[Aerosol deposition in nasal passages of burrowing and ground rodents when breathing dust-laden air].

In subterranean rodents, which dig down the passages with frontal teeth, adaptation to the underground mode of life presumes forming of mechanisms that provide protection against inhaling dust particles of different size when digging. One of such mechanisms can be specific pattern of air flow organization in the nasal cavity. To test this assumption, comparative study of geometry and aerodynamics of nasal passages has been conducted with regard to typical representative of subterranean rodents, the mole vole, and a representative of ground rodents, the house mouse. Numerical modeling of air flows and deposition of micro- and nanoparticle aerosols indicates that sedimentation of model particles over the whole surface of nasal cavity is higher in mole vole than in house mouse. On the contrary, particles deposition on the surface of olfactory epithelium turns out to be substantially less in the burrowing rodent as compared to the ground one. Adaptive significance of the latter observation has been substantiated by experimental study on the uptake ofnanoparticles of hydrated manganese oxide MnO x (H2O)x and Mn ions from nasal cavity into brain. It has been shown with use of magnetic resonance tomography method that there is no difference between studied species with respect to intake of particles or ions by olfactory bulb when they are introduced intranasally. Meanwhile, when inhaling nanoparticle aerosol of MnCl2, deposition of Mn in mouse's olfactory bulbs surpasses markedly that in vole's bulbs. Thereby, the morphology of nasal passages as a factor determining the aerodynamics of upper respiratory tract ensures for burrowing rodents more efficient protection of both lungs and brain against inhaled aerosols than for ground ones.

[Reproductive success of males of the ICR outbred line during propagation against the background of antigenic stimulation].

Diversity of viruses, bacteria, microscopic fungi, and endo- and ectoparasites is an inevitable environmental factor that influences the host reproduction and that is determined not only by negative effects of infectious diseases but also by activation of protective mechanisms, which provide a confrontation to the pressure of parasites. In the present work, hemocyanin was injected into males of the ICR outbred line in order to study reproductive consequences of antigenic stimulation of males. Intact females were added to control and antigen-stimulated males at the initial stage of antibody formation. During 6 days of combined keeping, a significantly greater amount of ovulated egg cells and living embryos were registered in the females added to males that were injected with hemocyanin compared with that theoretically expected for equal reproductive yield. Females covered by antigen-stimulated males bred larger embryos compared with those in the control. Indices of female fertility depended on prevalence of cellular (Th1) or humoral (Th2) immune responses in antigen-stimulated males. Shift of Th1/Th2 balance resulted in higher preimplantation embryonic losses in females covered by males with a prevalence of cellular immune response; however, they bred larger embryos. Thus, it was established that activation of the immune system in males does not influence their reproductive abilities. This allows us, on the one hand, to explain the contribution of protective reactions of the organism in the increase in fertility of the mammals that inhabit territories with high specific abundance of parasites; on the other hand, it demonstrates new ways of the management of the reproduction of animals bred under human control.

[Factors of stress in a local population of water vole].

Physiological mechanisms of stress have a multiple influence on the implementation of the adaptive capacity of individuals. From this perspective, analysis of factors determining the stress level of animals in changing environment acquires important ecological and evolutionary significance. In the paper the results are presented of long-term studies carried out at a site of irrigative channel being populated by water voles every year. The results show that high stress level of males is observed in connection with shortages of environmentally significant resources--food and sexual partners. An activation of adrenocortical function due to resources deficit is formed as a result of exacerbation of intraspecific competition that occurs at both low food supply and reducion in proportion of females in the local population. The effects of these factors are mediated through changes in spatio-ethological structure of the studied populations which are manifested in increased overlapping of individual home ranges. Food supply and lack of females have different effects on the level of glucocorticoids in resident and nonresident males. These results indicate that social interactions in water vole is the real stress factor even when total population is significantly depleted, which in North Baraba occurs when territory watering is reduced and suitable summer habitats are not plenty enough.

[Scent as an element of subjective assessment of young males and females].

In 46 male and 19 female students who were both donors and recipients of scent samples, we studied effects of the menstrual cycle phase, reproductive health, sexual motivation, and sexual experience on subjective assessment of intensity and pleasantness of the sweat scent. The sweat samples were collected by the 60-min long exposure of a filter paper in the armpit. Then the male and female samples were reciprocally assessed olfactorily with respect to their intensity, unpleasantness/pleasantness, and association with male or female. It has been established that the cycle phase affects statistically significantly the coincidence of subjective assessments by the unpleasant/pleasant scale, which different recipients were giving to the same scent samples. Their coincidence in the non-receptive state is replaced by the non-coincidence at the receptive cycle phase, which indicates an increase in the contribution of the recipient's individual properties to the variability of scent assessments. In girls in the non-receptive state there is noted the reverse correlation between the strength and pleasantness of the male scent. In the receptive state, they become tolerant to intensive male scents. At non-regular menstrual cycles, the female scent is assessments by young males as less pleasant. At the same time, the girls themselves with the cycle disturbances assess higher the male scent samples as compared with reproducibly healthy girls. The first sexual experience decreases the subjective assessments given by girls to the male scent samples. The young males, on the contrary, increase assessments given by girls to the male scent samples. The young males, on the contrary, increase assessments of the female scent on having acquired the sexual experiment. Coefficients of correlation of the mutual assessments of scent pleasantness of young males and females are progressingly rising with increase of biological and social significance of the search for optimal partner. Thus, effect of psychophysiological and social factors on assessments of pleasantness of scent samples aggress well with requirements, to which the reproductively significant non-verbal signal should fit.

