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The level of chromosomal abnormalities in the somatic cells of adult individuals is characterized by significant interindividual variability, which may be partly affected by the genetic and epigenetic background. The epigenetic landscape in cells is largely determined by genome methylation. This study aimed to analyze the relationships between global genome methylation and the frequencies of chromosome abnormalities in lymphocytes of plutonium workers. The frequencies of chromosome aberrations, micronuclei, aneuploidy of chromosomes 2, 7, 8, 12, X, and Y and sister chromatid exchanges were analyzed in the lymphocytes of 40 male workers from a nuclear chemical facility (Seversk, Russia) with incorporated plutonium-239 and 49 healthy male volunteers who had no occupational exposure to ionizing radiation. The long interspersed nuclear elements-1 (LINE-1) methylation index was assessed as a well-known marker of global genome methylation. The frequencies of centromere-negative micronuclei (4.74 ± 2.26 vs. 3.02 ± 1.69‰), chromosome-type aberrations (0.81 ± 0.79 vs. 0.44 ± 0.69%), and total chromosome non-disjunction (0.93 ± 0.43 vs. 0.50 ± 0.25%) were significantly higher in the group of workers than in controls (p < 0.05). The LINE-1 methylation index did not differ significantly between the worker and control groups (74.93 ± 3.63 vs. 73.92 ± 4.62%). Correlations between LINE-1 methylation and the frequency of micronuclei (R = –0.35, p = 0.031) were observed in the control group, whereas correlations of LINE-1 methylation with chromatid-type aberrations (R = –0.42, p = 0.012) (but not chromosome-type aberrations) and with sister chromatid exchanges (R = –0.53, p = 0.004) were observed only in the group of plutonium workers. Thus, LINE-1 hypomethylation after plutonium exposure is associated mainly with chromatid breaks, either repaired or misrepaired. [ABSTRACT FROM AUTHOR]

The review considers monogenic and chromosomal mutations associated with X-linked intellectual disability. Peculiarities of the development of the clinical phenotype in cases of different mutations were described. Special attention is paid to X-linked CNVs (microdeletions and microduplications). Chromosomal microaberrations most frequently found in patients with intellectual disability are presented. A modifying effect of X chromosome inactivation on the phenotype of carriers of X-linked mutations is discussed. The problems of interpretation of the clinical significance of X-linked CNVs are considered. [ABSTRACT FROM AUTHOR]

The results of U–Pb geochronological (SIMS) study of zircons from granitoids of the Konstantinovskii Stock located 6 km from the Sukhoi Log gold deposit are reported. The 206Pb/238U weighted average age for long-prismatic crystals, rims, and cores of the early stage of crystallization of zoned zircons is 303 ± 3 Ma (MSWD = 0.87). The data obtained on the age of xenogenic cores of zoned zircons of the Konstantinovskii Stock granitoids indicate consolidated basement of the Bodaibo epicratonic sedimentary basin and its intraplate tectono-thermal transformation in the Archean, Paleoproterozoic and Paleozoic. [ABSTRACT FROM AUTHOR]

Miscarriage is potentially associated with abnormal epigenetic regulation of genes responsible for the development of the embryo and placenta. The aim of this work was to analyze the methylation level of various subfamilies of the LINE-1 retrotransposon, which makes up about 17% of the entire genome, in chorionic villi of spontaneous abortions of the first trimester of pregnancy with different karyotypes, including the most common aneuploidies. The methylation profile in the LINE-1 retrotransposon promoter was analyzed using targeted bisulfite massive parallel sequencing in chorionic villi of induced abortions (n = 39), spontaneous abortions with normal karyotype (n = 173), trisomy 16 (n = 62) and monosomy X (n = 46), and peripheral blood lymphocytes of healthy volunteers (n = 17). The level of methylation of the LINE-1 retrotransposon subfamilies in the control groups of adult lymphocytes and chorionic villi of induced abortions was the highest for evolutionarily young L1HS subfamilies, lower for the more ancient L1PA2 and L1PA3 subfamilies, and the lowest for the even more ancient L1PA4 subfamily. In the groups of spontaneous abortions, an increased level of LINE-1 methylation was observed, and this effect was more pronounced for the older LINE-1 subfamilies. The revealed patterns indicate less control over the older subfamilies of the LINE-1 retrotransposon in the human genome, which can potentially be used as regulatory elements for nearby genes involved in embryonic development. An increase in the level of methylation of such sequences can disrupt the development of the placenta and embryo and make a certain contribution to miscarriage. [ABSTRACT FROM AUTHOR]

LINE-1 retrotransposon is the most common mobile genetic element in the genomes of various mammals, including humans. Its genes are represented by the greatest number of copies. For a long time, it has been considered that the presence of LINE-1 in genome reflects the limited ability of cells to eliminate it, and the retrotransposon activity is negative owing to the insertional mutagenesis. In recent years, the increased expression of LINE-1 retrotransposon and the activity of their encoded proteins observed in mammalian cells at different stages of development and, first of all, in early embryogenesis have been discussed in the literature. Is early embryogenesis the stage of development when the organism is more susceptible to the activity of retrotransposons, or does LINE-1 play some positive role in early embryonic development? This review is aimed at classifying the available data on the epigenetic regulation and the role of LINE-1 retrotransposon in embryogenesis of mammals. The link between the mechanisms of regulation of LINE-1 expression and the waves of epigenetic reprogramming is tracked in germ cells, during fertilization, and in blastocyst, as well as during the differentiation of embryonic and extraembryonic tissues. [ABSTRACT FROM AUTHOR]

