Summary: Modeling the segment polarity gene network
First: System is biologically defined; known expression patterns
Input: segment polarity genes
continuous model: transcription factors act as enzymes
Boolean model: mRNA and protein activity is switch-like
Validation: reproduces known gene expression patterns.
Explored: changes in kinetic parameters
changes in initial conditions
Insight: topology is a main source of robustness.
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Segmentation of the fruit fly embryo
ˇ Cell differentiation is based on differential gene expression.
ˇ The segment polarity genes determine and maintain the parasegment
Syncytial blastoderm, 1h End of gastrulation, 7h