TY  - JOUR
A1  - Röder, G.
A1  - Steinlein, C.
A1  - Schmid, M.
A1  - Linsenmair, Karl Eduard
T1  - Karyotype and chromosome banding in the Turkish desert woodlouse Desertellio elongatus (Crustacea, Isopoda, Oniscidea)
N2  - The karyotype of D. elongatus was investigated by means of C-banding, silver staining, and mithramycinand quinacrine fluorescent staining. The diploid chromosome number is 2n = 50. C-banding shows pericentromerically localized constitutive heterochromatin in every chromosome. Two of the chromosome pairs carry two telomeric nucleolus organizer regions each. No heteromorphic sex chromosomes were found.
KW  - Karyotype; chromosome banding; Desertellio elongatus; Crustacea; Isopoda; Oniscidea
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30989
ER  - 
TY  - JOUR
A1  - Linsenmair, Karl Eduard
T1  - Comparative studies on the social behaviour of the desert isopod Hemilepistus reaumuri and of a Porcellio species
N2  - Behavioural adaptations have made the desert isopod Hemilepistus reaumuri the most successful herbivore and detritivore of the macrofauna of many arid areas in North Africa and Asia Minor. For survival and reproduction Hemilepistus is dependent on burrows. New burrows can only be dug during spring. With the time-consuming digging of a burrow, Hemilepistus has only made the first step towards solving its ecological problems. The burrows are vital and have to be continuously defended against competitors. This requirement is met by co-operation of individuals within the framework of a highly developed social behaviour. In spring adults form monogamous pairs in which partners recognize each other individually and later form, with their progeny, strictly closed family communities. Hemilepistus is compared with a Porcellio' sp. which has developed, convergently, a social behaviour which resembles that of Hemilepistus in many respects, but differs essentially in some aspects, partly reflecting differences in ecological requirements. This and a few other Porcellio species demonstrate some possible steps in the evolution of the social behaviour of Hemilepistus. The female Hemilepistus is-in contrast to Porcellio sp. - semelparous and the selective advantages of monogamy in its environment are not difficult to recognize. This chapter discusses how this mating system could have evolved and especially why monogamous behaviour is also the best method for the Hemilepistus male to maximize its reproductive success. The cohesion of pairs and of family communities in Hemilepistus is based on a highly developed chemical communication system. Individual- and family-specific badges owe their specificity to genetically determined discriminating substances. The nature of the badges raises a series of questions: e.g. since alien badges release aggression, how do parents avoid cannibalizing their young? Similar problems arise from the fact that family badges are mixtures of chemical compounds of very low volatility with the consequence that they can only be transferred by direct contact and that during moulting all substances are lost which an individual does not produce itself. It is shown that in solving these problems inhibiting properties (presumably substances) and learning play a dominant role.
Y1  - 1984
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30846
ER  - 
TY  - JOUR
A1  - Linsenmair, Karl Eduard
T1  - Individual and family recognition in subsocial arthropods, in particular in the desert isopod Hemilepistus reaumuri
N2  - Individual recogmtlon in the non-eusocial arthropods is, according to our present knowledge, predominantly found in the frame of permanent or temporary monogamy. In some cases, e. g. in stomatopods and possibly other marine crustaceans too, individual recognition may serve to allow identification of (i) individuals within dominance hierarchies or (ii) neighbours in territorial species thus helping to avoid the repetition of unnecessary and costly fights. Kin recognition is experimentally proven only in some isopod species (genera Hemilepistus and Porcel/io) and in the primitive cockroach (termite?) Cryptocercus. The «signatures» or «discriminators» used in the arthropods are chemical. It is assumed that the identifying substances are mainly genetically determined and in this paper I shall discuss possible evolutionary origins. The main part of this account is devoted to the presentation of some aspects of the highly developed individual and kin identification and recognition system in the desert isopod Hemilepistus reaumuri - a pure monogamous species in which pairs together with their progeny form strictly exclusive family units. Amongst other things problems of (i) mate choice, (ii) learning to recognize a partner, (iii) avoiding the un adaptive familiarization with aliens are treated. Monogamy under present conditions is for both sexes the only suitable way of maximizing reproductive success; an extremely strong selection pressure must act against every attempt to abandon monogamy under the given ecological conditions. The family «badges» which are certainly always blends of different discriminator substances are extremely variable. This variability is mainly due to genetical differences and is not environmentally caused. It is to be expected that intra-family variabiliry exists in respect of the production of discriminator substances. Since the common badge of a family is the result of exchanging and mixing individual substances, and since the chemical nature of these discriminators requires direct body contacts in order to acquire those substances which an individual does not produce itself, problems must arise with molting. These difficulties do indeed exist and they are aggravated by the fact that individuals may produce substances which do not show up in the common family badge. An efficient learning capability on the one hand and the use of inhibiting properties of newly molted isopods help to solve these problems. In the final discussion three questions are posed and - partly at least - answered; (i) why are families so strictly exclusive, (ii) how many discriminator substances have to be produced to provide a variability allowing families to remain exclusive under extreme conditions of very high population densities, (iii) what is the structure of the family badge and what does an individual have to learn apart from the badge in order not to mistake a family member for an alien or vice versa.