Early stages of human embryonic development are characterized by the spatiotemporal coincidence of events of total epigenetic genome reprogramming and elevated level of mosaic forms of numerical chromosome abnormalities. It is possible that the abnormal reprogramming of various regions of the genome can lead to violations of local epigenetic chromatin organization and gene expression, which affect the correct chromosome segregation during mitosis. In this study, a comparative analysis of the methylation index of LINE-1 retrotransposon, which largely reflects the methylation profile of the genome, is performed in placental tissues of spontaneous abortions with complete and mosaic forms of aneuploidy and with a normal karyotype, as well as in the control group of induced abortions of the first trimester of pregnancy. It was shown that extraembryonic mesoderm and chorionic cytotrophoblast of spontaneous abortions with chromosomal mosaicism are characterized by the highest index of LINE-1 methylation among all studied groups. At the same time, the excessive hypomethylation of transposable genetic element was registered in spontaneous abortions with normal karyotype. We hypothesize that violations of parental genome demethylation during epigenetic reprogramming at preimplantation stages of development may be associated with an increased frequency of mitotic errors in chromosome segregation, which leads to the formation of a mosaic karyotype. [ABSTRACT FROM AUTHOR]

The article focuses on a study which discusses melt and fluid inclusions in the formation of granitoids of Caucasus Mineral Waters (CMW). A table is also presented which depicts sequence and conditions of crystallization of minerals from granitoids of CMW. According to the study, formation of dark bands with complex folds provides evidence for strong mobility of the melt due to its saturation with volatile components.

The methylation profiles of the placental tissues of human embryos with normal karyotype and trisomy 16 were compared using an Infinium HumanMethylation27 BeadChip array (Illumina, United States). Numerous differences between the extraembryonic tissues with diploid and aneuploid karyotypes were observed. The extraembryonic mesoderm of embryos with trisomy 16 appeared to be less methylated than the diploid tissue, whereas the cytotrophoblast of aneuploid embryos was hypermethylated. The presence of the supernumerary chromosome was shown to influence the epigenetic profile of the genome by changing the level of methylation of CpG sites of all chromosomes. However, the largest number of differentially methylated loci was found on chromosome 16. Furthermore, more often, the epimutations were tissuespecific. In both tissues, the hypomethylated genes belong to the groups of genes responsible for different metabolic processes, whereas the hypermethylated genes control the processes of development, cell adhesion, immune response, and response to stimulus. [ABSTRACT FROM AUTHOR]

For the first time, the epigenetic status of breast benign proliferative processes, malignant breast tumors, and metastases to regional lymph nodes has been studied using the GoldenGate Cancer Panel I DNA methylation microarray (Illumina, United States). The functional groups of differentially methylated genes were identified in each set of samples. The aberrant methylation of genes that regulate cell proliferation and mobility was found in the samples of benign proliferative breast processes. The aberrant methylation of genes responsible for cell differentiation and proliferation, as well as protein phosphorylation and cell mobility, was observed in the samples of malignant breast tumors. The differential methylation of the genes that regulate cell adhesion, the formation of anatomical structures, angiogenesis, immune response, signal transduction, and protein phosphorylation were found in samples with metastases to regional lymph nodes compared to the unaltered breast epithelium. It was found that tissues that range from benign proliferative processes and metastases to regional lymph nodes were generally characterized by a relatively lower level of epigenetic variability compared to the tissues of the primary tumor. [ABSTRACT FROM AUTHOR]

For the first time, DNA methylation patterns in the human cytotrophoblast and the extraembryonic mesoderm were determined using a genome-wide Infinium HumanMethylation27 BeadChip Array (Illumina, United States). These tissues are derivatives of the trophectoderm and the inner cell mass of the blastocyst and have substantial differences in the dynamics of epigenetic genome reprogramming during early stages of differentiation. It was shown that the genome of the extraembryonic mesoderm cells was more methylated than that of the cytotrophoblast, similarly to the findings in other mammalian species. There were differences in the methylation patterns of single CpG dinucleotides and dinucleotides located within promoter CpG islands: in both tissues most single CpG dinucleotides were methylated, promoters CpG island sites were not. A comparative analysis revealed 202 differentially methylated genes in the extraembryonic mesoderm and 40 such genes in the cytotrophoblast. These genes are responsible for a number of diverse biological processes. However, in the extraembryonic mesoderm, a majority of genes identified were responsible for DNA binding and transcriptional factor activity, whereas those identified in the cytotrophoblast were responsible for transport and protein and cytokine secretion. [ABSTRACT FROM AUTHOR]

Epigenetic mechanisms of cell cycle regulation providing for maintenance of genome stability and precise transmission of hereditary information to the daughter cells attract considerable interest. Up-to-date molecular technologies allow the genome-wide methylation pattern to be determined in a single experiment. In this work, we pioneered in determining the epigenetic status of the placental tissues of the human embryos with mosaic karyotype using a genome-wide Illumina Infinium HumanMethylation27 BeadChip array (Illumina, United States), comprising 27578 CpG dinucleotides contained in 14475 genes. The groups of genes associated with the cell cycle and its regulation that contain differentially methylated CpG sites in their promoter regions have been determined. It was demonstrated that the methylation level most frequently changed in oncogenes ( ARHGEF1 and FGF5), tumor suppressors ( APC2, BRACA2, DCC, GRLF1, RB1, TP73, TSPYL2, and VHL), and the genes involved in the regulation of chromosome segregation ( CNTROB, GMNN, PROCR, and TACC1). [ABSTRACT FROM AUTHOR]

