TY - JOUR A1 - Baumann, Otto A1 - Dames, Petra A1 - Kühnel, Dana A1 - Walz, Bernd T1 - Distribution of serotonergic and dopaminergic nerve fibers in the salivary gland complex of the cockroach Periplaneta americana Y1 - 2002 UR - http://www.biomedcentral.com/1472-6793/2/9 ER - TY - JOUR A1 - Baumann, Otto A1 - Kühnel, Dana A1 - Dames, Petra A1 - Walz, Bernd T1 - Dopaminergic and serotonergic innervation of cockroach salivary glands : distribution and morphology of synapses and release sites N2 - 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 Y1 - 2004 ER - TY - JOUR A1 - Malinova, Irina A1 - Mahlow, Sebastian A1 - Alseekh, Saleh A1 - Orawetz, Tom A1 - Fernie, Alisdair A1 - Baumann, Otto A1 - Steup, Martin A1 - Fettke, Jörg T1 - Double knockout mutants of arabidopsis grown under normal conditions reveal that the plastidial phosphorylase isozyme participates in transitory starch metabolism JF - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants N2 - 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. Y1 - 2014 U6 - https://doi.org/10.1104/pp.113.227843 SN - 0032-0889 SN - 1532-2548 VL - 164 IS - 2 SP - 907 EP - 921 PB - American Society of Plant Physiologists CY - Rockville ER - TY - JOUR A1 - Rein, Julia A1 - Zimmermann, Bernhard A1 - Hille, Carsten A1 - Lang, Ingo A1 - Walz, Bernd A1 - Baumann, Otto T1 - Fluorescence measurements of serotonin-induced V-ATPase-dependent pH changes at the luminal surface in salivary glands of the blowfly Calliphora vicina N2 - 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 Y1 - 2006 UR - http://jeb.biologists.org/ U6 - https://doi.org/10.1242/Jeb.02187 SN - 0022-0949 ER - TY - CHAP A1 - Kuhnert, Oliver A1 - Baumann, Otto A1 - Meyer, Irene A1 - Gräf, Ralph T1 - Functional characterization of CP148, a novel key component for centrosome integrity in Dictyostelium T2 - Molecular biology of the cell : the official publication of the American Society for Cell Biology Y1 - 2011 SN - 1059-1524 VL - 22 PB - American Society for Cell Biology CY - Bethesda ER - TY - JOUR A1 - Kuhnert, Oliver A1 - Baumann, Otto A1 - Meyer, Irene A1 - Gräf, Ralph T1 - Functional characterization of CP148, a novel key component for centrosome integrity in Dictyostelium JF - Cellular and molecular life sciences N2 - 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. KW - Dictyostelium KW - Corona KW - Microtubules KW - Centrosome KW - Nucleus Y1 - 2012 U6 - https://doi.org/10.1007/s00018-011-0904-2 SN - 1420-682X VL - 69 IS - 11 SP - 1875 EP - 1888 PB - Springer CY - Basel ER - TY - GEN A1 - Rein, Julia A1 - Voss, Martin A1 - Blenau, Wolfgang A1 - Walz, Bernd A1 - Baumann, Otto T1 - Hormone-induced assembly and activation of V-ATPase in blowfly salivary glands is mediated by protein kinase A N2 - 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. KW - Vacuolar h+-atpase KW - camp binding-sites KW - cyclic-amp KW - plasma-membrane KW - drosophila-melanogaster Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-46126 ER - TY - JOUR A1 - Stürmer, Karoline A1 - Baumann, Otto T1 - Immunolocalization of a putative unconventional myosin on the surface of motile mitochondria in locust photoreceptors Y1 - 1998 ER - TY - JOUR A1 - Stürmer, Karoline A1 - Baumann, Otto T1 - Immunolocalization of kinesin and cytoplasmic dynein in the retina of the locust Shistocerca gregaria Y1 - 1996 ER - TY - JOUR A1 - Baumann, Otto T1 - Konventionelle Fluoreszenzmikroskopie : Theorie und Anwendungsmöglichkeiten Y1 - 2004 ER - TY - JOUR A1 - Yasuhara, Jiro A1 - Baumann, Otto A1 - Takeyasu, Kunio T1 - Localization of Na/K-ATPase in developing and adult Drosophila melanogaster photoreceptors N2 - Drosophila melanogaster photoreceptors are highly polarized cells and their plasma membrane is organized into distinct domains. Zonula adherens junctions separate a smooth peripheral surface, the equivalent of the basolateral surface in other epithelial cells, from the central surface (cong apical surface). The latter consists of the microvillar rhabdomere and the juxtarhabdomeric domain, a nonmicrovillar area between the rhabdomere and the zonulae adherens. The distribution of Na/K-ATPase over these domains was examined by immunocytochemical, developmental, and genetic approaches. Immunofluorescence and immunogold labeling of adult compound eyes reveal that the distribution of Na/ K-ATPase is concentrated at the peripheral surface in the photoreceptors R1-R6, but extends over the juxtarhabdomeric domain to the rhabdomere in the photoreceptors R7/R8. Developmental analysis demonstrates further that Na/K-ATPase is localized over the entire plasma membrane in all photoreceptors in early pupal eyes. Redistribution of Na/K-ATPase in R1- R6 occurs at about 78% of pupal life, coinciding with the onset of Rh1-rhodopsin expression on the central surface of these cells. Despite the essential role of Rh1 in structural development and intracellular trafficking, Rh1 mutations do not affect the distribution of Na/K-ATPase. These results suggest that Na/K-ATPase and rhodopsin are involved in distinct intracellular localization mechanisms, which are maintained independent of each other. Y1 - 2000 UR - http://www.link.springer.de/link/service/journals/00441/bibs/030002/03000239.htm ER - TY - JOUR A1 - Baumann, Otto A1 - Murphy, Douglas B. T1 - Microtubule-associated movement of mitochondria and small particles in Acanthamoeba castellanii. Y1 - 1995 ER - TY - JOUR A1 - Röser, Claudia A1 - Jordan, Nadine A1 - Balfanz, Sabine A1 - Baumann, Arnd A1 - Walz, Bernd A1 - Baumann, Otto A1 - Blenau, Wolfgang T1 - Molecular and pharmacological characterization of serotonin 5-HT2 alpha and 5-HT7 receptors in the salivary glands of the blowfly calliphora vicina JF - PLoS one N2 - Secretion in blowfly (Calliphora vicina) salivary glands is stimulated by the biogenic amine serotonin (5-hydroxytryptamine, 5-HT), which activates both inositol 1,4,5-trisphosphate (InsP(3))/Ca2+ and cyclic adenosine 3',5'-monophosphate (cAMP) signalling pathways in the secretory cells. In order to characterize the signal-inducing 5-HT receptors, we cloned two cDNAs (Cv5-ht2 alpha, Cv5-ht7) that share high similarity with mammalian 5-HT2 and 5-HT7 receptor genes, respectively. RT-PCR demonstrated that both receptors are expressed in the salivary glands and brain. Stimulation of Cv5-ht2 alpha-transfected mammalian cells with 5-HT elevates cytosolic [Ca2+] in a dose-dependent manner (EC50 = 24 nM). In Cv5-ht7-transfected cells, 5-HT produces a dose-dependent increase in [cAMP](i) (EC50 = 4 nM). We studied the pharmacological profile for both receptors. Substances that appear to act as specific ligands of either Cv5-HT2 alpha or Cv5-HT7 in the heterologous expression system were also tested in intact blowfly salivary gland preparations. We observed that 5-methoxytryptamine (100 nM) activates only the Cv(5)-HT2 alpha receptor, 5-carboxamidotryptamine (300 nM) activates only the Cv5-HT7 receptor, and clozapine (1 mu M) antagonizes the effects of 5-HT via Cv5-HT7 in blowfly salivary glands, providing means for the selective activation of each of the two 5-HT receptor subtypes. This study represents the first comprehensive molecular and pharmacological characterization of two 5-HT receptors in the blowfly and permits the analysis of the physiological role of these receptors, even when co-expressed in cells, and of the modes of interaction between the Ca2+- and cAMP-signalling cascades. Citation: Roser C, Jordan N, Balfanz S, Baumann A, Walz B, et al. (2012) Molecular and Pharmacological Characterization of Serotonin 5-HT2a and 5-HT7 Receptors in the Salivary Glands of the Blowfly Calliphora vicina. Y1 - 2012 U6 - https://doi.org/10.1371/journal.pone.0049459 SN - 1932-6203 VL - 7 IS - 11 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Klose, Sascha Peter A1 - Rolke, Daniel A1 - Baumann, Otto T1 - Morphogenesis of honeybee hypopharyngeal gland during pupal development JF - Frontiers in zoology N2 - Background The hypopharyngeal gland of worker bees contributes to the production of the royal jelly fed to queens and larvae. The gland consists of thousands of two-cell units that are composed of a secretory cell and a duct cell and that are arranged in sets of about 12 around a long collecting duct. Results By fluorescent staining, we have examined the morphogenesis of the hypopharyngeal gland during pupal life, from a saccule lined by a pseudostratified epithelium to the elaborate organ of adult worker bees. The hypopharyngeal gland develops as follows. (1) Cell proliferation occurs during the first day of pupal life in the hypopharyngeal gland primordium. (2) Subsequently, the epithelium becomes organized into rosette-like units of three cells. Two of these will become the secretory cell and the duct cell of the adult secretory units; the third cell contributes only temporarily to the development of the secretory units and is eliminated by apoptosis in the second half of pupal life. (3) The three-cell units of flask-shaped cells undergo complex changes in cell morphology. Thus, by mid-pupal stage, the gland is structurally similar to the adult hypopharyngeal gland. (4) Concomitantly, the prospective secretory cell attains its characteristic subcellular organization by the invagination of a small patch of apical membrane domain, its extension to a tube of about 100 μm in length (termed a canaliculus), and the expansion of the tube to a diameter of about 3 μm. (6) Finally, the canaliculus-associated F-actin system becomes reorganized into rings of bundled actin filaments that are positioned at regular distances along the membrane tube. Conclusions The morphogenesis of the secretory units in the hypopharyngeal gland of the worker bee seems to be based on a developmental program that is conserved, with slight modification, among insects for the production of dermal glands. Elaboration of the secretory cell as a unicellular seamless epithelial tube occurs by invagination of the apical membrane, its extension likely by targeted exocytosis and its expansion, and finally the reorganisation of the membrane-associated F-actin system. Our work is fundamental for future studies of environmental effects on hypopharyngeal gland morphology and development. KW - Exocrine gland KW - Insect KW - Epithelial tube KW - Organogenesis KW - Cell polarity KW - Actin cytoskeleton KW - Apoptosis KW - Invagination Y1 - 2017 U6 - https://doi.org/10.1186/s12983-017-0207-z SN - 1742-9994 VL - 14 PB - BioMed Central CY - London ER - TY - GEN A1 - Klose, Sascha Peter A1 - Rolke, Daniel A1 - Baumann, Otto T1 - Morphogenesis of honeybee hypopharyngeal gland during pupal development N2 - Background The hypopharyngeal gland of worker bees contributes to the production of the royal jelly fed to queens and larvae. The gland consists of thousands of two-cell units that are composed of a secretory cell and a duct cell and that are arranged in sets of about 12 around a long collecting duct. Results By fluorescent staining, we have examined the morphogenesis of the hypopharyngeal gland during pupal life, from a saccule lined by a pseudostratified epithelium to the elaborate organ of adult worker bees. The hypopharyngeal gland develops as follows. (1) Cell proliferation occurs during the first day of pupal life in the hypopharyngeal gland primordium. (2) Subsequently, the epithelium becomes organized into rosette-like units of three cells. Two of these will become the secretory cell and the duct cell of the adult secretory units; the third cell contributes only temporarily to the development of the secretory units and is eliminated by apoptosis in the second half of pupal life. (3) The three-cell units of flask-shaped cells undergo complex changes in cell morphology. Thus, by mid-pupal stage, the gland is structurally similar to the adult hypopharyngeal gland. (4) Concomitantly, the