TY - JOUR A1 - Giling, Darren P. A1 - Nejstgaard, Jens C. A1 - Berger, Stella A. A1 - Grossart, Hans-Peter A1 - Kirillin, Georgiy A1 - Penske, Armin A1 - Lentz, Maren A1 - Casper, Peter A1 - Sareyka, Joerg A1 - Gessner, Mark O. T1 - Thermocline deepening boosts ecosystem metabolism: evidence from a large-scale lake enclosure experiment simulating a summer storm JF - Global change biology N2 - Extreme weather events can pervasively influence ecosystems. Observations in lakes indicate that severe storms in particular can have pronounced ecosystem-scale consequences, but the underlying mechanisms have not been rigorously assessed in experiments. One major effect of storms on lakes is the redistribution of mineral resources and plankton communities as a result of abrupt thermocline deepening. We aimed at elucidating the importance of this effect by mimicking in replicated large enclosures (each 9 m in diameter, ca. 20 m deep, ca. 1300 m 3 in volume) a mixing event caused by a severe natural storm that was previously observed in a deep clear-water lake. Metabolic rates were derived from diel changes in vertical profiles of dissolved oxygen concentrations using a Bayesian modelling approach, based on high-frequency measurements. Experimental thermocline deepening stimulated daily gross primary production (GPP) in surface waters by an average of 63% for > 4 weeks even though thermal stratification re-established within 5 days. Ecosystem respiration (ER) was tightly coupled to GPP, exceeding that in control enclosures by 53% over the same period. As GPP responded more strongly than ER, net ecosystem productivity (NEP) of the entire water column was also increased. These protracted increases in ecosystem metabolism and autotrophy were driven by a proliferation of inedible filamentous cyanobacteria released from light and nutrient limitation after they were entrained from below the thermocline into the surface water. Thus, thermocline deepening by a single severe storm can induce prolonged responses of lake ecosystem metabolism independent of other storm-induced effects, such as inputs of terrestrial materials by increased catchment run-off. This highlights that future shifts in frequency, severity or timing of storms are an important component of climate change, whose impacts on lake thermal structure will superimpose upon climate trends to influence algal dynamics and organic matter cycling in clear-water lakes. Keywords: climate variability, ecosystem productivity, extreme events, gross primary production, mesocosm, respiration stratified lakes KW - climate variability KW - ecosystem productivity KW - extreme events KW - gross primary production KW - mesocosm KW - respiration stratified lakes Y1 - 2017 U6 - https://doi.org/10.1111/gcb.13512 SN - 1354-1013 SN - 1365-2486 VL - 23 SP - 1448 EP - 1462 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Perkins, Anita K. A1 - Ganzert, Lars A1 - Rojas-Jimenez, Keilor A1 - Fonvielle, Jeremy Andre A1 - Hose, Grant C. A1 - Grossart, Hans-Peter T1 - Highly diverse fungal communities in carbon-rich aquifers of two contrasting lakes in Northeast Germany JF - Fungal ecology N2 - Fungi are an important component of microbial communities and are well known for their ability to decompose refractory, highly polymeric organic matter. In soils and aquatic systems, fungi play an important role in carbon processing, however, their diversity, community structure and function as well as ecological role, particularly in groundwater, are poorly studied. The aim of this study was to examine the fungal community composition, diversity and function in groundwater from 16 boreholes located in the vicinity of two lakes in NE Germany that are characterized by contrasting trophic status. The analysis of 28S rRNA gene sequences amplified from the groundwater revealed high fungal diversity arid clear differences in community structure between the aquifers. Most sequences were assigned to Ascomycota and Basidiomycota, but members of Chytridiomycota, Cryptomycota, Zygomycota, Blastocladiomycota, Glomeromycota and Neocallimastigomycota were also detected. In addition, 27 species of fungi were successfully isolated