@article{BaumannDamesKuehneletal.2002, author = {Baumann, Otto and Dames, Petra and K{\"u}hnel, Dana and Walz, Bernd}, title = {Distribution of serotonergic and dopaminergic nerve fibers in the salivary gland complex of the cockroach Periplaneta americana}, year = {2002}, language = {en} } @article{BaumannKuehnelDamesetal.2004, author = {Baumann, Otto and K{\"u}hnel, Dana and Dames, Petra and Walz, Bernd}, title = {Dopaminergic and serotonergic innervation of cockroach salivary glands : distribution and morphology of synapses and release sites}, year = {2004}, abstract = {The paired salivary glands in the cockroach are composed of acini with ion-transporting peripheral P-cells and protein-secreting central C-cells, and a duct system for the modification of the primary saliva. Secretory activity is controlled by serotonergic and dopaminergic neurons, whose axons form a dense plexus on the glands. The spatial relationship of release sites for serotonin and dopamine to the various cell types was determined by anti-synapsin immunofluorescence confocal microscopy and electron microscopy. Every C-cell apparently has only serotonergic synapses on its surface. Serotonergic and dopaminergic fibres on the acini have their release zones at a distance of similar to0.5 mum from the P-cells. Nerves between acinar lobules may serve as neurohaemal organs and contain abundant dopaminergic and few serotonergic release sites. Some dopaminergic and serotonergic release sites reside in the duct epithelium, the former throughout the duct system, the latter only in segments next to acini. These findings are consistent with the view that C-cells respond exclusively to serotonin, P-cells to serotonin and dopamine, and most duct cells only to dopamine. Moreover, the data suggest that C-cells are stimulated by serotonin released close to their surface, whereas P-cells and most duct cells are exposed to serotonin/dopamine liberated at some distance}, language = {en} } @article{MalinovaMahlowAlseekhetal.2014, author = {Malinova, Irina and Mahlow, Sebastian and Alseekh, Saleh and Orawetz, Tom and Fernie, Alisdair R. and Baumann, Otto and Steup, Martin and Fettke, J{\"o}rg}, title = {Double knockout mutants of arabidopsis grown under normal conditions reveal that the plastidial phosphorylase isozyme participates in transitory starch metabolism}, series = {Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants}, volume = {164}, journal = {Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants}, number = {2}, publisher = {American Society of Plant Physiologists}, address = {Rockville}, issn = {0032-0889}, doi = {10.1104/pp.113.227843}, pages = {907 -- 921}, year = {2014}, abstract = {In leaves of two starch-related single-knockout lines lacking either the cytosolic transglucosidase (also designated as disproportionating enzyme 2, DPE2) or the maltose transporter (MEX1), the activity of the plastidial phosphorylase isozyme (PHS1) is increased. In both mutants, metabolism of starch-derived maltose is impaired but inhibition is effective at different subcellular sites. Two constitutive double knockout mutants were generated (designated as dpe2-1 x phs1a and mex1 x phs1b) both lacking functional PHS1. They reveal that in normally grown plants, the plastidial phosphorylase isozyme participates in transitory starch degradation and that the central carbon metabolism is closely integrated into the entire cell biology. All plants were grown either under continuous illumination or in a light-dark regime. Both double mutants were compromised in growth and, compared with the single knockout plants, possess less average leaf starch when grown in a light-dark regime. Starch and chlorophyll contents decline with leaf age. As revealed by transmission electron microscopy, mesophyll cells degrade chloroplasts, but degradation is not observed in plants grown under continuous illumination. The two double mutants possess similar but not identical phenotypes. When grown in a light-dark regime, mesophyll chloroplasts of dpe2-1 x phs1a contain a single starch granule but under continuous illumination more granules per chloroplast are formed. The other double mutant synthesizes more granules under either growth condition. In continuous light, growth of both double mutants is similar to that of the parental single knockout lines. Metabolite profiles and oligoglucan patterns differ largely in the two double mutants.}, language = {en} } @article{ReinZimmermannHilleetal.2006, author = {Rein, Julia and Zimmermann, Bernhard and Hille, Carsten and Lang, Ingo and Walz, Bernd and Baumann, Otto}, title = {Fluorescence measurements of serotonin-induced V-ATPase-dependent pH changes at the luminal surface in salivary glands of the blowfly Calliphora vicina}, issn = {0022-0949}, doi = {10.1242/Jeb.02187}, year = {2006}, abstract = {Secretion in blowfly salivary glands is induced by the neurohormone serotonin and powered by a vacuolar-type H+- ATPase (V-ATPase) located in the apical membrane of the secretory cells. We have established a microfluorometric method for analysing pH changes at the luminal surface of the secretory epithelial cells by using the fluorescent dye 5-N- hexadecanoyl-aminofluorescein (HAF). After injection of HAF into the lumen of the tubular salivary gland, the fatty acyl chain of the dye molecule partitions into the outer leaflet of the plasma membrane and its pH-sensitive fluorescent moiety is exposed at the cell surface. Confocal imaging has confirmed that HAF distributes over the entire apical membrane of the secretory cells and remains restricted to this membrane domain. Ratiometric analysis of HAF fluorescence