TY - JOUR A1 - Fischer, Petra A1 - Heinken, Thilo A1 - Meyer, Peter A1 - Schmidt, Marcus A1 - Waesch, Gunnar T1 - Zur Abgrenzung und Situation des FFH-Lebensraumtyps "Mitteleuropäische Flechten-Kiefernwälder" (91TO) in Deutschland N2 - Die in Deutschland gegenwärtig durch Nährstoffeinträge und ausbleibenden Nährstoffentzug stark im Rückgang begriffenen Flechten-Kiefernwälder werden als Biotoptyp wie auch als Lebensraumtyp "Mitteleuropäische Flechten-Kiefernwälder" (Code 91T0) diskutiert. Die bisherige, sehr uneinheitliche Differenzierung von Flechten-Kiefernwäldern auf der Ebene von Biotoptypen wird dargestellt. Auf der Grundlage neuerer vegetationskundlicher übersichten werden Vorschläge für eine einheitliche Abgrenzung des Biotoptyps "Flechten-Kiefernwald" und des Lebensraumtyps 91T0 unterbreitet. Im niedersächsischen Naturwaldreservat "Kaarßer Sandberge" (Niedersachsen) wurde die Anwendung des Konzeptes erfolgreich erprobt. Nicht nur hier, sondern auch deutschlandweit wird der Rückgang der Erdflechten in den Kieferwäldern zugunsten von Drahtschmiele und/ oder pleurokarpen Moosen deutlich. Nach der derzeitigen Definition des Lebensraumtyps 91T0 besteht auf der Grundlage der FFH-Richtlinie nicht für alle Flechten-Kiefernwälder eine Chance der Verbesserung. Der Ausschluss von außerhalb des natürlichen Verbreitungsgebietes der Wald-Kiefer gelegenen sowie von durch Aufforstung angepflanzten Beständen bringt Probleme mit sich, die diskutiert werden. Für den Erhalt und die Wiederherstellung der größtenteils nutzungsbedingt entstandenen Flechten-Kiefernwälder sind praktikable Pflegemaßnahmen notwendig, die im Rahmen von Streunutzungsversuchen erprobt werden müssen. Y1 - 2009 SN - 0028-0615 ER - TY - THES A1 - Itonaga, Naomi T1 - White storks (Ciconia ciconia) of Eastern Germany: age-dependent breeding ability, and age- and density-dependent effects on dispersal behavior T1 - Der Weißstorch (Ciconia ciconia) aus dem östlichen Deutschland: altersabhängiges Reproduktionsvermögen und alters- und bestandsdichteabhängiges Ausbreitungsverhalten N2 - Dispersal behavior plays an important role for the geographical distribution and population structure of any given species. Individual’s fitness, reproductive and competitive ability, and dispersal behavior can be determined by the age of the individual. Age-dependent as well as density-dependent dispersal patterns are common in many bird species. In this thesis, I first present age-dependent breeding ability and natal site fidelity in white storks (Ciconia ciconia); migratory birds breeding in large parts of Europe. I predicted that both the proportion of breeding birds and natal site fidelity increase with the age. After the seventies of the last century, following a steep population decline, a recovery of the white stork population has been observed in many regions in Europe. Increasing population density in the white stork population in Eastern Germany especially after 1983 allowed examining density- as well as age-dependent breeding dispersal patterns. Therefore second, I present whether: young birds show more often and longer breeding dispersal than old birds, and frequency of dispersal events increase with the population density increase, especially in the young storks. Third, I present age- and density-dependent dispersal direction preferences in the give population. I asked whether and how the major spring migration direction interacts with dispersal directions of white storks: in different age, and under different population densities. The proportion of breeding individuals increased in the first 22 years of life and then decreased suggesting, the senescent decay in aging storks. Young storks were more faithful to their natal sites than old storks probably due to their innate migratory direction and distance. Young storks dispersed more frequently than old storks in general, but not for longer distance. Proportion of dispersing individuals increased significantly with increasing population densities indicating, density- dependent dispersal behavior in white storks. Moreover, the finding of a significant interaction effects between the age of dispersing birds and year (1980–2006) suggesting, older birds dispersed more from their previous nest sites over time due to increased competition. Both young and old storks dispersed along their spring migration direction; however, directional preferences were different in young storks and old storks. Young storks tended to settle down before reaching their previous nest sites (leading to the south-eastward dispersal) while old birds tended to keep migrating along the migration direction after reaching their previous nest sites (leading to the north-westward dispersal). Cues triggering dispersal events may be age-dependent. Changes in the dispersal direction over time were observed. Dispersal direction became obscured during the second half of the observation period (1993–2006). Increase in competition may affect dispersal behavior in storks. I discuss the potential role of: age for the observed age-dependent dispersal behavior, and competition for the density dependent dispersal behavior. This Ph.D. thesis contributes significantly to the understanding of population structure and geographical distribution of white storks. Moreover, presented age- and density (competition)-dependent dispersal behavior helps understanding underpinning mechanisms of dispersal behavior in bird species. N2 - Das Verständnis der Mechanismen, die dem Ausbreitungsverhalten und der Wahl des Neststandorts zugrunde liegen, gibt wichtige Einsichten in Strukturen und Dynamiken von Tierpopulationen. Der Gesundheitszustand, die Produktivität und Konkurrenzfähigkeit sowie das Ausbreitungsverhalten eines Individuums können über das Alter ermittelt werden. Alters- und dichteabhängige Veränderungen in Verbreitungsmustern kommen bei vielen Vogelarten vor. In der vorliegenden Studie untersuchten wir zunächst den Effekt des Alters auf die Reproduktivität, auf die Wahl des Neststandorts sowie auf die Geburtsorttreue des Weißstorchs (Ciconia ciconia). Wir fragten, ob sowohl der Anteil der brütenden Individuen als auch die Geburtsorttreue mit dem Alter zunimmt. Weißstörche sind Zugvögel, die während der Migration zumeist segelnd die Thermik nutzen und in weiten Teilen Europas brüten. Nach einem starken Bestandsrückgang konnte in vielen Regionen Europas ab den 1970er Jahren wieder ein positiver Trend in der Populationsentwicklung beobachtet werden. Die zunehmende Populationsdichte, besonders nach 1983 in der ostziehenden Subpopulation in den fünf Bundesländern der ehemaligen DDR, erlaubte die Analyse von dichte- und altersabhängigen Präferenzen in der Richtung der Brutstandorte sowie in der Verbreitungsfrequenz und -distanz. Wir untersuchten zudem die Alters- und Dichteabhängigkeit der Ausbreitungsrichtung einer Teilpopulation. Wir fragten, ob und wie die Hauptzugrichtung im Frühjahr mit der Verbreitungsrichtung interagiert: Beeinflussen Alter und Populationsdichte die Ausbreitungsrichtung? Der Anteil der brütenden Individuen, die älter als 22 Jahre sind, nahm innerhalb der beobachteten Teilpopulation ab, vermutlich aufgrund einer altersbedingten Abnahme des Gesundheitszustands. Junge Vögel zeigten eine starke Geburtsorttreue, was auf eine genetische Komponente in den Zugmustern junger Störche hinweist. Generell trat bei jungen Störchen häufiger Ausbreitungsverhalten auf als bei älteren Störchen. Eine signifikante Zunahme der Ausbreitungsdistanz von Individuen über die Zeit lässt auf eine dichteabhängige Komponente im Ausbreitungsverhalten der Weißstörche schließen. Weiterhin wurde eine signifikante Interaktion zwischen dem Alter sich ausbreitender Individuen und dem betrachteten Jahr gefunden. Demzufolge breiteten sich alte Vögel über die Zeit über größere Distanzen aus, vermutlich um der ansteigenden Konkurrenz, bedingt durch den wachsenden Bestandsdruck, zu entgehen. KW - Weißstorch KW - Altersabhängigkeit KW - Dichteabhängigkeit KW - Ausbreitungsverhalten KW - Reproduktivität KW - White stork KW - age-dependent KW - density-dependent KW - dispersal behavior KW - breeding ability Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-39052 ER - TY - JOUR A1 - Dreyer, Ingo A1 - Blatt, Michael R. T1 - What makes a gate? : the ins and outs of Kv-like K+ channels in plants N2 - Gating of K+ and other ion channels is 'hard-wired' within the channel protein. So it remains a puzzle how closely related channels in plants can show an unusually diverse range of biophysical properties. Gating of these channels lies at the heart of K+ mineral nutrition, signalling, abiotic and biotic stress responses in plants. Thus, our knowledge of the molecular mechanics underpinning K+ channel gating will be important for rational engineering of related traits in agricultural crops. Several key studies have added significantly to our understanding of channel gating in plants and have challenged current thinking about analogous processes found in animal K+ channels. Such studies highlight how much of K+ channel gating remains to be explored in plants. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/13601385 U6 - https://doi.org/10.1016/j.tplants.2009.04.001 SN - 1360-1385 ER - TY - JOUR A1 - Riesch, Rüdiger A1 - Duwe, Virginia A1 - Herrmann, Nina A1 - Padur, Lisa A1 - Ramm, Annemarie A1 - Scharnweber, Inga Kristin A1 - Schulte, Matthias A1 - Schulz-Mirbach, Tanja A1 - Ziege, Madlen A1 - Plath, Martin T1 - Variation along the shy-bold continuum in extremophile fishes (Poecilia mexicana, Poecilia sulphuraria) N2 - One potential trade-off that bold individuals face is between increased predation risks and gains in resources. Individuals experiencing high predation and hungry individuals (or individuals with low body condition) are predicted to show increased boldness. We examined one behavioral trait previously reported to be associated with boldness (the time individual fish needed to emerge from shelter) in various populations of mollies (Poecilia spp.). Our study system included several southern Mexican surface streams with high piscine predation and high food availability, sulfidic surface streams with high avian predation, in which the inhabiting fish show reduced body condition, and a sulfidic cave, where predation and body condition are low. Our comparison revealed very short times to emerge from the start box in populations from non-sulfidic streams. In sulfidic habitats (whether surface or cave), it took individual Poecilia mexicana considerably longer to emerge from the start box, and the same difference was also found in an independent comparison between P. mexicana and the closely related, highly sulfide-adapted Poecilia sulphuraria. Fish reared under common garden conditions (in the absence of predators and hydrogen sulfide) showed intermediate boldness scores to the extremes observed in the field. Our data thus indicate that (a) boldness is shaped by environmental conditions/ experiential effects, but is not heritable, (b) predation affects boldness in the predicted direction, but (c) low body condition leads to reduced boldness. Extremophile Poecilia spp. spend most of their time surfacing to survive under sulfidic and hypoxic conditions, which exposes them to increased levels of predations, but the fish forage on the bottom. Hence, in this system, increased boldness does not increase foraging success. We argue that energy limitation favors reducing energetically costly behaviors, and exploring novel environments may be just one of them. Y1 - 2009 UR - http://www.springerlink.com/content/100464 U6 - https://doi.org/10.1007/s00265-009-0780-z SN - 0340-5443 ER - TY - GEN A1 - Voss, Martin A1 - Blenau, Wolfgang A1 - Walz, Bernd A1 - Baumann, Otto T1 - V-ATPase deactivation in blowfly salivary glands is mediated by protein phosphatase 2C N2 - The activity of vacuolar H+-ATPase (V-ATPase) in the apical membrane of blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT). 5-HT induces, via protein kinase A, the phosphorylation of V-ATPase subunit C and the assembly of V-ATPase holoenzymes. The protein phosphatase responsible for the dephosphorylation of subunit C and V-ATPase inactivation is not as yet known. We show here that inhibitors of protein phosphatases PP1 and PP2A (tautomycin, ocadaic acid) and PP2B (cyclosporin A, FK-506) do not prevent V-ATPase deactivation and dephosphorylation of subunit C. A decrease in the intracellular Mg2+ level caused by loading secretory cells with EDTA-AM leads to the activation of proton pumping in the absence of 5-HT, prolongs the 5-HT-induced response in proton pumping, and inhibits the dephosphorylation of subunit C. Thus, the deactivation of V-ATPase is most probably mediated by a protein phosphatase that is insensitive to okadaic acid and that requires Mg2+, namely, a member of the PP2C protein family. By molecular biological techniques, we demonstrate the expression of at least two PP2C protein family members in blowfly salivary glands. © 2009 Wiley Periodicals, Inc. KW - vacuolar H+-ATPase KW - assembly KW - regulation KW - protein phosphatise KW - dephosphorylation Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44360 ER - TY - JOUR A1 - Tittel, Joerg A1 - Wiehle, Ines A1 - Wannicke, Nicola A1 - Kampe, Heike A1 - Poerschmann, Juergen A1 - Meier, Jutta A1 - Kamjunke, Norbert T1 - Utilisation of terrestrial carbon by osmotrophic algae N2 - Terrestrial-derived dissolved organic carbon (DOC) contributes significantly to the energetic basis of many aquatic food webs. Although heterotrophic bacteria are generally considered to be the sole consumers of DOC, algae and cyanobacteria of various taxonomic groups are also capable of exploiting this resource. We tested the hypothesis that algae can utilise DOC in the presence of bacteria if organic resources are supplied in intervals by photolysis of recalcitrant DOC. In short-term uptake experiments, we changed irradiation in the range of minutes. As model substrates, polymers of radiolabelled coumaric acid (PCA) were used, which during photolysis are known to release aromatic compounds comparable to terrestrial-derived and refractory DOC. Three cultured freshwater algae readily assimilated PCA photoproducts equivalent to a biomass-specific uptake of 5-60% of the bacterial competitors present. Algal substrate acquisition did not depend on whether PCA was photolysed continuously or in intervals. However, the data show that photoproducts of terrestrial DOC can be a significant resource for osmotrophic algae. In long-term growth experiments, interval light was applied one hour per day. We allowed cultured Chlamydomonas to compete for ambient DOC of low concentration. We found higher abundances of Chlamydomonas when cultures were irradiated intermittently rather than continuously. These data suggest that photolysis of DOC supports algal heterotrophy, and potentially facilitates growth, when light fluctuations are large, as during the diurnal light cycle. We concluded that osmotrophic algae can efficiently convert terrestrial carbon into the biomass of larger organisms of aquatic food webs. Y1 - 2009 UR - http://www.springerlink.com/content/101191 U6 - https://doi.org/10.1007/s00027-008-8121-2 SN - 1015-1621 ER - TY - THES A1 - Apel, Wiebke T1 - Untersuchung und Veränderung der Genexpression und Proteinstabilität in Plastiden höherer Pflanzen Y1 - 2009 CY - Potsdam ER - TY - JOUR A1 - de Frenne, Pieter A1 - Kolb, Annette A1 - Verheyen, Kris A1 - Brunet, Johanne A1 - Chabrerie, Olivier A1 - Decocq, Guillaume A1 - Diekmann, Martin A1 - Eriksson, Ove A1 - Heinken, Thilo A1 - Hermy, Martin A1 - Jõgar, Ülle A1 - Stanton, Sara A1 - Quataert, Paul A1 - Zindel, Renate A1 - Zobel, Martin A1 - Graae, Bente Jessen T1 - Unravelling the effects of temperature, latitude and local environment on the reproduction of forest herbs N2 - Aim To investigate the effect of temperature, latitude and local environment on the reproductive traits of widespread perennial forest herbs to better understand the potential impacts of rising temperatures on their population dynamics and colonization capacities. Location Six regions along a latitudinal gradient from France to Sweden. Methods Within each region, we collected data from three to five populations of up to six species. For each species, several variables were recorded in each region (temperature, latitude) and population (local abiotic and biotic environmental variables), and seed production and germination were estimated. Resource investment in reproduction (RIR) was quantified as seed number ¥ seed mass, while germinable seed output (GSO) was expressed as seed number ¥ germination percentage.We performed linear regression and mixed effect models to investigate the effects of temperature (growing degree hours), latitude and local abiotic and biotic environment on RIR and GSO. Results Temperature and latitude explained most of the variation in RIR and GSO for early flowering species with a northerly distribution range edge (Anemone nemorosa, Paris quadrifolia and Oxalis acetosella). Reproduction of the more southerly distributed species (Brachypodium sylvaticum, Circaea lutetiana and Primula elatior), in contrast, was independent of temperature/latitude. In the late summer species, B. sylvaticum and C. lutetiana, variation in RIR and GSO was best explained by local environmental variables, while none of the investigated variables appeared to be related to reproduction in P. elatior. Main conclusions We showed that reproduction of only two early flowering, northerly distributed species was related to temperature. This suggests that the potential reproductive response of forest herbs to climate warming partly depends on their phenology and distribution, but also that the response is to some extent species dependent. These findings should be taken into account when predictions about future shifts in distribution range are made. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/118545893/home U6 - https://doi.org/10.1111/j.1466-8238.2009.00487.x SN - 1466-822X ER - TY - JOUR A1 - Kamjunke, Norbert A1 - Vogt, Bernhard A1 - Woelfl, Stefan T1 - Trophic interactions of the pelagic ciliate Stentor spp. in North Patagonian lakes N2 - The zooplankton of oligotrophic lakes in North Patagonia is often dominated by mixotrophic ciliates, particularly Stentor amethystinus and Stentor araucanus. Therefore, we tested whether Stentor spp. (i) is an important food for juvenile endemic (Cheirodon australe, Galaxias maculatus, Odontesthes mauleanum, Percichthys trucha) and introduced (Oncorhynchus mykiss) fish species, and (ii) represents a remarkable grazer of bacteria. Ingestion rates of fish estimated by disappearance of Stentor in feeding experiments ranged between 8 (G. maculatus) and 53 (C australe) ciliates per fish and day, and assimilation rates measured by using radioactively labelled Stentor ranged between 3 (P. trucha) and 52 (C australe) ciliates per fish and day. However, although we detected the consumption of Stentor by fish, the daily consumption amounted to at most 0.2% of the fish biomass which can not cover the energy requirement of the fish. Furthermore, the daily consumption was equivalent to a maximum of 1.6% of the Stentor standing stock so that fish predation does not seem to be an important mortality factor for the ciliates. The clearance rate of Stentor sp. on natural bacteria was on average 3.8 mu l cil(-1) h(-1). The daily ingestion (mean 3.9 ngC cil(-1) d(-1)) was about 3.5% of the individual biomass of Stentor sp. Therefore, bacteria ingestion might explain a ciliate growth rate of appr. 1% d(-1), which was about 17% of the photosynthesis of endosymbiotic algae. The maximum density of Stentor sp. in the take could ingest about 1 mu g C L-1 d(-1) bacteria which is only 3% of average bacterial production. Thus, grazing by Stentor sp. does not seem to be a main loss factor for the bacteria. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00759511 U6 - https://doi.org/10.1016/j.limno.2008.08.001 SN - 0075-9511 ER - TY - JOUR A1 - Scheller, Frieder W. T1 - Tribute to Guenter Gauglitz (Editorial) Y1 - 2009 UR - http://www.springerlink.com/content/100417 U6 - https://doi.org/10.1007/s00216-008-2548-0 SN - 1618-2642 ER - TY - JOUR A1 - Treydte, Anna C. A1 - Grant, Rina C. C. A1 - Jeltsch, Florian T1 - Tree size and herbivory determine below-canopy grass quality and species composition in savannahs N2 - Large single-standing trees are rapidly declining in savannahs, ecosystems supporting a high diversity of large herbivorous mammals. Savannah trees are important as they support both a unique flora and fauna. The herbaceous layer in particular responds to the structural and functional properties of a tree. As shrubland expands stem thickening occurs and large trees are replaced by smaller trees. Here we examine whether small trees are as effective in providing advantages for grasses growing beneath their crowns as large trees are. The role of herbivory in this positive tree- grass interaction is also investigated. We assessed soil and grass nutrient content, structural properties, and herbaceous species composition beneath trees of three size classes and under two grazing regimes in a South African savannah. We found that grass leaf content (N and P) beneath the crowns of particularly large (ca. 3.5 m) and very large trees (ca. 9 m) was as much as 40% greater than the same grass species not growing under a tree canopy, whereas nutrient contents of grasses did not differ beneath small trees (< 2.3 m). Moderate herbivory enhanced these effects slightly. Grass species composition differed beneath and beyond the tree canopy but not between tree size classes. As large trees significantly improve the grass nutrient quality for grazers in contrast to smaller trees, the decline of the former should be halted. The presence of trees further increases grass species diversity and patchiness by favouring shade- tolerant species. Both grazing wildlife and livestock will benefit from the presence of large trees because of their structural and functional importance for savannahs. Y1 - 2009 UR - http://www.springerlink.com/content/100125 U6 - https://doi.org/10.1007/s10531-009-9694-3 SN - 0960-3115 ER - TY - JOUR A1 - Zhang, Gong A1 - Hubalewska, Magdalena A1 - Ignatova, Zoya T1 - Transient ribosomal attenuation coordinates protein synthesis and co-translational folding N2 - Clustered codons that pair to low-abundance tRNA isoacceptors can form slow-translating regions in the mRNA and cause transient ribosomal arrest. We report that folding efficiency of the Escherichia coli multidomain protein Sufl can be severely perturbed by alterations in ribosome-mediated translational attenuation. Such alterations were achieved by global acceleration of the translation rate with tRNA excess in vitro or by synonymous substitutions to codons with highly abundant tRNAs both in vitro and in vivo. Conversely, the global slow-down of the translation rate modulated by low temperature suppresses the deleterious effect of the altered translational attenuation pattern. We propose that local discontinuous translation temporally separates the translation of segments of the peptide chain and actively coordinates their co-translational folding. Y1 - 2009 UR - http://www.nature.com/nsmb/ U6 - https://doi.org/10.1038/Nsmb.1554 SN - 1545-9985 ER - TY - THES A1 - Zhang, Gong T1 - Transient ribosomal attenuation as a generic mechanism to coordinate protein biosynthesis and biogenesis Y1 - 2009 CY - Potsdam ER - TY - THES A1 - Najafabadi, Masood Soltani T1 - Transcription factor networks in the initial ohase of drouht stress in rice (Oryza sativa L.) Y1 - 2009 CY - Potsdam ER - TY - THES A1 - Grimbs, Sergio T1 - Towards structure and dynamics of metabolic networks T1 - Struktur und Dynamik metabolischer Netzwerke N2 - This work presents mathematical and computational approaches to cover various aspects of metabolic network modelling, especially regarding the limited availability of detailed kinetic knowledge on reaction rates. It is shown that precise mathematical formulations of problems are needed i) to find appropriate and, if possible, efficient algorithms to solve them, and ii) to determine the quality of the found approximate solutions. Furthermore, some means are introduced to gain insights on dynamic properties of metabolic networks either directly from the network structure or by additionally incorporating steady-state information. Finally, an approach to identify key reactions in a metabolic networks is introduced, which helps to develop simple yet useful kinetic models. The rise of novel techniques renders genome sequencing increasingly fast and cheap. In the near future, this will allow to analyze biological networks not only for species but also for individuals. Hence, automatic reconstruction of metabolic networks provides itself as a means for evaluating this huge amount of experimental data. A mathematical formulation as an optimization problem is presented, taking into account existing knowledge and experimental data as well as the probabilistic predictions of various bioinformatical methods. The reconstructed networks are optimized for having large connected components of high accuracy, hence avoiding fragmentation into small isolated subnetworks. The usefulness of this formalism is exemplified on the reconstruction