TY - JOUR A1 - Becker, Charles R. T1 - Evidence for a quasi-phonon gap in CsCl N2 - The observed impurity induced far-infrared absorption in CsCl : Rb\(^+\) and CsCl : K\(^+\) is compared with a calculated density of acoustic phonon states in CsCl. The absorption due to CsCl : Rb\(^+\) displays a minimum between the acoustic and optic phonon bands. A narrow line is observed in CsCl: K\(^+\) at 85.8 cm\(^{-1}\) which falls in this quasi-phonon gap. Y1 - 1971 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30767 ER - TY - JOUR A1 - Reimer, Georg A1 - Scheer, Ulrich A1 - Peters, Jan-Michael A1 - Tan, Eng M. T1 - Immunolocalization and partial characterization of a nucleolar autoantigen (PM-Scl) associated with polymyositis / scleroderma overlap syndromes. N2 - Precipitating anti-PM-Sel antibodies are present in sera from patients with polymyositis. scleroderma. and polymyositis/scleroderma overlap syndromes. By indirect immunofluorescence microscopy. anti-PM-Scl antibodies stained the nucleolus in cells of different tissues and species. suggesting that the antigen is highly conserved. By electron microscopy, anti-PM-Scl antibodies reacted primarily with the granular component of the nuc1eolus. Drugs that inhibit rRNA synthesis had a marked effect on the expression of PM-Scl antigen. In actinomycin D-treated cells, immunofluorescence staining by anti-PM-Scl was signüicantly reduced with residual staining restricted to the granular regions of nuc1eoli. Treatment with 5,6-dichloro-beta-D- ribofuranosylbenzimidazole (DRB) also selectively reduced nuc1eolar staining. On a molecular level, anti-PM-Sel antibodies precipitated 11 polypeptides with molecular weights (Mr) ranging from 110,000 to 20,000. The Mr 80,000 and 20.000 polypeptides were phosphorylated. Evidence suggests that the PM-Scl antigen complex may be related to a prerlbosomal particle. Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33191 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Sommerville, John A1 - Bustin, M. T1 - Injected histone antibodies interfere with transcription of lampbrush chromosome loops in oocytes of Pleurodeles N2 - Antibodies to calf thymus histone H2B were purified by chromatography on DEAE-cellulose and injected into oocyte nuclei of Pleurodeles waltlii. As shown by indirect immunofluorescence these antibodies cross-reacted strongly with corresponding histones associated with lampbrush chromosomes. Shortly after injection the lateral loops of the chromosomes retracted into the chromomeres and by 3 h postinjection the 'lampbrush' appearance was completely lost and the chromosomes appeared in light-microscopic preparations as rod-like structures consisting of 10ngitudina11y coalesced chromomeres. In control oocytes injected with non-immune immunoglobulins or antibodies against a ubiquitous transcript-associated protein no morphological alterations of the lampbrush chromosomes could be observed. Electron microscopic spreads of chromosomes prepared at various times after injection of anti-H2B revealed a progressive loss of transcriptional complexes from the loop axes. Finally, higher-order chromatin configurations, like supranuc1eosomal globules (' superbeads ') or cable-like chromatin strands 50- 60 nm thick predominated, indicating complete transcriptional inactivation of a11 chromosomal regions. The results indicate that H2B antibodies react specifically with his tones associated with the transcribed DNA of lateral loops in their native state. The resulting antigenantibody complexes seem to inhibit progression of the R A polymerases along the template, thus causing the premature release of transcripts, a process analogous to the stripping effect of actinomycin D. The demonstration of histones associated with heavily transcribed regions, which are not compacted into nucleosomes but largely extended, supports the current concept that unfolding of nucleosomes to a110w transcription of the DNA does not involve dissociation of histones. In contrast, amplified ribosomal RNA genes are unaffected by injected HzB antibodies. This does not necessarily indicate absence of his tones from nucleolar chromatin, since we do not know whether it is accessible in vivo to antibodies or whether the histone antigenie determinants are masked by the presence of other proteins. The technique of injecting specific antibodies should be widely applicable when analysing the in vivo distribution of chromosomal components at the