Search Results (226)

Tropodithietic acid (TDA) is a sulfur-containing secondary metabolite with pronounced antimicrobial activity that has been primarily described in marine Alphaproteobacteria of the Roseobacter clade. Despite extensive studies of these bacteria, the occurrence and genetic organization of the TDA biosynthetic pathway in other bacterial groups remain poorly understood. In this study, we report the production of TDA by the freshwater bacterium Janthinobacterium sp. PLB04 isolated from diseased cell cultures of the primmorphs from the Baikal sponge Lubomirskia baikalensis. The presence of a TDA biosynthetic gene cluster homologous to the canonical tda operon previously described in the marine Roseobacter clade was found in Janthinobacterium sp. PLB04 by genome mining with bioinformatic analysis. However, comparative analysis of the cluster architecture demonstrated the absence of the gene tdaC in the Janthinobacterium sp. PLB04 genome. Despite this difference, the strain retained the ability to synthesize TDA. TDA was extracted from the culture medium and identified using chromatographic and MALDI-TOF mass spectrometric analysis. These results suggest that tdaC may not be strictly required for TDA biosynthesis in this strain and may be functionally replaced with alternative enzymatic steps or functional redundancy within the pathway. The discovery of TDA production in a freshwater Janthinobacterium strain expands the known phylogenetic and ecological diversity of TDA-producing bacteria and provides new insights into the plasticity of the TDA biosynthetic gene cluster. Full article

Studying zooplankton in freshwater ecosystems is crucial for ecological research, providing insight into ecosystem health, biodiversity, and water quality. This study focuses on developing a hybrid approach for studying and analyzing zooplankton communities using machine learning and human expert analysis. The goal of the study was to automate the labor-intensive process of zooplankton analysis as part of a long-term Lake Baikal monitoring program (since 1945), while maintaining continuity with traditional methods. A software and algorithmic system were developed to automate the analysis: images were processed using a two-stage pipeline (object detection using YOLO V11, classification using metric learning and visual transformers), and complex cases and new species were sent to specialists for verification. Over 240,000 images from 811 samples were processed, and models are updated using verified data to adapt to seasonal changes. An updatable database of labeled zooplankton images suitable for statistical analysis and research has been created. A comparison of manual and machine analysis revealed no significant differences in species composition, with accurate detection in 87% of images. This approach allows for scalable monitoring and the accumulation of labeled data arrays for the development of computer vision methods and the assessment of the state of Lake Baikal’s ecosystem. Full article

Lysobacter antibioticus Hz25 is a novel strain that was isolated from the rhizosphere of the relict endemic plant Hedysarum zundukii Peschkova (Fabaceae), which grows on carbonate soils in the Baikal region of Russia. This work presents the complete genome sequence of Hz25 (5.98 Mb, 66.94% GC), which was obtained using a hybrid assembly method combining Oxford Nanopore and Illumina sequencing. Phylogenetic analysis based on 47 Lysobacter genomes and an average nucleotide identity (ANI) value of 96% confirmed its affiliation with L. antibioticus. A comparative pan-genome analysis with three closely related strains (13-6, 76, and ATCC 29479) identified 554 strain-specific genes. This significant genomic plasticity likely reflects adaptation to the sharply continental climate, high insolation, and low free iron content of the native soil. The genome encodes a comprehensive micropredator arsenal, including: seven chitinase genes (GH18 and GH19 families); bacteriolytic enzymes (Blp, L1, L4, Ami); a complete type III secretion system (T3SS) with predicted effectors; type IV pili (including the PilZ-PilB regulatory complex); and siderophore biosynthesis genes (lysochelin). The genome contains genes ars of an arsenic resistance system, but lacks the ACR3 efflux pump, suggesting that these genes may have alternative functions. Genes involved in calcium homeostasis (Excalibur domain, Na⁺/Ca²⁺ antiporter) were also identified. These features make Hz25 a promising candidate for biocontrol applications in cold climates and metal-contaminated environments. Full article

