TY - GEN A1 - Schmidt, Ruth A1 - Baumann, Otto A1 - Walz, Bernd T1 - cAMP potentiates InsP3-induced Ca2+ release from the endoplasmic reticulum in blowfly salivary glands T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe N2 - 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 842 KW - endoplasmic reticulum KW - salivary gland KW - physiological solution KW - fluid secretion KW - cAMP analog Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-429770 SN - 1866-8372 IS - 842 ER - TY - JOUR A1 - Gräf, Ralph A1 - Seckler, Robert A1 - Hagemann, Alfred A1 - D'Aprile, Iwan-Michelangelo A1 - Schulte, Christoph A1 - Zimmermann, Matthias A1 - Blom, Hans A1 - Horn-Conrad, Antje A1 - Kampe, Heike A1 - Jäger, Sophie A1 - Haase, Jana A1 - Eckardt, Barbara A1 - Priebs-Tröger, Astrid A1 - Walz, Bernd T1 - Portal Wissen = Raum BT - Das Forschungsmagazin der Universität Potsdam N2 - Mit „Portal Wissen“ laden wir Sie ein, die Forschung an der Universität Potsdam zu entdecken und in ihrer Vielfalt kennenzulernen. In der ersten Ausgabe dreht sich alles um „Räume“. Räume, in denen geforscht wird, solche, die es zu erforschen gilt, andere, die durch Wissenschaft zugänglich oder erschlossen werden, aber auch Räume, die Wissenschaft braucht, um sich entfalten zu können. Forschung vermisst Räume: „Wissenschaft wird von Menschen gemacht“, schrieb der Physiker Werner Heisenberg. Umgekehrt lässt sich sagen: Wissenschaft macht Menschen, widmet sich ihnen, beeinflusst sie. Dieser Beziehung ist „Portal Wissen“ nachgegangen. Wir haben Wissenschaftler getroffen, sie gefragt, wie aus ihren Fragen Projekte entstehen, haben sie auf dem oft verschlungenen Weg zum Ziel begleitet. Ein besonderes Augenmerk dieses Heftes gilt den „Kulturellen Begegnungsräumen“, denen ein eigener Profilbereich der Forschung an der Universität Potsdam gewidmet ist. Forschung hat Räume: Labore, Bibliotheken, Gewächshäuser oder Archive – hier ist Wissenschaft zu Liebe Leserinnen und Leser, Hause. All diese Orte sind so einzigartig wie die Wissenschaftler, die in ihnen arbeiten, oder die Untersuchungen, die hier stattfinden. Erst die Vision davon, wie ein Problem zu lösen ist, macht aus einfachen Zimmern „Laborräume“. Wir haben ihre Türen geöffnet, um zu zeigen, was – und wer – sich dahinter befindet. Forschung eröffnet Räume: Wenn Wissenschaft erfolgreich ist, bewegt sie uns, bringt uns voran. Auf dem Weg einer wissenschaftlichen Erkenntnis aus dem Labor in den Alltag stehen mitunter Hürden, die meist nicht auf den ersten Blick zu erkennen sind. Auf jeden Fall aber ist ihre Anwendung erster Ausgangspunkt von Wissenschaft, Antrieb und Motivation jedes Forschers. „Portal Wissen“ zeigt, welche „Praxisräume“ sich aus der Übersetzung von Forschungsresultaten ergeben. Dort, wo wir es unbedingt erwarten, und dort, wo vielleicht nicht. Forschung erschließt Räume: Bei Expeditionen, Feldversuchen und Exkursionen wird nahezu jede Umgebung zum mobilen Labor. So eröffnet Wissenschaft Zugänge auch zu Orten, die auf vielfach andere Weise verschlossen oder unzugänglich scheinen. Wir haben uns in Forscher- Reisetaschen gemogelt, um bei Entdeckungsreisen dabei zu sein, die weit weg – vor allem nach Afrika – führen. Zugleich haben wir beobachtet, wie „Entwicklungsräume“ sich auch von Potsdam aus erschließen lassen oder zumindest ihre Vermessung in Potsdam beginnen kann. Forschung braucht Räume: Wissenschaft hat zwei Geschlechter, endlich. Noch nie waren so viele Frauen in der Forschung tätig wie derzeit. Ein Grund zum Ausruhen ist dies gleichwohl nicht. Deutschlandweit ist aktuell nur jede fünfte Professur von einer Frau besetzt. „Portal Wissen“ schaut, welche „Entwicklungsräume“ Frauen sich in der Wissenschaft, aber auch darüber hinaus geschaffen haben. Und wo sie ihnen verwehrt werden. Wir wünschen Ihnen eine anregende Lektüre und dass auch Sie einen Raum finden, der Sie inspiriert. Prof. Dr. Robert Seckler Vizepräsident für Forschung und wissenschaftlichen Nachwuchs T3 - Portal Wissen: Das Forschungsmagazin der Universität Potsdam [Deutsche Ausgabe] - 01/2012 Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-440785 SN - 2194-4237 IS - 01/2012 ER - TY - JOUR A1 - Ast, Sandra A1 - Müller, Holger A1 - Flehr, Roman A1 - Klamroth, Tillmann A1 - Walz, Bernd A1 - Holdt, Hans-Jürgen T1 - High Na+ and K+-induced fluorescence enhancement of a pi-conjugated phenylaza-18-crown-6-triazol-substituted coumarin fluoroionophore JF - Chemical communications N2 - The new pi-conjugated 1,2,3-triazol-1,4-diyl fluoroionophore 1 generated via Cu(I) catalyzed [3 + 2] cycloaddition shows high fluorescence enhancement factors (FEF) in the presence of Na+ (FEF = 58) and K+ (FEF = 27) in MeCN and high selectivity towards K+ under simulated physiological conditions (160 mM K+ or Na+, respectively) with a FEF of 2.5 for K+. Y1 - 2011 U6 - https://doi.org/10.1039/c0cc04370b SN - 1359-7345 VL - 47 IS - 16 SP - 4685 EP - 4687 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schewe, Bettina A1 - Blenau, Wolfgang A1 - Walz, Bernd T1 - Intracellular pH regulation in unstimulated Calliphora salivary glands is Na+ dependent and requires V-ATPase activity JF - The journal of experimental biology N2 - Salivary gland cells of the blowfly Calliphora vicina have a vacuolar-type H+-ATPase (V-ATPase) that lies in their apical membrane and energizes the secretion of a KCl-rich primary saliva upon stimulation with serotonin (5-hydroxytryptamine). Whether and to what extent V-ATPase contributes to intracellular pH (pH(i)) regulation in unstimulated gland cells is unknown. We used the fluorescent dye BCECF to study intracellular pH(i) regulation microfluorometrically and show that: (1) under resting conditions, the application of Na+-free physiological saline induces an intracellular alkalinization attributable to the inhibition of the activity of a Na+-dependent glutamate transporter; (2) the maintenance of resting pHi is Na+, Cl-, concanamycin A and DIDS sensitive; (3) recovery from an intracellular acid load is Na+ sensitive and requires V-ATPase activity; (4) the Na+/H+ antiporter is not involved in pHi recovery after a NH4Cl prepulse; and (5) at least one Na+-dependent transporter and the V-ATPase maintain recovery from an intracellular acid load. Thus, under resting conditions, the V-ATPase and at least one Na+-dependent transporter maintain normal pH(i) values of pH.7.5. We have also detected the presence of a Na+-dependent glutamate transporter, which seems to act as an acid loader. Despite this not being a common pH(i)-regulating transporter, its activity affects steady-state pH(i) in C. vicina salivary gland cells. KW - Calliphora vicina KW - salivary gland KW - intracellular pH regulation KW - Na+/H+ antiporter KW - NHE KW - vacuolar H+-ATPase KW - V-ATPase KW - intracellular pH KW - insect KW - blowfly KW - BCECF KW - NH4Cl prepulse Y1 - 2012 U6 - https://doi.org/10.1242/jeb.063172 SN - 0022-0949 VL - 215 IS - 8 SP - 1337 EP - 1345 PB - Company of Biologists Limited CY - Cambridge 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 - Heindorff, Kristoffer A1 - Blenau, Wolfgang A1 - Walz, Bernd A1 - Baumann, Otto T1 - Characterization of a Ca2+/calmodulin-dependent AC1 adenylyl cyclase in a non-neuronal tissue, the blowfly salivary gland JF - Cell calcium N2 - 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. KW - Adenylyl cyclase KW - Phosphodiesterase KW - Crosstalk KW - Ca2+ KW - cAMP KW - Intracellular signalling KW - Salivary gland KW - Calliphora vicina KW - Rutabaga Y1 - 2012 U6 - https://doi.org/10.1016/j.ceca.2012.04.016 SN - 0143-4160 VL - 52 IS - 2 SP - 103 EP - 112 PB - Churchill Livingstone CY - Edinburgh 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 - Fechner, Lennart A1 - Baumann, Otto A1 - Walz, Bernd T1 - Activation of the cyclic AMP pathway promotes serotonin-induced Ca2+ oscillations in salivary glands of the blowfly Calliphora vicina JF - Cell calcium N2 - 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. KW - Calcium KW - Ca2+ KW - Calcium oscillations KW - cAMP KW - Signalling KW - Crosstalk KW - Salivary gland KW - Calliphora KW - Blowfly KW - Insect Y1 - 2013 U6 - https://doi.org/10.1016/j.ceca.2012.10.004 SN - 0143-4160 VL - 53 IS - 2 SP - 94 EP - 101 PB - Churchill Livingstone CY - Edinburgh 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 - Voss, Martin A1 - Fechner, Lennart A1 - Walz, Bernd A1 - Baumann, Otto T1 - Calcineurin activity augments cAMP/PKA-dependent activation of V-ATPase in blowfly salivary glands N2 - 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. Y1 - 2010 UR - http://ajpcell.physiology.org/ U6 - https://doi.org/10.1152/ajpcell.00328.2009 SN - 0363-6143 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 - JOUR A1 - Feng, J. J. A1 - Carson, J. H. A1 - Walz, Bernd A1 - Fein, A. T1 - Three-dimensional organization of endoplasmatic reticulum in the ventral photoreceptors of Limulus Y1 - 1994 ER - TY - JOUR A1 - Walz, Bernd A1 - Zimmermann, Bernhard A1 - Seidl, Siegfried T1 - Intracellular Ca2+ concentration and latency of light-induced Ca2+ changes in photoreceptors of the honeybee drone Y1 - 1994 ER - TY - JOUR A1 - Just, Frank A1 - Walz, Bernd T1 - Localization of carbonic-anhydrase in the salivary-glands of the cockroach, Periplaneta americana Y1 - 1994 SN - 0301-5564 ER - TY - JOUR A1 - Just, Frank A1 - Walz, Bernd T1 - Immunocytochemical localization of Na+/K+-ATPase and V-H+-ATPase in the salivary glands of the cockroach, periplaneta americana Y1 - 1994 ER - TY - JOUR A1 - Just, Frank A1 - Walz, Bernd T1 - Salivary glands of the cockroach, Periplaneta americana : new data from light and electron-microscopy Y1 - 1994 SN - 0362-2525 ER - TY - JOUR A1 - Walz, Bernd A1 - Baumann, Otto A1 - Zimmermann, Bernhard A1 - Ciriacy-Wantrup, E.v. T1 - Caffeine- and ryanodine-sensitive Ca2+-induced Ca2+ release from the endo plasmatic reticulum in honeybee photoreceptors Y1 - 1995 ER - TY - JOUR A1 - Walz, Bernd A1 - Baumann, Otto T1 - Structure and cellular physiology of Ca2+ stores in invertebrate photoreceptors Y1 - 1995 ER - TY - JOUR A1 - Stürmer, Karoline A1 - Baumann, Otto A1 - Walz, Bernd T1 - Actin-dependent light-induced translocation of mitochondria and ER cisternae in the photoreceptor cells of the locust schistocerca gregaria Y1 - 1995 ER - TY - JOUR A1 - Somlyo, A. V. A1 - Walz, Bernd T1 - Ca2+ in visual transduction and adaptation in vertebrates and invertebrates Y1 - 1995 ER - TY - JOUR A1 - Just, Frank A1 - Walz, Bernd T1 - The effects of serotonin and dopamine on salivary secretion by isolated cockroach salivary glands Y1 - 1996 ER - TY - JOUR A1 - Walz, Bernd T1 - Überlebenskünstler aus dem Moospolster N2 - Populärwissenschaftlicher Aufsat Y1 - 1997 ER - TY - JOUR A1 - Walz, Bernd T1 - Auch im Süßwasser - die Hydrozoe cordylophora caspia Y1 - 1997 ER - TY - JOUR A1 - Zimmermann, Bernhard A1 - Walz, Bernd T1 - Serotonin-induced intercellular calcium waves in salivary glands of the blowfley Calliphora erythrocephala Y1 - 1997 ER - TY - JOUR