Intraspecific Variation of Brown Rat Rattus norvegicus in Russia by D-Loop mtDNA Data.

For the first time in Russia, the intraspecific structure of the brown rat Rattus norvegicus was studied using the mitochondrial control region (D-loop) as a molecular marker. The mtDNA sequence was determined in brown rats from eight regions of European and Asian Russia. Three rat clades were identified, including one in European Russia and two in Asian Russia. The synanthropic subspecies R. n. norvegicus was found to have two, European and Asian, lineages. The European lineage included haplotypes from central and southern regions of Russia, and the Asian lineage included haplotypes from Eastern Siberia and the Russian Far East. The exoanthropic subspecies R. n. caraco from the Russian Far East formed a separate genetic lineage.

[Microsatellite loci variation and investigation of gene flow between two karyoforms of Cricetulus barabensis sensu lato (Rodentia, Cricetidae)].

We examine the diversity of six microsatellite loci and partial RAG1 exon of "barabensis" and "pseudogriseus" karyoforms in Cricetulus barabensis sensu lato species complex. A total of 435 specimens from 68 localities ranging from Altai to the Far East are investigated. The results of the population structure analysis (factor analysis and NJ tree based on Nei genetic distances) support subdivision into two well-differentiated clusters corresponding to the two karyoforms. These karyoforms are also well differentiated by the level of microsatellite variability. In several "barabensis" specimens, we found microsatellite alleles that are common in "pseudogriseus" populations but are otherwise absent in "barabensis." Most of these specimens originate from a single population in one of the zones of potential contact between karyoforms, Kharkhorin in Central Mongolia. These molecular results are consistent with previously published karyological data in suggesting that rare hybridization events between the two chromosomal races occur in nature.

[Features of the B chromosome in Korean wood mice Apodemus peninsulae (Thomas, 1906) from Transbaikalia and the Far East identified by the FISH method].

Korean field mice (Apodemus peninsulae) are widely distributed throughout northeastern Asia, including the Russian Far East, northern China, the Korean peninsula, Sakhalin, and Hokkaido. This mouse species is characterized by a high frequency of animals with B chromosomes differing in their number, morphology, and DNA composition in different geographical regions. For the first time a comparative analysis of DNA probes from B chromosomes with metaphase chromosomes of mice from Transbaikalia, the Far East (including the Russian Far East), Japan, and South Korea was conducted by in situ hybridization. B chromosomes in mice from the Russian Far East were shown to exhibit low variability in DNA content; however, the DNA composition of B chromosomes in species from Transbaikalia and Japan were highly variable. B chromosomes in A. peninsulae from the South Korean population demonstrate minor differences from those from the Russian Far East. We discuss the origin of B chromosomes in the studied region in comparison with previously obtained data for mice from Siberia and the Baikal region, as well as the dispersal routes of the Korean field mouse.

[Tandem repeats in rodents genome and their mapping].

Tandemly-repeated sequences represent a unique class of eukaryotic DNA. Their content in the genome of higher eukaryotes mounts to tens of percents. However, the evolution of this class of sequences is poorly-studied. In our paper, 62 families of Mus musculus tandem repeats are analyzed by bioinformatic methods, and 7 of them are analyzed by fluorescence in situ hybridization. It is shown that the same tandem repeat sets co-occure only in closely related species of mice. But even in such species we observe differences in localization on the chromosomes and the number of individual tandem repeats. With increasing evolutionary distance only some of the tandem repeat families remain common for different species. It is shown, that the use of a combination of bioinformatics and molecular biology techniques is very perspective for further studies of the evolution of tandem repeats.

[Polymorphism and Genetic Structure of Microtus maximowiczii (Schrenck, 1858) (Rodentia, Cricetidae) from the Middle Amur River Region as Inferred from Sequencing of the mtDNA Control Region].

The genetic variability of the mitochondrial DNA control region sequences was estimated for the Maximowicz's vole Microtus maximowiczii from the Middle Amur River region located between the confluence of Amur River with Ussuri River and Zeya River. The species as a whole was characterized by a high level of genetic variability. For each individual sample, low nucleotide diversity was observed, except for two samples in which a more than twofold increase in this index was revealed. The presence of the contact zone of two genetically distinct populations in the area between Bira and Bidzhan rivers is suggested.

