Bank Voles Clethrionomys Glareolus Research Articles

Douglas fir and Norway spruce have similar effects on small mammal density, but not survival, in Central European managed forests

In an effort to ameliorate the impacts of climate change, forest managers in Central Europe increasingly turn to conifer species that produce higher yields and are better adapted to projected future climatic conditions. Though small mammals are an important component of the forest ecosystem, the impacts of enriching native broadleaf forests with conifers on small mammal communities are not well understood. We conducted mark–recapture surveys of small mammals to ascertain differences in their community structure among stands of two conifers (native Norway spruce Picea abies and non-native Douglas fir Pseudotsuga menziesii) and the dominant broadleaf in the region, European beech (Fagus sylvatica). After estimating the density of two common species, the yellow-necked mouse Apodemus flavicollis and bank vole Clethrionomys glareolus, we found that the population density of each is positively related to the proportion of beech and negatively to the proportion of conifers in each stand, though these effects of stand composition are smaller than the positive effect of herb cover. Increasing Norway spruce proportion reduced monthly survival of small mammals, while Douglas fir proportion had a positive effect on survival. We conclude that the two conifer species have similar impacts on small mammal density, though overall small mammal survival was significantly lower on plots with Norway spruce. This suggests that increasing the proportion of Douglas fir at the expense of Norway spruce may be possible without significantly changing local patterns of small mammal population density, but further research is necessary to elucidate the exact impacts of these two conifer species on small mammal demography and behavior.

First description of nymphal stages of Hoplopleura edentula (Anoplura: Hoplopleuridae) and a global checklist of the Hoplopleura associated with Clethrionomys

Abstract We present the first record of the characteristics of the three nymphal stages of Hoplopleura edentula, one of the common Eurasian species of the genus Hoplopleura. Lastly, a list of all species of Hoplopleura parasitizing the host genus Clethrionomys is provided. The descriptions of sucking louse species usually lack the features of the nymphal stages. In addition, it is impossible to determine whether the host is the main one or an accidental when there is a co-occurance of two or more lice species, unless we observe nymphs of the same species. As a result, data on the host cycle, the range of host specificity and other aspects of parasite-host system functioning, the possibility of transfer between hosts, and the possibility of transmission of pathogens, are incomplete. This study examines 114 specimens of the bank vole Clethrionomys glareolus, in which 38 Hoplopleura edentula were found.

Small mammals in the diet of the tawny owl Strix aluco in selected sites of the Biebrza Basin and Knyszyn Forest in north-eastern Poland.

The analysis of pellets of the tawny owl Strix aluco collected in the years 2009–2023 in 22 sites (ten in the Biebrza Basin and twelve in Knyszyn Forest) allowed for finding four species of Soricomorpha, nine species of Chiroptera and fifteen species of Rodentia (4, 5 and 12 in the Biebrza Basin and 4, 7 and 13 in Knyszyn Forest, respectively). Most common and most frequently caught by owls were: the bank vole Clethrionomys glareolus, the yellow-necked mouse Apodemus flavicollis and the common shrew Sorex araneus. Valuable species of bats included the pond bat Myotis dasycneme and the western barbastelle Barbastella barbastellus noted in Knyszyn Forest. Rare rodents found in both study areas were: the northern birch mouse Sicista betulina and the common dormouse Muscardinus avellanarius while the forest dormouse Dryomys nitedula was noted only in Knyszyn Forest. The European water vole Arvicola amphibius commonly noted in the Biebrza Basin was not found in Knyszyn Forest. On the contrary, the common pine vole Microtus subterraneus was reecorded only in Knyszyn Forest.

No expression of magnetic compass orientation in Clethrionomys glareolus in total darkness (Rodentia: Cricetidae)

Our knowledge about magnetoreception in mammals remains limited. Among rodents, magnetic compass orientation has been documented in four subterranean mole-rats and four epigeic (i.e., active above ground) species. While it is well established that the magnetic compass of mole-rats is light-independent and magnetite-mediated, recent evidence suggests that a radical pair-based mechanism may underlie magnetic orientation in epigeic rodents. To determine whether the magnetic compass of epigeic rodents is light-dependent, which is thought to be an inherent feature of radical pair-based magnetoreception, we investigated the ability of the bank vole Clethrionomys glareolus (Cricetidae) to use magnetic compass orientation in total darkness. The voles, which were allowed to explore/build a nest overnight in a circular arena, did not exhibit any directional preference in the initial stage of the experiments; later they tended to prefer the southern sector of the arena irrespective of magnetic field direction, implying that they relied on nonmagnetic orientation cues. Previous tests (Oliveriusová et al. 2014) in the same environment, but under lighting, showed a significant reaction to a change in the orientation of the magnetic field. On the basis of the presented study in comparison with the previous one, it can be concluded that bank voles do not use the magnetic compass for near-space orientation in darkness and thus support evidence for light-dependent magnetoreception in a mammal.

