Cry1ac Toxin
Mostrando 13-24 de 47 artigos, teses e dissertações.
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13. Aggregation of Bacillus thuringiensis Cry1A Toxins upon Binding to Target Insect Larval Midgut Vesicles
During sporulation, Bacillus thuringiensis produces crystalline inclusions comprised of a mixture of δ-endotoxins. Following ingestion by insect larvae, these inclusion proteins are solubilized, and the protoxins are converted to toxins. These bind specifically to receptors on the surfaces of midgut apical cells and are then incorporated into the membrane t
American Society for Microbiology.
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14. Denaturation of Either Manduca sexta Aminopeptidase N or Bacillus thuringiensis Cry1A Toxins Exposes Binding Epitopes Hidden under Nondenaturing Conditions
The effect of polypeptide denaturation of Bacillus thuringiensis Cry1A toxins or purified Manduca sexta 120-kDa aminopeptidase N on the specificities of their interactions was investigated. Ligand and dot blotting experiments were conducted with 125I-labeled Cry1Ac, Cry1Ac mutant 509QNR-AAA511 (QNR-AAA), or 120-kDa aminopeptidase N as the probe. Mutant QNR-A
American Society for Microbiology.
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15. Cross-Resistance of Pink Bollworm (Pectinophora gossypiella) to Bacillus thuringiensis Toxins
Two strains of pink bollworm (Pectinophora gossypiella) selected in the laboratory for resistance to Bacillus thuringiensis toxin Cry1Ac had substantial cross-resistance to Cry1Aa and Cry1Ab but not to Cry1Bb, Cry1Ca, Cry1Da, Cry1Ea, Cry1Ja, Cry2Aa, Cry9Ca, H04, or H205. The narrow spectrum of resistance and the cross-resistance to activated toxin Cry1Ab sug
American Society for Microbiology.
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16. Role of Bacillus thuringiensis Cry1 δ Endotoxin Binding in Determining Potency during Lepidopteran Larval Development
Five economically important crop pests, Manduca sexta, Pieris brassicae, Mamestra brassicae, Spodoptera exigua, and Agrotis ipsilon, were tested at two stages of larval development for susceptibility to Bacillus thuringiensis toxins Cry1Ac, Cry1Ca, Cry1J, and Cry1Ba. Bioassay results for M. sexta showed that resistance to all four Cry toxins increased from t
American Society for Microbiology.
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17. Susceptibility of a Field-Derived, Bacillus thuringiensis-Resistant Strain of Diamondback Moth to In Vitro-Activated Cry1Ac Toxin
Resistant and susceptible populations of the diamondback moth (Plutella xylostella) were tested with crystalline, solubilized, and partially and fully activated forms of the Bacillus thuringiensis Cry1Ac δ-endotoxin. Fully activated toxin greatly reduced the resistance ratio (ratio of the 50% lethal concentration for the resistant population to that for the
American Society for Microbiology.
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18. Intranasal Coadministration of the Cry1Ac Protoxin with Amoebal Lysates Increases Protection against Naegleria fowleri Meningoencephalitis
Cry1Ac protoxin has potent mucosal and systemic adjuvant effects on antibody responses to proteins or polysaccharides. In this work, we examined whether Cry1Ac increased protective immunity against fatal Naegleria fowleri infection in mice, which resembles human primary amoebic meningoencephalitis. Higher immunoglobulin G (IgG) than IgA anti-N. fowleri respo
American Society for Microbiology.
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19. Partial Purification and Characterization of Bacillus thuringiensis Cry1A Toxin Receptor A from Heliothis virescens and Cloning of the Corresponding cDNA
Although extensively studied, the mechanism of action of insecticidal Bacillus thuringiensis Cry toxins remains elusive and requires further elucidation. Toxin receptors in the brush border membrane demand particular attention as they presumably initiate the cascade of events leading to insect mortality after toxin activation. The 170-kDa Cry1Ac toxin-bindin
American Society for Microbiology.
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20. Differential Effects of pH on the Pore-Forming Properties of Bacillus thuringiensis Insecticidal Crystal Toxins
The effect of pH on the pore-forming ability of two Bacillus thuringiensis toxins, Cry1Ac and Cry1C, was examined with midgut brush border membrane vesicles isolated from the tobacco hornworm, Manduca sexta, and a light-scattering assay. In the presence of Cry1Ac, membrane permeability remained high over the entire pH range tested (6.5 to 10.5) for KCl and t
American Society for Microbiology.
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21. Altered Glycosylation of 63- and 68-Kilodalton Microvillar Proteins in Heliothis virescens Correlates with Reduced Cry1 Toxin Binding, Decreased Pore Formation, and Increased Resistance to Bacillus thuringiensis Cry1 Toxins
The binding and pore formation abilities of Cry1A and Cry1Fa Bacillus thuringiensis toxins were analyzed by using brush border membrane vesicles (BBMV) prepared from sensitive (YDK) and resistant (YHD2) strains of Heliothis virescens. 125I-labeled Cry1Aa, Cry1Ab, and Cry1Ac toxins did not bind to BBMV from the resistant YHD2 strain, while specific binding to
American Society for Microbiology.
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22. Effects of Midgut-Protein-Preparative and Ligand Binding Procedures on the Toxin Binding Characteristics of BT-R1, a Common High-Affinity Receptor in Manduca sexta for Cry1A Bacillus thuringiensis Toxins
The identity of the physiologically important Cry1A receptor protein(s) in the lepidopteran Manduca sexta has been a matter of dispute due to the multiple proteins which bind the Cry1Ac toxin. Cry1Aa, Cry1Ab, and Cry1Ac exhibit essentially identical toxicities toward M. sexta larvae and show a high degree of sequence and presumed structural identities. These
American Society for Microbiology.
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23. Binding Analyses of Bacillus thuringiensis Cry δ-Endotoxins Using Brush Border Membrane Vesicles of Ostrinia nubilalis
Transgenic corn expressing the Bacillus thuringiensis Cry1Ab gene is highly insecticidal to Ostrinia nubilalis (European corn borer) larvae. We ascertained whether Cry1F, Cry9C, or Cry9E recognizes the Cry1Ab binding site on the O. nubilalis brush border by three approaches. An optical biosensor technology based on surface plasmon resonance measured binding
American Society for Microbiology.
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24. Ligand specificity and affinity of BT-R1, the Bacillus thuringiensis Cry1A toxin receptor from Manduca sexta, expressed in mammalian and insect cell cultures.
The Manduca sexta receptor for the Bacillus thuringiensis Cry1Aa, Cry1Ab, and Cry1Ac toxins, BT-R1, has been expressed in heterologous cell culture, and its ligand binding characteristics have been determined. When transfected with the BT-R1 cDNA, insect and mammalian cell cultures produce a binding protein of approximately 195 kDa, in contrast to natural BT