The sex ratio and X-chromosome inactivation were analyzed in placental tissues of human spontaneous abortuses with pure and mosaic forms of chromosome 16 trisomy. The sex ratio value was found to decrease with an increase in the share of cells with the trisomic karyotype, which suggests differential survival of embryos belonging to different sexes. The pattern of X-chromosome inactivation in cells of extraembryonic mesoderm in the control group of embryos and in spontaneous abortuses with the level of trisomy 16 below 80% corresponded to random X-inactivation, whereas in most embryos with a frequency of trisomy 16 exceeding 80% skewed inactivation was observed. Our results support the hypothesis about the existence of an autosomal transfactor influencing the initiation of X-chromosome inactivation and suggest its possible localization on chromosome 16. [ABSTRACT FROM AUTHOR]

The methylation status of the promoter region of the cell cycle gene P14ARF was studied in the extraembryonic mesoderm and in the cytotrophoblast of 46 human spontaneous abortions with chromosomal mosaicism. Aberrant methylation of alleles of this gene was revealed for the first time in placental tissues of 9% of embryos. The identified epimutations were found to be characteristic of embryos with aneuploid cell clones of postzygotic origin. It is suggested that epigenetic inactivation of loci responsible for the regulation of cell division and for segregation of chromosomes is associated with the origin of mosaic forms of the karyotype at early stages of human embryonic development. [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]

The paper presents data on the miaskite syenites of the Lovozero massif, pulaskites of the Khibiny massif, rocks of the larvikite–lardalite series of the Kurga massif, and subalkaline volcanics, which are preserved as remnants in the roof of the massifs. The studied rocks are characterized by a low agpaitic coefficient of <1, the absence of minerals typical of peralkaline rocks (eudialyte, aenigmatite, etc.), and the presence of zircon. The morphological features and chemical composition of zircon from miaskite of the Lovozero massif syenite indicate that the mineral is of magmatic nature. The crystallization age of the miaskites was dated on zircon at 373 ± 5 Мa. The isotope-geochemical characteristics of rocks of the subalkaline series indicate that the miaskites of the Lovozero massif are of mantle origin, show no indications of their crustal contamination, and were produced during the evolution of ankaramite melt. The pulaskites of the Khibiny massif were formed according to an analogous scenario, except their assimilation with crustal material, whose proportion did not exceed, according to model calculations, 10%. [ABSTRACT FROM AUTHOR]

This article presents the results of U–Pb geochronological study of gneiss-granites of the Mamskaya zone. The age estimate of 1874 ± 9 Ma (SIMS method) obtained for the magmatic protolith of gneiss-granites for the first time proves the close formation time of gneiss-granites from the Mamskaya zone and rapakivi-like granites of the Kodar complex in the Chara–Olekma block. In the Late Devonian and Carboniferous, according to preliminary data, the Paleoproterozoic protolith of the gneiss-granites underwent deep metamorphic processing during shear deformations and formation of pegmatoid granites and pegmatites. [ABSTRACT FROM AUTHOR]

The results of a comparison of the long-term population dynamics of seabirds breeding in the western part of the White Sea on both protected and unprotected islands are presented. A series of observations was conducted for more than 50 years in the Kandalaksha Nature Reserve and for more than 30 years in the Solovetskii Archipelago. The dynamics of the breeding part of the population were analyzed for six species occurring in both study areas. The population trends of the common eider Somateria mollissima, the European herring gull Larus argentatus, and the black guillemot Cepphus grylle, were the same in the two areas, while those of the Eurasian oystercatcher Haematopus ostralegus, the common gull Larus canus, and the ruddy turnstone Arenaria interpres differed. The uniform trends are due to similar natural conditions of the breeding and wintering grounds of the birds in the Solovetskii Archipelago and Kandalaksha Bay. The discrepancies are mostly associated with different protection regimes on the islands used for breeding, as well as with an increased pressure of both terrestrial and avian predators on seabird colonies in recent decades. [ABSTRACT FROM AUTHOR]

The crystalline complexes of the Hercynian South Altai Metamorphic Belt (SAMB), which is a part of the Central Asian Foldbelt more than 1500 km long. They compose different-scale tectonic plates, the level of metamorphism in which at the early stages reached the conditions of high-temperature amphibolite subfacies and, in places, granulite facies. In terms of tectonics, the band of their outcrops is confined to the margin of the North Asian Caledonian continent, stretching from southeast to northwest along the southern slope of the Gobi, Mongolian, and Chinese Altai to Eastern Kazakhstan, where they are represented in the Irtysh shear zone. The SAMB includes poly- and monometamorphic complexes. The age of granitoids formed at the late episode of metamorphism was determined for the Tsel tectonic plate of the Gobi Altai in the southeastern part of the SAMB: from 374 ± 2 to 360 ± 5 Ma. These and previously obtained results show that the early stage of low-pressure metamorphism and the late stage of high-pressure metamorphism occurred in the age intervals of ~390–385 and 375–360 Ma, respectively, almost throughout this belt. A short-term stage of stabilization was between these stages. These processes occurred during the closure of the basin with the Tethys-type oceanic crust of the South Mongolian Ocean (paleo-Tethys I). The spatial position of the SAMB is determined by the asymmetric structure of the basin, in which the active continental margin is represented along its northern part, and the passive one is represented along the southern one (in modern coordinates). [ABSTRACT FROM AUTHOR]

