@article{FrankeKartenbeckKrienetal.1972,
  author    = {Franke, Werner W. and Kartenbeck, J{\"u}rgen and Krien, S. and VanderWoude, W. J. and Scheer, Ulrich and Morr{\´e}, D. J.},
  title     = {Inter- and intracisternal elements of the Golgi apparatus: A system of membrane-to-membrane cross-links},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39514},
  year      = {1972},
  abstract  = {Electron opaque cross-bridge structures span the inter- and intracisternal spaces and provide membrane-to-membrane connections between adjacent cisternae of dictyosomes of pollen tubes of Clivia and Lilium. Additionally, the classic intercisternal rods, characteristic of intercisternal regions near the maturing face of dictyosomes, are connected with the adjacent membranes through similar cross-bridge elements. We suggest that these structural links are responsible for maintaining the flattened appearance of the central parts of Golgi apparatus cisternae as well as for the coherence of cisternae within the stack. Observations on other plant (e.g. microsporocytes of Canna) and animal cells (e.g. rodent liver and hepatoma cells, newt spermatocytes) show that such an array of membrane cross-links is a universal feature of Golgi apparatus architecture. The cross-bridges appear as part of the complex "zone of exclusion" which surrounds dictyosomes, entire Golgi apparatus and Golgi apparatus equivalents in a variety of cell types.},
  language  = {en}
}
@article{ScheerKartenbeckTrendelenburgetal.1976,
  author    = {Scheer, Ulrich and Kartenbeck, J{\"u}rgen and Trendelenburg, Michael F. and Stadler, Joachim and Franke, Werner W.},
  title     = {Experimental disintegration of the nuclear envelope: evidence for pore-connecting fibrils},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39735},
  year      = {1976},
  abstract  = {The disintegration of the nuclear envelope has been examined in nuclei and nuclear envelopes isolated from amphibian oocytes and rat liver tissue, using different electron microscope techniques (ultrathin sections and negatively or positively stained spread preparations). Various treatments were studied, including disruption by surface tension forces, very low salt concentrations, and non ionic detergents such as Triton X-lOO and Nonidet P-40. The high local stability of the cylinders of nonmembranous pore complex material is emphasized. As progressive disintegration occurred in the membrane regions, a network of fibrils became apparent which interconnects the pore complexes and is distinguished from the pore complexassociated intranuclear fibrils. This network might correspond to an indistinct lamella, about 15 - 20 nm thick, located at the level of the inner nuclear membrane, which is recognized in thin sections to bridge the interpore distances. With all disintegration treatments a somewhat higher susceptibility of the outer nuclear membrane is notable, but a selective removal does not take place. Final stages of disintegration are generally characterized by the absence of identifiable, membrane- like structures. Analysis of detergent-treated nuclei and nuclear membrane fractions shows almost complete absence of lipid components but retention of significant amount of glycoproteins with a typical endomembrane-type carbohydrate pattern. Various alternative interpretations of these observations are discussed. From the present observations and those of Aaronson and Blobel (1,2), we favor the notion that threadlike intrinsic membrane components are stabilized by their attachment to the pore complexes, and perhaps also to peripheral nuclear structures, and constitute a detergent-resistant, interpore skeleton meshwork.},
  language  = {en}
}
@article{TrendelenburgScheerFranke1973,
  author    = {Trendelenburg, Michael F. and Scheer, Ulrich and Franke, W. W.},
  title     = {Structural organization of the transcription of ribosomal DNA in oocytes of the house cricket},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-33113},
  year      = {1973},
  abstract  = {No abstract available},
  language  = {en}
}
@article{ScheerRaska1987,
  author    = {Scheer, Ulrich and Raska, I.},
  title     = {Immunocytochemical localization of RNA polymerase I in the fibrillar centers of nucleoli},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39618},
  year      = {1987},
  abstract  = {No abstract available},
  language  = {en}
}
@article{FischerHockScheer1993,
  author    = {Fischer, Dagmar and Hock, Robert and Scheer, Ulrich},
  title     = {DNA Topoisomerase II is not detectable on lampbrush chromosomes but enriched in the amplified nucleoli of xenopus oocytes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-32654},
  year      = {1993},
  abstract  = {In somatic cells DNA topoisomerase II (topo II) is thought to be involved in the domain Organization of the genome by anchoring the basis of chromatin loops to a chromosomal scafFold. Lampbrush chromosomes of am-phibian oocytes directly display this radial loop Organization in cytological preparations. In order to find out whether topo II may play a role in the Organization of these meiotic chromosomes, we performed immunofluorescence studies using antibodies against Xenopus topo II. Our results indicate that topo II is apparently absent from lampbrush chromosomes and is hence unlikely to act as a "fastener" of the numerous lateral chromosomal loops. Topo II was, however, enriched in the amplified nucleoli of Xenopus oocytes.},
  language  = {en}
}
@article{FrankeScheer1972,
  author    = {Franke, Werner W. and Scheer, Ulrich},
  title     = {Structural details of dictyosomal pores},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-32155},
  year      = {1972},
  abstract  = {Structural details of the dictyosomal pores in several plant cell types are described from tangential and cross sections of Golgi cisternae. Frequency distributions of the sizes of such Golgi pores are given and compared with the corresponding values of nuclear pores in the same cells. Golgi pore inner diameters are less homogeneously distributed and can be as small as 100 A or less. They are not simply cisterna I holes, but are often associated with centrally located electron dense granules or rods and with inner pore filaments. This organization, which is very common in dictyosomal pores in plant and animal cells, has some similarities with the structural architecture of nuclear envelope and annulate lamellar pore complexes. The particulate material associated with the dictyosomal pores shows spatial and structural relationship to cytoplasmic ribosomes. Possible modes of Golgi pore formation and some consequences of these observations for interpretation of nuclear pore structures are discussed.},
  language  = {en}
}
@article{Scheer1982,
  author    = {Scheer, Ulrich},
  title     = {Biologische Objekte im Transmissions-Elektronenmikroskop (Teil 4): Spreitungstechniken},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39652},
  year      = {1982},
  abstract  = {Visualizing nucleic acids (DNA, RNA), nucleoprotein complexes and chromatin requires the use of special electron microscopicspreading techniques. In part 4 (27 refs.), methods are outlined for spreading DNA and RNA molecules for electron microscopic observation, these methods using modifications of the basic protein film method developed by A. Kleinschmidt and R. K. Zahn (1959). Hybridization techniques that allow the observation of heteroduplexes formed between two DNA molecules or between DNA and RNA molecules are reviewed, with special emphasis being placed on the DNA-RNA hybrids as a tool for elucidating RNA splicing. Techniques for studying DNA-protein interactions without the use of a protein monolayer film are mentioned. Finally, the "Miller spreading technique" for visualizing the nucleosomal organization of eukaryotic chromatin as well as the transcription of genes is discribed and illustrated.},