prospective secretory cell attains its characteristic subcellular organization by the invagination of a small patch of apical membrane domain, its extension to a tube of about 100 μm in length (termed a canaliculus), and the expansion of the tube to a diameter of about 3 μm. (6) Finally, the canaliculus-associated F-actin system becomes reorganized into rings of bundled actin filaments that are positioned at regular distances along the membrane tube. Conclusions The morphogenesis of the secretory units in the hypopharyngeal gland of the worker bee seems to be based on a developmental program that is conserved, with slight modification, among insects for the production of dermal glands. Elaboration of the secretory cell as a unicellular seamless epithelial tube occurs by invagination of the apical membrane, its extension likely by targeted exocytosis and its expansion, and finally the reorganisation of the membrane-associated F-actin system. Our work is fundamental for future studies of environmental effects on hypopharyngeal gland morphology and development. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 337 KW - Exocrine gland KW - Insect KW - Epithelial tube KW - Organogenesis KW - Cell polarity KW - Actin cytoskeleton KW - Apoptosis KW - Invagination Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-395712 ER - TY - JOUR A1 - Klose, Sascha Peter A1 - Rolke, Daniel A1 - Baumann, Otto T1 - Morphogenesis of honeybee hypopharyngeal gland during pupal development JF - Frontiers in zoology N2 - Background: The hypopharyngeal gland of worker bees contributes to the production of the royal jelly fed to queens and larvae. The gland consists of thousands of two-cell units that are composed of a secretory cell and a duct cell and that are arranged in sets of about 12 around a long collecting duct. Results: By fluorescent staining, we have examined the morphogenesis of the hypopharyngeal gland during pupal life, from a saccule lined by a pseudostratified epithelium to the elaborate organ of adult worker bees. The hypopharyngeal gland develops as follows. (1) Cell proliferation occurs during the first day of pupal life in the hypopharyngeal gland primordium. (2) Subsequently, the epithelium becomes organized into rosette-like units of three cells. Two of these will become the secretory cell and the duct cell of the adult secretory units; the third cell contributes only temporarily to the development of the secretory units and is eliminated by apoptosis in the second half of pupal life. (3) The three-cell units of flask-shaped cells undergo complex changes in cell morphology. Thus, by mid-pupal stage, the gland is structurally similar to the adult hypopharyngeal gland. (4) Concomitantly, the prospective secretory cell attains its characteristic subcellular organization by the invagination of a small patch of apical membrane domain, its extension to a tube of about 100 mu m in length (termed a canaliculus), and the expansion of the tube to a diameter of about 3 mu m. (6) Finally, the canaliculus-associated F-actin system becomes reorganized into rings of bundled actin filaments that are positioned at regular distances along the membrane tube. Conclusions: The morphogenesis of the secretory units in the hypopharyngeal gland of the worker bee seems to be based on a developmental program that is conserved, with slight modification, among insects for the production of dermal glands. Elaboration of the secretory cell as a unicellular seamless epithelial tube occurs by invagination of the apical membrane, its extension likely by targeted exocytosis and its expansion, and finally the reorganisation of the membrane-associated F-actin system. Our work is fundamental for future studies of environmental effects on hypopharyngeal gland morphology and development. KW - Exocrine gland KW - Insect KW - Epithelial tube KW - Organogenesis KW - Cell polarity KW - Actin cytoskeleton KW - Apoptosis KW - Invagination Y1 - 2017 U6 - https://doi.org/10.1186/s12983-017-0207-z SN - 1742-9994 VL - 14 SP - 2866 EP - 2875 PB - BioMed Central CY - London ER - TY - JOUR A1 - Schwarze, Thomas A1 - Kelling, Alexandra A1 - Müller, Holger A1 - Trautmann, Michael A1 - Klamroth, Tillmann A1 - Baumann, Otto A1 - Strauch, Peter A1 - Holdt, Hans-Jürgen T1 - N-2-Pyridinylmethyl-N '-arylmethyl-diaminomaleonitriles: New Highly Selective Chromogenic Chemodosimeters for Copper(II) JF - Chemistry - a European journal KW - amides KW - chemodosimeter KW - colorimetric detection KW - copper KW - sensors KW - UV KW - Vis spectroscopy Y1 - 2012 U6 - https://doi.org/10.1002/chem.201201731 SN - 0947-6539 VL - 18 IS - 34 SP - 10506 EP - 10510 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Barchewitz, Tino A1 - Guljamow, Arthur A1 - Meißner, Sven A1 - Timm, Stefan A1 - Henneberg, Manja A1 - Baumann, Otto A1 - Hagemann, Martin A1 - Dittmann, Elke T1 - Non-canonical localization of RubisCO under high-light conditions in the toxic cyanobacterium Microcystis aeruginosa PCC7806 JF - Environmental microbiology N2 - The frequent production of the hepatotoxin microcystin (MC) and its impact on the lifestyle of bloom-forming cyanobacteria are poorly understood. Here, we report that MC interferes with the assembly and the subcellular localization of RubisCO, in Microcystis aeruginosa PCC7806. Immunofluorescence, electron microscopic and cellular fractionation studies revealed a pronounced heterogeneity in the subcellular localization of RubisCO. At high cell density, RubisCO particles are largely separate from carboxysomes in M. aeruginosa and relocate to the cytoplasmic membrane under high-light conditions. We hypothesize that the binding of MC to RubisCO promotes its membrane association and enables an extreme versatility of the enzyme. Steady-state levels of the RubisCO CO2 fixation product 3-phosphoglycerate are significantly higher in the MC-producing wild type. We also detected noticeable