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Evolution of the bilaterian larval foregut
D Arendt1, U Technau, J Wittbrodt
1European Molecular Biology Laboratory, Developmental Biology Programme, Meyerhofstrasse 1, 69012 Heidelberg, Germany.
Nature
|May 9, 2001
Summary
The evolution of larval guts in Bilateria suggests a conserved structure in common ancestors. Molecular data from Platynereis dumerilii indicate that early bilaterians had a tripartite gut in their primary larvae.
Area of Science:
- Developmental Biology
- Evolutionary Biology
- Molecular Biology
Background:
- Bilateria are divided into Protostomia and Deuterostomia, with distinct larval gut development.
- Primary larvae in both groups exhibit indirect development with ciliary locomotion.
- The independent evolution of tube-shaped guts in protostome and deuterostome larvae is a prevailing hypothesis.
Purpose of the Study:
- To investigate the evolutionary origins of larval gut development in Bilateria.
- To test the hypothesis of independent evolution of larval guts in Protostomia and Deuterostomia.
- To analyze gene expression patterns in Platynereis dumerilii trochophora larvae.
Main Methods:
- Analysis of gene homologue expression (brachyury, otx, goosecoid) in Platynereis dumerilii.
- Comparison of gene expression patterns with known data from Deuterostomia larvae.
- Focus on the polychaete Platynereis dumerilii as a representative protostome larva.
Main Results:
- Brachyury and otx gene expression in Platynereis larvae parallels that in Deuterostomia primary larvae.
- Goosecoid expression in Platynereis foregut mirrors its function in higher Deuterostomia.
- Molecular evidence supports the evolutionary conservation of larval foreguts and mouth regions.
Conclusions:
- The study provides molecular evidence for the conservation of larval foreguts and mouth regions between Protostomia and Deuterostomia.
- These findings challenge the hypothesis of independent evolution for larval guts.
- Data suggest that Urbilateria, the common bilaterian ancestor, possessed a tripartite tube-shaped gut in its primary larva.
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