  language  = {de}
}
@article{ScheerKnecht1971,
  author    = {Scheer, Ulrich and Knecht, Sigrid},
  title     = {Die V{\"o}gel der Azoren},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39668},
  year      = {1971},
  abstract  = {W{\"a}hrend einer viermonatigen Reise zu allen neun Azoreninseln wurde der gesamte Brutvogelbestand dieses Archipels untersucht. Die Befunde sind in einer detaillierten Artenliste zusammengefaßt, erg{\"a}nzt durch {\"o}kologische und brutbiologische Anmerkungen. Zahlreiche Beobachtungen lassen vermuten, daß vor allem Stieglitz und Kanarienvogel t{\"a}gliche und auch jahreszeitlich bedingte interinsulare Fl{\"u}ge unternehmen. Die Laut{\"a}ußerungen sechs verschiedener Vogel arten sind in Klangspektrogrammen dargestellt. Ein mathematischer Ansatz zeigt, daß sich die Anzahl der auf einer bestimmten Insel br{\"u}tenden Landvogelarten umgekehrt proportional zur Entfernung zum europ{\"a}ischen Festland und proportional zum Logarithmus naturalis der Inselfl{\"a}che verh{\"a}lt. Die abgeleitete Formel l{\"a}ßt sich prinzipiell auch auf andere Atlantikinseln anwenden, die weitgehend vom Festland isoliert sind.},
  language  = {de}
}
@article{FrankeScheerSpringetal.1976,
  author    = {Franke, Werner W. and Scheer, Ulrich and Spring, Herbert and Trendelenburg, Michael F. and Krohne, G.},
  title     = {Morphology of transcriptional units of rDNA: evidence for transcription in apparent spacer intercepts and cleavages in the elongating nascent RNA},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39681},
  year      = {1976},
  abstract  = {Several types of "irregular" structures in the arrangement of lateral fibrils were noted in electron microscopic preparations of transcriptionally active nucleolar chromatin from various plant and animal cells. Such forms include: I. Disproportionately long lateral fibrils which occur either as individual fibrils or in groups; 2. "Prelude complexes" and other arrangements of lateral fibrils in apparent spacer intercepts; 3. Thickening of the rDNA chromatin axis at the starting end of pre-rRNA matrix units; 4. Extremely long matrix units , the length of which exceeds that of the rDNA (double-strand) sequence complementary to the specific pre-rRN A (for abbreviations see text). In addition, the stability of high molecular weight RNAs contained in the nucleolar ribonucleoproteins during the preparation for electron microscopy was demonstrated by gel electrophoresis. The observations indicate that the morphological starting point of a pre-rRNA matrix unit is not necessarily identical with the initiation site for synthesis of pre-rRNA, but they rather suggest that the start of the transcriptional unit is located at least O.2-D.8 JLm before the matrix unit and that parts of the "apparent spacer" are transcribed. It is proposed that the pre-rRN A molecules do not represent the primary product of rDNA transcription but rather relatively stable intermediate products that have already been processed during transcription.},
  language  = {en}
}
@article{Linsenmair1979,
  author    = {Linsenmair, Karl Eduard},
  title     = {Untersuchungen zur Soziobiologie der W{\"u}stenassel Hemilepistus reaumuri und verwandter Isopodenarten (Isopoda, Oniscoidea): Paarbildung und Evolution der Monogamie},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-30854},
  year      = {1979},
  abstract  = {The desert isopod, Hemilepistus reaumuri, extremely common in the arid regions of North Africa and Asia Minor, depends upon the burrows it itself digs for survival during the hotter parts of the year. The dig-ging of new burrows is limited by chmatic conditions to a short period during the spring. Burrows must be constantly defendet - especially against roving eonspecifics. The decisive problem of a connnuous burrow defense is solved through cooperative behavior: the adult woodlice form monogamous pairs whose partners recognize one another individually. Here, questions on the binding of partners, especially the problem of the binding of male to female will be treated upon, along with questions on the evolution of monogamy, wherein the purely maternal families of Porcellio species will be taken as models for intermedi{\"a}re stages. At first, males olHemilepistus are not permitted to copulate at all; later, for a relatively long period, they are only permitted incomplete copulations, the females alone have control over the partunal ecdysis; they alone determine the moment of final copulations. Under the thermal conditions prevalent during the season of pair formation, a female irreversibly induces a parturial ecdysis only when it has spent a minimum of sev-eral days in her own burrow with a specific male. At higher average temperatures, the number of females which undergo parturial ecdyses without these preconditions increases sharply. Males cannot greatly lnrlu-ence the willingness of females to reproduce with the investment they make in the digging of burrows; the factors deciding this are the male's presence and its role as guard. The first condition necessary for the genesis of monogamy might have been the evolution of a stnc{\"u}y lo-cation-dependent copulatory behavior, which guaranteed the male exclusive mating pnveliges with the female whose location - the burrow - he acheived control of. A male must, under these conditions, serve guard duty in his own interest, and defend the burrow against competitors (Cf or 2) seeking an already-dug burrow. The decisive advantage for the female in the beginning of the development was probably that she could leave the burrow for extended feeding excursions, whereas alone it would have to either completely forego nourishment or, as is the case with the Porcellio species mentioned, must greatly restrict the spectrum of food that it can use (to that which is to be found only a short distance from the burrow and which can eas-ily be carried inside the burrow). This could be a disadvantage, especially during egg production. Necessary to the male's successful defense of the burrow is that he recognises his female. Studies of the Canary Island Porcellio species have shown over which pathways and under what selection pressures the recopinon of individuals, as is realized mHemilepistus, could have evolved. Females can bind males longer, the longer the period of their attraction is extended: Females olHemilepistus reaumuri have been proven to be al·ready att-ractive before they are ready to copulate and still remain attractive after they have copulated. The conse-quences of the last fact will be discussed. The question of why the males remain with the females after the parturial ecdysis will also be discussed: The great danger to the male's investment resulting from a tooi early abandoning, and the low probability of successfully finding another partner after a later abandomng should prevent a positive balance in the males' cost-effecriveness calculations.},
  language  = {de}
}
@article{BringmannZagstSchoeneretal.1991,
  author    = {Bringmann, Gerhard and Zagst, Rainer and Sch{\"o}ner, Bernd and Busse, Holger and Hemmerling, Martin and Burschka, Christian},
  title     = {Acetogenic Isoquinoline Alkaloids. XXIII. Structure of the Naphthyl Isoquinoline Alkaloid Dioncophylline A},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-31331},
