Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| a phylogenetic analysis of bacillus thuringiensis serovars by rflp-based ribotyping. | to determine the 23s and 5s rrna gene fingerprints in order to reveal phylogenetic relationships among bacillus thuringiensis strains. | 2001 | 11473592 |
| application of bacillus thuringiensis in poultry houses as a biological control agent against the housefly, musca domestica sorbens. | the efficiency of bacillus thuringiensis (b.t) as a microbial housefly control agent was evaluated in one of the natural maggot breeding medium, namely poultry faeces. two commercial formulations, a wettable powder and a liquid concentrate were assayed against musca domestica sorbens in synthetic fly breeding madia and in chicken faeces. the latter was found to favour maggot breeding when compared with the synthetic one. both formulations resulted in significant reduction in maggot numbers,, pup ... | 2001 | 11478452 |
| [investigation of different dosages of inserted bt genes and their insect-resistance in transgenic bt cotton]. | the plants with various dosages of inserted bt genes were developed by intercrossing among transgenic bt lines in which bt genes were inserted in different chromosomes, and commercial non-transgenic bt varieties. laboratory bioassay of insect-resistance and bt toxin protein assays with elisa were used to detect efficacy to bollworm in different cotton growing stages. as transgenic bt insect-resistant cotton, temporal difference of resistance existed in plants converging on different dosages of i ... | 2001 | 11480180 |
| screening of bacillus thuringiensis serotypes by polymerase chain reaction (pcr) for insecticidal crystal genes toxic against coffee berry borer. | using pcr,257 isolates of bacillus thuringiensis(bt) were screened for cry-type genes. of 257 isolates/strains, 60 isolates were identified as cry7/8, 10 isolates as cry3 and 36 isolates as cry 1i. one specific strain of b. thuringiensis (sumiyoshiensis; t03b 001) was investigated for the presence of cry7 and cry8 genes. genes cry7 and cry8 were first detected in this strain using family primers prior to analysis by exclusion polymerase chain reaction (e-pcr) using specific type primers. e-pcr c ... | 2001 | 11480211 |
| a droplet medium selection for cultivation of bacillus thuringiensis. | for an industrial fermentation system, design of a suitable medium for cultivation of cells is an important step. medium selection is commonly carried out with a lot of experimental works. in the present study, a simple method was proposed for medium selection in cultivation of bacillus thuringiensis for production of thuringiensin. a droplet of medium was employed to test the suitability of the medium. | 2001 | 11485443 |
| entomology. first light on genetic roots of bt resistance. | 2001 | 11486062 | |
| identification of a gene associated with bt resistance in heliothis virescens. | transgenic crops producing insecticidal toxins from bacillus thuringiensis (bt) are widely used for pest control. bt-resistant insect strains have been studied, but the molecular basis of resistance has remained elusive. here, we show that disruption of a cadherin-superfamily gene by retrotransposon-mediated insertion was linked to high levels of resistance to the bt toxin cry1ac in the cotton pest heliothis virescens. monitoring the early phases of bt resistance evolution in the field has been ... | 2001 | 11486086 |
| bt toxin resistance from loss of a putative carbohydrate-modifying enzyme. | the development of resistance is the main threat to the long-term use of toxins from bacillus thuringiensis (bt) in transgenic plants. here we report the cloning of a bt toxin resistance gene, caenorhabditis elegans bre-5, which encodes a putative beta-1,3-galactosyltransferase. lack of bre-5 in the intestine led to resistance to the bt toxin cry5b. wild-type but not bre-5 mutant animals were found to uptake toxin into their gut cells, consistent with bre-5 mutants lacking toxin-binding sites on ... | 2001 | 11486087 |
| structural implications for the transformation of the bacillus thuringiensis delta-endotoxins from water-soluble to membrane-inserted forms. | crystal structures combined with biochemical data show that the delta-endotoxins from bacillus thuringiensis are structurally poised towards large-scale, irreversible conformational changes that transform them from the soluble protein bound at the cell surface into a membrane-embedded form causing lysis of susceptible insect cells. cry delta-endotoxins are made of a helix bundle, a beta-prism and a beta-sandwich. the conformational change involves an umbrella-like opening between the helix-4,5-h ... | 2001 | 11498030 |
| construction and characterization of a recombinant bacillus thuringiensis subsp. israelensis strain that produces cry11b. | the mosquitocidal bacterium bacillus thuringiensis subsp. israelensis (bti) produces four major endotoxin proteins, cry4a, cry4b, cry11a, and cyt1a, and has toxicity in the range of many synthetic chemical insecticides. cry11b, which occurs naturally in b. thuringiensis subsp. jegathesan, is a close relative of cry11a, but is approximately 10-fold as toxic to culex quinquefasciatus. to determine whether the addition of cry11b to bti would improve its toxicity, we produced this protein in bti. hi ... | 2001 | 11500092 |
| gene knockout demonstrates that vip3a contributes to the pathogenesis of bacillus thuringiensis toward agrotis ipsilon and spodoptera exigua. | vip3a is an 89-kda protein secreted by bacillus thuringiensis during vegetative growth. to determine the importance of vip3a for the insect pathogenicity of b. thuringiensis the vip3a gene was deleted from strain hd1, yielding strain hd1deltavip3a. compared with hd1, strain hd1deltavip3a was one-fourth as toxic to agrotis ipsilon larvae and less than one-tenth as toxic to spodoptera exigua larvae. when streptomycin was included in the s. exigua diet the toxicity of hd1deltavip3a was approximatel ... | 2001 | 11500093 |
| exploring the mechanism of action of insecticidal proteins by genetic engineering methods. | 2000 | 11501380 | |
| secondary effects of the pesticide bacillus thuringiensis kurstaki on chicks of spruce grouse (dendragapus canadensis). | the objective of this study was to determine if application of the biological pesticide bacillus thuringiensis kurstaki (b.t.k.) had secondary effects on spruce grouse (dendragapus canadensis) chicks in the southern boreal forest of ontario, canada. b.t.k. kills larvae of lepidoptera that might otherwise be food. this may affect types of food ingested and influence chick growth rates by reducing the availability of a high-protein food. amount of ingested grit, which is diet-dependent, may also b ... | 2001 | 11503075 |
