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 OPUS4-7097 Konferenzveröffentlichung Riehl, Rüdiger; Schartl, Manfred; Anders, Fritz An ultrastructural study of melanoma in Xiphophorus Melanotic melanoma (MM) of Xiphophorus (Teleostei: Poeciliidae) was studied by conventional preparations and freeze-etch preparations for electron microscopy. MM of Xiphophorus exhibits tightly packed pigment cells with prominent dendritic processes and interdigitations of their plasma membranes. The most impressive feature of MM cells is the occurrence of Iarge lobulated nuclei with numerous nuclear pores and some nuclear pockets. Abundant spheroidal or ellipsoidal melanosomes (diameter 200-650 nm) and vesicular structures are distributed throughout the cellular dendrites, whereas the perinucJear cytoplasm is free of melanosomes. A further characteristic feature of melanoma cells in fish is the occurrence of melanosome complexes (i.e., "compound melanosomes"). These melanosome complexes consist of a few to numerous melanosomes, which are enveloped by a separate rnembrane. Pinocytotic vesicles couJd be demonstrated with distinct differences in frequency and distribution patterns, indicating differences in the metabolic activities of the cells in the same melanoma. Intercellular junctions are lacking in the MM cells. The conventional TEM technique showed clear advantages in the demonstration of intemal architecture of organelles, whereas FE bad considerable potential in respect to the visualization of membrane surface specializations. 1985 urn:nbn:de:bvb:20-opus-70978 Theodor-Boveri-Institut für Biowissenschaften OPUS4-4683 Konferenzveröffentlichung Fiala, Brigitte; Rabenstein, R.; Maschwitz, Ulrich Ant-attracting plant-structures: Food bodies of SE Asian Vitaceae No abstract available 1994 urn:nbn:de:bvb:20-opus-55177 Theodor-Boveri-Institut für Biowissenschaften 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 OPUS4-3978 Konferenzveröffentlichung Mahsberg, Dieter Brood care and family cohesion in the tropical scorpion Pandinus imperator (Koch) (Scorpiones: Scorpionidae) Pandinus imperator is a forest dweller of tropical West Africa. In the field, lobserved aggregations of up to 15 individuals. In the laboratory, mixed age groups of related and also unrelated animals lived jointly in terraria rarely showing within-group aggression or cannibalism. Brood-caring behavior of the mother influenced growth rate and survival probability of the young. With birth, mothers became very aggressive. To study family cohesion in Pandinus, experiments with family groups were conducted. Siblings aggregated around their mother. In choice experiments with two family groups, mothers were placed in enclosures that only the young were able to enter or to leave. Second instars significantly preferred the enclosure containing their own mother. Aggression among unrelated young of the same age was not observed. Feeding experiments studied the possible advantages of long-Iasting group living with regard to enhanced success in prey capture and its effect on growth of the young. Even groups of second instars were unable to subdue large prey on their own. Sibling groups with their mother removed suffered high mortality due to starvation and cannibalism compared to groups with mothers present. Here, young grew significantly faster: they shared the prey that only the mother was able to kill and dismember. Pandinus imperator has to be considered an intermediate subsocial scorpion. 1990 urn:nbn:de:bvb:20-opus-45776 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 OPUS4-7273 Konferenzveröffentlichung Anders, F.; Scholl, E.; Schartl, Manfred Environmental and hereditary factors in the causation of neoplasia, based on studies of the Xiphophorus fish melanoma system Neoplasia in Xiphophorus can be classified into: a) a Jarge group triggered by carcinogens; b) a large group triggered by promoters; and c) a small group that develops "spontaneously" according to Mendelian Jaw. The process leading to susceptibility for neoplasia is represented by the disintegration of gene systems that normally protect the fish from neoplasia. Interpopulational arid interracial hybridization is the most effective process that Ieads to disintegration of the protective gene systems. Environmental factors may complete disintegration in somatic cells and thus may trigger neoplasia. The applications of the findings on Xiphophorus to humans are discussed. 1981 urn:nbn:de:bvb:20-opus-86402 Theodor-Boveri-Institut für Biowissenschaften OPUS4-7274 Konferenzveröffentlichung Anders, F.; Schartl, Manfred; Scholl, E. Evaluation of environmental and hereditary factors in carcinogenesis, based on studies in Xiphophorus Neoplasia in Xiphophorus can be classified into a) a large group that is triggered by carcinogens; b) a large group triggered by promoters; c) a small group that develops "spontaneously" following interpopulational and interracial hybridizations; and d) a small group that develops "spontaneously" following germ line mutation. The process leading to susceptibility for neoplasia is represented by the disintegration of gene systems that normally protect the fish from neoplasia. Hybridization is the most effective process that leads to disintegration of the protection gene systems. Environmental factors may complete disintegration and thus may trigger neoplasia. It is discussed whether the findings on Xiphophorus may also apply to humans. 