Y1  - 1985
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33957
ER  - 
TY  - JOUR
A1  - Grafe, U.
A1  - Linsenmair, Karl Eduard
T1  - Protogynous sex change in the Reed Frog: Hyperolius viridiflavus
N2  - Observations on captive reed frogs Hyperolius viridijlavus ommatostictus showed that seven out of 24 females changed into males. Sex change occurred without any hormone treatment and resulted in completely functional males. The adaptive value is discussed in terms of maximizing life-time reproductive success. Hyperolius r. ommatostictus is the first amphibian known to show functional sex reversal.
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30990
ER  - 
TY  - JOUR
A1  - Schmuck, R.
A1  - Geise, W.
A1  - Linsenmair, Karl Eduard
T1  - Life cycle strategies and physiological adjustments of Reedfrog Tadpoles (Amphibia, Anura, Hyperoliidae) in relation to environmental conditions.
N2  - The relationship between different degrees of intraspecific crowding of reedfrog tadpoles and their physiological responses to a deterioration of the natal pond water quality was examined under laboratory conditions. Tadpoles that were reared at a lower density metamorphosed significantly earlier than those raised at a higher density. As density increases, the average body length at metamorphosis decreases. However, at low tadpole density, a significantly higher diversity of body size classes among freshly metamorphosed froglets was observed than under more crowded conditions. Mortality increased during metamorphic climax and was inversely correlated with the tadpole density. In ephemeral ponds, an accumulation of nitrogenous wastes from metabolic processes and/or a concentration by evaporation in prolonged rainless periods can pose a considerable chemical stress to reedfrog tadpoles. Hyperolius viridiflavus ommatostictus responded to an increasing ammonia concentration with an activity increase of the ornithine cycle (intensified urea synthesis). hi contrast, Hyperolius marmoratus taeniatus exhibited a strong tolerance against high ammonia levels. A deterioration of the natal pond water quality caused H. v. ommatostictus and H. v. nitidulus tadpoles to adjust to harsher climatic conditions at the time of metamorphosis. This physiological preadjustment enabled the froglets to start feeding and growing immediately after metamorphosis even at low air humidity and rare precipitation events. In contrast, froglets that were raised in daily refreshed water exhibited high mortality rates if subjected to identical conditions. As one possible indicator of the actual climatic conditions prevailing in the surrounding terrestrial habitat, fluctuations in the water ammonia level are discussed.
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31009
ER  - 
TY  - JOUR
A1  - Tacke, M.
A1  - Schuberth, W.
A1  - Becker, Charles R.
A1  - Haas, L. D.
T1  - The dielectric constant of PbTe at 4.2 K and \(\tilde ν\)=84.15 cm\(^{-1}\), 96.97 cm\(^{-1}\), 103.60 cm\(^{-1}\)
N2  - The dielectric constant of a PbTe epitaxial layer has been measured by surface wave spectroscopy using an optically pumped far-infrared laser and the technique of attenuated total reflection.
Y1  - 1982
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30821
ER  - 
TY  - JOUR
A1  - Geis, G.
A1  - Geick, R.
A1  - Becker, Charles R.
A1  - Wagner, V.