of the sucrose biosynthesis pathway in Chlamydomonas reinhardtii. The problem is shown to be computationally demanding and therefore necessitates efficient approximation algorithms. The problem of minimal nutrient requirements for genome-scale metabolic networks is analyzed. Given a metabolic network and a set of target metabolites, the inverse scope problem has as it objective determining a minimal set of metabolites that have to be provided in order to produce the target metabolites. These target metabolites might stem from experimental measurements and therefore are known to be produced by the metabolic network under study, or are given as the desired end-products of a biotechological application. The inverse scope problem is shown to be computationally hard to solve. However, I assume that the complexity strongly depends on the number of directed cycles within the metabolic network. This might guide the development of efficient approximation algorithms. Assuming mass-action kinetics, chemical reaction network theory (CRNT) allows for eliciting conclusions about multistability directly from the structure of metabolic networks. Although CRNT is based on mass-action kinetics originally, it is shown how to incorporate further reaction schemes by emulating molecular enzyme mechanisms. CRNT is used to compare several models of the Calvin cycle, which differ in size and level of abstraction. Definite results are obtained for small models, but the available set of theorems and algorithms provided by CRNT can not be applied to larger models due to the computational limitations of the currently available implementations of the provided algorithms. Given the stoichiometry of a metabolic network together with steady-state fluxes and concentrations, structural kinetic modelling allows to analyze the dynamic behavior of the metabolic network, even if the explicit rate equations are not known. In particular, this sampling approach is used to study the stabilizing effects of allosteric regulation in a model of human erythrocytes. Furthermore, the reactions of that model can be ranked according to their impact on stability of the steady state. The most important reactions in that respect are identified as hexokinase, phosphofructokinase and pyruvate kinase, which are known to be highly regulated and almost irreversible. Kinetic modelling approaches using standard rate equations are compared and evaluated against reference models for erythrocytes and hepatocytes. The results from this simplified kinetic models can simulate acceptably the temporal behavior for small changes around a given steady state, but fail to capture important characteristics for larger changes. The aforementioned approach to rank reactions according to their influence on stability is used to identify a small number of key reactions. These reactions are modelled in detail, including knowledge about allosteric regulation, while all other reactions were still described by simplified reaction rates. These so-called hybrid models can capture the characteristics of the reference models significantly better than the simplified models alone. The resulting hybrid models might serve as a good starting point for kinetic modelling of genome-scale metabolic networks, as they provide reasonable results in the absence of experimental data, regarding, for instance, allosteric regulations, for a vast majority of enzymatic reactions. N2 - In dieser Arbeit werden mathematische und informatische Ansätze zur Behandlung diverser Probleme im Zusammenhang mit der Modellierung metabolischer Netzwerke vorgestellt, insbesondere unter Berücksichtigung der eingeschränkten Verfügbarkeit detaillierter Enzymkinetiken. Es wird gezeigt, dass präzise mathematische Formulierungen der Probleme notwendig sind, um erstens angemessene und, falls möglich, effiziente Algorithmen zur Lösung zu entwickeln. Und zweitens, um die Güte der so gefundenen Lösungen zu bewerten. Des weiteren werden Methoden zur Analyse dynamischer Eigenschaften metabolischer Netzwerke eingeführt, welche entweder nur auf der Struktur der Netzwerke basieren oder zusätzlich noch Informationen über stationäre Zustände mit berücksichtigen. Außerdem wird eine Strategie zur Bestimmung von Schlüsselreaktionen eines Netzwerkes vorgestellt, welche die Entwicklung kinetischer Modelle vereinfacht. Der Erfolg neuer Technologien ermöglicht eine immer billigere und schnellere Sequenzierung des Genoms. Dies wird in naher Zukunft die Analyse biologischer Netzwerke nicht nur für Spezies, sondern auch für einzelne Individuen ermöglichen. Die automatische Rekonstruktion metabolischer Netzwerke ist bestens dafür geeignet, diese großen Datenmengen auszuwerten. Eine mathematische Formulierung der Rekonstruktion als Optimierungsproblem wird vorgestellt, die sowohl bereits vorhandenes Wissen als auch theoretische Vorhersagen verschiedenster bioinformatischer Methoden berücksichtigt. Die rekonstruierten Netzwerke sind hinsichtlich möglichst großer und plausibler Zusammenhangskomponenten hin optimiert, um fragmentierte und isolierte Teilnetzwerke zu vermeiden. Als Beispiel dient die Rekonstruktion der Saccharosesynthese in Chlamydomonas reinhardtii. Es wird gezeigt, dass das Problem sehr rechenintensiv ist und somit Approximationsalgorithmen erforderlich macht. Das 'inverse scope' Problem hat als Optimierungsziel, für ein gegebenes metabolisches Netzwerk die minimale Menge notwendiger Metabolite zu bestimmen, um eine ebenfalls gegebene Menge von gewünschten Zielmetaboliten zu produzieren. Diese Zielmetabolite können entweder durch experimentellen Messungen festgelegt werden, oder sie sind die gewünschten Endprodukte einer biotechnologischen Anwendung. Es wird gezeigt, dass das 'inverse scope' Problem rechenintensiv ist. Allerdings wird angenommen, dass die Berechnungskomplexität stark von der Anzahl gerichteter Zyklen innerhalb des metabolischen Netzwerkes abhängt. Dies könnte die Entwicklung effizienter Approximationsalgorithmen ermöglichen. Unter der Annahme von Massenwirkungskinetiken erlaubt es die 'chemical reaction network theory' (CRNT), anhand der Struktur metabolischer Netzwerke Rückschlüsse auf Multistabilität zu ziehen. Auch weitere Kinetiken können durch Modellierung von Enzymmechanismen mit berücksichtigt werden. CRNT wird zum Vergleich von mehreren Modellen des Calvinzyklus, welche sich in Größe und Abstraktionsniveau unterscheiden, verwendet. Obwohl für kleinere Modelle Ergebnisse erzielt werden, erlauben es die verfügbaren Theoreme und Algorithmen der CRNT nicht, Aussagen für größere Modelle zu machen, da die gegenwärtigen Implementierungen der Algorithmen an ihre Berechnungsgrenzen stoßen. Sind sowohl die Stoichiometrie eines metabolischen Netzwerkes, als auch die Metabolitkonzentrationen und Flüsse im stationären Zustand bekannt, so kann 'structural kinetic modelling' angewandt werden, um das dynamische Verhalten des Netzwerkes zu analysieren, selbst wenn die expliziten Ratengleichung unbekannt sind. Dieser Ansatz wird verwendet, um den stabilisierenden Einfluss allosterischer Regulation in menschlichen Erythrozyten zu untersuchen. Des weiteren werden die Reaktionen anhand ihrer Bedeutung hinsichtlich Stabilität im stationären Zustand angeordnet. Die wichtigsten Reaktionen bezüglich dieser Ordnung sind Hexokinase, Phosphofructokinase und Pyruvatkinase, welche bekanntermaßen stark reguliert und irreversibel sind. Kinetische Modelle, die auf generischen Ratengleichung beruhen, werden mit detaillierten Referenzmodellen für Erythrozyten und Hepatozyten verglichen. Die generischen Modelle simulieren das Verhalten nur in der Nähe eines gegebenen stationären Zustandes recht gut. Der zuvor erwähnte Ansatz, wichtige Reaktionen bezüglich Stabilität zu identifizieren, wird zur Bestimmung von Schlüsselreaktionen genutzt. Diese Schlüsselreaktionen werden im Detail modelliert, während für alle anderen Reaktionen weiterhin generische Ratengleichung verwendet werden. Die so entstandenen Hybridmodelle können das Verhalten des Referenzmodells signifikant besser beschreiben. Die Hybridmodelle können als Ausgangspunkt zur Erstellung genomweiter kinetischer Modelle dienen. KW - metabolische Netzwerke KW - Modellierung KW - Struktur KW - Dynamik KW - Bioinformatik KW - metabolic networks KW - modelling KW - structure KW - dynamics KW - bioinformatics Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-32397 ER - TY - JOUR A1 - Gliwicka, Marta A1 - Balazadeh, Salma A1 - Caldana, Camila A1 - Müller-Röber, Bernd A1 - Gaj, Malgorzata D. T1 - The use of multi-qPCR platform and tan1 mutant in identification of TF genes involved in somatic embryogenesis in Arabidopsis Y1 - 2009 UR - http://www.ib.uj.edu.pl/abc/index.php?d=06 SN - 0001-5296 ER - TY - JOUR A1 - Hejazi, Mahdi A1 - Fettke, Jörg A1 - Paris, Oskar A1 - Steup, Martin T1 - The two plastidial starch-related dikinases sequentially phosphorylate glucosyl residues at the surface of both the a- and b-type allomorphs of crystallized maltodextrins but the mode of action differs N2 - In this study, two crystallized maltodextrins were generated that consist of the same oligoglucan pattern but differ strikingly in the physical order of double helices. As revealed by x-ray diffraction, they represent the highly ordered A- and B-type allomorphs. Both crystallized maltodextrins were similar in size distribution and birefringence. They were used as model substrates to study the consecutive action of the two starch-related dikinases, the glucan, water dikinase and the phosphoglucan, water dikinase. The glucan, water dikinase and the phosphoglucan, water dikinase selectively esterify glucosyl residues in the C6 and C3 positions, respectively. Recombinant glucan, water dikinase phosphorylated both allomorphs with similar rates and caused complete glucan solubilization. Soluble neutral maltodextrins inhibited the glucan, water dikinase-mediated phosphorylation of crystalline particles. Recombinant phosphoglucan, water dikinase phosphorylated both the A- and B-type allomorphs only following a prephosphorylation by the glucan, water dikinase, and the activity increased with the extent of prephosphorylation. The action of the phosphoglucan, water dikinase on the prephosphorylated A- and B-type allomorphs differed. When acting on the B-type allomorph, by far more phosphoglucans were solubilized as compared with the A type. However, with both allomorphs, the phosphoglucan, water dikinase formed significant amounts of mono-phosphorylated phosphoglucans. Thus, the enzyme is capable of acting on neutral maltodextrins. It is concluded that the actual carbohydrate substrate of the phosphoglucan, water dikinase is defined by physical rather than by chemical parameters. A model is proposed that explains, at the molecular level, the consecutive action of the two starch-related dikinases. Y1 - 2009 UR - http://www.plantphysiol.org/ U6 - https://doi.org/10.1104/pp.109.138750 SN - 0032-0889 ER - TY - JOUR A1 - Naso, Alessia A1 - Dreyer, Ingo A1 - Pedemonte, Laura A1 - Testa, Ilaria A1 - Gomez-Porras, Judith Lucia A1 - Usai, Cesare A1 - Müller-Röber, Bernd A1 - Diaspro, Alberto A1 - Gambale, Franco A1 - Picco, Cristiana T1 - The role of the C-terminus for functional heteromerization of the plant channel KDC1 N2 - Voltage-gated potassium channels are formed by the assembly of four identical (homotetramer) or different (heterotetramer) subunits. Tetramerization of plant potassium channels involves the C-terminus of the protein. We investigated the role of the C-terminus of KDC1, a Shaker-like inward-rectifying K+ channel that does not form functional homomeric channels, but participates in the formation of heteromeric complexes with other potassium alpha- subunits when expressed in Xenopus oocytes. The interaction of KDC1 with KAT1 was investigated using the yeast two- hybrid system, fluorescence and electrophysiological studies. We found that the KDC1-EGFP fusion protein is not targeted to the plasma membrane of Xenopus oocytes unless it is coexpressed with KAT1. Deletion mutants revealed that the KDC1 C- terminus is involved in heteromerization. Two domains of the C-terminus, the region downstream the putative cyclic nucleotide binding domain and the distal part of the C-terminus called K-HA domain, contributed to a different extent to channel assembly. Whereas the first interacting region of the C-terminus was necessary for channel heteromerization, the removal of the distal KHA domain decreased but did not abolish the formation of heteromeric complexes. Similar results were obtained when coexpressing KDC1 with the KAT1-homolog KDC2 from carrots, thus indicating the physiological significance of the KAT1/KDC1 characterization. Electrophysiological experiments showed furthermore that the heteromerization capacity of KDC1 was negatively influenced by the presence of the enhanced green fluorescence protein fusion. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00063495 U6 - https://doi.org/10.1016/j.bpj.2009.02.055 SN - 0006-3495 ER - TY - THES A1 - Cruz Centeno, Danilo da T1 - The role of malate in the development of tomato fruit Y1 - 2009 CY - Potsdam ER - TY - THES A1 - Tschoep, Hendrik T1 - The response of growth and primary metabolism to a mild but sustained nitrogen limitation in arabidopsis thaliana Y1 - 2009 CY - Potsdam ER - TY - JOUR A1 - Walter, Juliane K. A1 - Rückert, Christine A1 - Voss, Martin A1 - Müller, Sebastian L. A1 - Piontek, Joerg A1 - Gast, Klaus A1 - Blasig, Ingolf E. T1 - The oligomerization of the coiled coil-domain of occluddin is redox sensitive N2 - The transmembrane tight junction protein occludin is sensitive to oxidative stress. Occludin oligomerizes; however, its function in the tight junction is unknown. The cytosolic C-terminal tail contains a coiled coil-domain and forms dimers contributing to the oligomerization. The regulation of the oligomerization remains unclear. As the domain area contains sulfhydryl residues, we tested the hypothesis that the dimerization of the coiled coil-domain depends on these residues. We showed that the dimerization is modulated by the thiol concentration in the low-millimolar range, which is relevant both for physiological and pathophysiological conditions. Masking the sulfhydryl residues in the fragment by covalent binding of 4-vinyl pyridine prevented the dimerization but did not affect its helical structure and cylindric shape. The data demonstrate, for the first time, that disulfide bridge formation of murine cystein 408 is involved in the dimerization. This process is redox-sensitive but the secondary structure of the domain is not. It is concluded that the dimerization of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0077-8923 U6 - https://doi.org/10.1111/j.1749-6632.2009.04058.x SN - 0077-8923 ER - TY - JOUR A1 - Blaum, Niels A1 - Tietjen, Britta A1 - Rossmanith, Eva T1 - The impact of livestock husbandry on small- and medium-sized carnivores in Kalahari savannah rangelands N2 - We analyzed relative sensitivities of small- and medium-sized carnivores to livestock husbandry (stocking rates and predator control) in Kalahari, South Africa, rangelands at a regional scale. We monitored small carnivores using track counts on 22 Kalahari farms across a land-use gradient ranging from low to high stocking rates and also interviewed each farm manager to identify farmers" perception of small carnivores as potential predators for livestock. We recorded 12 species of small- and medium-sized carnivores across 22 Kalahari farms. Stocking rate was the most important driving variable for local carnivore abundance. Abundance of all species was lowest on farms where stocking rate was high. Most farm managers perceived medium-sized carnivores, in particular, African wildcat (Felis silvestris lybica), black-backed jackal (Canis mesomelas), and caracal (Caracal caracal), as potential predators of livestock. Multiple regression analysis shows that black-backed jackal, African wildcat, and caracal were negatively affected by predator control measures, whereas bat-eared fox (Otocyon megalotis), cape fox (Vulpes chama), and small-spotted genet (Genetta genetta) were positively affected. Our results show a need for expanding research and conservation activities toward small- and medium-sized carnivores in southern African savannah rangelands. We, therefore, suggest developing a monitoring program combining passive tracking with indigenous knowledge of local Khoisan Bushmen to monitor carnivore populations, and we recommend additional predator removal experiments that manipulate predator densities. Y1 - 2009 UR - http://www.wildlifejournals.org/perlserv/?request=index-html&ct=1 U6 - https://doi.org/10.2193/2008-034 SN - 0022-541X ER - TY - GEN A1 - Schröder, Florian A1 - Lisso, Janina A1 - Lange, Peggy A1 - Müssig, Carsten T1 - The extracellular EXO protein mediates cell expansion in Arabidopsis leaves N2 - Background: The EXO (EXORDIUM) gene was identified as a potential mediator of brassinosteroid (BR)-promoted growth. It is part of a gene family with eight members in Arabidopsis. EXO gene expression is under control of BR, and EXO overexpression promotes shoot and root growth. In this study, the consequences of loss of EXO function are described. Results: The exo loss of function mutant showed diminished leaf and root growth and reduced biomass production. Light and scanning electron microscopy analyses revealed that impaired leaf growth is due to reduced cell expansion. Epidermis, palisade, and spongy parenchyma cells were smaller in comparison to the wild-type. The exo mutant showed reduced brassinolide-induced cotyledon and hypocotyl growth. In contrast, exo roots were significantly more sensitive to the inhibitory effect of synthetic brassinolide. Apart from reduced growth, exo did not show severe morphological abnormalities. Gene expression analyses of leaf material identified genes that showed robust EXO-dependent expression. Growth-related genes such as WAK1, EXP5, and KCS1, and genes involved in primary and secondary metabolism showed weaker expression in exo than in wild-type plants. However, the vast majority of BR-regulated genes were normally expressed in exo. HA- and GFP-tagged EXO proteins were targeted to the apoplast. Conclusion: The EXO gene is essential for cell expansion in leaves. Gene expression patterns and growth assays suggest that EXO mediates BR-induced leaf growth. However, EXO does not control BR-levels or BR-sensitivity in the shoot. EXO presumably is involved in a signalling process which coordinates BR-responses with environmental or developmental signals. The hypersensitivity of exo roots to BR suggests that EXO plays a diverse role in the control of BR responses in the root. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 139 KW - Plant transformation KW - Gene expression KW - Wall proteins KW - Thaliana KW - Brassinosteroids Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-45107 ER - TY - JOUR A1 - Mustin, Karen A1 - Benton, Tim G. A1 - Dytham, Calvin A1 - Travis, Justin M. J. T1 - The dynamics of climate-induced range shifting : perspectives from simulation modelling N2 - Predicted future climate change will alter species' distributions as they attempt to track the most suitable 'climate window'. Climate envelope models indicate the direction of likely range changes but do not incorporate population dynamics, therefore observed responses may differ greatly from these projections. We use simulation modelling to explore the consequences of a period of environmental change for a species structured across an environmental gradient. Results indicate that a species' range may lag behind its climate envelope and demonstrate that the rate of movement of a range can accelerate during a period of climate change. We conclude that the inclusion of both population dynamics and spatial environmental variability is vital to develop models that can both predict, and be used to manage, the impact of changing climate on species' biogeography. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0030-1299 U6 - https://doi.org/10.1111/j.1600-0706.2008.17025.x SN - 0030-1299 ER - TY - JOUR A1 - Song, Hui A1 - Bergstrasser, Claudia A1 - Rafat, Neysan A1 - Hoeger, Simone A1 - Schmidt, Marc A1 - Endres, N. A1 - Goebeler, Matthias A1 - Hillebrands, Jan-Luuk A1 - Brigelius-Flohé, Regina A1 - Banning, Antje A1 - Beck, Grietje A1 - Loesel, Ralf A1 - Yard, Benito A. T1 - The carbon monoxide releasing molecule (CORM-3) inhibits expression of vascular cell adhesion molecule-1 and E- selectin independently of haem oxygenase-1 expression N2 - Background and purpose: Although carbon monoxide (CO) can modulate inflammatory processes, the influence of CO on adhesion molecules is less clear. This might be due to the limited amount of CO generated by haem degradation. We therefore tested the ability of a CO releasing molecule (CORM-3), used in supra-physiological concentrations, to modulate the expression of vascular cell adhesion molecule (VCAM)-1 and E-selectin on endothelial cells and the mechanism(s) involved. Experimental approach: Human umbilical vein endothelial cells (HUVECs) were stimulated with tumour necrosis factor (TNF)-alpha in the presence or absence of CORM-3. The influence of CORM-3 on VCAM-1 and E- selectin expression and the nuclear factor (NF)-kappa B pathway was assessed by flow cytometry, Western blotting and electrophoretic mobility shift assay. Key results: CORM-3 inhibited the expression of VCAM-1 and E-selectin on TNF-alpha- stimulated HUVEC. VCAM-1 expression was also inhibited when CORM-3 was added 24 h after TNF-alpha stimulation or when TNF-alpha was removed. This was paralleled by deactivation of NF-kappa B and a reduction in VCAM-1 mRNA. Although TNF- alpha removal was more effective in this regard, VCAM-1 protein was down-regulated more rapidly when CORM-3 was added. CORM-3 induced haem oxygenase-1 (HO-1) in a dose- and time-dependent manner, mediated by the transcription factor, Nrf2. CORM-3 was still able to down-regulate VCAM-1 expression in HUVEC transfected with siRNA for HO-1 or Nrf2. Conclusions and implications: Down-regulation of VCAM and E-selectin expression induced by CORM-3 was independent of HO-1 up- regulation and was predominantly due to inhibition of sustained NF-kappa B activation. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/121548564/home U6 - https://doi.org/10.1111/j.1476-5381.2009.00215.x SN - 0007-1188 ER - TY - JOUR A1 - Braun, Uwe A1 - Kummer, Volker A1 - Xu, B. T1 - Taxonomy and nomenclature of powdery mildew fungi : erysiphe asclepiadis, E. robiniicola and Golovinomyces caulicola N2 - The new species Erysiphe asclepiadis is described, illustrated and discussed. A new Chinese collection of Erysiphe robiniicola has recently been found that can be used to elucidate and discuss the confused taxonomy and nomenclature of this species and other taxa of Erysiphe s. lat. on Robinia spp. Based on a re-examination of type material in connection with the data given in the protologue, it can be shown that Capnodium lygodesmiae must be reduced to synonymy with Ampelomyces quisqualis. The confusion surrounding the name C. lygodesmiae, caused by the occurrence of the hyperparasite A. quisqualis on a powdery mildew fungus with abundant chasmothecia, is discussed in detail. The new combination, Golovinomyces caulicola (; Spolverinia caulicola), is proposed for the powdery mildew that serves as host of C. lygodesmiae. Y1 - 2009 ER - TY - JOUR A1 - Reiss, Edda A1 - Hoelzel, Ralph A1 - Bier, Frank Fabian T1 - Synthesis and stretching of rolling circle amplification products in a flow-through system N2 - Enzymatic isothermal rolling circle amplification (RCA) produces long concatemeric single-stranded DNA (ssDNA) molecules if a small circular ssDNA molecule is applied as the template. A method is presented here in which the RCA reaction is carried out in a flow-through system, starting from isolated surface-tethered DNA primers. This approach combines gentle fluidic handling of the single-stranded RCA products, such as staining or stretching via a receding meniscus, with the option of simultaneous (fluorescence) microscopic observation. It is shown that the stretched and surface-attached RCA products are accessible for hybridization of complementary oligonucleotides, which demonstrates their addressability by complementary base pairing. The long RCA products should be well suited to bridge the gap between biomolecular nanoscale building-blocks and structures at the micro- and macroscale, especially at the single- molecule level presented here. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/107640323 U6 - https://doi.org/10.1002/smll.200900319 SN - 1613-6810 ER - TY - THES A1 - Roohi, Farnoosh T1 - Synthesis and evaluation of thermo-responsive stationary phases for high performance liquid chromatography (HPLC) Y1 - 2009 CY - Potsdam ER - TY - THES A1 - Yadav, Umesh Prasad T1 - Sucrose and trehalose-6-phosphate signalling in "Arabidopsis thaliana" Y1 - 2009 CY - Potsdam ER - TY - JOUR A1 - Voss, Martin A1 - Schmidt, Ruth A1 - Walz, Bernd A1 - Baumann, Otto T1 - Stimulus-induced translocation of the protein kinase A catalytic subunit to the apical membrane in blowfly salivary glands N2 - Secretion in blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT), which activates the InsP(3)/Ca2+ pathway and the cAMP/protein kinase A (PKA) pathway in the secretory cells. The latter signaling cascade induces the activation of a vacuolar H+-ATPase on the apical membrane. Here, we have determined the distribution of PKA by using antibodies against the PKA regulatory subunit-II (PKA-RII) and the PKA catalytic subunit (PKA-C) of Drosophila. PKA is present in high concentrations within the secretory cells. PKA-RII and PKA-C co-distribute in non-stimulated glands, being enriched in the basal portion of the secretory cells. Exposure to 8-CPT-cAMP or 5-HT induces the translocation of PKA-C to the apical membrane, whereas the PKA-RII distribution remains unchanged. The recruitment of PKA-C to the apical membrane corroborates our hypothesis that vacuolar H+-ATPase, which is enriched in this membrane domain, is a target protein for PKA. Y1 - 2009 UR - http://www.springerlink.com/content/100524 U6 - https://doi.org/10.1007/s00441-008-0673-x SN - 0302-766X ER - TY - JOUR A1 - Zurell, Damaris A1 - Jeltsch, Florian A1 - Dormann, Carsten F. A1 - Schröder-Esselbach, Boris T1 - Static species distribution models in dynamically changing systems : how good can predictions really be? N2 - SDM performance varied for different range dynamics. Prediction accuracies decreased when abrupt range shifts occurred as species were outpaced by the rate of climate change, and increased again when a new equilibrium situation was realised. When ranges contracted, prediction accuracies increased as the absences were predicted well. Far- dispersing species were faster in tracking climate change, and were predicted more accurately by SDMs than short- dispersing species. BRTs mostly outperformed GLMs. The presence of a predator, and the inclusion of its incidence as an environmental predictor, made BRTs and GLMs perform similarly. Results are discussed in light of other studies dealing with effects of ecological traits and processes on SDM performance. Perspectives are given on further advancements of SDMs and for possible interfaces with more mechanistic approaches in order to improve predictions under environmental change. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/117966123/home?CRETRY=1&SRETRY=0 U6 - https://doi.org/10.1111/j.1600-0587.2009.05810.x SN - 0906-7590 ER - TY - JOUR A1 - Koetting, Oliver A1 - Santelia, Diana A1 - Edner, Christoph A1 - Eicke, Simona A1 - Marthaler, Tina A1 - Gentry, Matthew S. A1 - Comparot-Moss, Sylviane A1 - Chen, Jychian A1 - Smith, Alison M. A1 - Steup, Martin A1 - Ritte, Gerhard A1 - Zeeman, Samuel C. T1 - STARCH-EXCESS4 is a laforin-like phosphoglucan phosphatase required for starch degradation in Arabidopsis thaliana N2 - Starch is the major storage carbohydrate in plants. It is comprised of glucans that form semicrystalline granules. Glucan phosphorylation is a prerequisite for normal starch breakdown, but phosphoglucan metabolism is not understood. A putative protein phosphatase encoded at the Starch Excess 4 (SEX4) locus of Arabidopsis thaliana was recently shown to be required for normal starch breakdown. Here, we show that SEX4 is a phosphoglucan phosphatase in vivo and define its role within the starch degradation pathway. SEX4 dephosphorylates both the starch granule surface and soluble phosphoglucans in vitro, and sex4 null mutants accumulate phosphorylated intermediates of starch breakdown. These compounds are linear alpha-1,4-glucans esterified with one or two phosphate groups. They are released from starch granules by the glucan hydrolases alpha-amylase and isoamylase. In vitro experiments show that the rate of starch granule degradation is increased upon simultaneous phosphorylation and dephosphorylation of starch. We propose that glucan phosphorylating enzymes and phosphoglucan phosphatases work in synergy with glucan hydrolases to mediate efficient starch catabolism. Y1 - 2009 UR - http://www.plantcell.org/ U6 - https://doi.org/10.1105/tpc.108.064360 SN - 1040-4651 ER - TY - JOUR A1 - Rathore, R. S. A1 - Garg, Neha A1 - Garg, Sarika T1 - Starch phosphorylase : role in starch metabolism and biotechnological applications N2 - The alpha-glucan phosphorylases of the glycosyltransferase family are important enzymes of carbohydrate metabolism in prokaryotes and eukaryotes. The plant a-glucan phosphorylase, commonly called starch phosphorylase (EC 2.4.1.1), is largely known for the phosphorolytic degradation of starch. Starch phosphorylase catalyzes the reversible transfer of glucosyl units from glucose-1-phosphate to the nonreducing end of alpha-1,4-D-glucan chains with the release of phosphate. Two distinct forms of starch phosphorylase, plastidic phosphorylase and cytosolic phosphorylase, have been consistently observed in higher plants. Starch phosphorylase is industrially useful and a preferred enzyme among all glucan phosphorylases for phosphorolytic reactions for the production of glucose-1-phosphate and for the development of engineered varieties of glucans and starch. Despite several investigations, the precise functional mechanisms of its characteristic multiple forms and the structural details are still eluding us. Recent discoveries have shed some light on their physiological substrates, precise biological functions, and regulatory aspects. in this review, we have highlighted important developments in understanding the role of starch phosphorylases and their emerging applications in industry. Y1 - 2009 UR - http://www.ingentaconnect.com/content/07388551 U6 - https://doi.org/10.1080/07388550902926063 SN - 0738-8551 ER - TY - JOUR A1 - Sulpice, Ronan A1 - Pyl, Eva-Theresa A1 - Ishihara, Hirofumi A1 - Trenkamp, Sandra A1 - Steinfath, Matthias A1 - Witucka-Wall, Hanna A1 - Gibon, Yves A1 - Usadel, Björn A1 - Poree, Fabien A1 - Piques, Maria Conceicao A1 - von Korff, Maria A1 - Steinhauser, Marie Caroline A1 - Keurentjes, Joost J. B. A1 - Guenther, Manuela A1 - Hoehne, Melanie A1 - Selbig, Joachim A1 - Fernie, Alisdair R. A1 - Altmann, Thomas A1 - Stitt, Mark T1 - Starch as a major integrator in the regulation of plant growth N2 - Rising demand for food and bioenergy makes it imperative to breed for increased crop yield. Vegetative plant growth could be driven by resource acquisition or developmental programs. Metabolite profiling in 94 Arabidopsis accessions revealed that biomass correlates negatively with many metabolites, especially starch. Starch accumulates in the light and is degraded at night to provide a sustained supply of carbon for growth. Multivariate analysis revealed that starch is an integrator of the overall metabolic response. We hypothesized that this reflects variation in a regulatory network that balances growth with the carbon supply. Transcript profiling in 21 accessions revealed coordinated changes of transcripts of more than 70 carbon-regulated genes and identified 2 genes (myo-inositol-1- phosphate synthase, a Kelch-domain protein) whose transcripts correlate with biomass. The impact of allelic variation at these 2 loci was shown by association mapping, identifying them as candidate lead genes with the potential to increase biomass production. Y1 - 2009 UR - http://www.pnas.org/ U6 - https://doi.org/10.1073/pnas.0903478106 SN - 0027-8424 ER - TY - GEN A1 - Szymanski, Jedrzej A1 - Jozefczuk, Szymon A1 - Nikoloski, Zoran A1 - Selbig, Joachim A1 - Nikiforova, Victoria A1 - Catchpole, Gareth A1 - Willmitzer, Lothar T1 - Stability of metabolic correlations under changing environmental conditions in Escherichia coli : a systems approach N2 - Background: Biological systems adapt to changing environments by reorganizing their cellula r and physiological program with metabolites representing one important response level. Different stresses lead to both conserved and specific responses on the metabolite level which should be reflected in the underl ying metabolic network. Methodology/Principal Findings: Starting from experimental data obtained by a GC-MS based high-throughput metabolic profiling technology we here develop an approach that: (1) extracts network representations from metabolic conditiondependent data by using pairwise correlations, (2) determines the sets of stable and condition-dependent correlations based on a combination of statistical significance and homogeneity tests, and (3) can identify metabolites related to the stress response, which goes beyond simple ob servation s about the changes of metabolic concentrations. The approach was tested with Escherichia colias a model organism observed under four different environmental stress conditions (cold stress, heat stress, oxidative stress, lactose diau xie) and control unperturbed conditions. By constructing the stable network component, which displays a scale free topology and small-world characteristics, we demonstrated that: (1) metabolite hubs in this reconstructed correlation networks are significantly enriched for those contained in biochemical networks such as EcoCyc, (2) particular components of the stable network are enriched for functionally related biochemical path ways, and (3) ind ependently of the response scale, based on their importance in the reorganization of the cor relation network a set of metabolites can be identified which represent hypothetical candidates for adjusting to a stress-specific response. Conclusions/Significance: Network-based tools allowed the identification of stress-dependent and general metabolic correlation networks. This correlation-network-ba sed approach does not rely on major changes in concentration to identify metabolites important for st ress adaptation, but rather on the changes in network properties with respect to metabolites. This should represent a useful complementary technique in addition to more classical approaches. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 147 KW - Small-world networks KW - saccharomyces-cerevisiae KW - trehalose synthesis KW - gene-expression KW - stress-response Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-45253 ER - TY - JOUR A1 - Wiethaus, Jessica A1 - Mueller, Alexandra A1 - Neumann, Meina A1 - Neumann, Sandra A1 - Leimkühler, Silke A1 - Narberhaus, Franz A1 - Masepohl, Bernd T1 - Specific interactions between four Molybdenum-binding proteins contribute to Mo-dependent gene regulation in Rhodobacter capsulatus N2 - The phototrophic purple bacterium Rhodobacter capsulatus encodes two transcriptional regulators, MopA and MopB, with partially overlapping and specific functions in molybdate-dependent gene regulation. Both MopA and MopB consist of an N-terminal DNA-binding helix-turn-helix domain and a C-terminal molybdate-binding di-MOP domain. They formed homodimers as apo-proteins and in the molybdate-bound state as shown by yeast two-hybrid (Y2H) studies, glutaraldehyde cross-linking, gel filtration chromatography, and copurification experiments. Y2H studies suggested that both the DNA- binding and the molybdate-binding domains contribute to dimer formation. Analysis of molybdate binding to MopA and MopB revealed a binding stoichiometry of four molybdate oxyanions per homodimer. Specific interaction partners of MopA and MopB were the molybdate transporter ATPase ModC and the molbindin-like Mop protein, respectively. Like other molbindins, the R. capsulatus Mop protein formed hexamers, which were stabilized by binding of six molybdate oxyanions per hexamer. Heteromer formation of MopA and MopB was shown by Y2H studies and copurification experiments. Reporter gene activity of a strictly MopA-dependent mop-lacZ fusion in mutant strains defective for either mopA, mopB, or both suggested that MopB negatively modulates expression of the mop promoter. We propose that depletion of the active MopA homodimer pool by formation of MopA-MopB heteromers might represent a fine-tuning mechanism controlling mop gene expression. Y1 - 2009 UR - http://jb.asm.org/ U6 - https://doi.org/10.1128/Jb.00526-09 SN - 0021-9193 ER - TY - GEN A1 - Blenau, Wolfgang A1 - Rotte, Cathleen A1 - Witte, Jeannine A1 - Baumann, Otto A1 - Walz, Bernd T1 - Source, topography and excitatory effects of GABAergic innervation in cockroach salivary glands N2 - Cockroach salivary glands are innervated by dopaminergic and serotonergic neurons. Both transmitters elicit saliva secretion. We studied the distribution pattern of neurons containing gamma-aminobutyric acid ( GABA) and their physiological role. Immunofluorescence revealed a GABA-immunoreactive axon that originates within the subesophageal ganglion at the salivary neuron 2 (SN2) and this extends within the salivary duct nerve towards the salivary gland. GABA-positive fibers form a network on most acinar lobules and a dense plexus in the interior of a minor fraction of acinar lobules. Co-staining with anti-synapsin revealed that some putative GABAergic terminals seem to make pre-synaptic contacts with GABA-negative release sites. Many putative GABAergic release sites are at some distance from other synapses and at distance from the acinar tissue. Intracellular recordings from isolated salivary glands have revealed that GABA does not affect the basolateral membrane potential of the acinar cells directly. When applied during salivary duct nerve stimulation, GABA enhances the electrical response of the acinar cells and increases the rates of fluid and protein secretion. The effect on electrical cell responses is mimicked by the GABA(B) receptor agonists baclofen and SKF97541, and blocked by the GABAB receptor antagonists CGP52432 and CGP54626. These findings indicate that GABA has a modulatory role in the control of salivation, acting presynaptically on serotonergic and/or dopaminergic neurotransmission. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 111 KW - GABA KW - salivary gland KW - innervation KW - cockroach KW - Periplaneta americana Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44353 ER - TY - JOUR A1 - Wonke, Gundula A1 - Wallschläger, Hans-Dieter T1 - Song dialects in the yellowhammer Emberiza citrinella : bioacoustic variation between and within dialects N2 - The yellowhammer Emberiza citrinella is a common European bird that sings in dialects that for decades have been distinguished by the existence of one single element (called a "specific''). In this study we looked into other possibilities for dialect discrimination, measuring 24 different variables. For the first time, multivariate statistics were used to discriminate dialect in yellowhammer song. Two similar dialects (XlB and XsB) that are not clearly defined in the literature were studied. Statistics incorporated (1) all variables, ( 2) no variables of "specific'' elements, and (3) no variables under the influence of these "specific'' variables. Multivariate statistics support dialect discrimination by ear and confirmed that only one element in yellowhammer song characterises dialect. In addition, we looked for local differences within two dialects and found that one local observation area showed a higher separation than the other sites (Meck1). However, as yet there is insufficient evidence for the existence of a new subdialect. Y1 - 2009 UR - http://www.springerlink.com/content/110831 U6 - https://doi.org/10.1007/s10336-008-0326-6 SN - 0021-8375 ER - TY - GEN A1 - Schumann, Silvia A1 - Terao, Mineko A1 - Garattini, Enrico A1 - Saggu, Miguel A1 - Lendzian, Friedhelm A1 - Hildebrandt, Peter A1 - Leimkühler, Silke T1 - Site directed mutagenesis of amino acid residues at the active site of mouse aldehyde oxidase AOX1 N2 - Mouse aldehyde oxidase (mAOX1) forms a homodimer and belongs to the xanthine oxidase family of molybdoenzymes which are characterized by an essential equatorial sulfur ligand coordinated to the molybdenum atom. In general, mammalian AOs are characterized by broad substrate specificity and an yet obscure physiological function. To define the physiological substrates and the enzymatic characteristics of mAOX1, we established a system for the heterologous expression of the enzyme in Eschericia coli. The recombinant protein showed spectral features and a range of substrate specificity similar to the native protein purified from mouse liver. The EPR data of recombinant mAOX1 were similar to those of AO from rabbit liver, but differed from the homologous xanthine oxidoreductase enzymes. Site-directed mutagenesis of amino acids Val806, Met884 and Glu1265 at the active site resulted in a drastic decrease in the oxidation of aldehydes with no increase in the oxidation of purine substrates. The double mutant V806E/M884R and the single mutant E1265Q were catalytically inactive enzymes regardless of the aldehyde or purine substrates tested. Our results show that only Glu1265 is essential for the catalytic activity by initiating the base-catalyzed mechanism of substrate oxidation. In addition, it is concluded that the substrate specificity of molybdo-flavoenzymes is more complex and not only defined by the three characterized amino acids in the active site. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 134 Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-45030 ER - TY - JOUR A1 - Nettels, Daniel A1 - Müller-Späth, Sonja A1 - Küster, Frank A1 - Hofmann, Hagen A1 - Haenni, Domminik A1 - Rüegger, Stefan A1 - Reymond, Luc A1 - Hoffmann, Armin S. A1 - Kubelka, Jan A1 - Heinz, Benjamin A1 - Gast, Klaus A1 - Best, Robert B. A1 - Schuler, Benjamin T1 - Single-molecule spectroscopy of the temperature-induced collapse of unfolded proteins N2 - We used single-molecule FRET in combination with other biophysical methods and molecular simulations to investigate the effect of temperature on the dimensions of unfolded proteins. With singlemolecule FRET, this question can be addressed even under nearnative conditions, where most molecules are folded, allowing us to probe a wide range of denaturant concentrations and temperatures. We find a compaction of the unfolded state of a small cold shock protein with increasing temperature in both the presence and the absence of denaturant, with good agreement between the results from single-molecule FRET and dynamic light scattering. Although dissociation of denaturant from the polypeptide chain with increasing temperature accounts for part of the compaction, the results indicate an important role for additional temperaturedependent interactions within the unfolded chain. The observation of a collapse of a similar extent in the extremely hydrophilic, intrinsically disordered protein prothymosin suggests that the hydrophobic effect is not the sole source of the underlying interactions. Circular dichroism spectroscopy and replica exchange molecular dynamics simulations in explicit water show changes in secondary structure content with increasing temperature and suggest a contribution of intramolecular hydrogen bonding to unfolded state collapse. Y1 - 2009 UR - http://www.pnas.org/content/106/49/20740.full.pdf+html SN - 0027-8424 ER - TY - JOUR A1 - Tietjen, Britta A1 - Zehe, Erwin A1 - Jeltsch, Florian T1 - Simulating plant water availability in dry lands under climate change : a generic model of two soil layers N2 - Dry lands are exposed to a highly variable environment and face a high risk of degradation. The effects of climate change are likely to increase this risk; thus a profound knowledge of the system dynamics is crucial for evaluating management options. This applies particularly for the interactions between water and vegetation, which exhibit strong feedbacks. To evaluate these feedbacks and the effects of climate change on soil moisture dynamics, we developed a generic, process-based, spatially explicit soil moisture model of two soil layers, which can be coupled with vegetation models. A time scale relevant for ecological processes can be simulated without difficulty, and the model avoids complex parameterization with data that are unavailable for most regions of the world. We applied the model to four sites in Israel along a precipitation and soil type gradient and assessed the effects of climate change by comparing possible climatic changes with present climate conditions. The results show that in addition to temperature, the total amount of precipitation and its intra-annual variability are an important driver of soil moisture patterns. This indicates that particularly with regard to climate change, the approach of many ecological models that simulate water dynamics on an annual base is far too simple to make reliable predictions. Thus, the introduced model can serve as a valuable tool to improve present ecological models of dry lands because of its focus on the applicability and transferability. Y1 - 2009 UR - http://www.agu.org/journals/wr/ U6 - https://doi.org/10.1029/2007WR006589 SN - 0043-1397 ER - TY - JOUR A1 - Rossmanith, Eva A1 - Blaum, Niels A1 - Höntsch, Kerstin A1 - Jeltsch, Florian T1 - Sex-related parental care strategies in the lesser spotted woodpecker "Picoides minor" : of flexible mothers and dependable fathers N2 - We investigated sex-specific parental care behaviour of lesser spotted woodpeckers Picoides minor in the low mountain range Taunus, Germany. Observed parental care included incubation, nest sanitation as well as brooding and feeding of nestlings. Contributions of the two sexes to parental care changed in progress of the breeding period. During incubation and the first half of the nestling period, parental care was divided equally between partners. However, in the late nestling stage, we found males to feed their nestlings irrespective of brood size while females considerably decreased feeding rate with the number of nestlings. This behaviour culminated in desertion of small broods by females shortly before fledging. The fact that even deserted nests were successful indicates that males were able to compensate for the females' absence. Interestingly, the mating of one female with two males with separate nests could be found in the population, which confirms earlier findings of polyandry in the lesser spotted woodpecker. We conclude that biparental care is not essential in the later stage and one partner can reduce effort and thus costs of parental care, at least in small broods where the mate is able to compensate for that behaviour. Reduced care and desertion appears only in females, which might be caused by a combination of two traits: First, females might suffer higher costs of investment in terms of mortality and secondly, male-biased sex ratio in the population generally leads to higher mating probabilities for females in the following breeding season. The occurrence of polyandry seems to be a result of these conditions. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/118513172/home U6 - https://doi.org/10.1111/j.1600-048X.2008.04353.x SN - 0908-8857 ER - TY - JOUR A1 - Lisdat, Fred A1 - Dronov, Roman A1 - Möhwald, Helmuth A1 - Scheller, Frieder W. A1 - Kurth, Dirk G. T1 - Self-assembly of electro-active protein architectures on electrodes for the construction of biomimetic signal chains N2 - The layer-by-layer adsorption technique based on the consecutive deposition of oppositely charged species is for the preparation of protein multilayers with fully electro-active protein molecules. The methodology was established with cytochrome c and the polyelectrolyte sulfonated polyaniline (PASA). The technique is also useful for the construction of bi-protein architectures confining protein-protein communication to an electrode. Following natural examples of protein complexes with defined signal transfer, cytochrome c was arranged with enzymes such as xanthine oxidase, bilirubin oxidase, laccase, and sulfite oxidase in self-assembled multilayer architectures. Thus, biomimetic signal chains from the enzyme substrate via the enzyme and cytochrome c towards the electrode can be established. Communication between proteins immobilised in multiple layers on the electrode can be achieved by in situ generation of small shuttle molecules or more advantageously by direct interprotein electron transfer. This allows the construction of new sensing electrodes, the properties of which can be tuned by the number of deposited protein layers. The mechanism of electron transfer within such protein assemblies on gold electrodes will be discussed. Y1 - 2009 UR - http://xlink.rsc.org/jumptojournal.cfm?journal_code=CC U6 - https://doi.org/10.1039/B813559b SN - 1359-7345 ER - TY - JOUR A1 - Apio, Ann A1 - Muwanika, Vincent B. A1 - Plath, Martin A1 - Wronski, Torsten T1 - Seasonal variation in reproductive behaviour of bushbuck (Tragelaphus scriptus Pallas, 1766) in an equatorial savannah ecosystem N2 - While several authors suggest that bushbuck (Tragelaphus scriptus Pallas) from tropical areas with an approximately bimodal rainfall pattern breed throughout the year, there is also a report of seasonal breeding in this species. In this study, we provide indirect evidence of seasonality in reproduction by analysing behavioural data (e.g. rates of mixed-sex sightings) in a population of bushbuck inhabiting an equatorial savannah ecosystem in western Uganda. Observation rates of mixed-sex sightings were correlated with rainfall patterns. We suggest that peaks in reproductive behaviour following the wet season may be advantageous if calves are born during the next wet season, when fresh vegetation is available. Y1 - 2009 UR - http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291365-2028 U6 - https://doi.org/10.1111/j.1365-2028.2008.01000.x SN - 0141-6707 ER - TY - JOUR A1 - Popp, Alexander A1 - Vogel, Melanie A1 - Blaum, Niels A1 - Jeltsch, Florian T1 - Scaling up ecohydrological processes : role of surface water flow in water-limited landscapes N2 - In this study, we present a stochastic landscape modeling approach that has the power to transfer and integrate existing information on vegetation dynamics and hydrological processes from the small scale to the landscape scale. To include microscale processes like ecohydrological feedback mechanisms and spatial exchange like surface water flow, we derive transition probabilities from a fine-scale simulation model. We applied two versions of the landscape model, one that includes and one that disregards spatial exchange of water to the situation of a sustainably used research farm and communally used and degraded rangeland in semiarid Namibia. Our simulation experiments show that including spatial exchange of overland flow among vegetation patches into our model is a precondition to reproduce vegetation dynamics, composition, and productivity, as well as hydrological processes at the landscape scale. In the model version that includes spatial exchange of water, biomass production at light grazing intensities increases 2.24-fold compared to the model without overland flow. In contrast, overgrazing destabilizes positive feedbacks through vegetation and hydrology and decreases the number of hydrological sinks in the model with overland flow. The buffer capacity of these hydrological sinks disappears and runoff increases. Here, both models predicted runoff losses from the system and artificial droughts occurring even in years with good precipitation. Overall, our study reveals that a thorough understanding of overland flow is an important precondition for improving the management of semiarid and arid rangelands with distinct topography. Y1 - 2009 UR - http://www.agu.org/journals/jg/ U6 - https://doi.org/10.1029/2008jg000910 SN - 0148-0227 ER - TY - THES A1 - Hiller, Matthias T1 - Sample preparation of membrane proteins suitable for solid-state MAS NMR and development of assignment strategies T1 - Präparation von Membranproteinen für Strukturuntersuchungen mittels Festkörper MAS NMR und die Entwicklung von Zuordnungsstrategien N2 - Although the basic structure of biological membranes is provided by the lipid bilayer, most of the specific functions are carried out by membrane proteins (MPs) such as channels, ion-pumps and receptors. Additionally, it is known, that mutations in MPs are directly or indirectly involved in many diseases. Thus, structure determination of MPs is of major interest not only in structural biology but also in pharmacology, especially for drug development. Advances in structural biology of membrane proteins (MPs) have been strongly supported by the success of three leading techniques: X-ray crystallography, electron microscopy and solution NMR spectroscopy. However, X-ray crystallography and electron microscopy, require highly diffracting 3D or 2D crystals, respectively. Today, structure determination of non-crystalline solid protein preparations has been made possible through rapid progress of solid-state MAS NMR methodology for biological systems. Castellani et. al. solved and refined the first structure of a microcrystalline protein using only solid-state MAS NMR spectroscopy. These successful application open up perspectives to access systems that are difficult to crystallise or that form large heterogeneous complexes and insoluble aggregates, for example ligands bound to a MP-receptor, protein fibrils and heterogeneous proteins aggregates. Solid-state MAS NMR spectroscopy is in principle well suited to study MP at atomic resolution. In this thesis, different types of MP preparations were tested for their suitability to be studied by solid-state MAS NMR. Proteoliposomes, poorly diffracting 2D crystals and a PEG precipitate of the outer membrane protein G (OmpG) were prepared as a model system for large MPs. Results from this work, combined with data found in the literature, show that highly diffracting crystalline material is not a prerequirement for structural analysis of MPs by solid-state MAS NMR. Instead, it is possible to use non-diffracting 3D crystals, MP precipitates, poorly diffracting 2D crystals and proteoliposomes. For the latter two types of preparations, the MP is reconstituted into a lipid bilayer, which thus allows the structural investigation in a quasi-native environment. In addition, to prepare a MP sample for solid-state MAS NMR it is possible to use screening methods, that are well established for 3D and 2D crystallisation of MPs. Hopefully, these findings will open a fourth method for structural investigation of MP. The prerequisite for structural studies by NMR in general, and the most time consuming step, is always the assignment of resonances to specific nuclei within the protein. Since the last few years an ever-increasing number of assignments from solid-state MAS NMR of uniformly carbon and nitrogen labelled samples is being reported, mostly for small proteins of up to around 150 amino acids in length. However, the complexity of the spectra increases with increasing molecular weight of the protein. Thus the conventional assignment strategies developed for small proteins do not yield a sufficiently high degree of assignment for the large MP OmpG (281 amino acids). Therefore, a new assignment strategy to find starting points for large MPs was devised. The assignment procedure is based on a sample with [2,3-13C, 15N]-labelled Tyr and Phe and uniformly labelled alanine and glycine. This labelling pattern reduces the spectral overlap as well as the number of assignment possibilities. In order to extend the assignment, four other specifically labelled OmpG samples were used. The assignment procedure starts with the identification of the spin systems of each labelled amino acid using 2D 13C-13C and 3D NCACX correlation experiments. In a second step, 2D and 3D NCOCX type experiments are used for the sequential assignment of the observed resonances to specific nuclei in the OmpG amino acid sequence. Additionally, it was shown in this work, that biosynthetically site directed labelled samples, which are normally used to observe long-range correlations, were helpful to confirm the assignment. Another approach to find assignment starting points in large protein systems, is the use of spectroscopic filtering techniques. A filtering block that selects methyl resonances was used to find further assignment starting points for OmpG. Combining all these techniques, it was possible to assign nearly 50 % of the observed signals to the OmpG sequence. Using this information, a prediction of the secondary structure elements of OmpG was possible. Most of the calculated motifs were in good aggreement with the crystal structures of OmpG. The approaches presented here should be applicable to a wide variety of MPs and MP-complexes and should thus open a new avenue for the structural biology of MPs. N2 - Biologische Membranen bestehen hauptsächlich aus Lipiden, ihre Funktion wird jedoch vor allem durch die eingebetteten Membranproteine (z.B. Kanäle, Ionenpumpen und Rezeptoren) bestimmt. Mutationen in dieser Proteinklasse können zum Auftreten verschiedener Krankheitsbilder führen, weshalb die Untersuchung der dreidimensionalen Struktur von Membranproteinen nicht nur von strukturbiologischem, sondern auch von pharmakologischem Interesse ist. In den letzten Jahren wurde eine Methode, die Festkörper NMR Spektroskopie, für Strukturuntersuchungen an Proteinproben im festen Aggregatzustand entwickelt. Diese Arbeit beschäftigt sich mit drei verschiedenen Präparationsarten von Membranproteinen, die eine Aufnahme von hochaufgelösten Festkörper NMR Spektren erlauben. Als Modelsystem wurde das Protein G der äußeren Membrane (outer membrane protein G, OmpG) von Escherichia coli gewählt. Eine wichtige Vorraussetzung zur Berechnung der Proteinstruktur aus den NMR-Spektren, ist die Zuordnung der einzelnen Signale zur jeweiligen Aminosäure in der Proteinsequenz. In dieser Arbeit wurde eine Methode entwickelt, die das Auffinden von Startpunkten für die sequentielle Zuordnung in großen Membranproteinen, wie zum Bsp. OmpG (281 Aminosäuren), erlaubt. Multidimensionale NMR Experimente mit verschieden spezifisch markierten Proben wurden durchgeführt und ermöglichten die Zuordnung von 50 % der NMR Signale der OmpG Proteinsequenz. Zur Überprüfung der gewonnenen Daten wurden diese zur Vorhersage von Sekundärstrukturelementen genutzt. Es konnte gezeigt werden, dass die berechneten Strukturmotive in guter Übereinstimmung zu den bisher veröffentlichten OmpG Strukturen liegen. Die in dieser Arbeit angewendeten Methoden sollten auf eine Vielzahl anderer Membranprotein anwendbar und somit einen neuen Weg zur Strukturbiologischen Untersuchung von Membranproteinen eröffnen. KW - Membranproteine KW - Festkörper NMR Spektroskopie KW - Proteinstruktur KW - OmpG KW - Membrane protein KW - solid-state MAS NMR KW - protein structure KW - OmpG Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-37246 ER - TY - GEN A1 - Kugler, Annette A1 - Köhler, Barbara A1 - Palme, Klaus A1 - Wolff, Patricia A1 - Dietrich, Petra T1 - Salt-dependent regulation of a CNG channel subfamily in Arabidopsis N2 - Background: In Arabidopsis thaliana, the family of cyclic nucleotide-gated channels (CNGCs) is composed of 20 members. Previous studies indicate that plant CNGCs are involved in the control of growth processes and responses to abiotic and biotic stresses. According to their proposed function as cation entry pathways these channels contribute to cellular cation homeostasis, including calcium and sodium, as well as to stress-related signal transduction. Here, we studied the expression patterns and regulation of CNGC19 and CNGC20, which constitute one of the five CNGC subfamilies. Results: GUS, GFP and luciferase reporter assays were used to study the expression of CNGC19 and CNGC20 genes from Arabidopsis thaliana in response to developmental cues and salt stress. CNGC19 and CNGC20 were differentially expressed in roots and shoots. The CNGC19 gene was predominantly active in roots already at early growth stages. Major expression was observed in the phloem. CNGC20 showed highest promoter activity in mesophyll cells surrounding the veins. Its expression increased during development and was maximal in mature and senescent leaves. Both genes were upregulated in the shoot in response to elevated NaCl but not mannitol concentrations. While in the root, CNGC19 did not respond to changes in the salt concentration, in the shoot it was strongly upregulated in the observed time frame (6-72 hours). Salt-induction of CNGC20 was also observed in the shoot, starting already one hour after stress treatment. It occurred with similar kinetics, irrespective of whether NaCl was applied to roots of intact plants or to the petiole of detached leaves. No differences in K and Na contents of the shoots were measured in homozygous T-DNA insertion lines for CNGC19 and CNGC20, respectively, which developed a growth phenotype in the presence of up to 75 mM NaCl similar to that of the wild type. Conclusion: Together, the results strongly suggest that both channels are involved in the salinity response of different cell types in the shoot. Upon salinity both genes are upregulated within hours. CNGC19 and CNGC20 could assist the plant to cope with toxic effects caused by salt stress, probably by contributing to a re-allocation of sodium within the plant. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 133 KW - Nucleotide-gated channel KW - Na+/H+ antiporter SOS1 KW - Ricinus-communis l KW - Plasma membrane KW - Functional analysis Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-45019 ER - TY - THES A1 - Witte, Jeannine T1 - Rhabdomerorganisation und –morphogenese im Komplexauge von Drosophila T1 - Rhabdomere organization and morphogenesis in the compound eye of Drosophila N2 - Sehzellen von Insekten sind epitheliale Zellen mit einer charakteristischen, hochpolaren Morphologie und Organisation. Die molekularen Komponenten der Sehkaskade befinden sich im Rhabdomer, einem Saum dicht gepackter Mikrovilli entlang der Sehzelle. Bereits in den 70er Jahren des letzten Jahrhunderts wurde beschrieben, dass die Mikrovilli entlang einer Sehzelle eine unterschiedliche Ausrichtung besitzen, oder in anderen Worten, die Rhabdomere entlang der Sehzell-Längsachse verdreht sind. So sind in den Sehzellen R1-R6 bei dipteren Fliegen (Calliphora, Drosophila) die Mikrovilli im distalen und proximalen Bereich eines Rhabdomers etwa rechtwinkelig zueinander angeordnet. Dieses Phänomen wird in der Fachliteratur als rhabdomere twisting bezeichnet und reduziert die Empfindlichkeit für polarisiertes Licht. Es wurde für das Drosophila-Auge gezeigt, dass diese strukturelle Asymmetrie der Sehzellen mit einer molekularen Asymmetrie in der Verteilung phosphotyrosinierter Proteine an die Stielmembran (einem nicht-mikrovillären Bereich der apikalen Plasmamembran) einhergeht. Zudem wurde gezeigt, dass die immuncytochemische Markierung mit anti-Phosphotyrosin (anti-PY) als lichtmikroskopischer Marker für das rhabdomere twisting verwendet werden kann. Bisher wurde hauptsächlich die physiologische Bedeutung der Rhabdomerverdrehung untersucht. Es ist wenig über die entwicklungs- und zellbiologischen Grundlagen bekannt. Ziel der vorliegenden Arbeit war es, die Identität der phosphotyrosinierten Proteine an der Stielmembran zu klären und ihre funktionelle Bedeutung für die Entwicklung des rhabdomere twisting zu analysieren. Zudem sollte untersucht werden, welchen Einfluss die inneren Sehzellen R7 und R8 auf die Verdrehung der Rhabdomere von R1-R6 haben. Für die zwei Proteinkinasen Rolled (ERK) und Basket (JNK) vom Typ der Mitogen-aktivierten Proteinkinasen (MAPK) konnte ich zeigen, dass sie in ihrer aktivierten (= phosphorylierten) Form (pERK bzw. pJNK) eine asymmetrische Verteilung an der Stielmembran aufweisen vergleichbar der Markierung mit anti-PY. Weiterhin wurde diese asymmetrische Verteilung von pERK und pJNK ebenso wie die von PY erst kurz vor Schlupf der Fliegen (bei ca. 90% pupaler Entwicklung) etabliert. Durch Präinkubationsexperimente mit anti-PY wurde die Markierung mit anti-pERK bzw. anti-pJNK unterbunden. Diese Ergebnisse sprechen dafür, dass pERK und pJNK zu den Proteinen gehören, die von anti-PY an der Stielmembran erkannt werden. Da es sich bei ERK und JNK um Kinasen handelt, ist es naheliegend, dass diese an der Entwicklung des rhabdomere twisting beteiligt sein könnten. Diese Hypothese wurde durch die Analyse von hypermorphen (rl SEM)und hypomorphen (rl 1/rl 10a) Rolled-Mutanten überprüft. In der rl SEM-Mutante mit erhöhter Aktivität der Proteinkinase erfolgte die asymmetrische Positionierung von pERK an der Stielmembran sowie die Mikrovillikippung schon zu einem früheren Zeitpunkt in der pupalen Entwicklung. Im adulten Auge war die anti-PY-Markierung im distalen Bereich der Sehzellen intensiver sowie der Kippwinkel vergrößert. In der rl 1/rl 10a-Mutanten mit reduzierter Kinaseaktivität waren die anti-PY-Markierung und der Kippwinkel im proximalen Bereich der Sehzellen verringert. Die Proteinkinase ERK hat somit einen Einfluss auf die zeitliche Etablierung des rhabdomere twisting wie auch auf dessen Ausprägung im Adulttier. Die Rhabdomerverdrehung sowie die Änderung im anti-PY-Markierungsmuster erfolgen an den Sehzellen R1-R6 relativ abrupt auf halber Ommatidienlänge, dort wo das Rhabdomer von R7 endet und das von R8 beginnt. Es stellte sich deshalb die Frage, ob die Rhabdomerverdrehung an R1-R6 durch die Sehzelle R7 und/oder R8 beeinflusst wird. Um dieser Frage nachzugehen wurden Mutanten analysiert, denen die R7- oder die R8-Photorezeptoren bzw. R7 und R8 fehlten. Das wichtigste Ergebnis dieser Untersuchungen war, dass bei Fehlen von R8 die Rhabdomerverdrehung bei R1-R6 nach keinen erkennbaren Regeln erfolgt. R8 ist somit Voraussetzung für die Etablierung der Rhabdomerverdrehung in R1-R6. Folgendes Modell wurde auf Grundlage dieses und weiterer Ergebnisse erarbeitet: Im dritten Larvenstadium rekrutiert R8 die Sehzellpaare R2/R5, R3/R4 und R1/R6. Dabei werden R1-R6 durch den Kontakt zu R8 „polarisiert“. Abschließend wird R7 durch R8 rekrutiert. Dies führt zu einer Fixierung der Polarität von R1-R6 durch R7. Die Ausführung der Mikrovillikippung anhand der festgelegten Polarität erfolgt in der späten Puppenphase. Die Proteinkinase ERK ist an diesem letzten Morphogeneseprozess beteiligt. N2 - Visual cells of insects are epithelial cells with a characteristic morphology and organization. The molecular components of the signalling cascade are arranged in the rhabdomere, an array of densely packed microvilli along the side of the cell body. Already in the 70s of the last century it was described that microvilli point in different directions in various segments of the rhabdomere. Thus, in Dipteran flies (Calliphora, Drosophila) microvilli in the distal part of visual cells R1-R6 are nearly perpendicular to the microvilli in the proximal portion. This phenomenon is termed rhabdomere twisting and decreases the sensitivity of visual cells to polarized light. For Drosophila, structural asymmetry was shown to correlate with molecular asymmetry in the distribution of phosphotyrosinated proteins to the stalk (a non-microvillar region of the apical plasma membrane). Furthermore, this asymmetric distribution of antiphosphotyrosine (anti-PY) provides a light microscopic marker for rhabdomere twisting. So far little is known about the developmental and cell biological basis of rhabdomere twisting. Purpose of the present study was to identify the phosphotyrosinated proteins at the stalk und to analyse their functional relevance for the development of rhabdomere twisting. Moreover, influence of the inner visual cells R7 and R8 on rhabdomere twisting should be examined. Two protein kinases of the MAPK-type, Rolled (ERK) and Basket (JNK), show for their activated (= phosphorylated) forms (pERK and pJNK respectively) an asymmetric distribution to the stalk comparable to labelling with anti-PY. In addition, this asymmetric distribution of pERK, pJNK and also PY is established shortly before eclosion of the fly. Preincubation experiments with anti-PY abolished labelling with anti-pERK and anti-pJNK respectively. These results indicate that pERK and pJNK belong to the proteins on the stalk recognized by anti-PY. ERK and JNK are kinases and therefore are likely to be involved in the development of rhabdomere twisting. To test this hypothesis I analysed hypermorph (rl SEM) and hypomorph (rl 1/rl 10a) rolled mutants. In rl SEM mutants with increased kinase activity asymmetric positioning of pERK to the stalk and tilting of microvilli occurred earlier during pupal development. In the adult eye anti-PY labelling was more intensive in the distal part of the visual cells, and congruently the microvillar tilt angle was increased. In rl 1/rl 10a mutants with reduced kinase activity anti-PY labelling and microvillar tilt angle were reduced in the proximal part of visual cells. Hence, protein kinase ERK has an influence on developmental establishment of rhabdomere twisting and its specification in the adult eye. In R1-R6 rhabdomere twisting as well as changes in anti-PY labelling pattern take place within a narrow range halfway along the rhabdomere where the rhabdomere of R7 ceases and that of R8 begins. So the question arises whether rhabdomere twisting of R1-R6 is influenced by R7 and/or R8. To answer that question I analysed mutants that lack R7 or R8 or both visual cells. Most importantly absence of R8 leads to a disorganized rhabdomere twisting in R1-R6. Consequently R8 seems to be required for the establishment of rhabdomere twisting in R1-R6. Following working model was developed: in the third larval instar R8 recruits pairs of visual cells R2/R5, R3/R4 and R1/R6. In that process R1-R6 become „polarised“ by the contact to R8. Finally R7 is recruited by R8. That fixes polarity of R1-R6 by R7. The active tilting of the microvilli on the basis of the given polarity is carried out in late pupal development with the help of protein kinase ERK. KW - Komplexauge KW - Drosophila KW - Rhabdomerverdrehung KW - MAPK KW - compound eye KW - Drosophila KW - rhabdomere twisting KW - MAP kinase Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41847 ER - TY - JOUR A1 - May, Felix A1 - Grimm, Volker A1 - Jeltsch, Florian T1 - Reversed effects of grazing on plant diversity : the role of below-ground competition and size symmetry N2 - Grazing is known as one of the key factors for diversity and community composition in grassland ecosystems, but the response of plant communities towards grazing varies remarkably between sites with different environmental conditions. It is generally accepted that grazing increases plant diversity in productive environments, while it tends to reduce diversity in unproductive habitats (grazing reversal hypothesis). Despite empirical evidence for this pattern the mechanistic link between modes of plant-plant competition and grazing response at the community level still remains poorly understood. Root-competition in particular has rarely been included in theoretical studies, although it has been hypothesized that variations in productivity and grazing regime can alter the relative importance of shoot- and root-competition. We therefore developed an individual-based model based on plant functional traits to investigate the response of a grassland community towards grazing. Models of different complexity, either incorporating only shoot competition or with distinct shoot- and root-competition, were used to study the interactive effects of grazing, resource availability, and the mode of competition (size-symmetric or asymmetric). The pattern predicted by the grazing reversal hypothesis (GRH) can only be explained by our model if shoot- and root-competition are explicitly considered and if size asymmetry of above- and symmetry of below-ground competition is assumed. For this scenario, the model additionally reproduced empirically observed plant trait responses: erect and large plant functional types (PFTs) dominated without grazing, while frequent grazing favoured small PFTs with a rosette growth form. We conclude that interactions between shoot- and root-competition and size symmetry/asymmetry of plant-plant interactions are crucial in order to understand grazing response under different habitat productivities. Our results suggest that future empirical trait surveys in grassland communities should include root traits, which have been largely ignored in previous studies, in order to improve predictions of plants" responses to grazing. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/118531693/home U6 - https://doi.org/10.1111/j.1600-0706.2009.17724.x SN - 0030-1299 ER - TY - GEN A1 - de Castro, Francisco A1 - Gaedke, Ursula A1 - Boenigk, Jens T1 - Reverse evolution : driving forces behind the loss of acquired photosynthetic traits N2 - Background: The loss of photosynthesis has occurred often in eukaryotic evolution, even more than its acquisition, which occurred at least nine times independently and which generated the evolution of the supergroups Archaeplastida, Rhizaria, Chromalveolata and Excavata. This secondary loss of autotrophic capability is essential to explain the evolution of eukaryotes and the high diversity of protists, which has been severely underestimated until recently. However, the ecological and evolutionary scenarios behind this evolutionary ‘‘step back’’ are still largely unknown. Methodology/Principal Findings: Using a dynamic model of heterotrophic and mixotrophic flagellates and two types of prey, large bacteria and ultramicrobacteria, we examine the influence of DOC concentration, mixotroph’s photosynthetic growth rate, and external limitations of photosynthesis on the coexistence of both types of flagellates. Our key premises are: large bacteria grow faster than small ones at high DOC concentrations, and vice versa; and heterotrophic flagellates are more efficient than the mixotrophs grazing small bacteria (both empirically supported). We show that differential efficiency in bacteria grazing, which strongly depends on cell size, is a key factor to explain the loss of photosynthesis in mixotrophs (which combine photosynthesis and bacterivory) leading to purely heterotrophic lineages. Further, we show in what conditions an heterotroph mutant can coexist, or even out-compete, its mixotrophic ancestor, suggesting that bacterivory and cell size reduction may have been major triggers for the diversification of eukaryotes. Conclusions/Significance: Our results suggest that, provided the mixotroph’s photosynthetic advantage is not too large, the (small) heterotroph will also dominate in nutrient-poor environments and will readily invade a community of mixotrophs and bacteria, due to its higher efficiency exploiting the ultramicrobacteria. As carbon-limited conditions were presumably widespread throughout Earth history, such a scenario may explain the numerous transitions from phototrophy to mixotrophy and further to heterotrophy within virtually all major algal lineages. We challenge prevailing concepts that affiliated the evolution of phagotrophy with eutrophic or strongly light-limited environments only. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 128 KW - Fresh-water habitats KW - Operon copy number KW - Growth-rate KW - Bacteria KW - Plankton Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44968 ER - TY - JOUR A1 - Moloney, Kirk A. A1 - Holzapfel, Claus A1 - Tielbörger, Katja A1 - Jeltsch, Florian A1 - Schurr, Frank Martin T1 - Rethinking the common garden in invasion research N2 - In common garden experiments, a number of genotypes are raised in a common environment in order to quantify the genetic component of phenotypic variation. Common gardens are thus ideally suited for disentangling how genetic and environmental factors contribute to the success of invasive species in their new non-native range. Although common garden experiments are increasingly employed in the study of invasive species, there has been little discussion about how these experiments should be designed for greatest utility. We argue that this has delayed progress in developing a general theory of invasion biology. We suggest a minimum optimal design (MOD) for common garden studies that target the ecological and evolutionary processes leading to phenotypic differentiation between native and invasive ranges. This involves four elements: (A) multiple, strategically sited garden locations, involving at the very least four gardens (2 in the native range and 2 in the invaded range); (B) careful consideration of the genetic design of the experiment; (C) standardization of experimental protocols across all gardens; and (D) care to ensure the biosafety of the experiment. Our understanding of the evolutionary ecology of biological invasions will be greatly enhanced by common garden studies, if and only if they are designed in a more systematic fashion, incorporating at the very least the MOD suggested here. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/14338319 U6 - https://doi.org/10.1016/j.ppees.2009.05.002 SN - 1433-8319 ER - TY - JOUR A1 - Kamjunke, Norbert A1 - Straile, Dietmar A1 - Gaedke, Ursula T1 - Response of heterotrophic bacteria, autotrophic picoplankton and heterotrophic nanoflagellates to re- oligotrophication N2 - We investigated the response of the microbial components of the pelagic food web to re-oligotrophication of large, deep Lake Constance where total phosphorus concentrations during mixing decreased from a maximum of 2.81 mu mol L- 1 in 1979 via 1.87 mu mol L-1 in 1987 to 0.26 mu mol L-1 in 2007. Measurements of heterotrophic bacteria, autotrophic picoplankton (APP) and heterotrophic nanoflagellates (HNF) in 2006 and 2007 were compared to values from 1987 to 1997. We hypothesized that the biomass and seasonal variability of all groups will decrease under more oligotrophic conditions due to reduced resource availability, particularly for APP and HNF but less for the competitively stronger bacteria. Average bacterial biomass between spring and autumn was unrelated to phosphorus, whereas the ratio of bacterial biomass to chlorophyll a concentration increased with decreasing trophy due to declining chlorophyll concentrations. In contrast, a unimodal relationship was found between APP and phosphorus with low biomass at low and high phosphorus concentrations and maximum biomass in between. Average HNF biomass decreased strongly by a factor of 10-30 with decreasing trophy, and chlorophyll-specific HNF biomass was unimodally related to phosphorus. The relative seasonal biomass variability did not change for any group during re-oligotrophication. To conclude, HNF responded much more strongly and bacteria less so than chlorophyll concentrations to oligotrophication, whereas APP exhibited a more complex pattern. Y1 - 2009 UR - http://plankt.oxfordjournals.org/ U6 - https://doi.org/10.1093/plankt/fbp037 SN - 0142-7873 ER - TY - JOUR A1 - Dreyer, Ingo A1 - Gajdanowicz, Pawel T1 - Regulation of the gating mode of the Arabidopsis K+ channel AKT2 is important for adaptation to abiotic stress Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/10956433 U6 - https://doi.org/10.1016/j.cbpa.2009.04.426 SN - 1095-6433 ER - TY - JOUR A1 - Walter, Juliane K. A1 - Castro, Victor Manuel A1 - Voss, Martin A1 - Gast, Klaus A1 - Rueckert, Christine A1 - Piontek, Jörg A1 - Blasig, Ingolf E. T1 - Redox-sensitivity of the dimerization of occludin N2 - Occludin is a self-associating transmembrane tight junction protein affected in oxidative stress. However, its function is unknown. The cytosolic C-terminal tail contains a coiled coil-domain forming dimers contributing to the self- association. Studying the hypothesis that the self-association is redox-sensitive, we found that the dimerization of the domain depended on the sulfhydryl concentration of the environment in low-millimolar range. Under physiological conditions, monomers and dimers were detected. Masking the sulfhydryl residues in the domain prevented the dimerization but affected neither its helical structure nor cylindric shape. Incubation of cell extracts containing full-length occludin with sulfhydryl reagents prevented the dimerization; a cysteine/alanine exchange mutant also did not show dimer formation. This demonstrates, for the first time, that disulfide bridge formation of the domain is involved in the occludin dimerization. It is concluded that the redox-dependent dimerization of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions. Y1 - 2009 UR - http://www.springerlink.com/content/101193 U6 - https://doi.org/10.1007/s00018-009-0150-z SN - 1420-682X ER - TY - JOUR A1 - Walter, Juliane K. A1 - Castro, Victor Manuel A1 - Voss, M. A1 - Gast, Klaus A1 - Rueckert, C. A1 - Piontek, J. A1 - Blasig, Ingolf E. T1 - Redox sensitivity of the dimerization of occludin N2 - Occludin is a self-associating transmembrane tight junction protein affected in oxidative stress. However, its function is unknown. The cytosolic C-terminal tail contains a coiled coil-domain forming dimers contributing to the self- association. Studying the hypothesis that the self-association is redox-sensitive, we found that the dimerization of the domain depended on the sulfhydryl concentration of the environment in low-millimolar range. Under physiological conditions, monomers and dimers were detected. Masking the sulfhydryl residues in the domain prevented the dimerization but affected neither its helical structure nor cylindric shape. Incubation of cell extracts containing full-length occludin with sulfhydryl reagents prevented the dimerization; a cysteine/alanine exchange mutant also did not show dimer formation. This demonstrates, for the first time, that disulfide bridge formation of the domain is involved in the occludin dimerization. It is concluded that the redox-dependent dimerization of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions. Y1 - 2009 UR - http://www.springerlink.com/content/a0w10t7jgn01lk6h/ SN - 1420-682X ER - TY - JOUR A1 - Meyer, Rhonda Christiane A1 - Kusterer, Barbara A1 - Lisec, Jan A1 - Steinfath, Matthias A1 - Becher, Martina A1 - Scharr, Hanno A1 - Melchinger, Albrecht E. A1 - Selbig, Joachim A1 - Schurr, Ulrich A1 - Willmitzer, Lothar A1 - Altmann, Thomas T1 - QTL analysis of early stage heterosis for biomass in Arabidopsis JF - Theoretical and applied genetics N2 - The main objective of this study was to identify genomic regions involved in biomass heterosis using QTL, generation means, and mode-of-inheritance classification analyses. In a modified North Carolina Design III we backcrossed 429 recombinant inbred line and 140 introgression line populations to the two parental accessions, C24 and Col-0, whose F 1 hybrid exhibited 44% heterosis for biomass. Mid-parent heterosis in the RILs ranged from −31 to 99% for dry weight and from −58 to 143% for leaf area. We detected ten genomic positions involved in biomass heterosis at an early developmental stage, individually explaining between 2.4 and 15.7% of the phenotypic variation. While overdominant gene action was prevalent in heterotic QTL, our results suggest that a combination of dominance, overdominance and epistasis is involved in biomass heterosis in this Arabidopsis cross. KW - Quantitative Trait Locus KW - recombinant inbred line KW - Quantitative Trait Locus analysis KW - dominance effect KW - recombinant inbred line population Y1 - 2009 U6 - https://doi.org/10.1007/s00122-009-1074-6 SN - 1432-2242 SN - 0040-5752 VL - 129 IS - 2 SP - 227 EP - 237 PB - Springer Nature CY - Berlin ER - TY - GEN A1 - Meyer, Rhonda Christiane A1 - Kusterer, Barbara A1 - Lisec, Jan A1 - Steinfath, Matthias A1 - Becher, Martina A1 - Scharr, Hanno A1 - Melchinger, Albrecht E. A1 - Selbig, Joachim A1 - Schurr, Ulrich A1 - Willmitzer, Lothar A1 - Altmann, Thomas T1 - QTL analysis of early stage heterosis for biomass in Arabidopsis T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The main objective of this study was to identify genomic regions involved in biomass heterosis using QTL, generation means, and mode-of-inheritance classification analyses. In a modified North Carolina Design III we backcrossed 429 recombinant inbred line and 140 introgression line populations to the two parental accessions, C24 and Col-0, whose F 1 hybrid exhibited 44% heterosis for biomass. Mid-parent heterosis in the RILs ranged from −31 to 99% for dry weight and from −58 to 143% for leaf area. We detected ten genomic positions involved in biomass heterosis at an early developmental stage, individually explaining between 2.4 and 15.7% of the phenotypic variation. While overdominant gene action was prevalent in heterotic QTL, our results suggest that a combination of dominance, overdominance and epistasis is involved in biomass heterosis in this Arabidopsis cross. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1330 KW - Quantitative Trait Locus KW - recombinant inbred line KW - Quantitative Trait Locus analysis KW - dominance effect KW - recombinant inbred line population Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-431272 SN - 1866-8372 IS - 1330 ER - TY - GEN A1 - Steinfath, Matthias A1 - Gärtner, Tanja A1 - Lisec, Jan A1 - Meyer, Rhonda C. A1 - Altmann, Thomas A1 - Willmitzer, Lothar A1 - Selbig, Joachim T1 - Prediction of hybrid biomass in Arabidopsis thaliana by selected parental SNP and metabolic markers T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - A recombinant inbred line (RIL) population, derived from two Arabidopsis thaliana accessions, and the corresponding testcrosses with these two original accessions were used for the development and validation of machine learning models to predict the biomass of hybrids. Genetic and metabolic information of the RILs served as predictors. Feature selection reduced the number of variables (genetic and metabolic markers) in the models by more than 80% without impairing the predictive power. Thus, potential biomarkers have been revealed. Metabolites were shown to bear information on inherited macroscopic phenotypes. This proof of concept could be interesting for breeders. The example population exhibits substantial mid-parent biomass heterosis. The results of feature selection could therefore be used to shed light on the origin of heterosis. In this respect, mainly dominance effects were detected. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1324 KW - Quantitative Trait Locus KW - feature selection KW - Partial Little Square KW - recombinant inbred line KW - Quantitative Trait Locus analysis Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-431115 SN - 1866-8372 IS - 1324 ER - TY - JOUR A1 - Steinfath, Matthias A1 - Gärtner, Tanja A1 - Lisec, Jan A1 - Meyer, Rhonda Christiane A1 - Altmann, Thomas A1 - Willmitzer, Lothar A1 - Selbig, Joachim T1 - Prediction of hybrid biomass in Arabidopsis thaliana by selected parental SNP and metabolic markers JF - Theoretical and applied genetics : TAG ; international journal of plant breeding research N2 - A recombinant inbred line (RIL) population, derived from two Arabidopsis thaliana accessions, and the corresponding testcrosses with these two original accessions were used for the development and validation of machine learning models to predict the biomass of hybrids. Genetic and metabolic information of the RILs served as predictors. Feature selection reduced the number of variables (genetic and metabolic markers) in the models by more than 80% without impairing the predictive power. Thus, potential biomarkers have been revealed. Metabolites were shown to bear information on inherited macroscopic phenotypes. This proof of concept could be interesting for breeders. The example population exhibits substantial mid-parent biomass heterosis. The results of feature selection could therefore be used to shed light on the origin of heterosis. In this respect, mainly dominance effects were detected. KW - Quantitative Trait Locus KW - feature selection KW - Partial Little Square KW - recombinant inbred line KW - Quantitative Trait Locus analysis Y1 - 2009 U6 - https://doi.org/10.1007/s00122-009-1191-2 SN - 0040-5752 SN - 1432-2242 VL - 120 SP - 239 EP - 247 PB - Springer CY - Berlin ER - TY - THES A1 - Schüler, Grit T1 - Potsdamer Längsschnittstudie : Beurteilung der körperlichen Entwicklung vom Kleinkindalter bis zum frühen Schulalter mit Hilfe von Somatometrie, Fotogrammetrie und Morphognose Y1 - 2009 CY - Potsdam ER - TY - JOUR A1 - Heinken, Thilo T1 - Populationsbiologische und genetische Konsequenzen von Habitatfragmentierung bei Pflanzen : wissenschaftliche Grundlagen für Biotopverbundsysteme N2 - Besides habitat loss, population-biological and genetic consequences of habitat fragmentation are thought to be a major threat to species since the 1990's and thus are now in the focus of plant species conservation. Using examples, this article gives an overview on the state of the art. It aims to evaluate the relevance habitat fragmentation and the resulting small size and isolation of populations may have for Central European plant populations. Stochasticity, edge effects, pollinator limitation, genetic drift and inbreeding depression are identified as important and very widespread negative effects. Together with changed habitat quality due to eutrophication, drainage or altered land use they negatively affect the fitness of individuals and populations, resulting in an increased risk of extinction. This negative effect of small populations on the fitness of individuals is called the Allee-effect, irrespective of the underlying causes, which can only be identified by scientific experiments. Metapopulation dynamics that are supported by a habitat network may prevent a permanent extinction of plant populations and minimize the negative genetic effects of habitat fragmentation by increasing gene flow via pollen and seeds. However, existing studies from Central Europe mainly concentrated on certain plant families (Gentianaceae, Primulaceae), habitats (species- rich grasslands), insect-pollinated and outcrossing species, and species mainly relying on sexual reproduction. On the other hand, few insights exist about grasses, ruderal plants and weeds, non-indigenous, wind- and self-pollinated species, and species mainly reproducing vegetatively or via apomictic seeds. However, according to the present state of knowledge especially these plant species, and those with a high dispersal potential, have to be considered as less sensitive to habitat fragmentation. Based on these findings, habitat types are classified with regard to their sensitivity to fragmentation, and ecological characters and species traits of sensitive and less sensitive species are compared. Finally, general consequences for conservation practice are presented with regard to target species and habitats for the formation of habitat networks, minimum viable population sizes, genetic rescue of populations, and deploying plants from ex-situ conservation to natural habitats. Y1 - 2009 SN - 0722-494X ER - TY - THES A1 - Wiemann, Annika T1 - Population genetics and social dynamics in harbour porpoises and bottlenose dolphins (Cetacea) : posibble implications for nature conservation Y1 - 2009 CY - Potsdam ER - TY - JOUR A1 - Warsinke, Axel T1 - Point-of-care testing of proteins N2 - Point-of-care testing (POCT) is a fast developing area in clinical diagnostics that is considered to be one of the main driving forces for the future in vitro diagnostic market. POCT means decentralized testing at the site of patient care. The most important POCT devices are handheld blood glucose sensors. In some of these sensors, after the application of less than 1 A mu l whole blood, the results are displayed in less than 10 s. For protein determination, the most commonly used devices are based on lateral flow technology. Although these devices are convenient to use, the results are often only qualitative or semiquantitative. The review will illuminate some of the current methods employed in POCT for proteins and will discuss the outlook for techniques (e.g., electrochemical immunosensors) that could have a great impact on future POCT of proteins. Y1 - 2009 UR - http://www.springerlink.com/content/100417 U6 - https://doi.org/10.1007/s00216-008-2572-0 SN - 1618-2642 ER - TY - JOUR A1 - Spijkerman, Elly T1 - Physiological characteristics of co-limiting conditions for P and C in Chlamydomonas Y1 - 2009 UR - http://www.phycologia.org/perlserv/?request=get-archive U6 - https://doi.org/10.2216/0031-8884-48.sp4.1 SN - 0031-8884 ER - TY - JOUR A1 - Ketmaier, Valerio A1 - Finamore, Francesco A1 - Largiader, Carlo Rodolfo A1 - Milone, Marco A1 - Bianco, Pier Giorgio T1 - Phylogeography of bleaks Alburnus spp. (Cyprinidae) in Italy, based on cytochrome b data N2 - Sequence variation of a fragment of the mitochondrial DNA encoding for the cytochrome b gene was used to reconstruct the phylogeography of the two species of bleaks occurring in Italy: the alborella Alburnus arborella in northern Italy and the vulturino Alburnus albidus in southern Italy. The study includes four populations of the alborella and 14 populations of the vulturino. A total of 57 haplotypes were identified; these could not be sorted into two reciprocally monophyletic clusters. Multiple phylogenetic methods and nested clade phylogeographical analysis consistently retrieved three well-supported clades, two of which contained both Northern and Southern Italian haplotypes. A third clade is limited to southern Italy. This clade is tentatively assigned to the vulturino. The placement in the same clade of northern and southern Italian haplotypes is explained in light of the introductions of fishes operated from northern to central and southern Italy. The origin of the vulturino dates back to the last two million years. This divergence time estimate identifies the Pleistocene confluences between adjacent river basins along the Adriatic slope of the Italian peninsula and their subsequent isolation as the cause that triggered the diversification of the genus in the area. The existence of a clade endemic to southern Italy supports the recognition of the area as a new peri-Mediterranean ichthyogeographic district, the borders of which correspond to the northern and southern edges of the vulturino range. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0022-1112 U6 - https://doi.org/10.1111/j.1095-8649.2009.02357.x SN - 0022-1112 ER - TY - JOUR A1 - Pfeifer, Marion A1 - Schatz, Bertrand A1 - Picó, F. Xavier A1 - Passalacqua, Nicodemo G. A1 - Fay, Michael F. A1 - Carey, Pete D. A1 - Jeltsch, Florian T1 - Phylogeography and genetic structure of the orchid "Himantoglossum hircinum" (L.) Spreng. across its European central-marginal gradient N2 - Aim This study aims to link demographic traits and post-glacial recolonization processes with genetic traits in Himantoglossum hircinum (L.) Spreng (Orchidaceae), and to test the implications of the central-marginal concept (CMC) in Europe. Location Twenty sites covering the entire European distribution range of this species. Methods We employed amplified fragment length polymorphism (AFLP) markers and performed a plastid microsatellite survey to assess genetic variation in 20 populations of H. hircinum located along central-marginal gradients. We measured demographic traits to assess population fitness along geographical gradients and to test for correlations between demographic traits and genetic diversity. We used genetic diversity indices and analyses of molecular variance (AMOVA) to test hypotheses of reduced genetic diversity and increased genetic differentiation and isolation from central to peripheral sites. We used Bayesian simulations to analyse genetic relationships among populations. Results Genetic diversity decreased significantly with increasing latitudinal and longitudinal distance from the distribution centre when excluding outlying populations. The AMOVA revealed significant genetic differentiation among populations (F-ST = 0.146) and an increase in genetic differentiation from the centre of the geographical range to the margins (except for the Atlantic group). Population fitness, expressed as the ratio N-R/N, decreased significantly with increasing latitudinal distance from the distribution centre. Flower production was lower in most eastern peripheral sites. The geographical distribution of microsatellite haplotypes suggests post-glacial range expansion along three major migratory pathways, as also supported by individual membership fractions in six ancestral genetic clusters (C1-C6). No correlations between genetic diversity (e.g. diversity indices, haplotype frequency) and population demographic traits were detected. Main conclusions Reduced genetic diversity and haplotype frequency in H. hircinum at marginal sites reflect historical range expansions. Spatial variation in demographic traits could not explain genetic diversity patterns. For those sites that did not fit into the CMC, the genetic pattern is probably masked by other factors directly affecting either demography or population genetic structure. These include post-glacial recolonization patterns and changes in habitat suitability due to climate change at the northern periphery. Our findings emphasize the importance of distinguishing historical effects from those caused by geographical variation in population demography of species when studying evolutionary and ecological processes at the range margins under global change. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/117963685/home U6 - https://doi.org/10.1111/j.1365-2699.2009.02168.x SN - 0305-0270 ER - TY - JOUR A1 - Timmermann, Mirna A1 - Plath, Martin T1 - Phototactic response and light sensitivity in an epigean and a hypogean population of a barb (Garra barreimiae, Cyprinidae) N2 - We investigated the response of two populations of the barb Garra barreimiae to different light intensities (0.5-2000 lx) from a light source. Adults of both the surface (epigean) and cave (hypogean) G. barreimiae populations show photophobic behavior. A photophobic response in the cave form was seen only at higher light intensities because the cavefish are eyeless and rely on extra-retinal light receptors to detect light. In contrast, juveniles (surface and cave) showed photophilic behavior, and their preference for the photic zone of the test tank decreased with increasing age. We discuss the potential role played by photophobic behavior for the colonization of caves by previously surface- dwelling fishes. Y1 - 2009 UR - http://www.springerlink.com/content/102847 U6 - https://doi.org/10.1007/s10452-008-9173-z SN - 1386-2588 ER - TY - THES A1 - Chen, Yanmei T1 - Phosphoproteomic study to assess signaling pathways mediating response to plant hormone and 2DOG treatments of "Arabidopsis thaliana" cell suspension cultures Y1 - 2009 CY - Potsdam ER - TY - JOUR A1 - Barbirz, Stefanie A1 - Becker, Marion A1 - Freiberg, Alexander A1 - Seckler, Robert T1 - Phage tailspike proteins with beta-solenoid fold as thermostable carbohydrate binding materials N2 - We have investigated the stability of three tailspike proteins (TSPs) from bacteriophages Sf6, P22, and HK620. Tailspikes are rod-like homotrimers with comparable beta-solenoid folds and similarly high kinetic stability in spite of different amino acid sequences. As tailspikes bind polysaccharides to recognize the bacterial host cell, their stability is required for maintenance of bacteriophage infectivity under harsh extracellular conditions. They resist denaturation by SDS at ambient temperature and their unfolding is slow even in 6 m guanidinium hydrochloride (GdmHCl). This makes them interesting candidates for very stable carbohydrate binding protein materials. Y1 - 2009 UR - http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291616-5195 U6 - https://doi.org/10.1002/mabi.200800278 SN - 1616-5187 ER - TY - JOUR A1 - Abercrombie, Laura Good A1 - Anderson, Cynthia M. A1 - Baldwin, Bruce G. A1 - Bang, In-Chul A1 - Beldade, Ricardo A1 - Bernardi, Giacomo A1 - Boubou, Angham A1 - Branca, Antoine A1 - Bretagnolle, Francois A1 - Bruford, Michael W. A1 - Buonamici, Anna A1 - Burnett, Robert K. A1 - Canal, D. A1 - Cardenas, H. A1 - Caullet, Coraline A1 - Chen, S. Y. A1 - Chun, Y. J. A1 - Cossu, C. A1 - Crane, Charles F. A1 - Cros-Arteil, Sandrine A1 - Cudney-Bueno, Richard A1 - Danti, Roberto A1 - Davila, José Antonio A1 - Della Rocca, Gianni A1 - Dobata, Shigeto A1 - Dunkle, Larry D. A1 - Dupas, Stephane and others T1 - Permanent genetic resources added to molecular ecology resources database 1 January 2009-30 April 2009 N2 - This article documents the addition of 283 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Agalinis acuta; Ambrosia artemisiifolia; Berula erecta; Casuarius casuarius; Cercospora zeae-maydis; Chorthippus parallelus; Conyza canadensis; Cotesia sesamiae; Epinephelus acanthistius; Ficedula hypoleuca; Grindelia hirsutula; Guadua angustifolia; Leucadendron rubrum; Maritrema novaezealandensis; Meretrix meretrix; Nilaparvata lugens; Oxyeleotris marmoratus; Phoxinus neogaeus; Pristomyrmex punctatus; Pseudobagrus brevicorpus; Seiridium cardinale; Stenopsyche marmorata; Tetranychus evansi and Xerus inauris. These loci were cross-tested on the following species: Agalinis decemloba; Agalinis tenella; Agalinis obtusifolia; Agalinis setacea; Agalinis skinneriana; Cercospora zeina; Cercospora kikuchii; Cercospora sorghi; Mycosphaerella graminicola; Setosphaeria turcica; Magnaporthe oryzae; Cotesia flavipes; Cotesia marginiventris; Grindelia Xpaludosa; Grindelia chiloensis; Grindelia fastigiata; Grindelia lanceolata; Grindelia squarrosa; Leucadendron coniferum; Leucadendron salicifolium; Leucadendron tinctum; Leucadendron meridianum; Laodelphax striatellus; Sogatella furcifera; Phoxinus eos; Phoxinus rigidus; Phoxinus brevispinosus; Phoxinus bicolor; Tetranychus urticae; Tetranychus turkestani; Tetranychus ludeni; Tetranychus neocaledonicus; Tetranychus amicus; Amphitetranychus viennensis; Eotetranychus rubiphilus; Eotetranychus tiliarium; Oligonychus perseae; Panonychus citri; Bryobia rubrioculus; Schizonobia bundi; Petrobia harti; Xerus princeps; Spermophilus tridecemlineatus and Sciurus carolinensis. Y1 - 2009 UR - http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291755-0998 U6 - https://doi.org/10.1111/j.1755-0998.2009.02746.x SN - 1755-098X ER - TY - THES A1 - Nikolovski, Nino T1 - Pectin: New insights from an old polymer through pectinase-based genetic screens T1 - Pektin: Neue Einblicke in ein altes Polymer durch Pektinase-basierte genetische Screens N2 - Pectic polysaccharides, a class of plant cell wall polymers, form one of the most complex networks known in nature. Despite their complex structure and their importance in plant biology, little is known about the molecular mechanism of their biosynthesis, modification, and turnover, particularly their structure-function relationship. One way to gain insight into pectin metabolism is the identification of mutants with an altered pectin structure. Those were obtained by a recently developed pectinase-based genetic screen. Arabidopsis thaliana seedlings grown in liquid medium containing pectinase solutions exhibited particular phenotypes: they were dwarfed and slightly chlorotic. However, when genetically different A. thaliana seed populations (random T-DNA insertional populations as well as EMS-mutagenized populations and natural variations) were subjected to this treatment, individuals were identified that exhibit a different visible phenotype compared to wild type or other ecotypes and may thus contain a different pectin structure (pec-mutants). After confirming that the altered phenotype occurs only when the pectinase is present, the EMS mutants were subjected to a detailed cell wall analysis with particular emphasis on pectins. This suite of mutants identified in this study is a valuable resource for further analysis on how the pectin network is regulated, synthesized and modified. Flanking sequences of some of the T-DNA lines have pointed toward several interesting genes, one of which is PEC100. This gene encodes a putative sugar transporter gene, which, based on our data, is implicated in rhamnogalacturonan-I synthesis. The subcellular localization of PEC100 was studied by GFP fusion and this protein was found to be localized to the Golgi apparatus, the organelle where pectin biosynthesis occurs. Arabidopsis ecotype C24 was identified as a susceptible one when grown with pectinases in liquid culture and had a different oligogalacturonide mass profile when compared to ecotype Col-0. Pectic oligosaccharides have been postulated to be signal molecules involved in plant pathogen defense mechanisms. Indeed, C24 showed elevated accumulation of reactive oxygen species upon pectinase elicitation and had altered response to the pathogen Alternaria brassicicola in comparison to Col-0. Using a recombinant inbred line population three major QTLs were identified to be responsible for the susceptibility of C24 to pectinases. In a reverse genetic approach members of the qua2 (putative pectin methyltransferase) family were tested for potential target genes that affect pectin methyl-esterification. The list of these genes was determined by in silico study of the pattern of expression and co-expression of all 34 members of this family resulting in 6 candidate genes. For only for one of the 6 analyzed genes a difference in the oligogalacturonide mass profile was observed in the corresponding knock-out lines, confirming the hypothesis that the methyl-esterification pattern of pectin is fine tuned by members of this gene family. This study of pectic polysaccharides through forward and reverse genetic screens gave new insight into how pectin structure is regulated and modified, and how these modifications could influence pectin mediated signalling and pathogenicity. N2 - Pektin Polysaccharide, eine Klasse pflanzlicher Zellwand Polymere, formen eine der komplexesten natürlichen Strukturen. Trotz seiner immensen Bedeutung in der Biologie der Pflanzen sind die Kenntisse über die molekularen Mechanismen der Pektin Biosynthese, dessen Modifikation und Abbau überraschend gering. Eine Möglichkeit neue Einblicke in den pflanzlichen Pektin Metabolismus zu erhalten, ist die Identifizierung von Mutanten mit veränderter Pektinstruktur. Solche Mutanten konnten durch ein neuatiges Selektionsverfahren gefunden werden. Zieht man Keimlinge der Ackerschmalwand (Arabidopsis thaliana) in Flüssigmedium mit Pektinase an, so lässt sich ein typischer Phänotyp beobachten: Die Pflanzen sind kleinwüchsig und leicht chlorotisch. Diesem Verfahren wurden Populationen verschiedener Genotypen (Insertions Linien, EMS Mutanten, natürlich vorkommende Varianten) ausgesetzt. Auf diese Weise wurden Individuen identifiziert, die gegenüber der Pektinase Behandlung eine verminderte oder erhöhte Resistenz aufweisen, was auf eine veränderte Pektinstruktur hindeutet. Die EMS Mutanten wurden einer detaillierten Zellwand Analyse unterzogen. die so in dieser Arbeit identifizierte Kollektion von Mutanten stellt eine wertvolle Ressource für weitere Forschungsansätze zur Regulation, Biosynthese und Modifikation des Pektins dar. Die Lokalisation der Insertionen in den T-DNA Linien führte zur Identifikation interessanter Gene, zu denen der putative Zuckertransporter PEC100 gehört. Dieses Gen steht vermutlich in Verbindung mit der Synthese von Rhamnogalakturonan-I, einem Bestandteil des Pektins. In dieser Arbeit konnte PEC100 im Golgi Apparat, dem Ort der Pektin Biosynthese, lokalisiert werden. Die natürlich vorkommende Variante C24 ist besonders empfindlich gegenüber der Pektinase. Diese Empfindlichkeit konnte anhand rekombinanter Inzucht Linien auf drei bedeutende quantitative Merkmalsloci (QTL) eingegrenzt werden. C24 zeigte zudem ein gegenüber der Referenz verändertes Massenprofil der Oligogalakturonide. Diese werden derzeit als Signalmoleküle in der pflanzlichen Pathogenabwehr diskutiert, was mit der in dieser Arbeit geseigten Resistenz von C24 gegenüber Schwarzfleckigkeit verursachende Pilz (Alternaria brassicicola) korreliert. In einem revers-genetischen Ansatz wurden zudem Mitglieder der Pektin Methyltransferase Familie als potentielle Enzyme getestet, die die Pektin Methylesterifikation beeinflussen könnten. Diese Mutation in einer dieser Methyltransferasen führte zu Veränderungen des Oligogalakturonid Massenprofils. Dies bestätigt die Hypothese, dass Mitglieder dieser Genfamilie an der Regulation der Methylesterifikation von Pektin beteiligt sind. Die vorliegende Studie, in der ein genetishen Selektionverfahren und Methoden der reversen Genetik kombiniert wurden, hat neue Einblicke in die Regulation und Modifikation von Pektin geliefert. KW - Pektin KW - Pektinase KW - genetischer Screen KW - Arabidopsis thaliana KW - Zellwand KW - pectin KW - pectinase KW - genetic screen KW - Arabidopsis thaliana KW - cell wall Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-35255 ER - TY - JOUR A1 - Pinkernelle, Josephine A1 - Abraham, Andreas A1 - Seidel, Katja A1 - Braun, Katharina T1 - Paternal deprivation induces dendritic and synaptic changes and hemispheric asymmetry of pyramidal neurons in the somatosensory cortex N2 - Similar to maternal care, paternal care is a source of neonatal sensory stimulation, which in primates and rodents has been shown to be essential for developing structure and function of sensory cortices. The aim of our study in the biparental rodent Octodon degus was to assess the impact of paternal deprivation on dendritic and synaptic development in the somatosensory cortex. We (i) quantified the amount of paternal care in relation to total parental investment and (ii) compared dendritic and synaptic development of pyramidal neurons in the somatosensory cortex of animals raised by a single mother or by both parents. On the behavioral level we show that paternal care comprises 37% of total parent-offspring interactions, and that the somatosensory stimulation provided by the fathers primarily consists of huddling, licking/grooming, and playing. On the morphological level we found that, compared with offspring raised by both parents (mother and father), the father-deprived animals displayed significantly reduced spine numbers on the basal dendrites of pyramidal neurons. Furthermore, paternal deprivation induces hemispheric asymmetry of the dendritic morphology of somatosensory pyramidal neurons. Father-deprived animals show shorter and less complex basal dendrites in the left somatosensory cortex compared with the right hemisphere. These findings indicate that paternal deprivation results in delayed or retarded dendritic and synaptic development of somatosensory circuits. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/114030483 U6 - https://doi.org/10.1002/Dneu.20726 SN - 1932-8451 ER - TY - THES A1 - Steinhauser, Marie-Caroline T1 - Optimisation and application of enzyme activity assays to characterise carbohydrate metabolism in the fruit of different tomato genotypes Y1 - 2009 CY - Potsdam ER - TY - JOUR A1 - Bleidorn, Christoph A1 - Hill, Natascha A1 - Erséus, Christer A1 - Tiedemann, Ralph T1 - On the role of character loss in orbiniid phylogeny (Annelida) : molecules vs. morphology N2 - Orbiniid phylogeny is matter of debate and incongruence between hypothesis based on molecules and morphology has been repeatedly reported. Moreover, the phylogenetic position of the "oligochaetoid polychaetes" of the taxon Questa varies between morphological and molecular cladistic analyses. Here, we present a nearly complete mitochondrial genome of Questa ersei. The mitochondrial gene order is roughly identical to known orbiniid taxa. Several translocations of tRNAs are unique to Orbiniidae and Questa when compared to other annelid mitochondrial genomes. Additionally, we assembled sequence data of six genes (18S, 16S, cox1, cox3, nad1, nad4) for a representative orbiniid taxon sampling and analysed all data in concatenation using Maximum Likelihood and Bayesian inference. For comparison with morphology we compiled a morphological data matrix for all taxa included in our molecular analyses. Our results strongly support a close relationship of Questa with orbiniids (sequence data, gene order, an 18 bp indel, morphology), and a position nested within orbiniids is recovered in our sequence based analyses. We demonstrate remarkable incongruence of most included morphological characters with the recovered best ML tree and suppose that repeated independent character loss might be an explanation. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/10557903 U6 - https://doi.org/10.1016/j.ympev.2009.03.022 SN - 1055-7903 ER - TY - GEN A1 - Bleidorn, Christoph A1 - Podsiadlowski, Lars A1 - Zhong, Min A1 - Eeckhaut, Igor A1 - Hartmann, Stefanie A1 - Halanych, Kenneth M. A1 - Tiedemann, Ralph T1 - On the phylogenetic position of Myzostomida : can 77 genes get it wrong? N2 - Background: Phylogenomic analyses recently became popular to address questions about deep metazoan phylogeny. Ribosomal proteins (RP) dominate many of these analyses or are, in some cases, the only genes included. Despite initial hopes, hylogenomic analyses including tens to hundreds of genes still fail to robustly place many bilaterian taxa. Results: Using the phylogenetic position of myzostomids as an example, we show that phylogenies derived from RP genes and mitochondrial genes produce incongruent results. Whereas the former support a position within a clade of platyzoan taxa, mitochondrial data recovers an annelid affinity, which is strongly supported by the gene order data and is congruent with morphology. Using hypothesis testing, our RP data significantly rejects the annelids affinity, whereas a platyzoan relationship is significantly rejected by the mitochondrial data. Conclusion: We conclude (i) that reliance of a set of markers belonging to a single class of macromolecular complexes might bias the analysis, and (ii) that concatenation of all available data might introduce conflicting signal into phylogenetic analyses. We therefore strongly recommend testing for data incongruence in phylogenomic analyses. Furthermore, judging all available data, we consider the annelid affinity hypothesis more plausible than a possible platyzoan affinity for myzostomids, and suspect long branch attraction is influencing the RP data. However, this hypothesis needs further confirmation by future analyses. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 123 KW - Cirriferum myzostomida KW - Mitochondrial genomes KW - Transfer-rna KW - Data sets KW - Sequence Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44893 ER - TY - JOUR A1 - Riesch, Rüdiger A1 - Tobler, Michael A1 - Plath, Martin A1 - Schlupp, Ingo T1 - Offspring number in a livebearing fish (Poecilia mexicana, Poeciliidae) : reduced fecundity and reduced plasticity in a population of cave mollies N2 - Life history traits within species often vary among different habitats. We measured female fecundity in mollies (Poecilia mexicana) from a H2S-rich cave and from a neighbouring surface habitat, as well as in laboratory-reared individuals of both populations raised in either light or continuous darkness. Compared to conspecifics from surface habitats, cave-dwelling P. mexicana had reduced fecundity (adjusted for size) in the field. In the laboratory, the fecundity of surface mollies was higher in light than in darkness, whereas fecundity in the cave mollies was almost unaffected by the ambient light conditions. Our results suggest a heritable component to the reduction in fecundity in female cave mollies. Moreover, the reduced plasticity in fecundity of cave mollies in response to light conditions might be an example of genetic assimilation or channelling of a life history trait in a population invading a new environment. Y1 - 2009 UR - http://www.springerlink.com/content/102877 U6 - https://doi.org/10.1007/s10641-008-9392-0 SN - 0378-1909 ER - TY - JOUR A1 - Schröder, Christiane A1 - Bleidorn, Christoph A1 - Hartmann, Stefanie A1 - Tiedemann, Ralph T1 - Occurrence of Can-SINEs and intron sequence evolution supports robust phylogeny of pinniped carnivores and their terrestrial relatives N2 - Investigating the dog genome we found 178965 introns with a moderate length of 200-1000 bp. A screening of these sequences against 23 different repeat libraries to find insertions of short interspersed elements (SINEs) detected 45276 SINEs. Virtually all of these SINEs (98%) belong to the tRNA-derived Can-SINE family. Can-SINEs arose about 55 million years ago before Carnivora split into two basal groups, the Caniformia (doglike carnivores) and the Feliformia (cat-like carnivores). Genome comparisons of dog and cat recovered 506 putatively informative SINE loci for caniformian phylogeny. In this study we show how to use such genome information of model organisms to research the phylogeny of related non-model species of interest. Investigating a dataset including representatives of all major caniformian lineages, we analysed 24 randomly chosen loci for 22 taxa. All loci were amplifiable and revealed 17 parsimony- informative SINE insertions. The screening for informative SINE insertions yields a large amount of sequence information, in particular of introns, which contain reliable phylogenetic information as well. A phylogenetic analysis of intron- and SINE sequence data provided a statistically robust phylogeny which is congruent with the absence/presence pattern of our SINE markers. This phylogeny strongly supports a sistergroup relationship of Musteloidea and Pinnipedia. Within Pinnipedia, we see strong support from bootstrapping and the presence of a SINE insertion for a sistergroup relationship of the walrus with the Otariidae. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/03781119 U6 - https://doi.org/10.1016/j.gene.2009.06.012 SN - 0378-1119 ER - TY - GEN A1 - Heinken, Thilo A1 - Winkler, Eckart T1 - Non-random dispersal by ants : long-term field data versus model predictions of population spread of a forest herb N2 - Myrmecochory, i.e. dispersal of seeds by ants towards and around their nests, plays an important role in temperate forests. Yet hardly any study has examined plant population spread over several years and the underlying joint contribution of a hierarchy of dispersal modes and plant demography. We used a seed-sowing approach with three replicates to examine colonization patterns of Melampyrum pratense, an annual myrmecochorous herb, in a mixed Scots pine forest in northeastern Germany. Using a spatially explicit individualbased (SEIB) model population patterns over 4 years were explained by short-distance transport of seeds by small ant species with high nest densities, resulting in random spread. However, plant distributions in the field after another 4 years were clearly deviating from model predictions. Mean annual spread rate increased from 0.9 m to 5.1 m per year, with a clear inhomogeneous component. Obviously, after a lag-phase of several years, non-random seed dispersal by large red wood ants (Formica rufa) was determining the species’ spread, thus resulting in stratified dispersal due to interactions with different-sized ant species. Hypotheses on stratified dispersal, on dispersal lag, and on non-random dispersal were verified using an extended SEIB model, by comparison of model outputs with field patterns (individual numbers, population areas, and maximum distances). Dispersal towards red wood ant nests together with seed loss during transport and redistribution around nests were essential features of the model extension. The observed lag-phase in the initiation of non-random, medium-distance transport was probably due to a change of ant behaviour towards a new food source of increasing importance, being a meaningful example for a lag-phase in local plant species invasion. The results demonstrate that field studies should check model predictions wherever possible. Future research will show whether or not the M. pratense–ant system is representative for migration patterns of similar animal dispersal systems after having crossed range edges by long-distance dispersal events. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 151 KW - Melampyrum pratense KW - population dynamics KW - seed dispersal KW - non-random dispersal KW - plant-animal interaction Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-46482 ER - TY - BOOK A1 - Braun, Uwe A1 - Ale-Agha, Nosratollah A1 - Bolay, Adrien A1 - Boyle, H. A1 - Brielmaier-Liebetanz, U. A1 - Emgenbroich, D. A1 - Kruse, J. A1 - Kummer, Volker T1 - New records of powdery mildew fungi (Erysiphaceae) N2 - The conidial stage and chasmothecia of Golovinomyces orontii have been found in Germany on cultivated Limnanthes douglasii. A powdery mildew anamorph found in the Netherlands on Malva alcea agrees morphologically with the Oidium of the latter species as well. Golovinomyces sp. (anamorph) on Parthenium integrifolium is described and discussed. Erysiphe sp. has been found in Germany on Acer opalus, and E. magnifica is recorded from Germany and Switzerland on Magnolia spp. Oidium passiflorae is new to Switzerland. An Oidium morphologically agreeing with the anamorph of Podosphaera aphanis has recently been collected on Exacum macranthum cultivated in a greenhouse, and conidiophores and conidia of a species of Podosphaera sect. Sphaerotheca subsect. Magnicellulatae (P. fusca complex) on Phlox paniculata and Polemonium caeruleum have been found in Germany. Y1 - 2009 ER - TY - JOUR A1 - Sharma, Reeta A1 - Stuckas, Heiko A1 - Bhaskar, Ranjana A1 - Rajput, Sandeep A1 - Khan, Imran A1 - Goyal, Surendra Prakash A1 - Tiedemann, Ralph T1 - mtDNA indicates profound population structure in Indian tiger (Panthera tigris tigris) N2 - We analyzed mtDNA polymorphisms (parts of control region, ND5, ND2, Cytb, 12S, together 902 bp) in 59 scat and 18 tissue samples from 13 Indian populations of the critically endangered Indian tiger (Panthera tigris tigris), along with zoo animals as reference. Northern tiger populations exhibit two unique haplotypes suggesting genetic isolation. Western populations from Sariska (extinct in 2004) and Ranthambore are genetically similar, such that Ranthambore could serve as a source for reintroduction in Sariska. Zoo populations maintain mitochondrial lineages that are rare or absent in the wild. Y1 - 2009 UR - http://www.springerlink.com/content/105709 U6 - https://doi.org/10.1007/s10592-008-9568-3 SN - 1566-0621 ER - TY - THES A1 - Nagel, Katja T1 - Morphologische Variabilität in menschlichen Populationen als Grundlage industrieller Produktgestaltung - Entwicklung einer Methode zur anthropologisch-ergonomischen Bewertung des Fahrzeuginnenraums Y1 - 2009 CY - Potsdam ER - TY - THES A1 - Feige, Katharina T1 - Molecular ecological analysis of methanogenic communities in terrestrial and submarine permafrost deposits of Siberian Laptev Sea area T1 - Molekular-ökologische Analyse von methanogenen Gemeinschaften im terrestrischen und submarinen Permafrost im Laptevseegebiet N2 - Despite general concern that the massive deposits of methane stored under permafrost underground and undersea could be released into the atmosphere due to rising temperatures attributed to global climate change, little is known about the methanogenic microorganisms in permafrost sediments, their role in methane emissions, and their phylogeny. The aim of this thesis was to increase knowledge of uncultivated methanogenic microorganisms in submarine and terrestrial permafrost deposits, their community composition, the role they play with regard to methane emissions, and their phylogeny. It is assumed that methanogenic communities in warmer submarine permafrost may serve as a model to anticipate the response of methanogenic communities in colder terrestrial permafrost to rising temperatures. The compositions of methanogenic communities were examined in terrestrial and submarine permafrost sediment samples. The submarine permafrost studied in this research was 10°C warmer than the terrestrial permafrost. By polymerase chain reaction (PCR), DNA was extracted from each of the samples and analyzed by molecular microbiological methods such as PCR-DGGE, RT-PCR, and cloning. Furthermore, these samples were used for in vitro experiment and FISH. The submarine permafrost analysis of the isotope composition of CH4 suggested a relationship between methane content and in situ active methanogenesis. Furthermore, active methanogenesis was proven using 13C-isotope measurements of methane in submarine permafrost sediment with a high TOC value and a high methane concentration. In the molecular-microbiological studies uncultivated lines of Methanosarcina, Methanomicrobiales, Methanobacteriacea and the Groups 1.3 and Marine Benthic from Crenarchaeota were found in all submarine and terrestrial permafrost samples. Methanosarcina was the dominant group of the Archaea in all submarine and terrestrial permafrost samples. The archaeal community composition, in particular, the methanogenic community composition showed diversity with changes in temperatures. Furthermore, cell count of methanogens in submarine permafrost was 10 times higher than in terrestrial permafrost. In vitro experiments showed that methanogens adapt quickly and well to higher temperatures. If temperatures rise due to climate change, an increase in methanogenic activity can be expected as long as organic material is sufficiently available and qualitatively adequate. N2 - Trotz allgemeiner Bedenken, dass auf Grund des Temperaturanstieges im Zusammenhang mit der globalen Klimaerwärmung große Mengen des in terrestrischen und submarinen Permafrostsedimenten gespeicherten Methans freigesetzt werden könnte, ist bisher wenig über die in diesen Böden lebenden methanogenen Mikroorganismen, ihre Phylogenese und sowie ihre Bedeutung hinsichtlich der Methanemissionen bekannt. Das Ziel dieser Doktorarbeit war die Erweiterung der bisherigen Kenntnisse über unkultivierte methanogene