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bacillus thuringiensis cry1ac toxin-binding and pore-forming activity in brush border membrane vesicles prepared from anterior and posterior midgut regions of lepidopteran larvae.it is generally accepted that bacillus thuringiensis cry toxins insert into the apical membrane of the larval midgut after binding to specific receptors, and there is evidence that the distribution of binding molecules along the midgut is not uniform. by use of the voltage-sensitive dye disc(3)(5) and (125)i-labeled cry1ac, we have measured the effect of cry1ac in terms of permeabilization capacity and of binding parameters on brush border membrane vesicles (bbmv) prepared from the anterior and ...200818223107
employing phage display to study the mode of action of bacillus thuringiensis cry toxins.phage display is an in vitro method for selecting polypeptides with desired properties from a large collection of variants. the insecticidal cry toxins produced by bacillus thuringiensis are highly specific to different insects. various proteins such as cadherin, aminopeptidase-n (apn) and alkaline phosphatase (alp) have been characterized as potential cry-receptors. we used phage display to characterize the cry toxin-receptor interaction(s). by employing phage-libraries that display single-chai ...200818226423
the pre-pore from bacillus thuringiensis cry1ab toxin is necessary to induce insect death in manduca sexta.the insecticidal cry toxins from bacillus thuringiensis bacteria are pore-forming toxins that lyse midgut epithelial cells in insects. we have previously proposed that they form pre-pore oligomeric intermediates before membrane insertion. for formation of these oligomers coiled-coil structures are important, and helix alpha-3 from cry toxins could form coiled-coils. our data shows that different mutations in helix alpha-3 are affected in pore formation and toxicity. mutants affected in toxicity ...200818226424
enhanced exocytosis of the receptor bt-r(1) induced by the cry1ab toxin of bacillus thuringiensis directly correlates to the execution of cell death.cry1ab toxin produced by bacillus thuringiensis exerts insecticidal action upon binding to bt-r(1), a cadherin receptor localized in the midgut epithelium of the tobacco hornworm manduca sexta. the univalent binding of toxin to receptor transmits a death signal into the cell and turns on a multi-step signal transduction pathway involving adenylyl cyclase (ac) and protein kinase a (pka), which drives the biochemical events that culminate in oncotic cell death. here, we report that cell killing by ...200818230416
mining an ostrinia nubilalis midgut expressed sequence tag (est) library for candidate genes and single nucleotide polymorphisms (snps).genes expressed in lepidopteran midgut tissues are involved in digestion and bacillus thuringiensis (bt) toxin resistance traits. five hundred and thirty five unique transcripts were annotated from 1745 high quality o. nubilalis larval midgut expressed sequence tags (ests). full-length cdna sequence of 12 putative serine proteinase genes and 3 partial o. nubilalis aminopeptidase n protein genes, apn1, apn3, and apn4, were obtained, and genes may have roles in plant feeding and bt toxin resistanc ...200819133073
lethal and sublethal effects of endosulfan on apolygus lucorum (hemiptera: miridae).various pesticides directly impact insect pest populations through acute toxicity (lethal) effects, but they also cause a range of indirect (sublethal) effects on pest physiology or behavior. in this study, we describe both lethal and sublethal effects of endosulfan on the survival, development, and fecundity of apolygus lucorum meyer-dür (hemiptera: miridae), an important pest of bacillus thuringiensis (bt) cotton, gossypium hirsutum l., in china. we quantify pesticide effects on adult mirids a ...200819133460
genetic characterization of resistance to deltamethrin in plutella xylostella (lepidoptera: plutellidae) from india.the diamondback moth, plutella xylostella (l.) (lepidoptera: plutellidae), is considered as one of the most difficult pests to control. it has developed resistance not only to synthetic insecticides but also to bacillus thuringiensis-based pesticides. we tested the hypothesis that selection in a p. xylostella population, from hosur, india, with deltamethrin would give a broad spectrum of resistance to several insecticides. we also were interested in genetically classifying resistance to deltamet ...200819133474
efficacy of transgenic cotton expressing cry1ac and cry1f insecticidal protein against heliothines (lepidoptera: noctuidae).cotton, cossypium hirsutum l, plants expressing cry1ac and cry1f (phytogen 440w) insecticidal crystal proteins of bacillus thuringiensis (bt) berliner, were evaluated against natural populations of tobacco budworm, heliothis virescens (f.), and bollworm, helicoverpa zea (boddie) (lepidoptera: noctuidae), across 13 southern u.s. locations that sustained low, moderate, and high infestations. the intrinsic activity of phytogen 440w was compared with nontreated non-bt cotton (psc355) and with manage ...200819133479
lethal activity of two bacillus thuringiensis strains against haemonchus contortus histotropic larvae.the in vitro lethal activity of two bacillus thuringiensis strains (ib-16 and ib-61) against haemonchus contortus histotropic fourth stage larvae (l(4)) was evaluated. each b. thuringiensis strain was used as soluble proteins at different concentrations. in addition, the in vitro lethal dose (ld(50)) of each strain was determined against h. contortus l(4) at different times. data were analyzed by anova and tukey tests. less than 50% mortality was observed at 50 and 100 microg/ml during all bioas ...200819120200
comparative study of the major iranian cereal cultivars and some selected spices in relation to support aspergillus parasiticus growth and aflatoxin production.aflatoxins are toxic fungal metabolites enable to contaminate a wide range of natural substrates. this contamination can be host-specific for different plant species. in this study, the ability of a toxigenic aspergillus parasiticus to produce various aflatoxins on major iranian cereals was evaluated with special focus on plant susceptibility to toxin production at cultivar level.200819079537
delaying insect resistance to transgenic crops. 200819057017
impact of larviciding with a bacillus thuringiensis israelensis formulation, vectobac wg, on dengue mosquito vectors in a dengue endemic site in selangor state, malaysia.the field bioefficacy of a wettable granule (wg) formulation of bacillus thuringiensis israelensis (bti), vectobac wg (bti strain am65-52) against dengue vectors, aedes aegypti and ae albopictus; was evaluated in a suburban residential area (tst) and in a temporary settlement site (kb) in the state of selangor, malaysia. pre-control ovitrap surveillance of the trial sites indicated a high population of both types of aedes mosquitoes. the populations were monitored continuously by weekly ovitrapp ...200819058596
[characteristics of sigl mutant in bacillus thuringiensis hd-73].the purpose of this study was to characterize sigl mutant in bacillus thuringiensis (bt) hd-73, and to determine the function of sigl gene of bt.200819062636