demonstrates that serotonin leads to a reversible dose-dependent acidification at the luminal surface. Inhibition by concanamycin A confirms that the serotonin-induced acidification at the luminal surface is due to H+ transport across the apical membrane via V-ATPase. Measurements with pH-sensitive microelectrodes corroborate a serotonin-induced luminal acidification and demonstrate that luminal pH decreases by about 0.4 pH units at saturating serotonin concentrations. We conclude that ratiometric measurements of HAF fluorescence provide an elegant method for monitoring V-ATPase-dependent H+ transport in the blowfly salivary gland in vivo and for analysing the spatiotemporal pattern of pH changes at the luminal surface}, language = {en} } @inproceedings{KuhnertBaumannMeyeretal.2011, author = {Kuhnert, Oliver and Baumann, Otto and Meyer, Irene and Gr{\"a}f, Ralph}, title = {Functional characterization of CP148, a novel key component for centrosome integrity in Dictyostelium}, series = {Molecular biology of the cell : the official publication of the American Society for Cell Biology}, volume = {22}, booktitle = {Molecular biology of the cell : the official publication of the American Society for Cell Biology}, publisher = {American Society for Cell Biology}, address = {Bethesda}, issn = {1059-1524}, pages = {2}, year = {2011}, language = {en} } @article{KuhnertBaumannMeyeretal.2012, author = {Kuhnert, Oliver and Baumann, Otto and Meyer, Irene and Gr{\"a}f, Ralph}, title = {Functional characterization of CP148, a novel key component for centrosome integrity in Dictyostelium}, series = {Cellular and molecular life sciences}, volume = {69}, journal = {Cellular and molecular life sciences}, number = {11}, publisher = {Springer}, address = {Basel}, issn = {1420-682X}, doi = {10.1007/s00018-011-0904-2}, pages = {1875 -- 1888}, year = {2012}, abstract = {The centrosome consists of a layered core structure surrounded by a microtubule-nucleating corona. A tight linkage through the nuclear envelope connects the cytosolic centrosome with the clustered centromeres within the nuclear matrix. At G2/M the corona dissociates, and the core structure duplicates, yielding two spindle poles. CP148 is a novel coiled coil protein of the centrosomal corona. GFP-CP148 exhibited cell cycle-dependent presence and absence at the centrosome, which correlates with dissociation of the corona in prophase and its reformation in late telophase. During telophase, GFP-CP148 formed cytosolic foci, which coalesced and joined the centrosome. This explains the hypertrophic appearance of the corona upon strong overexpression of GFP-CP148. Depletion of CP148 by RNAi caused virtual loss of the corona and disorganization of interphase microtubules. Surprisingly, formation of the mitotic spindle and astral microtubules was unaffected. Thus, microtubule nucleation complexes associate with centrosomal core components through different means during interphase and mitosis. Furthermore, CP148 RNAi caused dispersal of centromeres and altered Sun1 distribution at the nuclear envelope, suggesting a role of CP148 in the linkage between centrosomes and centromeres. Taken together, CP148 is an essential factor for the formation of the centrosomal corona, which in turn is required for centrosome/centromere linkage.}, language = {en} } @misc{ReinVossBlenauetal.2008, author = {Rein, Julia and Voss, Martin and Blenau, Wolfgang and Walz, Bernd and Baumann, Otto}, title = {Hormone-induced assembly and activation of V-ATPase in blowfly salivary glands is mediated by protein kinase A}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-46126}, year = {2008}, abstract = {The vacuolar H+-ATPase (V-ATPase) in the apical membrane of blowfly (Calliphora vicina) salivary gland cells energizes the secretion of a KCl-rich saliva in response to the neurohormone serotonin (5-HT). We have shown previously that exposure to 5-HT induces a cAMP-mediated reversible assembly of V-0 and V-1 subcomplexes to V-ATPase holoenzymes and increases V-ATPase-driven proton transport. Here, we analyze whether the effect of cAMP on V-ATPase is mediated by protein kinase A (PKA) or exchange protein directly activated by cAMP (Epac), the cAMP target proteins that are present within the salivary glands. Immunofluorescence microscopy shows that PKA activators, but not Epac activators, induce the translocation of V1 components from the cytoplasm to the apical membrane, indicative of an assembly of V-ATPase holoenzymes. Measurements of transepithelial voltage changes and microfluorometric pH measurements at the luminal surface of cells in isolated glands demonstrate further that PKA-activating cAMP analogs increase cation transport to the gland lumen and induce a V-ATPase-dependent luminal acidification, whereas activators of Epac do not. Inhibitors of PKA block the 5-HT-induced V-1 translocation to the apical membrane and the increase in proton transport. We conclude that cAMP exerts its effects on V-ATPase via PKA.}, language = {en} } @article{StuermerBaumann1998, author = {St{\"u}rmer, Karoline and Baumann, Otto}, title = {Immunolocalization of a putative unconventional myosin on the surface of motile mitochondria in locust photoreceptors}, year = {1998}, language = {en} } @article{StuermerBaumann1996, author = {St{\"u}rmer, Karoline and Baumann, Otto}, title = {Immunolocalization of kinesin and cytoplasmic dynein in the retina of the locust Shistocerca gregaria}, year = {1996}, language = {en} } @article{Baumann2004, author = {Baumann, Otto}, title = {Konventionelle Fluoreszenzmikroskopie : Theorie und Anwendungsm{\"o}glichkeiten}, year = {2004}, language = {de} }