A1 - Aschenbrenner, Stefan A1 - Walz, Bernd T1 - Pleated septate junctions in leech photoreceptors : ultrastructure, arrangement of septa, gate and fence functions Y1 - 1998 ER - TY - JOUR A1 - Lang, Ingo A1 - Walz, Bernd T1 - Dopamine stimulates salivary duct cells in the cockroach Pertiplaneta americana Y1 - 1999 ER - TY - JOUR A1 - Zimmermann, Bernhard A1 - Walz, Bernd T1 - The mechanism mediating regenerative intercellular Ca2+ waves in the blowfly salivary gland Y1 - 1999 ER - TY - JOUR A1 - Lang, Ingo A1 - Walz, Bernd T1 - Dye-coupling between cells of the salivary glands in the cockroach Periplaneta americana Y1 - 1999 ER - TY - JOUR A1 - Baumann, Otto A1 - Arlt, Kathleen A1 - Römmling, Katja A1 - Goller, Helmut A1 - Walz, Bernd T1 - Characterization of an extremely motile cellular network in the rotifer Asplanchna : Structure, kinetics and the cytoskeleton Y1 - 2000 ER - TY - JOUR A1 - Baumann, Otto A1 - Arlt, Kathleen A1 - Römmling, Katja A1 - Goller, Helmut A1 - Walz, Bernd T1 - Characterization of an extremely motile cellular network in the rotifer Asplanchna spp. : structure, kinetics, and cytoskeleton Y1 - 2000 ER - TY - JOUR A1 - Walz, Bernd A1 - Ukhanov, Kyrill T1 - Light-dependent repetitive Ca2+ spikes induced by extracellular application of neumycin in honeybee drone photoreceptors Y1 - 2000 SN - 0340-7594 ER - TY - JOUR A1 - Walz, Bernd A1 - Ukhanov, Kyrill A1 - Zimmermann, Bernhard T1 - Actions of neomycin on electrical light responses : Ca2+ release and intracellular Ca2+ changes in photoreceptors of the honeybee drone Y1 - 2000 SN - 0340-7594 ER - TY - JOUR A1 - Ukhanov, Kyrill A1 - Walz, Bernd T1 - The phosphoinositide signaling cascade is involved in photoreception in the leech Hirudo medicinalis Y1 - 2000 SN - 0340-7554 ER - TY - JOUR A1 - Lang, Ingo A1 - Walz, Bernd T1 - Dopamine-induced epithelial K+ and Na+ movements in the salivary ducts of Periplaneta americana Y1 - 2001 ER - TY - JOUR A1 - Ukhanov, Kyrill A1 - Mills, S. J. A1 - Potter, Barry V. L. A1 - Walz, Bernd T1 - InsP3-induced Ca2+ release in permeabilized invertebrate photoreceptors : a link between phototransduction and Ca2+ stores Y1 - 2001 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 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 - Zimmermann, Bernhard A1 - Dames, Petra A1 - Walz, Bernd A1 - Baumann, Otto T1 - Distribution and serotonin-induced activation of vacuolar-type H+-ATPase in the salivary glands of the blowfly Calliphora vicina Y1 - 2003 ER - TY - JOUR A1 - Schmidt, R. A1 - Walz, Bernd T1 - Serotonin and histamine produce different spatiotemporal Ca2+ signals in blowfly salivary glands Y1 - 2004 SN - 0171-9335 ER - TY - JOUR A1 - Marg, S. A1 - Walz, Bernd A1 - Blenau, Wolfgang T1 - The effects of dopamine receptor agonists and antagonists on the secretory rate of cockroach (Periplaneta americana) salivary glands N2 - The acinar salivary glands of the cockroach, Periplaneta americana, are innervated by dopaminergic and serotonergic nerve fibers. Serotonin stimulates the secretion of protein-rich saliva, whereas dopamine causes the production of protein-free saliva. This suggests that dopamine acts selectively on ion-transporting peripheral cells within the acini and the duct cells, and that serotonin acts on the protein-producing central cells of the acini. We have investigated the pharmacology of the dopamine-induced secretory activity of the salivary gland of Periplaneta americana by testing several dopamine receptor agonists and antagonists. The effects of dopamine can be mimicked by the non-selective dopamine receptor agonist 6,7-ADTN and, less effectively, by the vertebrate D1 receptor-selective