Differentiation of induced pluripotent stem cells (iPSCs) from patients and healthy donors allows in vitro study of genetic disorders. The authors have previously reported a clinical case of recurrent pregnancy loss in a patient with skewed X-chromosome inactivation in peripheral blood lymphocytes, endometrium, and buccal epithelium. A 239 kb microdeletion at Xq24 that affected eight genes, including UBE2A, has been found. In this work, an iPSC line iTAF15Xsk4 was produced from the patient's skin fibroblasts using nonintegrating episomal vectors. The iPSC line had a normal karyotype, expressed pluripotency markers, and expressed markers of all three germ layers upon differentiation in embryoid bodies. This cell line could be used for the UBE2A deficiency syndrome study. [ABSTRACT FROM AUTHOR]

The U-Pb (ID TIMS) geochronological studies of single zircon grains and their fragments have made it possible to establish that rare-metal alkaline granites of the Katugin massif (2055 ± 7-2066 ± 6 Ma) underwent high-temperature transformations at age levels of ~1921 ± 5 and 1876 ± 7 Ma. [ABSTRACT FROM AUTHOR]

The results of U–Th–Pb (LA-ICP-MS) geochronological studies of detrital zircon from metasandstones of the Kodar Group of the Udokan Complex of the Aldan Shield are presented. It has been established that the Kodar Group of the Udokan subzone of the Kodar–Udokan trough has an age of 2.08–2.05 Ga. The provenance areas of the Kodar Group deposits were the Archean (ca. 2.65, 2.83, and 3.23 Ga) igneous and metamorphic complexes of the Chara–Olekma Geoblock of the Aldan Shield and the adjacent territory of the Stanovoi suture zone, as well as Paleoproterozoic (ca. 2.08 Ga) island arcs or active continental margin complexes that existed in the southern margin of the Archean Chara–Olekma Geoblock and are unidentified on the present erosional level. It is assumed that rocks of different ages, belonging both to the Kodar Group of the Udokan Complex and to the metamorphic complexes of the Stanovoi suture zone, can be tectonically juxtaposed in the southern part of the Udokan subzone of the Kodar–Udokan trough. [ABSTRACT FROM AUTHOR]

The results of geochronological study (U–Pb SHRIMP-II) of zircons from granodiorites and plagiogranites of the main phase of the Tallai pluton of the Baikal–Vitim belt are presented. The obtained estimates of the age of the magmatic cores of zircons from granodiorite and plagiogranite coincide with each other within the limits of errors and are interpreted as the age of crystallization of rocks of the main phase of the Tallai pluton, 661 ± 6 Ma. The weighted average value of the age of the metamorphic rims of zircon from these rocks is 637 ± 5 Ma. The high positive values of εNd (660), +7.2 and +7.3, in the rocks of the main phase indicate a juvenile source of the parental melts. Based on new and earlier published geochronological data, a conclusion about the formation of Late Baikalian juvenile gabbro–granite associations of the same type within the Baikal–Vitim belt 660 million years ago (Tallai complex) and in the interval of 603–615 Ma (Padora complex) was made. [ABSTRACT FROM AUTHOR]

This paper reports the results of U–Pb geochronological (ID–TIMS) studies of garnet and U–Th–Pb (LA–ICP–MS) “screening” geochronological studies of zircon from pyroxene–carbonate rocks of the Ukduska massif. The U–Pb dates of garnets (1881 ± 8 Ma) and zircon rims (1865 ± 16 Ma) are indicative of the Early Proterozoic age of these rocks. The geochronological results make it possible to identify a new carbonate magmatism stage within the southeastern part of the Chara–Olyokma geoblock. [ABSTRACT FROM AUTHOR]

New geochronological (U–Pb ID-TIMS) data on zircons from pegmatites of the Mama mica belt in the Baikal Highlands are presented. The ages obtained for the plagioclase pegmatites (388 ± 2 and 389 ± 2 Ma, Mochikit deposit) and two-feldspar pegmatites (333 ± 1 and 332 ± 3 Ma, Slyudyanka deposit) demonstrate a significant age gap (50–60 Ma) between them. Based on the entire set of geological and new geochronological data available, it is proposed to divide the Mama complex, to which they were previously assigned, into two separate granitoid complexes. [ABSTRACT FROM AUTHOR]

The estimation of crystallization and metamorphic reworking ages of mafic rocks in the polycyclic Precambrian areas is a difficult problem. Magmatic baddeleyite can be partially or completely replaced by polycrystalline zircon within a wide range of temperature and pressures, from greenschist to granulite facies. Evaluation of the age of each phase of the zircon–baddeleyite aggregates can provide information on both the age of the magmatic crystallization and metamorphism. U-Th-Pb (SHRIMP-II) and U-Pb (ID-TIMS) geochronological studies were carried out for single baddeleyite grains and zircon–baddeleyite aggregates from gabbronorites ("drusites") of the Ambarnsky massif (Belomorian Province, Fennoscandian Shield). The petrological studies indicate the simultaneous growth of coronas at the olivine–plagioclase boundary and zircon rims around baddeleyite. U-Pb (ID-TIMS) dating of single baddeleyite grains yielded 2411 ± 6 Ma crystallization age of gabbronorites of the Ambarnsky massif. U-Pb (ID-TIMS) dating coupled with the discrete chemical abrasion give an age of 1911 ± 35 Ma for metamorphic zircon rims. The obtained results indicate that coronitic textures in the gabbronorites were formed 500 million years later than the magmatic crystallization of rocks as a result of the granulite-facies metamorphism that was probably related to the Lapland-Kola orogeny. [ABSTRACT FROM AUTHOR]

