Oscillating stochastic kinetochore model.

<p>(A) Model schematic showing the orientation of the two sisters and the respective forces (arrows). Sister kinetochores are connected by a linear spring (producing force <i>F</i>_spring, green) and are attached to a K-fibre in either a polymerising (<i>F</i>₊, blue) or depolymerising (<i>F</i>₋, red) state. The direction of polar ejection forces (PEF, <i>F</i>_PEF) is indicated by orange arrows. Sisters may be off-axis (twist angle <i>θ</i>); the spring force (and natural length) are then projected onto the metaphase plate normal. A directional switch is shown with the trailing sister (left) switching first (K-fibre catastrophe), followed by the originally leading sister (K-fibre rescue). See main text for details. (B) Simulated trajectory from model <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004607#pcbi.1004607.e020" target="_blank">Eq (5)</a> showing the (normal) distance from the metaphase plate of the two sisters. Parameters used were <i>p</i>_<i>c</i> = 0.94, <i>p</i>_<i>ic</i> = 0.61, <i>v</i>₊ = 0.05 μm s⁻¹, <i>v</i>₋ = −0.03 μm s⁻¹, <i>L</i> = 0.8 μm, <i>κ</i> = 0.05 s⁻¹, <i>α</i> = 0.03 s⁻¹ and <i>τ</i> = 1000 s² μm⁻², (Δ<i>t</i> = 2<i>s</i>). See <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004607#sec002" target="_blank">Methods</a> for parameter explanation. (C) Example sister pair trajectory, from kinetochore tracking of live-cell imaging data, showing the (normal) distance from the metaphase plate of the two sisters. (D) The hidden Markov chain transition network for K-fibres switching between polymerising (+) and depolymerising (–) states used in the MCMC algorithm model. <i>p</i>_<i>c</i>, <i>p</i>_<i>ic</i> are the probabilities of remaining coherent and incoherent, respectively, and <i>q</i>_<i>c</i> = 1−<i>p</i>_<i>c</i> and <i>q</i>_<i>ic</i> = 1−<i>p</i>_<i>ic</i>. (E) Time-lapse sequence of kinetochores. Kinetochores are marked by eGFP-CENP-A. Yellow bordered panel at right shows single kinetochore pair indicated by yellow box in first image.