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Updated: Jul 13, 2026

Embryo Microinjection and Electroporation in the Chordate Ciona intestinalis
09:38

Embryo Microinjection and Electroporation in the Chordate Ciona intestinalis

Published on: October 16, 2016

Nodal regulates neural tube formation in the Ciona intestinalis embryo

Kaoru Mita1, Shigeki Fujiwara

  • 1Department of Materials Science, Kochi University, 2-5-1 Akebono-cho, Kochi-shi, Kochi 780-8520, Japan. b06d3a05@s.kochi-u.ac.jp

Development Genes and Evolution
|July 13, 2007
PubMed

Insights

In Ciona intestinalis, overexpressing Ci-lefty or inhibiting Nodal signaling disrupted neural tube closure. A Ci-Nodal, Ci-ZicL, and Ci-Cdx cascade is crucial for this process.

Area of Science:

  • Developmental biology
  • Chordate evolution
  • Molecular signaling pathways

Background:

  • Neural tube formation is a critical developmental process in chordates.
  • Nodal signaling plays a conserved role in embryonic development across deuterostomes.
  • The protochordate Ciona intestinalis offers a model to study early chordate developmental mechanisms.

Purpose of the Study:

  • To investigate the role of Ci-lefty and Nodal signaling in neural tube closure in Ciona intestinalis.
  • To identify downstream targets of Nodal signaling involved in neural tube formation.
  • To elucidate the regulatory cascade governing neural tube development in this species.

Main Methods:

  • Overexpression of Ci-lefty and Ci-nodal in Ciona intestinalis embryos.
  • Treatment of embryos with SB431542, a Nodal receptor inhibitor.
  • Analysis of neural tube closure defects and body morphology.
  • Expression analysis of known and novel Nodal target genes, including Ci-ZicL and Ci-cdx.
  • Functional analysis using dominant-negative Ci-cdx constructs.

Main Results:

  • Overexpression of Ci-lefty phenocopied Nodal pathway inhibition, causing dorsal bending and impaired anterior-posterior elongation.
  • Both Nodal pathway inhibition and Ci-lefty overexpression led to neural tube closure defects.
  • Overexpression of Ci-nodal also induced similar developmental defects, highlighting the importance of Nodal signaling quantity and spatial restriction.
  • Ci-Nodal activated orthologues of Zic (Ci-ZicL) and cdx (Ci-cdx).
  • Inhibition of Ci-cdx function resulted in neural tube formation defects comparable to Nodal pathway disruption.

Conclusions:

  • Ci-Lefty acts as an antagonist of Nodal signaling in Ciona intestinalis, similar to other deuterostomes.
  • A regulatory cascade involving Ci-Nodal, Ci-ZicL, and Ci-Cdx is essential for proper neural tube formation in Ciona.
  • This study reveals conserved molecular mechanisms underlying neural tube development in chordates.

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