@inproceedings{FialaFederleMaschwitzetal.1994, author = {Fiala, Brigitte and Federle, W. and Maschwitz, U. and Azarae, Idris}, title = {The first myrmecophytic 2-partner-system in the genus Macaranga: The association between Macaranga puncticulata and a Componotus (Colobopsis) in Malaysia}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55144}, year = {1994}, abstract = {No abstract available}, subject = {Biologie}, language = {en} } @inproceedings{Mahsberg1990, author = {Mahsberg, Dieter}, title = {Brood care and family cohesion in the tropical scorpion Pandinus imperator (Koch) (Scorpiones: Scorpionidae)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-45776}, year = {1990}, abstract = {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.}, subject = {Skorpion}, language = {en} } @inproceedings{ScheerFranke1976, author = {Scheer, Ulrich and Franke, Werner W.}, title = {Transcriptional complexes of nucleolar genes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-41072}, year = {1976}, abstract = {No abstract available}, language = {en} } @inproceedings{FrankeScheerTrendelenburgetal.1978, author = {Franke, Werner W. and Scheer, Ulrich and Trendelenburg, Michael F. and Zentgraf, H. and Spring, H.}, title = {Morphology of transcriptionally active chromatin}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-41097}, year = {1978}, abstract = {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.}, language = {en} } @inproceedings{DabauvalleWilkenEwaldetal.1994, author = {Dabauvalle, M.-C. and Wilken, N. and Ewald, A. and Kuhbier, A. and Sen{\´e}cal, J.-L. and Scheer, Ulrich}, title = {Nuclear pore complex structure analyzed by immunogold EM with human autoantibodies}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39439}, year = {1994}, abstract = {No abstract available}, language = {en} } @inproceedings{Scheer1982, author = {Scheer, Ulrich}, title = {Electron microscopic analysis of chromatin and gene expression}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39456}, year = {1982}, abstract = {No abstract available}, language = {en} } @inproceedings{FrankeZentgrafScheer1978, author = {Franke, Werner W. and Zentgraf, Hanswalter and Scheer, Ulrich}, title = {Supranucleosomal and non-nucleosomal chromatin configurations}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39447}, year = {1978}, abstract = {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?}, language = {en} } @inproceedings{ScheerTrendelenburgFranke1976, author = {Scheer, Ulrich and Trendelenburg, M. F. and Franke, Werner W.}, title = {Regulation of transcription of ribosomal RNA genes during amphibian oogenesis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-33700}, year = {1976}, abstract = {No abstract available}, language = {en} } @inproceedings{FrankeScheer1975, author = {Franke, Werner W. and Scheer, Ulrich}, title = {Biochemical and structural aspects of nucleocytoplasmic transfer of ribonucleoproteins at the nuclear envelope level: facts and theses}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-33766}, year = {1975}, abstract = {No abstract available}, language = {en} } @inproceedings{TrendelenburgFrankeSpringetal.1975, author = {Trendelenburg, M. F. and Franke, Werner W. and Spring, H. and Scheer, Ulrich}, title = {Ultrastructure of transcription in the nucleoli of the green algae Acetabularia major and A. mediterranea}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-33779}, year = {1975}, abstract = {No abstract available}, language = {en} }