrulae are made to misexpress Xwnt-8, or are exposed to lithium ions, they develop with a loss of anterior structures. In the current study, we have characterized the neural defects produced by either Xwnt-8 or lithium and have examined potential cellular mechanisms underlying this anterior truncation. We find that the primary defect in embryos exposed to lithium at successively earlier stages during gastrulation is a progressive rostral to caudal deletion of the forebrain, while hindbrain and spinal regions of the CNS remain intact. Misexpression of Xwnt-8 during gastrulation produces an identical loss of forebrain. Our results demonstrate that lithium and Wnts can act upon either prospective neural ectodermal cells, or upon dorsal mesodermal cells, to cause a loss of anterior pattern. Specifically, ectodermal cells isolated from lithium- or Wnt-exposed embryos are unable to form anterior neural tissue in response to inductive signals from normal dorsal mesoderm. In addition, although dorsal mesodermal cells from lithium- or Wnt-exposed embryos are specified properly, and produce normal levels of the anterior neural inducing molecules noggin and chordin, they show a greatly reduced capacity to induce anterior neural tissue in conjugated ectoderm. Taken together, our results are consistent with a model in which Wnt- or lithium-mediated signals can induce either mesodermal or ectodermal cells to produce a dominant posteriorizing morphogen which respecifies anterior neural tissue as posterior.
Document ID
20040172954
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Fredieu, J. R.
(Oregon Health Sciences University Portland 97201, United States)
Cui, Y.
Maier, D.
Danilchik, M. V.
Christian, J. L.
Date Acquired
August 22, 2013
Publication Date
June 1, 1997
Publication Information
Publication: Developmental biology
Volume: 186
Issue: 1
ISSN: 0012-1606
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: HD31087
CONTRACT_GRANT: HD07098
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Developmental Biology

Available Downloads

There are no available downloads for this record.
No Preview Available