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Origin of anterior patterning. How old is our head?
1Department of Zoology and Animal Biology, University of Geneva, Switzerland. brigitte.galliot@zoo.unige.ch
Trends in Genetics : TIG
|January 19, 2000
Summary
Head development genes in animals with bilateral symmetry were found in radially organized animals. This suggests that the origins of head patterning are much older than scientists previously believed.
Area of Science:
- Developmental biology
- Evolutionary biology
- Genetics
Background:
- Most animals with bilateral symmetry (bilaterians) share homologous regulatory genes crucial for head development.
- Recent discoveries have identified homologues of these genes in radially organized animals like cnidarians (corals, sea anemones, jellyfish, hydra).
Purpose of the Study:
- To investigate the evolutionary origins of head patterning.
- To determine if genes involved in bilaterian head development are conserved in radially symmetric animals.
Main Methods:
- Cloning of homologous regulatory genes from cnidarian species.
- Analysis of gene expression patterns during development in hydrozoans.
Main Results:
- Homologues of key head development genes were successfully cloned from cnidarians.
- Some of these homologous genes were found to be expressed apically and/or during apical patterning in hydrozoans.
Conclusions:
- The presence and expression of these genes in cnidarians suggest that head patterning mechanisms are ancient.
- Head patterning may have originated earlier in evolutionary history than previously hypothesized, predating the emergence of bilateral symmetry.