The larvicidal activity of Bacillus thuringiensis Cry proteins against Thaumatotibia leucotreta (Lepidoptera: Tortricidae)

2012 ◽  
Vol 32 ◽  
pp. 47-53 ◽  
Author(s):  
Hua Li ◽  
Gustav Bouwer
Keyword(s):  
Bacillus Thuringiensis ◽  
Larvicidal Activity ◽  
Cry Proteins ◽  
Thaumatotibia Leucotreta

scholarly journals LARVICIDAL ACTIVITY OF BACILLUS THURINGIENSIS ISOLATED FROM Bt COTTON RHIZOSPHERE SOIL AGAINST ANOPHELES MOSQUITO LARVAE (CULICIDAE)

2018 ◽  
Vol 11 (9) ◽  
pp. 456
Author(s):  
Janani Rajendran ◽  
Nathiya Subramanian ◽  
Rajesh Kannan Velu
Keyword(s):  
Bacillus Thuringiensis ◽  
16S Rrna ◽  
Larvicidal Activity ◽  
Rhizosphere Soil ◽  
Anopheles Mosquito ◽  
Cotton Field ◽  
Mosquito Larvae ◽  
Bt Cotton ◽  
Cry Proteins ◽  
Sds Page

Objective: The objective of the study was to isolate and identify Bacillus thuringiensis (Bt) from Bt cotton rhizosphere soil and analyze its larvicidal activity against Anopheles mosquito larvae.Methods: Soil samples were collected from Bt cotton field, and B. thuringiensis was isolated and characterized by biochemical and microscopical characterization. Crystal (Cry) proteins were extracted and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and its larvicidal activity was checked by mortality analysis. Effective Bt isolates were identified by 16S rRNA sequencing.Results: A total of 24 isolates were characterized as Bacillus sp. by biochemical characterization. Further, parasporal inclusion and Cry proteins were extracted, and it was quantified by Bradford assay. The precipitated Cry proteins were analyzed by SDS-PAGE and the results have indicates Cry I protein at 100kDa, Cry3 protein at 44kDa, and cytolytic protein (Cyt) at 29kDa in most of the isolates. Larvicidal activity was checked by the 4th instar Anopheles mosquito larvae. Among the tested isolates, RBL10 and RBL20 have shown the highest percentage of larvicidal activity at 96 and 83%, respectively. Further, the two isolates RBL10 and RBL20 were identified as Bt by 16S rRNA sequencing.Conclusion: B. thuringiensis producing Cry and Cyt proteins posses potential larvicidal activity against Anopheles mosquito larvae which has biological and economic importance in mosquito control.

A STANDARDIZED BIOASSAY FOR LARVICIDAL ACTIVITY OF BACILLUS THURINGIENSIS IN SUNFLOWER MOTH HOMOEOSOMA ELECTELLUM (LEPIDOPTERA: PHYCITIDAE)

1985 ◽  
Vol 117 (1) ◽  
pp. 15-22 ◽  
Author(s):  
R. G. Lidstone ◽  
D. W. Goerzen ◽  
G. G. Khachatourians
Keyword(s):  
Bacillus Thuringiensis ◽  
Larvicidal Activity ◽  
Standard Test ◽  
Mortality Curve ◽  
Bioassay Technique ◽  
Sunflower Moth ◽  
Homoeosoma Electellum ◽  
Third Instar Larvae

AbstractA standard test for the larvicidal activity of Bacillus thuringiensis (B.t.) against the larvae of the sunflower moth Homoeosoma electellum (Hulst) has been developed. Bioassay parameters investigated include diet preparation, concentration of B.t., effect of formaldehyde, and method of pathogen incorporation in diet. The LC50 for seconded third-instar larvae is 1.24 μg of Dipel® WP ml−1 or 19.8 IU B.t. ml−1 pathogen-incorporated diet. Layering of a pathogen-suspension upon the surface of the diet was not a reliable bioassay technique for H. electellum. The addition of formaldehyde in the diet reduced the slope of the dose–mortality curve but did not change the LC50.

scholarly journals New Strategy for Identification of Novel cry-Type Genes from Bacillus thuringiensis Strains

2005 ◽  
Vol 71 (2) ◽  
pp. 761-765 ◽  
Author(s):  
Corina M. Berón ◽  
Leonardo Curatti ◽  
Graciela L. Salerno
Keyword(s):  
Bacillus Thuringiensis ◽  
Phylogenetic Distance ◽  
Cloning And Sequencing ◽  
Degenerate Primers ◽  
Dna Templates ◽  
Cry Proteins ◽  
New Strategy ◽  
Genes Encoding ◽  
Encoding Protein

ABSTRACT We designed five degenerate primers for detection of novel cry genes from Bacillus thuringiensis strains. An efficient strategy was developed based on a two-step PCR approach with these primers in five pair combinations. In the first step, only one of the primer pairs is used in the PCR, which allows amplification of DNA fragments encoding protein regions that include consensus domains of representative proteins belonging to different Cry groups. A second PCR is performed by using the first-step amplification products as DNA templates and the set of five primer combinations. Cloning and sequencing of the last-step amplicons allow both the identification of known cry genes encoding Cry proteins covering a wide phylogenetic distance and the detection and characterization of cry-related sequences from novel B. thuringiensis isolates.

