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Bacillus thuringiensis

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https://www.readbyqxmd.com/read/28540040/dna-secondary-structure-formation-by-dna-shuffling-of-the-conserved-domains-of-the-cry-protein-of-bacillus-thuringiensis
#1
Efrain H Pinzon, Daniel A Sierra, Miguel O Suarez, Sergio Orduz, Alvaro M Florez
BACKGROUND: The Cry toxins, or δ-endotoxins, are a diverse group of proteins produced by Bacillus thuringiensis. While DNA secondary structures are biologically relevant, it is unknown if such structures are formed in regions encoding conserved domains of Cry toxins under shuffling conditions. We analyzed 5 holotypes that encode Cry toxins and that grouped into 4 clusters according to their phylogenetic closeness. The mean number of DNA secondary structures that formed and the mean Gibbs free energy [Formula: see text] were determined by an in silico analysis using different experimental DNA shuffling scenarios...
2017: BMC Biophysics
https://www.readbyqxmd.com/read/28539890/insecticidal-effects-of-hemocoelic-delivery-of-bacillus-thuringiensis-cry-toxins-in-achaea-janata-larvae
#2
Thuirei J Ningshen, Vinod K Chauhan, Narender K Dhania, Aparna Dutta-Gupta
Insecticidal effects of Bacillus thuringiensis Cry toxins in hemocoel of larvae have not been properly evaluated. In the present study, hemocoelic injection of four representative Cry toxins i.e., Cry1Aa, Cry1Ab, Cry1Ac, and DOR5 to an economically important lepidopteran insect pest Achaea janata, induced larval mortality, reduced larval growth rate and gave rise to smaller pupae, all in a dose-dependent manner. We observed extensive degeneration as well as the disintegration of larval tissues, most notably, fat body, and the possible involvement of lysosomal enzymes in tissue histolysis...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28539590/abcc2-is-associated-with-bacillus-thuringiensis-cry1ac-toxin-oligomerization-and-membrane-insertion-in-diamondback-moth
#3
Josue Ocelotl, Jorge Sánchez, Isabel Gómez, Bruce E Tabashnik, Alejandra Bravo, Mario Soberón
Cry1A insecticidal toxins bind sequentially to different larval gut proteins facilitating oligomerization, membrane insertion and pore formation. Cry1Ac interaction with cadherin triggers oligomerization. However, a mutation in an ABC transporter gene (ABCC2) is linked to Cry1Ac resistance in Plutella xylostella. Cry1AcMod, engineered to lack helix α-1, was able to form oligomers without cadherinbinding and effectively countered Cry1Ac resistance linked to ABCC2. Here we analyzed Cry1Ac and Cry1AcMod binding and oligomerization by western blots using brush border membrane vesicles (BBMV) from a strain of P...
May 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28535300/magnitude-and-allele-frequency-of-cry1f-resistance-in-field-populations-of-the-fall-armyworm-lepidoptera-noctuidae-in-brazil
#4
O F Santos-Amaya, C S Tavares, J V C Rodrigues, T C Souza, N Rodrigues-Silva, R N C Guedes, A P Alves, E J G Pereira
Bacillus thuringiensis (Bt) corn producing the Cry1F protein was the first highly efficacious Bt corn deployed against the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Brazil, but reduced efficacy of this technology against the fall armyworm has been reported in some regions of the country. Here, we surveyed Cry1F resistance allele frequency and susceptibility of eight S. frugiperda populations collected in 2013 from non-Bt fields in different regions of Brazil. In F1 screen experiments, the overall frequency of the Cry1F resistance alleles in Brazilian populations was estimated at 0...
May 23, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28534112/decolorization-of-textile-dye-rb19-using-volcanic-rock-matrix-immobilized-bacillus-thuringiensis-cells-with-surface-displayed-laccase
#5
Juan Wan, Xiaowen Sun, Cheng Liu, Mengjun Tang, Lin Li, Hong Ni
A triplicate volcanic rock matrix-Bacillus thuringiensis-laccase WlacD (VRMs-Bt-WlacD) dye decolorization system was developed. WlacD was displayed on the B. thuringiensis MB174 cell surface to prepare a whole-cell laccase biocatalyst by using two repeat N-terminal domains of autolysin Mbg (Mbgn)2 as the anchoring motif. Immunofluorescence microscopic assays confirmed that the fusion protein (Mbgn)2-WlacD was anchored on the surface of the recombinant B. thuringiensis MB174. After optimization by a single factor test, L 9(3(4))-orthogonal test, Plackett-Burman test, steepest ascent method, and Box-Behnken response surface methodology, the whole-cell specific laccase activity of B...
