Studies of the genus Enchodelus Thorne, 1939 (Nematoda, Nordiidae) from Arctic polar deserts. 1. Species with long odontostyle: E. makarovae sp. n. and E. groenlandicus (Ditlevsen, 1927) Thorne, 1939, with an identification key to the species of the E. macrodorus group

Two nematode species of the genus Enchodelus Thorne, 1939, one new and one known from Arctic polar deserts were studied. Enchodelus makarovaesp. n. is an amphimictic species, characterised by females with body length of 1.57-2.00 mm, lip region 15-17.5 μm wide, amphid duplex, odontostyle 38-43 μm long or 2.3-2.8 times lip region diam. Odontophore with flanges, 1.2-1.4 times as long as odontostyle; pharynx length 320-377 μm, pharyngeal expansion 113-130 μm long or 32-37% of total pharynx length; female genital system amphidelphic, uterus tripartite, pars refringens vaginae with two trapezoid sclerotisations, vulva a transverse slit (V=45-51%); tail bluntly conoid (25-35 μm, c=45.8-70.3, c'=0.6-0.9 in females, and 29-33 μm, c=46.4-58.9, c'=0.7-0.8 in males). Males with 65-74 μm long spicules and 10-12 spaced ventromedian supplements. Additional information for Enchodelus groenlandicus is provided, this being a new geographic record for the Putorana Plateau, Russian Arctic.     

Multimodal silica-shelled quantum dots: direct intracellular delivery, photosensitization, toxic, and microcirculation effects

In the present study, we describe a multimodal QD probe with combined fluorescent and paramagnetic properties, based on silica-shelled single QD micelles with incorporated paramagnetic substances [tris(2,2,6,6-tetramethyl-3,5-heptanedionate)/gadolinium] into the micelle and/or silica coat. The probe was characterized with high photoluminescence quantum yield and good positive MRI contrast, low cytotoxicity, and easy intracellular delivery in viable cells. The intravenous administration of the probe in experimental animals did not affect significantly the physiological parameters and microcirculation (e.g., heart rate, blood pressure, diameter and shape of blood vessels), which makes it appropriate for tracing of blood circulation and in vivo multimodal imaging using fluorescent confocal microscopy, two-photon microscopy, and MRI.     

The parameters of grain filling and yield components in common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) and durum wheat (<Emphasis Type="Italic">Triticum turgidum</Emphasis> L. var. <Emphasis Type="Italic">durum</Emphasis>)

Final grain dry weight, a component of yield in wheat, is dependent on the duration and the rate of grain filling. The purpose of the study was to compare the grain filling patterns between common wheat, (Triticum aestivum L.), and durum wheat, (Triticum turgidum L. var. durum), and investigate relationships among grain filling parameters, yield components and the yield itself. The most important variables in differentiating among grain filling curves were final grain dry weight (W) for common wheat genotypes and grain filling rate (R) for durum wheat genotypes; however, in all cases the sets of variables important in differentiating among grain filling curves were extended to either two or all three parameters. Furthermore, in one out of three environmental conditions and for both groups of genotypes, the most important parameter in the set was grain filling duration (T). It indicates significant impact of environmental conditions on dry matter accumulation and the mutual effect of grain filling duration and its rate on the final grain dry weight. The medium early anthesis date could be associated with further grain weight and yield improvements in wheat. Grain filling of earlier genotypes occurs in more temperate environments, which provides enough time for gradual grain fill and avoids the extremes of temperature and the stress of dry conditions.     

Terpenoids from Anthemis austriaca Jacq

The aerial parts of Anthemis austriaca Jacq. afforded five new sesquiterpene lactones (two of which are dimeric guaianolides) and three new guaiane type sesquiterpene acids In addition, seven known terpenoids were also found in the studied species. Their structures were elucidated by spectral methods.     

Enhanced heme oxygenase activity increases the antioxidant defense capacity of guinea pig liver upon acute cobalt chloride loading: comparison with rat liver

Changes in the activity of so-called oxidative stress defensive enzymes, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and heme oxygenase, as well as changes in lipid peroxidation and reduced glutathione levels, were measured in guinea pig and rat liver after acute cobalt loading. Cobalt chloride administration produced a much higher degree of lipid peroxidation in guinea pig than in rat liver compared with the control animals. The intrahepatic reduced glutathione content in control guinea pig was higher than that in rat, but was equally decreased in both species after cobalt administration. The enzymatic scavengers of free radicals, superoxide dismutase, catalase and glutathione peroxidase, were significantly decreased in rat liver after acute cobalt loading, and as a compensatory reaction, the heme oxygenase activity was increased (seven-fold). In guinea pig liver, only superoxide dismutase activity was depleted in response to cobalt-induced oxidative stress, while catalase and glutathione peroxidase were highly activated and the heme oxygenase activity was dramatically increased (13-fold). It is assumed that enhanced heme oxygenase activity may have important antioxidant significance by increasing the liver oxidative-stress defense capacity.     

