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Deuterostomic development in the protostome Priapulus caudatus
José M Martín-Durán1, Ralf Janssen, Sofia Wennberg
1Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen 5008, Norway.
Current Biology : CB
|October 30, 2012
Summary
The blastopore in Priapulus caudatus, a key protostome, forms the anus, mirroring deuterostome development. This finding suggests the bilaterian ancestor likely developed via a deuterostomic pattern, impacting evolutionary insights.
Area of Science:
- Developmental biology
- Evolutionary developmental biology
- Zoology
Background:
- The fate of the blastopore in the bilaterian ancestor is poorly understood, hindering reconstruction of early animal development.
- Variability in blastopore fate in protostomes complicates understanding the transition to bilateral symmetry.
Purpose of the Study:
- To investigate gastrulation and blastopore fate in the priapulid Priapulus caudatus, a key taxon for understanding protostome evolution.
- To characterize the embryonic expression of genes involved in gut patterning in P. caudatus.
Main Methods:
- Detailed observation of gastrulation in Priapulus caudatus embryos.
- Analysis of gene expression patterns for key developmental markers (brachyury, caudal, foxA, goosecoid).
Main Results:
- The blastopore in P. caudatus forms the anus.
- Hindgut markers (brachyury, caudal) are expressed in the blastopore and anus.
- Foregut markers (foxA, goosecoid) are expressed in the developing mouth.
Conclusions:
- Gastrulation in P. caudatus follows a deuterostomic pattern.
- This finding supports a deuterostomic mode of development in the last common bilaterian ancestor.
- Challenges the protostomic or amphistomic model for the bilaterian ancestor.
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