amounts of the RubisCO oxygenase reaction product secreted into the medium that may support the mutual interaction of M. aeruginosa with its heterotrophic microbial community. Y1 - 2019 U6 - https://doi.org/10.1111/1462-2920.14837 SN - 1462-2912 SN - 1462-2920 VL - 21 IS - 12 SP - 4836 EP - 4851 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Bresnick, Anne R. A1 - Wolff-Long, Vicki L. A1 - Baumann, Otto A1 - Pollard, Thomas D. T1 - Phosphorylation of threonine-18 of the regulatory light chain dissociates the ATPase and motor properties of smooth muscle myosin II Y1 - 1995 SN - 006-2960 ER - TY - JOUR A1 - Mahlow, Sebastian A1 - Hejazi, Mahdi A1 - Kuhnert, Franziska A1 - Garz, Andreas A1 - Brust, Henrike A1 - Baumann, Otto A1 - Fettke, Jörg T1 - Phosphorylation of transitory starch by -glucan, water dikinase during starch turnover affects the surface properties and morphology of starch granules JF - New phytologist : international journal of plant science N2 - Glucan, water dikinase (GWD) is a key enzyme of starch metabolism but the physico-chemical properties of starches isolated from GWD-deficient plants and their implications for starch metabolism have so far not been described. Transgenic Arabidopsis thaliana plants with reduced or no GWD activity were used to investigate the properties of starch granules. In addition, using various in vitro assays, the action of recombinant GWD, -amylase, isoamylase and starch synthase 1 on the surface of native starch granules was analysed. The internal structure of granules isolated from GWD mutant plants is unaffected, as thermal stability, allomorph, chain length distribution and density of starch granules were similar to wild-type. However, short glucan chain residues located at the granule surface dominate in starches of transgenic plants and impede GWD activity. A similarly reduced rate of phosphorylation by GWD was also observed in potato tuber starch fractions that differ in the proportion of accessible glucan chain residues at the granule surface. A model is proposed to explain the characteristic morphology of starch granules observed in GWD transgenic plants. The model postulates that the occupancy rate of single glucan chains at the granule surface limits accessibility to starch-related enzymes. KW - Arabidopsis thaliana KW - glucan KW - water dikinase (GWD) KW - sex1-8 KW - starch granule surface KW - starch phosphorylation Y1 - 2014 U6 - https://doi.org/10.1111/nph.12801 SN - 0028-646X SN - 1469-8137 VL - 203 IS - 2 SP - 495 EP - 507 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Baumann, Otto A1 - Lutz, Kathleen T1 - Photoreceptor morphogenesis in the Drosophila compound eye : R1-R6 rhabdomeres become twisted just before eclosion N2 - The photosensitive microvilli of Drosophila photoreceptors R1-R6 are not aligned in parallel over the entire length of the visual cells. In the distal half of each cell, the microvilli are slightly tilted toward one side and, in the proximal half, extremely toward the opposite side. This phenomenon, termed rhabdomere twisting, has been known for several decades, but the developmental and cell biological basis of rhabdomere twisting has not been studied so far. We show that rhabdomere twisting is also manifested as molecular polarization of the visual cell, because phosphotyrosine- containing proteins are selectively partitioned to different sides of the rhabdomere stalk in the distal. and proximal sections of each R1-R6 photoreceptor. Both the asymmetrical segregation of phosphotyrosine proteins and the tilting of the microvilli occur shortly before eclosion of the flies, when eye development in all other aspects is considered to be essentially complete. Establishment of rhabdomere twisting occurs in a light-independent manner, because phosphotyrosine staining is unchanged in dark-reared wild-type flies and in mutants with defects in the phototransduction cascade, ninaE(17) and norpA(P24). We conclude that antiphosphotyrosine immunofluorescence can be used as a light microscopic probe for the analysis of rhabdomere twisting and that microvilli tilting represents a type of planar cell polarity that is established by an active process in the last phase of photoreceptor morphogenesis, just prior to eclosion of the flies. Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/31248 U6 - https://doi.org/10.1002/Cne.21030 SN - 0021-9967 ER - TY - JOUR A1 - Baumann, Otto T1 - Posterior midgut epithelial cells differ in their organization of the membrane skeleton from other Drosophila epithelia Y1 - 2001 ER - TY - JOUR A1 - Dames, Petra A1 - Schmidt, R. A1 - Walz, Bernd A1 - Baumann, Otto T1 - Regulation of vacuolar-type H+-ATPase (vATPase) in blowfly salivary glands Y1 - 2004 SN - 0171-9335 ER - TY - JOUR A1 - Richter, Katharina Natalia A1 - Rolke, Daniel A1 - Blenau, Wolfgang A1 - Baumann, Otto T1 - Secretory cells in honeybee hypopharyngeal gland: polarized organization and age-dependent dynamics of plasma membrane JF - Cell & tissue research N2 - The honeybee hypopharyngeal gland consists in numerous units, each comprising a secretory cell and a canal cell. The secretory cell discharges its products into a convoluted tubular membrane system, the canaliculus, which is surrounded at regular intervals by rings of actin filaments. Using probes for various membrane components, we analyze the organization of the secretory cells relative to the apicobasal configuration of epithelial cells. The canaliculus was defined by labeling with an antibody against phosphorylated ezrin/radixin/moesin (pERM), a marker protein for the apical membrane domain of epithelial cells. Anti-phosphotyrosine visualizes the canalicular system, possibly by staining the microvillar tips. The open end of the canaliculus leads to a region in which the secretory cell is attached to the canal cell by adherens and septate junctions. The remaining plasma membrane stains for Na,K-ATPase and