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https://www.readbyqxmd.com/read/29027367/the-parasporal-crystals-of-bacillus-pumilus-strain-15-1-a-potential-virulence-factor
#1
Diana C Garcia-Ramon, Colin Berry, Carmen Tse, Alberto Fernández-Fernández, Antonio Osuna, Susana Vílchez
Bacillus pumilus strain 15.1 was previously found to cause larval mortality in the Med-fly Ceratitis capitata and was shown to produce crystals in association with the spore. As parasporal crystals are well-known as invertebrate-active toxins in entomopathogenic bacteria such as Bacillus thuringiensis (Cry and Cyt toxins) and Lysinibacillus sphaericus (Bin and Cry toxins), the B. pumilus crystals were characterized. The crystals were composed of a 45 kDa protein that was identified as an oxalate decarboxylase by peptide mass fingerprinting, N-terminal sequencing and by comparison with the genome sequence of strain 15...
October 12, 2017: Microbial Biotechnology
https://www.readbyqxmd.com/read/29019656/adsorption-of-insecticidal-crystal-protein-cry11aa-onto-nano-mg-oh-2-effects-on-bioactivity-and-anti-ultraviolet-ability
#2
Xiaohong Pan, Zhangyan Xu, Lan Li, Enshi Shao, Saili Chen, Tengzhou Huang, Zhi Chen, Wenhua Rao, Tianpei Huang, Lingling Zhang, Songqing Wu, Xiong Guan
The traditional Bacillus thuringiensis (Bt) formulation for field applications are not resistant to harsh environmental conditions. Hence, the active ingredients of the Bt bioinsecticides could degrade quickly and has low anti-ultraviolet ability in the field, which significantly limits its practical application. In the present study, we developed an efficient and stable delivery system for Bt Cry11Aa toxins. We coated Cry11Aa proteins with Mg(OH)2 nanoparticles (MHNPs), and then assessed the effects of MHNPs on bioactivity and anti-ultraviolet ability of the Cry11Aa proteins...
October 11, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/29018619/alpha-arylphorin-is-a-mitogen-in-the-heliothis-virescens-midgut-cell-secretome-upon-cry1ac-intoxication
#3
Anais Castagnola, Jerreme Jackson, Omaththage P Perera, Cris Oppert, Shigetoshi Eda, Juan Luis Jurat-Fuentes
Insecticidal crystal (Cry) proteins produced by the bacterium Bacillus thuringiensis (Bt) target cells in the midgut epithelium of susceptible larvae. While the mode of action of Cry toxins has been extensively investigated, the midgut response to Cry intoxication and its regulation are not well characterized. In this work, we describe the secreted proteome (secretome) of primary mature midgut cell cultures from Heliothis virescens larvae after exposure to Cry1Ac toxin compared to control buffer treatment. The Cry1Ac-induced secretome caused higher proliferation and differentiation and an overall reduction in total cell mortality over time in primary H...
2017: PeerJ
https://www.readbyqxmd.com/read/28981636/bitrophic-and-tritrophic-effects-of-transgenic-cry1ab-cry2aj-maize-on-the-beneficial-nontarget-harmonia-axyridis-coleoptera-coccinellidae
#4
Xue Chang, Zengbin Lu, Zhicheng Shen, Yufa Peng, Gongyin Ye
Harmonia axyridis (Pallas) is a common and abundant predator in China and may be exposed to Cry toxins that are produced in Bt crops either by feeding on plant parts or by feeding on target or nontarget herbivorous insects. A new Bt maize line, expressing the Cry1Ab/Cry2Aj fused protein, has been developed and should be rigorously assessed for the ecological risks on the natural enemy. Laboratory experiments were carried out to study the effects of this Bt maize on nontarget predator H. axyridis via bitrophic interaction of adult H...
July 26, 2017: Environmental Entomology
https://www.readbyqxmd.com/read/28958733/identification-of-bacillus-thuringiensis-cry1abmod-binding-proteins-from-spodoptera-frugiperda
#5
Diana L Martínez de Castro, Blanca I García-Gómez, Isabel Gómez, Alejandra Bravo, Mario Soberón
Bacillus thuringiensis Cry toxins are currently used for pest control in transgenic crops but evolution of resistance by the insect pests threatens the use of this technology. The Cry1AbMod toxin was engineered to lack the alpha helix-1 of the parental Cry1Ab toxin and was shown to counter resistance to Cry1Ab and Cry1Ac toxins in different insect species including the fall armyworm Spodoptera frugiperda. In addition, Cry1AbMod showed enhanced toxicity to Cry1Ab-susceptible S. frugiperda populations. To gain insights into the mechanisms of this Cry1AbMod-enhanced toxicity, we isolated the Cry1AbMod toxin binding proteins from S...