| control of life, death, and differentiation in cultured midgut cells of the lepidopteran, heliothis virescens. | differentiated cells in the insect midgut depend on stem cells for renewal. we have immunologically identified integrin beta1, a promotor of cell-cell adhesion that also induces signals mediating proliferation, differentiation, and apoptosis on the surfaces of cultured heliothis virescens midgut cells; clusters of immunostained integrin beta1-like material, indicative of activated integrin, were detected on aggregating midgut columnar cells. growth factor-like peptides (midgut differentiation fa ... | 2001 | 11515966 |
| [studies on transgenic tobacco plants expressing two kinds of insect resistant genes]. | a synthetic bt cry1ac gene fussed with a secretary signal coding sequences at 5' end and a modified gna gene were used to construct a plant expression vector pbsgs1m+ and this vector was transferred into tobacco (nicotiana tabacum l.) by agrobacterium-mediated transformation method. results of pcr, southern blot and slot blot analysis indicated that both the chimeric bt cry1ac and gna genes were integrated into the genomes of transformed plants. western blot analysis indicated that at least the ... | 2001 | 11517599 |
| factors contributing to peak broadening and mass accuracy in the characterization of intact spores using matrix-assisted laser desorption/ionization coupled with time-of-flight mass spectrometry. | factors contributing to peak broadening, accuracy and precision in mass assignment in the matrix-assisted laser desorption/ionization characterization of a lipopeptide desorbed from intact bacillus spores were investigated. these spores were studied as an example of a thick, topologically irregular sample, which present a more difficult target than a pure peptide or protein. the type of matrix, matrix:sample ratio, laser fluence, and localized repetitive laser irradiation were all found to affec ... | 2001 | 11523093 |
| effect of bacillus thuringiensis cry1 toxins in insect hemolymph and their neurotoxicity in brain cells of lymantria dispar. | little information is available on the systemic effects of bacillus thuringiensis toxins in the hemocoel of insects. in order to test whether b. thuringiensis-activated toxins elicit a toxic response in the hemocoel, we measured the effect of intrahemocoelic injections of several cry1 toxins on the food intake, growth, and survival of lymantria dispar (lepidoptera) and neobellieria bullata (diptera) larvae. injection of cry1c was highly toxic to the lymantria larvae and resulted in the complete ... | 2001 | 11525986 |
| susceptibility of a field-derived, bacillus thuringiensis-resistant strain of diamondback moth to in vitro-activated cry1ac toxin. | resistant and susceptible populations of the diamondback moth (plutella xylostella) were tested with crystalline, solubilized, and partially and fully activated forms of the bacillus thuringiensis cry1ac delta-endotoxin. fully activated toxin greatly reduced the resistance ratio (ratio of the 50% lethal concentration for the resistant population to that for the susceptible population) of the resistant population, suggesting that a defect in toxin activation is a major resistance mechanism. | 2001 | 11526050 |
| evaluating the environmental effects of the gm revolution. | in the us, cradle of genetically modified crops, agricultural scientists and regulators are already tackling one environmental issue, and rushing to determine the magnitude of another. | 1999 | 11529176 |
| scientists back gm crops. | 1999 | 11529179 | |
| chitinase from bacillus thuringiensis subsp. pakistani. | the chitinase gene (chia71) from bacillus thuringiensis subsp. pakistani consists of an open reading frame of 1,905 nucleotides encoding 635 amino acid residues with an estimated molecular mass of 71 kda. comparison of the deduced amino acid sequence of the mature enzyme to other microbial chitinases shows a putative catalytic domain and a region with conserved amino acids similar to that of the type iii module of fibronectin and a chitin-binding domain. by activity detection of chitinase on sds ... | 2001 | 11549008 |
| screening for novel cry genes by hybridization. | to develop an efficient and sensitive method to facilitate the search for novel cry toxins. | 2001 | 11555212 |
| effects of exposure to event 176 bacillus thuringiensis corn pollen on monarch and black swallowtail caterpillars under field conditions. | the widespread planting of corn genetically modified to produce bacillus thuringiensis endotoxin has led to speculation that pollen from these fields might adversely affect nearby nontarget lepidopterans. a previous study of bt corn engineered with monsanto event 810 failed to detect an effect of pollen exposure on the black swallowtail, papilio polyxenes, in either the field or the laboratory. here, we report results of a field study investigating the impact of exposure to pollen from a bt corn ... | 2001 | 11559837 |
| temporal and spatial overlap between monarch larvae and corn pollen. | to assess the likelihood that monarch larvae will be exposed to bacillus thuringiensis (bt) pollen, we studied milkweed and monarch densities in habitats which comprise much of the land available to breeding monarchs, e.g., cornfields, cornfield edges, other agricultural fields, and nonagricultural areas, in four regions of the monarch breeding range. we found that monarchs use milkweed in cornfields throughout their breeding season, and that per plant densities are as high or higher in agricult ... | 2001 | 11559838 |
| assessing the impact of cry1ab-expressing corn pollen on monarch butterfly larvae in field studies. | survival and growth of monarch larvae, danaus plexippus (l.), after exposure to either cry1ab-expressing pollen from three bacillus thuringiensis (bt) corn (zea mays l.) events differing in toxin expression or to the insecticide, lambda-cyhalothrin, were examined in field studies. first instars exposed to low doses ( approximately 22 grains per cm(2)) of event-176 pollen gained 18% less weight than those exposed to bt11 or mon810 pollen after a 5-day exposure period. larvae exposed to 67 pollen ... | 2001 | 11559839 |
| corn pollen deposition on milkweeds in and near cornfields. | the density of corn pollen on leaves of milkweed plants inside and outside of cornfields was measured in several studies from different localities. the purpose was to obtain a representative picture of naturally occurring pollen densities to provide a perspective for laboratory and field studies of monarch larvae feeding on milkweed leaves with bt corn pollen. pollen density was highest (average 170.6 grains per cm(2)) inside the cornfield and was progressively lower from the field edge outward, ... | 2001 | 11559840 |
