Superoxide dismutase activity of human plasma; the effect of Cu2+-complex compounds

The superoxide-dismutase (EC 1.15.1.1) activity was revealed in blood plasma after its successive treatment with alcohol, chloroform and one- or two-substituted phosphate. Its value is the highest when treating plasma with KH2PO4. The boiling of the supernatant liquid obtained after addition of K2HPO4 leads to a complete loss of the activity. The treatment of plasma with KH2PO4 provides higher stability of the enzyme to thermal actions. The analysis of EPR-spectra has shown the presence of different complex compounds of copper ions in the supernatant liquid. Certain experiments with the use of aqueous solutions of CuCl2 and histidine have shown that Cu2+ inhibits the superoxide-dismutase activity in samples treated with KH2PO4 and increases it in samples treated with K2HPO4.     

The antitumor effect of magnetic nanodisks and DNA aptamer conjugates

Here we describe a method of forming large arrays (up to 10⁹ pieces) of free magnetic Ni-nanodisks 50 nm thick coated on both sides with layers of 5 nm thick Au. The antitumor effect of the magnetic nickel gold-coated nanodisks and DNA aptamer conjugates was evaluated in vivo and in vitro. Under the influence of rotating magnetic field, the studied nanodisks can cause the death of Ehrlich ascites carcinoma cells.     

The Decreased Cold-Resistance of Chilling-Sensitive Plants Is Related to Suppressed CO2 Assimilation in Leaves and Sugar Accumulation in Roots

Tomato (Lycopersicon esculentum L., cv. Sibirskii skorospelyi) and cucumber (Cucumis sativus L., cv. Konkurent) plants were grown in a soil culture in a greenhouse at an average daily temperature of 20°C and ambient illumination until the development of five and eight true leaves, respectively. During the subsequent three days, some plants were kept in a climatic chamber at 6°C in the light, whereas other plants remained in a greenhouse (control). The cold-resistance of cucumber leaves and roots, as assayed from the electrolyte leakage, was reduced after cold exposure stronger than cold-resistance of tomato organs. The ratio photosynthesis/dark respiration was lower in cucumber than in tomato leaves at all measurement temperatures. The concentrations of sugars (sucrose + glucose + fructose) increased in chilled tomato roots but decreased in cucumber roots. Cold exposure changed the activities of various invertase forms (soluble and insoluble acidic and alkaline invertases). The total invertase activity and the ratio of mono- to disaccharides increased. The lower cucumber cold-resistance is related to the higher sensitivity of its photosynthetic apparatus to chilling and, as a consequence, insufficient root supply with sugars.     

The detection of nonallelic to known genes of resistance to Tilletia caries (DC) Tul. in wheat strains from interspecific hybridization (Triticum aestivum x Aegilops cylindrica)

It was established by hybridological analysis that winter bread wheat lines 1/74-91, 3/36-91, 5/55-91 possess single dominant gene of resistance to bunt (Tilletia caries (DC) Tul.), but lines 8/2-91, 5/43-91, 4/11-91 and 8/16-91 have two independent dominant genes for this character. These genes originated from Aegilops cylindrica are not identical to Bt1-Bt17 genes and are unknown to date. The lines were obtained from crosses between winter bread wheat variety Odeskaya polukarlikovaya and Aegilops cylindrica.     

Biodiversity and monitoring of colorless filamentous bacteitrtn sulfide aquatic systems of North Caucasus region

Bacterial mats in sulfide aquatic systems of North Caucasus are basically composed by the species of genera Thiothrix and Sphaerotilus. Additionally, several non-filamentous sulfur-oxidizing bacteria were isolated from the mats and several minor 16S rRNA phylotypes were found in clone libraries from these mats. The minor components were affiliated with Proteobacteria, Chlorobia, Cyanobacteria and Firmicutes. Even in an individual mat population heterogeneity of Thiothrix spp. was revealed by analysis of 16S rRNA gene and RAPD-PCR. Five Thiothrix isolates were described as new species Thiothrix caldifontis sp. nov. and Thiothrix lacustris sp. nov. In the Thiothrix-Sphaerotilus type of bacterial mat the proportion of dominant organisms might be influenced by sulfide concentration in the spring water. The higher sulfide concentration (more than 10 mg/1) in the spring water is more favorable for the development of bacterial mats with dominant Thiothrix organisms than for Thiothrix-Sphaerotilus type of sulfur mat.     

