A variation of secondary sex ratio in blue fox (Alopex lagopus L.)

The effects of several genotypic and paratypic factors on the secondary (at birth) sex ratio was analyzed in blue fox bred in captivity. In particular, variation of sex ratio was for the first time studied as dependent on sire's age (without considering dam's age), the ages of both sire and dam, and the lines of both parents. The initial data were obtained from the Pushkino breeding facility, Moscow oblast. In total, 15,396 puppies were analyzed. The frequency of males (P) in this population was 0.551 +/- 0.004 (confidence interval 0.543 < p < 0.559). Parents' ages and litter size had no effect on the proportion of males in the progeny. In one of the two blue fox subpopulations under study, dam's line proved to be associated with a significant departure of sex ratio to a higher proportion of males, suggesting the effect of genotypic factors on the variation of secondary sex ratio in blue fox.     

The effect of artificial selection for coat color on fitness in a farm population of the sable (<Emphasis Type="Italic">Martes zibellina</Emphasis>)

The relationship between the response to artificial selection for darker coat color and fitness in a farm population of the sable (Martes zibellinaL.) from the Pushkinskoe Fur Farm (Moscow oblast) was studied. The selection was performed during 41 years. By the moment of the study, a response to the selection for this character had been obtained: the coat color in the selected population had become darker, and the proportion of black animals in it increased. In addition, sables with black heads, which were absent in the original population, had appeared. Artificial selection was accompanied by a decrease in the fitness of the selected population, which was expressed in decreased female reproductive capacity parameters (the fertility, maturation rate, and duration of the reproductive period). A selection technique consisting in the use of only highly fertile animals in the selection originally made it possible to restore the fitness parameters to the initial level almost without a decrease in the dark shade of the fur. However, further selection led to a drastic decrease in fitness that could not be precluded by any selection method used. The possible ways to overcome this unfavorable effect of artificial selection are discussed.     

The effect of artificial selection for coat color on fitness in a farm population of the sable (Martes zibellina)

The relationship between the response to artificial selection for darker coat color and fitness in a farm population of the sable (Martes zibellina L.) from the Pushkinskoe Fur Farm (Moscow oblast) was studied. The selection was performed during 41 years. By the moment of the study, a response to the selection for this character had been obtained: the coat color in the selected population had become darker, and the proportion of black animals in it increased. In addition, sables with black heads, which were absent in the original population, had appeared. Artificial selection was accompanied by a decrease in the fitness of the selected population, which was expressed in decreased female reproductive capacity parameters (the fertility, maturation rate, and duration of the reproductive period). A selection technique consisting in the use of only highly fertile animals in the selection originally made it possible to restore the fitness parameters to the initial level almost without a decrease in the dark shade of the fur. However, further selection led to a drastic decrease in fitness that could not be precluded by any selection method used. The possible ways to overcome this unfavorable effect of artificial selection are discussed.     

Elevated temperature prolongs long‐term effects of a pesticide on Daphnia spp. due to altered competition in zooplankton communities

Considerable research efforts have been made to predict the influences of climate change on species composition in biological communities. However, little is known about how changing environmental conditions and anthropogenic pollution can affect aquatic communities in combination. We investigated the influence of short warming periods on the response of a zooplankton community to the insecticide esfenvalerate at a range of environmentally realistic concentrations (0.03, 0.3 and 3 μg L^?1) in 55 outdoor pond microcosms. Warming periods increased the cumulative water temperature, but did not exceed the maximum temperature measured under ambient conditions. Under warming conditions alone the abundance of some zooplankton taxa increased selectively compared to ambient conditions. This resulted in a shift in the community composition that had not recovered by the end of the experiment, 8 weeks after the last warming period. Regarding the pesticide exposure, short‐term effects of esfenvalerate on the community structure and the sensitive taxa Daphnia spp. did not differ between the two temperature regimes. In contrast, long‐term effects of esfenvalerate on Daphnia spp., a taxon that did not benefit from elevated temperatures, were observed twice as long under warming than under ambient conditions. This resulted in long‐term effects on Daphnia spp. until 4 months after contamination at 3 μg L^?1 esfenvalerate. Under both temperature regimes, we identified strength of interspecific competition as the mechanism determining the time until recovery. However, enhanced interspecific competition under warming conditions was prolonged and explained the delayed recovery of Daphnia spp. from esfenvalerate. These results show that, for realistic prediction of the combined effects of changing environmental factors and toxicants on sensitive taxa, the impacts of stressors on the biotic interactions within the community need to be considered.     

Comparative clinical and epidemiological evaluation of beta-lactam antibiotics in the treatment of intraabdominal infections]

We performed a retrospective, comparative study to evaluate efficacy, safety and economic outcomes of empiric cefoperazone/sulbactam monotherapy compared with the meropenem, imipenem/cilastatine and combination of cefepime plus metroindazol in patients with intra-abdominal infection. A total of 468 patients diagnosed with intra-abdominal abscess, peritonitis, pancreatitis were included in the study (the severity of infection according to scale APACHE II was less than 15). Patients were randomized to be treated with either 500 mg meropemen i.v. every 8 hours or 500 mg imipenem/cilastatine i.v. every 8 hours or 2 g cefepime i.v. every 12 hours plus 500 mg metronidazol twice daily or cefoperazone/sulbactam 2 g daily administered every 12 hours. Overall positive clinical responses (cure or improvement) were achieved at the end of treatment for 87.5 patients in meropenem group, 86.6% in the imipenem/cilastatin group, 85.3% in the cefepime group and 86.8% in cefoperazone/sulbactam group. Total cost of the treatment per 100 patients with intra-abdominal infections for cefoperazone/sulbactam was 1957031 roubles, for combinations of cefepime with metronidazol--2497815 roubles. For carbapenem group cost achieved for meropenem--3085291 rub., for imipenem/cilastatin--2653388 roubles. Rate "cost-effectiveness" in total: 784.47$ for cefepime, and 834.39$ for imipenem/cilastatine, 970.21$ for meropenem and 615.4$ for cefoperazone/sulbactam. The most expensive treatment was considered to be with meropenem and imipenem/cilastatine, main share is determined by initial cost of preparations. Less expensive was treatment by cefoperazone/sulbactam with cefepime and by metronidazol.     