[transformation and expression of specific insecticide gene bt cry3a in resident endogenetic bacteria isolated from apriona germari (hope) larvae intestines].transforming the specific insecticidal gene bt cry3a into the dominant resident endogenetic bacteria in intestines of apriona germari (hope) larvae to construct transgenic bacteria that can colonize and express the insecticidal gene bt cry3a perfectly in intestines of apriona germari (hope) larvae.200819062639
[localization and identification of crystal protein genes in bacillus thuringiensis strain 4.0718].to localize and identify the insecticidal crystal protein genes (cry genes) in high-toxic bacillus thuringiensis strain 4.0718.200819062652
[prediction, overexpression and activity confirmation of adenylation domain in zwittermicin a biosynthesis gene cluster].the adenylation domain is required for the substrate activation of non-ribosomal peptide synthesis. the objective of this research was to prove that 2, 3-diaminopropionate is one of the presume precursors of zwittermicin a biosynthesis.200819062654
molecular level lignin patterns of genetically modified bt-maize mon88017 and three conventional varieties using tetramethylammonium hydroxide (tmah)-induced thermochemolysis.bt-maize mon88017, its near-isogenic line dkc5143, and the two conventional varieties dk315 and benicia were subjected to tetramethylammonium hydroxide (tmah)-induced thermochemolysis to reveal molecular level lignin patterns. mon88017 is genetically modified to express the cry3bb1 protein aimed at the western corn rootworm diabrotica virgifera virgifera, a serious threat for european maize production. the results indicated that roots of the bt-maize were characterized by a slightly enhanced tot ...200819053395
cross-utilization and expression of outer membrane receptor proteins for siderophore uptake by diamondback moth plutella xylostella (lepidoptera: plutellidae) gut bacteria.siderophore production by entomo- and phytopathogens, plus the cross-utilization of these siderophores and expression of outer membrane receptor proteins (omrps) by diamondback moth (dbm) gut bacterial strains, were all examined. all the tested strains grew in the presence of 2, 2'-dipyridyl, and the brachybacterium sp. psgb10, pseudomonas sp. prgb06, and serratia marcescens flgb16 strains were found to cross-utilize the siderophores of various entomopathogens, including bacillus thuringiensis. ...200819054090
increased survival of western corn rootworm on transgenic corn within three generations of on-plant greenhouse selection.to delay evolution of insect resistance to transgenic crops producing bacillus thuringiensis (bt) toxins, nearby "refuges" of host plants not producing bt toxins are required in many regions. such refuges are expected to be most effective in slowing resistance when the toxin concentration in bt crops is high enough to kill all or nearly all insects heterozygous for resistance. however, bt corn, zea mays, introduced recently does not meet this "high-dose" criterion for control of western corn roo ...200819047626
stability and antibacterial activity of bacteriocins produced by bacillus thuringiensis and bacillus thuringiensis ssp. kurstaki.bacteriocins are antimicrobial peptides that are produced by bacteria and toxic to bacterial strains closely related to the producer strain. it has previously been reported that bacillus thuringiensis strain neb17 and bacillus thuringiensis subsp. kurstaki bupm4 produce the bacteriocins thuricin 17 (3,162 da) and bacthuricin f4 (3,160.05 da), respectively. here, we demonstrate that these bacteriocins have functional similarities and show a similar spectrum of antimicrobial activities against ind ...200819047829
robustness in b. thuringiensis metabolic network.the robustness of complex biological networks means that networks are in a position to maintain their functions despite external and internal perturbations. it is a key characteristic of biological networks and might play an important role in the evolutionary process of biological networks. the purpose of this paper is, by investigating the fundamental organizational principles such as the so-called "bow tie" structure, "scale-free" structure and modularity that underlie b. thuringiensis metabol ...200819048474
genetic structure of sesamia nonagrioides (lefebvre) populations in the mediterranean area.the mediterranean corn borer, sesamia nonagrioides (lefebvre) (lepidoptera: noctuidae), is a major pest of maize in the mediterranean area. transgenic bt maize expressing the cry1ab toxin from the bacterium bacillus thuringiensis can effectively control this pest. the characterization of s. nonagrioides population structure, at a large geographical scale, would provide some insight in decision making for resistance management. the genetic relationships among nine populations from spain, one from ...200819036216
population dynamics of sesamia inferens on transgenic rice expressing cry1ac and cpti in southern china.genetically modified insect-resistant rice lines containing the cry1ac gene from bacillus thuringiensis (bt) or the cpti (cowpea trypsin inhibitor) gene developed for the management of lepidopterous pests are highly resistant to the major target pests, chilo suppressalis (walker), cnaphalocrocis medinalis (guenée), and scirpophaga incertulas (walker), in the main rice-growing areas of china. however, the effects of these transgenic lines on sesamia inferens (walker), an important lepidopterous r ...200819036217
amino acids at n- and c-termini are required for the efficient production and folding of a cytolytic delta-endotoxin from bacillus thuringiensis.bacillus thuringiensis cyt2aa toxin is a mosquito-larvicidal and cytolytic delta-endotoxin, which is synthesized as a protoxin and forms crystalline inclusions within the cell. these inclusions are solubilized under alkaline conditions and are activated by proteases within the larval gut. in order to assess the functions of the n-and c-terminal regions of the protoxin, several n- and c-terminal truncated forms of cyt2aa were constructed. it was determined that amino acid removal at the n-termina ...200819017496
coexistence in the eu-return of the moratorium on gm crops? 200818997757
[modeling relationship between sequence characteristics of insecticidal crystal proteins and their inhibitory against plutella xylostella].the knowledge of the relationship between sequence characteristics of insecticidal crystal proteins (icp) and their inhibitory against plutella xylostella provided helpful information for the rational design of icp with desirable activity against plutella xylostella. the four key loops of icp with determined activities against plutella xylostella were selected to study the quantitative relationship between sequence characteristics and insecticidal activity. the first principle components' score ...200818998541
