Genes cry 1 Ab e cry 1 Ac de Bacillus thuringiensis
نویسندگان
چکیده
busca por métodos alternativos de controle de insetos-praga tem sido realizada intensamente por diversos grupos de pesquisa no mundo todo, devido à necessidade de uma agricultura mais sustentável e mais comprometida com a preservação do meio ambiente (Bobrowski et al., 2003). Os inseticidas biológicos, utilizados há mais de 50 anos no Brasil, são uma alternativa para o controle mais seletivo de insetos nocivos (Hilder e Boulter, 1999; Betz et al., 2000). Dentre os agentes de controle biológico destaca-se o B. thuringiensis, que é uma bactéria Gram-positiva, a qual sintetiza inclusões cristalinas durante a esporulação, denominadas proteínas Cry, que são codificadas por genes cry. As proteínas do cristal bacteriano apresentam ação tóxica a insetos de diversas ordens, pr incipalmente aos lepidópteros, dípteros, coleópteros (Höfte e Whiteley, 1989; Schnepf et al., 1998). As proteínas da classe Cry1 de B. thuringiensis têm um peso molecular em torno de 130-140 kDa (Höfte e Whiteley, 1989). Após a digestão por tripsinas, no intestino médio de insetos suscetíveis (Tojo e Aizawa, 1983), o fragmento tóxico corresponde a 60-70 kDa (Aronson et al., 1986; Höfte e Whiteley, 1989). Esses peptídeos tóxicos se ligam a receptores específicos nas membranas, onde se formam canais iônicos, aumentando o volume e lise celular, devido à pressão osmótica interna aumentada (Schnepf et al., 1998; Neiva Knaak Mestre em Biologia Laboratório de Microbiologia e PPG-Biologia UNISINOS
منابع مشابه
A Spodoptera exigua cadherin serves as a putative receptor 2 for Bacillus thuringiensis Cry 1 Ca toxin and shows 3 differential enhancement to Cry 1 Ca and Cry 1 Ac toxicity
متن کامل
Isolation of Bacillus thuringiensis strains that contain Dipteran-specific cry genes from Ilha Bela (São Paulo, Brazil) soil samples.
The entomophatogenic bacterium Bacillus thuringiensis produces crystal proteins, named Cry proteins which are encoded by the cry genes. This bacterium is used on biological control of important economical pests, as well as in the control of disease´s vectors, such as Aedes aegypti, a mosquito that transmits the dengue viruses. Isolates of this bacterium can be characterized by the content of cr...
متن کاملScreening of cry gene contents of Bacillus thuringiensis strains isolated from avocado orchards in Mexico, and their insecticidal activity towards Argyrotaenia sp. (Lepidoptera: Tortricidae) larvae.
AIMS To screen for Bacillus thuringiensis strains from avocado orchards in two Mexican states with lepidopteran-specific cry gene content and evaluate their insecticidal activity against Argyrotaenia sp., an undescribed species present in avocado orchards. METHODS AND RESULTS Lepidopteran-active cry1, cry2 and cry9 genes were detected by PCR analysis in 37 isolates. cry1 genes were more frequ...
متن کاملDetection of new cry genes of Bacillus thuringiensis by use of a novel PCR primer system.
On the basis of the known cry gene sequences of Bacillus thuringiensis, three sets of primers were designed from four conserved blocks found in the delta-endotoxin-coding region. The primer pairs designed amplify the regions between blocks 1 and 5, 2 and 5, and 1 and 4. In silico analyses indicated that 100% of the known three-domain cry gene sequences can be amplified by these sets of primers....
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Bacillus thuringiensis is a bacterium used for biopesticides production and pest-resistant plants due to the synthesis of protein crystals by cry genes, which are effective in controlling several insect orders such as Lepidoptera. This work aimed at the evaluation and characterisation of two new B. thuringiensis isolates active against A. gemmatalis (Hübner 1818) larvae, which is the soybean ma...
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