electron-microscopic level and when studying complex metabolie processes, like the cleavage and modification of RNA, by selective inhibition of defined enzymic steps. Y1 - 1979 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33166 ER - TY - JOUR A1 - Reimer, Georg A1 - Rose, Kathleen M. A1 - Scheer, Ulrich A1 - Tan, Eng M. T1 - Autoantibody to RNA polymerase I in scleroderma sera N2 - Autoantibodies to components of the nucleolus are a unique serological feature of patients with scleroderma. There are autoantibodies of several specificities; one type produces a speckled pattern of nucleolar staining in immunofluorescence. In actinomycin D and 5,6-dichloro-{j-D-ribofuranosylbenzimidazoletreated Vero cells, staining was restricted to the fibrillar and not the granular regions. By double immunofluorescence, specific rabbit anti-RNA polymerase I antibodies stained the same fibrillar structures in drug-segregated nucleoli as scleroderma sera. Scleroderma sera immunoprecipitated 13 polypeptides from (35S)methionine-labeled HeLa cell extract with molecular weights ranging from 210,000 to 14,000. Similar polypeptides were precipitated by rabbit anti-RNA polymerase I antibodies, and their common identities were confirmed in immunoabsorption experiments. Microinjection of purified IgG from a patient with speckled nucleolar staining effectively inhibited ribosomal RNA transcription. Autoantibodies to RNA polymerase I were restricted to certain patients with scleroderma and were not found in other autoimmune diseases. Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34294 ER - TY - JOUR A1 - Reinhard, Matthias A1 - Halbrügge, Maria A1 - Scheer, Ulrich A1 - Wiegand, Christiane A1 - Jockusch, Brigitte M. A1 - Walter, Ulrich T1 - The 46/50 kDa phosphoprotein VASP purified from human platelets is a novel protein associated with actin filaments and focal contacts N2 - Vasoactive agents which elevate either cGMP or cAMP inhibit platelet activation by pathways sharing at least one component, the 46/50 kDa vasodilator-stimulated phosphoprotein (V ASP). V ASP is stoichiometrically phosphorylated by both cGMP-dependent and cAMPdependent protein kinases in intact human platelets, and its phosphorylation correlates very well with platelet inhibition caused by cGMP- and cAMP-elevating agents. Here we report that in human platelets spread on glass, V ASP is associated predominantly with the distal parts of radial micro filament bundles and with microfilaments outlining the periphery, whereas less V ASP is associated with a central microfilamentous ring. V ASP is also detectable in a variety of different cell types including fibroblasts and epithelial cells. In fibroblasts, V ASP is concentrated at focal contact areas, along microfilament bundles (stress fibres) in a punctate pattern, in the periphery of protruding lamellae, and is phosphorylated by cGMP- and cAMP-dependent protein kinases in response to appropriate stimuli. Evidence for the direct binding of V ASP to F -actin is also presented. The data demonstrate that V ASP is a novel phosphoprotein associated with actin filaments and focal contact areas, i.e. transmembrane junctions between microfilaments and the extracellular matrix. KW - cAMP / cGMP / cytoskeleton / phosphorylation / protein kinase Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34246 ER - TY - JOUR A1 - Scheer, Ulrich A1 - Dabauvalle, Marie-Christine A1 - Merkert, Hilde A1 - Benavente, Ricardo T1 - The nuclear envelope and the organization of the pore complexes N2 - No abstract available Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34275 ER - TY - JOUR A1 - Schubert, D.W. A1 - Kraus, M.M A1 - Kenklies, R. A1 - Becker, Charles R. A1 - Bicknell-Tassius, R.N. T1 - Composition and wavelength dependence of the refractive index in Cd\(_{1-x}\)Mn\(_x\)Te epitaxial layers N2 - We have investigated Cd\(_{1-x}\)Mn\(_x\)Te thin films with Mn concentrations of x=0.12, 0.18, 0.30, 0.52, and 0.70. These single crystal layers were grown by molecular beam epitaxy on [001] CdTe substrates. The real part of the refractive index, n, was determined below the band-gap Eo in the range of 0.5-2.5 eV at T=300 K. The parallel reOectivity was measured near the Brewster angle at the YAG laser wavelength of 1.064 J.Lm (hv= 1.165 eV). Combining these results with the optical pathlength results (nd) of reOection measurements in a Fourier spectrometer we have determined n(x,v) over a wide spectral range by utilizing a three parameter fit. The accuracy of these results for n should improve waveguide designs based on this material. Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-37716 ER - TY - JOUR A1 - Bell, Peter A1 - Dabauvalle, Marie-Christine A1 - Scheer, Ulrich T1 - In vitro assembly of prenucleolar bodies in Xenopus egg extract N2 - Nuclei assembled in Xenopus egg extract from purified DNA or chromatin resemble their natural counterparts in a number of structural and functional features. However, the most obvious structural element of normal interphase nuclei, the nucleolus, is absent from the in vitro reconstituted nuclei. By EM, cytological silver staining, and immunofluorescence microscopy employing antibodies directed against various nucleolar components we show that nuclei assembled in vitro contain numerous distinct aggregates that resemble prenucleolar bodies (PNBs) by several criteria. Formation of these PNB-like structures requires pore complex-mediated nuclear transport of proteins but is independent of the genetic content of the in vitro nuclei as well as transcriptional and translational events. Our data indicate that nuclei assembled in vitro are capable of initiating early steps of nucleologenesis but that the resulting PNBs are unable to fuse with each other, probably due to the absence of a functional nucleolus organizer. With appropriate modifications, this experimental system should be useful to define and analyze conditions promoting the site-specific assembly of PNBs into a coherent nucleolar body. Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34233 ER - TY - JOUR A1 - Scheer, Ulrich T1 - Identification of a novel class of tandemly repeated genes transcribed on lampbrush chromosomes of Pleurodeles waltlii N2 - Electron microscope preparations of lampbrush chromosomes from oocytes of Pleurodeles waltl;; have revealed a new class of tandemly repeated genes. These genes are highly active, as judged by the close spacing of nascent transcripts. They occur in clusters of >100 copies and are transcribed in units containing roughly 940 base pairs of DNA that are separated by nontranscribed spacers of an estimated DNA content of 2,410 base pairs. The size and the pattern of arrangement of these transcription units can not be correlated with any of the repetitious genes so far described. Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33153 ER - TY - JOUR A1 - Franke, Werner W. A1 - Kleinschmidt, Jürgen A. A1 - Spring, Herbert A1 - Krohne, Georg A1 - Grund, Christine A1 - Trendelenburg, Michael F. A1 - Stöhr, Michael A1 - Scheer, Ulrich T1 - A nucleolar skeleton of protein filaments demonstrated in amplified nucleoli of Xenopus laevis N2 - The amplified, extrachromosomal nucleoli of Xenopus oocytes contain a meshwork of -4-nm-thick filaments, which are densely coiled into higher-order fibrils of diameter 30-40 nm and are resistant to treatment with high- and low-salt concentrations, nucleases (DNase I, pancreatic RNase, micrococcal nuclease), sulfhydryl agents, and various nonionic detergents. This filamentous "skeleton" has been prepared from manually isolated nuclear contents and nucleoli as weil as from nucleoli isolated by fluorescence-activated particle sorting. The nucleolar skeletons are observed in light and electron microscopy and are characterized by ravels of filaments that are especially densely packed in the nucleolar cortex. DNA as weil as RNA are not constituents of this structure, and precursors to ribosomal RNAs are completely removed from the extraction-resistant filaments by treatment with high-salt buffer or RN ase. Fractions of isolated nucleolar skeletons show specific enrichment of an acidic major protein of 145,000 mol wt and an apparent pi value of -6.15, accompanied in some preparations by various amounts of minor proteins. The demonstration of this skeletal structure in "free" extrachromosomal nucleoli excludes the problem of contaminations by nonnucleolar material such as perinucleolar heterochromatin normally encountered in studies of nucleoli from somatic cells. It is suggested that this insoluble protein filament complex forms a skeleton specific to the nucleolus proper that is different from other extraction-resistant components of the nucleus such as matrix and lamina and is involved in the spatial organization of the nucleolar chromatin and its transcriptional products. In studies of the organization of the interphase nucleus, considerable progress has