An Erratum to this paper has been published: https://doi.org/10.1134/S001670292522001X

In Drosophila , a large group of actively transcribed genes is located in pericentromeric heterochromatin. It is assumed that heterochromatic proteins recruit transcription factors to gene promoters. Two proteins, Ouib and Nom, were previously shown to bind to the promoters of the heterochromatic genes nvd and spok . Interestingly, Ouib and Nom are paralogs of the M1BP protein, which binds to the promoters of euchromatic genes. We have shown that, like M1BP, the Quib and Nom proteins bind to CP190, which is involved in the recruitment of transcription complexes to promoters. Unlike heterochromatic proteins, Ouib and Nom do not interact with the major heterochromatic protein HP1a and bind to euchromatic promoters on polytene chromosomes from the larval salivary glands. The results suggest a new mechanism for the recruitment of transcription factors into the heterochromatic compartment of the nucleus.

Biotite–garnet–sillimanite–cordierite gneisses from the Leshchev zone of the Middle Volga megablock in the Volgo-Uralian segment of the East European craton have been studied. The Sm–Nd model age of the rocks was measured at 2.8 Ga. U–Pb isotope–geochronological studies of the cores of zircons from these rocks were carried out. Several generations of zircon cores were revealed on cathodoluminescence images. The age of the main sources of detrital zircons was measured at 2.58 Ga. Single zircon grains have core ages of 2.4, 2.7, and 3.1 Ga. The calculated εNd(2500) = –0.6 indicates the crustal or mixed mantle–crustal origin of the protolith of these gneisses. The high-alumina metaterrigenous rocks of the Bolshoi Cheremshan Group, the Leshchev zone, and the South Volga supracrustal complex are considered as rock complexes of Neoarchean and Paleoproterozoic basins with a proto-cratonic basement and a passive continental margin, which supersede each other in time and space.

The Drosophila transcription factor СР190 is one of the key proteins that determine the activity of housekeeping gene promoters and insulators. CP190 has an N-terminal BTB domain that allows for dimerization. Many of known Drosophila architectural proteins interact with the hydrophobic peptide-binding groove in the BTB domain, which is presumably a mechanisms for recruiting CP190 to regulatory elements. To study the role of the BTB domain in the interaction with architectural proteins, we obtained transgenic flies expressing CP190 variants with mutations in the peptide-binding groove, which disrupts their interaction with architectural proteins. As a result of the studies, it was found that mutations in the BTB domain do not affect binding of the CP190 protein to polytene chromosomes. Thus, our studies confirm the previously obtained data that CP190 is recruited to regulatory elements by several transcription factors interacting, in addition to BTB, with other CP190 domains.

The article presents data on migmatites of the Taratash metamorphic complex, Southern Urals. We studied the Sm-Nd isotopic system in ultrametamorphic processes leading to partial melting of a protolith and migmatization. The Sm-Nd isotopic system of the rocks indicates the contribution of Paleoarchean protolith (T Nd2 = 3.2–3.6 Ga) to the Taratash metamorphic complex, with the predominance of the crustal component (ɛ Nd (T) from −7.6 to −10.5). Based on morphology, U-Pb isotopic age, and Th/U-ratio, zircon found in melanosome and leucosome of the migmatites is subdivided into two generations. The main stage of migmatization occurred within 2.1–1.8 Ga ago and was triggered by granulite metamorphism at 2.06 Ga. Zircon grains of this stage have the low uranium concentration (213–469 ppm) at typical thorium concentration (180–631 ppm), Th/U = 0.8–1.7.

