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Triticummilitinae Zhuk. et Migusch., a tetraploid wheat with the GAA genome, is considered a natural naked mutant of Triticum timopheevii Zhuk. Previously, the karyotype and crossing characteristics of this wheat were examined. To clarify the origin and relationships of T. militinae with other representatives of the wheat family, analysis of its chloroplast genome, which remained unexplored, is of great interest. In the present study, for the first time, sequencing and annotation of the complete chloroplast genome of T. militinae, the size of which was found to be 135 898 bp, was conducted. The plastome of this wheat is composed of two inverted repeats, each of 21 552 bp in length, the small single-copy (SSC) region of 12 791 bp, and the large single-copy (LSC) region of 80 003 bp. The chloroplast genome of T. militinae contains 132 annotated structural genes, of which 85 genes are protein-coding, 31 are tRNA genes, and four genes code for rRNA. [ABSTRACT FROM AUTHOR]

The widespread Palearctic rodent species gray hamster Nothocricetulus migratorius has a karyotype with a stable number of chromosomes 2n = 22 throughout the entire range of its habitat. We found gray hamsters with diploid number of chromosomes 2n = 24 locally distributed in the Qurama Ridge of the Tian Shan. A new karyotype and analysis of G- and NORs-bands of differentially stained chromosome sets were described for the first time. The described karyotype differs from the 22-chromosomal karyotype of gray hamsters by the Y-chromosome morphology and the presence of an additional pair of heteromorphic small chromosomes. Molecular genetic analysis revealed genetic divergence of 24- and 22-chromosomal forms of N. migratorius, and the differences between them in mitochondrial markers are comparable and in terms of nuclear markers exceed the differences between C. barabensis (2n = 20) and C. psevdogriseus (2n = 24). The data obtained give grounds to discuss the taxonomic status of the 24-chromosomal form of gray hamsters from the Qurama Ridge and consider the differentiation of N. migratorius karyomorphs as a stage of chromosomal speciation. [ABSTRACT FROM AUTHOR]

Data on B chromosomes in populations of different systematic groups of plants and animals from extreme habitats, i.e., the range boundaries and its parts exposed to adverse environmental factors are reviewed. Analysis showed rather similar patterns of B chromosome distribution in the species extreme habitats. In particular, a tendency to the increased polymorphism and increase in B chromosome number and frequency, which was accompanied by changes in the karyotype, as well as genomic and chromosomal abnormalities in their carriers, was observed. B chromosomes are often found in species with wide ranges. The possible adaptive role of B chromosomes in the vital activity of organisms and the genome evolution is discussed. [ABSTRACT FROM AUTHOR]

Variability in the number and morphotypes of macro, mini, and micro B chromosomes of Apodemus peninsulae in the valley Zeya River from Amur oblast is described. Micro B chromosomes were found in the karyotypes of the Korean field mice from the Far East of Russia for the first time. Two opposite trends in the geographic variability of B chromosome morphotypes have been identified. The first one is caused by the presence/absence of mini and/or micro, in addition to macro B chromosomes, in animals from the right and left river banks in the northeastern part of the Upper Zeya Plain, as well as in the northern part of the Amur–Zeya Plain. The second trend is clinal variability characterized by a gradual increase in three combined geographic populations of A. peninsulae of numerical parameters of B chromosomes: index x̄В Max micro, x̄В Max macro, the number of morphotypes, the number of clones in mosaics, and the proportion of mosaics in the direction from north to south of the Zeya River Valley. The revealed diversity of A. peninsulae B chromosome morphotypes for 13 regions allows us to re-evaluate the geographical variability of additional chromosomes of this species in the Russian Far East. Adaptive value of B chromosome morphotypes for the species has been also assumed. [ABSTRACT FROM AUTHOR]

The karyotypes of 95 specimens (57 males and 38 females) of yellow-necked field mouse (Sylvaemus flavicollis Melchior, 1834) caught at seven points in Eastern Europe were studied. Only one specimen had an extra chromosome. It was shown that, in Sylvaemus flavicollis in the surveyed sites from the central part of the range (Eastern Europe), the frequency of occurrence of specimens with B chromosomes is very low and probably does not depend on the ecological conditions of habitats. [ABSTRACT FROM AUTHOR]

A molecular genetic and karyological study of the fourhorn sculpin Myoxocephalus quadricornis (Linnaeus, 1758) has been carried out. The karyotype was studied for the first time and the results of Ag-staining of the chromosomes of specimens of the species from the East Siberian Sea are presented. The karyotype of M. quadricornis is stable; it contains 32 (10 metacentric, 2 submetacentric, and 20 subtelocentric) chromosomes, while the number of chromosome arms is 44. Nucleolar organizers were found in the telomeric regions of the short arms of two homologous medium-sized subtelocentrics. Variability in the number of nucleolar-forming chromosomes and stained blocks of nucleolar organizers was found. Common features in the chromosome sets of M. quadricornis and Megalocottus platycephalus indicate their greater similarity compared to species of the genus Myoxocephalus. The results of the karyological analysis are consistent with the molecular genetic data about the sister relationships between M. quadricornis and Megalocottus platycephalus. A complex of karyological and molecular-genetic features has been identified that allow one to reliably distinguish M. quadricornis from species of the tribe Myoxocephalini and indicate the need for its removal from the genus Myoxocephalus. [ABSTRACT FROM AUTHOR]

As a result of analysis of the control region of mtDNA for the Evoron vole, a high haplotype (97%) and nucleotide (1.53%) diversity was found. The data obtained indicate a low level of genetic differentiation of populations. At the same time, populations geographically located closer are subdivided more strongly than remote ones. In general, there is agreement between the data on the variability of the mitochondrial DNA control region and chromosome races. However, if the data of chromosomal analysis indicate the preservation of the more ancient variants of the karyotype in the Evoron-Chukchagir Lowland ("evoron" chromosomal race), then the data of molecular genetic analysis testify in favor of the preservation of the most ancient mt haplotype (106-19) in the population of the Upper Bureya Depression (argi race). [ABSTRACT FROM AUTHOR]

