Biomedical subjects
Publications and source records attributed to J Krempaský.
Results of experimental and theoretical study of a photosynthetic system presented with rather complicated temporal behaviour are shown. Experimental results are comparable with those obtained previously by using the electrical method, and thus provide a support to the applicability of the more convenient spectrophotometric method. A possible explanation of a multimode nature of the oscillations observed is presented.
It was shown on the Frank autocatalytic reaction-diffusion scheme that strong environmental fluctuations, conditioned by external noise (e.g. sunlight fluctuation) and external macroscopic flows (e.g. ebb and flow), typical for conditions on prebiotic earth, may have been beneficial for chiral symmetry breaking and formation and stabilization of biomolecular homochirality.
Possible explanation is offered for the origin of pure chirality of amino acids and saccharides of racemic compounds during the prebiotical stage of evolution. It is based on the theory of "noise induced phase transitions", a mechanism approached in previous years by synergetic methods. It follows from this approach that a sufficiently intensive noise in the environment of the formation of racemic compounds of L- and D-chiralic macromolecules could produce homochiralic state, i.e. a state with either pure L- or D-chirality.
The paper deals with problems involved in the formation of stable structures in a system, in which processes typical of bimolecular autocatalytical reactions occur when the respective components are directly influenced from the outside. Such systems can arise in biochemical, biological and ecological sphere (see, e.g. Glansdorff and Prigogine 1971; Nicolis and Prigogine 1977; Haken 1977; 1980). It has been shown that a regions of so-called subcritical and supercritical regulation exist, manifested by the fact that the given system component would either persist or disappear. The selection of processes consists in the fact that generally only one solution can be realized from N alternatives as a stable state having the nature of a stable node, or a stable focus. When one of the components is supplied to the system from the exterior in a supercritical amount, the system can be "forced" to produce only that single substance. Thus, the system studied can be considered as a model of a biological filter. The results can also be applied in ecology and biotechnology.