Dynamic gene expression is required for anterior regionalization in a spider

doi:10.1073/pnas.0811150106

Dynamic gene expression is required for anterior regionalization in a spider

Department of Evolutionary Genetics, Institute for Genetics, University of Cologne, Zülpicher Strasse 47, 50674 Köln, Germany

Edited by Sean B. Carroll, University of Wisconsin, Madison, WI, and approved December 12, 2008 (received for review November 4, 2008)

Abstract

Patterning of a multicellular embryo requires precise spatiotemporal control of gene expression during development. The gradient of the morphogen bicoid regulates anterior regionalization in the syncytial blastoderm of Drosophila. However many arthropod embryos develop from a cellular blastoderm that does not allow the formation of transcription factor gradients. Here we show that correct anterior development of the cellularized embryo of the spider Achaearanea tepidariorum requires an anterior-to-posterior wave of dynamic gene expression for positioning the stripes of hairy, hedgehog, and orthodenticle expression. Surprisingly, this dynamic repositioning of the expression of these segmentation genes is blocked in orthodenticle^pRNAi embryos and no anterior structures are specified in those embryos. Our data suggest that dynamic gene expression across a field of cells is required for anterior regionalization in spiders and provides an explanation for the problem of how positional values for anterior segmentation genes are specified via a morphogen-independent mechanism across a field of cells.

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Footnotes

⁴To whom correspondence should be addressed. E-mail: damen{at}uni-koeln.de
Author contributions: M.P. and W.G.M.D. designed research; M.P., A.P.M., E.E.S., and N.M.F. performed research; M.P., A.P.M., and W.G.M.D. analyzed data; and W.G.M.D. wrote the paper.
↵¹Present address: Georg-August-Universität Göttingen, Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie GZMB Abteilung für Entwicklungsbiologie, Justus-von-Liebig-Weg 11, D-37077, Göttingen, Germany.
↵²Present address: Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Josef Baumann Gasse 1, A-1210 Wien, Austria.
↵³Present address: Institut für Entwicklungsbiologie, Universität zu Köln, Gyrhofstrasse 17, D-50923 Köln, Germany.
The authors declare no conflict of interest.
Data deposition: The sequences reported in this paper have been deposited in the GenBank database [accession nos. FM945393 (At-six3), FM945394 (At-Pax6), FM945395 (At-lab), FM945396 (At-Dfd), and FM945397 (At-dac)].
This article contains supporting information online at www.pnas.org/cgi/content/full/0811150106/DCSupplemental.