@book{KloseKlostermannEngelmannetal.2006, author = {Klose, Dagmar and Klostermann, Anke and Engelmann, Anna-Maria and Jeltsch, Gesche and Dowall, Kathrin and Meyer, Georg and Glados, Andrea and Fischer, Raul and Hoffmann, Katrin and Kaiser, Christoph and Ladewig, Marco and Skouras, Andreas and Wienert, Christian and Wilkening, Gregor and Klaudius, Mathias and Goldbeck, Johanna and Duch, Sven and Werfel, Claudia and Viebig, Wenke and Neumann, Katharina and Dammnik, Sabine}, title = {Antike so fern und doch so nah}, editor = {Klose, Dagmar}, isbn = {978-3-939469-37-7}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-11179}, publisher = {Universit{\"a}t Potsdam}, year = {2006}, abstract = {Historisches Denken entwickeln am Gegenstand der altorientalischen,griechischen und r{\"o}mischen Antike, das ist Anliegen der didaktischen Handreichung f{\"u}r die gymnasiale Oberstufe. Didaktisch-methodische {\"U}berlegungen, Sachinformationen und ein handlungsorientierter Materialteil bieten f{\"u}r Lehrer und Sch{\"u}ler ein ideenreiches Angebot zur Auswahl f{\"u}r einen interessegeleiteten Geschichtsunterricht.}, language = {de} } @article{WolffKristenJennySchettleretal.2014, author = {Wolff, Christian Michael and Kristen-Jenny, Iris and Schettler, Georg and Plessen, Birgit and Meyer, Hanno and Dulski, Peter and Naumann, Rudolf and Brauer, Achim and Verschuren, Dirk and Haug, Gerald H.}, title = {Modern seasonality in Lake Challa (Kenya/Tanzania) and its sedimentary documentation in recent lake sediments}, series = {Limnology and oceanography}, volume = {59}, journal = {Limnology and oceanography}, number = {5}, publisher = {Wiley}, address = {Waco}, issn = {0024-3590}, doi = {10.4319/lo.2014.59.5.1621}, pages = {1621 -- 1636}, year = {2014}, abstract = {From November 2006 to January 2010, a sediment trap that was cleared monthly was deployed in Lake Challa, a deep stratified freshwater lake on the eastern slope of Mt. Kilimanjaro in southern Kenya. Geochemical data from sediment trap samples were compared with a broad range of limnological and meteorological parameters to characterize the effect of single parameters on productivity and sedimentation processes in the crater basin. During the southern hemisphere summer (November-March), when the water temperature is high and the lake is biologically productive (nondiatom algae), calcite predominated in the sediment trap samples. During the "long rain" season (March-May) a small amount of organic matter and lithogenic material caused by rainfall appeared. This was followed by the cool and windy months of the southern hemisphere winter (June-October) when diatoms were the main component, indicating a diatom bloom initiated by improvement of nutrient availability related to upwelling processes. The sediment trap data support the hypothesis that the light-dark lamination couplets, which are abundant in Lake Challa cores, reflect seasonal delivery to the sediments of diatom-rich particulates during the windy months and diatom-poor material during the wet season. However, interannual and spatial variability in upwelling and productivity patterns, as well as El Nino-Southern Oscillation (ENSO)-related rainfall and drought cycles, exert a strong influence on the magnitude and geochemical composition of particle export to the hypolimnion of Lake Challa.}, language = {en} } @article{MeyerRaberEbertetal.2015, author = {Meyer, S{\"o}ren and Raber, Georg and Ebert, Franziska and Taleshi, Mojtaba S. and Francesconi, Kevin A. and Schwerdtle, Tanja}, title = {Arsenic-containing hydrocarbons and arsenic-containing fatty acids: Transfer across and presystemic metabolism in the Caco-2 intestinal barrier model}, series = {Molecular nutrition \& food research : bioactivity, chemistry, immunology, microbiology, safety, technology}, volume = {59}, journal = {Molecular nutrition \& food research : bioactivity, chemistry, immunology, microbiology, safety, technology}, number = {10}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1613-4125}, doi = {10.1002/mnfr.201500286}, pages = {2044 -- 2056}, year = {2015}, abstract = {Scope: Arsenic-containing hydrocarbons (AsHCs) and arsenic-containing fatty acids (AsFAs) represent two classes of arsenolipids occurring naturally in marine food. Toxicological data are yet scarce and an assessment regarding the risk to human health has not been possible. Here, we investigated the transfer and presystemic metabolism of five arsenolipids in an intestinal barrier model. Methods and results: Three AsHCs and two AsFAs were applied to