Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| 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 |
| control of pest blackflies (diptera:simuliidae) along the orange river, south africa: 1990-1995. | the efficacy of bacillus thuringiensis var. israelensis (b.t.i.) and temephos in controlling the pest blackfly simulium chutteri lewis along the middle orange river between 1990 and 1995, was assessed. larvicides were applied by helicopter to rapids and riffles between hopetown and onseepkans, a river distance of 807 km. larvicidal efficacy was based on the change in larval abundance at selected sites before and after each treatment. the success of the control programme was assessed independentl ... | 1996 | 9173360 |
| 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 |
| microdroplet application of mosquitocidal bacillus thuringiensis using ultra-low-volume generator for the control of mosquitos. | in an effort to develop a more effective technique in dispersing a microbial control agent, bacillus thuringiensis (bt), a truck-mounted ultra low volume (ulv) generator (scorpion) was used to disperse b. thuringiensis israelensis (bti) and bti with malathion. complete larval and adult mortalities for all tested mosquito species within the first 70-80 feet from the ulv generator were achieved. beyond that distance less than 50% mortality was achieved as insufficient sprayed particles reached the ... | 1996 | 9185282 |
| laboratory screening of different bacillus thuringiensis strains against certain lepidopteran pests and subsequent field evaluation on the pod boring pest complex of pigeonpea (cajanus cajan). | laboratory evaluation of different bacillus thuringiensis subspecies revealed that b. thuringiensis subsp. kurstaki (ncim 2514) at 10(8) spores/ml concentration caused more than 85% mortality to the neonate larvae of the lepidopteran insects spodoptera litura (f.) and phthorimaea operculella (z.). this strain at 10(10) spores/ml concentration was effective against the major lepidopteran pests comprising the pod boring complex of pigeonpea (cajanus cajan), viz. helicoverpa armigera (h.) and exela ... | 1997 | 9195006 |
| identification of two sequence elements associated with the gene encoding the 24-kda crystalline component in bacillus thuringiensis ssp. fukuokaensis: an example of transposable element archaeology. | a 6.5-kb fragment of plasmid dna from bacillus thuringiensis (bt) ssp. fukuokaensis that encodes a 24-kda crystalline component was analyzed to identify additional open reading frames (orfs). a novel bt is240-like element was found upstream of this gene and is considered to be a vestige of a once active insertion sequence due to a stop codon that interrupts the long orf encoding the putative transposase. this element was bounded by 17-bp terminal inverted repeats that defined the length of the i ... | 1997 | 9200224 |
| a high homology exists in n-terminal amino acid sequences of delta-endotoxins between lepidoptera-specific and coleoptera-specific bacillus thuringiensis strains. | the 130 kda parasporal inclusion proteins of the lepidoptera-specific bacillus thuringiensis reference strains for four h serovars were examined for sequences of 14 n-terminal amino acids. the four sequences fell into a single category, mnrnnqneyevida, and were dissimilar to any of the established sequences for lepidoptera- and/or diptera-killing crystal proteins. they were highly related to the reported sequence of the 130 kda protein of the strain buibui (serovar japonensis), which is specific ... | 1997 | 9203397 |
| [study on the test and evaluation of the toxicity of the strains preparation of the different subspecies of bacillus thuringiensis and on the research into its standardization]. | in this paper using the preparation of bacillus thuringiensis of usa standard sample-subsp. kurstaki hd-1-s-1980 (h3a3b) the toxicity to different subspecies preparations such as subsp. dendrolimus u strain(h4a4b), subsp. galleriae c88 strain (h5a5b) is tested and evaluated. and product's standardization is also researched. comparing their toxicity to various test-insects between the standard sample prepared from u strain and usa, standard sample, the boilogical determined results are as follows ... | 1996 | 9206272 |
