[Possible selection of variants of Act. spheroides without the actinophage-production capacity].
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Actinomyces↗
Biomedical subjects
V V Dmitriev
Publications and source records attributed to V V Dmitriev.
Ultrastructural characteristics of natural forms of microorganisms isolated from permafrost grounds of eastern Siberia by the method of low-temperature fractionation.
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Bacteria↗
[Effect of the RNAase from Bacillus intermedius on growth and physiological characteristics of Escherichia coli].
The effect of the RNase from Bacillus intermedius on the growth of Escherichia coli was investigated. RNase added to growth medium enhanced the synthesis of DNA, RNA, and protein and stimulated cell division; the degree of stimulation depended on the enzyme concentration. A necessary condition for stimulation was the adsorption of the enzyme on the cell surface and its interaction with the cytoplasmic membrane, as demonstrated immunocytochemically. The adsorption of the enzyme was accompanied by a 43% decrease in the surface charge density. Other effects of RNase involved a 25% increase in the growth rate, a 38% biomass gain, and generation time shortening by 10 min. The stimulation of bacterial growth correlated with the stimulation of cellular respiration rate.
Bacillus↗
[Production of Candida lipolytica protoplasts].
Optimal conditions were found for the production and isolation of the protoplasts of Candida lipolytica. The maximum amount of the protoplasts was produced after 90 minutes of the incubation with a crude preparation of the enzyme from Helix pomatia (100 mg/g wet biomass). Longer incubation results in lysis of the protoplasts and structural damages of the intracellular components. The yield of the protoplasts does not depend on the nature of stabilizing agent. A decrease in the stabilizer concentration increases the yield of the protoplasts four times. Preliminary treatment of the yeast cells with a 0.1 M solution of SH compounds (cysteine, beta-mercaptoethanol) does not increase the yield of the protoplasts; and 0.2 M solution of these compounds decreased the yield of the protoplasts.
Candida↗
[Comparative study of the ultrastructural characteristics of Torulopsis candida yeasts grown on glucose and hexadecane].
Electron-microscopic examination of the ultrastructure of Torulopsis candida cells grown on glucose and hexadecane revealed a well-developed network of canals in the cell wall of yeasts grown on hexadecane. These canals appeared in the non-adapted cells at the initial hours of the cultivation and completed their formation at the end of the logarithmic phase. The investigation by the freeze-etching showed the exocytosis of "secretory granules" to take place at the periplasma of the cells, and the morphological relationship of the granules to the canals in the cell wall.
Alkanes↗
[Ultrastructural organization of cytoplasmatic membrane of Anaerobacter polyendosporus studied by electron microscopic cryofractography].
Anaerobacter polyendosporus cells do not have typical mesosomes. However, the analysis of this anaerobic multispore bacterium by electron microscopic cryofractography showed that its cytoplasmic membrane contains specific intramembrane structures in the form of flat lamellar inverted lipid membranes tenths of nanometers to several microns in size. It was found that these structures are located in the hydrophobic interior between the outer and inner leaflets of the cytoplasmic membrane and do not contain intramembrane particles that are commonly present on freeze-fracture replicas. The flat inverted lipid membranes were revealed in bacterial cells cultivated under normal growth conditions, indicating the existence of a complex-type compartmentalization in biological membranes, which manifests itself in the formation of intramembrane compartments having the appearance of vesicles and inverted lipid membranes.
Bacillaceae↗
[Fine structure of mummified cells of microorganisms formed under exposure to a chemical analog of anabiosis autoinducer].
Under the influence of alkyl hydroxybenzene (C6-AHB) added to cell suspensions at a concentration of (1-5) x 10(-3) M, the cells of Saccharomyces cerevisiae, Micrococcus luteus, and Thioalkalivibrio versutus underwent dramatic changes in the ultrastructural organization of cell membranes, cytoplasm, and inclusions. In yeast suspension, the first changes were observed after 15 min in the structure of slit-like invaginations in the cytoplasmic membrane (CM): they were shortened and thickened. In the subsequent 30 to 60 min, CM ruptures were formed in the regions devoid of intramembrane protein particles and in the slit-like invaginations. After 24 h, complete disintegration of the intracellular membrane structures and conglomeration of the ribosomal part of the cytoplasm occurred. Similar changes were observed on the exposure of gram-positive and gram-negative bacteria to AHB. However, the cell wall in all the microorganisms studied was not destroyed, and in Micrococcus luteus it was even thickened. These mummified forms were preserved as morphologically intact but nonviable cells for more than three years of observations. By their ultrastructural characteristics, these mummified forms of microorganisms were similar to the fossilized microorganisms discovered by us in fibrous kerite. The concept of micromummies was formulated. AHB are supposed to play an important role in the process of fossilization of microorganisms in nature.
