[Composition and distribution of the mitochondrial lineages of gray whales (Eschirichtius robustus) in the far eastern seas of Russia].

The frequency of occurrence of the mitotypes (control region, cytochrome b gene, and DN2 gene) has been studied for groups of gray whales feeding and growing along Chukotka Peninsula, Koryak Coast, eastern Kamchatka, and Sakhalin Island. The number of the mitotypes decreased dramatically from the northern waters southwards; however, the dominant mitotypes remained the same. Both mitochondrial lineages known for this species might be found for the whales gathering in the reproductive area along the Californian Coast in accordance with the comparison of the published and original data on the haplotypes of the control region. However, it has also been argued that similar sequences of the control region might be found in different mitochondrial genomes, and the analysis of only this site of mtDNA might lead to incorrect conclusions.

[Molecular genetic analysis of the shantar summer group of bowhead whales (Balaena mysticetus L.) in the Okhotsk Sea].

The results of molecular genetic analysis (full-length sequences of the cytochrome b gene and mtDNA control region and the allelic composition of 14 microsatellite loci) of 65 tissue samples from the endangered bowhead whale (Balaena mysticetus) population in the Sea of Okhotsk are presented. The data obtained enable the suggestion that the current state of the Sea of Okhotsk bowhead whale population is rather stable.

[The mountain weasel Mustela kathiah (Carnivora: Mustelidae): molecular and karyological data].

The karyotype of Mustela kathiah was first described. Its structure is most similar to the karyotype of M. altaica, differing inthe morphological peculiarites of five pairs of large chromosomes. A comparative analysis of mitochondrial genes in the species Mustela allowed us to clarify understanding of the place of M. kathiah in the system of the genus. The earlier hypothesized proximity of the species to a group of small weasels (altaica, nivalis) or to a group of South Asian species (strigidorsa, nudipes) was not confirmed. A high level of differences between M. kathiah of Vietnam and specimens from southern China in nucleotide sequences of the cytochrome b (7.7%) and ND2 (6-6.2%) genes was found. Perhaps these differences, manifested in populations of M. kathiah from different regions, are adaptive.

[Genetic structure of sable (Martes zibellina L.) from Eurasia based on distribution of mitochondrial lineages].

The phylogeography of the sable, which is a commercially valuable species, is extremely complicated and poorly investigated. Specifically, the effects of factors such as the range dynamics of the sable during the Pleistocene Epoch, the localization of glacial refugia, species distribution pattern in Holocene, and recent dramatic population decline, along with massive reacclimatization measures, on the species phylogeography remain unclear. Based on the sequence analysis of the control region of mitochondrial DNA from sables that inhabit different parts of the species range, a suggestion was made of the considerably high Pleistocene genetic diversity in sable, which was subsequently lost. The initial diversity of mitochondrial lineages is mostly preserved in the Urals, while in the eastern part of the range, it seems to have been depleted as early as before the last glacial maximum. On the other hand, the even greater depletion of the mitochondrial lineages observed in some populations of central Siberia can be associated with the dramatic population decline at the turn of the 20th century.

[Karyotypes divergence in superspecies complex Cricetulus barabensis sensu lato and their interrelationships in natural contact zones].

Interrelationships between three chromosomal forms of striped hamsters belonging to the superspecies complex Cricetulus barabensis sensu lato (Cricetidae, Rodentia), namely 'barabensis', 'pseudogriseus', and 'griseus', are examined from the standpoint of different biological/genetic species concepts. Craniometric data suggest that differences between the karyotypes are rather of subspecies level. Cytogenetic differences between the karyotypes are also not great and correspond to the level of chromosomal races within a single species. The analysis of mitochondrial gene for cytochrome b (cytb) indicates the level of differences between forms of about 2.3-4.1%. Such a level may correspond to intraspecific differences as well as to differences between allied species. Experiments on hybridization resulted in hybrid litters obtained in different mating combinations of karyotypes. Both hybrid males and females fertility was confirmed, too. In nature, there exist several zones where contact between karyotypes 'barabensis' and 'pseudogriseus' is possible. Within one of such zones, in Central Mongolia, two males with atypical karyotype were detected by use of chromosome analysis. With chromosomes number and form, this karyotype may correspond to the hybrid between second and subsequent generations. However, typing of gene cytb and the intron localized in Y-chromosome (DBY1) did not reveal any traces of recent or ancient hybridization. In the other zone where contact between the karyotypes is possible, in South Buryatia, 'barabensis' and 'pseudogriseus' populations are separated by the River Chika and the distance between them does not exceed 5 km. Nevertheless, no hamsters with non-standard karyotypes and no traces of gene flow are detected by karyological and molecular analyses of these populations. The results of Tajima's test, analysis of pairwise differences distribution and indices of nucleotide diversity obtained in the course of examining gene cytb full nucleotide sequence all suggest that both contact zones studied have formed long ago and the absence of gene flow cannot be explained by their forming in the recent past. Thus, the karyotypes studied appear to be evolutionary lines developing independently from each other.

[Decorative forms of hamsters Phodopus (Mammalia, Cricetinae): an analysis of genetic lines distribution and peculiarities of hair changes].