genetic characterization of two putative toxin-antitoxin systems on cryptic plasmids from bacillus thuringiensis strain ybt-1520.a novel putative toxin-antitoxin segregational stability system named kyab system was identified in a novel native plasmid pbmb8240 from bacillus thuringiensis strain ybt-1520, based on sequences homology with other toxin-antitoxin systems, the lethal activity of the kyb putative toxin in escherichia coli and the stabilizing effect of the kyab system in bacillus thuringiensis. secondarily, the native plasmid pbmb9741 from the same strain was resequenced and the corrected plasmid was named as pbm ...200818955810
antibacterial activity of cyt1aa from bacillus thuringiensis subsp. israelensis.cyt1aa is a delta-endotoxin protein that is produced by bacillus thuringiensis subsp. israelensis. it is a membrane pore-forming toxin that is lethal to insect larvae and is broadly cytolytic to vertebrate as well as invertebrate cells. cyt1aa is produced as a protoxin of 27 kda. proteolytic activation results in a reduction of the molecular mass to approximately 23-24 kda and a threefold increase in activity. in this research, cyt1aa crystals were purified from b. thuringiensis ips78/11 harbour ...200818957605
the missing link in petrobactin biosynthesis: asbf encodes a (-)-3-dehydroshikimate dehydratase.the siderophore petrobactin harbors unique 3,4-dihydroxybenzoyl iron-liganding groups. these moieties are known to be synthesized from shikimate pathway precursors, but no reports of the biosynthetic enzymes responsible for this conversion have been published. the gene encoding asbf from bacillus thuringiensis 97-27 was overexpressed in an escherichia coli host. asbf rapidly and efficiently transforms (-)-3-dehydroshikimate (dhs) into 3,4-dihydroxybenzoate (k(cat)(dhs) = 217 +/- 10 min(-1); k(m) ...200818975921
effects of spinosad and bacillus thuringiensis israelensis on a natural population of daphnia pulex in field microcosms.spinosad, a candidate biological larvicide for mosquito control, was evaluated for its effects on a field population of daphnia pulex, using bacillus thuringiensis serovar israelensis (bti) as a reference larvicide. microcosms (125l enclosures) were placed in a shallow temporary oligohaline marsh where d. pulex was present. three concentrations of spinosad (8, 17 and 33 microg l(-1)) and two concentrations of bti (0.16 and 0.50 microl l(-1)) were applied (5 replicates per concentration, includin ...200818977509
field evaluation of a previously untested strain of biolarvicide (bacillus thuringiensis israelensis h14) for mosquito control in an urban area of orissa, india.a previously untested strain of bacillus thuringiensis israelensis (bti) serotype h14 (id no. vcrc b17) has been evaluated under field conditions in an urban area of rourkela city, india for its impact on the larval density of different mosquito species in a variety of habitats. the persistence of the biolarvicide used in an aqueous solution varied in different habitats. the lowest field application rate of 0.5 ml/m2 remained effective for about 10-12 days and provided 80-100% reduction in larva ...200818939694
long lasting persistence of bacillus thuringiensis subsp. israelensis (bti) in mosquito natural habitats.background: the detrimental effects of chemical insecticides on the environment and human health have lead to the call for biological alternatives. today, one of the most promising solutions is the use of spray formulations based on bacillus thuringiensis subsp. israelensis (bti) in insect control programs. as a result, the amounts of bti spread in the environment are expected to increase worldwide, whilst the common belief that commercial bti is easily cleared from the ecosystem has not yet bee ...200818941501
association and decontamination of bacillus spores in a simulated drinking water system.the objective of this work was to elucidate the disinfectant susceptibility of bacillus anthracis sterne (ba) and a commercial preparation of bacillus thuringiensis (bt) spores associated with a simulated drinking water system. biofilms composed of indigenous water system bacteria were accumulated on copper and polyvinyl chloride (pvc) pipe material surfaces in a low-flow pipe loop and uniformly mixed tank reactor (cdc biofilm reactor). application of a distributed shear during spore contact res ...200818947853
evaluation of a granulovirus (pogv) and bacillus thuringiensis subsp. kurstaki for control of the potato tuberworm (lepidoptera: gelechiidae) in stored tubers.liquid suspensions and dry formulations of a granulovirus (family baculoviridae, genus granulovirus, pogv) derived from infected larvae and the bacterium bacillus thuringiensis subsp. kurstaki (berliner) (btk) were evaluated for control of the potato tuberworm, phthorimaea operculella (zeller) (lepidoptera: gelechiidae), in stored tubers. laboratory bioassays at 25 degrees c showed that both pogv and a wettable powder (wp) formulation of btk incorporated with carriers (water, talc, sand, diatoma ...200818950035
yield response of dual-toxin bt cotton to helicoverpa zea infestations.field cage experiments were conducted to determine the impact of bollworms, helicoverpa zea (boddie), on yields of bollgard ii and widestrike cotton, gossypium hirsutum l. one-day-old bollworm larvae were infested in white flowers of bollgard ii and in white flowers and terminals of widestrike cotton. the infestation levels included 0, 50, and 100% of white flowers for each type of cotton. terminal infestations included one or two larvae per terminal on widestrike cotton. larvae were placed in f ...200818950041
baseline susceptibility of cnaphalocrocis medinalis (lepidoptera: pyralidae) to bacillus thuringiensis toxins in china.geographic variability in susceptibility of field-collected cnaphalocrocis medinalis (guenée) (lepidoptera: pyralidae) to bacillus thuringiensis (berliner) was studied to establish a geographic baseline for comparison of future population responses to the increased use of b. thuringiensis-based insect control products. colonies of c. medinalis were established from 10 populations collected from 10 different provinces in the major rice (oryza savita l.)-growing regions of china. populations were ...200818950053
molecular detection of nematicidal crystalliferous bacillus thuringiensis strains of iran and evaluation of their toxicity on free-living and plant-parasitic nematodes.the characterization of nematode-effective strains and cry genes in the iranian bacillus thuringiensis (bt) collection (70 isolates) is presented. characterization was based on pcr analysis using 12 specific primers for cry5, cry6, cry12, cry13, cry14, and cry21 genes encoding proteins active against nematodes, crystal morphology, and protein band patterns as well as their nematicidal activity on root-knot nematode (meloidogyne incognita) and two free-living nematodes (chiloplacus tenuis and acr ...200818923549
specific binding of bacillus thuringiensis cry2a insecticidal proteins to a common site in the midgut of helicoverpa species.for a long time, it has been assumed that the mode of action of cry2a toxins was unique and different from that of other three-domain cry toxins due to their apparent nonspecific and unsaturable binding to an unlimited number of receptors. however, based on the homology of the tertiary structure among three-domain cry toxins, similar modes of action for all of them are expected. to confirm this hypothesis, binding assays were carried out with (125)i-labeled cry2ab. saturation assays showed that ...200818931285
