Biomedical subjects

M V Gusev

Publications and source records attributed to M V Gusev.

72 records · Page 4Linked to original sources

PubMedDate not supplied

[Pyocyanin reactions with Pseudomonas aeruginosa cells and their fragments].

Pyocyanin added to suspensions of Pseudomonas aeruginosa P changes the structural organization of the cells depending on their physiological characteristics, in particular, the capability to liberate pyocyanin into the cultural broth. Exogenous pyocyanin does not interact with the cells of the parent strain producing the pigment. However, the structure of the isolated cell walls deformed after the fractionation becomes similar, upon contact with pyocyanin, to the structure of the freshly isolated cell walls. The fraction of the cytoplasmic membranes of the parent strain also slightly changes its spatial organization after addition of pyocyanin. The cells of the mutant which do not produce pyocyanin display the ability for structural interaction with exogenous pyocyanin. In contrast, the fraction of their cell walls does not react to addition of the pigment. The cytoplasmic membranes of the mutant interact with pyocyanin in the same manner as the whole cells. These changes caused by pyocyanin always involve certain parts of the molecules. As a result, the following features are observed in their spectra: the absorption at 1475 cm-1 becomes more intensive; the "knee" at the band Amide II is more pronounced in the range of 1500 cm-1; the absorption at 1520 cm-1 decreases as well as the intensity of the band Amide II as a whole. The interaction of pyocyanin with biological objects stems, apparently, from the presence of certain proteins in them since peroxidase was found to respond to pyocyanin in a manner similar to that described for the cells and their fractions.

Cell Wall↗

PubMedDate not supplied

[Comparative study of the oxygen reduction in photosystem II of the cyanobacteria, Anacystis nidulans and Anabaena variabilis].

Oxygen reduction in the photosystem II (PS II) of thylakoid membranes from the cyanobacteria Anacystis nidulans and Anabaena variabilis was studied in the system SiMo + DCMU in whose presence competitive electron transport to SiMo and O2 in possible. The reagents of the Mehler reaction were used; these reagents activate oxygen uptake by interacting with the reduced forms of oxygen (malonate and oxalate with O2; glyoxylate and catalase + ethanol with H2O2). The use of the reagents as shown that there was a considerable electron transport to O2 which decreased the rate of SiMo reduction and visible oxygen evolution. Oxygen was reduced to O2 and H2O2 in the photosystem II of A. nidulans whereas practically no generation of H2O2 was observed in the photosystem II of A. variabilis. Malate was found to be capable of activating oxygen uptake in the PS II of the cyanobacteria by interacting with O2. Oxalate was capable of this interaction only in the membranes of A. variabilis, but not in the membranes of A. nidulans where it competed with water as an electron donor. A decrease in SiMo reduction and oxygen evolution in A. nidulans in the presence of glycolate was due to oxidation of glyoxylate which was formed in the course of enzyme-catalyzed oxidation of glycolate by the membranes possessing the activity of glycolate oxidase, and the subsequent interaction of glyoxylate with H2O2. SiMo reduction by the cyanobacterial membranes and by the spheroplasts of A. variabilis, in contrast to the chloroplasts of higher plants, did not decrease in the presence of DCMU, but went on at a linear rate until the substrate was completely exhausted. The role of reduced O2 forms in metabolism of a phototrophic cell is discussed.

Cell Membrane↗

PubMedDate not supplied

[KMnO4-induced change in the chemiluminescence of Pseudomonas aeruginosa cells after their preliminary interaction with pyocyanine].

Pyocyanin was capable of interacting with the cells when it was added to the cell suspensions of a Pseudomonas aeruginosa P. culture producing the pigment and a mutant that did produce pyocyanin. As a result, the intensity of chemiluminescence induced by KMnO4 in the cells decreased. Pyocyanin inhibited the chemiluminescence of the parent strain and mutant cell homogenates and their fractions, with an exception of the fraction of the mutant cell walls with which it did not react. The character of pyocyanin interaction with the cells of Ps. aeruginosa P. was shown to depend on the conditions of the cultural incubation.