The main goal of cytogenetic studies on a plant is to provide general information about the evolutionary history of the plant, determine its cytological characteristics, and find resemblances between the case study and other plants such as species affinities. Some of this information is necessary for achieving plant breeding goals and determining appropriate policies. So far there have been no cytogenetic and karyological studies in different populations of the medicinal plant of sour tea in Iran. Thus, in this study, three different populations of Roselle (Hibiscus sabdariffa L.), obtained from Isfahan, Shiraz, and Sistan and Baluchestan, were studied on the basis of seven chromosomal parameters. The chromosomal data were analyzed in a completely randomized design with 10 replications and 5 observations. The three different populations were compared in terms of cytogenetical charactristics. According to the results of the analysis of variance table, there is no significant or meaningful difference in terms of these seven parameters among the three different populations of roselle. However, karyotypic diversity can be the source of genetic variation. Thus, the selection of parental bases for intraspecific and interspecific crossings should be based on the greater similarity of karyotypes in terms of the mentioned parameters. In all three populations the longest chromosome is chromosome no. 1 and the shortest one is chromosome no. 18. In the Isfahan, Shiraz, and Sistan and Baluchestan populations, chromosome no. 1 has the average length of 4.75, 4.74, and 4.69 µm, respectively. Chromosome no. 18 has the average length of 1.64 in both the Isfahan and Shiraz populations, and the average length of 1.65 in the Sistan and Baluchestan population. Moreover, the average chromatin length in the Isfahan population is equal to 46.39 µm, in the Shiraz population equal to 46.41 µm, and in the Sistan and Baluchestan population equal to 46.27 µm. The general formula was the same among the different populations and they were placed in the same chromosomal class. All three populations have the karyotype formula 18m with no observed satellites. The results showed that all of the studied populations were tetraploid (2n = 4x = 72). According to Stebbins (1971) method of classification, all populations were classified as 3B symmetry. Also using flow cytometry method, the average amount of nuclear DNA content in Isfahan and Shiraz populations, 5.7 picograms were calculated. [ABSTRACT FROM AUTHOR]

New data on the karyological variability of Apodemus peninsulae mice (Thomas, 1906) in the Tyva Republic are presented. By the ratio of macro and micro B chromosomes in the mice we studied earlier in this region and in the present study, it became possible to isolate several geographical populations that combine a number of studied catch points of East Asian mice within the territory of the Yenisei River basin in the northern and southern directions from Kyzyl (Republic of Tyva). The frequency distribution of micro B chromosomes makes the most significant contribution to obtaining a differentiation pattern of populations of mice with B chromosomes by area. [ABSTRACT FROM AUTHOR]

On the basis of a study of our own and published data on voles from the shores of Lake Evoron (n = 8) and the Amgun River (n = 8) in the Evoron-Chukchagir lowland, as well as individuals from laboratory breeding, new data on karyotypic variation (2n = 38–41, NF = 54–59), chromosomal transformations, and their combinations in the karyotype are presented. The numbering of chromosomes in the Evoron vole karyotype using differential (GTG) staining methods made it possible to identify pairs of chromosomes involved in various chromosomal rearrangements and to number the original pairs for the pairs formed from them by chromosome fusion. The tandem telomere-telomere (TTel) fusions of biarmed chromosomes form a large submetacentric element Mev1/4M; telomere-centromere fusion (TCen) as a result of inactivation of the centromere in one of the acrocentric pairs forms either an acrocentric (Mev17/18A) or metacentric element (Mev17/18M), and the Robertsonian translocation of the same pairs forms a metacentric element (Mev17/18M). The variability of the centromere position in two pairs of autosomes (Mev8 and Mev14) is also shown. The revealed rearrangements made it possible to describe twelve variants of the karyotype: two with 2n = 41, six with 2n = 40, three with 2n = 39, and one with 2n = 38. It is proposed that the voles of the Evoron-Chukchagir lowland be assigned to the "еvoron" chromosome race, and the other voles be assigned to the "argi" race. Prolific offspring from the individuals with TTel fusion in the karyotype and a high percentage of this rearrangement in individuals from natural sample sets indicates the absence of a harmful effect on the viability of voles. [ABSTRACT FROM AUTHOR]

The species number has been strikingly increasing in recent current works on Ethiopian endemic rodents, which to a great extent is due to genomic studies including the karyotype discoveries. Here, the diploid number 2N = 52 is defined anew for the genus Stenocephalemys, endemic to the Ethiopian Highlands, where four karyotypes with 2N values of 54, 50 and 46 were so far described for four taxa. The new karyotype (S. "pseudogriseicauda") combines into a nearly full series with other 2Ns (except the not yet found 2N = 48) within the genus and shows one interspecific chromosome rearrangement associated with the tandem fusion, in the direction 2N = 54 to 2N = 52. Together with the earlier detection of tandem fusions between karyotypes with 2N = 46 (S. albipes) and 2N = 54 (S. albocaudatus, S. griseicauda), this rodent taxonomic group presents an interesting case for the phenomenon of karyotypic orthoselection in an intrageneric phyletic line via the reoccurence of such characteristic chromosomal rearrangements as tandem fusions. [ABSTRACT FROM AUTHOR]

Cytogenetic analysis revealed that naked mole-rat populations across whole species distribution range possess an identical chromosomal set (2N = 60; NF = 100) despite significant differences in mtDNA. Supposed chromosomal stability of this eusocial species is considered as a factor contributing to maintaining the genetic variability. [ABSTRACT FROM AUTHOR]

Detection of translocations in subtelomeric regions of chromosomes is a serious diagnostic problem, because they are difficult to determine by conventional cytogenetics with G banding. The aim of this work was the development of the technology of DNA probe synthesis for unique sequences of subtelomeric chromosome regions based on long-range PCR using the clinical case of determining the parental origin of unbalanced translocation between chromosomes 5 and 8. The unbalanced translocation der(5)t(5;8)(р15.33;q24.22) in a proband with physical, motor, intellectual, and speech development delay and in his sibling with speech and intellectual development delay as well, which was previously identified by array comparative genomic hybridization (aCGH), was confirmed by FISH. A balanced translocation 46,XX,t(5;8)(p15.33;q24.22) was detected in the mother's karyotype using the created locus-specific DNA probe. This chromosome aberration was not detected by G banding of metaphase chromosomes. The father's karyotype was normal according to FISH results. The method presented here makes it possible to create locus-specific DNA probes in a molecular cytogenetic laboratory using long-range PCR for the rapid diagnosis of cryptic chromosomal rearrangements. [ABSTRACT FROM AUTHOR]

