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An amphioxus homeobox gene: sequence conservation, spatial expression during development and insights into vertebrate
P W Holland1, L Z Holland, N A Williams
1Department of Zoology, University of Oxford, UK.
Development (Cambridge, England)
|November 1, 1992
Summary
Investigating amphioxus embryonic development, this study cloned and analyzed the AmphiHox3 gene. Its expression patterns suggest the vertebrate brain is homologous to a large part of the amphioxus nerve cord.
Area of Science:
- Developmental Biology
- Evolutionary Biology
- Genetics
Background:
- Amphioxus embryology shares similarities with vertebrate embryology, indicating a close phylogenetic relationship.
- Amphioxus embryology is simpler, lacking pronounced craniofacial morphogenesis, offering insights into vertebrate evolutionary changes.
Purpose of the Study:
- To investigate molecular changes during vertebrate embryology evolution.
- To understand the relationship between amphioxus and vertebrate body plans through molecular analysis.
Main Methods:
- Cloning, DNA sequencing, and sequence analysis of the amphioxus homeobox gene, AmphiHox3.
- Expression analysis using whole mount in situ hybridization on amphioxus neurulae, embryos, and larvae.
Main Results:
- AmphiHox3 is homologous to mammalian Hox genes (e.g., mouse Hox-2.7/HoxB3) with conserved amino acid sequences.
- AmphiHox3 expression is localized in posterior mesoderm and specific regions of the dorsal nerve cord.
- Expression boundaries suggest the vertebrate brain is homologous to an extensive region of the amphioxus nerve cord.
Conclusions:
- The study provides the first molecular insights into amphioxus embryonic development and its relation to vertebrate body plans.
- AmphiHox3 gene expression patterns offer clues to the evolutionary origins of the vertebrate brain.