[Study of the quaternary structure of glutamate carboxylase from Escherichia coli]. / Issledovanie chetvertichnoi struktury glutamatdekarboksilazy iz Escherichia coli.

It was shown by electron microscopy, that the native molecule of glutamate decarboxylase is a hexamer with dihedral symmetry; the subunits are situated at the apices of an octahedron. Apoenzyme at pH 6.0 is dissociated form. It were found s20.w - 12.8 +/- 0.54S and 5.51 +/- 0.43S for the native hexamer and a dissociated form, respectively. By column gel-filtration the molecular mass of the dissociated form was estimated as 105-106 kDa, this value corresponds to a dimer. There were 10 buried SH-groups per subunit in the hexamer, after dimer formation 8 of them became accessible. The reversible hexamer-dimer dissociation depends on pH and PLP. The pH dependences of the enzyme dissociation and activity are very similar. In the result of adding of 6 PLP equivalents to the dimers the reactivation and hexamer assembly were reached, the SH-groups burying preceded both these reactions. Effect of pH and PLP on the quaternary structure is known for some other PLP-enzymes. It may be the additional proof for the idea of a common ancestor for PLP-enzymes.

[Electron-microscopic study of the morphology of scaffold-like structures in chromosomes, formed by formamide]. / Elektronno-mikroskopicheskoe issledovanie morfologii skéffold-podobnykh struktur v khromosomakh, obrabotannykh formamidom.

Isolated human metaphase chromosomes treated with formamide and prepared for electron microscopy by protein monolayer technique have an appearance of loop-shaped chromatin fibers coming off the central scaffold-like structures, such chromosomes having approximately the same histone content as those before treatment. The morphology of scaffold-like structures at different formamide concentrations is described. It is shown that during formamide treatment the protein-protein and/or protein-DNA interactions are weakened because of disruption of hydrogen bonds. However, the intermolecular interactions in the chromosomes allow them to preserve their shape and size. The changes in the structure of formamide-treated chromosomes become readily visible after spreading on the hypophase surface. It is shown that after removal of formamide from the incubation solution by dialysis, chromosomes condense drastically. The data obtained are in good agreement with the loop model of chromosome organization. However they evidence also that the scaffold in the form of a rigid characteristic chromosome structure arises as a result of redistribution and/or aggregation of chromosomal proteins during chromosome preparation.

[Detection of viral proteins during synthesis of defective phage of Proteus mirabilis D52 using the immunocolloid gold method]. / Vyiavlenie virusnykh belkov v protsesse sinteza defektnogo faga Proteus mitabilis D52 metodom immunokolloidnogo zolota.

We have applied the method of immunocolloidal gold in order to label the ribonuclear proteins of prokaryotic cells on isolated bacterial chromatosomes. In the process of protein synthesis it was possible to visualize a definite protein of defective phage D52 of Proteus mirabilis.

[Immune electron microscopy in the study of biological matter]. / Immunoélektronno-mikroskopicheskii metod v issledovanii biologicheskikh ob''ektov.

A brief review of literature data and our investigations on the antibodies used for specific labeling in electron microscopy is presented. Considered are the problems connected with structure and function of separate components of bacterial viruses revealed by means of specific antibodies. The results of fine differentiation of antigenic components in the case of phages of the colidysentery group allowed to elucidate the functional role of the adsorption apparatus in the course of phage interaction with the bacterial cell. The topology of structural proteins (gene-products 35, 36, 37) of the tail's long strands for phages T4, DDVI+h and DDVIh is determined. Antigenic properties of proteins that are found in the composition of two forms of Bacillus mycoides are demonstrated immune-electronmicroscopically. On the basis of this finding, a conclusion was made that one of these phages acted as precursor, the other--as satellite during the simultaneous development of these phages in the bacterial cell. It was also established that temperate and virulent phages are related antigenically, which proves that lysogenic bacteria can be one of the phage sources on the environmental conditions. Visualization of non-ribosomal genes of procaryots that code for structural proteins of a defective phage proves the efficiency of the immune-electronmicroscopic method for investigating of biological objects.

[Changes in the ultrastructure of subcomponent C1q of human complement during spontaneous inactivation in diluted solutions]. / Izmeneniia ul'trastruktury subkomponenta C1q komplememnta cheloveka pri spontannoi inaktivatsii v razbavlennykh rastvorakh.

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.

[Electron microscope study of changes in the chromatin structure in different functional states of nuclei of a ciliate Bursaria truncatella and a myxomycete Physarum polycephalum]. / Elektronno-mikroskopicheskoe izuchenie strukturnykh izmenenii khromatina v razlichnykh funktsional'nykh sostoianiiakh iadra infuzorii Bursaria truncatella i miksomitseta Physarum polycephalum.

