MERCREDI 18 MARS 2009
14 heures
Salle Séminaire 5
Centre de Physique Théorique
Marseille-Luminy

Todd Young
Department of Mathematics
Ohio University

Title: Models of Cell Cycle Dynamics and Clustering

Abstract: Biologists have long observed periodic-like oxygen
consumption oscillations in yeast populations under certain conditions
and several unsatisfactory explanations for this phenomenon have been
proposed.We hypothesize that these oscillations could be caused by a
weak form of cell cycle synchronization that we call clustering. We
develop some novel ODE models of the cell cycle. We give proofs and
simulations showing that both positive and negative feedback are
possible agents that can cause clustering of populations within the
cell cycle for these models. Furthermore, this clustering phenomenon
is seen to be robust; it occurs for a variety of models, a broad
selection of parameter values in those models and even for random and
stochastic perturbations of the models. Since there are necessarily an
integer number of clusters, clustering can lead to periodic-like
behavior with periods that are nearly integer divisors of the period
of the cell cycle.Related experiments have shown conclusively that
cell cycle clustering occurs in oscillating cultures.