Timon Idema, Julien O. Dubuis, M. Lisa Manning, Philip C. Nelson, Andrea J. Liu
Mitosis in the early syncytial Drosophila embryo is highly correlated in space and time, as manifested in mitotic wavefronts that propagate across the embryo. In this paper we investigate the idea that the embryo can be considered a mechanically-excitable medium, and that mitotic wavefronts can be understood as nonlinear wavefronts that propagate through this medium. We study the wavefronts via both image analysis of confocal microscopy videos and theoretical models. We find that the mitotic wavefront can be resolved into two distinct wavefronts in each cycle, corresponding to metaphase and anaphase, respectively. The two wavefronts have the same speed and are separated by a time interval that is independent of cycle, supporting the idea that they are two different markers for the same process. To understand the wavefronts theoretically we analyze wavefront propagation in excitable media. We study two classes of models, one with biochemical signaling and one with mechanical signaling. We find that the dependence of wavefront speed on cycle number is most naturally explained by mechanical signaling, and that the entire process suggests a scenario in which biochemical and mechanical signaling are coupled.
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http://arxiv.org/abs/1304.4025
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