Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| contribution of bacillus thuringiensis spores to toxicity of purified cry proteins towards indianmeal moth larvae | the influence of bacillus thuringiensis subsp. kurstaki hd-1 spores upon the toxicity of purified cry1ab and cry1c crystal proteins toward susceptible and bt-resistant indianmeal moth (imm, plodia interpunctella) larvae was investigated. with susceptible larvae, hd-1 spores were toxic in the absence of crystal protein and highly synergistic (approximately 35- to 50-fold) with either cry1ab or cry1c protein. with bt-resistant imm larvae, hd-1 spores were synergistic with cry1ab and cry1c protein ... | 1996 | 8661690 |
| cloning of a cryv-type insecticidal protein gene from bacillus thuringiensis: the cryv-encoded protein is expressed early in stationary phase. | a cryv-type protein (cgcryv) has been isolated from supernatant fluids of bacillus thuringiensis ab88 cultures. previous reports have suggested the cryptic nature of the cryv-type genes on the basis of the absence of cryv-type proteins in parasporal crystals. the cryv-type protein reported here is expressed early in stationary phase, and evidence indicates that it is an exported protein. analysis of the deduced protein sequence from this gene reveals the presence of an n-terminal domain that lik ... | 1996 | 8606196 |
| inconsistencies in determining bacillus thuringiensis toxin binding sites relationship by comparing competition assays with ligand blotting. | receptor binding properties of cry1aa, cry1ab, and cry1ac bacillus thuringiensis toxins to lymantria dispar brush border membrane vesicles (bbmv) were investigated by competition assays and bbmv ligand blotting. homologous competition binding assays demonstrated that all cry ia toxins bound to l. dispar bbmv with high binding affinities. heterologous competition assays suggested that all three toxins share the same binding sites. however, our ligand blotting experiments were not consistent with ... | 1996 | 8607806 |
| analysis of cryiaa expression in sige and sigk mutants of bacillus thuringiensis. | the sige and sigk genes, encoding the sporulation-specific sigma factors sigma 35 and sigma 28 of bacillus thuringiensis, were each disrupted by inserting a gene conferring resistance to kanamycin into their coding sequences. the b. thuringiensis sige- and sigk- mutant strains were blocked at different sporulation stages and were unable to sporulate. the sige-strain was blocked at stage ii of sporulation, whereas the sigk- strain was blocked at stage iv. the expression of a cryiaa'-'lacz transcr ... | 1996 | 8628234 |
| identification of a bacillus thuringiensis gene that positively regulates transcription of the phosphatidylinositol-specific phospholipase c gene at the onset of the stationary phase. | a transcriptional analysis of the phosphatidylinositol-specific phospholipase c (plca) gene of bacillus thuringiensis indicated that its transcription was activated at the onset of the stationary phase in b. thuringiensis but was not activated in b. subtilis. the b. thuringiensis gene encoding a transcriptional activator required for plca expression was cloned by using a b. subtilis strain carrying a chromosomal plca'-'lacz fusion as a heterologous host for selection. this trans activator (desig ... | 1996 | 8631661 |
| structure of the mosquitocidal delta-endotoxin cytb from bacillus thuringiensis sp. kyushuensis and implications for membrane pore formation. | the delta-endotoxin cytb, found in parasporal inclusions of bacillus thuringiensis subspecies kyushuensis, is a membrane pore-forming protein which is lethal to the larvae of dipteran insects and broadly cytolytic in vitro. the crystal structure of cytb in the protoxin form has been determined by isomorphous replacement using heavy-atom derivatives of both the wild-type protein and an engineered cysteine mutant. the atomic model comprising residues 19 to 245 and 28 bound water molecules has been ... | 1996 | 8632451 |
| domain iii substitution in bacillus thuringiensis delta-endotoxin cryia(b) results in superior toxicity for spodoptera exigua and altered membrane protein recognition. | to test our hypothesis that substitution of domain iii of bacillus thuringiensis delta-endotoxin (cry) proteins might improve toxicity to pest insects, e.g., spodoptera exigua, in vivo recombination was used to produce a number of cryia(b)-cryic hybrid genes. a rapid screening assay was subsequently exploited to select hybrid genes encoding soluble protoxins. screening of 120 recombinants yielded two different hybrid genes encoding soluble proteins with domains i and ii of cryia(b) and domain ii ... | 1996 | 8633853 |