[Comparative Analysis of DNA Homology in Pericentric Regions of Chromosomes of Wood Mice from Genera Apodemus and Sylvaemus].

In the present study, an analysis of the DNA homology of the pericentric chromosomal regions and pericentric heterochromatin in distantly related species of wood mice (species from the Apodemus genus, as well as from the Apodemus and Sylvaemus genera) was conducted by fluorescent in situ hybridization (FISH) with microdissected DNA probes obtained from the corresponding chromosomal regions of these species. Cross-hybridization of microdissected DNA probes obtained from pericentric C-positive blocks of chromosomes of Sylvaemus species with chromosomes of Apodemus species, as well as DNA probes from pericentric C-positive blocks of chromosomes of Apodemus species with chromosomes of Apodemus and Sylvaemus species, showed that DNA repeats homologous to the pericentric regions in other species represented. dispersed repeats in C-negative chromosomal regions, as well as in several regions bordering pericentric C-positive and C-negative regions in heterochromosomes and autosomes and in distal regions in the long arms of several autosomes. The results indicate that the level of DNA homology in pericentric chromosomal regions decreases with an increase in the differentiation level and a decrease in the kinship between the compared forms and species of wood mice. Most likely, degeneration of the DNA repeats is accompanied by a gradual destruction of repeat clusters and their replacement by new, nonhomologous repeats in almost all pericentric regions (some old repetitive sequences might be "extruded" into interstitial or telomeric regions of chromosomes). These processes, which are observed in some species from Sylvaemus genus in distantly related species of Sylvaemus and Apodemus genera, have almost achieved the final stages.

[Chromosomal variability of the Maximowicz's vole Microtus maximowiczii (Rodentia, Cricetidae, Microtus)].

The numeration of the chromosomes, which can be used to describe the karyotypes of various chromosomal forms from different geographical regions, has been proposed for the Maximowicz's vole Microtus maximowiczii. Application of FISH analysis has allowed us to show homology of Robertsonian rearregement (11/20) inkaryotypes of voles from Transbaikalia (2n = 41 and voles from Norsky reservation in Amur Region (2n = 40).

[B chromosome morphotypes of Apodemus peninsulae (Rodentia) from the Russian Far East].

Polymorphism of B chromosome morphotypes in the natural populations of the Korean field mouse Apodemus peninsulae (n = 367) has been studied in five regions of the Russian Far East: Magadan and Amur regions, the Jewish Autonomous region, Khabarovsk and Primorskii regions. Six groups of B chromosome morphotypes have been described on the size and morphological parameters. On the basis of their combinations 78 cell clones have been revealed, 23 of which are found in the animals with a stable karyotype and 76--in mosaics. The mosaics have also more diverse and unique combinations of B chromosome morphotypes. No differences between the geographic and local populations of mice on the studied characteristics have been found. Homogeneous structure of DNA in the B chromosomes of this species at the territory of the Russian Far East, as shown previously, allowed us to combine the numerical and dimensional data for each clone by introduction conditional "mass quantity" of B chromosomes (mB index). The leading role of natural selection in production of "critical" mass of supernumerary chromosomes in individuals with a stable karyotype and the weakening of its role in mosaics has been suggested.

[Comparative FISH analysis of C-positive regions of chromosomes of wood mice (Rodentia, Muridae, Sylvaemus)].

The homology of DNA of C-positive centromeric regions of chromosomes in wood mice of the genus Sylvaemus (S. uralensis, S. fulvipectus, S. sylvaticus, S. flavicollis, and S. ponticus) was estimated for the first time. DNA probes were generated by microdissection from the centromeric regions of individual autosomes of each species, and their fluorescence in situ hybridization (FISH) with metaphase chromosomes of representatives of all studied wood mouse species was carried out. Unlike in the chromosomal forms and races of S. uralensis, changes in the DNA composition of the chromosomal centromeric regions in the wood mouse species of the genus Sylvaemus (including closely related S. flavicollis and S. ponticus) are both quantitative and qualitative. The patterns of FISH signals after in situ hybridization of the microdissection DNA probes with chromosomes of the species involved in the study demonstrate significant differences between C-positive regions of wood mouse chromosomes in the copy number and the level of homology of repetitive sequences as well as in the localization of homologous repetitive sequences. It was shown that C-positive regions of wood mouse chromosomes can contain both homologous and distinct sets of repetitive sequences. Regions enriched with homologous repeats were detected either directly in C-positive regions of individual chromosomes or only on the short arms of acrocentrics, or at the boundary of C-positive and C-negative regions.