The paper presents data on the geological structure of the Kichera zone of the Baikal–Vitim belt (BVB) at the boundary between the marginal part of the Siberian craton and the Barguzin–Vitim superterrane of the Central Asian Orogenic Belt. Early Neoproterozoic (Early Baikalian) and Late Neoproterozoic (Late Baikalian) structures and complexes are identified and characterized in the Kichera zone of the BVB. Data are presented on the geochemistry of the rocks and on their U–Pb isotope age (zircon, SIMS and ID-TIMS) and on the Nd isotope characteristics of rocks from various parts of the Kichera zone, including representative rock association of the Nyurundukan migmatite–tonalite–metabasite complex with MORB-type tholeiites and tholeiites with intraplate geochemical features. It is shown that the sources of the Early Neoproterozoic complexes of the Kichera zone, which were metamorphosed at 0.76–0.74 Ga as a result of accretion events in the marginal part of the craton, were dominated by Early Precambrian recycled crustal material. The Late Neoproterozoic complexes typomorphic of the Kichera zone were formed in the Cryogenian–Ediacaran (720–545 Ma) from prevailing juvenile sources. Our data suggest that the metabasites of the Nyurundukan complex were formed in an environment of segmented troughs of the pull-apart paleorift system of the Kichera zone and can be compared with a reduced complex of continental-margin ophiolites transformed at 630 ± 7 to 615 ± 3 Ma. The destruction of the ancient continental crust of the craton ended with the formation and exhumation of deep rocks in the Late Ediacaran, the emplacement of adakite granites of the postcollisional geochemical type, and the formation of grabens filled with a terrigenous complex. The juvenile and riftogenic crust produced during the Late Neoproterozoic tectonic evolution of the Kichera rift zone does not show any features of mature continental-type crust. [ABSTRACT FROM AUTHOR]

Current near a round local ventilation suction port in the form of a funnel situated above an impermeable plane is considered. Limiting trajectories of dust particles are constructed in the velocity field found from a new computer program and the capture coefficient as a function of the slope and length of the funnel and distance from the plane is determined. The geometric dimensions of the separation region at the inlet to the funnel as functions of the distance from the plane and the length of the funnel are determined. [ABSTRACT FROM AUTHOR]

A mathematical model and computer program for use in calculating the separation region at the inlet to a funnel situated above an impermeable plane are developed by means of stationary discrete vortex rings. The basic computational relationships and algorithms for calculating the characteristic regions of detached flow, the limiting trajectories of dust particles, and the ventilation region are presented. [ABSTRACT FROM AUTHOR]

Syncollisional granite generated in zonal metamorphic complexes at 500-700°C and various pressure and in the presence of fluid of various composition are proved to differ in proportions of granite material generated by metamorphic, metasomatic, and magmatic processes. Monometamorphic low-pressure complexes devoid of the influx of foreign solutions are characterized by the most intense metamorphic differentiation: the dissolution and redeposition of quartz and plagioclase into lower pressure zones and the development of plagiomigmatites. The process starts with deformations of the schists at 500-550°C. The main factors (at a constant total composition of the rock) is an uneven pressure distribution and metamorphic solutions. This stage is followed by metasomatic granitization, which is initiated if shear motions and decompression are associated with influx of silicic alkaline solutions into the rocks and their transformation into migmatite (up to granite-gneiss). Granitization during this stage is controlled by an increase in the permeability of the rocks and the introduction of perfectly mobile Si, Na, and K and removal of Mg, Ca, and Fe, which modifies the composition of the rocks and makes them similar to granite. Metasomatic granitization may take place in low-pressure polymetamorphic complexes. Under a high lithostatic pressure and in the presence of water-carbon dioxide fluids (kyanite-sillimanite facies series of metamorphism), the magmatic process begins at higher temperatures. The early stages are dominated by metamorphic differentiation and metasomatic sodic migmatization. The rocks modified by these processes (their salic and mafic minerals are segregated) are affected by anatexis at 650-700°C (partial melting of the granite eutectic) and, at higher temperatures, by diatexis, which generates granite melts able to migrate. These processes are variably pronounced in all metamorphic complexes. [ABSTRACT FROM AUTHOR]

The possibility of the application of high-uranium self-irradiation-damaged metamict zircon for U-Pb geochronological studies (ID-TIMS) after preliminary high-temperature annealing and acid treatment was demonstrated using zircon from the Li–F granites of the Turga massif (Eastern Transbaikalia). Optimal conditions of high-temperature annealing and acid treatment of zircon with high self-irradiation α-dose can be selected to remove completely a metamict phase and preserve sufficient quantities of the mineral for U-Pb (ID-TIMS) studies. [ABSTRACT FROM AUTHOR]

The central portion of the Aldan Shield hosts very widely spread Archean and Early Proterozoic granitoids, much of which are granite-gneisses. Geochemical lines of evidence, data on inclusions in minerals, and Sm-Nd isotopic geochemical data suggest that the protoliths of granite-gneisses in the central part of the Aldan Shield were granitoids that had various composition, age, and were derived from distinct sources and under different parameters and were then emplaced in different geodynamic environments. The granitoids belong to at least two types of different composition that occur within spatially separated areas. The protoliths of granite-gneisses in the western part of the Western Aldan Megablock and the junction zone of the Chara-Olekma and Aldan geoblocks (granite-gneisses of type I) had the same age and affiliated to the same associations as the within-plate granitoids of the Nelyukinskii Complex. Their parental melts were derived at 2.4-2.5 Ga by the melting of Archean tonalite-trondhjemite orthogneisses of the Olekma and Aldan complexes. The protolith of granite-gneisses in the eastern portion of the Western Aldan Megablock (granite-gneisses of type II) can be subdivided into two groups according to their composition: granitoids with geochemical characteristics of subduction- and collision-related rocks. The protoliths of the type-II granite-gneisses with geochemical characteristics of subduction granitoids were produced simultaneously with the development of the Fedorovskaya island arc (at 2003-2013 Ma), whereas the protoliths of the type-II granite-gneisses with geochemical characteristics of collision granitoids were formed in the course of accretion of the Fedorovskaya island arc and the Olekma-Aldan continental microplate at 1962-2003 Ma, via the melting of magmatic rocks of the Fedorovskaya unit and older continental crustal material. [ABSTRACT FROM AUTHOR]

