Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
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| epigenetic transcriptional silencing and 5-azacytidine-mediated reactivation of a complex transgene in rice. | despite a growing number of reports indicating non-mendelian inheritance of transgene expression in monocots, no detailed description of the structure and stability of the transgene exists for transformants generated by direct dna-transfer techniques, making the cause for these observations difficult to determine. in this paper we describe the complex organization of btt cryiiia and bar transgenes in rice (oryza sativa l.) that displayed aberrant segregation in r1 progeny. silencing rather than ... | 1997 | 9342860 |
| rare codons are not sufficient to destabilize a reporter gene transcript in tobacco. | in plants, as in other eukaryotes, most synonymous codons of the genetic-code are not used with equal frequency, but instead some codons are preferred, whereas others are rare. circumstantial evidence led to the suggestion that rare codons have a negative influence on mrna stability. to address this question experimentally, rare codons encoded by a bacillus thuringiensis (b.t.) toxin gene (cryia(c)) or a synthetic sequence were introduced into a phytohemagglutinin (pha) reporter gene. in neither ... | 1997 | 9349262 |
| improvement of bacillus sphaericus toxicity against dipteran larvae by integration, via homologous recombination, of the cry11a toxin gene from bacillus thuringiensis subsp. israelensis. | integrative plasmids were constructed to enable integration of foreign dna into the chromosome of bacillus sphaericus 2297 by in vivo recombination. integration of the apha3 kanamycin resistance gene by a two-step procedure demonstrated that this strategy was applicable with antibiotic resistance selection. hybridization experiments evidenced two copies of the operon encoding the binary toxin from b. sphaericus in the recipient strain. the bacillus thuringiensis subsp. israelensis cry11aal gene ... | 1997 | 9361428 |
| contribution of the 65-kilodalton protein encoded by the cloned gene cry19a to the mosquitocidal activity of bacillus thuringiensis subsp. jegathesan. | two new crystal protein genes, cry19a and orf2, isolated from bacillus thuringiensis subsp. jegathesan were cloned and characterized. the cry19a gene encodes a 74.7-kda protein, and the orf2 gene encodes a 60-kda protein. cry19a contains the five conserved blocks present in most b. thuringiensis delta-endotoxins. the orf2 amino acid sequence is similar to that of the carboxy terminus of cry4 proteins. the cry 19a gene was expressed independently or in combination with orf2 in a crystal-negative ... | 1997 | 9361431 |
| the bacillus thuringiensis cry1ac toxin-induced permeability change in manduca sexta midgut brush border membrane vesicles proceeds by more than one mechanism. | aminopeptidase n purified from whole manduca sexta midgut binds the cry1ac insecticidal toxin from bacillus thuringiensis and this binding is inhibited by n-acetylgalactosamine (galnac). we have examined the membrane permeabilising activity of the cry1ac toxin using brush border membrane vesicles (bbmv) prepared from the anterior (a-bbmv) and posterior (p-bbmv) subregions of the m. sexta midgut. a toxin mixing assay demonstrated a faster rate of toxin activity on p-bbmv than on a-bbmv. in the pr ... | 1997 | 9365280 |
| abundance and distribution of bacillus thuringiensis in the agricultural soil of bangladesh | bacillus thuringiensis is distributed ubiquitously in the agricultural soil of bangladesh. simple correlation and regression analyses showed that the soil sand percentage and the available copper levels had significant negative and positive contributions, respectively, to the abundance and distribution of b. thuringiensis in the agricultural soil. among the isolates, only 2.5% of strains showed larvicidal activity against the mosquito culex quinquefasciatus. the larvicidal potency ld50 varied fr ... | 1997 | 9367730 |
| role of 2,6-dideoxy-2,6-diaminoglucose in activation of a eukaryotic phospholipase c by aminoglycoside antibiotics. | recent emergence of microbial resistance to aminoglycoside antibiotics, and the documented cytotoxicity associated with their use, calls for sustained efforts at understanding the effects of the compounds on eukaryotic cells. using a glycosyl phosphatidylinositol (gpi)-phospholipase c (gpi-plc) from the protozoan parasite trypanosoma brucei, we demonstrate that a eukaryotic plc can be activated 6-fold by aminoglycosides. neomycin b protected gpi-plc from a reduction in activity at ph 6.5, and in ... | 1997 | 9368017 |
| characterization of the vibrio cholerae el tor lipase operon lipab and a protease gene downstream of the hly region. | we have cloned and sequenced a region encoding a lipase operon and a putative, previously uncharacterized metalloprotease of vibrio cholerae o1. these lie downstream of hlya and hlyb, which encode the el tor hemolysin and methyl-accepting chemotactic factor, respectively. previous reports identified the hlyc gene downstream of hlyab, encoding an 18.3-kda protein. however, we now show that this open reading frame (orf) encodes a 33-kda protein, and since the amino acid sequence is highly homologo ... | 1997 | 9371455 |
| global variation in the genetic and biochemical basis of diamondback moth resistance to bacillus thuringiensis. | insecticidal proteins from the soil bacterium bacillus thuringiensis (bt) are becoming a cornerstone of ecologically sound pest management. however, if pests quickly adapt, the benefits of environmentally benign bt toxins in sprays and genetically engineered crops will be short-lived. the diamondback moth (plutella xylostella) is the first insect to evolve resistance to bt in open-field populations. here we report that populations from hawaii and pennsylvania share a genetic locus at which a rec ... | 1997 | 9371752 |
| cyta enables cryiv endotoxins of bacillus thuringiensis to overcome high levels of cryiv resistance in the mosquito, culex quinquefasciatus. | cry proteins produced by bacillus thuringiensis are selective biodegradable insecticides used increasingly in bacterial insecticides and transgenic plants as alternatives to synthetic chemical insecticides. however, the potential for development of resistance and cross-resistance in target insect populations to cry proteins used alone or in combination threatens the more widespread use of this novel pest control technology. here we show that high levels of resistance to cryiv proteins in larvae ... | 1997 | 9380670 |
| [distribution of natural parasites--fungi and microsporidia--in a population of malarial mosquito larva (diptera: culicidae) before and after infection by the entomopathogenic bacteria bacillus thuringiensis israelensis]. | the distribution specificity of fungi and microsporidies in natural population of anopheles messeae fall. and a. beklemishevi stegny et kab. and those which survived after treatment them by bacillus thuringiensis israelensis (bti) were observed. parasitic fungus nonselectively affected individuals of both species and all inversion genotypes of a. messeae. microsporidia parathelohania messeae affected males and it has not species and genotypic specificity. the 4-th instar larvae of both species i ... | 1997 | 9395427 |
