TY - JOUR A1 - Pagel, Jörn A1 - Fritzsch, Katrin A1 - Biedermann, Robert A1 - Schröder-Esselbach, Boris T1 - Annual plants under cyclic disturbance regime : better understanding through model aggregation N2 - In their application for conservation ecology, 'classical' analytical models and individual-based simulation models (IBMs) both entail their specific strengths and weaknesses, either in providing a detailed and realistic representation of processes or in regard to a comprehensive model analysis. This well-known dilemma may be resolved by the combination of both approaches when tackling certain problems of conservation ecology. Following this idea, we present the complementary use of both an IBM and a matrix population model in a case study on grassland conservation management. First, we develop a spatially explicit IBM to simulate the long-term response of the annual plant Thlaspi perfoliatum (Brassicaceae), claspleaf pennycress, to different management schemes (annual mowing vs. infrequent rototilling) based on field experiments. In order to complement the simulation results by further analyses, we aggregate the IBM to a spatially nonexplicit deterministic matrix population model. Within the periodic environment created by management regimes, population dynamics are described by periodic products of annual transition matrices. Such periodic matrix products provide a very conclusive framework to study the responses of species to different management return intervals. Thus, using tools of matrix model analysis (e.g., loop analysis), we can both identify dormancy within the age-structured seed bank as the pivotal strategy for persistence under cyclic disturbance regimes and reveal crucial thresholds in some less certain parameters. Results of matrix model analyses are therefore successfully tested by comparing their results to the respective IBM simulations. Their implications for an enhanced scientific basis for management decisions are discussed as well as some general benefits and limitations of the use of aggregating modeling approaches in conservation. Y1 - 2008 UR - 1960 = DOI: 10.1890/07-1305.1 SN - 1051-0761 ER - TY - THES A1 - Wagner, Kerstin T1 - The regulation of phopholipase activity by lipid membrane structure Y1 - 2007 CY - Potsdam ER - TY - THES A1 - Eisinger, Dirk T1 - A new management model for developing small scale contingency plans of rabies Y1 - 2007 CY - Potsdam ER - TY - THES A1 - Morozova, Daria T1 - Tolerance limits and survival potential of methanogenic archaea from Siberian permafrost under extreme liveing conditions Y1 - 2007 CY - Potsdam ER - TY - THES A1 - Rautengarten, Carsten T1 - Subtilisin-like serine proteases : in Arabidopsis thaliana (L.) Heynh. Y1 - 2007 CY - Potsdam ER - TY - THES A1 - Neumann-Schaal, Meina T1 - Studies on the mechanism molybdenum cofactor sulfuration and insertion into rhodobacter capsulatus xanthine dehydrogenase Y1 - 2007 CY - Potsdam ER - TY - JOUR A1 - Köchy, Martin A1 - Tielbörger, Katja T1 - Hydrothermal time model of germination : parameters for 36 Mediterranean annual species based on a simplified approach N2 - Germination rates and germination fractions of seeds can be predicted well by the hydrothermal time (HTT) model. Its four parameters hydrothermal time, minimum soil temperature, minimum soil moisture, and variation of minimum soil moisture, however, must be determined by lengthy germination experiments at combinations of several levels of soil temperature and moisture. For some applications of the HTT model it is more important to have approximate estimates for many species rather than exact values for only a few species. We suggest that minimum temperature and variation of minimum moisture can be estimated from literature data and expert knowledge. This allows to derive hydrothermal time and minimum moisture from existing data from germination experiments with one level of temperature and moisture. We applied our approach to a germination experiment comparing germination fractions of wild annual species along an aridity gradient in Israel. Using this simplified approach we estimated hydrothermal time and minimum moisture of 36 species. Comparison with exact data for three species shows that our method is a simple but effective method for obtaining parameters for the HTT model. Hydrothermal time and minimum moisture supposedly indicate climate related germination strategies. We tested whether these two parameters varied with the climate at the site where the seeds had been collected. We found no consistent variation with climate across species, suggesting that variation is more strongly controlled by site-specific factors.Abstract auch auf deutsch vorhanden:Keimungsgeschwindigkeit und Anteil gekeimter Samen lassen sich gut mit dem Hydrothermalzeit-Modell bestimmen. Dessen vier Parameter Hydrothermalzeit, Mindesttemperatur, Mindestbodenfeuchte und Streuung der Mindestbodenfeuchte müssen jedoch durch aufwendige Keimungsversuche bei Kombinationen von mehreren Temperatur- und Feuchtigkeitsstufen bestimmt werden. Für manche Anwendungen des Hydrothermalzeit-Modells sind aber ungefähre Werte für viele Arten wichtiger als genaue Werte für wenige Arten. Wenn die Mindesttemperatur und die Streuung der Mindestfeuchte aus Veröffentlichungen und Expertenwissen geschätzt würde, können die Hydrothermalzeit und Mindestbodenfeuchte aus vorhandenen Daten von Keimungsversuchen mit nur einer Temperatur- und Feuchtigkeitsstufe berechnet werden. Wir haben unseren Ansatz auf einen Keimungsversuch zum Vergleich der Keimungsquote wilder einjähriger Arten entlang eines Trockenheitsgradienten in Israel angewendet. Mit diesem Ansatz bestimmten wir die Hydrothermalzeit und Mindestfeuchtigkeit von 36 Arten. Der Vergleich mit genauen Werten für drei Arten zeigt, dass mit unserem Ansatz Hydrothermalzeit-Parameter einfach und effektiv bestimmt werden können. Hydrothermalzeit und Mindestfeuchtigkeit sollten auch bestimmte klimabedingte Keimungsstrategien anzeigen. Deshalb testeten wir, ob diese zwei Parameter mit dem Klima am Ursprungsort der Samen zusammenhängen. Wir fanden jedoch keinen für alle Arten übereinstimmenden Zusammenhang, so dass die Unterschiede vermutlich stärker durch standörtliche als durch klimatische Ursachen hervorgerufen werden. Y1 - 2007 UR - http://www.sciencedirect.com/science/journal/14391791 