TY - JOUR A1 - van der Kroef, Ilona A1 - Koszinski, Sylvia A1 - Grinat, Michael A1 - van der Meij, Marijn W. A1 - Hierold, Wilfried A1 - Südekum, Wolfgang A1 - Sommer, Michael T1 - Digital mapping of buried soil horizons using 2D and pseudo-3D geoelectrical measurements in a ground moraine landscape JF - European journal of soil science : EJSS N2 - The identification of buried soil horizons in agricultural landscapes helps to quantify sediment budgets and erosion-related carbon dynamics. High-resolution mapping of buried horizons using conventional soil surveys is destructive and time consuming. Geoelectrical sensors can offer a fast and non-destructive alternative for determining horizon positions and properties. In this paper, we compare the suitability of several geoelectrical methods for measuring the depth to buried horizons (Apb, Ahb and Hab) in the hummocky ground moraine landscape of northeastern Germany. Soil profile descriptions were developed for 269 locations within a 6-ha experimental field "CarboZALF-D". A stepwise linear discriminant analysis (LDA) estimated the lateral position of the buried horizons using electromagnetic induction data and terrain attributes. To predict the depth of a buried horizon, multiple linear regression (MLR) was used for both a 120-m transect and a 0.2-ha pseudo-three-dimensional (3D) area. At these scales, apparent electrical conductivity (ECa), electrical resistivity (ER) and terrain attributes were used as independent variables. The LDA accurately predicted Apb- and Ahb-horizons (a correct classification of 93%). The LDA of the Hab-horizon had a misclassification of 24%, which was probably related to the smaller test set and the higher depth of this horizon. The MLR predicted the depth of the Apb-, Ahb- and Hab-horizons with relative root mean square errors (RMSEs) of 7, 3 and 13%, respectively, in the pseudo-3D area. MLR had a lower accuracy for the 2D transect compared to the pseudo-3D area. Overall, the use of LDA and MLR has been an efficient methodological approach for predicting buried horizon positions. Highlights The suitability of geoelectrical measurements for digital modelling of diagnostic buried soil horizons was determined. LDA and MLR were used to detect multiple horizons with geoelectrical devices and terrain attributes. Geoelectrical variables were significant predictors of the position of the target soil horizons. The use of these tested digital technologies gives an opportunity to develop high-resolution soil mapping procedures. KW - colluvium depth modelling KW - electrical conductivity KW - electrical resistivity tomography KW - electromagnetic induction KW - EM38DD KW - linear discriminant analysis KW - linear regression KW - moraine soil landscape Y1 - 2019 SN - 1351-0754 SN - 1365-2389 VL - 71 IS - 1 SP - 10 EP - 26 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Chang, Dan A1 - Knapp, Michael A1 - Enk, Jacob A1 - Lippold, Sebastian A1 - Kircher, Martin A1 - Lister, Adrian M. A1 - MacPhee, Ross D. E. A1 - Widga, Christopher A1 - Czechowski, Paul A1 - Sommer, Robert A1 - Hodges, Emily A1 - Stümpel, Nikolaus A1 - Barnes, Ian A1 - Dalén, Love A1 - Derevianko, Anatoly A1 - Germonpré, Mietje A1 - Hillebrand-Voiculescu, Alexandra A1 - Constantin, Silviu A1 - Kuznetsova, Tatyana A1 - Mol, Dick A1 - Rathgeber, Thomas A1 - Rosendahl, Wilfried A1 - Tikhonov, Alexey N. A1 - Willerslev, Eske A1 - Hannon, Greg A1 - Lalueza i Fox, Carles A1 - Joger, Ulrich A1 - Poinar, Hendrik N. A1 - Hofreiter, Michael A1 - Shapiro, Beth T1 - The evolutionary and phylogeographic history of woolly mammoths BT - a comprehensive mitogenomic analysis JF - Scientific reports N2 - Near the end of the Pleistocene epoch, populations of the woolly mammoth (Mammuthus primigenius) were distributed across parts of three continents, from western Europe and northern Asia through Beringia to the Atlantic seaboard of North America. Nonetheless, questions about the connectivity and temporal continuity of mammoth populations and species remain unanswered. We use a combination of targeted enrichment and high-throughput sequencing to assemble and interpret a data set of 143 mammoth mitochondrial genomes, sampled from fossils recovered from across their Holarctic range. Our dataset includes 54 previously unpublished mitochondrial genomes and significantly increases the coverage of the Eurasian range of the