Southern analysis of BT-R 1, the Manduca sexta gene encoding the receptor for the Cry1Ab toxin of Bacillus thuringiensis

1997 ◽  
Vol 256 (5) ◽  
pp. 517-524 ◽  
Author(s):  
S. E. Franklin ◽  
L. Young ◽  
D. Watson ◽  
A. Cigan ◽  
T. Meyer ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Manduca Sexta ◽  
Southern Analysis ◽  
Gene Encoding ◽  
Cry1ab Toxin

scholarly journals The pre-pore from Bacillus thuringiensis Cry1Ab toxin is necessary to induce insect death in Manduca sexta

Peptides ◽  
2008 ◽  
Vol 29 (2) ◽  
pp. 318-323 ◽  
Author(s):  
N. Jiménez-Juárez ◽  
C. Muñoz-Garay ◽  
I. Gómez ◽  
S.S. Gill ◽  
M. Soberón ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Manduca Sexta ◽  
Cry1ab Toxin

Nitric oxide participates in the toxicity of Bacillus thuringiensis Cry1Ab toxin to kill Manduca sexta larvae

Peptides ◽  
2015 ◽  
Vol 68 ◽  
pp. 134-139 ◽  
Author(s):  
Carolina Chavez ◽  
Benito Recio-Tótoro ◽  
Biviana Flores-Escobar ◽  
Humberto Lanz-Mendoza ◽  
Jorge Sanchez ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Bacillus Thuringiensis ◽  
Manduca Sexta ◽  
Cry1ab Toxin ◽  
Manduca Sexta Larvae

scholarly journals Bacillus thuringiensis Bel Protein Enhances the Toxicity of Cry1Ac Protein to Helicoverpa armigera Larvae by Degrading Insect Intestinal Mucin

2009 ◽  
Vol 75 (16) ◽  
pp. 5237-5243 ◽  
Author(s):  
Shangling Fang ◽  
Li Wang ◽  
Wei Guo ◽  
Xia Zhang ◽  
Donghai Peng ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Armigera ◽  
Trichoplusia Ni ◽  
Knockout Mutant ◽  
Gene Encoding ◽  
In Vitro Degradation ◽  
Intestinal Mucin ◽  
Helicoverpa Armígera ◽  
Cry1ac Protein

ABSTRACT Bacillus thuringiensis has been used as a bioinsecticide to control agricultural insects. Bacillus cereus group genomes were found to have a Bacillus enhancin-like (bel) gene, encoding a peptide with 20 to 30% identity to viral enhancin protein, which can enhance viral infection by degradation of the peritrophic matrix (PM) of the insect midgut. In this study, the bel gene was found to have an activity similar to that of the viral enhancin gene. A bel knockout mutant was constructed by using a plasmid-free B. thuringiensis derivative, BMB171. The 50% lethal concentrations of this mutant plus the cry1Ac insecticidal protein gene were about 5.8-fold higher than those of the BMB171 strain. When purified Bel was mixed with the Cry1Ac protein and fed to Helicoverpa armigera larvae, 3 μg/ml Cry1Ac alone induced 34.2% mortality. Meanwhile, the mortality rate rose to 74.4% when the same amount of Cry1Ac was mixed with 0.8 μg/ml of Bel. Microscopic observation showed a significant disruption detected on the midgut PM of H. armigera larvae after they were fed Bel. In vitro degradation assays showed that Bel digested the intestinal mucin (IIM) of Trichoplusia ni and H. armigera larvae to various degrading products, similar to findings for viral enhancin. These results imply Bel toxicity enhancement depends on the destruction of midgut PM and IIM, similar to the case with viral enhancin. This discovery showed that Bel has the potential to enhance insecticidal activity of B. thuringiensis-based biopesticides and transgenic crops.

scholarly journals No Evidence of an Impact on the Rhizosphere Diazotroph Community by the Expression of Bacillus thuringiensis Cry1Ab Toxin by Bt White Spruce