Kinetics↗

PubMedDate not supplied

[Conditions for cyanobacteria L-transformation].

Anabaena variabilis and Chlorogloea fritschii can easily form L-like colonies that are characterized by their appearance and the morphology of component structures. The colonies consist of morphological elements typical of the L-variants of chemoheterotrophic bacteria: filaments, "grains", ring-shaped cells, etc. Data are presented pertinent to the functional activity of the photosynthetic apparatus of these organisms subjected to L-transformation.

Cyanobacteria↗

PubMedDate not supplied

[Effect of cyanobacteria excretions and cell biomass on hydrocarbon-oxidizing mycobacteria].

The presence of cyanobacterial cells and their exocellular excretions in an aqueous ecosystem stimulated biodegradation of diesel fuel. As was established using the technique of complete factor analysis, nitrogen addition to the medium and the presence of cyanobacterial cells in it are important for the growth of oil-oxidizing bacteria, while exocellular excretions of the cells are not sufficient for such a growth. The mycobacterial growth depended, to a certain extent, on the age of cyanobacterial cultures.

Cyanobacteria↗

PubMedDate not supplied

[Effect of petroleum hydrocarbons on the viability of cyanobacteria in association with oil-oxidizing bacteria].

An important aspect in the problem of interactions between microorganisms in the conditions of oil pollution is how to preserve the viability of phototrophic organisms if active oil-oxidizing microflora is present in the environment. As was illustrated using a closed model ecosystem, the association 'cyanobacteria--oil-oxidizing bacteria' is capable of withstanding the negative effect of oil pollution, but within the range of hydrocarbon concentrations which can be oxidized by oil-oxidizing bacteria during a very short time. The biological equilibrium in the ecosystem was maintained and the number of viable cells of the phototrophic component in the ecosystem increased if the oil-oxidizing bacteria started to function at the same time as toxic compounds commenced to produce their effect on the microorganisms.

Cyanobacteria↗

PubMedDate not supplied

[Petroleum-oxidizing microflora of the Arctic seas of the USSR].

Active petroleum-oxidizing bacteria of the USSR arctic seas are represented by Mycobacterium mucosum (non-colored), Mycobacterium phlei and Mycobacterium brevicale (red-orange) which inhabit the Yenisei Bay, the Kara Sea and the Laptev Sea. Vertical distribution of the petroleum-oxidizing mycobacteria is characterized by substitution of non-coloured forms for coloured ones with depth: "white" strains are found mainly in the surface layer while red and yellow-orange strains are detected in deep water layers and near the bottom.

Arctic Regions↗

PubMedDate not supplied

[Microbiologic oxidation of diesel fuel by the total factor experiment method].

The effect of nitrogen, phosphorus, glucose and temperature on the assimilation of diesel fuel and the biomass yield of Mycobacterium mucosum was studied by the method of complete factor experiment. The concentration of nitrogen and phosphorus were shown to be most important for the above processes. The growth dynamics of the culture was studied as well as the utilization by it of diesel fuel and glucose added to the medium separately or in combination. The presence of glucose in the medium had no effect on the utilization of diesel fuel; however, the utilization of glucose in the presence of diesel fuel was considerably decelerated.

Fuel Oils↗

PubMedDate not supplied

[Substrate-induced changes in Mycobacterium paraffinicum cells and cell membranes].

