@misc{ZiegeMahlowHennigeSulzetal.2009,
  author    = {Ziege, Madlen and Mahlow, Kristin and Hennige-Sulz, Carmen and Kronmarck, Claudia and Tiedemann, Ralph and Streit, Bruno and Plath, Martin},
  title     = {Audience effects in the Atlantic molly (Poecilia mexicana) : prudent male mate choice in response to perceived sperm competition risk?},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-45171},
  year      = {2009},
  abstract  = {Background: Multidirectional interactions in social networks can have a profound effect on mate choice behavior; e.g., Poecilia mexicana males show weaker expression of mating preferences when being observed by a rival. This may be an adaptation to reduce sperm competition risk, which arises because commonly preferred female phenotypes will receive attention also from surrounding males, and/or because other males can copy the focal male's mate choice. Do P. mexicana males indeed respond to perceived sperm competition risk? We gave males a choice between two females and repeated the tests under one of the following conditions: (1) an empty transparent cylinder was presented (control); (2) another ("audience") male inside the cylinder observed the focal male throughout the 2nd part, or (3) the audience male was presented only before the tests, but could not eavesdrop during the actual choice tests (non-specific sperm competition risk treatments); (4) the focal male could see a rival male interact sexually with the previously preferred, or (5) with the non-preferred female before the 2nd part of the tests (specific sperm competition risk treatments). Results: The strength of individual male preferences declined slightly also during the control treatment (1). However, this decrease was more than two-fold stronger in audience treatment (2), i.e., with non-specific sperm competition risk including the possibility for visual eavesdropping by the audience male. No audience effect was found in treatments (3) and (5), but a weak effect was also observed when the focal male had seen the previously preferred female sexually interact with a rival male (treatment 4; specific sperm competition risk). Conclusion: When comparing the two 'non-specific sperm competition risk' treatments, a very strong effect was found only when the audience male could actually observe the focal male during mate choice [treatment (2)]. This suggests that focal males indeed attempt to conceal their mating preferences so as to prevent surrounding males from copying their mate choice. When there is no potential for eavesdropping [treatment (3)], non-specific specific sperm competition risk seems to play a minor or no role. Our results also show that P. mexicana males tend to share their mating effort more equally among females when the resource value of their previously preferred mate decreases after mating with a rival male (perceived specific sperm competition risk), but this effect is comparatively weak.},
  language  = {en}
}
@article{ZhaoHerzschuh2009,
  author    = {Zhao, Yan and Herzschuh, Ulrike},
  title     = {Modern pollen representation of source vegetation in the Qaidam Basin and surrounding mountains, north-eastern Tibetan Plateau},
  issn      = {0939-6314},
  doi       = {10.1007/s00334-008-0201-7},
  year      = {2009},
  abstract  = {We use a data set of 35 surface pollen samples from lake sediments, moss polsters and top soils on the north- eastern Tibetan Plateau to explore the relationship between modern pollen assemblages and contemporary vegetation patterns. The surface pollen transect spanned four vegetation zones--alpine meadow, steppe, steppe desert and desert-- under different climatic/elevational conditions. Relative representation (R (rel)) values and Principal Components Analysis (PCA) were used to determine the relationships between modern pollen and vegetation and regional climate gradients. The results show that the main vegetation zones along the regional and elevational transects can be distinguished by their modern pollen spectra. Relative to Poaceae, a high representation of Artemisia, Nitraria and Chenopodiaceae was found, while Cyperaceae and Gentiana showed values in the middle range, and Ranunculaceae, Asteraceae, Ephedra and Fabaceae had low relative representation values. PCA results indicate a high correlation between the biogeoclimatic zones and annual precipitation and annual temperature and July temperature. The Artemisia/ Chenopodiaceae ratio and the Artemisia/Cyperaceae ratio are useful tools for qualitative and semi-quantitative palaeoenvironmental reconstruction on the north-eastern Tibetan Plateau. Surface lake sediments are found to have different palynomorph spectra from moss cushion and soil samples, reflecting the larger pollen source area in the contemporary vegetation for lakes.},
  language  = {en}
}
@misc{ZhangIgnatova2009,
  author    = {Zhang, Gong and Ignatova, Zoya},
  title     = {Generic algorithm to predict the speed of translational elongation : implications for protein biogenesis},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-45007},
  year      = {2009},
  abstract  = {Synonymous codon usage and variations in the level of isoaccepting tRNAs exert a powerful selective force on translation fidelity. We have developed an algorithm to evaluate the relative rate of translation which allows large-scale comparisons of the non-uniform translation rate on the protein biogenesis. Using the complete genomes of Escherichia coli and Bacillus subtilis we show that stretches of codons pairing to minor tRNAs form putative sites to locally attenuate translation; thereby the tendency is to cluster in near proximity whereas long contiguous stretches of slow-translating triplets are avoided. The presence of slow-translating segments positively correlates with the protein length irrespective of the protein abundance. The slow-translating clusters are predominantly located down-stream of the domain boundaries presumably to fine-tune translational accuracy with the folding fidelity of multidomain proteins. Translation attenuation patterns at highly structurally and functionally conserved domains are preserved across the species suggesting a concerted selective pressure on the codon selection and species-specific tRNA abundance in these regions.},
  language  = {en}
}
@article{ZhangHubalewskaIgnatova2009,
  author    = {Zhang, Gong and Hubalewska, Magdalena and Ignatova, Zoya},
  title     = {Transient ribosomal attenuation coordinates protein synthesis and co-translational folding},
  issn      = {1545-9985},
  doi       = {10.1038/Nsmb.1554},
  year      = {2009},
  abstract  = {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.},
  language  = {en}
}
@phdthesis{Zhang2009,
  author    = {Zhang, Gong},
  title     = {Transient ribosomal attenuation as a generic mechanism to coordinate protein biosynthesis and biogenesis},
  address   = {Potsdam},
  pages     = {114 S.},
  year      = {2009},
  language  = {en}
}
@article{ZerbianDowningKuegler2009,
  author    = {Zerbian, Sabine and Downing, Laura and K{\"u}gler, Frank},
  title     = {Introduction : tone and intonation from a typological perspective},
  issn      = {0024-3841},
  doi       = {10.1016/j.lingua.2007.10.024},