species. The resulting global phylogeny confirms that the Late Pleistocene mammoth population comprised three distinct mitochondrial lineages that began to diverge ~1.0–2.0 million years ago (Ma). We also find that mammoth mitochondrial lineages were strongly geographically partitioned throughout the Pleistocene. In combination, our genetic results and the pattern of morphological variation in time and space suggest that male-mediated gene flow, rather than large-scale dispersals, was important in the Pleistocene evolutionary history of mammoths. Y1 - 2017 U6 - https://doi.org/10.1038/srep44585 SN - 2045-2322 VL - 7 PB - Nature Publishing Group CY - London ER - TY - JOUR A1 - Hemme, Dorothea A1 - Veyel, Daniel A1 - Muehlhaus, Timo A1 - Sommer, Frederik A1 - Jueppner, Jessica A1 - Unger, Ann-Katrin A1 - Sandmann, Michael A1 - Fehrle, Ines A1 - Schoenfelder, Stephanie A1 - Steup, Martin A1 - Geimer, Stefan A1 - Kopka, Joachim A1 - Giavalisco, Patrick A1 - Schroda, Michael T1 - Systems-wide analysis of acclimation responses to long-term heat stress and recovery in the photosynthetic model organism Chlamydomonas reinhardtii JF - The plant cell N2 - We applied a top-down systems biology approach to understand how Chlamydomonas reinhardtii acclimates to long-term heat stress (HS) and recovers from it. For this, we shifted cells from 25 to 42 degrees C for 24 h and back to 25 degrees C for >= 8 h and monitored abundances of 1856 proteins/protein groups, 99 polar and 185 lipophilic metabolites, and cytological and photosynthesis parameters. Our data indicate that acclimation of Chlamydomonas to long-term HS consists of a temporally ordered, orchestrated implementation of response elements at various system levels. These comprise (1) cell cycle arrest; (2) catabolism of larger molecules to generate compounds with roles in stress protection; (3) accumulation of molecular chaperones to restore protein homeostasis together with compatible solutes; (4) redirection of photosynthetic energy and reducing power from the Calvin cycle to the de novo synthesis of saturated fatty acids to replace polyunsaturated ones in membrane lipids, which are deposited in lipid bodies; and (5) when sinks for photosynthetic energy and reducing power are depleted, resumption of Calvin cycle activity associated with increased photorespiration, accumulation of reactive oxygen species scavengers, and throttling of linear electron flow by antenna uncoupling. During recovery from HS, cells appear to focus on processes allowing rapid resumption of growth rather than restoring pre-HS conditions. Y1 - 2014 U6 - https://doi.org/10.1105/tpc.114.130997 SN - 1040-4651 SN - 1532-298X VL - 26 IS - 11 SP - 4270 EP - 4297 PB - American Society of Plant Physiologists CY - Rockville ER - TY - JOUR A1 - Kaiser, Michael A1 - Ellerbrock, Ruth H. A1 - Sommer, Michael T1 - Separation of coarse organic particles from bulk surface soil samples by electrostatic attraction N2 - Different separation procedures are suggested for studying the stability and functionality of sod organic matter (OM). Density fractionation procedures using high-molarity, water-based salt solutions to separate organic particles may cause losses or transfers of C between particle and soluble OM fractions during separation, which may be a result of solution processes. The objective of this study was to separate coarse organic particles (>0.315 mm) from air- dried surface soil samples to avoid such solution processes as far as possible. Air-dried surface soil samples (<2 mm) from nine adjacent arable and forest sites were sieved into five soil particle size fractions (2-1.25, 1.25-0.8, 0.8- 0.5, 0.5-0.4, and 0.4-0.315 mm). Coarse organic particles were separated from each of these fractions using electrostatic attraction by a charged glass surface. The sum of the total dry matter content of the electrostatically separated coarse organic particles ranged from 0.05 to 140 g kg(-1). Scanning electron microscopy images and organic C (OC) analyses indicated, however, that the coarse organic particle fractions were also composed of 20 to 76% mineral particles (i.e., 200-760 g mineral kg(-1) fraction). The repeatability of the electrostatic attraction procedure falls within a range similar to that of accepted density fractionation methods using high-molarity salt solutions. Based on the similarity in repeatability, we suggest