from the groundwater samples and tested for their ability to decompose complex organic polymers - the predominant carbon source in the groundwater. Most isolates showed positive activities for at least one of the tested polymer types, with three strains, belonging to the genera Gibberella, Isaria and Cadophora, able to decompose all tested substrates. Our results highlight the high diversity of fungi in groundwater, and point to their important ecological role in breaking down highly polymeric organic matter in these isolated microbial habitats. (C) 2019 Elsevier Ltd and British Mycological Society. All rights reserved. KW - Groundwater KW - Aquatic fungi KW - DOC KW - CDOM KW - Aquifers KW - Humic acids Y1 - 2019 U6 - https://doi.org/10.1016/j.funeco.2019.04.004 SN - 1754-5048 SN - 1878-0083 VL - 41 SP - 116 EP - 125 PB - Elsevier CY - Oxford ER - TY - GEN A1 - Cuadrat, Rafael R. C. A1 - Ionescu, Danny A1 - Dávila, Alberto M. R. A1 - Grossart, Hans-Peter T1 - Recovering genomics clusters of secondary metabolites from lakes using genome-resolved metagenomics T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Metagenomic approaches became increasingly popular in the past decades due to decreasing costs of DNA sequencing and bioinformatics development. So far, however, the recovery of long genes coding for secondary metabolites still represents a big challenge. Often, the quality of metagenome assemblies is poor, especially in environments with a high microbial diversity where sequence coverage is low and complexity of natural communities high. Recently, new and improved algorithms for binning environmental reads and contigs have been developed to overcome such limitations. Some of these algorithms use a similarity detection approach to classify the obtained reads into taxonomical units and to assemble draft genomes. This approach, however, is quite limited since it can classify exclusively sequences similar to those available (and well classified) in the databases. In this work, we used draft genomes from Lake Stechlin, north-eastern Germany, recovered by MetaBat, an efficient binning tool that integrates empirical probabilistic distances of genome abundance, and tetranucleotide frequency for accurate metagenome binning. These genomes were screened for secondary metabolism genes, such as polyketide synthases (PKS) and non-ribosomal peptide synthases (NRPS), using the Anti-SMASH and NAPDOS workflows. With this approach we were able to identify 243 secondary metabolite clusters from 121 genomes recovered from our lake samples. A total of 18 NRPS, 19 PKS, and 3 hybrid PKS/NRPS clusters were found. In addition, it was possible to predict the partial structure of several secondary metabolite clusters allowing for taxonomical classifications and phylogenetic inferences. Our approach revealed a high potential to recover and study secondary metabolites genes from any aquatic ecosystem. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 924 KW - metagenomics 2.0 KW - PKS KW - NRPS KW - freshwater KW - environmental genomics Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-445656 SN - 1866-8372 IS - 924 ER - TY - GEN A1 - Göritz, Anna A1 - Berger, Stella A. A1 - Gege, Peter A1 - Grossart, Hans-Peter A1 - Nejstgaard, Jens C. A1 - Riedel, Sebastian A1 - Röttgers, Rüdiger A1 - Utschig, Christian T1 - Retrieval of water constituents from hyperspectral in-situ measurements under variable cloud cover BT - a case study at lake Stechlin (Germany) T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Remote sensing and field spectroscopy of natural waters is typically performed under clear skies, low wind speeds and low solar zenith angles. Such measurements can also be made, in principle, under clouds and mixed skies using airborne or in-situ measurements; however, variable illumination conditions pose a challenge to data analysis. In the present case study, we evaluated the inversion of hyperspectral in-situ measurements for water constituent retrieval acquired under variable cloud cover. First, we studied the retrieval of Chlorophyll-a (Chl-a) concentration and colored dissolved organic matter (CDOM) absorption from in-water