| monarch larvae sensitivity to bacillus thuringiensis- purified proteins and pollen. | laboratory tests were conducted to establish the relative toxicity of bacillus thuringiensis (bt) toxins and pollen from bt corn to monarch larvae. toxins tested included cry1ab, cry1ac, cry9c, and cry1f. three methods were used: (i) purified toxins incorporated into artificial diet, (ii) pollen collected from bt corn hybrids applied directly to milkweed leaf discs, and (iii) bt pollen contaminated with corn tassel material applied directly to milkweed leaf discs. bioassays of purified bt toxins ... | 2001 | 11559841 |
| impact of bt corn pollen on monarch butterfly populations: a risk assessment. | a collaborative research effort by scientists in several states and in canada has produced information to develop a formal risk assessment of the impact of bt corn on monarch butterfly (danaus plexippus) populations. information was sought on the acute toxic effects of bt corn pollen and the degree to which monarch larvae would be exposed to toxic amounts of bt pollen on its host plant, the common milkweed, asclepias syriaca, found in and around cornfields. expression of cry proteins, the active ... | 2001 | 11559842 |
| baseline susceptibility to bacterial insecticides in populations of culex pipiens complex (diptera: culicidae) from california and from the mediterranean island of cyprus. | bacterial insecticides play an increasingly important role in mosquito control. to establish guidelines for detecting resistance at an early stage, information on natural variation in susceptibility of insect populations to these insecticides is needed. between 1990 and 1993, the susceptibility of culex pipiens l. complex to bacillus thuringiensis subsp. israelensis de barjac and/or bacillus sphaericus neide was determined in 31 collections from california. these collections were undertaken befo ... | 2001 | 11561853 |
| overwintering cost associated with resistance to transgenic cotton in the pink bollworm (lepidoptera: gelechiidae). | fitness costs associated with resistance to transgenic crops producing toxins from bacillus thuringiensis (bt) may have important effects on the evolution of resistance. we investigated overwintering costs in pink bollworm, pectinophora gosypiella (saunders), strains with different degrees of resistance to bt cotton. frequency of resistant individuals in a strain was not associated with induction of diapause or emergence from diapause in early winter. emergence from diapause in the spring was 71 ... | 2001 | 11561855 |
| evaluation of a new tablet formulation based on bacillus thuringiensis sorovar. israelensis for larvicidal control of aedes aegypti. | the effect of sunlight on the efficacy and persistence of an experimental tablet formulation based on bacillus thuringiensis sorovar. israelensis (c4p1) was evaluated against aedes aegypti larvae under simulated field conditions. the initial mortality ranged from 93 to 100%, and the residual activity (> or = 70% mortality) recorded in containers exposed to sunlight or shade were, respectively, 13-35 days and 40-54 days. the results suggest that c4p1 can provide long-term larvicidal effect and op ... | 2001 | 11562715 |
| [production of stable bacillus thuringiensis suspensions in an electromagnetic apparatus]. | the experiment demonstrated the podibility of obtaining stable suspensions of b. subtilis, a microorganism used as an experimental model, in an electromagnetic apparatus with a bilateral inductor. the optimum conditions of obtaining such suspensions were chosen, these conditions excluding the inactivation of the bacteria used as a model in the course of the process. suspensions containing 75% of culture fluid were shown to have the highest stability during prolonged storage. suspensions on the b ... | 2001 | 11569272 |
| differential effects of ph on the pore-forming properties of bacillus thuringiensis insecticidal crystal toxins. | the effect of ph on the pore-forming ability of two bacillus thuringiensis toxins, cry1ac and cry1c, was examined with midgut brush border membrane vesicles isolated from the tobacco hornworm, manduca sexta, and a light-scattering assay. in the presence of cry1ac, membrane permeability remained high over the entire ph range tested (6.5 to 10.5) for kcl and tetramethylammonium chloride, but was much lower at ph 6.5 than at higher phs for potassium gluconate, sucrose, and raffinose. on the other h ... | 2001 | 11571147 |
| variation in susceptibility to bacillus thuringiensis toxins among unselected strains of plutella xylostella. | so far, the only insect that has evolved resistance in the field to bacillus thuringiensis toxins is the diamondback moth (plutella xylostella). documentation and analysis of resistant strains rely on comparisons with laboratory strains that have not been exposed to b. thuringiensis toxins. previously published reports show considerable variation among laboratories in responses of unselected laboratory strains to b. thuringiensis toxins. because different laboratories have used different unselec ... | 2001 | 11571163 |
| fluorescent amplified fragment length polymorphism analysis of norwegian bacillus cereus and bacillus thuringiensis soil isolates. | we examined 154 norwegian b. cereus and b. thuringiensis soil isolates (collected from five different locations), 8 b. cereus and 2 b. thuringiensis reference strains, and 2 bacillus anthracis strains by using fluorescent amplified fragment length polymorphism (aflp). we employed a novel fragment identification approach based on a hierarchical agglomerative clustering routine that identifies fragments in an automated fashion. no method is free of error, and we identified the major sources so tha ... | 2001 | 11571195 |
| isolation of bacillus thuringiensis from intertidal brackish sediments in mangroves. | intertidal brackish sediments in mangroves were examined for isolation of bacillus thuringiensis strains with novel toxicity spectra. a total of 18 b. thuringiensis isolates were recovered from eight sediment samples (36.4%) out of 22 samples tested. the frequency of b. thuringiensis was 1.3% among the colonies of bacillus cereus/b. thuringiensis group. while five isolates were allocated to the four h serogroups, the majority of the isolates were serologically untypable or untestable. two isolat ... | 2001 | 11572461 |
| the monarch butterfly controversy: scientific interpretations of a phenomenon. | the future development and use of agricultural biotechnology has been challenged by two preliminary studies indicating potential risk to monarch butterfly populations by pollen from corn engineered to express proteins from bacillus thuringiensis. likewise, these studies have also challenged the way in which science should be performed, published in scientific journals and communicated to the public at large. herein, we provide a history of the monarch controversy to date. we believe a retrospect ... | 2001 | 11576433 |