field-evolved resistance to bt toxins. 200818846068
activation of the unfolded protein response is required for defenses against bacterial pore-forming toxin in vivo.pore-forming toxins (pfts) constitute the single largest class of proteinaceous bacterial virulence factors and are made by many of the most important bacterial pathogens. host responses to these toxins are complex and poorly understood. we find that the endoplasmic reticulum unfolded protein response (upr) is activated upon exposure to pfts both in caenorhabditis elegans and in mammalian cells. activation of the upr is protective in vivo against pfts since animals that lack either the ire-1-xbp ...200818846208
atomic force microscopy investigation of phage infection of bacteria.atomic force microscopy (afm) was used to study the process of infection of bacterial cells by bacteriophages, for which purpose experimental protocols were elaborated. three types of bacteriophages were characterized with afm and transmission electron microscopy (tem). bacteriophage interaction with cells was studied for three bacterial hosts: gram-negative escherichia coli 057 and salmonella enteritidis 89 and gram-positive bacillus thuringiensis 393. depending on the phase of lytic cycle, dif ...200818850726
the role of aiia, a quorum-quenching enzyme from bacillus thuringiensis, on the rhizosphere competence.bacteria sense their population density and coordinate the expression of target genes, including virulence factors in gram-negative bacteria, by the n-acylhomoserine lactones (ahls)-dependent quorum-sensing (qs) mechanism. in contrast, several soil bacteria are able to interfere with qs by enzymatic degradation of ahls, referred to as quorum quenching. a potent ahl-degrading enzyme, aiia, of bacillus thuringiensis has been reported to effectively attenuate the virulence of bacteria by quorum que ...200818852506
a 106-kda aminopeptidase is a putative receptor for bacillus thuringiensis cry11ba toxin in the mosquito anopheles gambiae.bacillus thuringiensis (bt) insecticidal toxins bind to receptors on midgut epithelial cells of susceptible insects, and binding triggers biochemical events that lead to insect mortality. recently, a 100-kda aminopeptidase n (apn) was isolated from brush border membrane vesicles (bbmv) of anopheles quadrimaculatus and shown to bind cry11ba toxin with surface plasmon resonance (spr) detection [abdullah et al. (2006) bmc biochem. 7, 16]. in our study, a 106-kda apn, called agapn2, released by phos ...200818826260
solubilization, activation, and insecticidal activity of bacillus thuringiensis serovar thompsoni hd542 crystal proteins.cry15aa protein, produced by bacillus thuringiensis serovar thompsoni hd542 in a crystal together with a 40-kda accompanying protein, is one of a small group of nontypical, less well-studied members of the cry family of insecticidal proteins and may provide an alternative for the more commonly used cry proteins in insect pest management. in this paper, we describe the characterization of the cry15aa and 40-kda protein's biochemical and insecticidal properties and the mode of action. both protein ...200818836017
metalloprotease vsm is the major determinant of toxicity for extracellular products of vibrio splendidus.genomic data combined with reverse genetic approaches have contributed to the characterization of major virulence factors of vibrio species; however, these studies have targeted primarily human pathogens. here, we investigate virulence factors in the oyster pathogen vibrio splendidus lgp32 and show that toxicity is correlated to the presence of a metalloprotease and its corresponding vsm gene. comparative genomics showed that an avirulent strain closely related to lgp32 lacked the metalloproteas ...200818836018
[differential expression protein between the thuringiensin-yield bacillus thuringiensis strain ct-43 and its mutants].the purpose of this research is trying to uncover the biosynthetic or metabolic relative protein of thuringiensis by proteomics.200818837379
isolation, characterization and genome sequencing of phage mztp02 from bacillus thuringiensis mz1.a lysogenic phage, mztp02, was produced via induction by mitomycin c from bacillus thuringiensis (b. thuringiensis) strain mz1. plaques were about 3 mm in diameter with a small inner zone consisting of new b. thuringiensis colonies. electron microscopic analysis showed that mztp02 had a long tail (220 nm x 18 nm) and an icosahedral head (82 nm x 85 nm). mztp02 was insensitive to organic solvents such as chloroform, and infected six b. thuringiensis strains. its complete genome contained 15,717 b ...200818807113
molecular modeling and characterization of the b. thuringiensis and b. thuringiensis ldc-9 cytolytic proteins.the cyt toxins are able to lyse a wide range of cell types in vitro, unlike the cry delta-endotoxins. it exerts its activity by the formation of pores within target cell membranes. the structural information available for cyt2aa (pdb id: 1cby) consists of a single domain in which two outer layers of alpha-helix wrap around a mixed beta-sheet. beta-barrel was suggested as a possible structure of the pores. hence, this study seeks to investigate the structural properties of other cytolytic protein ...200818808203
evaluation of bt (bacillus thuringiensis) rice varieties against stem borer (chilo suppressalis).three transgenic rice varieties namely khazar, neda and nemat, all containing a cry1ab gene, were evaluated through pcr analysis and field examinations for their resistance at natural infestation of insect pests during 2007. the results showed that all transgenic varieties produced 1.2 kb pcr product derived from application of cry1ab gene. in field conditions, transgenic varieties exhibited high levels of resistance against natural infestation of stem borer and the damaged plants based on dead ...200818817142
new strategy for isolating novel nematicidal crystal protein genes from bacillus thuringiensis strain ybt-1518.we have developed a strategy for isolating cry genes from bacillus thuringiensis. the key steps are the construction of a dna library in an acrystalliferous b. thuringiensis host strain and screening for the formation of crystal through optical microscopy observation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) analyses. by this method, three cry genes--cry55aa1, cry6aa2, and cry5ba2--were cloned from rice-shaped crystals, producing b. thuringiensis ybt-1518, which co ...200818820056
reproductive biology of two nontarget insect species, aphis gossypii (homoptera: aphididae) and orius sauteri (hemiptera: anthocoridae), on bt and non-bt cotton cultivars.transgenic bt cotton, engineered to continuously produce activated delta-endotoxins of the soil bacteria bacillus thuringiensis, holds great promise in controlling helicoverpa armigera and other lepidopteran pests. however, it also may impact the invertebrate community, which needs to be clarified. the effects of bt cotton on two nontarget insects, aphis gossypii and orius sauteri, were assessed under semifield and laboratory conditions. mean total duration of nymphal stages of a. gossypii was s ...200818801270
