Development Genes and Evolution

, Volume 224, Issue 1, pp 1–11

Oral–aboral identity displayed in the expression of HpHox3 and HpHox11/13 in the adult rudiment of the sea urchin Holopneustes purpurescens

Original Article

DOI: 10.1007/s00427-013-0457-5

Cite this article as:
Morris, V.B. & Byrne, M. Dev Genes Evol (2014) 224: 1. doi:10.1007/s00427-013-0457-5


Hox genes are noted for their roles in specifying axial identity in bilateral forms. In the radial echinoderms, the axis whose identity Hox genes might specify remains unclear. From the expression of Hox genes in the development of the sea urchin Holopneustes purpurescens reported here and that reported previously, we clarify the axis that might be specified by Hox genes in echinoderms. The expression of HpHox11/13 here is described at three developmental stages. The expression is around the rim of the blastopore in gastrulae, in the archenteron wall and adjacent mesoderm in early vestibula larvae, and in a patch of mesoderm close to the archenteron wall in later vestibula larvae. The retained expression of HpHox11/13 in the patch of mesoderm in the later vestibula larvae is, we suggest, indicative of a posterior or an aboral growth zone. The expression of HpHox3 at the echinoid-rudiment stage, in contrast, is in oral mesoderm beneath the epineural folds, concentrated in sites where the first three adult spines form. With the expression of HpHox5 and HpHox11/13 reported previously, the expressions here support the role of Hox genes in specifying oral–aboral identity in echinoderms. How such specification and a posterior growth zone add support to a concept of the structural homology between echinoderms and chordates is discussed.


Hox genes Oral–aboral identity Sea urchin Posterior growth zone Echinoderm–chordate homology 

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.School of Biological Sciences A12University of SydneyNSWAustralia
  2. 2.School of Medical Sciences F13University of SydneyNSWAustralia

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