spectrin and represents the basolateral domain. We also used fluorophore-tagged phalloidin, anti-phosphotyrosine and anti-pERM as probes for the canaliculus in order to describe fine-structural changes in the organization of the canalicular system during the adult life cycle. These probes in conjunction with fluorescence microscopy allow the fast and detailed three-dimensional analysis of the canalicular membrane system and its structural changes in a developmental mode or in response to environmental factors. KW - Hypopharyngeal gland KW - Cell polarity KW - Moesin KW - Actin cytoskeleton KW - Honeybee Y1 - 2016 U6 - https://doi.org/10.1007/s00441-016-2423-9 SN - 0302-766X SN - 1432-0878 VL - 366 SP - 163 EP - 174 PB - Springer CY - New York ER - TY - GEN A1 - Blenau, Wolfgang A1 - Rotte, Cathleen A1 - Witte, Jeannine A1 - Baumann, Otto A1 - Walz, Bernd T1 - Source, topography and excitatory effects of GABAergic innervation in cockroach salivary glands N2 - Cockroach salivary glands are innervated by dopaminergic and serotonergic neurons. Both transmitters elicit saliva secretion. We studied the distribution pattern of neurons containing gamma-aminobutyric acid ( GABA) and their physiological role. Immunofluorescence revealed a GABA-immunoreactive axon that originates within the subesophageal ganglion at the salivary neuron 2 (SN2) and this extends within the salivary duct nerve towards the salivary gland. GABA-positive fibers form a network on most acinar lobules and a dense plexus in the interior of a minor fraction of acinar lobules. Co-staining with anti-synapsin revealed that some putative GABAergic terminals seem to make pre-synaptic contacts with GABA-negative release sites. Many putative GABAergic release sites are at some distance from other synapses and at distance from the acinar tissue. Intracellular recordings from isolated salivary glands have revealed that GABA does not affect the basolateral membrane potential of the acinar cells directly. When applied during salivary duct nerve stimulation, GABA enhances the electrical response of the acinar cells and increases the rates of fluid and protein secretion. The effect on electrical cell responses is mimicked by the GABA(B) receptor agonists baclofen and SKF97541, and blocked by the GABAB receptor antagonists CGP52432 and CGP54626. These findings indicate that GABA has a modulatory role in the control of salivation, acting presynaptically on serotonergic and/or dopaminergic neurotransmission. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 111 KW - GABA KW - salivary gland KW - innervation KW - cockroach KW - Periplaneta americana Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44353 ER - TY - JOUR A1 - Baumann, Otto T1 - Spatial pattern of nonmuscle myosin-II distribution during the development of the Drosophila compound eye and implications for retinal morphogenesis N2 - Nonmuscle myosin-II is a motor protein that drives cell movement and changes in cell shape during tissue and organ development. This study has determined he dynamic changes in myosin-II distribution during Drosophila compound eye morphogenesis. In photoreceptor neurons, myosin-II is undetectable at the apical domain throughout the first half of pupal life, at which time this membrane domain is involuted into the epithelium and progresses toward the retinal floor. Myosin-II is deployed at the apical surface at about 60% of pupal development, once the developing rhabdomeres reach the retinal floor. Subsequently, myosin-II becomes restricted to two stripes at the sides of the developing rhabdomere, adopting its final position within the visual cells R1-6; here, myosin-II is associated with a set of actin filaments that extend alongside the rhabdomeres. At the midpupal stage, myosin-II is also incorporated into stress-fiber-like arrays within the basal endfeet of the pigment cells that then change their shape. This spatiotemporal pattern of myosin- II localization and the morphological defects observed in the eyes of a myosin-II mutant suggest that the myosin-II/F- actin system is involved in the alignment of the rhabdomeres within the retina and in the flattening of the retinal floor. The observation that the myosin-II/F-actin arrays are incomplete or disorganized in R7/R8 and in rhodopsin-1-null R1-6 suggests further that the establishment and stability of this cytoskeletal system depend on rhodopsin-1 expression. (C) 2004 Elsevier Inc. All rights reserved Y1 - 2004 ER - TY - GEN A1 - Batsios, Petros A1 - Ren, Xiang A1 - Baumann, Otto A1 - Larochelle, Denis A. A1 - Gräf, Ralph T1 - Src1 is a Protein of the Inner Nuclear Membrane Interacting with the Dictyostelium Lamin NE81 N2 - The nuclear envelope (NE) consists of the outer and inner nuclear membrane (INM), whereby the latter is bound to the nuclear lamina. Src1 is a Dictyostelium homologue of the helix-extension-helix family of proteins, which also includes the human lamin-binding protein MAN1. Both endogenous Src1 and GFP-Src1 are localized to the NE during the entire cell cycle. Immuno-electron microscopy and light microscopy after differential detergent treatment indicated that Src1 resides in the INM. FRAP experiments with GFP-Src1 cells suggested that at least a fraction of the protein could be stably engaged in forming the nuclear lamina together with the Dictyostelium lamin NE81. Both a BioID proximity assay and mis-localization of soluble, truncated mRFP-Src1 at cytosolic clusters consisting of an intentionally mis-localized mutant of GFP-NE81 confirmed an interaction of Src1 and NE81. Expression GFP-Src11–646, a fragment C-terminally truncated after the first transmembrane domain, disrupted interaction of nuclear membranes with the nuclear lamina, as cells formed protrusions of the NE that were dependent on cytoskeletal pulling forces. Protrusions were dependent on intact microtubules but not actin filaments. Our results indicate that Src1 is required for integrity of the NE and highlight Dictyostelium as a promising model for the evolution of nuclear architecture. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 263 KW - Dictyostelium KW - HeH-protein KW - LEM-domain protein KW - lamin KW - nuclear lamina KW - nucleolus KW - nucleus Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-97033 ER - TY - JOUR A1 - Batsios, Petros A1 - Ren, Xiang A1 - Baumann, Otto A1 - Larochelle, Denis A. A1 - Gräf, Ralph T1 - Src1 is a Protein of the Inner Nuclear Membrane Interacting with the Dictyostelium Lamin NE81 JF - Cells N2 - The nuclear envelope (NE) consists of the outer and inner nuclear membrane (INM), whereby the latter is bound to the nuclear lamina. Src1 is a Dictyostelium homologue of the helix-extension-helix family of proteins, which also includes the human lamin-binding protein MAN1. Both endogenous Src1 and GFP-Src1 are localized to the NE during the entire cell cycle. Immuno-electron microscopy and light microscopy after differential detergent treatment indicated that Src1 resides in the INM. FRAP experiments with GFP-Src1 cells suggested that at least a fraction of the protein could be stably engaged in forming the nuclear lamina together with the Dictyostelium lamin NE81. Both a BioID proximity assay and mis-localization of soluble, truncated mRFP-Src1 at cytosolic clusters consisting of an intentionally mis-localized mutant of GFP-NE81 confirmed an interaction of Src1 and NE81. Expression GFP-Src11–646, a fragment C-terminally truncated after the first transmembrane domain, disrupted interaction of nuclear membranes with the nuclear lamina, as cells formed protrusions of the NE that were dependent on cytoskeletal pulling forces. Protrusions were dependent on intact microtubules but not actin filaments. Our results indicate that Src1 is required for integrity of the NE and highlight Dictyostelium as a promising model for the evolution of nuclear architecture. KW - Dictyostelium KW - lamin KW - nuclear lamina KW - nucleus KW - nucleolus KW - HeH-protein KW - LEM-domain protein Y1 - 2016 U6 - https://doi.org/10.3390/cells5010013 SN - 2073-4409 VL - 5 IS - 1 PB - MDPI CY - Basel ER - TY - JOUR A1 - Malinova, Irina A1 - Alseekh, Saleh A1 - Feil, Regina A1 - Fernie, Alisdair A1 - Baumann, Otto A1 - Schoettler, Mark Aurel A1 - Lunn, John Edward A1 - Fettke, Jörg T1 - Starch Synthase 4 and Plastidal Phosphorylase Differentially Affect Starch Granule Number and Morphology JF - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants N2 - The process of starch granule formation in leaves of Arabidopsis ( Arabidopsis thaliana) is obscure. Besides STARCH SYNTHASE4 (SS4), the PLASTIDIAL PHOSPHORYLASE (PHS1) also seems to be involved, since dpe2-1/phs1a double mutants lacking both PHS1 and the cytosolic DISPROPORTIONATING ENZYME2 (DPE2) displayed only one starch granule per chloroplast under normal growth conditions. For further studies, a dpe2-1/phs1a/ss4 triple mutant and various combinations of double mutants were generated and metabolically analyzed with a focus on starch metabolism. The dpe2-1/phs1a/ ss4 mutant revealed a massive starch excess phenotype. Furthermore, these plants grown under 12 h of light/12 h of dark harbored a single large and spherical starch granule per plastid. The number of starch granules was constant when the light/dark regime was altered, but this was not observed in the parental lines. With regard to growth, photosynthetic parameters, and metabolic analyses, the triple mutant additionally displayed alterations in comparison with ss4 and dpe21/phs1a. The results clearly illustrate that PHS1 and SS4 are differently involved in starch granule formation and do not act in series. However, SS4 appears to exert a stronger influence. In connection with the characterized double mutants, we discuss the generation of starch granules and the observed formation of spherical starch granules. Y1 - 2017 U6 - https://doi.org/10.1104/pp.16.01859 SN - 0032-0889 SN - 1532-2548 VL - 174 SP - 73 EP - 85 PB - American Society of Plant Physiologists CY - Rockville ER - TY - JOUR A1 - Voss, Martin A1 - Schmidt, Ruth A1 - Walz, Bernd A1 - Baumann, Otto T1 - Stimulus-induced translocation of the protein kinase A catalytic subunit to the apical membrane in blowfly salivary glands N2 - Secretion in blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT), which activates the InsP(3)/Ca2+ pathway and the cAMP/protein kinase A (PKA) pathway in the secretory cells. The latter signaling cascade induces the activation of a vacuolar H+-ATPase on the apical membrane. Here, we have determined the distribution of PKA by using antibodies against the PKA regulatory subunit-II (PKA-RII) and the PKA catalytic subunit (PKA-C) of Drosophila. PKA is present in high concentrations within the secretory cells. PKA-RII and PKA-C co-distribute in non-stimulated glands, being enriched in the basal portion of the secretory cells. Exposure to 8-CPT-cAMP or 5-HT induces the translocation of PKA-C to the apical membrane, whereas the PKA-RII distribution remains unchanged. The recruitment of PKA-C to the apical membrane corroborates our hypothesis that vacuolar H+-ATPase, which is enriched in this membrane domain, is a target protein for PKA. Y1 - 2009 UR - http://www.springerlink.com/content/100524 U6 - https://doi.org/10.1007/s00441-008-0673-x SN - 0302-766X ER - TY - JOUR A1 - Walz, Bernd A1 - Baumann, Otto T1 - Structure and cellular physiology of Ca2+ stores in invertebrate photoreceptors Y1 - 1995 ER - TY - THES A1 - Baumann, Otto T1 - Strukturelle und funktionelle Organisation von Insekten-Photorezeptoren Y1 - 1998 CY - Potsdam ER - TY - GEN A1 - Grafe, Marianne A1 - Batsios, Petros A1 - Meyer, Irene A1 - Lisin, Daria A1 - Baumann, Otto A1 - Goldberg, Martin W. A1 - Gräf, Ralph T1 - Supramolecular Structures of the Dictyostelium Lamin NE81 T2 - Potsprint der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe N2 - Nuclear lamins are nucleus-specific intermediate filaments (IF) found at the inner nuclear membrane (INM) of the nuclear envelope (NE). Together with nuclear envelope transmembrane proteins, they form the nuclear lamina and are crucial for gene regulation and mechanical robustness of the nucleus and the whole cell. Recently, we characterized Dictyostelium NE81 as an evolutionarily conserved lamin-like protein, both on the sequence and functional level. Here, we show on the structural level that the Dictyostelium NE81 is also capable of assembling into filaments, just as metazoan lamin filament assemblies. Using field-emission scanning electron microscopy, we show that NE81 expressed in Xenopous oocytes forms filamentous structures with an overall appearance highly reminiscent of Xenopus lamin B2. The in vitro assembly properties of recombinant His-tagged NE81 purified from Dictyostelium extracts are very similar to those of metazoan lamins. Super-resolution stimulated emission depletion (STED) and expansion microscopy (ExM), as well as transmission electron microscopy of negatively stained purified NE81, demonstrated its capability of forming filamentous structures under low-ionic-strength conditions. These results recommend Dictyostelium as a non-mammalian model organism with a well-characterized nuclear envelope involving all relevant protein components known in animal cells. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 682 KW - lamin KW - NE81 KW - Dictyostelium KW - nuclear envelope KW - nuclear lamina KW - expansion microscopy Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-425976 SN - 1866-8372 IS - 682 ER - TY - JOUR A1 - Grafe, Marianne A1 - Batsios, Petros A1 - Meyer, Irene A1 - Lisin, Daria A1 - Baumann, Otto A1 - Goldberg, Martin W. A1 - Gräf, Ralph T1 - Supramolecular Structures of the Dictyostelium Lamin NE81 JF - Cells N2 - Nuclear lamins are nucleus-specific intermediate filaments (IF) found at the inner nuclear membrane (INM) of the nuclear envelope (NE). Together with nuclear envelope transmembrane proteins, they form the nuclear lamina and are crucial for gene regulation and mechanical robustness of the nucleus and the whole cell. Recently, we characterized Dictyostelium NE81 as an evolutionarily conserved lamin-like protein, both on the sequence and functional level. Here, we show on the structural level that the Dictyostelium NE81 is also capable of assembling into filaments, just as metazoan lamin filament assemblies. Using field-emission scanning electron microscopy, we show that NE81 expressed in Xenopous oocytes forms filamentous structures with an overall appearance highly reminiscent of Xenopus lamin B2. The in vitro assembly properties of recombinant His-tagged NE81 purified from Dictyostelium extracts are very similar to those of metazoan lamins. Super-resolution stimulated emission depletion (STED) and expansion microscopy (ExM), as well as transmission electron microscopy of negatively stained purified NE81, demonstrated its capability of forming filamentous structures under low-ionic-strength conditions. These results recommend Dictyostelium as a non-mammalian model organism with a well-characterized nuclear envelope involving all relevant protein components known in animal cells. KW - lamin KW - NE81 KW - Dictyostelium KW - nuclear envelope KW - nuclear lamina KW - expansion microscopy Y1 - 2019 U6 - https://doi.org/10.3390/cells8020162 SN - 2073-4409 VL - 8 IS - 2 PB - Molecular Diversity Preservation International CY - Basel ER - TY - JOUR A1 - Walz, Bernd A1 - Baumann, Otto A1 - Krach, Christian A1 - Baumann, Arnd A1 - Blenau, Wolfgang T1 - The aminergic control of cockroach salivary glands N2 - The acinar salivary glands of cockroaches receive a dual innervation from the subesophageal ganglion and the stomatogastric nervous system. Acinar cells are surrounded by a plexus of dopaminergic and serotonergic varicose fibers. In addition, seroton-ergic terminals lie deep in the extracellulor spaces between acinar cells. Excitation-secretion coupling in cockroach salivary glands is stimulated by both dopamine and serotonin. These monoamines cause increases in the intracellular concentrations of cAMP and Ca2+. Stimulation of the glands by serotonin results in the production of a protein-rich saliva, whereas stimulation by dopamine results in saliva that is protein-free. Thus, two elementary secretary processes, namely electrolyte/water secretion and protein secretion, are triggered by different aminergic transmitters. Because of its simplicity and experimental accessibility, cockroach salivary glands have been used extensively as a model system to study the cellular actions of biogenic amines and to examine the pharmacological properties of biogenic amine receptors. In this review, we summarize current knowledge concerning the aminergic control of cockroach salivary glands and discuss our efforts to characterize Periplaneta biogenic amine receptors molecularly Y1 - 2006 UR - 1960 = Doi 10.1002/Arch.20128 ER - TY - JOUR A1 - Baumann, Otto A1 - Walz, Bernd T1 - The blowfly salivary gland - A model system for analyzing the regulation of plasma membrane V-ATPase JF - Journal of insect physiology N2 - Vacuolar H+-ATPases (V-ATPases) are heteromultimeric proteins that use the energy of ATP hydrolysis for the electrogenic transport of protons across membranes. They are common to all eukaryotic cells and are located in the plasma membrane or in membranes of acid organelles. In many insect epithelia, V-ATPase molecules reside in large numbers in the apical plasma membrane and create an electrochemical proton gradient that is used for the acidification or alkalinization of the extracellular space, the secretion or reabsorption of ions and fluids, the import of nutrients, and diverse other cellular activities. Here, we summarize our results on the functions and regulation of V-ATPase in the