Jaburetox-induced toxic effects on the hemocytes of Rhodnius prolixus (Hemiptera: Reduviidae)

Abstract

Jaburetox is a recombinant peptide derived from a Canavalia ensiformis urease that presents toxic effects uponseveral species of insects, phytopathogenic fungi and yeasts of medical importance. So far, no toxicity of Jaburetoxto mammals has been shown. Previous reports have identified biochemical targets of this toxic peptide ininsect models, although its mechanism of action is not completely understood. In this work, we aimed to characterizethe effects of Jaburetox in hemolymphatic insect cells. For this purpose, the model insect and Chagas´disease vector Rhodnius prolixus was used. In vivo and in vitro experiments indicated that Jaburetox interacts witha subset of hemocytes and it can be found in various subcellular compartments. In insects injected with Jaburetoxthere was an increase in the gene expression of the enzymes UDP-N-acetylglucosamine pyrophosphorylase(UAP), chitin synthase and nitric oxide synthase (NOS). Nevertheless, the expression of NOS protein, the enzymeactivities of UAP and acid phosphatase (a possible link between UAP and NOS) as well as the phosphorylationstate of proteins remained unchanged upon the in vivo Jaburetox treatment. Nitric oxide (NO) imaging using fluorescentprobes showed that Jaburetox augmented NO production in the hemocyte aggregates when comparedto controls. Even though Jaburetox activated the hemocytes, as demonstrated by wheat germ agglutinin bindingassays, the peptide did not lead to an increase of their phagocytic behavior. Taken together, these findingscontribute to our understanding of toxic effects of Jaburetox, a peptide with biotechnological applications and aprospective tool for rational insect control.