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BP: Fachverband Biologische Physik

BP 26: Posters II

BP 26.53: Poster

Donnerstag, 28. Februar 2008, 17:00–19:30, Poster A

A Paradigm for Phenotype Decision: Non-linear Dynamics Coupled to Low Number Stochastic Effects — •Jan-Timm Kuhr^1,3, Madeleine Leisner^2,3, Joachim Rädler³, Berenike Maier^2,3, and Erwin Frey^1,3 — ¹Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Germany — ²Institut für Allgemeine Zoologie und Genetik, Westfälische Wilhelms Universität, Germany — ³Department für Physik, Ludwig-Maximilians-Universität München, Germany

Many organisms show a variety of phenotypes, even in populations consisting of genetically identical individuals. An example is the bacterium B. subtilis: Upon overpopulation a fraction cells switches to the “competent” phenotype, developing the trait of taking up genetic material from the surrounding medium and integrating it into their own genome, thereby speeding up evolution of the species. The bulk population, reproducing asexual, holds up a status quo while competent cells increase genetic variability by switching to quasi-sexual reproduction.

Here we present a scheme describing this extraordinary process by non-linear dynamics coupled to low-number stochastic effects of the involved molecular components. A two-component system is derived, explaining different phenotypes by bifurcation analysis and switching by intrinsic fluctuations intensified by auto-feedback. All parameters where chosen in accordance with previous experiments. The model quantitatively reproduces our experimental findings and explains the fractional onset of competence development on the single cell level.