The chemical compositions of Phanerozoic basalts of all known geodynamic settings (mid-ocean ridges, oceanic plateaus, oceanic islands, island arcs, fore-arc and back-arc basins, continental rifts, large igneous provinces) are compared with Archean basalts, including basalts of greenstone belts and high-grade gneiss complexes. Linear discriminant analysis has shown that the Archean basalts differ significantly from Phanerozoic basalts in terms of the content of the least mobile major and trace elements. In this regard, the geochemical systematics of Phanerozoic basalts in most cases cannot be used to reconstruct the geodynamic settings of Archean basalts. The results obtained are illustrated by the example of the Mesoarchean basalts of the Olondo fragment of the Tokko–Khani greenstone belt. [ABSTRACT FROM AUTHOR]

The problem of efficiency of using electrical properties for characterizing graphene structures obtained by chemical vapor deposition and formed on substrates of various materials (copper foil, glass, silicon, and Al2O3) is investigated. This study demonstrates the high sensitivity of the Kelvin-probe method as well as the methods of scanning capacitance and electrostatic microscopy to the number of graphene layers on the surface of substrates made of various materials. [ABSTRACT FROM AUTHOR]

Purpose: To study the contribution of embryo chromosomal abnormalities in primary and secondary recurrent pregnancy loss (RPL) and to analyze the recurrence of chromosomal constitution in miscarriages from the same couple. Methods: Retrospective study of abortion karyotypes in RPL families based on the mother's primary or secondary RPL status (563 embryo specimens, 335 samples from primary, and 228 samples from secondary RPL). RPL was defined as two or more consecutive miscarriages. One hundred eight cases of recurrent embryo/fetal loss in 51 families were analyzed to assess the probability of having the same karyotype pattern (recurrent normal or recurrent abnormal) in both previous and subsequent pregnancy loss. The karyotypes of abortions were established using standard cytogenetic analysis, as well as interphase fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH). Results: The frequency of aberrations was 43.9% in abortions from primary RPL versus 52.6% in secondary RPL (p = 0.041). Women 35 years of age or older were the main contributors to this difference. The odds ratio of a subsequent abortion having the same karyotype pattern (normal or abnormal) as the previous one was 6.98 (p = 0.0013). Conclusion: The frequency of abnormalities is higher in abortions from the secondary RPL versus primary RPL group, and this difference is due to the relative deficiency of miscarriages with abnormal karyotypes in older women with primary RPL. The probability of having the same karyotype pattern (recurrent normal or recurrent abnormal) in the previous and subsequent abortion is increased significantly compared with chance. [ABSTRACT FROM AUTHOR]

The Dotulur alkalic granite and Usugli Depression volcanics (West Stanovoi Superterrane of the Central Asia Fold Belt) have been dated by the U-Pb method, and their geochemistry has been analyzed. The geochemistry of the rocks suggests their intraplate nature. The alkalic granite and volcanics have similar ages of 142 ± 1 Ma and 138 ± 3 Ma, respectively. Considering the Usugli Depression structural position as an upper fault slice of the Elikan metamorphic core, the obtained dates allow the formation of the mentioned core and, accordingly, the collapse of central part of the Mongol-Okhotsk orogeny to have occurred not prior to 140 Ma. [ABSTRACT FROM AUTHOR]

New U-Pb zircon (TIMS) results allow dating of protoliths of tonalite-trondhjemite orthogneisses of the Olekma Complex in the central part of the Chara-Olekma Geoblock (Aldan Shield) to 2825 ± 3 Ma and 2994 ± 3 Ma. Together with the results of previous geochronological studies, this proves that the Olekma Complex comprises heterochronous igneous rocks intensively reworked under amphibolite facies conditions and formed during different stages of geological evolution of the Aldan Shield. [ABSTRACT FROM AUTHOR]

Results of U-Th-Pb LA-ICP-MS analysis of detrital zircons from metasandstones of the Chiney Subgroup (Udokan Group, Aldan Shield) have been obtained. It has been revealed that rocks of the Paleoproterozoic (about 1.90, 1.98, and 2.50 Ga) and Neoarchean (2.55 and 2.72 Ga) were their provenance sources. Deposition of the Chiney Subgroup occurred in the interval 1.87-1.90 Ga and was separated in time from the accumulation of the Kodar Subgroup siliciclastics (2.1-2.3 Ga). [ABSTRACT FROM AUTHOR]

Biotite plagiogranite intruding sediments of the Kodar Sub-Group of the Udokan Group that have both undergone amphibolite grade alterations has been dated by the U-Pb ID TIMS technique using zircon to 2105 ± 6 Ma. This age estimate to a first approximation corresponds to the younger age limit of deposition of the siliciclastics in the lower section of the Udokan Group. [ABSTRACT FROM AUTHOR]

