Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| phylogenetic relationships of bacillus thuringiensis delta-endotoxin family proteins and their functional domains. | 1997 | 9139891 | |
| 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 |
| 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 |
| 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 |
| 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 |
| expression of a bacillus thuringiensis cryia(c) gene in transgenic peanut plants and its efficacy against lesser cornstalk borer. | the invasion of peanut (arachis hypogaea l.) pods and seeds by aflatoxin-forming species of aspergillus is linked to injury by the lesser cornstalk borer and frequently causes a severe reduction in crop quality. the lesser cornstalk borer is susceptible to the lepidopteran-active bacillus thuringiensis insecticidal crystal protein. we have introduced a codon-modified bacillus thuringiensis cryia(c) gene into peanut using microprojectile bombardment. the toxin-coding region of a bt cryia(c) gene ... | 1997 | 9090064 |
| biological control studies of soft and hard ticks in egypt. i. the effect of bacillus thuringiensis varieties on soft and hard ticks (ixodidae). | the potential activity of three varieties of bacillus thuringiensis (kurstaki, israeliensis, and thuringiensis) against the soft tick argas persicus and the hard tick hyalomma dromedarii was investigated. soft ticks succumbed within a period ranging from 36 h to 5 days and hard ticks died at between 48 h and 10 days posttreatment, depending on the dose. concentrations lethal to 50% of tick populations (lc50 values) indicated that dipel 2x (b. thuringiensis var. kurstaki) was the most potent, fol ... | 1997 | 9089714 |
| toxicity of an isolate of bacillus thuringiensis subspecies darmstadiensis to adults of the mexican fruit fly (diptera: (diptera:tephritidae) in the laboratory. | centrifugation pellets obtained from an isolate of bacillus thuringiensis subspecies darmstadiensis (guat 1) cultured from a guatemalan soil sample were found to be toxic to anastrepha ludens (loew) adults in the laboratory. we developed a bioassay diet that consisted of a mixture of the bacterium, a protein source, and sugar. a ph of 4.1 of the mixture was needed to obtain maximum adult mortality. one meal of the diet, which lasted from 30 s to 4 min, was enough to cause > 70% mortality of both ... | 1997 | 9071889 |
| release of ectoenzymes from small intestine brush border membranes of mice by phospholipases. | this study investigated ectoenzyme release from small intestine brush border membranes (duodenum and jejunum, preparation a; ileum, preparation b) of mice by the action of phosphatidylinositol-specific phospholipase c or glycosyl-phosphatidylinositol-specific phospholipase d. most of the alkaline phosphatase was solubilized from preparation a, but about 60% was released from preparation b. as for alkaline phosphodiesterase i activity, 15 and 10% were released from preparations a and b, respectiv ... | 1997 | 9058973 |
| a new tissue technique for evaluating effects of bacillus thuringiensis toxins on insect midgut epithelium. | epithelial tissue wholemounts were produced after enzymatic removal of basal lamina and connective tissue from midguts of trichoplusia ni larvae. wholemounts were nourished in artificial hemolymph and tissue viability was assessed for up to 24 hr using the vital dyes trypan blue, acridine orange (ao), propidium iodide (pi), and 4', 6-diamidino-2-phenylindole (dapi). peritrophic membrane synthesis and modification of bacillus thuringiensis cry1ac protoxin to active toxin confirmed some normal epi ... | 1997 | 9056459 |
| identification of a second transcriptional start site for the insecticidal protein gene cryiva of bacillus thuringiensis subsp. israelensis. | expression of cryiva, one of the insecticidal protein genes of b. thuringiensis subsp. israelensis, is regulated at the transcriptional level. the cryiva gene is specifically transcribed during the stationary phase of this bacterium. as shown in our previous report [yoshisue et al. (1993a)], the transcription from the -364 position of the cryiva gene is conducted by the major promoter p1 that is functional during middle stages of the stationary phase of b. thuringiensis. in the present study, we ... | 1997 | 9055823 |
