scholarly journals Potential of Cry10Aa and Cyt2Ba, Two Minority δ-endotoxins Produced by Bacillus thuringiensis ser. israelensis, for the Control of Aedes aegypti Larvae

Toxins ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 355 ◽  
Author(s):  
Daniel Valtierra-de-Luis ◽  
Maite Villanueva ◽  
Liliana Lai ◽  
Trevor Williams ◽  
Primitivo Caballero
Keyword(s):  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Recombinant Proteins ◽  
Synergistic Activity ◽  
Minor Components ◽  
Parasporal Crystal ◽  
Synergistic Interactions ◽  
Bt Toxins ◽  
Mosquitocidal Activity ◽  
The Individual

Bacillus thuringiensis ser. israelensis (Bti) has been widely used as microbial larvicide for the control of many species of mosquitoes and blackflies. The larvicidal activity of Bti resides in Cry and Cyt δ-endotoxins present in the parasporal crystal of this pathogen. The insecticidal activity of the crystal is higher than the activities of the individual toxins, which is likely due to synergistic interactions among the crystal component proteins, particularly those involving Cyt1Aa. In the present study, Cry10Aa and Cyt2Ba were cloned from the commercial larvicide VectoBac-12AS® and expressed in the acrystalliferous Bt strain BMB171 under the cyt1Aa strong promoter of the pSTAB vector. The LC50 values for Aedes aegypti second instar larvae estimated at 24 hpi for these two recombinant proteins (Cry10Aa and Cyt2Ba) were 299.62 and 279.37 ng/mL, respectively. Remarkable synergistic mosquitocidal activity was observed between Cry10Aa and Cyt2Ba (synergistic potentiation of 68.6-fold) when spore + crystal preparations, comprising a mixture of both recombinant strains in equal relative concentrations, were ingested by A. aegypti larvae. This synergistic activity is among the most powerful described so far with Bt toxins and is comparable to that reported for Cyt1A when interacting with Cry4Aa, Cry4Ba or Cry11Aa. Synergistic mosquitocidal activity was also observed between the recombinant proteins Cyt2Ba and Cry4Aa, but in this case, the synergistic potentiation was 4.6-fold. In conclusion, although Cry10Aa and Cyt2Ba are rarely detectable or appear as minor components in the crystals of Bti strains, they represent toxicity factors with a high potential for the control of mosquito populations.

scholarly journals Enhancement of Cry19Aa Mosquitocidal Activity against Aedes aegypti by Mutations in the Putative Loop Regions of Domain II

2004 ◽  
Vol 70 (6) ◽  
pp. 3769-3771 ◽  
Author(s):  
Mohd Amir F. Abdullah ◽  
Donald H. Dean
Keyword(s):  
Bacillus Thuringiensis ◽  
Protein Engineering ◽  
Aedes Aegypti ◽  
Rational Design ◽  
Surface Loop ◽  
Mosquitocidal Activity ◽  
Loop Regions

ABSTRACT Improvements in the mosquitocidal activity of Bacillus thuringiensis Cry19Aa were achieved by protein engineering of putative surface loop residues in domain II through rational design. The improvement of Aedes toxicity in Cry19Aa was 42,000-fold and did not affect its toxicity against Anopheles or Culex.

Cell Based Assays Completed with the Mantle Cell Lymphoma Cell Lines Z138 and NCEB-1 Indicate That Combinations of Bortezomid and Flavopiridol Interact To Achieve Synergistic Activity.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2410-2410 ◽  
Author(s):  
Anita Kapanen ◽  
Catherine Tucker ◽  
Ghania Chikh ◽  
Marcel Bally ◽  
Richard Klasa
Keyword(s):  
Mantle Cell Lymphoma ◽  
Cell Lines ◽  
Cell Lymphoma ◽  
Synergistic Activity ◽  
Individual Agent ◽  
Term Survival ◽  
Combination Effects ◽  
Synergistic Interactions ◽  
Mantle Cell ◽  
The Individual