| [morphologic characterization and protein analysis of phages isolated from type strains of bacillus thuringiensis]. | the lysogeny of eleven type strains of bacillus thuringiensis was studied. eight new phages were isolated from the variants b. thuringiensis var. tochigiensis, yunnanensis, colmeri, shandongiensis, neoleonensis, silo, mexicanensis, and toguchini belonging to the b1 morphotype. the phages that were isolated from b. thuringiensis var. tochigiensis, yunnanensis, shandongiensis, and mexicanensis possessed transverse disks at their tails and were classified into one morphological group. the protein p ... | 1997 | 9206754 |
| [restriction analysis of dna from phages isolated from type strains of bacillus thuringiensis]. | comparative analysis of the dna of 11 phages isolated from type strains of bacillus thuringiensis was performed by means of digestion with restriction nucleases. according to the results obtained, the studied phages were classified into five groups. within each group, complete identity was revealed in both the restriction fragment number and the molecular mass of individual fragments. no homology was observed between genome structures of phages assigned to different groups. | 1997 | 9206755 |
| cloning and analysis of the first cry gene from bacillus popilliae. | an 80-kda parasporal crystal protein was detected in protein extracts of sporangia of bacillus popilliae isolated from a diseased larva of the common cockchafer (melolontha melolontha l.). amino acid analysis of tryptic peptides revealed significant homology to the cry2aa endotoxins of bacillus thuringiensis. the gene crybp1 (cry18aa1), which codes for the parasporal crystal protein, was found in a putative cry operon on the bacterial chromosome, which contains at least one further (smaller) ope ... | 1997 | 9209052 |
| identification and characterization of a previously undescribed cyt gene in bacillus thuringiensis subsp. israelensis. | mosquitocidal bacillus thuringiensis strains show as a common feature the presence of toxic proteins with cytolytic and hemolytic activities, cyt1aa1 being the characteristic cytolytic toxin of bacillus thuringiensis subsp. israelensis. we have detected the presence of another cyt gene in this subspecies, highly homologous to cyt2an1, coding for the 29-kda cytolytic toxin from b. thuringiensis subsp. kyushuensis. this gene, designated cyt2ba1, maps upstream of cry4b coding for the 130-kda crysta ... | 1997 | 9212418 |
| unique regulation of crystal protein production in bacillus thuringiensis subsp. yunnanensis is mediated by the cry protein-encoding 103-megadalton plasmid. | in sporulating cultures of bacillus thuringiensis subsp. yunnanensis hd977, two cell types are observed: cells forming only spores and cells forming only crystals. curing analysis suggested that the crystal proteins are plasmid encoded. through plasmid transfer experiments, it was established that a 103-mda plasmid is involved in the crystal production. conjugal transfer of this plasmid to cry- recipient cells of bacillus thuringiensis subsp. kurstaki hd73-26 conferred the ability to produce cry ... | 1997 | 9212426 |
| biochemical and molecular characterization of the insecticidal fragment of cryv. | two c-terminal deletion constructs were made to study the effect of such deletions on the biological activity of the cryv protein of bacillus thuringiensis subsp. kurstaki. the results of feeding on neonatal larvae of ostrinia nubilalis (european corn borer [ecb]) indicated that the 50% lethal dose of the full-length cryv protein was 3.34 micrograms/g of diet (95% fiducial limits, 2.53 to 4.32 micrograms/g of diet). removal of 71 amino acids (aa) from the c terminus had little effect on toxicity ... | 1997 | 9212427 |
| phosphatidylinositol-specific phospholipase c cyclic phosphodiesterase activity depends on solvent polarity. | large enhancements (maximum of 82-fold in terms of enzyme efficiency, vmax/km) of bacterial pi-plc cyclic phosphodiesterase activity were observed in the presence of organic solvents miscible in water (dimethyl sulfoxide, dimethylformamide, and 2-propanol). in general, organic solvents lowered the km for myo-inositol 1,2-cyclic phosphate (cip) and increased vmax substantially. this kinetic effect was similar to that obtained with phosphatidylcholine micelles and bilayers in an aqueous assay syst ... | 1997 | 9214296 |