| development and commercial use of bollgard cotton in the usa--early promises versus today's reality. | bollgard cotton is the trademark given to a number of varieties of cotton bio-engineered to produce an insecticidal protein from bacillus thuringiensis (bt). when produced by the modified cotton plants, this protein controls certain lepidopterous cotton insect pests. commercially available since 1996, these cotton varieties are purchased under a license agreement in which the growers pay a fee and agree to abide by the terms, which include a 1-year license to use the technology and agreement to ... | 2001 | 11576434 |
| comparison of the omega-transaminases from different microorganisms and application to production of chiral amines. | microorganisms that are capable of (s)-enantioselective transamination of chiral amines were isolated from soil samples by selective enrichment using (s)-alpha-methyl-benzylamine ((s)-alpha-mba) as a sole nitrogen source. among them, klebsiella pneumoniae js2f, bacillus thuringiensis js64, and vibrio fluvialis js17 showed good omega-transaminase (omega-ta) activities and the properties of the omega-tas were investigated. the induction level of the enzyme was strongly dependent on the nitrogen so ... | 2001 | 11577718 |
| distribution of s-layers on the surface of bacillus cereus strains: phylogenetic origin and ecological pressure. | bacillus anthracis, bacillus cereus and bacillus thuringiensis have been described as members of the bacillus cereus group but are, in fact, one species. b. anthracis is a mammal pathogen, b. thuringiensis an entomopathogen and b. cereus a ubiquitous soil bacterium and an occasional human pathogen. in two clinical isolates of b. cereus, in some b. thuringiensis strains and in b. anthracis, an s-layer has been described. we investigated how the s-layer is distributed in b. cereus, and whether phy ... | 2001 | 11578310 |
| breaking the code of resistance. | 2001 | 11581654 | |
| [genetic analysis of cry1ab gene of bt rice]. | improved histochemical staining for gus activity, pcr and western blotting were used to analyse the progeny population of bt rice crossed with conventional rice varieties. a total of 392 plants expressing bt toxin protein were found in 394 gus positive plants. the result demonstrated that cry1ab gene closely inherited and expressed with reporter gene gus. gus assays indicated that cry1ab gene of bt rice inherits as a single dorminant gene. southern hybridization confirmed cry1ab gene can inherit ... | 2001 | 11582744 |
| evaluation of biological and chemical insecticide mixture against aedes aegypti larvae and adults by thermal fogging in singapore. | to improve the operational efficiency of dengue vector control in singapore, larvicide and adulticide were applied together by thermal fog generator (agrofog af40). the mixture consisted of bacillus thuringiensis var. israelensis (vectobac 12 as) as biological larvicide at 1.5 l/ha and pirimiphos-methyl (actellic 50 ec) as adulticide at 100 g ai/ha, diluted 10-fold with water. aerosol of this mixture was evaluated against the mosquito aedes aegypti (l.) (diptera: culicidae) in bioassays using ca ... | 2001 | 11583451 |
| processing of cry1ab delta-endotoxin from bacillus thuringiensis by manduca sexta and spodoptera frugiperda midgut proteases: role in protoxin activation and toxin inactivation. | activation of cry protoxins is carried out by midgut proteases. this process is important for toxicity and in some cases for specificity. commercial proteases have been used for in vitro protoxin activation. in the case of cry1a protoxins, trypsin digestion generates a toxic fragment of 60-65 kda. here, we have analyzed the in vitro and in vivo activation of cry1ab. we found differences in the processing of cry1ab protoxin by manduca sexta and spodoptera frugiperda midgut proteases as compared t ... | 2001 | 11583928 |
| allergenicity of cry9c: an unresolved issue. | 2001 | 11590402 | |
| broad-spectrum resistance to bacillus thuringiensis toxins in heliothis virescens. | evolution of pest resistance to insecticidal proteins produced by bacillus thuringiensis (bt) would decrease our ability to control agricultural pests with genetically engineered crops designed to express genes coding for these proteins. previous genetic and biochemical analyses of insect strains with resistance to bt toxins indicate that (i) resistance is restricted to single groups of related bt toxins, (ii) decreased toxin sensitivity is associated with changes in bt-toxin binding to sites in ... | 1992 | 11607319 |
| bt breakthrough reveals good and bad news for pest resistance. | 2001 | 11642460 | |
| sample preparation for beta-exotoxin determination in bacillus thuringiensis cultures by reversed-phase high-performance liquid chromatography. | beta-exotoxin is a nucleotide analogue produced by the entomopathogenic bacterium bacillus thuringiensis. we have defined two new hplc procedures for quantification of this exotoxin in culture supernatants of b. thuringiensis grown in poor or rich medium. the sample is prepared either by precipitation in solvent or by solid-phase extraction. solvent precipitation is achieved treating the sample with acetone and acetonitrile. solid-phase extraction is performed with a c18 and an anion-exchange ca ... | 2001 | 11673902 |
| bt or not bt: is that the question? | 2001 | 11675483 | |
| regulation of the packaging of bacillus thuringiensis delta-endotoxins into inclusions. | during sporulation, many bacillus thuringiensis subspecies synthesize several related delta-endotoxins which are packaged into bipyramidal intracellular inclusions. these inclusions are solubilized in the alkaline, reducing conditions of the midguts of susceptible insect larvae and are converted by proteolysis to active toxins. the toxins insert into the membranes of cells lining the midgut and form cation-selective channels, which results in lethality. there are three delta-endotoxins, cry1ab3, ... | 2001 | 11679322 |
| high genetic variability for resistance to bacillus thuringiensis toxins in a single population of diamondback moth. | the long-term benefit of insecticidal products based on cry toxins, either in sprays or as transgenic crops, is threatened by the development of resistance by target pests. the models used to predict evolution of resistance to cry toxins most often are monogenic models in which two alleles are used. moreover, the high-dose/refuge strategy recommended for implementation with transgenic crops relies on the assumption that the resistance allele is recessive. using selection experiments, we demonstr ... | 2001 | 11679324 |
| bacillus thuringiensis delta-endotoxin cry1 hybrid proteins with increased activity against the colorado potato beetle. | cry1 delta-endotoxins of bacillus thuringiensis are generally active against lepidopteran insects, but cry1ba and cry1ia have additional, though low, levels of activity against coleopterans such as the colorado potato beetle. here we report the construction of cry1ba/cry1ia hybrid toxins which have increased activities against this insect species. | 2001 | 11679364 |
