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Stochastic Modeling of External Electric Field Effect on Escherichia Coli Min Protein Dynamics
Charin MODCHANG,Wannapong TRIAMPO,Paisan KANTHANG,Udorn JUNTHORN,Somrit UNAI,Waipot NGAMSAAD,Narin NUTTAVUT,Darapond TRIAMPO,Yongwirnon LENBURY 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
Cel division in Escherichia coli and other rod-shaped bacteria depends on the precise place- ment of a division septum at the cel center. The MinCDE system consisting of thre proteins, MinC, MinD, and MinE, controls acurate cel division at the center of the cel through pole-to- pole oscilation. With simplifying asumptions and relying on a deterministic model, we present a one-dimensional stochastic model that describes the effects of an external electric field on the MinCDE system. Computer simulations were performed to investigate the response of the oscila- tory dynamics to various strengths of the electric field and to the total number of Min proteins. A sufficient electric field strength was capable of interfering with MinCDE dynamics with posible changes to the cel division proces. Interestingly, effects of an electric field were found not to depend on the total number of Min proteins. The noise involved shifted the corect trend of Min proteins behavior. However, as a consequence of the robustnes of the dynamics, the oscilatory patern of the proteins stil existed even though the number of Min proteins was relatively low. When considering the corelations betwen the local and the global minimum (maximum) of MinD (MinE), the results suggest that using a high enough Min protein concentration wil reduce the localminimum(maximum)effect, which is related to the probability of polar division in each single oscilator cycle. Although this model is simple and neglects some complex mechanisms concerning protein oscilation in corelation with celdivision, it has ben demonstratedto be goodenough for positioning of the dividing site. Nevertheles, more experimental and theoretical studies are neded to provide a more realistic (but of course more complicated) model of bacterial cel division.
Wannapong Triampo,Ankana Boondirek,Charin Modchang,I-Ming Tang,Narin Nuttawut,Paisan Kanthang,Suchitra Sanguansin,Waipot Ngamsaad,Yongwimol Lenbury 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.4
One of the most important steps in the developmental process of the bacteria cells at the cellular level is the determination of the middle of the cell and the proper placement of the septum, these being essential to the division of the cell. In E. coli, this step depends on the proteins MinC, MinD, and MinE. Exposure to a constant electric field may cause the bacteria’s cell-division mechanism to change, resulting in an abnormal cytokinesis. To see the effects of an external field e.g., an electric or magnetic field on this process, we have solved a set of deterministic reaction diffusion equations, which incorporate the influence of an electric field. We have found some changes in the dynamics of the oscillations of the min proteins from pole to pole. The numerical results show some interesting effects, which are qualitatively in good agreement with some experimental results.
Investigating flow patterns in a channel with complex obstacles using the lattice Boltzmann method
Jiraporn Yojina,Waipot Ngamsaad,Narin Nuttavut,Darapond Triampo,Yongwimon Lenbury,Paisan Kanthang,Somchai Sriyab,Wannapong Triampo 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.10
In this work, mesoscopic modeling via a computational lattice Boltzmann method (LBM) is used to investigate the flow pattern phenomena and the physical properties of the flow field around one and two square obstacles inside a two-dimensional channel with a fixed blockage ratio, β =1 4, centered inside a 2D channel, for a range of Reynolds numbers (Re) from 1 to 300. The simulation results show that flow patterns can initially exhibit laminar flow at low Re and then make a transition to periodic, unsteady, and, finally, turbulent flow as the Re get higher. Streamlines and velocity profiles and a vortex shedding pattern are observed. The Strouhal numbers are calculated to characterize the shedding frequency and flow dynamics. The effect of the layouts or configurations of the obstacles are also investigated,and the possible connection between the mixing process and the appropriate design of a chemical mixing system is discussed.
Wannapong Triampo,Charin Modchang,I-Ming Tang,Narin Nuttawut,Paisan Kanthang,Waipot Ngamsaad,Yongwimol Lenbury 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.4
Determining the middle of the bacteria cell and the proper placement of the septum is essential to the division of the bacterial cell. In E. coli, this process depends on the proteins MinC, MinD, and MinE. Here, the lattice Boltzmann method (LBM) is used to study the dynamics of the oscillations of the min proteins from pole to pole. This determines the midcell division plane at the cellular level. The LBM is applied to the set of eterministic reaction diffusion equations proposed by Howard et al. to describe the dynamics of the Min proteins. The LBM results are in good agreement with those of Howard et al. and agree qualitatively with the experimental results. Our good results indicate that the LBM can be an alternative computational tool for simulating problems dealing with complex biological systems that can be described by using the reaction-diffusion equations