Problems related to the interpretation of data obtained during testing of potential geroprotectors in cytogerontological experiments are considered. It is emphasized that such compounds/physical factors should influence on the processes leading to the age-related increase of death probability of multicellular organisms (primarily — of man, in whose aging gerontologists are mainly interested). However, in the authors’ opinion, compounds which cure age-related diseases unlikely could be classified as geroprotectors. It is noted, that, in the model systems using cultured cells, researchers, as a rule, evaluate their viability criteria of which, to a great extent, depend on the aging theory shared by the experimenters. Besides, it is very important what cells are used in the studies — normal or transformed cells of multicellular organisms, unicellular eukaryotic or prokaryotic organisms, etc. In particular, biologically active compounds which decrease the viability of cultured cancer cells may increase the life span of experimental animals and humans, as well as compounds which increase the viability of normal cultured cells. Various problems with interpretation of data obtained with the Hayflick model, the stationary phase aging model, and the cell kinetics model, as well as in experiments on evaluation of cell colony-forming efficiency are analyzed. The approaches discussed are illustrated on the example of the results from gerontological investigations of a famous mTOR inhibitor, rapamycin. It is assumed that factors retarding the stationary phase aging (chronological aging) of cultured cells are, apparently, the most promising geroprotectors although the specific mechanisms of their action may vary considerably.

Plum pox virus (PPV, genus Potyvirus, family Potyviridae) is considered to be the most detrimental viral pathogen of stone fruit crops (Prunus spp.). The strain Winona (PPV-W) is the most variable strain of the nine recognized strains of the virus and is one of the most common in European Russia. Six new PPV-W isolates were first found in decorative green plantings of the city of Moscow (Kp2U, Avang, Pulk, Pulk-1), also in the Taldom district of the Moscow region (Karm) and in the Kovrov district of the Vladimir region (Vlad-4) on wild plums Prunus domestica. Analysis of the 3’-terminal genome segment of the novel isolates confirmed the high level of the PPV-W intra-strain diversity. Study of their relationship with other PPV-W isolates using the phylogenetic analysis of the coat protein gene’s sequences revealed no geographical clustering of the Russian PPV-W isolates. The aphid and seed transmission of the PPV-W was also investigated. Inoculation of Nicotiana benthamiana plants by the hop aphid Phorodon humuli from the plums, infected with the isolates Avang and Pulk, and by the thistle aphid Brachycaudus cardui from the plum, infected with the isolate Kp2U, was shown to result in the systemic infection of tobacco plants thus indicating the possibility of the natural PPV-W transmission by both aphid species. No evidence of the PPV-W seed transmission has been obtained.

Grapevine leafroll is one of the most widespread and harmful diseases of grapevine. To investigate the occurrence of grapevine leafroll-associated viruses-1 и 3, the survey of vineyards has been conducted in 2015 in six regions of Crimea. Total of 689 leaf samples with virus symptoms were collected. GLRaV-1 and GLRaV-3 were analysed by RT-PCR with the specific primers, followed by sequencing of the PCR products. GLRaV-1 and GLRaV-3 were detected in 34 (4.9%) and 37 (5.4%) of the samples, respectively. Vineyards in Simferopol, Bahchisaray and Sevastopol regions were found to be free of GLRaV-1 and GLRaV-3.

Endophytic fungi are found in natural populations of giant fescue (Festuca gigantea (L.) Vill.) and bearded wheatgrass (Elymus caninus (L.) L.) on the territory of S.N. Skadovsky Zvenigorod Biological Station (Moscow Region). Endophytes were isolated from infected seeds of both grass species. All isolates were identified as Epichloё festucae Leuchtm., Schardl & M.R. Siegel.

It is well-known that one of the key factors which affect the sexual reproduction of diatoms is the cell concentration in cross-cultures. The concentration of pheromones which probably initiate gametogenesis in the mixture of cells of opposite sexes, depends on the culture density. The influence of the cell concentration on the sexual reproduction has been studied in the experiments with taxonomically important marine diatom Ardissonea crystallina (C. Agardh) Grunow. Several clones have been isolated from samples taken near Sevastopol (the Black Sea). The cell concentration which is most favorable for the species reproduction has been estimated. Low initial density may also increase the time required to start heterothallic sexual reproduction. The optimum cell concentration which is most favorable for the species reproduction has been calculated. Bigger volume of the medium allowed reproduction at higher cell concentration. If the initial concentration of cells was greater than optimal density, the reproduction often did not occur, probably due to cell metabolism products accumulated in the culture.