| predicting spring moth emergence in the pink bollworm (lepidoptera: gelechiidae): implications for managing resistance to transgenic cotton. | cultural control methods have been central in the southwestern united states for reducing pink bollworm, pectinophora gossypiella (saunders), damage to cotton. nevertheless, it is not clear at present how such methods could be integrated within the novel pest management framework allowed by introduction of cotton producing a toxin from bacillus thuringiensis (bt) for pink bollworm control. using statewide pheromone trapping and climatic data in conjunction with deterministic simulation models, w ... | 2001 | 11681660 |
| larval mortality and development of pseudoplusia includens (lepidoptera: noctuidae) reared on a transgenic bacillus thuringiensis-cotton cultivar expressing cryiac insecticidal protein. | the effects of a transgenic bacillus thuringiensis (bt)-cotton cultivar (dpl 32) on three instars of the soybean looper, pseudoplusia includens (walker), were determined in laboratory studies. first, third, and fifth instars were fed field collected bt-cotton leaves for 1, 2, four and 7 d or until pupation, and then transferred to artificial diet. mortality during the larval stage increased linearly in response to an increase in the length of feeding time on bt-cotton by first and third instars. ... | 2001 | 11681665 |
| biotic and abiotic factors limiting efficacy of bt corn in indirectly reducing mycotoxin levels in commercial fields. | incidence of insect damage, and association of insect damage with mycotoxigenic corn ear molds and mycotoxins was examined in commercial fields of bt and non-bt hybrids of different backgrounds in illinois in 1998 and 1999. nearly 50% helicoverpa zea (boddie) infestation sometimes occurred in bt hybrids that express high levels of the protein in silks and kernels. damage by european corn borer, ostrinia nubilalis hübner, was uncommon, even in non-bt ears. levels of total fumonisins were generall ... | 2001 | 11681667 |
| new tachinidae (diptera) host records of eastern north american forest canopy lepidoptera: baseline data in a bacillus thuriengiensis variety kurstaki nontarget study. | macrolepidopteran caterpillars collected in 1995 and 1996 in the monongahela national forest, pocahontas county, wv, and the george washington national forest, augusta county, va, yielded 60 previously unreported tachinid host associations. most associations were between native species, but the introduced polyphagous tachinid compsilura concinnata (meigen) produced eight new associations with native hosts. the tachinids collected were slightly broader in their host preferences than associated br ... | 2001 | 11681675 |
| variation in the susceptibility of the forest tent caterpillar (lepidoptera: lasiocampidae) to bacillus thuringiensis variety kurstaki hd-1: effect of the host plant. | host-mediated effect on the efficacy of bacillus thuringiensis berliner against larvae of the forest tent caterpillar. malacosoma disstria hübner, was investigated under controlled conditions. host plants used in this study were quaking aspen, populus tremuloides michx., a preferred host, and sugar maple, acer saccharum marsh., a secondary host. larvae were reared in the laboratory on leaves of these hosts, and upon reaching the third, fourth, and fifth instar, they were fed leaves treated with ... | 2001 | 11681676 |
| management of early-instar japanese beetle (coleoptera: searabaeidae) in field-grown nursery crops. | numerous field studies were conducted in commercial nurseries in tennessee from 1996 through 1999 to evaluate chemical and biological treatments, application timing and rates, and method of application for control of early instars of japanese beetle, popillia japonica newman. insecticide treatments included bifenthrin, bendiocarb, chlorpyrifos, carbaryl, fipronil, halofenozide, imidacloprid, permethrin, tefluthrin, thiamethoxam, and trichlorfon. biological treatments included entomopathogenic ne ... | 2001 | 11681678 |
| effects of bt cotton and crylac toxin on survival and development of pink bollworm (lepidoptera: gelechiidae). | we evaluated the effects of bacillus thuringiensis (bt) toxin crylac on survival and development of a susceptible strain and laboratory-selected resistant strains of pink bollworm, pectinophora gossypiella (saunders). for susceptible and resistant strains tested on artificial diet, increases in crylac concentration reduced developmental rate and pupal weight. in greenhouse tests, survival of resistant larvae on transgenic cotton that produces crylac (bt cotton) was 46% relative to their survival ... | 2001 | 11681689 |
| life history traits of helicoverpa zea (lepidoptera: noctuidae) on non-bt and bt transgenic corn hybrids in eastern north carolina. | transgenic varieties of field corn that express the crylab b. thuringiensis (bt) toxin in ear tissue present the potential of reducing ear feeding by the corn earworm, helicoverpa zea (lepidoptera: noctuidae), and for reducing the size of populations of the insect infesting other host crops. life history parameters of h. zea feeding on ears of conventional and bt field corn varieties were measured in field plots in eastern north carolina in 1997 and 1998. transformation events investigated were ... | 2001 | 11681693 |
| aminopeptidase-n from the helicoverpa armigera (hubner) brush border membrane vesicles as a receptor of bacillus thuringiensis crylac delta-endotoxin. | brush border membrane vesicles (bbmvs) were prepared from the 2nd instar larvae of helicoverpa armigera. binding of the activated cry1ac of bacillus thuringiensis (bt) toxin was shown by immunoblot. a 120-kda protein was identified as a receptor for the cry1ac type delta-endotoxin. the aminopeptidase-n activity of bbmvs was measured as the hydrolysis of l-leucine p-nitroanilide. the specific activity was 35 units/mg protein. the bbmv preparation also showed low level of alkaline phosphatase acti ... | 2001 | 11683359 |
| isolation and characterization of a bacillus thuringiensis ssp. kurstaki strain toxic to spodoptera exigua and culex pipiens. | a strain of bacillus thuringiensis with dual toxicity was isolated from korean soil samples and named k2. k2 was determined as ssp. kurstaki (h3a3b3c) by serological test and produced bipyramidal-shaped parasporal inclusions. the plasmid and protein profiles of b. thuringiensis k2 were different from those of the reference strain, ssp. kurstaki hd-1. to verify gene type of b. thuringiensis k2, pcr analysis with specific cry gene primers was performed. the result showed that b. thuringiensis k2 h ... | 2001 | 11683364 |