| bacillus thuringiensis cytolytic toxin associates specifically with its synthetic helices a and c in the membrane bound state. implications for the assembly of oligomeric transmembrane pores. | the cyta toxin exerts its activity by the formation of pores within target cell membranes. however, the exact mechanism of pore formation and the structural elements that are involved in the toxic activity are yet to be determined. recently, the structure of the highly similar cytb toxin was solved (li et al., 1996), and a beta-barrel was suggested as a possible structure of the pores. due to the similarity between the toxins, the existence and positioning of alpha-helices and beta-sheets in cyt ... | 1997 | 9398283 |
| short-chain phosphatidylinositol conformation and its relevance to phosphatidylinositol-specific phospholipase c. | the solution conformation of chiral diheptanoylphosphatidylinositol (d- and l-inositol isomers) has been characterized by nmr spectroscopy. a positive noe between the inositol c2 proton and an sn-3 glycerol ch2 proton has been observed in the d- but not in the l-inositol isomer of diheptanoylphosphatidylinositol (pi). computer modeling using quanta constrained by this noe and ring coupling constants suggests that the inositol ring is nearly parallel to the chain packing direction, leaving the ph ... | 1997 | 9398326 |
| occurrence of a common binding site in mamestra brassicae, phthorimaea operculella, and spodoptera exigua for the insecticidal crystal proteins cryia from bacillus thuringiensis. | specific binding to midgut membrane proteins is required for the toxicity of insecticidal crystal proteins (icp) from bacillus thuringiensis. a direct relationship between toxicity and binding has been proposed. it has been hypothesized that sharing of a single receptor by more than one icp could lead to the occurrence of multiple resistance in the event of an alteration in the common receptor. binding of cryia(a), cryia(b) and cryia(c), three structurally related icps, has been studied in phtho ... | 1997 | 9404010 |
| molecular cloning and characterization of a novel mosquitocidal protein gene from bacillus thuringiensis subsp. fukuokaensis. | a novel mosquitocidal protein gene, cry20aa, was cloned from bacillus thuringiensis subsp. fukuokaensis (h-3a: 3d: 3e). the gene product, cry20aa, was naturally truncated and had a molecular mass of 86,138 da. the cry20aa protein possessed five conserved sequence blocks, as do most other insecticidal cry toxins. however, an amino acid comparison of cry20aa with other mosquitocidal toxins, including cry4a, cry4b, cry10a, cry11a, and cry11b, demonstrated that cry20aa was quite different from other ... | 1997 | 9406385 |
| extended screening by pcr for seven cry-group genes from field-collected strains of bacillus thuringiensis. | an extended multiplex pcr method was established to rapidly identify and classify bacillus thuringiensis strains containing cry (crystal protein) genes toxic to species of lepidoptera, coleoptera, and diptera. the technique enriches current strategies and simplifies the initial stages of large-scale screening of cry genes by pinpointing isolates that contain specific genes or unique combinations of interest with potential insecticidal activities, thus facilitating subsequent toxicity assays. fiv ... | 1997 | 9406409 |
| mosquito larvicidal activity of transgenic anabaena strain pcc 7120 expressing combinations of genes from bacillus thuringiensis subsp. israelensis. | various combinations of the genes cryiva (cry4a), cryivd (cry11a), and p20 from bacillus thuringiensis subsp. israelensis were introduced into the nitrogen-fixing cyanobacterium anabaena sp. strain pcc 7120 by means of escherichia coli-anabaena shuttle vector prl488p and were expressed under control of two tandem strong promoters, a cyanobacterial promoter (ppsba) and an e. coli t7 promoter (pa1). two of the clones carrying cryiva plus cryivd, one with p20 and one without p20, displayed toxicity ... | 1997 | 9406420 |
| southern analysis of bt-r1, the manduca sexta gene encoding the receptor for the cry1ab toxin of bacillus thuringiensis. | various subspecies of the gram-positive bacterium bacillus thuringiensis are known to produce a wide array of insecticidal crystal proteins (icps) upon sporulation. these icps act primarily on the brush border of midgut epithelial cells of susceptible larvae. recently, a protein of 210 kda, isolated from the midgut of manduca sexta, has been demonstrated to bind the cry1ab toxin produced by b. thuringiensis subsp, berliner and is therefore postulated to be involved in mediating the toxicity of c ... | 1997 | 9413435 |
| intracellular proteases in sporulated bacillus thuringiensis subsp. tenebrionis: detection and analysis by gelatin zymography. | three intracellular proteases were identified from sporulated cultures of bacillus thuringiensis subsp tenebrionis by fractionation with ammonium sulfate. in this study, we detected protease activities at m(r) 92 kda, 81 kda and 69 kda employing gelatin zymography. the major proteolytic activity was due to the 81 kda protease, which was identified as a metalloprotease being inhibited by both 1,10-phenanthroline and ethylenediamine tetraacetic acid. the proteases showed maximal azocasein hydrolyt ... | 1997 | 9415802 |
| insect resistance to bt revisited. | 1997 | 9415873 | |
| firms sleuth out transgenic foods. | 1997 | 9415876 | |
| rhône-poulenc rounds up dekalb and monsanto. | 1997 | 9415877 | |
| bacillus thuringiensis: from biodiversity to biotechnology. | bacillus thuringiensis is a gram-positive bacterium, widely used in agriculture as a biological pesticide. the biocidal activity mainly resides in a parasporal protein inclusion body, or crystal. the inclusion is composed of one or more types of delta-endotoxins (cry and cyt proteins). cry proteins are selectively toxic to different species from several invertebrate phyla: arthropods (mainly insects), nematodes, flatworms and protozoa. the mode of action of the insecticidal proteins is still a m ... | 1997 | 9418060 |
| a genetic system that reports transient activation of genes in bacillus. | site-specific recombination is a powerful tool for precise excision of dna fragments. we used this characteristic to construct a genetic system to report the transient activation of a promoter by promoting the stable acquisition of an antibiotic resistance marker by the bacterium. the system is composed of two compatible plasmid derivatives from gram-positive bacteria. one of the plasmids allows the insertion of promoters upstream from tnpi, which encodes the site-specific recombinase of tn4430. ... | 1997 | 9427554 |
| monitoring the insecticidal toxins from bacillus thuringiensis in soil with flow cytometry. | the accumulation and persistance in soil and other natural habitats of the insecticidal toxins from bacillus thuringiensis may result in environmental hazards, such as toxicity to nontarget species and the selection of toxin-resistant target species. we describe the use of flow cytometry as a method for detecting and tracking the fate of these insecticidal toxins in soil that does not require their extraction and purification. the toxins from b. thuringiensis subspp. tenebrionis and kurstaki wer ... | 1997 | 9436309 |
| identification and partial characterization of tochicin, a bacteriocin offduced by bacillus thuringiensis subsp tochigiensis. | bacillus thuringiensis subsp tochigiensis hd868 was identified as a bacteriocin producer which exhibited a bactericidal effect against closely related species. this bacteriocin designated as tochicin, was partially purified by 75% ammonium sulfate precipitation followed by subsequent dialysis. this partially purified tochicin showed a narrow antibacterial spectrum of activity against most of 20 typical b. thuringiensis strains and a strain of b. cereus, but not against other bacteria and yeasts ... | 1997 | 9439004 |
