Abstract

The Drosophila “segmentation cascade” is a paradigm for developmental pattern formation and has been studied for decades. However, two key aspects of Drosophila segmentation are still not well understood. First, the more complex later stages of patterning, involving the so-called “pair-rule” genes, are not understood at the systems level. Second, the relationship between the simultaneous, “long-germ” mode of patterning seen in Drosophila, and the sequential, “short-germ” mode of patterning seen in most other arthropods remains mysterious. I have been using a combination of models and experiments to unravel the first problem, revealing a previously unrecognised role for temporal information in spatially patterning the Drosophila embryo. Unexpectedly, my findings also shed light on the second problem, as they suggest a simple evolutionary mechanism by which to transition between simultaneous and sequential modes of segmentation.