Bacterial Diversity among the Sediments of Glacial Lakes in the Western Balkans: Exploring the Impact of Human Population

16S rRNA gene-based metagenomic approach was used to assess the biodiversity of bacterial communities in the sediments of selected glacial lakes in the Western Balkans and to assess the impact of human population on these microbial communities. Sediment samples were collected from three glacial lakes, viz., Plav Lake (in a zone of the highest impact of human population), Black Lake (a zone of medium impact of human population), and Donje Bare Lake (a remote lake with minimal impact of human population).

Canonical correlation analysis analysis indicated correlation between the distance of the lake from urbanized population and bacterial diversity in Donje Bare Lake sediment. Bacterial diversity of Black Lake sediment was correlated with high content of phosphorous and pH value. Chemical compounds exhibiting the most prominent correlation with bacterial diversity of Plav Lake were NH₄-N, K₂O, CaCo₃, and total nitrogen . Additionally, CCA analysis indicated that population density was correlated with biodiversity of bacterial communities in Plav Lake sediment, which is the most exposed to human population. Multivariate regression revealed the highest correlation between the presence of Proteobacteria classes and population density and levels of NH₄-N.

The influence of human population was observed to be important for shaping the sediment communities in addition to biological and chemical factors.     

Gramicidin Increases Lipid Flip-Flop in Symmetric and Asymmetric Lipid Vesicles

Unlike most transmembrane proteins, phospholipids can migrate from one leaflet of the membrane to the other. Because this spontaneous lipid translocation (flip-flop) tends to be very slow, cells facilitate the process with enzymes that catalyze the transmembrane movement and thereby regulate the transbilayer lipid distribution. Nonenzymatic membrane-spanning proteins with unrelated primary functions have also been found to accelerate lipid flip-flop in a nonspecific manner and by various hypothesized mechanisms. Using deuterated phospholipids, we examined the acceleration of flip-flop by gramicidin channels, which have well-defined structures and known functions, features that make them ideal candidates for probing the protein-membrane interactions underlying lipid flip-flop. To study compositionally and isotopically asymmetric proteoliposomes containing gramicidin, we expanded a recently developed protocol for the preparation and characterization of lipid-only asymmetric vesicles. Channel incorporation, conformation, and function were examined with small angle x-ray scattering, circular dichroism, and a stopped-flow spectrofluorometric assay, respectively. As a measure of lipid scrambling, we used differential scanning calorimetry to monitor the effect of gramicidin on the melting transition temperatures of the two bilayer leaflets. The two calorimetric peaks of the individual leaflets merged into a single peak over time, suggestive of scrambling, and the effect of the channel on the transbilayer lipid distribution in both symmetric 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and asymmetric 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1,2-dimyristoyl-sn-glycero-3-phosphocholine vesicles was quantified from proton NMR measurements. Our results show that gramicidin increases lipid flip-flop in a complex, concentration-dependent manner. To determine the molecular mechanism of the process, we used molecular dynamics simulations and further computational analysis of the trajectories to estimate the extent of membrane deformation. Together, the experimental and computational approaches were found to constitute an effective means for studying the effects of transmembrane proteins on lipid distribution in both symmetric and asymmetric model membranes.     

Determination of the metabolic index using the fluorescence lifetime of free and bound nicotinamide adenine dinucleotide using the phasor approach

The fluorescence lifetime of nicotinamide adenine dinucleotide (NADH) is commonly used in conjunction with the phasor approach as a molecular biomarker to provide information on cellular metabolism of autofluorescence imaging of cells and tissue. However, in the phasor approach, the bound and free lifetime defining the phasor metabolic trajectory is a subject of debate. The fluorescence lifetime of NADH increases when bound to an enzyme, in contrast to the short multiexponential lifetime displayed by NADH in solution. The extent of fluorescence lifetime increase depends on the enzyme to which NADH is bound. With proper preparation of lactate dehydrogenase (LDH) using oxalic acid (OA) as an allosteric factor, bound NADH to LDH has a lifetime of 3.4 ns and is positioned on the universal semicircle of the phasor plot, inferring a monoexponential lifetime for this species. Surprisingly, measurements in the cellular environments with different metabolic states show a linear trajectory between free NADH at about 0.37 ns and bound NADH at 3.4 ns. These observations support that in a cellular environment, a 3.4 ns value could be used for bound NADH lifetime. The phasor analysis of many cell types shows a linear combination of fractional contributions of free and bound species NADH.     

Assessment of the habitat conditions of a rare and endangered inland saline wetland community with Bolboschoenus maritimus (L.) Palla dominance in Southeastern Europe: the effects of physical–chemical water and soil properties

Wetlands Ecology and Management - Continental inland saline wetlands are among the most endangered habitats in Europe. In the Danube-Tisza-Danube canal network (Serbia, Southeastern Europe), which...