scholarly journals Fate of Bacillus thuringiensis subsp. israelensis in the Field: Evidence for Spore Recycling and Differential Persistence of Toxins in Leaf Litter

2012 ◽  
Vol 78 (23) ◽  
pp. 8362-8367 ◽  
Author(s):  
Guillaume Tetreau ◽  
Mattia Alessi ◽  
Sylvie Veyrenc ◽  
Sophie Périgon ◽  
Jean-Philippe David ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Leaf Litter ◽  
Mosquito Control ◽  
Crystal Form ◽  
High Concentration ◽  
Content Type ◽  
Breeding Sites ◽  
Commercial Mixture ◽  
Field Evidence ◽  
Larval Toxicity

ABSTRACTBacillus thuringiensissubsp.israelensisis a bioinsecticide increasingly used worldwide for mosquito control. Despite its apparent low level of persistence in the field due to the rapid loss of its insecticidal activity, an increasing number of studies suggested that the recycling ofB. thuringiensissubsp.israelensiscan occur under specific, unknown conditions. Decaying leaf litters sampled in mosquito breeding sites in the French Rhône-Alpes region several months after a treatment were shown to exhibit a high level of larval toxicity and contained large amounts of spores. In the present article, we show that the high concentration of toxins found in these litters is consistent with spore recycling in the field, which gave rise to the production of new crystal toxins. Furthermore, in these toxic leaf litter samples, Cry4Aa and Cry4Ba toxins became the major toxins instead of Cyt1Aa in the commercial mixture. In a microcosm experiment performed in the laboratory, we also demonstrated that the toxins, when added in their crystal form to nontoxic leaf litter, exhibited patterns of differential persistence consistent with the proportions of toxins observed in the field-collected toxic leaf litter samples (Cry4 > Cry11 > Cyt). These results give strong evidence thatB. thuringiensissubsp.israelensisrecycled in specific breeding sites containing leaf litters, and one would be justified in asking whether mosquitoes can become resistant when exposed to field-persistentB. thuringiensissubsp.israelensisfor several generations.

scholarly journals Decreased Toxicity of Bacillus thuringiensis subsp. israelensis to Mosquito Larvae after Contact with Leaf Litter

2012 ◽  
Vol 78 (15) ◽  
pp. 5189-5195 ◽  
Author(s):  
Guillaume Tetreau ◽  
Renaud Stalinski ◽  
Dylann Kersusan ◽  
Sylvie Veyrenc ◽  
Jean-Philippe David ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Leaf Litter ◽  
Mosquito Larvae ◽  
Important Food ◽  
Cry Toxins ◽  
Content Type ◽  
Breeding Sites ◽  
Mosquito Breeding ◽  
Important Food Source ◽  
Crystal Toxins

ABSTRACTBacillus thuringiensissubsp.israelensisis a bacterium producing crystals containing Cry and Cyt proteins, which are toxic for mosquito larvae. Nothing is known about the interaction between crystal toxins and decaying leaf litter, which is a major component of several mosquito breeding sites and represents an important food source. In the present work, we investigated the behavior ofB. thuringiensissubsp.israelensistoxic crystals sprayed on leaf litter. In the presence of leaf litter, a 60% decrease in the amount of Cyt toxin detectable by immunology (enzyme-linked immunosorbent assays [ELISAs]) was observed, while the respective proportions of Cry toxins were not affected. The toxicity of Cry toxins towardAedes aegyptilarvae was not affected by leaf litter, while the synergistic effect of Cyt toxins on allB. thuringiensissubsp.israelensisCry toxins was decreased by about 20% when mixed with leaf litter. The toxicity of two commercialB. thuringiensissubsp.israelensisstrains (VectoBac WG and VectoBac 12AS) and a laboratory-producedB. thuringiensissubsp.israelensisstrain decreased by about 70% when mixed with leaf litter. Taken together, these results suggest that Cyt toxins interact with leaf litter, resulting in a decreased toxicity ofB. thuringiensissubsp.israelensisin litter-rich environments and thereby dramatically reducing the efficiency of mosquitocidal treatments.

scholarly journals Distribution of Bacillus thuringiensis subsp. israelensis in Soil of a Swiss Wetland Reserve after 22 Years of Mosquito Control

