@article{WalzBaumannKrachetal.2006,
  author    = {Walz, Bernd and Baumann, Otto and Krach, Christian and Baumann, Arnd and Blenau, Wolfgang},
  title     = {The aminergic control of cockroach salivary glands},
  year      = {2006},
  abstract  = {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},
  language  = {en}
}
@article{RoeserJordanBalfanzetal.2012,
  author    = {R{\"o}ser, Claudia and Jordan, Nadine and Balfanz, Sabine and Baumann, Arnd and Walz, Bernd and Baumann, Otto and Blenau, Wolfgang},
  title     = {Molecular and pharmacological characterization of serotonin 5-HT2 alpha and 5-HT7 receptors in the salivary glands of the blowfly calliphora vicina},
  series = {PLoS one},
  volume    = {7},
  journal   = {PLoS one},
  number    = {11},
  publisher = {PLoS},
  address   = {San Fransisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0049459},
  pages     = {13},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}
@article{BlankenburgBalfanzHayashietal.2015,
  author    = {Blankenburg, Stefanie and Balfanz, Sabine and Hayashi, Y. and Shigenobu, S. and Miura, T. and Baumann, Otto and Baumann, Arnd and Blenau, Wolfgang},
  title     = {Cockroach GABA(B) receptor subtypes: Molecular characterization, pharmacological properties and tissue distribution},
  series = {Neuropharmacology},
  volume    = {88},
  journal   = {Neuropharmacology},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0028-3908},
  doi       = {10.1016/j.neuropharm.2014.08.022},
  pages     = {134 -- 144},
  year      = {2015},
  abstract  = {gamma-aminobutyric acid (GABA) is the predominant inhibitory neurotransmitter in the central nervous system (CNS). Its effects are mediated by either ionotropic GABA(A) receptors or metabotropic GABA(B) receptors. GABA(B) receptors regulate, via Gi/o, G-proteins, ion channels, and adenylyl cyclases. In humans, GABA(B) receptor subtypes are involved in the etiology of neurologic and psychiatric disorders. In arthropods, however, these members of the G-protein-coupled receptor family are only inadequately characterized. Interestingly, physiological data have revealed important functions of GABA(B) receptors in the American cockroach, Periplaneta americana. We have cloned cDNAs coding for putative GABA(B) receptor subtypes 1 and 2 of P. americana (PeaGB1 and PeaGB2). When both receptor proteins are co-expressed in mammalian cells, activation of the receptor heteromer with GABA leads to a dose-dependent decrease in cAMP production. The pharmacological profile differs from that of mammalian and Drosophila GABA(B) receptors. Western blot analyses with polyclonal antibodies have revealed the expression of PeaGB1 and PeaGB2 in the CNS of the American cockroach. In addition to the widespread distribution in the brain, PeaGB1 is expressed in salivary glands and male accessory glands. Notably, PeaGB1-like immunoreactivity has been detected in the GABAergic salivary neuron 2, suggesting that GABA(B) receptors act as autoreceptors in this neuron.},
  language  = {en}
}
@article{DamesZimmermannSchmidtetal.2006,
  author    = {Dames, Petra and Zimmermann, Bernhard and Schmidt, Ruth and Rein, Julia and Voss, Martin and Schewe, Bettina and Walz, Bernd and Baumann, Otto},
  title     = {cAMP regulates plasma membrane vacuolar-type H+-ATPase assembly and activity in blowfly salivary glands},
  issn      = {0027-8424},
  doi       = {10.1073/pnas.0600011103},
  year      = {2006},
  abstract  = {Reversible assembly of the V0V1 holoenzyme from V-0 and V-1 subcomplexes is a widely used mechanism for regulation of vacuolar-type H+-ATPases (V-ATPases) in animal cells. in the blowfly (Calliphora vicina) salivary gland, V- ATPase is located in the apical membrane of the secretory cells and energizes the secretion of a KCl-rich saliva in response to the hormone serotonin. We have examined whether the CAMP pathway, known to be activated by serotonin, controls V-ATPase assembly and activity. Fluorescence measurements of pH changes at the luminal surface of isolated glands demonstrate that CAMP, Sp-adenosine-3',5'-cyclic monophosphorothioate, or forskolin, similar to serotonin, cause V-ATPase-dependent luminal acidification. In addition, V-ATPase-dependent ATP hydrolysis increases upon treatment with these agents. Immunofluorescence microscopy and pelleting assays have demonstrated further that V, components become translocated from the cytoplasm to the apical membrane and V-ATPase holoenzymes are assembled at the apical membrane during conditions that increase intracellular cAMP. Because these actions occur without a change in cytosolic Ca2+, our findings suggest that the cAMP pathway mediates the reversible assembly and activation of V-ATPase molecules at the apical membrane upon hormonal stimulus},
  language  = {en}
}
@article{Baumann2004,