The fluorescence in situ hybridization (FISH) technique allows for the estimation of the number of stable chromosomal aberrations (translocations) in human blood T-lymphocytes decades after radiation exposure. Therefore, it is used for retrospective assessment of irradiation doses received by red bone marrow (RBM). Cytogenetic analysis of individuals exposed on the Techa River in the 1950s to 89,90Sr, locally irradiating RBM, showed that dose assessment based on FISH data led to underestimation of the actual dose estimated from measurements of whole-body 90Sr content. The purpose of current study was to evaluate the dose–effect relationship and the frequency of translocations per 1 Gy of RBM irradiation dose and T-lymphocytes dose for donors living in Techa riverside villages (n = 178; translocation yield = 2389; number of genome equivalents GE = 96 446). Irradiation doses were estimated using the latest version of the Techa River dosimetry system and the T-cell irradiation model. Statistical analysis showed that the frequency of translocations per 1000 GE per 1 Gy of RBM dose was 8.0 ± 0.7; this value was statistically significantly lower than the value estimated for Sellafield radiation workers under external exposure (11.6 ± 1.6). At the same time, the use of T-cell and their progenitor doses led to re-evaluation (increase) in the slope of the dose–response curve to 11.8 ± 1.6 per 1 Gy per 1000 GE, which agreed well with the published data. The obtained estimates of the background frequencies of translocations also were close to the published values ​​for unexposed donors. These findings demonstrate the legitimacy of using a model approach for estimation of irradiation doses in T-lymphocytes and their progenitors and the need to take into account complex T-cell dynamics in interpretation of cytogenetic data for the purposes of biodosimetry. [ABSTRACT FROM AUTHOR]

Most common reasons for pregnancy loss are chromosomal anomalies of the fetus. They are found in as much as half of the miscarriages. The standard technique for assessment of chromosomal abnormalities in spontaneously aborted fetuses has been karyotyping, however, it needs cell culture which is the most vulnerable element of a diagnostic process. At present, there are a number of molecular methods, which skip the necessity of cell culture. In this study, we assess retrospectively the diagnostic yield of two commonly used molecular techniques (MLPA and QF-PCR) for aneuploidy detection in miscarriages. A total of 674 samples were analyzed. The QF-PCR assay for chromosomes 13, 15, 16, 18, 21, 22, X and Y was used. Two subtelomeric and subcentromeric probe kits covering all chromosomes were used in MLPA tests. In QF-PCR test, chromosomal abnormalities were found in 49.5% of cases. Trisomies constituted 25.7%, monosomies X— 12.9% and triploidies—10.9%. In the MLPA series, a total of 55.1% samples turned out to carry a chromosomal aberration. Trisomies were found in 43.2% of all good quality samples, chromosome X monosomies accounted for 13.4% of samples, and triploidies were detected in 11.3%. Both QF-PCR and MLPA methods may be successfully implemented as an alternative for standard karyotype in testing material from spontaneous abortion. QF-PCR has lower sensitivity comparing to MLPA in detecting aneuploidies, however, it is an effective tool for the detection of polyploidies. It should be noted, that using these techniques, the maternal cell contamination should be considered as an important issue. [ABSTRACT FROM AUTHOR]

Human induced pluripotent stem cells (iPSCs) are a promising source of cells for regenerative medicine, study of the pathogenesis of various diseases, screening of pharmacological drugs, and other clinical and basic research. However, the maintenance of the genetic stability of the cells during reprogramming, long-term culture, and directed differentiation is necessary for the use of iPSCs. Large chromosomal aberrations affect the quality of iPSCs most adversely, so the review focuses on the analysis of chromosomal abnormalities, including the recurrent aneuploidy; the sources of its origin, the effect of reprogramming, and long-term culture on the accumulation of chromosome aberrations are discussed. Cases of spontaneous correction of the iPSCs karyotype and the possibility of induced correction of the large chromosomal abnormalities by removing or silencing the extra homologue are considered. [ABSTRACT FROM AUTHOR]

Experimental embryology achievements in the century resulted in the birth of the first child conceived artificially. Besides its obvious social significance, the successful solution of the "test-tube babies" provided also the unique chance for direct inspection of human embryos growing in vitro at their earlier stages. New technologies applied for human gametes and earlier embryos studies, combined with high resolution capacities of modern cytogenetic and molecular methods, helped a lot in elaboration of efficient algorithms for assisted reproductive technologies (ART) and also provided a solid background for illumination of many genetic problems of human development before implantation. The later include input of chromosome aberrations and genome imprinting in pathology of early human development, cytogenetic and molecular mechanisms of the primary embryonic differentiation, genome epigenetic changes from fertilization through cleavage and blastulation, and identification of genes responsible for early development and differentiation. Conspicuous achievements in ART also include the creation of three parental embryos as a new step for the treatment of mitochondrial diseases, elaboration of karyomapping technique amenable for the diagnostics of both chromosomal and genetic pathology, and participation of paternal mitochondria delivered by the sperm in human development. A new era in human development genetics and ART was recently mitigated by the genome editing technique. The necessity of strict regulations for the safe implementation of genome editing in human embryonic development has been stressed. The areas of special attention include all studies of genome editing, production of artificial gametes, growing of chimera embryos for the purposes of organ and tissue transplantation, etc. Conspicuous delay of Russian science in the field of human developmental biology and experimental embryology and the necessity of its urgent support from both the fundamental sciences and clinical medicine have to be stressed. [ABSTRACT FROM AUTHOR]

The study is focused on the analysis of the mechanisms underlying the formation and distribution of repeat clusters in mammalian chromosomes, as exemplified by a group of closely related species of voles of the subgenus Microtus (Microtus, Arvicolini). The distribution of repetitive sequences that are the parts of de novo formed heterochromatic regions of Microtus arvalis in two chromosomal forms of this species and three closely related species, M. rossiaemeridionalis, M. kirgisorum, and M. transcaspicus, was analyzed in detail. Possible relationships between the introduction of repetitive sequences, their transpositions, amplification, and the formation of reproductive isolation, which can lead to speciation, are discussed. [ABSTRACT FROM AUTHOR]

In the present study, on the basis of cytogenetic and molecular genetic (mtDNA control region) analysis, genetic variability of the Muya valley vole, Alexandromys mujanensis, an endemic of Buryatia and the northwest of Zabaykalsky krai, was assessed. Three isolated valley vole populations from the Muisko-Kuandinskaya and Barguzinskaya depressions, as well as the Baunt Lake valley, were examined. Polymorphism in the number of autosomal arms (NFa = 46–49) with a stable number of chromosomes (2n = 38), determined by morphological variability of four pairs of autosomes (MMUJ2, MMUJ7, MMUJ8, and MMUJ14), rather than two, as previously thought, was revealed. To date, for the Muya valley vole, ten karyotype variants have been identified. It seems likely that chromosomal rearrangements (pericentric inversions, as well as two variants of fusion of acrocentric chromosome pairs, i.e., centromeric-centromeric and centromeric-telomeric), which led to variability in autosome morphology in the populations of the Muya valley vole, are not harmful. Analysis of the mtDNA control region revealed high haplotype and nucleotide diversity for the species as a whole, while in the valley vole samples from the Dzherginsky Nature Reserve (Barguzinskaya Depression) and the Baunt lake valley, nucleotide diversity was reduced compared to the sample from the Muisko-Kuandinskaya Depression. Despite the fact that each of the studied populations has a unique composition of chromosomal rearrangements and mtDNA haplotypes, higher similarity between the populations of the Muisko-Kuandinskaya Depression and the populations of the Baunt lake valley can still be suggested. [ABSTRACT FROM AUTHOR]

