Autor(es): Waniek, Peter J.; Castro, Helena C.; Sathler, Plinio C.; Miceli, Leonardo; Jansen, Ana M.; Araujo, Catarina A. C.

Resumo: Defensins are cysteine-rich peptides involved in the innate immunity of insects and many other organisms. In the present study, two novel defensin-encoding cDNAs and the respective genomic DNAs (def3 and def4) of Triatoma brasiliensis were identified and their tissue-specific and temporal expression was characterized. Both of the deduced mature peptides consisted of 43 amino acid residues and were highly similar to previously identified triatomine defensins (81.4-100%). Semi-quantitative RT-PCR data showed that def3 was constitutively expressed in the fat body and was induced in salivary glands and the small intestine at 5 and 3 days after feeding (daf), respectively. The def4 mRNA level was highly up-regulated in the stomach and fat-body tissues at 5 and 3 daf, respectively. The three-dimensional structures of these defensins were predicted using a homology modeling approach with Def-AAA, the defensin from Anopheles gambiae, as template (62-74% identity). A map of the electrostatic potential of these models revealed that, despite their similar folding patterns, mature Def2 and Def4 have a more cationic structure than is the case for Def1 and Def3 Such differences may orient the antimicrobial profile of these defensins against distinct targets in different organs of the insect. (C) 2009 Elsevier Ltd. All rights reserved.

Palavras-Chave: Defensin; Triatoma brasiliensis; Digestive tract; Insect immunity; Blood feeding

Imprenta: Journal of Insect Physiology, v. 55, n. 9, p. 840-848, 2009

Identificador do objeto digital: 10.1016/j.jinsphys.2009.05.015

Descritores: Aedes aegypti - RT-PCR

Data de publicação: 2009

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