June 2017: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28527908/simultaneous-production-of-monoclonal-antibodies-against-bacillus-thuringiensis-bt-cry1-toxins-using-a-mixture-immunization
#6
Sa Dong, Cunzheng Zhang, Yuan Liu, Xiao Zhang, Yajing Xie, Jianfeng Zhong, Chongxin Xu, Xianjin Liu
The detections of Cry1 toxins are mainly dependent on immunoassays based on specific monoclonal antibodies (mAb). In the present study, a mixture immunization with seven Cry1 toxins was administered. The results showed that five mAbs with different characteristics, especially one mAb named 5-E8 which could recognize all the seven Cry1 toxins were obtained. Based on the 5-E8 mAb, a double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA) which can specifically detect the seven Cry1 toxins without cross-reactivity to Cry2A and vip3 was developed with the limit of detection (LOD) and limit of quantification (LOQ) of 6...
May 17, 2017: Analytical Biochemistry
https://www.readbyqxmd.com/read/28527035/comparison-of-rhizosphere-properties-as-affected-by-different-bt-and-non-bt-cotton-gossypium-hirsutum-l-genotypes-and-fertilization
#7
Maqshoof Ahamd, Waleed Mumtaz Abbasi, Moazzam Jamil, Muhammad Iqbal, Azhar Hussain, Muhammad Fakhar-U-Zaman Akhtar, Farheen Nazli
Incorporation of genetically modified crops in the cropping system raises the need for studying the effect of these crops on the soil ecosystem. The current study aimed to compare the effect of Bacillus thuringiensis (Bt)- and non-Bt-cotton (Gossypium hirsutum L.) genotypes on rhizosphere properties under fertilized and unfertilized soil conditions. One non-Bt-cotton (IUB 75) and four Bt-cotton varieties (IUB-222, MM-58, IUB-13, FH-142) were sown in a Randomized Complete Block Design (RCBD) in a factorial fashion with three replications under unfertilized (T1) and fertilized (T2 at NPK 310-170-110 kg ha(-1)) soil conditions...
June 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28521626/experimental-evolution-of-resistance-against-bacillus-thuringiensis-in-the-insect-model-host-galleria-mellonella-results-in-epigenetic-modifications
#8
Krishnendu Mukherjee, Ekaterina Grizanova, Ekaterina Chertkova, Ruediger Lehmann, Ivan Dubovskiy, Andreas Vilcinskas
Epigenetic mechanisms have been proposed to translate environmental stimuli into heritable transgenerational phenotypic variations that can significantly influence natural selection. An intriguing example is exposure to pathogens, which imposes selection for host resistance. To test this hypothesis, we used larvae of the greater wax moth Galleria mellonella as model host to experimentally select for resistance to Bacillus thuringiensis (Bt), the most widely used bacterial agent for the biological control of pest insects...
May 19, 2017: Virulence
https://www.readbyqxmd.com/read/28512299/transgenic-bt-rice-lines-producing-cry1ac-cry2aa-or-cry1ca-have-no-detrimental-effects-on-brown-planthopper-and-pond-wolf-spider
#9
Lin Niu, Amani Mannakkara, Lin Qiu, Xiaoping Wang, Hongxia Hua, Chaoliang Lei, Juan Luis Jurat-Fuentes, Weihua Ma
Transgenic rice expressing cry genes from the bacterium Bacillus thuringiensis (Bt rice) is highly resistant to lepidopteran pests. The brown planthopper (BPH, Nilaparvata lugens) is the main non-target sap-sucking insect pest of Bt transgenic rice. The pond wolf spider (PWS, Pardosa pseudoannulata) is one of the most dominant predators of BPH in rice fields. Consequently, the safety evaluation of Bt rice on BPH and PWS should be conducted before commercialization. In the current study, two experiments were performed to assess the potential ecological effects of Bt rice on BPH and PWS: (1) a tritrophic experiment to evaluate the transmission of Cry1Ac, Cry2Aa and Cry1Ca protein in the food chain; and (2) binding assays of Cry1Ac, Cry2Aa and Cry1Ca to midgut brush border membrane proteins from BPH and PWS...
May 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28506101/evaluation-of-personal-inhalable-aerosol-samplers-with-different-filters-for-use-during-anthrax-responses
#10
Sergey A Grinshpun, Angela M Weber, Michael Yermakov, Reshmi Indugula, Yousef Elmashae, Tiina Reponen, Laura Rose
Risk of inhalation exposure to viable Bacillus anthracis (B. anthracis) spores has primarily been assessed using short-term, stationary sampling methods which may not accurately characterize the concentration of inhalable-sized spores reaching a person's breathing zone. While a variety of aerosol sampling methods have been utilized during previous anthrax responses, no consensus has yet been established for personal air sampling. The goal of this study was to determine the best sampler-filter combination(s) for the collection and extraction of B...
