TY - JOUR A1 - Becker, Charles R. T1 - Evidence for a quasi-phonon gap in CsCl N2 - The observed impurity induced far-infrared absorption in CsCl : Rb\(^+\) and CsCl : K\(^+\) is compared with a calculated density of acoustic phonon states in CsCl. The absorption due to CsCl : Rb\(^+\) displays a minimum between the acoustic and optic phonon bands. A narrow line is observed in CsCl: K\(^+\) at 85.8 cm\(^{-1}\) which falls in this quasi-phonon gap. Y1 - 1971 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30767 ER - TY - JOUR A1 - Reimer, Georg A1 - Scheer, Ulrich A1 - Peters, Jan-Michael A1 - Tan, Eng M. T1 - Immunolocalization and partial characterization of a nucleolar autoantigen (PM-Scl) associated with polymyositis / scleroderma overlap syndromes. N2 - Precipitating anti-PM-Sel antibodies are present in sera from patients with polymyositis. scleroderma. and polymyositis/scleroderma overlap syndromes. By indirect immunofluorescence microscopy. anti-PM-Scl antibodies stained the nucleolus in cells of different tissues and species. suggesting that the antigen is highly conserved. By electron microscopy, anti-PM-Scl antibodies reacted primarily with the granular component of the nuc1eolus. Drugs that inhibit rRNA synthesis had a marked effect on the expression of PM-Scl antigen. In actinomycin D-treated cells, immunofluorescence staining by anti-PM-Scl was signüicantly reduced with residual staining restricted to the granular regions of nuc1eoli. Treatment with 5,6-dichloro-beta-D- ribofuranosylbenzimidazole (DRB) also selectively reduced nuc1eolar staining. On a molecular level, anti-PM-Sel antibodies precipitated 11 polypeptides with molecular weights (Mr) ranging from 110,000 to 20,000. The Mr 80,000 and 20.000 polypeptides were phosphorylated. Evidence suggests that the PM-Scl antigen complex may be related to a prerlbosomal particle. Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33191 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Sommerville, John A1 - Bustin, M. T1 - Injected histone antibodies interfere with transcription of lampbrush chromosome loops in oocytes of Pleurodeles N2 - Antibodies to calf thymus histone H2B were purified by chromatography on DEAE-cellulose and injected into oocyte nuclei of Pleurodeles waltlii. As shown by indirect immunofluorescence these antibodies cross-reacted strongly with corresponding histones associated with lampbrush chromosomes. Shortly after injection the lateral loops of the chromosomes retracted into the chromomeres and by 3 h postinjection the 'lampbrush' appearance was completely lost and the chromosomes appeared in light-microscopic preparations as rod-like structures consisting of 10ngitudina11y coalesced chromomeres. In control oocytes injected with non-immune immunoglobulins or antibodies against a ubiquitous transcript-associated protein no morphological alterations of the lampbrush chromosomes could be observed. Electron microscopic spreads of chromosomes prepared at various times after injection of anti-H2B revealed a progressive loss of transcriptional complexes from the loop axes. Finally, higher-order chromatin configurations, like supranuc1eosomal globules (' superbeads ') or cable-like chromatin strands 50- 60 nm thick predominated, indicating complete transcriptional inactivation of a11 chromosomal regions. The results indicate that H2B antibodies react specifically with his tones associated with the transcribed DNA of lateral loops in their native state. The resulting antigenantibody complexes seem to inhibit progression of the R A polymerases along the template, thus causing the premature release of transcripts, a process analogous to the stripping effect of actinomycin D. The demonstration of histones associated with heavily transcribed regions, which are not compacted into nucleosomes but largely extended, supports the current concept that unfolding of nucleosomes to a110w transcription of the DNA does not involve dissociation of histones. In contrast, amplified ribosomal RNA genes are unaffected by injected HzB antibodies. This does not necessarily indicate absence of his tones from nucleolar chromatin, since we do not know whether it is accessible in vivo to antibodies or whether the histone antigenie determinants are masked by the presence of other proteins. The technique of injecting specific antibodies should be widely applicable when analysing the in vivo distribution of chromosomal components at the electron-microscopic level and when studying complex metabolie processes, like the cleavage and modification of RNA, by selective inhibition of defined enzymic steps. Y1 - 1979 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33166 ER - TY - JOUR A1 - Reimer, Georg A1 - Rose, Kathleen M. A1 - Scheer, Ulrich A1 - Tan, Eng M. T1 - Autoantibody to RNA polymerase I in scleroderma sera N2 - Autoantibodies to components of the nucleolus are a unique serological feature of patients with scleroderma. There are autoantibodies of several specificities; one type produces a speckled pattern of nucleolar staining in immunofluorescence. In actinomycin D and 5,6-dichloro-{j-D-ribofuranosylbenzimidazoletreated Vero cells, staining was restricted to the fibrillar and not the granular regions. By double immunofluorescence, specific rabbit anti-RNA polymerase I antibodies stained the same fibrillar structures in drug-segregated nucleoli as scleroderma sera. Scleroderma sera immunoprecipitated 13 polypeptides from (35S)methionine-labeled HeLa cell extract with molecular weights ranging from 210,000 to 14,000. Similar polypeptides were precipitated by rabbit anti-RNA polymerase I antibodies, and their common identities were confirmed in immunoabsorption experiments. Microinjection of purified IgG from a patient with speckled nucleolar staining effectively inhibited ribosomal RNA transcription. Autoantibodies to RNA polymerase I were restricted to certain patients with scleroderma and were not found in other autoimmune diseases. Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34294 ER - TY - JOUR A1 - Reinhard, Matthias A1 - Halbrügge, Maria A1 - Scheer, Ulrich A1 - Wiegand, Christiane A1 - Jockusch, Brigitte M. A1 - Walter, Ulrich T1 - The 46/50 kDa phosphoprotein VASP purified from human platelets is a novel protein associated with actin filaments and focal contacts N2 - Vasoactive agents which elevate either cGMP or cAMP inhibit platelet activation by pathways sharing at least one component, the 46/50 kDa vasodilator-stimulated phosphoprotein (V ASP). V ASP is stoichiometrically phosphorylated by both cGMP-dependent and cAMPdependent protein kinases in intact human platelets, and its phosphorylation correlates very well with platelet inhibition caused by cGMP- and cAMP-elevating agents. Here we report that in human platelets spread on glass, V ASP is associated predominantly with the distal parts of radial micro filament bundles and with microfilaments outlining the periphery, whereas less V ASP is associated with a central microfilamentous ring. V ASP is also detectable in a variety of different cell types including fibroblasts and epithelial cells. In fibroblasts, V ASP is concentrated at focal contact areas, along microfilament bundles (stress fibres) in a punctate pattern, in the periphery of protruding lamellae, and is phosphorylated by cGMP- and cAMP-dependent protein kinases in response to appropriate stimuli. Evidence for the direct binding of V ASP to F -actin is also presented. The data demonstrate that V ASP is a novel phosphoprotein associated with actin filaments and focal contact areas, i.e. transmembrane junctions between microfilaments and the extracellular matrix. KW - cAMP / cGMP / cytoskeleton / phosphorylation / protein kinase Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34246 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Dabauvalle, Marie-Christine A1 - Merkert, Hilde A1 - Benavente, Ricardo T1 - The nuclear envelope and the organization of the pore complexes N2 - No abstract available Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34275 ER - TY - JOUR A1 - Schubert, D.W. A1 - Kraus, M.M A1 - Kenklies, R. A1 - Becker, Charles R. A1 - Bicknell-Tassius, R.N. T1 - Composition and wavelength dependence of the refractive index in Cd\(_{1-x}\)Mn\(_x\)Te epitaxial layers N2 - We have investigated Cd\(_{1-x}\)Mn\(_x\)Te thin films with Mn concentrations of x=0.12, 0.18, 0.30, 0.52, and 0.70. These single crystal layers were grown by molecular beam epitaxy on [001] CdTe substrates. The real part of the refractive index, n, was determined below the band-gap Eo in the range of 0.5-2.5 eV at T=300 K. The parallel reOectivity was measured near the Brewster angle at the YAG laser wavelength of 1.064 J.Lm (hv= 1.165 eV). Combining these results with the optical pathlength results (nd) of reOection measurements in a Fourier spectrometer we have determined n(x,v) over a wide spectral range by utilizing a three parameter fit. The accuracy of these results for n should improve waveguide designs based on this material. Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-37716 ER - TY - JOUR A1 - Bell, Peter A1 - Dabauvalle, Marie-Christine A1 - Scheer, Ulrich T1 - In vitro assembly of prenucleolar bodies in Xenopus egg extract N2 - Nuclei assembled in Xenopus egg extract from purified DNA or chromatin resemble their natural counterparts in a number of structural and functional features. However, the most obvious structural element of normal interphase nuclei, the nucleolus, is absent from the in vitro reconstituted nuclei. By EM, cytological silver staining, and immunofluorescence microscopy employing antibodies directed against various nucleolar components we show that nuclei assembled in vitro contain numerous distinct aggregates that resemble prenucleolar bodies (PNBs) by several criteria. Formation of these PNB-like structures requires pore complex-mediated nuclear transport of proteins but is independent of the genetic content of the in vitro nuclei as well as transcriptional and translational events. Our data indicate that nuclei assembled in vitro are capable of initiating early steps of nucleologenesis but that the resulting PNBs are unable to fuse with each other, probably due to the absence of a functional nucleolus organizer. With appropriate modifications, this experimental system should be useful to define and analyze conditions promoting the site-specific assembly of PNBs into a coherent nucleolar body. Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34233 ER - TY - JOUR A1 - Scheer, Ulrich T1 - Identification of a novel class of tandemly repeated genes transcribed on lampbrush chromosomes of Pleurodeles waltlii N2 - Electron microscope preparations of lampbrush chromosomes from oocytes of Pleurodeles waltl;; have revealed a new class of tandemly repeated genes. These genes are highly active, as judged by the close spacing of nascent transcripts. They occur in clusters of >100 copies and are transcribed in units containing roughly 940 base pairs of DNA that are separated by nontranscribed spacers of an estimated DNA content of 2,410 base pairs. The size and the pattern of arrangement of these transcription units can not be correlated with any of the repetitious genes so far described. Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33153 ER - TY - JOUR A1 - Franke, Werner W. A1 - Kleinschmidt, Jürgen A. A1 - Spring, Herbert A1 - Krohne, Georg A1 - Grund, Christine A1 - Trendelenburg, Michael F. A1 - Stöhr, Michael A1 - Scheer, Ulrich T1 - A nucleolar skeleton of protein filaments demonstrated in amplified nucleoli of Xenopus laevis N2 - The amplified, extrachromosomal nucleoli of Xenopus oocytes contain a meshwork of -4-nm-thick filaments, which are densely coiled into higher-order fibrils of diameter 30-40 nm and are resistant to treatment with high- and low-salt concentrations, nucleases (DNase I, pancreatic RNase, micrococcal nuclease), sulfhydryl agents, and various nonionic detergents. This filamentous "skeleton" has been prepared from manually isolated nuclear contents and nucleoli as weil as from nucleoli isolated by fluorescence-activated particle sorting. The nucleolar skeletons are observed in light and electron microscopy and are characterized by ravels of filaments that are especially densely packed in the nucleolar cortex. DNA as weil as RNA are not constituents of this structure, and precursors to ribosomal RNAs are completely removed from the extraction-resistant filaments by treatment with high-salt buffer or RN ase. Fractions of isolated nucleolar skeletons show specific enrichment of an acidic major protein of 145,000 mol wt and an apparent pi value of -6.15, accompanied in some preparations by various amounts of minor proteins. The demonstration of this skeletal structure in "free" extrachromosomal nucleoli excludes the problem of contaminations by nonnucleolar material such as perinucleolar heterochromatin normally encountered in studies of nucleoli from somatic cells. It is suggested that this insoluble protein filament complex forms a skeleton specific to the nucleolus proper that is different from other extraction-resistant components of the nucleus such as matrix and lamina and is involved in the spatial organization of the nucleolar chromatin and its transcriptional products. In studies of the organization of the interphase nucleus, considerable progress has been made in the elucidation of the arrangement of chromatin components and transcriptional products. However, relatively little is known about the composition and function of another category of nuclear structures, the nonnucleoproteinaceous architectural components that are insoluble in solutions of low and high ionic strength, despite numerous studies dedicated to this problem. Such structures include (a) the nuclear envelope and its pore complexes (I, 15, 18, 23, 37, 41), (b) a peripheral layer of insoluble protein ("lamina"; I, 15, 22, 23, 59), (e) certain skeletal proteins related to the chromosome "scaffold" described by Laemmli and coworkers (see references 2 and 3), and (d) ill-defined tangles of fibrillar structures of the nuclear interior that are collectively described as residual "matrix" (6, 21 ; for reviews, see references THE JOURNAL OF CEll BrOlOGY . VOlUME 90 AUGUST 1981 289-299 © The RockefeIler University Press · 0021 -9525/ 81 / 08/ 0289/ 11 $1 .00 4 and 12). The latter, preparatively Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33130 ER - TY - JOUR A1 - Franke, Werner W. A1 - Scheer, Ulrich A1 - Krohne, Georg A1 - Jarasch, Ernst-Dieter T1 - The nuclear envelope and the architecture of the nuclear periphery N2 - No abstract available Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33108 ER - TY - JOUR A1 - Bona, Marion A1 - Scheer, Ulrich A1 - Bautz, Ekkehard K. F. T1 - Antibodies to RNA polymerase II (B) inhibit transcription in lampbrush chromosomes after microinjection into living amphibian oocytes N2 - Antibodies directed against RNA polymerase II (B) from Drosophila melanogaster were obtained from rabbit sera and, as monoclonal immunoglobulins, from mouse hybridomas and shown to cross-react with the amphibian enzyme protein. Localization by indirect immunofluorescence microscopy revealed the association of this enzyme with chromatin of interphase nuclei of amphibian cells and its absence in nucleoli. Purified immunoglobulins were microinjected in to nuclei ofliving vitellogenic oocytes of Ple1lrodeles waltlii and X enopus laevis and their effects on transcriptional processes were monitored by biochemical and light and electron microscopic stud ies. RNA polymerase II antibodies from rabbit sera caused a rapid and almost complete release of nascent transcripts from the chromatin axis of the loops of lampbrush chromosomes, followed by collapse of the loops and their retraction on the main chromosome axis. Monoclonal murine antibodies to the Iarge RNA polymerase II subunits also inhibited transcription in chromosome Ioops but appeared to inhibit initiation rather than elongation events. Activities of class land III RNA polymerases were not significantly affected by injection of antibodies to polymerase II, indicating immunological differences between the three RNA polymerases. The potential value of the in vitro test system described , as a very sensitive assay for detecting proteins involved in transcription in living cells, is discussed. 