Doklady Biological Sciences最新文献

Rest and sleep states of an adult pair of hippopotamuses (Hippopotamus amphibius) and their two-month-old calf are described in a zoo (Tampa, United States). During the day, the animals spent an equal amount of time on land and in water; at night, they spent on average 76% of their time in water. Rest occupied 48-53% of the 24-hour period (11.4-12.8 h). On land, the animals rested in a lying position (18% of rest in the calf); in water-lying, sitting, or standing on the bottom with nostrils, eyes, and ears above the surface (80% in the female), or submerged and lying on the bottom (29% in the calf). All displayed eye jerks and twitches featured characteristics of REM sleep. On land, 98% of breathing pauses lasted <30 s. In water, they ranged from 4 to 145 s, with most lasting <1 min. The male's eyes were closed more often (up to 72%), the female's partially open (84%). Slow wave sleep in the hippopotamus is likely bilaterally symmetrical, as in terrestrial mammals. The female's sleep was more fragmented, less deep and less vigilant due to calf care.

Fungal and prokaryotic communities in unique ecosystems of Arctic seas are important to study for understanding global biogeochemical cycles and developing approaches to bioremediation of the ecosystems. High-throughput sequencing of the variable regions ITS1/ITS2 (in fungal genomes) and V3-V4 of the 16S rRNA gene (in bacterial genomes) was performed to study the species composition and taxonomic structure of fungal and heterotrophic bacterial communities in surface benthic sediments of the Kara Sea from depths of 16-417 m. The fungal biome was dominated by operational taxonomic units (OTUs) of Ascomycota (more than 50% of ITS reads in each of the 12 samples), which was followed by the division Basidiomycota (10-20%). Сhytridiomycota accounted for no more than 2% of ITS reads. No significant differences in the mycobiome structure of Kara Sea benthic sediments were found depending on the sampling depth. OTUs of Sordariomycetes and Eurotiomycetes (Aspergillaceae) prevailed. Basidiomycetes were represented mainly by yeasts of the families Filobasidiaceae, Malasseziaceae, Sporidiobolaceae, and Tremellaceae. According to fluorescence microscopy, the total number of fungal propagules ranged 207-546 thousand spores and mycelial fragments per 1 g benthic sediment and was minimum at greater depths. At all of the stations examined, sediments were found to contain numerous aerobic heterotrophic bacteria belonging to various families, orders, and classes of the phyla Pseudomonadota, Actinomycetota, Bacteroidota, Verrucomicrobiota, Gemmatimonadota, Myxococcota, and Acidobacteriota. Interestingly, nucleotide sequences characteristic of strict anaerobes were detected in oxidized surface benthic sediments of the Kara Sea. The set included sulfate-reducing bacteria of the phylum Thermodesulfobacteriota and chemoheterotrophic bacteria of Anaerolineae (phylum Chloroflexota). The data obtained in the study significantly expand our knowledge of the diversity of fungi and bacteria, which are key heterotrophic organisms that destroy organic matter in benthic sediments of Arctic seas.

The fatty acid (FA) composition was studied in pink salmon smolts during their migration (from start to ending) in the Indera River and in an experiment with stationary cages (in the river, the estuary, and the White Sea), taking account of differences in water temperature and salinity. Changes in the quantitative composition of FAs (higher contents of total saturated (SFAs) and monounsaturated (MUFAs) FAs and a lower content of polyunsaturated FAs (PUFAs)) were found in smolts in the middle of their downstream migration and in an experimental group kept in cages in the sea for 72 h. The qualitative composition of major FAs (16:0, 18:1(n-9), 20:5(n-3), and 22:6(n-3)) was the same in all of the study groups and was similar to that at earlier stages of pink salmon development. Variations in the contents of 20:5(n-3) and 22:6(n-3) were observed in experimental smolt groups that confirmed the important role of these PUFAs in adaptation of pink salmon smolts to the transition from a freshwater river ecosystem to living in the sea.

Wood-destroying fungi of the genus Ganoderma are among the most widespread polypore fungi in the world. The interest in their study is constantly growing because many biologically active substances are produced by Ganoderma. The artist's bracket fungus Ganoderma applanatum is the most common species of the genus in central Russia. The objectives of this study were to characterize intraspecific genetic polymorphism in terms of sexual and somatic compatibility and to assess the variation of the ITS sequence in G. applanatum, based on 26 natural isolates collected in various localities of the Moscow region. An original technique developed to reproduce the G. appalanatum life cycle in laboratory conditions and to obtain a fertile hymenium in vitro allowed a genetic analysis of the allele diversity of mating type loci in mon-mon and di-mon crosses. At least eight alleles of the matA locus and seven alleles of the matB locus were observed in 21 G. applanatum isolates. The Shannon genetic diversity index of antagonistic reactions of vegetative incompatibility was estimated at Hvc = 1.216, suggesting a high genetic polymorphism of vegetative incompatibility determinants. Diverse phenotypic manifestations of antagonistic reactions showed that the vegetative incompatibility loci were probably multiallelic. Antagonism type did not depend on the geographic location of the isolates, and vegetatively compatible clones were detected only within the same substrate. In spite of the genetic polymorphism and multiallelic nature of the mating and somatic compatibility loci, the ITS sequences showed no divergence in the Moscow G. applanatum isolates and were assumed to provide a reliable barcode for species identification and verification of natural isolates of the fungus. Based on the results, the G. applanatum population of the Moscow region is spread over a large area, but substantial intrapopulation differentiation in terms of sexual and somatic compatibility.