X-Y chromosome synapsis and recombination in 3 vole species of Asian lineage of the genus Microtus (Rodentia: Arvicolinae).

The pattern of X-Y chromosome pairing in male meiosis is an important taxonomic feature of grey voles of the genus Microtus. Asynaptic sex chromosomes have been found in the majority of species of the Palearctic phylogenetic lineage of this genus, while normal X-Y synapsis has been observed in the species of subgenus Pallasiinus belonging to the Asian phylogenetic lineage. We analyzed sex chromosome pairing and recombination in M. maximowiczii, M. mujanensis and M. fortis which also belong to the Asian phylogenetic lineage (subgenus Alexandromys). Using immunostaining for the proteins of the synaptonemal complex (SCP3) and recombination nodules (MLH1) we demonstrated that X and Y chromosomes of these species paired and recombined in a short subtelomeric region. This indicates that the sex chromosomes of these species retain an ancestral fully functional pseudoautosomal region, which has been lost or rearranged in the asynaptic species of the genus Microtus.

[Comparative FISH analysis of C-positive blocks of centromeric chromosomal regions of pygmy wood mice Sylvaemus uralensis (Rodentia, Muridae)].

The composition and homology of centromeric heterochromatin DNA has been compared in representatives of the Asian race and two chromosomal forms (Eastern European and Southern European) of the European race of the pygmy wood mouse Sylvaemus uralensis by means of in situ hybridization with metaphase chromosomes of microdissection DNA probes obtained from centromeric C-blocks of mice of the Southern European chromosomal form and the Asian race. Joint hybridization of both DNA probes yielded all possible variants of centromeric regions in terms of the presence of repetitive sequences homologous to those of some or another dissection region, which indicates a diversity of centromeric regions differing in DNA composition. However, most variations of the fluorescent in situ hybridization (FISH) patterns are apparently related to quantitative differences of repetitive elements of the genome. Experiments with the DNA probe obtained from the genome of the Southern European form of the pygmy wood mouse have shown that the number of intense FISH signals roughly corresponds to the number of large C-segments in representatives of the European race, which is characterized by a large amount of the centromeric C-heterochromatin in the karyotype. However, intense signals have been also detected in experiments on hybridization of this probe with chromosomes of representatives of the Asian race, which has no large C-blocks in the karyotype; thus, DNA sequences homologous to heterochromatic ones are also present in nonheterochromatic regions adjacent to C-segments. Despite the variations of the numbers of both intense and weak FISH signals, all chromosomal forms/races of S. uralensis significantly differ from one another in these characters. The number of intense FISH signals in DNA from the samples of pygmy wood mice from eastern Turkmenistan (the Kugitang ridge) and southern Omsk oblast (the vicinity of the Talapker railway station) was intermediate between those in the European and Asian races, which is apparently related to a hybrid origin of these populations (the hybridization having occurred long ago in the former case and recently in the latter case).

[Polymorphism of a short fragment of the mitochondrial genome control region (D-loop) in the Siberian roe deer Capreolus pygargus Pallas, 1771 (Artiodactyla, Cervidae) from the Russian Far East].

Genetic diversity of Siberian roe deer Capreolus pygargus, 1771 from the Russian Far East was studied based on polymorphism analysis of a mtDNA control region fragment (390 bp). Three phylogenetic lines were found in the animals examined. The trend for change of haplotypes of different phylogroups was shown to occur from north to south in Sikhote-Alin. The haplotype distribution of Siberian roe deer in the Russian Far East correlated with data on morphologiocal variability.

[Voles (Microtus Schrank, 1798) of the Russian Far East: allozymic and karyological divergence].

