Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen OPUS4-3093 Konferenzveröffentlichung Franke, Werner W.; Scheer, Ulrich Biochemical and structural aspects of nucleocytoplasmic transfer of ribonucleoproteins at the nuclear envelope level: facts and theses No abstract available 1975 urn:nbn:de:bvb:20-opus-33766 Theodor-Boveri-Institut für Biowissenschaften OPUS4-3368 Konferenzveröffentlichung Scheer, Ulrich Electron microscopic analysis of chromatin and gene expression No abstract available 1982 urn:nbn:de:bvb:20-opus-39456 Theodor-Boveri-Institut für Biowissenschaften OPUS4-3073 Konferenzveröffentlichung Scheer, Ulrich; Rose, Kathleen M. Localization of RNA polymerase I in interphase cells and mitotic chromosomes by light and electron microscopic immunocytochemistry Rabbit antibodies to RNA polymerase I from a rat hepatoma have been used to localize the enzyme in a variety of cells at the light and electron microscopic level. In interphase cells the immunofluorescence pattern indicated that polymerase I is contained exclusively within the nucleolus. That this fluorescence, which appeared punctated rather than uniform, represented transcriptional complexes of RNA polymerase I and rRNA genes was suggested by the observation that it was enhanced in regenerating liver and in a hepatoma and was markedly diminished in cells treated with actinomycin D. Electron microscopic immunolocalization using gold-coupled second antibodies showed that transcribed rRNA genes are located in, and probably confined to, the fibrillar centers of the nucleolus. In contrast, the surrounding dense fibrillar component, previously thought to be the site of nascent prerRNA, did not contain detectable amounts of polymerase I. During mitosis, polymerase I molecules were detected by immunofluorescence microscopy at the chromosomal nucleolus organizer region, indicating that a considerable quantity of the enzyme remains bound to the rRNA genes. From this we conclude that rRNA genes loaded with polymerase I molecules are transmitted from one cell generation to the next one and that factors other than the polymerase itself are involved in the modulation of transcription of DNA containing rRNA genes during the cell cycle. 1984 urn:nbn:de:bvb:20-opus-33223 Theodor-Boveri-Institut für Biowissenschaften OPUS4-2682 Konferenzveröffentlichung Trendelenburg, Michael F.; Spring, Herbert; Scheer, Ulrich; Franke, Werner W. Morphology of nucleolar cistrons in a plant cell, Acetabularia mediterranea The structural organization of transcriptionally active DNA that contains cistrons for precursor molecules of ribosomal RNA is described in positively stained spread preparations from nuclei and nucleoli isolated from the green alga, Acetabularia mediterranea Lmx. These nuclei contain large aggregates of nucleolar subunits in which fibril-covered regions, the putative active cistrons for precursors of ribosomal RNA, alternate with fibril-free intercepts, the "spacers". The length distribution of the different intercepts of this DNA is given, and the pattern is compared with those shown in animal cell systems. The data are discussed in relation to problems of transcription and of amplification of ribosomal RNA genes. 1974 urn:nbn:de:bvb:20-opus-32213 Theodor-Boveri-Institut für Biowissenschaften OPUS4-3610 Konferenzveröffentlichung Franke, Werner W.; Scheer, Ulrich; Trendelenburg, Michael F.; Zentgraf, H.; Spring, H. Morphology of transcriptionally active chromatin Some decades ago it was noted by cytologists that within the interphase nucleus large portions of the transcriptionally ("genetically," in their terms) inactive chromosomal material are contained in aggregates of condensed chromatin, the "chromocenters," whereas transcriptionally active regions of chromosomes appear in a more dispersed form and are less intensely stained with DNA-directed staining procedures (Heitz 1929, 1932, 1956; Bauer 1933). The hypothesis that condensed chromatin is usually characterized by very low or no transcriptional activity, and that transcription occurs in loosely packed forms of chromatin (including, in most cells, the nucleolar chromatin) has received support from