The localization of the specific protein Surf-6 from nucleoli of eukaryotic cells in mitosis and its sensitivity to the treatment of cells with RNase A and DNase I in situ were studied. It was shown that, in interphase nucleoli of 3T3 mouse cells, Surf-6 is probably associated with RNA and practically is not associated with DNA. In mitosis, Surf-6 appears in forming nucleoli after the known RNA-binding proteins fibrillarin and B23/nucleofozmin, which are involved in the early and late stages of the assembly of ribosomal particles, respectively. These observations and the regularities of migration of early and late proteins of ribosome assembly to nucleoli in the telophase of mitosis led us to the presumption that Surf-6 is involved in the terminal stages of the assembly of ribosomal particles in murine cells. An immunoblot analysis of the Surf-6 content in synchronized 3T3 cells showed for the first time that Surf-6 is present at all stages of the cell cycle but its content markedly decreases when cells enter the G0 period. Conversely, the activation of cells for proliferation is accompanied by an increase in the Surf-6 content. These observations allow one to regard Surf-6 as a marker of the cell proliferative state and suggest its implication in the regulation of the cell cycle. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2005, vol. 31, no. 6; see also http://www.maik.ru.

3T3 Cells↗

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[Expression of ouabain-sensitive H+,K+-ATPase catalytic subunit gene in the rat epidermis].

A comparative localization of Na+,K(+)-ATPase and ouabain-sensitive H+,K(+)-ATPase in rat skin was performed using in situ RNA hybridization and immunohistochemistry. Na+,K(+)-ATPase was predominantly detected in the basal layer of epithelium, whereas the ouabain-sensitive H+,K(+)-ATPase, in the granular and prickle cell layers. The genes of these ATPases are thus expressed in epithelial cells at different stages of their development. The hypothesis was advanced that the ouabain-sensitive H+,K(+)-ATPase is involved in maintaining the skin pH value. The probes specific to the mRNAs of the full-size alpha-subunit of the ouabain-sensitive H+,K(+)-ATPase and its truncated form were used to establish a similar distribution of both mRNA variants in skin. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2002, vol. 28, no. 4; see also http://www.maik.ru.

Animals↗

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[Localization of chromosomal nucleus organizing regions in one-cell mouse embryos and oocytes by fluorescence in situ hybridization].

In mouse zygotes, ribosomal genes (rDNA) are transcriptionally silent and so-called "nucleolar precursor bodies" are present instead of typical nucleoli. However, the functional significance of these structures remains obscure. Specifically, it remains unknown whether structural association between the nucleolar precursor bodies and rDNA are maintained when rDNA synthesis is switched off. Here, we studied for the first time the rDNA topology in one-cell mouse embryos and MII oocytes using fluorescence in situ hybridization and mouse rDNA probes. Our data suggest that in the pronuclei of one-cell embryos, rDNAs form rather compact clusters, whose number does not exceed that of nucleolus organizing chromosomes characteristic for the haploid set of mouse chromosomes. In zygotic pronuclei, not all nucleolar precursor bodies are associated with rDNA and not all rDNA repeats are attached to the nucleolar precursor bodies. Altogether, these data favor the idea that spatial interactions of nucleolus organizing chromosomes and nucleolar precursor bodies are not obligatory. We assume that associations between nucleolar precursor bodies and nucleolus organizing chromosomal regions are mediated by centromeric heterochromatin. The total numbers of silver stained nucleolus organizing chromosomes in CBA and C57BL mice are different. rDNA genes are unequally distributed among nucleolus organizing chromosomes and nucleolus organizing regions of sister chromatids.

Animals↗

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[Autocatalytic nature of "slow virus infections"].

