The Preboreal (11.75–10.70 ka BP) is still the least paleogeographically studied time interval in the central part of the East European Plain. High-resolution multi-proxy studies of lacustrine sediments at the Seltso site located in the Desna River floodplain (Dnieper River basin) were conducted. Radiocarbon dating, loss-on-ignition determination, sedimentological and palynological studies and identification of Non-Pollen Palynomorphs in lacustrine sediments allow us to reconstruct changes in vegetation caused by rapid warming at the Younger Dryas–Holocene boundary, short-term climatic fluctuations within the Preboreal and subsequent resumption of warming. Initial Preboreal warming reached its maximum at about 11.5 ka BP when a relatively dry continental climate existed. Between 11.4 and 11.2 ka BP, a short-term cooling corresponding to the Preboreal Oscillation in Greenland occurred, as indicated by a significant reduction of woody vegetation and expansion of open plant communities. In the Late Preboreal, approximately 11.2–10.7 ka BP, warming resumed, which was accompanied by a decrease in the climate continentality. Comparison with high-resolution lithological and palynological data from eight reliably dated sections of the central East European Plain indicates that in northwestern and central Europe, the impact of the Preboreal Oscillation cooling on the vegetation and the lake ecosystems’ development was probably somewhat stronger.

The climatostratigraphic scale of the Upper Middle Pleistocene in the northwest of the East European Plain contains a number of controversial issues, one of which is the position of the Likhvin (Holstein) Interglacial and lesser warm (interstadial) climatic events. To approach this problem, we have studied two sections of Quaternary deposits, Bolshaya Kosha (a well-known and long-studied natural exposure) and Nazarovo (a new, previously unknown section studied in a borehole), in which warm intervals of the Middle Pleistocene are recognized. In both sections, we performed lithological and paleobiological (carpological, spore-pollen) analyses and luminescence dating. In the Bolshaya Kosha section, seeds of the extinct species Caulinia goretskyi were revealed, which allowed us to attribute the obtained IRSL (ca 250–260 ka) dates to the post-Likhvin Bolshaya Kosha interstadial. The sum of data let us propose that both our IRSL and recently published 230Th/U dates (ca 240–290 ka) underestimate the age by 10–15%, and the post-Likhvin Kosha interstadial deposits were formed in the late MIS 9. In the Nazarovo section, palynological study showed the conditions of a relatively warm interstadial, with a change in the composition of vegetation from northern to middle taiga forests. According to IRSL dating, the section was formed in the MIS 10 late glacial between 330–370 ka. The two studied interstadials bracket the Likhvin (Holstein) Interglacial and sedimentary units in the Bolshaya Kosha section are proposed to have formed in MIS 9e.

Quercus (oaks) is a large and important genus of woody angiosperms occurring in a wide range of environments and often occupying a dominant position in temperate forests of the Northern Hemisphere or being a minor component in some subtropical and tropical forests. A reliable determination of fossil dispersed oak pollen requires combined light, scanning electron (SEM) and transmission electron microscopy (TEM) studies and relevant comparative data on extant oak species. We provide SEM and TEM data on 22 extant Quercus spp., representing all sections of the genus. The main objectives of our study were to clarify the nature of the so-called geniculus, a characteristic equatorial bulge in the exine of the colpus found in many oak species, and to test previous hypotheses about the structural basic units of the exine in Quercus. Our ontogenetic study and oxidative experiment involving several Quercus spp. and one Trigonobalanus sp. resulted in a more accurate interpretation of the nature of the geniculus and exine elements, their different developmental states and, therefore, their more reliable application in the systematics and evolution of the genus Quercus and Fagaceae in general.

Abstract. The presented study aims to investigate the paleoenvironmental conditions of Lake Shnitkino in Tver Region (northwestern European Russia). Two sediment cores from the lake bottom were obtained and analyzed using lithological and paleobotanic methods. The Holocene landscape and climatic characteristics of the lake basin are reconstructed. Four stages of lake evolution were inferred: 1) Younger Dryas/Preboreal transition, 2) Boreal, 3) Middle-Late Holocene, and 4) Recent time.

Lake Seliger has been always classified as a former glacial water body, a remnant of a vast proglacial lake, which has existed since the disappearance of the last glacial Ice Sheet in the territory 18–19 thousand years ago. The study was focused on areas of southern pools of the lake looking like underflooded meandering river channels. Bottom sediments were drilled in three such areas and ground penetrating radar profiling was carried out on two areas. Lake silt, several meters thick, was found to overlay coarse sand, which is most likely of riverine origin. A feature in favor of this is a characteristic asymmetrical bed profile in the supposed parts of ancient river bends and the time of transition from active flow to the regime of stagnant water body since 14.5 thousand years ago: in that time, glacier edge already lied far from here, and glacial melt water did not penetrate into this area. The inundation of segments of river valleys and their transformation into lake pools was provoked by damming of the Selizharovka River, which originally flowed out from Lake Seliger near Ostashkov Town. About 14.5 thousand years ago, the rapidly growing delta of the Krapivenka River, a left tributary of the Selizharovka, started growing rapidly, damming the latter river. In the period of 2 thousand years, the damming effect extended over the entire 15-km segment of the valley and reached the source of the river in Lake Seliger. In the Holocene, the level rise continued, though at a lesser rate. The total rise of lake level was 7–8 m, which caused flooding of the lower reaches of the valleys of rivers emptying into the lake and transformed them into estuaries. It is shown that glacioisostatic deformations of the Earth crust could not reverse the flow from Seliger into the Baltic Basin. After the disappearance of the most recent glacier, Lake Seliger and its tributaries have always belonged to the Volga Basin; this is to be taken into account in the reconstruction of the Volga runoff and the water balance of the receiving water body (the Caspian Sea).