The Kichera zone of the Baikal-Muya Belt consists of alternating tectonic plates with rocks of different metamorphic facies. Garnet-cordierite-sillimanite gneiss from the tectonic fragment in granite-gneiss of the Baikal massif with an age of 755 ± 15 Ma from the Goremyka plate and two-pyroxene schist of the granulite complex with an age of 617 ± 5 Ma from the Boguchan plate were studied. Thermobarometric studies of these key metamorphic rocks were carried out using the avPT (THERMOCALC) and TWEEQU (TWQ 2.01) methods. The P-T parameters estimated for the cordierite⎯sillimanite gneiss of the Goremyka plate correspond to the boundary between the amphibolite and granulite facies. Granulites of the Boguchan plate belong to the HT-LP type. Exhumation of metamorphic rocks could be caused by extension upon the evolution of the Late Baikal rifting. [ABSTRACT FROM AUTHOR]

We studied the petrography, mineralogy, and geochemistry of the Paleoproterozoic (2.06 Ga) granites of the Katugin massif (Stanovoy suture zone), which hosts the combined rare-metal Katugin deposit. Three groups of granites were distinguished: (1) biotite ( Bt) and biotite-riebeckite ( Bt-Rbk) granites of the western block of the massif; (2) biotite-arfvedsonite ( Bt-Arf) granites of the eastern block; and (3) arfvedsonite ( Arf), aegirine-arfvedsonite ( Aeg-Arf), and aegirine ( Aeg) granites of the eastern block. The Bt and Bt-Rbk granites of the first group are mainly metaluminous and peraluminous rocks with rather high CaO contents and the minimum F contents among the granites described here. It was suggested that the granites of this group could be derived from a source dominated by crustal rocks with a small addition of mantle materials. These granites probably crystallized from a metaluminous-peraluminous melt with elevated CaO and moderate F contents. Melts of such compositions are least favorable for the crystallization of ore minerals. The Bt-Arf granites of the second group are mainly peralkaline and show high contents of CaO and Y and low contents of NaO and F. A mixed mantle-crust source was proposed for the Bt-Arf granites. The initial melt of the Bt-Arf granites could have a peralkaline composition with elevated CaO content and moderate to high F content. The Arf, Aeg-Arf, and Aeg granites of the third group are enriched in ore mineral and were classified as peralkaline granites with very low CaO contents, elevated Na2O and F contents, and usually very high contents of Zr, Hf, Nb, and Ta. Based on the geochemical and isotopic data, it was supposed that the source of the granites of the third group could be derivatives of basaltic magmas produced in an OIB-type source with a minor addition of crustal material to the magma generation zone. It was suggested that the primary melt of this granite group could be a peralkaline CaO-poor and F-rich silicic melt, which is most favorable for the crystallization of ore minerals. Based on the analysis of the geochemical characteristics of the three granite groups and their relationships within the Katugin massif, a qualitative model of its formation was proposed. According to this model, the Bt and Bt-Rbk granites of the western block crystallized first, followed by the Bt-Arf granites of the eastern block and, eventually, the Arf, Aeg-Arf, and Aeg granites enriched in ore minerals. [ABSTRACT FROM AUTHOR]

The first results are presented for U-Pb SHRIMP-II dating of zircons from the upper part of the Khivachian regional horizon (stage) of the Regional Stratigraphic Scale (RSS) of the Permian in northeastern Russia. The obtained isotope age of 255 ± 2 Ma is close to that of the present boundary between the Wuchiapingian and Changhsingian stages of the Permian system in the International Stratigraphic Scale (254.1 Ma). Based on the distribution of bivalves- Intomodesma spp. and Claraioides aff. primitivus (Yin)-in the sections considered, their relations to the stratigraphic positions of the samples considered and dated formerly, and in view of the interregional correlation of recent δС data for clayey rocks, one may assume with certainty that most of the regional zone of Intomodesma costatum corresponds to the upper part of the Wuchiapingian stage. Here, the Changhsingian stage in northeastern Asia complies only with the uppermost part of this zone within the I. postevenicum subzone and, partially, of Otoceras layers within the Otoceras concavum zone. [ABSTRACT FROM AUTHOR]

Geochemical and Sm-Nd isotope-geochemical studies of synnyrite and syenite from the Synnyr massif and high-K syenite from the Tas massif of the Late Paleozoic (eastern Siberia) corresponding to one of the largest provinces of high-K and ultrapotassic magmatism worldwide are performed. It is shown that their formation was controlled by transformation of the Precambrian continental crust of the Siberian Craton and Central Asian Mobile Belt under the influence of the Siberian mantle plume. [ABSTRACT FROM AUTHOR]

Based on the results of Sm-Nd isotopic geochemical and U-Th-Pb geochronological LA-ICP-MS studies, it has been established that the formation of metamorphic rock protoliths of the Stanovoi Complex in the western Dzhugdzhur-Stanovoi Superterrane of the Central Asian Foldbelt took place over the following time spans: 2750-2860 Ma (Ilikan Group of the Ilikan Zone), 1890-1910 Ma (Bryanta Group of the Bryanta Zone), and ~2.0 Ga (Kupuri and Zeya groups of the Kupuri and Zeya zones, respectively). It has been shown that the western part of the Dzhugdzhur-Stanovoi Superterrane was formed ~1.9 Ga ago, as a result of collision of the Neoarchean Ilikan Terrane, the Paleoproterozoic island arc, and the Paleoproterozoic Kupuri-Zeya Terrane. The data make it possible to consider the Kurul'ta, and Zverevo blocks of the Stanovoi Structural Suture and the Ilikan Terrane of the Dzhugdzhur-Stanovoi Superterrane of the Central Asian Foldbelt as constituents of a common terrane. [ABSTRACT FROM AUTHOR]