  author    = {Baumann, Otto},
  title     = {Konventionelle Fluoreszenzmikroskopie : Theorie und Anwendungsm{\"o}glichkeiten},
  year      = {2004},
  language  = {de}
}
@article{Baumann2004,
  author    = {Baumann, Otto},
  title     = {Spatial pattern of nonmuscle myosin-II distribution during the development of the Drosophila compound eye and implications for retinal morphogenesis},
  year      = {2004},
  abstract  = {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},
  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{DamesSchmidtWalzetal.2004,
  author    = {Dames, Petra and Schmidt, R. and Walz, Bernd and Baumann, Otto},
  title     = {Regulation of vacuolar-type H+-ATPase (vATPase) in blowfly salivary glands},
  issn      = {0171-9335},
  year      = {2004},
  language  = {en}
}
@article{ZimmermannDamesWalzetal.2003,
  author    = {Zimmermann, Bernhard and Dames, Petra and Walz, Bernd and Baumann, Otto},
  title     = {Distribution and serotonin-induced activation of vacuolar-type H+-ATPase in the salivary glands of the blowfly Calliphora vicina},
  year      = {2003},
  language  = {en}
}
@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}
}
@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}
}
@misc{GrafeBatsiosMeyeretal.2019,
  author    = {Grafe, Marianne and Batsios, Petros and Meyer, Irene and Lisin, Daria and Baumann, Otto and Goldberg, Martin W. and Gr{\"a}f, Ralph},
  title     = {Supramolecular Structures of the Dictyostelium Lamin NE81},
  series = {Potsprint der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Potsprint der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {682},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-42597},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-425976},
  pages     = {17},
  year      = {2019},
  abstract  = {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.},
  language  = {en}
}
@article{GrafeBatsiosMeyeretal.2019,
  author    = {Grafe, Marianne and Batsios, Petros and Meyer, Irene and Lisin, Daria and Baumann, Otto and Goldberg, Martin W. and Gr{\"a}f, Ralph},
  title     = {Supramolecular Structures of the Dictyostelium Lamin NE81},
  series = {Cells},
  volume    = {8},
  journal   = {Cells},
  number    = {2},
  publisher = {Molecular Diversity Preservation International},
  address   = {Basel},
  issn      = {2073-4409},
  doi       = {10.3390/cells8020162},
  pages     = {17},
  year      = {2019},
  abstract  = {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.},
  language  = {en}
}
@article{BatsiosPeterBaumannetal.2012,
  author    = {Batsios, Petros and Peter, Tatjana and Baumann, Otto and Stick, Reimer and Meyer, Irene and Gr{\"a}f, Ralph},
  title     = {A lamin in lower eukaryotes?},
  series = {Nucleus},
  volume    = {3},
  journal   = {Nucleus},
  number    = {3},
  publisher = {Landes Bioscience},
  address   = {Austin},
  issn      = {1949-1034},
  doi       = {10.4161/nucl.20149},
  pages     = {237 -- 243},
  year      = {2012},
  abstract  = {Lamins are the major components of the nuclear lamina and serve not only as a mechanical support, but are also involved in chromatin organization, epigenetic regulation, transcription and mitotic events. Despite these universal tasks, lamins have so far been found only in metazoans. Yet, recently we have identified Dictyostelium NE81 as the first lamin-like protein in a lower eukaryote. Based on the current knowledge, we draw a model for nuclear envelope organization in Dictyostelium in this Extra View and we review the experimental data that justified this classification. Furthermore we provide unpublished data underscoring the requirement of posttranslational CaaX-box processing for proper protein localization at the nuclear envelope. Sequence comparison of NE81 sequences from four Dictyostelia with bona fide lamins illustrates the evolutional relationship between these proteins. Under certain conditions these usually unicellular social amoebae congregate to form a multicellular body. We propose that the evolution of the lamin-like NE81 went along with the invention of multicellularity.},
  language  = {en}
}
@article{SamereierBaumannMeyeretal.2011,
  author    = {Samereier, Matthias and Baumann, Otto and Meyer, Irene and Gr{\"a}f, Ralph},
  title     = {Analysis of dictyostelium TACC reveals differential interactions with CP224 and unusual dynamics of dictyostelium microtubules},
  series = {Cellular and molecular life sciences},
  volume    = {68},
  journal   = {Cellular and molecular life sciences},
  number    = {2},
  publisher = {Springer},
  address   = {Basel},
  issn      = {1420-682X},
  doi       = {10.1007/s00018-010-0453-0},
  pages     = {275 -- 287},
  year      = {2011},