| synergistic effect of the bacillus thuringiensis toxins cryiaa and cryiac on the gypsy moth, lymantria dispar. | the insecticidal activity of toxins cryiaa, cryiab, and cryiac against lymantria dispar (gypsy moth) and bombyx mori (silkworm) was examined by force-feeding bioassays. toxin cryiaa exhibited higher toxicity than toxins cryiab and cryiac for l. dispar and b. mori. to evaluate possible synergism among these toxins, bioassays were performed with mixtures of cryiaa and cryiab, cryiab and cryiac, and cryiaa and cryiac. expected toxicity was calculated from the activity of each individual toxin and i ... | 1996 | 8593057 |
| mosquitocidal activity of the cryic delta-endotoxin from bacillus thuringiensis subsp. aizawai. | the cloned 135-kda cryic delta-endotoxin from bacillus thuringiensis is a lepidopteran-active toxin, displaying high activity in vivo against spodoptera litoralis and spodoptera frugiperda larvae and in vitro against the s. frugiperda sf9 cell line. here, we report that the cryic delta-endotoxin cloned from b. thuringienesis subsp. aizawai hd-229 and expressed in an acrystalliferous b. thuringiensis strain is also toxic to aedes aegypti, anophles gambiae, and culex quinquefasciatus mosquito larv ... | 1996 | 8593070 |
| transmission dynamics of bacillus thuringiensis infecting plodia interpunctella: a test of the mass action assumption with an insect pathogen. | central to theoretical studies of host-pathogen population dynamics is a term describing transmission of the pathogen. this usually assumes that transmission is proportional to the density of infectious hosts or particles and of susceptible individuals. we tested this assumption with the bacterial pathogen bacillus thuringiensis infecting larvae of plodia interpunctella, the indian meal moth. transmission was found to increase in a more than linear way with host density in fourth and fifth insta ... | 1996 | 8587898 |
| functional significance of loops in the receptor binding domain of bacillus thuringiensis cryiiia delta-endotoxin. | analysis of the three surface loops in domain ii of bacillus thuringiensis cryiiia delta-endotoxin has been carried out to assess their role in receptor binding and toxicity. site-directed mutagenesis was used to convert loop residues to alanine and the mutant proteins were analyzed for structural stability, toxicity to beetle larvae (tenebrio molitor), binding to receptors on t. molitor brush border membrane vesicles (tm-bbmv) and insertion into bbmv, as measured by irreversible membrane recept ... | 1996 | 8568902 |
| site-directed mutations in the third domain of bacillus thuringiensis delta-endotoxin cryiaa affect its ability to increase the permeability of bombyx mori midgut brush border membrane vesicles. | a series of mutant bacillus thuringiensis cryiaa delta-endotoxin proteins was prepared by replacing the first, second, and last arginine residues of the conserved third-domain sequence, r-521 yrvrir-527, with other amino acids. the stable mutant proteins were bioassayed against bombyx mori larvae and found to all be approximately half as active as wild-type cryiaa. the toxins were also tested by means of a light-scattering assay for their ability to increase permeability of larval b. mori midgut ... | 1996 | 8572707 |
| a bacillus thuringiensis insecticidal crystal protein with a high activity against members of the family noctuidae. | the full characterization of a novel insecticidal crystal protein, named cry9ca1 according to the revised nomenclature for cry proteins, from bacillus thuringiensis serovar tolworthi is reported. the crystal protein has 1,157 amino acids and a molecular mass of 129.8 kda. it has the typical features of the lepidoptera-active crystal proteins such as five conserved sequence blocks. also, it is truncated upon trypsin digestion to a toxic fragment of 68.7 kda by removal of 43 amino acids at the n t ... | 1996 | 8572715 |
| role of domain ii, loop 2 residues of bacillus thuringiensis cryiab delta-endotoxin in reversible and irreversible binding to manduca sexta and heliothis virescens. | site-directed mutagenesis was used to examine the role of domain ii, loop 2 residues, 368rrpfnigi375, of bacillus thuringiensis insecticidal protein cryiab. alanine substitution of residues 368rrp370, called b4, abolished potency toward manduca sexta and heliothis virescens, and the loss of toxicity was correlated directly to substantially reduced binding affinity to brush-border membrane vesicles (bbmv) prepared from the target insect midguts. these results indicated that these positive charges ... | 1996 | 8576197 |
| characterization of six highly mosquitocidal bacillus thuringiensis strains that do not belong to h-14 serotype. | four strains belonging to bacillus thuringiensis serovars thompsoni, malaysiensis, canadensis, jegathesan and two auto-agglutinating b.t. strains were identified as being highly toxic to the mosquito larvae of the species aedes aegypti, anopheles stephensi, and culex pipiens. their larvicidal and hemolytic activities were determined and compared with those of strains known to be highly mosquitocidal and/or cytolytic from serovars of b.t. israelensis, morrisoni, darmstadiensis, medellin, kyushuen ... | 1996 | 8555944 |