1981 urn:nbn:de:bvb:20-opus-72741 Theodor-Boveri-Institut für Biowissenschaften OPUS4-2564 Konferenzveröffentlichung Dandekar, Thomas; Argos, P. Genetic algorithms as a new tool to study protein stability No abstract available 1993 urn:nbn:de:bvb:20-opus-29990 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 OPUS4-6974 Konferenzveröffentlichung Schreibman, Martin P.; Schartl, Manfred; Kallman, Klaus D.; Magliulo-Cepriano, Lucia Molecular approaches to study the genetic regulation of the fish reproductive system No abstract available. 1994 urn:nbn:de:bvb:20-opus-86679 Theodor-Boveri-Institut für Biowissenschaften OPUS4-7268 Konferenzveröffentlichung Schartl, Manfred; Mäueler, Winfried; Raulf, Friedrich; Robertson, Scott M. Molecular aspects of melanoma formation in Xiphophorus No abstract available. 1988 urn:nbn:de:bvb:20-opus-72689 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 OPUS4-3090 Konferenzveröffentlichung Zentgraf, Hanswalter; Scheer, Ulrich; Franke, Werner W. On the existence of arrested transcriptional machinery in late stages of avian erythropoiesis No abstract available 1976 urn:nbn:de:bvb:20-opus-33696 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 OPUS4-6972 Konferenzveröffentlichung Schartl, A.; Schartl, Manfred; Anders, F. Phenotypic conversion of malignant melanoma to benign melanoma and vice versa in Xiphophorus No abstract available. 1981 urn:nbn:de:bvb:20-opus-86662 Theodor-Boveri-Institut für Biowissenschaften OPUS4-6937 Konferenzveröffentlichung Peter, R. U.; Schartl, Manfred; Anders, F.; Duncker, H.-R. Pigment pattern formation during embryogenesis in Xiphophorus No abstract available. 1985 urn:nbn:de:bvb:20-opus-69370 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 OPUS4-4658 Konferenzveröffentlichung Fiala, Brigitte; Maschwitz, Ulrich; Tho, Yow Pong The association between Macaranga trees and ants in South-east Asia No abstract available 1991 urn:nbn:de:bvb:20-opus-54752 Theodor-Boveri-Institut für Biowissenschaften OPUS4-5954 Konferenzveröffentlichung Gotz, R.; Schartl, Manfred The conservation of neurotrophic factors during vertebrate evolution No abstract available 1994 urn:nbn:de:bvb:20-opus-61964 Theodor-Boveri-Institut für Biowissenschaften OPUS4-4674 Konferenzveröffentlichung Fiala, Brigitte; Federle, W.; Maschwitz, U.; Azarae, Idris The first myrmecophytic 2-partner-system in the genus Macaranga: The association between Macaranga puncticulata and a Componotus (Colobopsis) in Malaysia No abstract available 1994 urn:nbn:de:bvb:20-opus-55144 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 OPUS4-3092 Konferenzveröffentlichung Trendelenburg, M. F.; Franke, Werner W.; Spring, H.; Scheer, Ulrich Ultrastructure of transcription in the nucleoli of the green algae Acetabularia major and A. mediterranea No abstract available 1975 urn:nbn:de:bvb:20-opus-33779 Theodor-Boveri-Institut für Biowissenschaften OPUS4-7272 Konferenzveröffentlichung Anders, Fritz; Schartl, Manfred; Barnekow, Angelika Xiphophorus as an in vivo model for studies on oncogenes The capacity of Xiphophorus to develop neoplasia can be formally assigned to a "tumor gene" (Tu), which appears to be a normal part of the genome of all individuals. The wild fish have evolved population-specific and cell type-specific systems of regulatory genes (R) for Tu that protect the fish from neoplasia. Hybridization of members of different wild populations in the laborstory followed by treatment of the hybrids with carcinogens led to disintegration of the R systems permitting excessive expression of Tu and thus resulting in neoplasia. Certain hybrids developed neoplasia even spontaneously. Observations on the genuine phenotypic effect of the derepressed Tu in the early embryo indicated an essential normal function of this oncogene in cell differentiation, proliferation and cell-cell communication. Tu appeared to be indispensable in the genome but may also be present in accessory copics. Recently, c-src, the cellular homolog of the Rous sarcoma virus oncogene v-src, was detected in Xiphophorus. The protein product of c-src, pp60c-src, was identified and then examined by its associated kinase activity. This pp60c-src was found in all individuals tested, but, depending on the genotype, its kinase activity was different. The genetic characters of c-src, such as linkage relations, dosage relations, expression, etc., correspond to those of Tu. From a systematic study which showed that pp60c-src was present in all metazoa tested ranging from mammals down to sponges, we concluded that c-src has evolved with the multicellular organization of animals. Neoplasia of animals and humans is a characteristic closely related to this evolution. Our data showed that small aquariurn fish, besides being used successfully because they are time-, space-, and money-saving systems for carcinogenicity testing, are also highly suitable for basic studies on neoplasia at the populational, morphological, developmental, cell biological, and molecular levels. 1984 urn:nbn:de:bvb:20-opus-86398 Theodor-Boveri-Institut für Biowissenschaften