  abstract  = {We have localized TACC to the microtubule-nucleating centrosomal corona and to microtubule plus ends. Using RNAi we proved that Dictyostelium TACC promotes microtubule growth during interphase and mitosis. For the first time we show in vivo that both TACC and XMAP215 family proteins can be differentially localized to microtubule plus ends during interphase and mitosis and that TACC is mainly required for recruitment of an XMAP215-family protein to interphase microtubule plus ends but not for recruitment to centrosomes and kinetochores. Moreover, we have now a marker to study dynamics and behavior of microtubule plus ends in living Dictyostelium cells. In a combination of live cell imaging of microtubule plus ends and fluorescence recovery after photobleaching (FRAP) experiments of GFP-alpha-tubulin cells we show that Dictyostelium microtubules are dynamic only in the cell periphery, while they remain stable at the centrosome, which also appears to harbor a dynamic pool of tubulin dimers.},
  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}
}
@misc{BatsiosRenBaumannetal.2016,
  author    = {Batsios, Petros and Ren, Xiang and Baumann, Otto and Larochelle, Denis A. and Gr{\"a}f, Ralph},
  title     = {Src1 is a Protein of the Inner Nuclear Membrane Interacting with the Dictyostelium Lamin NE81},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-97033},
  pages     = {15},
  year      = {2016},
  abstract  = {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.},
  language  = {en}
}
@article{BatsiosRenBaumannetal.2016,
  author    = {Batsios, Petros and Ren, Xiang and Baumann, Otto and Larochelle, Denis A. and Gr{\"a}f, Ralph},
  title     = {Src1 is a Protein of the Inner Nuclear Membrane Interacting with the Dictyostelium Lamin NE81},
  series = {Cells},
  volume    = {5},
  journal   = {Cells},
  number    = {1},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2073-4409},
  doi       = {10.3390/cells5010013},
  year      = {2016},
  abstract  = {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.},
  language  = {en}
}
@article{SchulzBaumannSamereieretal.2009,
  author    = {Schulz, Irene and Baumann, Otto and Samereier, Matthias and Zoglmeier, Christine and Gr{\"a}f, Ralph},
  title     = {Dictyostelium Sun1 is a dynamic membrane protein of both nuclear membranes and required for centrosomal association with clustered centromeres},
  issn      = {0171-9335},
  doi       = {10.1016/j.ejcb.2009.06.003},
  year      = {2009},
  abstract  = {Centrosomal attachment to nuclei is crucial for proper mitosis and nuclear positioning in various organisms, and generally involves Sun-family proteins located at the inner nuclear envelope. There is still no common scheme for the outer nuclear membrane proteins interacting with Sun I in centrosome/nucleus attachment. Here we propose a model in which Sun1 mediates a physical link between centrosomes and clustered centromeres through both nuclear membranes in Dictyostelium. For the first time we provide a detailed microscopic analysis of the centrosomal and nuclear envelope localization of endogenous Dictyostelium Sun1 during interphase and mitosis. By immunogold electron microscopy we show that Sun1 is a resident of both nuclear membranes. Disruption of Sun1 function by overexpression of full-length GFP-Sun1 or a GFP-Sun-domain deletion construct revealed not only the established function in centrosome/nucleus attachment and maintenance of ploidy, but also a requirement of Sun1 for the association of the centromere cluster with the centrosome. Live-cell imaging visualized the occurrence of mitotic defects, and demonstrated the requirement of microtubules for dynamic distance changes between centrosomes and nuclei. FRAP analysis revealed at least two populations of Sun1, with an immobile fraction associated with the centrosome, and a mobile fraction in the nuclear envelope.},
  language  = {en}
}
@article{KuhnertBaumannMeyeretal.2012,
  author    = {Kuhnert, Oliver and Baumann, Otto and Meyer, Irene and Gr{\"a}f, Ralph},
  title     = {CP55, a novel key component of centrosomal organization in dictyostelium},
  series = {Cellular and molecular life sciences},
  volume    = {69},
  journal   = {Cellular and molecular life sciences},
  number    = {21},
  publisher = {Springer},
  address   = {Basel},
  issn      = {1420-682X},
  doi       = {10.1007/s00018-012-1040-3},
  pages     = {3651 -- 3664},
  year      = {2012},
