[Visualization of DNA segments, interacting with reactive oligonucleotide derivatives in interphase nuclei and metaphase chromosomes]. / Vizualizatsiia uchastkov DNK, vzaimodeistvuiushchikh s reaktsionnosposobnymi oligonukleotidov, v sostave interfaznykh iader i metafaznykh khromosom.

Reaction of (pdT)16 derivatives, bearing 4-(N-2-chloroethyl-N-methylamino)benzylphosphamide group on its 5' end and biotin on its 3' end with DNA in interphase nuclei and metaphase chromosomes has been investigated by fluorescence and electron microscopy. The result obtained evidence that in interphase nuclei DNA in active chromatin (nucleolus) is the most available for specific modification. In metaphase chromosomes the modified DNA regions are situated on the surface of chromosome.

[The detection of the location of glucose-6-phosphate dehydrogenase in the fibroblasts of voles and mice and in rat myoblasts by using monoclonal antibodies against glucose-6-phosphate dehydrogenase]. / Vyiavlenie lokalizatsii gliukozo-6-fosfatdegidrogenazy v fibroblastakh polevok i myshi i v mioblastakh krysy s pomoshch'iu monoklonal'nykh antitel protiv gliukozo-6-fosfatdegidrogenazy.

Monoclonal antibodies (MAs) were produced against glucose-6-phosphate dehydrogenase (G6PD) of two vole species--Microtus arvalis and M. subarvalis. The binding level of the MAs to G6PD in both species were almost the same, which suggested that these MAs may be specific for the antigenic determinants common to G6PD of these species. The MAs produced against the vole G6PD were used for its intracellular localization. The patterns obtained after staining cells with the use of MAs against G6PD were the same as those obtained after staining with the use of antibodies against F-actin. There was a good conformity between the results of light and electron microscopic immunoenzyme analyses with regard to the binding of MAs produced to the actin microfilaments. It is concluded that G6PD is closely associated with actin microfilaments of the cell cytoskeleton.

[The behavior of the X chromosomes in intra- and interspecific hybrid cells of murine teratocarcinoma PCC4azal]. / Povedenie X khromosom vo vnutri- i mezhvidovykh gibridakh kletok teratokartsinomy myshi PCC4azal.

We have demonstrated that X chromosomes are reactivated in hybrids obtained by fusion of mouse PCC4azaI teratocarcinoma cells (XO, 39HPRT-) with splenocytes from mouse females heterozygous in Hprt gene. These hybrids are capable of spontaneous differentiation. We also obtained similar interspecies hybrids of PCC4azaI cells with bone marrow cells of the American mink. The majority of such hybrids remained undifferentiated, however, after long-term cultivation at high cell density they differentiated into epithelial- or fibroblast-like cells similarly to PCC4azaI cells. Two hybrids had the autosomal complement of the mouse and two X chromosomes (mouse and mink); both X chromosomes were active. These X chromosomes were not inactivated during differentiation in vitro.

[Effect of attachment to a solid substrate on the structural organization of skeletal muscle symplasts]. / Vliianie prikrepleniia k tverdomu substratu na strukturnuiu organizatsiiu skeletno-myshechnykh simplastov.

A study was made of the ultrastructural reorganization of myosymplasts passed from the primary suspension culture to the secondary monolayer culture. The microtubules in myoblasts and myosymplasts from suspension are very rare, the intermediate filaments form a perinuclear network, small bundles of myofilaments are arranged in disorder, often as whorls around nuclei. After attachment to the solid substrate the myosymplasts form pseudopodia to move as non-muscle fibroblast-like cells. On the leading end of moving symplasts some stress fiber-like structures are found. Numerous microtubules appear. The microtubules and intermediate filaments are arranged in parallel along the axis of a lengthening symplast. A stepwise reorganization of the non-muscle type cytoskeleton to sarcomeres of differentiated myotubes is observed later. The role of attachment and mechanical stress in myotube morphogenesis are discussed.

[Characteristics of the ultrastructural organization of the nuclei of somatic cell hybrids]. / Osobennosti ul'trastrukturnoi organizatsii iader gibridov somaticheskikh kletok.

A study was made of the ultrastructure of cell nuclei of two types of hybrid clones obtained from the fusion of Chinese hamster with human skin fibroblasts, and from that of mouse hepatoma cells with mink fibroblasts. In cell nuclei of the eight hybrid clones deep invaginations of the inner membrane, not characteristic of the parent cells, were revealed. Analysis of serial sections, and application of electron microscopic radioautography and histochemistry have suggested that these structures are associated with the nuclear envelope which is necessary for regulating the superfluous chromosome localization in the hybrid nucleus.

[Characteristics of the submicroscopic structure of hybrid clone cells obtained by the fusion of mouse hepatoma cells and mink fibroblasts and containing different numbers of mink chromosomes]. / Osobennosti sumbikroskopicheskogo stroeniia kletok gibridnykh klonov, poluchennykh ot sliianiia kletok gepatomy myshi i fibroblastov norki i soderzhashchikh raznoe chislo khromosom norki.

Four hybrid clones obtained by fusion of mouse hepatoma cells with mink fibroblasts treated with polyethyleneglycol were studied morphologically and morphometrically using electron microscopy. The clones studied contained a double set of mouse chromosomes and different numbers of mink chromosomes. It is demonstrated that clones containing different mink chromosomes differ considerably from each other and from the parental cells in the manifestation of some morphological characters (form and type of cell growth, form of the nucleus, structure of mitochondria, distribution of membranes of the granular endoplasmic reticulum), as well as in some quantitative parametres of organelles (area of the cut of the cell and of the nucleus, a relative volume of the nucleus). The data obtained witness for the fact that some morphological traits characteristic of cells of a certain parental type may appear in hybrids independently of each other, and that the degree of their manifestation may depend on the number of chromosomes of one of the parents or, possibly, on one particular chromosome.