  year      = {2009},
  language  = {en}
}
@article{Zeijlstra2009,
  author    = {Zeijlstra, Hedde},
  title     = {Hard and soft conditions on the faculty of language},
  series = {Linguistics in Potsdam},
  journal   = {Linguistics in Potsdam},
  number    = {28},
  issn      = {1616-7392},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32221},
  pages     = {9 -- 38},
  year      = {2009},
  abstract  = {In this paper I argue that both parametric variation and the alleged differences between languages in terms of their internal complexity straightforwardly follow from the Strongest Minimalist Thesis that takes the Faculty of Language (FL) to be an optimal solution to conditions that neighboring mental modules impose on it. In this paper I argue that hard conditions like legibility at the linguistic interfaces invoke simplicity metrices that, given that they stem from different mental modules, are not harmonious. I argue that widely attested expression strategies, such as agreement or movement, are a direct result of conflicting simplicity metrices, and that UG, perceived as a toolbox that shapes natural language, can be taken to consist of a limited number of markings strategies, all resulting from conflicting simplicity metrices. As such, the contents of UG follow from simplicity requirements, and therefore no longer necessitate linguistic principles, valued or unvalued, to be innately present. Finally, I show that the SMT does not require that languages themselves have to be optimal in connecting sound to meaning.},
  language  = {en}
}
@phdthesis{Zbierzak2009,
  author    = {Zbierzak, Anna Maria},
  title     = {Isolation and characterization of the chilling sensitive 1 gene from Arabidopsis},
  address   = {Potsdam},
  pages     = {iii, 131 Bl. : Ill., graph. Darst.},
  year      = {2009},
  language  = {en}
}
@misc{Zapf2009,
  author    = {Zapf, Uta},
  title     = {Außenpolitischer Burgfrieden? : Kontinuit{\"a}t als Konsens},
  issn      = {0944-8101},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32702},
  year      = {2009},
  abstract  = {Wie stabil ist die Außenpolitik der Großen Koalition? Aufgrund ihrer Position als stellvertretende außenpolitische Sprecherin der SPD ist es der Autorin m{\"o}glich, neben den Gemeinsamkeiten auch die entscheidenden Unterschiede zu beleuchten. Vor dem Hintergrund mehrerer Beispiele, wie dem EU-Beitritt der T{\"u}rkei, stellt sie den Konsens zwischen CDU/ CSU und SPD als fragil heraus.},
  language  = {de}
}
@article{ZamponiAnsarivonKorffSchmisingetal.2009,
  author    = {Zamponi, Flavio and Ansari, Zunaira and von Korff Schmising, Clemens and Rothhardt, Philip and Zhavoronkov, Nickolai and Woerner, Michael and Elsaesser, Thomas and Bargheer, Matias and Trobitzsch-Ryll, Timo and Haschke, Michael},
  title     = {Femtosecond hard X-ray plasma sources with a kilohertz repetition rate},
  issn      = {0947-8396},
  doi       = {10.1007/s00339-009-5171-9},
  year      = {2009},
  abstract  = {Laser-driven plasma sources of femtosecond hard X-ray pulses have found widespread application in ultrafast X- ray diffraction. The recent development of plasma sources working at kilohertz repetition rates has allowed for diffraction experiments with strongly improved sensitivity, now revealing subtle fully reversible changes of the geometry of crystal lattices. We provide a brief review of this development and present a novel plasma source with an optimized mechanical and optical design, providing a high flux of several 10(10) photons/s at the Cu-K alpha energy of 8.04 keV and a pulse duration of a parts per thousand currency sign300 fs. First experiments, including the generation of Debye-Scherrer diffraction patterns from Si powder, demonstrate the high performance of this source.},
  language  = {en}
}
@phdthesis{ZamoraLopez2009,
  author    = {Zamora-L{\´o}pez, Gorka},
  title     = {Linking structure and function of complex cortical networks},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52257},
  school      = {Universit{\"a}t Potsdam},
  year      = {2009},
  abstract  = {The recent discovery of an intricate and nontrivial interaction topology among the elements of a wide range of natural systems has altered the manner we understand complexity. For example, the axonal fibres transmitting electrical information between cortical regions form a network which is neither regular nor completely random. Their structure seems to follow functional principles to balance between segregation (functional specialisation) and integration. Cortical regions are clustered into modules specialised in processing different kinds of information, e.g. visual or auditory. However, in order to generate a global perception of the real world, the brain needs to integrate the distinct types of information. Where this integration happens, nobody knows. We have performed an extensive and detailed graph theoretical analysis of the cortico-cortical organisation in the brain of cats, trying to relate the individual and collective topological properties of the cortical areas to their function. We conclude that the cortex possesses a very rich communication structure, composed of a mixture of parallel and serial processing paths capable of accommodating dynamical processes with a wide variety of time scales. The communication paths between the sensory systems are not random, but largely mediated by a small set of areas. Far from acting as mere transmitters of information, these central areas are densely connected to each other, strongly indicating their functional role as integrators of the multisensory information. In the quest of uncovering the structure-function relationship of cortical networks, the peculiarities of this network have led us to continuously reconsider the stablished graph measures. For example, a normalised formalism to identify the "functional roles" of vertices in networks with community structure is proposed. The tools developed for this purpose open the door to novel community detection techniques which may also characterise the overlap between modules. The concept of integration has been revisited and adapted to the necessities of the network under study. Additionally, analytical and numerical methods have been introduced to facilitate understanding of the complicated statistical interrelations between the distinct network measures. These methods are helpful to construct new significance tests which may help to discriminate the relevant properties of real networks from side-effects of the evolutionary-growth processes.},
  language  = {en}
}
@article{ZamoraLopezZhouKurths2009,
  author    = {Zamora-Lopez, Gorka and Zhou, Changsong and Kurths, J{\"u}rgen},
  title     = {Graph analysis of cortical networks reveals complex anatomical communication substrate},
  issn      = {1054-1500},
  doi       = {10.1063/1.3089559},
  year      = {2009},