A concept that considers the causative nature of the so-called "slow virus infections", causing syndromes of spongiform encephalopathies in man and animals as a chain autocatalytic process is put forward. According to this concept, PrP(27-30) protein, isolated recently from the brains of scrapie-infected animals, is a C-terminal domain of the normal protein component of brain tissue which is a latent zimogen. Certain clinical and experimental data are discussed within the framework of this concept. Exogenous proteinases are presumed to be capable of triggering such a chain autocatalytic process in the brains of susceptible animals. Indeed, in one of our experiments, a subtoxic dose of pronase injected into mouse brain induced the development of a syndrome indistinguishable from spongiform encephalopathy in its clinical and pathomorphological manifestations. The probable role of neuron-specific proteins of intermediate filaments in such pathological processes is discussed. It seems possible that spongiform encephalopathies are particular cases of pathological processes that have catalytic nature. Presumably, the Alzheimer disease has such a catalytic causative nature.

Animals↗

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[A study on the metabolism of ribonucleic acid and protein in nucleoli of molluscan oocytes].

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Animals↗

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[Cytoarchitectonics of the cerebral cortex in mice selected for high and low brain weight].

The cortex cytoarchitectonics was studied in mice, which had been genetically selected for high (H-line) and low (L-line) brain weight and manifested some differences in their behaviour. Microscopic brain sections were analysed to estimate the areas of the neocortex, archicortex and paleocortex and to investigate quantitatively the microstructure in different zones of the neocortex. In the H-line, absolute value of total cortical area is, on the average, by 18% higher than that in the L-line--mainly owing to the larger area of neocortex, while the mean values of neurone volume fraction and profile field reveal no significant difference between the H- and L-line. Hence, the total number of neurones in the neocortex of mice from H-line should be greater, as compared with the L-line. Besides, within the framework of the same cerebral organization in general, the obtained data are indicative of a somewhat higher spatial differentiation of the neocortex in mice from the H-line.

Animals↗

PubMedDate not supplied

[Features of higher nervous activity in mice with Robertsonian chromosomal translocations].

The ability of laboratory mice to learn to solve a simple food searching task, and their ability to extrapolate the direction of stimulus movement, were investigated in animals of CBA inbred strain (64 mice) and in mice with Robertsonian fusion of 8 and 17 chromosomes -- Rb (8, 17) 1 IEM possessing different genetic background (122 mice). As the ability for extrapolation is tested while the animal has no previous experience of such task solving, this form of behaviour seems to be different from conditioning. Mice with Rb (8, 17) 1 IEM but not CBA mice proved to be capable to solve the extrapolatory task at its first presentation. Their learning ability was found to be also superior to that of CBA mice. The present data proved that mice with Rb (8, 17) 1 IEM translocation may serve as a very promising model for investigation of complex behaviour patterns.

Adaptation, Psychological↗

PubMedDate not supplied

[Physiological and genetic ways of studying the extrapolation capability of mice].

Elementary reasoning--the ability of mice to extrapolate the direction of alimentary stimulus movement--was investigated in gentically different groups of animals. It was shown that mice possessing. Robertsonian translocation Rb(8,17) 11EM were superior in the extrapolation task solving than mice with normal kariotype, or mice with Robertsonian translocations of other types (RB(5, 19)1Wh, Rb(6, 15)1ALD, Rb(9, 14)6Bnr, Rb(16, 17)7bnr). Mice selected for low brain weight were superior in the extrapolation task solving than mice with high brain weight in 3--11 generations of selection. In F12--F14 this difference was absent. Mice with Robertsonian translocations and mice selected for brain weight are perspective models for physiological and genetic study of elementary reasoning.

Animals↗

PubMedDate not supplied

[Capacity for learning and extrapolation of mice selected for having different brain weights].

Ability for learning a simple food-searching reaction, and for extrapolation of a food stimulus movement has been studied in two lines of laboratory mice selected throughout 15 generations for high (H-line) and low (L-line) brain weight. It has been found that the mice from H-line learn the food-searching reaction more rapidly than those from L-line. In first presentation of the extrapolation task, the percentage of right solvings by mice from H- and L-lines does not differ from the 50%, expected for the random alternative choice. In subsequent presentations, the percentage of right solvings steadily increases in both lines, and taken over all presentations significantly exceeds the 50% random level, while the mean time of performance gradually grows shorter. Thus, no difference is observed between H- and L-lines either in solving the extrapolation task or in learning this practice, in contrast to a noticeable superiority of H-line in learning a simple motor reaction.

Animals↗