[The activation of specific immunity in male mice stimulates fertility of their breeding partners: the phenomenon of lot's daughters].

In previous experimental studies on laboratory mice, it was shown that activation of specific immunity by injection with sheep red blood cells (SRBC) lessens males' sexual olfactory attractiveness for intact females. However, reduced attractiveness can decrease males' reproductive efficiency only under the conditions of free mating, which is not obligatory for natural populations. The goal of this work was to study the influence of immunoenhancement on sexual behavior and reproductive output of outbred ICR male mice. Males, either injected with saline (control group) or SRBC-treated, were kept with intact females during 5 days after injection. While the number of fertile copulations was practically equal in both groups, the potential (ovulated ova) and actual (number of embryos) fecundity was significantly higher in females having been paired off with SRBC-treated males. Main reproductive effects were registered at 3-5th day after injection, when specific antibody-forming process starts and males' scent becomes less attractive for females. On the base of previous and present data, the hypothesis is proposed that if the quality of a non-alternative mating partner is compromised by activation of specific immunity, a female tries to maximize its reproductive output (due to low chance of repeated copulation). This responsibility for the next generation is reminiscent of the Bible story about Lot and his daughters, and may help to sustain the species existence under conditions of parasitic press.

[Reproductive physiology of the European mink: progesterone profile during pregnancy].

Reproductive physiology of the European mink, an endangered mustelid species, has been so far scarcely investigated. This study confirms that in European mink embryo implantation occurs on the day 12 of pregnancy. Progesterone profile during pregnancy has been compared in European mink and domestic ferret. In both species, progesterone increases at peri-implantation period, i. e. on day 8 and day 12 after mating. However, toward the end of pregnancy, on day 40 after mating, progesterone concentration in faeces of the ferrets decreases and does not differ from the initial level. In contrast, increase of progesterone during first 12 days of pregnancy in European mink is not as rapid as in ferrets, but in this species, there is no visible decrease of progesterone at the end of pregnancy. Peak levels of progesterone in faeces (day 8, 12) are lower in European mink than in ferret.

[Redistribution of immune defence in male mice exposed by female scent].

Since scent marks of mice are harbored by parasites, their sniffing during olfactory search of the mating partner leads to increase of the infection risk. A hypothesis that sexual signals can induce, along with the reproductive behavior, non-specific immune defense against respiratory infections is tested in the present paper. It was found in the experiments on outbred ICR mice that the scent of soiled bedding from cages with mature females stimulated leukocyte intervention to the upper air-ways. Migration of the white blood cells to lung tissue was accompanied with a more prominent immune and endocrine responeses to intranasal application of the bacterial lipopolysacharide (LPS). In particular, LPS administration to male mice treated by female scent was resulted in much greater amount of leukocyte aggregations in the peribronchial areas than that was found in the males kept isolated from the female signals. The female scent also enhanced adrenocortical response to LPS administration, which was coincided with statistically significant increase of IL-1beta concentration in hypothalamus. So, chemical signals of the mature female induce travel of white blood cells to the upper air-waya in the scent treated male mice. It can increase resistance to respiratory infections, on the one hand, and aggravates stress response to inhalation of the bacterial compounds, on the other hand.

[The sexual behavior, chemosignals and reproductive success in the male mice during activation of nonspecific immune response].

Hypothesis of reproductive compensation (Gowaty et al., 2007) suggests that constraining of free mating preference leads to reduction of the viability of progenies, which could be, partially, compensated by higher fecundity of the constrained parents. We consider infection as one of natural causes constraining female mating choice, because infection or immune response to infection can modulate male sexual demonstrations. Here we studied influence of LPS (bacterial endotoxin, activating non-specific immune response) on chemical attractiveness, sexual behavior and reproductive success in the outbreed male mice mated with the non-treated females. Single or repeated LPS administrations lead to increase of scent attractiveness of the male urine and soiled bedding for the non-estrus females. Injection of LPS (dose 50 mkg/kg) did not suppress the male sexual behavior. Time from pairing to successful mating correlates positively with the body mass of 16 day embryo. Embryos development, assessed by their body mass, was reduced in the females mated with the LPS-treated males. Higher level of plasma progesterone found in the females mated with the LPS-treated males, and shift of successful mating to the later time did not compensate reduction of embryo mass. At the same time the females mated with the LPS-treated males showed lower embryo lost in comparison with the females mated with the control males.

[Scent-marking costs and reproductive success in male mice of outbred strain ICR].