2011 ◽  
Vol 77 (11) ◽  
pp. 3663-3668 ◽  
Author(s):  
Valeria Guidi ◽  
Nicola Patocchi ◽  
Peter Lüthy ◽  
Mauro Tonolla
Keyword(s):  
Spatial Distribution ◽  
Bacillus Thuringiensis ◽  
Confidence Interval ◽  
Quantitative Pcr ◽  
Mosquito Control ◽  
Soil Samples ◽  
Sampling Point ◽  
Content Type ◽  
Large Numbers ◽  
Continuous Accumulation

ABSTRACTRecurrent treatments withBacillus thuringiensissubsp.israelensisare required to control the floodwater mosquitoAedes vexansthat breeds in large numbers in the wetlands of the Bolle di Magadino Reserve in Canton Ticino, Switzerland. Interventions have been carried out since 1988. In the present study, the spatial distribution of restingB. thuringiensissubsp.israelensisspores in the soil was measured. TheB. thuringiensissubsp.israelensisconcentration was determined in soil samples collected along six transects covering different elevations within the periodically flooded zones. A total of 258 samples were processed and analyzed by quantitative PCR that targeted an identical fragment of 159 bp for theB. thuringiensissubsp.israelensis cry4Aaandcry4Bagenes.B. thuringiensissubsp.israelensisspores were found to persist in soils of the wetland reserve at concentrations of up to 6.8 log per gram of soil. Continuous accumulation due to regular treatments could be excluded, as the decrease in spores amounted to 95.8% (95% confidence interval, 93.9 to 97.7%). The distribution of spores was correlated to the number ofB. thuringiensissubsp.israelensistreatments, the elevation of the sampling point, and the duration of the flooding periods. The number ofB. thuringiensissubsp.israelensistreatments was the major factor influencing the distribution of spores in the different topographic zones (P< 0.0001). These findings indicated thatB. thuringiensissubsp.israelensisspores are rather immobile after their introduction into the environment.

scholarly journals Functional Bacillus thuringiensis Cyt1Aa Is Necessary To Synergize Lysinibacillus sphaericus Binary Toxin (Bin) against Bin-Resistant and -Refractory Mosquito Species

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Nathaly Alexandre Nascimento ◽  
Mary Carmen Torres-Quintero ◽  
Samira López Molina ◽  
Sabino Pacheco ◽  
Tatiany Patrícia Romão ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Insect Resistance ◽  
Mosquito Control ◽  
Specific Binding ◽  
Mosquito Species ◽  
Binary Toxin ◽  
Binding Interaction ◽  
Data Set ◽  
Lysinibacillus Sphaericus ◽  
Content Type

ABSTRACT The binary (Bin) toxin from Lysinibacillus sphaericus is effective to mosquito larvae, but its utilization is threatened by the development of insect resistance. Bin toxin is composed of the BinB subunit required for binding to midgut receptors and the BinA subunit that causes toxicity after cell internalization, mediated by BinB. Culex quinquefasciatus resistance to this toxin is caused by mutations that prevent expression of Bin toxin receptors in the midgut. Previously, it was shown that the Cyt1Aa toxin from Bacillus thuringiensis subsp. israelensis restores Bin toxicity to Bin-resistant C. quinquefasciatus and to Aedes aegypti larvae, which are naturally devoid of functional Bin receptors. Our goal was to elucidate the mechanism involved in Cyt1Aa synergism with Bin in such larvae. In vivo assays showed that the mixture of Bin toxin, or its BinA subunit, with Cyt1Aa was effective to kill resistant larvae. However, no specific binding interaction between Cyt1Aa and the Bin toxin, or its subunits, was observed. The synergy between Cyt1Aa and Bin toxins is dependent on functional Cyt1Aa, as demonstrated by using the nontoxic Cyt1AaV122E mutant toxin affected in oligomerization and membrane insertion, which was unable to synergize Bin toxicity in resistant larvae. The synergism correlated with the internalization of Bin or BinA into anterior and medium midgut epithelial cells, which occurred only in larvae treated with wild-type Cyt1Aa toxin. This toxin is able to overcome failures in the binding step involving BinB receptor by allowing the internalization of Bin toxin, or its BinA subunit, into the midgut cells. IMPORTANCE One promising management strategy for mosquito control is the utilization of a mixture of L. sphaericus and B. thuringiensis subsp. israelensis insecticidal toxins. From this set, Bin and Cyt1Aa toxins synergize and display toxicity to resistant C. quinquefasciatus and to A. aegypti larvae, whose midgut cells lack Bin toxin receptors. Our data set provides evidence that functional Cyt1Aa is essential for internalization of Bin or its BinA subunit into such cells, but binding interaction between Bin and Cyt1Aa is not observed. Thus, this mechanism contrasts with that for the synergy between Cyt1Aa and the B. thuringiensis subsp. israelensis Cry toxins, where active Cyt1Aa is not necessary but a specific binding between Cry and Cyt1Aa is required. Our study established the initial molecular basis of the synergy between Bin and Cyt1Aa, and these findings enlarge our knowledge of their mode of action, which could help to develop improved strategies to cope with insect resistance.