| transgenic indica rice breeding line ir58 expressing a synthetic cryia(b) gene from bacillus thuringiensis provides effective insect pest control. | the indica rice breeding line ir58 was transformed by particle bombardment with a truncated version of a synthetic cryia(b) gene from bacillus thuringiensis. this gene is expressed under control of the camv 35s promoter and allows efficient production of the lepidopteran specific delta-endotoxin. r0, r1 and r2 generation plants displayed a significant insecticidal effect on several lepidopterous insect pests. feeding studies showed mortality rates of up to 100% for two of the most destructive in ... | 1996 | 9636319 |
| cloning and expression of full-length delta-endotoxin cryia(c) gene in three kinds of prokaryotic systems using shuttle vector pht3101. | two fragments, 6.5kb and 4.3kb encoding 5' end and 3' end of delta-endotoxin cryia(c) gene, respectively, were selected from the bacillus thuringiensis kurstaki-hd-73 75kb plasmid gene pool using random primer labelling delta-endotoxin cryia(b) gene probe. the full-length 3.92kb cryia(c) gene including 5' end 152 bp promoter sequence and 3' end 198 bp terminater sequence was rebuilt after uncoding sequences were deleted. three kinds of engineering strains harbouring the same recombinant plasmid ... | 1996 | 9639817 |
| [distribution of bacillus thuringiensis in soils of north and south of china]. | 221 isolates of bacillus thuringiensis were isolated in 1491 soil samples from north and south of china. h-serotypes and larvicidal characters of all bt isolates have been identified. the rate of bt-harbouring soil sample and the rate of bt isolates in northeast and neimeng were in 12.6% and 17.2% respectively. predominant serotypes were h4, h10, h3, h13, h5 and h29. the most fertile bt-harbouring area was the heilongjiang province with rate of bt-harbouring sample of 21.4% and rate of bt isolat ... | 1996 | 9639831 |
| [characterization of insecticidal crystal proteins of bacillus thuringiensis subsp. chinensis ct-43]. | bacillus thuringiensis subsp. chinensis ct-43, no flagellum, produces various shaped parasporal crystals, which consist of 140000, 130000, and 65000 proteins. based on two kinds of mutant, 140000 and 130000 crystal protein individually forms bipyramidal crystal and the 65000 protein forms cubidal crystal, and that the 140000 and 130000 protein is activated by trypsin into 55000 and 66000 proteins and 60000 protein, respectively. bioassay were conducted to 3rd instar plutella xylostella larvae wi ... | 1996 | 9639832 |
| 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 |
| [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 |
| 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 |
| response: evolution of insect resistance to bacillus thuringiensis--transformed plants. | 1996 | 17792216 | |
| toxicity of bacillus thuringiensis spore and crystal protein to resistant diamondback moth (plutella xylostella). | a colony of plutella xylostella from crucifer fields in florida was used in mortality bioassays with hd-1 spore, cryia(a), cryia(b), cryia(c), cryib, cryic, cryid, cryie, or cryiia. the data revealed high levels of field-evolved resistance to hd-1 spore and all cryia protoxins and no resistance to cryib, cryic, or cryid. cryie and cryiia were essentially not toxic. when hd-1 spore was combined 1:1 with protoxin and fed to susceptible larvae, spore synergized the activity of cryia and cryic 5- to ... | 1996 | 16535241 |
| characterization of a novel strain of bacillus thuringiensis. | bacillus thuringiensis is a well-known species of entomopathogenic bacteria that is widely used as a biopesticide against many insect pests. insecticidal proteins, coded for by genes located in plasmids, form typical parasporal, crystalline inclusions during sporulation. in this report, an unusual strain of b. thuringiensis subserovar oyamensis (lbit-113), isolated from living larvae of anopheles pseudopunctipennis in mexico, was characterized by its ultrastructure, the protein composition of it ... | 1996 | 16535294 |
| binding of bacillus thuringiensis cry1 toxins to the midgut brush border membrane vesicles of chilo suppressalis (lepidoptera: pyralidae): evidence of shared binding sites. | binding and competition among cry1aa, cry1ac, and cry1ba toxins were analyzed quantitatively in vitro by using (sup125)i-labeled activated toxins and brush border membrane vesicles isolated from chilo suppressalis larval midguts. the three toxins bound specifically to the midgut brush border membrane vesicles. direct binding experiments showed that cry1aa and cry1ba recognized a single class of binding sites with different affinities, whereas cry1aa recognized two classes of binding sites, one w ... | 1996 | 16535306 |
