Читать книгу Algorithms in Bioinformatics - Paul A. Gagniuc - Страница 26

The mRNA and/or the protein products encoded by one gene often regulate the expression of other genes. In multicellular eukaryotes, the set of genes that are expressed in a specific cell type forms an “open” gene network. Each gene network is a self-orchestrated feedback loop constantly adapting to different inputs from the environment. The dynamics of a gene network may be deduced in practice from the gene expression levels. The RNA-Seq technique shows the set of genes, and their expression levels (amount of mRNA) at the time of cell/tissue sampling. Repeated sampling at different time intervals can complete a puzzle related to the functional relationship between the genes of the set. Direct or indirect activation of a gene promoter by the product of other genes (mRNA or proteins) is done with a relative delay and largely depends on the frequency by which the gene product is synthesized. The frequency of synthesis impacts the time of accumulation of the gene product (mRNA or proteins) in the cell as well as its stochastic diffusion toward other promoters and macromolecules with which it can interact. Note that the environment can be represented by a number of factors: the current set of molecules inside the cell, the signal molecules synthesized by other cells (other gene networks) or the amount of nutrients, pressure, temperature, and so on.