An Experimental Design Method Leading to Chemical Turing Patterns

Adding a Turing Pattern Reaction Two chemical-reaction systems can form sustained stationary patterns (Turing patterns) in solution as the result of the movement of a diffusible species and the formation of negative feedback loops—the chlorite-iodide–malonic acid reaction and the ferrocyanide-iodate-sulfite reaction. Horváth et al. (p. 772) set out to find other examples based on three criteria—that the reaction can develop spatial bistability, that independent control of the negative feedback reaction can be achieved, and the activating and inhibiting processes can be decoupled by slowing down the diffusing species with a complexing agent. The thiourea-iodate-sulfite (TuIS) reaction could be developed into a system that produced different stationary patterns, including stripes and hexagonal arrays of spots. Thus, such Turing pattern–generating reactions are not necessarily uncommon. Three design criteria were used to create sustained stationary patterns in the thiourea-iodate-sulfite reaction system. Chemical reaction-diffusion patterns often serve as prototypes for pattern formation in living systems, but only two isothermal single-phase reaction systems have produced sustained stationary reaction-diffusion patterns so far. We designed an experimental method to search for additional systems on the basis of three steps: (i) generate spatial bistability by operating autoactivated reactions in open spatial reactors; (ii) use an independent negative-feedback species to produce spatiotemporal oscillations; and (iii) induce a space-scale separation of the activatory and inhibitory processes with a low-mobility complexing agent. We successfully applied this method to a hydrogen-ion autoactivated reaction, the thiourea-iodate-sulfite (TuIS) reaction, and noticeably produced stationary hexagonal arrays of spots and parallel stripes of pH patterns attributed to a Turing bifurcation. This method could be extended to biochemical reactions.

[1]  J. Boissonade,et al.  Experimental Studies and Quantitative Modeling of Turing Patterns in the (Chlorine Dioxide, Iodine, Malonic Acid) Reaction , 1999 .

[2]  P. De Kepper,et al.  Sustained spatiotemporal patterns in the bromate-sulfite reaction. , 2007, The journal of physical chemistry. A.

[3]  William J. Bruno,et al.  Pattern formation in an N+Q component reaction-diffusion system. , 1992, Chaos.

[4]  I. Szalai,et al.  Spatial bistability, oscillations and excitability in the Landolt reaction , 2006 .

[5]  Ehud Meron,et al.  Complex patterns in reaction-diffusion systems: A tale of two front instabilities. , 1994, Chaos.

[6]  Irving R Epstein,et al.  Complex patterns in reactive microemulsions: self-organized nanostructures? , 2005, Chaos.

[7]  Q Ouyang,et al.  Pattern Formation by Interacting Chemical Fronts , 1993, Science.

[8]  R. M. Noyes,et al.  Oscillations in chemical systems. II. Thorough analysis of temporal oscillation in the bromate-cerium-malonic acid system , 1972 .

[9]  M. Kuperman,et al.  Spatial bistability and waves in a reaction with acid autocatalysis. , 2002, Faraday discussions.

[10]  S. Ponce Dawson,et al.  Turing Patterns Inside Cells , 2007, PloS one.

[11]  Dulos,et al.  Experimental evidence of a sustained standing Turing-type nonequilibrium chemical pattern. , 1990, Physical review letters.

[12]  J. Boissonade,et al.  Transitions from bistability to limit cycle oscillations. Theoretical analysis and experimental evidence in an open chemical system , 1980 .

[13]  A. Wit,et al.  SPATIAL PATTERNS AND SPATIOTEMPORAL DYNAMICS IN CHEMICAL SYSTEMS , 2007 .

[14]  A. Turing The chemical basis of morphogenesis , 1952, Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences.

[15]  István Szalai,et al.  Turing Patterns, Spatial Bistability, and Front Instabilities in a Reaction−Diffusion System , 2004 .

[16]  I. Epstein,et al.  A chemical approach to designing Turing patterns in reaction-diffusion systems. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[17]  P. De Kepper,et al.  Pattern formation in the ferrocyanide-iodate-sulfite reaction: the control of space scale separation. , 2008, Chaos.

[18]  I. Epstein,et al.  An Introduction to Nonlinear Chemical Dynamics , 1998 .

[19]  J. Boissonade,et al.  Theoretical and experimental studies of spatial bistability in the chlorine-dioxide-iodide reaction , 2000 .