Prosocial behavior is a core element of social harmony, and implicit prosocial attitudes, which may outperform explicit assessments in predicting real-world behavior, underscore their unique utility in prosocial and moral research contexts. Moreover, red songs, a distinctive musical form emerging in specific revolutionary and developmental periods of China, align with this prosocial potential, as they are characterized by lyrics advocating patriotism, collective memory, and emotional resonance. However, the specific effect of red songs on implicit prosocial attitudes, as well as the potential moderating role of music training experience in this relationship, remains underexplored. This study aimed to explore whether red songs enhance implicit prosocial attitudes compared to neutral songs, whether music training modulates this effect, and the underlying neural correlates using the Single-Category Implicit Association Test (SC-IAT) and event-related potentials (ERPs). A mixed-factorial design was used with 60 college students (30 with ≥5 years of music training, 30 without). Participants completed the SC-IAT (measuring implicit prosocial D-scores) while EEG data were recorded, while listening to red (“China in the Lantern Light”) and neutral (“Lake Baikal”) songs. ERP components (N1, P2, N3, LPCs) were analyzed. Behaviorally, no significant main effects of song type or music training were observed, but a significant interaction emerged (F(1, 58) = 4.09, p = 0.04): the music training group showed higher D-scores under red songs (M = 0.35, SD = 0.32) than neutral songs (M = 0.15, SD = 0.51), while the non-music training group exhibited the opposite non-significant trend. Neurally, repeated measures ANOVAs revealed a significant main effect of electrode site for N1 (F(4, 212) = 48.63, p < 0.001, partial η² = 0.48), with the largest amplitudes at FCz. Red songs elicited larger N1 amplitudes than neutral songs at Fz and FCz, and incongruent trials elicited larger N1 amplitudes at Pz. For P2, a main effect of condition was found (F(1, 52) = 7.02, p = 0.01), with larger amplitudes in incongruent trials, and a significant three-way interaction of song type, condition, and electrode site (F(4, 208) = 4.46, p = 0.006), with larger P2 amplitudes for red songs under incongruent trials at Fz. For N3, main effects of song type (F(1, 53) = 14.48, p < 0.001) and stimulus type (F(2, 106) = 8.32, p = 0.001) were observed; congruent trials elicited larger N3 amplitudes than incongruent trials at Fz and FCz. For LPCs, main effects of song type (F(1, 53) = 4.89, p = 0.03) and electrode site (F(4, 212) = 3.05, p = 0.047) were found, with the largest amplitudes at Pz and the smallest at FCz. Red songs enhance implicit prosocial attitudes specifically among individuals with music training, and are accompanied by multi-stage neurocognitive differences. These findings highlight the conditional effects of red songs and inform prosocial education. Full article

Biogeochemical processes, including the oxygen cycle, were investigated in Lake Baikal during the spring thermal bar using a coupled numerical model that takes into account the intraday variability of atmospheric parameters and contains the following variables: nitrate, ammonium, phosphate, oxygen, chlorophyll a, phytoplankton, zooplankton, and small and large detritus. Nitrification, photosynthesis, remineralization, and respiration processes describe the biochemical dynamics of oxygen in the model. As a study area, the deep-water cross-section of Lake Baikal, Boldakov River–Maloye More Strait, was considered using meteorological data for June 2024 at the lake surface. Numerical results show that the thermal bar can contribute to the transport of dissolved oxygen and phyto- and zooplankton to the deeper layers of the lake. Full article