  abstract  = {Sensory information entering the nervous system follows independent paths of processing such that specific features are individually detected. However, sensory perception, awareness, and cognition emerge from the combination of information. Here we have analyzed the corticocortical network of the cat, looking for the anatomical substrate which permits the simultaneous segregation and integration of information in the brain. We find that cortical communications are mainly governed by three topological factors of the underlying network: (i) a large density of connections, (ii) segregation of cortical areas into clusters, and (iii) the presence of highly connected hubs aiding the multisensory processing and integration. Statistical analysis of the shortest paths reveals that, while information is highly accessible to all cortical areas, the complexity of cortical information processing may arise from the rich and intricate alternative paths in which areas can influence each other.},
  language  = {en}
}
@misc{Zamirirad2009,
  author    = {Zamirirad, Azadeh},
  title     = {Kommentar: Hunger nach mehr : Iran nach den Wahlen},
  issn      = {0944-8101},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33982},
  year      = {2009},
  abstract  = {"Tats{\"a}chlich steht das offiziell verk{\"u}ndete Wahlergebnis nicht im Widerspruch zu einer im Mai landesweit durchgef{\"u}hrten Umfrage eines US-Forschungsinstituts. Dieses sah Ahmadinedschad klar vor seinem gr{\"o}ßten Konkurrenten Mussavi. Vermeintliche Quellen aus dem iranischen Innenministerium dagegen sprachen nach der Wahl von einem Erdrutschsieg Mussavis. Indizien f{\"u}r einen Betrug gibt es viele..."},
  language  = {de}
}
@article{ZamagniKoUeirMutti2009,
  author    = {Zamagni, Jessica and Ko{\"U}ir, Adrijan and Mutti, Maria},
  title     = {The first microbialite-coral mounds in the Cenozoic (Uppermost Paleocene) from the Northern Tethys (Slovenia) : environmentally-triggered phase shifts preceding the PETM?},
  issn      = {0031-0182},
  doi       = {10.1016/j.palaeo.2008.12.007},
  year      = {2009},
  abstract  = {Upper Thanetian microbialite-coral mounds from the Adriatic Carbonate Platform (SW Slovenia) are described herein for the first time, representing an important case study of extensively microbially-cemented boundstones in the Early Paleogene. The mounds are constructed primarily by microbialites associated to small-sized coral colonies, forming metric bioconstructions in a mid-ramp setting. Detailed macroscopic and microscopic studies show that microbes are the major framework builders, playing a prominent role in the stabilization and growth of the mounds, with corals being the second most important component. Microbial carbonates represent up to 70\% of the mounds, forming centimetric-thick crusts alternating with coral colonies. The microbial nature of the crusts is demonstrated by their growth form and internal microfabrics, showing accretionary, binding, and encrusting growth fabrics, often with gravity-defying geometries. Thin sections and polished slabs reveal a broad range of mesofabrics, with dense, structureless micrite (leiolite), laminated crusts (stromatolites), and clotted micritic masses (thrombolites). A first layer of micro- encrusters, including leiolites and thrombolites, occurs in cryptic habitats, whereas discontinuous stromatolites encrust the upper surface of corals. A second encrustation, the major mound construction phase, follows and is dominated by thrombolites, encrusting corals and other micro-encrusters. This sequence represents the basic constructional unit horizontally and vertically interlocked, in an irregular pattern, to form the mounds. The processes, which favored the deposition of these microbial carbonates, were mainly related to in situ precipitation, with minor evidences for grain agglutination and trapping processes. Scleractinian corals comprise moderately diversified community of small (centimetric) colonial, massive, platy encrusting, and branching forms. Coral colonies are distributed uniformly throughout the mounds without developing any ecological zonation. These features indicate that coral development remained at the pioneer stage throughout the mound growth. The spatial relationships between corals and microbialites, as well as the characteristics of microbial crusts and coral colonies, indicate a strong ecological competition between corals and microbes. A model for the evolution of the trophic structures during the mound growth is proposed, with changes in the paleoecology of the main bioconstructors triggered by frequent environmental perturbations. Turbidity and nutrient pressure, interpreted here as related to frequent recurrences of wet phases during the warm, humid climate of the Uppermost Thanetian, might have promoted temporary dominance of microbes over corals, causing rapid environmentally- driven "phase shifts" in the dominant biota.},
  language  = {en}
}
@phdthesis{Zamagni2009,
  author    = {Zamagni, Jessica},
  title     = {Responses of a shallow-water ecosystem to the early Paleogene greenhouse environmental conditions : evolution of Larger Foraminifera and coral communities from the Northern Tethys},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31853},
  school      = {Universit{\"a}t Potsdam},
  year      = {2009},
  abstract  = {Modern anthropogenic forcing of atmospheric chemistry poses the question of how the Earth System will respond as thousands of gigatons of greenhouse gas are rapidly added to the atmosphere. A similar, albeit nonanthropogenic, situation occurred during the early Paleogene, when catastrophic release of carbon to the atmosphere triggered abrupt increase in global temperatures. The best documented of these events is the Paleocene-Eocene Thermal Maximum (PETM, ~55 Ma) when the magnitude of carbon addition to the oceans and atmosphere was similar to those expected for the future. This event initiated global warming, changes in hydrological cycles, biotic extinction and migrations. A recently proposed hypothesis concerning changes in marine ecosystems suggests that this global warming strongly influenced the shallow-water biosphere, triggering extinctions and turnover in the Larger Foraminifera (LF) community and the demise of corals. The successions from the Adriatic Carbonate Platform (SW Slovenia) represent an ideal location to test the hypothesis of a possible causal link between the PETM and evolution of shallow-water organisms because they record continuous sedimentation from the Late Paleocene to the Early Eocene and are characterized by a rich biota, especially LF, fundamental for detailed biostratigraphic studies. In order to reconstruct paleoenvironmental conditions during deposition, I focused on sedimentological analysis and paleoecological study of benthic assemblages. During the Late Paleocene-earliest Eocene, sedimentation occurred on a shallow-water carbonate ramp system characterized by enhanced nutrient levels. LF represent the common constituent of the benthic assemblages that thrived in this setting throughout the Late Paleocene to the Early Eocene. With detailed biostratigraphic and chemostratigraphic analyses documenting the most complete record to date available for the PETM event in a shallow-water marine environment, I correlated chemostratigraphically for the first time the evolution of LF with the δ¹³C curves. This correlation demonstrated that no major turnover in the LF communities occurred synchronous with the PETM; thus