Observation of polar bear (Ursus maritimus) feeding on Svalbard reindeer (Rangifer tarandus platyrhyncus) – exceptional behaviour or upcoming trend?

A polar bear (Ursus maritimus) was observed feeding on Svalbard reindeer (Rangifer tarandus platyrhyncus) on September 3rd 2018 near Skansbukta, central Svalbard. A well-developed male was observed to rest nearby and feed on fresh reindeer carcass. Polar bear hunting a reindeer is rather an exceptional behaviour at present, but could become more frequent with drastic decline of sea ice and thus loss of traditional hunting areas with presence of seals – the usual prey

Water temperature regime of selected lakes on James Ross Island during 2015 austral summer

Five lakes on the northernmost tip of James Ross Island (JRI), Ulu Peninsula, were selected to study their water temperature regime and relationship to atmospheric factors. Different genetic types of lakes were selected to cover not only influence of atmospheric parameters but also the morphology of lakes. Water temperature of all lakes showed strong similarities in the reaction to atmospheric factors no matter its genetic type or morphological properties, which were only second order factors shaping the general trends into more individual temporal patterns. All lakes are characterised by strong diurnal regime with maximum temperatures in late afternoon and minimum early morning. Most stable conditions were found in Monolith Lake and Triangular Lake, the first one with the biggest volume and regular inflow and outflow of water, the second one with semi-permanent ice cover protecting the water column from larger fluctuations caused by atmospheric factors. The most unstable environment was found in Shallow Lake, small shallow temporary lake with variable water level. Spatio-temporal issues of temperature relationships between water body and the terrestrial environment were shown with IR camera timelapse shooting on the example of Shallow Lake

Snow and glacier melt contributions to streamflow on James Ross Island, Antarctic Peninsula

The Antarctic Peninsula is experiencing a rapid increase in air temperature, which has a major impact on the entire ecosystem, including the runoff process. Although water availability plays an important role in polar ecosystems, runoff generation in the Antarctic Peninsula region is still poorly understood. We analysed the variability in rain, snow and glacier contributions to runoff in relation to climate variability in a small, partly glaciated catchment on James Ross Island in the north-eastern Antarctic Peninsula. We used the hydrological model HBV to simulate the runoff process for the period 2010/11–2020/21 at a daily resolution. The model was calibrated against both measured discharge and glacier mass balance. Model simulations showed the negative mass balance of Triangular Glacier for 9 out of 11 study years with an average annual mass loss of 49 mm water equivalent. About 92 % of the annual runoff occurred between October and May. On average, peak runoff occurred in the second half of the summer season due to the combination of strong glacier and snow melt. The majority (76 %) of runoff originated from snowmelt, 14 % originated from glacier melt and 10 % from rainfall. The contribution of snowmelt to total runoff was higher in colder years with more precipitation. In contrast, glacier melt contributed dominantly during warmer years with less precipitation. Our simulation showed the presence of significant runoff-generating events outside the usual high summer runoff measurement season

Diatoms in cryoconite holes and adjacent proglacial freshwater sediments, Nordenskiöld glacier (Spitsbergen, High Arctic)

Cryoconite holes are small, extreme habitats, widespread in the ablation zones of gla-ciers worldwide. They can provide a suitable environment for microorganisms including bacteria, cyanobacteria, algae, fungi, and invertebrates. Diatoms have been previously recovered from cryoconite holes of Greenland and of Svalbard, and recent findings from Antarctica suggest that cryoconite holes may harbor a unique diatom flora distinct from other aquatic habitats nearby. In the present study, we characterize the diatom communi-ties of Nordenskiöld glacier cryoconite holes in Billefjorden (Svalbard, Spitsbergen), and multivariate approaches were used to compare them with three freshwater localities in the immediate vicinity to investigate possible sources of the species pool. We found cryoconite holes to have similar or greater average genus-richness than adjacent lake/ ponds habitats, even though lower numbers of valves were recovered. Overall, cryoconite hole diatom communities differed significantly from those observed in lakes, suggesting that other sources actively contribute to these communities than nearby lakes alone. This further suggests that (i) diatoms present in cryoconite might not exclusively originate from aquatic habitats, but also from (semi-) terrestrial ones; and (ii) that a much wider area than the immediate surroundings should be considered as a possible source for cryoconite diatom flora

Inverted Solution Processable OLEDs Using a Metal Oxide as an Electron Injection Contact