population dynamics of spodoptera litura (lepidoptera: noctuidae) on bt cotton in the yangtze river valley of china.genetically modified cotton that produces a crystalline protein from bacillus thuringiensis subsp. kurstaki (berliner) (bt) has been widely deployed to manage lepidopteran insect pests in cotton growing areas worldwide. however, susceptibility of different insect species to bt protein varies, which may affect lepidopteran pest populations in the field. studies on effects of two transgenic cotton lines (bg1560 and gk19) carrying a cry1a gene on common cutworm spodoptera litura f. (lepidoptera: no ...200818801271
suppression of cotton bollworm in multiple crops in china in areas with bt toxin-containing cotton.transgenic cotton that has been engineered to produce insecticidal toxins from bacillus thuringiensis (bt) and so to resist the pest cotton bollworm (helicoverpa armigera) has been widely planted in asia. analysis of the population dynamics of h. armigera from 1992 to 2007 in china indicated that a marked decrease in regional outbreaks of this pest in multiple crops was associated with the planting of bt cotton. the study area included six provinces in northern china with an annual total of 3 mi ...200818801998
evaluating the insecticidal genes and their expressed products in bacillus thuringiensis strains by combining pcr with mass spectrometry.by a combination of pcr and mass spectrometry, a total of five cry genes (cry1aa, cry1ac, cry2aa, cry2ab, and cry1ia) were detected in genomic dna from the wild-type bacillus thuringiensis strain 4.0718, and three protoxins (cry1aa, cry1ac, and cry2aa) were identified in the strain's parasporal crystals. these results indicated that this complementary method may be useful in evaluating b. thuringiensis strains at both the gene and protein levels.200818791021
characterization of the cry1ac17 gene from an indigenous strain of bacillus thuringiensis subsp. kenyae.an indigenously isolated strain of bacillus thuringiensis subsp. kenyae exhibited toxicity against lepidopteran as well as dipteran insects. the lepidopteran active cry1ac protoxin gene coding sequence of 3.5 kb from this strain was cloned into vector pet28a(+). however, it could not be expressed in commonly used escherichia coli expression hosts, bl21(de3) and bl21(de3)plyss. this gene is classified as cry1ac17 in the b. thuringiensis toxic nomenclature database. the coding sequence of this gen ...200818795364
genetic relationships between sympatric populations of bacillus cereus and bacillus thuringiensis, as revealed by rep-pcr genomic fingerprinting.the bacterial strain bacillus cereus is closely related to bacillus thuringiensis, although any genetic relationship between the two strains is still in debate. using rep-pcr genomic fingerprinting, we established the genetic relationships between brazilian sympatric populations of b. cereus and b. thuringiensis simultaneously collected from two geographically separate sites. we observed the formation of both b. thuringiensis and b. cereus clusters, as well as strains of b. cereus that are more ...200818797766
assessment of the nutritional values of genetically modified wheat, corn, and tomato crops.the genetic modification in fruit and vegetables could lead to changes in metabolic pathways and, therefore, to the variation of the molecular pattern, with particular attention to antioxidant compounds not well-described in the literature. the aim of the present study was to compare the quality composition of transgenic wheat ( triticum durum l.), corn ( zea mays l.), and tomato ( lycopersicum esculentum mill.) to the nontransgenic control with a similar genetic background. in the first experim ...200818781763
location of the bombyx mori 175kda cadherin-like protein-binding site on bacillus thuringiensis cry1aa toxin.to identify and gain a better understanding of the cadherin-like receptor-binding site on bacillus thuringiensis cry toxins, it is advantageous to use cry1aa toxin, because its 3d structure is known. therefore, cry1aa toxin was used to examine the locations of cadherin-like protein-binding sites. initial experiments examining the binding compatibility for cry1aa toxin of partial fragments of recombinant proteins of a 175kda cadherin-like protein from bombyx mori (btr175) and another putative rec ...200818783429
proteomic analysis of the peritrophic matrix from the gut of the caterpillar, helicoverpa armigera.the peritrophic matrix from the midgut of the caterpillar, helicovera armigera, was solubilized by treatment with anhydrous trifluoromethanesulfonic acid, apparently by depolymerisation of its chitin component. this allowed the efficient extraction of proteins in a technique that may be broadly applicable to the analysis of other structures containing chitin. gel electrophoresis and mass spectrometry of tryptic peptides were used to identify the extracted proteins with gut-expressed cdna sequenc ...200818760362
transcriptional analysis of the conjugative plasmid paw63 from bacillus thuringiensis.the broad-host range plasmid paw63 is a model for the study of molecular mechanisms associated with conjugation in the gram-positive bacillus cereus group. its main features are a conjugative apparatus that includes type iv secretion system-like components and two group ii introns, b.th.i1 and b.th.i2, located within conjugation genes, as well as a putative regulatory control circuit. furthermore, paw63 shares a common backbone with pxo2, the second virulence plasmid of bacillus anthracis, and w ...200818761035
effects of bt transgenic chinese cabbage on the herbivore mamestra brassicae (lepidoptera: noctuidae) and its parasitoid microplitis mediator (hymenoptera: braconidae).we investigated the effects of a diamondback moth-resistant chinese cabbage (brassica campestris subsp napus variety pekinensis makino), expressing the insecticidal protein cryla(c) toxin derived from bacillus thuringiensis, on the nontarget herbivore mamestra brassicae (l.) (lepidoptera: noctuidae) and its parasitoid wasp microplitis mediator (haliday) (hymenoptera: braconidae). a decreased survival rate at neonate stage was observed in m. brassicae when reared on bt cabbage, although overall d ...200818767720
influence of molting on efficacy of two functionally different larvicides: bti and temephos.the sensitivity of the second, third (l3), and fourth (l4) instars of culex pipiens l. and ochlerotatus sticticus (meigen) to two larvicides, temephos and bacillus thuringiensis variety israelensis (bti) was tested with and without molting occurring in the experiments. in the first experiment for both tested mosquito species, lc50 values increased from the second to the fourth instar when tested against temephos, whereas for bti the opposite trend was observed. the highest lc50 value was found f ...200818767729
