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Updated: Aug 10, 2026
09:31
Expression of Fluorescent Proteins in Branchiostoma lanceolatum by mRNA Injection into Unfertilized Oocytes
Published on: January 12, 2015
Conserved RARE localization in amphioxus Hox clusters and implications for Hox code evolution in the vertebrate
Hiroshi Wada1, Hector Escriva, Shicui Zhang
1Seto Marine Biological Laboratory, FSERC, Kyoto University, Wakayama, Japan. 98champ@msg.biglobe.ne.jp
Summary
Conserved retinoic acid response elements (RAREs) regulate Hox gene expression in both amphioxus and vertebrates. This suggests that neural crest cell Hox expression evolved from ancient neural tube regulatory pathways.
Area of Science:
- Developmental Biology
- Evolutionary Biology
- Genetics
Background:
- The Hox code is crucial for vertebrate craniofacial development.
- Retinoic acid (RA)-dependent gene expression in neural tubes and neural crest cells is mediated by the 3' AmphiHox1 flanking region.
Purpose of the Study:
- To investigate the role of DR5-type RA response elements (RAREs) in the 3' AmphiHox1 flanking region of Branchiostoma floridae.
- To determine if these RAREs are conserved and functional in vertebrate development.
Main Methods:
- Reporter gene assays in chick embryos using flanking regions from Branchiostoma floridae and chick Hoxb1.
- Analysis of RARE location and function in amphioxus and vertebrate Hox clusters.
Main Results:
- DR5-type RAREs in the 3' AmphiHox1 flanking region of B. floridae are necessary and sufficient for reporter gene expression in chick neural tube and neural crest cells.
- A similar DR5 element in chick Hoxb1 drives comparable expression.
- AmphiHox3 contains a functional DR5-type RARE in its 5' flanking region, showing conserved RARE location and function.
Conclusions:
- Conserved RAREs mediate RA-dependent Hox gene regulation across amphioxus and vertebrates.
- Vertebrate neural crest Hox gene expression likely evolved through co-option of ancestral neural tube regulatory pathways.
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