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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 99, No. 5, 2004, pp. 493-498
Bioline Code: oc04106
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 99, No. 5, 2004, pp. 493-498

 en Histopathological and Ultrastructural Effects of δ-endotoxins of Bacillus thuringiensis check for this species in other resources Serovar israelensis in the Midgut of Simulium pertinax check for this species in other resources Larvae (Diptera, Simuliidae)
CFG Cavados; S Majerowicz; JQ Chaves; CJPC Araújo-Coutinho & L Rabinovitch

Abstract

The bacterium Bacillus thuringiensis check for this species in other resources (Bt) produces parasporal crystals containing δ-endotoxins responsible for selective insecticidal activity on larvae. Upon ingestion, these crystals are solubilized in the midgut lumen and converted into active toxins that bind to receptors present on the microvilli causing serious damage to the epithelial columnar cells. We investigated the effect of these endotoxins on larvae of the Simulium pertinax, a common black fly in Brazil, using several concentrations during 4 h of the serovar israelensis strain IPS-82 (LFB-FIOCRUZ 584), serotype H-14 type strain of the Institute Pasteur, Paris. Light and electron microscope observations revealed, by time and endotoxin concentration, increasing damages of the larvae midgut epithelium. The most characteristic effects were midgut columnar cell vacuolization, microvilli damages, epithelium cell contents passing into the midgut lumen and finally the cell death. This article is the first report of the histopathological effects of the Bti endotoxins in the midgut of S. pertinax larvae and the data obtained may contribute to a better understanding of the mode of action of this bacterial strain used as bioinsecticide against black fly larvae.

Keywords
Bacillus thuringiensis serovar israelensis - Simulium pertinax - midgut - histopathology - ultrastructure

 
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