Inhibition of interferon I induction by non-structural protein NSs of Puumala virus and other vole-associated orthohantaviruses: phenotypic plasticity of the protein and potential functional domains

The orthohantavirus Puumala virus (PUUV), which is transmitted by bank voles (Clethrionomys glareolus), and other vole-borne hantaviruses contain in their small (S) genome segment two overlapping open reading frames, coding for the nucleocapsid protein and the non-structural protein NSs, a putative type I interferon (IFN-I) antagonist. To investigate the role of NSs of PUUV and other orthohantaviruses, the expression pattern of recombinant NSs constructs and their ability to inhibit human IFN-I promoter activity were investigated. The NSs proteins of PUUV and related cricetid-borne orthohantaviruses showed strong inhibition of IFN-I promoter induction. We identified protein products originating from three and two methionine initiation codons in the NSs ORF of PUUV during transfection and infection, respectively. The three putative start codons are conserved in all PUUV strains analysed. Translation initiation at these start codons influenced the inhibitory activity of the NSs products, with the wild-type (wt) construct expressing two proteins starting at the first and second methionine and showing strong inhibition activity. Analysis of in vitro-generated variants and naturally occurring PUUV NSs proteins indicated that amino acid variation in the NSs protein is well tolerated, suggesting its phenotypic plasticity. The N-terminal 20-amino-acid region of the NSs protein was found to be associated with strong inhibition and to be highly vulnerable to amino acid exchanges and tag fusions. Infection studies using human, bank vole, and Vero E6 cells did not show obvious differences in the replication capacity of PUUV Sotkamo wt and a strain with a truncated NSs protein (NSs21Stop), showing that the lack of a full-length NSs might be compensated by its N-terminal peptide, as seen in transfection experiments. These results contribute to our understanding of virus-host interactions and highlight the importance of future innate immunity studies in reservoir hosts.

Assessment of mouse rodents’ dose from the CHNPP contaminated territories

The main feature of the nearest 5-km zone of the Chernobyl nuclear power plant is the maximum concentration of fuel fallouts due to the accident in 1986. It is a unique testing ground for radiobiological research in the natural habitat of animals. At present, the background radiation level in the 5-km zone of the Chernobyl nuclear power plant fluctuates from 0.1 to 20 μSv/h. Besides, electrons from the decay of 90Sr and 137Cs add a significant contribution to the radiation background. Even though a large amount of experimental data on dose loads on the fauna of affected areas has been accumulated to date, the results obtained do not give an unambiguous idea of the dose dependences of radiobiological effects in natural ecosystems. In this work, we studied the total dose of irradiation of two murine rodents species: the bank vole (Clethrionomys glareolus) and the yellow-necked mouse (Apodemus flavicollis), living in territories of different levels of pollution near the destroyed power unit 4 of the Chernobyl nuclear power plant. We have assessed the density of radioactive contamination of the territory and study the isotopic composition of the fallout. Soil samples were taken to a depth of 30 cm, considering the depth of burrowing of mouse-like burrows is 10-15 cm. The 90Sr, 90Y, and 137Cs concentrations were measured using β- and γ-spectrometric methods for the selected soil samples. The 90Sr, 90Y, and 137Cs βactivity spectra were measured using a developed scintillation beta-spectrometer with a thin entrance window. Soil samples' gamma spectrometric studies were carried out using an anti-Compton device with an HPGe detector. The method for processing complex Xray and gamma-spectra in the energy range of 10-100 keV is developed. It takes into account the complexity of describing X-ray lines and providing a processing error of ≤1%. We calculated the murine rodents' radiation doses using the obtained data on the concentration of 90Sr, 90Y, and 137Cs activities in soil samples and animal bodies. The doses were calculated due to external irradiation with γ-quanta and electrons and internal irradiation with 137Cs and 90Sr electrons. For the first time, we obtained data on external electrons' contribution to the total dose of irradiation of murine rodents living in the contaminated territories of the 5-km zone of the Chernobyl nuclear power plant. Doses of internal irradiation and external γ-quanta are in good agreement with the data obtained for these territories earlier. It was found that the radiation dose is formed mainly due to external electrons for most rodents. Since many studies, including genetic and biochemical ones, are tied to the radiation dose, the correct account of the contribution of electrons to the radiation dose is, in many cases, critical.