survivorship of helicoverpa zea and heliothis virescens on cotton plant structures expressing a bacillus thuringiensis vegetative insecticidal protein.a series of tests quantified bollworm, helicoverpa zea (boddie), and tobacco budworm, heliothis virescens (f.), larval survival on plant structures of a nontransgenic cotton (gossypium hirsutum l.), 'coker 312', and two transgenic cottons expressing vip3a protein or both vip3a + crylab proteins (vipcot). vegetative and reproductive structures including terminal leaves, flower bud (square) bracts, whole debracted squares, flower petals, flower anthers, and intact capsules (bolls) were harvested f ...200818767734
an empirical test of the f2 screen for detection of bacillus thuringiensis-resistance alleles in tobacco budworm (lepidoptera: noctuidae).insects exposed to genetically modified crops expressing bacillus thuringiensis (bt) toxins are under intense selection pressure that could result on widespread bt resistance. screening for early indications of bt resistance developing in targeted lepidoptera is conducted in many of the regions where genetically modified cotton and corn have been commercialized. heliothis virescens (f.) (lepidoptera: noctuidae) has been selected in the laboratory to have a gene for resistance to cry1ac. we used ...200818767754
fitness costs associated with cry1ac-resistant helicoverpa zea (lepidoptera: noctuidae): a factor countering selection for resistance to bt cotton?the heritability, stability, and fitness costs in a cry1ac-resistant helicoverpa zea (boddie) (lepidoptera: noctuidae) colony (ar) were measured in the laboratory. in response to selection, heritability values for ar increased in generations 4-7 and decreased in generations 11-19. ar had significantly increased pupal mortality, a male-biased sex ratio, and lower mating success compared with the unselected parental strain (sc). ar males had significantly more mating costs compared with females. a ...200818767756
fate of bacillus thuringiensis (bt) cry3bb1 protein in a soil microcosm.transgenic crops expressing insecticidal, crystalline (cry) bacillus thuringiensis (bt) proteins were commercialized in the us in 1996. there is little information in the peer-reviewed literature on the environmental fate of the coleopteran-active bt cry3bb1 protein expressed in event mon863 corn. the exposure characterization of bt proteins is unique in that the fate of the protein in soil and in crop residue must be considered. to date, the significance of macrodecomposing organisms, such as e ...200818768202
construction of bacillus thuringiensis wild-type s76 and cry- derivatives expressing a green fluorescent protein: two potential marker organisms to study bacteria-plant interactions.collectively, the species bacillus thuringiensis, bacillus cereus, and bacillus anthracis represent microorganisms of high economic, medical, and biodefense importance. although the genetic correlation and pathogenic characteristics have been extensively dissected, the ecological properties of these three species in their natural environments remain poorly understood. thus, a tractable marker for detecting these bacteria under specific environmental and physiological conditions is a valuable too ...200818772942
the surface layer protein of bacillus thuringiensis ctc forms unique intracellular parasporal inclusion body.bacillus thuringiensis subsp. finitimus strain ctc forms round parasporal inclusion body. the inclusion body protein gene ctc has been cloned and characterized. sequence homology analysis reveals that the amino acid sequence of ctc protein shows 87% identity with the surface layer (s-layer) protein sap (genbank z36946) in b. anthracis. in this report, transmission electron microscope observation showed that ctc formed intracellular parasporal inclusion body and sheet structure of s-layer-like pr ...200818720489
[effect of cry1ca7 protein modified by site-directed mutagenesis on inhibiting spodoptera exigua hübner].to obtain the mutants with different toxicity from the wild-type crylca7.200818720836
expression of v-cath gene from hearnpv in tobacco confers an antifeedant effect against helicoverpa armigera.biotechnology solutions for insect control on crops largely depend on the expression of bacillus thuringiensis insecticidal proteins to kill pests. v-cath, a cathepsin l-like cysteine protease from baculoviruses, has been shown to play an essential role in host insect liquefaction. in this study, the v-cath gene from helicoverpa armigera single nucleopolyhedrovirus (hearnpv) was cloned into the pbi121 binary vector under the control of camv35s promoter, and was expressed in tobacco via agrobacte ...200818722486
quantitation and differentiation of bioparticles based on the measurements of light-scattering signals with a common spectrofluorometer.by simultaneously scanning both the excitation and emission monochromators of a common spectrofluorometer with same starting excitation and emission wavelength (namely, delta lambda = 0), we obtained synchronous light scattering (sls) signals that related to rayleigh and mie scatterings. it was found that the sls signals could be applied for quantitation and differentiation of model bioparticles such as saccharomyces cerevisiae, schizosaccharomyces pombe, staphylococcus aureus, escherichia coli, ...200818729400
design and construction of a synthetic bacillus thuringiensis cry4aa gene: hyperexpression in escherichia coli.cry4aa produced by bacillus thuringiensis is a dipteran-specific toxin and is, therefore, of great interest for developing a bioinsecticide to control mosquitoes. however, the expression of cry4aa in escherichia coli is relatively low, which is a major disadvantage in its development as a bioinsecticide. in this study, to establish an effective production system, a 1,914-bp modified gene (cry4aa-s1) encoding cry4aa was designed and synthesized in accordance with the g + c content and codon prefe ...200818751699
kinetics of bacillus thuringiensis var. israelensis growth on high glucose concentrations.the kinetic and general growth features of bacillus thuringiensis var. israelensis were evaluated. initial glucose concentration (s0) in fermentation media varied from 10 to 152 g/l. the results afforded to characterize four morphologically and physiologically well-defined culture phases, independent of s0 values: phase i, vegetative growth; phase ii, transition to sporulation; phase iii, sporulation; and phase iv, spores maturation and cell lysis. important process parameters were also determin ...200818712542
the stimulation of immune defence accelerates development in the red flour beetle (tribolium castaneum).the timing of the transition between life stages is of key importance for an organism. depending on the environmental conditions, maturing earlier at a smaller size or maturing later at a larger size can be advantageous for fitness. exposure to parasites and subsequent immune activation may lead to alterations in development. immune defence often comes at a cost, such as energy drain towards immune function, which is likely to delay development. on the other hand, animals may react to an anticip ...200818713243
