Dissipative structures in a two-cell system: Numerical and experimental approaches

Abstract

It has been shown that the coupling between the photoreduction of the oxidized form of dicliloroindophenol (an artificial electron acceptor) by thylakoids and the incident light intensity can lead to the appearance of multiple steady states when the system is operated under open conditions. In the present work, a numerical study and experimental evidence are presented on the occurrence of dissipative structures in an arrangement of two continuously stirred tank reactors with mutual mass exchange of dichloroindophenol through an inert membrane. The stable spatial structures are generated by the creation of transient internal and external asymmetries. A nontrivial hysteresis effect between symmetric and asymmetric stable steady states has been observed. (4)(5)(6). Scriven and co-workers (7-9) and Martinez and Baer (10, 11) have extended and generalized the work of Turing and thus far have analyzed the onset to instability in arbitrary networks of compartments. The coexistence of multiple stationary solutions with properties similar to those described by Martinez and Scriven has been found also in distributed reaction-diffusion systems (12-16).Few models are concerned with enzyme kinetics that of- MATERIALS AND METHODSPreparation of Thylakoids. Thylakoids were prepared from fresh lettuce (Latuca sativa, var. romaine) in a sorbitol buffer (pH 7.6) by the procedure of Epel and Neumann (23).Immobilization Procedure. The immobilization process, based on a method using a calcium alginate gel (24), was modified to obtain films rather than beads. The thylakoid suspension was mixed with an equal volume of a 4% sodium alginate solution in sorbitol buffer (330 mM, pH 7.6 Under our experimental conditions, the DCIPox exhibits an absorTtion peak centered at 600 nm (E600 = 17.9 mM--cm-'). No detectable absorbance of the reduced form (DCIPred) is measured for wavelengths between 500 and 800 nm. All measurements were carried out in a modified extraction buffer with no phosphate, 50 mM CaCl2, and 5 mM MgCl2-Abbreviations: DCIP, dichloroindophenol; CSTR, continuously stirred tank reactor; bp, bifurcation points; lp, limit points. 551The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Spatial patterns in a photobiochemical system

“…According to the reaction-diffusion theory, the interaction of diffusion transport and nonlinear chemical kinetics can lead to instabilities of a concentration field with the result that initially homogeneous domains develop regional nonuniformities (1,2). The autocatalytic nature of a photobiochemical reaction resulting from the coupling of two intrinsically linear processes-i.e., the reduction of DCIP by thylakoids and the light absorption by the same electron acceptor DCIP-has been demonstrated in a spatially compartmentalized system (25,30). In those studies, the existence of multiple steady states in a single open reactor and of stable asymmetric steady states in coupled open reactors with mutual diffusion through an inert membrane was shown by experimental and numerical methods.…”