the Caco-2 intestinal barrier model. Thereby, the short-chain AsHCs reached up to 50\% permeability. Transport is likely to occur via passive diffusion. The AsFAs showed lower intestinal bioavailability, but respective permeabilities were still two to five times higher as compared to arsenobetaine or arsenosugars. Interestingly, AsFAs were effectively biotransformed while passing the in vitro intestinal barrier, whereas AsHCs were transported to the blood-facing compartment essentially unchanged. Conclusion: AsFAs can be presystemically metabolised and the amount of transferred arsenic is lower than that for AsHCs. In contrast, AsHCs are likely to be highly intestinally bioavailable to humans. Since AsHCs exert strong toxicity in vitro and in vivo, toxicity studies with experimental animals as well as a human exposure assessment are needed to assess the risk to human health related to the presence of AsHCs in seafood.}, language = {en} } @article{EbertMeyerLeffersetal.2016, author = {Ebert, Franziska and Meyer, S{\"o}ren and Leffers, Larissa and Raber, Georg and Francesconi, Kevin A. and Schwerdtle, Tanja}, title = {Toxicological characterisation of a thio-arsenosugar-glycerol in human cells}, series = {Journal of trace elements in medicine and biology}, volume = {38}, journal = {Journal of trace elements in medicine and biology}, publisher = {Springer Publishing Company}, address = {Jena}, issn = {0946-672X}, doi = {10.1016/j.jtemb.2016.04.013}, pages = {150 -- 156}, year = {2016}, abstract = {Arsenosugars are water-soluble arsenic species predominant in marine algae and other seafood including mussels and oysters. They typically occur at levels ranging from 2 to 50 mg arsenic/kg dry weight. Most of the arsenosugars contain arsenic as a dimethylarsinoyl group (Me2As(O)-), commonly referred to as the oxo forms, but thio analogues have also been identified in marine organisms and as metabolic products of oxo-arsenosugars. So far, no data regarding toxicity and toxicokinetics of thio-arsenosugars are available. This in vitro-based study indicates that thio-dimethylarsenosugar-glycerol exerts neither pronounced cytotoxicity nor genotoxicity even though this arsenical was bioavailable to human hepatic (HepG2) and urothelial (UROtsa) cells. Experiments with the Caco-2 intestinal barrier model mimicking human absorption indicate for the thio-arsenosugar-glycerol higher intestinal bioavailability as compared to the oxo-arsenosugars. Nevertheless, absorption estimates were much lower in comparison to other arsenicals including arsenite and arsenic-containing hydrocarbons. Arsenic speciation in cell lysates revealed that HepG2 cells are able to metabolise the thio-arsenosugar-glycerol to some extent to dimethylarsinic acid (DMA). These first in vitro data cannot fully exclude risks to human health related to the presence of thio-arsenosugars in food. (C) 2016 Elsevier GmbH. All rights reserved.}, language = {en} } @article{MeyerRaberEbertetal.2015, author = {Meyer, S{\"o}ren and Raber, Georg and Ebert, Franziska and Leffers, L. and Mueller, Sandra Maria and Taleshi, M. S. and Francesconi, Kevin A. and Schwerdtle, Tanja}, title = {In vitro toxicological characterisation of arsenic-containing fatty acids and three of their metabolites}, series = {Toxicology research}, volume = {4}, journal = {Toxicology research}, number = {5}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2045-452X}, doi = {10.1039/c5tx00122f}, pages = {1289 -- 1296}, year = {2015}, abstract = {Arsenic-containing fatty acids are a group of fat-soluble arsenic species (arsenolipids) which are present in marine fish and other seafood. Recently, it has been shown that arsenic-containing hydrocarbons, another group of arsenolipids, exert toxicity in similar concentrations comparable to arsenite although the toxic modes of action differ. Hence, a risk assessment of arsenolipids is urgently needed. In this study the cellular toxicity of a saturated (AsFA 362) and an unsaturated (AsFA 388) arsenic-containing fatty acid and three of their proposed metabolites (DMA(V), DMAPr and thio-DMAPr) were investigated in human liver cells (HepG2). Even though both arsenic-containing fatty acids were less toxic as compared to arsenic-containing hydrocarbons and arsenite, significant effects were observable at mu M concentrations. DMA(V) causes effects in a similar concentration range and it could be seen that it is metabolised to its highly toxic thio analogue thio-DMA(V) in HepG2 cells. Nevertheless, DMAPr and thio-DMAPr did not exert any cytotoxicity. In summary, our data indicate that risks to human health related to the presence of arsenic-containing fatty acids in marine food cannot be excluded. This stresses the need for a full in vitro and in vivo toxicological characterisation of these arsenolipids.