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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVED MASS REARING OF INSECTS FOR BIOLOGICAL CONTROL PROGRAMS THROUGH ADVANCED NUTRITION AND QUALITY CONTROL ANALYSES Title: Eicosanoids in Invertebrate Immunity: An in Vitro Approach

Authors
item Stanley, David
item Miller, Jon - NORTHERN ILLINOIS UNIV

Submitted to: Congress on In Vitro Biology
Publication Type: Abstract Only
Publication Acceptance Date: January 30, 2006
Publication Date: March 1, 2006
Citation: Stanley, D.W., Miller, J. 2006. Eicosanoids in invertebrate immunity: an in vitro approach [abstract]. Congress on In Vitro Biology. 42:A4.

Technical Abstract: Eicosanoids are oxygenated metabolites of arachidonic acid. Two major groups of eicosanoids are prostaglandins (PGs) and various lipoxygenase (LOX) products, all of which exert profound influences in mammals. Eicosanoids also act in insects, where they mediate cellular immune defense reactions to microbial infections and metazoan parasites. In this talk I introduce eicosanoids, review our work on eicosanoid actions in insect immunity, and present new data on cellular resistance to viruses. In our in vitro studies, Manduca sexta hemolymph was collected and diluted. The hemocytes were challenged with bacteria and microaggregation reactions were recorded. Microaggregation reactions increased in challenged preparations. Treating the hemocyte preparations with pharmaceutical inhibitors of eicosanoid biosynthesis disabled the microaggregation reactions. The influence of the pharmaceuticals was reversed by treating the disabled cells with arachidonic acid or with PGH. We infer that hemocytes produce the eicosanoids responsible for mediating cellular immunity in insects. More recently, we considered eicosanoid actions in established insect cell lines. We used two cells lines, one non-permissive to viral infection (HzAM1, a pupal ovarian line from Helicoverpa zea) and one permissive (HvAM1, a pupal ovarian line from Heliothis virescens). Treating the HzAM1 line with inhibitors of eicosanoid biosynthesis, then challenging the cultures with the AcMNPV baculovirus, resulted in significantly increased proportions of cells producing virus and higher overall extracellular virus concentrations. We infer that eicosanoids affect one or more insect cellular mechanism(s) of viral resistance. We report on similar experiments with the permissive line in a poster presentation.

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