Beschreibung: This data was collected as part of the Polarstern PS113 expedition to obtain insights into primary productivity on a latitudinal transect in the Atlantic Ocean. In-situ experiments of stable isotope (13C) uptake were conducted on board in triplicates of 1L pre-acid washed polycarbonate bottles. In detail, samples were spiked with Na13CO3 at a final 13C concentration of 200 µmol L-1. Experiments were terminated after 24h incubation and filter on a 0.7 precombusted polycarbonate filter. Samples were snap fronzen and stored at -80°C while at sea. Prior analysis, samples were acid fumed and dried. Samples were analysed on a PDZ Europa ANCA-GSL elemental analyzer interfaced to a PDZ Europa 20-20 isotope ratio mass spectrometer (Sercon Ltd., Cheshire, UK) by the Isotopic Laboratory at the UC Davis, California campus. This data reflects high-resolution spatial variations in primary productivity.

Beschreibung: This data set was collected in support of an investigation of the variability of particulate organic matter content and composition across a high-resoultion latitudinal transect across the Atlantic Ocean during the PS113 expedition. 4L of seawater from the clean ships' underway system were filtered on a 0.7 µm pre-combusted GFF filter. Samples were snap-frozen and stored at -80°C while at sea. Samples were acid fumed and dried before analyses. Particulate organic carbon and particulate nitrogen contents were measured using an Euro EA elemental analyzer (CHNS; EuroVector, Italy). This data reflects high-resolution spatial variabilites in particulate organic carbon and particulate nitrogen concentrations in surface waters accompanied by few samples from higher depths (0 - 400 m).

Beschreibung: This data was collected to investigate spatial differences in dissolved inorganic nutrient concentrations in surface waters of the Atlantic Ocean as part of the PS113 expedition. Water samples for dissolved inorganic nutrient concentrations including Nitrate, Silicate and Phosphate were filtered through a 0.2 µm syringe filter and stored at -80°C while at sea. Nutrient concentrations were assayed on an Evolution 3 Alliance Autoanalyser and calibrations were corrected for concentrations using certified reference material (CRM) 7602a (JAMSTEC; JAPAN) and MERCK STD (NIST-Standard). Concentrations were calculated by means of standard colorimetric techniques (Grasshoff, Kremling, & Ehrhardt, 2009).

Beschreibung: Marine microbial plankton drive global biogeochemical cycles and are therefore pivotal to the ecosystem functioning of the biosphere. In particular marine picoplankton harbour a vast biodiversity on which their community dynamics and functioning are based. Because they function collectively as a community, it is crucial to understand the underlying diversity patterns of microbial assemblages and identify their drivers. The data set I investigated here allows insights into surface water bacterio- and picoplankton communities of Arctic and subarctic coastal waters and fjord systems. To infer their diversity with a metabarcoding approach, I amplified and sequenced the V4 regions of the prokaryotic 16S and eukaryotic 18S ribosomal DNA which serve as molecular markers. The resulting amplicons were arranged into amplicon sequence variants (ASVs) which I used as a substitute for species. In comparing prokaryotic and picoeukaryotic alpha and beta diversity across space, I unveiled profound differences between the domains, the investigated regions and the respective drivers. Picoeukaryotes appeared to vastly exceed prokaryotes in their richness and are thus hypothesized to comprise a large rare biosphere ensuring community stability. They are more strongly influenced by fjord structures and glaciers than prokaryotes and I found spring bloom conditions to induce a drastic decrease in picoeukaryotic richness. Prokaryotes appeared to be more strongly influenced by nutrient availability and environmental conditions than picoeukaryotes, resulting in a higher spatial turnover through more efficient taxa sorting. I found no distance-decay relationship in prokaryotic and picoeukaryotic communities on the scales observed here. I assume a functional coupling and mutual dependence of the prokaryotic and eukaryotic communities based on co-varying alpha diversity measures, which were fundamentally restructured by spring bloom conditions. I observed a pronounced compositional turnover in both space and time. Seasonal succession and change across years appeared to shape picoplankton communities equally strong as spatially differing influences, stressing the need to control for time in future spatial analyses. In contributing to a better understanding of the basic patterns and their drivers underlying picoplankton diversity, this study may also contribute to a better understanding of the impact climate change will have on the planet. Spatial dynamics across environmentally differing sites can deliver indications to the influence of environmental changes in time. Thus, they allow to anticipate changes in microbial plankton dynamics and therefore the functioning of the global biosphere in the face of climate change.

