Sergey E. Peltek

Novosibirsk Free Electron Laser—Facility Description and Recent Experiments

The design and operational characteristics of the Novosibirsk free electron laser facility are described. Selected experiments in the terahertz range carried out recently at the user stations are surveyed in brief.

Molecular analysis of the benthos microbial community in Zavarzin thermal spring (Uzon Caldera, Kamchatka, Russia)

BackgroundGeothermal areas are of great interest for the study of microbial communities. The results of such investigations can be used in a variety of fields (ecology, microbiology, medicine) to answer fundamental questions, as well as those with practical benefits. Uzon caldera is located in the Uzon-Geyser depression that is situated in the centre of the Karym-Semyachin region of the East Kamchatka graben-synclinorium. The microbial communities of Zavarzin spring are well studied; however, its benthic microbial mat has not been previously described.ResultsPyrosequencing of the V3 region of the 16S rRNA gene was used to study the benthic microbial community of the Zavarzin thermal spring (Uzon Caldera, Kamchatka). The community is dominated by bacteria (>95% of all sequences), including thermophilic, chemoorganotrophic Caldiserica (33.0%) and Dictyoglomi (24.8%). The benthic community and the previously examined planktonic community of Zavarzin spring have qualitatively similar, but quantitatively different, compositions.ConclusionsIn this study, we performed a metagenomic analysis of the benthic microbial mat of Zavarzin spring. We compared this benthic community to microbial communities found in the water and of an integral probe consisting of water and bottom sediments. Various phylogenetic groups of microorganisms, including potentially new ones, represent the full-fledged trophic system of Zavarzin. A thorough geochemical study of the spring was performed.

No DNA damage response and negligible genome-wide transcriptional changes in human embryonic stem cells exposed to terahertz radiation

Terahertz (THz) radiation was proposed recently for use in various applications, including medical imaging and security scanners. However, there are concerns regarding the possible biological effects of non-ionising electromagnetic radiation in the THz range on cells. Human embryonic stem cells (hESCs) are extremely sensitive to environmental stimuli, and we therefore utilised this cell model to investigate the non-thermal effects of THz irradiation. We studied DNA damage and transcriptome responses in hESCs exposed to narrow-band THz radiation (2.3 THz) under strict temperature control. The transcription of approximately 1% of genes was subtly increased following THz irradiation. Functional annotation enrichment analysis of differentially expressed genes revealed 15 functional classes, which were mostly related to mitochondria. Terahertz irradiation did not induce the formation of γH2AX foci or structural chromosomal aberrations in hESCs. We did not observe any effect on the mitotic index or morphology of the hESCs following THz exposure.

The mechanism by which TATA-box polymorphisms associated with human hereditary diseases influence interactions with the TATA-binding protein.

SNPs in ТАТА boxes are the cause of monogenic diseases, contribute to a large number of complex diseases, and have implications for human sensitivity to external and internal environmental signals. The aim of this work was to explore the kinetic characteristics of the formation of human ТВР complexes with ТАТА boxes, in which the SNPs are associated with β‑thalassemias of diverse severity, immunosuppression, neurological disorders, and so on. It has for the first time been demonstrated, using an electrophoretic mobility shift assay, that TBP interacts with SNP‐containing ТАТА boxes with a significant (8–36‐fold) decrease in TBP/ТАТА association rate constant (ka) as compared with that in healthy people, a smaller decrease in dissociation rate constant (kd) and changes in the half‐lives of TBP/ТАТА complexes. Carriers of the −24G allele (rs 1800202T>G) in the TATA box of the triosephosphate isomerase gene promoter, associated with neurological and muscular disorders, were observed to have a 36‐fold decrease in TBP/TATA association rate constant that are consistent with TPI deficiency shown for patients who carry this defective allele. The kinetic characteristics of TBP/ТАТА complexes obtained suggest that, at a molecular level, hereditary diseases are largely caused by changes in TBP/ТАТА association rates and these changes have a bearing on disease severity.