Fullerenol C₆₀(OH)_22-24 was tested for its effect on the viability of human peripheral blood monocytes, and its adhesion/internalization by monocytes was studied. Nanoparticles used at concentrations of 0.25, 0.5, 2.5, 5, 12.5, 25, 50, 100, and 200 μg/mL were incubated with human blood mononuclear cells for 24, 48, and 72 h (5% CO₂ at 37°C). Monocyte viability and fullerenol fluorescence intensity in the monocyte gate were then assessed by flow cytometry. Nanoparticles were adsorbed/internalized by cells in proportion to their concentration and incubation time. Fullerenol C₆₀(OH)_22-24 used at 200 μg/mL reduced the monocyte viability on average by 17, 30, and 28% after 24, 48, and 72 h, respectively. Cell survival inversely correlated with nanoparticle uptake intensity. The concentrations ≤100 μg/mL did not exhibit cytotoxicity even after prolonged exposure, supporting biomedical applicability of fullerenol.

Macrofossils of shrubby birch (Betula humilis) of the boreal species group and avens (Dryas sp.) of the Arctic-alpine species group, both dated to ~2500 radiocarbon years ago, were found in the Kazakh Uplands (Abylai site, 49°15' N, 75°07' E). The species are currently absent from the region. The finds indicate that a refugium of the species existed in the Kazakh Uplands in the Holocene. The species appeared on the territory of the Kazakh Uplands at the end of the Late Pleistocene. At the beginning of the Holocene, their ranges retreated to the north and a refugium formed on the territory of the Kazakh Uplands. Sharply continental climate and favorable edaphic conditions contributed to the preservation of the refugium. The disappearance of the refugium was associated with biocenotic reorganization, which affected the vegetation in the second half of the Late Holocene and was caused by climate changes.

Annual rings of conifers conventionally serve as a reliable indicator of climatic changes, whereas methods of such analyses are poorly developed for diffuse-porous species, such as the common aspen Populus tremula L. PiC densitometry was proposed as a new approach based on algorithmic analysis of the wood porosity distribution across the annual ring. Scotch pine Pinus sylvestris L. and aspen samples were used in the study. The method included measurement of the annual ring widths, anatomical analysis of the wood microstructure, and image processing to construct porosity profiles. Basic differences in porosity dynamics were observed between the species. In pine, porosity decreased by 70% from earlywood to latewood, reflecting a seasonal reduction in water supply. In aspen, the respective change did not exceed 20%, indicating a stable water demand throughout the season. Dendroclimatic analysis showed that pine radial growth was most sensitive to May-June precipitation, while temperatures during the same period were the key factor in aspen. PiC densitometry expands the possibilities of dendrochronological studies, allowing the use of diffuse-porous species for climate reconstruction and assessment of the climate effect on the wood structure.

Age differences in the response to acute stress were studied in young and mature reproductive-age inbred male Wistar rats. Stress was found to increase the corticosterone level in both age groups, while the testosterone level decreased and the leptin concentration increases. In response to stress, young rats showed a classic decrease in the mass coefficients (MCs) of the thymus and liver and an increase in the MCs of the adrenal glands and heart. In contrast, mature rats showed a decrease in the MC of the adrenal glands and stability of the MC of other visceral organs under all experimental conditions. The rats were tested in the elevated plus maze (EPM), and opposite behavioral changes were observed in the two groups after stress exposure. Exploratory activity decreased in the young rats and increased in the mature rats. It was assumed that neurons of the dorsal part of the periaqueductal grey and the cerebellum were in an excited state as a result of accumulated life experience in the mature rats and that this was expressed as more intense locomotor activity (LA) and a higher efficiency of decision-making mechanisms in choosing the direction of movement in the EPM. Lack of such experience in the young rats inhibited the LA speed and decision-making mechanisms, inducing a feeling of uncertainty during navigation in the EPM. The data can have a wide range of applications in preclinical studies related to health, aging, stress, and modeling of various diseases.

Tzvelev and Kulikov, who are leading monographers of the genus Betula, recognize the independence of birch microspecies. In the Southern Trans-Urals, B. krylovii belongs to this group. Most studies of Betula representatives have employed conventional phenotype-based methods and lack mechanisms to resolve taxonomic challenges in the complex genus. The study aimed to comprehensively asses the genetic and morphological polymorphism in birch populations along the Tobol River in the Southern Trans-Urals. Ploidy levels of Betula representatives, variability of chloroplast DNA fragments, and the morphological structure of leaf blades were examined in 10 birch sampling sites. Moderate genetic polymorphism and low interpopulation differentiation were observed in B. pendula of the Southern Trans-Urals. A low occurrence of B. pubescens was inferred from the ploidy data. According to the results of the comprehensive analysis, the taxa B. pendula and B. krylovii have similar phenotypic features, common chlorotypes, and the same ploidy level (2n), indicating that the taxonomic status of B. krylovii requires revision.