We studied the possibility of using a broadly neutralizing anti-influenza A antibody as a module for the development of different protein constructs for diagnostics. For this purpose we constructed two recombinant proteins — an antibody Fab-fragment and Fab-mCherry, which is a hybrid of the Fab-fragment and a fluorescent protein mCherry. Both proteins were expressed in Escherichia coli cells and purified in a functionally active state from cultivation medium. The antibody Fab-fragment was shown to bind all eleven tested strains of the influenza A H1N1 and H3N2 subtypes. The stronger binding was observed for the group I hemagglutinins that correlates with the immunochemical profile of the parental antibody. Comparison of the dissociation constants of complexes of the antibody Fab-fragment and Fab-mCherry with A(H1N1)/Solomon Islands/03/06 virus particles demonstrated that the attachment of mCherry protein did not interfere with the antigen-binding properties of the antibody Fab-fragment.

Footprinting is one of the simplest and most accurate approaches to investigate structure and interaction of biopolymers. It is based on the accessibility of intra- and intermolecular contacts for external damaging agents. In the method, one end of the polymer is labeled, and then the sample is incubated in cutting medium. Length distribution of the products allows to reveal the accessibility of different regions of polymer in the corresponding conditions. In DNA footprinting various enzymes and chemical reagents can be used. The highest temporal and spatial resolution without sequence specificity can be obtained with hydroxyl radicals. In this paper we present a new modification of the experimental approach using fluorescent-labeled DNA fragments and up-to-date methods of quantitative analysis, which can considerably increase its applicability.

An experimental setup for study of imm obilized molecules and their complexes by fluorescence microscopy with sensitivity at the single fluorophore level was developed. The installation records fluorescence images of immobilized molecules in two spectral ranges simultaneously, allowing analysis based on the Förster resonance energy transfer effect. The fluorescence excitation is caused by evanescent light wave formed by the total internal reflection technique, and registration of signal with a highly sensitive detection system allows conducting measurements with a temporal resolution of about 100 ms. The glass surface modification protocol was developed for immobilization of nucleosomes via the high-affinity streptavidin-biotin interactions. To ensure immobilization, one of the DNA ends of fluorescently labelled nucleosomal DNA was biotinylated. The algorithm of image processing for analysis of structural rearrangements in single nucleosomes was developed. Fluorescence microscopy of single immobilized molecules and their complexes allows the analysis of nucleosome structural dynamics during transcription and its interaction with various nuclear proteins.

The growth and biomass accumulation of three microalgal strains of Desmodesmus (Scenedesmaceae, Chlorophyceae), 1Рm66В, 2Cl66E, 3Dp86Е-1, isolated from White Sea benthic invertebrates were studied under conditions of batch culture in different standard (BG-11, Prat, Goldberg, Gromov, Tamiya, artificial sea water) and modified media. Culture condition and biomass accumulation were recorded as well as the uptake of nitrate and phosphate. Vigorous growth of the microalgae brought about a significant alkalization of the culture medium to pH 10. The most significant biomass accumulation was recorded in BG-11 (the complete medium and one with addition of artificial sea water), Tamiya and Prat media. Addition of the sea water did not affect the growth of Desmodesmus sp. in the nitrate-containing media although that maintained the growth of the microalgae in the nitrogen-lacking media without cell aggregation. The obtained results suggest the suitability of BG-11 medium for isolation and cultivation of both symbiotic and free-living microalgae. The Prat medium is more suitable for maintaining the microalgal strains in collection.

The method of synthesis of fluorescently labeled DNA allowing assembly of mononucleosomes with 40 bp linkers was developed. Cy3 and Cy5 labels were introduced in the linkers at distances of 10 bp before the first and 15 bp after the last nucleotide of the nucleosome positioning DNA sequence, respectively. In the absence of histone H1.5 fluorescence microscopy of single complexes revealed the presence of two equally probable states of nucleosomes, differing in the conformation of linkers: open one with the energy transfer efficiency E between the labels being equal to 0.06 and closed one with E = 0.37. Binding of histone H1.5 with nucleosomes occurs in nanomolar range of concentrations, and the rate of complex formation is significantly higher than the dissociation rate. In the complexes, significant convergence of DNA linkers (E = 0.73) takes place, and their conformation in the region of labels becomes more uniform. Designed nucleosomal constructs are highly sensitive fluorescent sensors for the analysis of structural rearrangements of linkers and in combination with microscopy of single complexes allow studying the structure of complexes of nucleosomes with different chromatin architectural proteins.