that the electrostatic attraction procedure will successfully remove coarse organic particles (>0.315 mm) from air-dried surface soil samples. Because aqueous solutions are not used, the electrostatic attraction procedure to separate coarse organic particles avoids C losses and transfers associated with solution-dependent techniques. Therefore, this method can be used as a pretreatment for subsequent density- or solubility-based soil OM fractionation procedures. Y1 - 2009 UR - https://www.soils.org/publications/sssaj U6 - https://doi.org/10.2136/sssaj2009.0046 SN - 0361-5995 ER - TY - JOUR A1 - Kaiser, Michael A1 - Berhe, Asmeret Asefaw A1 - Sommer, Michael A1 - Kleber, Markus T1 - Application of ultrasound to disperse soil aggregates of high mechanical stability JF - Journal of plant nutrition and soil science = Zeitschrift für Pflanzenernährung und Bodenkunde N2 - Questions remain about the exact ultrasonic energy level that is required to effectively disperse soil aggregates and to what extent this is accompanied by physical damage to individual soil particles. We found maximum aggregate dispersion at energy levels of 1500 J?cm3 and no evidence for the disintegration of particles < 20 mu m even at that energy level. Our findings suggest that sonication at energies much greater than those applied conventionally can disperse aggregates of high mechanical stability. KW - soil aggregates KW - ultrasonication KW - dispersion maxima KW - water-extractable elements Y1 - 2012 U6 - https://doi.org/10.1002/jpln.201200077 SN - 1436-8730 VL - 175 IS - 4 SP - 521 EP - 526 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Kaiser, Michael A1 - Walter, K. A1 - Ellerbrock, Ruth H. A1 - Sommer, Michael T1 - Effects of land use and mineral characteristics on the organic carbon content, and the amount and composition of Na-pyrophosphate-soluble organic matter, in subsurface soils JF - European journal of soil science N2 - Land use and mineral characteristics affect the ability of surface as well as subsurface soils to sequester organic carbon and their contribution to mitigation of the greenhouse effect. There is less information about the effects of land use and soil properties on the amount and composition of organic matter (OM) for subsurface soils as compared with surface soils. Here we aimed to analyse the long-term (>= 100 years) impact of arable and forest land use and soil mineral characteristics on subsurface soil organic carbon (SOC) contents, as well as on amount and composition of OM sequentially separated by Na pyrophosphate solution (OM(PY)) from subsurface soil samples. Seven soils with different mineral characteristics (Albic and Haplic Luvisol, Colluvic and Haplic Regosol, Haplic and Vertic Cambisol, Haplic Stagnosol) were selected from within Germany. Soil samples were taken from subsurface horizons of forest and adjacent arable sites continuously used for > 100 years. The OM(PY) fractions were analysed for their OC content (OC(PY)) and characterized by Fourier transform infrared spectroscopy. Multiple regression analyses for the arable subsurface soils indicated significant positive relationships between the SOC contents and combined effects of the (i) exchangeable Ca (Ca(ex)) and oxalate-soluble Fe (Fe(ox)) and (ii) the Ca(ex) and Al(ox) contents. For these soils the increase in OC (OC(PY) multiplied by the relative C=O content of OM(PY)) and increasing contents of Ca(ex) indicated that OM(PY) mainly interacts with Ca2+. For the forest subsurface soils (pH < 5), the OC(PY) contents were related to the contents of Na-pyrophosphate-soluble Fe and Al. The long-term arable and forest land use seems to result in different OM(PY)-mineral interactions in subsurface soils. On the basis of this, we hypothesize that a long-term land-use change from arable to forest may lead to a shift from mainly OM(PY)-Ca2+ to mainly OM(PY)-Fe3+ and -Al3+ interactions if the pH of subsurface soils significantly decreases to < 5. Y1 - 2011 U6 - https://doi.org/10.1111/j.1365-2389.2010.01340.x SN - 1351-0754 VL - 62 IS - 2 SP - 226 EP - 236 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Kaiser, Michael A1 - Zederer, Dan P. A1 - Ellerbrock, Ruth H. A1 - Sommer, Michael A1 - Ludwig, Bernard T1 - Effects of mineral characteristics on content, composition, and stability of organic matter fractions separated from seven forest topsoils of different