| identification of entomopathogenic bacillus isolated from simulium (diptera, simuliidae) larvae and adults. | entomopathogenic bacteria isolated from simulium larvae and adults from breeding sites in the states of são paulo and rio de janeiro, brazil, were identified as 18 strains of bacillus thuringiensis and one of b. sphaericus. most of these strains were serotyped according to their flagellar antigens. however, nine of the b. thuringiensis samples, could not be serotyped and were designated as "autoagglutinating"; they were also shown to be toxic in preliminary tests against aedes aegypti larvae. ad ... | 2001 | 11685272 |
| molecular cloning of a new crystal protein gene cry1af1 of bacillus thuringiensis nt0423 from korean sericultural farms. | a new cry1ab-type gene encoding the 130 kda protein of bacillus thuringiensis nt0423 bipyramidal crystals was cloned, sequenced, and expressed in a crystal-negative b. thuringiensis host. hybridization experiments revealed that the crystal protein gene is located on a 44 mda plasmid of b. thuringiensis nt0423. a strong positive signal detected on the 6.6 kb hindiii fragment from b. thuringiensis nt0423 plasmid dna was cloned and sequenced. the cry1ab-type gene, designated cry1af1, consisted of o ... | 2001 | 11685507 |
| bacteriological larvicides of dipteran disease vectors. | the apparent success in vector control observed between 1950 and 1970 was followed by worldwide resistance to organosynthetic insecticides wherever they were used intensively. insect resistance to one or more categories of insecticides has limited the effectiveness of these compounds, and their non-selective mode of action adversely affects non-target organisms. this scenario highlights the need for selective agents in integrated vector control programs. this article gives an overview of the mai ... | 2001 | 11685898 |
| ion channels induced in planar lipid bilayers by the bacillus thuringiensis toxin cry1aa in the presence of gypsy moth (lymantria dispar) brush border membrane. | the apical brush border membrane, the main target site of bacillus thuringiensis toxins, was isolated from gypsy moth (lymantria dispar) larval midguts and fused to artificial planar lipid bilayer membranes. under asymmetrical n-methyl-d-glucamine-hcl conditions (450 mm cis/150 mm trans, ph 9.0), which significantly reduce endogenous channel activity, trypsin-activated cry1aa, a b. thuringiensis insecticidal protein active against the gypsy moth in vivo, induced a large increase in bilayer membr ... | 2001 | 11687877 |
| effect of accessory proteins p19 and p20 on cytolytic activity of cyt1aa from bacillus thuringiensis subsp. israelensis in escherichia coli. | the gene coding for the accessory protein p19 of bacillus thuringiensis subsp. israelensis was expressed in escherichia coli and its product was characterized. to investigate its putative role in delta-endotoxin crystallization as a p20-like polypeptide, each of the two encoding genes, p20 and p19, was cloned for inducible expression coordinatively with cyt1aa. the latter is known to kill its transgenic host. p20 but not p19 stabilized cyt1aa and protected the host cells from its lethal effect. ... | 2001 | 11688801 |
| expression and crystallization of an n-terminally activated form of the bacillus thuringiensis cry1ca toxin. | when the active form of the bacillus thuringiensis delta-endotoxin cry1ca was expressed in e. coli severe growth retardation was observed. the absence of a short peptide from the n-terminus of the protoxin was responsible for this effect. the introduction of a mutation at an amino acid previously reported as being involved in the initial stages of pore formation within the natural insect target partially abolished the growth retardation effect. we suggest that removal of the n-terminal peptide i ... | 2001 | 11688803 |
| suitability of anabaena pcc7120 expressing mosquitocidal toxin genes from bacillus thuringiensis subsp. israelensis for biotechnological application. | we present evidence that anabaena pcc7120 (a.7120) strains expressing mosquitocidal toxin genes from bacillus thuringiensis subsp. israelensis (bti) have a strong potential for biotechnological application. characterization of two 4-year-old recombinant a.7120 clones constructed previously in our laboratory [clone 7 and clone 11, each carrying three bti genes (cry4aa, cry11aa, and p20)] revealed three facts. first, the bti genes were stable in a.7120 even in the absence of antibiotic selection w ... | 2001 | 11693914 |
| recombinant baculoviruses for insect control. | baculoviruses are double-stranded dna viruses which are highly selective for several insect groups. they are valuable natural control agents, but their utility in many agricultural applications has been limited by their slow speed of kill and narrow host specificity. baculoviruses have been genetically modified to express foreign genes under powerful promoters in order to accelerate their speed of kill. in our and other laboratories, the expression of genes coding for insect juvenile hormone est ... | 2001 | 11695193 |
| notes from the underground. communication and control in the rhizosphere. | 2001 | 11706157 | |
| structure of cry3a delta-endotoxin within phospholipid membranes. | interaction of delta-endotoxin and its proteolytic fragments with phospholipid vesicles was studied using electron microscopy, scanning microcalorimetry, and limited proteolysis. it was shown that native protein destroys liposomes. the removal of 4 n-terminal alpha-helices and the extreme 56 c-terminal amino acid residues did not affect this ability. the results obtained by limited proteolysis of delta-endotoxin bound to lipid vesicles show essential conformational changes in three or four n-ter ... | 2001 | 11714267 |
| crystallization of the bacillus thuringiensis toxin cry1ac and its complex with the receptor ligand n-acetyl-d-galactosamine. | cry1ac from bacillus thuringiensis ssp. kurstaki hd-73 is a pore-forming protein specifically toxic to lepidopteran insect larvae. it binds to the cell-surface receptor aminopeptidase n in manduca sexta midgut via the sugar n-acetyl-d-galactosamine (galnac). by using 1,3-diaminopropane (dap) as the buffer throughout protoxin activation and chromatography on q-sepharose at ph 10.3, trypsin-activated cry1ac has been purified in a monomeric state, which was crucial to obtaining single crystals of c ... | 2001 | 11717524 |
| unfolding affects insect cell permeabilization by bacillus thuringiensis cry1c toxin. | bacillus thuringiensis cry toxins are efficient, environment-friendly biological insecticides. their molecular mode of action on target insect cells remains largely unknown. the aim of this study was to investigate the relation between the conformational state of the cry1c toxin and its ionophoric activity on live sf9 cells of spodoptera frugiperda, a target insect for this protein. potassium ion movement induced by cry1c across the cell membrane was measured with a fluorescent assay developed p ... | 2001 | 11718667 |
