Critical dynamics in genetic regulatory networks: examples from four kingdoms

Area of Science:

• Systems biology
• Genetics
• Dynamical systems theory

Background:

• Organisms require coordinated gene expression for functionality amidst environmental changes.
• Genetic networks must be robust to external perturbations yet adaptable to new signals.
• A balance between robustness and adaptability is found in dynamical systems near phase transitions (criticality).

Purpose of the Study:

• To investigate the dynamical properties of gene transcription networks in various organisms.
• To determine if these networks operate near criticality.
• To explore criticality as a potential evolutionary mechanism for biological diversity.

Main Methods:

• Inferred gene regulatory interactions using hundreds of microarray experiments.
• Developed Boolean models of genetic networks based on experimental data.
• Analyzed the dynamical properties of these models.

Main Results:

• The gene transcription networks of S. cerevisiae, E. coli, B. subtilis, D. melanogaster (segment polarity), and A. thaliana (flower development) were studied.
• Analysis indicated that all five networks operate close to criticality.
• This finding is consistent across diverse species and biological systems.

Conclusions:

• Criticality in genetic networks allows for the coexistence of robustness and adaptability.
• The widespread operation of genetic networks near criticality suggests it's a fundamental evolutionary mechanism.
• This mechanism may explain the generation of diverse, dynamically robust life forms.