Growth of the Hippocampus in Bank Voles (Clethrionomys glareolus, Rodentia) from Different Seasonal Generations

Age-related variations in the hippocampus mass in the late postnatal ontogeny of bank voles (Clethrionomys glareolus) from the spring and autumn generations are considered in a comparative aspect. The mass of the hippocampus of the spring voles increases regularly over their short life cycle and approaches the values maximum for the species at two months of age. In the autumn voles, a two-peak growth curve is detected, the hippocampus increasing until September, after which an autumn-winter regression of the mass of this brain region was observed. The hippocampal growth of autumn voles resumed at the age of 7–9 months and coincided with the beginning of the period of reproduction. The hippocampus of autumn voles reached a definitive size at the age of 10–11 months. The results obtained characterize specific features of hippocampal growth in spring and autumn voles. The mechanisms that switch the alternative types of ontogeny of the seasonal generations are discussed.

Geochemical Ecology of Small Mammals at Industrially Polluted Areas: Is There any Effect of Reduction in the Emissions?

The paper presents data on the involvement of local populations of bank vole (Clethrionomys glareolus) in the biogeochemical cycles of Cu, Zn, Cd, and Pb at territories strongly chemically polluted by large nonferrous metallurgical plant in the Middle Urals (in 1990–1992) and after a significant decrease in its emissions (in 2015–2017). At maximally polluted areas (impact zone), the animal-controlled transit Cu, Cd, and Pb flows approached their background values by the end of the study period, and the Zn flow simultaneously twofold decreased compared to the background areas. At moderately polluted areas (buffer zone), no significant changes in the metal fluxed were detected for any of the elements. The specifics of the transit flows of the elements at variably polluted areas are controlled by the concentrations of these elements in the diet of the animals and by the abundance of voles. Thereby the manyfold (fifty-fold) decrease in the emissions did no result in an equivalent decrease in the concentrations of the metals in the animal rations at the polluted areas. The main reason for the changes was a structural transformation in the community of the small mammals, which led to a drastic decrease in the bank vole population in the impact zone. The simultaneous effects of the analyzed factors over the study period of time (25 years) resulted in intensification (in the background zone), retardation (impact zone), and stabilization (buffer zone) of the biogeochemical exchange of the elements.

The content of dioxins and furans in soils, bottom sediments of water bodies, and tissues of small mammals near the landfill site with municipal solid wastes (Moscow, Russia).

For the first time, the levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were characterized in the tissues of wild small mammals living in contaminated sites near a municipal solid waste landfill (Moscow, Russia). The Ural field mice Sylvaemus uralensis, the bank voles Clethrionomys glareolus, and the common shrews Sorex araneus were trapped at 1- and 5-km distances from the landfield "Salariyevo." High-resolution chromatography-mass spectrometry was used to measure the levels of 17 PCDD/Fs congeners in the animal organisms and natural objects (soils, bottom sediments). The values of the total toxic equivalencies (WHO-TEQ05) for animals were many times higher than those for soils and bottom sediments. The octo-substituted congeners dominated in the samples from the habitat, whereas the highly toxic 2,3,7,8-substituted ones-in the mammalian tissues. The levels of WHO-TEQ05 were comparable in the soil samples collected at 1- and 5-km distances from the dump body. The levels of WHO-TEQ05 in tissues of mammals caught 1km from the dump were much higher than those of the distant territory inhabitants. The maximum WHO-TEQ05 levels were found in the shrews, and this has been considered in terms of nutrition characteristics. The data obtained will be used to assess the risks of chronic exposure to low doses of PCDD/Fs contaminating the environment near landfills.