Adaptation, Physiological↗
[Methanotrophic communities in the soils of Russian northern taiga and subarctic tundra].
The PCR analysis of DNA extracted from soil samples taken in Russian northern taiga and subarctic tundra showed that the DNA extracts contain genes specific to methanotrophic bacteria, i.e., the mmoX gene encoding the conserved alpha-subunit of the hydroxylase component of soluble methane monooxygenase, the pmoA gene encoding the alpha-subunit of particulate methane monooxygenase, and the mxaF gene encoding the alpha-subunit of methanol dehydrogenase. PCR analysis with group-specific primers also showed that methanotrophic bacteria in the northern taiga and subarctic tundra soils are essentially represented by the type I genera Methylobacter, Methylomonas, Methylosphaera, and Methylomicrobium and that some soil samples contain type II methanotrophs close to members of the genera Methylosinus and Methylocystis. The electron microscopic examination of enrichment cultures obtained from the soil samples confirmed the presence of methanotrophic bacteria in the ecosystems studied and showed that the methanotrophs contain only small amounts of intracytoplasmic membranes.
Alcohol Oxidoreductases↗
[Isolation and morphological and biochemical characterization of mitochondria of yeast Torulopsis candida grown on glucose and hexadecane].
A method for isolating intact mitochondria from Torulopsis candida grown on glucose and hexadecane was developed. The isolated mitochondria were capable of oxidizing substrates of the di- and tricarboxylic acid cycle and of showing Chance respiration control. The morphological examination of the fractions showed that the major portion of mitochondria from yeast grown on glucose were in the condensed form whereas mitochondria from yeast grown on hexadecane were in the orthodoxal form.
Alkanes↗
[Cytoplasmic membrane invagination in basidiomycetous yeasts].
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Basidiomycota↗
[Penetration of pancreatic DNase into Candida tropicalis cells].
Permeability of Candida tropicalis cells for exogenic DNAse was studied by a cytochemical method. The enzyme were shown to penetrate yeast outer membrane and cell wall after a 20 minute incubation period when incubated together with cells at the beginning of the stationary phase.
Candida↗
[Changes in the fine structure of microbial cells induced by chaotropic salts].
The electron microscopic examination of the thin sections of cells of the yeasts Saccharomyces cerevisiae and Pichia pastoris and the gram-positive bacteria Micrococcus luteus and Bacillus subtilis showed that cell treatment with the chaotropic salts guanidine hydrochloride (6 M) and guanidine thiocyanate (4 M) at 37 degrees C for 3-5 h or at 100 degrees C for 5-6 min induced degradative processes, which affected almost all cellular structures. The cell wall, however, retained its ultrastructure, integrity, and rigidity, due to which the morphology of cells treated with the chaotropic salts did not change. High-molecular-weight DNA was localized in a new cell compartment, ectoplasm (a peripheral hydrophilic zone). The chaotropic salts destroyed the outer and inner membranes and partially degraded the outer and inner protein coats of Bacillus subtilis spores, leaving their cortex (the murein layer) unchanged. The spore core became accessible to stains and showed the presence of regions with high and low electron densities. The conditions of cell treatment with the chaotropic salts were chosen to provide for efficient in situ PCR analysis of the 16S and 18S rRNA genes with the use of oligonucleotide primers.
Bacillus subtilis↗
[Ultrastructure of resting cells of some non-spore-forming bacteria].
Using electron microscopy (ultrathin sections and freeze-fractures), we investigated the ultrastructure of the resting cells formed in the cultures of Micrococcus luteus, Arthrobacter globiformis, and Pseudomonas aurantiaca under conditions of prolonged incubation (up to 9 months). These resting cells included cyst-like forms that were characterized by complex cell structure and the following ultrastructural properties: (i) a thickened or multiprofiled cell wall (CW), typically made up of a layer of the preexisting CW and one to three de novo synthesized murein layers; (ii) a thick, structurally differentiated capsule; (iii) presence of large intramembrane particles (d = 180-270 A), occurring both on the PF and EF sides of the membrane fractures of M. luteus and A. globiformis; (iv) a peculiar structure of the cytoplasm, which was either fine-grained or lumpy (coarse-grained) in different parts of the cell population; and (v) a condensed nucleoid. Intense formation of cyst-like cells occurred in aged (2- to 9-month-old) bacterial cultures grown on diluted complex media or on nitrogen-, carbon-, and phosphorus-limited synthetic media, as well as in suspensions of cells incubated in media with sodium silicate. The general morphological properties, ultrastructural organization, and physiological features of cyst-like cells formed during the developmental cycle suggest that constitutive dormancy is characteristic of non-spore-forming bacteria.