recombinant bacillus thuringiensis strain shows high insecticidal activity against plutella xylostella and leptinotarsa decemlineata without affecting nontarget species in the field.to construct a recombinant bacillus thuringiensis (bt) strain with broad insecticidal spectrum and investigate its impact on nontarget organisms in field.200818713287
[evaluation of the triflumuron and the mixture of bacillus thuringiensis plus bacillus sphaericus for control of the immature stages of aedes aegypti and culex quinquefasciatus (diptera: culicidae) in catch basins].introduction: in cali, colombia, catch basins (streetside storm drains) are one of the main larval habitats of aedes aegypti and culex quinquefasciatus. since 1999, these mosquitoes have been controlled by the secretaría de salud municipal (secretary of municipal public health) using the larvicide triflumuron. because of high densities of these mosquitoes that remain in the city, treatment failure was suspected -possibly insecticide resistance of the target species. objectives: the efficacy of t ...200818719724
synthetic peptides as artificial receptors towards proteins from genetically modified organisms.the aim of this work was the preparation of peptide ligands with good affinity and selectivity towards proteins from genetically modified organisms, namely neomycin phosphotransferase ii (npt ii) and the endotoxin cry1a. a 12 x 12 combinatorial solid phase synthesis in aqueous medium was performed to prepare peptide libraries. from this library, two dipeptides with binding properties towards the chosen ligands (pro-lys for npt ii, k(eq) 7.59 x 10(4)m(-1); trp-gln for cry 1a, k(eq) 4.35 x 10(4)m( ...200818672356
consumption of bt maize pollen expressing cry1ab or cry3bb1 does not harm adult green lacewings, chrysoperla carnea (neuroptera: chrysopidae).adults of the common green lacewing, chrysoperla carnea (stephens) (neuroptera: chrysopidae), are prevalent pollen-consumers in maize fields. they are therefore exposed to insecticidal proteins expressed in the pollen of insect-resistant, genetically engineered maize varieties expressing cry proteins derived from bacillus thuringiensis (bt). laboratory experiments were conducted to evaluate the impact of cry3bb1 or cry1ab-expressing transgenic maize (mon 88017, event bt176) pollen on fitness par ...200818682800
carboxy-terminal half of cry1c can help vegetative insecticidal protein to form inclusion bodies in the mother cell of bacillus thuringiensis.vegetative insecticidal protein (vip) is a class of insecticidal proteins produced by some strains of bacillus thuringiensis during the vegetative stage of their growth and has toxicity against a wide spectrum of lepidopteran insects. unlike insecticidal crystal proteins, which are produced as parasporal crystal proteins within the cell during sporulation, vip is secreted into the culture medium. here, we show that vip3aa7 protein can be relocated into the mother cell of b. thuringiensis by alte ...200818685842
toxin gene pattern in bacillus cereus group strains isolated from sheep ricotta cheese. 200818685978
l-2,3-diaminopropionate: one of the building blocks for the biosynthesis of zwittermicin a in bacillus thuringiensis subsp. kurstaki strain ybt-1520.zwittermicin a (zwa) is a hybrid polyketide-non-ribosomal peptide that is thought to be biosynthesized from five proposed building blocks, including the 2,3-diaminopropionate. candidate genes for de novo biosynthesis of 2,3-diaminopropionate, zwa5a and zwa5b, have been identified in a previous study. in this research, zwa5a was interrupted and chemically synthesized 2,3-diaminopropionate was used to feed the zwa5a(-) mutant. results showed that feeding with 2,3-diaminopropionate restored the abi ...200818692050
availability of insecticidal molecules to control aedes albopictus (skuse).following the implementation of the directive 98/8/ce a few changes in the availability of insecticidal molecules to control ae. albopictus have been outlined. available products for larvicidal treatments will predominantly be based upon two growth regulators (diflubenzuron and pyriproxyfen). for the control of the adult forms there will mostly be active ingredients belonging to the pyrethroid group. importance of surveillance for the onset of tolerance or resistance phenomena.200818693569
[bacillus thuringiensis: general aspects. an approach to its use in the biological control of lepidopteran insects behaving as agricultural pests].bacillus thuringiensis is the most widely applied biological pesticide used to control insects that affect agriculture and forestry and which transmit human and animal pathogens. during the past decades b. thuringiensis has been the subject of intensive research. these efforts have yielded considerable data about the relationships between the structure, mechanism of action, and genetics of their pesticidal crystal proteins. as a result, a coherent picture of these relationships has emerged. othe ...200818705497
how to cope with insect resistance to bt toxins?transgenic bt crops producing insecticidal crystalline proteins from bacillus thuringiensis, so-called cry toxins, have proved useful in controlling insect pests. however, the future of bt crops is threatened by the evolution of insect resistance. understanding how bt toxins work and how insects become resistant will provide the basis for taking measures to counter resistance. here we review possible mechanisms of resistance and different strategies to cope with resistance, such as expression of ...200818706722
variations in the mosquito larvicidal activities of toxins from bacillus thuringiensis ssp. israelensis.comparing activities of purified toxins from bacillus thuringiensis ssp. israelensis against larvae of seven mosquito species (vectors of tropical diseases) that belong to three genera, gleaned from the literature, disclosed highly significant variations in the levels of lc(50) as well as in the hierarchy of susceptibilities. similar toxicity comparisons were performed between nine transgenic gram-negative species, four of which are cyanobacterial, expressing various combinations of cry genes, c ...200818637949
dynamics of mycotoxin and aspergillus flavus levels in aging bt and non-bt corn residues under mississippi no-till conditions.mycotoxin and aspergillus flavus levels in soil-surface corn debris left by no-till agriculture methods (stover, cobs, and cobs with grain) were determined during the december-march fallow period for near-isogenic bt and non-bt hybrid corn. by december, average mycotoxin levels in non-bt corn were many times higher in cobs with grain than in grain harvested in september (total aflatoxins, 774 vs 211 ng/g; total fumonisins, 216 vs 3.5 microg/g; cyclopiazonic acid, 4102 vs 72.2 microg/g; zearaleno ...200818642924
response of lymantria dispar l. (lepidoptera: lymantriidae) to bacillus thuringiensis subsp. kurstaki at different ingested doses and temperatures.we examined mortality and feeding inhibition response of lymantria dispar l. (lepidoptera: lymantriidae) larvae to ingested doses of bacillus thuringiensis subsp. kurstaki as a function of dose, instar and temperature. we developed generalized (logistic) linear mixed models and a mixture survival model, commonly used in medical statistics, to analyze the complex data set. we conducted bioassays of foray 48b with larvae from the njss laboratory stock, using droplet imbibing or force-feeding to en ...200818644375