Characterization of cry Genes in a Mexican Bacillus thuringiensis Strain Collection

1998 ◽  
Vol 64 (12) ◽  
pp. 4965-4972 ◽  
Author(s):  
Alejandra Bravo ◽  
Sergio Sarabia ◽  
Lorena Lopez ◽  
Hernesto Ontiveros ◽  
Carolina Abarca ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Specific Primers ◽  
Cry Proteins ◽  
Pcr Product ◽  
Strain Collection ◽  
Lepidopteran Insects ◽  
Ecological Patterns ◽  
Biogeographical Regions ◽  
Selection Of

ABSTRACT Mexico is located in a transition zone between the Nearctic and Neotropical biogeographical regions and contains a rich and unique biodiversity. A total of 496 Bacillus thuringiensis strains were isolated from 503 soil samples collected from the five macroregions of the country. The characterization of the strain collection provided useful information on the ecological patterns of distribution of B. thuringiensis and opportunities for the selection of strains to develop novel bioinsecticidal products. The analysis of the strains was based on multiplex PCR with novel general and specific primers that could detect the cry1,cry3, cry5, cry7, cry8,cry9, cry11, cry12,cry13, cry14, cry21, andcyt genes. The proteins belonging to the Cry1 and Cry9 groups are toxic for lepidopteran insects. The Cry3, Cry7, and Cry8 proteins are active against coleopteran insects. The Cry5, Cry12, Cry13, and Cry14 proteins are nematocidal. The Cry11, Cry21, and Cyt proteins are toxic for dipteran insects. Six pairs of general primers are used in this method. Strains for which unique PCR product profiles were obtained with the general primers were further characterized by additional PCRs with specific primers. Strains containingcry1 genes were the most abundant in our collection (49.5%). Thirty-three different cry1-type profiles were identified. B. thuringiensis strains harboringcry3 genes represented 21.5% of the strains, and 7.9% of the strains contained cry11 and cyt genes.cry7, cry8, and cry9 genes were found in 0.6, 2.4, and 2.6% of the strains, respectively. No strains carrying cry5, cry12, cry13,cry14, or cry21 genes were found. Finally, 14% of the strains did not give any PCR product and did not react with any polyclonal antisera. Our results indicate the presence of strains that may harbor potentially novel Cry proteins as well as strains with combinations of less frequently observed cry genes.

scholarly journals Occurrence and Ear Damage of Helicoverpa zea on Transgenic Bacillus thuringiensis Maize in the Field in Texas, U.S. and Its Susceptibility to Vip3A Protein

Toxins ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 102 ◽  
Author(s):  
Fei Yang ◽  
José C. Santiago González ◽  
Jayme Williams ◽  
Donald C. Cook ◽  
Ryan T. Gilreath ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Zea ◽  
Sustainable Use ◽  
Leaf Tissue ◽  
Corn Earworm ◽  
Laboratory Population ◽  
Bt Maize ◽  
Cry Proteins ◽  
Damage Area ◽  
The U.S

The corn earworm, Helicoverpa zea (Boddie), is a major pest of Bacillus thuringiensis (Bt) maize and cotton in the U.S.. Reduced efficacy of Bt plants expressing Cry1 and Cry2 against H. zea has been reported in some areas of the U.S.. In this study, we evaluated the occurrence and ear damage of H. zea on transgenic Bt maize expressing Cry proteins or a combination of Vip3A and Cry proteins in the field in Texas in 2018. We found that the occurrence of H. zea larvae and the viable kernel damage area on the ear were not different between non-Bt maize and Bt maize expressing Cry1A.105+Cry2Ab2 and Cry1Ab+Cry1F proteins. A total of 67.5% of the pyramided Bt maize expressing Cry1Ab+Cry1F+Vip3A was damaged by 2nd–4th instar larvae of H. zea. Diet bioassays showed that the resistance ratio against Vip3Aa51 for H. zea obtained from Cry1Ab+Cry1F+Vip3A maize was 20.4 compared to a field population collected from Cry1F+Cry1A.105+Cry2Ab2 maize. Leaf tissue bioassays showed that 7-day survivorship on WideStrike3 (Cry1F+Cry1Ac+Vip3A) cotton leaves was significantly higher for the H. zea population collected from Cry1Ab+Cry1F+Vip3A maize than for a Bt-susceptible laboratory population. The results generated from this study suggest that H. zea has evolved practical resistance to Cry1 and Cry2 proteins. Therefore, it is crucial to ensure the sustainable use of the Vip3A technology in Bt maize and cotton.

scholarly journals Rearrangement of N-Terminal α-Helices of Bacillus thuringiensis Cry1Ab Toxin Essential for Oligomer Assembly and Toxicity

Toxins ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 647
Author(s):  
Sabino Pacheco ◽  
Jean Piere Jesus Quiliche ◽  
Isabel Gómez ◽  
Jorge Sánchez ◽  
Mario Soberón ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Conformational Changes ◽  
Membrane Integrity ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Membrane Vesicles ◽  
Insect Midgut ◽  
Cry Proteins ◽  
Cry1ab Toxin ◽  
Domain I

Cry proteins produced by Bacillus thuringiensis are pore-forming toxins that disrupt the membrane integrity of insect midgut cells. The structure of such pore is unknown, but it has been shown that domain I is responsible for oligomerization, membrane insertion and pore formation activity. Specifically, it was proposed that some N-terminal α-helices are lost, leading to conformational changes that trigger oligomerization. We designed a series of mutants to further analyze the molecular rearrangements at the N-terminal region of Cry1Ab toxin that lead to oligomer assembly. For this purpose, we introduced Cys residues at specific positions within α-helices of domain I for their specific labeling with extrinsic fluorophores to perform Föster resonance energy transfer analysis to fluorescent labeled Lys residues located in Domains II–III, or for disulfide bridges formation to restrict mobility of conformational changes. Our data support that helix α-1 of domain I is cleaved out and swings away from the toxin core upon binding with Manduca sexta brush border membrane vesicles. That movement of helix α-2b is also required for the conformational changes involved in oligomerization. These observations are consistent with a model proposing that helices α-2b and α-3 form an extended helix α-3 necessary for oligomer assembly of Cry toxins.

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