A new type of bottom-emission electroluminescent device is described in which a metal oxide is used as the electron-injecting contact. The preparation of such a device is simple. It consists of the deposition of a thin layer of a metal oxide on top of an indium tin oxide covered glass substrate, followed by the solution processing of the light-emitting layer and subsequently the deposition of a high-workfunction (air-stable) metal anode. This architecture allows for a low-cost electroluminescent device because no rigorous encapsulation is required. Electroluminescence with a high brightness reaching 5700 cd m–2 is observed at voltages as low as 8 V, demonstrating the potential of this new approach to organic light-emitting diode (OLED) devices. Unfortunately the device efficiency is rather low because of the high current density flowing through the device. We show that the device only operates after the insertion of an additional hole-injection layer in between the light-emitting polymer (LEP) and the metal anode. A simple model that explains the experimental results and provides avenues for further optimization of these devices is described. It is based on the idea that the barrier for electron injection is lowered by the formation of a space–charge field over the metal-oxide–LEP interface due to the build up of holes in the LEP layer close to this interfac

Observation of the Emperor penguins Aptenodytes forsteri in the Prince Gustav Channel related with unusual sea-ice decline in north-western Weddell Sea

A pair of juvenile emperor penguins (Aptenodytes forsteri) was observed in the northern coast of James Ross Island, the north-western sector of the Weddell Sea, Antarctica, in January 2017. The penguins originated from the colony located on Snow Hill Island, 120-130 km far from the observation area. Despite the emperor penguin´s ability to migrate over long distances, when they are well-known from different areas in Antarctica, this was the first observation of this species in the north of James Ross Island. In this short paper we discuss the environmental factors which allowed the penguins to reach James Ross Island northern coast, especially significant sea ice variability in this area during last decade

Heterologous expression, purification and characterization of nitrilase from Aspergillus niger K10

<p>Abstract</p> <p>Background</p> <p>Nitrilases attract increasing attention due to their utility in the mild hydrolysis of nitriles. According to activity and gene screening, filamentous fungi are a rich source of nitrilases distinct in evolution from their widely examined bacterial counterparts. However, fungal nitrilases have been less explored than the bacterial ones. Nitrilases are typically heterogeneous in their quaternary structures, forming short spirals and extended filaments, these features making their structural studies difficult.</p> <p>Results</p> <p>A nitrilase gene was amplified by PCR from the cDNA library of <it>Aspergillus niger </it>K10. The PCR product was ligated into expression vectors pET-30(+) and pRSET B to construct plasmids pOK101 and pOK102, respectively. The recombinant nitrilase (Nit-ANigRec) expressed in <it>Escherichia coli </it>BL21-Gold(DE3)(pOK101/pTf16) was purified with an about 2-fold increase in specific activity and 35% yield. The apparent subunit size was 42.7 kDa, which is approx. 4 kDa higher than that of the enzyme isolated from the native organism (Nit-ANigWT), indicating post-translational cleavage in the enzyme's native environment. Mass spectrometry analysis showed that a C-terminal peptide (Val₃₂₇- Asn₃₅₆) was present in Nit-ANigRec but missing in Nit-ANigWT and Asp₂₉₈-Val₃₁₃peptide was shortened to Asp₂₉₈-Arg₃₁₀in Nit-ANigWT. The latter enzyme was thus truncated by 46 amino acids. Enzymes Nit-ANigRec and Nit-ANigWT differed in substrate specificity, acid/amide ratio, reaction optima and stability. Refolded recombinant enzyme stored for one month at 4°C was fractionated by gel filtration, and fractions were examined by electron microscopy. The late fractions were further analyzed by analytical centrifugation and dynamic light scattering, and shown to consist of a rather homogeneous protein species composed of 12-16 subunits. This hypothesis was consistent with electron microscopy and our modelling of the multimeric nitrilase, which supports an arrangement of dimers into helical segments as a plausible structural solution.</p> <p>Conclusions</p> <p>The nitrilase from <it>Aspergillus niger </it>K10 is highly homologous (≥86%) with proteins deduced from gene sequencing in <it>Aspergillus </it>and <it>Penicillium </it>genera. As the first of these proteins, it was shown to exhibit nitrilase activity towards organic nitriles. The comparison of the Nit-ANigRec and Nit-ANigWT suggested that the catalytic properties of nitrilases may be changed due to missing posttranslational cleavage of the former enzyme. Nit-ANigRec exhibits a lower tendency to form filaments and, moreover, the sample homogeneity can be further improved by <it>in vitro </it>protein refolding. The homogeneous protein species consisting of short spirals is expected to be more suitable for structural studies.</p