@article{AlbrechtHaebelKochetal.2004, author = {Albrecht, Tanja and Haebel, Sophie and Koch, Anke and Krause, Ulrike and Eckermann, Nora and Steup, Martin}, title = {Yeast glycogenin (Glg2p) produced in Escherichia coli is simultaneously glucosylated at two vicinal tyrosin residues but results in a reduced bacterial glycogen accumulation}, year = {2004}, abstract = {Saccharomyces cerevisiae possesses two glycogenin isoforms (designated as Glg1p and Glg2p) that both contain a conserved tyrosine residue, Tyr232. However, Glg2p possesses an additional tyrosine residue, Tyr230 and therefore two potential autoglucosylation sites. Glucosylation of Glg2p was studied using both matrix-assisted laser desorption ionization and electrospray quadrupole time of flight mass spectrometry. Glg2p, carrying a C-terminal (His(6)) tag, was produced in Escherichia coli and purified. By tryptic digestion and reversed phase chromatography a peptide (residues 219-246 of the complete Glg2p sequence) was isolated that contained 4-25 glucosyl residues. Following incubation of Glg2p with UDPglucose, more than 36 glucosyl residues were covalently bound to this peptide. Using a combination of cyanogen bromide cleavage of the protein backbone, enzymatic hydrolysis of glycosidic bonds and reversed phase chromatography, mono- and diglucosylated peptides having the sequence PNYGYQSSPAM were generated. MS/MS spectra revealed that glucosyl residues were attached to both Tyr232 and Tyr230 within the same peptide. The formation of the highly glucosylated eukaryotic Glg2p did not favour the bacterial glycogen accumulation. Under various experimental conditions Glg2p-producing cells accumulated approximately 30\% less glycogen than a control transformed with a Glg2p lacking plasmid. The size distribution of the glycogen and extractable activities of several glycogen-related enzymes were essentially unchanged. As revealed by high performance anion exchange chromatography, the intracellular maltooligosaccharide pattern of the bacterial cells expressing the functional eukaryotic transgene was significantly altered. Thus, the eukaryotic glycogenin appears to be incompatible with the bacterial initiation of glycogen biosynthesis}, language = {en} } @article{PacholskyVakeelHimmeletal.2004, author = {Pacholsky, Dirk and Vakeel, Padmanabhan and Himmel, Mirko and Lowe, T. and Stradal, T. and Rottner, K. and F{\"u}rst, Dieter Oswald and vanderVen, Peter F. M.}, title = {Xin repeats define a novel actin-binding motif}, issn = {0021-9533}, year = {2004}, abstract = {Xin is a protein that is expressed during early developmental stages of cardiac and skeletal muscles. Immunolocalization studies indicated a peripheral localization in embryonic mouse heart, where Xin localizes with beta- catenin and N-cadherin. In adult tissues, Xin is found primarily in the intercalated discs of cardiomyocytes and the myotendinous junctions of skeletal muscle cells, both specialized attachment sites of the myofibrillar ends to the sarcolemma. A large part of the Xin protein consists of unique 16 amino acid repeats with unknown function. We have investigated the characteristics of the Xin repeats by transfection experiments and actin-binding assays and ascertained that, upon expression in cultured cells, these repeats bind to and stabilize the actin-based cytoskeleton. In vitro co- sedimentation assays with skeletal muscle actin indicated that they not only directly bind actin filaments, but also have the capability of arranging microfilaments into networks that sediment upon low-speed centrifugation. Very similar repeats were also found in Xin-repeat protein 2' (XIRP2), a novel protein that seems to be expressed mainly in striated muscles. Human XIRP2 contains 28 Xin repeats with properties identical to those of Xin. We conclude that the Xin repeats define a novel, repetitive actin-binding motif present in at least two different muscle proteins. These Xin- repeat proteins therefore constitute the first two members of a novel family of actin-binding proteins}, language = {en} } @article{WilkePartzschFarges2004, author = {Wilke, Max and Partzsch, G. M. and Farges, Francois}, title = {XAFS of iron in silicate melt at high temperature}, issn = {0024-4937}, year = {2004}, language = {en} } @article{OskinovaFeldmeierHamann2004, author = {Oskinova, Lida and Feldmeier, Achim and Hamann, Wolf-Rainer}, title = {X-ray emission lines from inhomogeneous stellar winds}, issn = {0004-6361}, year = {2004}, abstract = {It is commonly adopted that X-rays from O stars are produced deep inside the stellar wind, and transported outwards through the bulk of the expanding matter which attenuates the radiation and affects the shape of emission line profiles. The ability of the X-ray observatories Chandra and XMM-Newton to resolve these lines spectroscopically provided a stringent test for the theory of the X-ray production. It turned out that none of the existing models was able to fit the observations consistently. The possible caveat of these models was the underlying assumption of a smooth stellar wind. Motivated by the evidence that the stellar winds are in fact structured, we present a 2-D numerical model of a stochastic, inhomogeneous wind. Small parcels of hot, X-ray emitting gas are permeated by cool, absorbing wind material which is compressed into thin shell