Dynamic mechanism of phase variation in bacteria based on multistable gene regulatory networks.

Phase variation, which causes splitting the homogeneous bacterial population into subpopulations of the cells with different and reversible activity of the same variable genes, provide bacteria with wide opportunities to implement their adaptation strategies. Meanwhile, the gene networks perform integral regulation of the genome and control over the formation of phenotypic traits of the organism. Mechanisms of phase variation, such as genomic rearrangements and DNA methylation, affect the regulatory contours of gene networks.

Gene and epigene networks: two levels in organizing the hereditary system.

Intracellular governing gene networks consisting of genes and regulatory bonds among them are considered as the first level in organizing the hereditary system. We give examples of both prokaryotic gene network that controls the development of the lambda-phage and eukaryotic gene network that controls the early Drosophila ontogenesis. Using the method of generalized threshold models kinetic curves are shown for some gene products of these networks.

Parametric stability evaluation in computer experiments on the mathematical model of Drosophila control gene subnetwork.

Using the method of generalized threshold models, the problem is formulated and solved to evaluate the parametric stability of the model of a gene subnetwork controlling the early ontogenesis of the fruit fly Drosophila melanogaster. Computer experiments have been performed to test the parametric stability of the model. Quantitative evaluations have been obtained for parametric stability of the Drosophila gene subnetwork in nuclei along the embryo's anterior-posterior axis.

Epigenes: design and construction of new hereditary units.

A plasmid digene construction designed before [Tchuraev, R.N. (1982) J.

A new method for the analysis of the dynamics of the molecular genetic control systems. II. Application of the method of generalized threshold models in the investigation of concrete genetic systems.

Mathematical models of the prokaryotic control systems of tryptophan biosynthesis (both normal and with cloned blocks) and arabinose catabolism have been built using the method of generalized threshold models. Kinetic curves for molecular components (mRNAs, proteins, metabolites) of the systems considered are obtained. It has been shown that the method of generalized threshold models gives a more detailed qualitative picture of the dynamics of the molecular genetic control systems in comparison with the heuristic method of threshold models.

A new method for the analysis of the dynamics of the molecular genetic control systems. I. Description of the method of generalized threshold models.

In the molecular system of coding polymers and metabolites a control subsystem has been singled out that forms controlling variables showing the action of regulatory molecules and a controlled subsystem where, depending on the values of controlling variables controlled variables are formed, i.e. concentrations of DNA, m-RNA, proteins and metabolites.