title: Biochemical pathway of melanotic encapsulation of Brugia malayi in the mosquito, Armigeres subalbatus.
abstract: The mosquito, Armigeres subalbatus, is naturally resistant to the filarial worm, Brugia malayi, and microfilariae (mf) penetrating the midgut are killed by melanotic encapsulation reactions in the hemocoel within 48 h following ingestion. This vector-parasite system was used to assess changes in hemolymph tyrosine, tyrosine derivatives, and catecholamine-metabolizing enzyme activities using high pressure liquid chromatography with electrochemical detection (HPLC-ED) during melanotic encapsulation reactions against mf. Tyrosine and dopa were detected in the hemolymph of both control and immune-activated (mf-exposed) mosquitoes, but not dopamine or N-acetyl dopamine (NADA). Tyrosine was significantly increased in immune-activated mosquitoes at 6 and 12 h post blood feeding, but was depleted following intrathoracic inoculation of mf in the absence of a blood meal. Dopa also was elevated in immune-activated mosquitoes at 6, 12, and 24 h post-exposure to mf. There were significant increases in phenol oxidase (PO) and dopa decarboxylase (DDC) activities in immune-activated mosquitoes as compared to controls, and these elevated activities were correlated with changes in tyrosine and dopa levels in the hemolymph. No significant differences in N-acetyl transferase (NAT) and dopachrome conversion enzyme (DCE) activities between control and immune-activated mosquitoes were observed. The possible roles these molecules play in melanotic encapsulation reactions of A. subalbatus against mf are discussed.
authors.affiliation: Department of Animal Health and Biomedical Sciences, College of Agricultural and Life Sciences, University of Wisconsin-Madison 53706, USA.
authors.forename: X
authors.initials: X
authors.lastname: Zhao
authors.forename: M T
authors.initials: MT
authors.lastname: Ferdig
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: B M
authors.initials: BM
authors.lastname: Christensen
mesh_terms: D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism; D017178:Brugia malayi / Q000378:metabolism*; D009033:Culicidae / Q000276:immunology* / Q000469:parasitology; D005260:Female; D005849:Gerbillinae; D006458:Hemolymph / Q000737:chemistry; D007113:Immunity, Innate; D008543:Melanins / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000378:metabolism; D014443:Tyrosine / Q000032:analysis
chemical_list: D008543:Melanins; D014443:Tyrosine; D014442:Monophenol Monooxygenase; D001191:Arylamine N-Acetyltransferase