the evolution of LF was mainly controlled by endogenous biotic forces. The study of Late Thanetian metric-sized microbialite-coral mounds which developed in the middle part of the ramp, documented the first Cenozoic occurrence of microbially-cemented mounds. The development of these mounds, with temporary dominance of microbial communities over corals, suggest environmentally-triggered "phase shifts" related to frequent fluctuations of nutrient/turbidity levels during recurrent wet phases which preceding the extreme greenhouse conditions of the PETM. The paleoecological study of the coral community in the microbialites-coral mounds, the study of corals from Early Eocene platform from SW France, and a critical, extensive literature research of Late Paleocene - Early Eocene coral occurrences from the Tethys, the Atlantic, the Caribbean realms suggested that these corals types, even if not forming extensive reefs, are common in the biofacies as small isolated colonies, piles of rubble or small patch-reefs. These corals might have developed 'alternative' life strategies to cope with harsh conditions (high/fluctuating nutrients/turbidity, extreme temperatures, perturbation of aragonite saturation state) during the greenhouse times of the early Paleogene, representing a good fossil analogue to modern corals thriving close to their thresholds for survival. These results demonstrate the complexity of the biological responses to extreme conditions, not only in terms of temperature but also nutrient supply, physical disturbance and their temporal variability and oscillating character.},
  language  = {en}
}
@article{ZackKonradSchmolke2009,
  author    = {Zack, Thomas and Konrad-Schmolke, Matthias},
  title     = {Distinguishing trace element redistribution during mineral reactions from fluid-induced trace element mobility in blueschists},
  issn      = {0016-7037},
  doi       = {10.1016/j.gca.2009.05.019},
  year      = {2009},
  language  = {en}
}
@article{ZabalzavanDongenFroehlichetal.2009,
  author    = {Zabalza, Ana and van Dongen, Joost T. and Fr{\"o}hlich, Anja and Oliver, Sandra N. and Faix, Benjamin and Gupta, Kapuganti Jagadis and Schmalzlin, Elmar and Igal, Maria and Orcaray, Luis and Royuela, Mercedes and Geigenberger, Peter},
  title     = {Regulation of respiration and fermentation to control the plant internal oxygen concentration},
  issn      = {0032-0889},
  doi       = {10.1104/pp.108.129288},
  year      = {2009},
  abstract  = {Plant internal oxygen concentrations can drop well below ambient even when the plant grows under optimal conditions. Using pea (Pisum sativum) roots, we show how amenable respiration adapts to hypoxia to save oxygen when the oxygen availability decreases. The data cannot simply be explained by oxygen being limiting as substrate but indicate the existence of a regulatory mechanism, because the oxygen concentration at which the adaptive response is initiated is independent of the actual respiratory rate. Two phases can be discerned during the adaptive reaction: an initial linear decline of respiration is followed by a nonlinear inhibition in which the respiratory rate decreased progressively faster upon decreasing oxygen availability. In contrast to the cytochrome c pathway, the inhibition of the alternative oxidase pathway shows only the linear component of the adaptive response. Feeding pyruvate to the roots led to an increase of the oxygen consumption rate, which ultimately led to anoxia. The importance of balancing the in vivo pyruvate availability in the tissue was further investigated. Using various alcohol dehydrogenase knockout lines of Arabidopsis (Arabidopsis thaliana), it was shown that even under aerobic conditions, alcohol fermentation plays an important role in the control of the level of pyruvate in the tissue. Interestingly, alcohol fermentation appeared to be primarily induced by a drop in the energy status of the tissue rather than by a low oxygen concentration, indicating that sensing the energy status is an important component of optimizing plant metabolism to changes in the oxygen availability.},
  language  = {en}
}
@article{YinLinker2009,
  author    = {Yin, Jian and Linker, Torsten},
  title     = {Convenient synthesis of bicyclic carbohydrate 1,2-lactones and their stereoselective opening to 1- functionalized glucose derivatives},
  issn      = {0947-6539},
  doi       = {10.1002/chem.200802178},
  year      = {2009},
  abstract  = {Closed and re-opened for business: C-2 branched carbohydrates 1 cyclize under conditions of decarboxylation to the hitherto unknown carbohydrate 1,2-lactones 2 in high yields. The gluco isomer can be opened at the anomeric position with various nuceophiles in the presence of Sc(OTf)3, which allows the stereoselective synthesis of 1-functionalized glucose derivatives 3. Thus, 1,2-bis-C-branched saccharides become available in only a few steps starting from glycals.},
  language  = {en}
}
@article{YinLinker2009,
  author    = {Yin, Jian and Linker, Torsten},
  title     = {Stereodivergent syntheses at the glucose backbone},
  issn      = {1477-0520},
  doi       = {10.1039/B918893m},
  year      = {2009},
  abstract  = {Both diastereomers of 2-C-branched carbohydrates with various functional groups are selectively available from the same malonate precursor in good yields in only a few steps.},
  language  = {en}
}
@phdthesis{Yin2009,
  author    = {Yin, Jian},
  title     = {Syntheses and transformations of 2-C-Malonyl substituted carbohydrates},
  address   = {Potsdam},
  pages     = {XII, 133 S. _ graph. Darst.},
  year      = {2009},
  language  = {en}
}
@phdthesis{Yin2009,
  author    = {Yin, Chunhong},
  title     = {The interplay of nanostructure and efficiency of polymer solar cells},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29054},
  school      = {Universit{\"a}t Potsdam},
  year      = {2009},
  abstract  = {The aim of this thesis is to achieve a deep understanding of the working mechanism of polymer based solar cells and to improve the device performance. Two types of the polymer based solar cells are studied here: all-polymer solar cells comprising macromolecular donors and acceptors based on poly(p-phenylene vinylene) and hybrid cells comprising a PPV copolymer in combination with a novel small molecule electron acceptor. To understand the interplay between morphology and photovoltaic properties in all-polymer devices, I compared the photocurrent characteristics and excited state properties of bilayer and blend devices with different nano-morphology, which was fine tuned by using solvents with different boiling points. The main conclusion from these complementary measurements was that the performance-limiting step is the field-dependent generation of free charge carriers, while bimolecular recombination and charge extraction do not compromise device performance. These findings imply that the proper design of the donor-acceptor heterojunction is of major importance towards the goal of high photovoltaic efficiencies. Regarding polymer-small molecular hybrid solar cells I combined the hole-transporting polymer M3EH-PPV with a novel Vinazene-based electron acceptor. This molecule can be either deposited from solution or by thermal evaporation, allowing for a large variety of layer architectures to be realized. I then demonstrated that the layer architecture has a large influence on the photovoltaic properties. Solar cells with very high fill factors of up to 57 \% and an open circuit voltage of 1V could be achieved by realizing a sharp and well-defined donor-acceptor heterojunction. In the past, fill factors exceeding 50 \% have only been observed for polymers in combination with soluble fullerene-derivatives or nanocrystalline inorganic semiconductors as the electron-accepting component. The finding that proper processing of polymer-vinazene devices leads to similar high values is a major step towards the design of efficient polymer-based solar cells.},