agonist chloro-APB. The vertebrate D1 receptor-selective agonist SKF 38393 and vertebrate D2 receptor-selective agonist R(-)- TNPA were ineffective. R(+)-Lisuride induces a secretory response with a slower onset and a lower maximal response compared with dopamine-induced secretion. However, lisuride-stimulated glands continue secreting saliva, even after lisuride-washout. Dopamine-induced secretions can be blocked by the vertebrate dopamine receptor antagonists cis(Z)- flupenthixol, chlorpromazine, and S(+)-butaclamol. Our pharmacological data do not unequivocally indicate whether the dopamine receptors on the Periplaneta salivary glands belong to the D1 or D2 subfamily of dopamine receptors, but we can confirm that the pharmacology of invertebrate dopamine receptors is remarkably different from that of their vertebrate counterparts. (C) 2004 Elsevier Ltd. All rights reserved Y1 - 2004 SN - 0022-1910 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 - 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 - Rietdorf, Katja A1 - Blenau, Wolfgang A1 - Walz, Bernd T1 - Protein secretion in cockroach salivary glands requires an increase in intracellular cAMP and Ca2+ concentrations N2 - The salivary glands in the cockroach Periplaneta americana secrete protein-containing saliva when stimulated by serotonin (5-HT) and protein-free saliva upon dopamine stimulation. In order to obtain information concerning the signalling pathways involved in 5-HT-induced protein secretion, we have determined the protein content of saliva secreted after experimental manipulations that potentially elevate intracellular Ca2+ and cyclic nucleotide concentrations in isolated glands. We have found that 5-HT stimulates the rate of protein secretion in a dose-dependent manner (threshold: 3 x 10(-8) M; EC50 1.5 x 10(-6) M). The maximal rate of 5-HT-induced protein secretion was 2.2 +/- 0.2 mu g/min. Increasing intracellular Ca2+ or cAMP by bath application of ionomycin (5 mu M), db cAMP (10 mM), forskolin (100 mu M) or IBMX (100 mu M), respectively, stimulated protein secretion at significantly lower rates, whereas db cGMP (1 mM) did not activate protein secretion. The high rates and the kinetics of 5-HT-induced protein secretion could only be mimicked by either applying forskolin together with IBMX (with or without ionomycin) or by applying IBMX together with ionomycin. Our measurements suggest that 5-HT-induced protein secretion is mediated by an elevation of [cAMP](i) and that Ca2+ may function as a co-agonist and augment the rate of protein secretion. (c) 2005 Elsevier Ltd. All rights reserved Y1 - 2005 SN - 0022-1910 ER - TY - JOUR A1 - Hille, Carsten A1 - Walz, Bernd T1 - Dopamine-induced graded intracellular Ca2+ elevation via the Na+-Ca2+ exchanger operating in the Ca2+-entry mode in cockroach salivary ducts N2 - 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. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/01434160 U6 - https://doi.org/10.1016/j.ceca.2005.11.006 SN - 0143-4160 ER - TY - JOUR A1 - Dames, Petra A1 - Zimmermann, Bernhard A1 - Schmidt, Ruth A1 - Rein, Julia A1 - Voss, Martin A1 - Schewe, Bettina A1 - Walz, Bernd A1 - Baumann, Otto T1 - cAMP regulates plasma membrane vacuolar-type H+-ATPase assembly and activity in blowfly salivary glands N2 - 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 Y1 - 2006 UR - http://www.pnas.org/ U6 - https://doi.org/10.1073/pnas.0600011103 SN - 0027-8424 ER - TY - JOUR A1 - Schewe, Bettina A1 - Schmaelzlin, Elmar A1 - Walz, Bernd T1 - Intracellular pH homeostasis and serotonin-induced pH changes in Calliphora salivary glands : the contribution of V-ATPase and carbonic