Method of isolating conditionally-pathogenic Gram-negative microorganisms, agents of intrahospital infections, from air

The possibility of detecting Pseudomonas aeruginosa and other Gram-negative bacteria in the air of the burn department at the Institute of Surgery was studied. The investigation of large volumes of air (0.5-1 m3) in the wards and the corridor with the use of a new bacteriological aerosol sampler, model IIAB-5, resulted in the detection of Pseudomonas aeruginosa. Besides, in a number of other rooms Klebsiella, Proteus, Citrobacter and Enterobacter were detected in the air. The possibility of the spread of Gram-negative opportunistic bacteria through the air in hospital conditions is discussed.     

Taxonomic identification of gram-negative nonfermenting microorganisms in environmental research

The scheme for the identification of Gram-negative nonfermenting microorganisms is proposed. The scheme comprises the most important key signs, such as the cytochrome oxidase reaction determined by the method of Gaby and Hadley, the oxidation/fermentation test, maltose oxidation and motility, as well as additional key signs, among them gelatinase activity, the oxidation of 10% lactose, nitratase activity with the liberation of free nitrogen, the utilization of the sources of carbon and energy (glucose and sodium acetate) in limited media containing ammonium salts and nitrates as the sources of nitrogen. Additional tests for the identification of nonfermenting microorganisms similar in their main key signs are also recommended.     

Elemental distribution in striated muscle and the effects of hypertonicity: Electron probe analysis of cryo sections

A method of rapid freezing in supercooled Freon 22 (monochlorodifluoromethane) followed by cryoultramicrotomy is described and shown to yield ultrathin sections in which both the cellular ultrastructure and the distribution of diffusible ions across the cell membrane are preserved and intracellular compartmentalization of diffusabler ions can be quantitated. Quantitative electron probe analysis (Shuman, H., A.V. Somlyo, and A.P. Somlyo. 1976. Ultramicros. 1:317-339.) of freeze-dried ultrathin cryto sections was found to provide a valid measure of the composition of cells and cellular organelles and was used to determine the ionic composition of the in situ terminal cisternae of the sarcoplasmic reticulum (SR), the distribution of CI in skeletal muscle, and the effects of hypertonic solutions on the subcellular composition if striated muscle. There was no evidence of sequestered CI in the terminal cisternae of resting muscles, although calcium (66mmol/kg dry wt +/- 4.6 SE) was detected. The values of [C1](i) determined with small (50-100 nm) diameter probes over cytoplasm excluding organelles over nuclei or terminal cisternae were not significantly different. Mitochondria partially excluded C1, with a cytoplasmic/ mitochondrial Ci ratio of 2.4 +/- 0.88 SD. The elemental concentrations (mmol/kg dry wt +/- SD) of muscle fibers measured with 0.5-9-μm diameter electron probes in normal frog striated muscle were: P, 302 +/- 4.3; S, 189 +/- 2.9;C1, 24 +/- 1.1;K, 404 +/- 4.3, and Mg, 39 +/- 2.1. It is concluded that: (a) in normal muscle the "excess CI" measured with previous bulk chemical analyses and flux studies is not compartmentalized in the SR or in other cellular organelles, and (b) the cytoplasmic C1 in low [K](0) solutions exceeds that predicted by a passive electrochemical distribution. Hypertonic 2.2 X NaCl, 2.5 X sucrose, or 2.2 X Na isethionate produced: (a) swollen vacuoles, frequently paired, adjacent to the Z lines and containing significantly higher than cytoplasmic concentrations of Na and Cl or S (isethionate), but no detectable Ca, and (b) granules of Ca, Mg, and P = approximately (6 Ca + 1 Mg)/6P in the longitudinal SR. It is concluded that hypertonicity produces compartmentalized domains of extracellular solutes within the muscle fibers and translocates Ca into the longitudinal tubules.     

The medium for determining the gelatinase activity of non-fermenting gram-negative microorganisms

To determine the gelatinase activity of Gram-negative nonfermenting microorganisms, a double-layer medium containing 2% of agar in the lower layer and 10-20% of gelatin in the upper layer has been developed. The medium ensures free access of atmospheric oxygen, possibility of rapid (24-42 h) determination of gelatinase activity at 22-25 degrees C, efficacy of the test. simultaneous determination of gelatin hydrolysis by 8-12 strains in one dish.     

Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

Subcellular Localization of Oxaloacetate Decarboxylase and Its Isolation from Maize Leaves

The activity of oxaloacetate decarboxylase was revealed in leaves of a C₄ plant, maize (Zea mays L.). This activity was unrelated to decarboxylase activities of other enzymes, e.g., NAD-malate dehydrogenase (EC 1.1.1.38) or NADP-malate dehydrogenase (EC 1.1.1.40), and was located in chloroplasts (83.1%). Using a four-step purification procedure, an electrophoretically pure enzyme preparation of oxaloacetate decarboxylase was obtained from maize leaves. The specific activity of the enzyme was 3.150 EU/mg protein, the factor of purification was 40.4, and the yield was 11.0%. The enzyme exhibited Michaelis–Menten kinetics with K _m for oxaloacetate 30 ± 5 M and pH optimum 7.1 ± 0.5. The metabolite-mediated regulation of oxaloacetate decarboxylase activity has been investigated. It is found that sodium chloride (1.0 mM) activates the enzyme, whereas ATP inhibits the enzyme activity.     

Investigation of the possibility of exceeding the Greenwald density limit during ECRH in T-10

In T-10 experiments, attempts were made to significantly exceed the Greenwald limit $\bar n_{Gr} $ during high-power (P _ab=750 kW) electron-cyclotron resonance heating (ECRH) and gas puffing. Formally, the density limit $(\bar n_e )_{\lim } $ exceeding the Greenwald limit $({{(\bar n_e )_{\lim } } \mathord{\left/ {\vphantom {{(\bar n_e )_{\lim } } {\bar n_{Gr} }}} \right. \kern-0em} {\bar n_{Gr} }} = 1.8)$ was achieved for q _L=8.2. However, as q _L decreased, the ratio ${{(\bar n_e )_{\lim } } \mathord{\left/ {\vphantom {{(\bar n_e )_{\lim } } {\bar n_{Gr} }}} \right. \kern-0em} {\bar n_{Gr} }}$ also decreased, approaching unity at q _L≈3. It was suggested that the “current radius” (i.e., the radius of the magnetic surface enclosing the bulk of the plasma current I _p), rather than the limiter radius, was the parameter governing the value of $(\bar n_e )_{\lim } $ . In the ECRH experiments, no substantial degradation of plasma confinement was observed up to $\bar n_e \sim 0.9(\bar n_e )_{\lim } $ regardless of the ratio ${{(\bar n_e )_{\lim } } \mathord{\left/ {\vphantom {{(\bar n_e )_{\lim } } {\bar n_{Gr} }}} \right. \kern-0em} {\bar n_{Gr} }}$ . In different scenarios of the density growth up to $(\bar n_e )_{\lim } $ , two types of disruptions related to the density limit were observed.     

Phylogenetic analysis of a microbial community involved in anaerobic oxidation of ammonium nitrogen

The phylogenetic diversity of a microbial community involved in anaerobic oxidation of ammonium nitrogen in the DEAMOX process was studied. Analysis of clone libraries containing 16S rRNA gene inserts of Bacteria, (including Planctomycetes) and Archaea revealed the presence of nucleotide sequences of the microorganisms involved in the main reactions of the carbon, nitrogen, and sulfur cycles, including nitrifying, denitrifying, and ANAMMOX bacteria. In the bacterial clone library, 16S rRNA gene sequences of representatives of the phyla Proteobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Verrucomicrobia, Lentisphaerae, Spirochaetales, and Planctomycetes, as well as of some new groups, were detected. In the archaeal clone library, nucleotide sequences of methanogens belonging to the orders Methanomicrobiales, Methanobacteriales, and Methanosarcinales were found. It is possible that both ANAMMOX bacteria and bacteria of the genus Nitrosomonas are involved in anaerobic ammonium oxidation in the DEAMOX reactor. Many sequences were similar to those from the clone libraries obtained previously from the ANAMMOX community of marine sediments. It is also probable that the DEAMOX reactions occur in natural ecosystems (in marine and freshwater sediments and the oceanic water column), thereby providing for the coupling of the nitrogen and sulfur cycles.     

L1 (LINE-1) retrotransposable elements provide a "fossil" record of the phylogenetic history of murid rodents

The single most difficult problem in phylogenetic analysis is deciding whether a shared taxonomic character is due to common ancestry or one that appeared independently due to convergence, parallelism, or reversion to an ancestral state. Mammalian L1 retrotransposons undergo periodic amplifications in which multiple copies of the elements are interspersed in the genome. Because these elements apparently are transmitted only by inheritance and are retained in the genome, a shared L1 amplification event can only be an inherited ancestral character. We propose that L1 amplification events can be an excellent tool for analyzing mammalian evolution and demonstrate here how we addressed several refractory problems in rodent systematics using L1 DNA as a taxonomic character.