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Looking at the origin of phenotypic variation from pattern formation gene networks
1Developmental Biology Program, Institute of Biotechnology, FIN-00014, University of Helsinki, Helsinki, Finland. isaac.salazar@uab.cat
Journal of Biosciences
|November 19, 2009
Summary
Developmental gene networks are not strictly hierarchical as commonly believed. This review argues for non-hierarchical models incorporating morphology and epigenetics for a more accurate understanding of development.
Area of Science:
- Developmental Biology
- Evolutionary Developmental Biology
- Genetics
Background:
- Widespread views posit hierarchical and multilayered developmental gene networks.
- These models suggest top layers partition embryos, controlling downstream gene expression for finer subdivision.
Purpose of the Study:
- Critically review prevailing models of developmental gene network functioning.
- Challenge the hierarchical superstructure concept in developmental genetics.
Main Methods:
- Review of developmental and evolutionary arguments.
- Analysis of experimental evidence on pattern formation.
- Examination of gene network modularity and epigenetic influences.
Main Results:
- Developmental gene networks are often non-hierarchical.
- Morphogenetic mechanisms are not subordinate to cell signaling.
- Gene network functioning is not solely decodable from promoter analysis.
- Modularity is extensive but blurred by developmental drift.
Conclusions:
- Hierarchical models fail to incorporate crucial morphogenetic mechanisms.
- Evolutionary opportunism and epigenetic factors significantly influence gene networks.
- Developmental gene networks exhibit non-hierarchical structures influenced by reuse and drift.
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