1 Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33128 ER - TY - JOUR A1 - Trendelenburg, Michael F. A1 - Scheer, Ulrich A1 - Zentgraf, Hanswalter A1 - Franke, Werner W. T1 - Heterogeneity of spacer lengths in circles of amplified ribosomal DNA of two insect species, Dytiscus marginalis and Acheta domesticus N2 - No abstract available Y1 - 1976 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33055 ER - TY - JOUR A1 - Emmrich, F. A1 - Moll, Heidrun A1 - Simon, Markus M. T1 - Recombinant human interleukin 2 acts as a B cell growth and differentiation promoting factor N2 - Human B cells appropriately activated by a B cell mitogen are rendered susceptible to human Interleukin 2 (IL-2) as demonstrated with recombinant human IL-2 (rec. h IL-2). They show increased proliferation and drastically enhanced immunoglobulin secretion. Susceptibility to IL-2 is accompanied with the expression of the IL-2 receptor (Tac antigen) on B cells. The data suggest that IL-2 is one of the lymphokines directly involved in the activation of B lymphocytes. Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34132 ER - TY - JOUR A1 - Moll, Heidrun A1 - Emmrich, F. A1 - Simon, Markus M. T1 - Recombinant human interleukin 2 directly provides signals for the proliferation and functional maturation of murine B lymphocytes N2 - In this study the effect of recombinant human interleukin 2 (rec.hIL-2) on the proliferation and maturation of B lymphocytes was investigated. It was found that the presence of rec.hIL 2 results in proliferation of mitogen (LPS)-activated B cell blasts. In addition, it is shown that highly enriched murine B cells can be induced by rec.hIL-2 to proliferate and to develop into antibody-secreting cells (PFC) in the presence of antigen (SRBC). When tested for its effect on B cell preparations enriched for resting (small) or activated (blasted) B lymphocytes, it was found that rec.hIL 2 provides signals for both B cell populations to develop into PFC. In contrast, induction of proliferation by the same lymphokine source was only seen in blasted B cells. The data indicate that IL 2 is involved in the generation of B effector cells by directly acting on their precursors thereby providing differentiation as well as proliferation signals. Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34090 ER - TY - JOUR A1 - Simon, Markus M. A1 - Moll, Heidrun A1 - Prester, Marlot A1 - Nerz, Gaby A1 - Eichmann, Klaus T1 - Immunoregulation by mouse T-cell clones. I. Suppression and amplification of cytotoxic responses by cloned H-Y-specific cytolytic T lymphocytes. N2 - H-Y-specific and H-2Db-restricted, Lyt-1 "2+ T-cell clones (CTLL) with graded specific cytotoxic activities on male C57BL/6 (B6) target cells (1E3, +++; 2C5, ++; 2A5, +, 3E6, ±) were tested for their capacity to inhibit the generation of H-Y-specific cytotoxic T lymphocytes (CTL) in vitro. Addition of irradiated lymphocytes of CTLL 1E3 and CTLL 3E6 but not those of CTLL 2A5 or CTLL 2C5 abolished the generation of CTL from in vivo primed H-Y-specific precursor cells (CTLP) when added to fresh mixed-lymphocyte cultures (MLC). Exogenous sources of T-cell growth factors (TCGF) did not overcome suppression. Rather the presence of TCGF resulted in a further enhancement of suppressive activities in CTLL 1E3 and 3E6 and the induction of similar activities in cells from CTLL 2A5 and 2C5, which by themselves were not inhibitory. Moreover when added to similar MLC on Day 1 instead of Day 0, only irradiated cells of CTLL 3E6 but not those of the other three CTLL were suppressive. Induction of suppressive activities in H-Y-specific CTLL was independent of the appropriate male stimulator cells since it was also observed in MLC induced by irrelevant antigens (H-2, trinitrophenol). Furthermore at low cell numbers, irradiated lymphocytes from any of the CTLL consistently enhanced CTL activities generated from H-Y-specific CTLP. This augmenting activity, which was not TCGF, could be transferred by soluble mediators present in antigen-sensitized CTLL cultures. Thus, these data indicate (i) that cytotoxic effector cells can function as suppressor cells in the generation of CTL, (ii) that the cytotoxic activity of cloned CTL does not correlate with their capacity to suppress CTL responses, (iii) that the inhibition of CTL responses by CTLL is not due to simple consumption of T-cell growth factors produced in MLC, and (iv) that different CTL clones may interfere with the generation of CTL at different stages of their maturation. Moreover, the experiments suggest an antigen-independent enhancement of suppression by the interaction of CTL with lymphokines. Together with the augmenting activity evoked by cloned CTL the data provide strong evidence for the expression of multiple immunological functions by one particular subset of T cells and suggest that cytotoxic effector cells can differentially regulate the maturation and/or clonal expression of their precursor cells. Y1 - 1984 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30892 ER - TY - JOUR A1 - Moll, Heidrun A1 - Eichmann, K. A1 - Simon, M. M. T1 - Immunoregulation by mouse T-cell clones. II. The same H-Y-specific T helper clone can provide help for the generation of cytotoxic lymphocytes and of antibody-secreting cells. N2 - Mouse H-Y-specific and I-Ab restricted T-cell clones have been established and compared for their helper effects in the differentiation ofboth T and B Iymphocytes. The results demonstrate that three individual T -cell clones and one subclone could help in the antigen-driven induction of cytotoxic Iymphocytes (CTL) from their precursor cells (CTL-P), and were able to activate B cells to develop into antibody-secreting cells (PFC) in the presence of SRBC, provided the cloned T cells were restimulated by H-Y antigen on antigen-presenting cells. In addition, antigen or lectin could induce the same H -Y -specific T -cell clones to secrete factor(s) expressing helper activities similar to that ofthe cloned T cells. Furthermore, it is shown that the T cell-derived soluble mediator(s) was distinct from T-cell growth factor (TCGF) and from immune interferon (lFN-y). The data reveal a new type ofT cell with helper potential for the activation ofCTL-P and B Iymphocytes, and suggest the existence of distinct T helper cells which can provide help for both cytotoxic and antibody responses by virtue of different Iymphokine activities. Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30903 ER - TY - JOUR A1 - Frischholz., S. A1 - Röllinghoff, M. A1 - Moll, Heidrun T1 - Cutaneous leishmaniasis: Co-ordinate expression of granzyme A and lymphokines by CD4\(^+\) T cells from susceptible mice. JF - Immunology N2 - We have recently demonstrated that the frequency ofT cells expressing granzyme A is significantly higher in skin lesions and spleens of susceptible BALB/c mice compared with resistant C57BL/6 mice infected with Leishmania major, a cause of human cutaneous leishmaniasis. In the present study, we have performed in vitro studies to characterize the subpopulation, the antigen responsiveness and the lymphokine production pattern of granzyme A-expressing T cells in L. major-infected mice. Using a limiting dilution system for functional analysis of selected T cells at the clonallevel, we could show that granzyme A activity in infected BALB/c mice can be assigned to L. major-reactive CD4\(^+\) T cells secreting interleukin-2 (IL-2) and IL-4. Granzyme A production was most pronounced in the early phase of infection. On the other hand, granzyme A expression could not be detected in C57BL/6-derived T cells responding to L. major. The da ta support the suggestion that granzyme A is produced by L. major-responsive CD4\(^+\) T cells facilitating lesion formation and the dissemination of infection. Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30954 VL - 82 SP - 255 EP - 260 ER - TY - JOUR A1 - Fiala, Brigitte A1 - Grunsky, Harald A1 - Maschwitz, Ulrich A1 - Linsenmair, Karl Eduard T1 - Diversity of ant-plant interactions: Protective efficacy in Macaranga species with different degrees of ant-association. N2 - The pioneer tree Macaranga in SE Asia has developed manyfold associations with ants. The genus comprises all stages of interaction with ants, from facultative relationships to obligate myrmecophytes. Only myrmecophytic Macaranga offer nesting space for ants and are associated with a specific ant partner. The nonmyrmecophytic species are visited by a variety of different ant species which are attracted by extrafloral nectaries (EFN) and food bodies. Transitional Macaranga species like M. hosei are colonized later in their development due to their stem structure. Before the colonization by their specific Crematogaster partner the young plants are visited by different ant species attracted by EFN. These nectaries are reduced and food body production starts as soon as colonization becomes possible. We demonstrated earlier that obligate ant partners can protect their Macaranga plants against herbivore damage and vine cover. In this study we focused on nonspecific interactions and studied M. tanarius and M. hosei, representing a non-myrmecophyte and a transitional species respectively. In ant exclusion experiments both M. tanarius and M. hosei suffered significantly higher mean leaf damage than controls, 37% versus 6% in M. hosei, 16% versus 7% in M. tanarius. M. tanarius offers both EFN and food bodies so that tests for different effects of these two food rewards could be conducted. Plants with food bodies removed but with EFN remaining had the lowest mean increase of herbivore damage of all experimental groups. Main herbivores on M. hosei were mites and caterpillars. Many M. tanarius plants were infested by a shootborer. Both Macaranga species were visited by various ant species. Crematogaster spp. being the most abundant. We found no evidence for any specific relationships. The results of this study strongly support the hypothesis that non-specific, facultative associations with ants can be advantageous for Macaranga plants. Food bodies appear to have lower attractive value for opportunistic ants than EFN and may require a specific dietary adaptation. This is also indicated by the fact that food body production in the transitional M. hosei does not start before stem structure allows a colonization by the obligate Crematogaster species. M. hosei thus benefits from facultative association with a variety of ants until it produces its first domatia and can be colonized by its obligate mutualist. KW - Ant-plant interactions ; Herbivory Macaranga ; Mutualism ; Myrmecophytes Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32905 ER - TY - JOUR A1 - Fiala, Brigitte A1 - Maschwitz, Ulrich T1 - Studies on the south east asian ant-plant association Crematogaster borneensis / Macaranga: adaptations of the ant partner. N2 - C. borneensis (Myrmicinae) lives in dose association with several myrmecophytic species of the South East Asian pioneer tree genus Macaranga (Euphorbiaceae). The ants are adapted to the plants so dosely that they do not survive away from it. The only food they utilize is provided as food bodies by the plant and honeydew from specific scale insects kept inside the hollow internodes. The anatomy of the digestive tract is also adapted to life on the host plant: the crop is very sm all and can store only minute food quantities. C. borneensis exdusively colonizes certain Macaranga species. Queens as weIl as workers are able to recognize their host plant species, probably by chemical cues. Colony founding queens swarm throughout the year, mostly during darkness. There is strong competition among queens for host plants. Queens do not carry scale insects on their nuptial flight. Worker ants are active day and night. Most of them patrol and collect food bodies on the younger parts of the host plant. An important characteristic is their deaning behaviour, which results in removal of aIl foreign objects. Even though they are rather smalI, workers respond very aggressively to certain kinds of disturbance of the host plant. The ants attack most phytophagous insects and are especially effective in killing and removing smalI, softbodied herbivores (e.g. caterpillars). They do not possess a functional sting, but apply defensive secretion and-once biting an intruder-will not let go. Their effective alarm system results in a mass attack, which provides adequate defence for the colony and the host plant. A comparison with another Crematogaster species further illustrated the special adaptations of C. borneensis to its host plant. N2 - Untersuchungen über die südostasiatische Ameisen·Pflanzen-Vergesellschaftung Cremattogaster borneensis Maoaranga : Anpassungen des Ameisenpartners 213 C. borneensis (Myrmicinae) lebt in enger Gemeinschaft mit myrmekophytischen Arten der südostasiatischen Pionierbaumgattung Macaranga (Euphorbiaceae) . Die Ameise ist so eng an die Pflanze adaptiert, daß sie getrennt von ihr nicht lebensfähig ist. Die Nahrung bezieht C. borneensis in Form von Nährkörperchen ausschließlich von der Pflanze. Im Sproßachseninnern gehaltene spezifische Schildläuse bieten eine weitere Nahrungsquelle. Die Adaptationen erstrecken sich bis auf die Anatomie des Verdauungstraktes : Der Kropf ist sehr klein und kann nur geringe Nahrungsmengen speichern. C. borneensis besiedelt spezifisch nur Macaranga-Pflanzen. Sowohl Königinnen als auch Arbeiterinnen sind in der Lage, die Wirtspflanze zu erkennen, wobei offenbar chemische Reize eine Rolle spielen. Die koloniegründenden Königinnen schwärmen das gesamte Jahr über, das Schwärmen erfolgt überwiegend während der Dunkelheit. Um die besiedlungsfähigen Macaranga-Pflanzen herrscht ein starker Konkurrenzdruck. Die beteiligten Schildlausarten sind spezifisch für die Assoziation. Sie werden nicht von der Königin beim Hochzeitsflug mitgenommen. Die Arbeiterinnen sind tag- und nachtaktiv. Die meisten Tiere halten sich im jüngsten Drittel der Pflanze auf, wo sie patrouillieren und Nährkörperchen sammeln. Mittels eines spezifischen Säuberungsverhaltens entfernen die Arbeiterinnen alle Fremdobjekte von der Pflanze. Trotz ihrer geringen Größe attackieren die Ameisen eine Vielzahl phytophager Insekten und sind dabei besonders effektiv in der Abwehr kleiner, wenig sklerotisierter Tiere wie z.B. Raupen. Sie verfügen zwar nicht ' über einen funktionsfähigen Stachel, setzen aber Wehrsekrete ein und beißen sich hartnäckig fest . Mit Hilfe eines effektiven Alarmierungssystems, das einen Massenangriff ermöglicht, gewährleisten sie eine Verteidigung ihrer Kolonien und damit gleichzeitig ihrer Wirtspflanze. Eine Vergleich mit einer anderen Crematogaster-Art demonstriert die besonderen Adaptationen von C. borneensis an ihre Wirtspflanze. Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32689 ER - TY - JOUR A1 - Ernsberger, Uwe A1 - Sendtner, Michael A1 - Rohrer, Hermann T1 - Proliferation and differentiation of embryonic chick sympathetic neurons: Effects of ciliary neurotropic factor. N2 - At early developmental stages (embryonic day 7, E7), chick paravertebral sympathetic ganglia contain a cell population that divides in culture while expressing various neuronal properties. In an attempt to identify factors that control neuronal proliferation, we found that ciliary neurotrophic factor (CNTF) specifically inhibits the proliferation of those cells expressing neuronal markers. In addition, CNTF affects the differentiation of sympathetic ganglion cells by inducing the expression of vasoactive intestinal peptide immunoreactivity (VIP-IR). After 1 day in culture, tyrosine hydroxylase immunoreactivity (TH-I R) was expressed by about 86% of the cells whereas VIP-IR was virtually absent. In the presence of CNTF, 50%-60% of the cells expressed VIP-IR after 4 days in culture; however, none of the cells expressed VIP-IR in the absence of CNTF. These results, and the demonstration of cells that express both VIP and TH-IR, indicate that VIP is induced in cells that initially express tyrosine hydroxylase. The findings suggest a potential role for CNTF as a factor affecting the proliferation and differentiation of developing sympathetic neurons. Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31721 ER - TY - JOUR A1 - Sendtner, Michael T1 - Neurotrophic factors and their action on motoneuron survival: Implications for neuromuscular disorders N2 - Motoneuron diseases represent a m&jor challenge to modern neurology, yet their clinical manifestations ware first described more than hundred years ago, and despite many studies the etiology of these diseases ramd,ns obscure with no effective treatments having been reported. Although progress has been made in establishing genetic linkage in the rare inherited for.ms of these diseases such as familial amyotrophic lateral scleriosisl , spinal mDscular atrophy and X-linked bulbo-spinal-mDscular atrophy, this new information has not yet affected therapeutic techniques. During the last few years several important steps have been taken concerning the physiological mechanisms involved in motoneuron survival during development, after lesion and in animal models of degenerative diseases, the molecular clOning of several new neurotrophic factors (brain-derived neurotrophic factor (BDNP), neurotrophin-3 and-4 (NT-3 and NT-4) and ciliary neurotrophic factor (CNTP)); the identification of a gene family of receptor molecules for same of these factors, progress in the understanding of the effects of polypeptide growth factors on muscle cell differentiation, neuronal sprouting (insulin-like growth factor-I and -11 (IGF-I and IGF-II), and in vitro motoneuronal survival (CNTF, IGF-I and -II and basic FGF). These findings have raised new hopes in that they could lead to a better understanding of the pathophysiological processes underlying these diseases, and that the pharmacological use of same of these newly characterized neurotrophic factors could present new possibilities for the treatment of these diseases. Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31149 ER - TY - JOUR A1 - Schüssler, Ulrich T1 - Petrographie, Geochemie und Metamorphosealter von Metabasiten im KTB-Zielgebiet Oberpfalz N2 - An Metabasiten der Zone Erbendorf-Vohenstrauß, der Erbendorfer Grünschieferzone und der Zone Tirschenreuth-Mähring wurden petrographische, geochemische und phasenpetrologische Untersuchungen sowie K-Ar-Mineraldatierungen durchgeführt. In der Zone Erbendorf-Vohenstrauß treten in regionaler Abhängigkeit drei Haupttypen von Metabasiten auf: 1. Flaseramphibolite mit der Paragenese Hornblende + Oligoklas/ Andesin + Granat ± Salit und mit Plagioklas- und / oder Kalksilikat-reichen Flasern findet man hauptsächlich im nördlichen und zentralen Teil der Zone Erbendorf-Vohenstrauß. Geochemisch zeigen sie eine deutliche Anreicherung der inkompatiblen Elemente und der leichten Seltenerdelemente und sind vergleichbar mit modernen Tholeiiten von ozeanischen Inseln oder anomalen Abschnitten mittelozeanischer Rükken. Ein kontinentaler Intraplatten-Charakter scheint nicht gegeben. In der Kontaktaureole von Windisch-Eschenbach wurde ein Teil der Flaseramphibolite kontaktmetamorph überprägt. 2. Schiefrige, teils streifige Amphibolite mit der Paragenese Hornblende + Andesin / Labrador ± Salit dominieren im Süd teil der Zone Erbendorf-Vohenstrauß, erscheinen aber in einzelnen Ausstrichen auch im Norden. Die Streifung entsteht durch Plagioklas- und / oder Kalksilikat-reiche Zwischenlagen. Geochemisch sind diese Amphibolite bei flachen Spurenelement- und Seltenerdelement- Mustern vergleichbar mit modernen Tholeiiten von normalen Abschnitten mittelozeanischer Rücken. Sowohl Flaseramphibolite als auch schiefrige, teils streifige Amphibolite zeigen Übergänge zu massigen, homogenen Amphiboliten. 3. Metagabbros mit der Paragenese Hornblende + Plagioklas ± Biotit und einer grobkörnigen, gabbro iden Textur treten hauptsächlich im Bereich der Schuppenzone Michldorf-Kaimling (VOLL 1960) auf. Geochemisch nehmen sie bei einer schwachen Anreicherung der inkompatiblen Elemente eine Zwischenstellung zwischen Flaseramphiboliten und schiefrigen, teils streifigen Amphiboliten ein. In der Erbendorfer Grünschieferzone treten Metagabbros und schiefrige, teils gestreifte Amphibolite mit der Paragenese Hornblende + Oligoklas ± Epidot ± Chlorit auf. Die Amphibolite wurden z. T. stark retrograd überprägt und dabei auch deformiert. Dies wird auf größere, post-regionalmetamorphe, tektonische Bewegungen, möglicherweise Deckenüberschiebungen zurückgeführt. Geochemisch sind die Metabasite der Erbendorfer Grünschieferzone mit modernen tholeiitischen bis kalkalkalischen, subduktionsgebundenen Basalten vergleichbar. Sie unterscheiden sich damit völlig von den südlich angrenzenden Flaseramphiboliten der Zone Erbendorf-Vohenstrauß und den nördlich benachbarten Amphiboliten des Fichtelgebirges. Dies unterstreicht die Stellung der Erbendorfer Grünschieferzone als eigenständige tektonische Einheit. Im Vergleich mit dem Münchberger Komplex zeigt die Erbendorfer Grünschieferzone große Ähnlichkeit mit der Prasinit-Phyllit-Serie hinsichtlich der tektonischen Stellung, der Lithologie und insbesondere des geochemischen Charakters der Metabasite. Zwischen der Zone Erbendorf-Vohen-strauß und den Münchberger Serien konnten bezüglich der Metabasite dagegen keine Parallelen festgestellt werden. Schiefrige, teils streifige Amphibolite der Zone Tirschenreuth-Mähring mit der Paragenese Hornblende + Andesin ± Salit (± Granat) und hellen Plagioklas- oder Kalksilikat-reichen Lagen sind geochemisch mit modernen Basalten normaler mittel ozeanischer Rücken vergleichbar. Die untersuchten Metabasite dürften die Zusammensetzung des basaltischen Ausgangsmaterials zumindest annähernd wiedergeben. In einigen Fällen wurde jedoch eine sekundäre Mobilisation von Elementen festgestellt: Die kontaktmetamorphe Überprägung eines Teils der Flaseramphibolite in der Kontaktaureole von Windisch-Eschenbach führte zu einer deutlichen Anreicherung von Rb, Li und K und zu einer Abreicherung von Ca, Sr und V, insbesondere aber von Cr und Ni. Die sog. immobilen Elemente Nb, Ce, (P), Zr, Ti, Y, Sc streuen in einem deutlich breiteren Bereich als bei den nicht kontaktmetamorphen Flaseramphiboliten. In einer Probe sind die Seltenerdelemente insgesamt angereichert. Eine Mobilisation von P20 S und den leichten Seltenerdelementen in einigen schiefrigen, teils streifigen Amphiboliten der Zone Erbendorf-Vohenstrauß und in einigen kontaktmetamorphen Flaseramphiboliten wird auf einen Abbau von Apatit im Zuge einer post-regionalmetamorphen, möglicherweise postgranitischen, hydrothermalen Überprägung zurückgeführt. Mineralchemische Untersuchungen ergaben für die Zusammensetzung der Hornblenden aus Amphiboliten der Zone Erbendorf-Vohenstrauß deutliche regionale Unterschiede, die weitgehend unabhängig von der regionalen Verteilung der einzelnen Metabasit-Haupttypen sind. Vergleichende Untersuchungen an Granat untermauern eine vermutete, frühere, eklogitfazielle Überprägung eines Granatamphibolits vom Nordrand der Zone Erbendorf-Vohenstrauß bei Hauxdorf. K-Ar-Altersdatierungen an Hornblende- und Glimmerkonzentraten belegen, daß das letzte, (Mitteldruck-) metamorphe Ereignis im Westteil der Zone Erbendorf-Vohenstrauß vor etwa 380 Ma beendet war. Dieses Alter wird korreliert mit einer letzten Metamorphose der höhermetamorphen Serien des Münchberger Komplexes zur gleichen Zeit. Im Ostteil der Zone Erbendorf-Vohenstrauß treten jüngere Altersdaten mit einem Schwerpunkt bei 324 Ma auf, die entweder auf einen Einfluß der etwa gleichalten Niederdruck-Metamorphose im unmittelbar benachbarten Moldanubikum i. e. S. oder auf die Intrusion des 324 Ma alten (KÖHLER et al. 1974) Leuchtenberger Granits zurückzuführen sind. Im Übergangsbereich vom Saxothuringikum zum Moldanubikum bei Mähring zeigen Altersdaten um 320Ma das Ende der letzten (Niederdruck-)Metamorphose an. N2 - Petrographical, petrological and geochemical investigations as well as K-Ar mineral-dating were carried out on metabasites of the Zone Erbendorf-Vohenstrauß, the Erbendorf Greenschist Zone and the Zone Tirschenreuth-Mähring. Within the Zone Erbendorf-Vohenstrauß, three main types ofmetabasites occur in a clear regional distribution: 1. Flaseramphibolites with hornblende + oligoclase I andesine + gamet ± salite and with ill-defined plagioclase- and I or calc-silicate-rich flaser texture are dominating in the northern and central part ofthe Zone Erbendorf-Vohenstrauß. Geochemically, they are clearly enriched in incompatible elements and light rare earth elements and compare well with modern tholeiites of ocean islands or anomalous mid-ocean ridge segments. There are no indications for a continental within-plate character. 2. Schistose, partly striped amphibolites with hornblende + andesine I labradore ± salite prevail in the southern part of the Zone Erbendorf-Vohenstrauß, but also occur in some outcrops of the northern part. Stripes are formed by plagioclase- and I or calc-silicat-rich intercalations. Geochemically, these amphibolites with flat trace element- and rare earth element patterns are similar to modern tholeiites from normal mid-ocean ridges. Flaseramphibolites as well as schistose, partly striped amphibolites sometimes form transitions to massive, homogeneous amphibolites. 3. Metagabbros with hornblende + plagioclase ± biotite in a coarse, gabbroic structure mainly occur within the "Schuppenzone Michldorf-Kaimling" (VOLL 1960). Geochemically, they are transitional between flaseramphibolites and schistose, partly striped amphibolites. Within the Erbendorf Greenschist Zone, metagabbros and schistose, sometimes striped amphibolites with hornblende + oligocJase ± epidote ± chlorite occur. Part of them underwent astrang retrograde overprint, accompanied by deformation. This may be a consequence oflarge, post-regionalmetamorphic tectonic movements, possibly nappe-thrusting. Geochemically, the metabasites of the Erbendorf Greenschist Zone can be compared with modem tholeiitic to calc-alkaline, subduction-bound basalts. Thus, they differ c1early from flaseramphibolites ofthe Zone Erbendorf-Vohenstrauß in the south and amphibolites ofthe Fichtelgebirge in the north. This underscores the position of the Erbendorf Greenschist Zone as aseparate tectonic unit. Compared with units ofthe Münchberg complex, a elose correlation exists between the Erbendorf Greenschist Zone and the Prasinit-Phyllit-Serie relative to the tectonic position, the lithology and especially the geochemistry of metabasites. In contrast, a correlation between the Zone Erbendorf-Vohenstrauß and the crystalline units ofthe Münchberg complex is not encouraged by the composition of the metabasites. Schistose, partly striped amphibolites ofthe Zone Tirschenreuth-Mähring with hornblende + andesine ± salite (± gamet) and sometimes plagioelase- or ca1c-silicate-rich intercalations are geochemically similar to modem basalts of normal mid-ocean ridges. In most ofthe investigated metabasites the geochemical composition ofthe basaltic protoliths may be approximately conserved. In some cases, however, secondary element mobilization was recognized: The contact-metamorphic overprint of some flaseramphibolites led to an enrichment of Rb, Li and K and a simultaneous dep1etion ofCa, Sr and V, especially ofCr and Ni. The elements Nb, Ce, (P), Zr, Ti, Y, Sc, commonly regarded as immobile, scatter in a much wider range than in the unaffected flaseramphibolites. In one sampIe the rare earth elements are enriched. A mobilization of P2Üs and the light rare earth elements in some schistose, partly striped amphibolites ofthe Zone Erbendorf-Vohenstrauß as weil as some contact-metamorphosed flaseramphibolites is presumably a result of apatite decomposition during a post-regionalmetamorphic, possibly postgranitic hydrothermal overprint. Homblendes with different chemical compositions from amphibolites ofthe Zone ErbendorfVohenstrauß show a elear regional distribution which is almost entirely independent from the distribution of the main metabasite types. A comparison of gamet compositions underscores the eelogitic precursor rock of the gamet-amphibolite from Hauxdorf near Erbendorf. K-Ar dating on homblendes and micas verify that the last (medium-pressure) metamorphic event in the western part ofthe Zone Erbendorf-Vohenstrauß ended 380 Ma ago. This correlates with the last metamorphic overprint of the Münchberg crystalline units at the same time. In the eastern part of the Zone Erbendorf-Vohenstrauß younger ages around 324 Ma occur. This either refers to an influence from the last (low-pressure) metamorphism ofthe neighbouring Moldanubian s.str. with nearly the same age, or to an influence by the intrusion ofthe 324 Ma old (KÖHLER et al. 1974) Leuchtenberg granite. K-Ar ages of about 320 Ma from the transition between the Saxothuringian and the Moldanubian near Mähring testjfy to the end of the last (low-pressure) metamorphic overprint in this area. Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31694 N1 - Zugl. Diss. Univ. Würzburg, 1990 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Zentgraf, Hanswalter A1 - Sauer, Helmut W. T1 - Different chromatin structures in Physarum polycephalum: a special form of transcriptionally active chromatin devoid of nucleosomal particles N2 - Nonnucleolar chromatin from interphase nuclei of Physarum polycephalum plasmodia occurs in two different structural configurations as seen in electron microscopic spread preparations. While the majority of the chromatin is devoid of nascent ribonucleoprotein (RNP) fibrils and compacted into nucleosomal particles, a minor proportion (10- 20%) is organized differently and reveals a smooth contour. It is this form of smooth chromatin which is rich in transcription units (mean length: 1.36±0.21 11m). Only occasionally are solitary nascent RNP fibrils observed which are associated with beaded strands of chromatin. In transcribed smooth chromatin nucleosomal particles are not only absent from the transcription units but also from their nontranscribed flan king regions, indicating that this special structural aspect is not merely a direct consequence of the transcriptional process. The existence of ca. 10- 20% of Physarum chromatin in the smoothly contoured form is discussed in relation to reports of a preferential digestibility of a similar proportion of Physarum chromatin by DNAse I (Jalouzot et al. , 1980) and to the altered configuration of "peak A" chromatin subunits after micrococcal nuclease digestion (Johnson et al., 1978a, b). Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33148 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Zentgraf, Hanswalter T1 - Nucleosomal and supranucleosomal organization of transcriptionally inactive rDNA circles in Dytiscus oocytes N2 - Oocytes of the water beetle, Dytiscus marginalis, contain large amounts of rDNA most of which is present in the form of rings containing one or several pre-rRNA genes. Electron microscopy of spread preparations of vitellogenic oocytes has shown that the rDNA is extended in chromatin rings with transcribed pre- rRNA genes and is not packed into nucleosomes (Trendelenburg eta!. , 1976). When similar preparations are made from previtellogenic ooytes in which a large proportion of the nuc1eolar chromatin is transcriptionally inactive, a different morphological form of this chromatin is recognized. In contrast to the transcribed chromatin rings the inactive nucleolar chromatin circles show the characteristic beaded configuration, indicative of nucleosomal packing. Nuc1eosomal packing is also indicated by the comparison of the lengths of these chromatin rings with both iso lated rDNA circ1es and transcribed chromatin rings. In addition, these inactive nuc1eofilaments often appear to be compacted into globular higher order structures of diameters from 21 to 34nm, each composed of an aggregate of 6-9 nuc1eosomes. While the estimated reduction of the overall length of rDNA, as seen in our preparations, is, on the average, only 2.2 - 2.4 fold in the nuc1eosomal state it is 10- 13 fold when supranuc1eosomal globules are present. These data show that the extrachromosomal rDNA of these oocytes goes through a cycle of condensation and extensio n, as a function of the specific transcriptional activity, and that the beaded state described here is exc1usively found in the non-transcribed state. Y1 - 1978 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33188 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Trendelenburg, Michael F. A1 - Krohne, Georg A1 - Franke, Werner W. T1 - Lengths and patterns of transcriptional units in the amplified nucleoli of oocytes of Xenopus laevis N2 - Transcriptionally active chromatin from peripheral amplified nuc1eoli of lampbrush-chromosome stage oocytes of Xenopus laevis was dispersed and spread in various solutions of low salt concentrations (incIuding some with additions of detergents) and examined by electron microscopy. Nucleolar material from oocytes of animals with normal (2-nu) and mutant (I-nu) genetical constitution of nucleolus organizers was compared. Histograms showing the distributions of the lengths of matrix units, apparent spacer intercepts, and the total repeating units of the rDNA containing chromatin axes revealed a significant degree of heterogeneity, with indications of subclasses and predominant repeat unit size c1asses of 3.3 and 3.8 11m length. The correspondence of matrix unit length to the molecular weight of the first stable product of rDNA transcription was studied using gel electrophoresis of labelIed pre-rRNA under non-denaturing and denaturing conditions. Evaluations of individual strands of nucleolar chromatin furt her demonstrated the existence of both (i) strands with obviously homogeneous repeating units and (ii) strands with intra-axial heterogeneity of rDNA subunits. " Preludecomplexes ", i.e. groups of transcriptional complexes in apparent spacer intercepts, were not infrequently noted. The data are compared with the measurements of lengths of repeating units in fragments of rDNA obtained by digestion with EcoRI endonuclease as described by Morrow et al. (1974) and Wellauer et al. (1974, 1976a, b). The results are discussed in relation to problems of variations in the modes of arrangement of the pre-rRNA genes, the state of packing of rDNA during transcription, and possible mechanisms of the amplification process. Y1 - 1977 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33069 ER - TY - JOUR A1 - Zentgraf, H. A1 - Müller, U. A1 - Scheer, Ulrich A1 - Franke, W. W. T1 - Evidence for the existence of globular units in the supranucleosomal organization of chromatin N2 - No abstract available Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34123 ER - TY - JOUR A1 - Schüssler, Ulrich A1 - Henjes-Kunst, Friedhelm T1 - Petrographical and Geochronological Investigations on a Garnet-Tourmaline Pegmatite from Ringgold Knoll, Oates Coast, Antarctica N2 - The Ringgold Knoll pegmatite, a late-stage member of the Granite Harbour Intrusives, crosscuts high-grade Wilson gneisses of the Oates Coast, which forms the westernmost part of the Wilson Terrane at the Pacific end of the Cambro-Ordovician Ross orogenic belt in West Antarctica. The pegmatite mineral assemblage consists of K-feldspar, plagioclase, quartz, garnet (almandinespessartine-pyrope), dark tourmaline (schorl-dravite), muscovite, apatite, monazite, zircon, blue AI-rich tourmaline and dumortierite in order of decreasing abundances. Major, minor and rare earth elements are reported for the greater part of the mineral assemblage. The time of pegmatite emplacement is constrained by Rb-Sr and Sm-Nd isochron ages of 492 ± 8 (2a) Ma and 500 ± 40 (2a) Ma, respectively. High initial 87Sr/86Sr of 0.7315 ± 0.0003 and low E Nd,t of -8.7 ± 1.2 strongly support an origin of the magma from highly evolved crustal source rocks. K-Ar and Ar-Ar model ages of about 470 to 475 Ma for igneous muscovite indicate that the pegmatite together with its wall rocks spent a prolonged period at elevated temperatures before final cooling below about 350 °C. The muscovite dates may give an estimate for the time of exhumation of the Oates Coast crystalline basement along two major late Ross orogenic detachment zones within the Wilson Terrane i.e. the Wilson and the Exiles thrusts (c.f. FLÖTTMANN and KLEINSCHMIDT, 1991). N2 - Der Pegmatit vom Ringgold Knoll geh6rt zur spaten Gangfolge der Granite Harbour Intrusionen und durchschlagt hochgradig metamorphe Wilson Gneise der Oates Coast, die den westlichsten Teil des Wilson Terranes am pazifischen Ende des Kambro-Ordovizischen Ross Orogengiirtels in der Westantarktis bildet. Die pegmatitische Mineralparagenese besteht aus Kalifeldspat, Plagioklas, Quarz, almandin-spessartin-pyrop-betontem Granat, dunklem schorl-dravit-betontem Turmalin, Muscovit, Apatit, Monazit, Zirkon, blauem AI-reichem Turmalin und Dumortierit in der Reihenfolge abnehmenden Modalanteils. FUr den groBeren Teil der Minerale wurden Haupt-, Neben- und Seltenerdelemente bestimmt. Der Zeitpunkt der Pegmatitintrusion wird durch Rb-Sr und Sm-Nd Isochronenalter von 492 ± 8 (20") Ma bzw. 500 ± 40 Ma (20") datiert. Ein hohes "SrI" Sr Initialverhaltnis von 0,7315 ± 0,0003 und ein niedriger Wert flir E Nd,t von -8,7 ± 1,2 sprechen deutlich für eine Magmenherkunft von hochdifferenzierten krustalen Ausgangsgesteinen. K-Ar und Ar-Ar Modellalter von etwa 470 bis 475 Ma von magmatischem Muscovit zeigen, daB der Pegmatit und das Nebengestein eine langsame AbkUhlung auf Temperaturen unter etwa 350°C er1ebten. Die Muscovitdaten konnen als eine Zeitmarke gesehen werden fUr die Heraushebung des kristallinen Grundgebirges der Oates Coast entlang der zwei split Ross-orogenen Wilson und Exiles Hauptüberschiebungszonen im Wilson Terrane (FLÖTTMANN und KLElNSCHMlDT 1991). Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31789 ER - TY - JOUR A1 - Fiala, Brigitte A1 - Maschwitz, Ulrich T1 - Domatia as most important adaptations in the evolution of myrmecophytes in the paleotropical tree genus Macaranga (Euphorbiacae) N2 - The paleotropical tree genus Macaranga (Euphorbiaceae) comprises all stages of interaction with ants, from facultative associations to obligate myrmecophytes. In SE.-Asia food availability does not seem to be the limiting factor for the development of a close relationship since all species provide food for ants in form of extrafloral nectar and/or food bodies. Only myrmecophytic Macaranga species offer nesting space for ants (domatia) inside intern odes which become hollow due to degeneration of the pith. Non-myrmecophytic species have a solid stem with a compact and wet pith and many resin ducts. The stem interior of some transitional species remains solid, but the soft pith can be excavated. The role of different ant-attracting attributes for the development of obligate ant-plant interactions is discussed. In the genus Macaranga, the provision of nesting space seems to be the most important factor for the evolution of obligate myrmecophytism. KW - Angiosperms ; Ant-plant interactions ; domatia ; Flora of Malaysia Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32935 ER - TY - JOUR A1 - Krohne, Georg A1 - Franke, Werner W. A1 - Scheer, Ulrich T1 - The major polypeptides of the nuclear pore complex N2 - Nuclear envelopes of maturing oocytes of various amphibia contain an unusually high number of pore complexes in very close packing. Consequently, nuclear envelopes , which can be manually isolated in great purity, provide a remarkable enrichment of nuclear pore complex material, relative to membranous and other interporous structures. When the polypeptides of nuclear envelopes isolated from oocytes of Xenopl/s la evis and Triturus alpestris are examined by gel electrophoresis, visualized either by staining with Coomassie blue or by radiotluorography after in vitro reaction with [3H]dansyl chloride , a characteristic pattern is obtained (10 major and 15 minor bands). This polypeptide pattern is radically different from that of the nuclear contents isolated from the same cell. Extraction of the nuclear envelope with high salt concentrations and moderateIy ac tive detergents such as Triton X- 100 results in the removal of membrane material but leaves most of the non-membranous structure of the pore complexes. The dry weight of the pore complex (about 0.2 femtograms) remains essentially unchanged during such extractions as measured by quantitative electron microscopy . The extracted preparations which are highly enriched in nuclear pore complex material contain only two major polypeptide components with apparent molecular weights of 150000 and 73000. Components of such an electrophoretic mobility are not present as major bands , if at all , in nuclear contents extracted in the same way. lt is concluded that these two polypeptides are the major constituent protein(s) of the oocyte nuclear pore complex and are specific for this structure. When nuclear envelopes are isolated from rat liver and extracted with high salt buffers and Triton X- 100 similar bands are predominant, but two additional major components of molecular weights of 78000 and 66000 are also recognized. When the rat liver nuclear membranes are further subfractionated material enriched in the 66000 molecular weight component can be separated from the membrane material, indicating that this is relatively loosely associated material , probably a part of the nuclear matrix . The results suggest that the nuclear pore complex is not only a characteristic ubiquitous structure but also contains similar, if not identical , skeletal proteins that are remarkably re sistant to drastic changes of ionic strength as weil as to treatments with detergents and thiol reagents. Y1 - 1978 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33078 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Sommerville, John T1 - Sizes of chromosome loops and hnRNA molecules in oocytes of amphibia of different genome sizes N2 - The lengths of lampbrush chromosome loops and their tran scription units show a positive correlation with genome size in oocytes of amphibia with different C values. However, there is no such correlation with contour lengths of hnRNA molecu les isolated from these oocytes. These results indi cate th at more ON A sequences are transcribed in amphibia of higher C value , but that processing of RNA transc ripts occurs while they are still attached to the chromosomes as nascent ribonucleoprotein fibrils. Y1 - 1982 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33094 ER - TY - JOUR A1 - Rungger, M. A1 - Crippa, M. A1 - Trendelenburg, M. F. A1 - Scheer, Ulrich A1 - Franke, Werner W. T1 - Visualization of rDNA spacer transcription in Xenopus oocytes treated with fluorouridine N2 - Under the intluence of 5-tluoro-uridine, the ultrastructure of the rDNA transcription units in Xenopus oocytes is altered. Whereas part of the matrix units maintains anormal aspect or shows various degrees of inhibition, in a strong proportion of the transcription units the alternating pattern of matrix units and fibril-free spacer regions is no longer recognized. Transcriptional complexes are found along the entire DNP axis, including the regions of the spacers. These observations support biochemical data on transcription in rDNA spacer region. Y1 - 1978 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33082 ER - TY - JOUR A1 - Dabauvalle, Marie-Christine A1 - Schulz, Barbara A1 - Scheer, Ulrich A1 - Peters, Reiner T1 - Inhibition of nuclear accumulation of karyophilic proteins in living cells by microinjection of the lectin wheat germ agglutinin N2 - No abstract available Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34288 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Lanfranchi, Gerolamo A1 - Rose, Kathleen M. A1 - Franke, Werner W. A1 - Ringertz, Nils R. T1 - Migration of rat RNA polymerase I into chick erythrocyte nuclei undergoing reactivation in chick-rat heterokaryons N2 - Transcriptionally inactive chick erythrocyte nudei were reactivated by Sendai virusinduced fusion of erythrocytes with rat L6j1 myoblasts. We used antibodies to trace the appearance of a specific protein engaged in transcription of a defined dass of genes, those coding for rRNA, during reactivation. Using immunofluorescence microscopy, we found increasing amounts of rat RNA polymerase I to appear, during a certain period of time after fusion, in the reforming nudeoli of the chick nudei. Amounts of rat RNA polymerase I sufficient to be detected by immunofluorescence microscopy had accumulated in the newly developed chick nudeoli 72- 190 h after fusion was initiated. This time interval coincides with the time when chick rRNA synthesis can first be detected. The results raise the possibility that during these stages of the reactivation process chick rRNA genes are transcribed by heterologous RNA polymerase I moleeules of rat origin. Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33232 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Hügle, Barbara A1 - Hazan, Rachel A1 - Rose, Kathleen M. T1 - Drug-induced dispersal of transcribed rRNA genes and transcriptional products: Immunolocalization and silver staining of different nucleolar components in rat cells treated with 5,6-dichloro-1-Beta-D-ribofuranosylbenzimidazole N2 - Upon incubation of cultured rat cells with the adenosine analogue 5,6-dichloro-l-β- D-ribofuranosylbenzimidazole (DRB), nucleoli reversibly dissociate into their substructures, disperse throughout the nuclear interior, and form nucleolar "necklaces". We have used this experimental system, which does not inhibit transcription of the rRNA genes, to study by immunocytochemistry the distribution of active rRNA genes and their transcriptional products during nucleolar dispersal and recovery to normal morphology. Antibodies to RNA polymerase I allow detection of template-engaged polymerase, and monoclonal antibodies to a ribosomal protein (S 1) of the small ribosomal subunit permit localization of nucleolar preribosomal particles. The results show that, under the action of DRB transcribed rRNA, genes spread throughout the nucleoplasm and finally appear in the form of several rows, each containing several (up to 30) granules positive for RNA polymerase land argyrophilic proteins. Nucleolar material containing preribosomal particles also appears in granular structures spread over the nucleoplasm but its distribution is distinct from that of rRNA gene-containing granules. We conclude that, although transcriptional units and preribosomal particles are both redistributed in response to DRB, these entities retain their individuality as functionally defined subunits. We further propose that each RNA polymerase-positive granular unit represents a single transcription unit and that each continuous array of granules ("string of nucleolar beads") reflects the linear distribution of rRNA genes along a nucleolar organizer region. Based on the total number of polymerase I-positive granules we estimate that a minimum of 60 rRNA genes are active during interphase of DRB-treated rat cells. Y1 - 1984 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33216 ER - TY - JOUR A1 - Zentgraf, Hanswalter A1 - Trendelenburg, Michael F. A1 - Spring, Herbert A1 - Scheer, Ulrich A1 - Franke, Werner W. A1 - Müller, Ulrike A1 - Drury, Kenneth C. A1 - Rungger, Duri T1 - Mitochondrial DNA arranged into chromatin-like structures after injection into amphibian oocyte nuclei N2 - Purified mitochondrial DNA (mitDNA) from ovaries ofXenopus lae vis was injected into the nuclei (germinal vesicles) of large viteUogenic oocytes of the same organism and examined by electron microscopy ofthe spread nuclear contents. Normally located nuclei of untreated oocytes as weil as peripherally translocated nuclei of centrifuged oocytes were used. In addition, oocyte nuclei isolated and incubated under liquid paraffin oil were injected with DNA. The integrity oftranscriptional structures of endogenous chromosomal (Iampbrush chromosomes) and extrachromosomal (nucleoli) genes of the injected nuclei was demonstrated. Microinjected mitDN A was identified as circles of chromatin exhibiting polynucleosome-like organization and a me an contour length of 2.6 J.Lm, corresponding to a compaction ratio of the mitDN A of about 2 : I. This DNA packing ratio is similar to that observed after preparation of various kinds of native chromatin in low salt buffers. The chromatin circles formed from injected mitDNA only very rarely exhibited lateral fibrils suggestive of transcriptional activity. These results suggest that purified mitDNA can be transformed to normally structured chromatin when exposed to oocyte nuclear contents but is rarely , if at all , transcribed in this form and in this environment. Y1 - 1979 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33174 ER - TY - JOUR A1 - Carroll, Patrick A1 - Sendtner, Michael A1 - Meyer, Michael A1 - Thoenen, Hans T1 - Rat ciliary neurothrophic factor (CNTF): gene structure and regulation of mRNA levels in glial cell cultures. N2 - The structure of the rat ciliary neurotrophic factor (CNTF) gene and the regulation ofCNTF mRNA levels in cultured glial cells were investigated. The rat mRNA is encoded by a simple two-exon transcription unit. Sequence analysis of the region upstream of the transcription start-site did not reveal a typical TATA-box consensus sequence. Low levels of CNTF mRNA were detected in cultured Schwann cells, and CNTF mRNA was not increased by a variety of treatments. Three-week-old astrocyteenriched cell cultures from new-born rat brain contained easily detectable CNTF mRNA. In astrocyte-enriched cultures, upregulation of CNTF mRNA levels was observed after treatment with IFN-gamma. CNTF mRNA levels were down-regulated in these cells by treatments that elevate intracellular cyclic AMP and by members of the fibroblast growth factor (FGF) family. The implications of these results for potential in vivo functions of CNTF are discussed. KW - Astrocytes ; Schwann cells ; Interferon-gamma ; Fibroblast growth factor ; Cyclic AMP Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31763 ER - TY - JOUR A1 - Arakawa, Yoshihiro A1 - Sendtner, Michael A1 - Thoenen, Hans T1 - Survival effect of ciliary neurotrophic factor (CNTF) on chick embryonic motoneurons in culture: comparison with other neurotrophic factors and cytokines N2 - No abstract available Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31718 ER - TY - JOUR A1 - Sendtner, Michael A1 - Stöckli, K. A. A1 - Thoenen, Hans T1 - Synthesis and localization of ciliary neurotrophic factor in the sciatic nerve of the adult rat after lesion and during regeneration N2 - Ciliary neurotrophic factor (CNTF) is expressed in high quantities in Schwann cells of peripheral nerves during postnatal development of the rat. The absence of a hydrophobic leader sequence and the immunohistochemical localization of CNTF within the cytoplasm of these cells indicate that the factor might not be available to responsive neurons under physiological conditions. However, CNTF supports the survival of a variety of embryonic neurons, including spinal motoneurons in culture. Moreover we have recently demonstrated that the exogenous application of CNTF protein to the lesioned facial nerve of the newborn rat rescued these motoneurons from cell death. These results indicate that CNTF might indeed play a major role in assisting the survival of lesioned neurons in the adult peripheral nervous system. Here we demonstrate that the CNTF mRNA and protein levels and the manner in which they are regulated are compatible with such a function in lesioned peripheral neurons. In particular, immunohistochemical analysis showed significant quantities of CNTF at extracellular sites after sciatic nerve lesion. Western blots and determination of CNTF biological activity of the same nerve segments indicate that extracellular CNTF seems to be biologically active. After nerve lesion CNTF mRNA levels were reduced to <5 % in distal regions of the sciatic nerve whereas CNTF bioactivity decreased to only one third of the original before-lesion levels. A gradual reincrease in Schwann cells occurred concomitant with regeneration. Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31738 ER - TY - JOUR A1 - Stöckli, K. A. A1 - Lililien, L. E. A1 - Näher- Noé, M. A1 - Breitfeld, G. A1 - Hughes, Richard A. A1 - Raff, M. C. A1 - Thoenen, Hans A1 - Sendtner, Michael T1 - Regional distribution, developmental changes, and cellular localization of CNTF-mRNA and protein in the rat brain N2 - Ciliary neurotrophic factor (CNTF) is a potent survival molecule for a variety of embryonic neurons in culture. The developmental expression of CNTF occurs clearly after the time period of the physiological cell death of CNTF-responsive neurons. This, together with the sites of expression, excludes CNTF as a target-derived neuronal survival factor, at least in rodents. However, CNTF also participates in the induction of type 2 astrocyte differentiation in vitro. Here we demonstrate that the time course of the expression of CNTF-mRNA and protein in the rat optic nerve (as evaluated by quantitative Northern blot analysis and biological activity, respectively) is compatible with such a glial differentiation function of CNTF in vivo. We also show that the type 2 astrocyte-inducing- activity previously demonstrated in optic nerve extract can be precipitated by an antiserum against CNTF. Immunohistochemical analysis of astrocytes in vitro and in vivo demonstrates that the expression of CNTF is confined to a subpopulation of type 1 astrocytes. The olfactory bulb of adult rats has comparably high levels of CNTF to the optic nerve, and here again, CNTF-immunoreactivity is localized in a subpopulation of astrocytes. However, the postnatal expression of CNTF in the olfactory bulb occurs later than in the optic nerve. In other brain regions both CNTF-mRNA and protein levels are much lower. Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31172 ER - TY - JOUR A1 - Masu, Yasuo A1 - Wolf, Eckhard A1 - Holtmann, Bettina A1 - Sendtner, Michael A1 - Brem, Gottfried A1 - Thoenen, Hans T1 - Disruption of the CNTF gene results in motor neuron degeneration N2 - CNTF is a cytosolic molecule expressed postnatally in myelinating Schwann cells and in a subpopulation of astrocytes. Although CNTF administration prevents lesion-mediated and genetically determined motor neuron degeneration, its physiological function remained elusive. Here it is reported that abolition of CNTF gene expression by homologous recombination results in a progressive atrophy and loss of motor neurons in adult mice, which is functionally reflected by a small but significant reduction in muscle strength. Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33038 ER - TY - JOUR A1 - Meng, Li A1 - Sendtner, Michael A1 - Smith, Austin T1 - Essential function of LIF receptor in motor neurons N2 - D EVELOPME'iT and maintenance of the mammalian nervous system is dependent upon neurotrophic cytokines. One class of neurotrophic factor acts through rcccptor complexes involving the lowaffinity leukaemia inhibitor y faclor receptor subunit (LlF-R). Members of this fa mily of cytokines, such as ciliary neurotrophic factor (CNTF) and leukaemia inhibitory factor (LIF), have profound effects on the survival and maintenance of motor neurons, Recently it was reported that mice lacking LlF-R die shortly after birth unlike mice lacking CNTF or LIF which are viable. Here we describe histopathological analyses of lifr mutants tha t reveal a loss > 35% of facia l motor neurons, 40% of spinal motor neurons and 50% of neurons in the nucleus ambiguus. These findings point to the existence of a ligand for LIF-R tha t is required for the normal development of motor neurons in both brainstem nuclei and spinal cord. Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34219 ER - TY - JOUR A1 - Stöckli, K. A. A1 - Lottspeich, F. A1 - Sendtner, Michael A1 - Masiakowski, P. A1 - Carroll, Patrick A1 - Götz, Rudolf A1 - Lindholm, D. A1 - Thoenen, Hans T1 - Molecular cloning, expression and regional distribution of rat ciliary neurotrophic factor N2 - CILIARY neurotrophic factor (CNTF) was originally characterized as a survival factor for chick ciliary neurons in vitro. More recently, it was shown to promote the survival of a variety of otherneuronal cell types and to affect the differentiation of E7 chick sympathetic neurons by inhibiting their proliferation and by inducing the expression of yasoactiYe intestinal peptide immunoreactiyity (VIP-IR). In cultures of dissociated sympathetic neurons from newborn rats, CNTF induces cholinergic differentiation as shown by increased levels of choline acetyltransferase (ChAT. Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34229 ER - TY - JOUR A1 - Ellgring, Johann Heinrich T1 - Video-unterstützte Therapie und Supervision - ein Überblick N2 - No abstract available Y1 - 1982 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33599 ER - TY - JOUR A1 - Bünemann, Moritz A1 - Pott, Lutz T1 - Membrane-delimited activation of muscarinic K current by an albumin-associated factor in guinea-pig atrial myocytes N2 - No abstract available KW - cardiac myocyte ; muscarinic K current ; G-protein ; Albumin ; serum Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31300 ER - TY - JOUR A1 - Vortkamp, Andrea A1 - Gessler, Manfred A1 - Paslier, D. Le A1 - Elaswarapu, R. A1 - Smith, S. A1 - Grzeschik, Karl-Heinz T1 - Isolation of a yeast artificial chromosome contig spanning the Greig cephalopolysyndactyly syndrome (GCPS) gene region N2 - Disruption of the zinc finger gene GLI3 has been shown to be the cause of Greig cephalopolysyndactyly syndrome (GCPS), at least in some GCPS translocation patients. To characterize this genomic region on human chromosome 7p13, we have isolated a VAC contig of more than 1000 kb including the GLI3 gene. In this contig the gene itself spans at least 200-250 kb. A CpG island is located in the vicinity of the 5' region of the known GLI3 cDNA, implying a potential promoter region. Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30182 ER - TY - JOUR A1 - Maschwitz, U. A1 - Fiala, Brigitte A1 - Dolling, W. R. T1 - New trophobiotic symbioses of ants with South East Asian bugs N2 - A trophobiotic relationship between two species of phloem-feeding plataspid bugs and an ant, Meranoplus mucronatus, was discovered on tree trunks in Malaysia. Similar relationships were found between coreid bugs and Crematogaster sp. and Anoplolepis longipes, on bamboo in the same area. The ants recruit to groups of the bugs and feed on the liquid, sugar-rich faeces of the larvae, stimulating release of the honeydew by tactile signals. They protect all stages of the bugs from disturbance by biting and by the use of defensive secretions. Phloem-feeding bugs in the families Plataspidae and Coreidae need long sty lets to pierce the thick bark of their host tree. The different methods of accommodating the resting stylets in these two families are described. The plataspids are described as Tropidotylus servus sp. novo and T. minister sp. novo A coreid previously reported in association with M. mucronatus in Malaya is described as Hygia cliens sp. novo The coreids on bamboo were determined as Cloresmus spp. and Notobitus affinis. KW - Ants KW - Coreidae KW - Heteroptera KW - Malaya KW - New Species KW - Plataspidae KW - Trophobiosis Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34030 ER - TY - JOUR A1 - Moreno-Diaz de la Espina, Susana A1 - Franke, Werner W. A1 - Krohne, Georg A1 - Trendelenburg, Michael F. A1 - Grund, Christine A1 - Scheer, Ulrich T1 - Medusoid fibril bodies: a novel type of nuclear filament of diameter 8 to 12 nm with periodic ultrastructure demonstrated in oocytes of Xenopus laevis N2 - No abstract available Y1 - 1982 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34116 ER - TY - JOUR A1 - Hadjiolova, Krassimira A1 - Rose, Kathleen M. A1 - Scheer, Ulrich T1 - Immunolocalization of nucleolar proteins after D-galactosamine-induced inhibition of transcription in rat hepatocytes N2 - No abstract available Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33205 ER - TY - JOUR A1 - Maschwitz, Ulrich A1 - Fiala, Brigitte A1 - Moog, J. A1 - Saw, L. G. T1 - Two new myrmecophytic associations from the Malay Peninsula: ants of the genus Cladomyrma as partners of Saraca thaipingensis and Crypteronia griffithii N2 - In Peninsular Malaysia the trees Saraca thaipingensis (Caesalpiniaceae) and Crypteronia griffithii (Crypteroniaceae) are inhabited by ants. In the vicinity ofGombak, near Kuala