  language  = {en}
}
@article{YenesewTwinomuhweziKiremireetal.2009,
  author    = {Yenesew, Abiy and Twinomuhwezi, Hannington and Kiremire, Bernard T. and Mbugua, Martin N. and Gitu, Peter M. and Heydenreich, Matthias and Peter, Martin G.},
  title     = {8-Methoxyneorautenol and radical scavenging flavonoids from Erythrina abyssinica},
  issn      = {1011-3924},
  year      = {2009},
  abstract  = {A new pterocarpan (named 8-methoxyneorautenol) was isolated from the acetone ext. of the root bark of Erythrina abyssinica. In addn., the known isoflavonoid derivs. eryvarin L, erycristagallin and shinpterocarpin were identified for the first time from the roots of this plant. The structures were detd. on the basis of spectroscopic evidence. The new compd. showed selective antimicrobial activity against Trichophyton mentagrophytes. The acetone ext. of the root bark of E. abyssinica showed radical scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The pterocarpenes, 3-hydroxy-9-methoxy-10-(3,3-dimethylallyl)pterocarpene and erycristagallin, were the most active constituents of the roots of this plant and showing dose-dependent activities similar to that of the std. quercetin. [on SciFinder (R)]},
  language  = {en}
}
@phdthesis{Yazdanbakhsh2009,
  author    = {Yazdanbakhsh, Nima},
  title     = {Development of a robotized image processing platform to decipher root elongation kinetics in a. thaliana and investigating the role of carbohydrates and the circadian clock genes in detected diurnal patterns},
  address   = {Potsdam},
  pages     = {97 S. : Ill., graph. Darst.},
  year      = {2009},
  language  = {en}
}
@article{YangEisert2009,
  author    = {Yang, Dong and Eisert, Jens},
  title     = {Entanglement combing},
  issn      = {0031-9007},
  doi       = {10.1103/Physrevlett.103.220501},
  year      = {2009},
  abstract  = {We show that all multipartite pure states can, under local operations, be transformed into bipartite pairwise entangled states in a "lossless fashion": An arbitrary distinguished party will keep pairwise entanglement with all other parties after the asymptotic protocol-decorrelating all other parties from each other-in a way that the degree of entanglement of this party with respect to the rest will remain entirely unchanged. The set of possible entanglement distributions of bipartite pairs is also classified. Finally, we point out several applications of this protocol as a useful primitive in quantum information theory.},
  language  = {en}
}
@article{YanRichterShuetal.2009,
  author    = {Yan, Ming and Richter, Eike M. and Shu, Hua and Kliegl, Reinhold},
  title     = {Readers of Chinese extract semantic information from parafoveal words},
  issn      = {1069-9384},
  doi       = {10.3758/Pbr.16.3.561},
  year      = {2009},
  abstract  = {Evidence for semantic preview benefit (PB) from parafoveal words has been elusive for reading alphabetic scripts such as English. Here we report semantic PB for noncompound characters in Chinese reading with the boundary paradigm. In addition, PBs for orthographic relatedness and, as a numeric trend, for phonological relatedness were obtained. Results are in agreement with other research suggesting that the Chinese writing system is based on a closer association between graphic form and meaning than is alphabetic script. We discuss implications for notions of serial attention shifts and parallel distributed processing of words during reading.},
  language  = {en}
}
@phdthesis{Yadav2009,
  author    = {Yadav, Umesh Prasad},
  title     = {Sucrose and trehalose-6-phosphate signalling in "Arabidopsis thaliana"},
  address   = {Potsdam},
  pages     = {X, 156 S. : zahlr. graph. Darst.},
  year      = {2009},
  language  = {en}
}
@article{WyschkonKohnBallaschketal.2009,
  author    = {Wyschkon, Anne and Kohn, Juliane and Ballaschk, Katja and Esser, G{\"u}nter},
  title     = {Sind Rechenst{\"o}rungen genau so h{\"a}ufig wie Lese-Rechtschreibst{\"o}rungen?},
  issn      = {1422-4917},
  doi       = {10.1024/1422-4917.37.6.499},
  year      = {2009},
  abstract  = {Is a specific disorder of arithmetic skills as common as reading/spelling disorder?Background: Referring to the prevalence rates of learning disorders in the research literature, the numbers of mathematics disorder and reading/ spelling disorder are often reported to be identical. However, the correlation between intelligence level and reading/ spelling skills is much weaker than between intelligence and arithmetic skills. If the same definition criterion is applied to both disorders, a lower prevalence rate for mathematics disorder should be expected. Objective: Are there differences in the prevalence estimates for learning disorders depending on the definition criterion? Method: A large representative sample of German students (N = 1970) was used to review the hypothesis. Results: Depending on the definition criterion, we could show a prevalence range of mathematics disorder between 0.1\% and 8.1\% in the same sample. Using the same definition criterion for both learning disorders, there are two to three times as many students with reading/spelling disorder than those with mathematics disorder. Discussion: Whenever children with reading/spelling disorder are compared to children with mathematics disorder, the same definition criterion has to be applied.},
  language  = {de}
}
@article{Wyrwa2009,
  author    = {Wyrwa, Ulrich},
  title     = {Die Internationalen Antij{\"u}dischen Kongresse von 1882 und 1883 in Dresden und Chemnitz : zum Antisemitismus als europ{\"a}ischer Bewegung},
  year      = {2009},
  language  = {de}
}
@article{Wyrwa2009,
  author    = {Wyrwa, Ulrich},
  title     = {Genese und Entfaltung antisemitischer Motiven in Heinrich von Treitschkes Deutscher Geschichte im 19. Jahrhundert},
  isbn      = {978-3- 8375-0114-8},
  year      = {2009},
  language  = {de}
}
@misc{Wustmann2009,
  author    = {Wustmann, Gerrit},
  title     = {Literaturbericht: Iran und die internationale Politik},
  issn      = {0944-8101},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-34100},
  year      = {2009},
  abstract  = {Die vier Buchrezensionenum die Islamische Republik Iran spiegeln die ganze Bandbreite des Dilemmas im Umgang mit dem politisch gewichtigsten und auch umstrittensten Land im Nahen Osten wider. Sie zeigen die tiefe Spaltung, die in der Publizistik gegen{\"u}ber diesem Land existiert; sei es in der Presse oder Fachliteratur.},
  language  = {de}