scholarly journals Entomological survey for identification of Aedes larval breeding sites and their distribution in Chattogram, Bangladesh

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Md. Sahidur Rahman ◽  
Md. Omar Faruk ◽  
Sumiya Tanjila ◽  
Nur Mohammad Sabbir ◽  
Najmul Haider ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Field Survey ◽  
Mosquito Control ◽  
Multiple Logistic Regression Analysis ◽  
Binary Logistic Regression ◽  
Breeding Sites ◽  
Entomological Survey ◽  
Different Types ◽  
Coconut Shells ◽  
Positive Properties

Abstract Background Studying the characteristics of Aedes mosquito habitats is essential to control the mosquito population. The objective of this study was to identify the breeding sites of Aedes larvae and their distribution in Chattogram, Bangladesh. We conducted an entomological survey in 12 different sub-districts (Thana) under Chattogram City, during the late monsoon (August to November) 2019. The presence of different wet containers along with their characteristics and immature mosquitoes was recorded in field survey data form. Larvae and/or pupae were collected and brought to the laboratory for identification. Results Different indices like house index, container index, and the Breteau index were estimated. The multiple logistic regression analysis was applied to identify habitats that were more likely to be positive for Aedes larvae/pupae. A total of 704 wet containers of 37 different types from 216 properties were examined, where 52 (7.39%) were positive for Aedes larvae or pupae. Tire, plastic buckets, plastic drums, and coconut shells were the most prevalent container types. The plastic group possessed the highest container productivity (50%) whereas the vehicle and machinery group was found as most efficient (1.83) in terms of immature Aedes production. Among the total positive properties, 8% were infested with Aedes aegypti, 2% with Aedes albopictus, and 1% contained both species Ae. aegypti and A. albopictus. The overall house index was 17.35%, the container index was 7%, and the Breteau index was 24.49. Containers in multistoried houses had significantly lower positivity compared to independent houses. Binary logistic regression represented that containers having shade were 6.7 times more likely to be positive than the containers without shade (p< 0.01). Conclusions These findings might assist the authorities to identify the properties, containers, and geographical areas with different degrees of risk for mosquito control interventions to prevent dengue and other Aedes-borne disease transmissions.

scholarly journals Complete Sequences of Two Plasmids Found in a Brazilian Bacillus thuringiensis Serovar israelensis Strain

2019 ◽  
Vol 8 (9) ◽  
Author(s):  
Fabrício S. Campos ◽  
Fernando B. Cerqueira ◽  
Gil R. Santos ◽  
Eliseu J. G. Pereira ◽  
Roberto F. T. Corrêia ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Crucial Role ◽  
Bacterial Genomes ◽  
Content Type ◽  
Complete Sequences

Plasmids play a crucial role in the evolution of bacterial genomes by mediating horizontal gene transfer. In this work, we sequenced two plasmids found in a Brazilian Bacillus thuringiensis serovar israelensis strain which showed 100% nucleotide identities with Bacillus thuringiensis serovar kurstaki plasmids.

scholarly journals Intracellular and Extracellular Expression of Bacillus thuringiensis Crystal Protein Cry5B in Lactococcus lactis for Use as an Anthelminthic

2015 ◽  
Vol 82 (4) ◽  
pp. 1286-1294 ◽  
Author(s):  
Evelyn Durmaz ◽  
Yan Hu ◽  
Raffi V. Aroian ◽  
Todd R. Klaenhammer
Keyword(s):  
Bacillus Thuringiensis ◽  
Lactococcus Lactis ◽  
Copy Number ◽  
Oral Delivery ◽  
Membrane Integrity ◽  
Biologically Active ◽  
High Copy Number ◽  
Cry Protein ◽  
Western Blots ◽  
Content Type