2007 ◽  
Vol 73 (20) ◽  
pp. 6577-6583 ◽  
Author(s):  
Josyanne Lamarche ◽  
Richard C. Hamelin
Keyword(s):  
Bacillus Thuringiensis ◽  
Bacterial Communities ◽  
White Spruce ◽  
Sequencing Analysis ◽  
Nitrogen Fixing ◽  
Cloning And Sequencing ◽  
Insecticidal Toxin ◽  
Soil Bacterial Communities ◽  
Cry1ab Toxin ◽  
Natural Stands

ABSTRACT Nitrogen fixation is one of the most important roles played by soil bacterial communities, as fixation supplies nitrogen to many ecosystems which are often N limited. As impacts on this functional group of bacteria might harm the ecosystem's health and reduce productivity, monitoring that particular group is important. Recently, a field trial with Bt white spruce, which constitutively expresses the Cry1Ab insecticidal toxin of Bacillus thuringiensis, was established. The Bt white spruce was shown to be resistant to spruce budworm. We investigated the possible impact of these genetically modified trees on soil nitrogen-fixing bacterial communities. The trial consisted of untransformed controls, GUS white spruce (transformed with the β-glucuronidase gene), and Bt/GUS white spruce (which constitutively expresses both the Cry1Ab toxin and β-glucuronidase) in a random design. Four years after planting, soil samples from the control and the two treatments from plantation as well as from two natural stands of white spruce were collected. Diazotroph diversity was assessed by extracting soil genomic DNA and amplifying a region of the nitrogenase reductase (nifH) gene, followed by cloning and sequencing. Analysis revealed that nitrogen-fixing communities did not differ significantly among the untransformed control, GUS white spruce, and Bt/GUS white spruce. Nevertheless, differences in diazotroph diversity were observed between white spruce trees from the plantation site and those from two natural stands, one of which grew only a few meters away from the plantation. We therefore conclude, in the absence of evidence that the presence of the B. thuringiensis cry1Ab gene had an effect on diazotroph communities, that either site and/or field preparation prior to planting seems to be more important in determining diazotroph community structure than the presence of Bt white spruce.

Changes in microvilli and Golgi-associated membranes of lepidopteran cells induced by an insecticidally active bacterial δ-endotoxin

1989 ◽  
Vol 93 (2) ◽  
pp. 337-347
Author(s):  
NANCY J. LANE ◽  
J. B. HARRISON ◽  
W. M. LEE
Keyword(s):  
Bacillus Thuringiensis ◽  
Gap Junctions ◽  
Manduca Sexta ◽  
Golgi Complex ◽  
Intramembranous Particle ◽  
Structural Alterations ◽  
Particle Population ◽  
Consistent Increase ◽  
Columnar Cells ◽  
Anterior Midgut

The δ-endotoxin from Bacillus thuringiensis var. kurstaki was fed to late larvae of the tobacco hornworm, Manduca sexta, to determine its effect on the anterior midgut epithelium, which was examined ultrastructurally at intervals thereafter. The cells of the midgut are primarily of the columnar and goblet variety and the effects of the toxin were more pronounced on the former. Tissues examined after only 1–5 min of exposure to the toxin already revealed fine-structural alterations. These were most notably changes in the microvilli and membranes associated spatially with the Golgi complex: vacuoles associated with its maturing face became enlarged. This effect was intensified with more-extensive exposure to the toxin, resulting in an increase in both vacuoles and the number of lysosomal bodies, many containing myelin-like formations; some of these arose as autophagic vacuoles. There seemed to be no consistent increase in endocytotic activity at the apical border, however. The intramembranous particle population of the microvilli of the columnar cells showed some slight changes with toxin treatment; alterations in microvillar contours also occured. The intercellular septate and gap junctions on the lateral borders were sometimes disrupted and with time often became internalized. It seems, then, that the toxin initially modifies the microvillar membranes and subsequently the Golgi-associated saccules are affected, giving rise to vacuoles and lysosomes.

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