A5013648070- Liquid Crystal Research Advancements
- Plant Molecular Biology Research
- Material Dynamics and Properties
- Plant Reproductive Biology
- Microtubule and mitosis dynamics
- Polysaccharides and Plant Cell Walls
- Cellular Mechanics and Interactions
- Theoretical and Computational Physics
- Polysaccharides Composition and Applications
- Advanced Cellulose Research Studies
- Nonlinear Dynamics and Pattern Formation
- Bacterial Genetics and Biotechnology
- Biofuel production and bioconversion
- Bacteriophages and microbial interactions
- Photosynthetic Processes and Mechanisms
- Surfactants and Colloidal Systems
- Plant nutrient uptake and metabolism
- Advanced Materials and Mechanics
- Phase Equilibria and Thermodynamics
- Gene Regulatory Network Analysis
- Diffusion and Search Dynamics
- Advanced biosensing and bioanalysis techniques
- Microbial Metabolic Engineering and Bioproduction
- Advanced Thermodynamics and Statistical Mechanics
- Micro and Nano Robotics
Institute for Atomic and Molecular Physics
2016-2025
Utrecht University
1982-2025
Wageningen University & Research
2009-2021
GGD Amsterdam
2014-2019
Amsterdam University of Applied Sciences
2019
Vitenparken
2019
University of Vienna
2016
Graduate School Experimental Plant Sciences
2004-2015
University of Edinburgh
2015
State Key Laboratory of Cell Biology
2003-2014
We present the results of Monte Carlo simulations on a system hard ellipsoids revolution with length-to-breadth ratios a/b = 3, 2·75, 2, 1·25 and b/a 1·25. identify four distinct phases, viz. isotropic fluid, nematic ordered solid plastic solid. The coexistence points all first order phase transitions are located by performing absolute free energy computations for coexisting phases. find phases only ⩾ 2·75 ⩽ 1>/2·75. A is observed 0·8. It found that diagram surprisingly symmetric under...
Despite recent progress in visualization experiments, the mechanism underlying chromosome segregation bacteria still remains elusive. Here we address a basic physical issue associated with bacterial segregation, namely spatial organization of highly confined, self-avoiding polymers (of nontrivial topology) rod-shaped cell-like geometry. Through computer simulations, present evidence that, under strong confinement conditions, topologically distinct domains polymer complex effectively repel...
Environmental and hormonal signals cause reorganization of microtubule arrays in higher plants, but the mechanisms driving these transitions have remained elusive. The organization is required to direct morphogenesis. We discovered that severing by protein katanin plays a crucial unexpected role reorientation cortical arrays, as triggered blue light. Imaging genetic experiments revealed phototropin photoreceptors stimulate katanin-mediated specifically at intersections, leading generation...
The phase diagram of a system hard ellipsoids revolution was investigated by means constant-pressure Monte Carlo simulation. Prolate as well oblate were considered. results for the isotherms at several different values length-to-breadth ratio are presented. Four phases identified and tentative picture is given.
Abstract We present the results of Monte Carlo simulations on a system hard ellipsoids revolution with length-to-breadth ratios a/b = 3, 2.75, 2, 1.25 and b/a 1.25. identify four distinct phases, viz. isotropic fluid, nematic ordered solid plastic solid. The coexistence points all first order phase transitions are located by performing absolute free energy computations for coexisting phases. find phases only ≥ 2.75 ≤ 1/2.75. A is observed 0.8. It found that diagram surprisingly symmetric...
Actin has well established functions in cellular morphogenesis. However, it is not understood how the various actin assemblies a cell are kept dynamic equilibrium, particular when cells have to respond acute signals. Here, we characterize rapid and transient reset response increased intracellular calcium levels. Within seconds of influx, formin INF2 stimulates filament polymerization at endoplasmic reticulum (ER), while cortical disassembled. The reaction then reversed within few minutes....
Abstract When a liquid crystal forming particles are confined to spatial volume with dimensions comparable that of their own size, they face complex trade-off between global tendency align and the local constraints imposed by boundary conditions. This interplay may lead non-trivial orientational patterns strongly depend on geometry confining volume. novel regime crystalline behavior can be probed colloidal macro-aggregates biomolecules. Here we study director fields filamentous fd -viruses...