| characterization of bacillus thuringiensis isolated from infections in burn wounds. | four strains of bacillus thuringiensis were isolated from infections in burn wounds and from water used in the treatment of burn wounds. the strains produced large parasporal inclusion bodies composed of 141, 83, and 81 kda protoxins. the four strains were tested for insecticidal activity against larvae of pieris brassicae and aedes aegypti but showed no activity; vero cell assays for the production of enterotoxins were also negative. attempts to classify the strains according to flagellar h-ser ... | 1997 | 9215586 |
| intramolecular proteolytic cleavage of bacillus thuringiensis cry3a delta-endotoxin may facilitate its coleopteran toxicity. | the cry3a delta-endotoxin protein inclusion synthesized by bacillus thuringiensis subsp. tenebrionis is soluble in alkaline and acid buffer solutions but the toxin precipitates when returned to neutral ph conditions. the midgut ph of susceptible beetle larvae is neutral to slightly acidic, a ph environment in which the cry3a toxin is insoluble. to investigate this paradox we studied the cry3a toxin after various proteolytic treatments. in many cases the toxin was cleaved into polypeptides that r ... | 1997 | 9217464 |
| aminopeptidase n from bombyx mori as a candidate for the receptor of bacillus thuringiensis cry1aa toxin. | cry1aa toxin-binding proteins from the midgut brush border membrane vesicles of bombyx mori, a toxin-susceptible silkworm, were analyzed to find candidates for the toxin receptors. ligand blotting showed that cry1aa toxin bound to a 120-kda protein. a part of the 120-kda protein was solubilized from the membrane vesicles with phosphatidylinositol-specific phospholipase c, resulting in a 110-kda protein which therefore may be linked to a glycosyl-phosphatidylinositol anchor. the 120-kda and 110-k ... | 1997 | 9219522 |
| is bt better? | 1997 | 9222128 | |
| specific sequence modifications of a cry3b endotoxin gene result in high levels of expression and insect resistance. | solanum melongena (eggplant) cv. picentia and the wild species solanum integrifolium were transformed with both a wild type (wt) and four mutagenized versions of bacillus thuringiensis (bt) gene bt43 belonging to the cry3 class. the bt gene was partly modified in its nucleotide sequence by replacing four target regions (w: +1 to +170; x: +592 to +1057; y: +1203 to +1376; z: +1376 to +1984) with synthetic fragments obtained by polymerase chain reaction amplification of crude oligonucleotides. the ... | 1997 | 9225859 |
| restriction of intramolecular movements within the cry1aa toxin molecule of bacillus thuringiensis through disulfide bond engineering. | disulfide bridges were introduced into crylaa, a bacillus thuringiensis lepidopteran toxin, to stabilize different protein domains including domain i alpha-helical regions thought to be involved in membrane integration and permeation. bridged mutants could not form functional ion channels in lipid bilayers in the oxidized state, but upon reduction with beta-mercaptoethanol, regained parental toxin channel activity. our results show that unfolding of the protein around a hinge region linking doma ... | 1997 | 9237670 |
| [extrachromosomal dna spectrum of bacillus thuringiensis berliner and bacillus sphaericus meyer et neide]. | analysis of the pattern of extrachromosomal dna in different cultures of bacillus thuringiensis and bacillus sphaericus demonstrated a higher content of extrachromosomal dna in b. thuringiensis than in b. sphaericus. the quantity and approximate molecular weights of the plasmids were determined. the assumption that the plasmid dna content in b. thuringiensis strains is higher than in the other representatives of the genus bacillus was confirmed. | 1997 | 9244760 |
| effect of insecticidal crystal proteins of bacillus thuringiensis on human erythrocytes in vitro. | effect of intact and alkali solubilized insecticidal crystal protein (icp) preparations from a mutant strain of b. thuringiensis var. israelensis (vcrc mb24) and the wild type strain (vcrc b17) in vitro on human erythrocytes with respect to lipid peroxidation, osmofragility and membrane bound enzymes was determined. the alkali solubilized icps of both b. thuringiensis strains caused increased lipid peroxidation, decreased resistance to hypotonic lysis and reduction in the activity of membrane bo ... | 1996 | 9246919 |