| larvicidal efficacy of bacillus sphaericus h-5a, 5b and b. thuringiensis var. israelensis h-14 against malaria vectors in bhabar area, district naini tal, u.p. | 1997 | 9699425 | |
| study on the flying height of aedes caspius and culex pipiens females in the po delta area, italy. | we have studied the vertical distribution of culicidae in the "ancona di bellocchio" protected area (regional park of the po delta, emilia-romagna, italy) by means of nonilluminated cdc traps baited with co2. traps were placed at heights of 1.5, 3, 4, and 5 m from the ground in open areas and at 1.5, 3, 4, 5, 6, and 7 m in wooded areas. we calculated the average flying height of the species caught, i.e., in order of decreasing flying height, culex pipiens linnaeus s.l., culex modestus ficalbi, c ... | 1997 | 9474562 |
| performance of ulv formulations (pesguard 102/vectobac 12as) against three mosquito species. | adulticidal and larvicidal performances of a water-based pyrethroid microemulsion pesguard ps 102 (ai d-allethrin and d-phenothrin, both at 5.0% w/w) and vectobac 12as, an aqua-suspension bacillus thuringiensis israelensis (b.t.i.) formulation (ai 1,200 itu/mg) were assessed against mosquitoes aedes aegypti, aedes albopictus, and culex quinquefasciatus using a leco ulv fog generator model 1600 and a scorpion 20 ulv airblast sprayer. laboratory-cultured mosquito adults and larvae were used for ef ... | 1997 | 9474567 |
| the mossie-buster: a hose-driven insecticide delivery tool for the control of container-breeding mosquitoes. | a novel insecticide delivery tool, the mossie-buster, was recently developed to control larval populations from urban breeding sites in townsville, australia. this functional and user-friendly control device directly targets the main breeding sites of aedes aegypti (l.) with a focused delivery of insecticides. the mossie-buster comprises a commercially available device and attachments that mix an insecticide solution into the flow of water emitted from a hose. attached to the device is a trigger ... | 1997 | 9474568 |
| a novel insecticidal serotype of clostridium bifermentans. | a novel clostridium bifermentans strain toxic to mosquito larvae on ingestion was isolated from a soil sample collected from secondary forest floor. this strain was designated as serovar paraiba (c. b. paraiba) according to its specific h antigen. clostridium bifermentans paraiba is most toxic to anopheles maculatus theobald larvae (lc50 = 0.038 mg/liter), whereas toxicity to aedes aegypti (linn.) (lc50 = 0.74 mg/liter) and culex quinquefasciatus say (lc50 = 0.11 mg/liter) larvae was 20 and 3 ti ... | 1997 | 9474569 |
| field evaluation of vectobac g, vectobac 12as and bactimos wp against the dengue vector aedes albopictus in tires. | the efficacy of three formulations of bacillus thuringiensis var. israelensis was studied against aedes albopictus in discarded tires. the formulations were: vectobac g (corn cob formulation), vectobac 12as (aqueous suspension), and bactimos wp (wettable powder formulation). both vectobac g and vectobac 12as were effective for 24 hr with more than 80% mortality. both vectobac formulations were significantly more effective than bactimos wp for 24 hr after treatment (p < 0.0005). a week after trea ... | 1997 | 9491362 |
| insect chitinases: molecular biology and potential use as biopesticides. | chitin, an insoluble structural polysaccharide that occurs in the exoskeletal and gut linings of insects, is a metabolic target of selective pest control agents. one potential biopesticide is the insect molting enzyme, chitinase, which degrades chitin to low molecular weight, soluble and insoluble oligosaccharides. for several years, our laboratories have been characterizing this enzyme and its gene. most recently, we have been developing chitinase for use as a biopesticide to control insect and ... | 1997 | 9501415 |
| plasmid patterns of bacillus thuringiensis strains and isolates. | bacillus thuringiensis produces crystal proteins which are toxic to several orders of economically important insects and other invertebrates. the genes encoding these toxins reside mainly on plasmids. this report consists of a comparative analysis of the plasmid content of a number of b. thuringiensis strains and isolates which may facilitate the search for novel toxin genes and other important products of this organism. | 1997 | 9556387 |
| effect of insecticidal crystal proteins of bacillus thuringiensis var. israelensis on the enzymes of rat intestinal brush border membrane vesicles. | in vivo treatment of intestinal brush border membrane vesicles with solubilized insecticidal crystal proteins (icp) from the two strains of b. thuringiensis var. israelensis (vcrc b17 and vcrc mb24) caused no adverse effect on gamma glutamyl transpeptidase, na+k+atpase, sucrase and lactase enzymes. but, exposure of membrane vesicles to solubilized icp's in vitro, lead to significant reduction in the activity of na+k+atpase, sucrase and lactase enzymes. | 1997 | 9567748 |
| cdnas for a chymotrypsinogen-like protein from two strains of plodia interpunctella. | gut proteinases are involved in the solubilization and activation of insecticidal toxins produced by bacillus thuringiensis and may also be involved in resistance development. approximately threefold lower chymotrypsin-like enzyme activity was observed in a bt(entomocidus)-resistant strain of the indianmeal moth, plodia interpunctella, than that in the bt-susceptible strain. because chymotrypsin-like proteinases are involved in bt protoxin activation in p. interpunctella, we compared cdna sequen ... | 1997 | 9569643 |
| characterization of a cry2a gene cloned from an isolate of bacillus thuringiensis serovar sotto. | a cry2a-type gene, designated as cry2(skw), was cloned from bacillus thuringiensis serovar sotto skw01-10.2-06, and some unique features of the gene were revealed. the cry2(skw) gene encoded a polypeptide of 635 residues with a predicted molecular mass of 71,137 da. cry2(skw) had 95.4% identity with cry2aa in amino acid sequence and was two residues longer than cry2aa. two open reading frames (orfs), designated as orf1 and orf2, were present upstream of the cry2(skw) and showed high homology wit ... | 1997 | 9175551 |
| investigation of mosquito-specific larvicidal activity of a soil isolate of bacillus thuringiensis serovar canadensis. | the lc50 value of alkali-solubilized parasporal inclusion proteins of a diptera-specific strain, belonging to bacillus thuringiensis serovar canadensis, was 2.4 microg/ml for larvae of the mosquito, aedes aegypti. a significant loss in larvicidal activity occurred when solubilized inclusion proteins were treated with a. aegypti larval gut extract, silkworm (bombyx mori) larval gut juice, and the proteinase k. approximately 90% of the larvicidal activity was destroyed upon treatment with protease ... | 1997 | 9175558 |
| growth inhibition, morphological change, and ectoenzyme release of llc-pk1 cells by phosphatidylinositol-specific phospholipase c of bacillus thuringiensis. | phosphatidylinositol-specific phospholipase c (pi-plc) from bacillus thuringiensis added to a culture of llc-pk1 cells inhibited cell growth by 40%. in contrast with normal cells, the cells cultured in the presence of pi-plc showed needle-like appendages which seemed to have been formed due to portions of the cell remaining adhered to the culture dish as the cell shrank. when llc-pk1 cells were treated with pi-plc, significant amounts of alkaline phosphatase and alkaline phosphodiesterase i were ... | 1997 | 9178552 |
