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A S Tikhonenko

Publications and source records attributed to A S Tikhonenko.

At least 19 recordsLinked to original sources
PubMed1985

[Changes in the ultrastructure of subcomponent C1q of human complement during spontaneous inactivation in diluted solutions].

Dilution of human serum or solutions of highly purified subcomponent C1q of human complement results in the drop of C1q activity. Electron microscopy of highly purified subcomponent C1q revealed that a certain part of molecules has a changed ultrastructure and C1q subunits are dissociated. As the preparations for electron microscopy have been obtained from dilute solutions, the changes in the ultrastructure and C1q inactivation should be interrelated phenomena. The conformational liability of the C1q structure is supposed to have a functional role.

Complement Activating Enzymes↗
PubMed1984

Structural organization of macronuclear chromatin of the ciliate Bursaria truncatella in resting cysts and at excysting.

The structural studies of macronuclear chromatin of the ciliate Bursaria truncatella showed that in resting cysts practically all macronuclear chromatin was arranged in compact clumps 100 to 300 nm in size. By means of negative staining the internal structure of chromatin clumps was revealed; the chromatin clumps were shown to consist of subunits corresponding in size to nucleosomes. Upon incubation in low salt buffer the chromatin clumps decondensed forming loop-shaped chromatin fibres suggesting a similar structural organization of both the chromatin clumps of cysts and the chromatin clumps of grown and differentiated Bursaria truncatella cells [8, 9, 16]. We established that at excysting there occurred natural decondensation of the chromatin clumps resulting in loop-shaped chromatin fibres around the clumps. This in all probability was due to activation of macronuclear chromatin. Sometimes short transcription units of nonribosomal genes (0,2-1,3 micron in contour length) with closely located RNP-fibrils (more than 20 fibrils per 1 micron) were observed on the loops. We suggest that such genes respond to the synthesis of proteins involved in regulation of excysting and/ or subsequent cell growth and differentiation.

Animals↗
PubMed1983

Bacteriophages of methanotrophs isolated from fish.

Bacteriophages of methanotrophic bacteria were isolated from 67 fish. Only two phages isolated from two fish species specifically lysed Methylocystis sp. and Flavobacterium gasotypicum. The phages lysing these species were designated 63-F and CMF-1-F, respectively. The isolated phages differed greatly in the fine structure of the virion, plaque morphology, spectrum of lytic action, serological properties, and UV sensitivity. At the same time, they had identical one-step growth characteristics: their latent period equalled 5 h, lysis time was 3 to 4 h, and burst size was about 240 virions. The phages had guanine- and cytosine-rich double-stranded DNAs consisting of common nitrogen bases. The molecular masses of the DNAs as determined by the sums of restriction endonuclease cleavage fragments were 28 X 10(6) daltons for phage 63-F and 31 X 10(6) daltons for phage CMF-1-F.

Animals↗
PubMed1983

The structure of inactive interphase macronuclear chromatin of the ciliate Bursaria truncatella. Radial loops in the structure of chromatin clumps.

The organization of chromatin in macronuclei of Bursaria truncatella cells that completed their growth and differentiation was electron microscopically studied. The data obtained showed that (1) inactive macronuclear chromatin was organized in compact chromatin clumps 120 to 180 nm in diameter linked by one or several chromatin fibres, and (2) in low salt buffer the chromatin clumps gradually unraveled, radial loops of supranucleosomal or, more often, nucleosomal structure appearing around chromatin clumps. Upon prolonged incubation in low salt buffer chromatin clumps were completely transformed into nucleosomal fibres. The data obtained evidenced in favour of a loop-packed structure of chromatin clumps.

Animals↗
PubMed1981

[Structural study of the chromatin of the myxomycete Physarum polycephalum in the mitotic cycle].

The chromatin structure of Physarum polycephalum was studied with electron microscope at different phases of its mitotic cycle. At the S-phase and during mitosis, the chromatin has a nucleosomal structure. At the early G2-phase the chromatin structure changes, long regions of non-beaded structure being found in the chromatin fibers. At the late G2-phase, the major part of chromatin loses its globular organization, with chromatin fibres without a pronounced subunit structure prevailing in the preparations. Biochemical data show that the amount of chromatin resistant to staphylococcal nuclease varies during the mitotic cycle. The amount of nuclease-resistant chromatin is equal to 80% at the S-phase, to decrease up to 50-60% by the early G2-phase. Successive changes of chromatin structure at different levels of its transcriptional activity are found. Lability of nucleosomes is shown to increase with the increase in the transcriptional activity of chromatin, thus leading presumably to the chromatin structural alterations during the mitotic cycle.

Chromatin↗
PubMed1977

[Bacteriophage induction in cultures of C1. botulinum type A].

