TY - JOUR A1 - Wagner, Nicole D. A1 - Hillebrand, Helmut A1 - Wacker, Alexander A1 - Frost, Paul C. T1 - Nutritional indicators and their uses in ecology JF - Ecology letters N2 - The nutrition of animal consumers is an important regulator of ecological processes due to its effects on their physiology, life-history and behaviour. Understanding the ecological effects of poor nutrition depends on correctly diagnosing the nature and strength of nutritional limitation. Despite the need to assess nutritional limitation, current approaches to delineating nutritional constraints can be non-specific and imprecise. Here, we consider the need and potential to develop new complementary approaches to the study of nutritional constraints on animal consumers by studying and using a suite of established and emerging biochemical and molecular responses. These nutritional indicators include gene expression, transcript regulators, protein profiling and activity, and gross biochemical and elemental composition. The potential applications of nutritional indicators to ecological studies are highlighted to demonstrate the value that this approach would have to future studies in community and ecosystem ecology. KW - Ecological stoichiometry KW - lipid profiling KW - metabolism KW - nutrient-stress KW - nutrition KW - proteomics KW - transcriptomics Y1 - 2013 U6 - https://doi.org/10.1111/ele.12067 SN - 1461-023X VL - 16 IS - 4 SP - 535 EP - 544 PB - Wiley-Blackwell CY - Hoboken ER - TY - THES A1 - Dethloff, Frederik T1 - In vivo 13C stable isotope tracing of single leaf development in the cold T1 - Stabile 13C Isotopenmarkierung zur in vivo Untersuchung der Einzelblattentwicklung in der Kälte N2 - Measuring the metabolite profile of plants can be a strong phenotyping tool, but the changes of metabolite pool sizes are often difficult to interpret, not least because metabolite pool sizes may stay constant while carbon flows are altered and vice versa. Hence, measuring the carbon allocation of metabolites enables a better understanding of the metabolic phenotype. The main challenge of such measurements is the in vivo integration of a stable or radioactive label into a plant without perturbation of the system. To follow the carbon flow of a precursor metabolite, a method is developed in this work that is based on metabolite profiling of primary metabolites measured with a mass spectrometer preceded by a gas chromatograph (Wagner et al. 2003; Erban et al. 2007; Dethloff et al. submitted). This method generates stable isotope profiling data, besides conventional metabolite profiling data. In order to allow the feeding of a 13C sucrose solution into the plant, a petiole and a hypocotyl feeding assay are developed. To enable the processing of large numbers of single leaf samples, their preparation and extraction are simplified and optimised. The metabolite profiles of primary metabolites are measured, and a simple relative calculation is done to gain information on carbon allocation from 13C sucrose. This method is tested examining single leaves of one rosette in different developmental stages, both metabolically and regarding carbon allocation from 13C sucrose. It is revealed that some metabolite pool sizes and 13C pools are tightly associated to relative leaf growth, i.e. to the developmental stage of the leaf. Fumaric acid turns out to be the most interesting candidate for further studies because pool size and 13C pool diverge considerably. In addition, the analyses are also performed on plants grown in the cold, and the initial results show a different metabolite pool size pattern across single leaves of one Arabidopsis rosette, compared to the plants grown under normal temperatures. Lastly, in situ expression of REIL genes in the cold is examined using promotor-GUS plants. Initial results suggest that single leaf metabolite profiles of reil2 differ from those of the WT. N2 - Messungen des pflanzlichen Metaboloms können ein hilfreiches Werkzeug sein, um Pflanzen zu phänotypisieren. Jedoch sind die Änderungen der Poolgrößen teilweise schwer zu interpretieren, weil sich nicht nur die Poolgrößen sondern auch die Kohlenstoffflüsse unabhängig voneinander ändern können. Werden nun zusätzlich Informationen über die Flüsse ermittelt, kann der pflanzliche Phänotyp deutlich genauer beschrieben werden. Die größte Herausforderung für diese Messungen ist die In-vivo-Integration einer stabilen oder radioaktiven Markierung in einer Pflanze, ohne das System dabei zu stören. In dieser Arbeit wird ein Verfahren entwickelt, um die Verteilung von Kohlenstoffen aus einer