Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published July 28, 2015 | Published + Supplemental Material
Journal Article Open

Evolutionary rewiring of gene regulatory network linkages at divergence of the echinoid subclasses


Evolution of animal body plans occurs with changes in the encoded genomic programs that direct development, by alterations in the structure of encoded developmental gene-regulatory networks (GRNs). However, study of this most fundamental of evolutionary processes requires experimentally tractable, phylogenetically divergent organisms that differ morphologically while belonging to the same monophyletic clade, plus knowledge of the relevant GRNs operating in at least one of the species. These conditions are met in the divergent embryogenesis of the two extant, morphologically distinct, echinoid (sea urchin) subclasses, Euechinoidea and Cidaroidea, which diverged from a common late Paleozoic ancestor. Here we focus on striking differences in the mode of embryonic skeletogenesis in a euechinoid, the well-known model Strongylocentrotus purpuratus (Sp), vs. the cidaroid Eucidaris tribuloides (Et). At the level of descriptive embryology, skeletogenesis in Sp and Et has long been known to occur by distinct means. The complete GRN controlling this process is known for Sp. We carried out targeted functional analyses on Et skeletogenesis to identify the presence, or demonstrate the absence, of specific regulatory linkages and subcircuits key to the operation of the Sp skeletogenic GRN. Remarkably, most of the canonical design features of the Sp skeletogenic GRN that we examined are either missing or operate differently in Et. This work directly implies a dramatic reorganization of genomic regulatory circuitry concomitant with the divergence of the euechinoids, which began before the end-Permian extinction.

Additional Information

© 2015 National Academy of Sciences. Contributed by Eric H. Davidson, June 24, 2015 (sent for review May 20, 2015; reviewed by Douglas H. Erwin and Gregory A. Wray). Published online before print July 13, 2015. We thank Dr. Isabelle Peter for excellent discussions and for her creative suggestion of injecting the minimal Sp-pmar1 reporter construct; Ryan Range for providing plasmid containing β-catenin:GFP insert; and Miao Cui for providing C59 inhibitor and educating us in its use. We extend a special thanks to Andy Cameron and Parul Kudtakar at the Beckman Institute's Center for Computational Regulatory Genomics for providing support with transcriptomics in Eucidaris. This work was supported by a National Science Foundation CREATIV Grant 1240626. Author contributions: E.H.D. designed research; E.M.E. performed research; E.M.E. and E.H.D. analyzed data; and E.M.E. and E.H.D. wrote the paper. Reviewers: D.H.E., Smithsonian National Museum of Natural History; and G.A.W., Duke University. The authors declare no conflict of interest. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1509845112/-/DCSupplemental.

Attached Files

Published - PNAS-2015-Erkenbrack-E4075-84.pdf

Supplemental Material - pnas.201509845SI.pdf


Files (1.9 MB)
Name Size Download all
1.7 MB Preview Download
186.5 kB Preview Download

Additional details

August 22, 2023
August 22, 2023