}
@article{WuLiChenetal.2009,
  author    = {Wu, Ye and Li, Ping and Chen, Maoyin and Xiao, Jinghua and Kurths, J{\"u}rgen},
  title     = {Response of scale-free networks with community structure to external stimuli},
  issn      = {0378-4371},
  doi       = {10.1016/j.physa.2009.03.037},
  year      = {2009},
  abstract  = {The response of scale-free networks with community structure to external stimuli is studied. By disturbing some nodes with different strategies, it is shown that the robustness of this kind of network can be enhanced due to the existence of communities in the networks. Some of the response patterns are found to coincide with topological communities. We show that such phenomena also occur in the cat brain network which is an example of a scale-free like network with community structure. Our results provide insights into the relationship between network topology and the functional organization in complex networks from another viewpoint.},
  language  = {en}
}
@article{WronskiApioPlathetal.2009,
  author    = {Wronski, Torsten and Apio, Ann and Plath, Martin and Averbeck, Christiane},
  title     = {Do ecotypes of bushbuck differ in grouping patterns?},
  issn      = {0873-9749},
  doi       = {10.1007/s10211-009-0058-5},
  year      = {2009},
  abstract  = {Grouping patterns within the genus Tragelaphus suggest that species inhabiting open areas tend to live in larger groups, while species preferring dense habitats live solitarily or in small family groups. We asked if similar variation would be concealed in the within-species variation of bushbuck (Tragelaphus scriptus). Recent molecular phylogeographic analyses revealed several locally adapted forms of bushbuck in different ecoregions on the African continent. We compared group sizes of south-eastern bushbuck (Tragelaphus sylvaticus) among six different populations ("ecotypes"). To date, most data on the social organization of bushbuck have been collected from only one population in Queen Elizabeth National Park (QENP) in Uganda. This particular population, however, inhabits an unusual-comparatively open-habitat type, while bushbuck otherwise inhabit dense habitats, leaving doubt whether data collected in QENP are representative of the entire species. We, therefore, compared grouping patterns between ecotypes inhabiting rather open habitats (e.g., dianae and haywoodi) and ecotypes occupying rather dense habitats (e.g., massaicus and ornatus). In bachelor groups and in all-female (spinster) groups, single sightings were the most frequent "group type" in all populations examined. We detected no significant difference among ecotypes in relative frequencies of group size categories in the case of bachelor groups. Spinster group sizes were slightly (albeit significantly) smaller in QENP than in all other areas. Moreover, a comparison of two areas inside (low human pursuit) and outside Lake Mburo National Park (high hunting pressure) in Uganda revealed no significant difference in grouping patterns in response to human pursuit (as reported for impala [Aepyceros melampus] inhabiting the same area). Altogether, our results suggest that group sizes in bushbuck are not dependent on the habitat type they inhabit; neither does human nuisance have an impact on grouping patterns. Hence, an "almost solitary" lifestyle appears to be a characteristic of the entire taxon.},
  language  = {en}
}
@article{WronskiApioPlath2009,
  author    = {Wronski, Torsten and Apio, Ann and Plath, Martin},
  title     = {Absence of a dominance hierarchy confirms territorial organization in male bushbuck (Tragelaphus scriptus Pallas, 1766)},
  issn      = {0141-6707},
  doi       = {10.1111/j.1365-2028.2007.00876.x},
  year      = {2009},
  abstract  = {It has been suggested that all species of spiral-horned antelopes (Tragelaphini) lack territoriality. Furthermore, some authors suggested that bushbuck (Tragelpahus scriptus) males form dominance hierarchies. In this study, we investigated the dominance relationships in two groups of free-ranging bushbuck males in Queen Elizabeth National Park, Uganda. Adult males dominated young-adult bachelors and subadult males, but no distinct dominance relationships were found among adult males. Landau's index of linearity revealed no linear dominance hierarchy in the study populations. Our results support the idea that adult males are territorial, and overt aggression is directed almost exclusively towards bachelors that challenge territory holders.},
  language  = {en}
}
@book{Wotschack2009,
  author    = {Wotschack, Christiane},
  title     = {Zum Einfluß von Lesestrategien auf Effekte der kognitiven Kontrolle},
  year      = {2009},
  language  = {de}
}
@article{Wotschack2009,
  author    = {Wotschack, Christiane},
  title     = {Zum Einfluss von Lesestrategien auf Effekte der kognitiven Kontrolle},
  series = {Spektrum Patholinguistik},
  volume    = {2},
  journal   = {Spektrum Patholinguistik},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  issn      = {1866-9085},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32636},
  pages     = {69 -- 78},
  year      = {2009},
  abstract  = {Inhalt: 1. Einleitung 1.1 Blickbewegungen beim Lesen 1.2 Kognitive Kontrolle und verteilte Verarbeitung 2. Fragestellungen und Hypothesen 3. Methoden 3.1 Probanden 3.2 Material 3.3 Durchf{\"u}hrung und Auswertung 4. Ergebnisse 4.1 Unterschiede in Effekten der Wortvorhersagbarkeit 4.2 Unterschiede in Effekten der Wortfrequenz 5. Diskussion 6. Literatur},
  language  = {de}
}
@phdthesis{Wotschack2009,
  author    = {Wotschack, Christiane},
  title     = {Eye movements in reading strategies : how reading strategies modulate effects of distributed processing and oculomotor control},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  isbn      = {978-3-86956-021-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-36846},
  school      = {Universit{\"a}t Potsdam},
  pages     = {213},
  year      = {2009},
  abstract  = {Throughout its empirical research history eye movement research has always been aware of the differences in reading behavior induced by individual differences and task demands. This work introduces a novel comprehensive concept of reading strategy, comprising individual differences in reading style and reading skill as well as reader goals. In a series of sentence reading experiments recording eye movements, the influence of reading strategies on reader- and word-level effects assuming distributed processing has been investigated. Results provide evidence for strategic, top-down influences on eye movement control that extend our understanding of eye guidance in reading.},
  language  = {en}
}
@misc{Woop2009,
  author    = {Woop, Gerry},
  title     = {Bentley der Politikpalette : Außenpolitik im Wahlkampf},
  issn      = {0944-8101},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32678},
  year      = {2009},
  abstract  = {Außenpolitik - h{\"a}ufig ein kontrovers diskutiertes Thema. Wie steht es mit der Offenlegung außenpolitischer Grunds{\"a}tze der Parteien in Zeiten des Wahlkampfes? Sollte man sich nur vorsichtig {\"a}ußern, um potentiellen Koalitionspartnern nicht vor den Kopf zu stoßen?},
  language  = {de}
}