| phage display of bacillus thuringiensis cryia(a) insecticidal toxin. | the display of proteins or peptides on the surface of filamentous phages or phagemids has been shown to be a very powerful technology for the rescue of specific binders from large combinatorial libraries, as well as to select derivatives of known proteins with altered binding properties. the bacillus thuringiensis (bt) crystal proteins are a large family of insecticidal toxins which bind to receptors found on the brush border of larval midgut cells, different crystal toxins having different larv ... | 1997 | 9247136 |
| pcr-based approach for detection of novel bacillus thuringiensis cry genes. | a two-step strategy, named exclusive pcr or e-pcr, has been developed to overcome the main limitation of pcr, which is the detection of already-known sequences only. this strategy allows the ability to detect and further clone and sequence genes for which no specific primers are available and in which a variable region exists between two conserved regions. this approach has been applied to bacillus thuringiensis cryi genes by the use of mixtures of degenerate and specific primers recognizing wel ... | 1997 | 9251188 |
| cloning and characterization of a cytolytic and mosquitocidal delta-endotoxin from bacillus thuringiensis subsp. jegathesan. | a cytolytic toxin gene encoding a 30.1-kda cyt2bb1 toxin protein from b. thuringiensis subsp. jegathasan was cloned employing a limited-growth pcr screening method with forward and reverse oligonucleotide primers designed from n-terminal amino acid sequences of native and trypsin-cleaved protein, respectively. the expressed protein showed little cross-reactivity to the antibody raised against the cyt1aa protein. unlike cyt1aa and cyt2aa expression, there was little or no visible crystal inclusio ... | 1997 | 9251213 |
| membrane insertion: the strategies of toxins (review). | protein toxins are soluble molecules secreted by pathogenic bacteria which act at the plasma membrane or in the cytoplasm of target cells. they must therefore interact with a membrane at some point, either to modify its permeability properties or to reach the cytoplasm. as a consequence, toxins have the built-in capacity to adopt two generally incompatible states: water-soluble and transmembrane. irrespective of their origin or function, the membrane interacting domain of most protein toxins see ... | 1997 | 9253764 |
| allosteric activation of phosphatidylinositol-specific phospholipase c: specific phospholipid binding anchors the enzyme to the interface. | phosphatidylinositol-specific phospholipase c (pi-plc) from bacillus thuringiensis exhibits 'interfacial activation' toward the water-soluble substrate myo-inositol 1,2-(cyclic)phosphate [zhou et al. (1997) biochemistry 36, 347-355]. the activation of pi-plc enzyme is optimal with pc or pe interfaces. nmr experiments (trnoe and 31p line width analyses) were carried out to investigate the interaction of pi-plc with activator amphiphiles. these studies showed that the enzyme had high affinity for ... | 1997 | 9254604 |
| ion channels formed in planar lipid bilayers by bacillus thuringiensis toxins in the presence of manduca sexta midgut receptors. | a purified, gpi-linked receptor complex isolated from manduca sexta midgut epithelial cells was reconstituted in planar lipid bilayers. cryiaa, cryiac and cryic, three bacillus thuringiensis insecticidal proteins, formed channels at much lower doses (0.33-1.7 nm) than in receptor-free membranes. the non-toxic protein cryib also formed channels, but at doses exceeding 80 nm. the channels of crylac, the most potent toxin against m. sexta, rectified the passage of cations. all other toxin channels ... | 1997 | 9256233 |