U6 - https://doi.org/10.1016/j.baae.2006.04.002 SN - 1439-1791 ER - TY - THES A1 - Hänsel, Ulrike T1 - The role of hemicelluloses in plant growth and development Y1 - 2007 CY - Potsdam ER - TY - JOUR A1 - Scheffler, Christiane A1 - Ketelhut, Kerstin A1 - Mohasseb, Iman T1 - Does physical education modify the body composition? - Results of a longitudinal study of pre-school children N2 - The aim of the study is the analysis of body composition, motor development and cardiovascular parameters of preschool-children. In 2001/2002 a longitudinal study started in 17 nursery schools in Berlin. A total of 160 children out of the 264 children participated in a regular exercise programme. After 24 months of training significant differences of body composition, motor skills and cardiovascular parameters between 5 complete year old children of the intervention and the control group were observed. The results show that such an exercise programme is successful as a preventive measure to decrease the risk of obesity. Y1 - 2007 ER - TY - JOUR A1 - Thiele, T. A1 - Jeltsch, Florian A1 - Blaum, Niels T1 - Importance of woody vegetation for foraging site selection in the Southern Pied Babbler (Turdoides bicolor) under two different land use regimes Y1 - 2008 SN - 0140-1963 ER - TY - JOUR A1 - Köchy, Martin T1 - Effects of simulated daily precipitation patterns on annual plant populations depend on life stage and climatic region N2 - Background To improve the understanding of consequences of climate change for annual plant communities, I used a detailed, grid-based model that simulates the effect of daily rainfall variability on individual plants in five climatic regions on a gradient from 100 to 800 mm mean annual precipitation (MAP). The model explicitly considers moisture storage in the soil. I manipulated daily rainfall variability by changing the daily mean rain (DMR, rain volume on rainy days averaged across years for each day of the year) by ± 20%. At the same time I adjusted intervals appropriately between rainy days for keeping the mean annual volume constant. In factorial combination with changing DMR I also changed MAP by ± 20%. Results Increasing MAP generally increased water availability, establishment, and peak shoot biomass. Increasing DMR increased the time that water was continuously available to plants in the upper 15 to 30 cm of the soil (longest wet period, LWP). The effect of DMR diminished with increasing humidity of the climate. An interaction between water availability and density-dependent germination increased the establishment of seedlings in the arid region, but in the more humid regions the establishment of seedlings decreased with increasing DMR. As plants matured, competition among individuals and their productivity increased, but the size of these effects decreased with the humidity of the regions. Therefore, peak shoot biomass generally increased with increasing DMR but the effect size diminished from the semiarid to the mesic Mediterranean region. Increasing DMR reduced via LWP the annual variability of biomass in the semiarid and dry Mediterranean regions. Conclusion More rainstorms (greater DMR) increased the recharge of soil water reservoirs in more arid sites with consequences for germination, establishment, productivity, and population persistence. The order of magnitudes of DMR and MAP overlapped partially so that their combined effect is important for projections of climate change effects on annual vegetation. Y1 - 2008 UR - http://www.biomedcentral.com/1472-6785/8/4 ER - TY - JOUR A1 - Köchy, Martin A1 - Mathaj, Martin A1 - Jeltsch, Florian A1 - Malkinson, Dan T1 - Resilience of stocking capacity to changing climate in arid to Mediterranean landscapes N2 - Small livestock is an important resource for rural human populations in dry climates. How strongly will climate change affect the capacity of the rangeland? We used hierarchical modelling to scale quantitatively the growth of shrubs and annual plants, the main food of sheep and goats, to the landscape extent in the eastern Mediterranean region. Without grazing, productivity increased in a sigmoid way with mean annual precipitation. Grazing reduced productivity more strongly the drier the landscape. At a point just under the stocking capacity of the vegetation, productivity declined precipitously with more intense grazing due to a lack of seed production of annuals. We repeated simulations with precipitation patterns projected by two contrasting IPCC scenarios. Compared to results based on historic patterns, productivity and stocking capacity did not differ in most cases. Thus, grazing intensity remains the stronger impact on landscape productivity in this dry region even in the future. Y1 - 2008 UR - http://www.springerlink.com/content/gj0567116q770036/ U6 - https://doi.org/10.1007/s10113-008-0048-6 ER - TY - THES A1 - Kahlau, Sabine T1 - Analysis of plastid gene expression in tomato: from the genome to the translatome Y1 - 2008 CY - Potsdam ER - TY - JOUR A1 - Koechy, Martin A1 - Brakenhielm, Sven T1 - Separation of effects of moderate N deposition from natural change in ground vegetation of forests and bogs N2 - The effect of moderate rates of nitrogen deposition on ground floor vegetation is poorly predicted by uncontrolled surveys or fertilization experiments using high rates of nitrogen (N) addition. We compared the temporal trends of ground floor vegetation in permanent plots with moderate (7-13 kg/ha/yr) and lower bulk N deposition (4-6 kg/ha/yr) in southern Sweden during 1982-1998. We examined whether trends differed between growth forms (vascular plants and bryophytes) and vegetation types (three types of coniferous forest, deciduous forest, and bog). Trends of site-standardized cover and richness varied among growth forms, vegetation types, and deposition regions. Cover in spruce forests decreased at the same rate with both moderate and low deposition. In pine forests cover decreased faster with moderate deposition and in bogs cover decreased faster with low deposition. Cover of bryophytes in spruce forests increased at the same rate with both moderate and low deposition. In pine forests cover decreased faster with moderate deposition and in bogs and deciduous forests there was a strong non-linear increase with moderate deposition. The