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1.
O. M. Lisitsyna Y. R. Musinova M. Y. Shubina V. Y. Polyakov E. V. Sheval 《Biology Bulletin》2013,40(6):558-561
Interphase prenucleolar bodies are globular bodies which accumulate in large numbers in the nucleoplasm of cultivated cells after hypotonic treatment and subsequent return to isotonic conditions; detailed studies of the role of these structures in the recovery of the nucleolus have not yet been performed. The limited mobility of interphase pronucleoli within the nucleus has been demonstrated. Exchange of the major nucleolar protein B23 between prenucleolar bodies and the surrounding nucleoplasm, rather than stable binding of this protein to the prenucleolar bodies, has been demonstrated using fluorescence recovery after photobleaching method. Gradual accumulation of B23 in the recovering nucleolus with concomitant disappearance of prenucleolar bodies has been demonstrated. 相似文献
2.
E. V. Sheval O. A. Dudnik S. S. Abramchuk V. Y. Polyakov 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2009,3(2):168-183
According to the radial loop model of chromosome organization, a major role in the formation and maintenance of chromosomes
is played by the residual structures (the nuclear matrix in interphase nuclei and the chromosome scaffold in metaphase chromosomes).
However, in vivo microscopy has recently revealed that the components of these “static” structures are highly mobile and continuously
exchanged between specific target sites and the nucleoplasm or cytoplasm. This contradiction between predicted stability and
observed dynamics led us to reexamine the principles underlying the association of proteins with residual structures. In the
present paper, we have analyzed the association of two perichromosomal layer proteins, pKi-67 and B23, with the residual structures.
The results show that these two proteins are associated with residual structures throughout the cell cycle; only those structures
change that contain proteins precipitated by 2 M NaCl (nucleoli, perichromosomal layer, prenucleolar bodies, cytoplasm of
mitotic cells). Both pKi-67 and B23 remain associated with the nuclear matrix even when they are translocated to nucleoplasmic
foci due to inhibitor action or hypotonic treatment. However, in most cases it remains possible to extract a structurally
visible protein fraction with 2 M NaCl (protein distributed in nucleoplasm). One may suppose that the protein fraction associated
with residual structures includes molecules interacting with their binding sites at the moment of permeabilization, while
the free proteins are extracted (i.e., during the interaction with binding sites, these proteins form salt-resistant complexes;
however, on diffusion the same proteins are extractable by the high-salt solution). The residual structures may be considered
as a “snapshot” of all proteins transiently (or statically) bound to their target sites at the moment of permeabilization.
The article is published in the original. 相似文献
3.
E. G. Volkova S. Y. Kurchashova E. V. Sheval V. Y. Polyakov 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2009,3(4):404-409
The nuclear pore complexes are complex protein structures located in the nuclear envelope, where they control the nuclear-cytoplasmic
transport, and inside the stacks of endoplasmic reticulum cisternae, annulate lamellae. After overexpression of some nucleoporins,
numerous granules are visible in the cytoplasm. According to the published data, these granules are the annulate lamellae.
In the current paper, the structural organization of POM121-containing granules was analyzed using correlative light and electron
microscopy. The ultrastructural study demonstrates that POM121-containing granules are not annulate lamellae but aggregates
of endoplasmic reticulum membranes. Thus, overexpressed POM121 is not able to induce the annulate lamella formation. The mechanisms
of self-organization of non-functional structures (such as the aggregates of endoplasmic reticulum membranes described here)
and possible involvement of these mechanisms in the formation of cellular structures are discussed. 相似文献
4.
5.
E. A. Arifulin E. E. Bragina V. A. Zamyatnina E. G. Volkova E. V. Sheval’ S. A. Golyshev L. N. Kintsurashvili G. I. Kir’yanov A. N. Prusov V. Yu. Polyakov 《Russian Journal of Developmental Biology》2012,43(2):121-130
Changes in chromatin structure at different stages of differentiation of human spermatids were studied. It was shown that,
in nuclei of early spermatids, chromatin is loosely packed and its structural element is an 8-nm fiber. This “elementary”
fiber is predominant at the initial stages of differentiation; in the course of maturation, it is replaced by globular elements
approximately 60 nm in diameter. In intermediate spermatids, these globules start to condense into fibrillar aggregates and
reduce their diameter to 30–40 nm. At all stages of spermatid maturation, except the final stages, these globules are convergence
centers for elementary fibers. This remodelling process is vectored and directed from the apical (acrosomal) to the basal
pole of the nucleus. In mature spermatids, the elementary 8-nm fibers are almost absent and the major components are 40-nm
fibrillar aggregates. The nuclei of mature spermatids are structurally identical with the nuclei of spermatozoa with the so-called
“immature chromatin,” which are commonly found in a low proportion in sperm samples from healthy donors and may prevail over
the normal cells in spermiogenetic disorders. The cause of this differentiation blockade remains unknown. Possibly, the formation
of intermolecular bonds between protamines, which are required for the final stages of chromatin condensation, is blocked
in a part of spermatids. The results of this study are discussed in comparison with the known models of nucleoprotamine chromatin
organization in human spermatozoa. 相似文献
6.
