Stress induced «railway for pre-ribosome export» structure as a new model for studying eukaryote ribosome biogenesis

The article presents the details of the process of structural organization, formation and disassembly of the nucleolus, chromatin condensation during the passage of the cell cycle studied by the method of classical transmission electron microscopy (TEM) in the cells of the meristematic zone of the wheat root. The transformations of peripheral chromosome material (PCM) in telophase, the transformations of the nucleolar nucleolonema in the interphase and prophase, and the chromatin transformations (condensation and decondensation) were studied and analyzed under the conditions of the geomagnetic field, weakened magnetic field and static magnetic field. Using an analysis of the dynamics of structural transformations of proliferating nuclei, we observed a disturbance in the formation of the chromonema and condensed chromatin in the middle interphase, a change in the structural organization of the nucleolus during the transition from late interphase to prophase, as well as a change in the structure of PCM, pre-nucleolus and chromatin in telophase. A schema for the generation of a specific conformation of nucleolonema and chromonema and its influence on the structural organization of chromosomes in anaphase and telophase was proposed. The nature of this structure is discussed. Possible mechanisms of the effect of magnetic field on the nuclear compartment, regulation of chromatin decompactization, export of pre-ribosomal particles under stress, and the fine structure of the nucleolonema are considered.