Abstract Mantle cell lymphoma (MCL) has the poorest long-term survival of all the lymphoma subtypes. CHOP-like regimens currently represent the standard of care for individuals with MCL, but traditional chemotherapeutic regimens do not elicit disease free survival times that are comparable to other sub classes of B-cell lymphomas. Median survival rate of a MCL patient still is approximately 3 years. Therefore new, targeted therapeutics are needed to improve the clinical outcome of MCL. The aim of the study was to identify and characterize combination effects achieved when flavopiridol, a Cyclin D1 inhibitor, and bortezomib, a proteosome inhibitor, are used in a combination setting together or with other agents contained in the CHOP regimen. Two MCL cell lines, Z138 and NCEB-1, were tested for cytotoxicity of drugs alone and in combinations, where alamar blue was used to assess cell viability. The resulting data were analyzed by using the median effect principle introduced by Chou and Talalay. In addition, mechanisms governing measured cytotoxic effects and combination effects were studied by DNA staining (propidium iodine), Caspase 3/7 activation and by western analysis of cyclinD1, NfkB, Bcl-xl, Bax and Bcl-2. The combination of bortezomib and flavopiridol was found to be synergistic in both cell lines studied. Synergistic interactions were dependent on drug-to-drug ratio. In NCEB-1, a ratio 1:12000 (bortezomib:flavopiridol) determined based on the IC90 of each of the individual agents showed synergy over a broad range of fa values (representing the fraction of affected cells). At ratios based on the IC10 and IC50 of the agents when used alone produced effects that were estimated to be antagonistic by the median effect principle. In the Z138 cell line, drug to drug ratios based on the individual agent IC50 and IC90 resulted in synergistic interactions. Consistent with the objective of identifying synergistic combinations, a clear dose reduction was observed to achieve a given therapeutic goal (e.g. 90% cell kill). 10-fold less bortezomib and 55-fold less flavopiridol would be required to achieve 90% cell death/cytostasis based on addition of the agents alone. Mechanistic studies showed that bortezomib in the combination and alone activated the caspase-dependent apoptotic pathway. The combination of bortezomib and flavopiridol for treatment of MCL would appear to an appropriate choice for clinical evaluation, however novel strategies must be developed in order to insure that combination effects observed in cell based screening assays are capture in patients. In this regard it is important to consider drug-drug ratio effects as well as combination engendered toxicities, both parameters that can be evaluated through careful pharmacodynamic assessments in well defined animal models of MCL.

scholarly journals Viability and reconstitution of delta-endotoxins from Bacillus thuringiensis var. israelensis extracts after forty years of storage against Aedes aegypti (Diptera: Culicidae)

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
David Fernández-Chapa ◽  
Hugo Alberto Luna-Olvera ◽  
Jesica Ramirez-Villalobos ◽  
Guadalupe Rojas-Verde ◽  
Katiushka Arévalo-Niño ◽  
...  
Keyword(s):  
Biological Activity ◽  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Storage Conditions ◽  
Prolonged Storage ◽  
Synergistic Activity ◽  
Median Lethal Concentration ◽  
Useful Life ◽  
High Concentrations ◽  
The Stability

Abstract Background Bacillus thuringiensis subsp. israelensis (Bti) produces insecticidal endotoxins known as Cry and Cyt. Its efficiency and specificity make it the most widely used substance as a biopesticide for controlling disease from vector insects, such as mosquitoes, responsible for important human diseases such as malaria, filariasis, dengue, and yellow fevers. To date, it is proven difficult to develop a commercial product that has more than 2 years of shelf life, and there is little information on the viability of these commercial proteins under prolonged storage conditions. Results This study aimed to evaluate biological activity of reconstituted Bti endotoxins after 40 years of storage against the mosquito Aedes aegypti larvae. Five concentrations of Bti extracts were used for bioassays against 3rd and 4th instars of A. aegypti larvae. All reconstituted endotoxins from stored extracts showed a potency increase. The strain HD-500 from extract 3260 was the most effective insecticide (LC50 = 0.0014 mg/l), followed by 3756 (LC50 = 0.0037 mg/l). These strains were particularly notable, increasing their larvicidal potency one hundredfold and one thousandfold, respectively. Protein profiles in polyacrylamide gels revealed a greater presence of Cyt toxins compared to the stored Bti extracts, which maintained their activity at high concentrations. Conclusion The reconstituted Bti strains presented a great biological activity against A. aegypti larvae, specially extract 3260 (median lethal concentration (LC50) value = 0.0014 mg/l). This considerable larvicidal activity after 40 years under storage was an encouraging signal for the development of future formulation strategies regarding their useful life. The stability of extracts of stored endotoxins produced by Bti decreased significantly, particularly Cyt1A protein, which is responsible for their synergistic activity.