Cyanobacteria of the genus Tychonema are common inhabitants of freshwater bodies in a temperate zones. In Lake Baikal, Tychonema sp. was first reported in 2014. It grows excessively on the bottom on almost all substrates types, forming epiphytic and epizoic biofilms, and its role in the mass mortality events affecting of endemic Baikal sponges is discussed. The cyanobacterial strain BBK16 (=IPPAS B-2063^T), isolated from a biofilm on a log pier in the Bolshiye Koty settlement in 2016, was used for further taxonomic characterization. Key morphological features of strain BBK16 include its growth as a creeping mat, highly motile trichomes that are sometimes narrowed and hooked at the ends, and the presence of rounded-conical apical cells with a calyptra. Strain ultrastructure (fascicular parietal thylakoids and type D cell division) differs from Tychonema species with radial thylakoids but aligns with other genera in the Microcoleaceae family. A comprehensive analysis, including 16S rRNA gene phylogeny, conserved protein phylogeny, and whole-genome comparisons, confirmed its placement within the genus Tychonema. The average nucleotide identity, average amino acid identity and digital DNA–DNA hybridization values between strain BBK16 and T. bourrellyi FEM GT703 were 90.7%, 91.1% and 43.3%, respectively, indicating values below the standard thresholds for species delineation. Based on combined morphological, genomic, and ecological evidence, we propose the name Tychonema litorale sp. nov. for strain BBK16, a novel species described in accordance with the International Code of Nomenclature for Algae, Fungi, and Plants. Full article

Ice and snow tourism (IST) is a significant global trend, offering Russia opportunities for tourism growth and seasonal diversification. This study investigates the potential of ice and snow art as a distinct subcategory of IST on Lake Baikal. Our research is based on an analysis of academic publications and official policy documents, field surveys conducted in winter 2025, and stakeholder consultations, with the “Olkhon Ice Fest” serving as a case study. The findings indicate a clear shift toward IST, with the number of winter tourists on Olkhon Island increasing by 70% between 2021 and 2024. The festival’s key features—its use of the natural ice landscape, a unique artistic technique, an explicit ecological focus, and strong entrepreneurial initiative—support the development of a conceptual model of IST on Lake Baikal grounded in ecotourism principles. Ensuring the long-term sustainable development of IST in the region requires improved governance, infrastructure, and transport systems, as well as support for green businesses and increased environmental awareness among tourists. This study contributes to the ongoing discourse on sustainable winter tourism by demonstrating the interconnections among environmental sustainability, socioeconomic benefits, and cultural innovation, thereby situating local IST practices within the broader framework of the United Nations Sustainable Development Goals (SDGs). Full article

Lake Kotokel is one of the largest lakes along the eastern shore of Lake Baikal. Increasing anthropogenic pressure combined with climate variability led to a sharp decline in its ecological condition, culminating in an outbreak of Gaff disease in 2009. Moreover, Lake Kotokel may serve as a source of pollutants to Lake Baikal due to its hydrological connection via a system of rivers. In light of these factors, ongoing research seeks to identify the drivers of ecological degradation in the lake ecosystem and provide a comprehensive assessment of its current environmental status and potential adverse processes. In this study, we report, for the first time, the occurrence of microplastic particles in the surface water and sediments of Lake Kotokel. Mean microplastic concentrations were 0.59 ± 0.25 items/m³ in water and 280 ± 162 items/kg dry weight in sediments, with corresponding average microplastic masses of 2.6 ± 1.4 μg/m³ in water and 1.33 ± 1.21 mg/kg dry weight in sediments. In surface waters, microplastic were predominantly 1–3 mm in size, whereas sediments were dominated by 0.1–1 mm particles. Fibers were the most abundant morphological form, comprising 79.5% and 82.8% of particles in water and sediments, respectively. Five polymer types were identified, with polyethylene terephthalate being the most prevalent. Based on particle abundance and polymer composition, the ecological risk of microplastic in Lake Kotokel was assessed as low to moderate. Full article