September 25, 2017: Peptides
https://www.readbyqxmd.com/read/28940938/downregulation-of-chilo-suppressalis-alkaline-phosphatase-genes-associated-with-resistance-to-three-transgenic-bacillus-thuringiensis-rice-lines
#6
L Qiu, P Wang, T Wu, B Li, X Wang, C Lei, Y Lin, J Zhao, W Ma
Insecticidal crystal (Cry) proteins produced by the bacterium Bacillus thuringiensis are highly toxic to lepidopteran pests. Strains of transgenic rice expressing cry genes have been developed that are resistant to rice pests. Understanding the mode of action of Cry toxins in rice pests will improve our ability to use them effectively as insecticides. In this study, we tested the hypothesis that alkaline phosphatases (ALPs) are involved in Cry1A, Cry2Aa and Cry1Ca toxicity in Chilo suppressalis, an important insect pest of rice crops in China...
September 21, 2017: Insect Molecular Biology
https://www.readbyqxmd.com/read/28939515/broad-specificity-immunoassay-for-detection-of-bacillus-thuringiensis-cry-toxins-through-engineering-of-a-single-chain-variable-fragment-with-mutagenesis-and-screening
#7
Jianfeng Zhong, Xiaodan Hu, Xiao Zhang, Yuan Liu, Chongxin Xu, Cunzheng Zhang, Manman Lin, Xianjin Liu
The cultivation of genetically modified crops (GMCs) has greatly increased worldwide. Given the fact that over 10 Bacillus thuringiensis Cry toxins have been applied in GMCs, there is a need to develop an efficient and economically affordable detection method that simultaneously screen such compounds with similar structures in crops and foodstuff. Here we described an approach using a site-directed mutagenesis that enhances the generic specificity of single chain variable fragment (scFv). After three rounds of panning against mixed antigen (Cry1Ab, Cry1Ac, Cry1B, Cry1C and Cry1F) from the constructed mutagenesis library, one mutant showed greater ability to bind to a range of Cry toxins...
September 19, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28928675/larval-mid-gut-responses-to-sub-lethal-dose-of-cry-toxin-in-lepidopteran-pest-achaea-janata
#8
Vinod K Chauhan, Narender K Dhania, R K Chaitanya, Balasubramanian Senthilkumaran, Aparna Dutta-Gupta
The lack of homogeneity in field application of Bacillus thuringiensis formulation often results in ingestion of sub-lethal doses of the biopesticide by a fraction of pest population and there by promotes the toxin tolerance and resistance in long term. Gut regeneration seems to be one of the possible mechanism by which this is accomplished. However, the existing information is primarily derived from in vitro studies using mid-gut cell cultures. Present study illustrates cellular and molecular changes in mid-gut epithelium of a Bt-susceptible polyphagous insect pest castor semilooper, Achaea janata in response to a Cry toxin formulation...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28901209/the-distinct-properties-of-natural-and-gm-cry-insecticidal-proteins
#9
Jonathan R Latham, Madeleine Love, Angelika Hilbeck
The Cry toxins are a family of crystal-forming proteins produced by the bacterium Bacillus thuringiensis. Their mode of action is thought to be to create pores that disrupt the gut epithelial membranes of juvenile insects. These pores allow pathogen entry into the hemocoel, thereby killing the insect. Genes encoding a spectrum of Cry toxins, including Cry mutants, Cry chimaeras and other Cry derivatives, are used commercially to enhance insect resistance in genetically modified (GM) crops. In most countries of the world, such GM crops are regulated and must be assessed for human and environmental safety...
September 13, 2017: Biotechnology & Genetic Engineering Reviews
https://www.readbyqxmd.com/read/28900215/highly-effective-broad-spectrum-chimeric-larvicide-that-targets-vector-mosquitoes-using-a-lipophilic-protein
#10
Dennis K Bideshi, Hyun-Woo Park, Robert H Hice, Margaret C Wirth, Brian A Federici
Two mosquitocidal bacteria, Bacillus thuringiensis subsp. israelensis (Bti) and Lysinibacillus sphaericus (Ls) are the active ingredients of commercial larvicides used widely to control vector mosquitoes. Bti's efficacy is due to synergistic interactions among four proteins, Cry4Aa, Cry4Ba, Cry11Aa, and Cyt1Aa, whereas Ls's activity is caused by Bin, a heterodimer consisting of BinA, the toxin, and BinB, a midgut-binding protein. Cyt1Aa is lipophilic and synergizes Bti Cry proteins by increasing midgut binding...
