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17 results on '"Marée, Athanasius F.M."'

4. Systems Biology Approach Pinpoints Minimum Requirements for Auxin Distribution during Fruit Opening : Plant Systems Biology

Author

Li, Xin-Ran, Vroomans, Renske M.A., Fox, Samantha, Grieneisen, Verônica A., Østergaard, Lars, Marée, Athanasius F.M., and Institute of Biotechnology

Subjects
polar auxin transport, fungi, mathematical modeling, food and beverages, 1182 Biochemistry, cell and molecular biology, heterocyclic compounds, fruit development, auxin, 1183 Plant biology, microbiology, virology, systems biology of patterning
Abstract

The phytohormone auxin is implied in steering various developmental decisions during plant morphogenesis in a concentration-dependent manner. Auxin maxima have been shown to maintain meristematic activity, for example, of the root apical meristem, and position new sites of outgrowth, such as during lateral root initiation and phyllotaxis. More recently, it has been demonstrated that sites of auxin minima also provide positional information. In the developing Arabidopsis fruit, auxin minima are required for correct differentiation of the valve margin. It remains unclear, however, how this auxin minimum is generated and maintained. Here, we employ a systems biology approach to model auxin transport based on experimental observations. This allows us to determine the minimal requirements for its establishment. Our simulations reveal that two alternative processes—which we coin “flux-barrier” and “flux-passage”—are both able to generate an auxin minimum, but under different parameter settings. Both models are in principle able to yield similar auxin profiles but present qualitatively distinct patterns of auxin flux. The models were tested by tissue-specific inducible ablation, revealing that the auxin minimum in the fruit is most likely generated by a flux-passage process. Model predictions were further supported through 3D PIN localization imaging and implementing experimentally observed transporter localization. Through such an experimental–modeling cycle, we predict how the auxin minimum gradually matures during fruit development to ensure timely fruit opening and seed dispersal.

Published
2019

9. A Bistable Circuit Involving SCARECROW-RETINOBLASTOMA Integrates Cues to Inform Asymmetric Stem Cell Division

Author

Cruz-Ramírez, Alfredo, primary, Díaz-Triviño, Sara, additional, Blilou, Ikram, additional, Grieneisen, Verônica A., additional, Sozzani, Rosangela, additional, Zamioudis, Christos, additional, Miskolczi, Pál, additional, Nieuwland, Jeroen, additional, Benjamins, René, additional, Dhonukshe, Pankaj, additional, Caballero-Pérez, Juan, additional, Horvath, Beatrix, additional, Long, Yuchen, additional, Mähönen, Ari Pekka, additional, Zhang, Hongtao, additional, Xu, Jian, additional, Murray, James A.H., additional, Benfey, Philip N., additional, Bako, Laszlo, additional, Marée, Athanasius F.M., additional, and Scheres, Ben, additional

Published
2012
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16. Mathematical Model for Spatial Segregation of the Rho-Family GTPases Based on Inhibitory Crosstalk.

Author

Jilkine, Alexandra, Marée, Athanasius F.M., and Edelstein-Keshet, Leah

Subjects
*MATHEMATICAL models, *CYTOSKELETON, *NUCLEATION, *MYOSIN, *CELL motility, *ACTIN
Abstract

Cdc42, Rac, and Rho are small GTPases known to play a central role in signal transduction to the actin cytoskeleton. These proteins regulate cell motility, by affecting nucleation, uncapping, and depolymerization of actin filaments, and acto-myosin contractility. Studies of crosstalk and mutual feedbacks in these three proteins have led to a number of proposals for their interaction. At the same time, observations of the spatiotemporal dynamics of Rho-family proteins give evidence of spatial polarization and mutual exclusion between Cdc42/Rac and Rho. In this paper, we formulate a mathematical model to account for such observations, based on the known underlying biology of these proteins. We first investigate which of the crosstalk schemes proposed in the literature is consistent with observed dynamics, and then derive a simple model that can correctly describe these dynamics (assuming crosstalk is mediated via Rho GEFs). We show that cooperativity is an essential ingredient in the interactions of the proteins. The co-occurrence of a stable rest state with the possibility of fast spatial segregation can be related to bistability in a set of underlying ODEs in which the inactive forms of these proteins are fixed at a constant level. We show that the fast diffusion of the inactive forms is essential for stabilizing the transition fronts in the PDE formulation of the model, leading to robust spatial polarization, rather than traveling waves. [ABSTRACT FROM AUTHOR]

Published
2007
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17. Migration and Thermotaxis of Dictyostelium discoideumSlugs, a Model Study

Author

Marée, Athanasius F.M, Panfilov, Alexander V, and Hogeweg, Paulien

Abstract

Dictyostelium discoideumslugs show a pronounced thermotaxis. We have modelled the motion of the D. discoideumslug in the absence and in the presence of a thermal gradient. Our model is an extension of the hybrid cellular automata/partial differential equation model, as formulated by Savill and Hogeweg [J. theor. Biol., (1997) 184, 229–235]. The modelled slugs maintain their shape and crawl, with a velocity depending on slug size, as found in experiments. Moreover, they show thermotactic behaviour: independent of the initial orientation, after some transient process, the slugs start moving along the temperature gradient. The slug behaviour in our model is due to the collective behaviour of the amoebae. Individual amoebae can neither respond to a shallow temperature gradient, nor show differentiation in motion velocity. The behaviour is achieved by a modification of the cyclic AMP waves: differences in temperature alter the excitability of the cell, and thereby the shape of the cyclic AMP wave. Chemotaxis towards cyclic AMP causes the slug to turn. We show that the mechanism still functions at very low signal-to-noise ratios.

Published
1999
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