Three different-age series of granitoid veins and dikes of the Baikal–Muya fold belt were studied. Two of them, plagiogranites of the ophiolite complex and the first postophiolitic plagiogranites, are associated with the suprasubduction ophiolites of the eastern Baikal–Muya belt. The third series is represented by hypabyssal tonalite–plagiogranite–leucogranite complex of the Kichera zone in the western Baikal–Muya belt. The composition and isotope-geochemical characteristics (ε Nd (T) = –0.9; –1.3) of the plagiogranite veins no more than 60 cm thick, and ε Nd (T) values (–1.8…+ 0.2) of host layered leucocratic gabbros in the Sredne-Mamakan ophiolitic complex are consistent with the previously established suprasubduction nature of the ophiolite association. Tonalites and plagiogranites of the dyke system of the post-ophiolitic magmatic series intersect the dunite–pyroxenite–gabbro banded series of the Sredne-Mamakan ophiolites of the eastern Baikal–Muya fold zone. High Sr/Y ratios and low concentrations of Y and heavy REE indicate that these granitoids are ascribed to the adakite series. LA-ICP-MS study of zircon from post-ophiolitic plagiogranites yields the crystallization age of 629 ± 5 Ma. Sm–Nd isotope-geochemical characteristics of plagiogranitoids (ε Nd (T) = +2.5; +4.0) in combination with geochemical data confirm their origin during partial melting of a mafic protolith corresponding to the Neoproterozoic oceanic crust. The adakitic granitoids in the Kichera zone of the western Baikal–Muya belt belong to the tonalite–leucogranite differentiated series of the hypabyssal complex, which has no a direct spatial relationship with unambiguous ophiolite associations. The chemical composition and Sm–Nd isotope-geochemical characteristics of these rocks (ε Nd (T) = +3.2…+7.1) indicate the heterogeneity of the predominantly juvenile island-arc or oceanic Neoproterozoic crust, which experienced partial melting at 595 ± 5 Ma.

Представлены данные о возрасте метаморфизма пород Елабужской зоны и детритового циркона из парагнейсов Елабужской зоны, их корреляция с ранее датированными породами Средневолжского мегаблока. Геохимические особенности и степень метаморфизма пород Елабужской зоны и Средневолжского блока сходны. Различие заключается в явном проявлении палеопротерозойского метаморфизма изученных пород Елабужской зоны, что контрастирует с ситуацией в Средневолжском геоблоке, где метаморфизм такого возраста не проявлен. Изучение U-Pb-изотопной системы внешних зон циркона Елабужской зоны деформаций даёт основание считать, что метаморфическое преобразование пород происходило в два этапа, 1,99 и 1,95 млрд лет назад.

This data on the age of metamorphism of rocks of the Yelabuga zone and the geochronological data on detrital zircon from paragneisses of the same zone are presented, and their correlation with the ages of rocks from the Middle Volga megablock is made. The rocks of the Yelabuga zone and Middle Volga megablock have similar geochemical characteristics and degrees of metamorphism, but demonstrate the following differences: Paleoproterozoic metamorphism was clearly expressed in the studied rocks of the Yelabuga zone, which contrasts to rocks of the Middle Volga megablock, where no metamorphism of this age is manifested. The study of the U–Pb isotopic system in external zones of zircon crystals from the Yelabuga deformation zone suggests that rocks underwent two stages of metamorphism, 1.99 and 1.95 Ga ago.

