Email updates

Keep up to date with the latest news and content from BMC Biology and BioMed Central.

Journal App

google play app store
Open Access Highly Accessed Research article

Uncoupling of complex regulatory patterning during evolution of larval development in echinoderms

Kristen A Yankura, Megan L Martik, Charlotte K Jennings and Veronica F Hinman*

Author affiliations

Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA

For all author emails, please log on.

Citation and License

BMC Biology 2010, 8:143  doi:10.1186/1741-7007-8-143

Published: 30 November 2010

Abstract

Background

Conservation of orthologous regulatory gene expression domains, especially along the neuroectodermal anterior-posterior axis, in animals as disparate as flies and vertebrates suggests that common patterning mechanisms have been conserved since the base of Bilateria. The homology of axial patterning is far less clear for the many marine animals that undergo a radical transformation in body plan during metamorphosis. The embryos of these animals are microscopic, feeding within the plankton until they metamorphose into their adult forms.

Results

We describe here the localization of 14 transcription factors within the ectoderm during early embryogenesis in Patiria miniata, a sea star with an indirectly developing planktonic bipinnaria larva. We find that the animal-vegetal axis of this very simple embryo is surprisingly well patterned. Furthermore, the patterning that we observe throughout the ectoderm generally corresponds to that of "head/anterior brain" patterning known for hemichordates and vertebrates, which share a common ancestor with the sea star. While we suggest here that aspects of head/anterior brain patterning are generally conserved, we show that another suite of genes involved in retinal determination is absent from the ectoderm of these echinoderms and instead operates within the mesoderm.

Conclusions

Our findings therefore extend, for the first time, evidence of a conserved axial pattering to echinoderm embryos exhibiting maximal indirect development. The dissociation of head/anterior brain patterning from "retinal specification" in echinoderm blastulae might reflect modular changes to a developmental gene regulatory network within the ectoderm that facilitates the evolution of these microscopic larvae.