Variation of Metallothionein I and II Gene Expression in the Bank Vole (Clethrionomys glareolus) Under Environmental Zinc and Cadmium Exposure

The main idea of the study was to assess how environmental metal pollution activates defence responses at transcription levels in the tissues of bank voles (Clethrionomys glareolus). For this purpose, the metallothioneine (MT) genes expression (a well known biomarker of exposure and response to various metals) was measured. The real-time PCR method was used for relative quantification of metallothionein I and metallothionein II expressions in the livers, kidneys and testes of bank voles from six populations exposed to different contaminants, mainly zinc, cadmium and iron. The assessment of Zn, Cu and Fe concentrations in the tissues allowed to study the MTs gene expression responses to these metals. ANOVA analysis showed differences between populations in terms of metal concentration in tissues, livers and kidneys. Student T test showed significant differences in metal concentration between unpolluted and polluted sites only for the liver tissue: significantly lower Zn levels and significantly higher Fe levels in the unpolluted sites. Kruskal–Wallis test performed on CT data shows differences in the gene expressions between populations for both MT genes for liver and testes. In the liver metallothionein I gene expression was upregulated in populations considered as more polluted (up to 7.5 higher expression in Miasteczko Śląskie comparing to Mikołajki). Expression of metallothionein II revealed a similar pattern. In kidneys, differences in expression of both MT genes were not that evident. In testes, MT upregulation in polluted sites was noted for metallothionein II. For metallothionein however, we found downregulation in populations from more contaminated sites. The expressions of both MTs were positively influenced by cadmium in kidney (concentration data from the previous study) and zinc and copper in liver, while cadmium had effects only on the liver MT II gene expression. Positive relationship was obtained for lead and metallothionein II expression in the liver.

Tick infestation in bank voles from East Anglia

Bank voles (Clethrionomys glareolus) are widespread and abundant in the western half of Eurasia, including Great Britain. These small rodents often come into contact with domestic animals and/or humans, either directly or indirectly, and thus are an interface between sylvatic and domestic cycles for zoonotic organisms. Bank voles were live-trapped and inspected for ticks in Cambridgeshire, Essex and Suffolk from June 1999 to April 2000. Infested voles hosted between 1 and 10 ticks. Larvae were the most frequent stage. Overall prevalence estimate of tick infestation was 14.5% (95% C.I. : 8.3% to 20.7%). Prevalence estimates fluctuated with seasons. Two tick species were identified : Ixodes ricinus (larvae only) and Ixodes trianguliceps (all three stages). The aggregated distribution of ticks on their hosts suggests that co-feeding transmission of tick-borne pathogens may happen in British bank voles. Further investigations are required to improve our knowledge and understanding of the epidemiology of tick-borne diseases in East Anglia.

Mitogenomic phylogenetics of the bank vole Clethrionomys glareolus, a model system for studying end-glacial colonization of Europe

We have revisited the mtDNA phylogeny of the bank vole Clethrionomys glareolus based on Sanger and next-generation Illumina sequencing of 32 complete mitochondrial genomes. The bank vole is a key study species for understanding the response of European fauna to the climate change following the Last Glacial Maximum (LGM) and one of the most convincing examples of a woodland mammal surviving in cryptic northern glacial refugia in Europe. The genomes sequenced included multiple representatives of each of the eight bank vole clades previously described based on cytochrome b (cob) sequences. All clades with the exception of the Basque – likely a misidentified pseudogene clade – were highly supported in all phylogenetic analyses and the relationships between the clades were resolved with high confidence. Our data extend the distribution of the Carpathian clade, the marker of a northern glacial refugium in the Carpathian Mountains, to include Britain and Fennoscandia (but not adjacent areas of continental Europe). The Carpathian sub-clade that colonized Britain and Fennoscandia had a somewhat different history from the sub-clade currently found in or close to the Carpathians and may have derived from a more north-westerly refugial area. The two bank vole populations that colonized Britain at the end of the last glaciation are for the first time linked with particular continental clades, the first colonists with the Carpathian clade and the second colonists with the western clade originating in a more southerly refugium in the vicinity of the Alps. We however found no evidence that a functional divergence of proteins encoded in the mitochondrial genome promoted the partial genetic replacement of the first colonists by the second colonists detected previously in southern Britain. We did identify one codon site that changed more often and more radically in the tree than expected and where the observed amino acid change may affect the reductase activity of the cytochrome bc1 complex, but the change was not specific to a particular clade. We also found an excess of radical changes to the primary protein structure for geographically restricted clades from southern Italy and Norway, respectively, possibly related to stronger selective pressure at the latitudinal extremes of the bank vole distribution. However, overall, we find little evidence of pervasive effects of deviation from neutrality on bank vole mtDNA phylogeography.

Spontaneous expression of magnetic compass orientation in an epigeic rodent: the bank vole, Clethrionomys glareolus.