The paper discusses the Białowieża bison (Bison bonasus bonasus) as a museum exhibit in the 18th – early 20th centuries, basing on the analysis of archival documents, mainly from St. Petersburg. One of the last remnants of extinct megafauna once roaming through Europe, by the Early Modern time it had been eliminated in the most part of its previous range. In the 16th–18th century, it had the status of a natural curiosity and an exclusively royal game. In the 18th century, the carcasses of the European bison from the imperial menageries went into the cabinets of curiosities where they became the objects of study for naturalists. By the late 18th century, the last population of the European lowland bison had survived in Białowieża Primeval Forest, which became a part of the Russian Empire with the Third partition of Poland. The attention of the Imperial family, which preserved the system of protection of the European bison and the forest where they lived, ensured the survival of the species till WWI. The development of zoology and zoological collections provided a new status to the Białowieża bison – the status of a valuable gift of the Russian Tsar to a scientific community. To receive such a precious gift, a scientific community had to use its diplomatic and bureaucratic channels, to recruit a naturalist willing to travel to Białowieża, to organize a hunt, to process the skin and bones, and finally, to deliver this massive package to a museum. Nevertheless, throughout the second half of the 19th century, most requests made by European and Russian naturalists were granted and the majority of zoological museums received the European bison from Białowieża, either in form of a stuffed animal, a skeleton, or at least a skull. The transformation of the 17–18th century Kunstkammern into research zoological institutions and the development of taxidermy went in parallel with the transformation of the European bison as a museum exhibit. Stuffed animals became anatomically accurate; new expositions included habitat groups, and some institutions amassed extensive collections for comparative study. The presence of the European bison almost in every major European museum made them well known for wider public. In 1919, the last Białowieża bison was killed in the wild, but the popularity of this species helped the restitution of the animal. Nowadays, the “old” specimens are of interest not only from a historical point of view, but also as a source of samples for genetic research.

Приводятся результаты изотопно-геохронологического изучения метаосадочных пород большечеремшанской серии Волго-Уральского сегмента Восточно-Европейского кратона с целью выявления их древнейшей составляющей. Для 16 образцов высокоглиноземистых гнейсов и кристаллосланцев, отобранных из керна скважин, было проведено Sm-Nd изотопное исследование и рассчитаны модельные возрасты TNd(DM). Из пород с максимальными значениями модельных возрастов (выше 3.2 млрд лет) были выделены акцессорные цирконы в трех скважинах: Миннибаевская 20 000, Ново-Елховская 20 009 и Зай-Каратайская 12 930. Изотопное U-Pb датирование 200 зерен циркона было выполнено на масс-спектрометре вторичных ионов Cameca 1280 NORDSIM в Музее естественной истории в Стокгольме. Наилучшие для анализа участки кристаллов циркона были предварительно выбраны по их катодолюминесцентным изображениям. Проведенный анализ продемонстрировал многообразие как возрастных (от 3.8 до 2.6 млрд лет), так и геохимических групп цирконов в метаосадках большечеремшанской серии, что свидетельствует о гетерогенном составе и возрасте питающих провинций в момент их денудации. Наличие эоархейских и палеоархейских цирконов в терригенной составляющей метаосадочного протолита большечеремшанской серии указывает на существование фрагментов древнейшей архейской коры в Волго-Уральском сегменте Восточно-Европейского кратона.

Detrital zircons of the ancient metasedimentary rocks bear important information about the early crust of the Earth. In this work, the early crust in the west of the Ukrainian Shield was studied using U-Pb dating of terrigenous zircons from metasedimentary rocks (quartzites) of the lower parts of the Bug Group (Kosharo-Aleksandrovka Formation) of the Podolia Domain and through Sm-Nd isotopic investigation of these rocks. The Nd model age of rocks is 3.4–3.1 Ga. Detrital zircons were studied in two samples of quartzites. The cathodoluminescent images of most zircons support their clastic origin. More than 150 zircon grains were studied on an ion microprobe. The isotope age of zircons is 3775–2000 Ma. These results were compared with previous results of study of terrigenous zircons from garnet schists of the Zaval’e quarry located closely to the studied area. It is concluded that both Paleoarchean and Meso- to Neoarchean rocks were destroyed during formation of terrigenous rocks of the Bug Group. The different amount of ancient zircons in quartzites and garnet schists indicates the different remoteness of the most ancient rocks from sedimentary basins.