The cortical microtubule arrays of higher plants are organized without centrosomes and feature treadmilling polymers that dynamic at both ends. control polymer end stability is fundamental for the assembly organization cytoskeletal arrays, yet relatively little understood about how minus ends controlled in acentrosomal no factors have been identified act plants. Here, we identify Arabidopsis thaliana SPIRAL2 (SPR2) as a protein tracks protects them against subunit loss. SPR2 function...
The occurrence of smectic order in a system perfectly aligned hard cylinders is studied with use bifurcation analysis the free-energy functional second virial coefficient approximation. This approximation shown to yield second-order transition mean-field type towards phase. influence higher-order terms density expansion considered by calculating shift location point associated transition, when third- and fourth-order one-particle are taken into account.
The isotropic-symmetry-breaking bifurcations occurring in a class of liquid-crystal models describing particles with the symmetry rectangular slabs are studied. model free-energy functional employed is appropriate to both mean-field treatment anisotropic dispersion forces and Onsager approximation for hard anisometric particles. bifurcating solutions stationary-phase equations classified terms eigenvalues effective pair interaction. Explicit conditions derived systems exhibiting crossover...
The y-expansion as introduced by Barboy and Gelbart is applied to a system of hard ellipsoids-of-revolution. expansion truncated after the third order term yielding an approximate theory requiring second- third-virial coefficients inputs. As virial coefficient not known analytically, numerical results are obtained for this quantity. equation state from free-energy variational calculation. compared with Monte Carlo data taken preceding paper in series. application scaled particle same...
Cells use actin filaments to define and maintain their shape exert forces on the surrounding tissue. Accessory proteins like crosslinkers motors organize these into functional structures. However, physical effects also influence filament organization: steric interactions impose packing constraints at high density spatially confine within cell boundaries. Here we investigate combined of spatial confinement by growing dense networks in cell-sized microchambers with nonadhesive walls. We show...
Oriented cell divisions are significant in plant morphogenesis because cells embedded walls and cannot relocate. Cell follow various regular orientations, but the underlying mechanisms have not been clarified. We propose that cell-shape-dependent self-organization of cortical microtubule arrays is able to provide a mechanism for determining planes early tissue-generating may form basis robust control division orientation embryo. To show this, we simulate microtubules on actual surface...
We theoretically and experimentally study nematic liquid crystal equilibria within shallow rectangular wells. model the wells a two-dimensional Oseen-Frank framework, with strong tangent anchoring, obtain explicit analytical expressions for director fields energies of 'diagonal' 'rotated' solutions reported in literature. These separate leading-order defect from bulk distortion energy both families solutions. The continuum is complemented by microscopic mean-field approach. numerically...
Abstract We consider a fluid of hard boomerangs, each composed two spherocylinders joined at their ends an angle ψ. The resulting particle is nonconvex and biaxial. occurence nematic order in such system has been investigated using Straley's theory, which simplificaton Onsager's second-virial treatment long rods, by bifurcation analysis. excluded volume boomerangs approximated the sum volumes pairs constituent spherocylinders, angle-dependent coefficient replaced low-order interpolating...
Summary Exocytosis and endocytosis are pivotal in many biological processes, but remain difficult to quantify. Here we combine a new algorithm for estimating vesicle size with detailed morphological analysis of tip‐growing cells, which exocytosis is highly localized therefore more readily quantified. Cell preservation was rendered as life‐like possible by rapid freezing. This allowed us produce the first estimates rates root hairs pollen tubes model plant Arabidopsis. To quantify during cell...
The cortical array is a structure consisting of highly aligned microtubules which plays crucial role in the characteristic uniaxial expansion all growing plant cells. Recent experiments have shown polymerization-driven collisions between membrane-bound microtubules, suggesting possible mechanism for their alignment. We present both coarse-grained theoretical model and stochastic particle-based simulations this mechanism, compare results from these complementary approaches. Our indicate that...
The organization of the eukaryote nucleus into functional compartments arises by self-organization both through specific protein-protein and protein-DNA interactions non-specific that lead to entropic effects, such as e.g.depletion attraction.While many have so far been demonstrated, contributions are still unclear.We used coarse-grained molecular dynamics simulations previously published models for Arabidopsis thaliana chromatin show can explain in vivo localization nucleoli...
The highly aligned cortical microtubule array of interphase plant cells is a key regulator anisotropic cell expansion. Recent computational and analytical work has shown that the non-equilibrium self-organization this structure can be understood on basis experimentally observed collisional interactions between dynamic microtubules attached to plasma membrane. Most these approaches assumed new are homogeneously isotropically nucleated surface. Experimental evidence, however, shows nucleation...