| analysis of the large aqueous pores produced by a bacillus thuringiensis protein insecticide in manduca sexta midgut-brush-border-membrane vesicles. | an osmotic swelling assay utilising carboxyfluorescein self-quenching to measure intravesicular volume changes was adapted to investigate permeability changes induced by the bacillus thuringiensis cry1ac delta-endotoxin in manduca sexta midgut-brush-border-membrane vesicles (bbmv). this assay provides a more quantitative analysis of cry-toxin-induced bbmv permeability changes, extending our previously published protocol which employed a light-scattering signal to monitor delta-endotoxin activity ... | 1997 | 9183021 |
| phosphatidylinositol-specific phospholipase c: kinetic and stereochemical evidence for an interaction between arginine-69 and the phosphate group of phosphatidylinositol. | a new substrate analogue, (2r)-1,2-dipalmitoyloxypropanethiophospho-1-d-myo-inositol (dpspi), has been used in a new, continuous assay for phosphatidylinositol-specific phospholipase c (pi-plc). dpspi is superior to other substrate analogs that have been used for assaying pi-plc since it is synthesized as a pure diastereomer and maintains both acyl chains of the natural substrate, dipalmitoylphosphatidylinositol (dppi). the assay that has been developed using this new analogue has allowed us to ... | 1997 | 9184143 |
| one gene in diamondback moth confers resistance to four bacillus thuringiensis toxins. | environmentally benign insecticides derived from the soil bacterium bacillus thuringiensis (bt) are the most widely used biopesticides, but their success will be short-lived if pests quickly adapt to them. the risk of evolution of resistance by pests has increased, because transgenic crops producing insecticidal proteins from bt are being grown commercially. efforts to delay resistance with two or more bt toxins assume that independent mutations are required to counter each toxin. moreover, it g ... | 1997 | 9050831 |
| a 16s rrna gene oligonucleotide probe for identification of bacillus thuringiensis isolates from sheep fleece. | larvae of the australian sheep blowfly lucilia cuprina are susceptible to some strains of bacillus thuringiensis, including some isolates from sheep fleeces from south australia and western australia. larvicidal strains of b. thuringiensis include var. thuringiensis, tolworthi, darmstadiensis, morrisoni, and toumanoffi. as part of an ecological study, a large number of b. thuringiensis fleece isolates from untreated sheep and sheep previously treated with larvicidal b. thuringiensis were screene ... | 1997 | 9028924 |
| chair of gmo panel resigns over maize. | 1997 | 9034175 | |
| transgenic plants: an emerging approach to pest control. | insect pests are a major cause of damage to the world's commercially important agricultural crops. current strategies aimed at reducing crop losses rely primarily on chemical pesticides. alternatively transgenic crops with intrinsic pest resistance offer a promising alternative and continue to be developed. the first generation of insect-resistant transgenic plants are based on insecticidal proteins from bacillus thuringiensis (bt). a second generation of insect-resistant plants under developmen ... | 1997 | 9035137 |
| distribution and characterization of bacillus thuringiensis in the environment of the olive in greece. | the distribution of bacillus thuringiensis in greece, was studied and the presence of this organism was found in 11.2% of the samples collected. the characterization of the different isolates was based on their whole-cell protein profiles. some of the isolates form quite unusual parasporal inclusions. | 1997 | 9037671 |
| identification of a gene for cyt1a-like hemolysin from bacillus thuringiensis subsp. medellin and expression in a crystal-negative b. thuringiensis strain. | a gene designated cyt1ab1, encoding a 27,490-da protein, was isolated from bacillus thuringiensis subsp. medellin (h30 serotype) by using an oligonucleotide probe corresponding to the cyt1aa1 gene. the sequence of the cyt1ab1 protein, as deduced from the sequence of the cyt1ab1 gene, was 86% identical to that of the cyt1aa1 protein and 32% identical to that of the cyt2aa1 protein from b. thuringiensis subsp. kyushuensis. the cyt1ab1 gene was flanked upstream by a p21 gene, in the same orientatio ... | 1997 | 9023925 |
| the bacillus thuringiensis vegetative insecticidal protein vip3a lyses midgut epithelium cells of susceptible insects. | the vip3a protein is a member of a newly discovered class of vegetative insecticidal proteins with activity against a broad spectrum of lepidopteran insects. histopathological observations indicate that vip3a ingestion by susceptible insects such as the black cutworm (agrotis ipsilon) and fall armyworm (spodoptera frugiperda) causes gut paralysis at concentrations as low as 4 ng/cm2 of diet and complete lysis of gut epithelium cells resulting in larval death at concentrations above 40 ng/cm2. th ... | 1997 | 9023933 |
| a recombinase-mediated system for elimination of antibiotic resistance gene markers from genetically engineered bacillus thuringiensis strains. | a tnpi-mediated site-specific recombination system to construct genetically modified bacillus thuringiensis strains was developed. recombinant b. thuringiensis strains from which antibiotic resistance genes can be selectively eliminated were obtained in vivo with a new vector based on the specific resolution site of transposon tn4430. for example, a cryic gene, whose product is active against spodoptera littoralis, was introduced into b. thuringiensis kto harboring a cryia(c) gene active against ... | 1997 | 9023958 |
| cloning of novel enterotoxin genes from bacillus cereus and bacillus thuringiensis. | a novel enterotoxin gene was cloned from bacillus cereus fm1, and its nucleotide sequence was determined. previously, a 45-kda protein causing characteristic enterotoxin symptoms in higher animals had been isolated (k. shinagawa, p. 181-193, in a. e. pohland et al., ed., microbial toxins in foods and feeds, 1990) from the same b. cereus strain, but no report of cloning of the enterotoxin gene has been published. in the present study, a specific antibody to the purified enterotoxin was produced a ... | 1997 | 9055420 |
| identification of a second transcriptional start site for the insecticidal protein gene cryiva of bacillus thuringiensis subsp. israelensis. | expression of cryiva, one of the insecticidal protein genes of b. thuringiensis subsp. israelensis, is regulated at the transcriptional level. the cryiva gene is specifically transcribed during the stationary phase of this bacterium. as shown in our previous report [yoshisue et al. (1993a)], the transcription from the -364 position of the cryiva gene is conducted by the major promoter p1 that is functional during middle stages of the stationary phase of b. thuringiensis. in the present study, we ... | 1997 | 9055823 |
| a new tissue technique for evaluating effects of bacillus thuringiensis toxins on insect midgut epithelium. | epithelial tissue wholemounts were produced after enzymatic removal of basal lamina and connective tissue from midguts of trichoplusia ni larvae. wholemounts were nourished in artificial hemolymph and tissue viability was assessed for up to 24 hr using the vital dyes trypan blue, acridine orange (ao), propidium iodide (pi), and 4', 6-diamidino-2-phenylindole (dapi). peritrophic membrane synthesis and modification of bacillus thuringiensis cry1ac protoxin to active toxin confirmed some normal epi ... | 1997 | 9056459 |