It has been demonstrated on basis of Sm-Nd isotopic analyses of the Cenozoic sands from the Chara and Tokkin Basins in the eastern flank of the Baikal rift zone that the Chara-Olekma Geoblock of the Aldan Shield is an area of intense crust growing processes occurred not only in the Paleoarchaean but in the Mesoarchaean as well. [ABSTRACT FROM AUTHOR]

In terms of chemical composition, the Late Quaternary geyserites of the Olkhon area and Olkhon Island are subdivided into the ferrosiliceous and carbonate-siliceous groups and are commonly characterized by low concentrations of rare elements. In several cases, the geyserites are enriched in Fe, Mn, Cr, Sb, As, and Y. Regardless of the chemical composition of geyserite, the key components of the gas phase are HO, CO, and CH. The parent matter for the geyserites was constituted by aqueous solutions (fluids) of 400°C and higher temperatures, silica-saturated, and enriched in carbon dioxide and hydrocarbons, as well as in some ore components. [ABSTRACT FROM AUTHOR]

The Regional Stratigraphic Scale (RSS) of the Permian deposits in northeastern Russia represents the only complete stratigraphic succession of Permian marine deposits distinguished in Russia, which serves as a standard at the correlation of Permian deposits of all regions of the eastern part of the Boreal Biogeographic Superrealm. However, a high level of faunistic endemism makes it extremely difficult to correlate directly stratons of the RSS with stages of the International Stratigraphic Scale (ISS) of the Permian deposits. The first U-Pb SIMS age datings of zircons from felsic tuffs of the Omchak Formation of the Ayan-Yuryakh Anticlinorium (the lower part of the Permian Khivachian Horizon of the RSS of northeastern Russia) allowed us to obtain the important reference level for the Upper Permian subdivision of the Permian RSS. The zircon age of 257.1 ± 3.0 Ma is in good agreement with the stratigraphic position of the studied sample, which makes it possible to correlate the surrounding deposits with the Wuchiapingian Stage of the Permian deposits in the International Stratigraphic Scale. [ABSTRACT FROM AUTHOR]

Geochronological (LA–ICP–MS) U–Th–Pb studies of detrital zircon of the Late Cenozoic sand deposits on Ol'khon Island have been performed. It has been shown that their main source is represented by Early Paleozoic igneous and metamorphic complexes of the Ol'khon Terrane of the Central-Asian Mobile belt and Late Carboniferous–Early Permian granitoids of the Angara–Vitim batholite. Sands from the source were transported over a distance of no less than 100 km. It is supposed that it was effectuated by strong air flows, over the ice on the Lake Baikal in particular. [ABSTRACT FROM AUTHOR]

The results of Sm-Nb isotopic-geochemical studies of metasedimentary and metavolcanic rocks of the Dzheltulak Group of the central part of the Dzheltulak suture, as well as geochronological U-Th-Pb (LA ICP MS) studies of detrital zircons from metasedimentary rocks, which are considered as Paleoproterozoic in current stratigraphic schemes, are presented. The age of the youngest zircons is 170-190 Ma, whereas the age of the last stage of regional metamorphism is 140-150 Ma. Thus, the Dzheltulak Group hosts metasedimentary rocks, the age of the protolith of which ranges from 140-150 to 170-190 Ma. The detrital zircons derived from intrusive and metamorphic rocks of the Selenga-Stanovoi and Dzhugdzhur-Stanovoi superterranes. [ABSTRACT FROM AUTHOR]

The Gilyui Complex includes sedimentary and volcanic rocks metamorphosed to amphibolite and epidote-amphibolite facies, which constitute blocks confined to the main structural sutures of the Dzhugdzhur-Stanovoi superterrane in the Central Asian fold belt. In recent stratigraphic scales, they are considered as being Neoarchean in age with Nd model age values of 1.5-3.0 Ga. The youngest detrital zircons from metamorphosed mudstone of the Gilyui Complex yield a date of 285 ± 4 Ma, which determines the lower age limit for the formation of its protolith. The age of crystallization of rhyolites from the Gilyui Complex is determined to be 231 ± 4 Ma. If the rhyolites form volcanic flow units or sills, the Gilyui Complex is approximately 230 Ma or 231 ± 4 to 285 ± 4 Ma old, respectively. [ABSTRACT FROM AUTHOR]

Arguments in favor of magmatic or metasomatic genesis of the Katugin rare-metal ore deposit are discussed. The geological and mineralogical features of the deposit confirm its magmatic origin: (1) the shape of the ore-bearing massif and location of various types of granites (biotite, biotite-amphibole, amphibole, and amphibole-aegirine); (2) the geochemical properties of the massif rocks corresponding to A type granite (high alkali content (up to 12.3% NaO + KO), extremely high FeO/MgO ratio ( f = 0.96-1.00), very high content of the most incoherent elements (Rb, Li, Y, Zr, Hf, Ta, Nb, Th, U, Zn, Ga, and REE) and F, and low concentrations of Ca, Mg, Al, P, Ba, and Sr); (3) Fe-F-rich rock-forming minerals; (4) no previously proposed metasomatic zoning and regular replacement of rock-forming minerals corresponding to infiltration fronts of metasomatism. The similar ages of the barren (2066 ± 6 Ma) and ore-bearing (2055 ± 7 Ma) granites along with the features of the ore mineralization speak in favor of the origin of the ore at the magmatic stage of the massif's evolution. The nature of the ore occurrence and the relationships between the ore minerals support their crystallization from F-rich aluminosilicate melt and also under melt liquation into aluminosilicate and fluoride (and/or aluminofluoride) fractions. [ABSTRACT FROM AUTHOR]