Statistical analysis of secondary sex ratio variation in sable Martes zibellina L

The secondary sex ratio in sable Martes zibellina L. maintained in captivity was estimated for the first time ever. The data obtained at the Pushkin pedigree breeding farm (Moscow oblast) in 1982 through 1987 were analyzed. In total, 1705 litters of 414 females were examined. The total frequency of male births (P) was 0.527 +/- 0.007; the 95%-confidence interval of p (the probability of birth of a male) was within the limits 0.513 < p < 0.541, and the deviation from the expected 1:1 ratio was statistically significant. No effect of parental age and litter size on the number of male progeny was found. This may indicate a small influence of the parental hormonal and immunological status on sex ratio, which was reported in many other mammal species including those related to sable. Apparently, there is an evolutionary mechanism underlying the stable excess of males in sable litters.     

Cyclic adenosine-3',5'-phosphate and guanosine-3',5'-phosphate in mouse plasma during administration of chemical compounds with different degrees of radioprotective effectiveness

A study was made of seven radioprotective agents of different chemical classes (sulfur-containing, indolylalkylamines, and imidazol, urea and pyridasine derivatives) and also of their six structural analogs without radioprotective properties on the content of cyclic nucleotides in blood plasma and on the postirradiation survival of mice. There was a correlation between the ability of the preparations to increase the level of cyclic adenosine-3',5'-monophosphate and their radioprotective properties; with guanosine-3',5'-monophosphate, this correlation was absent.     

Inheritance of litter size at birth in farmed arctic foxes (Alopex lagopus, Canidae, Carnivora)

Natural populations of the arctic fox (Alopex lagopus, Canidae, Carnivora) differ drastically in their reproductive strategy. Coastal foxes, which depend on stable food resources, produce litters of moderate size. Inland foxes feed on small rodents, whose populations are characterized by cycling fluctuation. In the years with low food supply, inland fox populations have a very low rate of reproduction. In the years with high food supply, they undergo a population explosion. To gain insight into the genetic basis of the reproductive strategy of this species, we performed complex segregation analysis of the litter size in the extended pedigree of the farmed arctic foxes involving 20,665 interrelated animals. Complex segregation analysis was performed using a mixed model assuming that the trait was under control of a major gene and a large number of additive genetic and random factors. To check the significance of any major gene effect, we used Elston-Stewart transmission probability test. Our analysis demonstrated that the inheritance of this trait can be described within the frameworks of a major gene model with recessive control of low litter size. This model was also supported by the pattern of its familial segregation and by comparison of the distributions observed in the population and that expected under our model. We suggest that a system of balanced polymorphism for litter size in the farmed population might have been established in natural populations of arctic foxes as a result of adaptation to the drastic fluctuations in prey availability.     

The Rapoport effect is detected in a river system and is based on nested organization

Aim To test two hypotheses: (i) the Rapoport effect is valid for a river continuum, particularly regarding the altitudinal distribution of mayflies over the large‐scale continuum from alpine stream to medium‐sized lowland river, and (ii) the observed Rapoport effect is based on high nestedness of the meta‐assemblage, implying the presence of a common species pool and species‐thinned nested subsets. Location Geometric centre of Eurasia, south‐western Siberia, Russia. Methods Regression analysis of breadth and midpoints of species altitudinal ranges, species richness and altitude. Comparison of the observed patterns with the null model predicted by the mid‐domain effect and conventional null hypothesis. Nestedness analysis. Results The Rapoport effect was explicitly demonstrated: species altitudinal ranges expanded with increase in the ranges’ midpoints and average per‐altitude ranges increased with increase in altitude and concurrent decrease in species richness. The significance of each trend was confirmed with respect to both the null models applied. Nestedness analysis has revealed that the observed Rapoport effect is based on nested organization of the meta‐assemblage over the river altitudinal/longitudinal gradient: a common species pool at low (but not the lowest) altitudes and nested subsets of this pool at higher altitudes. Main conclusions This study for the first time credibly shows the altitudinal Rapoport effect in freshwaters. This finding demonstrates cross‐habitat‐type consistency of the Rapoport effect, but does not suggest that the Rapoport effect is an obligatory attribute of river systems or lotic organisms. High nestedness underlying the observed Rapoport effect together with some previous studies indicate that the Rapoport effect in altitudinal and bathymetric gradients in general may be based on nested organization. The study highlights a deficiency of cross‐habitat‐type analyses of macroecological patterns (i.e. over terrestrial, freshwater and marine habitats).     

Toxicity and radio-protective properties of pyridazine derivatives

In experiments in irradiated (CBA X S57B1)F1 mice a study was made of toxicity and radioprotective efficiency of some pyridazine and pyridazine dione derivatives. Some of these substances were shown to have a moderate protective action when administered intraperitoneally. A correlation was revealed between the chemical structure and the radioprotective properties of the compounds.