The segment polarity network is a robust developmental module

• Published in: Nature (London) Vol. 406; no. 6792; pp. 188 - 192
• Main Authors: von Dassow, George, Meir, Eli, Munro, Edwin M, Odell, Garrett M
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 13.07.2000; Nature Publishing Group
• Subjects: Animals; Biological and medical sciences; Body Patterning - genetics; Body Patterning - physiology; Computer Simulation; Drosophila; Drosophila - embryology; Drosophila - genetics; Drosophila - physiology; Fundamental and applied biological sciences. Psychology; General aspects and techniques. Study of several systematic groups. Models; Genes; Genes, Insect; Hymenoptera; Insects; Invertebrates; Mathematical biology. Models; Models, Biological; pair-rule genes; Proteins; Techniques; Embryonic development; Segmentation; Insecta; Drosophila; Modular system; Gene expression; Drosophilidae; Arthropoda; Polarity; Simulation model; Invertebrata; Dynamic model; Diptera
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/35018085

All insects possess homologous segments, but segment specification differs radically among insect orders. In Drosophila, maternal morphogens control the patterned activation of gap genes, which encode transcriptional regulators that shape the patterned expression of pair-rule genes. This patterning cascade takes place before cellularization. Pair-rule gene products subsequently 'imprint' segment polarity genes with reiterated patterns, thus defining the primordial segments. This mechanism must be greatly modified in insect groups in which many segments emerge only after cellularization. In beetles and parasitic wasps, for instance, pair-rule homologues are expressed in patterns consistent with roles during segmentation, but these patterns emerge within cellular fields. In contrast, although in locusts pair-rule homologues may not control segmentation, some segment polarity genes and their interactions are conserved. Perhaps segmentation is modular, with each module autonomously expressing a characteristic intrinsic behaviour in response to transient stimuli. If so, evolution could rearrange inputs to modules without changing their intrinsic behaviours. Here we suggest, using computer simulations, that the Drosophila segment polarity genes constitute such a module, and that this module is resistant to variations in the kinetic constants that govern its behaviour.