| carbohydrate analyses of manduca sexta aminopeptidase n, co-purifying neutral lipids and their functional interactions with bacillus thuringiensis cry1ac toxin. | bacillus thuringiensis cry1ac insecticidal toxin binds specifically to 120kda aminopeptidase n (apn) (ec 3.4.11.2) in the epithelial brush border membrane of manduca sexta midguts. the isolated 120-kda apn is a member of a functional cry1 toxin receptor complex (febs lett. 412 (1997) 270). the 120-kda form is glycosyl-phosphatidylinositol (gpi) anchored and converted to a 115-kda form upon membrane solubilization. the 115-kda apn also binds cry1a toxins and cry1ac binding is inhibited by n-acety ... | 2001 | 11719073 |
| butterfly effects. | concerns about the potential toxicity of pollen from genetically modified maize on neighbouring butterflies prompted urgent studies, reports nigel williams. | 2001 | 11719229 |
| binding specificity of bacillus thuringiensis cry1aa for purified, native bombyx mori aminopeptidase n and cadherin-like receptors. | to better understand the molecular interactions of bt toxins with non-target insects, we have examined the real-time binding specificity and affinity of cry1 toxins to native silkworm (bombyx mori) midgut receptors. previous studies on b. mori receptors utilized brush border membrane vesicles or purifed receptors in blot-type assays. | 2001 | 11722800 |
| effects of the 20-kilodalton helper protein on cry1ac production and spore formation in bacillus thuringiensis. | bacillus thuringiensis produces large amounts of various pesticidal proteins during the stationary phase. in order to achieve a high yield and form crystals, some pesticidal proteins require the presence of other proteins. helper protein p20 is required for efficient production of both the cyt1a and cry11a crystal proteins in b. thuringiensis subsp. israelensis. although full-length cry1 protoxins are usually independent in terms of expression and crystallization in b. thuringiensis, in this stu ... | 2001 | 11722880 |
| the alpha-helix 4 residue, asn135, is involved in the oligomerization of cry1ac1 and cry1ab5 bacillus thuringiensis toxins. | the insecticidal cry toxins produced by the bacterium bacillus thuringiensis are comprised of three structural domains. domain i, a seven-helix bundle, is thought to penetrate the insect epithelial cell plasma membrane through a hairpin composed of alpha-helices 4 and 5, followed by the oligomerization of four hairpin monomers. the alpha-helix 4 has been proposed to line the lumen of the pore, whereas some residues in alpha-helix 5 have been shown to be responsible for oligomerization. mutation ... | 2001 | 11722927 |
| shared binding sites in lepidoptera for bacillus thuringiensis cry1ja and cry1a toxins. | bacillus thuringiensis toxins act by binding to specific target sites in the insect midgut epithelial membrane. the best-known mechanism of resistance to b. thuringiensis toxins is reduced binding to target sites. because alteration of a binding site shared by several toxins may cause resistance to all of them, knowledge of which toxins share binding sites is useful for predicting cross-resistance. conversely, cross-resistance among toxins suggests that the toxins share a binding site. at least ... | 2001 | 11722929 |
| toxicity analysis of n- and c-terminus-deleted vegetative insecticidal protein from bacillus thuringiensis. | a vegetative insecticidal protein (vip)-encoding gene from a local isolate of bacillus thuringiensis has been cloned, sequenced, and expressed in escherichia coli. the expressed protein shows insecticidal activity against several lepidopteran pests but is ineffective against agrotis ipsilon. comparison of the amino acid sequence with those of reported vips revealed a few differences. analysis of insecticidal activity with n- and c-terminus deletion mutants suggests a differential mode of action ... | 2001 | 11722946 |
| cyt1aa from bacillus thuringiensis subsp. israelensis is toxic to the diamondback moth, plutella xylostella, and synergizes the activity of cry1ac towards a resistant strain. | the bacillus thuringiensis subsp. israelensis cytolytic protein cyt1aa was found to be toxic to an insecticide-susceptible laboratory population of plutella xylostella. cry1ac-resistant populations of p. xylostella showed various degrees of resistance to cyt1aa. cyt1aa/cry1ac mixtures showed a marked level of synergism in the cry1ac-resistant populations. | 2001 | 11722947 |
| transformation of enterobacter gergoviae isolated from pink bollworm (lepidoptera: gelechiidae) gut with bacillus thuringiensis toxin. | production of molecules with toxic activity by genetically transformed symbiotic bacteria of pest insects may serve as a powerful approach to biological control. the symbiont, enterobacter gergoviae, isolated from the gut of the pink bollworm (pbw), has been transformed to express cyt1a, a cytolytic protein toxin lethal to mosquito and black fly larvae, as a model system. these transgenic bacteria might be used to spread genes encoding insecticidal proteins to populations of agricultural insects ... | 2002 | 11727033 |
| a uv tolerant mutant of bacillus thuringiensis subsp. kurstaki producing melanin. | a uv-resistant mutant (bt-m) of bacillus thuringiensis subsp. kurstaki, producing a dark brown pigment, identified as melanin, was studied. bt-m had higher larvicidity against heliothis armigera than its parent. survival of bt-m spores and their insecticidal activity to irradiation at 254 nm and 366 nm were higher than those of the parent. the only toxic polypeptide produced by bt-m was cry1ac (130 kda); it lost cry1aa, cry2aa, and cry2ab. | 2002 | 11727037 |
| biochemistry and genetics of insect resistance to bacillus thuringiensis. | bacillus thuringiensis (bt) is a valuable source of insecticidal proteins for use in conventional sprayable formulations and in transgenic crops, and it is the most promising alternative to synthetic insecticides. however, evolution of resistance in insect populations is a serious threat to this technology. so far, only one insect species has evolved significant levels of resistance in the field, but laboratory selection experiments have shown the high potential of other species to evolve resist ... | 2002 | 11729083 |
| economic, ecological, food safety, and social consequences of the deployment of bt transgenic plants. | transgenic plants expressing insecticidal proteins from the bacterium, bacillus thuringiensis (bt), are revolutionizing agriculture. bt, which had limited use as a foliar insecticide, has become a major insecticide because genes that produce bt toxins have been engineered into major crops grown on 11.4 million ha worldwide in 2000. based on the data collected to date, generally these crops have shown positive economic benefits to growers and reduced the use of other insecticides. the potential e ... | 2002 | 11729093 |
| illegal bt cotton in india haunts regulators. | 2001 | 11731762 | |