Mikroorganismen in submarinen und terrestrischen Sedimentablagerungen, die Zusammensetzung ihrer Lebensgemeinschaft, ihrer Phylogenese und ihrer Bedeutung bei der Emission von Methan. Es wird vermutet, dass methanogene Gemeinschaften submarines Permafrostes zur Erstellung von Modellen genutzt werden können, um Aussagen bezüglich potenzieller Reaktionen methanogener Gemeinschaften des kälteren terrestrischen Permafrostes auf steigende Temperaturen, zu ermöglichen. Die Zusammensetzung der methanogenen Gemeinschaft wurde in terrestrischen und submarinen Permafrostproben untersucht. Der im Rahmen dieser Forschungsarbeit untersuchte submarine Permafrost wies eine im Vergleich zum terrestrischen Permafrost um circa 10°C höhere Temperatur auf. Mittels Polymerasenkettenreaktion (PCR) wurde von jeder der Proben DNA extrahiert und mittels weiterer molekular-mikrobiologischen Methoden wie DGGE, RT-PCR und Klonierung analysiert. Des Weiteren wurden die Proben für in vitro Experimente und Zellzählungen (DAPI und FISH) verwendet. Die Analyse der Isotopenzusammensetzung von CH4 in submarinen Permafrostsedimenten ließ einen Zusammenhang zwischen Methangehalt und aktiver in situ Methanogenese vermuten. Überdies konnte aktive Methanogenese, mittels 13C-Isotopenmessungen von Methan in submarinem Permafrostsediment mit hohem TOC-Wert und hoher Methankonzentration, bewiesen werden. Im Rahmen der molekular-mikrobiologischen Untersuchungen wurden in allen submarinen und terrestrischen Permafrostproben unkultivierte Linien von Methanosarcina, Methanomicrobiales, Methanobacteriacea und den Gruppen 1.3 und Marine Benthic von Crenarchaeota gefunden. Methanosarcina war in allen submarinen und terrestrischen Permafrostproben die dominierende Gruppe der Archaeen. Die Zusammensetzung der archaealen Gemeinschaft, insbesondere die Zusammensetzung der methanogenen Gemeinschaft, variierte zwischen den submarinen und terrestrischen Proben. Des Weiteren fand sich bei der Zellzählung der Methanogenen im submarinen Permafrost eine 10-fach höhere Zellzahl als im terrestrischen Permafrost. Die in vitro Experimente zeigten, dass Methanogene sich schnell und gut an höhere Temperaturen anpassen können. Im Falle weiter steigender Temperaturen auf Grund der Klimaveränderungen, kann – bei ausreichender Verfügbarkeit und Qualität organischen Materials – mit einer Zunahme der methanogenen Aktivität gerechnet werden. KW - methanogene Archaea KW - Permafrost KW - submarin KW - terrestrisch KW - methanogenic archaea KW - permafrost KW - submarine KW - terrestrial Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-37998 ER - TY - GEN A1 - Blenau, Wolfgang A1 - Rotte, Cathleen A1 - Krach, Christian A1 - Balfanz, Sabine A1 - Baumann, Arnd A1 - Walz, Bernd T1 - Molecular characterization and localization of the first tyramine receptor of the American cockroach (Periplaneta americana) N2 - The phenolamines octopamine and tyramine control, regulate, and modulate many physiological and behavioral processes in invertebrates. Vertebrates possess only small amounts of both substances, and thus, octopamine and tyramine, together with other biogenic amines, are referred to as “trace amines.” Biogenic amines evoke cellular responses by activating G-protein-coupled receptors. We have isolated a complementary DNA (cDNA) that encodes a biogenic amine receptor from the American cockroach Periplaneta americana, viz., Peatyr1, which shares high sequence similarity to members of the invertebrate tyramine-receptor family. The PeaTYR1 receptor was stably expressed in human embryonic kidney (HEK) 293 cells, and its ligand response has been examined. Receptor activation with tyramine reduces adenylyl cyclase activity in a dose-dependent manner (EC50 350 nM). The inhibitory effect of tyramine is abolished by co-incubation with either yohimbine or chlorpromazine. Receptor expression has been investigated by reverse transcription polymerase chain reaction and immunocytochemistry. The mRNA is present in various tissues including brain, salivary glands, midgut, Malpighian tubules, and leg muscles. The effect of tyramine on salivary gland acinar cells has been investigated by intracellular recordings, which have revealed excitatory presynaptic actions of tyramine. This study marks the first comprehensive molecular, pharmacological, and functional characterization of a tyramine receptor in the cockroach. KW - Biogenic amine KW - cellular signaling KW - G-protein-coupled receptor KW - octopamine KW - salivary gland Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44335 ER - TY - THES A1 - Krebs, Jonas T1 - Molecular and physiological characterisation of selected DOF transcription factors in the model plant Arabidopsis thaliana T1 - Molekulare und physiologische Charakterisierung ausgewählter DOF Transkriptionsfaktoren in der Modellpflanze Arabidopsis thaliana N2 - About 2,000 of the more than 27,000 genes of the genetic model plant Arabidopsis thaliana encode for transcription factors (TFs), proteins that bind DNA in the promoter region of their target genes and thus act as transcriptional activators and repressors. Since TFs play essential roles in nearly all biological processes, they are of great scientific and biotechnological interest. This thesis concentrated on the functional characterisation of four selected members of the Arabidopsis DOF-family, namely DOF1.2, DOF3.1, DOF3.5 and DOF5.2, which were selected because of their specific expression pattern in the root tip, a region that comprises the stem cell niche and cells for the perception of environmental stimuli. DOF1.2, DOF3.1 and DOF3.5 are previously uncharacterized members of the Arabidopsis DOF-family, while DOF5.2 has been shown to be involved in the phototrophic flowering response. However, its role in root development has not been described so far. To identify biological processes regulated by the four DOF proteins in detail, molecular and physiological characterization of transgenic plants with modified levels of DOF1.2, DOF3.1, DOF3.5 and DOF5.2 expression (constitutive and inducible over-expression, artificial microRNA) was performed. Additionally expression patterns of the TFs and their target genes were analyzed using promoter-GUS lines and publicly available microarray data. Finally putative protein-protein interaction partners and upstream regulating TFs were identified using the yeast two-hybrid and one-hybrid system. This combinatorial approach revealed distinct biological functions of DOF1.2, DOF3.1, DOF3.5 and DOF5.2 in the context of root development. DOF1.2 and DOF3.5 are specifically and exclusively expressed in the root cap, including the central root cap (columella) and the lateral root cap, organs which are essential to direct oriented root growth. It could be demonstrated that both genes work in the plant hormone auxin signaling pathway and have an impact on distal cell differentiation. Altered levels of gene expression lead to changes in auxin distribution, abnormal cell division patterns and altered root growth orientation. DOF3.1 and DOF5.2 share a specific expression pattern in the organizing centre of the root stem cell niche, called the quiescent centre. Both genes redundantly control cell differentiation in the root´s proximal meristem and unravel a novel transcriptional regulation pathway for genes enriched in the QC cells. Furthermore this work revealed a novel bipartite nuclear localisation signal being present in the protein sequence of the DOF TF family from all sequenced plant species. Summing up, this work provides an important input into our knowledge about the role of DOF TFs during root development. Future work will concentrate on revealing the exact regulatory networks of DOF1.2, DOF3.1, DOF3.5 and DOF5.2 and their possible biotechnological applications. N2 - Mehr noch als Tiere, die ihren Lebensraum unter widrigen Umständen verlassen können, sind Pflanzen mit einem festen Standort auf ihre Anpassungsfähigkeit angewiesen. Einen entscheidenden Beitrag dazu leistet die Genregulation, d.h. das gezielte An- und Ausschalten von Erbanlagen, den Genen. Vermittelt wird dieser Regulationsprozess unter anderem durch Transkriptionsfaktoren: Proteine, die die Fähigkeit besitzen, an bestimmte Regionen der Gene zu binden und damit deren Aktivität zu beeinflussen. In der Ackerschmalwand (Arabidopsis thaliana), die als Modellpflanze in der Genetik verwendet wird, existieren etwa 2000 solcher Transkriptionsfaktoren, eingeteilt in Familien, von denen einige auch in tierischen Organismen auftreten, andere pflanzenspezifisch sind. Auf Grund ihrer Funktion als wichtige Kontrollelemente sind sie von großem wissenschaftlichem und biotechnologischem Interesse. Im Rahmen dieser Doktorarbeit sollte die Funktion von vier pflanzenspezifischen Transkriptionsfaktoren, genannt DOF1.2, DOF3.1, DOF3.5 und DOF5.2, untersucht werden, welche durch ihre spezifische Aktivität in der Wurzelspitze der Ackerschmalwand identifiziert wurden. Um die Funktion dieser vier Regulatoren aufzuklären, wurden an der Modellpflanze gentechnische Veränderungen durchgeführt und die so veränderten, auch als transgen bezeichneten Pflanzen mit molekularbiologischen und physiologischen Methoden untersucht. Es konnte gezeigt werden, dass DOF1.2 und DOF3.5 eine wesentliche Funktion beim gerichteten Wurzelwachstum spielen und ein seitliches Wachsen der Wurzel aufgrund veränderter Umwelteinflüsse verhindern, bzw. hervorrufen können. Die beiden anderen Proteine DOF3.1 und DOF5.2 erfüllen ihre Funktion in der Stammzellnische der Wurzel. Vergleichbar mit tierischen Stammzellen sind auch pflanzliche Stammzellen nicht zu einem bestimmten Zelltyp herangereift, sondern verbleiben in einem sogenannten undifferenzierten Zustand. Es konnte gezeigt werden, dass DOF3.1 und DOF5.2 zum Erhalt dieses Zustands benötigt werden, da nach Inaktivierung beider Proteine Zellspezialisierungen auftreten, die bei gentechnisch unveränderten Pflanzen nicht auftreten. Desweiteren konnte in dieser Arbeit geklärt werden, welcher Proteinabschnitt der DOF-Proteine für ihren Transport in den Zellkern notwendig ist. Denn da die pflanzlichen Erbanlagen im Zellkern vorliegen, muss für eine Einflussnahme auf deren Aktivität zunächst ein Transport der Regulationsproteine in den Zellkern stattfinden. Zusammengenommen konnte mit dieser Doktorarbeit das Wissen über Transkriptionsfaktoren und Entwicklungsprozesse der Wurzel erheblich erweitert werden. Zudem ist die Grundlage für interessante zukünftige Arbeiten gelegt worden. Dabei wird es von zentraler Bedeutung sein, komplexe Regulationsnetzwerke verstehen zu lernen und durch gezielte Manipulationen biotechnologisch nutzen zu können. KW - DOF Transkriptionsfaktoren KW - Arabidopsis thaliana KW - Wurzel KW - Ruhezentrum KW - Columella KW - DOF transcription factors KW - Arabidopsis thaliana KW - root KW - quiescent center KW - columella Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41831 ER - TY - JOUR A1 - Treydte, Anna C. A1 - Heitkönig, Ignas M. A. A1 - Ludwig, Fulco T1 - Modelling ungulate dependence on higher quality forage under large trees in African savannahs N2 - In African savannahs, large trees improve grass quality, particularly in dry and nutrient poor areas. Enhanced below-canopy grass nutrients, such as nitrogen and phosphorus contents should therefore attract and benefit grazers. To predict whether ungulates really need these forage quality islands we focused on four grazer species, i.e., zebra, buffalo, wildebeest, and warthog, differing in body size and digestive system. We confronted literature estimations of their feeding requirements with forage availability and quality, observed in three South African savannah systems, through linear modelling. The model predicted the proportion of below-canopy grass that grazers should include in their diet to meet their nutritional requirements. During the wet season, the model predicted that all animals could satisfy their daily nutrient requirements when feeding on a combination of below- and outside-canopy grasses. However, wildebeest, having relatively high nutrient demands, could meet their nutrient requirements only by feeding almost exclusively below canopies. During the dry season, all animals could gain almost twice as much digestible protein when feeding on below - compared to outside-canopy forage. Nonetheless, only warthogs could satisfy their nutrient requirements - when feeding almost exclusively on below-canopy grasses. The other ungulate species could not meet their phosphorus demands by feeding at either site without exceeding their maximum fibre intake, indicating the unfavourable conditions during the dry season. We conclude that grazing ungulates, particularly warthog, zebra, and buffalo, actually depend on the available below-canopy grass resources. Our model therefore helps to quantify the importance of higher quality forage patches beneath savannah trees. The composition of grazer communities depending on below-canopy grasses can be anticipated if grazer food requirements and the abundance of large trees in savannahs are known. The model suggests that the conservation of large single-standing trees in savannahs is crucial for maintenance of locally grazing herbivores. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/14391791 U6 - https://doi.org/10.1016/j.baae.2008.03.003 SN - 1439-1791 ER - TY - BOOK A1 - Abel, Markus A1 - Holschneider, Matthias T1 - Modellierung und Datenbankanalyse komplexer Systeme Teil 9 : Vorlesung 2009-07-02 N2 - Komplexe Systeme reichen von "harten", physikalischen, wie Klimaphysik, Turbulenz in Fluiden oder Plasmen bis zu so genannten "weichen", wie man sie in der Biologie, der Physik weicher Materie, Soziologie oder Ökonomie findet. Die Ausbildung von Verständnis zu einem solchen System beinhaltet eine Beschreibung in Form von Statistiken und schlussendlich mathematischen Gleichungen. Moderne Datenanalyse stellt eine große Menge von Werkzeugen zur Analyse von Komplexität auf verschiedenen Beschreibungsebenen bereit. In diesem Kurs werden statistische Methoden mit einem Schwerpunkt auf dynamischen Systemen diskutiert und eingeübt. Auf der methodischen Seite werden lineare und nichtlineare Ansätze behandelt, inklusive der Standard-Werkzeuge der deskriptiven und schlussfolgernden Statistik, Wavelet Analyse, Nichtparametrische Regression und der Schätzung nichtlinearer Maße wie fraktaler Dimensionen, Entropien und Komplexitätsmaßen. Auf der Modellierungsseite werden deterministische und stochastische Systeme, Chaos, Skalierung und das Entstehen von Komplexität durch Wechselwirkung diskutiert - sowohl für diskrete als auch für ausgedehnte Systeme. Die beiden Ansätze werden durch Systemanalyse jeweils passender Beispiele vereint. Y1 - 2009 UR - http://info.ub.uni-potsdam.de/multimedia/show_projekt.php?projekt_id=44 PB - Univ.-Bibl. CY - Potsdam ER - TY - BOOK A1 - Abel, Markus A1 - Holschneider, Matthias T1 - Modellierung und Datenbankanalyse komplexer Systeme Teil 8 : Vorlesung 2009-06-25 N2 - Komplexe Systeme reichen von "harten", physikalischen, wie Klimaphysik, Turbulenz in Fluiden oder Plasmen bis zu so genannten "weichen", wie man sie in der Biologie, der Physik weicher Materie, Soziologie oder Ökonomie findet. Die Ausbildung von Verständnis zu einem solchen System beinhaltet eine Beschreibung in Form von Statistiken und schlussendlich mathematischen Gleichungen. Moderne Datenanalyse stellt eine große Menge von Werkzeugen zur Analyse von Komplexität auf verschiedenen Beschreibungsebenen bereit. In diesem Kurs werden statistische Methoden mit einem Schwerpunkt auf dynamischen Systemen diskutiert und eingeübt. Auf der methodischen Seite werden lineare und nichtlineare Ansätze behandelt, inklusive der Standard-Werkzeuge der deskriptiven und schlussfolgernden Statistik, Wavelet Analyse, Nichtparametrische Regression und der Schätzung nichtlinearer Maße wie fraktaler Dimensionen, Entropien und Komplexitätsmaßen. Auf der Modellierungsseite werden deterministische und stochastische Systeme, Chaos, Skalierung und das Entstehen von Komplexität durch Wechselwirkung diskutiert - sowohl für diskrete als auch für ausgedehnte Systeme. Die beiden Ansätze werden durch Systemanalyse jeweils passender Beispiele vereint. Y1 - 2009 UR - http://info.ub.uni-potsdam.de/multimedia/show_projekt.php?projekt_id=43 PB - Univ.-Bibl. CY - Potsdam ER - TY - BOOK A1 - Abel, Markus A1 - Holschneider, Matthias T1 - Modellierung und Datenbankanalyse komplexer Systeme Teil 7 : Vorlesung 2009-06-18 N2 - Komplexe Systeme reichen von "harten", physikalischen, wie Klimaphysik, Turbulenz in Fluiden oder Plasmen bis zu so genannten "weichen", wie man sie in der Biologie, der Physik weicher Materie, Soziologie oder Ökonomie findet. Die Ausbildung von Verständnis zu einem solchen System beinhaltet eine Beschreibung in Form von Statistiken und schlussendlich mathematischen Gleichungen. Moderne Datenanalyse stellt eine große Menge von Werkzeugen zur Analyse von Komplexität auf verschiedenen Beschreibungsebenen bereit. In diesem Kurs werden statistische Methoden mit einem Schwerpunkt auf dynamischen Systemen diskutiert und eingeübt. Auf der methodischen Seite werden lineare und nichtlineare Ansätze behandelt, inklusive der Standard-Werkzeuge der deskriptiven und schlussfolgernden Statistik, Wavelet Analyse, Nichtparametrische Regression und der Schätzung nichtlinearer Maße wie fraktaler Dimensionen, Entropien und Komplexitätsmaßen. Auf der Modellierungsseite werden deterministische und stochastische Systeme, Chaos, Skalierung und das Entstehen von Komplexität durch Wechselwirkung diskutiert - sowohl für diskrete als auch für ausgedehnte Systeme. Die beiden Ansätze werden durch Systemanalyse jeweils passender Beispiele vereint. Y1 - 2009 UR - http://info.ub.uni-potsdam.de/multimedia/show_projekt.php?projekt_id=42 PB - Univ.-Bibl. CY - Potsdam ER - TY - BOOK A1 - Abel, Markus A1 - Holschneider, Matthias T1 - Modellierung und Datenbankanalyse komplexer Systeme Teil 6 : Vorlesung 2009-06-11 N2 - Komplexe Systeme reichen von "harten", physikalischen, wie Klimaphysik, Turbulenz in Fluiden oder Plasmen bis zu so genannten "weichen", wie man sie in der Biologie, der Physik weicher Materie, Soziologie oder Ökonomie findet. Die Ausbildung von Verständnis zu einem solchen System beinhaltet eine Beschreibung in Form von Statistiken und schlussendlich mathematischen Gleichungen. Moderne Datenanalyse stellt eine große Menge von Werkzeugen zur Analyse von Komplexität auf verschiedenen Beschreibungsebenen bereit. In diesem Kurs werden statistische Methoden mit einem Schwerpunkt auf dynamischen Systemen diskutiert und eingeübt. Auf der methodischen Seite werden lineare und nichtlineare Ansätze behandelt, inklusive der Standard-Werkzeuge der deskriptiven und schlussfolgernden Statistik, Wavelet Analyse, Nichtparametrische Regression und der Schätzung nichtlinearer Maße wie fraktaler Dimensionen, Entropien und Komplexitätsmaßen. Auf der Modellierungsseite werden deterministische und stochastische Systeme, Chaos, Skalierung und das Entstehen von Komplexität durch Wechselwirkung diskutiert - sowohl für diskrete als auch für ausgedehnte Systeme. Die beiden Ansätze werden durch Systemanalyse jeweils passender Beispiele vereint. Y1 - 2009 UR - http://info.ub.uni-potsdam.de/multimedia/show_projekt.php?projekt_id=41 PB - Univ.-Bibl. CY - Potsdam ER - TY - BOOK A1 - Abel, Markus A1 - Holschneider, Matthias T1 - Modellierung und Datenbankanalyse komplexer Systeme Teil 10 : Vorlesung 2009-07-09 N2 - Komplexe Systeme reichen von "harten", physikalischen, wie Klimaphysik, Turbulenz in Fluiden oder Plasmen bis zu so genannten "weichen", wie man sie in der Biologie, der Physik weicher Materie, Soziologie oder Ökonomie findet. Die Ausbildung von Verständnis zu einem solchen System beinhaltet eine Beschreibung in Form von Statistiken und schlussendlich mathematischen Gleichungen. Moderne Datenanalyse stellt eine große Menge von Werkzeugen zur Analyse von Komplexität auf verschiedenen Beschreibungsebenen bereit. In diesem Kurs werden statistische Methoden mit einem Schwerpunkt auf dynamischen Systemen diskutiert und eingeübt. Auf der methodischen Seite werden lineare und nichtlineare Ansätze behandelt, inklusive der Standard-Werkzeuge der deskriptiven und schlussfolgernden Statistik, Wavelet Analyse, Nichtparametrische Regression und der Schätzung nichtlinearer Maße wie fraktaler Dimensionen, Entropien und Komplexitätsmaßen. Auf der Modellierungsseite werden deterministische und stochastische Systeme, Chaos, Skalierung und das Entstehen von Komplexität durch Wechselwirkung diskutiert - sowohl für diskrete als auch für ausgedehnte Systeme. Die beiden Ansätze werden durch Systemanalyse jeweils passender Beispiele vereint. Y1 - 2009 UR - http://info.ub.uni-potsdam.de/multimedia/show_projekt.php?projekt_id=45 PB - Univ.-Bibl. CY - Potsdam ER - TY - JOUR A1 - Neumann, Meina A1 - Mittelstaedt, Gerd A1 - Seduk, Farida A1 - Iobbi-Nivol, Chantal A1 - Leimkühler, Silke T1 - MocA is a specific cytidylyltransferase involved in molybdopterin cytosine dinucleotide biosynthesis in Escherichia coli N2 - We have purified and characterized a specific CTP: molybdopterin cytidylyltransferase for the biosynthesis of the molybdopterin (MPT) cytosine dinucleotide (MCD) cofactor in Escherichia coli. The protein, named MocA, shows 22% amino acid sequence identity to E. coli MobA, the specific GTP: molybdopterin guanylyltransferase for molybdopterin guanine dinucleotide biosynthesis. MocA is essential for the activity of the MCD-containing enzymes aldehyde oxidoreductase Yag-TSR and the xanthine dehydrogenases XdhABC and XdhD. Using a fully defined in vitro assay, we showed that MocA, Mo-MPT, CTP, and MgCl2 are required and sufficient for MCD biosynthesis in vitro. The activity of MocA is specific for CTP; other nucleotides such as ATP and GTP were not utilized. In the defined in vitro system a turnover number of 0.37 +/- 0.01 min(-1) was obtained. A1:1 binding ratio of MocA to Mo-MPT and CTP was determined to monomeric MocA with dissociation constants of 0.23 +/- 0.02 mu M for CTP and 1.17 +/- 0.18 mu M for Mo-MPT. We showed that MocA was also able to convert MPT to MCD in the absence of molybdate, however, with only one catalytic turnover. The addition of molybdate after one turnover gave rise to a higher MCD production, revealing that MCD remains bound to MocA in the absence of molybdate. This work presents the first characterization of a specific enzyme involved in MCD biosynthesis in bacteria. Y1 - 2009 UR - http://www.jbc.org/ U6 - https://doi.org/10.1074/jbc.M109.008565 SN - 0021-9258 ER - TY - GEN A1 - Mwinyi, Adina A1 - Meyer, Achim A1 - Bleidorn, Christoph A1 - Lieb, Bernhard A1 - Bartolomaeus, Thomas A1 - Podsiadlowski, Lars T1 - Mitochondrial genome sequence and gene order of Sipunculus nudus give additional support for an inclusion of Sipuncula into Annelida N2 - Background: Mitochondrial genomes are a valuable source of data for analysing phylogenetic relationships. Besides sequence information, mitochondrial gene order may add phylogenetically useful information, too. Sipuncula are unsegmented marine worms, traditionally placed in their own phylum. Recent molecular and morphological findings suggest a close affinity to the segmented Annelida. Results: The first complete mitochondrial genome of a member of Sipuncula, Sipunculus nudus, is presented. All 37 genes characteristic for metazoan mtDNA were detected and are encoded on the same strand. The mitochondrial gene order (protein-coding and ribosomal RNA genes) resembles that of annelids, but shows several derivations so far found only in Sipuncula. Sequence based phylogenetic analysis of mitochondrial protein-coding genes results in significant bootstrap support for Annelida sensu lato, combining Annelida together with Sipuncula, Echiura, Pogonophora and Myzostomida. Conclusion: The mitochondrial sequence data support a close relationship of Annelida and Sipuncula. Also the most parsimonious explanation of changes in gene order favours a derivation from the annelid gene order. These results complement findings from recent phylogenetic analyses of nuclear encoded genes as well as a report of a segmental neural patterning in Sipuncula. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 124 KW - Transfer-rna genes; Phylogenetic analysis; Animal phylogeny; Control region; Sister Taxau Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44916 ER - TY - THES A1 - Dreja, Tanja S. T1 - Microarray-basierte Expressionsanalysen des weißen Fettgewebes der NZO-Maus sowie der Langerhansschen Inseln der NZL-Maus : zwei Modelle für das metabolische Syndrom T1 - Microarray based expression analyses of white adipose tissue of the NZO-mouse and of the islets of Langerhans of the NZL-mouse : two models for the human metabolic syndrome N2 - Übergewicht und Adipositas führen zu Insulinresistenz und erhöhen deutlich das Risiko für die Entwicklung von Typ-2-Diabetes und kardiovaskulären Erkrankungen. Sowohl Adipositas als auch die Suszeptibilität gegenüber Diabetes sind zu einem erheblichen Teil genetisch determiniert. Die relevanten Risikogene, deren Interaktion mit der Umwelt, insbesondere mit Bestandteilen der Nahrung, und die Pathomechanismen, die zur Insulinresistenz und Diabetes führen, sind nicht vollständig aufgeklärt. In der vorliegenden Arbeit sollte durch Genexpressionsanalysen des weißen Fettgewebes (WAT) und der Langerhansschen Inseln die Entstehung und Progression von Adipositas und Typ-2-Diabetes untersucht werden, um relevante Pathomechanismen und neue Kandidatengene zu identifizieren. Zu diesem Zweck wurden Diät-Interventionsstudien mit NZO- und verwandten NZL-Mäusen, zwei polygenen Mausmodellen für das humane metabolische Syndrom, durchgeführt. Eine kohlenhydrathaltige Hochfett-Diät (HF: 14,6 % Fettanteil) führte in beiden Mausmodellen zu früher Adipositas, Insulinresistenz und Typ 2 Diabetes. Eine fettreduzierte Standarddiät (SD: 3,3 % Fettanteil), welche die Entstehung von Adipositas und Diabetes stark verzögert, sowie eine diabetesprotektive kohlenhydratfreie Hochfett-Diät (CHF: 30,2 % Fettanteil) dienten als Kontrolldiäten. Mit Hilfe der Microarray-Technologie wurden genomweite Expressionsprofile des WAT erstellt. Pankreatische Inseln wurden durch laserbasierte Mikropräparation (Laser Capture Microdissection; LCM) isoliert und ebenfalls hinsichtlich ihres Expressionsprofils analysiert. Differenziell exprimierte Gene wurden durch Real-Time-PCR validiert. Im WAT der NZO-Maus bewirkte die HF-Diät eine reduzierte Expression nukleärer Gene der oxidativen Phosphorylierung und von lipogenen Enzymen. Dies deutet auf eine inadäquate Fettspeicherung und -verwertung in diesen Tieren hin. Die Reduktion in der Fettspeicherung und -oxidation ist spezifisch für das adipöse NZO-Modell und konnte bei der schlanken SJL Maus nicht beobachtet werden, was auf eine mögliche Beteiligung an der Entstehung der Insulinresistenz hinweist. Zusätzlich wurde bestätigt, dass die Expansion des Fettgewebes bei der adipösen NZO-Maus eine zeitlich verzögerte Infiltration von Makrophagen in das WAT und dort eine lokale Immunantwort auslöst. Darüber hinaus wurde die Methode der LCM etabliert und zur Gewinnung hochangereicherter RNA aus den Langerhansschen Inseln eingesetzt. In erstmalig durchgeführten genomweiten Expressionsanalysen wurde zu einem frühen Zeitpunkt in der Diabetesentwicklung der Einfluss einer diabetogenen HF-Diät und einer diabetesprotektiven CHF-Diät auf das Expressionsprofil von pankreatischen Inselzellen verglichen. Im Gegensatz zum WAT bewirkt die diabetogene HF-Diät in Inselzellen einerseits, eine erhöhte Expression von nukleären Genen für die oxidative Phosphorylierung und andererseits von Genen, die mit Zellproliferation assoziiert sind. Zudem wurden 37 bereits annotierte Gene identifiziert, deren differenzielle Expression mit der Diabetesentwicklung korreliert. Das Peptidhormon Cholecystokinin (Cck, 11,8-fach erhöht durch die HF) stellt eines der am stärksten herauf regulierten Gene dar. Die hohe Anreicherung der Cck-mRNA in Inselzellen deutet auf eine bisher unbekannte Funktion des Hormons in der Regulation der Inselzellproliferation hin. Der Transkriptionsfaktor Mlxipl (ChREBP; 3,8-fach erniedrigt durch die HF) stellt in Langerhansschen Inseln eines der am stärksten herunter regulierten Gene dar. Ferner wurde ChREBP, dessen Funktion als glucoseregulierter Transkriptionsfaktor für lipogene Enzyme bislang in der Leber, aber nicht in Inselzellen nachgewiesen werden konnte, erstmals immunhistochemisch in Inselzellen detektiert. Dies deutet auf eine neue, bisher unbekannte regulatorische Funktion von ChREBP im Glucosesensor-Mechanismus der Inselzellen hin. Eine durchgeführte Korrelation der mit der Diabetesentwicklung assoziierten, differenziell exprimierten Inselzellgene mit Genvarianten aus humanen genomweiten Assoziationsstudien für Typ-2-Diabetes (WTCCC, Broad-DGI-T2D-Studie) ermöglichte die Identifizierung von 24 neuartigen Diabetes-Kandidatengenen. Die Ergebnisse der erstmals am polygenen NZO-Mausmodell durchgeführten genomweiten Expressionsuntersuchungen bestätigen bisherige Befunde aus Mausmodellen für Adipositas und Diabetes (z.B. ob/ob- und db/db-Mäuse), zeigen in einigen Fällen aber auch Unterschiede auf. Insbesondere in der oxidativen Phosphorylierung könnten die Ergebnisse relevant sein für das Verständnis der Pathogenese des polygen-bedingten humanen metabolischen Syndroms. N2 - Overweight and obesity cause insulin resistance and increase the risk of developing type 2 diabetes and cardiovascular diseases. Both, obesity and susceptibility to diabetes, are to a major part genetically predisposed. The relevant genes, their interaction with the environment – especially with food components – and the pathomechanisms causing insulin resistance and diabetes are not fully known yet. In the present study the development and progression of obesity and type 2 diabetes should be investigated by the means of gene expression analyses of the white adipose tissue (WAT) and the islets of Langerhans to identify underlying pathomechanisms and new causative candidate genes. For this purpose diet intervention studies on NZO- and related NZL-mice – two polygenic mouse models for the human metabolic syndrome – were performed. A carbohydrate containing high fat-diet (HF: 14.6 % fat) caused early obesity, insulin resistance and type 2 diabetes in both mouse models. A fat reduced standard chow (SD: 3.3 % fat) which strongly delayed the onset of obesity and diabetes, and a diabetes protective carbohydrate free high fat-diet (CHF: 30.2 % fat) served as control diets. Using microarray technology genome wide expression profiles of the WAT were generated. Pancreatic islets were isolated by the means of laser capture microdissection (LCM) and expression profiles of them were created, too. Differentially expressed genes were validated by quantitative real time PCR. The HF-diet reduced the expression of nuclear genes of the oxidative phosphorylation and lipogenic enzymes in the WAT of the NZO-mouse. This suggests an inadequate storage and utilization of fat in these animals. This is specific for the obese NZO-model and wasn’t observed for the lean SJL-mouse, indicating a role in the development of insulin resistance. Additionally, there was proof that the enlargement of the WAT triggers a retarded infiltration of macrophages into the WAT and there a local immune response. Moreover, the LCM technique was established and used for the isolation of highly enriched RNA from islets of Langerhans. For the first time the influence of carbohydrates in a high fat-diet on the expression profile of pancreatic islets was investigated by the use of genome wide expression analyses at an early time point at the onset of diabetes. Contrary to the WAT the diabetogenic HF-diet in islets cells increased the expression of both nuclear genes coding for the oxidative phosphorylation and genes associated with cell proliferation. Furthermore 37 already annotated genes correlated with diabetes progression were identified. The peptide hormone cholecystokinin (Cck: 11.8-fold enriched by the HF-diet) is one of the most up-regulated genes. The strong enrichment of Cck-mRNA in islets suggests a previously unknown function of the hormone in the regulation of the islet cell proliferation. The transcription factor ChREBP (Mlxipl: 3.8-fold reduced by the HF-diet) is one of the most down-regulated genes in the islets of Langerhans. Moreover, ChREBP, which has been already identified as a glucose regulated transcription factor for lipogenic enzymes in the liver but not in islets of Langerhans, was detected for the first time in islet cells, using immunohistochemistry. This points to an until now unknown regulatory function of ChREBP in the glucosesensor mechanism of the islet cells. Correlation of the differentially expressed genes associated with diabetes progression with gene variants from human genome wide association studies for type 2 diabetes (WTCCC, Broad-DGI-T2D-study) made the identification of 24 new diabetes candidate genes possible. The results of the genome wide expression analyses, which were done for the first time on a polygenic mouse-model, corroborated previous results for monogenic mouse-models for obesity and diabetes (e.g. ob/ob- and db/db-mice), however also demonstrated differences in some instances. Especially the results concerning the oxidative phosphorylation could be relevant for the comprehension of the pathogenesis of the polygenic human metabolic syndrome. KW - Microarray KW - Diabetes KW - metabolisches Syndrom KW - Diätintervention KW - LCM KW - microarray KW - diabetes KW - human metabolic syndrome KW - diet intervention KW - laser capture microdissection Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-32379 ER - TY - JOUR A1 - Dietzel, Uwe A1 - Kuper, Jochen A1 - Doebbler, Jennifer A. A1 - Schulte, Antje A1 - Truglio, James J. A1 - Leimkühler, Silke A1 - Kisker, Caroline T1 - Mechanism of substrate and inhibitor binding of Rhodobacter capsulatus xanthine dehydrogenase N2 - Rhodobacter capsulatus xanthine dehydrogenase (XDH) is an (alpha beta)(2) heterotetrameric cytoplasmic enzyme that resembles eukaryotic xanthine oxidoreductases in respect to both amino acid sequence and structural fold. To obtain a detailed understanding of the mechanism of substrate and inhibitor binding at the active site, we solved crystal structures of R. capsulatus XDH in the presence of its substrates hypoxanthine, xanthine, and the inhibitor pterin-6- aldehyde using either the inactive desulfo form of the enzyme or an active site mutant (E(B)232Q) to prevent substrate turnover. The hypoxanthine-and xanthine-bound structures reveal the orientation of both substrates at the active site and show the importance of residue GluB-232 for substrate positioning. The oxygen atom at the C-6 position of both substrates is oriented toward Arg(B)-310 in the active site. Thus the substrates bind in an orientation opposite to the one seen in the structure of the reduced enzyme with the inhibitor oxypurinol. The tightness of the substrates in the active site suggests that the intermediate products must exit the binding pocket to allow first the attack of the C-2, followed by oxidation of the C-8 atom to form the final product uric acid. Structural studies of pterin-6-aldehyde, a potent inhibitor of R. capsulatus XDH, contribute further to the understanding of the relative positioning of inhibitors and substrates in the binding pocket. Steady state kinetics reveal a competitive inhibition pattern with a K-i of 103.57 +/- 18.96 nM for pterin-6-aldehyde. Y1 - 2009 UR - http://www.jbc.org/ U6 - https://doi.org/10.1074/jbc.M808114200 SN - 0021-9258 ER - TY - THES A1 - Hubberten, Hans-Michael T1 - Local and systemic regulation of sulfur homeostasis in arabidopsis thaliana Y1 - 2009 CY - Potsdam ER - TY - JOUR A1 - Schmoll, Tim A1 - Schurr, Frank Martin A1 - Winkel, Wolfgang A1 - Epplen, Joerg T. A1 - Lubjuhn, Thomas T1 - Lifespan, lifetime reproductive performance and paternity loss of within-pair and extra-pair offspring in the coal tit "Periparus ater" N2 - The hypothesis that females of socially monogamous species obtain indirect benefits (good or compatible genes) from extra-pair mating behaviour has received enormous attention but much less generally accepted support. Here we ask whether selection for adult survival and fecundity or sexual selection contribute to indirect selection of the extra- pair mating behaviour in socially monogamous coal tits (Periparus ater). We tracked locally recruited individuals with known paternity status through their lives predicting that the extra-pair offspring (EPO) would outperform the within- pair offspring (WPO). No differences between the WPO and EPO recruits were detected in lifespan or age of first reproduction. However, the male WPO had a higher lifetime number of broods and higher lifetime number of social offspring compared with male EPO recruits, while no such differences were evident for female recruits. Male EPO recruits did not compensate for their lower social reproductive success by higher fertilization success within their social pair bonds. Thus, our results do not support the idea that enhanced adult survival, fecundity or within-pair fertilization success are manifestations of the genetic benefits of extra-pair matings. But we emphasize that a crucial fitness component, the extra-pair fertilization success of male recruits, has yet to be taken into account to fully appreciate the fitness consequences of extra-pair matings. Y1 - 2009 UR - http://dx.doi.org/10.1098/rspb.2008.1116 U6 - https://doi.org/10.1098/rspb.2008.1116 SN - 1471-2954 ER - TY - JOUR A1 - Vogt, Birgit A1 - Warncke, Marit A1 - Micheel, Burkhard A1 - Sheriff, Ahmed T1 - Lentiviral gene transfer of CTLA4 generates B cells with reduced costimulatory properties : brief definite report N2 - Peripheral T-cell (TC) tolerance can be induced by tolerogenic antigen-presenting cell (APC). A prerequisite is the reduction or blockade of B7 of APC. Besides dendritic cell, B cells can be used as APC. Here, we show the generation B cells with reduced B7 expression by lentiviral transduction of endoplasmic reticulum (ER)-directed CTLA4. Vectors coding for the human CTL4-Ig were used for the human B-cell line Raji. Transduction efficiency was over 90% (MOI = 3). For the murine B-cell line A20 and for primary mouse B cells, murine CTLA4 was used. We show that B cells with reduced B7 expression reduce the antigen (Ag) specific TC proliferation in vitro. B cells expressing an ER-directed CTLA4 may reduce Ag-specific immune responses. Y1 - 2009 UR - http://informahealthcare.com/loi/aut U6 - https://doi.org/10.1080/08916930902832470 SN - 0891-6934 ER - TY - JOUR A1 - Popp, Alexander A1 - Domptail, Stephanie A1 - Blaum, Niels A1 - Jeltsch, Florian T1 - Landuse experience does not qualify for adaptation to climate change N2 - The need to implement sustainable resource management regimes for semi-arid and arid rangelands is acute as non- adapted grazing strategies lead to irreversible environmental problems such as desertification and associated loss of economic support to society. In these sensitive ecosystems, traditional sectoral, disciplinary approaches will not work to attain sustainability: achieving a collective vision of how to attain sustainability requires interactive efforts among disciplines in a more integrated approach. Therefore, we developed an integrated ecological-economic approach that consists of an ecological and an economic module and combines relevant processes on either level. Parameters for both modules are adjusted for an arid dwarf shrub savannah in southern Namibia. The economic module is used to analyse decisions of different virtual farmer types on annual stocking rates depending on their knowledge how the ecosystem works and climatic conditions. We used a dynamic linear optimisation model to simulate farm economics and livestock dynamics. The ecological module is used to simulate the impact of the farmers' land-use decision, derived by the economic module, on ecosystem dynamics and resulting carrying capacity of the system for livestock. Vegetation dynamics, based on the concept of State-and-transition models, and forage productivity for both modules is derived by a small- scale and spatially explicit vegetation model. This mechanistic approach guarantees that data collected and processes estimated at smaller scales are included in our application. Simulation results of the ecological module were successfully compared to simulation results of the optimisation model for a time series of 30 years. We revealed that sustainable management of semi-arid and arid rangelands relies strongly on rangeland managers' understanding of ecological processes. Furthermore, our simulation results demonstrate that the projected lower annual rainfall due to climate change adds an additional layer of risk to these ecosystems that are already prone to land degradation. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/03043800 U6 - https://doi.org/10.1016/j.ecolmodel.2008.11.015 SN - 0304-3800 ER - TY - THES A1 - Troppmann, Britta T1 - Klonierung und Charakterisierung aminerger Rezeptoren der Amerikanischen Schabe Periplaneta americana T1 - Characterization of biogenic amine receptors of the american cockroach Periplaneta americana N2 - Biogene Amine sind kleine organische Verbindungen, die sowohl bei Vertebraten als auch bei Invertebraten als Neurotransmitter, Neuromodulatoren und/oder Neurohormone wirken. Sie bilden eine bedeutende Gruppe von Botenstoffen und entfalten ihre Wirkungen vornehmlich über die Bindung an G-Protein-gekoppelte Rezeptoren. Bei Insekten wurde eine Vielzahl von Wirkungen biogener Amine beschrieben. Das führte schon frühzeitig zur Vermutung, dass Insekten (u. a. Invertebraten) wie die Wirbeltiere ein diverses Repertoire an aminergen Rezeptoren besitzen. Für ein umfassendes Verständnis der komplexen physiologischen Wirkungen biogener Amine fehlten jedoch wichtige Informationen über die molekulare Identität der entsprechenden Rezeptorproteine und ihrer pharmakologischen Eigenschaften, ihre Lokalisation und ihre intrazellulären Reaktionspartner. Viele bei Schaben gut untersuchte (neuro)physiologische Prozesse sowie Verhaltensweisen werden durch Serotonin und Dopamin gesteuert bzw. moduliert. Über die beteiligten Rezeptoren ist jedoch bisher vergleichsweise wenig bekannt. Die Klonierung und Charakterisierung von Serotonin- und Dopaminrezeptoren der Amerikanischen Schabe P. americana ist damit ein längst überfälliger Schritt auf dem Weg zu einem umfassenden Verständnis der vielfältigen Wirkungen biogener Amine bei Insekten. Durch die Anwendung verschiedener Klonierungsstrategien konnten cDNAs isoliert werden, die für potentielle Serotoninrezeptoren und einen Dopaminrezeptor kodieren. Die Sequenzen weisen die größte Ähnlichkeit zu Mitgliedern der 5-HT1- und 5-HT7-Rezeptorklassen bzw. den Invertebratentyp-Dopaminrezeptoren auf. Die isolierten Rezeptoren der Amerikanischen Schabe wurden dementsprechend Pea(Periplaneta americana)5-HT1, Pea5-HT7 und PeaDop2 benannt. Das Hydropathieprofil dieser Rezeptoren postuliert das Vorhandensein der charakteristischen heptahelikalen Architektur G-Protein-gekoppelter Rezeptoren. Die abgeleiteten Aminosäuresequenzen zeigen typische Merkmale aminerger Rezeptoren. So sind Aminosäuren, die bedeutend für die Ligandenbindung, die Rezeptoraktivierung und die Kopplung an G﷓Proteine sind, in den Rezeptoren konserviert. Expressionsstudien zeigten eine auffallend hohe Expression aller drei Rezeptor-mRNAs im Gehirn sowie in den Speicheldrüsen. Im Rahmen dieser Arbeit wurden polyklonale Antikörper gegen den Pea5-HT1-Rezeptor sowie den PeaDop2-Rezeptor hergestellt. Der anti-Pea5-HT1-Antikörper detektiert im Homogenat von Schabengehirnen, Speicheldrüsen und Pea5-HT1-exprimierenden HEK 293-Zellen die glykosylierte Form des Rezeptors. In Gehirnschnitten markiert der anti-Pea5-HT1-Antikörper spezifisch einige Zellkörper in der Pars intercerebralis und deren Axone, welche in den Corpora cardiaca Nerv I projizieren. Der PeaDop2-Rezeptor wurde durch den spezifischen anti-PeaDop2-Antikörper in Neuronen mit Somata im anterioren Randbereich der Medulla nachgewiesen. Diese Neurone innervieren die optischen Loben und projizieren in das ventrolaterale Protocerebrum. Die intrazellulären Signalwege der heterolog exprimierten Pea5-HT1- und PeaDop2-Rezeptoren wurden in HEK 293-Zellen untersucht. Die Aktivierung des Pea5-HT1-Rezeptors durch Serotonin führt zur Hemmung der cAMP-Synthese. Des Weiteren wurde gezeigt, dass der Rezeptor konstitutive Aktivität besitzt. WAY 100635, ein hoch selektiver 5-HT1A-Rezeptorantagonist, wurde als wirksamer inverser Agonist am Pea5-HT1-Rezeptor identifiziert. Der stabil exprimierte PeaDop2-Rezeptor antwortet auf eine Aktivierung durch Dopamin mit einer Erhöhung der cAMP-Konzentration. Eine C-terminal trunkierte Variante dieses Rezeptors ist eigenständig nicht funktional. Die Ergebnisse der vorliegenden Arbeit indizieren, dass die untersuchten aminergen Rezeptoren im zentralen Nervensystems der Schabe an der Informationsverarbeitung beteiligt sind und verschiedene physiologische Prozesse in peripheren Organen regulieren. Mit der Klonierung und funktionellen Charakterisierung der ersten Serotoninrezeptoren und eines Dopaminrezeptors ist damit eine wichtige Grundlage für die Untersuchung ihrer Funktionen geschaffen worden. N2 - Biogenic amines are small organic compounds that act as neurotransmitters, neuromodulators and/or neurohormones in vertebrates and in invertebrates. They form an important group of messenger substances and mediate their diverse effects primarily by binding to G protein-coupled receptors. The molecular identification as well as the functional and pharmacological characterization of these receptors is crucial for the comprehension of the intracellular signaling pathways activated by biogenic amines. This work describes the molecular and functional characterization of the first serotonin receptors and an invertebrate-type dopamine receptor of the American cockroach, Periplaneta americana. Using a PCR-strategy based on degenerate primers and RACE-PCR three cDNAs encoding for putative biogenic amine receptors were isolated from P. americana brain cDNA (Pea5-ht1, Pea5-ht7, Peadop2). The deduced amino acid sequences display major characteristics common to all G protein-coupled receptors. Primarily Distribution of receptor mRNA was investigated by RT-PCR. The analysis revealed a high mRNA expression level for all three receptors in the brain and salivary glands. The distribution of the Pea5﷓HT1 and PeaDop2 receptor proteins was analyzed by immunohistochemistry with specific affinity-purified polyclonal antibodies. Both receptor proteins are expressed in brain and salivary glands. Furthermore the cellular distribution of the receptors was investigated by immunocytochemistry on brain sections. The anti-Pea5-HT1 receptor antibody specifically labelled some large somata in the pars intercerebralis. Labeled axons of these neurons pass down the anterior surface of the brain and cross over in the chiasma region of the corpora cardiaca nerve 1. The PeaDop2 receptor was detected in neurons with somata at the anterior edge of the medulla bilaterally innervating the optic lobes and projecting to the ventro-lateral protocerebrum. In order to clarify the functional and pharmacological properties of the cloned receptors, we studied HEK 293 cell lines stably expressing Pea5-HT1 or PeaDop2. Activation of Pea5-HT1 expressing cells by serotonin reduced adenylyl cyclase activity in a dose-dependent manner. The Pea5-HT1 receptor was expressed as a constitutively active receptor with methiothepin acting as a neutral antagonist and WAY 100635 as an inverse agonist. The activation of the PeaDop2 receptor by dopamine induced an increase in intracellular cAMP level, whereas a C-terminally truncated splice variant of this receptor does not exhibit any functional property by itself. The results of this work suggest important roles of the investigated receptors in various areas of the cockroach brain. The molecular and pharmacological characterization of the first serotonin receptors and a dopamine receptor of the cockroach now provides the basis for forthcoming studies regarding the significance of these particular receptors for cockroach behavior and physiology KW - Insekt KW - Dopamin KW - Serotonin KW - G-Protein-gekoppelte-Rezeptoren KW - insect KW - serotonin KW - dopamine KW - G-protein-coupled-receptors Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-36619 ER - TY - JOUR A1 - Bulik, Sascha A1 - Grimbs, Sergio A1 - Huthmacher, Carola A1 - Selbig, Joachim A1 - Holzhutter, Hermann G. T1 - Kinetic hybrid models composed of mechanistic and simplified enzymatic rate laws : a promising method for speeding up the kinetic modelling of complex metabolic networks N2 - Kinetic modelling of complex metabolic networks - a central goal of computational systems biology - is currently hampered by the lack of reliable rate equations for the majority of the underlying biochemical reactions and membrane transporters. On the basis of biochemically substantiated evidence that metabolic control is exerted by a narrow set of key regulatory enzymes, we propose here a hybrid modelling approach in which only the central regulatory enzymes are described by detailed mechanistic rate equations, and the majority of enzymes are approximated by simplified (nonmechanistic) rate equations (e.g. mass action, LinLog, Michaelis-Menten and power law) capturing only a few basic kinetic features and hence containing only a small number of parameters to be experimentally determined. To check the reliability of this approach, we have applied it to two different metabolic networks, the energy and redox metabolism of red blood cells, and the purine metabolism of hepatocytes, using in both cases available comprehensive mechanistic models as reference standards. Identification of the central regulatory enzymes was performed by employing only information on network topology and the metabolic data for a single reference state of the network [Grimbs S, Selbig J, Bulik S, Holzhutter HG & Steuer R (2007) Mol Syst Biol3, 146, doi:10.1038/msb4100186]. Calculations of stationary and temporary states under various physiological challenges demonstrate the good performance of the hybrid models. We propose the hybrid modelling approach as a means to speed up the development of reliable kinetic models for complex metabolic networks. Y1 - 2009 UR - http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291742-4658 U6 - https://doi.org/10.1111/j.1742-4658.2008.06784.x SN - 1742-464X ER -