title: A set of simple cell processes is sufficient to model spiral cleavage.
abstract: During cleavage, different cellular processes cause the zygote to become partitioned into a set of cells with a specific spatial arrangement. These processes include the orientation of cell division according to: an animal-vegetal gradient; the main axis (Hertwig's rule) of the cell; and the contact areas between cells or the perpendicularity between consecutive cell divisions (Sachs' rule). Cell adhesion and cortical rotation have also been proposed to be involved in spiral cleavage. We use a computational model of cell and tissue biomechanics to account for the different existing hypotheses about how the specific spatial arrangement of cells in spiral cleavage arises during development. Cell polarization by an animal-vegetal gradient, a bias to perpendicularity between consecutive cell divisions (Sachs' rule), cortical rotation and cell adhesion, when combined, reproduce the spiral cleavage, whereas other combinations of processes cannot. Specifically, cortical rotation is necessary at the 8-cell stage to direct all micromeres in the same direction. By varying the relative strength of these processes, we reproduce the spatial arrangement of cells in the blastulae of seven different invertebrate species.
authors.affiliation: Genomics, Bioinformatics and Evolution, Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain.|Evo-devo Helsinki community, Centre of Excellence in Computational and Experimental Developmental Biology, Institute of Biotechnology, University of Helsinki, PO Box 56, Helsinki FIN-00014, Finland.
authors.forename: Miguel
authors.initials: M
authors.lastname: Brun-Usan
authors.affiliation: Genomics, Bioinformatics and Evolution, Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain.|Evo-devo Helsinki community, Centre of Excellence in Computational and Experimental Developmental Biology, Institute of Biotechnology, University of Helsinki, PO Box 56, Helsinki FIN-00014, Finland.
authors.forename: Miquel
authors.initials: M
authors.lastname: Marín-Riera
authors.affiliation: Departamento de Biología Molecular and Centro de Biología Molecular, 'Severo Ochoa' (CSIC, Universidad Autónoma de Madrid), Madrid, Spain.|Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Grande
authors.affiliation: Departamento de Biología Molecular and Centro de Biología Molecular, 'Severo Ochoa' (CSIC, Universidad Autónoma de Madrid), Madrid, Spain.|Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Truchado-Garcia
authors.affiliation: Genomics, Bioinformatics and Evolution, Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain isalazar@mappi.helsinki.fi.|Evo-devo Helsinki community, Centre of Excellence in Computational and Experimental Developmental Biology, Institute of Biotechnology, University of Helsinki, PO Box 56, Helsinki FIN-00014, Finland.
authors.forename: Isaac
authors.initials: I
authors.lastname: Salazar-Ciudad
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D002450:Cell Communication / Q000502:physiology; D002455:Cell Division / Q000502:physiology*; D016764:Cell Polarity; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D004625:Embryo, Nonmammalian; D049851:Gastropoda / Q000196:embryology; D007448:Invertebrates / Q000196:embryology*; D008954:Models, Biological; D008974:Mollusca / Q000196:embryology
keywords: Developmental morphospace; Developmental rules; Spiral cleavage