Three species of dwarf hamsters (genus Phodopus, family Cricetidae) inhabit some regions of Russia, Kazakhstan, Mongolia, and China, each having quite extensive range. In recent decades, the dwarf hamsters became widely spread all over the world, initially as laboratory animals and later as popular pets. By now, there is lot of decorative breed lines and colored forms of these animals. Comparison of mtDNA nucleotide sequences of dwarf hamsters acquired in pet shops of some countries in Europe, South-East Asia and North America with distribution of mtDNA haplotypes within natural ranges showed the limitation of decorative line founders' points of origin by one region for each of the species. All haplotypes found in decorative Dzungarian hamsters (Ph. sungorus) purchased ounside Russia coincide with or are significantly close to haplotypes spread in the southern part of West Siberia (Russia) and adjacent regions of Kazakhstan; haplotypes of decorative Campbell's hamster (Ph. campbelli) belong to haplogroup of this species natural populations inhabiting South Tyva (Russia); and all studied decorative Desert hamsters (Ph. roborovskii) had one hapotype specific for South-Eastern Kazakhstan. The review of the history of researches on dwarf hamsters biology allows to determine delivery of hamsters from mentioned regions to scientific laboratories and zoos by certain expeditions and/or researchers. Unlike hamsters with natural hair color, the colored hamsters have no normal hair. Their hair is dull and straggly. The hair differentiation (presence of different hair types and their size characteristics) gets broken and results in deformation, bending, and splitting of the shaft, cracks in cuticle, change of configuration and location of medulla, uneven development of cortex. It is assumed that these destructive changes are associated with genetic characteristics of these hamsters' colored forms.

[Analysis of genetic diversity of the Roborovski hamster (Phodopus roborovskii) in the northern part of its habitat].

An analysis of sequences of the cytochrome b gene and control region of mitochondrial DNA of 30 Roborovski hamsters (Phodopus roborovskii; Rodentia: Cricetinae) captured at ten geographical points from Zaisanskaya Depression (Kazakhstan) in the northwest to the Shilin-Gol area (China) in the southeast was conducted. The absence of a connection between the similarity of the discovered haplotypes and their geographical distribution allows us to assume that the modern genetic diversity of the species on the studied territory formed owing to migration waves from more southern areas.

[Genetic analysis of sympatric sable (Martes zibellina) and Marten (M. martes) populations in the northern urals].

Analysis of nucleotide sequences of the mitochondrial DNA (mtDNA) control region (495 bp) of sables (Martes zibellina) and martens (M. martes) from allopatric parts of the species ranges has shown a considerable interspecific genetic distance (3%). In sympatric populations of these species in the northern Urals, differences between two species-specific mtDNA lineages are still large; however, classification of each individual nucleotide sequence with one of the two lineages is not correlated with whether the given animal is phenotypically a sable, a marten, or a potential hybrid (the so-called kidas). This indicates a high degree of mutual introgression of the sable and marten mtDNAs in the northern Urals and suggests that their interspecific hybridization is common in the sympatric zone.

[Molecular genetic study of the beluga (Delphinapterus leucas: Cetacea, Monodontidae) summering in the southern Sea of Okhotsk as compared to North American populations].

The structure of the left part of the mtDNA control region has been studied in Delphinapterus leucas captured in summer in the southern Sea of Okhotsk. The data have been compared with published results of similar studies on D. leucas at different sites along the American coast. A high specificity of maternal lineages of D. leucas from the southern Sea of Ok.

[Effect of deficiency of dietary nitrogen on cellulose digestibility and nitrogen-fixing flora activity in the sibling vole Microtus rossiaemeridionalis]. / Vliianie defitsita dietarnogo azota na perevarimost' tselliulozy i aktivnost' azotfiksoruiushchei microflory u vostochnoevropeiskikh polevok Microtus rossiameridianalis.

The effect of food composition on nitrogen-fixing activity of the symbionts living in the digestive tract of the sibling vole Microtus rossiaemeridionalis was experimentally studied. In the control, the rodents were allowed to select any of three food mixes: protein-rich, protein-free with low cellulose content, and protein-free with high cellulose content. The voles consumed the food in a proportion corresponding to 16% of protein and about 6% of cellulose. Exclusion of the protein-rich food considerably increased cellulose consumption (up to 12%) and digestibility (from 35 to 64%). The changes in the consumed food composition were reflected in localization of nitrogenase activity in the digestive tract: the control level of nitrogen-fixing activity in the cecum was three times that in the proventriculus, while an inverse proportion was observed in the experimental groups. In all cases, the colon was the major locus of nitrogen fixation.

[Water and energy metabolism in representatives of the genus Martes and Mustela (Mammalia: Mustelidae)]. / O nekotorykh osobennostiakh vodnogo i énergeticheskogo obmena predstavitelei rodov Martes i Mustela (Mammalia: Mustelidae).

