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Transfer of a large gene regulatory apparatus to a new developmental address in echinoid evolution

Gao, Feng and Davidson, Eric H. (2008) Transfer of a large gene regulatory apparatus to a new developmental address in echinoid evolution. Proceedings of the National Academy of Sciences of the United States of America, 105 (16). pp. 6091-6096. ISSN 0027-8424. PMCID PMC2329712. doi:10.1073/pnas.0801201105.

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Of the five echinoderm classes, only the modern sea urchins (euechinoids) generate a precociously specified embryonic micromere lineage that ingresses before gastrulation and then secretes the biomineral embryonic skeleton. The gene regulatory network (GRN) underlying the specification and differentiation of this lineage is now known. Many of the same differentiation genes as are used in the biomineralization of the embryo skeleton are also used to make the similar biomineral of the spines and test plates of the adult body. Here, we determine the components of the regulatory state upstream of these differentiation genes that are shared between embryonic and adult skeletogenesis. An abrupt “break point” in the micromere GRN is thus revealed, on one side of which most of the regulatory genes are used in both, and on the other side of which the regulatory apparatus is entirely micromere-specific. This reveals the specific linkages of the micromere GRN forged in the evolutionary process by which the skeletogenic gene batteries were caused to be activated in the embryonic micromere lineage. We also show, by comparison with adult skeletogenesis in the sea star, a distant echinoderm outgroup, that the regulatory apparatus responsible for driving the skeletogenic differentiation gene batteries is an ancient pleisiomorphic aspect of the echinoderm-specific regulatory heritage.

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Additional Information:© 2008 by The National Academy of Sciences of the USA. Contributed by Eric H. Davidson, February 5, 2008 (received for review October 24, 2007). Published online before print April 14, 2008, doi: 10.1073/pnas.0801201105. We thank Paola Oliveri and Qiang Tu for their extraordinary efforts in constructing the micromere GRN in sea urchins, which provided the foundations for this evolutionary study; Andy Cameron and Pat Leahy for the instruction in culturing sea urchin larvae; Veronica Hinman for the instruction in working with sea star embryos and for the screening of sea star ets1 cDNA clone; and Andy Cameron, Haixia Huang, and Viveca Sapin for help with microtomes. This work was supported by National Science Foundation Grant IOS-0641398 and the Camilla Chandler Frost Fellowship. Author contributions: F.G. and E.H.D. designed research; F.G. performed research; F.G. and E.H.D. analyzed data; and F.G. and E.H.D. wrote the paper. The authors declare no conflict of interest. This article contains supporting information online at
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Camilla Chandler Frost ScholarshipUNSPECIFIED
Subject Keywords:embryonic and adult skeletogenesis; gene network evolution; sea urchin; sea star
Issue or Number:16
PubMed Central ID:PMC2329712
Record Number:CaltechAUTHORS:GAOpnas08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11254
Deposited By: Archive Administrator
Deposited On:28 Jul 2008 21:17
Last Modified:08 Nov 2021 21:56

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