Magnetoreception has been convincingly demonstrated in only a few mammalian species. Among rodents, magnetic compass orientation has been documented in four species of subterranean mole rats and two epigeic (i.e. active above ground) species-the Siberian hamster and the C57BL/6J mouse. The mole rats use the magnetic field azimuth to determine compass heading; their directional preference is spontaneous and unimodal, and their magnetic compass is magnetite-mediated. By contrast, the primary component of orientation response is learned in the hamster and the mouse, but both species also exhibit a weak spontaneous bimodal preference in the natural magnetic field. To determine whether the magnetic compass of wild epigeic rodents features the same functional properties as that of laboratory rodents, we investigated magnetic compass orientation in the bank vole Clethrionomys glareolus (Cricetidae, Rodentia). The voles exhibited a robust spontaneous bimodal directional preference, i.e. built nests and slept preferentially along the north-south axis, and deflected their directional preference according to a shift in the direction of magnetic north, clearly indicating that they were deriving directional information from the magnetic field. Thus, bimodal, axially symmetrical directional choice seems to be a common feature shared by epigeic rodents. However, spontaneous directional preference in the bank vole appeared to be more pronounced than that reported in the hamster and the mouse. These findings suggest that bank voles are well suited for future studies investigating the adaptive significance and mechanisms of magnetic orientation in epigeic rodents.

Species composition, abundance, and annual cycles of fleas (Siphonaptera) on bank voles (Clethrionomys glareolus) in the western part of Vologda Province (Babaevo District)

A total of 383 fleas of 11 species were collected off 428 bank voles (Clethrionomys glareolus) captured near Babaevo (59°4′N, 35°8′E). Three of the species recorded (Amphipsylla rossica, Doratopsylla dasycnema, and Palaeopsylla soricis) were not typical of these rodents, infesting the latter occasionally from other animals, such as the common vole Microtus arvalis and shrews inhabiting adjacent or the same biotopes. Peromyscopsylla bidentata, infesting the bank vole in most part of its range, was recorded only as a single female. Megabothris turbidus was also very rare, being sporadically recorded from May to October; the examined territory probably lies at the northern boundary of its range. The most abundant species, Ctenophthalmus uncinatus, had two peaks of abundance: in April, when adults emerged from overwintered cocoons, and in July. Then their abundance decreased and the last occasional individuals were recorded till December. The year-round parasite Amalaraeus penicilliger was most abundant in winter. Other species were few in number. Adults of Megabothris rectangulatus were recorded from April to August with two peaks of abundance: in April, when they emerged from overwintered cocoons and in July, when the second generation emerged. The univoltine species Peromyscopsylla silvatica emerged in July–August and parasitized till September. Rhadinopsylla integella was the most abundant in October–December, but occasional specimens were recorded in January. The polyxenous species Hystrichopsylla talpae emerged in late July and occurred till September.

Relaxed functional constraints on triplicate α-globin gene in the bank vole suggest a different evolutionary history from other rodents

Gene duplication plays an important role in the origin of evolutionary novelties, but the mechanisms responsible for the retention and functional divergence of the duplicated copy are not fully understood. The α-globin genes provide an example of a gene family with different numbers of gene duplicates among rodents. Whereas Rattus and Peromyscus each have three adult α-globin genes (HBA-T1, HBA-T2 and HBA-T3), Mus has only two copies. High rates of amino acid evolution in the independently derived HBA-T3 genes of Peromyscus and Rattus have been attributed to positive selection. Using RACE PCR, reverse transcription-PCR (RT-PCR) and RNA-seq, we show that another rodent, the bank vole Clethrionomys glareolus, possesses three transcriptionally active α-globin genes. The bank vole HBA-T3 gene is distinguished from each HBA-T1 and HBA-T2 by 20 amino acids and is transcribed 23- and 4-fold lower than HBA-T1 and HBA-T2, respectively. Polypeptides corresponding to all three genes are detected by electrophoresis, demonstrating that the translated products of HBA-T3 are present in adult erythrocytes. Patterns of codon substitution and the presence of low-frequency null alleles suggest a postduplication relaxation of purifying selection on bank vole HBA-T3.

