Quantum probability in decision making from quantum information representation of neuronal states

The recent wave of interest to modeling the process of decision making with the aid of the quantum formalism gives rise to the following question: ‘How can neurons generate quantum-like statistical data?’ (There is a plenty of such data in cognitive psychology and social science.) Our model is based on quantum-like representation of uncertainty in generation of action potentials. This uncertainty is a consequence of complexity of electrochemical processes in the brain; in particular, uncertainty of triggering an action potential by the membrane potential. Quantum information state spaces can be considered as extensions of classical information spaces corresponding to neural codes; e.g., 0/1, quiescent/firing neural code. The key point is that processing of information by the brain involves superpositions of such states. Another key point is that a neuronal group performing some psychological function F is an open quantum system. It interacts with the surrounding electrochemical environment. The process of decision making is described as decoherence in the basis of eigenstates of F. A decision state is a steady state. This is a linear representation of complex nonlinear dynamics of electrochemical states. Linearity guarantees exponentially fast convergence to the decision state

Mild reductions in cytosolic NADP-dependent isocitrate dehydrogenase activity result in lower amino acid contents and pigmentation without impacting growth

Transgenic tomato (Solanum lycopersicum) plants were generated targeting the cytosolic NADP-dependent isocitrate dehydrogenase gene (SlICDH1) via the RNA interference approach. The resultant transformants displayed a relatively mild reduction in the expression and activity of the target enzyme in the leaves. However, biochemical analyses revealed that the transgenic lines displayed a considerable shift in metabolism, being characterized by decreases in the levels of the TCA cycle intermediates, total amino acids, photosynthetic pigments, starch and NAD(P)H. The plants showed little change in photosynthesis with the exception of a minor decrease in maximum photosynthetic efficiency (Fv/Fm), and a small decrease in growth compared to the wild type. These results reveal that even small changes in cytosolic NADP-dependent isocitrate dehydrogenase activity lead to noticeable alterations in the activities of enzymes involved in primary nitrate assimilation and in the synthesis of 2-oxoglutarate derived amino acids. These data are discussed within the context of current models for the role of the various isoforms of isocitrate dehydrogenase within plant amino acid metabolism

NO Dioxygenase Activity in Hemoglobins Is Ubiquitous In Vitro, but Limited by Reduction In Vivo

Genomics has produced hundreds of new hemoglobin sequences with examples in nearly every living organism. Structural and biochemical characterizations of many recombinant proteins reveal reactions, like oxygen binding and NO dioxygenation, that appear general to the hemoglobin superfamily regardless of whether they are related to physiological function. Despite considerable attention to “hexacoordinate” hemoglobins, which are found in nearly every plant and animal, no clear physiological role(s) has been assigned to them in any species. One popular and relevant hypothesis for their function is protection against NO. Here we have tested a comprehensive representation of hexacoordinate hemoglobins from plants (rice hemoglobin), animals (neuroglobin and cytoglobin), and bacteria (Synechocystis hemoglobin) for their abilities to scavenge NO compared to myoglobin. Our experiments include in vitro comparisons of NO dioxygenation, ferric NO binding, NO-induced reduction, NO scavenging with an artificial reduction system, and the ability to substitute for a known NO scavenger (flavohemoglobin) in E. coli. We conclude that none of these tests reveal any distinguishing predisposition toward a role in NO scavenging for the hxHbs, but that any hemoglobin could likely serve this role in the presence of a mechanism for heme iron re-reduction. Hence, future research to test the role of Hbs in NO scavenging would benefit more from the identification of cognate reductases than from in vitro analysis of NO and O2 binding

Influence of mitochondrial genome rearrangement on cucumber leaf carbon and nitrogen metabolism

The MSC16 cucumber (Cucumis sativus L.) mitochondrial mutant was used to study the effect of mitochondrial dysfunction and disturbed subcellular redox state on leaf day/night carbon and nitrogen metabolism. We have shown that the mitochondrial dysfunction in MSC16 plants had no effect on photosynthetic CO2 assimilation, but the concentration of soluble carbohydrates and starch was higher in leaves of MSC16 plants. Impaired mitochondrial respiratory chain activity was associated with the perturbation of mitochondrial TCA cycle manifested, e.g., by lowered decarboxylation rate. Mitochondrial dysfunction in MSC16 plants had different influence on leaf cell metabolism under dark or light conditions. In the dark, when the main mitochondrial function is the energy production, the altered activity of TCA cycle in mutated plants was connected with the accumulation of pyruvate and TCA cycle intermediates (citrate and 2-OG). In the light, when TCA activity is needed for synthesis of carbon skeletons required as the acceptors for NH4+ assimilation, the concentration of pyruvate and TCA intermediates was tightly coupled with nitrate metabolism. Enhanced incorporation of ammonium group into amino acids structures in mutated plants has resulted in decreased concentration of organic acids and accumulation of Glu