Specific features of source-sink relations in alloplasmic hybrid of winter wheat with alien cytoplasm of goatgrass with emphasis on resistance to low temperature stress

We studied the influence of alien cytoplasm of spring goatgrass Aegilops ovata L. on some physiological parameters in winter wheat (Triticum aestivum L.), Mironovskaya 808, under normal conditions and in the case of modified source-sink relations. Measurements of relative rates of plant dry matter growth and its distribution among organs, CO₂ exchange (photosynthesis upon light saturation and dark respiration), content of sugars (sucrose + glucose + fructose) and their ratio in leaves, frost hardiness, and indices of membrane stability and damage of leaves by frost have shown that, on average, alloplasmic hybrid differed from the initial cultivar by almost all parameters. Reduced frost hardiness, increased index of leaf damage by frost, lowered leaf content of sugars, and reduced sucrose/(glucose + fructose) ratio in the alloplasmic hybrid were combined with higher roots/leaves ratio, relative rate of dry matter growth, and photosynthesis and respiration rates. The alloplasmic hybrid was more tolerant to decreased source strength in source-sink relations as compared to the initial cultivar.     

<Emphasis Type="Italic">Hoeflea siderophila</Emphasis> sp. nov., a new neutrophilic iron-oxidizing bacterium

A new representative of neutrophilic iron-oxidizing bacteria was isolated from the iron-containing sediments of the brackish low-temperature iron-rich spring of the Staraya Russa Resort (Novgorod region, Russia). The cells of strain Hf1 were thin, slightly curved rods, motile by means of a single polar flagellum. The bacterium reproduced by binary division and was capable of producing rosettes. Optimal growth was observed within the pH range of 6.2–8.5 (with an optimum at 7.5), at 9–38°C (with an optimum at 30°C), and in the salinity range of 0.1–8.5% NaCl (with an optimum at 1%). The organism was a facultative anaerobe. The strain was capable of mixotrophic and organoheterotrophic growth. Fe(II) oxidation occurred under anaerobic conditions via reduction of NO₃⁻ and N₂O, or under microaerobic conditions with oxygen as an electron acceptor. According to phylogenetic analysis based on the comparison of the 16S rRNA gene sequences, the strain was closest to the organotrophic marine bacterium Hoeflea phototrophica (98.5% similarity). The level of DNA-DNA homology with the type species of the genus Hoeflea was 19%. The DNA G + C base content was 57.5 mol %. According to its phenotypic and chemotaxonomic properties, as well as to the results of phylogenetic analysis, strain Hf1 was classified into the genus Hoeflea of the family Phyllobacteriaceae, order Rhizobiales of the phylum Alphaproteobacteria as a novel species, Hoeflea siderophila sp. nov. The type strain is Hf1^T (=DSM 21587 = VKM A7094). The GenBank accession number for the 16S rRNA gene sequences of strain Hf1^T is EU670237.     

Molecular phylogeny and taxonomy of colorless, filamentous sulfur bacteria of the genus Thiothrix

Comprehensive investigation combining molecular genetic techniques and comparative studies of morphological and physiological properties made it possible to resolve the disputed issue of the taxonomic status of the groups ??T. nivea?? and ??Eikelboom type 021N?? of the genus Thiothrix. The phylogenetic trees constructed on the basis of 16S rRNA and gyrB gene sequences demonstrated that members of the genus Thiothrix formed a cluster within the order Thiotrichales. According to the ??ribosomal?? tree, the cluster of the genus Thiothrix was divided into two main groups, I and II, corresponding to the groups ??T. nivea?? and ??Eikelboom type 021N??. The levels of similarity between the 16S rRNA gene sequences of Thiothrix species reached 88.9?C100%. On the contrary, in the ??gyrase?? tree, these species were not divided into ??T. nivea?? and ??Eikelboom type 021N?? groups. The levels of similarity between the amino acid sequences of the gyrB gene fragments of Thiothrix species varied from 74.5 to 99.2%. Importantly, members of the groups ??T. nivea?? and ??Eikelboom type 021N?? formed very similar 16S rRNA secondary structures in the variable region V3, where a 30-nucleotide deletion characteristic of all Thiothrix species was detected. Phenotypic analysis of the studied bacteria revealed some morphological and physiological properties shared by the groups ??T. nivea?? and ??Eikelboom type 021N??. The data obtained indicate that members of the groups ??T. nivea?? and ??Eikelboom type 021N?? are phenotypically and genetically heterogeneous species within the single monophyletic genus Thiothrix..