[site-specific integration of heterologous gene into bacillus thuringiensis chromosome and its expression].to efficiently construct resistance gene-free bacillius thuringiensis engineered strain that can stably express heterologous gene.200818652300
[influence of cry2a sporulation-dependent promoter and molecular chaperone orf1-orf2 from bacillus thuringiensis on cry11aa protein].to analyze the coordination function of cry2a sporulation-dependent promoter and the enhanced expression of molecular chaperone orf1-orf2 to crystal protein cry11aa.200818652302
[identification, cloning and expression of the insecticidal protein genes from bacillus thuringiensis isolate rpp39].we characterized strain rpp39 isolated from the soil of sichuan, china. a type of cry2aa gene was cloned and expressed in e. coli. methods; we characterized strain rpp39 by scanning electron microscope, pcr-rflp identification and sds-page analysis. we cloned cry2aa gene by pcr clone. we constructed the recombinant plasmid pet-2aa, and transformed e.coli.bl21 (de3) to express by iptg. we determined the toxicity of expressed products to the larvae of plutella xylostella and chilo supperssalis thr ...200818652304
[apoptosis of hl-60 cells induced by crystal proteins from bacillus thuringiensis bt9875].to study the effect of bt9875 crystal protein treated with proteinase k on human cancer cells, hl-60.200818652305
enhanced synthesis and antimicrobial activities of bacteriocins produced by mexican strains of bacillus thuringiensis.recently, we reported the synthesis of five bacteriocin-like inhibitor substances (bt-blis: morricin 269, kurstacin 287, kenyacin 404, entomocin 420, and tolworthcin 524) by mexican strains of bacillus thuringiensis. here we show that, collectively, these bt-blis have a moderate to broad spectrum of antibacterial activity, being toxic to clinically significant against gram-positive and gram-negative bacteria, including common etiological agents of human diseases, such as strep throat and scarlet ...200818654760
novel roles of bacillus thuringiensis to control plant diseases.bacillus thuringiensis is well known as an effective bio-insecticidal bacterium. however, the roles of b. thuringiensis to control plant diseases are not paid great attention to. in recent years, many new functions in protecting plants from pathogen infection have been discovered. for example, acyl homoserine lactone lactonase produced by b. thuringiensis can open the lactone ring of n-acyl homoserine lactone, a signal molecule in the bacterial quorum-sensing system. this in turn, significantly ...200818654770
[adsorption and desorption of bt toxin on three kinds of minerals].this paper studied the characteristics of the adsorption and desorption of bt (bacillus thuringiensis) toxin on goethite, kaolinite, and silica. the results showed that in phosphate buffer (ph 8), the adsorption isotherms of bt toxin on the test minerals followed langmuir equation (r2 >0. 9661), and the adsorbed amounts were in the order of goethite > kaolinite > silica. the bt toxin was easily adsorbed on the minerals, and the adsorption could reach equilibrium after 1 hour. within the range of ...200818655606
a two-year field study with transgenic bacillus thuringiensis maize: effects on soil microorganisms.we evaluated the changes of some soil microbiological characteristics due to the use of transgenic maize expressing bacillus thuringiensis (bt) toxin. a two-year field experiment was conducted (2003 and 2004). two lines of transgenic bt maize that express the cry1ab protein (event 176 and mon 810) and their near-isogenic non-bt lines were used. rhizosphere and non-rhizosphere soils were collected and measurements were performed during the maize cultural cycle and immediately at pre-harvest. key ...200818656246
effects of bacillus thuringiensis toxin cry1ac and beauveria bassiana on asiatic corn borer (lepidoptera: crambidae).in this study, interactions between cry1ac, a toxic crystal protein produced by bacillus thuringiensis (berliner), and beauveria bassiana on the mortality and survival of ostrinia furnacalis was evaluated in the laboratory. the results showed that cry1ac is toxic to o. furnacalis. not only were larval growth and development delayed, but pupation, pupal weight and adult emergency also decreased when larvae were fed on artificial diet containing purified cry1ac toxin. when third instars o. furnaca ...200818656480
application of different downstream processing methods and their comparison for the large-scale preparation of bacillus thuringiensis var. israelensis after fermentation for mosquito control.bacillus thuringiensis var. israelensis, a gram positive, spore-forming bacillus, produces parasporal crystal protein during sporulation, which is toxic in the mosquito larvae gut. an efficient downstream processing method for separating the spore crystal complex (scc) from the fermented broth of b. thuringiensis var. israelensis is required to achieve maximum mosquitocidal activity. the different downstream processing methods, viz., tangential flow ultra-filtration, continuous centrifugation an ...200818657445
bacterial community structure in tree hole habitats of ochlerotatus triseriatus: influences of larval feeding.we investigated the bacterial community composition of tree holes in relation to the presence and absence of larvae of the mosquito ochlerotatus triseriatus. larvae were eliminated from a subset of natural tree holes with bacillus thuringiensis serovar israelensis, and total bacterial numbers, slow- and fast-growing colony-forming units on minimal media, and 16s rrna gene sequence data from water column and leaf material were obtained. total bacterial counts did not change significantly with tre ...200818666529
effects of single and multiple applications of mosquito insecticides on nontarget arthropods.mosquito management plans have been implemented in the united states and globally to manage mosquito vectors of west nile virus and many other diseases. however, there is public concern about ecological risks from using insecticides to manage mosquitoes. two studies were conducted during the late summers of 2004 through 2006 at benton lake national wildlife refuge near great falls, mt. the first experiment was conducted in 2004 and 2005 to assess acute impacts of mosquito adulticides (permethrin ...200818666536
laboratory evaluation of bacillus thuringiensis (vectobac wdg) against mosquito larvae, culex pipiens and culiseta longiareolata.mosquitoes are vectors of many human diseases and cause environmental nuisances. due to their large geographical distribution and abundance, culex pipiens and culiseta longiareolata represent the most important mosquito species in algeria and many countries in the world. they are generally controlled by conventional insecticides. the high reproductive ability and development of insecticide resistance of mosquito species are leading to a search for novel molecules. as so, vectobac that is based o ...200819226801
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