Arthrobacter↗
[An electron microscopic study of the ultrastructure of microbial cells in extreme biotopes in situ].
The ultrastructure of microbial cells was studied in situ in natural biotopes by high-resolution transmission electron microscopy using the known methods of cryofractography, thin sectioning, and the negative staining of total cell specimens, as well as new methods of the low-temperature fractionation of microbial cells (providing for the recovery of cells from natural sources and their concentration), the preparation of micromonoliths, and aimed electron microscopy. Among the natural biotopes studied were permafrost ground and oil sludge. Most of the microorganisms found in the 1- to 3-million-year-old permafrost ground represented resting forms (spores, cysts, and cyst-like cells with specific organo-mineral envelopes). Oil sludge older than 35 years contained bacteria of atypical morphology and ultrastructure, including various resting forms and ultramicrobacteria. The data obtained is indicative of considerable promise of high-resolution electron microscopy in studying microbial communities in situ.
Bacteria↗
[Fluorescence microscopic study of the microorganisms treated with chaotropic agents].
The yeasts Saccharomyces cerevisiae and Pichia pastoris and the bacteria Micrococcus luteus, Bacillus subtilis, and Anaerobacter polyendosporus have been treated with the chaotropic agents guanidine hydrochloride and guanidine thiocyanate and certain detergents and studied using fluorescence microscopy. Studies with the use of fluorochromes that can selectively stain nucleic acids (diamidino-2-phenylindole (DAPI), propidium iodide, and acridine orange) show that treatment of the bacterial and yeast cells at 37 degrees C for 3-5 h induces a release of DNA from the cytoplasm and its accumulation in the cellular zone, known as ectoplasm, located between the cell wall and the remainder of the cytoplasm (called endoplasm) in the form of one or several large granules. After treating the cells with the chaotropic agents at 100 degrees C for 5-6 min, the DNA is diffusively distributed over the ectoplasm. The fluorochromes used do not allow the detection of RNA. These findings are in agreement with previous data obtained from electron microscopic study of thin cell sections. After 33 PCR cycles, a considerable portion of DNA leaves the cells; as a result, they show a low level of diffusive fluorescence when stained with DAPI. When endospores of B. subtilis are treated with the chaotropic agents, they become highly permeable to the fluorochromes. Fluorescence microscopic study of such endospores shows that they contain DNA in the central part of their cores.
DNA, Bacterial↗
[A new parasitological index for the estimation of peculiarities of the relationships between parasite and its host, and biotope of the host].
A new parasitological index (hostal-topical index) for the estimation of the degree of ectoparasite's relationship with its host and biotope of the host is proposed: [formula: see text], where [formula: see text]--hostal-topical index; n--amount of ectoparasites of the given species on the given host species in the biotope; N--amount of ectoparasites of all species from the given taxonomic group on the given host species in the biotope; n1--amount of hosts of the given species in the biotope; N1--amount of hosts of all species from the given taxonomic group in the biotope; n2--amount of ectoparasites of the given species in the biotope; N2--amount of ectoparasites of all species from the given taxonomic group in the biotope. Values [formula: see text] < 0.1 indicate that there is a distinct relationship with the biotope in spite of the host; values fallen into the range 0.1 < [formula: see text] < 0.5 indicate a moderate relationship with the biotope through the host; values [formula: see text] > 0.5 indicate a significant relationship with the host. By means of this index we have analyzed peculiarity of several parasitic species of fleas and gamasid mites to their hosts, biotopes, and biotope through the host. As it was found on the materials from different native zones and subzones of the Omsk Region (Western Siberia, Russia), values of the hostal-topical index for polyhostal parasitic species are lesser than those for oligohostal species. Values of this index can be different for the same species in the different native zones and subzones as well as in the different biotopes of the same native zone (subzone).
Animals↗
[Heparin therapy of disseminated intravascular coagulation in pyo-inflammatory diseases in children].
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Child↗
[Mechanism of the development of hypocoagulation disorders in the course of disseminated intravascular coagulation syndrome in newborn infants with pyo-septic diseases].
The development of hypocoagulation disturbances in sepsis of the newborn is mediated by the consumption of coagulation and vascular-platelet hemostasis factors. The formation of an insufficient clot in a number of patients may result in an increase of spontaneous fibrinolysis index, which does not correspond to the degree of decreased plasmin system activity due to its depletion.
Bacterial Infections↗