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Sealable Femtoliter Chamber Arrays for Cell-free Biology

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Effect of phenotypic selection on stochastic gene expression.

Thierry Mora¹, Aleksandra M Walczak

¹Laboratoire de Physique Statistique and ‡Laboratoire de Physique Théorique, CNRS, Université P. et M. Curie, École Normale Supérieure , Paris, France.

The Journal of Physical Chemistry. B

|June 26, 2013

Summary

Genetically identical cells adapt gene expression for optimal fitness. Selection influences protein levels, affecting population variability and response to stress, demonstrating a link between heritability and adaptation.

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Area of Science:

Cellular and Molecular Biology
Evolutionary Biology
Systems Biology

Background:

Genetically identical cells exhibit phenotypic variability, impacting responses to environmental signals like nutrients and drug stress.
Previous models often used discrete states, but this study focuses on a single, continuously variable trait.

Purpose of the Study:

To investigate how natural selection acts on a single gene's protein expression levels.
To model the population's adaptation and fitness enhancement through changes in expression.
To quantitatively link population fitness to expression heritability and diversity.

Main Methods:

Analysis of gene regulatory models under selection.
Calculation of steady-state distributions for protein expression levels.
Quantitative assessment of fitness, heritability, and expression diversity.

Main Results:

Populations adapt protein expression levels to enhance fitness.
Selection can modulate population-level expression variability, either increasing or decreasing it.
The stability of bimodal expression states and switching rates between metastable states are affected by selection.

Conclusions:

Selection actively shapes gene expression variability within populations.
Heritability and diversity of expression are key determinants of population fitness.
Understanding these dynamics is crucial for predicting cellular responses to environmental challenges.