  year      = {1991},
  abstract  = {No abstract available},
  subject      = {Chemie},
  language  = {en}
}
@article{AlbertBerningBurschkaetal.1981,
  author    = {Albert, Bernhard and Berning, Wilfried and Burschka, Christian and H{\"u}nig, Siegfried and Martin, Hans-Dieter and Prokschy, Frank,},
  title     = {Transanulare Wechselwirkung des Azo-Chromophors inisodrinanalogen Systemen},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-31328},
  year      = {1981},
  abstract  = {No abstract available},
  subject      = {Chemie},
  language  = {de}
}
@article{FialaLinsenmairMaschwitz1994,
  author    = {Fiala, Brigitte and Linsenmair, Karl Eduard and Maschwitz, Ulrich},
  title     = {Diversit{\"a}t von Interaktionen zwischen Ameisen und Pflanzen im s{\"u}dostasiatischen Regenwald},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-32894},
  year      = {1994},
  abstract  = {Assoziationen von Ameisen mit Pflanzen (und oft noch mit pflanzensaugenden Insekten als drittem Partner) d{\"u}rften eine Ursache des Artenreichtums und der hohen Abundanzen tropischer Formicidae sein. Die von den Ameisen genutzten Pflanzen bieten entweder Nahrung an, {\"u}ber extraflorale Nektarien und/oder N{\"a}hrk{\"o}rperchen, oder aber - bei den eigentlichen Myrmekophyten - Nistraum und z.T. auch Nahrung. Diese Beziehungen zeichnen sich durch unterschiedliche Nutzungsweisen und Nutzungsintensit{\"a}ten und damit stark differierende Abh{\"a}ngigkeit der Partner voneinander aus. Ein besonders breites Spektrum von Ameisen-Pflanzen-Assoziationen finden wir in der pal{\"a}otropischen Baumgattung Macaranga (Euphorbiaceae), die sich daher als Modellsystem f{\"u}r vergleichende Untersuchungen hervorragend eignet. Die Grundfrage unserer Untersuchungen an diesem System lautet: Verl{\"a}uft aufgrund der ausgepr{\"a}gt mosaikartigen Verteilung der von den myrmekophilen Pflanzen angebotenen Nahrungs- und Nistraumressourcen die Neu- und Wiederbesiedlung von Habitaten durch die Ameisen in Form von Zufallsprozessen? Oder werden, im Gegenteil, durch diesen Umstand Spezialisierungen seitens der Ameisen gef{\"o}rdert und die Zusammensetzung der Lebensgemeinschaften dadurch st{\"a}rker deterministisch gepr{\"a}gt? Unsere bisherigen Untersuchungen zeigen, daß beide Prinzipien wirken. Bei der alleinigen Nutzung von Nahrungsressourcen fehlen spezialisierte Beziehungen weitgehend und stochastische Ereignisse d{\"u}rften sehr h{\"a}ufig die Pflanzen-Ameisen-Assoziation bestimmen. Bei den eigentlichen Myrmekophyten hingegen ist die Auswahl der assozierten Ameisen viel st{\"a}rker determiniert, ganz besonders dann, wenn der Wohnraum, den die Pflanze offeriert, nur durch aktives {\"O}ffnen seitens der Ameisen erschlossen werden kann.},
  language  = {de}
}
@article{ScheerSommervilleMueller1980,
  author    = {Scheer, Ulrich and Sommerville, John and M{\"u}ller, Ulrike},
  title     = {DNA is assembled into globular supranucleosomal chromatin structures by nuclear contents of amphibian oocytes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39671},
  year      = {1980},
  abstract  = {The assembly of DNA into nucleosomal and supranucleosomal chromatin structures has been studied (i) by injection of circular DNA molecules (plasmids) into nuclei of Pleurodeles waltlii oocytes; and (ii) by in vitro incubation of plasmid molecules with the supernatant fraction from oocyte nuclei of Pleurodeles and Xenopus laevis, followed by purification of nucleoprotein structures formed with sucrose gradient centrifugation. [n both types of experiments , spread preparations of the newly assembled and transcriptionally inactive chromatin , examined by electron microscopy , show dense globular higher order (supranucleosomal) packing forms. Under partially relaxing (low salt) preparation conditions granular chromatin subunits of about 30 nm diameter can be seen either as widely spaced particles or in closely packed aggregates. The transcriptionally inactive endogenous chromatin of chromomeres of lampbrush chromosomes is arranged in similar higher order chromatin units. A correlation is found between the sizes of the DN A molecule probes used and the numbers of nucleosomes and higher order globules in the assembled chromatin structures. After prolonged dispersion in low salt buffers , these globular chromatin units unfold into chains of7-12 nucleosomes. The results support the concept that chromatin is arranged , under physiological ion concentrations as they are present in the nucleus , in supranucleosomal units of globular morphology.},
  language  = {en}
}
@article{HuegleHazanScheeretal.1985,
  author    = {H{\"u}gle, Barbara and Hazan, Rachel and Scheer, Ulrich and Franke, Werner W.},
  title     = {Localization of ribosomal protein S1 in the granular component of the interphase nucleolus and its distribution during mitosis},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39695},
  year      = {1985},
  abstract  = {Using antibodies to various nucleolar and ribosomal proteins, we define, by immunolocalization in situ, the distribution of nucleolar proteins in the different morphological nucleolar subcompartments. In the present study we describe the nucleolar localization of a specific ribosomal protein (51) by immunofluorescence and immunoelectron microscopy using a monoclonal antibody (R5 1-105). In immunoblotting experiments, this antibody reacts specifically with the largest and most acidic protein of the small ribosomal subunit (51) and shows wide interspecies cross-reactivity from amphibia to man. Beside its localization in cytoplasmic ribosomes, this protein is found to be specifically localized in the granular component of the nucleolus and in distinct granular aggregates scattered over the nucleoplasm. This indicates that ribosomal protein 51, in contrast to reports on other ribosomal proteins, is not bound to nascent pre-rRNA transcripts but attaches to preribosomes at later stages of rRNA processing and maturation. This protein is not detected in the residual nucleolar structures of cells inactive in rRNA synthesis such as amphibian and avian erythrocytes. During mitosis, the nucleolar material containing ribosomal protein 51 undergoes a remarkable transition and shows a distribution distinct from that of several other nucleolar proteins. In prophase, the nucleolus disintegrates and protein 51 appears in numerous small granules scattered throughout the prophase nucleus. During metaphase and anaphase, a considerable amount of this protein is found in association with the surfaces of all chromosomes and finely dispersed in the cell plasm. In telophase, protein 51-containing material reaccumulates in granular particles in the nucleoplasm of the newly formed nuclei and, finally, in the re-forming nucleoli. These observations indicate that the nucleolus-derived particles containing ribosomal protein 51 are different from cytoplasmic ribosomes and, in the living cell, are selectively recollected after mitosis into the newly formed nuclei and translocated into a specific nucleolar subcompartment, i.e ., the granular component. The nucleolar location of ribosomal protein 51 and its rearrangement du'ring mitosis is discussed in relation to the distribution of other nucleolar proteins.},
  subject      = {Cytologie},
  language  = {en}
}
@article{ScheerHinssenFrankeetal.1984,
  author    = {Scheer, Ulrich and Hinssen, Horst and Franke, Werner W. and Jockusch, Brigitte M.},
  title     = {Microinjection of actin-binding proteins and actin antibodies demonstrates involvement of nuclear actin in transcription of lampbrush chromosomes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39706},