irradiance measurements. Then, we evaluated the errors in the retrievals of the concentration of total suspended matter (TSM), Chl-a and the absorption coefficient of CDOM from above-water reflectance measurements due to highly variable reflections at the water surface. In order to approximate cloud reflections, we extended a recent three-component surface reflectance model for cloudless atmospheres by a constant offset and compared different surface reflectance correction procedures. Our findings suggest that in-water irradiance measurements may be used for the analysis of absorbing compounds even under highly variable weather conditions. The extended surface reflectance model proved to contribute to the analysis of above-water reflectance measurements with respect to Chl-a and TSM. Results indicate the potential of this approach for all-weather monitoring. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 941 KW - remote sensing KW - inland water KW - hyperspectral measurements KW - in-situ KW - cloud KW - surface reflection KW - inversion KW - bio-optical modeling Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-459837 SN - 1866-8372 IS - 941 ER - TY - JOUR A1 - Lundgreen, Regitze B. C. A1 - Jaspers, Cornelia A1 - Traving, Sachia J. A1 - Ayala, Daniel J. A1 - Lombard, Fabien A1 - Grossart, Hans-Peter A1 - Nielsen, Torkel G. A1 - Munk, Peter A1 - Riemann, Lasse T1 - Eukaryotic and cyanobacterial communities associated with marine snow particles in the oligotrophic Sargasso Sea JF - Scientific reports N2 - Marine snow aggregates represent heterogeneous agglomerates of dead and living organic matter. Composition is decisive for their sinking rates, and thereby for carbon flux to the deep sea. For oligotrophic oceans, information on aggregate composition is particularly sparse. To address this, the taxonomic composition of aggregates collected from the subtropical and oligotrophic Sargasso Sea (Atlantic Ocean) was characterized by 16S and 18S rRNA gene sequencing. Taxonomy assignment was aided by a collection of the contemporary plankton community consisting of 75 morphologically and genetically identified plankton specimens. The diverse rRNA gene reads of marine snow aggregates, not considering Trichodesmium puffs, were dominated by copepods (52%), cnidarians (21%), radiolarians (11%), and alveolates (8%), with sporadic contributions by cyanobacteria, suggesting a different aggregate composition than in eutrophic regions. Composition linked significantly with sampling location but not to any measured environmental parameters or plankton biomass composition. Nevertheless, indicator and network analyses identified key roles of a few rare taxa. This points to complex regulation of aggregate composition, conceivably affected by the environment and plankton characteristics. The extent to which this has implications for particle densities, and consequently for sinking rates and carbon sequestration in oligotrophic waters, needs further interrogation. Y1 - 2019 U6 - https://doi.org/10.1038/s41598-019-45146-7 SN - 2045-2322 VL - 9 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Kühne, Franziska A1 - Fauth, Henriette A1 - Destina Sevde, Ay-Bryson A1 - Visser, Leonie N.C. A1 - Weck, Florian T1 - Communicating the diagnosis of cancer or depression: Results of a randomized controlled online study using video vignettes JF - Cancer Medicine N2 - Background Communicating a diagnosis is highly important, yet complex, especially in the context of cancer and mental disorders. The aim was to explore the communication style of an oncologist vs. psychotherapist in an online study. Methods Patients (N = 136: 65 cancer, 71 depression) were randomly assigned to watch a standardized video vignette with one of two communication styles (empathic vs. unempathic). Outcome measures of affectivity, information recall, communication skills, empathy and trust were applied. Results Regardless of diagnosis, empathic communication was associated with the perception of a significantly more empathic (p < 0.001, η2partial = 0.08) and trustworthy practitioner (p = 0.014, η2partial = 0.04) with better communication skills (p = 0.013, η2partial = 