Abstract

During the first few hours of development, the trunk of the Drosophila embryo becomes subdivided into 14 parasegments. This process, governed by a hierarchical cascade of different classes of segmentation genes, is one of the most famous textbook examples of developmental pattern formation. The first periodically expressed (stripy) genes are the pair-rule genes, which are initially expressed with double-segment periodicity. This surprising ‘pair-rule’ mode of patterning appears to be a derived feature of insects, since pair-rule gene expression is only ever segmental in most other arthropods.

The pair-rule genes regulate each other, leading to dynamic expression patterns and a transition from double- to single-segment periodicity. However, despite a long history of experimental work, this regulatory system has received little attention from modellers and is the least well-understood part of the segmentation cascade. I will be talking about a computational model of the pair-rule system I have been working on during my PhD so far, and how it has helped generate testable hypotheses about pair-rule patterning.