  year      = {1984},
  abstract  = {Nuclei of amphibian oocytes contain large amounts of actin, mostly in unpolymerized or short-polymer form. When antibodies to actin or actin-binding proteins (fragmin and the actin modulator from mammalian smooth muscle) are injected into nuclei of living oocytes of Pleurodeles waltlii, transcription of the lampbrush chromosomes, but not of the rRNA genes, is inhibited. When transcription is repressed by drugs or RNA is digested by microinjection of RNAase into oocyte nuclei, an extensive meshwork of actin filament bundles is seen in association with the isolated lampbrush chromosomes. These observations indicate a close relationship between the state of nuclear actin and transcriptional activity and suggest that nuclear actin may be involved in transcriptional events concerning protein-coding genes.},
  language  = {en}
}
@article{ScheerHansmannFalketal.1986,
  author    = {Scheer, Ulrich and Hansmann, Paul and Falk, Heinz and Sitte, Peter},
  title     = {Ultrastructural localization of DNA in two Cryptomonas species by use of a monoclonal DNA-antibody},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39746},
  year      = {1986},
  abstract  = {Immunogold cytochemistry - DNA localization - Cryptomonas nucleomorph The distribution and subcellular localization of DNA in the unicellular alga Cryptomonas has been investigated electron-microscopically by indirect immunocytochemistry, using a monoclonal DNA antibody and a gold-Iabeled secondary antibody. This technique proved to be very sensitive and entirely specific. DNA could be demonstrated in four different compartments (nucleus, nucleomorph, plastid, and mitochondrion). Within the plastid, DNA is concentrated in stroma regions that are localized preferentially around the center of the organelle. The mitochondrion contains several isolated DNA-containing regions (nucleoids). Within the nucleus, most of the DNA is localized in the 'condensed' chromatin. DNA was also detectable in small areas of the nucleolus, whereas the interchromatin space of the nucleus appeared almost devoid of DNA. Within the nucleomorph, DNA is distributed inhomogeneously in the matrix. DNA could furthermore be detected in restricted areas of the 'fibrillogranular body' of the nucleomorph, resembling the situation encountered in the nucleol us. The presence of DNA and its characteristic distribution in the nucleomorph provide additional, strong evidence in favour of the interpretation of that organelle as the residual nucleus of a eukaryotic endosymbiont in Cryptomonas.},
  subject      = {Cytologie},
  language  = {en}
}
@article{Scheer1978,
  author    = {Scheer, Ulrich},
  title     = {Changes of nucleosome frequency in nucleolar and non-nucleolar chromatin as a function of transcription: an electron microscopic study},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39750},
  year      = {1978},
  abstract  = {The morphology of nucleolar and non-nucleolar (Iampbrush chromosome loops) chromatin was studied in the electron microscope during states of reduced transcriptional activity in amphibian oocytes (Xenopus laevis, Triturus alpestris, T. cristatus). Reduced transcriptional activity was observed in maturing stages of oocyte development and after treatment with an inhibitor, actinomycin D. Strands of nucleolar chromatin appear smooth and thin, and contain only few, if any, nucleosomal particles in the transcribed units. This is true whether they are densely or only sparsely covered with lateral ribonucleoprotein fibrils. This smooth and non-nucleosomal character is also predominant in the interspersed, apparently nontranscribed rDNA spacer regions. During inactivation, however, nucleolar chromatin frequently and progressively assumes a beaded appearance in extended fibril-free-that is, apparently nontranscribed - regions. I n either fUll-grown 00- cytes or late after drug treatment, most of the nucleolar chromatin is no longer smooth and thin, but rather shows a beaded configuration indistinguishable from inactive non - nucleolar chromatin. In many chromatin strands, transitions of fibril-associated regions of smooth character into beaded regions wihout lateral fibrils are seen. Similarly, in the non-nucleolar chromatin of the retracting lampbrush chromosome loops, reduced transcriptional activity is correlated with a change from smooth to beaded morphology. Here, however, beaded regions are also commonly found interspersed between the more or less distant bases of the lateral fibrils, the putative transcriptional complexes. I n both sorts of chromatin, detergents (in particular Sarkosyl) that remove most of the chromatin proteins including histones from the DNA axis but leave the RNA polymerases of the transcriptional complexes attached were used to discriminate between polymerases and nucleosomal particles. The results suggest that nucleosomes are absent in heavily transcribed chromatin regions but are reformed after inactivation. In contrast to the findings with inactivated nucleolar genes, in lampbrush chromosome loops the beaded nucleosomal configuration appears to be assumed also in regions within transcriptional units that, perhaps temporarily, are not involved in transcription.},
  language  = {en}
}
@article{ScheerSommerville1981,
  author    = {Scheer, Ulrich and Sommerville, J.},
  title     = {Structural organization of nascent transcripts and hnRNA molecules in amphibian oocytes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39765},
  year      = {1981},
  abstract  = {Comparisons ofrelative lengths oflampbrush loops, nascent RNP transcripts and hnRNA molecules from oocytes of amphibia with different C-values show that there is an increasing trend in loop, and transcriptional unit, length with increase in genome size but no increasing trend with respect to RN A contour length.The formation of duplex regions and circles in RNP fibrils indicates that RNA processing may occur within the nascent fibrils. The hnRNA molecules from oocytes of the various amphibia readily form intermolecular duplex structures. These complementary sequences have a low kinetic complexity and are transcribed from highly repetitive sequences distributed throughout the genome. Their possible function is considered.},
  language  = {en}
}
@article{ScheerSchmidtZachmannHuegleetal.1984,
  author    = {Scheer, Ulrich and Schmidt-Zachmann, Marion S. and H{\"u}gle, Barbara and Franke, Werner W.},
  title     = {Identification and localization of a novel nucleolar protein of a high molecular weight by a monoclonal antibody},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39786},
  year      = {1984},