September 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28899808/complete-genome-sequence-of-the-nematicidal-bacillus-thuringiensis-mybt18247
#11
Jacqueline Hollensteiner, Anja Poehlein, Cathrin Spröer, Boyke Bunk, Anna E Sheppard, Philip Rosenstiel, Hinrich Schulenburg, Heiko Liesegang
The Gram-positive spore forming bacterium Bacillus thuringiensis MYBT18247 encodes three cry toxin genes, (cry6Ba2, cry6Ba3 and cry21-like) which are active against nematodes. For a better understanding of the evolution of virulence and cry toxins, we present here the complete genome sequence of Bacillus thuringiensis MYBT18247. Various additional virulence factors such as bacteriocins, proteases and hemolysins were identified. In addition, the methylome and the metabolic potential of the strain were analyzed and the strain phylogenetically classified...
September 9, 2017: Journal of Biotechnology
https://www.readbyqxmd.com/read/28872766/ht-supersage-of-the-gut-tissue-of-a-vip3aa-resistant-heliothis-virescens-lepidoptera-noctuidae-strain-provides-insights-into-the-basis-of-resistance
#12
Camilo Ayra-Pardo, Maria E Ochagavía, Ben Raymond, Asim Gulzar, Lianet Rodríguez-Cabrera, Claudia Rodríguez de la Noval, Ivis Morán Bertot, Ryohei Terauchi, Kentaro Yoshida, Hideo Matsumura, Pilar Téllez Rodríguez, Daily Hernández Hernández, Orlando Borrás-Hidalgo, Denis J Wright
Multi-toxin Bt-crops expressing insecticidal toxins with different modes of action e.g. Cry and Vip, are expected to improve resistance management in target pests. While Cry1A resistance has been relatively well characterized in some insect species, this is not the case for Vip3A, for which no mechanism of resistance has yet been identified. Here we applied HT-SuperSAGE to analyze the transcriptome of the gut tissue of tobacco budworm Heliothis virescens (F.) laboratory-selected for Vip3Aa resistance. From a total of 1 324 252 sequence reads, 58951 26-bp tags were obtained representing 17 751 non-singleton unique transcripts (UniTags) from genetically similar Vip3Aa-resistant (Vip-Sel) and susceptible control (Vip-Unsel) strains...
September 5, 2017: Insect Science
https://www.readbyqxmd.com/read/28866859/toxin-gene-contents-and-activity-of-bacillus-thuringiensis-strains-against-two-sugarcane-borer-species-diatraea-saccharalis-f-and-d-flavipennella-box
#13
L M Silva, M C Silva, S M F A Silva, R C Alves, H A A Siqueira, E J Marques
Bacillus thuringiensis (Berliner) bears essential characteristics in the control of insect pests, such as its unique mode of action, which confers specificity and selectivity. This study assessed cry gene contents from Bt strains and their entomotoxicity against Diatraea saccharalis (F.) and Diatraea flavipennella (Box) (Lepidoptera: Crambidae). Bioassays with Bt strains were performed against neonates to evaluate their lethal and sublethal activities and were further analyzed by PCR, using primers to identify toxin genes...
September 2, 2017: Neotropical Entomology
https://www.readbyqxmd.com/read/28852435/complete-genome-sequence-of-the-nematicidal-bacillus-thuringiensis-mybt18246
#14
Jacqueline Hollensteiner, Anja Poehlein, Cathrin Spröer, Boyke Bunk, Anna E Sheppard, Philip Rosentstiel, Hinrich Schulenburg, Heiko Liesegang
10.1601/nm.5000 is a rod-shaped facultative anaerobic spore forming bacterium of the genus 10.1601/nm.4857. The defining feature of the species is the ability to produce parasporal crystal inclusion bodies, consisting of δ-endotoxins, encoded by cry-genes. Here we present the complete annotated genome sequence of the nematicidal 10.1601/nm.5000 strain MYBT18246. The genome comprises one 5,867,749 bp chromosome and 11 plasmids which vary in size from 6330 bp to 150,790 bp. The chromosome contains 6092 protein-coding and 150 RNA genes, including 36 rRNA genes...
2017: Standards in Genomic Sciences
https://www.readbyqxmd.com/read/28821431/bacillus-thuringiensis-cyt2aa2-binding-on-lipid-cholesterol-bilayer-depends-on-protein-concentration-and-time
#15
Sudarat Tharad, Alberto Moreno-Cencerrado, Öykü Üzülmez, Boonhiang Promdonkoy, Jose L Toca-Herrera
Bacillus thuringiensis produces cytolytic proteins (Cyt) that show toxicity against dipteran insect larvae acting directly on the cell membrane. Up to now, two different models have been proposed to explain the interaction mechanism of the cytolytic protein Cyt2Aa2 on lipid membranes: pore-forming and detergent-like action. Here we report on the interaction of Cyt2Aa2 with lipid/cholesterol bilayers at early stage (far from equilibrium) as a function of protein concentration. Quartz crystal microbalance with dissipation (QCM-D) measurements showed that the rate of protein adsorption increased with concentration, although the mass of the final protein-lipid was similar after two hours...