studies of ultrathin sections in the electron microscope and from the numerous attempts to separate transcriptionally active from inactive chromatin biochemically (for references, see Anderson et al. 1975; Berkowitz and Doty 1975; Krieg and Wells 1976; Rickwood and Birnie 1976; Gottesfeld 1977). Electron microscopic autoradiography has revealed that sites of RNA synthesis are enriched in dispersed chromatin regions located at the margins of condensed chromatin (Fakan and Bernhard 1971, 1973; Bouteille et al. 1974; Bachellerie et al. 1975) and are characterized by the occurrence of distinct granular and fibrillar ribonucleoprotein (RNP) structures, such as perichromatin granules and fibrils. The discovery that, in most eukaryotic nuclei, major parts of the chromatin are organized in the form of nucleosomes (Olins and Olins 1974; Kornberg 1974; Baldwin et al. 1975) has raised the question whether the same nucleosomal packing of DNA is also present in transcriptionally active chromatin strands. Recent detailed examination of the morphology of active and inactive chromatin involving a diversity of electron microscopic methods, particularly the spreading technique by Miller and coworkers (Miller and Beatty 1969; Miller and Bakken 1972), has indicated that the DNA of some actively transcribed regions is not packed into nucleosomal particles but is present in a rather extended form within a relatively thin (4-7 nm) chromatin fiber. 1978 urn:nbn:de:bvb:20-opus-41097 Theodor-Boveri-Institut für Biowissenschaften OPUS4-3373 Konferenzveröffentlichung Dabauvalle, M.-C.; Wilken, N.; Ewald, A.; Kuhbier, A.; Senécal, J.-L.; Scheer, Ulrich Nuclear pore complex structure analyzed by immunogold EM with human autoantibodies No abstract available 1994 urn:nbn:de:bvb:20-opus-39439 Theodor-Boveri-Institut für Biowissenschaften OPUS4-3091 Konferenzveröffentlichung Franke, Werner W.; Scheer, Ulrich Pathways of nucleocytoplasmic translocation of ribonucleoproteins No abstract available 1974 urn:nbn:de:bvb:20-opus-33832 Theodor-Boveri-Institut für Biowissenschaften OPUS4-3094 Konferenzveröffentlichung Scheer, Ulrich; Trendelenburg, M. F.; Franke, Werner W. Regulation of transcription of ribosomal RNA genes during amphibian oogenesis No abstract available 1976 urn:nbn:de:bvb:20-opus-33700 Theodor-Boveri-Institut für Biowissenschaften OPUS4-3367 Konferenzveröffentlichung Franke, Werner W.; Zentgraf, Hanswalter; Scheer, Ulrich Supranucleosomal and non-nucleosomal chromatin configurations A significant contribution to the understanding of chromatin organization was the d iscovery of the nucleosome as a globular repeating unit of the package of DNA (Hewish and Burgoyne, 1973; Woodcock, 1973; Kornberg, 1974; Olins and Olins, 1974; for review see Oudet et al., 1978 a) . In accord with the original definition and in ag reement with most workers in this field of research we identify a nucleosome as a spheric alor slightly oblate gr anular particle 10-13 nm in diameter, containing about 200 base pairs of DNA and two of each of the four his tones H2a, H2b, H3 and H4. It is this structure in which the bulk of the nuclear chroma tin is organized in most eukaryotic cells, with the exception of the dinofl age llates (Rae and Steele, 1977; dinofl agellate DNA, however, c an be packed into nucleosoma l structures in vitro by addition of the appropriate amounts of histones;the same reference). Although it seems clear from the work reported that condensed and transcriptiona lly inactive chroma tin is contained in nucleosomes as the principle for first order p acking of DNA there are two important questions onto which we are focusing in the present study: ( i ) What is the higher order of p a cking present in - and perhaps typical-of - the condensed sta te of chromatin, and (ii) what is the specific form of arrangement of transcriptionally a ctive chromatin? 1978 urn:nbn:de:bvb:20-opus-39447 Theodor-Boveri-Institut für Biowissenschaften OPUS4-3612 Konferenzveröffentlichung Scheer, Ulrich; Franke, Werner W. Transcriptional complexes of nucleolar genes No abstract available 1976 urn:nbn:de:bvb:20-opus-41072 Theodor-Boveri-Institut für Biowissenschaften