been made in the elucidation of the arrangement of chromatin components and transcriptional products. However, relatively little is known about the composition and function of another category of nuclear structures, the nonnucleoproteinaceous architectural components that are insoluble in solutions of low and high ionic strength, despite numerous studies dedicated to this problem. Such structures include (a) the nuclear envelope and its pore complexes (I, 15, 18, 23, 37, 41), (b) a peripheral layer of insoluble protein ("lamina"; I, 15, 22, 23, 59), (e) certain skeletal proteins related to the chromosome "scaffold" described by Laemmli and coworkers (see references 2 and 3), and (d) ill-defined tangles of fibrillar structures of the nuclear interior that are collectively described as residual "matrix" (6, 21 ; for reviews, see references THE JOURNAL OF CEll BrOlOGY . VOlUME 90 AUGUST 1981 289-299 © The RockefeIler University Press · 0021 -9525/ 81 / 08/ 0289/ 11 $1 .00 4 and 12). The latter, preparatively Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33130 ER - TY - JOUR A1 - Franke, Werner W. A1 - Scheer, Ulrich A1 - Krohne, Georg A1 - Jarasch, Ernst-Dieter T1 - The nuclear envelope and the architecture of the nuclear periphery N2 - No abstract available Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33108 ER - TY - JOUR A1 - Bona, Marion A1 - Scheer, Ulrich A1 - Bautz, Ekkehard K. F. T1 - Antibodies to RNA polymerase II (B) inhibit transcription in lampbrush chromosomes after microinjection into living amphibian oocytes N2 - Antibodies directed against RNA polymerase II (B) from Drosophila melanogaster were obtained from rabbit sera and, as monoclonal immunoglobulins, from mouse hybridomas and shown to cross-react with the amphibian enzyme protein. Localization by indirect immunofluorescence microscopy revealed the association of this enzyme with chromatin of interphase nuclei of amphibian cells and its absence in nucleoli. Purified immunoglobulins were microinjected in to nuclei ofliving vitellogenic oocytes of Ple1lrodeles waltlii and X enopus laevis and their effects on transcriptional processes were monitored by biochemical and light and electron microscopic stud ies. RNA polymerase II antibodies from rabbit sera caused a rapid and almost complete release of nascent transcripts from the chromatin axis of the loops of lampbrush chromosomes, followed by collapse of the loops and their retraction on the main chromosome axis. Monoclonal murine antibodies to the Iarge RNA polymerase II subunits also inhibited transcription in chromosome Ioops but appeared to inhibit initiation rather than elongation events. Activities of class land III RNA polymerases were not significantly affected by injection of antibodies to polymerase II, indicating immunological differences between the three RNA polymerases. The potential value of the in vitro test system described , as a very sensitive assay for detecting proteins involved in transcription in living cells, is discussed. 1 Y1 - 1981 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33128 ER - TY - JOUR A1 - Trendelenburg, Michael F. A1 - Scheer, Ulrich A1 - Zentgraf, Hanswalter A1 - Franke, Werner W. T1 - Heterogeneity of spacer lengths in circles of amplified ribosomal DNA of two insect species, Dytiscus marginalis and Acheta domesticus N2 - No abstract available Y1 - 1976 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33055 ER - TY - JOUR A1 - Emmrich, F. A1 - Moll, Heidrun A1 - Simon, Markus M. T1 - Recombinant human interleukin 2 acts as a B cell growth and differentiation promoting factor N2 - Human B cells appropriately activated by a B cell mitogen are rendered susceptible to human Interleukin 2 (IL-2) as demonstrated with recombinant human IL-2 (rec. h IL-2). They show increased proliferation and drastically enhanced immunoglobulin secretion. Susceptibility to IL-2 is accompanied with the expression of the IL-2 receptor (Tac antigen) on B cells. The data suggest that IL-2 is one of the lymphokines directly involved in the activation of B lymphocytes. Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34132 ER - TY - JOUR A1 - Moll, Heidrun A1 - Emmrich, F. A1 - Simon, Markus M. T1 - Recombinant human interleukin 2 directly provides signals for the proliferation and functional maturation of murine B lymphocytes N2 - In this study the effect of recombinant human interleukin 2 (rec.hIL-2) on the proliferation and maturation of B lymphocytes was investigated. It was found that the presence of rec.hIL 2 results in proliferation of mitogen (LPS)-activated B cell blasts. In addition, it is shown that highly enriched murine B cells can be induced by rec.hIL-2 to proliferate and to develop into antibody-secreting cells (PFC) in the presence of antigen (SRBC). When tested for its effect on B cell preparations enriched for resting (small) or activated (blasted) B lymphocytes, it was found that rec.hIL 2 provides signals for both B cell populations to develop into PFC. In contrast, induction of proliferation by the same lymphokine source was only seen in blasted B cells. The data indicate that IL 2 is involved in the generation of B effector cells by directly acting on their precursors thereby providing differentiation as well as proliferation signals. Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34090 ER - TY - JOUR A1 - Simon, Markus M. A1 - Moll, Heidrun A1 - Prester, Marlot A1 - Nerz, Gaby A1 - Eichmann, Klaus T1 - Immunoregulation by mouse T-cell clones. I. Suppression and amplification of cytotoxic responses by cloned H-Y-specific cytolytic T lymphocytes. N2 - H-Y-specific and H-2Db-restricted, Lyt-1 "2+ T-cell clones (CTLL) with graded specific cytotoxic activities on male C57BL/6 (B6) target cells (1E3, +++; 2C5, ++; 2A5, +, 3E6, ±) were tested for their capacity to inhibit the generation of H-Y-specific cytotoxic T lymphocytes (CTL) in vitro. Addition of irradiated lymphocytes of CTLL 1E3 and CTLL 3E6 but not those of CTLL 2A5 or CTLL 2C5 abolished the generation of CTL from in vivo primed H-Y-specific precursor cells (CTLP) when added to fresh mixed-lymphocyte cultures (MLC). Exogenous sources of T-cell growth factors (TCGF) did not overcome suppression. Rather the presence of TCGF resulted in a further enhancement of suppressive activities in CTLL 1E3 and 3E6 and the induction of similar activities in cells from CTLL 2A5 and 2C5, which by themselves were not inhibitory. Moreover when added to similar MLC on Day 1 instead of Day 0, only irradiated cells of CTLL 3E6 but not those of the other three CTLL were suppressive. Induction of suppressive activities in H-Y-specific CTLL was independent of the appropriate male stimulator cells since it was also observed in MLC induced by irrelevant antigens (H-2, trinitrophenol). Furthermore at low cell numbers, irradiated lymphocytes from any of the CTLL consistently enhanced CTL activities generated from H-Y-specific CTLP. This augmenting activity, which was not TCGF, could be transferred by soluble mediators present in antigen-sensitized CTLL cultures. Thus, these data indicate (i) that cytotoxic effector cells can function as suppressor cells in the generation of CTL, (ii) that the cytotoxic activity of cloned CTL does not correlate with their capacity to suppress CTL responses, (iii) that the inhibition of CTL responses by CTLL is not due to simple consumption of T-cell growth factors produced in MLC, and (iv) that different CTL clones may interfere with the generation of CTL at different stages of their maturation. Moreover, the experiments suggest an antigen-independent enhancement of suppression by the interaction of CTL with lymphokines. Together with the augmenting activity evoked by cloned CTL the data provide strong evidence for the expression of multiple immunological functions by one particular subset of T cells and suggest that cytotoxic effector cells can differentially regulate the maturation and/or clonal expression of their precursor cells. Y1 - 1984 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30892 ER - TY - JOUR A1 - Moll, Heidrun A1 - Eichmann, K. A1 - Simon, M. M. T1 - Immunoregulation by mouse T-cell clones. II. The same H-Y-specific T helper clone can provide help for the generation of cytotoxic lymphocytes and of antibody-secreting cells. N2 - Mouse H-Y-specific and I-Ab restricted T-cell clones have been established and compared for their helper effects in the differentiation ofboth T and B Iymphocytes. The results demonstrate that three individual T -cell clones and one subclone could help in the antigen-driven induction of cytotoxic Iymphocytes (CTL) from their precursor cells (CTL-P), and were able to activate B cells to develop into antibody-secreting cells (PFC) in the presence of SRBC, provided the cloned T cells were restimulated by H-Y antigen on antigen-presenting cells. In addition, antigen or lectin could induce the same H -Y -specific T -cell clones to secrete factor(s) expressing helper activities similar to that ofthe cloned T cells. Furthermore, it is shown that the T cell-derived soluble mediator(s) was distinct from T-cell growth factor (TCGF) and from immune interferon (lFN-y). The data reveal a new type ofT cell with helper potential for the activation ofCTL-P and B Iymphocytes, and suggest the existence of distinct T helper cells which can provide help for both cytotoxic and antibody responses by virtue of different Iymphokine activities. Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30903 ER - TY - JOUR A1 - Frischholz., S. A1 - Röllinghoff, M. A1 - Moll, Heidrun T1 - Cutaneous leishmaniasis: Co-ordinate expression of granzyme A and lymphokines by CD4\(^+\) T cells from susceptible mice. JF - Immunology N2 - We have recently demonstrated that the frequency ofT cells expressing granzyme A is significantly higher in skin lesions and spleens of susceptible BALB/c mice compared with resistant C57BL/6 mice infected with Leishmania major, a cause of human cutaneous leishmaniasis. In the present study, we have performed in vitro studies to characterize the subpopulation, the antigen responsiveness and the lymphokine production pattern of granzyme A-expressing T cells in L. major-infected mice. Using a limiting dilution system for functional analysis of selected T cells at the clonallevel, we could show that granzyme A activity in infected BALB/c mice can be assigned to L. major-reactive CD4\(^+\) T cells secreting interleukin-2 (IL-2) and IL-4. Granzyme A production was most pronounced in the early phase of infection. On the other hand, granzyme A expression could not be detected in C57BL/6-derived T cells responding to L. major. The da ta support the suggestion that granzyme A is produced by L. major-responsive CD4\(^+\) T cells facilitating lesion formation and the dissemination of infection. Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30954 VL - 82 SP - 255 EP - 260 ER - TY - JOUR A1 - Fiala, Brigitte A1 - Grunsky, Harald A1 - Maschwitz, Ulrich A1 - Linsenmair, Karl Eduard T1 - Diversity of ant-plant interactions: Protective efficacy in Macaranga species with different degrees of ant-association. N2 - The pioneer tree Macaranga in SE Asia has developed manyfold associations with ants. The genus comprises all stages of interaction with ants, from facultative relationships to obligate myrmecophytes. Only myrmecophytic Macaranga offer nesting space for ants and are associated with a specific ant partner. The nonmyrmecophytic species are visited by a variety of different ant species which are attracted by extrafloral nectaries (EFN) and food bodies. Transitional Macaranga species like M. hosei are colonized later in their development due to their stem structure. Before the colonization by their specific Crematogaster partner the young plants are visited by different ant species attracted by EFN. These nectaries are reduced and food body production starts as soon as colonization becomes possible. We demonstrated earlier that obligate ant partners can protect their Macaranga plants against herbivore damage and vine cover. In this study we focused on nonspecific interactions and studied M. tanarius and M. hosei, representing a non-myrmecophyte and a transitional species respectively. In ant exclusion experiments both M. tanarius and M. hosei suffered significantly higher mean leaf damage than controls, 37% versus 6% in M. hosei, 16% versus 7% in M. tanarius. M. tanarius offers both EFN and food bodies so that tests for different effects of these two food rewards could be conducted. Plants with food bodies removed but with EFN remaining had the lowest mean increase of herbivore damage of all experimental groups. Main herbivores on M. hosei were mites and caterpillars. Many M. tanarius plants were infested by a shootborer. Both Macaranga species were visited by various ant species. Crematogaster spp. being the most abundant. We found no evidence for any specific relationships. The results of this study strongly support the hypothesis that non-specific, facultative associations with ants can be advantageous for Macaranga plants. Food bodies appear to have lower attractive value for opportunistic ants than EFN and may require a specific dietary adaptation. This is also indicated by the fact that food body production in the transitional M. hosei does not start before stem structure allows a colonization by the obligate