spacer gif spacer gif spacer gif spacer gif ARCHIVE ANNOUNCEMENT! spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

First published online 23 January 2008
doi: 10.1242/dev.018317

Development 135, 881-888 (2008)
Published by The Company of Biologists 2008
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
dev.018317v1
135/5/881    most recent
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Google Scholar
Right arrow Articles by Marques-Souza, H.
Right arrow Articles by Tautz, D.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Marques-Souza, H.
Right arrow Articles by Tautz, D.

Delimiting the conserved features of hunchback function for the trunk organization of insects

Henrique Marques-Souza1,*, Manuel Aranda1,* and Diethard Tautz2,{dagger}

1 Department of Genetics, University of Cologne, Zülpicherstrasse 47, 50674 Köln, Germany.
2 Max-Planck Institute for Evolutionary Biology, August-Thienemannstrasse 2, 24306 Plön, Germany.

{dagger} Author for correspondence (e-mail: tautz{at}mpil-ploen.mpg.de)

Accepted 28 December 2007

The gap gene hunchback in Drosophila acts during syncytial blastoderm stage via a short-range gradient and concentration-dependent activation or repression of target genes. Orthologues of hunchback can be easily found in other insects, but it has been unclear how well its functions are conserved. The segmentation process in most insect embryos occurs under cellular conditions, which should not allow the formation of diffusion-controlled transcription factor gradients. We have studied here in detail the function of hunchback in the short germ embryo of Tribolium using parental RNAi and interaction with possible target genes. We find that hunchback is a major regulator of the trunk gap genes and Hox genes in Tribolium, but may only indirectly be required to regulate other segmentation genes. The core function of hunchback appears to be the setting of the Ultrabithorax expression border via a repression effect, and the activation of the Krüppel expression domain. These regulatory effects are likely to be direct and are conserved between Drosophila and Tribolium. We find no evidence for a classical gap phenotype in the form of loss of segments in the region of expression of hunchback. However, the phenotypic effects in Tribolium are highly comparable with those found for other short germ embryos, i.e. the core functions of hunchback in Tribolium appear to be the same in these other insects, although they are evolutionarily more distant to Tribolium, than Tribolium is to Drosophila. These results allow the disentanglement of the conserved role of hunchback in insects from the derived features that have been acquired in the lineage towards Drosophila. Given that the gap phenotype appears to occur only in long germ embryos and that the main role of hunchback appears to be the regionalization of the embryo, it may be appropriate to revive an alternative name for the class of gap genes, namely `cardinal genes'.

Key words: Segmentation, Gap genes, Hox genes, Tribolium, Short germ embryogenesis






© The Company of Biologists Ltd 2008