| isolation and partial characterisation of insulin-mimetic inositol phosphoglycans from human liver. | extracts of human liver were found to contain activities which copurified and coeluted with the two major subtypes of mediators (type a and type p) isolated from insulin-stimulated rat liver. the putative type a mediator from human liver inhibited camp-dependent protein kinase from bovine heart, decreased phosphoenolypyruvate carboxykinase mrna levels in rat hepatoma cells, and stimulated lipogenesis in rat adipocytes. the putative type p mediator stimulated bovine heart pyruvate dehydrogenase p ... | 1997 | 9259987 |
| nucleotide sequence and characterization of the cryptic bacillus thuringiensis plasmid pgi3 reveal a new family of rolling circle replicons. | the complete nucleotide sequence of plasmid pgi3 from bacillus thuringiensis subsp. thuringiensis h1.1. was obtained. although this 11,365-bp molecule contained at least 11 putative open reading frames (orfs), extensive database searches did not reveal any homologous sequences with the exception of orf6, which displayed similarity to the largest orf of pstk1, a 1,883-bp cryptic plasmid isolated from bacillus stearothermophilus. deletion analysis to determine the pgi3 minimal replicon revealed th ... | 1997 | 9260939 |
| cell integrity markers for in vitro evaluation of cytotoxic responses to bacteria-containing commercial insecticides. | toxicity of two commercial "bt" products, containing bacillus thuringiensis subsp. kurstaki spores (btk) and associated parasporal inclusion body proteins, was tested in vitro using two unrelated lepidoperan cell lines and several markers of cell integrity (morphology, quantification of loss of adherence and electron transport (redox) activity, and degradation of nuclear dna, actin, hsp-70, and beta-tubulin). with doses of 10(-7), 10(-5), and 10(-3) international units (iu)/target cell, these ma ... | 1997 | 9262955 |
| marginal cross-resistance to mosquitocidal bacillus thuringiensis strains in cry11a-resistant larvae: presence of cry11a-like toxins in these strains. | culex quinquefasciatus mosquito larvae resistant to the cry11a toxin showed marginal cross-resistance to the multiple toxin crystals from b. thuringiensis subsp. israelensis and also to toxin crystals from three other mosquitocidal strains, i.e. b. thuringiensis subsp. fukuokaensis, subsp. jegathesan, and subsp. kyushuensis. cross-resistance patterns of the cry11a-resistant larvae to mosquitocidal strains of b. thuringiensis together with the immunological screening using antisera raised against ... | 1997 | 9271871 |
| diversity and differential distribution of is231, is232 and is240 among bacillus cereus, bacillus thuringiensis and bacillus mycoides. | bacillus cereus, bacillus thuringiensis and bacillus mycoides are very closely related bacteria, generally considered as subspecies of b. cereus sensu lato. different transposable elements have been isolated from b. thuringiensis, including is231, is232 and is240 and their variants. the distribution of these three insertion sequences (is) within the b. cereus group has been investigated in 90 strains of b. thuringiensis (representing 61 serovars), in 30 reference strains of b. cereus and in 33 s ... | 1997 | 9274007 |
| spo0a represses transcription of the cry toxin genes in bacillus thuringiensis. | the dna regions upstream from the genes encoding polypeptides of bacillus thuringiensis subsp. israelensis larvicidal crystals (cry4a, cry4b, cry11a) contain sequences with similarities to the spo0a box of bacillus subtilis (or '0a' box) and the promoter recognized by the sigma h-associated rna polymerase of b. subtilis. expression of cry-lacz transcriptional fusions was analysed in various b. thuringiensis genetic backgrounds. the early transcription of the toxin genes was not sporulation-depen ... | 1997 | 9274027 |
| simultaneous production of the 34-kda and 40-kda proteins from bacillus thuringiensis subsp. thompsoni is required for the formation of inclusion bodies. | cooperation of two crystal proteins from bacillus thuringiensis subsp. thompsoni. strain hnc was shown to be essential for the formation of inclusion bodies. expression of the operon containing the 34-kda and 40-kda protein genes from hnc in a b. thuringiensis crystal minus strain resulted in the formation of inclusion bodies identical to those from strain hnc. interruption of one of the genes in the operon led to the lack of inclusion body and to low production of the remaining protein. absence ... | 1997 | 9276472 |