  abstract  = {A monoclonal murine antibody (No-I 14) is described which reacts specifically with a polypeptide of molecular weight (M,) 180000 present in low-speed nuclear pellets from oocytes and somatic cells of Xenopus laevis and X. borealis and in isolated amplified nucleoli. Two-dimensional gel electrophoresis has revealed the acidic nature of this polypeptide (isoelectric at pH of ca 4.2 in the presence of 9.5 M urea). A relatively large proportion of the protein is extracted at elevated ionic strength( i.e., at 0.4-0.5 M alkali salt) in a form sedimenting at approx. 7-8S , compatible with a monomeric state. It is also extracted by digestion with RNase but not with DNase. In immunofluorescence microscopy, antibody No-114 stains intensely nucleoli of oocytes and all somatic cells examined , including the residual nucleolar structure of Xenopus erythrocytes which are transcriptionally inactive. During mitosis the antigen does not remain associated with the nucleolar organizer regions (NOR) of chromosomes but is released and dispersed over the cytoplasm until telophase when it re-associates with the reforming interphase nucleoli. At higher resolution the immunofluorescent region is often resolved into a number of distinct subnucleolar components of varied size and shape. Immunoelectron microscopy using colloidal gold-coupled secondary antibodies reveals that the M, 180000 protein is confined to the dense fibrillar component of the nucleolus. This conclusion is also supported by its localization in the fibrillar part of segregated nucleoli of cells treated with actinomycin D. We conclude that nucleoli contain a prominent protein of M, 180000 which contributes to the general structure of the dense fibrillar component of the interphase nucleolus , independent of its specific transcriptional activity.},
  language  = {en}
}
@article{Schuessler1988,
  author    = {Sch{\"u}ssler, Ulrich},
  title     = {Mobilisation einzelner Elemente in Amphiboliten aus der Umgebung der KTB-Lokation, Zone Erbendorf-Vohenstrauss, n{\"o}rdliche Oberpfalz},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39248},
  year      = {1988},
  abstract  = {No abstract available},
  subject      = {Mineralogie},
  language  = {de}
}
@article{ThiryScheerGoessens1991,
  author    = {Thiry, Marc and Scheer, Ulrich and Goessens, Guy},
  title     = {Localization of nucleolar chromatin by immunocytochemistry and in situ hybridization at the electron microscopic level},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39289},
  year      = {1991},
  abstract  = {Nucleoli are the morphological expression of the activity of a defined set of chromosomal segments bearing rRNA genes. The topological distribution and composition of the intranucleolar chromatin as well as the definition of nucleolar structures in which enzymes of the rDNA transcription machinery reside have been investigated in mammalian cells by various immunogold labelling approaches at the ultrastructural level. The precise intranucleolar location of rRNA genes has been further specified by electron microscopic in situ hybridization with a non-autoradiographic procedure. Our results indicate that the fibrillar centers are the sole nucleolar structures where rDNA, core histones, RNA polymerase I and DNA to po isomerase I are located together. Taking into account the potential value and limitations of immunoelectron microscopic techniques, we propose that transcription of the rRNA genes takes place within the confines of the fibrillar centers, probably close to the boundary regions to the surrounding dense fibrillar component.},
  language  = {en}
}
@article{GesslerKoenigArdenetal.1994,
  author    = {Gessler, Manfred and K{\"o}nig, A. and Arden, K. and Grundy, P. and Orkin, S. H. and Sallan, S. and Peters, C. and Ruyle, S. and Mandell, J. and Li, F. and Cavenee, W. and Bruns, G. A.},
  title     = {Infrequent mutation of the WT1 gene in 77 Wilms' Tumors},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-34308},
  year      = {1994},
  abstract  = {Homozygous deletions in Wilms' tumor DNA have been a key step in the identification and isolation of the WTI gene. Several additional loci are also postulated to contribute to Wilms' tumor formation. To assess the frequency of WTI alterations we have analyzed the WTI locus in a panel of 77 Wilms' tumors. Eight tumors showed evidence for large deletions of several hundred or thousand kilobasepairs of DNA, some of which were also cytogenetically detected. Additional intragenic mutations were detected using more sensitive SSCP analyses to scan all 10 WTI exons. Most of these result in premature stop codons or missense mutations that inactivate the remaining WTI allele. The overall frequency of WTI alterations detected with these methods is less than 15\%. While some mutations may not be detectable with the methods employed, our results suggest that direct alterations of the WTI gene are present in only a small fraction of Wilms' tumors. Thus, mutations at other Wilms' tumor loci or disturbance of interactions between these genes likely play an important role in Wilms' tumor development.},
  language  = {en}
}
@article{Ellgring1992,
  author    = {Ellgring, Johann Heinrich},
  title     = {Psychosoziale Aspekte des Morbus Parkinson},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-34052},
  year      = {1992},
  abstract  = {No abstract available},
  language  = {de}
}
@article{Koenig1984,
  author    = {K{\"o}nig, Dorothea},
  title     = {Materialien zu den Fragmenten des Mihanovic-Homiliars},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38566},
  year      = {1984},
  abstract  = {No abstract available},
  language  = {ru}
}
@article{Koenig1986,
  author    = {K{\"o}nig, Dorothea},
  title     = {Materialien zu den Fragmenten des Mihanovic-Homiliars},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38599},
  year      = {1986},
  abstract  = {No abstract available},
  language  = {ru}
}
@article{Koenig1974,
  author    = {K{\"o}nig, Dorothea},
  title     = {Notizen zum Wortschatz des Vatikanski Hrvatski Molitvenik},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38740},
  year      = {1974},
  abstract  = {No abstract available},
  language  = {de}
}
@article{KoenigAitzetmueller1987,
  author    = {K{\"o}nig, Dorothea and Aitzetmueller, Rudolf},
  title     = {Die Slavistik an der Universit{\"a}t W{\"u}rzburg},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38778},
  year      = {1987},
  abstract  = {No abstract available},
  language  = {de}
}
@article{Hee2009,
  author    = {Hee, Katrin},
  title     = {Nicht Tabu},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39075},
  year      = {2009},
  abstract  = {Dieser Artikel beschreibt eine Unterrichtssequenz f{\"u}r den Deutschunterricht im Bereich Deutsch als Fremdsprache und richtet sich an Lernende der Niveaustufe A2. Er zeigt, wie Lernende spielerisch sowohl rezeptive Sprachkenntnisse als auch aktive Sprachbeherrschung verbessern und ihren Wortschatz erweitern k{\"o}nnen. Ein besonders wichtiges Kriterium sind dabei der Spielcharakter und die Auflockerung des Unterrichts, sowie die M{\"o}glichkeit, individuell auf die Bed{\"u}rfnisse der Studenten eingehen zu k{\"o}nnen.},
  subject      = {Wortschatz},
  language  = {de}
}
@article{Hee2009,
  author    = {Hee, Katrin},
  title     = {Ein internationales Kochbuch},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39067},
  year      = {2009},
  abstract  = {In diesem Artikel wird eine Unterrichtssequenz beschrieben, die sich {\"u}ber einen Zeitraum von zirka 2 Wochen hinzieht und sich an Deutschlernende auf A1-Niveau richtet. Unterrichtsprojekt und Inhalt des Artikels ist ein internationales Kochbuch, das die Studenten selbst entwerfen. Das Projekt eignet sich besonders zur Binnendifferenzierung von großen Gruppen. Jedes Kapitel wird von einer Gruppe bearbeitet, so dass die Studenten je nach F{\"a}higkeiten und Lerntempo individuell ihr Wissen anwenden und erweitern k{\"o}nnen. Der Artikel gibt einen {\"U}berblick {\"u}ber die einzelnen Kapitel des Kochbuches, die jeweiligen Lernziele und allgemeine didaktische Hinweise in Bezug auf das Projekt.},
  subject      = {Projektarbeit},
  language  = {de}
}
@article{Apostoiu2009,
  author    = {Apostoiu, Nicoleta},
  title     = {Theater im Franz{\"o}sischunterricht: "Die ausgeflippte Familie"},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39089},
  year      = {2009},
