Related Experiment Videos
Did the first chordates organize without the organizer?
Matthew J Kourakis1, William C Smith
1Molecular, Cell and Developmental Biology, University of California, Santa Barbara, CA 93106, USA.
Trends in Genetics : TIG
|July 19, 2005
Summary
The vertebrate organizer, crucial for body plan development, may have evolved later in vertebrates and played a permissive rather than instructive role. This challenges traditional models of early chordate evolution.
Area of Science:
- Developmental Biology
- Evolutionary Biology
- Chordate Embryogenesis
Background:
- Traditional models depict the organizer as inducing major body plan components in unpatterned vertebrate embryos.
- Recent molecular and genetic data necessitate a re-evaluation of the organizer's role and evolutionary origins.
Purpose of the Study:
- To reconcile the role of the organizer in vertebrate development with mechanisms in invertebrate chordates.
- To propose a revised evolutionary model for the chordate body plan and the vertebrate organizer.
Main Methods:
- Review of experimental data from vertebrate development.
- Analysis of molecular and genetic findings in embryogenesis.
- Comparison of developmental mechanisms across vertebrates and invertebrate chordates (ascidian urochordate).
Main Results:
- The organizer's role might be more permissive than instructive.
- The organizer may not have been present at the base of the chordate lineage.
- The organizer could be a later evolutionary innovation specific to the vertebrate lineage.
Conclusions:
- The evolutionary origin of the organizer requires a revised perspective.
- Understanding the organizer's permissive role offers insights into vertebrate body plan formation.
- Reconciliation of vertebrate and invertebrate chordate developmental mechanisms is possible through evolutionary analysis.