The goal of the proposed research is to investigate arachidonic acid metabolites (eicosanoids) in the physiology of tick salivary glands and their role as salivary secretory products that facilitate tick feeding. Eicosanoids are secreted by the salivary glands of several tick species and are hypothesized to assist in tick feeding by preventing host hemostatic reactions and increase the flow of host blood at the tick feeding site. Preliminary data indicate that high concentrations of arachidonic acid are present in phosphatidylcholine and phosphatidylethanolamine in the salivary glands of A. americanum. Because nothing is known about the sequestration and/or synthesis of arachidonic acid in the salivary glands or changes in levels in the salivary glands during tick feeding in any tick, these questions will be studied in A. americanum. In most tissues, the synthesis of eicosanoids is limited by the availability of their common precursor, free arachidonic acid which is liberated from membrane phospholipids. We propose to establish the organelle locations of arachidonic acid and how the free level of arachidonic acid is liberated from esterified stores in complex lipids of the salivary glands. Activity and control of phospholipase A2 will be studied in detail. We will investigate agonist induced increased in phospholipase A2 activity and its linkage to GTP- binding proteins and modulation by calcium, protein kinase C and lipocortin-like molecules. The ability of the salivary glands to metabolize arachidonic acid both in vivo and in vitro will be studied. These experiments will be performed in Nebraska with salivary gland extracts shipped from Oklahoma. Eicosanoids will be separated, identified, and quantified by TLC, HPLC, RIA and enzyme-linked immunoassay (EIA). Saliva from A. americanum will be collected by stimulating ticks to secrete with known agonists of secretion and analyzed for eicosanoids and pharmacological activity involving smooth muscle bioassays and platelet aggregation. These experiments will be performed in Arizona with tick saliva collected in Oklahoma. We will also study the possibility that eicosanoids serve as """"""""local"""""""" hormones to control or modulate secretion. Results of these experiments will enable us to have a clearer picture of the importance of arachidonic acid metabolites at the tick-host interface and the importance of these molecules in enabling ticks to be efficient vectors of pathogens.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI031460-04
Application #
2066413
Study Section
Tropical Medicine and Parasitology Study Section (TMP)
Project Start
1991-08-01
Project End
1996-05-31
Budget Start
1994-06-01
Budget End
1995-05-31
Support Year
4
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Oklahoma State University Stillwater
Department
Zoology
Type
Schools of Earth Sciences/Natur
DUNS #
City
Stillwater
State
OK
Country
United States
Zip Code
74078
Zhu, K; Bowman, A S; Dillwith, J W et al. (1998) Phospholipase A2 activity in salivary glands and saliva of the lone star tick (Acari: Ixodidae) during tick feeding. J Med Entomol 35:500-4
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
Bowman, A S; Gengler, C L; Surdick, M R et al. (1997) A novel phospholipase A2 activity in saliva of the lone star tick, Amblyomma americanum (L.). Exp Parasitol 87:121-32
Zhu, K; Bowman, A S; Brigham, D L et al. (1997) Isolation and characterization of americanin, a specific inhibitor of thrombin, from the salivary glands of the lone star tick Amblyomma americanum (L.). Exp Parasitol 87:30-8
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
Zhu, K; Dillwith, J W; Bowman, A S et al. (1997) Identification of hemolytic activity in saliva of the lone star tick (Acari:Ixodidae). J Med Entomol 34:160-6
Bowman, A S; Coons, L B; Needham, G R et al. (1997) Tick saliva: recent advances and implications for vector competence. Med Vet Entomol 11:277-85
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
Zhu, K; Sauer, J R; Bowman, A S et al. (1997) Identification and characterization of anticoagulant activities in the saliva of the lone star tick, Amblyomma americanum (L.). J Parasitol 83:38-43

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