Papers by Mikhail Tsyganov
FEMS Microbiology Letters, 1992
A method of pH distribution measurements in agar nutrient media containing expanding bacterial po... more A method of pH distribution measurements in agar nutrient media containing expanding bacterial populations is described. It is based on measuring pH microsamples taken at different points of the media. The sample volume was 10 td. A pH sensitive field effect transistor was used as a measuring electrode. Acidification was found to occur in glucose media, while aikalization occurred in the media containing peptone.
Doklady Akademii nauk SSSR, 1991
Doklady Biochemistry and Biophysics, 2004
Proceedings of the Royal Society B: Biological Sciences, 1993
The occurrence of spatially ordered structures plays an important role in biology (examples: morp... more The occurrence of spatially ordered structures plays an important role in biology (examples: morphogenesis, ecosystems, dynamics of populations, etc.). Turing proposed a reaction-diffusion process that is the basis for most theoretical studies of stationary biological pattern formation. Now, when Turing structures are obtained in experiments (40 years after Turing's publication), it is interesting to discover whether Turing structures are the only mechanism used by nature in biological pattern formation. In microbial growth, we have found experimental evidence of an alternative to the Turing model that is based on waves displayed in excitable media. In studies of Escherichia coli populations, we observed that interacting taxis waves create motionless patterns. Taxis waves consuming two different substrates (serine and aspartic acid) were involved. Taxis waves consuming serine stop when they collide. However, those supported by consumption of aspartic were initiated at the collision line. Colliding and annihilating in turn, the waves give rise to stationary pattern formation, and wave theory provides an alternative to the classical Turing mechanism.
FEMS Microbiology Letters, 1993
FEMS Microbiology Letters, 1991
Many motile bacteria (for instance, Escherichia coli) inoculated at some point in a semisolid nut... more Many motile bacteria (for instance, Escherichia coli) inoculated at some point in a semisolid nutrient medium can form population waves: bands or rings. The formation of these motile structures is due to chemotaxis. The population waves when they are drawn together can form two types of non-motile structures. Firstly, the population waves can collide. Secondly, in certain conditions, the waves can slow down and stop without coming into contact directly with each other. In this way demarcation zones are formed. The mechanism of the occurrence of the demarcation zones has been unknown. In this paper we show that formation of these zones is due to lack of nutrients (which at the same time act as attractants) within the narrow gap between individual bacterial populations.
Biophysics, 2009
A study was made of the time of formation and the rate of propagation of bacterial population wav... more A study was made of the time of formation and the rate of propagation of bacterial population waves as dependent on substrate concentration. Experimentally and theoretically it is shown that the time of bacterial wave formation grows with increasing concentration of the nutritive component. At the same time, the wave propagation rate drops at relatively high concentrations of the nutritive
Radiophysics and Quantum Electronics
ABSTRACT
Physical Review E, 2017
We study waves with exponentially decaying oscillatory tails in a reaction-diffusion system with ... more We study waves with exponentially decaying oscillatory tails in a reaction-diffusion system with linear cross diffusion. To be specific, we consider a piecewise linear approximation of the FitzHugh-Nagumo model, also known as the Bonhoeffer-van der Pol model. We focus on two types of traveling waves, namely solitary pulses that correspond to a homoclinic solution, and sequences of pulses or wave trains, i.e., a periodic solution. The effect of cross diffusion on wave profiles and speed of propagation is analyzed. We find the intriguing result that both pulses and wave trains occur in the bistable cross-diffusive FitzHugh-Nagumo system, whereas only fronts exist in the standard bistable system without cross diffusion.
Research into living cells and their communities can be extended to more general problems, e.g., ... more Research into living cells and their communities can be extended to more general problems, e.g., what is the algorithm of data processing in living systems, or what is the difference between living systems and computers. It has been shown that a computerised system simulating cell behaviour, i.e., multiplication, motility, memory, and taxis, can be better at image processing than video-based
Soviet Physics Uspekhi, 1991
Physics Uspekhi, Nov 1, 1998
As a result of cyclic interactions with their environment, microparticles are often drawn into a ... more As a result of cyclic interactions with their environment, microparticles are often drawn into a directed, stochastically determined motion and subsequently arrange themselves into dynamical structures. In the present review, the possibility of a directed motion of microparticles in the presence of weak, asymmetric, periodic governing fields is analyzed. The minimum energy requirement for changing from random walk to directed motion is estimated. Applications to regulatory processes in biosystems, such as the virus–bacterium interaction and intercellular movement of chemotaxis bacteria, vesicles, enzymes, and ions, are discussed and certain high-technology uses of these effects considered.
Herald of the Russian Academy of Sciences, 2011
ABSTRACT
Cell Systems, 2016
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Physical Review E Statistical Nonlinear and Soft Matter Physics, Oct 1, 2004
In this paper, we use numerical simulations to demonstrate a half-soliton interaction of waves in... more In this paper, we use numerical simulations to demonstrate a half-soliton interaction of waves in a mathematical model of a "prey-predator" system with taxis when of two colliding waves, one annihilates and the other continues to propagate. We show that this effect depends on the "ages" or, equivalently, "widths" of the colliding waves. In two spatial dimensions we demonstrate that the type of interaction, i.e., annihilation, quasisoliton, or half-soliton, depends not only on curvature and width of the colliding waves, but also on the angle of the collision. When conditions of collision are varying in such a way that only a part of a wave survives the collision, then "taxitons," compact pieces of solitary waves, may form, which can exist for a significant time.
Biofizika
It has been shown in our previous studies that, during collision, bacterial population waves can ... more It has been shown in our previous studies that, during collision, bacterial population waves can penetrate each other or stop. In the present study, the mechanism of the two regimes of interaction is considered in detail. Based on the experimental and theoretical research, it has been shown that this interaction is a vivid example to confirm one of the characteristic properties of waves in cross-diffusion systems.
Doklady Akademii nauk / [Rossiĭskaia akademii nauk]
Biofizika
By way of example of interaction of T4 bacteriophage with E. coli bacterium the scenario of enhan... more By way of example of interaction of T4 bacteriophage with E. coli bacterium the scenario of enhancement of sorption of phages on bacteria through the remote mechanism of their cyclic interaction has been considered. An enlargement of the typical phage size, when its fibrillae are opened, underlies this mechanism. Modification of the structure of phages also occurs through the medium by release of products of bacterial metabolism into it. Allied questions related to investigation of physicochemical and biological processes, which require to take into account "fluffing" of microparticles. The medium-induced change of volume of microparticles leads to spatial cooperative effects with non-linear dynamics. Such phenomena are possible in all diffusional processes in biology, chemistry and physics.
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Papers by Mikhail Tsyganov