| release of ectoenzymes from small intestine brush border membranes of mice by phospholipases. | this study investigated ectoenzyme release from small intestine brush border membranes (duodenum and jejunum, preparation a; ileum, preparation b) of mice by the action of phosphatidylinositol-specific phospholipase c or glycosyl-phosphatidylinositol-specific phospholipase d. most of the alkaline phosphatase was solubilized from preparation a, but about 60% was released from preparation b. as for alkaline phosphodiesterase i activity, 15 and 10% were released from preparations a and b, respectiv ... | 1997 | 9058973 |
| toxicity of an isolate of bacillus thuringiensis subspecies darmstadiensis to adults of the mexican fruit fly (diptera: (diptera:tephritidae) in the laboratory. | centrifugation pellets obtained from an isolate of bacillus thuringiensis subspecies darmstadiensis (guat 1) cultured from a guatemalan soil sample were found to be toxic to anastrepha ludens (loew) adults in the laboratory. we developed a bioassay diet that consisted of a mixture of the bacterium, a protein source, and sugar. a ph of 4.1 of the mixture was needed to obtain maximum adult mortality. one meal of the diet, which lasted from 30 s to 4 min, was enough to cause > 70% mortality of both ... | 1997 | 9071889 |
| biological control studies of soft and hard ticks in egypt. i. the effect of bacillus thuringiensis varieties on soft and hard ticks (ixodidae). | the potential activity of three varieties of bacillus thuringiensis (kurstaki, israeliensis, and thuringiensis) against the soft tick argas persicus and the hard tick hyalomma dromedarii was investigated. soft ticks succumbed within a period ranging from 36 h to 5 days and hard ticks died at between 48 h and 10 days posttreatment, depending on the dose. concentrations lethal to 50% of tick populations (lc50 values) indicated that dipel 2x (b. thuringiensis var. kurstaki) was the most potent, fol ... | 1997 | 9089714 |
| expression of a bacillus thuringiensis cryia(c) gene in transgenic peanut plants and its efficacy against lesser cornstalk borer. | the invasion of peanut (arachis hypogaea l.) pods and seeds by aflatoxin-forming species of aspergillus is linked to injury by the lesser cornstalk borer and frequently causes a severe reduction in crop quality. the lesser cornstalk borer is susceptible to the lepidopteran-active bacillus thuringiensis insecticidal crystal protein. we have introduced a codon-modified bacillus thuringiensis cryia(c) gene into peanut using microprojectile bombardment. the toxin-coding region of a bt cryia(c) gene ... | 1997 | 9090064 |
| nitric oxide and tnf-alpha production by murine peritoneal macrophages activated with a novel 20-kda protein isolated from bacillus thuringiensis var. thuringiensis parasporal bodies. | the effects of a novel 20-kda protein isolated from bacillus thuringiensis var. thuringiensis (btp20) parasporal bodies on macrophage activation were investigated and compared with the activity of lps. murine resident or ifn-gamma-primed peritoneal macrophages (50 u/ml of ifn-gamma for 16 h) were treated with 50 microg/ml of btp20, alone or in combination with lps (1 to 100 ng/ml). btp20 was not toxic for macrophages as determined by the mtt (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium ... | 1997 | 9103445 |
| large-scale production and characterization of bacillus thuringiensis subsp. tenebrionis insecticidal protein from escherichia coli. | bacillus thuringiensis subsp. tenebrionis insecticidal protein was produced in recombinant escherichia coli and purified to near homogeneity to provide quantities of protein for safety-assessment studies associated with the registration of transgenic potato plants. the 68-kda protein is produced naturally by bacillus thuringiensis subsp. tenebrionis by translation initiation at an internal initiation site in the native dna sequence. the gene sequence specific for this truncated protein was expre ... | 1997 | 9114517 |
| a novel delta-endotoxin gene cryim from bacillus thuringiensis ssp. wuhanensis. | a new cryi-related sequence designated cryim was cloned using an immunoscreening technique from ssp. wuhanensis of bacillus thuringiensis (bt), previously reported to produce multiple cry proteins [chestukhina et al. (1994) can. j. microbiol. 240, 1026-1034]. analysis of the cryim nucleotide sequence revealed an orf, btii-type promoter-like sequence, peculiar for such genes, a translation initiation element and a putative transcription terminator. nevertheless, its product was not previously fou ... | 1997 | 9119053 |
| transgenic elite indica rice plants expressing cryiac delta-endotoxin of bacillus thuringiensis are resistant against yellow stem borer (scirpophaga incertulas). | generation of insect-resistant, transgenic crop plants by expression of the insecticidal crystal protein (icp) gene of bacillus thuringiensis (bt) is a standard crop improvement approach. in such cases, adequate expression of the most appropriate icp against the target insect pest of the crop species is desirable. it is also considered advantageous to generate bt-transgenics with multiple toxin systems to control rapid development of pest resistance to the icp. larvae of yellow stem borer (ysb), ... | 1997 | 9122157 |
| phylogenetic relationships of bacillus thuringiensis delta-endotoxin family proteins and their functional domains. | 1997 | 9139891 | |
| distribution of the insertion element is240 among bacillus thuringiensis strains. | the presence of is240 was investigated in 69 bacillus thuringiensis (bt) strains including strains from serotype h1 to h45 and additional strains with known dipteran larvae toxicity. restriction digests of total dna and pcr products obtained with a single 16-bases primer corresponding to the is240 inverted repeated sequence were hybridized with the is240a element. the results indicate that 67% of the bt strains tested, including all known mosquitocidal strains, possess at least one is240-related ... | 1997 | 9142741 |
| effect of bacillus thuringiensis toxins on the membrane potential of lepidopteran insect midgut cells. | to test whether the ability of bacillus thuringiensis toxins to form pores in the midgut epithelial cell membrane of susceptible insects correlates with their in vivo toxicity, we measured the effects of different toxins on the electrical potential of the apical membrane of freshly isolated midguts from gypsy moth (lymantria dispar) and silkworm (bombyx mori) larvae. in the absence of toxin, the membrane potential, measured with a conventional glass microelectrode, was stable for up to 30 min. i ... | 1997 | 9143102 |
| sequence analysis and characterization of pom1, a small cryptic plasmid from butyrivibrio fibrisolvens, and its use in construction of a new family of cloning vectors for butyrivibrios. | as a preliminary step in the development of vector systems, we have isolated and begun to characterize small, cryptic plasmids from several strains of the rumen bacterium butyrivibrio fibrisolvens. we present here the complete nucleotide sequence of butyrivibrio plasmid pom1, which was isolated from b. fibrisolvens bu49. while it is very similar in size to the previously characterized butyrivibrio plasmids prjf1 and prjf2, pom1 exhibits a restriction pattern which is quite distinct. analysis of ... | 1997 | 9143105 |