| suitability of 30 agricultural products and by-products as nutrient sources for laboratory production of bacillus thuringiensis subsp. aizawai (hd133) | bacillus thuringiensis subsp. aizawai (hd133) was grown in culture media in which dextrose was a common carbon source and 30 different agricultural products and by-products were tested as the main nitrogen sources. these products included legumes, cereals, animal proteins, leaf proteins, yeasts, oilseeds, tubers, and casamino acid. of the 30 products tested, cottonseed meal, defatted soy flour, and corn gluten meal were the most efficient substrates for the production of spore-crystal biomass an ... | 1997 | 9281398 |
| bacillus thuringiensis delta-endotoxin binding sites in two lepidoptera, wiseana spp. and epiphyas postvittana | proteins from the midguts of the light-brown apple moth epiphyas postvittana (walker) and the porina caterpillars wiseana cervinata (walker), w. copularis (meyrick), and w. jocosa (meyrick) which bind the bacillus thuringiensis delta-endotoxin cry1ba were characterized using cry1ba labeled with bolton and hunter reagent. a comparison of two iodine labeling techniques on the toxicity of b. thuringiensis delta-endotoxins showed that labeling using chloramine-t substantially decreased cry1ba toxici ... | 1997 | 9281402 |
| involvement of an endogenous metalloprotease in the activation of protoxin in bacillus thuringiensis subsp. kurstaki. | insecticidal crystal proteins harvested from sporulated cultures of bacillus thuringiensis subsp. kurstaki contain the protoxin (mr 132 kda) and minor amounts of toxin (66 kda). the proteolytic processing of 132 kda protoxin to an active 66 kda toxin is brought about by exogenous proteases or larval gut enzymes. under denaturing/reducing conditions this conversion is also mediated by endogenous protease(s) of the producer organism. this endogenous protease is identified as a metalloprotease as t ... | 1997 | 9285057 |
| field evaluation of bacillus sphaericus, h5a5b and b. thuringiensis var. israelensis, h-14 against the bancroftian filariasis vector culex quinquefasciatus, say in chennai, india. | fortnightly application of bacillus sphaericus (strain b101, serotype h5a5b) and b. thuringiensis var. israelensis (strain 164, serotype h-14) in two different waterways of chennai @ 1 g/sq m surface area has resulted in significant reduction in both immature and adult densities of culex quinquefasciatus say. the use of these biolarvicides as biocontrol agents is suggested in the urban areas to control mosquitoes in general. | 1997 | 9291671 |
| field trial of bacticide on larval populations of two species of vector mosquitoes in calcutta. | 1997 | 9291672 | |
| urban malaria vector biology. | one of the main reasons for the set-back in the urban malaria control programme is the peculiar biobehaviour of the principal urban malaria vector anopheles stephensi. certain relevant facts such as incrimination as the vector of malaria, sibling or biological species, resting habitat, manlanding behaviour, seasonal prevalence, blood meal analysis, longevity, parity status, daily survival and mortality rates of adults, breeding habitats and vertical distribution of larvae of an. stephensi have b ... | 1997 | 9291684 |
| biological control of malaria vectors. | a comprehensive review is presented of the potentiality of biocontrol agents viz. entomophagus bacteria (bacillus thuringiensis var. israelensis and bacillus sphaericus), fungi, microsporidians, predators and parasites against malaria vectors in the field condition. unlike insecticides, these control agents are host specific and safer to the environment. however, barring fishes which are being used in certain situations, other biocontrol agents have not yet reached the operational stage. two spo ... | 1997 | 9291686 |
| presence in human erythrocyte membranes of a novel form of sialidase acting optimally at neutral ph. | the feature of intact human erythrocytes and erythrocyte white ghosts is a unique sialidase activity with acidic optimal ph (acidic sialidase). the treatment of white ghosts with mildly alkaline isotonic solutions at 37 degrees c, like that used to produce resealed ghosts, is accompanied by the expression, together with the acidic sialidase, of a novel sialidase with a ph optimum of 7.2 (neutral sialidase) that remained masked in the inside-out vesicles prepared from white ghosts. exhaustive tre ... | 1997 | 9292542 |
