[Todos] charla

[Hernan G Solari]

El jueves 16/12 a las 15hs en el Aula de Seminarios de física nos dará 
una charla dentro del tema:  modelos matemáticos en biología, Joshua 
Weitz (de Gerogia Tech. U.). Titulo y abstracts como siguen:

To lyse or not to lyse: stochastic bacterial fate determination by
infecting viruses

Nearly 40 years ago, Philippe Kourilsky observed a strange
phenomenon when studying infections of bacterial hosts by
bacteriophage lambda.  Individual viruses tended to kill bacteria
when infecting bacteria alone, whereas infections by multiple
viruses caused lysogeny (where a viral genome is integrated into
the bacterial chromosome and then inherited vertically).  Since
then, the mechanistic basis for such a counter-intuitive response
to a small change has remained elusive.  However, interest in cell
fate determination has been revived, in part due to innovations in
single-cell microscopy that permit experimentalists to measure
fate on a cellular rather than a population level.  Here we
consider cellular decision making as resulting from first passage
processes of regulatory proteins and examine the effect of
transient dynamics within the initial lysis-lysogeny switch of
bacteriophage lambda.  We examine model predictions as resulting
from steady state and from transient dynamics and show that
transient fate determination permits robust and biased decision
making even in the face of variation in kinetic parameters.  We
compare our model results to a recent experimental study of cell
fate determination in single cell assays of multiply infected
bacteria (Zeng et al., Cell 2010).  Whereas the experimental study
proposed a ``quasi-independent'' hypothesis for cell fate
determination consistent with an observed data collapse, we
demonstrate that observed cell fate results are compatible with an
alternative form of data collapse.  We discuss a mechanistic basis
for the new data collapse and demonstrate results from an
explicitly stochastic model of fate determination that leads to
the same data collapse observed in the single cell study.  Our
findings elucidate the importance of transient gene regulatory
dynamics in fate determination, and present a novel alternative
hypothesis to explain single-cell level heterogeneity within the
phage lambda lysis-lysogeny decision switch.

estan todos invitados

saludos
            Hernan


-- 
Hernan G. Solari (solari en df.uba.ar http://www.df.uba.ar/~solari)