| reversal of low-level resistance to bacillus sphaericus in a field population of the southern house mosquito (diptera:culicidae) from an urban area of recife, brazil. | a larval population of culex quinquefasciatus say from an urban area (coque) of recife, brazil, submitted to selection with bacillus sphaericus neide for a 26-mo trial, was 10 times less susceptible to b. sphaericus and slightly more susceptible to bacillus thuringiensis israelensis, compared with untreated populations. the low-level resistance to b. sphaericus was unstable in the absence of selection pressure. the lc50 of b. sphaericus to the coque population declined gradually and attained a s ... | 1997 | 9145030 |
| parameters influencing potency of bacillus thuringiensis var. israelensis products. | bioassays of products based on bacillus thuringiensis var. israelensis have been carried out according to standard protocols. these analyses revealed that the slopes of the log-probit transformed concentration mortality curves of various products were different from that of the international standards (ips82 for b. thuringiensis israelensis). for statistical reasons, this invalidates the tests. products giving various slopes of the concentration mortality curves will obtain different potencies w ... | 1997 | 9145032 |
| use of bactimos briquets (b.t.i. formulation) combined with the backswimmer notonecta irrorata (hemiptera:notonectidae) for control of mosquito larvae. | the efficacies of bacillus thuringiensis var. israelensis (bactimos briquets) and the backswimmer notonecta irrorata were evaluated both individually and in combination to control mosquito larvae in plastic containers in monterrey, mexico. the combined strategy proved to be the most effective one. | 1997 | 9152881 |
| cytolytic activity of bacillus thuringiensis cryic and cryiac toxins to spodoptera sp. midgut epithelial cells in vitro. | a sensitive lactate dehydrogenase (ldh) assay was modified to determine the cytolytic activity of bacillus thuringiensis cryic and cryiac delta endotoxins to viable collagenase-dissociated midgut epithelial cells (mec) from larvae of spodoptera frugiperda and spodoptera exigua. the mec preparations from these spodoptera sp. consisted predominantly of columnar cells (65-75%) and goblet cells (25-35%). time course microscopy experiments indicated that only the columnar cells became swollen during ... | 1997 | 9156349 |
| channel activity caused by a bacillus thuringiensis delta-endotoxin preparation depends on the method of activation. | the spontaneous insertion of bacillus thuringiensis cry delta-endotoxins into planar lipid bilayers to form discrete channels in the absence of receptors is the subject of conflicting reports in the literature. because these proteins are synthesized as protoxins requiring proteolytic activation for conversion to the active form, differences in the in-vitro protocol used for this activation could be responsible for the contradictory results. to investigate this, cryla(c) toxin was activated by di ... | 1997 | 9160336 |
| cloning of the npra gene for neutral protease a of bacillus thuringiensis and effect of in vivo deletion of npra on insecticidal crystal protein. | the npra gene, encoding bacillus thuringiensis neutral protease a, was cloned by the use of gene-specific oligonucleotides. the size of neutral protease a deduced from the npra sequence was 566 amino acids (60,982 da). the cloned npra gene was partially deleted in vitro, and the deleted allele, designated npra3, was used to construct an npra3 strain (neutral protease a-deficient strain) of b. thuringiensis. growth and sporulation of the npra3 strain were similar to those of an isogenic npra+ str ... | 1997 | 9172350 |
| discrimination between bacillus cereus and bacillus thuringiensis using specific dna probes based on variable regions of 16s rrna. | identification of bacillus cereus and differentiation between b. cereus and closely related species are currently based on biochemical tests. the main problem is to discriminate between b. cereus and b. thuringiensis. sequencing part of the 16s rrna showed that several b. cereus isolates present in food and involved in food poisoning, confirmed according to the classical biochemical methods, were in fact b. thuringiensis. as this organism is the most commonly used microbial insecticide worldwide ... | 1997 | 8997705 |
| activation of phosphatidylinositol-specific phospholipase c toward inositol 1,2-(cyclic)-phosphate. | phosphatidylinositol-specific phospholipase c (pi-plc) from bacillus thuringiensis catalyzes the hydrolysis of phosphatidylinositol (pi) in discrete steps: (i) an intramolecular phosphotransferase reaction to form inositol 1,2-(cyclic)-phosphate (cip), followed by (ii) a cyclic phosphodiesterase activity that converts cip to inositol 1-phosphate. water-soluble cip was used as the substrate to study the cyclic phosphodiesterase activity and interfacial behavior of pi-plc. different detergent mice ... | 1997 | 9003187 |
| stereocontrolled syntheses of water-soluble inhibitors of phosphatidylinositol-specific phospholipase c: inhibition enhanced by an interface. | three inositol 1,2-(cyclic)-phosphate analogs, inositol cyclic phosphonates with different stereochemistry at the c-2 position of the inositol ring, have been synthesized as water-soluble inhibitors of phosphatidylinositol-specific phospholipase c (pi-plc). their inhibition of both phosphotransferase and cyclic phosphodiesterase activities has been studied in the absence and presence of an interface. key results include the following. (i) only the analog with the same stereochemistry at the c-2 ... | 1997 | 9003188 |
| cloning and expression of a bacillus thuringiensis (l1-2) gene encoding a crystal protein active against glossina morsitans morsitans and chilo partellus. | a local isolate of bacillus thuringiensis,designated l1-2, that is toxic to chilo partellus was found to be toxic to the adult tsetse fly, glossina morsitans morsitans. the delta-endotoxin crystals derived from the isolate gave a major protein band with a molecular weight of mr 130,000-140,000 on denaturing polyacrylamide gel electrophoresis. the sequence of the cloned gene was found to be similar to that of the b. thuringiensis subsp. kurstaki hd-73 cryia(c) gene, having one amino acid differen ... | 1997 | 9003589 |
| effects of bacillus thuringiensis subsp. israelensis (b.t.i.) applications on invertebrates from two streams on prince edward island. | 1997 | 8975807 | |
| initial frequency of alleles for resistance to bacillus thuringiensis toxins in field populations of heliothis virescens. | the risk of rapid pest adaptation to an insecticide is highly dependent on the initial frequency of resistance alleles in field populations. because we have lacked empirical estimates of these frequencies, population-genetic models of resistance evolution have relied on a wide range of theoretical estimates. the recent commercialization of genetically engineered cotton that constitutively produces an insecticidal protein derived from the biocontrol agent, bacillus thuringiensis (bt) has raised c ... | 1997 | 11038613 |
| cloning of a chitinase gene into bacillus thuringiensis subsp. aizawai for enhanced insecticidal activity. | chitinase from a high producing strain (tp-1) of bacillus licheniformis was used with b. thuringiensis subsp. aizawai (b.t.a.) in a combined larvicidal assay against the pest, spodoptera exigua. with 10 mu of this chitinase, the ld(50) of b.t.a. was reduced by 7.6, 13.8 and 15 times on days 3, 5 and 7, respectively when compared to use of b.t.a. alone. in addition, a combination of chitinase (10 mu) and b.t.a. at a sub-lethal dose retarded growth and development of s. exigua. in preparation for ... | 1997 | 12501305 |