  abstract  = {Dictyostelium centrosomes consist of a layered core structure surrounded by a microtubule-nucleating corona. At the G2/M transition, the corona dissociates and the core structure duplicates, yielding two spindle pole bodies. Finally, in telophase, the spindle poles mature into two new, complete centrosomes. CP55 was identified in a centrosomal proteome analysis. It is a component of the centrosomal core structure, and persists at the centrosome throughout the entire cell cycle. FRAP experiments revealed that during interphase the majority of centrosomal GFP-CP55 is immobile, which indicates a structural task of CP55 at the centrosome. The CP55null mutant is characterized by increased ploidy, a less structured, slightly enlarged corona, and by supernumerary, cytosolic MTOCs, containing only corona proteins and lacking a core structure. Live cell imaging showed that supernumerary MTOCs arise in telophase. Lack of CP55 also caused premature recruitment of the corona organizer CP148 to mitotic spindle poles, already in metaphase instead of telophase. Forces transmitted through astral microtubules may expel prematurely acquired or loosely attached corona fragments into the cytosol, where they act as independent MTOCs. CP55null cells were also impaired in growth, most probably due to difficulties in centrosome splitting during prophase. Furthermore, although they were still capable of phagocytosis, they appeared unable to utilize phagocytosed nutrients. This inability may be attributed to their partially disorganized Golgi apparatus.},
  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}
}
@article{KruegerBatsiosBaumannetal.2012,
  author    = {Kr{\"u}ger, Anne and Batsios, Petros and Baumann, Otto and Luckert, Eva and Schwarz, Heinz and Stick, Reimer and Meyer, Irene and Gr{\"a}f, Ralph},
  title     = {Characterization of NE81, the first lamin-like nucleoskeleton protein in a unicellular organism},
  series = {Molecular biology of the cell : the official publication of the American Society for Cell Biology},
  volume    = {23},
  journal   = {Molecular biology of the cell : the official publication of the American Society for Cell Biology},
  number    = {2},
  publisher = {American Society for Cell Biology},
  address   = {Bethesda},
  issn      = {1059-1524},
  doi       = {10.1091/mbc.E11-07-0595},
  pages     = {360 -- 370},
  year      = {2012},
  abstract  = {Lamins build the nuclear lamina and are required for chromatin organization, gene expression, cell cycle progression, and mechanical stabilization. Despite these universal functions, lamins have so far been found only in metazoans. We have identified protein NE81 in Dictyostelium, which has properties that justify its denomination as a lamin-like protein in a lower eukaryote. This is based on its primary structure, subcellular localization, and regulation during mitosis, and its requirement of the C-terminal CaaX box as a posttranslational processing signal for proper localization. Our knockout and overexpression mutants revealed an important role for NE81 in nuclear integrity, chromatin organization, and mechanical stability of cells. All our results are in agreement with a role for NE81 in formation of a nuclear lamina. This function is corroborated by localization of Dictyostelium NE81 at the nuclear envelope in human cells. The discovery of a lamin-like protein in a unicellular organism is not only intriguing in light of evolution, it may also provide a simple experimental platform for studies of the molecular basis of laminopathies.},
  language  = {en}
}
@article{BarchewitzGuljamowMeissneretal.2019,
  author    = {Barchewitz, Tino and Guljamow, Arthur and Meißner, Sven and Timm, Stefan and Henneberg, Manja and Baumann, Otto and Hagemann, Martin and Dittmann, Elke},
  title     = {Non-canonical localization of RubisCO under high-light conditions in the toxic cyanobacterium Microcystis aeruginosa PCC7806},
  series = {Environmental microbiology},
  volume    = {21},
  journal   = {Environmental microbiology},
  number    = {12},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {1462-2912},
  doi       = {10.1111/1462-2920.14837},
  pages     = {4836 -- 4851},
  year      = {2019},
  abstract  = {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.},
  language  = {en}
}
@misc{SchmidtBaumannWalz2008,
  author    = {Schmidt, Ruth and Baumann, Otto and Walz, Bernd},
  title     = {cAMP potentiates InsP3-induced Ca2+ release from the endoplasmic reticulum in blowfly salivary glands},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  number    = {842},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-42977},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429770},
  pages     = {13},
  year      = {2008},