The intraspecific and interspecific differentiations of voles of the Russian Far East with respect to allozymic and karyotypic characteristics have been studied. The morphologically similar but karyotypically different species Microtus oeconomus, M. fortis, M. maximowiczii, and M. sachaliensis are characterized by considerable allozymic differentiation. In these voles, the allozymic differentiation has been found to increase in the order adjacent populations-subspecies-species. The interspecific allozymic differentiation of the chromosomally polymorphic M. maximowiczii-M. evoronensis-M. mujanensis does not exceed the intraspecific differences in M. oeconomus, M. fortis, and M. maximowiczii. The results are analyzed in terms of the allopatric and stasipatric models of speciation. The taxonomic status of M. maximowiczii gromovi is considered.

[B chromosome number polymorphism and mosaicism of the Korean field mouse Apodemus peninsulae (rodentia) in the Russian Far East].

Karyotype analysis of the Apodemus peninsulae (n = 355) from 41 trapping points from the Russian Far East made it possible to reveal B chromosomes in 87.9 % animals, where 61.7% among them were mosaics. Different levels of B chromosome numbers variability such as inter- and intrapopulational, and intraindividual (mosaicism) as well have been studied. It has been revealed that frequencies of occurrence of individuals with B chromosomes and mosaicism were not constant between different population's samples. The range of the modal B chromosome number variations and the xB index variability (from 0 to 4, xB averaged 1.67) both have been fist investigated in different samples and populations of this species. Individuals with the predominant B chromosome numbers (as a rule, 0-2) have been revealed in both groups of animals (with stable and mosaic karyotypes) but the frequency was different in the geographical regions. The spectra of B chromosome variability were wider in mosaics (0-7) in comparison with animals with stable karyotypes (0-4). High frequency of individuals with B chromosomes and with mosaicism, and their significance for the species is discussed. The adaptive role of the low number of B chromosomes (1-2) is assumed and the B chromosome system seems not to be balanced in the species in whole.

[Karyological and allozyme variability of far eastern voles Microtus fortis Büchner, 1889 (Cricetidae, Rodentia) from the Russian Far East].

Karyological (G-, C-, and NOR-banding) and allozyme analyses were carried out for island and continental populations of the vole Microtus fortis from the Far East of Russia. Variability of the autosome pair 7 was found. The presence of variation in the number of telomere heterochromatin blocks in the populations of Far Eastern voles was confirmed. NOR-staining of the Far Eastern vole chromosomes was carried out, showing stability of the number and the positions of the nucleolus organizer regions. Ten enzyme systems and three non-enzyme proteins (controlled in total by 25 interpretable loci) were examined in the Far Eastern vole from the island and continental populations. All of the loci were shown to be monomorphic, except for one esterase locus, which exhibited polymorphism at the intrapopulation and interpopulation levels. The issue of distribution of the Far Eastern vole subspecies is discussed. It is suggested that M. fortis pelliceus occurs not only in the Russian Far East, but also in Northern Transbaikalia.

A complex B chromosome system in the Korean field mouse, Apodemus peninsulae.

Information on B chromosomes of six subspecies of A. peninsulae Thomas, 1906, from 79 local populations of Russia (Siberia, Altai, Buryatia and the Far East), Mongolia, China, Korea and Japan (Hokkaido) is reviewed. The frequency of animals with B chromosomes is higher in this taxon than in other mammals and ranges from 0.4 up to 1.0, excluding two insular populations (Sakhalin Island and Stenin Island, Primorye) where Bs were not found. The B chromosome polymorphism shows four levels of variation in number (intraindividual mosaicism, intrapopulational and interpopulational), as well as variability in size, morphology and differential staining. Geographic variation was found among populations for these cytogenetic characteristics and, in some cases, it coincided with subspecies distribution. Comparative chromosome banding of micro and macro Bs illuminates possible pathways for their origin.

Comparative analysis of micro and macro B chromosomes in the Korean field mouse Apodemus peninsulae (Rodentia, Murinae) performed by chromosome microdissection and FISH.