@article{Woolford2009,
  author    = {Woolford, Ellen},
  title     = {Aspect splits and parasitic marking},
  series = {Linguistics in Potsdam},
  journal   = {Linguistics in Potsdam},
  number    = {28},
  issn      = {1616-7392},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32236},
  pages     = {39 -- 72},
  year      = {2009},
  abstract  = {Aspect splits can affect agreement, Case, and even preposition insertion. This paper discusses the functional 'why' and the theoretical 'how' of aspect splits. Aspect splits are an economical way to mark aspect by preserving or suppressing some independent element in one aspect. In formal terms, they are produced in the same way as coda conditions in phonology, with positional/contextual faithfulness.This approach captures the additive effects of cross-cutting splits. Aspect splits are analyzed here from Hindi, Nepali, Yucatec Maya, Chontal, and Palauan.},
  language  = {en}
}
@article{WonkeWallschlaeger2009,
  author    = {Wonke, Gundula and Wallschl{\"a}ger, Hans-Dieter},
  title     = {Song dialects in the yellowhammer Emberiza citrinella : bioacoustic variation between and within dialects},
  issn      = {0021-8375},
  doi       = {10.1007/s10336-008-0326-6},
  year      = {2009},
  abstract  = {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.},
  language  = {en}
}
@phdthesis{Wonke2009,
  author    = {Wonke, Christoph},
  title     = {Das deutsche System der Hausm{\"u}llentsorgung : eine normative und positive volkswirtschaftliche Untersuchung},
  publisher = {Lang},
  address   = {Frankfurt am Main},
  isbn      = {978-3-631-58617-4},
  pages     = {235, XLVII S.},
  year      = {2009},
  language  = {de}
}
@article{WolfBleiss2009,
  author    = {Wolf-Bleiß, Birgit},
  title     = {Neologismen},
  series = {Sprachwandel und Entwicklungstendenzen als Themen im Deutschunterricht : fachliche Grundlagen - Unterrichtsanregungen - Unterrichtsmaterialien},
  journal   = {Sprachwandel und Entwicklungstendenzen als Themen im Deutschunterricht : fachliche Grundlagen - Unterrichtsanregungen - Unterrichtsmaterialien},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  isbn      = {978-3-86956-003-8},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-37063},
  pages     = {83 -- 101},
  year      = {2009},
  language  = {de}
}
@article{Wolf2009,
  author    = {Wolf, Klaus},
  title     = {Vom Zweckbau zum Denkmal},
  series = {Milit{\"a}r und Gesellschaft in der fr{\"u}hen Neuzeit},
  volume    = {13},
  journal   = {Milit{\"a}r und Gesellschaft in der fr{\"u}hen Neuzeit},
  number    = {1},
  issn      = {1861-910X},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32028},
  pages     = {122 -- 142},
  year      = {2009},
  abstract  = {Inhalt: - 1. Im Diskurs: Prunkst{\"u}cke, Troph{\"a}en, Altert{\"u}mer - 2. Leere als Symbol - 3. Kunstwerk und Denkmal: Der Bauschmuck - Schlussbetrachtungen},
  language  = {de}
}
@book{WolfPolzenhagen2009,
  author    = {Wolf, Hans-Georg and Polzenhagen, Frank},
  title     = {World Englishes : a cognitive sociolinguistic approach},
  series = {Applications of cognitive linguistics},
  volume    = {8},
  journal   = {Applications of cognitive linguistics},
  publisher = {Mouton de Gruyter},
  address   = {Berlin, New York},
  isbn      = {978-3-11-019633-7},
  doi       = {10.1515/9783110199222},
  pages     = {XIV, 278 S.},
  year      = {2009},
  language  = {en}
}
@article{WolfIgboanusi2009,
  author    = {Wolf, Hans-Georg and Igboanusi, Herbert},
  title     = {The role of ethnically mixed marriages in language shift : a case study of Nigeria's minority languages},
  year      = {2009},
  abstract  = {As the foundation of homes, the marriage institution is an important agent of sociali- zation. In this regard, marriage can be relied upon as a major factor in language and cultural maintenance. However, mixed marriages may contribute to language shift in the home because they can lead to a change in language use patterns among minority language speakers and their children. This means that the likelihood of preserving a minority language is greater in marriages among individuals who speak the same indigenous language than in situations in which spouses speak different languages. This study uses questionnaire data from parents of ethnically mixed marriages to explain how mixed marriages contribute to language shift from minority languages to English (Nigeria's official language), Nigerian Pidgin (informal lingua franca) and the major languages (i.e. Hausa, Igbo and Yoruba) in the home domains. The study shows that the future of minority languages will largely depend on the roles of families and the value attached to minority ethnic identity by young people, particularly those from mixed homes. Keywords: language shift; maintenance; family; minority languages; intermarriage; nigeria},
  language  = {en}
}
@article{WoernervonKorffSchmisingBargheeretal.2009,
  author    = {Woerner, Michael and von Korff Schmising, Clemens and Bargheer, Matias and Zhavoronkov, Nickolai and Vrejoiu, Ionela and Hesse, Dietrich and Alexe, Marin and Elsaesser, Thomas},
  title     = {Ultrafast structural dynamics of perovskite superlattices},
  issn      = {0947-8396},
  doi       = {10.1007/s00339-009-5174-6},
  year      = {2009},
  abstract  = {Femtosecond x-ray diffraction provides direct insight into the ultrafast reversible lattice dynamics of materials with a perovskite structure. Superlattice (SL) structures consisting of a sequence of nanometer-thick layer pairs allow for optically inducing a tailored stress profile that drives the lattice motions and for limiting the influence of strain propagation on the observed dynamics. We demonstrate this concept in a series of diffraction experiments with femtosecond time resolution, giving detailed information on the ultrafast lattice dynamics of ferroelectric and ferromagnetic superlattices. Anharmonically coupled lattice motions in a SrRuO3/PbZr0.2Ti0.8O3 (SRO/ PZT) SL lead to a switch-off of the electric polarizations on a time scale of the order of 1 ps. Ultrafast magnetostriction of photoexcited SRO layers is demonstrated in a SRO/SrTiO3 (STO) SL.},
  language  = {en}
}
@misc{Wittmann2009,
  author    = {Wittmann, Klaus},
  title     = {Die NATO als milit{\"a}rischer Akteur},
  issn      = {0944-8101},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-34189},
  year      = {2009},
  abstract  = {Die NATO gilt als das erfolgreichste Milit{\"a}rb{\"u}ndnis der Geschichte. Dabei war sie immer zugleich auch ein politisches B{\"u}ndnis. Notwendig ist die aktuelle Selbstvergewisserung zu Zweck und Hauptaufgaben. Verteidigung, Stabilisierung Europas und internationale Friedensmissionen werden dazu geh{\"o}ren. Wichtig bleibt ein gemeinsamer Wille zum praktischen Untersetzen durch verbesserte milit{\"a}rische F{\"a}higkeiten. Die Allianz sollte das spezifische milit{\"a}rische Instrument in die breiteren internationalen sicherheitsrelevanten Bem{\"u}hungen einbringen.},
  language  = {de}
}
@article{Wittkopf2009,
  author    = {Wittkopf, Sarah},
  title     = {Von der Einwanderung der Jekim zu ihrer politischen Partizipation bei den Wahlen zum Tel Aviver Stadtrat im Jahr 1936},