| ligand specificity and affinity of bt-r1, the bacillus thuringiensis cry1a toxin receptor from manduca sexta, expressed in mammalian and insect cell cultures. | the manduca sexta receptor for the bacillus thuringiensis cry1aa, cry1ab, and cry1ac toxins, bt-r1, has been expressed in heterologous cell culture, and its ligand binding characteristics have been determined. when transfected with the bt-r1 cdna, insect and mammalian cell cultures produce a binding protein of approximately 195 kda, in contrast to natural bt-r1 from m. sexia, which has an apparent molecular weight of 210 kda. transfection of cultured spodoptera frugiperda cells with the bt-r1 cd ... | 1997 | 9292994 |
| proteinase-mediated insect resistance to bacillus thuringiensis toxins. | two bacillus thuringiensis (bt)-resistant strains of the indianmeal moth, plodia interpunctella, lack a major gut proteinase that activates bt protoxins. the absence of this enzyme is genetically linked to larval survival on bt-treated diets. when considered with previous data supporting the existence of receptor-mediated insect resistance to bt, these results provide evidence that insect adaptation to these toxins occurs through multiple physiological mechanisms, which complicate efforts to pre ... | 1997 | 9295279 |
| modification of methane emission in sheep by cysteine and a microbial preparation. | modification of methane emission from ruminants by the use of l-cysteine and/or a microbial preparation in wethers fed lucerne hay was assessed in an open circuit respiratory trial according to a 4 x 4 latin squared design. l-cysteine (0.1 g kg-1 w0.75, as sulphur equivalent) was drenched daily to wethers as an aqueous solution of hydrochloride. the microbial preparation was a dried mixture of bacillus subtilis, bacillus cereus, bacillus thuringiensis, pseudomonas fluorescens, streptomyces cellu ... | 1997 | 9301098 |
| further characterization of bt-r1, the cadherin-like receptor for cry1ab toxin in tobacco hornworm (manduca sexta) midguts. | bt-r1, the manduca sexta midgut receptor for the crystal toxin cry1ab produced by bacillus thuringiensis ssp. berliner, was partly purified by gel filtration from m. sexta brush border membrane vesicles in the presence of the detergent chaps. fractions containing bt-r1 were tested for their stability against degradation as indicated by retention of cry1ab binding on ligand blots. at 4 degrees c and ph 7.4 in the presence of ca2+, bt-r1 was stable for up to 48 h but a 65% loss of binding was obse ... | 1997 | 9304795 |
| assessing the odds: the emergence of resistance to bt transgenic plants. | 1997 | 9306386 | |
| bacillus thuringiensis crylaa delta-endotoxin affects the k+/amino acid symport in bombyx mori larval midgut. | we have examined the type of inhibition exerted by an activated preparation of the bacillus thuringiensis delta-endotoxin crylaa on k+-dependent leucine transport into midgut brush border membrane vesicles or epithelial cells of the isolated midgut from bombyx mori to study its possible interaction with the amino acid symporter. k+ permeability and the cation-dependent amino acid translocation into brush border membrane vesicles were evaluated by monitoring the fluorescence of the voltage-sensit ... | 1997 | 9312210 |
| aminopeptidase dependent pore formation of bacillus thuringiensis cry1ac toxin on trichoplusia ni membranes. | the insecticidal bacillus thuringiensis cry1ac delta-endotoxin specifically binds to a 120 kda aminopeptidase n (apn) in the midgut of susceptible insects such as manduca sexta, heliothis virescens, lymantria dispar and plutella xylostella. the 120 kda apn has a glycosylphosphatidylinositol (gpi) anchor susceptible to the action of gpi-specific phospholipase c (piplc). here we show that cry1ac pore-forming activity depends on the amount of apn present on brush border membrane vesicles (bbmv) fro ... | 1997 | 9315707 |