Chromatin structural organization was studied by means of electron microscopy in the macronuclei of ciliate Bursaria truncatella at various stages of the life cycle (at different time intervals after cell division, in resting cysts and at excysting) and in the nuclei of myxomycete Physarum polycephalum during the mitotic cycle. Inactive chromatin was shown to be organized in compact clumps 100-300 nm in diameter linked with each other, their loop organization being convincingly demonstrated. Upon activation chromatin decompacts and is represented by nucleosomal fibres with a lot of replicationally and transcriptionally active regions. Both the reptication and transcription processes in physarum nuclei and transcription processes in bursaria can occur on the loops of chromatin fibres emerging from the decompacting clump. The data obtained evidence in favour of a structural-functional correspondence between the chromatin clumps of physarum and bursaria and the chromomeres in chromosomes of higher eucaryotes. Based on the data received it is concluded that the chromatin clump represents a dynamic structure unit able to decompact forming the loop-shaped chromatin fibres. Such a structural organization provides the spacial distribution of DNA in the nuclei and the possibility of selective functioning of definite regions of the genome.

[Study of the effect of different concentrations of a detergent on the chromatin structure of Physarum polycephalum during the mitotic cycle]. / Izuchenie vliianiia razlichnykh kontsentratsii detergenta na strukturu khromatina Physarum polycephalum v protsesse mitoticheskogo tsikla.

The influence of different concentrations of detergent Joy on the chromatin structure of Physarum polycephalum in the process of mitotic cycle was studied electronmicroscopically. The investigations showed that at Joy concentrations less than 0,01% a small part of nuclei disrupt and, as a rule, chromatin is insufficiently dispersed; at concentrations more than 0,1% the detergent may influence the chromatin structure of Physarum polycephalum. Based on the data obtained we consider that the optimal detergent concentrations that practically do not influence the chromatin structure and lead to disruption of the majority of nuclei and to the proper dispersion of chromatin is 0,1-0,01%.

[Structure of the macronucleus chromatin of the ciliate Bursaria truncatella. III. Chromatin organization in resting cysts and during excysting]. / Struktura khromatina makronukleusa infuzorii Bursaria truncatella. III. Strukturnaia organizatsiia khromatina v tsistakh pokoia i v protsesse ékstsistirovaniia.

Structural organization of macronuclear chromatin of a ciliate Bursaria truncatella was studied electronmicroscopically by means of Miller's technique and negative staining of resting cysts and at excysting. In resting cysts practically all the macronuclear chromatin was shown to be organized into compact chromatin clumps 100-300 nm in size. At excysting a natural decompactization of the chromatin clumps occurred and radial loop-shaped chromatin fibres appeared around the clumps. Sometimes transcription units with a relatively small contour length of transcribed region and with high RNA-polymerase density were observed on the loops. The responsibility of such genes for the synthesis of proteins taking part in regulation of excystment and/or subsequent cell growth and differentiation is discussed.

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.

[Structure of the interphase chromatin in the ciliata Bursaria truncatella macronucleus. II. Loop organization of inactive chromatin clumps]. / Struktura interfaznogo khromatina makronukleusa infuzorii Bursaria truncatella. II. Petel'naia organizatsiia glybok neaktivnogo khromatina.

Electron microscopic study of chromatin organization in isolated macronuclei of a ciliate Bursaria truncatella showed macronuclear chromatin to be organized in compact clumps 120--180 nm in diameter linked with each other by one or several chromatin fibres. Macronucleus being dispersed in a solution of low ionic strength, radial loops basically of nucleosomal structure start appearing around chromatin clumps. Long-time dispersing of macronuclear chromatin brings complete decompactization of chromatin clumps into a set of nucleosome fibres. The way the fibres of interphase chromatin are packed in a chromatin clump is discussed.

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.

[Topology of the structural proteins of long tail fibers of phages T4D, DDVIh+ and DDVIh]. / Topologiia strukturnykh belkov dlinnykh khvostovykh fibrill fagov T4D, DDV1h+ i DDV1h.

Topology of the products of the genes 34, 35, 36 and 37 of the bacteriophage T4D long tail fibers were determined with the aid of monospecific antibodies. The antibodies against gene product 34 were the only to interact with the proximal part of long tail fibers, but the distal part bound the antibodies against 35, 36 and 37. Product of the gene 35 is located at the joint-site with the distal part and binds the distance not more than 75 A long. Gene product 36 is located between these of 35 and 37 and occupy the region about 150 A. The capability of the antibodies obtained against the above-mentioned proteins were tested ot bind with long tail fibers diagnostic phages DDVIh+ and DDVIh Shigella disentheriae. We could'nt mark any difference in binding of the antibodies against gene 34, 35 and 36 product with DDVI phages and T4D. The distal part of the fibers of DDVIh bound the antibodies against product of gene 37 as T4D. Nevertheless DDVIh+ possesses only few antigenic sites relative to product of gene 37 of T4. The changes in the distal part of long tail fibers of h-strain DDVI may lead to the broadening of the host specifity of this virus.

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.

[Structural study of the chromatin of the myxomycete Physarum polycephalum in the mitotic cycle]. / Izuchenie struktury khromatina miksomitseta Physarum polycephalum v mitoticheskom tsikle.