In the females of the viviparous lizard Zootoca vivipara (Lichtenstein, 1823) (family Lacertidae) from Northwest Russia (2n = 35: 32A (acrocentric autosomes) + Z1Z2W sex chromosomes), the ovarian lumen germinal vesicles (oocytes), as well as germinal lamina cells, were examined. Chromosome preparations were obtained using the direct method and the method of total oocyte nuclei spreading developed by Dresser and Moses. Chromosome preparations were stained with Giemsa; for visualization of synaptonemal complexes (SCs), total preparations of oocyte nuclei were stained with silver nitrate and DAPI. It was demonstrated that, during oogenesis in the female, primary follicles enter the early stages of the meiotic prophase I (stages from leptotene to diplotene, lampbrush chromosomes are formed). Here, for the first time, total oocyte spreads were obtained and studied. On the basis of light microscopic analysis of the oocyte SCs and taking into account their length in a female with 2n = 35, the SC karyotype is presented, consisting of 19 SC elements, among which 16 SC autosomal bivalents are distinguished. The remaining three SC elements, according to the authors, can be univalents of Z1Z2W sex chromosomes or one WZ1 bivalent and Z2 and B chromosome univalents. As in the SC karyotype of Z. vivipara males, in a female, specific features in the morphology of SC elements of chromosomes 5 and 6 were observed. [ABSTRACT FROM AUTHOR]

In interspecific hybrids a decrease in genetic exchanges between chromosomes from different species and negative interactions between functionally incompatible loci limit genetic variation among the progeny. Earlier the fraction of crossover genotypes was increased in intraspecific hybrids of the cultivated tomato Solanum lycopersicum with the expression of the recA Escherichia coli gene. In this research transgenic hybrids between S. lycopersicum and some wild tomato species were obtained in order to study the effect of recA gene expression on the frequency of crossovers in the progeny of interspecific hybrids. Interspecific hybrids showed negative interactions between the loci of the cultivated tomato and the S. cheesmaniae, S. pimpinellifolium, and S. habrochaites species. In the latter case it resulted in semilethal necrosis. The recA gene expression in interspecific hybrids with S. cheesmaniae partially compensates among the F2 progeny the deficiency of recessive genotypes at the Wv:wv locus of chromosome 2. In general, the fractions of crossover genotypes in the F2 progeny were higher in transgenic interspecific hybrids than in control non-transgenic hybrids of the same combination of crossing, but lower than in intraspecific S. lycopersicum hybrids. [ABSTRACT FROM AUTHOR]

Robertsonian translocations/isochromosomes formed by homologous acrocentric chromosomes are rare, and consequently their epidemiology has not been well investigated. This study, based on the analysis of published data including systematic studies of patients with reproductive disorders and individual reports on carriers of homologous translocation (HT), was conducted to determine the major epidemiological characteristics of HT. 10-fold differences were found between couples with infertility and couples with miscarriages, both in the frequency of HT carriers (0.03 and 0.45‰, correspondingly) and in their proportion of the total number of robertsonian translocation carriers (0.9 and 9%, correspondingly), p < 0.005. In patients with an apparent male infertility factor, these rates are 0.21‰ and 3%. In the group of males from couples with miscarriages (although about half of them are partners of women with female factor of reproductive disorder), rates of 0.36‰ and 10.5% were observed, p < 0.05. Among all HT carriers, those with HT of chromosomes 13 and 22 are found more frequently. For carriers of HT of chromosomes 13, 14, 15 and 21, female predominance was typical with the average sex ratio (SR) of 0.36 (22♂/61♀). Among the carriers of chromosome 22 HT, there was no female predominance, SR = 1.18 (13♂/11♀) the difference with other acrocentrics is statistically significant, p < 0.05. Analysis of reports on individual cases showed that only two out of 22 male HT carriers, were tested for infertility. One of them had a cell line with unbalanced HT, and for the other patient, the researchers found no reason to link the impairment of spermatogenesis with the presence of HT. Thus, in the majority of male HT carriers, spermatogenesis was not impaired. It is suggested that the disturbance of spermatogenesis in some cases is due to gonadal mosaicism for translocation trisomy resulting from incomplete correction of the original translocation trisomy. There are some published reports on healthy offspring with an inherited a parental balanced HT and on offspring with normal karyotypes born to apparently non mosaic HT carriers. Hence, it is possible to consider the probability of having healthy offspring for HT carriers as not zero, therefore references to the algorithms for the patients' comprehensive examination and appropriate counseling are given. [ABSTRACT FROM AUTHOR]

Abstract: The nature of the formation of fertile progenies of F2 and F3 generations of wheat-rye hybrids obtained as a result of meiotic restitution using the Saratovskaya 29 variety (C29 x R) and the wheat-rye substituted line 1Rv(1A) (1Rv (1A) × R) was studied. The karyotype analysis of the F2Triticum aestivum L. cv. Saratovskaya 29 × Secale cereale L. var. Onochoyskaya (S29 × R) hybrid using C-banding revealed 56 chromosomes; among them were 42 wheat chromosomes and 14 rye chromosomes. The karyotype of the F2 1Rv(1A) × R hybrid contained 46 chromosomes, of which three pairs of rye chromosomes 1R1R4R4R2RL2RL, 1R1R replaced the chromosomes 1A1A, and 2RL2RL and 4R4R were additional to the wheat chromosomes. In the F3 generation of S29 × R hybrids, the octoploid number of chromosomes with aneuploidy of single rye and wheat chromosomes was preserved, while in the 1Rv(1A) × R hybrids the number of chromosomes varied from 42 to 49, but in most plants 2n = 46 was retained. Meiosis of the F3 1Rv(1A) × R hybrids was more stable than that of the S29 × R hybrids. The average number of univalents in 1Rv(1A) × R hybrids was 1.54 ± 0.17, which was significantly lower than in S29 × R hybrid progenies (2.56 ± 0.23 and 2.07 ± 0.27). The F3 С29 × R and 1Rv(1A) × R hybrids were characterized by the variability in the seed set and 1000-grain weight. On average, С29 × R plants produced a smaller number of grains with but larger size than 1Rv(1A) × R plants, forming more grains with lower 1000-grain weight. The obtained results indicate the influence of the substitution 1Rv(1A) on the reorganization of hybrid genomes. [ABSTRACT FROM AUTHOR]

