Toxic responses induced by the Jack Bean Urease-derived peptide Jaburetox in Rhodnius prolixus, a Chagas? disease vector

LEONARDO L. FRUTTERO; NATALIA R. MOYETTA; MATHEUS V. COSTE GRAHL; MONIQUE SIEBRA KRUG; VALQUIRIA BROLL; FERNANDA STANISÇUASKI; CELIA R. CARLINI

Maceió

Congreso; XXVI Congreso Brasilero IX Congreso Latinoamericano de Entomología.; 2016

Insecticidal properties of ureases from Canavalia ensiformis seeds (Jack bean ureases, JBU) were described more than 10 years ago, although their mechanisms of action are still not completely understood. A recombinant peptide derived from one of C. ensiformis ureases called Jaburetox was shown to be highly toxic and lethal to insects belonging to different orders. Previous findings indicated that the toxic peptide acts on the insects in a complex fashion by forming ionic channels, disrupting lipid membranes and inhibiting diuresis and the transmembrane potential of Malpighian tubules. Moreover, recent data suggested that the central nervous system (CNS) is a target organ for JBU and Jaburetox. In this work, we employed biochemical, molecular and cellular approaches to explore the mode of action of Jaburetox using R. prolixus, one of the main Chagas? disease vectors, as experimental model. In vitro incubations with fluorescent FITC-labeled Jaburetox indicated a high affinity of the peptide for the CNS but not for salivary glands (SG). Jaburetox treatment in vivo (by feeding) and in vitro induced an increment of both the mRNA and the activity of UDP-N-acetylglucosamine pyrophosphorylase (UAP), an enzyme involved in chitin synthesis and glycosylation pathways. On the other hand, in vitro incubations of Jaburetox with CNS and SG homogenates partially inhibited the activity of nitric oxide synthase (NOS), an enzyme involved in nitrinergic signaling. No changes were observed upon Jaburetox treatment in the activity of the enzyme acid phosphatase, a possible link between UAP and NOS. Taken together, these findings contribute to better understanding basic aspects of the biochemistry and neurophysiology of insects and could lead to the development of optimized strategies for insect control.