Microplastic pollution of ecosystems is considered a modern problem. Freshwater ecosystems, despite the interest shown in their study, remain poorly understood. Lake Baikal (Russia) is one of the least studied freshwater ecosystems in this regard. This large lake is distinguished from others by its high level of biodiversity and clean drinking water. The aim of this study is a multi-matrix investigation of microplastic pollution in one of the lake’s bay. The following matrices are used: surface water, water column, sediment, macrophytes, macroinvertebrates, and fish, as well as ice and snow during the winter. The results show that certain locations exhibit high concentrations of microplastic particles. In some cases, this was due to the properties or characteristics of these locations (littoral zones near the water’s edge, macrophytes with mucus sheaths, ice and snow (potentially, the near-surface water layer after ice melt)), while in others, it was due to localized pollution (pier and ship mooring areas). An analysis of the polymer types of the detected microplastic particles reveals the presence of both common (polypropylene, polyethylene terephthalate, polystyrene, polyethylene, polyvinyl chloride) and rare (polyvinyl alcohol and alkyd resin). Moreover, in some locations, the latter two polymers predominate, a phenomenon rarely observed in other studies. Further research was recommended to focus on the chronic effects of microplastic particles on organisms associated with areas of elevated particle concentrations. Full article

Accurately modelling surface solar radiation (SSR) is essential for environmental research but remains a significant challenge in topographically complex regions like Lake Baikal, where ground measurements are sparse. This study evaluates the performance of various open-access cloud cover products—from satellite sensors (AVHRR, MODIS) and ground-based observations—for modelling daily SSR totals, using a physical radiation model validated against in-situ measurements from 10 coastal stations. The results demonstrate that the choice of cloud data critically impacts model accuracy. The AVHRR satellite product yields the most reliable estimates (R² = 0.54, RMSE = 4.538 MJ/m²), significantly outperforming both ground-based cloudiness observations and the ERA5 reanalysis dataset. This finding underscores that spatially continuous satellite data provide a superior representation of cloud attenuation for regional modelling than point-based ground observations or reanalysis. Consequently, a physical model driven by high-quality satellite cloud masks is recommended as an effective methodology for generating reliable SSR fields. Full article

Understanding the molecular mechanisms that enable vertebrate adaptation to deep-water environments remains a central goal in evolutionary biology. This study used comparative transcriptomics of skeletal muscle tissue to investigate these mechanisms in four endemic sculpin fish species (Cottoidei) from Lake Baikal, which inhabit different depth niches ranging from pelagic to benthic-abyssal zones up to 1642 m. Pelagic species showed increased activity in genes involved in sarcomere structure, calcium handling, and motor proteins, indicating adaptations for sustained locomotion. In contrast, deep-benthic specialists showed enrichment in pathways for glycolytic metabolism, proteasome function, and ubiquitination, reflecting adaptations for energy efficiency and protein homeostasis in a high-pressure environment. We conclude that the colonization of the Baikal abyssal zone by sculpins relies on a suite of shared molecular mechanisms, with distinct ecological pressures driving specific transcriptional changes in motility, metabolic strategy, and cellular integrity. This study provides a systems-level model for deep-water adaptation in vertebrates. Full article

This study is based on data obtained as part of continuous monitoring of small gas impurities (SO₂, NO₂, NO), mass concentration of aerosol particles PM_2.5 and meteorological parameters, which was first implemented at the Tankhoi observation point (southeastern coast of Lake Baikal, Russia) from October 2023 to May 2025. Statistical methods and the non-parametric wind regression receptor model (NWR) were used to analyze temporal variability and identify sources of pollution. It was found that the concentrations of gas impurities have a clearly pronounced winter maximum: the median values for sulfur dioxide and nitrogen in winter reached 9.2 μg/m³ and 13.8 μg/m³, respectively, which is associated with emissions from coal-fired thermal power plants and unfavorable meteorological conditions (inversions, low boundary layer height). In contrast to gases, PM_2.5 demonstrated a summer peak up to 43.5 μg/m³ in July–August 2024 due to abnormally hot weather and forest fires. The daily course of sulfur dioxide was characterized by an atypical daily maximum caused by the convective transport of polluted air masses from the upper layers of the boundary layer. During this period, higher concentrations of sulfur dioxide caused by long-range high-altitude transport of emissions from regional thermal power plants can reach the ground surface, leading to an increase in their concentration in the near-surface layer. Using the NWR model, the influence of regional thermal power plants located 100–150 km northwest of the station on the levels of SO₂ and NO₂ was confirmed. The results also highlight the contribution of local sources, such as vehicles, stoves, and shipping, to the formation of NO and PM_2.5. Full article