May 16, 2017: Journal of Occupational and Environmental Hygiene
https://www.readbyqxmd.com/read/28505109/the-vip3ag4-insecticidal-protoxin-from-bacillus-thuringiensis-adopts-a-tetrameric-configuration-that-is-maintained-on-proteolysis
#11
Leopoldo Palma, David J Scott, Gemma Harris, Salah-Ud Din, Thomas L Williams, Oliver J Roberts, Mark T Young, Primitivo Caballero, Colin Berry
The Vip3 proteins produced during vegetative growth by strains of the bacterium Bacillus thuringiensis show insecticidal activity against lepidopteran insects with a mechanism of action that may involve pore formation and apoptosis. These proteins are promising supplements to our arsenal of insecticidal proteins, but the molecular details of their activity are not understood. As a first step in the structural characterisation of these proteins, we have analysed their secondary structure and resolved the surface topology of a tetrameric complex of the Vip3Ag4 protein by transmission electron microscopy...
May 14, 2017: Toxins
https://www.readbyqxmd.com/read/28499858/enhanced-behavioral-immune-defenses-in-a-c-%C3%A2-elegans-c-type-lectin-like-domain-gene-mutant
#12
Barbara Pees, Anke Kloock, Rania Nakad, Camilo Barbosa, Katja Dierking
C-type lectin-like domain (CTLD) proteins occupy crucial functions in the immune system of vertebrates, but their role in invertebrate immunity is much less understood. The nematode Caenorhabditis elegans possesses a highly diverse CTLD protein encoding (clec) gene repertoire. A role of C. elegans clec genes in pathogen defense is always assumed, yet experimental evidence for clec immune function is rare. To systematically test the potential function of clec genes in the C. elegans defense against pathogens, we screened 39 clec mutants for survival on the Gram-positive pathogen Bacillus thuringiensis (BT18247) and 37 clec mutants on the Gram-negative pathogen Pseudomonas aeruginosa (PA14)...
May 10, 2017: Developmental and Comparative Immunology
https://www.readbyqxmd.com/read/28495035/selection-of-bacillus-thuringiensis-strains-toxic-to-cotton-boll-weevil-anthonomus-grandis-coleoptera-curculionidae-larvae
#13
Melisa P Pérez, Diego H Sauka, María I Onco, Marcelo F Berretta, Graciela B Benintende
Preliminary bioassays with whole cultures (WC) of 124 Bacillus thuringiensis strains were performed with neonate larvae of Anthonomus grandis, a major cotton pest in Argentina and other regions of the Americas. Three exotic and four native strains were selected for causing more than 50% mortality. All of them were β-exotoxin producers. The native strains shared similar morphology of parasporal crystals, similar protein pattern and identical insecticidal gene profiles. These features resembled Lepidoptera-toxic strains...
May 8, 2017: Revista Argentina de Microbiología
https://www.readbyqxmd.com/read/28492498/assessment-of-inheritance-and-fitness-costs-associated-with-field-evolved-resistance-to-cry3bb1-maize-by-western-corn-rootworm
#14
Aubrey R Paolino, Aaron J Gassmann
The western corn rootworm, Diabrotica virgifera virgifera LeConte, is among the most serious insect pests of maize in North America. One strategy used to manage this pest is transgenic maize that produces one or more crystalline (Cry) toxins derived from the bacterium Bacillus thuringiensis (Bt). To delay Bt resistance by insect pests, refuges of non-Bt maize are grown in conjunction with Bt maize. Two factors influencing the success of the refuge strategy to delay resistance are the inheritance of resistance and fitness costs, with greater delays in resistance expected when inheritance of resistance is recessive and fitness costs are present...
May 11, 2017: Toxins
https://www.readbyqxmd.com/read/28489382/antimicrobial-spirotetronate-metabolites-from-marine-derived-micromonospora-harpali-scsio-gj089
#15
Chun Gui, Shanwen Zhang, Xiangcheng Zhu, Wenjuan Ding, Hongbo Huang, Yu-Cheng Gu, Yanwen Duan, Jianhua Ju
Two new spirotetronate aglycones, 22-dehydroxymethyl-kijanolide (1) and 8-hydroxy-22-dehydroxymethyl-kijanolide (2), along with seven new spirotetronate glycosides, microsporanates A-F (3-8) and tetrocarcin P (9), together with three known tetrocarcins [tetrocarcins A (10), B (11), and AC6H (12)], were isolated from fermentation broths of the marine-derived Micromonospora harpali SCSIO GJ089. The structures of 1-9 were elucidated on the basis of 1D and 2D NMR and MS spectroscopic data. Compounds 3-8 feature an α,β-unsaturated carbonyl moiety within their spirotetronate skeletons...
