Lecturer: Dr. Yasmine Meroz
Affiliation: School of Engineering
and Applied Science, Harvard University
Abstract:
Dynamics of biological systems are
inherently stochastic from the level of
protein fluctuations, to cellular
transport, and all the way to
sensorimotor responses of whole
organisms. In many cases the
observed stochastic dynamics exhibit
exotic properties such as memory,
correlations and non-Gaussian
propagators, which cannot be
explained simply due to thermal
noise, pointing at complex underlying
physics. I present an approach
seeded in the statistical physics
analysis of stochastic trajectories [1],
to relate such observed complex
characteristics to minimal models of
the underlying physics.
I utilise this framework to investigate
the high-dimensional subdiffusive
dynamics of protein fluctuations,
characterising the structure of the
rough energy landscape and
revealing the coexistence of distinct
origins of subdiffusion [2]. The
multiple analogies between protein
dynamics and glassy systems hint
that this approach may also shed
light on the latter.
I then use a similar approach to
tackle information processing
mechanisms in biological systems,
where I analyse the response
trajectories of cell chemotaxis to
known stimuli [3]. I present a minimal
model which represents stochastic
processing via a memory kernel, and
predicts a coupling between the fast
membrane polarization (sensing),
and the slow cytoskeletal polarization
(movement). The model successfully
recovers experimental observations
including directional memory.
References
[1] Y. Meroz, I.M. Sokolov (2015) A toolbox
for determining subdiffusive mechanisms,
Physics Reports, 573(6), 1-29
[2] Y. Meroz, V. Ovchinnikov, M. Karplus (in
preparation) Coexisting Origins of
Anomalous Dynamics in Proteins
[3] H.V. Prentice-Mott*, Y. Meroz*, A.
Carlson, M.A. Levine, M.W. Davidson, D.
Irmia, G. Charras, L. Mahadevan, J.V. Shah
(2015) [* equal contribution] Directional
memory arises from long-lived cytoskeletal
asymmetries in polarized chemotactic cells.
PNAS, in press.