Comparative analysis of micro B and macro B chromosomes of the Korean field mouse Apodemus peninsulae, collected in populations from Siberia and the Russian Far East, was performed with Giemsa, DAPI, Ag-NOR staining and chromosome painting with whole and partial chromosome probes generated by microdissection and DOP-PCR. DNA composition of micro B chromosomes was different from that of macro B chromosomes. All analyzed micro B chromosomes contained clusters of DNA repeats associated with regions characterized by an uncondensed state in mitosis. Giemsa and DAPI staining did not reveal these regions. Their presence in micro B chromosomes led to their special morphology and underestimation in size. DNA repeat clusters homologous to DNA of micro B chromosome arms were also revealed in telomeric regions of some macro B chromosomes of specimens captured in Siberian regions. Neither active NORs nor clusters of ribosomal DNA were found in the uncondensed regions of micro B chromosomes. Possible evolutionary pathways for the origin of macro and micro B chromosomes are discussed.

[Genogeographic variability and genetic differentiation of the root vole (Microtus oeconomus Pallas, 1776, Cricetidae, Rodentia) from the Kuril Islands]. / Genogeograficheskaia izmenchivost' i geneticheskaia differentsiatsiia polevki-ékonomiki (Microtus oeconomus Pallus, 1776, Cricetidae, Rodentia) kuril'skikh ostrovov.

Electrophoretic analysis of 12 enzyme systems and 3 nonenzyme proteins (in all, 24 interpretable loci) was carried out for Microtus oeconomus from ten Kuril islands, Kamchatka Peninsula, and the vicinity of the city of Magadan. Gene geographic variation was examined and the coefficients of genetic variation and differentiation were estimated. The inter-population allozyme differentiation was low (DNEI, 1972 not higher than 0.053) and caused by variation in the allele frequencies of polymorphic loci. The greatest genetic distances were found between the populations belonging to different subspecies. Allozyme differentiation of Far Eastern M. oeconomus and M. fortis are discussed in relation to the data on the age of the island isolation and paleontological records. Karyological analysis (G-, C-, and NOR-banding) demonstrated the absence of differences between M. oeconomus from Kamchatka and the vicinity of Magadan.

[Gene-geographical variation and genetic differentiation in red-backed voles of the genus Clethrionomys (Rodentia, Cricetidae) in the Okhotskii region]. / Genogeograficheskaia izmenchivost' i geneticheskaia differentsiatsiia lesnykh polevok roda Clethrionomys (Rodentia, Cricetidae) Priokhot'ia.

Thirteen enzyme systems and three nonenzyme proteins were electrophoretically analyzed in red-backed voles of the genus Clethrionomys. In total, 25 loci were interpreted. Gene-geographic variation was studied and indices of genetic variability and differentiation were determined. By the distribution of electrophoretic variants of hemoglobin, C. rutilus was shown to be divided into two geographical groups (northern and southern). A low level of genetic differentiation was revealed in the island isolates of C. rutilus and C. rufocanus. Separation of C. rufocanus, C. rex, and C. sicotanensis into a superspecies complex was confirmed. A study of differential G- and C-banding on C. rutilus and C. rufocanus chromosomes did not reveal intraspecific variation of autosomes. In these species, karyotypes of voles from Kamchatka Peninsula were studied for the first time. They appeared to be morphologically similar to the karyotypes continental voles by both autosomes and sex chromosomes.

[Chromosomal variability of the field mouse Apodemus agarius (Rodentia, Muridae)]. / Khromosomnaia izmenchivost' polevoi myshi Apodemus agarius (Rodentia, Muridae).

Chromosome sets of 114 Apodemus agrarius mice from 29 localities in Moldova, Ukraine, Siberia, and Far East were studied by means of G-, C-, and NOR-banding. In all populations studied, the Y chromosome was shown to be a medium-size acrocentric chromosome consisting of heterochromatin. Chromosome polymorphism observed in populations from Primorskii krai concerned (1) the morphology of the first two autosome pairs (variants A/A, A/ST, and ST/ST), (2) the number of metacentric chromosomes (from 6 to 8), and (3) heterochromatin localization in the pericentromeric regions of two metacentric chromosome pairs. A karyotype with an additional heterochromatic microchromosome found in all the metaphases studied was described in one mouse from a locality of western Primorye that has not been studied previously. In the karyotype of 15 mice from four populations of Primorye, the pool of nucleolus organizer regions is distributed over three autosome pairs rather than over four, as is the case A. agrarius from Europe. Based on the analysis of literature sources and our own data, the problem of chromosome polymorphism in the field mouse is discussed.