Since non-territorial mice have as good chances for reproduction as territorial mice, we suppose that low territorial compatibility is compensated by higher breeding activity. Based on the scent war hypothesis, proteinuria was used as the criterion of territorial compatibility for male mice. Correlation between proteinuria, assessed as the protein/creatinine ratio, and reproductive output was studied in 22 male mice. Each male was caged with two females for five days. HPLC of urinary samples showed that more than 70 per cent of the proteins lay within the range 15-20 kDa. This result is typical for the major urinary proteins (MURs) which play the key role in chemical signalling im mice. Individual variation of the protein/creatinine ratio had good repeatability in the resampled urinary samples. Male proteinuria correlated negatively with early behavioural response to females, with mating success during the first two days, and with prenatal development of the progeny. Thus, the tradeoff between scent-marking efficiency determined by MUPs and breeding efficiency equalized the reproductive success of male mice with different ability of territorial competition.

[Scent attractiveness and endocrine status in male students before and during a stress situation].

Scent attractiveness of sweat samples collected from male students before and during theoretical exams was assessed by female students. Five-rank scale was used for subjective assessment of the scent samples in term unpleasant/pleasant. Scent attractiveness depended on physiological conditions of both recipients and donors. Male students with low basal concentration of salivary cortisol smelt better than students with high level of cortisol. High level of salivary testosterone also was associated with low scent attractiveness of the male students, but only for the recipients in non-receptive phase of menstrual cycle. In all, the females who were in receptive phase of menstrual cycle assessed scent attractiveness of male students higher then the females in non-receptive phase. Exam stress coincided with increase of the salivary cortisol resulting in decline of scent attractiveness in male students. The negative effect of exam was most prominent in students that failed exam and in student who aspired to be the best but failed. So, the exam stress and basal variation of stress-related physiological indexes, such as salivary cortisol, are mirrored in male chemical signals, which are recognized by females.

[Immune system and behavioural strategies of reproduction under parasitic pressure]. / Immunnaia sistema i realizatsiia povedencheskikh strategii razmnozheniia pri parazitarnykh pressakh.

Since both reproduction and immunocompetence are costly, the negative reciprocal relationships between function were found in many species. Due to reproductive immunosuppression, some fraction of seasonally breeding populations of small mammals reproduces in the first breeding season, while others reproduce in the next one. Enhancement of breeding efforts under the increased risk of mortality and the reproductive delay until recovery are the polar variants of mating behavior of parasitized individuals. However the parasite-induced changes of odor, visual or acoustic signals limit the mating success of the infected hosts. The direct influence of the immune system, regularly activated by infections, to chemicals signals can be answer to the question: why these signals are honest? Decrease in strange infection risk by kin breeding can be a satisfactory strategy of an isolated population. Nevertheless, many species follow the inbreeding avoidance strategy, where the major histocompatibility complex (MHC) genes play key role in kin recognition. The advantage of MHC heterozygosity was found at the all steps of the breeding cycle; including mating choice, fertilization, pre- and postnatal development. So, the relationships between immune system and neuroendocrine regulation of behavior give proximal explanations of the evolutionary stable strategies of breeding behavior.

[Genetic-physiologic mother-fetus relationships and their effect on the adaptive traits of the offspring]. / Genetiko-fiziologicheskie vzaimootnosheniia mat'-plod i ikh vliianie na adaptivnye priznaki potomkov.

Using our own data and literature, we present analysis of genetic-physiological mechanisms providing for stable reproduction of mammals. Using multiparous species (such as minks, mice, water voles), we demonstrate that embryonic and early postnatal mortality of the offspring makes a significant contribution to stabilization of the actual fertility rate at a level optimal for the species. Studies of phenogenetics of fertility of inbred mice and their hybrids have demonstrated the definitive role of immunogenetic relationships between mother and fetuses in establishing of vitally important characteristics of the offspring. Antigenic differences between mother and fetuses observed in crosses between different strains and in experiments on allogenic transplantation of embryos provide stimulate the hormonal support of pregnancy (increase the level of progesterone) and the rate of embryonic development. It has been shown that antigenic stimulation of mother's immune system has a modifying effect on physiological and behavioral characteristics of the offspring and specifically on certain components of their reproductive success. In studies of the olfactory choice of mating partners by mouse and water vole females we established that mammals are capable of "predicting" the optimal phenotypic combination of parents leading to the most effective development of the offspring.

[Steroid hormone dynamics in cold adaptation of rats of different inbred strains]. / Dinamika steroidnykh gormonov pri adaptatsii k kholodu u krys raznykh inbrednykh linii.

In experiments on WAG, Sprague-Dawley and August rats the significance of genetic differences in the adrenocortical and gonadal response to long-term cold adaptation was demonstrated. The highest blood corticosterone level in WAG rats and the lowest one in August rats were seen following the 4-week exposure to 10 degrees C. A decreased blood testosterone concentration under cold conditions was observed only in August rats. Aldosterone excretion with the urine diminished during the cold exposure in WAG and Sprague-Dawley rats, being enhanced in August rats. The relationship is discussed between hormonal and metabolic changes under prolonged exposure to cold.