The quantities of consumed food and water, quantity and moisture content of faeces, as well as quantity and concentration of excreted urine were determined in representatives of Martes--marten (M. martes) and sable (M. zibellina)--as well as in polecat (Mustela putorius). Under the same cage conditions and free access to food, all three species had similar energy value of the daily diet. However, the level of drinking water consumption and the ratio between the quantities of arriving water and energy was reliably higher in both Martes species than in polecat. In addition, both marten and sable featured a much higher rate of evaporation loss in the overall water balance and, consequently, a higher quantity of heat dissipated with evaporation as compared to polecat. Comparison of the obtained and previous data (Sokolov et al., 1995; Rozhnov, 1991) allowed us to propose that the mentioned differences can be specific for representatives of Martes and Mustela genera irrespective of ecological specialization of particular species.

[Nitrogen requirements of Microtus rossiaemeridionalis]. / Potrebnost' v azote u vostochnoevropeiskoi polevki Microtus rossiaemeridionalis

Total nitrogen requirements in the small herbivorous rodent Microtus rossiaemeridionalis were studied. When provided with two kinds of standard laboratory food (about 20 and 0% digestible protein, respectively) ad libitum (cafeteria diet), the voles chose a diet of 14% protein. The total daily (with urine and faeces) nitrogen losses were, in this case, determined as 3.65 +/- 0. 60 mg N/g of body mass. When provided with a protein-free diet alone, the animals lost 0.90 +/- 0.05 mg N/g body mass per day, comprising about 3% of their body mass daily. It was proposed that the consumption of a low-fiber diet (about 4% in both kinds of food) could affect the gastrointestinal bacterial flora and, thus, lead to changes in the primarily herbivorous nitrogen metabolism.

[Nitrogen fixation--new fenomenon in rodent feeding]. / Azotofiksatsiia--novyi fenomen v pitanii gryzunov.

We have conducted a series of experiments in order to test hypothesis about the possible use of nitrogen fixation by small phytophagous mammals as a way to supplement their nitrogen balance. Two groups of red voles Clethrionomys rutilis were kept on rations with different protein nitrogen content. Three days later, the rate of nitrogen fixation was determined in different regions of the digestive tract. Nitrogen-fixing activity has been detected in the GI tract of all studied voles, specifically in those regions, where symbiocenoses were present; it was particularly high in animals of the experimental group under the conditions of dietary nitrogen limitation. A mixed culture of bacteria capable of nitrogen fixation has been isolated from the digestive tract of red voles.

[The characteristics of water metabolism and the resistance to dehydration of representatives of the family of mustelids (Carnivora: Mustelidae)]. / Osobennosti vodnogo obmena i ustoichivost' k degidratatsii u nekotorykh prestavitelei semeistva kun'ikh (Carnivora: Mustelidae).

Food consumption, total water intake, urine volume and concentration, and water content in feces were determined under the conditions of free access to drinking water and in its absence in some mustelids that inhabit territories with different water accessibility: Mustela putorius, M. eversmanni, M. lutreola, and M. vison. Specific features of water metabolism and resistance to dehydration in the studied species corresponded fairly well to differences in their ecology.

[A comparative study of the osmoregulating system in the hamsters Phodopus roborovskii and Phodopus sungorus]. / Sravnitel'noe izuchenie osmoreguliruiushchei sistemy u mokhnonogikh khomiachkov Phodopus roborovskii i Phodopus sungorus.

The hamster Phodopus roborovskii is adapted to live in desert, Phodopus sungorus in less arid regions. Hamsters of both species have rather close values of blood serum osmolality and ion concentration, after dehydration the value of urine osmolality is found to be equally high. The microdissection of the kidney did not reveal any difference in the structure and arrangement of nephrons in cortex and medulla. According to the results of immunocytochemical analysis of the hypothalamo-hypophyseal neurosecretory system of hamster Phodopus roborovskii, compared to Phodopus sungorus, has a smaller quantity of vasopressin-positive neurons, which is likely to be a result of a release of larger quantities of vasopressin in long-term dehydration. It is suggested that of importance in the animal adaptation to life in arid condition may be not only morphofunctional reorganization of kidney but also of the hypothalamo-hypophyseal system which is involved in permanent secretion of vasopressin.

[The functional capacities of the kidneys in hamsters of the genus Phodopus]. / Funktsional'nye vozmozhnosti pochek khomiachkov roda Phodopus.

Studies have been made on total osmolarity and concentration of Na and K in the urine, as well as on the level of diuresis in three species of the hamsters (Phodopus sungorus, Ph. campbelli, Ph. roborovskii) under the conditions of presence or absence of wet food and during water and salt loading. Mean value of osmotic concentration of the urine at free access to wet food varied within 2,600-3,500 mosmol, under the condition of dry-eating--within, 5,600--6,400 mosmol, which indicates the existence of a highly effective renal mechanism of water economy in the investigated species. At the same time, the capacity to maintain constant body weight in animals fed only air-dried food was noted only in separate specimens. In experiments with water load (30 microliters/g), the volume of fluid excreted within 4 hours amounted up to 87% of the load for Ph. sungorus, 70%--for Ph. campbelli and 43% for Ph. roborovskii. Studies on sodium and potassium contents of the urine under the conditions of dry-eating and salt loading indicate that the species investigated are capable of cation concentrating, yet they do not reveal any special mechanisms accounting for the excretion of excessive salts.