ABSTRACTTheBacillus thuringiensiscrystal (Cry) protein Cry5B (140 kDa) and a truncated version of the protein, tCry5B (79 kDa), are lethal to nematodes. Genes encoding the two proteins were separately cloned into a high-copy-number vector with a strong constitutive promoter (pTRK593) inLactococcus lactisfor potential oral delivery against parasitic nematode infections. Western blots using a Cry5B-specific antibody revealed that constitutively expressed Cry5B and tCry5B were present in both cells and supernatants. To increase production,cry5Bwas cloned into the high-copy-number plasmid pMSP3535H3, carrying a nisin-inducible promoter. Immunoblotting revealed that 3 h after nisin induction, intracellular Cry5B was strongly induced at 200 ng/ml nisin, without adversely affecting cell viability or cell membrane integrity. Both Cry5B genes were also cloned into plasmid pTRK1061, carrying a promoter and encoding a transcriptional activator that invoke low-level expression of prophage holin and lysin genes inLactococcuslysogens, resulting in a leaky phenotype. Cry5B and tCry5B were actively expressed in the lysogenic strainL. lactisKP1 and released into cell supernatants without affecting culture growth. Lactate dehydrogenase (LDH) assays indicated that Cry5B, but not LDH, leaked from the bacteria. Lastly, using intracellular lysates fromL. lactiscultures expressing both Cry5B and tCry5B,in vivochallenges ofCaenorhabditis elegansworms demonstrated that the Cry proteins were biologically active. Taken together, these results indicate that active Cry5B proteins can be expressed intracellularly in and released extracellularly fromL. lactis, showing potential for future use as an anthelminthic that could be delivered orally in a food-grade microbe.

Cañihua (Chenopodium pallidicaule Aellen) a promising superfood in food industry: a review

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jerry Fredy Gomez Cahuata ◽  
Yessica Estefany Rosas-Quina ◽  
Erika Pachari Vera
Keyword(s):  
Food Industry ◽  
Unsaturated Fatty Acids ◽  
Protein Quality ◽  
Current Knowledge ◽  
Scientific Information ◽  
Essential Amino Acids ◽  
High Concentration ◽  
Content Type ◽  
Functional Value ◽  
Potential Applications

Purpose The purpose of this paper is to divulge the current knowledge about the nutritional and functional characteristics of Cañihua (Chenopodium pallidicaule Aellen), in addition to its potential applications in the food industry since research studies related to it are still limited compared to other cereals of greater diffusion. Design/methodology/approach The scientific information was collected from Web of Science, Scopus and Google Scholar databases, using keywords such as nutrition value of Chenopodium pallidicaule, amaranth and pseudocereals. Consistent information was selected according to its relevance, year of publication and accuracy with the topic. A total of 49 research papers were selected. Findings Cañihua is a grain with high nutritional potential, considered a superfood because it has a high protein quality, a balanced composition of essential amino acids and unsaturated fatty acids, with a high concentration of linoleic and oleic acid. Besides, it has a good level of bioactive compounds with high antioxidant capacity. However, its production and consumption are limited outside its area of origin, although its cultivation is possible under harsh conditions. Originality/value This paper, through a systematic bibliographic review, highlights the potential of cañihua to be considered in the development of food products with high nutritional and functional value. The information compiled will help researchers and professionals become aware of the importance of this grain and join forces in its processing and enhancement of its attributes.

Evaluation of the corrosion behavior of AZ31 magnesium alloy with different protein concentrations

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yucong Ma ◽  
Mohd Talha ◽  
Qi Wang ◽  
Zhonghui Li ◽  
Yuanhua Lin
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Surface Film ◽  
Energy Dispersive Spectrometer ◽  
Inhibitory Effect ◽  
Corrosion Process ◽  
High Concentration ◽  
Content Type ◽  
Atomic Force

Purpose The purpose of this paper is to study systematically the corrosion behavior of AZ31 magnesium (Mg) alloy with different concentrations of bovine serum albumin (BSA) (0, 0.5, 1.0, 1.5, 2.0 and 5.0 g/L). Design/methodology/approach Electrochemical impedance spectroscopy and potential dynamic polarization tests were performed to obtain corrosion parameters. Scanning electrochemical microscopy (SECM) was used to analyze the local electrochemical activity of the surface film. Atomic force microscope (AFM), Scanning electron microscope-Energy dispersive spectrometer and Fourier transform infrared spectroscopy were used to determine the surface morphology and chemical composition of the surface film. Findings Experimental results showed the presence of BSA in a certain concentration range (0 to 2.0 g/L) has a greater inhibitory effect on the corrosion of AZ31, however, the presence of high-concentration BSA (5.0 g/L) would sharply reduce the corrosion resistance. Originality/value When the concentration of BSA is less than 2.0 g/L, the corrosion resistance of AZ31 enhances with the concentration. The adsorption BSA layer will come into being a physical barrier to inhibit the corrosion process. However, high-concentration BSA (5.0 g/L) will chelate with dissolved metal ions (such as Mg and Ni) to form soluble complexes, which increases the roughness of the surface and accelerates the corrosion process.