anhydrase Y1 - 2008 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 - 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 - TY - GEN A1 - Blenau, Wolfgang A1 - Rotte, Cathleen A1 - Krach, Christian A1 - Balfanz, Sabine A1 - Baumann, Arnd A1 - Walz, Bernd T1 - Molecular characterization and localization of the first tyramine receptor of the American cockroach (Periplaneta americana) N2 - The phenolamines octopamine and tyramine control, regulate, and modulate many physiological and behavioral processes in invertebrates. Vertebrates possess only small amounts of both substances, and thus, octopamine and tyramine, together with other biogenic amines, are referred to as “trace amines.” Biogenic amines evoke cellular responses by activating G-protein-coupled receptors. We have isolated a complementary DNA (cDNA) that encodes a biogenic amine receptor from the American cockroach Periplaneta americana, viz., Peatyr1, which shares high sequence similarity to members of the invertebrate tyramine-receptor family. The PeaTYR1 receptor was stably expressed in human embryonic kidney (HEK) 293 cells, and its ligand response has been examined. Receptor activation with tyramine reduces adenylyl cyclase activity in a dose-dependent manner (EC50 350 nM). The inhibitory effect of tyramine is abolished by co-incubation with either yohimbine or chlorpromazine. Receptor expression has been investigated by reverse transcription polymerase chain reaction and immunocytochemistry. The mRNA is present in various tissues including brain, salivary glands, midgut, Malpighian tubules, and leg muscles. The effect of tyramine on salivary gland acinar cells has been investigated by intracellular recordings, which have revealed excitatory presynaptic actions of tyramine. This study marks the first comprehensive molecular, pharmacological, and functional characterization of a tyramine receptor in the cockroach. KW - Biogenic amine KW - cellular signaling KW - G-protein-coupled receptor KW - octopamine KW - salivary gland Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44335 ER - TY - GEN A1 - Blenau, Wolfgang A1 - Troppmann, Britta A1 - Walz, Bernd T1 - Pharmacology of serotonin-induced salivary secretion in Periplaneta americana N2 - The acinar salivary gland of the cockroach, Periplaneta americana, is innervated by dopaminergic and serotonergic nerve fibers. Stimulation of the glands by serotonin (5-hydroxytryptamine, 5-HT) results in the production of a protein-rich saliva, whereas stimulation by dopamine results in saliva that is protein-free. Thus, dopamine acts selectively on ion-transporting peripheral cells within the acini, and 5-HT acts on protein-producing central cells. We have investigated the pharmacology of the 5-HT-induced secretory activity of isolated salivary glands of P. americana by testing several 5-HT receptor agonists and antagonists. The effects of 5-HT can be mimicked by the non-selective 5-HT receptor agonist 5-methoxytryptamine. All tested agonists that display at least some receptor subtype specificity in mammals, i.e., 5-carboxamidotryptamine, (+/-)-8-OH-DPAT, (+/-)-DOI, and AS 19, were ineffective in stimulating salivary secretion. 5-HT-induced secretion can be blocked by the vertebrate 5-HT receptor antagonists methiothepin, cyproheptadine, and mianserin. Our pharmacological data indicate that the pharmacology of arthropod 5-HT receptors is remarkably different from that of their vertebrate counterparts. (C) 2007 Elsevier Ltd. All rights reserved. KW - Biogenic amine KW - G protein-coupled receptor KW - insect KW - salivary gland KW - secretion Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44319 ER -