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Updated: Feb 8, 2026

Embryo Microinjection and Electroporation in the Chordate Ciona intestinalis
Published on: October 16, 2016
Pax3/7 duplicated and diverged independently in amphioxus, the basal chordate lineage
Thomas B Barton-Owen1,2, David E K Ferrier1, Ildikó M L Somorjai3,4
1University of St Andrews, Gatty Marine Laboratory, Scottish Oceans Institute, East Sands, St Andrews, Fife, KY16 8LB, UK.
Abstract:
The Pax3/7 transcription factor family is integral to developmental gene networks contributing to important innovations in vertebrate evolution, including the neural crest. The basal chordate lineage of amphioxus is ideally placed to understand the dynamics of the gene regulatory network evolution that produced these novelties. We report here the discovery that the cephalochordate lineage possesses two Pax3/7 genes, Pax3/7a and Pax3/7b. The tandem duplication is ancestral to all extant amphioxus, occurring in both Asymmetron and Branchiostoma, but originated after the split from the lineage leading to vertebrates. The two paralogues are differentially expressed during embryonic development, particularly in neural and somitic tissues, suggesting distinct regulation. Our results have implications for the study of amphioxus regeneration, neural plate and crest evolution, and differential tandem paralogue evolution.
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