Crematogaster species. M. hosei thus benefits from facultative association with a variety of ants until it produces its first domatia and can be colonized by its obligate mutualist. KW - Ant-plant interactions ; Herbivory Macaranga ; Mutualism ; Myrmecophytes Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32905 ER - TY - JOUR A1 - Fiala, Brigitte A1 - Maschwitz, Ulrich T1 - Studies on the south east asian ant-plant association Crematogaster borneensis / Macaranga: adaptations of the ant partner. N2 - C. borneensis (Myrmicinae) lives in dose association with several myrmecophytic species of the South East Asian pioneer tree genus Macaranga (Euphorbiaceae). The ants are adapted to the plants so dosely that they do not survive away from it. The only food they utilize is provided as food bodies by the plant and honeydew from specific scale insects kept inside the hollow internodes. The anatomy of the digestive tract is also adapted to life on the host plant: the crop is very sm all and can store only minute food quantities. C. borneensis exdusively colonizes certain Macaranga species. Queens as weIl as workers are able to recognize their host plant species, probably by chemical cues. Colony founding queens swarm throughout the year, mostly during darkness. There is strong competition among queens for host plants. Queens do not carry scale insects on their nuptial flight. Worker ants are active day and night. Most of them patrol and collect food bodies on the younger parts of the host plant. An important characteristic is their deaning behaviour, which results in removal of aIl foreign objects. Even though they are rather smalI, workers respond very aggressively to certain kinds of disturbance of the host plant. The ants attack most phytophagous insects and are especially effective in killing and removing smalI, softbodied herbivores (e.g. caterpillars). They do not possess a functional sting, but apply defensive secretion and-once biting an intruder-will not let go. Their effective alarm system results in a mass attack, which provides adequate defence for the colony and the host plant. A comparison with another Crematogaster species further illustrated the special adaptations of C. borneensis to its host plant. N2 - Untersuchungen über die südostasiatische Ameisen·Pflanzen-Vergesellschaftung Cremattogaster borneensis Maoaranga : Anpassungen des Ameisenpartners 213 C. borneensis (Myrmicinae) lebt in enger Gemeinschaft mit myrmekophytischen Arten der südostasiatischen Pionierbaumgattung Macaranga (Euphorbiaceae) . Die Ameise ist so eng an die Pflanze adaptiert, daß sie getrennt von ihr nicht lebensfähig ist. Die Nahrung bezieht C. borneensis in Form von Nährkörperchen ausschließlich von der Pflanze. Im Sproßachseninnern gehaltene spezifische Schildläuse bieten eine weitere Nahrungsquelle. Die Adaptationen erstrecken sich bis auf die Anatomie des Verdauungstraktes : Der Kropf ist sehr klein und kann nur geringe Nahrungsmengen speichern. C. borneensis besiedelt spezifisch nur Macaranga-Pflanzen. Sowohl Königinnen als auch Arbeiterinnen sind in der Lage, die Wirtspflanze zu erkennen, wobei offenbar chemische Reize eine Rolle spielen. Die koloniegründenden Königinnen schwärmen das gesamte Jahr über, das Schwärmen erfolgt überwiegend während der Dunkelheit. Um die besiedlungsfähigen Macaranga-Pflanzen herrscht ein starker Konkurrenzdruck. Die beteiligten Schildlausarten sind spezifisch für die Assoziation. Sie werden nicht von der Königin beim Hochzeitsflug mitgenommen. Die Arbeiterinnen sind tag- und nachtaktiv. Die meisten Tiere halten sich im jüngsten Drittel der Pflanze auf, wo sie patrouillieren und Nährkörperchen sammeln. Mittels eines spezifischen Säuberungsverhaltens entfernen die Arbeiterinnen alle Fremdobjekte von der Pflanze. Trotz ihrer geringen Größe attackieren die Ameisen eine Vielzahl phytophager Insekten und sind dabei besonders effektiv in der Abwehr kleiner, wenig sklerotisierter Tiere wie z.B. Raupen. Sie verfügen zwar nicht ' über einen funktionsfähigen Stachel, setzen aber Wehrsekrete ein und beißen sich hartnäckig fest . Mit Hilfe eines effektiven Alarmierungssystems, das einen Massenangriff ermöglicht, gewährleisten sie eine Verteidigung ihrer Kolonien und damit gleichzeitig ihrer Wirtspflanze. Eine Vergleich mit einer anderen Crematogaster-Art demonstriert die besonderen Adaptationen von C. borneensis an ihre Wirtspflanze. Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32689 ER -