| cloning of novel enterotoxin genes from bacillus cereus and bacillus thuringiensis. | a novel enterotoxin gene was cloned from bacillus cereus fm1, and its nucleotide sequence was determined. previously, a 45-kda protein causing characteristic enterotoxin symptoms in higher animals had been isolated (k. shinagawa, p. 181-193, in a. e. pohland et al., ed., microbial toxins in foods and feeds, 1990) from the same b. cereus strain, but no report of cloning of the enterotoxin gene has been published. in the present study, a specific antibody to the purified enterotoxin was produced a ... | 1997 | 9055420 |
| [thermodynamic analysis of domain organization of bacillus thuringiensis toxins]. | the structure of delta-endotoxins cryia(c) and cryiiia from bacillus thuringiensis was studied by differential scanning microcalorimerty. the analysis of molecular melting showed that the n- and c-terminal halves of the cryia(c) protoxin from b. thuringiensis subspecies kurstaki hd-73 are thermodynamically independent subunits, with the c-terminal fragment being denatured at a much lower temperature than the n-terminal fragment. the tertiary structure of the n-terminal fragment undergoes no chan ... | 1996 | 9054340 |
| one gene in diamondback moth confers resistance to four bacillus thuringiensis toxins. | environmentally benign insecticides derived from the soil bacterium bacillus thuringiensis (bt) are the most widely used biopesticides, but their success will be short-lived if pests quickly adapt to them. the risk of evolution of resistance by pests has increased, because transgenic crops producing insecticidal proteins from bt are being grown commercially. efforts to delay resistance with two or more bt toxins assume that independent mutations are required to counter each toxin. moreover, it g ... | 1997 | 9050831 |
| acute toxicity of selected pesticides to the estuarine shrimp leander tenuicornis (decapoda:palaemonidae). | the shrimp leander tenuicornis is abundant in southeastern queensland intertidal marsh pools and was chosen as an indicator species for toxicological studies with pesticides. acute toxicity to this crustacean of temephos and 3 pesticide compounds under evaluation for registration in australia (bacillus thuringiensis var. israelensis, s-methoprene, and pyriproxyfen) was tested in 96-h laboratory trials. temephos was the most toxic compound, with a median lethal concentration (lc50) of 0.01 ppm (0 ... | 1996 | 9046481 |
| ultralow volume application of bacillus thuringiensis ssp. israelensis for the control of mosquitoes. | evaluation of the effectiveness of bacillus thuringiensis ssp. israelensis (b.t.i.) against mosquito larvae dispersed by ultralow volume (ulv) spraying was conducted in simulated field trials. effectiveness was measured using 3 different indicators: larval mortality, colony-forming unit enumeration, and droplet analysis. b.t.i. was dispersed with a ulv generator using 2 different flow rates: 0.3 and 0.5 liter/min on 2 different days. based on the results of this study, it can be concluded that a ... | 1996 | 9046471 |
| raising activity of bacillus thuringiensis var. israelensis against anopheles stephensi larvae by encapsulation in tetrahymena pyriformis (hymenostomatida:tetrahymenidae). | toxicity of bacillus thuringiensis var israelensis (b.t.i.) against surface-feeding mosquito larvae of anopheles stephensi was enhanced by encapsulation in the protozoan tetrahymena pyriformis. in the laboratory, larvae died about 8 times faster when exposed to protozoan cells filled with b.t.i. than when exposed to the same concentrations of b.t.i. alone. best larvicidal activities were achieved with ratios of 1:200-1:500 t. pyriformis cells to b.t.i. spores. the concentration of b.t.i. needed ... | 1996 | 9046467 |
| distribution and characterization of bacillus thuringiensis in the environment of the olive in greece. | the distribution of bacillus thuringiensis in greece, was studied and the presence of this organism was found in 11.2% of the samples collected. the characterization of the different isolates was based on their whole-cell protein profiles. some of the isolates form quite unusual parasporal inclusions. | 1997 | 9037671 |
