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.