The method of spectroscopy of attenuated total reflection (ATR) range was used to study the dynamics of biochemical changes of both the whole cell of Mycobacterium paraffinicum 134 and its outer layer depending on the type of growth substrate. The cells and their outer layers were shown to vary significantly in their composition upon growth in different media. When the cells were cultivated in a medium with glucose, the biosynthesis of structural lipids of the cell wall, viz. glycolipids and mycolic acids, proceeded at a high rate. The quantity of triglycerides produced at the stationary growth phase was also high. When the cells were cultivated in MPB, the content of structural and reserve lipids was very low in both the cell and its outer layer. Therefore, a sufficiently lipophilic cell wall was formed when the cells were grown in the medium with glucose, but it was much less lipophilic when the cells were cultivated in MPB. Consequently, the both types of cells differed in their capacity to absorb a hydrophobic substrate. The paper discusses the role of lipid components in regulating the structure of mycobacterial cell walls depending on a growth substrate.

Alkanes↗

PubMedDate not supplied

[Study of the dynamics of the uptake and utilization of a hydrocarbon in Mycobacterium paraffinicum cells by means of IR-spectroscopy].

The dynamics of uptake and further utilization of hexadecane in different regions of the cells of Mycobacterium paraffinicum was studied using spectroscopy of Attenuated Total Reflection (ATR) in the IR range during the whole period of their growth. The outer layers of the cells were found to be rapidly saturated during their growth on a medium containing hexadecane. Oxidation of the hydrocarbon resulted in accumulation of a large amount of triglycerides whose active biosynthesis started at the end of the logarithmic growth phase. The bulk of triglycerides concentrated in the cytoplasm. Later, the content of triglycerides decreased almost twofold, this suggesting assimilation of these compounds by the cell. After 13 days of cultivation, all parameters were stablized; therefore, the metabolic processes decelerated and the state of dormancy occurred. No degradation of the culture was observed.

Alkanes↗

PubMedDate not supplied

[Electron microscopic and biochemical study of spheroplasts of the blue-green alga Anabaena variabilis].

Electron microscopy of the spheroplasts of the blue-green alga Anabaena variabilis revealed damages induced by lysozyme. Biochemical analysis confirmed the data of electron microscopy that the spheroplasts had lost partly the cytoplasmic content of the cells. DNA was preserved in the spheroplasts though the nucleoid was not detected by electron microscopy.

Cyanobacteria↗

PubMedDate not supplied

[Comparative study of the functions of the spheroplasts and cells of the blue-green alga Anabaena variabilis].

The effect of light was studied with the spheroplasts of the blue-green alga Anabaena variabilis. Contrary to the intact cells, the spheroplasts did not synthesize nucleic acids and pigments in the light. These components of the spheroplasts were decomposed in the light, and the remaining chlorophyll was incapable of luminescence. The rate of oxygen uptake increased upon the incubation of the spheroplasts in the light. Changes of the functions induced by lysozyme in the cells of A. variabilis are irreversible, contrary to those which are caused by the incubation in the darkness and can be restored if the cells are transferred into the light.

Chlorophyll↗

PubMedDate not supplied

[Change in the ATP content in the cells of Anabaena variabilis].

The content of ATP in the cells of Anabaena variabilis does not change during one day in the darkness as compared to that in the cells grown in the light, this suggesting the endogenous energy reserve of the cell. The level of ATP gradually decreases when the cells are incubated in the darkness during 25 days, but does not reach zero. The content of ATP increases for a short period in the light in the cells that have been incubated in the darkness during several days (up to 7 days). On the contrary, the level of ATP increases to a small extent and then falls in the cells grown in the light. These differences suggest disturbed coupling of the synthesis and utilization of ATP in the cells grown in the darkness. The content of ATP increases again in the darkness, confirming that the alga is capable of synthesizing ATP in the darkness.

Adenosine Triphosphate↗

PubMedDate not supplied

[Characteristics of oxygen metabolism in the obligate phototrophic blue-green alga Anabaena variabilis in darkness].