scholarly journals An Intramolecular Salt Bridge in Bacillus thuringiensis Cry4Ba Toxin Is Involved in the Stability of Helix α-3, Which Is Needed for Oligomerization and Insecticidal Activity

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Sabino Pacheco ◽  
Isabel Gómez ◽  
Jorge Sánchez ◽  
Blanca-Ines García-Gómez ◽  
Mario Soberón ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Double Point ◽  
Single Point ◽  
Three Dimensional ◽  
Point Mutations ◽  
Salt Bridge ◽  
Dimensional Structure ◽  
Cry Toxins ◽  
Content Type ◽  
Domain I

ABSTRACT Bacillus thuringiensis three-domain Cry toxins kill insects by forming pores in the apical membrane of larval midgut cells. Oligomerization of the toxin is an important step for pore formation. Domain I helix α-3 participates in toxin oligomerization. Here we identify an intramolecular salt bridge within helix α-3 of Cry4Ba (D111-K115) that is conserved in many members of the family of three-domain Cry toxins. Single point mutations such as D111K or K115D resulted in proteins severely affected in toxicity. These mutants were also altered in oligomerization, and the mutant K115D was more sensitive to protease digestion. The double point mutant with reversed charges, D111K-K115D, recovered both oligomerization and toxicity, suggesting that this salt bridge is highly important for conservation of the structure of helix α-3 and necessary to promote the correct oligomerization of the toxin. IMPORTANCE Domain I has been shown to be involved in oligomerization through helix α-3 in different Cry toxins, and mutations affecting oligomerization also elicit changes in toxicity. The three-dimensional structure of the Cry4Ba toxin reveals an intramolecular salt bridge in helix α-3 of domain I. Mutations that disrupt this salt bridge resulted in changes in Cry4Ba oligomerization and toxicity, while a double point reciprocal mutation that restored the salt bridge resulted in recovery of toxin oligomerization and toxicity. These data highlight the role of oligomer formation as a key step in Cry4Ba toxicity.

scholarly journals The distribution of Culex mosquitoes in Coimbatore, Tamil Nadu, India

2015 ◽  
Vol 47 (1) ◽  
pp. 1
Author(s):  
A. Naresh Kumar ◽  
K. Murugan ◽  
C. Thomas Vincent ◽  
P. Madhiyazhagan ◽  
T. Nataraj ◽  
...  
Keyword(s):  
Tamil Nadu ◽  
Mosquito Control ◽  
Lymphatic Vessels ◽  
Wuchereria Bancrofti ◽  
Severe Damage ◽  
Breeding Sites ◽  
Ecological Changes ◽  
Mapping System ◽  
Coimbatore District ◽  
Vector Distribution

Lymphatic filariasis is an infection with the filarial worms, <em>Wuchereria bancrofti</em>, <em>Brugia</em> <em>malayi</em> and <em>B. timori</em>. These parasites are transmitted to humans through the bite of an infected <em>Culex</em> mosquito and develop into adult worms in the lymphatic vessels, causing severe damage and swelling (lymphoedema). Mosquito control, in view of their medical as well as economical importance, assumes global importance. Geographic information system (GIS) is a powerful tool to analyse the distribution of mosquitoes and their relationship to different environmental factors, and can substantially improve our ability to quantify the impacts of demographic, climatic and ecological changes in vector distribution. In the present study <em>Culex</em> <em>quinquefasciatus</em>, <em>Culex</em> <em>tritaeniorhynchus</em> and <em>Culex</em> <em>gelidus</em> were recorded in the study area. Few other factors such as larval mosquito density, number of breeding sites, human population, etc. were also analysed for its impact on the distribution of <em>Culex</em> mosquitoes. Distribution of Culex in the present study affirmed that <em>C. quinquefasciatus</em> is predominant in the entire focal area, which explains the behavioural response and capability of the species in varied zones. Information gathered from this study is being used to construct a GIS-based mapping system for distribution of <em>Culex</em> mosquitoes in the Coimbatore District, Tamil Nadu, India.

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