trend of number of vascular plants was constant with moderate and decreased with low deposition. We found no trend in the number of bryophyte species. We propose that the decrease of cover and number with low deposition was related to normal ecosystem development (increased shading), suggesting that N deposition maintained or increased the competitiveness of some species in the moderate-deposition region. Deposition had no consistent negative effect on vegetation suggesting that it is less important than normal successional processes. Y1 - 2008 UR - http://dx.doi.org/10.1016/j.foreco.2007.11.039 U6 - https://doi.org/10.1016/j.foreco.2007.11.039 ER - TY - JOUR A1 - Sellrie, Frank A1 - Warsinke, Axel A1 - Micheel, Burkhard T1 - Homogeneous indirect fluorescence quenching immunoassay for the determination of low molecular weight substances JF - Analytical & bioanalytical chemistry N2 - This paper describes the principle of a homogeneous indirect fluorescence quenching immunoassay that uses monoclonal antibodies. It is a carrier-free assay system that is performed completely in solution. The assay system was established for the determination of a low molecular weight substance (hapten), the herbicide diuron, used as a model analyte. A fluorescein-monuron conjugate together with a fluorescence-quenching monoclonal anti-fluorescein antibody and an anti-analyte antibody (here an anti-diuron/monuron monoclonal antibody) were used as central components of the assay. The fluorescein-monuron conjugate can be bound either by the anti-fluorescein monoclonal antibody or by the anti-diuron/ monuron monoclonal antibody. Due to steric hindrance, binding of both antibodies to the conjugate was not possible at the same time. By selecting the antibody concentrations appropriately, a dynamic equilibrium can be established that permits the preferential binding of the anti-diuron/monuron antibody to the conjugate, which allows the fluorescein in the conjugate to fluoresce. This equilibrium can be easily altered by adding free analyte (diuron), which competes with the conjugate to bind to the anti-diuron/monuron antibody. A reduction of anti-diuron/monuron antibody binding to the conjugate results in an increase in the binding of the anti-fluorescein antibody, which leads to a decrease in the fluorescence of the conjugate. The fluorescence is therefore a direct indicator of the state of equilibrium of the system and thus also the presence of free unconjugated analyte. The determination of an analyte based on this test principle does not require any washing steps. After the test components are mixed, the dynamic equilibrium is rapidly reached and the results can be obtained in less than 5 min by measuring the fluorescence of the fluorescein. We used this test principle for the determination of diuron, which was demonstrated for concentrations of approximately 5 nM. Y1 - 2008 UR - http://www.springerlink.com/content/n7227875454216v7/ VL - 386 IS - 2 SP - 206 EP - 210 ER - TY - THES A1 - Sharma, Reeta T1 - Molecular genetic analysis of Bengal tiger (Panthera tigris tigres) population and its implication in conservation and wildlife forensics Y1 - 2008 CY - Potsdam ER - TY - JOUR A1 - Schlag, Peter M. A1 - Osterziel, Karl Joseph A1 - Özcelik, Cemil A1 - Scherneck, Siegfried A1 - Wenzel, Katrin A1 - Daskalow, Katjana A1 - Herse, Florian A1 - Seitz, Susanne A1 - Zacharias, Ute A1 - Schenk, Jörg A. A1 - Schulz, Herbert A1 - Hübner, Norbert A1 - Micheel, Burkhard T1 - The protein phosphatase 1 inhibitor KEPI is down regulated in breast cancer cell lines and tissues and involved in the regulation of the tumour suppressor EGR1 via the MEK-ERK pathway N2 - KEPI is a protein kinase C-potentiated inhibitory protein for type 1 Ser/Thr protein phosphatases. We found no or reduced expression of KEPI in breast cancer cell lines, breast tumors and metastases in comparison to normal breast cell lines and tissues, respectively. KEPI protein expression and ubiquitous localization was detected with a newly generated antibody. Ectopic KEPI expression in MCF7 breast cancer cells induced differential expression of 95 genes, including the up-regulation of the tumor suppressors EGR1 (early growth response 1) and PTEN (phosphatase and tensin homolog), which is regulated by EGR1. We further show that the up-regulation of EGR1 in MCF7/KEPI cells is mediated by MEK-ERK signaling. The inhibition of this pathway by the MEK inhibitor UO126 led to a strong decrease in EGR1 expression in MCF7/KEPI cells. These results reveal a novel role for KEPI in the regulation of the tumor suppressor gene EGR1 via activation of the MEK-ERK MAPK pathway. Y1 - 2008 UR - http://www.atypon-link.com/doi/abs/10.1515/BC.2007.062 ER - TY - THES A1 - Ruiz-Martinez, Maria T1 - Characterisation and engineering of lignocellulolytic enzymes from the soil bacterium Sorangium cellulosum Y1 - 2016 ER - TY - THES A1 - Geyer, Juliane T1 - Adapting biodiversity conservation management to climate change Y1 - 2016 ER - TY - THES A1 - Heinze, Johannes T1 - The impact of soil microbiota on plant species performance and diversity in semi-natural grasslands Y1 - 2016 ER - TY - THES A1 - Reichel, Victoria Eleonore T1 - Biomedical applications and multifunctional nanostructures based on magnetite nanoparticles synthesized in presence of biological additives Y1 - 2016 ER - TY - THES A1 - Onana Eloundou Epse Mbebi, Jeanne Marie T1 - Robustness and plasticity in chemical reaction networks Y1 - 2016 ER - TY - THES A1 - Fiedler, Dorothea T1 - Impact of Dissolved Organic Nitrogen on Freshwater Phytoplankton N2 - In freshwater sciences, nitrogen gained increasing attention in the past as an important resource potentially influencing phytoplankton growth and thus eutrophication. Most studies and all management approaches, however, are still restricted to dissolved inorganic nitrogen (DIN = nitrate + nitrite + ammonium) since dissolved organic nitrogen (DON) was considered to be refractory for most of the photoautotrophs. In the meantime this assumption has been disproved for all aquatic systems. While research on DON in marine ecosystems substantially increased, in freshwater a surprisingly small number of investigations has been carried out on DON utilization by phytoplankton or even the occurrence and seasonal development of total DON or its