We have investigated the in vitro interaction of recombinant HP1 family protein paralogs (HP1a, HP1b and HP1c) and the 5’ untranslated regulatory regions of gypsy retrotransposon group in Drosophila melanogaster: gypsy, Springer, Tirant, ZAM, Rover and 17.6. With the use of competitive DNA, conditions for specific binding were obtained. It is shown that HP1 family proteins effectively bind to the 5’ untranslated region of retrotransposons, which have tandem repeats in their composition. It has been found that repeats are absolutely necessary for binding HP1a protein to the 5’ untranslated region of Tirant and ZAM mobile genetic elements. The absence of repeats in the case of ZAM element or their number less than two—in the case of Tirant makes such interaction impossible. Thus, the presence of tandem repeats in the 5’ untranslated region of retrotransposons of the gypsy group is an important tool for regulating their transposition by heterochromatin proteins.

Recently, a large number of papers have appeared that describe the successful use of various biologically active compounds (mitochondrial antioxidants, antidiabetic biguanides, mimetics of dietary restriction, etc.) as geroprotectors. However, in our opinion, in most cases, the positive results of such studies are determined by a “successful” selection of control objects. As such, animals with some abnormalities are often used, so that any favorable effect on the corresponding pathological processes leads to an increase in life span. Besides, control animals can be normal, i.e. wild type, but placed in some extreme conditions, which can be overcome precisely by certain biologically active compounds. Thus, treatment of pathologies is present, and not an effect on the fundamental processes of aging. There is a point of view, according to which the results of Clive McСay’s experiments, which have significantly prolonged the life of rats by limiting caloric intake, are determined, firstly, by the fact that the control animals were fed ad libitum (which is not at all characteristic of animals in the wild), and secondly, because the Fisher-344 rats used in experiments are short-lived. The above considerations seem to concern also gerontological experiments on cultured cells. In particular, we sometimes hear from our colleagues remarks about the model of “stationary phase aging” of cell cultures used in our laboratory due to the fact that most of the experiments are carried out on transformed rather than normal cells. However, this approach seems to us quite justified, because the phenomenon of “stationary phase”/chronological aging is common to a wide variety of cells, including bacteria, yeasts, cyanobacteria, mycoplasmas, animal and plant cells. Herewith cells with unlimited mitotic potential do not change either from experiment to experiment or during long-term cultivation both with and without (in the framework of stationary phase aging model) subcultivation, which cannot be said of normal diploid fibroblasts, whose telomeres are shortened with each division (and from the moment of seeding of the cells to their entering the stationary phase of growth they can divide up to 10 times!). We believe that to search for effective geroprotectors, which provide an impact on the fundamental mechanisms of aging, it is necessary to conduct studies on “maximally healthy” animals, or on “maximally stable” model systems.

Biotic interactions in a mixed culture of two microalgae species — Scenedesmus quadricauda (Turp.) Breb. and Monoraphidium arcuatum (Korsch.) Hind., used in bioassay in monocultures as test objects, were studied. The toxic effect of cell-free filtrates from different “ages” monoculture (2, 7, 10, 15, 21 and 28 days) S. quadricauda on the growth of the “young” test culture M. arcuatum and, conversely, the toxic effect of cell-free filtrates from the different “ages” (2, 7, 10, 15, 21 and 28 days) monoculture M. arcuatum on the growth of the “young” test culture S. quadricauda was evaluated. Simultaneously the toxicity of their own filtrates of different “ages” was monitored by a test culture of each species. The interactions of the species in the mixed culture can be regarded as negative, such as antagonistic, when both populations inhibit the growth of each other through metabolites and food resource competition, while the effect of S. quadricauda on M. arcuatum is much stronger. The main factor constraining the growth of monoculture S. quadricauda is the rapid depletion of the food resource from the medium, and not the inhibition of growth by its own metabolites. The depletion of the food resources from the medium in monoculture M. arcuatum occurs much later than in monoculture S. quadricauda. Metabolites of S. quadricauda cause a strong inhibitory effect on the growth of M. arcuatum, and the metabolites of M. arcuatum—a weak inhibitory effect on the growth of S. quadricauda. The filtrates of the “old” culture of S. quadricauda (21–28 days) cause the greatest inhibitory effect on the process of cell division of M. arcuatum. The filtrates of the “old” culture S. quadricauda (21–28 days) cause the greatest inhibitory effect on the process of cell division of M. arcuatum. A comparative analysis of the cell number dynamics of two species S. quadricauda and M. arcuatum in mono- and two-species algal cultures, as well as experiments with filtrates of these monocultures, showed that the interaction of species can be explained by the food resource competition and allelopathic interaction (exometabolite effect).