Characterization of a novel Bacillus thuringiensis toxin active against Aedes aegypti larvae

Acta Tropica ◽  
2021 ◽  
pp. 106088
Author(s):  
Jiangyu Wu ◽  
Li Wei ◽  
Jiali He ◽  
Kang Fu ◽  
Xinxin Li ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Bacillus Thuringiensis Toxin

scholarly journals Parasporal Body Formation via Overexpression of the Cry10Aa Toxin of Bacillus thuringiensis subsp. israelensis, and Cry10Aa-Cyt1Aa Synergism

2009 ◽  
Vol 75 (14) ◽  
pp. 4661-4667 ◽  
Author(s):  
Alejandro Hernández-Soto ◽  
M. Cristina Del Rincón-Castro ◽  
Ana M. Espinoza ◽  
Jorge E. Ibarra
Keyword(s):  
Bacillus Thuringiensis ◽  
Gradient Centrifugation ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Microbial Control ◽  
Control Agent ◽  
Mass Spectrometry Analysis ◽  
Parasporal Crystal ◽  
Spectrometry Analysis ◽  
Crystal Complex

ABSTRACT Bacillus thuringiensis subsp. israelensis is the most widely used microbial control agent against mosquitoes and blackflies. Its insecticidal success is based on an arsenal of toxins, such as Cry4A, Cry4B, Cry11A, and Cyt1A, harbored in the parasporal crystal of the bacterium. A fifth toxin, Cry10Aa, is synthesized at very low levels; previous attempts to clone and express Cry10Aa were limited, and no parasporal body was formed. By using a new strategy, the whole Cry10A operon was cloned in the pSTAB vector, where both open reading frames ORF1 and ORF2 (and the gap between the two) were located, under the control of the cyt1A operon and the STAB-SD stabilizer sequence characteristic of this vector. Once the acrystalliferous mutant 4Q7 of B. thuringiensis subsp. israelensis was transformed with this construct, parasporal bodies were observed by phase-contrast microscopy and transmission electron microscopy. Discrete, ca. 0.9-μm amorphous parasporal bodies were observed in the mature sporangia, which were readily purified by gradient centrifugation once autolysis had occurred. Pure parasporal bodies showed two major bands of ca. 68 and 56 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. These bands were further characterized by N-terminal sequencing of tryptic fragments using matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis, which identified both bands as the products of ORF1 and ORF2, respectively. Bioassays against fourth-instar larvae of Aedes aegypti of spore-crystal complex and pure crystals of Cry10Aa gave estimated 50% lethal concentrations of 2,061 ng/ml and 239 ng/ml, respectively. Additionally, synergism was clearly detected between Cry10A and Cyt1A, as the synergistic levels (potentiation rates) were estimated at 13.3 for the mixture of Cyt1A crystals and Cry10Aa spore-crystal complex and 12.6 for the combination of Cyt1A and Cry10Aa pure crystals.

scholarly journals Evaluación de dos formulaciones de Bacillus thuringiensis H-14 para el control de larvas de Aedes aegypti

Biomédica ◽  
1987 ◽  
Vol 7 (1-2) ◽  
pp. 5 ◽  
Author(s):  
Marco F. Suárez ◽  
Dwight Ayala ◽  
Michael J. Nelson
Keyword(s):  
Bacillus Thuringiensis ◽  
Aedes Aegypti
Sign in / Sign up

Export Citation Format

Share Document