  abstract  = {Background Serotonin induces fluid secretion from Calliphora salivary glands by the parallel activation of the InsP3/Ca2+ and cAMP signaling pathways. We investigated whether cAMP affects 5-HT-induced Ca2+ signaling and InsP3-induced Ca2+ release from the endoplasmic reticulum (ER). Results Increasing intracellular cAMP level by bath application of forskolin, IBMX or cAMP in the continuous presence of threshold 5-HT concentrations converted oscillatory [Ca2+]i changes into a sustained increase. Intraluminal Ca2+ measurements in the ER of ß-escin-permeabilized glands with mag-fura-2 revealed that cAMP augmented InsP3-induced Ca2+ release in a concentration-dependent manner. This indicated that cAMP sensitized the InsP3 receptor Ca2+ channel for InsP3. By using cAMP analogs that activated either protein kinase A (PKA) or Epac and the application of PKA-inhibitors, we found that cAMP-induced augmentation of InsP3-induced Ca2+ release was mediated by PKA not by Epac. Recordings of the transepithelial potential of the glands suggested that cAMP sensitized the InsP3/Ca2+ signaling pathway for 5-HT, because IBMX potentiated Ca2+-dependent Cl- transport activated by a threshold 5-HT concentration. Conclusion This report shows, for the first time for an insect system, that cAMP can potentiate InsP3-induced Ca2+ release from the ER in a PKA-dependent manner, and that this crosstalk between cAMP and InsP3/Ca2+ signaling pathways enhances transepithelial electrolyte transport.},
  language  = {en}
}
@misc{VossBlenauWalzetal.2009,
  author    = {Voss, Martin and Blenau, Wolfgang and Walz, Bernd and Baumann, Otto},
  title     = {V-ATPase deactivation in blowfly salivary glands is mediated by protein phosphatase 2C},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-44360},
  year      = {2009},
  abstract  = {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.},
  language  = {en}
}
@article{SchwarzeKellingMuelleretal.2012,
  author    = {Schwarze, Thomas and Kelling, Alexandra and M{\"u}ller, Holger and Trautmann, Michael and Klamroth, Tillmann and Baumann, Otto and Strauch, Peter and Holdt, Hans-J{\"u}rgen},
  title     = {N-2-Pyridinylmethyl-N '-arylmethyl-diaminomaleonitriles: New Highly Selective Chromogenic Chemodosimeters for Copper(II)},
  series = {Chemistry - a European journal},
  volume    = {18},
  journal   = {Chemistry - a European journal},
  number    = {34},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0947-6539},
  doi       = {10.1002/chem.201201731},
  pages     = {10506 -- 10510},
  year      = {2012},
  language  = {en}
}
@misc{BlenauRotteWitteetal.2009,
  author    = {Blenau, Wolfgang and Rotte, Cathleen and Witte, Jeannine and Baumann, Otto and Walz, Bernd},
  title     = {Source, topography and excitatory effects of GABAergic innervation in cockroach salivary glands},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-44353},
  year      = {2009},
  abstract  = {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.},
  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{VossFechnerWalzetal.2010,
  author    = {Voss, Martin and Fechner, Lennart and Walz, Bernd and Baumann, Otto},
  title     = {Calcineurin activity augments cAMP/PKA-dependent activation of V-ATPase in blowfly salivary glands},
  issn      = {0363-6143},
  doi       = {10.1152/ajpcell.00328.2009},
  year      = {2010},
  abstract  = {We have examined the role of the Ca2+-dependent protein phosphatase 2B (calcineurin) in the regulation of the vacuolar H+-ATPase (V-ATPase) in blowfly salivary glands. In response to the neurohormone serotonin [5-hydroxytryptamine (5-HT)] and under the mediation of the cAMP/PKA signaling pathway, the secretory cells assemble and activate V-ATPase molecules at the apical membrane. We demonstrate that the inhibition of calcineurin activity by cyclosporin A, by FK- 506, or by prevention of the elevation of Ca2+ diminishes the 5-HT-induced assembly and activation of V-ATPase. The effect of calcineurin on V-ATPase is mediated by the cAMP/PKA signaling pathway, with calcineurin acting upstream of PKA, because 1) cyclosporin A does not influence the 8-(4-chlorophenylthio) adenosine-3',5'-cyclic monophosphate (8-CPT-cAMP)-induced activation of V-ATPase, and 2) the 5-HT-induced rise in cAMP is highly reduced in the presence of cyclosporin A. Moreover, a Ca2+ rise evoked by the sarco(endo) plasmic reticulum Ca2+-ATPase (SERCA) inhibitor cyclopiazonic acid leads to an increase in intracellular cAMP concentration and a calcineurin-mediated PKA- dependent activation of V-ATPase. We propose that calcineurin activity mediates cross talk between the inositol 1,4,5- trisphosphate/Ca2+ and the cAMP/PKA signaling pathways, thereby augmenting the 5-HT-induced rise in cAMP and thus the cAMP/PKA-mediated activation of V-ATPase.},
  language  = {en}
}
@article{FechnerBaumannWalz2013,
  author    = {Fechner, Lennart and Baumann, Otto and Walz, Bernd},
  title     = {Activation of the cyclic AMP pathway promotes serotonin-induced Ca2+ oscillations in salivary glands of the blowfly Calliphora vicina},
  series = {Cell calcium},
  volume    = {53},
  journal   = {Cell calcium},
  number    = {2},
  publisher = {Churchill Livingstone},
  address   = {Edinburgh},
  issn      = {0143-4160},
  doi       = {10.1016/j.ceca.2012.10.004},
