Solubility and phase transitions in the water-protein-salt system

The previously derived formulas for the curves corresponding to sol-gel, liquid-liquid, and liquid-solid phase transitions, which correlate the critical molar composition of the water-protein-salt system with individual characteristic features of its component (protein charge z, the number of ions adsorbed v, the function of electrolyte activity A) are presented as curves in ordinary coordinates of protein solubility logS against salt concentration m3. Tendencies in changes in phase transition lines versus the v, z, and v/z ratio have been determined. Correlations of the salting-out curve and the salting-out coefficient with phase transitions are discussed.     

Differential traits and antigenic properties of the S- and R-forms of Neisseria meningitidis]

The authors demonstrated a marked dissociation of the Neisseria meningitis cultures and the capacity to their rapid change from S- to R-forms. Differential signs of the S- and R-forms are described. Differences in the degree of dissociation of the cultures depending on their origin were shown: strains isolated from the cerebrospinal fluid and the blood of patients with meningitis proved to be less dissociated, and those isolated from carriers--more dissociated. Transfers from media to media and adaptation of cultures to artificial nutrient media produced the greatest influence on dissociation of the freshly isolated strains.     

Age- and sex-related differences in brainstem auditory evoked potentials in secondary school students living in Northern European Russia

Brainstem auditory evoked potentials (BAEPs) were studied in 46 1st- to 11th-year students (22 boys and 24 girls) of a rural secondary school in Arkhangel’sk oblast. The objective of this work was to study age- and sex-related differences in BAEP characteristics in children and adolescents, living in the North and assess the BAEP characteristics as compared to reference values. In all three age groups of students, interpeak intervals I–III, III–V, and I–V characterizing the peripheral and central conduction times were shorter in girls than in boys. Interpeak interval III–V tended to increase with age only in boys (at puberty), with a significant increase in the latencies of waves I, III, and V. The BAEP characteristics in the subjects examined included a shorter peak latency and a greater amplitude of wave I (except senior students), relatively prolonged interpeak interval I–III, and more pronounced sex-related differences in BAEPs, especially at puberty. These findings show that it is necessary to revise regional reference values for BAEPs, differentiated by sex and age, including at puberty.     

The features of system organization of the brain activity during different sleep stages and transition states

Electropoligraphical study of the natural night sleep in 16 adults with the use of correlation, coherent, cluster and factor analysis were used to obtain new data describing the active nature of sleep, which is expressed especially in periods of falling asleep and the transition from one stage to another. It is shown that the process of falling asleep and deeper sleep is accompanied by intense reorganization of cortico-subcortical relations, which is reflected in the dynamics ofcrosscorrelation and coherent estimates of interrelations of biopotentials of the brain. The results of factor analysis of multichannel EEG heterogeneity of the transition process from wakefulness to sleep is manifested in significant changes of I, II and III factors weight during I(B) stage of sleep, which may reflect changes in the degree of contribution of the main integrative brain systems in the reorganization of its integral activity. A considerable increase in the I factor weight (reflecting the generalized modulatory brainstem effect on the cortex), along with a decrease in the balance of factors II and III (associated with organization of fronto-occipital and interhemispheric interactions) clearly indicates a special role of sleep synchronizing influences from the brain stem in the development of this initial stage. Reduction of EEG interhemispheric interrelations in the anterior and inferior frontal areas with the deepening of sleep may be indication of the reorganization of the frontal areas activity associated with the coordinated increasing of inactivation process in the cortex of both hemispheres. Degree of stability of the spatial structure of interregional interactions of different brain cortex areas (according to the analysis of average dispersion of crosscorrelation EEG relations) increases on falling asleep with the onset of stage I(A), but with the transition to the stage I(B) there is a significant increase of instability of values EEG crosscorrelation. With the deepening of sleep the subsequent decrease of the dispersion of EEG crosscorrelations in frontal cortex is revealed. During REM sleep the dispersion levels of inter-regional interactions increases as much as possible, especially for EEG crosscorrelations of posterotemporal and inferiofrontal parts of both hemispheres.     