The authors describe the mitomycin induction of bacteriophages in strains No. 4/2, 98, and 345 of Cl. botulinum, type A. All the strains under study produced phages of the same morphology with a head and a process capable of contraction. The phages detected by electron microscopy failed to express any lytic activity on the strains of type A and other Cl. botulinum types neither in the fluid nor in the hard nutrient media. The data obtained supplemented and widened the view on the incidence of phage carrier state in the cultures of botulism causative agent.

Bacteriophages↗
PubMed1976

[Conditions for the self-organization of submicroscopic structures from mycelial extracts of the "fructose" variant of Actinomyces roseflavus var. roseofungini].

Self-organization of various submicroscopic formations, such as "tubes", "ribbons", etc. differing in ultrastructure and containing a polyenic antibiotic was observed in acetone extracts of the mycelium of the "fructose" variant of Actinomyces roseoflavus var. roseofungini. Conditions for separate isolation of the above structures are described. Concentration of the extract and the ratio of the volumes of water added to the extract are determinant for the process of self-organization. A possibility of reorganization of the tubular structures into the ribbon-like ones and vice versa is shown.

Cell Fractionation↗
PubMed1976

[Production of tubular structures from the aerial mycelium of Actinomyces roseoflavus var. roseofungini].

Tubular formations analogous by their structure to those found on the surface of the outer sheath of the hyphae of the aerial mycelium of Actinomyces roseoflavus var. roseofungini were reconstructed in vitro from the mycelium acetone extract on addition of water. A polyenic antibiotic was shown to be present in the composition of the "tubes". A possible role of the antibiotic in the genesis of the secondary structures of the actinomycete is discussed.

Culture Media↗
PubMed1976

[Effect of mutagens on RNA-containing phages and its infectious RNA. VII. Genetic nature of morphologic mutants of RNA-containing phage MS2].

Temperature-sensitive "leaky" mutants of phage MS2 having white dense ring around negative colonies are described. As these mutants are used for quantitative genetic studies, the white ring presents interest. Typical mutant 40 is used as a model for investigation. Light microscopy has shown, that cells from white ring zone have spore-like inclusions, which determine the characteristic structure of surrounding mutant negative colonies. Cytochemical reactions for the presence of glicogen, lipids, volutin, nuclear material and spores were negative. Electrone microscopy of negatively stained samples and ultrathin sections has revealed that cells from white ring zone, unlike phage-infected wild type cells, have two types of electron dense inclusions: 1) crystalline structures formed with great number of closely packed mature phage particles, and 2) large amorphic bodies. Electrone microscope-cytochemical data showed that inclusions remain intact under treatment of ultrathin sections of white zone ring with DNase and perchloric acid, while nuclear material was completely destroyed. Amorphic bodied were completely destructed after the treatment with RNase, while nuclear material and crystalline phage aggregated remained unchanged. Therefore, amorphic bodies consist of RNA, which has not been used to form virions. Single cycle of the development of mutant 40 at 37 degrees and 43 degrees C and under the temperature of incubation 37 degrees leads to 43 degrees C and 43 degrees leads to 37 degrees C in the course of intracellular reproduction is investigated. Influence of the phage on growth on infected culture is studied. The data obtained draw to a conclusion that the impaired function belongs to cystron protein of the phage membrane. As certain mutations in this cystrone of RNA-containing phage result in the depression of cystrone RNA polymerase, it is supposed that the formation of RNA containing bodies in infected cells, determining the formation of white rings in NA, together with cristalline aggregates of cells, is a result of mutation damage of cystrone protein of the phage MS2 membrane.

Coliphages↗
PubMed1975

Effective selection of Proteus mirabilis clones producing mirabilicin D-52.

From a defective-lysogenic Proteus mirabilis strain we isolated several clones differing in the pattern of their growth on agar plates. Using electron microscopy we have shown some of the selected clones to be efficient in producing mirabilicin D-52 after UV induction, while other clones produced defective mirabilicin polysheaths and polycores. Clones producing polysheaths and polycores can be detected electron microscopically only, since these defective particles are biologically inactive.

Bacteriocins↗
PubMed1975

Electron microscopy of phages liberated by megacin A producing lysogenic Bacillus megaterium strains.

Mitomycin C was added at fairly high concentration (5-10 mug/ml) to exponentially growing cultures of selected strains of Bacillus megaterium. Lysis of the bacteria followed, associated by liberation of phage and megacin A production. In contrast, a low concentration (0.5 mug/ml) of mitomycin induced only megacin A production. Electron microscopic examination of the lysates induced by 5-10 mug/ml of mitomycin in 19 strains of B. megaterium showed them all to contain phages; most of the strains proved polylysogenic. Their lysates contained distinct complete phages of different structures and dimensions. A few strains released defective phage particles. The significance of the electron microscopic findings is discussed in relation to megacinogeny.

Bacillus megaterium↗