T1  - Antiferromagnetic resonance in CoO/NiO mixed crystals
N2  - We have studied the lowest magnetic excitation of Ni\(_{1-x}\)Co\(_x\)O mixed crystals for 0.94 \(\leq\) x \(\leq\) 1. Together with previous results for 0.02 \(\leq\) x \(\leq\) 0.07 and neutron data for x = 0.14 and x = 0.30, the results are discussed by means of a model, especially the variation of AFMR frequency and preferred spin direction with Co concentration x.
Y1  - 1977
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31239
ER  - 
TY  - JOUR
A1  - Becker, Charles R.
T1  - Impurity-induced absorption in or near the phonon gap of KI
N2  - In or near the phonon gap of KI a single weak line due to OW (OD\(^-\)) at 69.7 (69.3) cm\(^{-1}\) has been observed. A second and much stronger line at 94.1 cm\(^{-1}\) was shown not to be related to OH\(^-\), but instead is thought to be due to CO\(_3\).
Y1  - 1970
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30757
ER  - 
TY  - JOUR
A1  - Köhler, H.
A1  - Becker, Charles R.
T1  - Optically active lattice vibrations in Bi\(_2\)Se\(_3\)
N2  - The preparation of Bi2Sea single crystals with low free carrier densities allowed an investigation of the lattice vibrations to be carried out from the reflectivity of cleavage planes at nearly normal incidence of the radiation (E ~ c). The experimental results ean be explained with two classical oscillators, whose eigenfrequencies oceur at 92 and 69.5 cm-I. The static dielectric constant was determined to be 100 ± 10 for E ~ c.
N2  - Die Praparation von Bi2Se3-Einkristallen mit niedriger Konzentration freier Ladungstrager erlaubte die Untersllchung der Gitterschwingungcn aus dem Reflexionsvermogen von Spaltflaclwn bci nahezu senkreehter Inzidenz der Stmhlung (E ~ c). Die .:\'IeBergebnisse konnen mit zwei klassischen Dispersionsoszillatoren erklart werden, deren Eigenfrequenzen bei 92 und 69,5 cm- I liegen. Dic st,atische Dielektrizitatskonstante wurde zu 100 ± 10 für E ~ c bestimmt.
Y1  - 1974
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31296
ER  - 
TY  - JOUR
A1  - Klitzing, K. von
A1  - Becker, Charles R.
T1  - Far infrared photoconductivity of residual acceptors in pure tellurium
N2  - The photoconductivity of both undeformed and deformed Te samples has been investigated at liquid He temperature by means of a Fourier spectrometer. Three peaks were usually found in the spectra of undeformed samples at 11, 24 and 46 cm\(^{-1}\). These are shown to be due to three different chemical impurities. The deformed samples are characterized by additional structure at higher frequencies.
Y1  - 1976
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31278
ER  - 
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  - 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  - 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  - 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  - 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  - 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  - 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  - 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 <Schmetterlinge>
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  - 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  - 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  - 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  - 
TY  - JOUR
A1  - Scheer, Ulrich
T1  - The ultrastructure of the nuclear envelope of amphibian oocytes: a reinvestigation. III. Actinomycin D-induced decrease in central granules within the pores.
N2  - No abstract available
Y1  - 1970
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32110
ER  - 
TY  - JOUR
A1  - Franke, Werner W.
A1  - Scheer, Ulrich
A1  - Fritsch, Hansjörg
T1  - Intranuclear and cytoplasmic annulate lamellae in plant cells
N2  - No abstract available
Y1  - 1972
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32148
ER  - 
TY  - JOUR
A1  - Franke, Werner W.
A1  - Kartenbeck, Jürgen
A1  - Zentgraf, Hanswalter
A1  - Scheer, Ulrich
A1  - Falk, Heinz
T1  - Membrane-to-membrane cross-bridges. A means to orientation and interaction of membrane faces
N2  - No abstract available
Y1  - 1971
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32122
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
A1  - Trendelenburg, Michael F.
T1  - Effects of actinomycin D on the association of newly formed ribonucleoproteins with the cistrons of ribosomal RNA in Triturus oocytes
N2  - No abstract available
Y1  - 1975
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32383
ER  - 
TY  - JOUR
A1  - Franke, Werner W.