  abstract  = {Das Hauptziel des Projekts war, internationale Studenten auf A1-Niveau zu motivieren, damit sie ihre kommunikative Kompetenz in Franz{\"o}sisch verbessern konnten. Da sich kein geeignetes Material f{\"u}r dieses Projekt fand, entwarf ich ein Projekt, um den Stoff vom gesamten Semesterkurs zu wiederholen.},
  subject      = {Projektarbeit},
  language  = {de}
}
@article{Ramos2009,
  author    = {Ramos, Carmen},
  title     = {Schl{\"u}sselbegriff: Handlungs- und Aufgabenorientierung},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39054},
  year      = {2009},
  abstract  = {Kurze Darstellung des Begriffs "Handlungsorientierung".},
  subject      = {Handlungsorientierung},
  language  = {de}
}
@article{RamosWildenauerJozsa2009,
  author    = {Ramos, Carmen and Wildenauer-J{\´o}zsa, Doris},
  title     = {Learning by doing: Eine handlungsorientierte Fortbildungsveranstaltung {\"u}ber Handlungsorientierung},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39049},
  year      = {2009},
  abstract  = {Der Artikel stellt Hintergr{\"u}nde, Ablauf und Ergebnisse eines als universit{\"a}re Dozentenfortbildung konzipierten Workshops zum Thema Handlungsorientierung vor.},
  subject      = {Handlungsorientierung},
  language  = {de}
}
@article{Karagiannakis2009,
  author    = {Karagiannakis, Evangelia},
  title     = {Projektorientierte Landeskunde im DaF-Unterricht - Eine Kooperation zwischen DaF-Lernern und Lehramtsstudierenden},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39031},
  year      = {2009},
  abstract  = {DaF-Unterricht an Hochschulen hat zum Ziel, nicht-deutschen Studierenden m{\"o}glichst z{\"u}gig die deutsche Sprache zu vermitteln. Da sie sich bereits im Zielsprachenland aufhalten und hier (f{\"u}r begrenzte Zeit) leben, ist es wichtig, auch landeskundliche Kenntnisse zu erwerben. Beides geschieht im universit{\"a}ren Sprachunterricht aufgrund von {\"a}ußeren Rahmenbedingungen oft sehr "kopflastig". Projektorientierte Methoden k{\"o}nnen hier Abhilfe schaffen, da jeder einzelne Lernerde sehr viel intensiver selbst aktiv werden muss als im herk{\"o}mmlichen Sprachunterricht. Besonders gewinnbringend werden Projekte, wenn sie in Kooperation mit deutschen Muttersprachlern, am besten k{\"u}nftigen DeutschlehrerInnen stattfinden. Diese sind nicht nur authentische Gespr{\"a}chspartner, sondern haben zudem auch (in unterschiedlich ausgepr{\"a}gtem Maße) didaktische Kenntnisse, die in die Projektarbeit einfließen. Sie selbst k{\"o}nnen in solchen Kooperationen wichtige Erfahrungen f{\"u}r ihren Lehrberuf sammeln. Wie dies in der Praxis aussehen kann, soll in diesem Beitrag exemplarisch vorgestellt werden.},
  subject      = {Projektarbeit},
  language  = {de}
}
@article{Holstein2009,
  author    = {Holstein, Silke},
  title     = {Web-Spaziergang - eine virtuelle Reise},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39029},
  year      = {2009},
  abstract  = {Im Artikel wird ein binationales Internet-Projekt beschrieben. Daran nahmen ein Deutschkurs der Universit{\"a}t Alcal{\´a} de Henares in Spanien und zwei Spanischkurse der Universit{\"a}t W{\"u}rzburg teil. Diese tauschten sich {\"u}ber einen Web-Blog aus. Das Ziel war, die jeweilige Stadt vorzustellen und so der anderen Seite einen virtuellen Besuch im Land der Zielsprache zu erm{\"o}glichen. Der Artikel beschreibt den didaktischen Umgang mit dem Blog und gibt Hinweise f{\"u}r Lehrende, die einen Blog im Unterricht einsetzen m{\"o}chten.},
  subject      = {Handlungsorientierung},
  language  = {de}
}
@article{FrankeScheer1970,
  author    = {Franke, Werner W. and Scheer, Ulrich},
  title     = {The ultrastructure of the nuclear envelope of amphibian oocytes: a reinvestigation. I. The mature oocyte},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-32098},
  year      = {1970},
  abstract  = {1 n order to review the contradictory statements on the ultrast ructure of the nuclear envelope, a study was undertaken combining section and negat ive stai ning electron microscopy on manually isolated oocyte nuclei and nuclear envelopes from six amphibian species including Anura as well as Urodela. The a ppeara nce of the negatively stained iso lated nuclear envelopes is described in deta il and the dependence on the preparation co nditions used is emphas ized . Pore complex structures such as pore perimeter, central granule, an nul ar components, interna l fibrils, and annu lus-attached fibrils could be identified by both techniques, negat ive staining and sect ions. Comparative studies show that no marked diffe rences ex ist in the structural data of the nuclear envelope among the investigated amphibians and the significance of the structural components is discussed. A model of the nuclea r pore complex based on the findings of the present investigation is prese nted.},
  language  = {en}
}
@article{QuastSchmittSchaeferetal.1994,
  author    = {Quast, Helmut and Schmitt, Edeltraud and Sch{\"a}fer, Peter and Heller, Eberhard and Aldenkortt, Sven},
  title     = {Synthesis and Thermolysis of a Chiral, Non-Racemic Iminoaziridine},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38298},
  year      = {1994},
  abstract  = {The 2-halo imidoyl chlorides 7 are obtained from the amide 5 and the 2-halo amides 6 by the action of phosphorus pentachloride and thionyl chloride, respectively. Non-racemic (S)-6a is converted into 7a which is racemic, however. The reaction of Lawesson's reagent with 6a furnishes the diastereomeric 1,3.2-thiazaphospholidine derivatives 15. Treatment of (S)-6a (98\% eel with methyl triflate affords 2-chloro imidate 8 (95\% eel which reacts with methanamine in the presence of methanammonium chloride to yield the 2-chloro amidine (S)-9a (90\% eel. The 2-halo imidoyl halides 7a and b react with methanamine to produce the 2-halo amidines 9a and b. - Strong bases, e.g. potassium tert-butoxide or sodium hydride in the presence of catalytic amounts of tertbutyl alcohol, eliminate hydrogen chloride or bromide from the 2-halo amidines 9a and band (S)-9a to yield mixtures of Recently, we demonstrated that the formation of the chiral non-racemic aziridinone (R)-2 from the a-chloro amide (5)-1 by base-promoted dehydrochlorination[2) as well as the nucleophilic cleavage of the N-C(3) bond of (R)_2[3,4) occur with inversion of configuration, thus excluding the intervention of achiral (acyclic) intermediates. In the temperature range of lOO-170°C, however, slow racemization accompanies the thermolysis of (R)-2 and indicates the existence of an achiral or a racemic transient, e. g. (M)-3 + (P)-3. Indeed, high-level quantum-chemical calculations reveal that an activation energy of (170 ± 25) kJmol- 1 is required for the unimolecular ring opening of the parent aziridinone which affords a species of high diradical character[41. Subsequently, the unstable N-phenylaziridinone invoked in the decomposition of the (5)-2-bromopropananilide anion was shown to react with tert-butylamine or dimethylformamide with inversion of configuration at C(3)[51. Thus, the stereochemical evidence in the series of 3-alkylaziridinones excludes achiral (acyclic) aziridinone isomers as intermediates at low tempera tures [6J. Similar stereochemical studies are still missing in the related series of iminoaziridines. Therefore, we report on the synthesis and thermolysis of the diastereomeric chiral racemic (E)- and (Z)-(4)[71 and non-racemic iminoaziridines (E,R)- and (Z,R)-4. Racemic Iminoaziridines (E)- and (Z)-4 Though a photochemical route to the iminoaziridines (E)- and (Z)-4 has been devised more recently, i. e. the phothe 2-iminoaziridines (E)- and (Z)-4, and (E,R)- and (Z.R)-4 (83\% eel, respectively. The 1.3-elimination of hydrogen bromide from 9b is diastereoselective at -30 to -40°C [(E)-4:(Z)-4 = <10:>90). The diastereomers equilibrate at 36°C with (kEZ + k ZE) = (5.92 ± 0.08) . 10-5 S-I (K = kEZlkzE = 0.428 ± 0.013). - The thermolysis of (E)- and (Z)-4 in [D61benzene solution yields the imine 16 and methyl isocyanide (17). The decomposition follows the first-order rate law. The following Arrhenius and Eyring parameters are calculated from five rate constants obtained in the temperature range of 70-110°C: Ea = (115.2 ± 0.4) kJmol-t, IgA = (12.06 ± 0.28), AH* = (112.1 ± 0.4) kJmol- l , AS'" = (-23.9 ± 0.7) JK-I mol-I, AGj73K = 121 kJmol-1 . The enantiomeric excess of the surviving fraction of (E,R)- and (Z.R)-4 is unchanged after two half-lives at 80°C.},