tubular salivary gland of the blowfly Calliphora vicina. In this gland, V-ATPase activity energizes the secretion of a KCl-rich saliva in response to the neurohormone serotonin (5-HT). Because of particular morphological and physiological features, the blowfly salivary glands are a superior and exemplary system for the analysis of the intracellular signaling pathways and mechanisms that modulate V-ATPase activity and solute transport in an insect epithelium. KW - Vacuolar-type H+-ATPase KW - Insect epithelia KW - Reversible assembly KW - cAMP KW - Phosphorylation KW - Calliphora vicina Y1 - 2012 U6 - https://doi.org/10.1016/j.jinsphys.2011.11.015 SN - 0022-1910 VL - 58 IS - 4 SP - 450 EP - 458 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Baumann, Otto A1 - Walz, Bernd T1 - The endoplasmic reticulum of animal cells and its organization into structural and functional domains Y1 - 2001 ER - TY - JOUR A1 - Baumann, Otto T1 - The Golgi apparatus in honeybee photoreceptor cells: Structural organization and spatial relationship to microtubules and actin filaments Y1 - 1998 ER - TY - JOUR A1 - Marelja, Zvonimir A1 - Chowdhury, Mita Mullick A1 - Dosche, Carsten A1 - Hille, Carsten A1 - Baumann, Otto A1 - Löhmannsröben, Hans-Gerd A1 - Leimkühler, Silke T1 - The L-cysteine desulfurase NFS1 is localized in the cytosol where it provides the sulfur for molybdenum cofactor biosynthesis in humans JF - PLoS one N2 - In humans, the L-cysteine desulfurase NFS1 plays a crucial role in the mitochondrial iron-sulfur cluster biosynthesis and in the thiomodification of mitochondrial and cytosolic tRNAs. We have previously demonstrated that purified NFS1 is able to transfer sulfur to the C-terminal domain of MOCS3, a cytosolic protein involved in molybdenum cofactor biosynthesis and tRNA thiolation. However, no direct evidence existed so far for the interaction of NFS1 and MOCS3 in the cytosol of human cells. Here, we present direct data to show the interaction of NFS1 and MOCS3 in the cytosol of human cells using Forster resonance energy transfer and a split-EGFP system. The colocalization of NFS1 and MOCS3 in the cytosol was confirmed by immunodetection of fractionated cells and localization studies using confocal fluorescence microscopy. Purified NFS1 was used to reconstitute the lacking molybdoenzyme activity of the Neurospora crassa nit-1 mutant, giving additional evidence that NFS1 is the sulfur donor for Moco biosynthesis in eukaryotes in general. Y1 - 2013 U6 - https://doi.org/10.1371/journal.pone.0060869 SN - 1932-6203 VL - 8 IS - 4 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Guljamow, Arthur A1 - Delissen, Friedmar A1 - Baumann, Otto A1 - Thuenemann, Andreas F. A1 - Dittmann-Thünemann, Elke T1 - Unique properties of eukaryote-type actin and profilin horizontally transferred to cyanobacteria JF - PLoS one N2 - A eukaryote-type actin and its binding protein profilin encoded on a genomic island in the cyanobacterium Microcystis aeruginosa PCC 7806 co-localize to form a hollow, spherical enclosure occupying a considerable intracellular space as shown by in vivo fluorescence microscopy. Biochemical and biophysical characterization reveals key differences between these proteins and their eukaryotic homologs. Small-angle X-ray scattering shows that the actin assembles into elongated, filamentous polymers which can be visualized microscopically with fluorescent phalloidin. Whereas rabbit actin forms thin cylindrical filaments about 100 mu m in length, cyanobacterial actin polymers resemble a ribbon, arrest polymerization at 510 lam and tend to form irregular multi-strand assemblies. While eukaryotic profilin is a specific actin monomer binding protein, cyanobacterial profilin shows the unprecedented property of decorating actin filaments. Electron micrographs show that cyanobacterial profilin stimulates actin filament bundling and stabilizes their lateral alignment into heteropolymeric sheets from which the observed hollow enclosure may be formed. We hypothesize that adaptation to the confined space of a bacterial cell devoid of binding proteins usually regulating actin polymerization in eukaryotes has driven the co-evolution of cyanobacterial actin and profilin, giving rise to an intracellular entity. Y1 - 2012 U6 - https://doi.org/10.1371/journal.pone.0029926 SN - 1932-6203 VL - 7 IS - 1 SP - 221 EP - 231 PB - PLoS CY - San Fransisco ER - TY - GEN A1 - Voss, Martin A1 - Blenau, Wolfgang A1 - Walz, Bernd A1 - Baumann, Otto T1 - V-ATPase deactivation in blowfly salivary glands is mediated by protein phosphatase 2C N2 - The activity of vacuolar H+-ATPase (V-ATPase) in the apical membrane of blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT). 5-HT induces, via protein kinase A, the phosphorylation of V-ATPase subunit C and the assembly of V-ATPase holoenzymes. The protein phosphatase responsible for the dephosphorylation of subunit C and V-ATPase inactivation is not as yet known. We show here that inhibitors of protein phosphatases PP1 and PP2A (tautomycin, ocadaic acid) and PP2B (cyclosporin A, FK-506) do not prevent V-ATPase deactivation and dephosphorylation of subunit C. A decrease in the intracellular Mg2+ level caused by loading secretory cells with EDTA-AM leads to the activation of proton pumping in the absence of 5-HT, prolongs the 5-HT-induced response in proton pumping, and inhibits the dephosphorylation of subunit C. Thus, the deactivation of V-ATPase is most probably mediated by a protein phosphatase that is insensitive to okadaic acid and that requires Mg2+, namely, a member of the PP2C protein family. By molecular biological techniques, we demonstrate the expression of at least two PP2C protein family members in blowfly salivary glands. © 2009 Wiley Periodicals, Inc. KW - vacuolar H+-ATPase KW - assembly KW - regulation KW - protein phosphatise KW - dephosphorylation Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44360 ER -