pedogenesis JF - Geoderma : an international journal of soil science N2 - Mineral topsoils possess large organic carbon (OC) contents but there is only limited knowledge on the mechanisms controlling the preservation of organic matter (OM) against microbial decay. Samples were taken from the uppermost mineral topsoil horizon (0 to 5 cm) of seven sites under mature deciduous forest showing OC contents between 69 and 164 g kg(-1) and a wide range in mineral characteristics. At first, organic particles and the water-extractable OM were removed from the soil samples. Thereafter, Na-pyrophosphate extractable organic matter (OM(PY)), assumed to be indicative for OM bound via cation mediated interactions, and the OM remaining in the extraction residue (OM(ER)), supposed to be indicative for OM occluded in mechanically highly stable micro-aggregates, were sequentially separated and quantified. The composition of OM(PY) and OM(ER) was analyzed by FTIR and their stability by C-14 measurements. The OC remaining in the extraction residues accounted for 38 to 59% of the bulk soil OC (SOC) suggesting a much larger relevance of OM(ER) for the OM dynamic in the analyzed soils as compared with OM(PY) that accounted for 1.6 to 7.5% of the SOC. The FUR analyses revealed a lower relative proportion of C=O groups in OM(ER) compared to OM(PY) indicating differences in the degree of microbial processing between these fractions. Correlation analyses suggest an increase in the stability of OM(PY) with the soil pH and contents of Na-pyrophosphate soluble Fe, Al, and Mg and an increase in the stability of OM(ER) with the soil pH and the contents of clay and oxalate-soluble Fe and Al. Despite the detected influence of soil mineral characteristics on the turnover of OM(PY) and OM(ER), the Delta C-14 signatures indicated mean residence times less than 100 years. The presence of less stabilized OM in these fractions can be derived from methodological uncertainties and/or the fast cycling compartment of mineral-associated OM. (C) 2015 Elsevier B.V. All rights reserved. KW - Forest mineral topsoil KW - Organic matter stabilization KW - Na-pyrophosphate soluble organic matter KW - Micro-aggregates KW - Infrared spectroscopy KW - C-14 analyses Y1 - 2016 U6 - https://doi.org/10.1016/j.geoderma.2015.08.029 SN - 0016-7061 SN - 1872-6259 VL - 263 SP - 1 EP - 7 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Giraudier, Manon A1 - Ventura-Bort, Carlos A1 - Burger, Andreas M. A1 - Claes, Nathalie A1 - D'Agostini, Martina A1 - Fischer, Rico A1 - Franssen, Mathijs A1 - Kaess, Michael A1 - Koenig, Julian A1 - Liepelt, Roman A1 - Nieuwenhuis, Sander A1 - Sommer, Aldo A1 - Usichenko, Taras A1 - Van Diest, Ilse A1 - von Leupoldt, Andreas A1 - Warren, Christopher Michael A1 - Weymar, Mathias T1 - Evidence for a modulating effect of transcutaneous auricular vagus nerve stimulation (taVNS) on salivary alpha-amylase as indirect noradrenergic marker: A pooled mega-analysis T2 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe N2 - Background Non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) has received tremendous attention as a potential neuromodulator of cognitive and affective functions, which likely exerts its effects via activation of the locus coeruleus-noradrenaline (LC-NA) system. Reliable effects of taVNS on markers of LC-NA system activity, however, have not been demonstrated yet. Methods The aim of the present study was to overcome previous limitations by pooling raw data from a large sample of ten taVNS studies (371 healthy participants) that collected salivary alpha-amylase (sAA) as a potential marker of central NA release. Results While a meta-analytic approach using summary statistics did not yield any significant effects, linear mixed model analyses showed that afferent stimulation of the vagus nerve via taVNS increased sAA levels compared to sham stimulation (b = 0.16, SE = 0.05, p = 0.001). When considering potential confounders of sAA, we further replicated previous findings on the diurnal trajectory of sAA activity. Conclusion(s) Vagal activation via taVNS increases sAA release compared to sham stimulation, which likely substantiates the assumption that taVNS triggers NA release. Moreover, our results highlight the benefits of data pooling and data sharing in order to allow stronger conclusions in research. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 808 KW - Non-invasive vagus nerve stimulation KW - tVNS KW - sAA KW - Noradrenaline KW - Biomarker KW - Data pooling Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-577668 SN - 1866-8364 IS - 808 SP - 1378 EP - 1388 ER - TY - JOUR A1 - Giraudier, Manon A1 - Ventura-Bort, Carlos A1 - Burger, Andreas M. A1 - Claes, Nathalie A1 - D'Agostini, Martina A1 - Fischer, Rico A1 - Franssen, Mathijs A1 - Kaess, Michael A1 - Koenig, Julian A1 - Liepelt, Roman A1 - Nieuwenhuis, Sander A1 - Sommer, Aldo A1 - Usichenko, Taras A1 - Van Diest, Ilse A1 - von Leupoldt, Andreas A1 - Warren, Christopher Michael A1 - Weymar, Mathias T1 - Evidence for a modulating effect of transcutaneous auricular vagus nerve stimulation (taVNS) on salivary alpha-amylase as indirect noradrenergic marker: A pooled mega-analysis JF - Brain Stimulation N2 - Background Non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) has received tremendous attention as a potential neuromodulator of cognitive and affective functions, which likely exerts its effects via activation of the locus coeruleus-noradrenaline (LC-NA) system. Reliable effects of taVNS on markers of LC-NA system activity, however, have not been demonstrated yet. Methods The aim of the present study was to overcome previous limitations by pooling raw data from a large sample of ten taVNS studies (371 healthy participants) that collected salivary alpha-amylase (sAA) as a potential marker of central NA release. Results While a meta-analytic approach using summary statistics did not yield any significant effects, linear mixed model analyses showed that afferent stimulation of the vagus nerve via taVNS increased sAA levels compared to sham stimulation (b = 0.16, SE = 0.05, p = 0.001). When considering potential confounders of sAA, we further replicated previous findings on the diurnal trajectory of sAA activity. Conclusion(s) Vagal activation via taVNS increases sAA release compared to sham stimulation, which likely substantiates the assumption that taVNS triggers NA release. Moreover, our results highlight the benefits of data pooling and data sharing in order to allow stronger conclusions in research. KW - Non-invasive vagus nerve stimulation KW - tVNS KW - sAA KW - Noradrenaline KW - Biomarker KW - Data pooling Y1 - 2022 U6 - https://doi.org/10.1016/j.brs.2022.09.009 SN - 1876-4754 VL - 15 SP - 1378 EP - 1388 PB - Elsevier CY - New York, NY, USA ET - 6 ER - TY - JOUR A1 - Wanner, Manfred A1 - Elmer, Michael A1 - Sommer, Michael A1 - Funk, Roger A1 - Puppe, Daniel T1 - Testate amoebae colonizing a newly exposed land surface are of airborne origin JF - Ecological indicators : integrating monitoring, assessment and management N2 - We hypothesized that at the very beginning of terrestrial ecosystem development, airborne testate amoebae play a pivotal role in facilitating organismic colonization and related soil processes. We, therefore, analyzed size and quantity of airborne testate amoebae and immigration and colonization success of airborne testate amoebae on a new land surface (experimental site "Chicken Creek", artificial post-mining water catchment). Within an altogether 91-day exposure of 70 adhesive traps, 12 species of testate amoebae were identified to be of airborne origin. Phryganella acropodia (51% of all individuals found, diameter about 35-45 mu m) and Centropyxis sphagnicola (23% of all individuals found, longest axis about 55-68 mu m), occurred most frequently in the adhesive traps. We extrapolated an aerial amoeba deposition of 61 individuals d(-1) m(-2) (living and dead individuals combined). Although it would be necessary to have a longer sequence (some additional years), our analysis of the "target substrate" of aerial immigration (catchment site) may point to a shift from a stochastic (variable) beginning of community assembly to a more deterministic (stable) course. This shift was assigned to an age of seven years of initial soil development. Although experienced specialists are necessary to conduct these time-consuming studies, the presented data suggest that terrestrial amoebae are suitable indicators for initial ecosystem development and utilization. KW - Artificial water catchment KW - Immigration by air KW - Biological indicator Y1 - 2015 U6 - https://doi.org/10.1016/j.ecolind.2014.07.037 SN - 1470-160X SN - 1872-7034 VL - 48 SP - 55 EP - 62 PB - Elsevier CY - Amsterdam ER -