An express assay for primary screening of potato transformants by their GFP fluorescence intensities is developed. In comparison to the widely used methods of transgenic plant screening by real-time reverse transcription polymerase chain reaction (Real-Time RT-PCR) or Northern-blotting, the GFP fluorescence assay needs n o expensive reagents and takes less time. This approach may allow to carry out nondestructive screening of the primary transgenic regenerants which can be further grown and used. To prove this assay reliability, the expression of the modified GFP (hGFP) gene in the leaves of transgenic potato (cv. “Skoroplodny”) plants, determined by its mRNA accumulation, was compared to GFP fluorescence intensity in the micro-samples of aseptic plant leaves. The strong correlation between the results of these two methods is the evidence of positive dependence of GFP fluorescence intensity on the target mRNA content.

Results of a study of diatoms from Holocene peatbog sediments from Shemya Island (Aleutian Islands, USA) are presented. The column of peat sediments (385 cm depth) was investigated (the formation of peat sediments began more than 9500 years ago). Sixty-seven taxa of 31 genera, 17 families, 8 orders and 3 classes were identified. According to results of taxonomical and ecogeographical analyses most taxa belong to the order Naviculales and family Pinnulariaceae and are benthic organisms with cosmopolitan distribution. Forms with different quality of frustule preservation were revealed. Centric diatoms demonstrate the best preservation in sediment. Of special interest is the dissolution of frustules in water body with presummably low pH value. Pattern of species relative abundance dynamics were studied. Several zones with characteristic diatom complexes are distinguished. Analysis of distribution of diatoms in the column showed that, apparently, in the past there was a shallow oligotrophic reservoir with a relatively low pH. Water level changed occasionally, but trophic level did not change over the period of the reservoir existence.

A chromosome consisting of a nucleosome core, linker DNA and linker histone (LH), is an important structural element of chromatin and plays role in the replication and transcription regulation. There are two experimentally confirmed modes of LH binding to the nucleosome and linker DNA, which differ in their geometry: binding on-dyad and off-dyad. It was shown that the LH amino acid sequence influences the type of histone binding and the conformation of the chromatosome. However, the geometry of linker DNA bound with LH also changes. Thus, the mutual influence of these factors and the molecular basis determining the type of LH binding to nucleosomes remain unclear. In this study, we applied molecular modeling methods, including homology modeling, atom-atom interaction analysis and DNA deformation energy analysis to study the joint effect of the LH amino acid sequence and the DNA nucleotide sequence on the configuration of the chromatosome. We analyzed the known crystal and NMR structures of the chromatosome for the atom-atom interactions of LH and DNA as well as the energy of DNA deformation in these structures for various DNA sequences. For various LH H1 variants, the analysis was carried out using homology modeling methods. Sequence-dependent differences in the bending energy of the linker DNA for two different conformations of the chromatosome were found, and nucleotide sequences preferred for these structures were also proposed. As a result of the analysis, it was shown that the DNA nucleotide sequence along with the LH amino acid sequence influences the type of binding to the nucleosome. It is assumed that the contribution of the DNA nucleotide sequence and its geometry can be determinative in comparison with the LH amino acid sequence in some cases. Hypotheses for experimental verification have been formulated, according to which the type of LH binding can change with different DNA nucleotide sequences.

Nhp6A is a small non-histone chromosomal yeast protein that binds DNA nonspecifically. This protein is present at many promoters and transcribed regions of genome and is involved in regulation of transcription. Recently, Nhp6A was shown to participate in destabilization of the nucleosomal structure. This may explain its location in regulatory sites, but its function in the coding regions remains unknown. In the present work, in order to reveal the mechanism of action of Nhp6A, we have studied genes associated with the protein along the entire length, including the open reading frame. We have shown that Nhp6A predominantly binds to the coding regions of short GC-rich yeast genes. The observed interaction is not associated directly with the high content of GC-pairs in these DNA loci, so we can propose a specific regulatory mechanism involving Nhp6A for this group. Since a part of genes retain features of the ancestral bacterial genome, we suggest this group as an “ancient”. Presumably, this genomic distribution of Nhp6 is related to the mechanisms of regulation of gene transcription that appeared early in the course of evolution.

The purpose of this study was to identify the impact of different discriminative features of stimuli in P300 brain-computer interface paradigm on overall performance and evoked potentials. It has been shown, that stimuli sets with greater number of discriminative features yield better target selection accuracy. Target selection accuracy was significantly higher for stimuli that differ from each other by color, shape and semantics. Highest performance was achieved with stimuli set containing largest number of discriminative features, namely set of 9 different colored letters. This result is mainly due to higher mean P300 peak amplitude for stimuli sets that contain more discriminative features. The results of the study can be used for designing better user experience in brain-computer interfacing (BCI). Movement of stimuli presentation point and characteristics of this movement (linear or pseudorandom) didn’t have any impact on BCI performance. This result is promising for future BCI designs with rapid serial visual presentation, using mobile robots or augmented reality as stimuli presentation environment.