| transgenic dna introgressed into traditional maize landraces in oaxaca, mexico. | concerns have been raised about the potential effects of transgenic introductions on the genetic diversity of crop landraces and wild relatives in areas of crop origin and diversification, as this diversity is considered essential for global food security. direct effects on non-target species, and the possibility of unintentionally transferring traits of ecological relevance onto landraces and wild relatives have also been sources of concern. the degree of genetic connectivity between industrial ... | 2001 | 11734853 |
| bacillus anthracis pxo1 plasmid sequence conservation among closely related bacterial species. | the complete sequencing and annotation of the 181.7-kb bacillus anthracis virulence plasmid pxo1 predicted 143 genes but could only assign putative functions to 45. hybridization assays, pcr amplification, and dna sequencing were used to determine whether pxo1 open reading frame (orf) sequences were present in other bacilli and more distantly related bacterial genera. eighteen bacillus species isolates and four other bacterial species were tested for the presence of 106 pxo1 orfs. three orfs wer ... | 2002 | 11741853 |
| drosophila toll is activated by gram-positive bacteria through a circulating peptidoglycan recognition protein. | microbial infection activates two distinct intracellular signalling cascades in the immune-responsive fat body of drosophila. gram-positive bacteria and fungi predominantly induce the toll signalling pathway, whereas gram-negative bacteria activate the imd pathway. loss-of-function mutants in either pathway reduce the resistance to corresponding infections. genetic screens have identified a range of genes involved in these intracellular signalling cascades, but how they are activated by microbia ... | 2001 | 11742401 |
| detection of specific bacillus anthracis spore biomarkers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. | analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (maldi-tofms) was applied for the characterization of bacillus anthracis spore biomarkers. b. anthracis spores were extracted under a simple procedure, followed by linear mode analysis, using sinapinic acid as the matrix. several markers with a mass range of 4-7 kda were detected in three b. anthracis strains: vollum, sterne and v770-np1-r. similar spectra were also obtained for spore extracts of two members ... | 2001 | 11746875 |
| transgenes in mexican maize. | 2002 | 11753352 | |
| determination of cry9c protein in corn-based foods by enzyme-linked immunosorbent assay: interlaboratory study. | the performance of a commercially available enzyme-linked immunosorbent assay kit (enviro-logix) was assessed for the determination of cry9c protein, which is produced by the genetically modified corn starlink, in 8 types of corn-based foods (starch, refined oil, soft tortillas, tortilla chips, corn flakes, corn puffs, corn muffins, and corn bread) in an interlaboratory study involving 7 laboratories in the united states. the assay kit is a double antibody sandwich and is based on the specific i ... | 2001 | 11767159 |
| engineered genes contaminate corn's birthplace. | 2001 | 11770775 | |
| [insecticidal activity of bacillus thuringiensis cells]. | the influence of sixteen different nutrient media on the entomopathogenic activity of three bacillus thuringiensis strains was studied. the medium composition based on potato, yeast extract, and molasses was optimized. b. thuringiensis no 1 grown on the media no 7 and 9 displayed the highest entomopathogenic activity (94.3 and 90.6%, respectively). | 2001 | 11771324 |
| mutagenic analysis of a conserved region of domain iii in the cry1ac toxin of bacillus thuringiensis. | we used site-directed mutagenesis to probe the function of four alternating arginines located at amino acid positions 525, 527, 529, and 531 in a highly conserved region of domain iii in the cry1ac toxin of bacillus thuringiensis. we created 10 mutants: eight single mutants, with each arginine replaced by either glycine (g) or aspartic acid (d), and two double mutants (r525g/r527g and r529g/r531g). in lawn assays of the 10 mutants with a cultured choristoneura fumiferana insect cell line (cf1), ... | 2002 | 11772627 |
| cloning and characterization of the crystal protein-encoding gene of bacillus thuringiensis subsp. yunnanensis. | molecular cloning and characterization of a novel cry gene, cry32aa, of bacillus thuringiensis subsp. yunnanensis was carried out. the cry32aa protein was predicted to have a molecular mass of 139.2 kda and was found to have an unusual 42-amino-acid-long tail at the c terminus. the cry32aa gene was localized on the 103-mda plasmid of the organism. bioassays showed no toxicity against several moths and mosquitoes. however, it exhibited weak toxicity against larvae of the diamondback moth, plutell ... | 2002 | 11772653 |
| study on the effect of bacillus thuringiensis (b.t. serotype h-14) and its toxins against cephalopina titillator (clark), the egyptian camel myiasis producing dipterous fly. | bacillus t. israelensis (b.t. serotype h-14) and its toxins have a marked lethal effect on both the eggs and the newly moulted 3rd stage larvae of cephalopina titillator. the bacillus was less effective than bacillus and its toxins on both the eggs and larvae. on the other hand, the larvae were more affected by both bacillus and bacillus and its toxins than the eggs. prolonged exposure time showed more lethal effect. | 2001 | 11775107 |
| effects of various insecticides on the development of the egg parasitoid trichogramma dendrolimi (hymenoptera: trichogrammatidae). | the toxicity of six insecticides, acephate, methomyl, ethofenprox, cartap, chlorfluazuron, and bacillus thuringiensis (bt) was tested on different developmental stages of the egg parasitoid, trichogramma dendrolimi (matsumura). each of the insecticides tested showed different degrees of toxicity to the parasitoid, ethofenprox showed the highest toxicity and cartap showed relatively higher toxicity compared with the other insecticides. the development of the parasitoids treated with these two ins ... | 2001 | 11777034 |
| interactions between nosema pyrausta (microsporidia: nosematidae) and bacillus thuringiensis subsp. kurstaki in the european corn borer (lepidoptera: pyralidae). | larval susceptibility to bacillus thuringiensis was determined for nosema pyrausta-infected and uninfected european corn borers, ostrinia nubilalis (hübner), in bioassays using a commercial formulation of b. thuringiensis subsp. kurstaki, dipel es, incorporated into diet. lc50 values for n. pyrausta-infected larvae were significantly lower (p<0.0001) than for uninfected larvae and declined with increasing levels of infection. lc50 values for a 15-d bioassay using field-colony first instars were ... | 2001 | 11777037 |