| isolated domain ii and iii from the bacillus thuringiensis cry1ab delta-endotoxin binds to lepidopteran midgut membranes. | the dna fragment encoding cry1ab domain ii-iii (45.3 kda) was cloned and expressed. domain ii-iii is expressed in low yields. in vitro binding analysis to manduca sexta and trichoplusia ni larval midgut tissue sections demonstrated that domain ii-iii fragment bound along the microvilli of the midgut epithelium, indicating that this fragment retains binding functionality in the absence of domain i. binding of domain ii-iii to the midgut brush border membrane proteins from t. ni larvae indicated t ... | 1997 | 9315709 |
| determinants for the activity of the neutral amino acid/k+ symport in lepidopteran larval midgut | the columnar cells of lepidopteran larvae express, in their apical brush-border membrane, a class of symporters which in vivo couple the intracellularly directed amino acid and k+ fluxes. an analysis of the functional properties of the symporter for neutral amino acids along the anterior, middle and posterior regions of the larval midgut of bombyx mori demonstrated the ability of a k+ gradient to drive leucine accumulation into brush-border membrane vesicles (bbmv) in all three preparations. how ... | 1994 | 9317520 |
| single-site mutations in the conserved alternating-arginine region affect ionic channels formed by cryiaa, a bacillus thuringiensis toxin. | the role of the third domain of cryiaa, a bacillus thuringiensis insecticidal toxin, in toxin-induced membrane permeabilization in a receptor-free environment was investigated. planar lipid bilayer experiments were conducted with the parental toxin and five proteins obtained by site-directed mutagenesis in block 4, an arginine-rich, highly conserved region of the protein. four mutants were constructed by replacing the first arginine in position 21 by a lysine (r521k), a glutamine (r521q), a hist ... | 1997 | 9327562 |
| cloning, expression and toxicity of a mosquitocidal toxin gene of bacillus thuringiensis subsp. medellin. | bacillus thuringiensis (bt) subsp. medellin (btmed) produces parasporal crystalline inclusions which are toxic to mosquito larvae. it has been shown that the inclusions of this bacterium contain mainly proteins of 94, 68 and 28-30 kda. ecori partially digested total dna of btmed was cloned by using the lambda zap ii cloning kit. recombinant plaques were screened with a mouse polyclonal antibody raised against the 94 kda crystal protein of btmed. one of the positive plaques was selected, and by i ... | 1997 | 9332588 |
| mechanism of decay of the cry1aa mrna in bacillus subtilis. | we undertook the study of the decay process of the cry1aa mrna of bacillus thuringiensis expressed in b. subtilis. the cry1aa transcript is a 3.7-kb mrna expressed during sporulation whose transcriptional control has previously been studied in both b. subtilis and b. thuringiensis. we found that the cry1aa mrna has a half-life of around 9 min and that its decay occurs through endoribonucleolytic cleavages which result in three groups of high-molecular-weight mrna intermediates ranging in size fr ... | 1997 | 9335281 |
| interaction of the delta-endotoxin cyta from bacillus thuringiensis var. israelensis with lipid membranes. | we investigated the binding of cyta, a cytolytic delta-endotoxin from bacillus thuringiensis var. israelensis, to small unilamellar lipid vesicles (suv) and the accompanying changes in the overall cyta conformation. from the titration of tryptophan fluorescence with suv, we determined the apparent association constants of 3500 m-1 and 11000 m-1 for the protoxin cyta27 and the proteolytically activated toxin cyta24, respectively. inclusion of a negatively charged lipid or a positively charged lip ... | 1997 | 9335544 |
| cloning and characterization of manduca sexta and plutella xylostella midgut aminopeptidase n enzymes related to bacillus thuringiensis toxin-binding proteins. | we report the purification, cloning and characterization of an aminopeptidase n from the midgut epithelium of manduca sexta that binds cry1ab5, an insecticidal crystal protein [icp] from bacillus thuringiensis. sequence information derived from this m. sexta aminopeptidase n was used for the cloning of an aminopeptidase n from the midgut brush-border membrane of plutella xylostella, an insect species of which some populations acquired resistance against cry1ab5. affinity chromatography on a cry1 ... | 1997 | 9342226 |
| 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 |