laboratoire de physique statistique
 
 
laboratoire de physique statistique

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PHYSICAL BIOLOGY 


2
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2011
Non-genetic individuality in Escherichia coli motor switching - Mora, Thierry and Bai, Fan and Che, Yong-Suk and Minamino, Tohru and Namba, Keiichi and Wingreen, Ned S.
PHYSICAL BIOLOGY 8 (2011)

Abstract : By analyzing 30 min, high-resolution recordings of single Escherichia coli flagellar motors in the physiological regime, we show that two main properties of motor switching-the mean clockwise and mean counter-clockwise interval durations-vary significantly. When we represent these quantities on a two-dimensional plot for several cells, the data do not fall on a one-dimensional curve, as expected with a single control parameter, but instead spread in two dimensions, pointing to motor individuality. The largest variations are in the mean counter-clockwise interval, and are attributable to variations in the concentration of the internal signaling molecule CheY-P. In contrast, variations in the mean clockwise interval are interpreted in terms of motor individuality. We argue that the sensitivity of the mean counter-clockwise interval to fluctuations in CheY-P is consistent with an optimal strategy of run and tumble. The concomittent variability in mean run length may allow populations of cells to better survive in rapidly changing environments by `hedging their bets'.
 
2009
Dynamical modeling of molecular constructions and setups for DNA unzipping - Barbieri, Carlo and Cocco, Simona and Monasson, Remi and Zamponi, Francesco
PHYSICAL BIOLOGY 6 (2009)

Abstract : We present a dynamical model of DNA mechanical unzipping under the action of a force. The model includes the motion of a fork in a sequence-dependent landscape, the trap(s) acting on the bead(s) and the polymeric components of the molecular construction (unzipped single strands of DNA and linkers). Different setups are considered to test the model, and the outcome of the simulations is compared to simpler dynamical models existing in the literature where polymers are assumed to be at equilibrium.