}, language = {en} } @article{PohleHosoyaPohleetal.2022, author = {Pohle, Lara and Hosoya, Georg and Pohle, Jennifer and Meyer-Jenßen, Lars}, title = {The relationship between early childhood teachers' instructional quality and children's mathematics development}, series = {Learning and instruction : the journal of the European Association for Research on Learning and Instruction}, volume = {82}, journal = {Learning and instruction : the journal of the European Association for Research on Learning and Instruction}, publisher = {Elsevier}, address = {Oxford}, issn = {0959-4752}, doi = {10.1016/j.learninstruc.2022.101636}, pages = {12}, year = {2022}, abstract = {This study examined how early childhood (EC) teachers' instructional quality predicted children's development in mathematics across two measurement occasions. Therefore, EC teachers' (n = 25) instructional quality was assessed using one standardized observation instrument covering both domain-specific and general aspects of instructional quality. Additionally, data on children's (n = 208) outcome in early number skills was collected applying a standardized test. Multilevel structural equation modeling was used accounting for nested data. Children's age and the average size of preschool groups were controlled for. Results revealed that EC teachers' instructional quality predicted children's development but was not associated with their initial achievement. The findings suggest that instruments covering domain-specific and general aspects might be helpful in order to measure EC teachers' instructional quality in mathematics and predict children's learning growth. Understanding the mechanisms between instructional quality and children's development may help EC teachers to enhance their math teaching in practice.}, language = {en} } @article{BornhorstEbertMeyeretal.2020, author = {Bornhorst, Julia and Ebert, Franziska and Meyer, S{\"o}ren and Ziemann, Vanessa and Xiong, Chan and Guttenberger, Nikolaus and Raab, Andrea and Baesler, Jessica and Aschner, Michael and Feldmann, J{\"o}rg and Francesconi, Kevin and Raber, Georg and Schwerdtle, Tanja}, title = {Toxicity of three types of arsenolipids}, series = {Metallomics}, volume = {12}, journal = {Metallomics}, number = {5}, publisher = {Oxford University Press}, address = {Cambridge}, issn = {1756-591X}, doi = {https://doi.org/10.1039/d0mt00039f}, pages = {794 -- 798}, year = {2020}, abstract = {Although fish and seafood are well known for their nutritional benefits, they contain contaminants that might affect human health. Organic lipid-soluble arsenic species, so called arsenolipids, belong to the emerging contaminants in these food items; their toxicity has yet to be systematically studied. Here, we apply the in vivo model Caenorhabditis elegans to assess the effects of two arsenic-containing hydrocarbons (AsHC), a saturated arsenic-containing fatty acid (AsFA), and an arsenic-containing triacylglyceride (AsTAG) in a whole organism. Although all arsenolipids were highly bioavailable in Caenorhabditis elegans, only the AsHCs were substantially metabolized to thioxylated or shortened metabolic products and induced significant toxicity, affecting both survival and development. Furthermore, the AsHCs were several fold more potent as compared to the toxic reference arsenite. This study clearly indicates the need for a full hazard identification of subclasses of arsenolipids to assess whether they pose a risk to human health.}, language = {en} } @article{MuellerEbertRaberetal.2018, author = {M{\"u}ller, Sandra Marie and Ebert, Franziska and Raber, Georg and Meyer, S{\"o}ren and Bornhorst, Julia and H{\"u}wel, Stephan and Galla, Hans-Joachim and Francesconi, Kevin A. and Schwerdtle, Tanja}, title = {Effects of arsenolipids on in vitro blood-brain barrier model}, series = {Archives of toxicology : official journal of EUROTOX}, volume = {92}, journal = {Archives of toxicology : official journal of EUROTOX}, number = {2}, publisher = {Springer}, address = {Heidelberg}, issn = {0340-5761}, pages = {823 -- 832}, year = {2018}, abstract = {Arsenic-containing hydrocarbons (AsHCs), a subgroup of arsenolipids (AsLs) occurring in fish and edible algae, possess a substantial neurotoxic potential in fully differentiated human brain