A1  - Spring, Herbert
A1  - Scheer, Ulrich
A1  - Zerban, Heide
T1  - Growth of the nuclear envelope in the vegetative phase of the green alga Acetabularia. Evidence for assembly from membrane components synthesized in the cytoplasm.
N2  - No abstract available
Y1  - 1975
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32403
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
A1  - Trendelenburg, Michael F.
A1  - Spring, Herbert
T1  - Classification of loops of lampbrush chromosomes according to the arrangement of transcriptional complexes
N2  - The arrangement of transcriptional units in the loops of lampbrush chromosomes from oocyte nuclei of urodele amphibia and from primary nuclei of the green alga Acetabularia have been studied in the electron microscope using spread preparations. Loops with different patterns of arrangement of matrix units (i.e. to a first approximation, transcriptional units) can be distinguished: (i) loops consisting of one active transcriptional unit; (ii) loops containing one active transcriptional unit plus additional fibril-free, i.e. apparently untranscribed, intercepts that may include 'spacer' regions; (iii) loops containing two or more transcriptional units arranged in identical or changing polarities, with or without interspersed apparent spacer regions. Morphological details of the transcriptional complexes are described. The observations are not compatible with the concept that one loop reflects one and only one transcriptional unit but, rather, lead to a classification of loop types according to the arrangement of their transcriptional units. We propose that the lampbrush chromosome loop can represent a unit for the coordinate transcription of either one gene or a set of several (different) genes.
Y1  - 1976
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32822
ER  - 
TY  - JOUR
A1  - Brabletz, Thomas
A1  - Pfeuffer, Isolde
A1  - Schorr, Elke
A1  - Siebelt, Friederike
A1  - Wirth, Thomas
A1  - Serfling, Edgar
T1  - Transforming growth factor \(\beta\) and cyclosporin A inhibit the inducible activity of the interleukin-2 gene in T cells through a noncanonical octamer-binding site
N2  - Transforming growth factor \(\beta\) (TGF-\(\beta\)) has a growth-inhibitory effect on numerous different cell types of the immune system, including T lymphocytes. We show in this study that the inhibitory action of TGF-\(\beta\) on T lymphocytes is accompanied by a block of interleukin 2 (IL-2) gene expression which is mediated, at least in part, by inhibition of IL-2 promoter/enhancer activity. The functional analysis of cis-regulatory (protoenhancer) elements of the IL-2 enhancer/promoter region showed that the most TGF-\(\beta\)-responsive element maps to its so-called upstream promoter site. The proto-enhancer activity of the upstream promoter site element is also inhibited by cyclosporin A. The upstream promoter site DNA harbors two noncanonical, closely linked binding sequences for octamer and AP-1-like factors. Both sites are involved in the establishment of IL-2 enhancer activity. Since the activity of genuine octamer sites but not that of AP-1-binding sites is also impaired by TGF-\(\beta\) and cyclosporin A in E14 T lymphoma cells, we conclude that both immunosuppressives interfere with the activity but not the DNA binding of octamer factors in T lymphocytes.
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31199
ER  - 
TY  - JOUR
A1  - Ries, Wolfgang
A1  - Albright, Thomas
A1  - Silvestre, Jerome
A1  - Bernal, Ivan
A1  - Malisch, Wolfgang
A1  - Burschka, Christian
T1  - Unusual structural features of a siloxane
N2  - Crystals of the R, S diastereoisomer of [Cp(CO)\(_2\)-FeSiCH\(_3\)F]\(_2\)O are monoclinic, space group ndc (No. 14), with a = 846.0(3) [836.4(1»), b = 768.0(3) [757.1(1»), c = 1548.5(4) [1522.3(2)] pm, {3 = 97.34(3t [97.47(3t] at 300 K [120 K] with Z = 2. Even at 120 K the Si-O-Si fragment is found to be strictly linear due to crystallographically imposed symmetry. To explain the unusual electron distribution derived from the X-ray data collected, several types of possible disorders are discussed, none of which leads to a satisfying explanation. Retaining the Ci symmetry (linear Si-O-Si fragment in the final model) the important bond lengths are Fe-Si 226.7(1) [226.5(1)] pm, Si-F 160.9(2) [161.8(2)] pm, Si-O 160.3(1) [161.1(1)] pm, Si-C 185.0(3) [185.6(3)] pm. The electronic features of this compound were probed via molecular orbital calculations of the extended Hiickel type. It was found that the lone pairs on the siloxane oxygen were tipped away from cylindrical symmetry. The tipping was directed toward the fluorine substituents on the silicon atoms and away from the CpFe(CO)\(_2\) units. A pertubational approach was utilized to rationalize this effect.