  pages     = {94 -- 101},
  year      = {2013},
  abstract  = {Ca2+ and cAMP signalling pathways interact in a complex manner at multiple sites. This crosstalk fine-tunes the spatiotemporal patterns of Ca2+ and cAMP signals. In salivary glands of the blowfly Calliphora vicina fluid secretion is stimulated by serotonin (5-hydroxytryptamine, 5-HT) via activation of two different 5-HT receptors coupled to the InsP(3)/Ca2+ (Cv5-HT2 alpha) or the cAMP pathway (Cv5-HT7), respectively. We have shown recently in permeabilized gland cells that cAMP sensitizes InsP(3)-induced Ca2+ release to InsP(3). Here we study the effects of the CAMP signalling pathway on 5-HT-induced oscillations in transepithelial potential (TEP) and in intracellular [Ca2+]. We show: (1) Blocking the activation of the cAMP pathway by cinanserin suppresses the generation of TEP and Ca2+ oscillations, (2) application of 8-CPT-cAMP in the presence of cinanserin restores 5-HT-induced TEP and Ca2+ oscillations, (3) 8-CPT-cAMP sensitizes the InsP(3)/Ca2+ signalling pathway to 5-HT and the Cv5-HT2 alpha, receptor agonist 5-MeOT, (4) 8-CPT-cAMP induces Ca2+ oscillations in cells loaded with subthreshold concentrations of InsP(3), (5) inhibition of protein kinase A by H-89 abolishes 5-HT-induced TEP and Ca2+ spiking and mimics the effect of cinanserin. These results suggest that activation of the cyclic AMP pathway promotes the generation of 5-HT-induced Ca2+ oscillations in blowfly salivary glands.},
  language  = {en}
}
@article{Baumann1998,
  author    = {Baumann, Otto},
  title     = {The Golgi apparatus in honeybee photoreceptor cells: Structural organization and spatial relationship to microtubules and actin filaments},
  year      = {1998},
  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{Baumann1998,
  author    = {Baumann, Otto},
  title     = {Association of spectrin with a subcompartment of the endoplasmic reticulum in honeybee photoreceptor cells.},
  year      = {1998},
  language  = {en}
}
@article{StuermerBaumannWalz1995,
  author    = {St{\"u}rmer, Karoline and Baumann, Otto and Walz, Bernd},
  title     = {Actin-dependent light-induced translocation of mitochondria and ER cisternae in the photoreceptor cells of the locust schistocerca gregaria},
  year      = {1995},
  language  = {en}
}
@article{WalzBaumann1995,
  author    = {Walz, Bernd and Baumann, Otto},
  title     = {Structure and cellular physiology of Ca2+ stores in invertebrate photoreceptors},
  year      = {1995},
  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}
}
@article{BaumannBauer2013,
  author    = {Baumann, Otto and Bauer, Alexandra},
  title     = {Development of apical membrane organization and V-ATPase regulation in blowfly salivary glands},
  series = {The journal of experimental biology},
  volume    = {216},
  journal   = {The journal of experimental biology},
  number    = {7},
  publisher = {Company of Biologists Limited},
  address   = {Cambridge},
  issn      = {0022-0949},
  doi       = {10.1242/jeb.077420},
  pages     = {1225 -- 1234},
  year      = {2013},
  abstract  = {Secretory cells in blowfly salivary gland are specialized via morphological and physiological attributes in order to serve their main function, i.e. the transport of solutes at a high rate in response to a hormonal stimulus, namely serotonin (5-HT). This study examines the way that 5-HT-insensitive precursor cells differentiate into morphologically complex 5-HT-responsive secretory cells. By means of immunofluorescence microscopy, immunoblotting and measurements of the transepithelial potential changes, we show the following. (1) The apical membrane of the secretory cells becomes organized into an elaborate system of canaliculi and is folded into pleats during the last pupal day and the first day of adulthood. (2) The structural reorganization of the apical membrane is accompanied by an enrichment of actin filaments and phosphorylated ERM protein (phospho-moesin) at this membrane domain and by the deployment of the membrane-integral part of vacuolar-type H+-ATPase (V-ATPase). These findings suggest a role for phospho-moesin, a linker between actin filaments and membrane components, in apical membrane morphogenesis. (3) The assembly and activation of V-ATPase can be induced immediately after eclosion by way of 8-CPT-cAMP, a membrane-permeant cAMP analogue. (4) 5-HT, however, produces the assembly and activation of V-ATPase only in flies aged for at least 2 h after eclosion, indicating that, at eclosion, the 5-HT receptor/adenylyl cyclase/cAMP signalling pathway is inoperative upstream of cAMP. (5) 5-HT activates both the Ca2+ signalling pathway and the cAMP signalling cascade in fully differentiated secretory cells. However, the functionality of these signalling cascades does not seem to be established in a tightly coordinated manner during cell differentation.},