  series = {PaRDeS : Zeitschrift der Vereinigung f{\"u}r J{\"u}dische Studien e.V.},
  journal   = {PaRDeS : Zeitschrift der Vereinigung f{\"u}r J{\"u}dische Studien e.V.},
  number    = {15},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  issn      = {1614-6492},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-36235},
  pages     = {39 -- 53},
  year      = {2009},
  language  = {de}
}
@article{Wittig2009,
  author    = {Wittig, Peter},
  title     = {Deutsche Politik in den Vereinten Nationen: Ist Deutschland ein Global Player?},
  series = {Die Vereinten Nationen in den internationalen Beziehungen , 9. Potsdamer UNO-Konferenz am 28. Juni 2008},
  volume    = {2009},
  journal   = {Die Vereinten Nationen in den internationalen Beziehungen , 9. Potsdamer UNO-Konferenz am 28. Juni 2008},
  number    = {8},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-101617},
  pages     = {7 -- 13},
  year      = {2009},
  abstract  = {1. Vorbemerkung 2. Globale Agenda Deutschlands 2. Globales Potenzial Deutschlands 3. Akzeptanz Deutschlands als Global Player 4. Fazit},
  language  = {de}
}
@phdthesis{Witte2009,
  author    = {Witte, Jeannine},
  title     = {Rhabdomerorganisation und -morphogenese im Komplexauge von Drosophila},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-41847},
  school      = {Universit{\"a}t Potsdam},
  year      = {2009},
  abstract  = {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-L{\"a}ngsachse 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 Ph{\"a}nomen wird in der Fachliteratur als rhabdomere twisting bezeichnet und reduziert die Empfindlichkeit f{\"u}r polarisiertes Licht. Es wurde f{\"u}r das Drosophila-Auge gezeigt, dass diese strukturelle Asymmetrie der Sehzellen mit einer molekularen Asymmetrie in der Verteilung phosphotyrosinierter Proteine an die Stielmembran (einem nicht-mikrovill{\"a}ren Bereich der apikalen Plasmamembran) einhergeht. Zudem wurde gezeigt, dass die immuncytochemische Markierung mit anti-Phosphotyrosin (anti-PY) als lichtmikroskopischer Marker f{\"u}r das rhabdomere twisting verwendet werden kann. Bisher wurde haupts{\"a}chlich die physiologische Bedeutung der Rhabdomerverdrehung untersucht. Es ist wenig {\"u}ber die entwicklungs- und zellbiologischen Grundlagen bekannt. Ziel der vorliegenden Arbeit war es, die Identit{\"a}t der phosphotyrosinierten Proteine an der Stielmembran zu kl{\"a}ren und ihre funktionelle Bedeutung f{\"u}r 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. F{\"u}r 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 Pr{\"a}inkubationsexperimente mit anti-PY wurde die Markierung mit anti-pERK bzw. anti-pJNK unterbunden. Diese Ergebnisse sprechen daf{\"u}r, dass pERK und pJNK zu den Proteinen geh{\"o}ren, 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 k{\"o}nnten. Diese Hypothese wurde durch die Analyse von hypermorphen (rl SEM)und hypomorphen (rl 1/rl 10a) Rolled-Mutanten {\"u}berpr{\"u}ft. In der rl SEM-Mutante mit erh{\"o}hter Aktivit{\"a}t der Proteinkinase erfolgte die asymmetrische Positionierung von pERK an der Stielmembran sowie die Mikrovillikippung schon zu einem fr{\"u}heren Zeitpunkt in der pupalen Entwicklung. Im adulten Auge war die anti-PY-Markierung im distalen Bereich der Sehzellen intensiver sowie der Kippwinkel vergr{\"o}ßert. In der rl 1/rl 10a-Mutanten mit reduzierter Kinaseaktivit{\"a}t 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 Auspr{\"a}gung im Adulttier. Die Rhabdomerverdrehung sowie die {\"A}nderung im anti-PY-Markierungsmuster erfolgen an den Sehzellen R1-R6 relativ abrupt auf halber Ommatidienl{\"a}nge, 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 f{\"u}r 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 f{\"u}hrt zu einer Fixierung der Polarit{\"a}t von R1-R6 durch R7. Die Ausf{\"u}hrung der Mikrovillikippung anhand der festgelegten Polarit{\"a}t erfolgt in der sp{\"a}ten Puppenphase. Die Proteinkinase ERK ist an diesem letzten Morphogeneseprozess beteiligt.},
  language  = {de}
}
@phdthesis{Witt2009,
  author    = {Witt, Sandra},
  title     = {Die Rolle der DGDG Synthase DGD1 bei der Galaktolipid Synthese in den H{\"u}llmembranen von Chloroplasten},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33447},
  school      = {Universit{\"a}t Potsdam},
  year      = {2009},
  abstract  = {In den Chloroplasten von h{\"o}heren Pflanzen sind die Galaktolipide Monogalaktosyldiacylglycerol (MGDG) und Digalaktosyldiacylglycerol (DGDG) die am weitesten verbreiteten Lipide. In dieser Forschungsarbeit wurde die Funktion der DGDG Synthase DGD1, und insbesondere die Funktion des N-terminalen Bereichs dieses Enzyms in der Modellpflanze Arabidopsis thaliana untersucht. Die {\"U}berexpression des N-terminalen Bereichs von DGD1 in WT-Col2 resultierte in einem reduzierten Wachstum, welches sich jedoch von der dgd1-1 Mutante unterschied. Dies legte bereits nahe, dass die Expression von N-DGD1 einen negativen Einfluss auf das Wachstum hat. Durch Studien in einem heterologen E.coli Expressionssystem konnte diese These best{\"a}tigt werden. Zellen, die ausschließlich N-DGD1 zusammen mit einer MGD Synthase aus Gurke exprimierten, waren im Wachstum stark beeintr{\"a}chtigt. Nicht nur der N-terminale Bereich von DGD1, auch der N-terminale Bereich von MGD1 besitzt eine Funktion als Transitpeptid und ist somit ein wichtiger Faktor zur korrekten Lokalisierung des MGD1 Proteins. In dieser Arbeit ist es gelungen, ein Fusionskonstrukt aus N-MGD1 und DGD2 in die dgd1-1 Mutante zu transferieren und damit das reduzierte Wachstum zu komplementieren. Fr{\"u}here Versuche, ein reduziertes dgd1-1 Wachstum mit DGD2 allein zu komplementieren, scheiterten. Somit gibt dies einen Hinweis darauf, dass N-MGD1 als Transitpeptid fungieren kann. Bindungsstudien zur Interaktion von DGD1 und N-DGD1 Protein zeigten, dass die polaren Lipide MGDG und DGDG in Wechselwirkung mit dem N-terminalen Bereich von DGD1 treten. Bis zum heutigen Zeitpunkt ist nicht erforscht, wie der Transport von DGDG und MGDG zwischen den H{\"u}llmembranen des Chloroplasten erfolgt. Die in dieser Arbeit angefertigen Bindungsstudien konnten Hinweise darauf geben, dass N-DGD1 als eine Art „Antiporter" fungiert, um MGDG und DGDG zwischen den H{\"u}llmembranen zu transportieren. Weiterhin wurden Bindungsstudien zur Erforschung von Interaktionen der Glykosyltransferasen DGD1, DGD2, MGD1, MGD2 und MGD3 angefertigt. Dabei wurden Wechselwirkungen zwischen den Glykosyltransferasen DGD1, DGD2 und MGD2 detektiert. Interessant ist, dass Hinweise auf eine Dimerbildung bestimmter Enzyme gefunden wurden, so f{\"u}r DGD1 und MGD2. Ein weiterer Ansatz zur Erforschung von Wechselwirkungen von DGD1 Protein mit bis jetzt unbekannten Proteinen war die Expression von DGD1-StrepIITag und DGD1-CTAPTag Fusionsproteinen in dgd1-1 Mutanten. Es wurden f{\"u}r beide Tags transgene Linien generiert, die im Wachstum komplementiert waren und wildtyp{\"a}hnliche Mengen an DGDG akkumulierten. Die Expression der verschiedenen Tags in den Pflanzen war sehr unterschiedlich, wobei der DGD1-CTAP-Tag am st{\"a}rksten exprimiert war. Mit Pflanzenmaterial dieser Linien kann nun eine Aufreinigung des getaggten Proteins und eventueller Interaktionspartner erfolgen.},
  language  = {de}
}