| natural occurrence of bacillus thuringiensis on cabbage foliage and in insects associated with cabbage crops. | bacillus thuringiensis was isolated from the phylloplane of organically grown cabbage in one field during two growth seasons (1992-93). the frequency of b. thuringiensis varied between 0.02 and 0.67 of the total b. cereus/b. thuringiensis population, with an average of 0.11. characterization of the b. thuringiensis isolates from foliage showed that the majority (64% of 150 isolates) belonged to serovar kurstaki, had bipyramidal crystals and toxicity towards pieris brassicae and/or trichoplusia n ... | 1997 | 12452602 |
| seasonal distribution and characterization of bacillus thuringiensis isolated from sericultural environments in korea. | to isolate naturally occurring novel bacillus thuringiensis strains, we investigated the distribution and characteristics of b. thuringiensis from samples of sericultural farms in various regions of korea in the spring and fall. fifty-four b. thuringiensis strains out of 164 samples and 34 b. thuringiensis strains out of 135 samples were isolated in the spring and fall, respectively. seventy percent of the isolates in the spring and 15% in the fall were toxic to lepidopteran larvae. dipteran-act ... | 1998 | 12501280 |
| microbial control of mosquitoes with special emphasis on bacterial control. | there are a number of microbial agents including fungus, protozoa, virus and bacteria which act as mosquitocidal agents. however, among these agents, bacillus thuringiensis var israelensis and b. sphaericus are the most potent mosquitocidal agents. bacillus thuringiensis var israelensis and b. sphaericus are gram-positive sporulating bacteria which produce protoxin crystals during sporulation and are highly toxic to susceptible mosquito larvae when they ingest them. these bacterial agents are en ... | 1998 | 10748561 |
| delta-endotoxin proteins associated with spherical parasporal inclusions of the four lepidoptera-specific bacillus thuringiensis strains. | four lepidoptera-specific reference strains of bacillus thuringiensis, belonging to serovars sumiyoshiensis (h3a:3d), fukuokaensis (h3a:3d:3e), darmstadiensis (h10a:10b) and japonensis (h23), which produce spherical parasporal inclusions, were examined for comparative characterization of delta-endotoxins. sds-page profiles of the alkali-solubilized parasporal inclusions revealed the presence of single major protein bands of 130 kda in the four strains. chymotrypsin and trypsin treatment of the p ... | 1998 | 9633648 |
| larvicidal activity of bacillus thuringiensis isolated from jordanian habitats against drosophila melanogaster larvae. | bacillus thuringiensis was isolated from 23 of 37 samples obtained from different jordanian habitats. of the 37 samples, 187 different spore-forming colonies were selected and thirty (16%) were identified as b. thuringiensis based on their pathogenicity and production of parasporal inclusions. the lethal dose (ld50) of b. thuringiensis indicated a variation in their pathogenicity to drosophila melanogaster larvae. sensitivity of the first, the second and the third instar larvae of d. melanogaste ... | 1998 | 10664675 |
| field trials of biolarvicide bacillus thuringiensis var. israelensis strain 164 and the larvivorous fish aplocheilus blocki against anopheles stephensi for malaria control in goa, india. | severe outbreaks of malaria occurred in the coastal villages of the candolim primary health centre (phc) of goa, india, in 1993 and 1994. these outbreaks were associated with accelerated construction activity with an influx of migrant laborers. the weekly application of bacillus thuringiensis var. israelensis (b.t.i.) strain 164 at 1 g/m2 and introduction of the indigenous larvivorous fish aplocheilus blocki in major breeding habitats of anopheles stephensi replaced ongoing ddt spraying and pyre ... | 1998 | 10084141 |
| acute toxicity of selected pesticides to the pacific blue-eye, pseudomugil signifer (pisces). | because the larvivorous fish pseudomugil signifer is native to southeastern queensland and is abundant in shallow estuarine habitats, intertidal marshes, wetland habitats, and freshwater streams, it was chosen as an indicator species for toxicologic studies with pesticides. acute toxicity studies with 2 organophosphorus pesticides (pirimiphos-methyl and temephos) and 3 alternate compounds under evaluation for registration in australia (bacillus thuringiensis var. israelensis, s-methoprene, and p ... | 1998 | 10084142 |
| bacterial control of mosquito larvae: investigation of stability of bacillus thuringiensis var. israelensis and bacillus sphaericus standard powders. | bacillus thuringiensis var. israelensis and bacillus sphaericus products were assayed against their respective reference powders ips82 and sph88. since their production in 1982 and 1988, the potency and larvicidal activity of these standard powders have been regularly checked on their test insects aedes aegypti (for ips82) or culex pipiens (for sph88). over the 16-year evaluation period of ips82 and 10-year evaluation period of sph88, their potencies were considered stable. the global mean of ea ... | 1998 | 10084145 |
| kinetic modeling of omega-transamination for enzymatic kinetic resolution of alpha-methylbenzylamine. | a kinetic model for omega-transaminase from bacillus thuringiensis js64 was developed by using the king-altman method to simulate the kinetic resolution of alpha-methylbenzylamine (alpha-mba). starting from a ping-pong bi-bi mechanism, a complete kinetic model including substrate inhibition only in the reverse reaction (i.e., transamination between acetophenone and l-alanine) was developed. the asymmetric synthesis of (s)-alpha-mba proved to be difficult due to a much lower maximum reverse react ... | 1998 | 10099461 |
| [characterization of entomopathogenic bacillus samples isolated in senegal and study of their toxicity for malaria vectors]. | a screening program developed in senegal to isolate new strains of entomopathogenic bacillus has led to the isolation of 194 strains of bacillus thuringiensis and 9 strains of bacillus sphaericus from various sites and insect samples. the characterization of these strains regarding their h serotype, their crystal composition and their toxicity against mosquitoes (culex pipiens, aedes aegypti and anopheles stephensi) has led to the isolation of 27 mosquitocidal strains. as malaria is an important ... | 1998 | 10797955 |
| phosphatidylcholine activation of bacterial phosphatidylinositol-specific phospholipase c toward pi vesicles. | the effect of different phospholipids on the kinetic behavior of phosphatidylinositol-specific phospholipase c (pi-plc) from bacillus thuringiensis toward pi vesicles has been investigated. cosonicated pc/pi vesicles displayed enhanced hydrolysis of pi when less than 0. 20 mole fraction pc was incorporated into the vesicle; higher mole fractions of pc led to a decrease from the maximum activity mimicking surface dilution of substrate. since the pc could affect pi-plc binding to vesicles, the eff ... | 1998 | 9572869 |