  language  = {en}
}
@article{MareljaChowdhuryDoscheetal.2013,
  author    = {Marelja, Zvonimir and Chowdhury, Mita Mullick and Dosche, Carsten and Hille, Carsten and Baumann, Otto and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Leimk{\"u}hler, Silke},
  title     = {The L-cysteine desulfurase NFS1 is localized in the cytosol where it provides the sulfur for molybdenum cofactor biosynthesis in humans},
  series = {PLoS one},
  volume    = {8},
  journal   = {PLoS one},
  number    = {4},
  publisher = {PLoS},
  address   = {San Fransisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0060869},
  pages     = {13},
  year      = {2013},
  abstract  = {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.},
  language  = {en}
}
@article{WalzBaumannZimmermannetal.1995,
  author    = {Walz, Bernd and Baumann, Otto and Zimmermann, Bernhard and Ciriacy-Wantrup, E.v.},
  title     = {Caffeine- and ryanodine-sensitive Ca2+-induced Ca2+ release from the endo plasmatic reticulum in honeybee photoreceptors},
  year      = {1995},
  language  = {en}
}
@article{BaumannLutz2006,
  author    = {Baumann, Otto and Lutz, Kathleen},
  title     = {Photoreceptor morphogenesis in the Drosophila compound eye : R1-R6 rhabdomeres become twisted just before eclosion},
  issn      = {0021-9967},
  doi       = {10.1002/Cne.21030},
  year      = {2006},
  abstract  = {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.},
  language  = {en}
}
@phdthesis{Baumann1998,
  author    = {Baumann, Otto},
  title     = {Strukturelle und funktionelle Organisation von Insekten-Photorezeptoren},
  address   = {Potsdam},
  pages     = {Getr. Z{\"a}hlung : Ill., graph. Darst.},
  year      = {1998},
  language  = {de}
}
@article{VossSchmidtWalzetal.2009,
  author    = {Voss, Martin and Schmidt, Ruth and Walz, Bernd and Baumann, Otto},
  title     = {Stimulus-induced translocation of the protein kinase A catalytic subunit to the apical membrane in blowfly salivary glands},
  issn      = {0302-766X},
  doi       = {10.1007/s00441-008-0673-x},
  year      = {2009},
  abstract  = {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.},
  language  = {en}
}
@article{BresnickWolffLongBaumannetal.1995,
  author    = {Bresnick, Anne R. and Wolff-Long, Vicki L. and Baumann, Otto and Pollard, Thomas D.},
  title     = {Phosphorylation of threonine-18 of the regulatory light chain dissociates the ATPase and motor properties of smooth muscle myosin II},
  issn      = {006-2960},
  year      = {1995},
  language  = {en}
}
@article{Baumann1997,
  author    = {Baumann, Otto},
  title     = {Biogenesis of surface domains in fly photoreceptor cells: Fine-structural analysis of the plasma membrane and immunolocalization of Na+, K+-ATPase und alpha-spectrin during cell differentiation.},
  year      = {1997},
  language  = {en}
}
@article{Baumann1997,
  author    = {Baumann, Otto},
  title     = {Distribution of Na+, K+-ATPase in photoreceptor cells of insects.},
  year      = {1997},
  language  = {en}
}
@article{BaumannMurphy1995,
  author    = {Baumann, Otto and Murphy, Douglas B.},
  title     = {Microtubule-associated movement of mitochondria and small particles in Acanthamoeba castellanii.},
  year      = {1995},
  language  = {en}
}
@article{BaumannSalvaterraTakeyasu2010,
  author    = {Baumann, Otto and Salvaterra, Paul M. and Takeyasu, Kunio},
  title     = {Developmental changes in beta-subunit composition of Na,K-ATPase in the Drosophila eye},
  issn      = {0302-766X},
  doi       = {10.1007/s00441-010-0948-x},
  year      = {2010},
  abstract  = {The Drosophila genome contains at least three loci for the Na,K-ATPase beta-subunit; however, only the protein products of nrv1 and nrv2 have been characterized hitherto. Here, we provide evidence that nrv3 also encodes for a functional Na,K-ATPase beta-subunit, as its protein product co-precipitates with the Na,K-ATPase alpha-subunit. Nrv3 expression in adult flies is restricted to the nervous system in which Nrv3 is enriched in selective types of sensory cells. Because Nrv3 expression is especially prominent in the compound eye, we have analyzed the subcellular and developmental distribution of Nrv3 within the visual cells and related this distribution to those of the alpha-subunit and of the beta-subunits Nrv1 and Nrv2. Prospective visual cells express Nrv2 in the third larval instar stage and during the first half of pupal development. During the last third of pupal life, Nrv3 gradually replaces Nrv2 as the Na,K-ATPase beta-subunit in the photoreceptor cells. Adult photoreceptors express Nrv3 as their major beta-subunit; the visual cells R1-R6 co-express Nrv2 at a low level, whereas R7 and R8 co-express Nrv1. Notably, beta-subunits do not co- distribute exactly with the alpha-subunit at some developmental stages, supporting the concept that the alpha-subunit and beta-subunit can exist in the plasma membrane without being engaged in alpha/beta heterodimers. The non-visual cells within the compound eye express almost exclusively Nrv2, which segregates together with the alpha-subunit to septate junctions throughout development.},