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.

[Electron microscopic study of transcription of loach oocyte ribosomal genes]. / Elektronno-mikroskopicheskoe issledovanie transkriptsii ribosomnykh genov ootsitov v'iuna.

Transcription of ribosomal genes of a loach Misgurnus fossilis L. was studied by electron microscopy. Relative transcriptional activity in nucleoli at different vitellogenic stages was determined by direct calculation of the number of operating ribosomal genes in the nucleoli. Morphologic studies showed that the transcribing regions of mean length 2.3 +/- 0.2 mkm are separated by spacers of variable lengths. Both short (1.2--1.4 micrometer) and long (2.4--2.6 micrometer) spacers were visualised. The lateral RNP fibrils have granular structure, each granule containing 300--350 RNA bases. It was found that chromatin has nucleosomal structure in spacer regions and is of non-beaded, smooth structure in transcribing regions. The data obtained allow to suggest that in transcribing regions chromatin undergoes structural transition before the transcription process.

[Structure of polyriboguanylic acid in solution]. / Struktura poliriboguanilovoi kisloty v rastvore.

The electron microscopic data and the CD spectra of poly(G) have shown that the transition of a freeze-dried preparation of poly(G) from a "metastable" to a "stable" form is the transition of the four-stranded poly(G) from the globular form to the linear one. The observed phenomenon of the formation of long four-stranded poly(G) fibers (4--5 nm in diameter and 200-2000 nm in length) is suggested to be a result of a joint of the initial poly(G) molecules (50--80 nm in length) due to noncovalent binding ("sticking") of their free one-, double- or three-stranded ends. This phenomenon has permitted us not only to compare the thickness of low molecular weight poly (G) preparations under different conditions but to observe directly the existence of a large number of double-stranded (2--3 nm in diameter) regions ("defects") in four -stranded poly(G) fibers. The data obtained have shown that under certain conditions (high temperature, low pH, etc.) the four-stranded poly(G) fibers break down with the formation of two-stranded poly(G) fibers whose hydrogen bond systems depend on the conditions of their formation.

[Electron microscopic study of the action of submicroscopic levorin structures on Candida guillermondii]. / Elektronno-mikroskopicheskoe izuchenie deistviia submikroskopiches-kikh struktur levorina na Candida guilliermondii.

In the course of preparation of aqueous solutions of the polyene antibiotic levorin, the latter is recovered in the solid phase forming granular submicroscopic structures. If the cells of Candida guilliermondii are treated with submicroscopic granular structures (SMGS) of levorin, the structures are adsorbed on the surface of the yeast cell walls. Some visible changes occur in the ultrastructure of the yeast cells incubated with SMGS of levorin for 5 min: the inner layer of the cell wall becomes loose, the periplasmic space appears, the cytoplasmic membrane becomes thicker, the mitochondria swell, and fragmentation of the mitochondrial cristae takes place. Dense round alien bodies 20--40 mn in size can be discerned in the periplasmic space of such cells. If the yeast cells are treated with the levorin structures for a longer period of time (15--60 min), the cell ultrastructure is entirely disorganized.

[Virulent and temperate phages of Bacillus licheniformis, the producer of bacitracin antibiotic]. / Virulentnye i umerennye fagi Bacillus licheniformis--produtsenta antibiotika batsitratsina.

Virulent and temperate bacterial phages were isolated from the cultural broth of Bacillus licheniformis obtained under the industrial conditions when synthesis of the antibiotic bacitracin was interfered with. The following properties of the phages were studied: the fine structure, the morphology of negative colonies, the spectrum of lytic action, the rate of adsorption, the individual growth cycle, as well as the lysogenic state of certain strains of Bac. licheniformis. Some phages were serologically related and morphologically identical whereas others differed sharply in their morphology and antigenic properties.

[Fine structure of the outer sheath of the aerial mycelium in Actinomyces levoris]. / Tonkoe stroenie poverkhnostnogo chekhla vozdushnogo mitseliia Actinomyces levoris.

The outer sheath of the aerial mycelium of Actinomyces levoris 64 bears groove-like and granular submicroscopic structures. They are very susceptible to a short-term treatment of the aerial mycelium with aqueous acetone which causes their disintegration. Under specified conditions, submicroscopic structures, viz. granules and threads, assemble from the acetone extract of the aerial mycelium of Actinomyces levoris. These structures possess the anti-yeast activity. The granular structures reorganized from the acetone extract of the aerial mycelium of Actinomyces levoris somewhat resemble in morphology the structures seen in the outer sheath of the aerial mycelium of this actinomycete. The results obtained are discussed within the framework of the hypothesis on a possible participation of polyene antibiotics in the formation of the outer sheath of the aerial mycelium of actinomycetes which produce these antibiotics.

[Bacteriophage induction in cultures of C1. botulinum type A]. / Induktsiia bakteriofaga v kul'turakh C1. botulinum tipa 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.