compounds in lakes. Therefore, our present knowledge on DON utilization by phytoplankton is often based on single species experiments using a sole, usually low molecular weight DON component, often in unnaturally high amounts mainly carried out with marine phytoplankton species. Thus, we know that some phytoplankton species can take up different DON fractions if they are available in high concentrations and as sole nitrogen source. This does not necessarily imply that phytoplankton would perform likewise in natural environments. In addition, it will be difficult to draw conclusions on the behavior of freshwater phytoplankton from experiments with marine phytoplankton since the nutrient regime in marine environments differs from that of freshwater. In the light of the parallel availability of inorganic and organic nitrogen species in natural freshwater ecosystems, several questions must be raised: "If inorganic nitrogen is available, would phytoplankton really rely on an organic nitrogen source? Could a connection be detected between the seasonal development of DON and changes in the phytoplankton community composition as found for inorganic nitrogen? And if we reduce the input of inorganic nitrogen in lakes and rivers would the importance of DON as nitrogen source for phytoplankton increase, counteracting all management efforts or even leading to undesired effects due to changes in phytoplankton physiology and biodiversity?" I experimentally addressed the questions whether those DON compounds differentially influence growth, physiology and composition of phytoplankton both as sole available nitrogen source and in combination with other nitrogen compounds. I hypothesized that all offered DON - compounds (urea, natural organic matter (NOM), dissolved free and combined amino acids (DFAA, DCAA)) could be utilized by phytoplankton at natural concentrations. However, I assumed that the availability would decrease with increasing compound complexity. I furthermore hypothesized that the occurrence of low DIN concentrations would not affect the utilization of DON negatively. The nitrogen source, whatsoever, would have an impact on phytoplankton physiology as well as community composition. To investigate these questions and assumptions I conducted bioassays with algae monocultures as well as phytoplankton communities testing the utilization of various DON compounds by several freshwater phytoplankton species. Especially the potential utilization of NOM, a complex DON compound mainly consisting of humic substances is of interest, since it is usually regarded to be refractory. In order to be able to use natural concentrations of DON - compounds for my experiments the concentration of total DON and some DON - compounds (urea, humic substances, heigh molecular weight substances) was assessed in Lake Müggelsee. All compounds were able to support algae growth in the low natural concentrations supplied. However, I found that the offered DON compounds differ in their availability to various algae species, both, as sole nitrogen source or in combination with low DIN concentrations. As expected, the availability decreased with increasing complexity of the nitrogen compound. Furthermore, I could show that changes in algal physiology (nitrogen storage, metabolism) occur depending on the utilized nitrogen source. Especially the secondary photosynthetic pigment composition, heterocyst frequency and C:N - ratio of the algae were affected. The uptake and usage of certain nitrogen compounds might be more costly, potentially resulting in those physiology changes. Whereas laboratory experiments with single species revealed strong effects of DON, algal responses to DON in a multi-species situation remain unclear. Experiments with phytoplankton communities from Lake Müggelsee revealed that the nitrogen pool composition does influence the phytoplankton community structure. The findings furthermore show that several species combined might utilize the supplied nitrogen completely different than monocultures in the laboratory. Thus, besides the actual ability of algae to use the offered nitrogen sources other factors, such as interspecific competition, may be of importance. I further investigated, if the results of the laboratory experiments, can be verified in the field. Here, I surveyed the seasonal development of several dissolved organic matter (DOM) components (urea, high molecular weight substances (HMWS), humic substances (HS)) and associated parameters (Specific UV-absorption (SUVA), C:N - ratio) in Lake Müggelsee between 2011 and 2013. Furthermore, data from the long term measurements series of Lake Müggelsee such as physical (temperature, light, pH, O2) and chemical parameters (nitrogen, phosphorous, silica, inorganic carbon), zooplankton and phytoplankton data were used to investigate how much of the variability of the phytoplankton composition in Lake Müggelsee can be explained by DON/DOM concentration and composition, relative to the other groups of explanatory variables. The results show that DON mainly consists of rather complex compounds such as humic substances and biopolymers (80 %) and that only slight seasonal trends are detectable. Using variance partitioning I could show, that the usually investigated nutrients (DIN, silica, inorganic carbon, phosphorous) and abiotic factors together explain most of the algae composition as was to be expected (57.1 % of modeled variance). However, DOM and the associated parameters uniquely explain 10.3 % of the variance and thus slightly more than zooplankton with 9.3 %. I could therefore prove, that the composition of DOM (nitrogen and carbon) is connected to the algae composition in an eutrophic lake such as Lake Müggelsee. DON - compounds such as urea, however, could not be correlated with the occurrence of specific phytoplankton species. Overall, the results of this study imply that DON can be a valuable nitrogen source for freshwater phytoplankton. DON is used by various species even when DIN is available in low concentrations. Through the reduction of DIN in lakes and rivers, the DON:DIN ratio might be changed, resulting even in an increased importance of DON as phytoplankton nitrogen source. My work suggests that not only N2-fixation but also DON utilization might compensate for reduced N - input. Changes from DIN