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Estudo da atividade tóxica para Aedes aegypti das proteínas Cry4Aa e Cry4Ba de Bacillus thuringiensis expressas em baculovírus recombinantes

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Medicina, 2007. / Submitted by Larissa Ferreira dos Angelos (ferreirangelos@gmail.com) on 2010-01-25T14:46:22Z
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Previous issue date: 2007-06-14 / Os genes cry4Aa e cry4Ba, pertencentes a diferentes estirpes brasileiras de Bacillus thuringiensis, S1806 e S1989, respectivamente, foram amplificados por PCR e clonados em um vetor de clonagem. A análise do seqüenciamento do gene cry4Aa mostrou alta identidade com outras seqüências do gene já descritas e este foi clonado tanto no vetor de transferência pSynXIVVI+X3, como no pFastBac®1 para expressão e análise da toxicidade da proteína heteróloga a partir dos baculovírus construídos por recombinação homóloga, vSyncry4Aa, e por transposição sítio-específica, vBacCry4Aa. O gene cry4Ba foi introduzido no vetor pSynXIVVI+X3 dando origem, por recombinação homóloga, ao baculovírus recombinante vSyncry4Ba. Os vírus recombinantes, derivados de recombinação homóloga, foram isolados em placas de 96 poços, enquanto o vírus recombiante obtido por transposição foi isolado de colônias de células de Escherichia coli DH10BacTM crescidas em placas de Petri contendo antibióticos, X-Gal e IPTG. Células de inseto BTI-TN5B1-4 foram infectadas com os vírus recombinantes isoladamente e mRNA derivados dos extratos celulares (72 h.p.i.) analisados por RT-PCR, para confirmação da expressão e presença de transcritos específicos para os genes. Extratos de larvas de Spodoptera frugiperda, infectadas com os vírus recombinantes (120 h.p.i.) foram analisados por eletroforese em gel de poliacrilamida (SDS-PAGE), mostrando a presença de bandas de aproximadamente 128 e 130 kDa correspondentes aos tamanhos das proteínas Cry4Aa e Cry4Ba, respectivamente. Possíveis cristais das proteínas recombinantes foram observados por microscopia de luz. Bioensaios com os extratos de insetos infectados mostraram-se tóxicos para larvas de segundo instar de Aedes aegypti. _______________________________________________________________________________ ABSTRACT / The cry4Aa and cry4Ba genes from Brazilian strains of Bacillus thuringiensis, S-1806 and S-1989, respectively, were amplified by PCR, cloned into a plasmid cloning vector and sequenced. Sequence analysis of the cry4Aa gene showed high identity to previous known cry genes and it was cloned into both pSynXIVVI+X3 and pFastBac®1 transfer vectors for expression and toxicity analysis of the heterologous proteins derived from the recombinant baculoviruses constructed by homologous recombination (vSynCry4Aa) and transposition (vBacCry4Aa). The cry4Ba gene was introduced into the transfer vector pSynXIVVI+X3/3 resulting in the construction of the recombinant virus vSynCry4Ba by homologous recombination. The recombinant viruses, derived from homologous recombination, were isolated by serial dilution in 96 well plates while the recombinant virus produced by transposition was isolated from Escherichi coli (DH10BacTM) colonies grown on Petri dishes containing antibiotics, X-Gal and IPTG. Insect cells BTI-TN5B1-4 were separetly infected with the recombinante viruses and mRNA from cell extracts (72 h.p.i.) analysed by RT-PCR, in order to confirm the presence of the genes specific transcripts. Recombinant viruses infected insect extracts (120 h p.i.) were analysed by polyacrylamide gel electrophoresis (SDS-PAGE) showing the presence of polypepitide bands of around 128 and 130 kDa, corresponding, respectively to the sizes of the proteins Cry4Aa and Cry4Ba. Putative crystals from the recombinant proteins were observed by light microscopy. Bioassays with virus-infected insect extracts were shown to be toxic to second instar Aedes aegypti larvae.

Identiferoai:union.ndltd.org:IBICT/oai:repositorio.unb.br:10482/3412
Date14 June 2007
CreatorsCorrêa, Roberto Franco Teixeira
ContributorsRibeiro, Bergmann Morais, Monnerat, Rose Gomes
Source SetsIBICT Brazilian ETDs
LanguagePortuguese
Detected LanguageEnglish
Typeinfo:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis
Sourcereponame:Repositório Institucional da UnB, instname:Universidade de Brasília, instacron:UNB
Rightsinfo:eu-repo/semantics/openAccess

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