| transgenic plants: an emerging approach to pest control. | insect pests are a major cause of damage to the world's commercially important agricultural crops. current strategies aimed at reducing crop losses rely primarily on chemical pesticides. alternatively transgenic crops with intrinsic pest resistance offer a promising alternative and continue to be developed. the first generation of insect-resistant transgenic plants are based on insecticidal proteins from bacillus thuringiensis (bt). a second generation of insect-resistant plants under developmen ... | 1997 | 9035137 |
| chair of gmo panel resigns over maize. | 1997 | 9034175 | |
| a 16s rrna gene oligonucleotide probe for identification of bacillus thuringiensis isolates from sheep fleece. | larvae of the australian sheep blowfly lucilia cuprina are susceptible to some strains of bacillus thuringiensis, including some isolates from sheep fleeces from south australia and western australia. larvicidal strains of b. thuringiensis include var. thuringiensis, tolworthi, darmstadiensis, morrisoni, and toumanoffi. as part of an ecological study, a large number of b. thuringiensis fleece isolates from untreated sheep and sheep previously treated with larvicidal b. thuringiensis were screene ... | 1997 | 9028924 |
| palatability of leaf material contaminated with bacillus thuringiensis var. kurstaki, to hydatophylax argus, a detritivorous aquatic insect. | 1996 | 9026162 | |
| a recombinase-mediated system for elimination of antibiotic resistance gene markers from genetically engineered bacillus thuringiensis strains. | a tnpi-mediated site-specific recombination system to construct genetically modified bacillus thuringiensis strains was developed. recombinant b. thuringiensis strains from which antibiotic resistance genes can be selectively eliminated were obtained in vivo with a new vector based on the specific resolution site of transposon tn4430. for example, a cryic gene, whose product is active against spodoptera littoralis, was introduced into b. thuringiensis kto harboring a cryia(c) gene active against ... | 1997 | 9023958 |
| the bacillus thuringiensis vegetative insecticidal protein vip3a lyses midgut epithelium cells of susceptible insects. | the vip3a protein is a member of a newly discovered class of vegetative insecticidal proteins with activity against a broad spectrum of lepidopteran insects. histopathological observations indicate that vip3a ingestion by susceptible insects such as the black cutworm (agrotis ipsilon) and fall armyworm (spodoptera frugiperda) causes gut paralysis at concentrations as low as 4 ng/cm2 of diet and complete lysis of gut epithelium cells resulting in larval death at concentrations above 40 ng/cm2. th ... | 1997 | 9023933 |
| identification of a gene for cyt1a-like hemolysin from bacillus thuringiensis subsp. medellin and expression in a crystal-negative b. thuringiensis strain. | a gene designated cyt1ab1, encoding a 27,490-da protein, was isolated from bacillus thuringiensis subsp. medellin (h30 serotype) by using an oligonucleotide probe corresponding to the cyt1aa1 gene. the sequence of the cyt1ab1 protein, as deduced from the sequence of the cyt1ab1 gene, was 86% identical to that of the cyt1aa1 protein and 32% identical to that of the cyt2aa1 protein from b. thuringiensis subsp. kyushuensis. the cyt1ab1 gene was flanked upstream by a p21 gene, in the same orientatio ... | 1997 | 9023925 |
| modulation of the cleavage of glycosylphosphatidylinositol-anchored proteins by specific bacterial phospholipases. | many enzymes are tethered to the extracellular face of the plasma membrane by a glycosylphosphatidylinositol (gpi) anchor. these proteins can be released in soluble form by the action of gpi-specific phospholipase. little is currently known about the factors modulating this release. we investigated the effects of several experimental variables on the cleavage of the gpi-anchored proteins 5'nucleotidase, acetylcholinesterase, and alkaline phosphatase by phospholipases from bacillus thuringiensis ... | 1996 | 9018379 |
| [the use of electro-optic method for control of biological preparations]. | 1996 | 9011866 | |
| [a comparison of the antibacterial activity of the parasporal bodies of different bacilli]. | solutions of the parasporal bodies of bacillus sphaericus, b. laterosporus, and several b. thuringiensis subspecies display antibacterial activity showing the potential of membranotropic action of the body proteins. comparison of the antibiotic effect of various delta-endotoxins of b. thuringiensis made it possible to identify highly active unique proteins. this approach forms the basis of goal-directed search for organisms sensitive to polypeptides of various bodies. it has already been establi ... | 1996 | 9004895 |
