@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{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{WalzBaumann1995, author = {Walz, Bernd and Baumann, Otto}, title = {Structure and cellular physiology of Ca2+ stores in invertebrate photoreceptors}, year = {1995}, language = {en} } @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} } @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{MargWalzBlenau2004, author = {Marg, S. and Walz, Bernd and Blenau, Wolfgang}, title = {The effects of dopamine receptor agonists and antagonists on the secretory rate of cockroach (Periplaneta americana) salivary glands}, issn = {0022-1910}, year = {2004}, abstract = {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}, language = {en} } @article{JustWalz1996, author = {Just, Frank and Walz, Bernd}, title = {The effects of serotonin and dopamine on salivary secretion by isolated cockroach salivary glands}, year = {1996}, language = {en} } @article{BaumannWalz2001, author = {Baumann, Otto and Walz, Bernd}, title = {The endoplasmic reticulum of animal cells and its organization into structural and functional domains}, year = {2001}, language = {en} } @article{ZimmermannWalz1999, author = {Zimmermann, Bernhard and Walz, Bernd}, title = {The mechanism mediating regenerative intercellular Ca2+ waves in the blowfly salivary gland}, year = {1999}, language = {en} } @article{UkhanovWalz2000, author = {Ukhanov, Kyrill and Walz, Bernd}, title = {The phosphoinositide signaling cascade is involved in photoreception in the leech Hirudo medicinalis}, issn = {0340-7554}, year = {2000}, language = {en} } @article{FengCarsonWalzetal.1994, author = {Feng, J. J. and Carson, J. H. and Walz, Bernd and Fein, A.}, title = {Three-dimensional organization of endoplasmatic reticulum in the ventral photoreceptors of Limulus}, year = {1994}, 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{Walz1997, author = {Walz, Bernd}, title = {{\"U}berlebensk{\"u}nstler aus dem Moospolster}, year = {1997}, abstract = {Popul{\"a}rwissenschaftlicher Aufsat}, language = {de} }