KW  - Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31925
ER  - 
TY  - JOUR
A1  - Peach, Michael E.
A1  - Burschka, Christian
T1  - Metal carbonyl complexes of some aromatic ortho bis(methylthio)ethers
N2  - Various complexes of the type M(CO)4L and [M(CO)4lzL, M = Cr, Mo, W, have been prepared and characterized. A series of aromatic ortho bis(methylthio)ethers were used as the ligand L. The crystal structures of the free ligand C6(SCH)6 and of the complex Cr(CO)4C6(SCH)6 are reported.
N2  - On a prepare divers complexes du type M(CO)4L et [M(CO)4]2L, ou M = Cr, Mo, W, et on les a identifies. On a utilise une serie d'ortho bis (methylthio) ethers aromatiques comme ligand L. On rapporte la structure cristalIine du ligand libre C6(SCH)6 et celle du complexe Cr(CO)4C6(SCH)6.
KW  - Chemie
Y1  - 1982
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31964
ER  - 
TY  - JOUR
A1  - Borasio, Gian Domenico
A1  - John, Jacob
A1  - Wittinghofer, Alfred
A1  - Barde, Yves-Alain
A1  - Sendtner, Michael
A1  - Heumann, Rolf
T1  - ras p21 protein promotes survival and fiber outgrowth of cultured embryonic neurons
N2  - Although evidence obtained with the PC12 cell line has suggested a role for the ras oncogene proteins in the signal transduction of nerve growth factor-mediated fiber outgrowth, little is known about the signal transduction mechanisms involved in the neuronal response to neurotrophic factors in nontransformed cells. We report here that the oncogene protein T24-ras, when introduced into the cytoplasm of freshly dissociated chick embryonic neurons, promotes the in vitro survival and neurite outgrowth of nerve growth factor-responsive dorsal rootganglion neurons, brain-derived neurotrophic factor-responsive nodose ganglion neurons, and ciliary neuronotrophic factor-responsive ciliary ganglion neurons. The proto-oncogene product c-Ha-ras also promotes neuronal survival, albeit less strongly. No effect could be observed with truncated counterparts of T24-ras and c-Ha-ras lacking the 23 C-terminal amino acids including the membrane-an-choring, palmityl-accepting cysteine. These results sug-gest a generalized involvement of ras or ras-like proteins in the intracellular signal transduction pathway for neurotrophic factors.
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32621
ER  - 
TY  - JOUR
A1  - Sendtner, Michael
A1  - Kreutzberg, Georg W.
A1  - Thoenen, Hans
T1  - Ciliary neurotrophic factor (CNTF) prevents the degeneration of motor neurons after axotomy
N2  - The period of natural cell death in the development of rodent motor neurons is followed by a period of sensitivity to axonal injury1-3. In the rat this early postnatal period of vulnerability coincides with that of very low ciliary neurotrophic factor (CNTF) levels in the sciatic nerve before CNTF increases to the high, adult levels4. The developmental time course of CNTF expression, its regional tissue distribution and its cytosolic localization (as suggested by its primary structure)4*5 favour a role for CNTF as a lesion factor rather than a target-derived neurotrophic molecule like nerve growth factor. Nevertheless CNTF exhibits neurotrophic activity in vitro on different populations of embryonic neurons6. To determine whether the vulnerability of motor neurons to axotomy in the early postnatal phase is due to insufficient availability of CNTF, we transected the axons of newborn rat motor neurons and demonstrated that iocal application of CNTF prevents the degeneration of the corresponding cell bodies.
