Parasitic castration of snails by larval trematodes, which manifests itself as histopathological changes in the gonads and/or lowered oviposition, represents one of the most dramatic examples of how parasites are capable of modifying the host's internal environment to favor their own growth and reproduction. However, the molecular basis for this phenomenon is still unknown. Preliminary findings show that Schistosoma mansoni infection of the snail Biomphalaria glabrata leads to a depression in oviposition and concurrently in the levels of several host biogenic amines in the CNS and/or plasma, including L-dopa, dopamine, and serotonin. Since these bioamines regulate reproductive activity in other molluscs, this research proposal addresses the hypothesis that parasitic castration by larval schistosomes is due in part to parasite modulation of snail host bioamine levels or enzymes responsible for their synthesis. Using a combination of analytical methods to quantify bioamine levels and enzyme activities in snail tissues, in vivo inhibition experiments, and assays measuring bioamine interaction with host reproductive organs and larval S. mansoni, the investigator will address four specific aims: 1) to determine the effects of schistosome infection on bioamine levels in the central nervous system (CNS), gonads, albumin gland, and cell-free hemolymph (plasma) of the snail host, B. glabrata, 2) to determine the impact of larval infection on key enzymes involved in bioamine synthetic pathways in the CNS, 3) to assess effects of in vivo and in vitro monoamine manipulations on reproductive activity of infected and noninfected snails, and 4) to assess the ability of larval schistosomes to take up and metabolize, or inhibit activity of, host bioamines. Understanding the role of bioamines in snail reproduction and how parasites interfere with their activity may lead to novel methods of biological control based on metabolic disruption of egg production in the vector snail.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI038263-02
Application #
2413728
Study Section
Special Emphasis Panel (ZRG5-TMP (01))
Project Start
1996-05-01
Project End
2000-04-30
Budget Start
1997-05-01
Budget End
1998-04-30
Support Year
2
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Wisconsin Madison
Department
Pathology
Type
Schools of Veterinary Medicine
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Boyle, Jon P; Yoshino, Timothy P (2005) Serotonin-induced muscular activity in Schistosoma mansoni larval stages: importance of 5-HT transport and role in daughter sporocyst production. J Parasitol 91:542-50
Boyle, J P; Hillyer, J F; Yoshino, T P (2003) Pharmacological and autoradiographical characterization of serotonin transporter-like activity in sporocysts of the human blood fluke, Schistosoma mansoni. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 189:631-41
Boyle, Jon P; Wu, Xiao-Jun; Shoemaker, Chuck B et al. (2003) Using RNA interference to manipulate endogenous gene expression in Schistosoma mansoni sporocysts. Mol Biochem Parasitol 128:205-15
Boyle, Jon P; Yoshino, Timothy P (2002) Monoamines in the albumen gland, plasma, and central nervous system of the snail Biomphalaria glabrata during egg-laying. Comp Biochem Physiol A Mol Integr Physiol 132:411-22
Boyle, J P; Zaide, J V; Yoshino, T P (2000) Schistosoma mansoni: effects of serotonin and serotonin receptor antagonists on motility and length of primary sporocysts in vitro. Exp Parasitol 94:217-26
Santhanagopalan, V; Yoshino, T P (2000) Monoamines and their metabolites in the freshwater snail Biomphalaria glabrata. Comp Biochem Physiol A Mol Integr Physiol 125:469-78
Bai, G; Brown, J F; Watson, C et al. (1997) Isolation and characterization of phenoloxidase from egg masses of the gastropod mollusc, Biomphalaria glabrata. Comp Biochem Physiol B Biochem Mol Biol 118:463-9
Bai, G; Johnston, L A; Watson, C O et al. (1997) Phenoloxidase activity in the reproductive system of Biomphalaria glabrata: role in egg production and effect of schistosome infection. J Parasitol 83:852-8