cells. Previous in vivo studies indicating that AsHCs cross the blood-brain barrier of the fruit fly Drosophila melanogaster raised the question whether AsLs could also cross the vertebrate blood-brain barrier (BBB). In the present study, we investigated the impact of several representatives of AsLs (AsHC 332, AsHC 360, AsHC 444, and two arsenic-containing fatty acids, AsFA 362 and AsFA 388) as well as of their metabolites (thio/oxo-dimethylpropionic acid, dimethylarsinic acid) on porcine brain capillary endothelial cells (PBCECs, in vitro model for the blood-brain barrier). AsHCs exerted the strongest cytotoxic effects of all investigated arsenicals as they were up to fivefold more potent than the toxic reference species arsenite (iAsIII). In our in vitro BBB-model, we observed a slight transfer of AsHC 332 across the BBB after 6 h at concentrations that do not affect the barrier integrity. Furthermore, incubation with AsHCs for 72 h led to a disruption of the barrier at sub-cytotoxic concentrations. The subsequent immunocytochemical staining of three tight junction proteins revealed a significant impact on the cell membrane. Because AsHCs enhance the permeability of the in vitro blood-brain barrier, a similar behavior in an in vivo system cannot be excluded. Consequently, AsHCs might facilitate the transfer of accompanying foodborne toxicants into the brain.}, language = {en} } @article{BiskabornNazarovaPestryakovaetal.2019, author = {Biskaborn, Boris and Nazarova, Larisa B. and Pestryakova, Luidmila Agafyevna and Syrykh, Liudmila and Funck, Kim and Meyer, Hanno and Chapligin, Bernhard and Vyse, Stuart Andrew and Gorodnichev, Ruslan and Zakharov, Evgenii and Wang, Rong and Schwamborn, Georg and Bailey, Hannah L. and Diekmann, Bernhard}, title = {Spatial distribution of environmental indicators in surface sediments of Lake Bolshoe Toko, Yakutia, Russia}, series = {Biogeosciences}, volume = {16}, journal = {Biogeosciences}, number = {20}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1726-4170}, doi = {10.5194/bg-16-4023-2019}, pages = {4023 -- 4049}, year = {2019}, abstract = {Rapidly changing climate in the Northern Hemisphere and associated socio-economic impacts require reliable understanding of lake systems as important freshwater resources and sensitive sentinels of environmental change. To better understand time-series data in lake sediment cores, it is necessary to gain information on within-lake spatial variabilities of environmental indicator data. Therefore, we retrieved a set of 38 samples from the sediment surface along spatial habitat gradients in the boreal, deep, and yet pristine Lake Bolshoe Toko in southern Yakutia, Russia. Our methods comprise laboratory analyses of the sediments for multiple proxy parameters, including diatom and chironomid taxonomy, oxygen isotopes from diatom silica, grain-size distributions, elemental compositions (XRF), organic carbon content, and mineralogy (XRD). We analysed the lake water for cations, anions, and isotopes. Our results show that the diatom assemblages are strongly influenced by water depth and dominated by planktonic species, i.e. Pliocaenicus bolshetokoensis. Species richness and diversity are higher in the northern part of the lake basin, associated with the availability of benthic, i.e. periphytic, niches in shallower waters. delta O-18(diatom) values are higher in the deeper south-western part of the lake, probably related to water temperature differences. The highest amount of the chironomid taxa underrepresented in the training set used for palaeoclimate inference was found close to the Utuk River and at southern littoral and profundal sites. Abiotic sediment components are not symmetrically distributed in the lake basin, but vary along restricted areas of differential environmental forcing. Grain size and organic matter are mainly controlled by both river input and water depth. Mineral (XRD) data distributions are influenced by the methamorphic lithology of the Stanovoy mountain range, while elements (XRF) are intermingled due to catchment and diagenetic differences. We conclude that the lake represents a valuable archive for multiproxy environmental reconstruction based on diatoms (including oxygen isotopes), chironomids, and sediment-geochemical parameters. Our analyses suggest multiple coring locations preferably at intermediate depth in the northern basin and the deep part in the central basin, to account for representative bioindicator distributions and higher temporal resolution, respectively.}, language = {en} }