Lumpur, the hollow internodes of young Saraca thaipingensis plants are colonized mainly by two Cladomyrma species. In larger trees a Crematogaster sp. is also found. Crypteronia griffithii is inhabited by a third species of Cladomyrma. None of these species is conspecific with any of the three Cladomyrma taxa so far described. The colonies are founded by single mated queens, which have a conspicuous, sphecid wasp-like behaviour when searching for host plants and nest sites. They chew holes into the plant intern odes and hollow them out to provide nest sites. Coccids and pseudococcids are cultivated within the internodes. The homopterans are not carried by queens on their nuptial flights. They apparently find their way by themselves into the cavities or are perhaps carried there by the worker ants. The Cladomyrma ants on Crypteronia are not aggressive, in contrast to those on Saraca thaipingensis. The relationship of Crypteronia with ants seems to be obligatory, whereas Saraca was only partly colonized by Cladomyrma. The interaction of Saraca with Crematogaster sp. is loose and facultative, since the Crematogaster sp. also lives on other tree species. Our studies have now revealed four Cladomyrma spp. which are regularly associated with plants. The genus therefore seems to have an entirely myrmecophytic way of life. KW - Myrmecophytism ; Malaysia ; trophobionts ; colony foundation ; Cladomyrma Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32992 ER - TY - JOUR A1 - Lillien, Laura E. A1 - Sendtner, Michael A1 - Rohrer, Hermann A1 - Hughes, Simon M. A1 - Raff, Martin C. T1 - Type-2 Astrocyte Development in Rat Brain Cultures is initiated by a CNTF-like protein produced by type-1 astrocytes N2 - No abstract available Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31708 ER - TY - JOUR A1 - Schüssler, Ulrich A1 - Skinner, David N. B. A1 - Roland, Norbert W. T1 - Subduction-related Mafic to Intermediate Plutonism in the Northwestern Wilson Terrane, North Victoria Land and Oates Coast, Antarctica N2 - No abstract available KW - Wilson Terrane ; intrusions ; mafic composition ; relative age ; petrographic analysis ; gabbroic composition ; subduction zones Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31805 ER - TY - JOUR A1 - Schüssler, Ulrich T1 - Zur geologischen Situation der Erzlagerstätte Kupferberg-Neufang in der Umrahmung der Münchberger Gneismasse N2 - Die Kupfer-Zink-Lagerstätte von Kupferberg-Neufang im Bereich der Münchberger Deckenstruktur besteht aus einem etwa 4 km langen Zug einzelner stratiformer Vererzungslinsen, der in NW-SE-Richtung vom anchimetamorphen Paläozoikum "Bayerischer" Faziesentwicklung in die Prasinit-Phyllit-Serie hinüberzieht. Bisherige lagerstättenkundliche Untersuchimgen interpretierten die gesamte Lagerstätte als einheitliche, submarin-exhalativ entstandene stratiforme Bildung in Zusammenhang mit ordovizischem basischem Vulkanismus, der in den Rahmengesteinen der Lagerstätte durch die Diabase der anchimetamorphen Randschieferserie bzw. die Prasinite der Prasinit-Phyllit-Serie dokumentiert ist. Diese Vorstellung steht jedoch in deutlichem Widerspruch zu den Ergebnissen neuerer geochemischer und biostratigraphischer Untersuchungen, die für die Diabase und Prasinite eine völlig unterschiedliche Zusammensetzung ergaben und die zeigten, daß die Prasinit-Phyllit-Serie schon im Oberproterozoikum, die erzführenden Schichten im anchimetamorphen Paläozoikum aber erst im Unterdevon sedimentiert wurden. Für eine Klärung der Situation sind weitere Untersuchungen im Bereich der Lagerstätte erforderlich. Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31791 ER - TY - JOUR A1 - Kreuzer, Hans A1 - Seidel, Eberhard A1 - Schüssler, Ulrich A1 - Okrusch, Martin A1 - Lenz, Karl-Ludwig A1 - Raschka, Helmut T1 - K-Ar geochronology of different tectonic units at the northeastern margin of the Bohemian Massif N2 - No abstract available Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31811 ER - TY - JOUR A1 - Schüssler, Ulrich A1 - Richter, P. A1 - Okrusch, Martin T1 - Metabasites from the KTB Oberpfalz target area, Bavaria - geochemical characteristics and examples of mobile behaviour of "immobile" elements N2 - No abstract available Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31021 ER - TY - JOUR A1 - Schüssler, Ulrich A1 - Oppermann, Uwe A1 - Kreuzer, Hans A1 - Seidel, Eberhard A1 - Okrusch, Martin A1 - Lenz, Karl-Ludwig A1 - Raschka, Helmut T1 - Zur Altersstellung des ostbayerischen Kristallins - Ergebnisse neuer K-Ar Datierungen N2 - No abstract available Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31778 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - Ahmed Sefrioui: La boîte à merveilles. N2 - No abstract available Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-36766 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - Die Turnierkunst des Huon de Méry N2 - No abstract available Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-36753 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - Rezeptionsgeschichte und Trivialliteratur: Ein Leser der Nouvelle Héloise im Jahre 1838. N2 - No abstract available Y1 - 1977 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-36728 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - Der Roman als totales Spiel: Alain Robbe-Grillet, Topologie d'une cité fantôme. N2 - No abstract available Y1 - 1984 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-36889 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - Aimé Césaires Bearbeitungen von Une saison au Congo N2 - No abstract available Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-36837 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - Caliban als Dialektiker N2 - No abstract available Y1 - 1978 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-36850 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - A Johenne, ma dame et m'amie N2 - No abstract available Y1 - 1970 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-36735 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - Enanchet - "semplice compilatore"? N2 - No abstract available Y1 - 1970 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-36967 ER - TY - JOUR A1 - Pleticha-Geuder, Eva T1 - Die Drucke des Würzburger "Kreises der Jüngeren" N2 - No abstract available KW - Würzburg KW - Kreis der Jüngeren KW - Bibliographie Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-36296 ER - TY - JOUR A1 - Pleticha-Geuder, Eva T1 - Ex Bibliotheca Monasterii Neustatt ad Moenum. Zur Geschichte der Bibliothek von Kloster Neustadt am Main bis zur Säkularisation. N2 - No abstract available KW - Würzburg / Universitätsbibliothek KW - Adelsbibliothek KW - Ausstellung KW - Würzburg <1988> KW - Bronnbach / Kloster / Bibliothek KW - Kleinheubach KW - Neustadt
Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35469 ER - TY - JOUR A1 - Pleticha-Geuder, Eva T1 - Erläuterungen zu den Miniaturen der Handschrift N2 - Die Fries-Chronik des Fürstbischofs Julius Echter von Mespelbrunn : eine fränkische Prachthandschrift des 16. Jahrhunderts aus dem Bestand der Universitätsbibliothek Würzburg Codex M.ch. f.760 ; [Ausstellung zur 500. Wiederkehr des Geburtstages von Magister Lorenz Fries (1489 - 1550), 19. Oktober - 3. Dezember 1989, Universitätsbibliothek Würzburg] KW - Fries KW - Lorenz / Würzburger Bischofschronik / Handschrift / Würzburg / Universitätsbibliothek / Ausstellung Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35451 ER - TY - JOUR A1 - Daut, Volker T1 - Die Entwicklung der Todesvorstellung bei Kindern und Jugendlichen N2 - No abstract available Y1 - 1980 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-36069 ER - TY - JOUR A1 - Heuer, D. A1 - Reusch, Wolfgang T1 - Das belastete Potentiometer - Ein Beispiel für Abschätzungen N2 - No abstract available Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30634 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - Sirène en (n)ixe. Mytheninversion in Mallarmés Sonett 'A la nue accablante' N2 - No abstract available Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33863 ER - TY - JOUR A1 - Dunkel, Franz G. A1 - Hildel, Werner A1 - Rességuier, Peter T1 - Hieracium fallax Willd. und weitere Hieracium echioides-Zwischenarten im nordwestlichen Bayern T1 - Occurence of Hieracium fallax and other intermediate species of the section Echinina (Nägeli & Peter) Zahn in northwestern Bavaria N2 - Die Grenze des riesigen eurasiatisch-kontinentalen Areals von Hieracium echioides Lumn. verläuft durch Mitteldeutschland, Zwischenarten aus der Hieracium echioides-Verwandtschaft (sect. Echinina) dringen westlich bis in die Oberrheinebene vor, sind aber im übrigen Süden und Südosten Deutschlands sehr selten oder fehlen. In den letzten Jahren wurden im Nordwesten Bayerns neue Wuchsorte von Hieracium auriculoides Láng (MTB 5526.31, 5924.44, 6125.13, 6223.22), H. calodon Tausch ex Peter (6123.21, 6125.13) und H. fallax Willd. (6223.21) nachgewiesen. Dies stellt den zweiten aktuellen Nachweis von H. fallax in Bayern dar, bemerkenswert ist ein Nachweis von H. auriculoides in der Rhön in ca. 700 m Meereshöhe. N2 - The huge geographic area of H. echioides centers in Eastern Europe and Western Asia and extends to Middle Germany, intermediate species (Zwischenarten) of H. echioides reach further western parts of Germany in the Upper Rhine valley. These species occur very rarely in the southern and south eastern parts of Germany, they are lacking in wide parts of southern Bavaria. At Lower Francony, the north western part of Bavaria some populations of Hieracium auriculoides (MTB 5526.31, 5924.44, 6125.13, 6223.22), H. calodon (6123.21, 6125.13) and H. fallax (6223.21) were detected. The finding of H. fallax represents the second actual one in Bavaria. The occurence of H. auriculoides at 700 m above sea level should be mentioned. KW - Habichtskraut KW - Unterfranken KW - Hieracium auriculoides KW - calodon KW - euchaetium KW - fallax KW - Lower Francony KW - Echinina Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35337 ER - TY - JOUR A1 - Ewald, Jörg T1 - Ein pflanzensoziologisches Modell der Schattentoleranz von Baumarten in den Bayerischen Alpen T1 - A Phytosociological Model of Shade Tolerance of Tree Species in the Bavarian Alps N2 - The ecological niche, as a summary of the environment in which a tree species can live, is a central concept in vegetation ecology and its application in silviculture. While the fundamental niche focusses on the physiological constraints of survival and growth, the realised niche takes competition in real communities into account. To understand realised niches in a causal fashion requires knowledge of the life cycle of plant species. The concept of regeneration niche is based on the notion that establishment and juvenile growth are particularly sensitive stages. Obviously, silviculturalists must be particularly interested in regeneration niches. The database BERGWALD contains 4,934 phytosociological plots from mountain forests and related vegetation types of the Bavarian Alps. The detailed information on plant species composition (trees, tree regeneration, shrubs, herbs and bryophytes) and cover has so far been used extensively for deriving vegetation units, site types and groups of indicator species. In the present study the database content was analysed with regard to the ecology of tree species in general and their regeneration niche in particular. The availability of light as a crucial resource that changes during forest succession was estimated by calculating average Ellenberg indicator values (mL) based on total field and bryophyte layer composition. The relative frequency of plots across the mL gradient in the total database was juxtaposed to the occurrence of the 16 most common tree species in the tree and in the regeneration layer, respectively. [...] As expected, the realised niches of tree species on the light gradient corresponded broadly to Ellenberg's L-value of tree regeneration. As the regional climax, Abies alba and Fagus sylvatica have coincident optima of tree layer and juvenile occurrences in closed, mature stands. Ulmus glabra and Fraxinus excelsior, as species of lower altitude, exhibit niches most similar to these climax species, followed by Acer pseudoplatanus and Picea abies, two of the most frequent species, that occur from low elevations to the timber line. The intermediate role of these four species is confirmed, as regeneration occurs mostly at light levels higher than those found under adult trees of the same species. Against expectations, Taxus baccata clearly prefers stands with moderate to high light, as do Sorbus aria, Sorbus aucuparia and Alnus incana. While Larix decidua and Pinus cembra occupy very similar overall niches, tree layer and regeneration niches of Larix differ markedly, whereas coincident layer niches in Pinus cembra underpin its status as a climax species at tree line. Pinus sylvestris and Salix eleagnos are typical shade-intolerant pioneers, of which regeneration is practically restricted to non-forest vegetation. Pinus rotundata and Juniperus communis are small trees that are entirely restricted to open stands subject to geomorphological activity. The results demonstrate the potential of phytosociological databases for studying the niches of tree species. To be sure, such analyses are no replacement for physiological and experimental studies. The research community is invited to use this source as a reference framework and an empirical validation for more specialised research. KW - Baumart KW - Bayerische Alpen KW - Ellenberg indicator value for light KW - Niche model KW - Phytosociological database KW - Regeneration niche Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35345 ER - TY - JOUR A1 - Meierott, Lenz T1 - Cerastium brachypetalum Desp. ex Pers. und Cerastium tenoreanum Ser. (Caryophyllaceae) in Franken T1 - Cerastium brachypetalum Desp. ex Pers. and Cerastium tenoreanum Ser. (Caryophyllaceae) in Franconia, Southern Germany N2 - Für Cerastium tenoreanum Ser. und die Varietäten von Cerastium brachypetalum Desp. ex Pers. werden ihre korrekte Nomenklatur, ihre Unterscheidungsmerkmale und ihre Verbreitung in Süddeutschland und Franken mitgeteilt. Die gegenwärtige Ausbreitungstendenz annueller Cerastien wird diskutiert. N2 - The present communication on Cerastium tenoreanum Ser. and the varieties of Cerastium brachypetalum Desp. ex Pers. deals with nomenclature and diagnostic features of these taxa and their distribution pattern in Southern Germany. Factors influencing the recent distributional expansion of annual Cerastia are discussed. KW - Hornkraut KW - Nelkengewächse KW - Franken KW - Cerastium brachypetalum KW - Cerastium tenoreanum KW - Caryophyllaceae KW - Franconia Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35354 ER - TY - JOUR A1 - Gottschlich, Günter A1 - Drenckhahn, Detlev T1 - Iconography of the Genus Hieracium in central Europe - Part 1: General Description and Morphotypes N2 - The genus Hieracium comprises more than one thousand sexual and apomictic species in Europe, with numerous intermediates and microspecies. Only a small fraction of the members of the genus Hieracium has been illustrated or photo-documented in the literature. Since many of these publications are difficult to obtain, only a few specialists are familiar with most of the species and subspecies described in the literature. In order to overcome this problem