  language  = {en}
}
@article{HeindorffBaumann2014,
  author    = {Heindorff, Kristoffer and Baumann, Otto},
  title     = {Calcineurin is part of a negative feedback loop in the InsP(3)/Ca2+ signalling pathway in blowfly salivary glands},
  series = {Cell calcium},
  volume    = {56},
  journal   = {Cell calcium},
  number    = {3},
  publisher = {Churchill Livingstone},
  address   = {Edinburgh},
  issn      = {0143-4160},
  doi       = {10.1016/j.ceca.2014.07.009},
  pages     = {215 -- 224},
  year      = {2014},
  abstract  = {The ubiquitous InsP(3)/Ca2+ signalling pathway is modulated by diverse mechanisms, i.e. feedback of Ca2+ and interactions with other signalling pathways. In the salivary glands of the blowfly Calliphora vicina, the hormone serotonin (5-HT) causes a parallel rise in intracellular [Ca2+] and [cAMP] via two types of 5-HT receptors. We have shown recently that cAMP/protein kinase A (PKA) sensitizes InsP(3)-induced Ca2+ release. We have now identified the protein phosphatase that counteracts the effect of PKA on 5-HT-induced InsP(3)/Ca2+ signalling. We demonstrate that (1) tautomycin and okadaic acid, inhibitors of protein phosphatases PP1 and PP2A, have no effect on 5-HT-induced Ca2+ signals; (2) cyclosporin A and FK506, inhibitors of Ca2+/calmodulin-activated protein phosphatase calcineurin, cause an increase in the frequency of 5-HT-induced Ca2+ oscillations; (3) the sensitizing effect of cyclosporin A on 5-HT-induced Ca2+ responses does not involve Ca2+ entry into the cells; (4) cyclosporin A increases InsP(3)-dependent Ca2+ release; (5) inhibition of PKA abolishes the effect of cyclosporin A on the 5-HT-induced Ca2+ responses, indicating that PKA and calcineurin act antagonistically on the InsP(3)/Ca2+ signalling pathway. These findings suggest that calcineurin provides a negative feedback on InsP(3)/Ca2+ signalling in blowfly salivary glands, counteracting the effect of PKA and desensitizing the signalling cascade at higher 5-HT concentrations. (C) 2014 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@misc{BaumannWalz2012,
  author    = {Baumann, Otto and Walz, Bernd},
  title     = {The blowfly salivary gland - A model system for analyzing the regulation of plasma membrane V-ATPase},
  series = {Journal of insect physiology},
  volume    = {58},
  journal   = {Journal of insect physiology},
  number    = {4},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0022-1910},
  doi       = {10.1016/j.jinsphys.2011.11.015},
  pages     = {450 -- 458},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}
@article{HeindorffBlenauWalzetal.2012,
  author    = {Heindorff, Kristoffer and Blenau, Wolfgang and Walz, Bernd and Baumann, Otto},
  title     = {Characterization of a Ca2+/calmodulin-dependent AC1 adenylyl cyclase in a non-neuronal tissue, the blowfly salivary gland},
  series = {Cell calcium},
  volume    = {52},
  journal   = {Cell calcium},
  number    = {2},
  publisher = {Churchill Livingstone},
  address   = {Edinburgh},
  issn      = {0143-4160},
  doi       = {10.1016/j.ceca.2012.04.016},
  pages     = {103 -- 112},
  year      = {2012},
  abstract  = {Crosstalk between intracellular signalling pathways is a functionally important and widespread phenomenon in cell physiology across phyla. In the salivary gland of the blowfly, serotonin induces fluid secretion via parallel activation of both the InsP(3)/Ca2+ and the cAMP/PKA signalling pathways, which interact on multiple levels. We have determined the molecular identity of a link between both pathways that mediates a Ca2+-dependent rise of intracellular cAMP. Whereas hydrolysis of cAMP via phosphodiesterases is largely independent of Ca2+, cAMP synthesis by adenylyl cyclases (AC) is potentiated in a Ca2+/calmodulin (Ca2+/CaM)-dependent manner. The existence of a Ca2+/CaM-dependent AC is supported by physiological data and a molecular approach. We have cloned Cv rutabaga cDNA, encoding the first blowfly AC, and confirmed its expression in the salivary gland via reverse transcription followed by polymerase chain reaction. The putative gene product of Cv rutabaga is a Ca2+/CaM-dependent type I AC and shows highest homology to Rutabaga from Drosophila. Thus, a Ca2+/CaM-dependent AC serves as a link between the InsP(3)/Ca2+ and the cAMP/PKA signalling pathways in the salivary gland of the blowfly and might be important for the amplification and optimization of the secretory response.},
  language  = {en}
}