Structure and diversity of small mammal communities of mountain forests in Western Carpathians

We sampled the small mammal (SM) community in mountain forest ecosystems of the Beskydy Mountains over 5 years in order to study associations with different types of forest habitat. Fourteen species were determined, three being eudominant (yellow-necked mouse—Apodemus flavicollis (45 %), bank vole—Clethrionomys glareolus (23.3 %) and field vole—Microtus agrestis (15.7 %) and one dominant common shrew—Sorex araneus (9.3 %)). Highest abundance was observed in young succession sites (plantations) with dicotyledonous plants dominant (>50 %) in the undergrowth. Highest diversity was observed in plantations and primeval forests. Lowest total abundance and diversity were observed in mature monocultures. Significant differences in diversity were only found between old monocultures and other sites. Using a faunistic similarity index, two basic SM community groups were determined: those inhabiting (1) early (plantation) and late (reserve) successional forest ecosystems with a dense dicotyledonous plant herb layer, and (2) plantations with a dense grass herb layer and forests with a dense canopy closure (fruiting monoculture). Redundancy analysis confirmed separate habitat preferences of the three eudominant species. Generalised linear model indicated increasing preference of field vole for plantations with dominance of grass and 10–15 %, and increasing preference of bank vole for plantations with a dicotyledonous plant ratio of >10–15 %. The biotopes monitored proved suitable for long-term survival of the dominant SM species. Early successional plantations and forest reserves also represent important refuges for a number of rarer SM species presently under threat.

Correlation between level of chromosomal aberrations and demographic parameters

The correlation between the level of chromosomal abnormalities and demographic parameters has been studied using individuals from a local wildlife population of the bank vole (Clethrionomys glareolus) from a Middle Ural locality in the southern taiga subzone (57°15' N, 58°44' E). Variations in the rate of structural chromosomal aberrations, gaps, and changes in the number of chromosomes in the bone marrow cells of the bank vole has been examined using routine cytogenetic methods. The effect of demographic parameters, i.e., population density, age, sex, and reproductive status, has been estimated using loglinear analysis. It has been shown that the share of individuals with an elevated rate of cells that carry structural chromosomal abnormal� ities and gaps decreases with increases the population size. This pattern agrees with the standpoint that a lower rate of mutations in somatic cells enhances survival of organisms. This pattern can have established as a con� sequence of natural selection, which induces the rearrangement of the genetic structure in the population or as a byproduct of other processes in the population that accompanies the changes in its size. A high popula� tion density leads to an increase in the share of individuals that display an elevated rate of cells with abnormal chromosome numbers among the yearling voles. A similar effect may result from an asymmetric interference competition between adults and yearling individuals. Our results demonstrate that the proportion of animals that display an elevated rate of somatic cells with structural chromosomal abnormalities and aberrant chro� mosome numbers considerably increases with age, which agrees with both the theoretical concepts and experimental data. Neither sex nor involvement in reproduction has any significant effect on the level of cyto� genetic instability.

The effect of a caudal hippocampus lesion on learning in a Morris water maze in Bank Voles (Clethrionomys glareolus)

A bilateral cytotoxic lesion of the caudal hippocampus (about 1/3 of the whole hippocampus, which is insufficiently studied) influences learning of bank voles (Clethrionomys glareolus) in the Morris water maze. This effect has been estimated in this paper. A version of the test intended to measure long-term spatial memory was used. The lesion was shown to exert an influence on the learning dynamics by slowing it down, as well as to reduce the accuracy of platform location memorizing at early stages of training. The data obtained indicate the involvement of this area in control of spatial learning in rodents.

Morphofunctional analysis of testes and sperm in the assessment of male reproductive success in the bank vole (Clethrionomys glareolus)

The morphofunctional analysis of testes and sperms in bank vole (Clethrionomys glareolus, Schreber, 1780) from a natural population is carried out to assess the reproductive potential of animals. It is shown that the reproductive success of males depends on the density of the population. Under physiological stress, such as a "peak" of the population size, the animals, against a background of accelerated aging, have activation of the hypothalamic-pituitary-adrenal axis, which contributes to oppression of the spermatogenesis process. The absolute weight of the testes is not always the determining factor in assessing the fertility of the animal. The informative indicators of the reproductive success of males and the population as a whole include the level of destructive changes in the endocrine and germinal regions of morphological defects of the testis and sperm.

Functional features of microbial communities in the digestive tract of field voles (Microtus rossiaemeridionalis and Clethrionomys glareolus)

The nitrogen-fixating and cellobiohydrolase activity, the nitrogen (N) and carbon (C) contents, and the number of microorganisms in the prestomach, cecum, and colon of two vole species were studied: the southern vole (Microtus rossiaemeridionalis) and the bank vole (Clethrionomys glareolus), which is characterized by a mixed type of diet. The nitrogen-fixating activity in the cecum was found to be the highest in the voles compared with the mammals studied earlier. The seasonal dynamics of both nitrogenase and cellobiohydrolase activities was registered in the southern vole. The structure of the microbial complex in the southern vole is more varied and includes microorganisms associated with plant substrates.