Seminar on the Theory of Complex Systems  Summer Term 2016

Confirmed:

• Thu 12.05.16   at 14 c.t.
  Nils Becker   Bioquant, Heidelberg
  Prediction in linear signalling networks
  

  Adaptation to changing environments is considered a defining property of life. The intuition is that some environmental change is sensed by the organism and then, later, elicits some appropriate response. However, in daily life we often not only react, but preempt environmental changes -- when there is a chance of rain I take my umbrella. Such anticipation necessarily involves the estimation of probabilities of future events. I will argue that similar forecasts can be made by single cells, by using biochemical signalling networks to predict external time-varying signals. To this end I discuss the response functions that maximize the predictive capabilities of linear biochemical signal transduction networks; these are seen to strike a balance between extrapolation and robustness against signal fluctuations. I then consider the chemotaxis behavior of E.coli and show that its response can be understood as a robust predictor of spatiotemporal variations in ligand concentration.

• Thu 19.05.16   at 14 c.t.
  Raffaello Potestio   MPI Polymer Physics, Mainz
  Up and Down the Ladder - A personal account of multi-scale modeling of biophysical systems
  

  A feature common to most biological systems is the interplay of characteristic length and time scales, which determines their mechanical and dynamical properties. This multi-scale nature limits our capability to investigate biomolecules by means of computer simulations: in fact, the size of the system often makes it impossible to treat the whole of it with atomistic resolution; at the same time, coarse-grained models, lacking relevant chemical details, might be a too crude approximation. In this talk I will review and discuss some examples of multi-scale methods aimed at incorporating, in a sequential or concurrent fashion, features characteristic of different length and time scales, in order to provide a computationally advantageous yet accurate description of the system.

• Thu 07.07.16   at 14 c.t.
  Igor Kulic   Institut Charles Sadron, Strasbourg
  Biofilament Confotronics
  

  Many biological structures, like viral capsids, transmembrane proteins and filaments from DNA, over F-actin to bacterial flagella are well known to undergo conformational transitions. The field of confotronics deals with the many-body dynamics of a large number such soft switchable (bistable) structures. More precisely it investigates how non-linear switchable monomer units mutually interact , how collective behavior emerges from interactions and in particular how mechanical information processing in such systems works. I will focus on the important example of microtubules that have only recently been shown to exhibit complex confotronic dynamics and will present the available biophysical evidence. We will end with a thought provoking conclusion. Microtubules could act as conformational wires able of rapidly transmitting structural information via tubulin dimer domino-switching on sub-second time scales along their full contour i.e. on typical cellular length scales.