Specific Features of the Formation of a Halo during Pathogenesis as a Response of Cereal Epidermal Cells to Penetration of Powdery Mildew Causative Agents

A cytophysiological study was carried out of the functional status of a halo as a response of the host plant to contact with a powdery mildew pathogen. Interactions of the powdery mildew causative agents with barley, wheat, wheat–wheat-grass hybrids, wheat-aegilops lines, and aegilops with different genotypic resistance lead to the expression of haloes during pathogens, which are induced by infection pegs of the primary growth tubes, appressoria, and hyphal lobes. Haloes are visualized using cytochemical reactions to proteins and scanning electron microscopy. The observed differences in the size of haloes and intensity of their staining (uniform or zonal) are related, to a great extent, to individual reactions of the plant cell at the penetration site and, to a lesser extent, to the level of genotypic resistance. An analysis of electron microscopy and cytochemistry studies suggests that the halo as a physiologically active zone is localized at the level of the plant cell plasmalemma. Active taxis of the cell organelles to the site of infection during the formation of a halo suggests that some kind of informational signals to changes in the cell metabolism are spread from the halo zone, which lead to compatible or incompatible interactions.     

Characteristics of destructive-regenerative processes in the kidneys of albino rats in conditions of necronephrosis caused by corrosive sublimate

Study of serial semi-thin (0.5 micron) metacrylate and paraffinic (8 microns) of rat kidney sections 6, 12, 24 and 48 h after subcutaneous injection of mercury bichloride at a dose of 0.6 mg/100 g bw has revealed that injury to different parts of the canalicular nephron is of heterogeneous character. The proximal part of the nephron demonstrates both complete and partial necrosis of nephrocyte cytoplasm. The distal parts of the nephron and collecting tubules are characterized by partial necrosis of the apical cytoplasm. Within the period between 12 and 24 h after the mercury bichloride injection, intracellular reparative processes are observed, in addition to destruction, in partially damaged but viable nephrocytes, which is confirmed by the enlargement of the nucleolic size. Regeneration of the tubular epithelium due to cellular restoration was unmarked 24 h after the mercury bichloride injection.     

Fractionation of eukaryotic DNA in a pulsed electrical field. II. Discrete DNA fragments and level of structural organization of chromatin]

The data presented confirm the possibility of enzymatic formation of discrete DNA-fragments appearing during fractionation of nuclear DNA by FIGE. Teniposide-dependent pattern of DNA-fragments as well as occurrence of protein-linked DNA breaks suggest that discrete cleavage of intact nuclear DNA is modulated by DNA topoisomerase II. The possible relationship between discrete DNA-fragments and the higher order chromatin folding are discussed.     

Stability of Ion Flow and Role of Boundary Conditions in a Simplified Model of the E × B Plasma Accelerator with a Uniform Electron Mobility

Plasma Physics Reports - Resistive oscillations of axial plasma with ionization effects are analyzed in configuration similar to the Hall effect thrusters. From analysis of stationary equations we...     

Fatty acid composition of Escherichia coli cells and their viability in air

Experiments on E. coli used as a model have revealed that fatty-acid composition is one of the characteristics which determine the viability of bacteria in the air. The viability of microbial cells in the air has been shown to increase with the increase of the pool of cyclopropane acids and the palmitic acid/palmitoleic acid ratio in the cells, irrespective of their genotype and the phase of their growth.     

Biochemical characteristics of the Ca2+ pumping ATPase in the peribacteroid membrane from broad bean root nodules

Ca²⁺-ATPase in the peribacteroid membrane (PBM) of symbiosomes isolated from Vicia faba root nodules was characterized in terms of its hydrolytic and transport activities. Both activities were found to be pH-dependent and exhibit pH optimum at pH 7.0. Translocation of Ca²⁺ through the PBM by the Ca²⁺-ATPase was shown to be fueled by ATP and other nucleotide triphosphates in the following order: ATP?>?ITP???GTP???UTP???CTP, the K _m of the enzyme for MgATP being about 100 μM. Ca-dependent ITP-hydrolytic activity of symbiosomes was investigated in the presence of the Ca-EGTA buffer system and showed the affinity of PBM Ca²⁺-ATPase for Ca²⁺ of about 0.1 μM. The transport activity of Ca²⁺-ATPase was inhibited by erythrosin B as well as orthovanadate, but markedly stimulated by calmodulin from bovine brain. These results allowed us to conclude that this enzyme belongs to IIB-type Ca²⁺-ATPases which are present in other plant membranes.     

Changes in the nucleoli of epithelial cells of the kidney tubules in mercuric chloride-induced experimental kidney tubular necrosis

Electron-microscopic studies of epithelial cells of uric tubules in white rat kidneys after i.m. injections of mercury dichloride (0.4 mg/100 of body weight) given every 24, 48 and 72 hours showed the affected epithelial cells to have nonspecific changes in tubule ultrastructure, i.e. dissociation and segregation of tubule components as well as degranulation, fragmentation and hypertrophy. The dissociation of nucleolus components is followed by the damage of an essential part of cell mitochondrial apparatus and becomes irreversible. In some damaged cells degranulation is accompanied by the nucleolus decay into separate solid fragments formed of fibrous tissue. The enlargement of nucleolus fragments in the absence of proribosomes speaks in favour of the depression of proribosome formation process while the ability to synthesize p-RNA in comparatively slight.     

Residual electron momentum and energy in a gas ionized by a short high-power laser pulse

A study is made of the nonadiabatic dynamics of photoelectrons produced during interaction of an elliptically polarized, high-power laser pulse with a gas. Expressions for the so-called residual momentum and energy of the electrons (i.e., the mean electron momentum and energy after the passage of the pulse through the gas) are derived. The residual electron momentum and energy are investigated analytically as functions of the gas and laser parameters. A relationship is established between the residual energy and the electron temperature tensor.     

Сa2+-ATPase of the Symbiosome Membrane from Broad Bean Root Nodules: Novel Results Supporting the Mechanism of Transmembrane Translocation of Ca2+

Russian Journal of Plant Physiology - On the preparations of symbiosomes isolated from broad bean (Vicia faba L.) root nodules, the transport activity of symbiosome membrane (SM) Ca2+-ATPase...