We report zircon for from ophiolitic and high-grade rocks of the Neoproterozoic Baikal-Muya belt of Siberia that occupies an arc-shaped area on the southeastern margin of the Siberian craton. It consists of arc-related plutonic, metavolcanic and metasedimentary rocks as well as fragmented ophiolites and high-grade metamorphic assemblages. Magmatic zircons from two plagiogranite dyke samples of the Mamakan ophiolite complex in the Sredne-Mamakan massif of the eastern Baikal-Muya belt yielded similar and concordant SHRIMP mean Pb-206/U-238 ages of 640.0 +/- 4.1 and 650 +/- 6 Ma, respectively, that reflect the time of dyke emplacement and from which we suggest an age of ca. 645 Ma as the most likely time of ophiolite formation.Enderbitic gneisses of the North Baikal area, in the western part of the Baikal-Muya belt, contain complex zircon populations that reflect variable recrystallization, Pb-loss and metamorphic overgrowth during granulite-facies metamorphism. LA-ICP-MS dating of these zircons yielded inconclusive results that led us to undertake a detailed study of cathodoluminescence images combined with U-Pb SHRIMP dating. Well-preserved magmatic domains in zircons from enderbite sample 2821 yielded concordant results with a mean Pb-206/U-238 age of 640 +/- 5 Ma, slightly higher but broadly comparable with the data obtained by LA-ICP-MS. The zircon populations of two more enderbitic gneiss samples are more complex, and their LA-ICP-MS data constitute broad swaths along concordia between ca. 840 and 600 Ma, reflecting two end-member isotopic components, namely an igneous crystallization event at ca. 800 Ma and a Pb-loss and recrystallization event at ca. 600 Ma. SHRIMP analyses of magmatic zircon domains of these samples yielded concordant data with identical mean Pb-206/U-238 ages of 826 +/- 7.5 Ma and 826 +/- 8 Ma, respectively, whereas low-U metamorphic rims crystallized at 640 +/- 7 Ma. Newly crystallized ball-round metamorphic zircons in one sample produced a mean Pb-206/U-238 age of 640 +/- 6 Ma. We suggest that the protoliths of the enderbitic gneisses crystallized at 826 +/- 7.5 Ma and experienced granulite-metamorphism at 640 +/- 6 Ma. The LA-ICP-MS analyses are fully compatible with this interpretation.Our geochronological data and previously published ages for Neoproterozoic igneous rocks of the BaikalMuya belt define two age groups at 830-780 and 650-640 Ma. We interpret that the older group reflects the evolution of a large arc system in the Baikal-Muya belt and the eastern Sayan-northwestern Mongolia region, whereas the younger group documents collision between the above arc system and the southern margin of the Siberian craton. (c) 2015 Elsevier Ltd. All rights reserved.

We present the results of isotope-geochronological study of metasedimentary rocks of the Bolshecheremshanskaya Formation of the Volgo-Uralian segment of the East European Craton carried out to identify their protoliths. 16 samples of high-alumina gneisses from well cores were studied using the Sm-Nd isotope method and T Nd (DM) model ages. Accessory zircons were selected from rocks with the most ancient model ages (more 3.2 Ga) in three wells: Minnibaevskaya 20000, Novo-Elkhovskaya 20009, and Zai-Karatayskaya 12930 in South Tatarstan. The isotope U-Pb dating of 200 zircon grains was performed on a Cameca 1280 NORDSIM secondary ion mass spectrometer at the Natural History Museum (Stockholm, Sweden). The most applicable sites for analysis of zircon crystals were pre-selected based on cathodoluminescence images. The analytical results demonstrate the diversity of zircon groups in age from 3.8 to 2.6 Ga and together with geochemical features of metasedimentary rocks of the Bolshecheremshanskaya Formation suggest the heterogeneous composition and age of provenance areas under denudation. Occurrence of Eoarchean and Paleoarchean zircons in the clastic material of the protolith of the Bolshecheremshanskaya gneisses indicates the existence of Early Archean crustal terrains in Volgo-Uralia.