gefütterten Vorstufe zu messen. Die Messung basiert dabei auf einem Primärmetabolitenprofil, das mit Hilfe eines Massenspektrometers mit vorgeschaltetem Gaschromatographen erstellt wird (Wagner et al. 2003; Erban et al. 2007; Dethloff et al. eingereicht). Mit dieser Methode ist es einfach möglich, stabile Isotopenprofildaten neben herkömmlichen Metabolitprofildaten zu erzeugen. Die Vorstufe, in diesem Fall 13C Saccharose, wird dazu mit Hilfe eines neuen Petiolen- und Hypokotyl-Fütterungs-Assay in die Pflanze gefüttert. Um die große Menge an Einzelblattproben aufzuarbeiten, die dabei anfallen, wird eine vereinfachte und optimierte Extraktion angewendet. Mit Hilfe einer einfachen Berechnung kann aus den Messdaten eine relative Verteilung des Kohlenstoffs aus 13C Saccharose bestimmt werden. Die Funktionalität dieses Verfahrens wird an Einzelblättern von Arabidopsis-Rosetten gezeigt, wobei sowohl Primärmetabolitenprofile als auch stabile Isotopenprofile erzeugt und untersucht werden. Es kann hierbei gezeigt werden, dass konventionelle Poolgrößen und 13C Poolgrößen einiger Metaboliten eng mit dem relativen Wachstum einzelner Blattpositionen bzw. mit dem jeweiligen Entwicklungsstadium der Blätter zusammenhängen. Anders als bei den meisten anderen Metaboliten zeigen die konventionellen Poolgrößen und 13C Poolgrößen von Fumarsäure ein unterschiedliches Verhalten in den einzelnen Blättern, was Fumarsäure zum interessantesten Kandidaten für weitere Studien macht. Die beschriebenen Untersuchungen werden weiterhin an in Kälte gewachsenen Pflanzen durchgeführt, wobei erste Ergebnisse ein verändertes Metabolitenprofil in den einzelnen Blättern zeigen. Des Weiteren wird die In-situ-Expression von REIL-Genen mit Hilfe von Promotor-GUS-Reportern untersucht. Erste Ergebnisse von Einzelblatt-Metabolitenprofilen der reil2 zeigen einen deutlichen Unterschied zum WT. KW - stable isotope tracing KW - metabolism KW - sucrose KW - carbon flow KW - qualitative pathway interpretation Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-70486 ER - TY - JOUR A1 - Brothers, Soren M. A1 - Hilt, Sabine A1 - Attermeyer, Katrin A1 - Grossart, Hans-Peter A1 - Kosten, Sarian A1 - Lischke, Betty A1 - Mehner, Thomas A1 - Meyer, Nils A1 - Scharnweber, Inga Kristin A1 - Köhler, Jan T1 - A regime shift from macrophyte to phytoplankton dominance enhances carbon burial in a shallow, eutrophic lake JF - Ecosphere : the magazine of the International Ecology University N2 - Ecological regime shifts and carbon cycling in aquatic systems have both been subject to increasing attention in recent years, yet the direct connection between these topics has remained poorly understood. A four-fold increase in sedimentation rates was observed within the past 50 years in a shallow eutrophic lake with no surface in-or outflows. This change coincided with an ecological regime shift involving the complete loss of submerged macrophytes, leading to a more turbid, phytoplankton-dominated state. To determine whether the increase in carbon (C) burial resulted from a comprehensive transformation of C cycling pathways in parallel to this regime shift, we compared the annual C balances (mass balance and ecosystem budget) of this turbid lake to a similar nearby lake with submerged macrophytes, a higher transparency, and similar nutrient concentrations. C balances indicated that roughly 80% of the C input was permanently buried in the turbid lake sediments, compared to 40% in the clearer macrophyte-dominated lake. This was due to a higher measured C burial efficiency in the turbid lake, which could be explained by lower benthic C mineralization rates. These lower mineralization rates were associated with a decrease in benthic oxygen availability coinciding with the loss of submerged macrophytes. In contrast to previous assumptions that a regime shift to phytoplankton dominance decreases lake heterotrophy by boosting whole-lake primary production, our results suggest that an equivalent net metabolic shift may also result from lower C mineralization rates in a shallow, turbid lake. The widespread occurrence of such shifts may thus fundamentally alter the role of shallow lakes in the global C cycle, away from channeling terrestrial C to the atmosphere and towards burying an increasing amount of C. KW - calcite precipitation KW - CO2 emissions KW - global carbon cycle KW - metabolism KW - regime shift KW - sedimentation KW - submerged macrophytes KW - temperate zone KW - trophic status Y1 - 2013 U6 - https://doi.org/10.1890/ES13-00247.1 SN - 2150-8925 VL - 4 IS - 11 PB - Wiley CY - Washington ER -