  language  = {en}
}
@article{HellerHerdeis1993,
  author    = {Heller, Eberhard and Herdeis, Claus},
  title     = {Synthesis of 2S,5S- and 2R,5S-5-Hydroxypipecolic Acid via Amide-Methylenation of S-5-Hydroxy-2-piperidone with Dimethyltitanocene},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38288},
  year      = {1993},
  abstract  = {A route to 2S,5S-and 2R,5S-hydroxypipecolic acid is presented, starting with the enantiopure 5S-5-hydroxy-piperidone 7. The key step of this reaction sequence is the chemoselsctive methylenation of the amide carbonyl group of 8 with dimethyltitanocene 9 to 10. The transformation of the exocyclic enecarbamate double bond to the carboxylic acid group is best accomplished via hydroboration/oxidation to the alcohol 11a,b. Separation and oxidation of the dlastereomers 11a,b, to 148. and 14b, and hydrolysis furnishes the diastereomeric pipecolic acids 15a and 15b in enantiopure form.},
  subject      = {Chemie},
  language  = {en}
}
@article{Ruhe1989,
  author    = {Ruhe, Ernstpeter},
  title     = {Erz{\"a}hlen nach der Avantgarde. Rachid Boudjedras Weiterentwicklung des modernen Romans},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38266},
  year      = {1989},
  abstract  = {No abstract available},
  language  = {de}
}
@article{Ruhe1982,
  author    = {Ruhe, Ernstpeter},
  title     = {Du songe {\`a} la r{\´e}alit{\´e} ou de la r{\´e}alit{\´e} au songe? Die j{\"u}ngsten Romane Mongo Betis},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38191},
  year      = {1982},
  abstract  = {No abstract available},
  language  = {de}
}
@article{ReimerRaskaScheeretal.1988,
  author    = {Reimer, Georg and Raska, Ivan and Scheer, Ulrich and Tan, Eng M.},
  title     = {Immunolocalization of 7-2-ribonucleoprotein in the granular component of the nucleolus},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-33890},
  year      = {1988},
  abstract  = {Certain autoimmune sera contain antibodies against a nucleolar ribonucleoprotein particle associated with 7-2-RNA (R. Reddy et al. (1983) J. Bioi. Chem . 258, 1383; C. Hashimoto and J. A. Steitz (1983) J. Bioi. Chem. 258, 1379). In this study, we showed by immunofluorescence microscopy that antibodies reactive with 7-2-ribonucleoprotein immunolocalized in the granular regions of actinomycin D and 5,6-dichloro-I-j3-D-ribofuranosylbenzimidazole (DRB)-segregated nucleoli from Vero cells. By electron microscopic immunocytochemistry, antigen-antibody complexes were located in the granular component of transcriptionally active nucleoli from rat liver hepatocytes and HeLa cells. Anti-7- 2-RNP antibodies from two autoimmune sera immunoprecipitated a major protein of Mr 40,000 from e5S] methionine-Iabeled HeLa cell extract. The immunolocalization data suggest that 7-2-ribonucleoprotein may be involved in stages of ribosome biogenesis which take place in the granular component of the nucleolus, i.e., assembly, maturation, and/or transport of preribosomes},
  language  = {en}
}
@article{SommervilleScheer1982,
  author    = {Sommerville, John and Scheer, Ulrich},
  title     = {Transcription of complementary repeat sequences in amphibian oocytes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-33915},
  year      = {1982},
  abstract  = {Repeat sequences are transcribed in the germinal vesicles of amphibian oocytes. In the hnRNA population both complements of the repeats are found and can be readily detected because they form intermolecular duplex structures. The structure and formation of duplex regions have been studied in the hnRNA of Xenopus laevis, Triturus cristatus, Amphiuma means and Necturus maculosus, a series of amphibians of increasing genome size (C-value). In T. cristatus, the duplex structures are mostly 600- 1200 bp in length, whereas in X. laevis they are shorter and in N. maculosus they tend to be longer. Although the proportion of RNA sequence capable of rapidly forming duplex structures is different in different organisms, this property bears no relationship to C-value. However the sequence complexity of complementary repeats, as estimated from the rate of duplex formation, does show an increasing trend with C-value. The complementary repeats found in oocyte hnRNA are transcribed from families of DNA sequence that are each represented in the genome by thousands of copies. The extent of cross-species hybridization is low, indicating that the repeat sequences transcribed in different amphibian genera are not the same. In situ hybridization experiments indicate that the repeat sequences are spread throughout the genome. The evolution and possible function of complementary repeats are considered.},
  language  = {en}
}
@article{BenaventeRoseReimeretal.1987,
  author    = {Benavente, Ricardo and Rose, Kathleen M. and Reimer, Georg and H{\"u}gle-D{\"o}rr, Barbara and Scheer, Ulrich},
  title     = {Inhibition of nucleolar reformation after microinjection of antibodies to RNA polymerase I into mitotic cells},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-33247},
  year      = {1987},
  abstract  = {The formation of daughter nuclei and the reformation of nucleolar structures was studied after microinjection of antibodies to RNA polymerase I into dividing cultured cells (PtK2). The fate of several nucleolar proteins representing the three main structural subcomponents of the nucleolus was examined by immunofluorescence and electron microscopy. The results show that the RNA polymerase I antibodies do not interfere with normal mitotic progression or the early steps of nucleologenesis, i.e. , the aggregation of nucleolar material into prenucleolar bodies. However,they inhibit the telophasic coalescence of the prenucleolar bodies into the chromosomal nucleolar organizer regions, thus preventing the formation of new nucleoli. These prenucleolar bodies show a fibrillar organization that also compositionally resembles the dense fibrillar component of interphase nucleoli . We conclude that during normal nucleologenesis the dense fibrillar component forms from preformed entities around nucleolar organizer regions, and that this association seems to be dependent on the presence of an active form of RNA polymerase I.},
  language  = {en}
}
@article{FrankeBergerFalketal.1974,
  author    = {Franke, Werner W. and Berger, S. and Falk, Heinz and Spring, H. and Scheer, Ulrich and Trendelenburg, Michael F. and Schweiger, H. G. and Herth, W.},
  title     = {Morphology of the nucleo-cytoplasmic interactions during the development of Acetabularia cells. I. The vegetative phase},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-32363},
  year      = {1974},