[Use of cell enucleation in studying the stability of cytoplasmic organelles and cytoplasm organization]. / Primenenie énukleatsii kletok dlia izucheniia stabil'nosti tsitoplazmaticheskikh organell i organizatsii tsitoplazmy.

A study was made of the viability and ultrastructure of cytoplasts produced by enucleation of cytochalasin-induced A9 cells in suspension. These cytoplasts are in general as viable as cells enucleated in the monolayer. The organization of the cytoplasm, i.e. a specific distribution of cytoplasmic organelles, is conserved for at least 24 hours in the absence of the nucleus. This fact may reflect a high degree of autonomy of the cytoskeleton.

[Morphological and morphometric research on fibroblasts with genetically determined metabolic defects]. / Morfologicheskoe i morfometricheskoe issledovanie fibroblastov s geneticheski obuslovlennym defektami obmena.

The skin fibroblasts from people with the inherited metabolism diseases were studied by the methods of electron microscopy, light autoradiography and morphometric analysis. Comparison of morphological and morphometric data for the structure of the protein-synthesizing apparatus of the normal and deficient fibroblasts showed a significant role of the posttranslational regulation level of the basic specific syntheses in deficient fibroblasts.

[Characteristics of the manifestation of the morphological signs of muscle differentiation in a suspension culture of myogenic cells]. / Osobennosti proiavleniia morfologicheskikh priznakov myshechnoi differentsirovki v suspenzionnoi kul'ture miogennykh kletok.

With electron microscopy, cell elements were observed in a suspension culture of the chick embryo femoral muscle cells. The newly formed myosymplasts displayed no regular ultrastructure. A disturbance in the temporal sequence in myogenic steps was noticed, in addition to the appearance of uninucleated cells with a differentiated sarcomere zone.

[Reversible suppression of muscle differentiation expression in a monolayer culture]. / Obratimoe podavlenie ékspressii myshechnoi differentsiatsii v odnosloinoi kul'ture.

The phenotype of skeletal-muscle cells of a chick embryo in the primary monolayer culture maintained in the full medium (80% of the Eagle medium, 15% of serum, 5% of embryonic extract) and in the poor one (85% of the Eagle medium, 15% of serum) has been studied using both light and electron microscopy. In the full medium culture, which served as a control, the fusion of myoblasts (the index of fusion 51%) with the consequent formation of muscles fibers was observed. These fibres were able to contract and their ultrastructure was typical for differentiated skeletal-muscle cells. In the medium without an embryonic extract, the fusion of myoblasts was suppressed (the index of fusion 6%). The monolayer fibroblast-like cells lacking characters of differentiated muscle cells and, unlike, having those of typical fibroblasts were most numerous. The transference of myogene cells into fibroblast-like ones is reversal : after the substitution of the poor medium by the full one, both cell fusion (the index of fusion 45-47%) and differentiation of cell fibres are observed.

[Electron microscopic study of chick embryo myogenic cells in a suspension culture]. / Elektronno-mikroskopicheskoe issledovanie miogennykh kletok kurinogo émbriona v suspenzionnoi kul'ture.

Cell aggregates arising in the suspension culture of the chick embryo myogenic cells were studied by means of electron microscope. The small aggregates are formed by mononuclear myoblasts. The large aggregates are characterized by the tissular organization with the orderly distribution of different cell types. The periphery of such aggregates is occupied by polynuclear myosimplasts in different parts of which individual characters of muscle fiber are expressed to different extent. The cells similar with fibroblasts, chondroblasts, chondrocytes and even fatty cells, as well as collagenous extracellular matrix are situated in the centre of large aggregates. The possibility of origin of different cell types from myoblasts under the specific conditions of suspension culture is discussed.

[Electron microscopic study of mammalian somatic cell fusion under the action of polyethylene glycol]. / Elektronnomikroskopicheskoe issledovanie sliianiia somaticheskikh kletok mlekopitaiushchikh pod deistviem poliétilenglikolia.

An electron microscope study of heterokaryons and synkaryons, obtained after the treatment of suspension of human embryonic fibroblasts and cultured fibroblasts of Chinese hamster (clone M151) with polyethylene glycol (PEC, m. v. 6000) has shown that in 15 minutes after the administration of PEG, the cell agglutination and disappearance of plasma membranes between cells takes place. It is not obvious, however, how PER is passing through the cell envelope, but the similar action of PEF towards the inner cell membranes was observed. In the heterokaryons, the nuclear fusion may occur not only during mitosis but also in interphasic cells. Therefore heterokaryons transform to synkaryons extremely synchroneously. During 20 hours the majority, and during 48 hours all the heterokaryons are seen transformed to synkaryons.

[Method of electron microscopic autoradiography for studying the structural functional organization of particular regions of polytene chromosomes]. / Metod élektronnomikroskopicheskoi avtoradiografii dlia izucheniia strukturno-funktsional'noi organizatsii opredelennykh raionov politennykh khromosom

A method is described permitting to select particular chromosome regions and to compare their morphology as seen under the light and electron microscope levels with data of electronmicroscopic autoradiography. This method can be employed in studies with specific labelled precursors.