Reparsing segmentation - transcription control of early body patterning in Drosophila

18 November 2005

Ulrike Gaul
Rockefeller University


The segmented body pattern of the Drosophila larva is generated by a hierarchical gene network active in the syncytial blastoderm. The network consists of ~50 genes, including maternal factors deposited as RNA/protein into the egg and several tiers of zygotic factors that act sequentially to generate increasingly refined and complex expression patterns along the antero-posterior axis. Most components of the network are transcription factors and regulation within the network is largely transcriptional; many cis- and trans-acting components are characterized. After tremendous initial progress, it has proved difficult to fully describe and understand this regulatory network, due to its complexity and the scale of the experimental effort necessary.

In recent work, we have (collaboratively with E. Siggia's group) applied computer algorithms ("Ahab", "Stubb") to detect cis-regulatory elements ("modules") in the segmentation network and predict their binding site composition. This allowed us to analyze the entire, now significantly enlarged, set of validated modules under uniform criteria and begin to extract basic rules governing their composition (Schroeder et al, below). This work has provided the background for our analysis of evolutionary changes in the network and current efforts (in collaboration with E. Segal) to predict module expression from sequence.

In my presentation, I will discuss what we have learned in these studies about the transcriptional control of pattern formation and about regulatory evolution.


M Schroeder, M Pearce, J Fak, HQ Fan, U Unnerstall, E Emberly, N Rajewsky, ED Siggia and U Gaul, "Transcriptional control in the segmentation gene network of Drosophila", PLoS Biol 2:E271 2004. HTML

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