  abstract  = {The ultrastructure of th e growin g and ma turing primary nucleus of Acetabularia medite rranea and Acetabularia major has been studied with the use of various fi xation procedures. Particular interest has been focused on the deta ils of the nuclear periphery and the perinuclear region. It is demonstrated that early in nuclear grow th a characteristic perinucl ear structura l complex is formed which is, among the eukaryotic cells, unique to Acetabularia and re lated genera. This perinuclear system consists essentially of a) the nuclear envelope with a very hi gh pore frequency and various pore complex assoc iat ion s w ith granular and/or threadlike structures some of which are continuous with the nucleolus; b) an approx imate ly 100 nm thick intermediate zone densely filled with a filam entOus material and occasional sma ll membraneous structures from which the typical cytOplasmic and nuclear organe lles and particles are excl ud ed ; c) an adjacent Iacunar labyrinthum which is interrupted by many plasmatic junction channels between the intermed iate zone and the free cytOplasm; d) numerous dense perinuclear bodies in the juxtanuclear cytOplasm which a re especia lly frequent at the junction channels and reveal a composition of aggregated fibrillar and granul ar structures; e) very dense exclusively fibrill ar agg regates which occur either in assoc iation with t he perinuclear region of the lacunar labyrinthum or, somewhat further out, in the cytOplasmic strands between the bra nches of the lacun ar labyrinthum in the form of slender, characteristic rods or "sausages".},
  language  = {en}
}
@article{Scheer1973,
  author    = {Scheer, Ulrich},
  title     = {Nuclear pore flow rate of ribosomal RNA and chain growth rate of its precursor during oogenesis of Xenopus laevis},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-32178},
  year      = {1973},
  abstract  = {The number of ribosomal RNA molecules which are transferred through an average nuclear pore complex per minute into the cytoplasm (nuclear pore flow rate, NPFR) during oocyte growth of Xenopus laevis is estimated. The NPFR calculations are based on determinations of the increase of cytoplasmic rRNA content during defined time intervals and of the total number of pore complexes in the respective oogenesis stages. In the mid-la mpbrush stage (500:"700 I'm oocyte diameter) the NPFR is maximal with 2.62 rRNA molecules/ pore/ minute. Then it decreases to zero at the end of oogenesis. The nucleocytoplasmic RNA f10w rates determined are compared with corresponding values of other cell types. The molecular weight of the rRNA precursor transcribed in the extrachromosomal nucleoli of Xenopus lampbrush stage oocytes is determined by acrylamide gel electrophoresis to be 2.5 x 10· daltons. From the temporal increase of cytoplasmic rRNA (3.8 I'g per oocyte in 38 days) and the known number of simultaneously growing precursor molecules in the nucleus the chain growth rate of the 40 S precursor RNA is estimated to be 34 nucleotides per second.},
  language  = {en}
}
@article{ScheerFranke1969,
  author    = {Scheer, Ulrich and Franke, Werner W.},
  title     = {Negative staining and adenosine triphosphatase activity of annulate lamellae of newt oocytes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-32087},
  year      = {1969},
  abstract  = {Semi -iso la ted annul a te lamellae were prepared from single newt oocy tes (Triturus alpestris) by a modified Call a n-T omlin technique. Such preparations were examined with the electron mi croscope, and the negative sta ining a ppearance of th e a nnulate lamellae is described . The annul a te lamellae can be de tected either adhering to the nuclear envelope or being detached from it. Sometimes they a re obse rved to be connected with slender tubular-like structures interpreted as pa rts of the endoplasmic reti culum. The results obta ined from negativ e sta ining a re combined with those from sections. Especially, the structural data on th e a nnula te lamellae and the nuclear envelope of the very same cell were compa red . Evidence is presented th a t in the oocytes studied the two kinds of porous cisternae, n amely a nnul a te lamellae and nuclear envelope, a re markedly distinguished in that the annul a te lamellae ex hibit a much higher pore frequency (generally about twice tha t found for the corresponding nuclear envelope) and have al so a rela tive pore area occupying as much as 32 \% to 55 \% of th e cistern al surface (compa red with 13 \% to 22 \% in the nuclear envelopes). T he pore di ame ter a nd all other ultras tructural details of the pore complexes, however, a re equi valent in both kinds of porous cisternae. Like the annuli of the nuclear pore complexes of various a nimal and pl ant cells, the a nnuli of the a nnula te lamellae pores reveal al so an eightfold symmetry of their subunits in negatively stained as well as in ectioned ma teria l. Furthermore, th e a nnul a te lamellae a re shown to be a site of activity of the Mg-Na-Kstimul a ted ATPase.},
  language  = {en}
}
@article{RoseSzopaHanetal.1988,
  author    = {Rose, Kathleen M. and Szopa, Jan and Han, Fu-Sheng and Cheng, Yung-Chi and Richter, Arndt and Scheer, Ulrich},
  title     = {Association of DNA topoisomerase I and RNA polymerase I: A possible role for topoisomerase I in ribosomal gene transcription},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-33901},
  year      = {1988},
  abstract  = {RNA polymerase I preparations purified from a rat hepatoma contained DNA topoisomerase activity. The DNA topoisomerase associated with the polymerase had an Mr of 110000, required Mg2+ but not ATP, and was recognized by anti-topoisomerase I antibodies. When added to RNA polymerase I preparations containing topoisomerase activity, anti-topoisomerase I antibodies were able to inhibit the DNA relaxing activity of the preparation as well as RNA synthesis in vitro. RNA polymerase II prepared by analogous procedures did not contain topoisomerase activity and was not recognized by the antibodies. The topoisomerase I: polymerase I complex was reversibly dissociated by column chromatography on Sephacryl S200 in the presence of 0.25 M (NH4hS04. Topoisomerase I was immunolocalized in the transcriptionally active ribosomal gene complex containing RNA polymerase I in situ. These data indicate that topoisomerase I and RNA polymerase I are tightly complexed both in vivo and in vitro, and suggest a role for DNA topoisomerase I in the transcription of ribosomal genes.},
  language  = {en}
}
@article{RoeschAtzmuellerSchaacketal.1994,
  author    = {R{\"o}sch, M. and Atzm{\"u}ller, R. and Schaack, G. and Becker, Charles R.},
  title     = {Resonant Raman scattering in a zero-gap semiconductor: Interference effects and deformation potentials at the E\(_1\) and E\(_1\) + \(\Delta_1\) gaps of HgTe},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38062},
  year      = {1994},
  abstract  = {No abstract available},
  language  = {en}
}
@article{KrausBeckerScholletal.1993,
  author    = {Kraus, M. M. and Becker, Charles R. and Scholl, S. and Wu, Y. S. and Yuan, S. and Landwehr, G.},
  title     = {Infrared photoluminescence on molecular beam epitaxially grown Hg\(_{1-x}\)Cd\(_x\)Te layers},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38053},
  year      = {1993},
  abstract  = {No abstract available},
  language  = {en}
}
@article{HeBeckerBicknellTassiusetal.1993,
  author    = {He, L. and Becker, Charles R. and Bicknell-Tassius, R. N. and Scholl, S. and Landwehr, G.},
  title     = {Molecular beam epitaxial growth of (100) Hg\(_{0.8}\)Cd\(_{0.2}\)Te on Cd\(_{0.96}\)Zn\(_{0.04}\)Te},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38044},
  year      = {1993},
  abstract  = {No abstract available},
  language  = {en}
}