Karyotyping of the common shrews Sorex araneus from the poorly studied region of the Northwest of Russia revealed the belonging of individuals to two chromosomal races, Lemi and St. Petersburg. The Lemi race, previously known only from Finland, was discovered for the first time on the territory of Russia and thus replenished the list of S. araneus chromosomal races that are distributed within the Russian part of the species range (27 races out of 74 known in the whole species range at the moment). The studied individuals showed a high level of chromosomal polymorphism, caused by Rb translocations. [ABSTRACT FROM AUTHOR]

We studied the species composition and chromosomal variability of malaria mosquitoes in the Volga Basin (Upper, Middle, and Lower Volga regions). We investigated larvae karyotypes of sibling species of the Anopheles maculipennis group. We calculated the frequencies of chromosomal inversions in the local populations of the dominant species An. messeae. We discovered that karyotypic structure of An. messeae populations depends on landscape-climatic zones. Populations of the Upper, Middle and Lower Volga differ in frequency of chromosome inversions XL, 2R, 3R, and 3L. [ABSTRACT FROM AUTHOR]

The discovery of cell-free DNA in the blastocoele fluid is promising for the development of new noninvasive methods for the preimplantation genetic diagnosis of chromosomal diseases. However, there are no data confirming the concordance between the molecular karyotype of cell-free DNA from blastocoele fluid and the blastocyst cells per se. This paper reports on such concordance according to the results of molecular cytogenetic analysis by comparative genomic hybridization. [ABSTRACT FROM AUTHOR]

The karyotype of males of two species of the genus Nothobranchius with the lowest diploid numbers was investigated: Nothobranchius rachovi (2 N = 16) and Nothobranchius krysanovi (2 N = 18). For the first time, whole mounts of spread syneptonemal complexes (SC) of these species were obtained and investigated. When the SC was painted with silver nitrate and immunostained with rabbit antibodies against the SCP3 protein, eight and nine homomorphic SCs were detected in the nuclei of class I spermatocytes of N. krysanovi and N. rachovi, respectively. The sex chromosomes were not identified. [ABSTRACT FROM AUTHOR]

The karyotype of Camptochironomus tentans (Fabricius), 1805 (Diptera, Chironomidae) from the populations of the Lower Volga region and Central Caucasus (the northern macroslope) has been studied. In the karyotype of C. tentans from Saratov oblast, 14 banding sequences (BS), 13 genotypic combinations, and 14 zygotic combinations were identified. Four new BSs were described: ten B12, ten F4, ten F5, and ten G4, which are distinguished by simple paracentric inversions from those already known for the species. The chromosomal polymorphism belongs to the inversion type; its level in the Saratov population is generally the same as in populations of other parts of the area. The number of heterozygous inversions per specimen was 1.3; the number of heterozygous inversions per arm was 0.86; the percentage of heterozygous larvae was 84.5. The polymorphic arms in C. tentans were A, B, C, and F. Nine previously known BSs were revealed in the karyotype of C. tentans from Central Caucasus, and no new sequences were found. Arm B in C. tentans was polymorphic. The zygotic combinations in all the studied populations were distinct. [ABSTRACT FROM AUTHOR]

The karyotype of Camptochironomus pallidivittatus Edwards, 1929 (Diptera, Chironomidae) from six populations of the Lower Volga region and Central Caucasus (the northern macroslope) has been studied. In populations of C. pallidivittatus from the Central Caucasus, 11 banding sequences (BS) were found; one sequence, pal B10, was new for the species. In the Saratov population, 11 BS were also found, three of which were new for the species-pal A3, pal B11, and pal B12. The banding sequences detected for the first time have not yet been found in other parts of the area of this species and may be endemic to these regions. In the studied populations of C. pallidivittatus, banding sequences were found that were non standard, but fixed in the karyotype. This is indicative of some degree of chromosomal divergence. These banding sequences include pal A2.2 in arm A and pal B10.10 in arm B in the Central Caucasus region, as well as pal B2.2 and pal G2.2 in the Lower Volga region. Arms A, B, D, and G in the Central Caucasian populations and A, B, and D in the Saratov oblast were polymorphic. The composition of heterozygous sequences between populations from different regions coincided only in arm D (pal D1.2). In arms A and B, the set of heterozygous BS was different: pal A1.2 and pal B1.10 sequences were found in the Central Caucasian populations, and pal A1.3 and B11.12 were found in Saratov oblast. The number of genotypic combinations of C. pallidivittatus was higher in the Central Caucasus region, whereas the number of zygotic combinations was higher in the Saratov population. The percentage of heterozygous larvae in the Central Caucasian populations varied from 20 to 80, whereas all individuals in the Saratov population had heterozygous inversions. Zygotic combinations of larvae in all the studied populations were different. [ABSTRACT FROM AUTHOR]

To study whether inversions (or arrangements) by themselves or karyotypes are the main global warming adaptive target of natural selection, two Drosophila subobscura Serbian populations (Apatin and Petnica) were re-analyzed using different statistical approaches. Both populations were sampled in an approximately 15 years period: Apatin in 1994 and 2008 + 2009 and Petnica in 1995 and 2010. For all chromosomes, the four colleptions studied were in Hardy-Weinberg equilibrium. Thus, it seems that inversions (or arrangements) combined at random to constitute populations' karyotypes. However, there were differences in karyotypic frequencies along the years, although they were significant only for Apatin population. It is possible to conclude that inversions (or arrangements) are likely the target of natural selection, because they presented long-term changes, but combine at random to generate the corresponding karyotypic combinations. As a consequence, the frequencies of karyotypes also change along time. [ABSTRACT FROM AUTHOR]

The contact points of four karyotypic races (St. Petersburg, Moscow, Seliger and West Dvina) of the common shrew Sorex araneus L. were studied at the Valdai Hills (European Russia) in an area unimpeded by geographic barriers. The populations of the races are separated by narrow hybrid zones that represent the most complex heterozygous hybrid karyotypes. At these points of contact, the morphometric differentiation of karyotype races was examined in 12 cranial measurements in 190 shrews of a known karyotype. A comparison of the mean values in studied samples of immature shrews revealed statistically significant differences and the correlation of some measurements which describe the level of musculus temporalis. It has been proposed that morphometric differences in the karyotypic races were preserved and accumulated because of a 50% reduction of the frequencies of hybrids. The deviation from the Hardy-Weinberg ration in the frequencies of the genotype and haploid sets of chromosomes in the hybrid zones can be attributed to a number of fatalities of hybrid embryos or the nonrandom mating of karyotypic races. The ethological isolation might arise in the evolution of some karyotypic races from the reduced fitness of the hybrids. [ABSTRACT FROM AUTHOR]

