Volume 11, Nº 4 (2017)

Hepatocellular carcinoma (HCC) is an aggressive cancer that is resistant to drug therapy. It is believed that the development of HCC is correlated with misregulation of programmed cell death. Discovery of effective inducers of HCC cell death is very important for HCC therapy. The aim of this work was to identify structural changes leading to the death of HCC cells exposed to nanosized and original forms of lithium salts. Structural features of autophagy and apoptosis were revealed in HCC cells after their incubation with various forms of lithium salts by light, electron microscopy, and flow cytometry. It was shown that nanosized forms of lithium carbonate and lithium citrate had a pronounced effect on HCC-29 cells. Of these forms, the nanosized lithium citrate induced mainly apoptosis, while the nanosized form of lithium carbonate, along with apoptosis, induced autophagic death of HCC cells.

Macrophages are cells of natural immunity and play a key role in pathogenesis of viral infections. Results of ultrastructural research on macrophages infected with tick-borne encephalitis virus (TBEV), an agent that causes dangerous infections affecting nervous system in human beings and belongs to the Flaviviridae family, were shown here. Using virology methods, it was ascertained that the TBEV is consumed by macrophages and multiplies in them. Ultrastructural research showed that the virus penetrates into the cytoplasm by means of local plasmalemma lysis and newly synthesized virus particles escape from the cell by the same path. At the same time, induration of the perinuclear space of cytoplasm was observed, where ribosomes, microfilaments, ribonucleoprotein threats, and virus-specific structures, namely, nucleocapsids, tube formations, and viroplasts, were found in large quantities. On the surface of viroplasts, newly synthesized virus particles were visualized. Thus, evidence was presented that microphages can play certain role in spreading of TBEV and are the target of the virus. Like active antigen-presenting cells, such macrophages can modulate the protective response of an organism and affect the pathogenesis of tick-borne encephalitis.

The nucleus of two-cell mouse embryos contains coilin-containing bodies of two types: (i) one to three large spherical structures 1 μm in size and (ii) small foci, which vary in number in different blastomeres. The largest coilin-containing structures, unlike the smallest ones, contain RNA polymerase I, nucleic acid chaperon YB-1, and actin. Neither large nor small coilin-positive domains contain symplekin, one of the signature components of histone locus bodies. In nuclei of late two-cell embryos, symplekin localizes to one to two well-formed spherical bodies that are observed both in close proximity to the coilin-positive structures and apart from them. Large coilin-containing bodies were not observed in embryos at the morula stage, as well as in the nuclei of late two-cell embryos after artificial suppression of transcription activity. Thus, the population of coilin-containing bodies in the nuclei of late two-cell embryos of mice is heterogeneous in morphology and molecular composition. It can be suggested that the largest coilin-containing bodies are provisional nuclear domains that are formed against a background of significant changes in the nuclear metabolism at the final stages of embryonic genome activation and the initial stages of reactivation of nucleolar transcription.

In this paper, we have developed a method to prepare spreads of mitotic chromosomes of Amoeba proteus and described the process of Amoeba proteus karyotyping. This protocol allows obtaining spread chromosomes with a characteristic pattern of chromomeres on individual chromosomes. It is shown that, in the metaphase of mitosis, amoebas of strain B (one of the type strains of A. proteus in the Amoebae Cultures Collection of the Institute of Cytology, Russian Academy of Sciences) contain 27 pairs of chromosomes. It is established that the pattern of chromomeres is a chromosome-specific feature. A typical karyogram and image bank of DAPI- and YoYo1-banded individual chromosomes of A. proteus, strain B composed of five different spreads of mitotic cells are presented.

We examined the organization of microtubule system of interphase cells in roots of Medicago sativa L. during acclimation to salt and osmotic stress at different concentrations of NaCl, Na₂SO₄, and mannitol. We identified morphological changes of tubulin cytoskeleton in different root tissues during the acclimation to salt and osmotic stress: (1) decreased density of the cortical microtubule network, (2) random orientation of cortical microtubule bundles, (4) thickening of the bundles, (3) nonuniform density of the bundles, (4) fragmentation of the bundles, and (5) formation of microtubule converging centers. Network thinning and thickening of the bundles were observed both under osmotic and salt stress. Random orientation of cortical microtubules was visualized under osmotic stress but not during salt stress. Fragmentation of microtubule bundles took place under salt stress with a high concentration of mannitol. Formation of microtubule converging centers was common under prolonged action of sodium sulfate, less evident under sodium chloride, and not found after mannitol treatment. Our data show that, in alfalfa root cells, cortical microtubules rearrange not only in response to different ions, but also to osmotic pressure. Thus, the signaling pathways and molecular mechanisms inducing reorganization of the microtubule system may be triggered by sodium cations, as well as by sulfate and chloride anions at concentrations that do not cause irreversible cell damage.