to DON as main nitrogen source might also promote certain, potentially undesired algae species and influence the biodiversity of a limnic ecosystem through changes in the phytoplankton community structure. Thus, DON, especially urea, should be included in calculations concerning total available nitrogen and when determining nitrogen threshold values. Furthermore, the input-reduction of DON, for example from waste-water treatment plants should also be evaluated and the results of my thesis should find consideration when planning to reduce the nitrogen input in freshwater. N2 - Das Interesse an Stickstoff als potentielle Einflußgröße auf das Phytoplanktonwachstum und damit auch als Eutrophierungsfaktor hat in der Vergangenheit in der Limnologie stark zugenommen. Bisher ging man davon aus, das gelöster organischer Stickstoff (DON) für photoautotrophe Organismen refraktär, also nicht nutzbar ist. Dies führte dazu, dass der Großteil an Studien und Managementmaÿnahmen nur gelösten inorganischen Stickstoff (DIN = Nitrat + Nitrit + Ammonium) einbezieht. Mittlerweile wurde allerdings für alle aquatischen Systeme nachgewiesen, dass DON durchaus für Organismen verfügbar sein kann. Während die Forschung im marinen Bereich stark zugenommen hat, wurden in Binnengewässern nur sehr wenige Untersuchungen zur DON - Nutzung durch Phytoplankton oder auch nur das Vorkommen und die saisonale Entwicklung von DON oder seiner Komponenten durchgeführt. Dies resultiert darin, dass sich unser heutiges Wissen zur DON - Nutzung durch Pytoplankton hauptsächlich auf Experimente stützt, die mit einzelnen, überwiegend marinen Phytoplanktonarten und einer, üblicherweise niedermolekularen DON - Komponente in meist unnatürlich hohen Konzentrationen durchgeführt wurden. Demzufolge wissen wir nur, dass es einige Phytoplanktonarten gibt, die verschiedene DON - Fraktionen aufnehmen können, wenn sie in hohen Konzentrationen und als alleinige Stickstoffquelle vorliegen. Diese Ergebnisse spiegeln nicht das tatsächliche Verhalten von Phytoplankton in seiner natürlichen Umgebung wieder. Zudem ist es schwierig, von Experimenten mit marinen Phytoplanktonarten auf das Verhalten limnischer Phytoplankter zu schließen, da sich der Nährstoffhaushalt in marinen Systemen von dem in Binnengewässern stark unterscheidet. Im Hinblick auf die parallele Verfügbarkeit von inorganischem und organischem Stickstoff in natürlichen Binnengewässern stellen sich eine Vielzahl von Fragen: "Wie stark DON als Stickstoffquelle durch Phytoplankton genutzt wird, wenn auch inorganischer Stickstoff zur Verfügung steht. Gibt es eventuell eine Verbindung zwischen der saisonalen Entwicklung von DON und Änderungen in der Zusammensetzung der Phytoplanktongemeinschaft wie man es auch für inorganischen Stickstoff sowie andere biotische und abiotische Faktoren findet? Es ist bisher auch ungeklärt, ob durch eine Reduktion des Eintrags von inorganischem Stickstoff die Bedeutung von DON als Stickstoffquelle für Phytoplankton zunimmt. Würde so eventuell den Managmentmaßnahmen entgegengewirkt oder käme es zu ungewünschten Effekten durch Änderungen in Phytoplanktonphysiologie und Biodiversität?" Im Verlauf meiner Doktorarbeit habe ich mich mit einem Teil dieser offenen Fragen auseinandergesetzt. Meine Experimente dienten dazu herauszufinden, inwieweit sich verschiedene DON -Komponenten auf Wachstum, Physiologie und die Phytoplanktonzusammensetzung auswirken, wenn sie als einzige verfügbare Stickstoffquelle aber auch in Kombination mit anderen Stickstoffkomponenten zur Verfügung stehen. Hierbei stehen folgende Hypothesen und Annahmen im Vordergrund: a) alle angebotenen DON - Komponenten (Harnstoff, gelöste freie Aminosäuren (DFAA), gelöste gebundene Aminosäuren (DCAA) und natürliches organisches Material (NOM)) können in natürlicher Konzentration von Phytoplankton genutzt werden, b) die Verfügbarkeit nimmt mit zunehmender Komplexität des DON ab, c) geringe DIN - Konzentrationen haben keinen negativen Einfluss auf die Nutzung von DON durch das Phytoplankton, d) die Stickstoffquelle beeinflusst Phytoplanktonphysiologie sowie die Zusammensetzung der Phytoplanktongemeinschaft. Um mehr Informationen zur DON - Verfügbarkeit für Süßwasserphytoplankton zu erhalten, wurde zunächst die Nutzung verschiedener DON - Komponenten durch verschiedene Phytoplanktonspezies aus Binnengewässern sowie Phytoplanktongemeinschaften untersucht. Besonders die mögliche Nutzung von NOM, einer komplexen, hauptsächlich aus Huminstoffen bestehenden DON - Komponente war von Interesse, da sie überwiegend als refraktär eingeschätzt wird. Um die Verfügbarkeit diverser DON - Komponenten in natürlicher Konzentration zu testen, wurde zunächst die Konzentration von Gesamt - DON sowie einiger DON -Komponenten (Harnstoff, Huminstoffe, hochmolekulare Substanzen) im Müggelsee ermittelt. Alle DON - Komponenten ermöglichten ein Algenwachstum in der niedrigen natürlichen Konzentration, in der sie zur Verfügung gestellt wurden. Es konnte festgestellt werden, dass sich die unterschiedlichen DON - Komponenten in ihrer Verfügbarkeit für verschiedene Algenarten unterschieden, unabhängig davon, ob sie als alleinige Stickstoffquelle vorlagen oder in Kombination mit DIN in niedriger Konzentration. Wie erwartet nahm die Algenverfügbarkeit mit zunehmender Komplexität der Stickstoffkomponenten ab. Desweiteren konnte gezeigt werden, dass die verwendete Stickstoffquelle zu Änderungen in der Algenphysiologie (Metabolismus, Stickstoffspeicherung) führen kann. Vor allem die Zusammensetzung sekundärer Photosynthesepigmente, die Heterocystenhäufigkeit sowie das C:N - Verhältnis des Phytoplankton wurden beeinflusst. Auch wenn alle untersuchten Stickstoffquellen das Phytoplanktonwachstum ermöglichen, ist die Nutzung einiger Komponenten gegebenenfalls mit höheren Kosten z.B. für Transport, Aufschluß etc. verbunden, was wiederum in einer Änderungen der Phytoplanktonphysiologie resultieren kann. Während Experimente mit einzelnen Phytoplanktonarten im Labor starke Effekte von DON erkennen lassen, sind die Ergebnisse der Multi-Spezies-Versuche weniger eindeutig interpretierbar. Versuche mit Phytoplanktongemeinschaften aus dem Müggelsee zeigten, dass die Zusammensetzung des Stickstoffpools Auswirkungen auf die Struktur der Phytoplanktongemenschaft hat. Zudem nutzen verschiedene Arten zusammen den zur