The salivary glands and their secretions are vital to the capacity of ixodid ticks to he parasitic and are the major route by which pathogenic organisms and toxins access the vertebrate host. We propose to continue research on the characterization of receptors and signal pathways controlling salivary gland function in an ixodid tick, Amblyomma americanum (L.). The evidence implicating dopamine as a neurotransmitter at the neuroeffector junction and its interaction with a D-1 receptor is compelling; however, the effects of dopamine receptor antagonists on dopamine stimulated fluid secretion suggest that dopamine control is more complex and may utilize multiple receptors. Receptor binding studies, cyclic AMP, and secretion assays will he used to clarify the role of dopamine and dopamine receptors in the salivary glands. Other data indicates the existence of a ligand (neuropeptide from the tick synganglion), which through a receptor mediated interaction, activates phospholipase C (PLC) catalyzed hydrolysis of plasma membrane phosphoinositides. We propose to study the forms and characteristics of PLC. We will also address the question of whether PLC is activated through a receptor tyrosine kinase or GTP-dependent protein. Signalling through phosphatidylcholine breakdown and its relationship, if any, to phosphoinositide turnover will also be investigated. Since salivary secretion is regulated by protein kinase-catalyzed phosphorylation of proteins, we will continue ongoing molecular characterization of protein kinases and their role in controlling salivary gland function. Information about receptors and regulation of cell functions in the salivary glands will provide key insights into factors which enable ticks to be parasitic and their relationship to pathogen transmission to hosts.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
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Tropical Medicine and Parasitology Study Section (TMP)
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Oklahoma State University Stillwater
Schools of Earth Sciences/Natur
United States
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Qian, Y; Yuan, J; Essenberg, R C et al. (1998) Prostaglandin E2 in the salivary glands of the female tick, Amblyomma americanum (L.): calcium mobilization and exocytosis. Insect Biochem Mol Biol 28:221-8
McSwain, J L; Luo, C; deSilva, G A et al. (1997) Cloning and sequence of a gene for a homologue of the C subunit of the V-ATPase from the salivary gland of the tick Amblyomma americanum (L). Insect Mol Biol 6:67-76
Qian, Y; Essenberg, R C; Dillwith, J W et al. (1997) A specific prostaglandin E2 receptor and its role in modulating salivary secretion in the female tick, Amblyomma americanum (L.). Insect Biochem Mol Biol 27:387-95
Luo, C; McSwain, J L; Tucker, J S et al. (1997) Cloning and sequence of a gene for the homologue of the stearoyl CoA desaturase from salivary glands of the tick Amblyomma americanum. Insect Mol Biol 6:267-71
Sauer, J R; McSwain, J L; Bowman, A S et al. (1995) Tick salivary gland physiology. Annu Rev Entomol 40:245-67
Sauer, J R; McSwain, J L; Essenberg, R C (1994) Cell membrane receptors and regulation of cell function in ticks and blood-sucking insects. Int J Parasitol 24:33-52
Qureshi, A E; Essenberg, R C; Sauer, J R (1994) Protein phosphatase 1 and 2A in tick salivary glands as assessed by responses to okadaic acid. Insect Biochem Mol Biol 24:309-17
Shipley, M M; Dillwith, J W; Essenberg, R C et al. (1993) Analysis of lipids in the salivary glands of Amblyomma americanum (L.): detection of a high level of arachidonic acid. Arch Insect Biochem Physiol 23:37-52
Shipley, M M; Dillwith, J W; Bowman, A S et al. (1993) Changes in lipids of the salivary glands of the lone star tick, Amblyomma americanum, during feeding. J Parasitol 79:834-42
McSwain, J L; Essenberg, R C; Sauer, J R (1992) Oral secretion elicited by effectors of signal transduction pathways in the salivary glands of Amblyomma americanum (Acari: Ixodidae). J Med Entomol 29:41-8

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