В работе приведены новые геологические, геохимические и изотопно-геохимические данные по магматическим породам детально изученного участка западной части Байкало-Муйского пояса – представительного сегмента неопротерозойского обрамления Сибирского кратона. В строении района исследования принимают участие три ассоциации горных пород: гранулит-эндербит-чарнокитовый, ультрамафит-мафитовый комплексы и наиболее поздняя тоналит-плагиогранит-гранитная серия пород, по геохимическим характеристикам отвечающая адакитам. Показано, что комплекс тоналитов и гранитов интрудирует как породы метаморфической ассоциации, так и габброиды мыса Тонкий, Слюдинского и Курлинского массивов. Для тоналитов получены геохронологические данные по цирконам – 595 ± 5 млн лет, указывающие, с учетом геологической информации, что не более чем за несколько десятков миллионов лет после формирования гранулиты были выведены в верхние уровни литосферы. Sm-Nd изотопные данные свидетельствуют о присутствии ювенильного материала в составе серии гранитоидов – Nd(t) 3.2–7.1. Проведен обзор данных по комплексам – индикаторам геодинамических условий, существовавших в неопротерозое в Байкало-Муйском поясе: офиолитам, островодужным сериям, эклогитам и молассовым толщам. Обсуждается роль пространственно связанных гранулитов и ультрамафит-мафитовых интрузий, а также гранитоидов с адакитовыми геохимическими характеристиками, для палеогеодинамических реконструкций западной части Байкало-Муйского пояса во взаимосвязи с другими элементами структуры Центрально-Азиатского пояса, прилегающими к южной части Сибирской платформы.

The paper presents new geological, geochemical, and isotopic data on igneous rocks from a thoroughly studied area in the western Baikal-Muya Belt, which is a representative segment of the Neoproterozoic framework of the Siberian Craton. Three rock associations are distinguished in the studied area: granulite-enderbite-charnockite and ultramafic-mafic complexes followed by the latest tonalite-plagiogranitegranite series corresponding to adakite in geochemical characteristics. Tonalites and granites intrude the metamorphic and gabbroic rocks of the Tonky Mys Point, as well as Slyudyanka and Kurlinka intrusions. The tonalites yielded a U-Pb zircon age of 595 ± 5 Ma. The geochronological and geological information indicate that no later than a few tens of Ma after granulite formation they were transferred to the upper lithosphere level. The Sm-Nd isotopic data show that juvenile material occurs in rocks of granitoid series (ɛ Nd (t) = 3.2–7.1). Ophiolites, island-arc series, eclogites, and molasse sequences have been reviewed as indicators of Neoproterozoic geodynamic settings that existed in the Baikal-Muya Belt. The implications of spatially associated granulites and ultramafic-mafic intrusions, as well as granitoids with adakitic geochemical characteristics for paleogeodynamic reconstructions of the western Baikal-Muya Belt, are discussed together with other structural elements of the Central Asian Belt adjoining the Siberian Platform in the south.

Zircons from the oldest magmatic and metasedimentary rocks of the Podolia domain of the Ukrainian shield were studied and dated by U-Pb method on a NORDSIM secondary-ion mass spectrometer. The age of zircon cores in the enderbite gneisses taken in the Kazachii Yar and Odessa quarries on the opposite banks of the Yuzhnyi Bug River reaches 3790 Ma. Cores of the terrigenous zircons in the quartzites from the Odessa quarry as well as in the garnet gneisses from the Zaval’e graphite quarry have an age within 3650–3750 Ma. Zircon rims record two metamorphic events at 2750–2850 Ma and around 1900–2000 Ma. Extremely low U content in the zircons of the second age group indicates conditions of the granulite-facies metamorphism in the Paleoproterozoic within the Podolia domain. Obtained data on the orthorocks (enderbite-gneiss) and metasedimentary rocks unambiguously suggest the existence of ancient Paleoarchean crust in the Podolia (Dniester-Bug) domain of the Ukrainian shield. They contribute in our knowledge of scales of the formation and geochemical features of the primordial crust.