Dispersed fossil pollen grains of Fagaceae from the Eocene sediments of the south of Primorskii Region have been analyzed using a scanning electron microscope. Fourteen types of Fagaceae pollen were identified: one of them represented the extinct genusEotrigonobalanus,four were assigned to the subfamily Castaneoideae, two to the genusFagus,and seven to the genusQuercus;four of the latter were produced by deciduous oaks (Quercus), one, by evergreen oaks (Cyclobalanoides), and two, by evergreen sclerophyllous oaks (Heterobalanus). The presence of pollen of the extinct genusEotrigonobalanusin the study region was demonstrated for the first time. The data obtained are indicative of considerable diversity of the family Fagaceae in the Eocene of Primorskii Region.

Pollen sculpture elements of four Rhododendron species from 49 populations were studied using scanning electron microscopy. The sculpture in the polar areas of the studied taxa pollen differed in type, shape, size, and distribution of individual elements. There were five sculpture types identified. The pollen of Rhododendron ledebourii from various populations in Altai revealed sculpture elements characteristic of R. dauricum, R. mucronulatum, and R. sichotense, questioning the taxonomic position of the former species. Analysis of the geographical distribution of sculpture types clarified species boundaries and zones of sympatric distribution. The northern boundary of R. mucronulatum was expanded and new populations of R. sichotense were revealed. In the sympatric zones of R. mucronulatum and R. sichotense, there were intermediate populations showing pollen sculptures typical of R. dauricum, R. mucronulatum, and R. sichotense. The sculpture diversity observed in the pollen of R. dauricum, together with its presence in sympatric zones, suggests that it is probably a hybrid of R. sichotense and R. mucronulatum or a subspecies of R. sichotense.

Fossil pollen grains of Castaneoideae from Holocene sediments from the southern Sea of Japan (J-3) at a depth of 200–202, 165–167, and 120–122 cm were studied with a scanning electron microscope. Pollen of some extant species of Castaneoideae, native to the region ( Castanopsis cuspidata , C. sclerophylla , and Lithocarpus glaber ) were also studied. As a result, four types of fossil pollen grains were revealed; type I is identified to species as Castanopsis cuspidata , type II is referred to the genus Castanopsis , type III is assigned to the genus Lithocarpus , and type IV is only identifined to subfamily (Castaneoideae type).

The size of Rhododendron sichotense seeds and exotesta cells from 20 populations were studied using a scanning electron microscope (SEM). The results of a correlation analysis showed that seed size depends on bioclimatic factors. As a species marker, we used the exotesta cell elongation coefficient. This characteristic was unresponsive to environmental variables, demonstrating its taxonomic significance. In the centre of the species range, the samples had an exotesta cell elongation coefficient that was typical for the species, but in samples from the far northern and southern parts of the range, where the distribution of R. sichotense meets that of of R. dauricum L. and R. mucronulatum Turcz., respectively, the value of the exotesta cell elongation coefficient was intermediate between these species. Therefore, the exotesta cell elongation coefficient can be recommended for use in the detection of hybridisation areas.

The cDNA fragment encoding the catalytic domain of the new silicatein-like cathepsin enzyme LoCath was expressed in a strain Top10 of Escherichia coli, extracted and purified via nickel-affinity chromatography. Recombinant enzyme performed silica-polymerizing activity when mixed with water-soluble silica precursor-tetrakis-(2-hydroxyethyl)-orthosilicate. Scanning electron microscopy revealed hexagonal, octahedral and β-tridimit crystals. Energy dispersion fluorescence X-ray spectrometry analysis showed that all these crystals consist of pure silicon oxide. It is the first report about the ability of marine sponge's cathepsin to polymerize silicon, as well as about the structure and composition of the silicon oxide crystal formed by recombinant cathepsin. Further study of the catalytic activity of silicatein and cathepsin will help to understand the biosilification processes in vivo, and will create basis for biotechnological use of recombinant proteins for silicon polymerization.

Holocene dispersed pollen from two cores from the shelf zone of the Korean Bay and from the deep water zone of the south of the Sea of Japan were studied by means of light and electron (scanning and transmission) microscopy. Three sculpture types were observed: rod-like, rugulate-granulate and (micro)verrucate. Ten conventional groups were separated according to the sporoderm morphology and ultrastructure. Possible specific attribution was suggested based on the comparison with published data on modern and fossil oak pollen. The perspective of further application of electron microscopy for this taxon is discussed.

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Методом сканирующей электронной микроскопии (СЭМ) проведено сравнительное исследование морфологии пыльцы и семян 3 видов рода Rhododendron L. подсекции Rhodorastrum (Maxim.) Cullen: Rh. dauricum L., Rh. mucronolatum Turcz., Rh. sichotense Pojark. Результаты дискриминантного анализа морфометрических признаков пыльцы и семян доказали обособленность видов Rh. sichotense, Rh. dauricum и Rh. mucronulatum. На уровне пыльцы виды различаются по типу скульптуры (гранулярная, морщинистая, мелкоморщинистая) в области апокольпиума, мезокольпиума, апертур, и по диаметру тетрады. Для семян исследованных видов выделен таксономически значимый морфометрический признак – коэффициент вытянутости клеток экзотесты.