| binding of bacillus thuringiensis cry1 toxins to the midgut brush border membrane vesicles of chilo suppressalis (lepidoptera: pyralidae): evidence of shared binding sites. | volume 62, no. 5, p. 1544, abstract, line 4: "cry1aa" should read "cry1ac." [this corrects the article on p. 1544 in vol. 62.]. | 1996 | 16535392 |
| bacillus thuringiensis hd-73 spores have surface-localized cry1ac toxin: physiological and pathogenic consequences. | spores from cry(sup+) strains of bacillus thuringiensis bound fluorescein isothiocyanate-labeled antibodies specific for the 65-kda activated cry 1ac toxin, whereas spores from bacillus cereus and cry(sup-) strains of b. thuringiensis did not. the cry(sup+) spores could be activated for germination by alkaline conditions (ph 10.3), whereas cry(sup-) spores could not. once the surrounding exosporia had been removed or permeabilized, cry(sup+) spores were able to bind the toxin receptor(s) from in ... | 1996 | 16535421 |
| field trial of bacillus thuringiensis var israelensis pellet formulation in the control of mosquitoes. | in a simulated field trial bacillus thuringiensis var israelensis (bti) pellet formulation exhibited an enhanced efficacy with increasing dose. a dosage of 1.0 and 1.5 ppm was most effective under simulated field conditions. in field trials persistence of bti pellet (1.0 ppm) was observed for 35 days in moderately polluted water collection as compared to 21 days in highly polluted water bodies. | 1996 | 28769402 |
| recoverability of heat-injured bacillus spores by lysozyme and edta or alkaline thioglycollate. | the d95°c value of bacillus thuringiensis spores plated in the presence of lysozyme increased from 3.0 min to 3.6 min by post-treatment of heat-injured spores with 50mm edta. in the case of bacillus alvei and bacillus polymyxa spores d-values decreased from 4.9 to 4.3 min and from 4.7 to 4.1 min respectively. post-treatment of heat-injured spores treated with alkaline thioglycollate increased d95°c values of bacillus alvei from 4.2 to 5.3 min, b. thuringiensis 3.6 to 4.7 min, and bacillus polymy ... | 1996 | 24415421 |
| selection of rhizosphere-competent pseudomonas strains as biocontrol agents in tropical soils. | pseudomonas strains were isolated from the rhizosphere of maize grown in yellow-red latosol from rio de janeiro, brazil, to serve as a delivery system for heterologous genes and for risk assessment studies in tropical soils. selected strains were modified by insertion of the cryivb gene from bacillus thuringiensis and tested for pathogenicity gene expression against larvae of a susceptible model species, anopheles aquasalis. modified strains br8 and br12 showed similar survival performance to th ... | 1996 | 24415420 |
| production of thuringiensin from bacillus thuringiensis using a net-draft-tube, modified airlift reactor. | a net-draft-tube, modified airlift reactor and a stirred-tank reactor were used for thuringiensin production by bacillus thuringiensis subsp. darmstadiensis growing with various concentrations of molasses. the optimum concentration of molasses for thuringiensin production in both reactors was 15 g/l. there was a 6 h delay in sporulation in the modified airlift reactor compared with that in the stirred-tank reactor. thuringiensin yield in the modified airlift reactor (2.2 g/l) was consequently hi ... | 1996 | 24415084 |
| 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 |
| the heliothis virescens 170 kda aminopeptidase functions as "receptor a" by mediating specific bacillus thuringiensis cry1a delta-endotoxin binding and pore formation. | the relationship between bacillus thuringiensis cry1aa, cry1ab and cry1ac delta-endotoxin binding and pore formation was investigated using a purified 170 kda aminopeptidase n (apn) from heliothis virescens brush border membranes. aminopeptidases with molecular sizes of 110, 140 and 170 kda were eluted from a cry1ac toxin affinity column using n-acetylgalactosamine. the 140 kda aminopeptidase has a cross-reacting determinant typical of a cleaved glycosyl-phosphatidylinositol anchor. after mild b ... | 1997 | 9443374 |
| [sensitivity of larvae of the malaria mosquito anopheles messae with various inversion genotypes to the entomopathogenic bacteria bacillus thuringiensis israelensis as a function of dose]. | the influence of the entomopathogenic bacterium bacillus thuringiensis israelensis (bti) on the chromosomal composition of a natural population of fourth instar larvae of the malaria mosquito (anopheles messeae fall.) was investigated. the two doses used in the experiment yielded different death rates. a dose of 6.17 micrograms bti per 1 mg of host mass led to a death rate of 41.1 +/- 3.0%. the chromosomal composition of the population remained unchanged, but the proportion of xl11-2r11 females ... | 1997 | 9445817 |
| [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 |
| 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 |
| 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 |