卷 55, 编号 5 (2019)

The current data on the generation and neutralization of reactive oxygen species in various compartments of plant cells are summarized. The role of antioxidants (AOs) in the protection of macromolecules and cellular structures from oxidative damage is considered. Special attention is paid to the participation of AOs in redox signaling and the regulation of cellular functions. The cross-link between the functioning of the AO system (AOS) and the nonspecific plant resistance to stressors is analyzed. The regulation of AOS in plants under the action of exogenous AOs, signal mediators, phytohormones, and other physiologically active substances, as well as by transgenesis, is considered.

Campylobacter spp. are the principal bacteria causing human gastroenteritis globally. Recently, several species of Campylobacter other than C. jejuni and C. coli have been identified. These emerging species have been associated with undiagnosed intestinal infectious diseases, although their clinical importance has not been determined yet. In order to establish the implication of the emerging bacterial species in human gastroenteritis, several epidemiological studies have been performed, where molecular typing methods have played a central role. This review provides an overview of the most used molecular typing tools used to characterized Campylobacter species.

An intracellular serine protease designated ISPr from newly isolated salt-tolerant Bacillus sp. LCB10 was expressed in Escherichia coli. The isp gene was cloned into pET30a vector and expressed in E. coli BL21 (DE3). After purification, the molecular mass of ISPr was estimated to be 35 kDa by SDS-PAGE and the specific activity was 384 U/mg. The protease showed optimal activity at 40°C and pH 10.0. ISPr was active and stable in wide range of alkaline pH. ISPr activity increased 1.8-fold in the presence of Mn²⁺ and was completely inhibited by PMSF. The enzyme exhibited high NaCl tolerance. The protease had a stable activity in the presence of 1–5% NaCl and retained 86% activity in the presence 7% NaCl, thus, this enzyme would have great potential in industry.

KT2 is a cationic antimicrobial peptide belonging to Crocodylus siamensis leucrocin I analogs. The mode of action of this compound taken at lethal concentration includes translocation into bacterial cells where binding to DNA is presumed to occur. However, the effects of KT2 on bacterial membrane have not been completely elucidated to date. In this study, a LIVE/DEAD staining technique was used to estimate the appropriate time of peptide-bacteria interaction. The results indicated more than 90% of Escherichia coli population was killed at density of ∼5 × 10⁸ CFU/mL within 30 min after treatment with KT2 at MIC and 10 × MIC. The effects of KT2 on bacterial cells were investigated by the atomic force microscopy (AFM). At near MICs, the peptide induced heavy indentation of the bacterial surface as well as cellular collapse. Conversely, at concentrations of several times the MIC the potential to kill bacteria was greatly increased as judged by the induction of multiple membrane buds on the cell surface. Therefore, the collected results indicate that KT2 can cause different effects on bacterial surface which are positively correlated in magnitude and severity with peptide concentration via membranolytic effects.

Two methods for the synthesis of hybrid organic-inorganic nanocomplexes comprising chymotrypsin and silver nanoparticles have been developed based on the chemical reduction of silver nitrate by sodium borohydride. In the first method, the enzyme is added to the reaction mixture simultaneously with other reagents. In the second method, it is added to the reaction mixture at certain intervals after the start of the reduction reaction. Chymotrypsin immobilized on nanocomplexes stabilizes silver nanoparticles. As compared to the native enzyme, the immobilized enzyme prepared by the both methods exhibits an increased proteolytic activity in acidic and strongly alkaline media. At the same time, chymotrypsin immobilized on silver nanoparticles by the second method exhibits the highest level of proteolytic activity.

Electrophoretic, homogeneous, highly purified preparations of various isoforms of the immunodominant antigen V (LcrV protein) of Yersinia pestis have been obtained via chromatographic purification. A significant similarity in the chromatographic profiles of the LcrV antigen isoforms of different strains with tryptophan (W113) and glutamic acid (E113) residues at position 113, which differed from the isoform profile containing glycine residue LcrV (G113), has been recorded. The latter is characterized by the highest antigenic and protective activity as compared with other protein isoforms. This isoform almost completely protected the immunized group of animals and had the greatest ability to induce the production of antibodies, the titers of which reached 1 : 250 000.

The placement of pea plants (Pisum sativum L.) under flooding conditions led to an increase in lactate dehydrogenase (EC 1.1.1.27) activity in the roots. The enzyme was purified to an electrophoretic homogeneous state by a multistage purification method including ammonium sulfate fractionation, ion exchange chromatography on DEAE-Sephacel, and gel chromatography on Sephadex G-200. The degree of purification was 43.4, the yield was 2.5%, and the specific activity was 80.5 U/mg protein. Its physicochemical properties were studied: the molecular weight of the native lactate dehydrogenase molecule was 138 kDa. The molecular weight of the subunits was determined by PAGE by electrophoresis in the presence of DDS-Na. Its value was 34 kDa, which indicates that the enzyme is a homotetramer. The kinetic and regulatory properties of the enzyme and the values ​​of the Michaelis constants were established. he effect of the concentration of hydrogen ions and temperature on direct and reverse reactions catalyzed by it was obtained. It was determined that lactate dehydrogenase inhibited ATP.

The effect of the nitrogen source (sodium nitrate and soybean meal) on the growth, pathogenicity, and lipid composition of mycelium of Stagonospora cirsii Davis VIZR 1.41, a potential mycoherbicide against Canada thistle (Cirsium arvens (L.) Scop.), was studied. The fungus grew significantly (two times) faster on sucrose-soybean meal medium (SSM) than on modified Czapek medium (CM). The fungal mycelium during the exponential growth phase demonstrated the maximal pathogenicity level on the third day on SSM and on the sixth day on CM. Canada thistle leaf tissues were more susceptible (25% higher development of necrotic lesion) to mycelium obtained on SSM than to mycelium obtained on CM. The nitrogen source strongly affected the lipid composition of S. cirsii mycelium. In S. cirsii mycelium obtained on SSM, the total lipid content was 1.7 times lower; the ratio of nonpolar lipids to polar lipids was three times lower than that for fungal mycelium grown on CM. Considerable differences were found in the composition of nonpolar (sterols and fatty acid) and polar (sphingolipids) lipids with respect to the nitrogen source in the culture medium. The higher contents of sterols, free fatty acids, and some glycoceramides in the mycelium of S. cirsii obtained on SSM may be related to its higher pathogenicity level and can serve as a marker of mycoherbicide quality.