0.05). Cancer patients reported a larger decrease in positive affect (p < 0.001, η2partial = 0.15) and a larger increase in negative affect (p < 0.001, η2partial = 0.14) from pre- to post-video than depressive patients. Highly relevant information was recalled better in both groups (p < 0.001, d = 0.61–1.06). Conclusions The results highlight the importance of empathy while communicating both a diagnosis of cancer and a mental disorder. Further research should focus on the communication of a mental disorder in association with cancer. KW - consultation KW - mental health KW - oncology KW - psycho-oncology KW - skills Y1 - 2021 U6 - https://doi.org/10.1002/cam4.4396 SN - 2045-7634 VL - 10 SP - 9012 EP - 9021 PB - Wiley CY - Hoboken, New Jersey, USA ET - 24 ER - TY - JOUR A1 - Abdalla, Hassan E. A1 - Adam, Remi A1 - Aharonian, Felix A. A1 - Benkhali, Faical Ait A1 - Angüner, Ekrem Oǧuzhan A1 - Arakawa, Masanori A1 - Arcaro, C A1 - Armand, Catherine A1 - Armstrong, T. A1 - Egberts, Kathrin T1 - Very high energy γ-ray emission from two blazars of unknown redshift and upper limits on their distance JF - Monthly Notices of the Royal Astronomical Society N2 - We report on the detection of very high energy (VHE; E > 100 GeV) gamma-ray emission from the BL Lac objects KUV 00311-1938 and PKS 1440-389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or preceded by multiwavelength observations with Fermi/LAT, XRT and UVOT onboard the Swift satellite, and ATOM. Based on an extrapolation of the Fermi/LAT spectrum towards the VHE gamma-ray regime, we deduce a 95 per cent confidence level upper limit on the unknown redshift of KUV 00311-1938 of z < 0.98 and of PKS 1440-389 of z < 0.53. When combined with previous spectroscopy results, the redshift of KUV 00311-1938 is constrained to 0.51 <= z < 0.98 and of PKS 1440-389 to 0.14 (sic) z < 0.53. KW - BL Lacertae objects: individual KW - galaxies: high-redshift KW - gamma-rays: general KW - Resolved and unresolved sources as a function of wavelength Y1 - 2020 VL - 494 IS - 4 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Raynaud, F A1 - Jond-Necand, C A1 - Marcilhac, Anne A1 - Fürst, Dieter Oswald A1 - Benyamin, Yves T1 - Calpain 1-gamma filamin interaction in muscle cells : a possible in situ regulation by PKC-alpha Y1 - 2006 ER - TY - JOUR A1 - Raynaud, F A1 - Jond-Necand, C A1 - Marcilhac, Anne A1 - Fürst, Dieter Oswald A1 - Benyamin, Yves T1 - Calpain 1-gamma filamin interaction in muscle cells :a possible in situ regulation by PKC-alpha Y1 - 2006 ER - TY - JOUR A1 - Yoon, S.-C. A1 - Langer, Norbert A1 - Scheithauer, S. T1 - Effects of rotation on the helium burning shell source in accreting white dwarfs N2 - We investigate the effects of rotation on the behavior of the helium-burning shell source in accreting carbon- oxygen white dwarfs, in the context of the single degenerate Chandrasekhar mass progenitor scenario for type la supernovae (SNe Ia). We model the evolution of helium-accreting white dwarfs of initially 1 M-circle dot, assuming four different constant accretion rates (2, 3, 5 and 10 x 10(-7) M-circle dot/yr). In a one-dimensional approximation, we compute the mass accretion and subsequent nuclear fusion of helium into carbon and oxygen, as well as angular momentum accretion, angular momentum transport inside the white dwarf, and rotationally induced chemical mixing. Our models show two major effects of rotation: a) The helium-burning nuclear shell source in the rotating models is much more stable than in corresponding non-rotating models - which increases the likelihood that accreting white dwarfs reach the stage of central carbon ignition. This effect is mainly due to rotationally induced mixing at the CO/He interface which widens the shell source, and due to the centrifugal force lowering the density and degeneracy at the shell source location. b) The C/O-ratio in the layers which experience helium shell burning - which may affect the energy of an SN Ia explosion - is strongly decreased by the rotationally induced mixing of a-particles into the carbon-rich layers. We discuss implications of our results for the evolution of SNe la progenitors Y1 - 2004 SN - 0004-6361 ER -