October 14, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28808417/down-regulation-of-aminopeptidase-n-and-abc-transporter-subfamily-g-transcripts-in-cry1ab-and-cry1ac-resistant-asian-corn-borer-ostrinia-furnacalis-lepidoptera-crambidae
#16
Tiantao Zhang, Brad S Coates, Yueqin Wang, Yidong Wang, Shuxiong Bai, Zhenying Wang, Kanglai He
The Asian corn borer (ACB), Ostrinia furnacalis (Lepidoptera: Crambidae), is a highly destructive pest of cultivated maize throughout East Asia. Bacillus thuringiensis (Bt) crystalline protein (Cry) toxins cause mortality by a mechanism involving pore formation or signal transduction following toxin binding to receptors along the midgut lumen of susceptible insects, but this mechanism and mutations therein that lead to resistance are not fully understood. In the current study, quantitative comparisons were made among midgut expressed transcripts from O...
2017: International Journal of Biological Sciences
https://www.readbyqxmd.com/read/28802270/an-intramolecular-salt-bridge-in-bacillus-thuringiensis-cry4ba-toxin-is-involved-in-the-stability-of-helix-%C3%AE-3-which-is-needed-for-oligomerization-and-insecticidal-activity
#17
Sabino Pacheco, Isabel Gómez, Jorge Sánchez, Blanca-Ines García-Gómez, Mario Soberón, Alejandra Bravo
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...
October 15, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28790205/comparative-genomics-of-bacillus-thuringiensis-reveals-a-path-to-specialized-exploitation-of-multiple-invertebrate-hosts
#18
Jinshui Zheng, Qiuling Gao, Linlin Liu, Hualin Liu, Yueying Wang, Donghai Peng, Lifang Ruan, Ben Raymond, Ming Sun
Understanding the genetic basis of host shifts is a key genomic question for pathogen and parasite biology. The Bacillus cereus group, which encompasses Bacillus thuringiensis and Bacillus anthracis, contains pathogens that can infect insects, nematodes, and vertebrates. Since the target range of the essential virulence factors (Cry toxins) and many isolates is well known, this group presents a powerful system for investigating how pathogens can diversify and adapt to phylogenetically distant hosts. Specialization to exploit insects occurs at the level of the major clade and is associated with substantial changes in the core genome, and host switching between insect orders has occurred repeatedly within subclades...
August 8, 2017: MBio
https://www.readbyqxmd.com/read/28780070/identification-of-cry48aa-cry49aa-toxin-ligands-in-the-midgut-of-culex-quinquefasciatus-larvae
#19
Tatiana Maria Teodoro Rezende, Tatiany Patrícia Romão, Michel Batista, Colin Berry, Michael J Adang, Maria Helena Neves Lobo Silva-Filha
A binary mosquitocidal toxin composed of a three-domain Cry-like toxin (Cry48Aa) and a binary-like toxin (Cry49Aa) was identified in Lysinibacillus sphaericus. Cry48Aa/Cry49Aa has action on Culex quinquefasciatus larvae, in particular, to those that are resistant to the Bin Binary toxin, which is the major insecticidal factor from L. sphaericus-based biolarvicides, indicating that Cry48Aa/Cry49Aa interacts with distinct target sites in the midgut and can overcome Bin toxin resistance. This study aimed to identify Cry48Aa/Cry49Aa ligands in C...
September 2017: Insect Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28777960/in-situ-surface-transfer-process-of-cry1ac-protein-on-sio2%C3%AF-the-effect-of-biosurfactants-for-desorption
#20
Shuzhou Miao, Xingzhong Yuan, Yunshan Liang, Hou Wang, Lijian Leng, Zhibin Wu, Longbo Jiang, Yifu Li, Dan Mo, Guangming Zeng
Genetically modified Bacillus thuringiensis (Bt) crops, which have been widely used in agricultural transgenic plants, express insecticidal Cry proteins and release the toxin into soils. Taking into consideration the environmental risk of Cry proteins, biosurfactant-rhamnolipids were applied to desorb Cry proteins from soil environment, which has not been elucidated before. Quartz crystal microbalance with dissipation (QCM-D) was used in this article to investigate the adsorption and desorption behaviors of Cry1Ac on SiO2 surface (model soil)...
July 25, 2017: Journal of Hazardous Materials
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