and encourage geobotanical research on the genus Hieracium, we decided to edit an iconography of central and southern European Hieracia in an electronical journal (Forum geobotanicum) with free international access through the internet. Part I of this endeavour contains descriptions and photographs of the morphological spectrum of the genus Hieracium. Here, we categorize the genus into 15 basic morphotypes. These types conform partly to the sections and subsections of the genus Hieracium, but are in some cases informal and may even include members of different sections. Classification of morphotypes is considered helpful to obtain a first rough picture of an unknown species that then can be traced to the species and subspecies level by using keys or, after completion of this iconography, simply by screening the relevant images. One particularly novel aspect of the present endeavour will be the regular inclusion of magnified images and scanning electron micrographs. KW - Habichtskraut KW - Hieracium KW - iconography KW - classification KW - scanning electron micrographs Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35363 ER - TY - JOUR A1 - Dunkel, Franz G. T1 - Zur Kenntnis des Ranunculus auricomus-Komplexes in Deutschland: Ranunculus suborbicularis spec. nova T1 - The Ranunculus auricomus complex in Germany: Ranunculus suborbicularis spec. nova N2 - Die bei Schwarz (1949) als R. vertumnalis abgebildeten Pflanzen entsprechen nicht dem Typusmaterial, sondern weichen durch fast kreisförmige Blattspreiten der Schlussblätter und geringe Blattteilung ab. Sie werden hier als R. suborbicularis spec. nov. beschrieben und mit ihrem Blattzyklus und weiteren Belegen abgebildet. Die bekannte Verbreitung erstreckt sich auf Berlin (wohl erloschen), Thüringen und Bayern. Insgesamt ist aufgrund der kleinen Zahl der Populationen eine starke Gefährdung anzunehmen. N2 - In 1949 O. Schwarz published an article on thuringian species of the Ranunculus auricomus complex illustrated with several pictures of the species. However, figure 2, purported to represent Ranunculus vertumnalis, does not correspond with the type material. The specimen depicted in figure 2 of Schwarz (1949) showed almost circular later leaves and lacked the main incisures and, therefore, is described here as R. suborbicularis spec. nov. Details of leaf cycle, cauline leaves and other features are presented. The known distribution includes Thuringia, Bavaria and Berlin (obviously extinct). Due to a restricted number of populations R. suborbicularis is considered to be endangered. KW - Gold-Hahnenfuß KW - Thüringen KW - Bayern KW - Berlin KW - Ranunculus suborbicularis KW - Ranunculus auricomus KW - Ranunculus vertumnalis Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35377 ER - TY - JOUR A1 - Rostanski, Krzysztof A1 - Meierott, Lenz T1 - Zur Gattung Oenothera L. in Franken - mit besonderer Berücksichtigung von Oenothera stucchii Soldano (neu für Deutschland) T1 - The Genus Oenothera in Franconia - with special reference to Oenothera stucchii Soldano (new for Germany) N2 - In August 2004 the authors of this report undertook a survey on the Genus Oenothera (evening-primroses) in the valley of the river Main between the cities of Schweinfurt and Bamberg (Bavaria, Lower and Upper Franconia). 22 different taxa were identified, most of which are new to Bavaria, one new for Europe (Oenothera hazelae Gates) and another one new for Middle Europe (Oenothera stucchii Soldano). In this report a list of all Oenothera species found in Franconia is given and Oenothera stucchii, a particular tall (up to > 2 m) species with extremely long Hypanthia of 50-70 mm and fruit capsules with truncated teeth, is described and depicted in more detail. KW - Nachtkerze KW - Franken KW - Oenothera KW - Oenothera stucchii KW - Bavaria KW - Franconia Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35388 ER - TY - JOUR A1 - Röder, Daniela A1 - Jeschke, Michael A1 - Kiehl, Kathrin T1 - Vegetation und Böden alter und junger Kalkmagerrasen im Naturschutzgebiet "Garchinger Heide" im Norden von München T1 - Vegetation and soils of ancient and young calcareous grasslands in the nature reserve "Garchinger Heide" N2 - Das Naturschutzgebiet "Garchinger Heide" ist ein Relikt der ehemals ausgedehnten Kalkmagerrasen auf Pararendzinen über Niederterrassenschotter im Alpenvorland. Bei jahrhundertelanger extensiver Landnutzung hat sich auf trockenen nährstoffarmen Böden eine artenreiche Vegetation mit zahlreichen seltenen und gefährdeten Arten entwickelt. Die "Altheide", welche den größten Teil des Naturschutzgebiets einnimmt, ist geprägt durch flachgründige, nährstoffarme Böden, welche eine geschlossene Vegetation mit einem hohen Anteil an Arten der Halbtrockenrasen (hauptsächlich Mesobromion erecti und Cirsio-Brachypodion) tragen. Das 1945 durch Oberbodenabtrag begonnene, aber nicht mehr ausgebaute und verwendete „Rollfeld“ weist einen niedrigen Feinbodenanteil, welcher auf eine geringe Wasserverfügbarkeit schließen lässt, sowie niedrige Gehalte an Gesamtstickstoff und CAL-austauschbaren P2O5 auf. Die Vegetation ist lückig mit einem hohen Anteil an Trockenrasenarten (Xerobromion, Sedo-Scleranthetea, Sesleritalia albicantis). Das heutige Vorkommen zahlreicher Arten, welche in früheren Untersuchungen (1956 und 1986) nicht gefunden wurden, lässt auf eine fortschreitende Sukzession der Vegetation des Rollfeldes hin zu der der Altheide schließen. Der 1959 zum Naturschutzgebiet hinzu gekaufte ehemalige Acker unterscheidet sich immer noch deutlich von der Altheide. Eine allmähliche Annäherung der Standortbedingungen ist jedoch zu beobachten. So sanken die Gehalte an CAL-austauschbarem P_ 2 O_5 und K_2 O im Vergleich zu Werten aus dem Jahr 1993 deutlich ab. Trotz des immer noch hohen Anteils an Grünlandarten (Molinio-Arrhenatheretea) konnten sich im Vergleich zu 1986 mehr Magerrasenarten etablieren. N2 - The nature reserve "Garchinger Heide" north of Munich (Bavaria, Germany) is a remnant of the formerly widespread calcareous grasslands of the Munich Gravel Plain on dry, nutrient-poor calcaric Regosol soils with low water-storage capacity. Most of the nature reserve is covered by species-rich ancient grasslands with a high proportion of species of the Mesobromion erecti and Cirsio-Brachypodion. At the “Rollfeld”, where topsoil was removed in 1945, vegetation cover is lower and the proportion of species of the Xerobromion, Sedo-Scleranthetea and Seslerietalia albicantis is higher than on the ancient grasslands due to low water-availability and low nutrient contents. In 2003, the number of ancient grassland species, which have successfully established on the topsoil-removal site, was higher than in vegetation descriptions from 1956 and 1986. On an ex-arable field within the nature reserve, which was last ploughed in 1959, several species of the Molinio-Arrhenatheretea were still found in 2003. In comparison to 1986, however, the number of species of the Mesobromion erecti and Cirsio-Brachypodion was higher and the vegetation has become more similar to the ancient grassland vegetation. This positive development was also reflected in the soil analyses; the contents of exchangeable P_2 O_5 and K_2 O in the soil of the ex-arable field have decreased considerably during the last 12 years. KW - Vegetation KW - Festuco-Brometea KW - Boden KW - Garchinger Heide KW - calcareous grassland KW - topsoil removal KW - ex-arable field KW - vegetation KW - soil nutrients Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35397 ER - TY - JOUR A1 - Argos, P. A1 - Dandekar, Thomas T1 - Delineating the main chain topology of four-helix bundle proteins using the genetic algorithm and knowledge based on the amino acid sequence alone N2 - No abstract available KW - Proteine KW - Strukturanalyse KW - Abstandsmessung Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33807 ER - TY - JOUR A1 - Hübner, Stefanie A1 - Wissemann, Volker T1 - Morphometrische Analysen zur Variabilität von Prunus spinosa L. - Populationen(Prunoideae, Rosaceae) im mittleren Saaletal, Thüringen T1 - Morphometric analysis on the variability of Prunus spinosa L. - populations(Prunoideae, Rosaceae) in the central valley of the river Saale, Thuringia N2 - Prunus spinosa L. (Rosaceae) is one of the most widespread members of the genus Prunus in middle europe. Its morphological plasticity resulted in a number of described taxa at subspecific level. Since the early neolithic times, drupes of the plum family are recorded and exhibit already a remarkable diversity in size and form. Here we present a short historical account to the use of P. spinosa and an overview of the different taxonomic treatments. We examined distribution patterns in general and in particular in the central valley of the river Saale (Thuringia) with respect to ecological, edaphic and climatic factors. We assessed within 16 populations the variability of 22 metric and 10 qualitative morphological characters at 7 different locations. Population sites included forest-, way- and fieldsides, as well as lightish pine forests. Pollen fertility did not increase during the flowering period, all flowers were directly fully fertile from the beginning. In contrast, glucose content varied significantly depending of the status of fertilization. Epicuticular wax structure was without variation amongst the populations. P. spinosa leaves are covered with a smooth layer of slightly striated wax. Morphological characters were scored on 270 branches and 506 fruits. Most of the characters showed enormous variability among and within populations such as metrics of leaves, thorns and character states of flower morphology. The lowest variability among populations and therefore not dependend of modificatory factors was found in fruit characters. Since kernel morphology seems to be genetically rather than modificatory controlled, we applied the 3 taxonomical concepts of Werneck, Kühn and Scholz u. Scholz to identify evolutionary units at subspecific levels. However, population variability was still so high, that from our study here we can not support an infraspecific classification of Prunus spinosa L. KW - Prunus KW - Rosengewächse KW - Systematik KW - Rosaceae KW - Prunus KW - Evolution KW - Morphology KW - Systematics Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35207 ER - TY - JOUR A1 - Ewald, Jörg T1 - Ökologie der Weißtanne (Abies alba Mill.) im bayerischen Alpenraum T1 - Ecology of silver fir (Abies alba Mill.) in the Bavarian Alps N2 - Based on queries of the phytosociological databank BERGWALD, a compilation of 3.504 forest vegetation plots from the Bavarian Alps, the ecological niche of Abies alba is re-assessed. The tree species occurs mostly admixed in mountain forests with Fagus and Picea rather than forming distinctive communities of its own. Climatically, Abies is widely distributed to the upper limit of the montane belt, but occurs only sparsely in subalpine forest. Analysis of Ellenberg indicator values based on total species composition yielded the following results: As a tolerant species Abies regeneration has a marked preference for shady forest, which in turn Abies tree layers themselves help create. It also has a clear preference for acidic topsoil conditions. Sites with low N-supply, such as early successional stages on raw carbonate soils, are rarely colonised by Abies. Also, dry and markedly wet forest sites in the region are avoided by Abies. Permutation-based indicator species analysis found a large number of common forest species as being significantly associated with Abies and its frequent companion Fagus sylvatica, whereas there is a negative relationship with more specialised Seslerion and Erico-Pinion species. As Abies alba has very few specific companion species not shared with either Fagus or Picea, the delimitation of Abietetum-syntaxa appears mostly motivated by ecological rather than phytosociological considerations. As a result of its susceptibility towards game browsing, Abies regeneration is an indicator of high woody species richness. The study broadly confirms Abies alba's status as a climax species intermediate between Fagus and Picea, and demonstrates the potential of large phytosociological databanks for niche modelling. KW - Weißtanne KW - Ökologie KW - Bayern KW - Ellenberg indicator values ; Mixed mountain forest ; Niche model ; Phytosociological databank Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35193 ER - TY - JOUR A1 - Rostás, Michael T1 - The effects of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one on two species of Spodoptera and the growth of Setosphaeria turcica in vitro N2 - Maize seedlings contain high amounts of glucosidically bound 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA). The effects of DIMBOA on the feeding behaviour and performance of two noctuids, Spodoptera exigua Hübner and S. frugiperda Smith, were compared. The question was raised whether S. frugiperda, preferring maize and other Poaceae, is better adapted to DIMBOA than S. exigua. In addition, the effects of DIMBOA on the mycelial growth of the plant pathogen Setosphaeria turcica Leonard et Suggs (causal agent of northern corn leaf blight) was assessed in vitro. DIMBOA had an antifeedant effect on S. exigua but stimulated feeding in S. frugiperda in dual-choice experiments. In a no-choice setup, larvae of S. exigua gained less biomass and had a prolonged development when feeding on an artificial diet containing DIMBOA. However, pupal weight was not significantly different between treatments. In contrast, larvae of S. frugiperda were not affected by DIMBOA. Strong detrimental effects of DIMBOA were found on the mycelial growth of the pathogen S. turcica. KW - Eulen KW - Pilzbefall KW - Mais KW - DIMBOA KW - Abwehr KW - DIMBOA KW - Performance KW - Spodoptera KW - Fungus KW - Zea mays Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-35079 ER - TY - JOUR A1 - Drenckhahn, Detlev T1 - Neue und wieder entdeckte Hieracien auf Rügen T1 - New taxa and rediscovered hawkweeds on the island of Rügen, Germany N2 - The island of Rügen (Rugia), located in the Baltic sea, is the most northeastern (NE) part of Germany. Due to its particular geographic position at the border between scandinavian, middle european and continental european floral elements, Rügen harbours several hawkweed species (Hieracia) of the scandinavian area such as Hieracium fuscocinererum, H. subramosum, H. subrigidum and H. diaphanoides subsp. neoornatum and, at the same time, is the most northwestern location of H. echioides. Two endemic Hieracium species have been identified recently, i. e. H. muorum subsp. rugianum and H. caesium subsp. zabelianum (Gottschlich et al. 1998, Bot. Rundbr. Mecklenburg-Vorpommern 31:1-94). In the present communication, two further novel endemic Hieracium taxa will be described, which are restricted to the chalk cliffs of Cape Arkona and Jasmund, i. e. H. swantevitii and H. lachenalii subsp. litocretaceum. H. swantevitii (Swantevit’s hawkweed) is intermediate between H. caesium/H. bifidum and H. lachenalii with hairy, modestly glandular involucre and slightly serrated elongated leaves . This view of an intermediate position of H. swantevitii between these species was further supported by the ultrastructure of epidermal papillae of the outer bracts of the involucre visualized by scanning electron microscopy. H. lachenalii subsp. litocretaceum (chalk cliff hawkweed) is characterized by its narrow anguste to almost linear denticulate leaves in combination with mode rately glandular heads. In addition to the description of these two new hawkweed taxa , the rediscovery of three further species will be reported for Rügen, i. e. H. echioides (W. Gager in SE Rügen), H. cymosum subsp. cymosum (close to Göhren in SE Rügen) and H. subrigidum E Glowe in N Rügen. The locality of H. echioides appears to be most north-western site in middle Europe, the locality of H. cymosum is one of the last growth sites in the northern German lowlands and H. subrigidum (so far only known as a single herbarium specimen, collected 1858 in Rügen) has so far not been recorded in other localities of middle Europe. KW - Habichtskraut KW - Hieracium swantevitii KW - Hieracium lachenalii subsp. litocretaceum KW - Hieracium subrigidum KW - Hieracium cymosum KW - Hieracium echioides KW - Scanning electron microscopy KW - Epidermal papillae Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34843 ER - TY - JOUR A1 - Wu, Y. S. A1 - Becker, Charles R. A1 - Waag, A. A1 - Bicknell-Tassius, R. N. A1 - Landwehr, G. T1 - The effects of laser illumination and high energy electrons on molecular-beam epitaxial growth of CdTe N2 - We report the results of a detailed investigation on the Te-stabilized (2 x 1) and the Cdstabilized c( 2 X 2) surfaces of ( 100) CdTe substrates. The investigation demonstrates for the first time that both laser illumination and, to a greater extent, high-energy electron irradiation increase the Te desorption and reduce the Cd desorption from ( 100) CdTe surfaces. Thus it is possible by choosing the proper growth temperature and photon or electron fluxes to change the surface reconstruction from the normally Te-stabilized to a Cd-stabilized phase. Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30795 ER - TY - JOUR A1 - Kleinschmidt, Jürgen A. A1 - Scheer, Ulrich A1 - Dabauvalle, Marie-Christine A1 - Bustin, Michael A1 - Franke, Werner W. T1 - High mobility group proteins of amphibian oocytes: a large storage pool of a soluble high mobility group-1-like protein and involvement in transcriptional events N2 - No abstract available Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33250 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - Nouvelle critique und Strukturalismus N2 - No abstract available KW - Romanische Sprachen KW - Literatur KW - Geschichte Y1 - 1976 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32324 SN - 3-87452-263-6 ER - TY - JOUR A1 - Ruhe, Ernstpeter T1 - Centre vide, cadre plein: les Romanesques d'Alain Robbe-Grillet N2 - No abstract available KW - Autobiographie ; Robbe-Grillet KW - Alain ; Boudjedra KW - Rachid ; Doubrovsky KW - Serge ; Avantgardeliteratur ; Geschichte 1976-1991 ; Kongress ; Mainz <1990> Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30524 SN - 3-8233-4120-0 ER - TY - JOUR A1 - Grafe, T. Ulmar A1 - Schmuck, Richard A1 - Linsenmair, Karl Eduard T1 - Reproductive energetics of the African Reed Frogs, Hyperolius viridiflavus and Hyperolius marmoratus N2 - No abstract available Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31187 ER - TY - JOUR A1 - Linsenmair, Karl Eduard T1 - Biologische Vielfalt und ökologische Stabilität N2 - No abstract available Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31157 ER - TY - JOUR A1 - Plakhutin, B. N. A1 - Arbuznikov, Alexei V. T1 - Equations for determination of vector coupling coefficients in systems with two open shells. Ions of transition metals with p\(^M\)d\(^N\) configuration N2 - No abstract available Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30746 ER - TY - JOUR A1 - Plakhutin, B. N. A1 - Arbuznikov, Alexei V. A1 - Trofimov, A. B. T1 - Coupling coefficients for systems with two open electronic shells: transition metal ions with p\(^M\)d\(^N\) configuration N2 - No abstract available Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30736 ER - TY - JOUR A1 - Plakhutin, B. N. A1 - Zhidomirov, G. M. A1 - Arbuznikov, Alexei V. T1 - Vector coupling coefficients for calculations of transition-metal atoms and ions by the SCF coupling operator method N2 - No abstract available Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30702 ER - TY - JOUR A1 - Moll, Heidrun A1 - Röllinghoff, Martin T1 - T-cell reactivity to purified lipophosphoglycan from Leishmania major: A model for analysis of the cellular immune response to microbial carbohydrates. N2 - The major macromolecule on the surface o/Leishmania majorpromastigotes is a lipophosphoglycan (LPG). This glycoconjugate plays a key role in determining infectivity and survival of para-sites in the mammalian host cell. In addition, L. major LPG is able to induce a host-protective immune response. In this article, we summarise the evidence for recognition of highly purified LPG by T cells and we discuss the potential mechanisms of T-cell Stimulation by this non-protein antigen. KW - Leishmania KW - T lymphocytes KW - glycosyl phosphatidyl-inostitols. Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33022 ER - TY - JOUR A1 - Tiu, W. U. A1 - Davern, K. M. A1 - Garcia, E. G. A1 - Moll, Heidrun A1 - Mitchell, Graham F. T1 - Monoclonal antibodies reacting with Schistosoma japonicum eggs and their target epitopes N2 - Ten monoclonal antibodies (McAbs) raised to Schistosoma japonicum eggs could be assigned using several serological and immunochemical techniques to 3 groups. The McAbs, termed A, B and C-McAbs, apparently recognize carbohydrate epitopes that can be located on the same antigen molecule. The antibodies, generally of IgM isotype, are idiotypically related. They are distinct from another IgM McAb (Group D-McAb) the carbohydrate target epitope of which can also be associated with the epitopes of A. B and C-McAbs. The McAbs produce large vacuolated bleb reactions in the circumoval precipitin test (COPT) and target epitopes have different representations in various life cycle stages such as immature and mature eggs, male and female worms (including S. mansoni). Antigens affinity purified on columns containing A, B, C and D-McAbs stimulate proliferation of T cells from egg-sensitized mice and elicit DTH reactions in such mice. This raises the possibility that the target antigens of these carbohydrate-reactive monoclonal antibodies are immunopathologic and involved in egg-induced granuloma formation. KW - Schistosoma japonicum; Egg antigen; Carbohydrate epitope; Circumoval precipitin test; Immunoassay Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30916 ER - TY - JOUR A1 - Solbach, W. A1 - Bogdan, C. A1 - Moll, Heidrun A1 - Lohoff, M. A1 - Röllinghoff, M. T1 - Parasitäre Evasionsmechanismen: Beispiel Leishmanien T1 - Mechanisms of Parasite Evasion: Leishmania as an Example N2 - Leishmanien besitzen eine Vielzahl von Mechanismen, die humorale und zelluläre Immunabwehr effektiv zu unterlaufen. Diese hängen eng mit der Expression von hauptsächlich zwei Glykokonjugaten auf der Parasitenoberfläche zusammen, dem gp63 und dem Lipophosphoglykan. Die Parasiten sind einerseits schlechte Aktivatoren des alternativen Komplementweges und umgehen damit ihre eigene extrazelluläre Lyse. Oberflächengebundene Komplementfaktoren fördern andererseits die Aufnahme der Leishmanien durch Makrophagen. Solange diese nicht durch T-Zellen aktiviert sind, dienen sie den Parasiten als "Refugium". Dies gilt insbesondere, als Leishmanien in der Lage sind, 1. den "oxidative burst" zu hemmen; 2. toxische Sauerstoffmetaboliten zu entgiften; 3. abbauende lysosomale Enzyme zu hemmen und 4. das saure Milieu in den Lysosomen für ihren eigenen Metabolismus auszunutzen. Schließlich unterlaufen Leishmanien die zelluläre Immunabwehr des Wirts, indem sie die Aktivierung von T-Lymphozyten hemmen und die Expansion von T-Zell-Sub-populationen bewirken, die für ihr eigenes Überleben nützlich sind. N2 - Leishmania display a variety of mechanisms for effective evasion of the humoral and cellular immune responses of the host which are strongly associ-ated with the expression of two major surface glycoconjugates, gp63 and lipophosphoglycan. The parasites are poor activators of the alternative com-plement pathway thus avoiding their own extracellular lysis. Complement bound on the surface of promastigotes promotes the uptake of leishmania by macrophages which function as »safe targets« as long as they are not acti-vated by T lymphocytes. This is due to the fact that intracellular parasites are able to 1. decrease the oxidative burst; 2. scavenge toxic oxygen metabolites; 3. inhibit degradative lysosomal enzymes; 4. exploit the acidic milieu of lysosomes for their own metabolism. Finally, leishmania have been shown to evade the host's cellular immune response by down-regulating T cell-activat-ing processes and by initiating the expansion of T cell subpopulations which promote their own survival. KW - Leishmanien KW - Immunsystem KW - Evasionsmechanismen KW - Makrophagen KW - T-Zellen KW - leishmania KW - immune System KW - evasion mechanisms KW - macrophages KW - T cells Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30920 ER - TY - JOUR A1 - Moll, Heidrun A1 - Mitchell, Graham F. T1 - Analysis of variables associated with the promotion of resistance, and its abrogation, in T cell-reconstituted nude mice infected with Leishmania major N2 - No abstract available Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30949 ER - TY - JOUR A1 - Kobelt, Frank A1 - Linsenmair, Karl Eduard T1 - Adaptations of the reed frog Hyperolius viridiflavus to its arid environment. I. The skin of Hyperolius viridiflavus nitidulus in wet and dry season conditions. N2 - Hyperolius viridiflavus nitidulus inhabits parts of the seasonally very hot and dry West African savanna. During the long lasting dry season, the small frog is sitting unhidden on mostly dry plants and has to deal with high solar radiation load (SRL), evaporative water loss (EWL) and small energy reserves. It seems to be very badly equipped to survive such harsh climatic conditions (unfavorable surface to volume ratio, very limited capacity to störe energy and water). Therefore, it must have developed extraordinary efficient mechanisms to solve the mentioned Problems. Some of these mechanisms are to be looked for within the skin of the animal (e.g. protection against fast desiccation, deleterious effects of UV radiation and over-heating). The morphology of the wet season skin is, in most aspects, that of a "normal" anuran skin. It differs in the Organization of the processes of the melanophores and in the arrangement of the chromatophores in the Stratum spongiosum, forming no "Dermal Chromatophore Unit". During the adaptation to dry season conditions the number of iridophores in dorsal and ventral skin is increased 4-6 times compared to wet season skin. This increase is accompanied by a very conspicuous change of the wet season color pattern. Now, at air temperatures below 35° C the color becomes brownish white or grey and changes to a brilliant white at air temperatures near and over 40° C. Thus, in dry season State the frog retains its ability for rapid color change. In wet season State the platelets of the iridophores are irregularly distributed. In dry season State many platelets become arranged almost parallel to the surface. These purine crystals probably act as quarter-wave-length interference reflectors, reducing SRL by reflecting a considerable amount of the radiated energy input. EWL is as low as that of much larger xeric reptilians. The impermeability of the skin seems to be the result of several mechanisms (ground substance, iridophores, lipids, mucus) supplementing each other. The light red skin at the pelvic region and inner sides of the limbs is specialized for rapid uptake of water allowing the frog to replenish the unavoidable EWL by using single drops of dew or rain, available for only very short periods. Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30551 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Trendelenburg, Michael F. A1 - Franke, Werner W. T1 - Regulation of transcription of genes of ribosomal RNA during amphibian oogenesis: a biochemical and morphological study N2 - Natural changes in the transcription of rRNA genes were studied in nucleoli from three oogenic stages of the newt Triturus alpestris with electron microscope, autoradiographic, and biochemical techniques. From determinations of the uridine triphosphate pool sizes and [3H]uridine uptake, phosphorylation, and incorporation into 28S and 18S rRNAs in vivo it was estimated that the rate of rRNA synthesis was about 0.01% in previtellogenic oocytes and 13% in mature oocytes when compared to midvitellogenesis. Spread preparations of nucleoli showed significant morphological changes in the transcriptional complexes. The total number of lateral fibrils, i.e., ribonucleoproteins containing the nascent rRNA precursor, were drastically decreased in stages of reduced synthetic activity. This indicates that rRNA synthesis is regulated primarily at the level of transcription. The resulting patterns of fibril coverage of the nucleolar chromatin axes revealed a marked heterogeneity. On the same nucleolar axis occurred matrix units that were completely devoid of lateral fibrils, matrix units that were almost fully covered with lateral fibrils, and various forms of matrix units with a range of lateral fibril densities intermediate between the two extremes. Granular particles that were tentatively identified as RNA polymerase molecules were not restricted to the transcription l complexes. They were observed, although less regularly and separated by greater distances, in untranscribed spacer regions as well as in untranscribed gene intercepts. The results show that the pattern of transcriptional control of rRNA genes differs widely in different genes, even in the same genetic unit. Y1 - 1976 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32814 ER - TY - JOUR A1 - Gorboulev, Valentin G. A1 - Axelrod, Vladimir D. A1 - Bayev, Alexander A. T1 - Primary structure of baker's yeast valine tRNA\(^{Val}_{2b}\) N2 - The minor form of vallne tBNA from baker's yeaat - tRNA\(^{Val}_{2b}\) - purified by column chromatography was completely digesteft with guanylo-BNase and pancreatic ENase. The products of these digestions were separated by a combination of thin-layer chromatography on cellulose and high voltage electrophoresis on DEAE-paper and then identified. The halves of tRNA Val 2b were prepared by partial digestion with pancreatic Mass and their complete guanylo-BNase and pancreatic ENase, digests were analysed. Basing on the obtained data the primary structure of baker1s yeast tRNA\(^{Val}_{2b}\) was reconstructed. Y1 - 1977 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32546 ER - TY - JOUR A1 - Dabauvalle, Marie-Christine A1 - Loos, Karin A1 - Merkert, Hilde A1 - Scheer, Ulrich T1 - Spontaneous assembly of pore complex-containing membranes ("Annulate lamellae") in Xenopus egg extract in the absence of chromatin N2 - No abstract available Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32797 ER - TY - JOUR A1 - Wilken, Norbert A1 - Kossner, Ursula A1 - Senécal, Jean-Luc A1 - Scheer, Ulrich A1 - Dabauvalle, Marie-Christine T1 - Nup180, a novel nuclear pore complex protein localizing to the cytoplasmic ring and associated fibrils N2 - No abstract available Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32049 ER -