May 10, 2017: Journal of Natural Products
https://www.readbyqxmd.com/read/28488696/functional-roles-of-cadherin-aminopeptidase-n-and-alkaline-phosphatase-from-helicoverpa-armigera-h%C3%A3-bner-in-the-action-mechanism-of-bacillus-thuringiensis-cry2aa
#16
Man Zhao, Xiangdong Yuan, Jizhen Wei, Wanna Zhang, Bingjie Wang, Myint Myint Khaing, Gemei Liang
A pyramid strategy combining the Cry1A and Cry2A toxins in Bt crops has been widely used throughout the world to delay pest adaption to transgenic crops and broaden the insecticidal spectrum. Midgut membrane-bound cadherin (CAD), aminopeptidase-N (APN) and alkaline phosphatase (ALP) are important for Cry1A toxicity in some lepidopteran larvae, but the proteins that bind Cry2A in the midgut of target insects and their role in the Cry2A mechanism of action are still unclear. In this study, we found that heterologously expressed CAD, APN4 and ALP2 peptides from the midgut of Helicoverpa armigera could bind to the Cry2Aa toxin with a high affinity...
May 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28483999/hybridizing-transgenic-bt-cotton-with-non-bt-cotton-counters-resistance-in-pink-bollworm
#17
Peng Wan, Dong Xu, Shengbo Cong, Yuying Jiang, Yunxin Huang, Jintao Wang, Huaiheng Wu, Ling Wang, Kongming Wu, Yves Carrière, Andrea Mathias, Xianchun Li, Bruce E Tabashnik
Extensive cultivation of crops genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) has suppressed some major pests, reduced insecticide sprays, enhanced pest control by natural enemies, and increased grower profits. However, these benefits are being eroded by evolution of resistance in pests. We report a strategy for combating resistance by crossing transgenic Bt plants with conventional non-Bt plants and then crossing the resulting first-generation (F1) hybrid progeny and sowing the second-generation (F2) seeds...
May 8, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28481307/histopathological-effects-of-bt-and-tcda-insecticidal-proteins-on-the-midgut-epithelium-of-western-corn-rootworm-larvae-diabrotica-virgifera-virgifera
#18
Andrew J Bowling, Heather E Pence, Huarong Li, Sek Yee Tan, Steven L Evans, Kenneth E Narva
Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is a major corn pest in the United States, causing annual losses of over $1 billion. One approach to protect against crop loss by this insect is the use of transgenic corn hybrids expressing one or more crystal (Cry) proteins derived from Bacillus thuringiensis. Cry34Ab1 and Cry35Ab1 together comprise a binary insecticidal toxin with specific activity against WCR. These proteins have been developed as insect resistance traits in commercialized corn hybrids resistant to WCR feeding damage...
May 8, 2017: Toxins
https://www.readbyqxmd.com/read/28479507/complete-genome-sequence-and-bioinformatics-analyses-of-bacillus-thuringiensis-strain-bm-bt15426
#19
Junyan Liu, Lin Li, Brian M Peters, Bing Li, Dingqiang Chen, Zhenbo Xu, Mark E Shirtliff
OBJECTIVES: This study aimed to investigate the genetic characteristics of Bacillus thuringiensis strain BM-BT15426. METHODS: B. thuringiensis strain was identified by sequencing the PCR product (amplifying 16S rRNA gene) using ABI Prism 377 DNA Sequencer. The genome was sequenced using PacBio RS II sequencers and assembled de novo using HGAP. Also, further genome annotation was performed. RESULTS: The genome of B. thuringiensis strain BM-BT15426 has a length of 5,246,329 bp and contains 5409 predicted genes with an average G + C content of 35...
May 4, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28472094/what-are-farmers-really-planting-measuring-the-presence-and-effectiveness-of-bt-cotton-in-pakistan
#20
David J Spielman, Fatima Zaidi, Patricia Zambrano, Asif Ali Khan, Shaukat Ali, H Masooma Naseer Cheema, Hina Nazli, Rao Sohail Ahmad Khan, Arshad Iqbal, Muhammad Amir Zia, Ghulam Muhammad Ali
Genetically modified, insect-resistant Bacillus thuringiensis (Bt) cotton is cultivated extensively in Pakistan. Past studies, however, have raised concerns about the prevalence of Bt cotton varieties possessing weak or nonperforming insect-resistance traits conferred by the cry gene. We examine this issue using data drawn from a representative sample of cotton-growing households that were surveyed in six agroclimatic zones spanning 28 districts in Pakistan in 2013, as well as measurements of Cry protein levels in cotton tissue samples collected from the sampled households' main fields...
2017: PloS One
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