Using pulse electrophoresis in controlled homogenous electric field we performed molecular karyotyping of cephalosporin C-producing industrial and laboratory strains of Acremonium chrysogenum. Differences in size of several chromosomes of high-producing strain CB26/8 compared to the wild-type strain ATCC 11550 were revealed. It was shown that chromosomal polymorphism in the high-producing strain was not associated with alteration of localization and copy number of cephalosporin C (CPC) biosynthesis and transport genes. A cluster of 'early' CPC biosynthesis genes is located on chromosome VI (4.4 Mb); a cluster of the 'late genes', on chromosome II (2.3 Mb). Both clusters are presented as a single copy per A. chrysogenum genome in the wild-type and in CB26/8 high-producing strains. Based on comparative analysis of laboratory and industrial CPC producers, a karyotype scheme for A. chrysogenum strains of various origins was designed. [ABSTRACT FROM AUTHOR]

Acoustic characteristics were studied in two species of the Anopheles maculipennis species complex, A. messeae and A. atroparvus. The species were found to clearly differ in sound frequencies, which was assumed to play a key role in species identification during mating in regions of their sympatric distribution. The sound spectrum in A. messeae was far more diverse than in A. atroparvus, which was associated with intraspecific inversion polymorphism of the former. Mosquitoes with the inversion combinations that were most common in populations of the central region of the A. messeae species area specifically differed in acoustic signal spectrum from each other. Hence, sound communication within the species was considered to be the main mechanism that is responsible for sexual partner selection and determines the chromosome associations observed earlier in individual karyotypes. Since males carrying different inversion combinations significantly differed in acoustic characteristics, females were assumed to play a main role in selecting the sexual partner. [ABSTRACT FROM AUTHOR]

Considerable differences in karyotypes of Tribolodon hakonensis from Primorye and the rivers of the Sea of Okhotsk drainage were demonstrated. These differences raise doubts that these fishes belong to one species and point to the necessity of more precise definition of the species status of the southern form of T. hakonensis. The karyological evidence is consistent with the data of mtDNA PCR-RFLP analysis on genetic independence of the southern and the northern forms of T. hakonensis. In the northern form of T. hakonensis, variation of the chromosomal arm number was revealed. Specifically, the number of chromosomes was constant (2 n = 50), whereas the number of chromosomal arms (NF) constituted 88, 92, and 94, which suggests genetic heterogeneity of the northern form. PCR-RFLP analysis of mtDNA showed that haplotypes of northern T. hakonensis split into two groups with 100% support. Based on comparative phylogenetic and karyological analyses of the Tribolodon species, independent divergence of the southern and the northern forms of T. hakonensis was suggested. [ABSTRACT FROM AUTHOR]

The results of light and electron microscopic (EM) studies of meiosis in Microtus arvalis males of the karyoform 'arvalis' (2 n = 46, NFa = 80), in hybrids between the chromosomal forms arvalis and obscurus (2 n = 46, NFa = 68), in M. rossiaemeridionalis voles (2 n = 54, NFa = 54), and in a hybrid between the species M. rossiaemeridionalis and kermanensis (2 n = 54, NFa = 54) are presented. SC (synaptonemal complex) karyotypes of the parental forms and the hybrids were constructed on the basis of measurements of the length of autosomal SCs revealed by the EM analysis in spermatocytes at the stage of middle pachytene. The SC karyotypes of M. arvalis and the hybrids ♀ obscurus × ♂ arvalis consist of 22 synaptonemal complexes of autosomal bivalents and the axial elements of the synaptonemal complexes of the sex chromosomes X and Y. The SC karyotypes of M. rossiaemeridionalis and the hybrid M. rossiaemeridionalis × M. kermanensis consist of 26 synaptonemal complexes of autosomal bivalents and a sex bivalent; they differ only in the length of the Y chromosome axis (Y chromosome in the hybrid was inherited from M. kermanensis). Asynaptic configurations of the autosomal SCs were not observed in the hybrids. The SC axial elements of the X and Y chromosomes in the parental forms and in the hybrids were located close to each other throughout pachytene, but they did not form a synaptic region. The normal synapsis in sterile hybrids ( M. rossiaemeridionalis × M. kermanensis) and the behavior of the sex chromosomes in meiosis in fertile and sterile hybrids are discussed in the context of specific features of meiosis and reproductive isolation. [ABSTRACT FROM AUTHOR]

nalysis of sperm aneuploidy in 11 healthy men using two-or three-color FISH permitted to determine the average frequency of disomy for chromosomes 13 and 21 (0.11% and 0.2%, respectively), disomy for chromosome 18 (0.05%) and to reveal gonosomal aneuploidy variants and their frequency. The frequency of XX disomy was 0.04%; XY, 0.17%; YY, 0.06%; and gonosomal nullisomy, 0.29%. We assessed the frequency of meiotic nondisjunction of 13, 21, 18, X, and Y chromosomes and the frequency of XX, XY, and YY diploid spermatozoa. The XY variant prevailed in gonosomal aneuploidy and diploidy and was associated with abnormal chromosomal segregation in meiotic anaphase I. The contribution of human sperm chromosomal imbalance to early embryonic lethality and to some forms of chromosomal abnormalities in the off-spring is discussed. [ABSTRACT FROM AUTHOR]

Using C-banding method and in situ hybridizatiion with the 45S and 5S rRNA gene probes, six hexaploid species of the genus Avena L. with the ACD genome constitution were studied to reveal evolutionary karyotypic changes. Similarity in the C-banding patterns of chromosomal patterns and in the patterns of distribution of the rRNA gene families suggests a common origin of all hexaploid species. Avena fatua is characterized by the broadest intraspecific variation of the karyotype; this species displays chromosomal variants typical of other hexaploid species of Avena. For instance, a translocation with the involvement of chromosome 5C marking A. occidentalis was discovered in many A. fatua accessions, whereas in other representatives of this species this chromosome is highly similar to the chromosome of A. sterilis. Only A. fatua and A. sativa show slight changes in the morphology and in the C-banding pattern of patterns of chromosome 2C. These results can be explained either by a hybrid origin of A. fatua or by the fact that this species is an intermediate evolutionary form of hexaploid oats. The 7C-17 translocation was identified in all studied accessions of wild and weedy species ( A. sterilis, A. fatua, A. ludoviciana, and A. occidentalis) and in most A. sativa cultivars, but it was absent in A. byzantina and in two accessions of A. sativa. The origin and evolution of the Avena hexaploid species are discussed in context of the results. [ABSTRACT FROM AUTHOR]