| germination, growth, and sporulation of bacillus thuringiensis subsp. israelensis in excreted food vacuoles of the protozoan tetrahymena pyriformis. | spores of bacillus thuringiensis subsp. israelensis and their toxic crystals are bioencapsulated in the protozoan tetrahymena pyriformis, in which the toxin remains stable. each t. pyriformis cell concentrates the spores and crystals in its food vacuoles, thus delivering them to mosquito larvae, which rapidly die. vacuoles containing undigested material are later excreted from the cells. the fate of spores and toxin inside the food vacuoles was determined at various times after excretion by phas ... | 1998 | 9572947 |
| release of the glycosylphosphatidylinositol-anchored enzyme ecto-5'-nucleotidase by phospholipase c: catalytic activation and modulation by the lipid bilayer. | many hydrolytic enzymes are attached to the extracellular face of the plasma membrane of eukaryotic cells by a glycosylphosphatidylinositol (gpi) anchor. little is currently known about the consequences for enzyme function of anchor cleavage by phosphatidylinositol-specific phospholipase c. we have examined this question for the gpi-anchored protein 5'-nucleotidase (5'-ribonucleotide phosphohydrolase; ec 3.1.3.5), both in the native lymphocyte plasma membrane, and following purification and reco ... | 1998 | 9576857 |
| effects on larvicidal activity of single proline substitutions in alpha3 or alpha4 of the bacillus thuringiensis cry4b toxin. | the possible role of alpha-helices 3 and 4 in toxicity of the dipteran-active bacillus thuringiensis cry4b delta-endotoxin was investigated by employing proline substitutions via site-directed mutagenesis. similar to the wild-type cry4b, the mutant toxins were over-expressed in escherichia coli as cytoplasmic inclusions and were structurally stable upon solubilization and trypsin activation. the substitution of glutamine 149 by proline in the center of helix 4 (q149p) resulted in a nearly comple ... | 1998 | 9584996 |
| investigation of spectral reproducibility in direct analysis of bacteria proteins by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. | matrix-assisted laser desorption/ionization (maldi) time-of-flight mass spectrometry (tofms) can be used for rapid detection of bacteria proteins in a crude mixture. it can potentially be used as a tool for bacterial identification based on the mass spectral patterns or the appearance of some characteristic mass peaks. however, there are many experimental parameters that can potentially have a strong effect on the observed mass spectra. the objective of this work is to address the mass spectral ... | 1998 | 9586233 |
| bacillus thuringiensis insecticidal proteins: molecular mode of action. | growing interest in biorational pesticides has placed the bacillus thuringiensis insecticidal crystal proteins at the forefront of pesticides for plant genetic engineering. the development of improvement pesticides, both in enhanced activity and broader host range, depends on an understanding of its mechanism of action. this review presents a complete overview of the bacterium and the group of insecticidal proteins known as cry proteins or delta-endotoxins. the molecular mode of action is descri ... | 1998 | 9594569 |
| laboratory bioassay to compare susceptibilities of aedes aegypti and anopheles albimanus to bacillus thuringiensis var. israelensis as affected by their feeding rates. | this study presents the effect of differences in the feeding rates of aedes aegypti and anopheles albimanus on their susceptibilities to bacillus thuringiensis israelensis. aedes aegypti was more susceptible than an. albimanus because of its faster rate of feeding. aedes aegypti ingested 11.5 times more spores than did an. albimanus, resulting in lower lt50 values. anopheles albimanus larvae fed at a slower rate and required fewer spores than ae. aegypti to induce 50% mortality. these findings s ... | 1998 | 9599326 |
| cry1ac, a bacillus thuringiensis toxin, triggers extracellular ca2+ influx and ca2+ release from intracellular stores in cf1 cells | intracellular ca2+ concentration was measured in single cf1 cells (choristoneura fumiferana, spruce budworm) loaded with fura-2, a ca2+-sensitive fluorescent probe. cf1 cells displayed ca2+ surges in response to cry1ac and cry1c proteins, two cf1-toxic bacillus thuringiensis products, but not to cry1aa and cry3a, which are not toxic to cf1 cells. in the presence of extracellular ca2+, the toxin-induced ca2+ response was insensitive to methoxyverapamil, a voltage-dependent ca2+ channel blocker, b ... | 1998 | 9600867 |
| cloning and sequencing of three new putative toxin genes from clostridium bifermentans ch18. | three new open reading frames were found downstream from cbm71, a toxin gene from clostridium bifermentans malaysia (cbm) strain ch18. the first one (91bp downstream) called cbm72, is 1857bp long and encodes a 71727-da protein (cbm72) with a sequence similar to that of bacillus thuringiensis delta-endotoxins. this protein shows no significant toxicity to mosquito larvae. the two others, cbm17.1 (462bp) and cbm17.2 (459bp), are copies of the same gene encoding cbm p18 and p16 polypeptides and loc ... | 1998 | 9602158 |
| effects of midgut-protein-preparative and ligand binding procedures on the toxin binding characteristics of bt-r1, a common high-affinity receptor in manduca sexta for cry1a bacillus thuringiensis toxins. | the identity of the physiologically important cry1a receptor protein(s) in the lepidopteran manduca sexta has been a matter of dispute due to the multiple proteins which bind the cry1ac toxin. cry1aa, cry1ab, and cry1ac exhibit essentially identical toxicities toward m. sexta larvae and show a high degree of sequence and presumed structural identities. these similarities make it likely that there is a common mechanism of toxicity in these lepidopteran-specific toxins in terms of both mode of act ... | 1998 | 9603829 |
| expression of a bacillus thuringiensis delta-endotoxin gene by bacillus pumilus. | the delta-endotoxin genes from bacillus thuringiensis were introduced into a rhizosphere-inhabiting bacillus pumilus isolate to create a delta-endotoxin expression and delivery system for subterranean feeding insects such as the larvae of pale western cutworm (agrotis orthogonia morrison (lepidoptera: noctuidae)). preliminary experiments indicated that bacillus thuringiensis subsp. kurstaki cultures were toxic to pale western cutworm larvae. three different cry genes from bacillus thuringiensis ... | 1998 | 9606908 |
| insect resistance of transgenic tobacco expressing an insect chitinase gene. | chitinase expression in the insect gut normally occurs only during moulting, where the chitin of the peritrophic membrane is presumably degraded. thus, insects feeding on plants that constitutively express an insect chitinase gene might be adversely affected, owing to an inappropriately timed exposure to chitinase. this hypothesis was tested by introducing a cdna encoding a tobacco hornworm (manduca sexta) chitinase (ec 3.2.1.14) into tobacco via agrobacterium tumefaciens-mediated transformation ... | 1998 | 9608735 |
| characterization of plasmid paw63, a second self-transmissible plasmid in bacillus thuringiensis subsp. kurstaki hd73. | bacillus thuringiensis subspecies kurstaki hd73, toxic for lepidopteran larvae, contains two large self-transmissible plasmids of approximately 75 kb, pht73 and paw63. the conjugative plasmid pht73 has been studied extensively and has been shown to harbour the toxin gene cry1ac, the transposon tn4430 and several insertion sequences. in this study it was demonstrated that the minor plasmid paw63 is also self-transmissible and about 10-30 times more efficient in mobilizing plasmid pbc16. to facili ... | 1998 | 9611801 |