Successful parasitism of fly hosts by the ectoparasitoid Nasonia vitripennis is dependent on injection of venom into host pupae. Previous studies have shown that envenomation induces a series of biochemical and immunological changes in the host that are essential to larval development. The host fly dies as a result of the association and death at the cellular level is through an oncotic lytic mechanism. Here we show that cell death is evoked by venom using a signal transduction pathway that involves G-protein activation, followed by phosholipase C stimulation of inositol 1,4,5 triphosphate turnover that promotes mobilization of intracellular calcium. A known G-protein uncoupler, suramide, blocks the effects of wasp venom. Fluorescent microscopy revealed that cultured cells injured by venom lose mitochondrial membrane potential within 15 minutes of intoxication. This is consistent with labeling of smooth endoplasmic reticulum (ER) with the probe ER-tracker that revealed smooth ER were unaltered in morphology 3 hours after exposure to venom. It appears that venom disrupts mitochondrial membrane integrity, resulting in release of intracellular calcium stores and ultimately triggering cell death.
Species 1: Hymenoptera Pteromalidae Nasonia vitripennis
Keywords: oncosis, signal transduction
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