Using karyological, allozyme, and molecular genetic analysis, habitation of the four Sylvaemus wood mice species, pygmy wood mouse ( S. uralensis), wood mouse ( S. sylvaticus), yellow-necked mouse ( S. flavicollis), and yellow-bellied mouse ( S. fulvipectus) in Rostov oblast was demonstrated. Sylvaemus uralensis was distributed nearly over the whole territory of the oblast; S. sylvaticus was found in the central and western parts of the oblast on the right bank area of Don River; S. flavicollis inhabited northern and central parts of Rostov oblast on the right bank area of Don River; S. fulvipectus was found in the southern parts of the oblast, in the left bank area of Don River. Using the chromosome C-banding technique, it was demonstrated that the pygmy wood mice living in Rostov oblast in the right bank areas of Manych River and Don River in its low course, belonged to the eastern European chromosomal form of S. uralensis. The pygmy wood mice from the outskirts of the town of Salsk, the left bank area of Manych River, were probably hybrids between eastern European and southern European chromosomal forms. Based on the mitochondrial DNA cytochrome b gene fragment sequencing and chromosome C-banding, it was suggested that the wood mice inhabiting Rostov oblast belonged to the southern lineage of S. sylvaticus, living on Apennine Peninsula, Balkan Peninsula, and nearly throughout Ukraine. [ABSTRACT FROM AUTHOR]

Using a set of approaches based on the use of molecular cytogenetic markers (DAPI/C-banding, estimation of the total area of DAPI-positive regions in prophase nuclei, FISH with 26S and 5S rDNA probes) and the microsatellite (SSR-PCR) assay, we studied genomic polymorphism in 15 flax ( Linum usitatissimum L.) varieties from different geographic regions belonging to three directions of selection (oil, fiber, and intermediate flax) and in the k-37 × Viking hybrid. All individual chromosomes have been identified in the karyotypes of these varieties on the basis of the patterns of differential DAPI/C-banding and the distribution of 26S and 5S rDNA, and idiograms of the chromosomes have been generated. Unlike the oil flax varieties, the chromosomes in the karyotypes of the fiber flax varieties have, as a rule, pericentromeric and telomeric DAPI-positive bands of smaller size, but contain larger intercalary regions. Two chromosome rearrangements (chromosome 3 inversions) were detected in the variety Luna and in the k-37 × Viking hybrid. In both these forms, no colocalization of 26S rDNA and 5S rDNA on the satellite chromosome was detected. The SSR assay with the use of 20 polymorphic pairs of primers revealed 22 polymorphic loci. Based on the SSR data, we analyzed genetic similarity of the flax forms studied and constructed a genetic similarity dendrogram. The genotypes studied here form three clusters. The oil varieties comprise an independent cluster. The genetically related fiber flax varieties Vita and Luna, as well as the landrace Lipinska XIII belonging to the intermediate type, proved to be closer to the oil varieties than the remaining fiber flax varieties. The results of the molecular chromosome analysis in the fiber and oil flax confirm their very close genetic similarity. In spite of this, the combined use of the chromosome and molecular markers has opened up unique possibilities for describing the genotypes of flax varieties and creating their genetic passports. [ABSTRACT FROM AUTHOR]

Variability of the cranial properties of chromosomal races Serov, Manturovo and Petchora of the common shrew were studied. A consistent increase of scull size in the Serov race with moving from the plain to highlands and a skull size decrease from low to high latitudes was detected. Interpopulation variability among different races was shown to be comparable with interracial variability or to exceed it. This suggests microevolution at the level of local populations. [ABSTRACT FROM AUTHOR]

Using the molecular cytogenetic and RAPD methods of analysis, we studied genomes of 22 cultivated flax varieties and 24 wild species from six sections of the genus Linum L. The chromosome numbers were exactly determined in the karyotypes of all studied species, and all individual chromosomes were identified by the C/DAPI-banding pattern and localization of 26S rDNA and 5S rDNA. B chromosomes were discovered and studied for the first time in species of the section Syllinum Griseb. According to the data obtained, the species studied were divided into eight groups on the basis of similarity of their karyotypes, which corresponded in general to their clustering based on the RAPD results. The systematic positions and phylogenetic relationships of the flax species were verified. [ABSTRACT FROM AUTHOR]

This short communication is a review of key trends in the karyotypic evolution of mammalian taxa Laurasiatheria, inferred from comparative chromosome painting. [ABSTRACT FROM AUTHOR]

The karyotypes of larvae Glyptotendipes glaucus Mg. 1804 from three reservoirs of Kaliningrad city (Pen’kovoe and Karasevka lakes and Chistyi pond) were studied. The levels of the natural inversion polymorphism for the three populations were determined. Ten new inversion sequences (gla B4, gla B5, gla B6, gla D5, gla E4, gla E5, gla E6, gla E7, gla F6, and gla F7) were detected in the species studied. Inversion including the centromeric region in IIIEF (gla E6 + gla F7) was pericentric. Several cases of gla B5 and gla B6 combination with gla B2 resulting in genotypic combination gla B2.5 and gla B2.6 were found. The dependence of the number of inversion sequences and genotype combinations from the content of heavy metal ions in sediments of the reservoirs was revealed. All populations were characterized by the prevalence of inversion sequence gla B2 in chromosome I. [ABSTRACT FROM AUTHOR]

The banding structures of chromosomes of three Palearctic species of chironomids of the genus Sergentia Kieffer, 1922 from the Irkutsk reservoir were comparatively analyzed: S. baueri Wülker et al., 1999 (2 n = 8), S. prima Proviz et al., 1997 (2 n = 8), and S. electa Proviz et al., 1999 (2 n = 6). The S. baueri karyotype was taken as a standard in chromosome mapping. It was established that in contrast to S. baueri and S. prima the S. electa karyotype was formed due to a complex translocation: transfer of chromosome IV in the median part of chromosome III. The sequences of chromosome I bands were found to be completely homologous in all Palearctic species and in S. rara Proviz et al., 1999 (2 n = 8) taken as the original species in the group of Baikalian endemics. In both groups, seven homozygous inversions were detected, of which the common one is the inversion in chromosome III. It was assumed on the basis of the results of the karyological analysis that among the Palearctic species S. baueri is most similar to the Baikalian endemics and S. electa is phylogenetically closer to S. prima. Specific features of the chromosome and morphological evolutions of the Sergentia genus species are considered. [ABSTRACT FROM AUTHOR]