fragments. Wind fragmentation alters the radiative transfer drastically, compared to homogeneous models of the same mass-loss rate. X-rays produced deep inside the wind, which would be totally absorbed in a homogeneous flow, can effectively escape from a fragmented wind. The wind absorption becomes wavelength independent if the individual fragments are optically thick. The X-ray line profiles are flat-topped in the blue part and decline steeply in the red part for the winds with a short acceleration zone. For the winds where the acceleration extends over significant distances, the lines can appear nearly symmetric and only slightly blueshifted, in contrast to the skewed, triangular line profiles typically obtained from homogeneous wind models of high optical depth. We show that profiles from a fragmented wind model can reproduce the observed line profiles from zeta Orionis. The present numerical modeling confirms the results from a previous study, where we derived analytical formulae from a statistical treatment}, language = {en} } @article{HennebergPanznerPietschetal.2004, author = {Henneberg, Oliver and Panzner, Tobias and Pietsch, Ullrich and Geue, Thomas and Saphiannikova, Marina and Rochon, Paul and Finkelstein, Kenneth D.}, title = {X-ray and VIS light scattering from light-induced polymer gratings}, issn = {0044-2968}, year = {2004}, abstract = {Sinusoidally shaped surface relief gratings made of polymer films containing, azobenzene moieties can be created by holographic illumination with laser light of about lambda approximate to 500 nm. The remarkable material transport takes place at temperatures far (100 K) below the glass transition temperature of the material. As probed by visible light scattering the efficiency of grating formation crucially depends on the polarization state of the laser light and is maximal when circular polarization is used. In contrast to VIS light scattering X-ray diffraction is most sensitive for periodic surface undulations with amplitudes below 10 nm. Thus, combined in-situ X-ray and visible light scattering at CHESS were used to investigate the dynamics of surface relief grating formations upon laser illumination. The time development of grating peaks up to 9th order at laser power of P = 20 mW/cm(2) could be investigated, even the onset of grating formation as a function of light polarization. A linear growth of grating amplitude was observed for all polarizations. The growth velocity is maximal using circularly polarized light but very small for s-polarized light}, language = {en} } @article{FrischHahneFriederici2004, author = {Frisch, Stefan and Hahne, A. and Friederici, A. D.}, title = {Word category and verb-argument structure information in the dynamics of parsing}, issn = {0010-0277}, year = {2004}, abstract = {One of the core issues in psycholinguistic research concerns the relationship between word category information and verb-argument structure (e.g. transitivity) information of verbs in the process of sentence parsing. In two experiments (visual versus auditory presentation) using event-related brain potentials (ERPs), we addressed this question by presenting sentences in which the critical word simultaneously realized both a word category and a transitivity violation. ERPs for sentences with both types of violation clustered with the patterns for sentences with a word category violation only, but were different from the patterns elicited by argument structure violations in isolation, since only the latter elicited an N400 ERP component. The finding that an argument structure violation evoked an N400 only if the phrase structure of the respective sentence was correct suggests that a successful integration of the word category information of a verb functionally precedes the application of its argument structure information. (C) 2003 Elsevier B.V. All rights reserved}, language = {en} } @article{BroschRippl2004, author = {Brosch, Renate and Rippl, Gabriele}, title = {Word and image : Intermedial Relationshs}, isbn = {3-88476- 702-X}, year = {2004}, language = {en} } @article{Kern2004, author = {Kern, Andrea}, title = {Why do our reasons come to an end? : the concept of finite knowledge}, year = {2004}, language = {en} } @article{PietschJarreSaldittetal.2004, author = {Pietsch, Ullrich and Jarre, A. and Salditt, T. and Panzner, Tobias and Pfeiffer, F.}, title = {White beam x-ray waveguide optics}, year = {2004}, abstract = {We report a white beam x-ray waveguide (WG) experiment. A resonant beam coupler x-ray waveguide (RBC) is used simultaneously as a broad bandpass (or multibandpass) monochromator and as a beam compressor. We show that, depending on the geometrical properties of the WG, the exiting beam consists of a defined number of wavelengths which can be shifted by changing the angle of incidence of the white x-ray synchrotron beam. The characteristic far-field pattern is recorded as a function of exit angle and energy. This x-ray optical setup may be used to enhance the intensity of coherent x-ray WG beams since the full energetic acceptance of the WG mode is transmitted. (C) 2004 American Institute of Physics}, language = {en} } @article{HuppertBlasiusStone2004, author = {Huppert, Amit and Blasius, Bernd and Stone, Lewi}, title = {What minimal models can tell : a reply to van Nes and Scheffer}, year = {2004}, language = {en} }