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In Silico Biology 5, 0016 (2004); ©2004, Bioinformation Systems e.V.  



A life-like virtual cell membrane using discrete automata

Gordon Broderick, Melania Ru'aini, Eugene Chan and Michael J. Ellison*

Project CyberCell™, Institute for Biomolecular Design, 3-67, Medical Sciences Bldg, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7

* Corresponding author; Email: mike.ellison@ualberta.ca


Edited by E. Wingender; received September 17, 2004; revised and accepted November 17, 2004; published November 27, 2004


Abstract

A framework is presented that captures the discrete and probabilistic nature of molecular transport and reaction kinetics found in a living cell as well as formally representing the spatial distribution of these phenomena. This particle or agent-based approach is computationally robust and complements established methods. Namely it provides a higher level of spatial resolution than formulations based on ordinary differential equations (ODE) while offering significant advantages in computational efficiency over molecular dynamics (MD). Using this framework, a model cell membrane has been constructed with discrete particle agents that respond to local component interactions that resemble flocking or herding behavioural cues in animals. Results from simulation experiments are presented where this model cell exhibits many of the characteristic behaviours associated with its biological counterpart such as lateral diffusion, response to osmotic pressure gradients, membrane growth and cell division. Lateral diffusion rates and estimates for the membrane modulus of elasticity derived from these simple experiments fall well within a biologically relevant range of values. More importantly, these estimates were obtained by applying a simple qualitative tuning of the model membrane. Membrane growth was simulated by injecting precursor molecules into the proto-cell at different rates and produced a variety of morphologies ranging from a single large cell to a cluster of cells. The computational scalability of this methodology has been tested and results from benchmarking experiments indicate that real-time simulation of a complete bacterial cell will be possible within 10 years.

Keywords: mathematical model, agents, flocking, lipid bilayer, cell membrane, discrete automata, stochastic simulation, virtual cell