Polymorphism of the mtDNA control region in wild reindeer Rangifer tarandus (Mammalia: Artioodactyla) from the European part of Russia

Genetic diversity of wild reindeer (Rangifer tarandus) inhabiting the European part of Russia, including Komi Republic, Arkhangelsk oblast, Murmansk oblast, and the Republic of Karelia was characterized using sequence polymorphism of the mtDNA control region. Despite of currently low population number of wild reindeer, they were characterized by a high level of genetic diversity (?? = 0.018; H = 0.872 to 0.914). Phylogenetic analysis showed close relationships between European reindeer and wild reindeer of Siberia. In reindeer from Murmansk oblast a haplotype in common with the wild reindeer form Southwestern Norway was described. The reindeer sample examined contained no haplotypes earlier described for the reindeer of Central Norway. It is suggested that in recent past wild reindeer from the European north of Russia formed one population with the reindeer from the north of the Asian part of Eurasia.     

The determination of the optimal conditions for the production of a number of pathogenicity factors in Vibrio cholerae

Conditions for the cultivation of V. cholerae of different sero- and biovars on tryptone medium, ensuring the maximum production of cholera toxin (CT), dermonecrotic factor (DNF), hemorrhagic factor (HF) and new cholera toxin (NCT) have been determined. The lack of coincidence in the optimum conditions ensuring the maximum production of CT, DNF and HF has been established, which may be indicative of different nature of these toxic substances. NCT, produced by vct- strains, is similar to CN in biological activity as determined in the skin permeability test and in the conditions of accumulation in tryptone medium.     

The seasonal sensitivity of brown bear denning phenology in response to climatic variability

Background

For brown bears (Ursus arctos), hibernation is a critical part of the annual life cycle because energy savings during hibernation can be crucial for overwintering, and females give birth to cubs at that time. For hibernation to be a useful strategy, timing is critical. However, environmental conditions vary greatly, which might have a negative effect on the functionality of the evolved biological time-keeping. Here, we used a long-term dataset (69 years) on brown bear denning phenology recorded in 12 Russian protected areas and quantified the phenological responses to variation in temperature and snow depth. Previous studies analyzing the relationship between climate and denning behavior did not consider that the brown bear response to variation in climatic factors might vary through a period preceding den entry and exit. We hypothesized that there is a seasonal sensitivity pattern of bear denning phenology in response to variation in climatic conditions, such that the effect of climatic variability will be pronounced only when it occurs close to den exit and entry dates.

Results

We found that brown bears are most sensitive to climatic variations around the observed first den exit and last entry dates, such that an increase/decrease in temperature in the periods closer to the first den exit and last entry dates have a greater influence on the denning dates than in other periods.

Conclusions

Our study shows that climatic factors are modulating brown bear hibernation phenology and provide a further structuring of this modulation. The sensitivity of brown bears to changes in climatic factors during hibernation might affect their ability to cope with global climate change. Therefore, understanding these processes will be essential for informed management of biodiversity in a changing world.

     

Spatial Synchronization of Brain Bioelectric Potentials Differs in Boys and Girls Aged 12–13 Years Reading Narrative Texts

The contribution of each cortical zone to the organization of spatial synchronization of brain bioelectric potential s (SSBP) was estimated using cross-correlation matrices of 20-channell EEG during reading in boys and girls aged 12–13 years. Differences in the topical distribution of the SSBP levels in young boys and girls were revealed both in the resting state and during reading. In boys, the SSBP level in the left temporal lobe was lower than that in girls, and in the right parietal lobe it was higher than that in girls in all the states studied. A decrease of SSBP in central cortex zones was revealed, indicating the activation of motor cortical areas in all subjects during reading. Enhancement of SSBP in the parietal regions of the left hemisphere and the occipital zones of both hemispheres is observed in boys during reading, while in girls SSBP is increased bilaterally in the frontotemporal areas with the involvement of the left frontal lobe. Moreover, during reading intrahemispheric correlations between EEGs of the central and temporoparietal regions with emphasis on the right hemisphere were more pronounced in boys, while both intra- and interhemispheric correlations of the left temporal regions were pronounced in girls.