title: A computational model of nuclear self-organisation in syncytial embryos.
abstract: Syncytial embryos develop through cycles of nuclear division and rearrangement within a common cytoplasm. A paradigm example is Drosophila melanogaster in which nuclei form an ordered array in the embryo surface over cell cycles 10-13. This ordering process is assumed to be essential for subsequent cellularisation. Using quantitative tissue analysis, it has previously been shown that the regrowth of actin and microtubule networks after nuclear division generates reordering forces that counteract its disordering effect (Kanesaki et al., 2011). We present here an individual-based computer simulation modelling the nuclear dynamics. In contrast to similar modelling approaches e.g. epithelial monolayers or tumour spheroids, we focus not on the spatial dependence, but rather on the time-dependence of the interaction laws. We show that appropriate phenomenological inter-nuclear force laws reproduce the experimentally observed dynamics provided that the cytoskeletal network regrows sufficiently quickly after mitosis. Then repulsive forces provided by the actin system are necessary and sufficient to regain the observed level of order in the system, after the strong disruption resulting from cytoskeletal network disassembly and spindle formation. We also observe little mixing of nuclei through cell cycles. Our study highlights the importance of the dynamics of cytoskeletal forces during this critical phase of syncytial development and emphasises the need for real-time experimental data at high temporal resolution.
authors.affiliation: Bioquant, University of Heidelberg, Heidelberg, Germany; Institute for Theoretical Physics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Koke
authors.affiliation: Institute for Biochemistry and Molecular Cell Biology, University of Göttingen, Göttingen, Germany.
authors.forename: Takuma
authors.initials: T
authors.lastname: Kanesaki
authors.affiliation: Institute for Biochemistry and Molecular Cell Biology, University of Göttingen, Göttingen, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Grosshans
authors.affiliation: Bioquant, University of Heidelberg, Heidelberg, Germany; Institute for Theoretical Physics, University of Heidelberg, Heidelberg, Germany. Electronic address: ulrich.schwarz@bioquant.uni-heidelberg.de.
authors.forename: Ulrich S
authors.initials: US
authors.lastname: Schwarz
authors.affiliation: Bioquant, University of Heidelberg, Heidelberg, Germany; Department of Mathematics, University of Surrey, Guildford, UK. Electronic address: c.dunlop@surrey.ac.uk.
authors.forename: Carina M
authors.initials: CM
authors.lastname: Dunlop
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D002467:Cell Nucleus / Q000502:physiology*; D048750:Cell Nucleus Division / Q000502:physiology; D019295:Computational Biology; D003198:Computer Simulation; D004331:Drosophila melanogaster / Q000196:embryology; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000648:ultrastructure; D015726:Giant Cells / Q000502:physiology / Q000648:ultrastructure*; D008938:Mitosis / Q000502:physiology; D008941:Spindle Apparatus / Q000502:physiology
keywords: Cytoskeleton; Drosophila melanogaster; Individual-based model; Morphogenesis