Karsten Kruse

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BACKGROUND Asymmetric division of the C. elegans zygote is due to the posterior-directed movement of the mitotic spindle during metaphase and anaphase. During this movement along the anterior-posterior axis, the spindle oscillates transversely. These motions are thought to be driven by a force-generating complex-possibly containing the motor protein(More)
In the bacterium Escherichia coli, the Min proteins oscillate between the cell poles to select the cell center as division site. This dynamic pattern has been proposed to arise by self-organization of these proteins, and several models have suggested a reaction-diffusion type mechanism. Here, we found that the Min proteins spontaneously formed planar(More)
Self-organization of proteins in space and time is of crucial importance for the functioning of cellular processes. Often, this organization takes place in the presence of strong random fluctuations due to the small number of molecules involved. We report on stochastic switching of the Min-protein distributions between the two cell halves in short(More)
We present a physical analysis of the dynamics and mechanics of contractile actin rings. In particular, we analyze the dynamics of ring contraction during cytokinesis in the Caenorhabditis elegans embryo. We present a general analysis of force balances and material exchange and estimate the relevant parameter values. We show that on a microscopic level(More)
In the bacterium Escherichia coli, selection of the division site involves pole-to-pole oscillations of the proteins MinD and MinE. Different oscillation mechanisms based on cooperative effects between Min-proteins and on the exchange of Min-proteins between the cytoplasm and the cytoplasmic membrane have been proposed. The parameters characterizing the(More)
During division it is of primary importance for a cell to correctly determine the site of cleavage. The bacterium Escherichia coli divides in the center, producing two daughter cells of equal size. Selection of the center as the correct division site is in part achieved by the Min-proteins. They oscillate between the two cell poles and thereby prevent(More)
We develop a general theory for active viscoelastic materials made of polar filaments. This theory is motivated by the dynamics of the cytoskeleton. The continuous consumption of a fuel leads to a non equilibrium state characterized by the generation of flows and stresses. Our theory can be applied to experiments in which cytoskeletal patterns are set in(More)
During unequal cell division the mitotic spindle is positioned away from the center of the cell before cell cleavage. In many biological systems this repositioning is accompanied by oscillatory movements of the spindle. We present a theoretical description for mitotic spindle oscillations. We show that the cooperative attachment and detachment of cortical(More)
We introduce a phenomenological model to study the properties of bundles of polar filaments which interact via active elements. The stability of the homogeneous state, the attractors of the dynamics in the unstable regime, and the tensile stress generated in the bundle are discussed. We find that the interaction of parallel filaments can induce unstable(More)