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Stochasticity Open Seminar May 9, 2017, 12:00

Open Seminars of the Research Group on


Stochasticity and Control in the Dynamics and Diversity of Immune Repertories: an Example of Multi-Cellular Co-Operation


Tuesday, May 9, 2017, 12:00

at the Israel Institute for Advanced Studies, Room 128



Cell-state organization: The living cell as a sloppy dynamical system


Erez Braun (Technion)


Biological cells present a paradox, in that they show simultaneous stability and flexibility, allowing them to adapt to new environments and to evolve over time. The emergence of a stable cell state, well-defined morphology, metabolism and function, depends on genotype-to-phenotype associations. These in turn essentially reflect the organization of gene regulatory modes determining the temporal spectrum of expressed proteins. Cell-state organization is a dynamical process in which the molecular disorder manifests itself in a macroscopic order. The genome does not determine the ordered cell state; rather, it participates in this process by providing a set of constraints on the spectrum of regulatory modes, analogous to boundary conditions in physical dynamical systems.


We have developed an experimental framework in which cell populations are exposed to unforeseen challenges; novel perturbations they had not encountered before along their evolutionary history. Our study of cell populations exposed some intriguing characteristics of their behavior, showing that cell-state organization reflects exploratory dynamics in a degenerate, high-dimensional phase-space. Thus, at the fundamental level, the living cell behaves similar to other exploratory biological systems, e.g., the nerve and immune systems. I’ll discuss these exploratory dynamics, arguing that from the physics view point, the living cell belongs to a broad class of systems exhibiting sloppy dynamics, characterized by their insensitivity to the underlying parameters yet efficient convergence to a viable state. These concepts have significant consequences for our understanding of the emergence and stabilization of a cell phenotype in diverse biological contexts. In particular, understanding exploratory dynamics has implications on three major areas of biological inquiry: evolution, cell differentiation and cancer.



Related Research Questions


  1. What are the relevant variables determining the state of the living cell?
  2. How does order, a stable cell state, emerge from the intracellular molecular disorder?
  3. What is the potential of cells to adapt to unforeseen challenges and what type of dynamics enable this potential? 



Suggested Reading


The unforeseen challenge: from genotype-to-phenotype in cell populations
E. Braun
Rep. Prog. Phys. 78 (2015) 036602.



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