Verfügung gestellten Stickstoff anders, als Monokulturen im Labor. Demzufolge spielen neben der eigentlichen Fähigkeit der Algen, verschiedene Stickstoffkomponenten nutzen zu können noch andere Faktoren wie z.B. interspezifische Konkurrenz eine Rolle für die tatsächliche Nutzung im Gewässer. Im weiteren Teil meiner Doktorarbeit habe ich untersucht, inwieweit die Ergebnisse der Laborversuche im Feld verifiziert werden können. Dafür wurde die saisonale Entwicklung verschiedenen gelösten organischen Materials (DOM) (Harnstoff, hochmolekulare Substanzen (HMWS), Huminstoffe (HS)) und weitere assoziierte Parameter (spezifische UV-Absorption (SUVA), C:N - Verhältnis) im Müggelsee von 2011-2013 bestimmt. Desweiteren wurden Daten aus der Langzeitmessung vom Müggelsee verwendet, um herauszufinden, wieviel der Variabilität in der Phytoplanktonzusammensetzung im Müggelsee durch die DON / DOM Konzentration und Zusammensetzung erklärt werden, im Verhältnis zu den anderen potentiellen Einflussfaktoren. Hierzu zählen physikalische (Temperatur, Licht, pH, O2) und chemische Parameter (Stickstoff, Phosphor, Silikat, inorganischer Kohlenstoff), Zooplankton- und Phytoplanktondaten. Die Ergebnisse zeigen, dass sich DON hauptächlich aus komplexen Komponenten wie Huminstoffen und Biopolymeren (80 %) zusammensetzt und das nur ein geringer saisonaler Trend in der DON-Entwicklung festzustellen ist. Mittels Varianzpartitionierung konnte gezeigt werden, dass die üblicherweise untersuchten Nährstoffe (DIN, Silikat, inorganischer Kohlenstoff, Phosphor) und abiotische Faktoren zusammen den Großteil der Algenzusammensetzung erklären, wie zu erwarten war (57.1 %). DOM und die damit assoziierten Parameter konnten allein 10.3% der Varianz erklären und damit etwas mehr als Zooplankton, eine anerkannte Einflußgröße, mit 9.3%. Damit konnte gezeigt werden, dass auch die DOM - Zusammensetzung (Stickstoff und Kohlenstoff) als Einflussgröße der Algenzusammensetzung in einem eutrophen See wie dem Müggelsee berücksichtigt werden sollte. Zusammenfassend zeigen die Ergebnisse dieser Doktorarbeit, dass DON eine wichtige Stickstoffquelle für Phytoplankton aus Binnengewässern sein kann und von zahlreichen Arten genutzt wird, auch wenn DIN, zumindest in niedrigen Konzentrationen, verfügbar ist. Durch die Reduktion von DIN in Seen und Flüssen könnte es zu einer Änderung des DON / DIN - Verhältnisses kommen, was zu einer noch stärkeren Bedeutung von DON als Stickstoffquelle für Phytoplankton führen kann. Meine Arbeit legt nahe, dass nicht nur die N2 - Fixierung, sondern auch die Nutzung von DON eine Reduktion des Stickstoffeintrags kompensieren könnte. Ein Wechsel von DIN zu DON als Hauptstickstoffquelle für Phytoplankton fördert möglicherweise auch bestimmte unerwünschte Algenarten und beeinflusst die Biodiversität der Binnengewässer durch Änderungen in der Phytoplanktongemeinschaft. Aus diesen Gründen sollte DON, vor allem Harnstoff in Kalkulationen des gesamtverfögbaren Stickstoffs sowie bei der Ermittlung von Stickstoffgrenzwerten einbezogen werden. Bei der Planung von Maßnahmen zur Reduktion des Stickstoffeintrages in Binnengewässer zur Verbesserung der Wasserqualtät sollten die Ergebnisse dieser Doktorarbeit demzufolge in Betracht gezogen und auch eine Reduktion des DON - Eintrages, z. B. aus Klärwerken, erwogen werden. KW - DON KW - phytoplankton KW - natural organic matter KW - LC-OCD-OND Y1 - 2016 ER - TY - THES A1 - Knecht, Volker T1 - Modeling Biomolecular Association Y1 - 2017 ER - TY - JOUR A1 - Schmidt, Andreas A1 - Rabsch, Wolfgang A1 - Broeker, Nina K. A1 - Barbirz, Stefanie T1 - Bacteriophage tailspike protein based assay to monitor phase variable glucosylations in Salmonella O-antigens JF - BMC microbiology N2 - Background Non-typhoid Salmonella Typhimurium (S. Typhimurium) accounts for a high number of registered salmonellosis cases, and O-serotyping is one important tool for monitoring epidemiology and spread of the disease. Moreover, variations in glucosylated O-antigens are related to immunogenicity and spread in the host. However, classical autoagglutination tests combined with the analysis of specific genetic markers cannot always reliably register phase variable glucose modifications expressed on Salmonella O-antigens and additional tools to monitor O-antigen glucosylation phenotypes of S. Typhimurium would be desirable. Results We developed a test for the phase variable O-antigen glucosylation state of S. Typhimurium using the tailspike proteins (TSP) of Salmonella phages 9NA and P22. We used this ELISA like tailspike adsorption (ELITA) assay to analyze a library of 44 Salmonella strains. ELITA was successful in discriminating strains that carried glucose 1-6 linked to the galactose of O-polysaccharide backbone (serotype O1) from non-glucosylated strains. This was shown by O-antigen compositional analyses of the respective strains with mass spectrometry and capillary electrophoresis. The ELITA test worked rapidly in a microtiter plate format and was highly O-antigen specific. Moreover, TSP as probes could also detect glucosylated strains in flow cytometry and distinguish multiphasic cultures differing in their glucosylation state. Conclusions Tailspike proteins contain large binding sites with precisely defined specificities and are therefore promising tools to be included in serotyping procedures as rapid serotyping agents in addition to antibodies. In this study, 9NA and P22TSP as probes could specifically distinguish glucosylation phenotypes of Salmonella on microtiter plate assays and in flow cytometry. This opens the possibility for flow sorting of cell populations for subsequent genetic analyses or for monitoring phase variations during large scale O-antigen preparations necessary for vaccine production. KW - Salmonella Typhimurium KW - O-antigen KW - Tailspike protein KW - Bacteriophage KW - Phase variation KW - O-serotyping KW - Flow cytometry Y1 - 2016 U6 - https://doi.org/10.1186/s12866-016-0826-0 SN - 1471-2180 VL - 16 PB - BioMed Central CY - London ER - TY - THES A1 - Ebrahimian Motlagh, Saghar T1 - Functional characterization of stress-responsive transcription factors and their gene regulatory networks in Arabidopsis thaliana Y1 - 2016 ER - TY - THES A1 - Schöppler, Vanessa T1 - Material properties of Banksia follicles Y1 - 2016 ER - TY - THES A1 - Pellizzer, Tommaso T1 - A novel approach to identify plastidic factors for plastome genome incompatibility and evidence for the central involvement of the chloroplast in leaf shaping Y1 - 2016 ER - TY - THES A1 - Sauter, Jörg T1 - The molecular origin of plant cell wall swelling N2 - In dieser Arbeit werden die Eigenschaften von hydratisierten Hemicellulose Polysacchariden mittels Computersimulation untersucht. Die hohe Quellfähigkeit von Materialien die aus diesen Molekülen bestehen, erlaubt die Erzeugung von zielgerichteter Bewegung in Planzenmaterialien, ausschließlich gesteuert durch Wasseraufnahme. Um den molekularen Ursprung dieses Quellvermögens zu untersuchen wird, im Vergleich mit Experimenten, ein atomistisches Modell für Hemicellulose Polysaccharide entwickelt und getestet. Unter Verwendung dieses Modells werden Simulationen von kleinen Polysacchariden benutzt um die Wechselwirkungen mit Wasser, den Einfluss von Wasser auf die Konformationsfreiheit der Moleküle, und die Quellfähigkeit, quantifiziert durch den osmotischen Druck, zu verstehen. Es wird gezeigt, dass verzweigte und lineare Polysaccharide unterschiedliche Hydratisierungseingenschaften im Vergleich zu lineare Polysacchariden aufweisen. Um das Quellverhalten auf Längen- und Zeitskalen untersuchen zu können die über die Begrenzungen atomistischer Simulationen hinausgehen, wurde eine Prozedur entwickelt um übertragbare vergröberte Modelle herzuleiten. Die Übertragbarkeit der vegröberten Modelle wird gezeigt, sowohl über unterschiedliche Polysaccharidkonzentrationen als auch über unterschiedliche Polymerlängen. Daher erlaubt die Prozedur die Konstruktion von großen vergröberter Systemen ausgehend von kleinen atomistischen Referenzsystemen. Abschließend wird das vergröberte Modell verwendet um zu zeigen, dass lineare und verzweigte Polysaccharide ein unterschiedliches Quellverhalten aufweisen, wenn sie mit einem Wasserbad gekoppelt werden. N2 - In this Thesis, the properties of aqueous hemicellulose polysaccharides are investigated using computer simulations. The high swelling capacity of materials composed of these molecules allows the generation of directed motion in plant materials entirely controlled by water uptake. To explore the molecular origin of this swelling capacity, a computational model with atomistic resolution for hemicellulose polysaccharides is build and validated in comparison with experiments. Using this model, simulations of small polysaccharides are employed to gain an understanding of the interactions of these molecules with water, the influence of water on their conformational freedom, and the swelling capacity quantified in terms of osmotic pressure. It is revealed that the branched hemicellulose polysaccharides show different hydration characteristics compared to linear polysaccharides. To study swelling properties on length and time scales that exceed the limitations imposed by atomistic simulations, a procedure to obtain transferable coarse-grain models is developed. The transferability of the coarse-grain models over both different degrees of polymerization as well as different solute concentrations is demonstrated. Therefore, the procedure allows the construction of large coarse-grained systems based on small atomistic reference systems. Finally, the coarse-grain model is applied to demonstrate that linear and branched polysaccharides show a different swelling behavior when coupled to a water bath. Y1 - 2016 ER - TY - THES A1 - Hanke-Gogokhia, Christin T1 - Small GTPase ARL3-GTP is key molecule in transition zone formation and trafficking of ciliary cargo in mouse photoreceptors Y1 - 2016 ER - TY - THES A1 - Frieß, Fabian T1 - Shape-memory polymer micronetworks Y1 - 2016 ER - TY - THES A1 - Jöst, Jan Moritz Michael T1 - Broad leaves, narrow leaves or no leaves at all - a genetic and phenotypic dissection of barley leaf size mutants Y1 - 2016 ER - TY - THES A1 - Korkuć, Paula T1 - Spatial investigations of protein structures with regard to compound binding and post-translational modifications Y1 - 2016 ER - TY - THES A1 - Sokolowska, Ewelina Maria T1 - Implementation of a plasmodesmata gatekeeper system, and its effect on intercellular transport Y1 - 2016 ER - TY - JOUR A1 - Lah, Ljerka A1 - Trense, Daronja A1 - Benke, Harald A1 - Berggren, Per A1 - Gunnlaugsson, Þorvaldur A1 - Lockyer, Christina A1 - Öztürk, Ayaka A1 - Öztürk, Bayram A1 - Pawliczka, Iwona A1 - Roos, Anna A1 - Siebert, Ursula A1 - Skóra, Krzysztof A1 - Víkingsson, Gísli A1 - Tiedemann, Ralph T1 - Spatially Explicit Analysis of Genome-Wide SNPs Detects Subtle Population Structure in a Mobile Marine Mammal, the Harbor Porpoise JF - PLoS one N2 - The population structure of the highly mobile marine mammal, the harbor porpoise (Phocoena phocoena), in the Atlantic shelf waters follows a pattern of significant isolation-by-distance. The population structure of harbor porpoises from the Baltic Sea, which is connected with the North Sea through a series of basins separated by shallow underwater ridges, however, is more complex. Here, we investigated the population differentiation of harbor porpoises in European Seas with a special focus on the Baltic Sea and adjacent waters, using a population genomics approach. We used 2872 single nucleotide polymorphisms (SNPs), derived from double digest restriction-site associated DNA sequencing (ddRAD-seq), as well as 13 microsatellite loci and mitochondrial haplotypes for the same set of individuals. Spatial principal components analysis (sPCA), and Bayesian clustering on a subset of SNPs suggest three main groupings at the level of all studied regions: the Black Sea, the North Atlantic, and the Baltic Sea. Furthermore, we observed a distinct separation of the North Sea harbor porpoises from the Baltic Sea populations, and identified splits between porpoise populations within the Baltic Sea. We observed a notable distinction between the Belt Sea and the Inner Baltic Sea sub-regions. Improved delineation of harbor porpoise population assignments for the Baltic based on genomic evidence is important for conservation management of this endangered cetacean in threatened habitats, particularly in the Baltic Sea proper. In addition, we show that SNPs outperform microsatellite markers and demonstrate the utility of RAD-tags from a relatively