@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{WalzUkhanovZimmermann2000,
  author    = {Walz, Bernd and Ukhanov, Kyrill and Zimmermann, Bernhard},
  title     = {Actions of neomycin on electrical light responses : Ca2+ release and intracellular Ca2+ changes in photoreceptors of the honeybee drone},
  issn      = {0340-7594},
  year      = {2000},
  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{Walz1997,
  author    = {Walz, Bernd},
  title     = {Auch im S{\"u}ßwasser - die Hydrozoe cordylophora caspia},
  year      = {1997},
  language  = {de}
}
@article{SomlyoWalz1995,
  author    = {Somlyo, A. V. and Walz, Bernd},
  title     = {Ca2+ in visual transduction and adaptation in vertebrates and invertebrates},
  year      = {1995},
  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{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}
}
@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}
}
@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{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}
}
@article{BaumannArltRoemmlingetal.2000,
  author    = {Baumann, Otto and Arlt, Kathleen and R{\"o}mmling, Katja and Goller, Helmut and Walz, Bernd},
  title     = {Characterization of an extremely motile cellular network in the rotifer Asplanchna : Structure, kinetics and the cytoskeleton},
  year      = {2000},
  language  = {en}
}
@article{BaumannArltRoemmlingetal.2000,
  author    = {Baumann, Otto and Arlt, Kathleen and R{\"o}mmling, Katja and Goller, Helmut and Walz, Bernd},
  title     = {Characterization of an extremely motile cellular network in the rotifer Asplanchna spp. : structure, kinetics, and cytoskeleton},
  year      = {2000},
  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}
}
@article{LangWalz1999,
  author    = {Lang, Ingo and Walz, Bernd},
  title     = {Dopamine stimulates salivary duct cells in the cockroach Pertiplaneta americana},
  year      = {1999},
  language  = {en}
}
@article{LangWalz2001,
  author    = {Lang, Ingo and Walz, Bernd},
  title     = {Dopamine-induced epithelial K+ and Na+ movements in the salivary ducts of Periplaneta americana},
  year      = {2001},
  language  = {en}
}
@article{HilleWalz2006,
  author    = {Hille, Carsten and Walz, Bernd},
  title     = {Dopamine-induced graded intracellular Ca2+ elevation via the Na+-Ca2+ exchanger operating in the Ca2+-entry mode in cockroach salivary ducts},
  issn      = {0143-4160},
  doi       = {10.1016/j.ceca.2005.11.006},
  year      = {2006},
  abstract  = {Stimulation with the neurotransmitter dopamine causes an amplitude-modulated increase in the intracellular Ca2+ concentration ([Ca2+](i)) in epithelial cells of the ducts of cockroach salivary glands. This is completely attributable to a Ca2+ influx from the extracellular space. Additionally, dopamine induces a massive [Na+](i) elevation via the Na+- K+-2Cl(-) cotransporter (NKCC). We have reasoned that Ca2+-entry is mediated by the Na+-Ca2+ exchanger (NCE) operating in the Ca2+-entry mode. To test this hypothesis, [Ca2+](i) and [Na+](i) were measured by using the fluorescent dyes Fura- 2, Fluo-3, and SBFI. Inhibition of Na+-entry from the extracellular space by removal of extracellular Na+ or inhibition of the NKCC by 10 mu M bumetanide did not influence resting [Ca2+]i but completely abolished the dopamine-induced [Ca2+](i) elevation. Simultaneous recordings of [Ca2+](i) and [Na+](i) revealed that the dopamine-induced [Na+](i) elevation preceded the [Ca2+](i) elevation. During dopamine stimulation, the generation of an outward Na+ concentration gradient by removal of extracellular Na+ boosted the [Ca2+](i) elevation. Furthermore, prolonging the dopamine-induced [Na+](i) rise by blocking the Na+/K+-ATPase reduced the recovery from [Ca2+](i) elevation. These results indicate that dopamine induces a massive NKCC-mediated elevation in [Na+](i), which reverses the NCE activity into the reverse mode causing a graded [Ca2+](i) elevation in the duct cells.},
  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{LangWalz1999,
  author    = {Lang, Ingo and Walz, Bernd},
  title     = {Dye-coupling between cells of the salivary glands in the cockroach Periplaneta americana},
  year      = {1999},
  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}
}