The rate of endogenous respiration of the cells of Anabaena variabilis in the mineral medium in the darkness decreases gradually during 30 to 40 days and is then maintained at a low level. The rate of oxygen uptake was the same in the cells grown in aerobic and anaerobic conditions in the darkness. The ability for oxygen evolution in the light is maintained in the anaerobic cells for a longer time, and the biomass yield and the content of phycocyanin in the cells decrease at a lower rate in anaerobic conditions. Therefore, under certain conditions of the medium, the processes related to the cell survival in the darkness are directed to preserve the photosynthesizing apparatus, and oxygen is a factor accelerating the death while anaerobic conditions delay destruction of the cells in the darkness.

Aerobiosis↗

PubMedDate not supplied

[Characteristics of different growth stages of the blue-green alga Anacystis nidulans (Synechococcus)].

The rate of growth of the blue-green alga Anacystis nidulans is highest during the first 5--8 days but the number of the cells increases up to 30 days when the stationary phase takes place (30--60 days). The content of chlorophyll is almost constant during the first 20 days of growth while the content of phycocyanin increases; then the content of the both pigments decreases. The rate of O2 evolution and the rate of electron transport to ferricyanide decrease exponentionally during the first 10 days of growth. The rate of endogenous respiration and the rate of O2 absorption, induced by methylviologen in the light in the presence of DCMU decrease more slowly. At the same time, the rate of O2 absorption in the presence of methylviologen without DCMU and the rate of TTC reduction in the darkness increase and later decrease. The rate of TTC reduction in the light increases up to 30--40 days and then decreases. The rate of the cell death in the darkness decreases when the age of the "light" culture is 50 days. Addition to the medium of its main components does not increase the rate of growth of the culture after 10 days of its growth. Addition of CaCl2, glucose, and asparagic acid increases the rate of growth of the 3-day-old culture. Addition of phosphorus inhibits growth. Argon favours growth of the culture. The cells are rapidly discoloured in conditions of hampered gas exchange; they die rapidly also in the presence of DCMU, methylviologen, and KCN.

Chlorophyll↗

PubMedDate not supplied

[Metabolism and destruction of the blue-green alga Anabaena variablis in the dark].

Anabaena variabilis remains viable in the dark, which is accompanied with intensive utilization of the reserve polysaccharide by the cells. The content of protein and RNA increases in the cells and incomplete cellular division occurs at the beginning of the culture incubation in the dark. Destruction of the intracellular protein and RNA begins before all the reserve polysaccharide has been utilized. During the whole period of incubation of the alga in the dark, structural integrity of the cells is preserved though the intracellular components are destroyed. Further incubation in the dark results in a complete lysis of the culture. Destruction in the intact cells does not involve DNA whose total content in the culture decreases only by the beginning of lytic processes.

Cell Division↗

PubMedDate not supplied

[Photodestruction of the blue-green alga Anabaena variablis].

The effect of light on the cells was studied with the obligate phototrophic blue-green alga Anabaena variabilis after its incubation in the dark. Incubation of the alga in the dark during two weeks was not essential for the cell reproduction systems in the light. Incubation in the dark during 3-4 weeks caused damages in the systems which were however reversible and repaired in the light. Longer incubation of the cells in the dark results in irreversible damages of the systems protecting them from photooxidation which may be the main factor preventing growth of the cells in the light.

Carotenoids↗

PubMedDate not supplied

[Age changes in cells in Streptococcus diacetilactis cultures].

The activity of metabolism changed in the cultures of Streptococcus diacetilactis, strain Bogdan, with aging. The number of viable cells decreased as well as the ability to evolve oxygen, to produce C-4 compounds, and to react to pH changes by liberating acids upon alkalifying or neutral products upon acidifying. After the culture had been grown during 72 hours, 2,3-butyleneglycol was found in the cultural broth, and the number of viable cells was low. As was revealed by electron microscopy, the cells were intact during 48 hours; they started to disintegrate by 72 hours. After 120 hours all cells were disintegrated. First, the cells produced no more mesosomes, became less electron dense; then the cell wall was decomposed and the contents of the cell poured through disruptions in the cytoplasmic membrane.

Butylene Glycols↗