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Expression of the Hox gene complex in the indirect development of a sea urchin

Arenas-Mena, César and Martinez, Pedro and Cameron, R. Andrew and Davidson, Eric H. (1998) Expression of the Hox gene complex in the indirect development of a sea urchin. Proceedings of the National Academy of Sciences of the United States of America, 95 (22). pp. 13062-13067. ISSN 0027-8424. PMCID PMC23710. doi:10.1073/pnas.95.22.13062.

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Hox complex genes control spatial patterning mechanisms in the development of arthropod and vertebrate body plans. Hox genes are all expressed during embryogenesis in these groups, which are all directly developing organisms in that embryogenesis leads at once to formation of major elements of the respective adult body plans. In the maximally indirect development of a large variety of invertebrates, the process of embryogenesis leads only to a free-living, bilaterally organized feeding larva. Maximal indirect development is exemplified in sea urchins. The 5-fold radially symmetric adult body plan of the sea urchin is generated long after embryogenesis is complete, by a separate process occurring within imaginal tissues set aside in the larva. The single Hox gene complex of Strongylocentrotus purpuratus contains 10 genes, and expression of eight of these genes was measured by quantitative methods during both embryonic and larval developmental stages and also in adult tissues. Only two of these genes are used significantly during the entire process of embryogenesis per se, although all are copiously expressed during the stages when the adult body plan is forming in the imaginal rudiment. They are also all expressed in various combinations in adult tissues. Thus, development of a microscopic, free-living organism of bilaterian grade, the larva, does not appear to require expression of the Hox gene cluster as such, whereas development of the adult body plan does. These observations reflect on mechanisms by which bilaterian metazoans might have arisen in Precambrian evolution.

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Cameron, R. Andrew0000-0003-3947-6041
Additional Information:© 1998 National Academy of Sciences. Contributed by Eric H. Davidson, August 26, 1998. We are grateful to Prof. André Adoutte (Université de Paris-Sud) and to Prof. Ellen Rothenberg and Dr. Kevin Peterson (this institute) for reviews and discussions of this manuscript. This work was supported by the Stowers Institute for Medical Research and by National Institutes of Health Grant HD05753 (to E.H.D.) and from the National Science Foundation Grant IBN9604454 (to R.A.C.). The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
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Stowers Institute for Medical ResearchUNSPECIFIED
Issue or Number:22
PubMed Central ID:PMC23710
Record Number:CaltechAUTHORS:20121023-111759814
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ID Code:35034
Deposited On:23 Oct 2012 18:41
Last Modified:09 Nov 2021 23:12

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