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Ras is an essential component for notochord formation during ascidian embryogenesis
1Department of Life Science, Tokyo Institute of Technology, Yokohama, Japan. nakatani@lifesci.ucsb.edu
Mechanisms of Development
|February 12, 1998
Summary
Ras signaling is crucial for notochord cell development in ascidian embryos. Inhibiting Ras prevents notochord formation, indicating its essential role in this developmental process.
Area of Science:
- Developmental Biology
- Cell Signaling
- Molecular Embryology
Background:
- Notochord cell fate specification in ascidian embryos relies on inductive interactions.
- Basic fibroblast growth factor (bFGF) exhibits notochord-inducing activity.
- Ras signaling pathway, mediated by Ras small-GTP binding protein, is involved in bFGF receptor signaling in vertebrates.
Purpose of the Study:
- To investigate the role of the Ras signaling pathway in ascidian notochord induction.
- To determine if Ras is essential for signal transduction during notochord formation.
Main Methods:
- Injection of dominant-negative Ras (RasN17) into fertilized ascidian eggs.
- Co-isolation of presumptive-notochord (A6.2) and inducer (A6.1) blastomeres followed by RasN17 injection.
- Treatment of RasN17-injected blastomeres with bFGF.
- Microinjection of constitutively active Ras (RasV12) into A6.2 blastomeres.
Main Results:
- RasN17 injection inhibited notochord formation, suggesting Ras pathway involvement.
- Notochord differentiation was suppressed when RasN17 was injected into presumptive-notochord cells.
- bFGF treatment failed to rescue notochord development in RasN17-injected cells.
- Constitutively active Ras (RasV12) injection did not bypass the requirement for notochord induction.
Conclusions:
- The Ras signaling pathway is essential for ascidian notochord formation.
- Additional signaling pathways must be activated concurrently for complete notochord development.