Phylogenetic Relationships of Burbot (Lota lota L., 1758) of the Volga-Kama River Basin Inferred from the Analysis of Mitochondrial DNA Markers.

The phylogenetic relationships of burbot (Lota lota L., 1758) of the Volga-Kama River basin are reconstructed for the first time. The sequences of the gene cytochrome b and the mtDNA control region obtained for 44 samples from the Kama River and Mezhevaya Utka River (the Volga River tributaries) are studied. New haplotypes of both markers were revealed. The results of phylogenetic reconstructions based on cytochrome b and control region mtDNA do not contradict the existing ideas about the phylogenetic structure of the species, and indicate inclusion of burbot from the Volga-Kama basin in Eurasian haplogroup. According to obtained data, the Volga-Kama River basin could play an important role in shaping the genetic diversity of burbot in Europe, and during certain periods it served as a corridor connecting the river systems of the European and Asian parts of the species range.

Isolation of primary osteoblast cell lines from adult rat and rat embryos and their use as models for in vitro biocompatibility tests of nanostructured titanium-based implants.

Methods for obtaining osteoblast cultures from the calvaria of adult Wistar rats and 12-day-old embryos of these rats have been adapted for studying the biocompatibility and ossointegration of titanium-based implants. The osteoblast morphology and their differentiation into osteocytes on a titanium matrix with specially treated surface have been studied. It has been confirmed that two cultures of diploid rat cells obtained in the study can serve as efficient models for preclinical in vitro testing of nanostructured titanium implants for biocompatibility and osseointegration.

[The genetic diversity of burbot (Lota lota L., 1758) of Western Siberia (the analysis of the mtDNA control region polymorphism)].

The genetic variability of burbot (Lota lota L., 1758) inhabiting the Ob-Irtysh and Taz river basins in Western Siberia has been studied based on the polymorphism of the hypervariable fragment of mtDNA control region (407 bp). The analysis of 134 fish samples revealed 30 haplotypes, 23 of which were new. Among haplotypes, previously detected in Eurasia and North America, EB30 was the most frequently found in Western Siberia (45.5% frequency). The results of our study are in agreement with previous research pointing to the genetic differentiation of two burbot subspecies, L. l. lota and L. l. maculosa, and indicate that burbot inhabiting the Ob-Irtysh and Taz river basins belong to the Eurasian-Beringian clade (nominative subspecies L. l. lota). However, a high genetic diversity of burbot in Western Siberia, along with a relatively high differentiation of burbot groups within studied territory, points to a regional specificity of burbot population.

[Analysis of Microsatellite DNA in Rodents from Eastern Urals Radioactive Trace Zone and Contiguous Territories].

The variability of four microsatellite loci of rodents, caught from the head part of Eastern Urals Radioactive Trace (EURT), along with the rodents inhabiting contiguous zone with background radiation level and distant-reference territory, was analyzed forthe first time. Differences in the parameters of genetic diversity between northern red-backed voles from the EURT zone and from the reference population were detected. An increase in some indices of genetic diversity in animals from a contiguous to the EURT zone was found; this is probably associated with animal migration and configuration of the area of pollution. A transfer of radiation-induced effects to the contiguous territories and a decrease in the possibility of fixation of adaptations in a series of generations of mobile rodent species in the area of local radioactive pollution are consequences of migrations. The results of the study make it possible to recommend microsatellite markers for the analysis of radiation-induced effects in rodents as model objects of radioecological monitoring.

First data on genetic diversity of burbot (Lota lota L.) in the Western Siberian.

Analysis of genetic diversity of burbot (Lota lota Linneus, 1758) mitochondrial control region (mtCR) haplotypes from geographically distant localities in the Ob-Irtysh River basin in comparison with distribution of known burbot haplotypes was conducted. mtCR fragments from burbot samples, obtained in two localities (longitudinal part of the Irtysh near Tobolsk and the Sob River, a left-bank tributary of the Ob River), were sequenced.

[Interrelationship between the level of chromosomal aberrations and demographic parameters].

The interrelationship between the level of chromosomal abnormalities and demographic parameters has been studied using individuals from the natural population of bank vole (Clethrionomys glareolus) from a locality within the Middle Ural, of the southern taiga subzone (57 degrees 15' N, 58 degrees 44' E). Routine methods of cytogenetic analysis are applied to examination of variability in the frequency of structural chromosomal aberrations, gaps and changes in number of chromosomes in bank voles' bone marrow cells. Influence of demographic parameters, namely population density, age, sex, and reproductive status, on cytogenetic characteristics is estimated with the help of log-linear analysis. It is shown that population increasing in size leads to a decrease in the share of individuals characterized by higher frequency of cells with structural chromosomal abnormalities and gaps. This outcome appears to be in concordance with the notion of less amount of mutations in somatic cells to be favorable for organisms' survival rate. Such a pattern could emerge as a consequence of natural selection causing reorganization of genetic structure of a population. Alternatively, these changes may be a by-product of other processes accompanying population dynamics. High population density results in an increase of a share of individuals among young-of-the-years with higher frequency of cells subjected to abnormalities in chromosome number. Similar effects are possible as a result of asymmetric interference competition of adults in relation to younglings. Our data indicate that the share of animals having higher frequency of somatic cells with structual chromosomal aberrations and numerical chromosomal abnormalities is essentially increased by age, which is in accordance to theoretical concepts and experimental data. Gender and participation in reproduction do not render significant influence on the level of cytogenetic instability.

[Factors of maintaining chromosome polymorphism in common vole Microtus arvalis Pallas, 1779: reduced fertility and meiotic drive].

The common vole Microtus arvalis (the form obscurus) exhibits polymorphism of a pericentric inversion in chromosome pair 5 throughout the species range. In the Urals populations, the frequency of an acrocentric variant of the heteromorphic chromosome is very low (on average 3.2%) and virtually does not change annually. The factors of maintaining stable chromosomal polymorphism in the common vole were studied under conditions of a laboratory colony. Heterozygous and homozygous for the acrocentric chromosome females showed a significant reduction of the reproductive output irrespective of the male karyotype. This effect was manifested mostly in litter size at birth. A number of cytogenetic and exophenotypic characteristics, as well as parent--offspring transmission of this chromosome in crosses of various types, were examined. We have found meiotic drive in favor of the acrocentric, as a result of which the frequency of the acrocentric (without taking into account the postnatal mortality) totaled over all cross variants (0.48) was significantly higher than that expected with random segregation (0.42). It is likely that meiotic drive of the acrocentric largely compensates for the reduced fertility of its carriers, being among the factors of maintaining it in natural populations.