The present study aimed to reveal differences in the activity of a mitochondrial enzyme, succinate dehydrogenase (SDG), in larvae of mosquito Anopheles messeae with various karyotypes. Four-instar larvae of malaria mosquito previously obtained in laboratory conditions from imagoes collected in a taiga population of Tomsk region served as material for the study. Assessment of SDG activity indices demonstrated its regular variation in mosquito larvae with different karyotypes. Maximum succinate dehydrogenase activity was detected in tissues of larvae carrying combinations of XL1, XL2, 2R1, 3R1, 3L1 inversions, in which mostly inhabit the northeastern part of the species range. The lowest enzyme activity was observed in larvae with alternative chromosomal variants (XL0, 2R0, 3R0, 3L0), predominantly inhabiting the southwestern part of the range. Moreover, the studied physiologic-biochemical features of the mosquitoes were shown to depend on the set of inversions in the karyotypes: in the higher the number of variants of chromosomal aberrations in the karyotype characteristic of the northern latitudes, of the higher the activity index, and vice versa. The significance of the relationships between the nuclear and the mitochondrial genome functioning in adaptive regulation of the cell energy metabolism in A. messeae larvae is discussed. [ABSTRACT FROM AUTHOR]

The karyotype formation was studied in the F1BC1 and F1BC2 hybrids of Secale cereale L. ssp. tetraplodium Kobyl. (RRRR, 4 x = 28) and Triticale (AABBRR, 6 x = 42). The hybrid karyotypes were heterogenomic for homeologous chromosome groups of the wheat and rye genomes. The hybrids differed in cytological stability, the balance of chromosomes of the original species, and the fertility of spikes. The majority of F1BC1 and F1BC2 plants were cytologically unstable and unbalanced in chromosome composition and displayed a low spike fertility. Cytologically stable hexaploids occurred in F1BC1 and F1BC2 at a frequency of 1.0 and 9.5%, respectively. The resulting hexaploid secalotriticum lines (RRAABB, 6 x = 42) were genotypically diverse and morphogenetically various. The genetic factors responsible for the diversity of the F1BC1 and F1BC2 rye-triticale amphiploids and early secalotriticum generations are discussed. [ABSTRACT FROM AUTHOR]

It is rather difficult to construct a system of gray voles of the tribe Microtini by a set of morphological and karyological characters because form generation is mosaic at these organization levels. The sequence of the mitochondrial cytochrome b gene was used to study the phylogenetic relationships and taxonomic position of the Central Asian subgenus Blanfordimys. Afghan vole Microtus ( Blanfordimys) afghanus and Bucharian vole M. ( Blanfordimys) bucharensis clustered with Pamir vole M. ( Neodon) juldaschi, which is conventionally assigned to another subgenus. The last two species proved to be significantly closer to each other than either of them was to M. ( Blanfordimys) afghanus, which disagrees with the monophyletic origin accepted for Blanfordimys. The genetic distances between the species of the subgenus Blanfordmys and M. juldaschi were comparable with the distances between the sister subgenera Microtus s. str. and Sumeriomys or Pallasiinus and Alexandromys and with the basal divergence of supraspecific clades in the subgenus Terricola. It was assumed that a special Central Asian group of species exists within the tribe Microtini and includes species of the subgenus Blanfordimys and M. juldaschi and that the subgenera Neodon and Blanfordimys should be revised. [ABSTRACT FROM AUTHOR]

Specific karyotype structure and chromosomal polymorphism was investigated in the populations of Sergentia nebulosa Linevitsh et al., 1984 and Sergentia assimilis Proviz V. et Proviz L., 1999, the deep-water endemic chironomid species (Diptera, Chironomidae) from the Baikal Lake. The distinguishing feature of the karyotypes of these species, compared to the other Baikalian Sergentia, is well-developed nucleolus in region 6 of arm C. Both species display the presence of interspecific population polymorphism, determined by the structure of this arm. In some populations, chromosome regions from 4 to 6 contain a homozygous inversion, which is absent in the other populations. The distinguishing karyotype feature of S. assimilis, which shares fluctuating homozygous inversions with the other species, is the presence of two species-specific homozygous inversions. These are the secondary overlapping inversion in arm A, regions 2 to 7, and the inversion in regions 4 to 10 of arm G. Both species of interest contain nucleolus organizer in region 10 of arm G. In populations of S. nebulosa, six heterozygous inversions localized in arms A, B, C, F, and G were discovered. The highest number of heterozygotes for inversions (71%) was observed in the population from Southern Baikal. In arm B of S. assimilis, one heterozygous inversion and heterozygosity for nucleolus organizer in the chromosome region 16 was detected. Chromosomal evolution of Baikalian Sergentia, and the role of inversion polymorphism in the population adaptation is discussed. [ABSTRACT FROM AUTHOR]

A complicated population system of B chromosomes has been revealed in the karyotypes of the East-Asian mouse Apodemus peninsulae over the whole range. Based on our previous data for mice from Altai, Siberia, Pribaikal’e, and Mongolia and on the results of the present work, we infer that most of animals studied (196 out of 312, or 63%) have an individual variant of the B chromosome system. Only three mice lacked B chromosomes. New data for 44 A. peninsulae mice caught in 2000–2005 in 16 localities of seven regions of Altai, Siberia, and Pribaikal’e showed that all of them had individual variants of the system of B chromosomes due to different combinations (from 2 to 18 B chromosomes) of five classes of B macro- and microchromosomes. [ABSTRACT FROM AUTHOR]

The methylation status of the cell cycle control gene RB1 has been studied in placental tissues of spontaneous abortions of the first trimester of pregnancy with mosaic variants of numerical chromosomal abnormalities verified by a molecular cytogenetic examination. Aberrant methylation of the gene promoter region has been revealed for the first time in 20% of embryos with chromosomal mosaicism that died in utero. A maximum frequency of epimutations was recorded in a group of embryos with a low level of abnormal cells for which mitotic errors are most likely to determine the formation of mosaic aneuploidy in primary euploid zygotes. It has been suggested that aberrant epigenetic genomic modifications at early stages of human embryonic development can be one of the mechanisms promoting genomic instability realized in the form of mosaic abnormalities of the karyotype that are incompatible with the normal course of embryogenesis. [ABSTRACT FROM AUTHOR]