The method of chromatin photo-stabilization by the action of visible light in the presence of ethidium bromide was used for investigation of higher-level chromatin structures in isolated nuclei. As a model we used rat hepatocyte nuclei isolated in buffers which stabilized or destabilized nuclear matrix. Several higher-level chromatin structures were visualized: 100nm globules-chromomeres, chains of chromomeres-chromonemata, aggregates of chromomeres-blocks of condensed chromatin. All these structures were completely destroyed by 2M NaCl extraction independent of the matrix state, and DNA was extruded from the residual nuclei (nuclear matrices) into a halo. These results show that nuclear matrix proteins do not play the main role in the maintenance of higher-level chromatin structures. Preliminary irradiation led to the reduction of the halo width in the dose-dependent manner. In regions of condensed chromatin of irradiated nucleoids there were discrete complexes consisting of DNA fibers radiating from an electron-dense core and resembling the decondensed chromomeres or the rosette-like structures. As shown by the analysis of proteins bound to irradiated nuclei upon high-salt extraction, irradiation presumably stabilized the non-histone proteins. These results suggest that in interphase nuclei loop domains are folded into discrete higher-level chromatin complexes (chromomeres). These complexes are possibly maintained by putative non-histone proteins, which are extracted with high-salt buffers from non-irradiated nuclei. 相似文献
7.
Fibrillarin is one of the most studied nucleolar proteins. Its main functions are methylation and processing of pre-rRNA. Fibrillarin is a highly conserved protein; however, in the course of evolution from archaea to eukaryotes, it acquired an additional N-terminal glycine and arginine-rich (GAR) domain. In this review, we discuss the evolution of fibrillarin structure and its relation to the functions of the protein in prokaryotes and eukaryotes. 相似文献
8.
A novel approach for detection of replication sites in plant cells nuclei is described. The included nucleotide (EdU) was revealed by using “click” chemistry in semithin sections of the material embedded in acrylic resin. The use of the proposed protocol allows (1) to achieve good preservation of cell morphology, (2) to work with any tissues, and (3) to obtain high resolution during microscopy (especially, axial). 相似文献
9.
Gretsov E. M. Churakova J. V. Sheval E. V. Vorobjev I. A. 《Russian Journal of Developmental Biology》2004,35(3):182-190
We describe three lymphoid tumors with the same immunophenotype characteristic for chronic lymphoid leukemia (CD19+/CD5+, clonality of the light immunoglobulin chains, CD23+ and CD10–). However, clinical picture and morphology of neoplastic cells dictate different clinical forms of these cases: chronic lymphoid leukemia, large cell transformation of chronic lymphoid leukemia and diffuse large B-cell lymphoma. Taking into account that immunophenotype reflects the origin of tumor, while clinical outcome and morphological features of cells reflect the stage of tumor progression and/or pathway of tumor formation, we discuss the approach to natural classification of lymphoid tumors based on the process of their evolution. 相似文献
10.
Chromosome scaffold represents a continuous protein substructure revealed in isolated metaphase chromosomes after harsh extraction. According to postulates of the widespread radial loop model the scaffold plays an important role in the formation and maintenance of structural integrity of the mitotic chromosomes. Here, the data concerning the structure and major components of the chromosome scaffold are presented. The experiments suggesting that the scaffold represents a system of discrete linker proteins and the data about high mobility of scaffolding proteins are discussed. Furthermore, the data about higher-level chromatin structures (elementary chromonema and 200–250 nm fibers) and behavior of scaffolding proteins are compared. The results presented agree with the idea that at the present stage it is possible to discriminate chromatin complexes, whose structural integrity is not maintained by the chromosome scaffold. 相似文献