Hydroclimatic and geomorphological prerequisites for mudflow hazard were studied using data on several of the largest flood events in the Khamar-Daban mountain area (Lake Baikal, East Siberia) for the period from 1966 to 2022. The data include flood-forming precipitation and atmospheric circulation patterns, the amount of related suspended sediment discharge in the years of high floods, as well as terrain features favorable for the formation of catastrophic floods and mudflows. Floods and mudflows in the area can arise under conditions of extremely high daily precipitation (up to 200 mm or more) after the territory becomes moistened by prolonged rainfall under meridional air transport. The maximum water discharge correlates with a multifold increase in the suspended sediment discharge and turbidity. The increase in sediment discharge associated with maximum water discharge (floods) of ≤10% probability is apparently due to 4–9 times higher flow rates. On the other hand, the formation of the solid runoff component in the area is controlled geomorphologically by slope processes depending on slope steepness, elevation contrasts, and the thickness of soft sediments subject to denudation and transport. The geomorphological conditions are most favorable for the development of mudflows and catastrophic floods in the catchments of the Bezymyannaya, Slyudyanka, Khara-Murin, and Utulik rivers. Floods and mudflows are especially hazardous on the southern shore of Lake Baikal, encircled by the Khamar-Daban Range, where active mudflow processes pose risks to the towns of Slyudyanka and Baikalsk, as well as to the sludge storage facilities of the abandoned Baikal Pulp and Paper Mill. Full article

Reproductive barriers to gene flow play a key role in speciation. However, as it is not always feasible to study them directly, most studies rely on genetic divergence to infer species delimitation. In order to correlate genetic distances to reproductive incompatibilities, compact groups of closely related species are needed. In this work, we explored a species complex of Baikal amphipods (Crustacea: Amphipoda: Gammaroidea), Eulimnogammarus verrucosus. Three biological species (W, S, and E), geographically isolated in Baikal, had been found to have interspecific differences exceeding the patristic distance threshold of 0.16, and a postzygotic incompatibility had been confirmed for the closest pair, W and S. Here, we expanded our knowledge on geographical distribution of the species, discovering that secondary contact between the W and S species already occurs in natural conditions near the source of the Angara River. Our experiments have shown that the three species within the E. verrucosus species complex are separated by both prezygotic and postzygotic barriers. While neither of these barriers is absolute, their combination can ensure reproductive isolation upon secondary contact of the species. The experimental system we have developed in this and previous works can provide support for testing species delimitation hypotheses based on sequencing data and further extend these results to related species for which such experiments are unfeasible. Full article

Geothermal heating that emanates from the interior of the Earth, including the Baikal Rift Zone, produces potential energy for water movement. The basic concept behind the mechanism of deep-water renewal in Lake Baikal is conditional instability, which is a consequence of the joint effects of temperature and pressure on water density. However, an exact trigger of this instability is unknown. In this study, based on a non-hydrostatic 2.5D numerical model taking into account the intraday variability of atmospheric conditions, it was shown that, due to geothermal heating, the water column near the lake bed becomes slightly warmer (0.1–0.2 °C) than ambient waters, which can lead to instability. Simulated temperature distributions showed that 3.4 °C waters gradually shifted along the bed slope to ~650 m on day 1, ~750 m on day 3, ~830 m on day 5, and >1200 m on day 10 in the presence of geothermal heat flux; however, in its absence these waters remained at the level of ~600 m. In view of these findings, a conceptual model of deep convection and a map with potential zones of high ventilation processes in Lake Baikal are proposed. According to the map developed, deep-water renewal is expected to be the most intense at the eastern shore of Lake Baikal because of abnormally high heat release. Full article