Beschreibung: Climate change is opening the Arctic Ocean to increasing human impact and ecosystem changes. Arctic fjords, the region’s most productive ecosystems, are sustained by a diverse microbial community at the base of the food web. Here we show that Arctic fjords become more prokaryotic in the picoplankton (0.2–3 µm) with increasing water temperatures. Across 21 fjords, we found that Arctic fjords had proportionally more trophically diverse (autotrophic, mixotrophic, and heterotrophic) picoeukaryotes, while subarctic and temperate fjords had relatively more diverse prokaryotic trophic groups. Modeled oceanographic connectivity between fjords suggested that transport alone would create a smooth gradient in beta diversity largely following the North Atlantic Current and East Greenland Current. Deviations from this suggested that picoeukaryotes had some strong regional patterns in beta diversity that reduced the effect of oceanographic connectivity, while prokaryotes were mainly stopped in their dispersal if strong temperature differences between sites were present. Fjords located in high Arctic regions also generally had very low prokaryotic alpha diversity. Ultimately, warming of Arctic fjords could induce a fundamental shift from more trophic diverse eukaryotic- to prokaryotic-dominated communities, with profound implications for Arctic ecosystem dynamics including their productivity patterns.

Beschreibung: Diabetes is associated with long-term complications in the brain and reduced cognitive ability. Vitamin D 3 (VD 3 ) appears to be involved in the amelioration of hyperglycaemia in streptozotocin (STZ)-induced diabetic rats. Our aim was to analyse the potential of VD 3 in avoiding brain damage through evaluation of acetylcholinesterase (AChE), Na + K + -adenosine triphosphatase (ATPase) and delta aminolevulinate dehydratase ( δ -ALA-D) activities and thiobarbituric acid reactive substance (TBARS) levels from cerebral cortex, as well as memory in STZ-induced diabetic rats. Animals were divided into eight groups ( n  = 5): control/saline, control/metformin (Metf), control/VD 3 , control/Metf + VD 3 , diabetic/saline, diabetic/Metf, diabetic/VD 3 and diabetic/Metf + VD 3 . Thirty days after treatment, animals were submitted to contextual fear-conditioning and open-field behavioural tests, after which they were sacrificed and the cerebral cortex was dissected. Our results demonstrate a significant memory deficit, an increase in AChE activity and TBARS levels and a decrease in δ -ALA-D and Na + K + -ATPase activities in diabetic rats when compared with the controls. Treatment of diabetic rats with Metf and VD 3 prevented the increase in AChE activity when compared with the diabetic/saline group. In treated diabetic rats, the decrease in Na + K + -ATPase was reverted when compared with non-treated rats, but the increase in δ -ALA-D activity was not. VD 3 prevented diabetes-induced TBARS level and improved memory. Our results show that VD 3 can avoid cognitive deficit through prevention of changes in important enzymes such as Na + K + -ATPase and AChE in cerebral cortex in type 1 diabetic rats. Copyright © 2014 John Wiley & Sons, Ltd.

Beschreibung: Climate change is opening the Arctic Ocean to increasing human impact and ecosystem changes. Arctic fjords, the region’s most productive ecosystems, are sustained by a diverse microbial community at the base of the food web. Here we show that Arctic fjords become more prokaryotic in the picoplankton (0.2–3 µm) with increasing water temperatures. Across 21 fjords, we found that Arctic fjords had proportionally more trophically diverse (autotrophic, mixotrophic, and heterotrophic) picoeukaryotes, while subarctic and temperate fjords had relatively more diverse prokaryotic trophic groups. Modeled oceanographic connectivity between fjords suggested that transport alone would create a smooth gradient in beta diversity largely following the North Atlantic Current and East Greenland Current. Deviations from this suggested that picoeukaryotes had some strong regional patterns in beta diversity that reduced the effect of oceanographic connectivity, while prokaryotes were mainly stopped in their dispersal if strong temperature differences between sites were present. Fjords located in high Arctic regions also generally had very low prokaryotic alpha diversity. Ultimately, warming of Arctic fjords could induce a fundamental shift from more trophic diverse eukaryotic- to prokaryotic-dominated communities, with profound implications for Arctic ecosystem dynamics including their productivity patterns.