small, opportunistically sampled cetacean sample set for population diversity and divergence analysis. Y1 - 2016 U6 - https://doi.org/10.1371/journal.pone.0162792 SN - 1932-6203 VL - 11 IS - 10 PB - PLoS CY - Lawrence, Kan. ER - TY - THES A1 - Wutke, Saskia T1 - Tracing Changes in Space and Time BT - Paternal Diversity and Phenotypic Traits during Horse Domestication N2 - The horse is a fascinating animal symbolizing power, beauty, strength and grace. Among all the animal species domesticated the horse had the largest impact on the course of human history due to its importance for warfare and transportation. Studying the process of horse domestication contributes to the knowledge about the history of horses and even of our own species. Research based on molecular methods has increasingly focused on the genetic basis of horse domestication. Mitochondrial DNA (mtDNA) analyses of modern and ancient horses detected immense maternal diversity, probably due to many mares that contributed to the domestic population. However, mtDNA does not provide an informative phylogeographic structure. In contrast, Y chromosome analyses displayed almost complete uniformity in modern stallions but relatively high diversity in a few ancient horses. Further molecular markers that seem to be well suited to infer the domestication history of horses or genetic and phenotypic changes during this process are loci associated with phenotypic traits. This doctoral thesis consists of three different parts for which I analyzed various single nucleotide polymorphisms (SNPs) associated with coat color, locomotion or Y chromosomal variation of horses. These SNPs were genotyped in 350 ancient horses from the Chalcolithic (5,000 BC) to the Middle Ages (11th century). The distribution of the samples ranges from China to the Iberian Peninsula and Iceland. By applying multiplexed next-generation sequencing (NGS) I sequenced short amplicons covering the relevant positions: i) eight coat-color-associated mutations in six genes to deduce the coat color phenotype; ii) the so-called ’Gait-keeper’ SNP in the DMRT3 gene to screen for the ability to amble; iii) 16 SNPs previously detected in ancient horses to infer the corresponding haplotype. Based on these data I investigated the occurrence and frequencies of alleles underlying the respective phenotypes as well as Y chromosome haplotypes at different times and regions. Also, selection coefficients for several Y chromosome lineages or phenotypes were estimated. Concerning coat color differences in ancient horses my work constitutes the most comprehensive study to date. I detected an increase of chestnut horses in the Middle Ages as well as differential selection for spotted and solid phenotypes over time which reflects changing human preferences. With regard to ambling horses, the corresponding allele was present in medieval English and Icelandic horses. Based on these results I argue that Norse settlers, who frequently invaded parts of Britain, brought ambling individuals to Iceland from the British Isles which can be regarded the origin of this trait. Moreover, these settlers appear to have selected for ambling in Icelandic horses. Relating to the third trait, the paternal diversity, these findings represent the largest ancient dataset of Y chromosome variation in non-humans. I proved the existence of several Y chromosome haplotypes in early domestic horses. The decline of Y chromosome variation coincides with the movement of nomadic peoples from the Eurasian steppes and later with different breeding practices in the Roman period. In conclusion, positive selection was estimated for several phenotypes/lineages in different regions or times which indicates that these were preferred by humans. Furthermore, I could successfully infer the distribution and dispersal of horses in association with human movements and actions. Thereby, a better understanding of the influence of people on the changing appearance and genetic diversity of domestic horses could be gained. My results also emphasize the close relationship of ancient genetics and archeology or history and that only in combination well-founded conclusions can be reached. KW - ancient DNA KW - domestication KW - horse KW - equus caballus KW - locomotion KW - Y chromosome KW - coat colour Y1 - 2016 ER - TY - THES A1 - Hofferek, Vinzenz T1 - Starvation response of Drosophila melanogaster BT - a Lipidomic Approach Y1 - 2016 ER - TY - THES A1 - Avcilar-Kucukgoze, Irem T1 - Effect of tRNA Aminoacylation and Cellular Resources Allocation on the Dynamics of Translation in Escherichia coli Y1 - 2016 ER - TY - THES A1 - Reil, Daniela T1 - Puumala hantavirus dynamics in bank voles: identification of environmental correlates to predict human infection risk Y1 - 2016 ER - TY - THES A1 - Bolger, Anthony T1 - Sequencing the Genome of the stress-tolerant wild tomato Solanum pennellii and Novel Algorithms motivated thereby Y1 - 2016 ER - TY - THES A1 - Zhu, Fangjun T1 - Gene evolution and expression patterns in the all-female fish Amazon molly: Poecilia formosa Y1 - 2016 ER - TY - THES A1 - Dotzek, Jana T1 - Mitochondria in the genus Oenothera - Non-Mendelian inheritance patterns, in vitro structure and evolutionary dynamics Y1 - 2016 ER - TY - THES A1 - Sas, Claudia T1 - Evolution of the selfing syndrome in the genus capsella BT - an investigation into floral UV absorption and scent emission Y1 - 2016 ER - TY - THES A1 - Kloß, Lena T1 - The link between genetic diversity and species diversity BT - patterns and processes in plants of agriculturally managed grassland Y1 - 2016 ER - TY - THES A1 - Hoffmann, Stefan T1 - In vivo Selection of Switchable DNA-Binding Proteins Y1 - 2016 ER - TY - THES A1 - Zhang, Youjun T1 - Investigation of the TCA cycle and glycolytic metabolons and their physiological impacts in plants Y1 - 2016 ER - TY - THES A1 - Löwenberg, Candy T1 - Shape-memory effect of gelatin-based hydrogels Y1 - 2016 ER - TY - THES A1 - Klauschies, Toni T1 - Revealing causes and consequences of functional diversity using trait-based models Y1 - 2016 ER - TY - THES A1 - Stief, Anna T1 - Genetics and ecology of plant heat stress memory Y1 - 2016 ER - TY - THES A1 - Beltran, Juan Camilo Moreno T1 - Characterization of the Clp protease complex and identification of putative substrates in N. tabacum Y1 - 2016 ER -