Studying the non-thermal effects of terahertz radiation on E. coli/pKatG-GFP biosensor cells

Studies of the impact of terahertz radiation on living objects present a significant interest since its use for security systems is currently considered promising. We studied the non-thermal impact of terahertz radiation on E. coli/pKatG-gfp biosensor cells. The Novosibirsk free electron laser (NovoFEL), which currently has the worlds highest average and peak power, was used as the source of terahertz radiation. We demonstrated that exposure to terahertz radiation at the wavelengths of 130, 150, and 200 µm and a power of 1.4 W/cm(2) induces changes in green fluorescent protein (GFP) fluorescence values and thus induces the expression of GFP in E. coli/pKatG-gfp biosensor cells. Possible mechanisms of the E. coli response to non-thermal exposure to terahertz radiation are discussed.

Identification of Bacillus strains by MALDI TOF MS using geometric approach.

Microorganism identification by MALDI TOF mass-spectrometry is based on the comparison of the mass spectrum of the studied organism with those of reference strains. It is a rapid and reliable method. However, commercial databases and programs are mostly designed for identification of clinically important strains and can be used only for particular mass spectrometer models. The need for open platforms and reference databases is obvious. In this study we describe a geometric approach for microorganism identification by mass spectra and demonstrate its capabilities by analyzing 24 strains belonging to the Bacillus pumilus group. This method is based on representing mass spectra as points on a multidimensional space, which allows us to use geometric distances to compare the spectra. Delimitation of microorganisms performed by geometric approach correlates well with the results of molecular phylogenetic analysis and clustering using Biotyper 3.1. All three methods used allowed us to reliably divide the strains into two groups corresponding to closely related species, Bacillus pumilus and Bacillus altitudinis. The method developed by us will be implemented in a Web interface designed for using open reference databases for microorganism identification. The data is available at http://www.bionet.nsc.ru/mbl/database/database.html.

Impact of Terahertz Radiation on Stress-Sensitive Genes of E.Coli Cell

Terahertz (THz) radiation is increasingly used in scientific studies, as well in practical applications, primarily in medicine and safety systems, therefore, exposure of living cells to THz-waves present significant interest. We studied the impact of THz radiation on E. coli biosensor cells containing plasmids with promoters of stress-sensitive genes controlling the expression of GFP. The impact of THz radiation was nonthermal, i.e., special care was taken to keep specimen temperature in the 35±2°C range during irradiation so that heat shock genes would not be induced. GFP level was measured by fluorometry. We found that THz radiation activates genes associated with oxidative stress response. Lower activation levels were found for copper homeostasis genes, while antibiotics resistance genes showed no response. Thus, THz radiation impact varies for different E. coli stress systems. We conclude that THz radiation significantly affects oxidative homeostasis, which is vital for E. coli cells.

Geobacillus icigianus sp. nov., a thermophilic bacterium isolated from a hot spring.

A Gram-reaction-positive, motile, thermophilic spore-forming strain, G1w1(T), was isolated from a hot spring of the Valley of Geysers, Kamchatka (Russia). Based on data from the present polyphasic taxonomic study, including phylogenetic analysis of 16S rRNA and spo0A gene sequences, the strain is considered to represent a novel species of the genus Geobacillus, for which the name Geobacillus icigianus sp. nov. is proposed. The type strain is G1w1(T) ( = VKM B-2853(T) = DSM 28325(T)).

Draft Genome Sequence of Geobacillus icigianus Strain G1w1T Isolated from Hot Springs in the Valley of Geysers, Kamchatka (Russian Federation).

ABSTRACT The Geobacillus icigianus G1w1T strain was isolated from sludge samples of unnamed vaporing hydrothermal (97°С) outlets situated in a geyser in the Troinoy region (Valley of Geysers, Kronotsky Nature Reserve, Kamchatka, Russian Federation; 54°25′51.40″N, 160°7′41.40″E). The sequenced and annotated genome is 3,457,810 bp and encodes 3,342 genes.

Draft Genome Sequences of Geobacillus stearothermophilus Strains 22 and 53, Isolated from the Garga Hot Spring in the Barguzin River Valley of the Russian Federation

ABSTRACT Geobacillus stearothermophilus strains 22 and 53 were isolated from sediment samples isolated from the Garga hot spring (72°C) located in the valley of the river Barguzin (the Baikal region, Russian Federation) (54°19′3.72″N, 110°59′38.4″E).