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32637
ER  - 
TY  - JOUR
A1  - Banach, Katrin
A1  - Bünemann, Moritz
A1  - Hüser, Jörg
A1  - Pott, Lutz
T1  - Serum contains a potent factor that decreases \(\beta\)-adrenergic receptor-stimulated L-type Ca\(^{2+}\) current in cardiac myocytes
N2  - No abstract available
KW  - Cardiac myocyte ; Beta-Receptor ; Muscarinic receptor ; cAMP ; G-protein ; Serum
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32027
ER  - 
TY  - JOUR
A1  - Derksen, J.
A1  - Trendelenburg, Michael F.
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
T1  - Spread chromosomal nucleoli of Chironomus salivary glands
N2  - No abstract available
Y1  - 1973
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32209
ER  - 
TY  - JOUR
A1  - Zentgraf, Hanswalter
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
T1  - Characterization and localization of the RNA synthesized in mature avian erythrocytes
N2  - No abstract available
Y1  - 1975
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32410
ER  - 
TY  - JOUR
A1  - Spring, Herbert
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
A1  - Trendelenburg, Michael F.
T1  - Lampbrush type chromosomes in the primary nucleus of the green alga Acetabularia mediterranea
N2  - No abstract available
Y1  - 1975
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32370
ER  - 
TY  - JOUR
A1  - Eckert, W. A.
A1  - Franke, Werner W.
A1  - Scheer, Ulrich
T1  - Nucleocytoplasmic translocation of RNA in Tetrahymena pyriformis and its inhibition by actinomycin D and cycloheximide
N2  - No abstract available
Y1  - 1975
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32399
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
T1  - Annulate lamellae in plant cells: formation during microsporogenesis and pollen development in Canna generalis Bailey
N2  - The occurrence of stacked annulate tamellae is documented for a plant cell system, namely for pollen mother cells and developing pollen grains of Canna generalis. Their structural subarchiteeture and relationship to endoplasmie reticulum (ER) and nuclear envelope cisternae is described in detail. The results demonstrate structural homology between plant and animal annulate lamellae and are compatible with, though do not prove, the view that annulate lamcllar cisternae may originate as a degenerative form of endoplasmic retieulum.
Y1  - 1972
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32160
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
T1  - The rifamycin derivative AF/013 is cytolytic
N2  - No abstract available
Y1  - 1975
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32429
ER  - 
TY  - JOUR
A1  - Dabauvalle, Marie-Christine
A1  - Loos, Karin
A1  - Scheer, Ulrich
T1  - Identification of a soluble precursor complex essential for nuclear pore assembly in vitro
N2  - No abstract available
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32801
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Trendelenburg, Michael F.
A1  - Franke, Werner W.
T1  - Transcription of ribosomal RNA cistrons: Correlation of morphological and biochemical data
N2  - Electron microscopic spread preparations of oocyte nucleoli (lampbrush stage) of various amphibians are quantitatively evaluated and the length distributions of repeat-, matrix-, and spacer-units along the rRNA cistron containing axes are given. The correlation of the matrix unit data with the gel electrophoretic pattern of labelled nuclear RNA from the same oocytes is examined. The mean value of the matrix unit corresponds fairly well to a 2.6 million D peak of pre-rRNA but the distribution of both matrix units and labelled pre-rRNAs shows an asymmetrical heterogeneity indicating the existence of some larger primary transcription products of rDNA. Novel structural aspects are described in the spacer regions which suggest that transcription does also take place in DNP regions between the matrix units. A special "prelude piece" coding for approx. 0.5 million D of RNA is frequently visualized in the spacer segments at the beginning of a matrix unit. Possible artifacts resulting from the preparation, the relative congruence between the data obtained using both methods, and the functional meaning of the findings are discussed against the background of current concepts of structural organization and transcription products of nucleolar DNA.
Y1  - 1973
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32195
ER  - 
TY  - JOUR
A1  - Franke, Werner W.
A1  - Trendelenburg, Michael F.
A1  - Scheer, Ulrich
T1  - Natural segregation of nucleolar components in the course of plant cell differentiation
N2  - Segregation of the nucleolar components is described in the differentiated nucleus of the generative cell in the growing Clivia and Lilium pollen tubes. This finding of a natural nucleolar segregation is discussed against the background of current views of the correlations of nucleolar morphology and transcriptional activity.
Y1  - 1973
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32182
ER  -