| cloning and expression of a bacillus thuringiensis (l1-2) gene encoding a crystal protein active against glossina morsitans morsitans and chilo partellus. | a local isolate of bacillus thuringiensis,designated l1-2, that is toxic to chilo partellus was found to be toxic to the adult tsetse fly, glossina morsitans morsitans. the delta-endotoxin crystals derived from the isolate gave a major protein band with a molecular weight of mr 130,000-140,000 on denaturing polyacrylamide gel electrophoresis. the sequence of the cloned gene was found to be similar to that of the b. thuringiensis subsp. kurstaki hd-73 cryia(c) gene, having one amino acid differen ... | 1997 | 9003589 |
| mapping of the entomocidal fragment of spodoptera-specific bacillus thuringiensis toxin cryic. | insecticidal cryi protoxins of bacillus thuringiensis are activated by proteolysis in the midgut of insects. a conservation of proteolytic cleavage sites in the cryi proteins facilitates the expression of active toxins in transgenic plants to obtain protection from various insects. however, the engineering of cryic toxins has, thus far, failed to yield applicable resistance to armyworms of spodoptera species representing common insect pests worldwide. to improve the production of recombinant cry ... | 1996 | 9003281 |
| stereocontrolled syntheses of water-soluble inhibitors of phosphatidylinositol-specific phospholipase c: inhibition enhanced by an interface. | three inositol 1,2-(cyclic)-phosphate analogs, inositol cyclic phosphonates with different stereochemistry at the c-2 position of the inositol ring, have been synthesized as water-soluble inhibitors of phosphatidylinositol-specific phospholipase c (pi-plc). their inhibition of both phosphotransferase and cyclic phosphodiesterase activities has been studied in the absence and presence of an interface. key results include the following. (i) only the analog with the same stereochemistry at the c-2 ... | 1997 | 9003188 |
| activation of phosphatidylinositol-specific phospholipase c toward inositol 1,2-(cyclic)-phosphate. | phosphatidylinositol-specific phospholipase c (pi-plc) from bacillus thuringiensis catalyzes the hydrolysis of phosphatidylinositol (pi) in discrete steps: (i) an intramolecular phosphotransferase reaction to form inositol 1,2-(cyclic)-phosphate (cip), followed by (ii) a cyclic phosphodiesterase activity that converts cip to inositol 1-phosphate. water-soluble cip was used as the substrate to study the cyclic phosphodiesterase activity and interfacial behavior of pi-plc. different detergent mice ... | 1997 | 9003187 |
| discrimination between bacillus cereus and bacillus thuringiensis using specific dna probes based on variable regions of 16s rrna. | identification of bacillus cereus and differentiation between b. cereus and closely related species are currently based on biochemical tests. the main problem is to discriminate between b. cereus and b. thuringiensis. sequencing part of the 16s rrna showed that several b. cereus isolates present in food and involved in food poisoning, confirmed according to the classical biochemical methods, were in fact b. thuringiensis. as this organism is the most commonly used microbial insecticide worldwide ... | 1997 | 8997705 |
| [sensitivity of dissociation variants of micrococcus luteus to the action of delta-endotoxins of bacillus thuringiensis]. | endotoxins of bacillus thuringiensis subsp. tenebrionis produced an antibiotic effect on three out of the four species of micrococci tested, showing an activity of 10-23 units/mg, comparable with that of bacitracin. the r variants of micrococcus luteus were more than twice as resistant to the action of delta-endotoxins as cells of the s and m types. enhanced growth of the tested microorganisms at concentrations of antibiotics large enough to inhibit the growth of the s and m variants, but insuff ... | 1996 | 8992244 |
| identification of flagellar (h) antigenic subfactors in bacillus thuringiensis h serotypes 10, 18 and 24 isolated in japan. | a total of 95 bacillus thuringiensis strains isolated from japan and belonging to h serotypes 10, 18 and 24, were examined for their h antigenic subfactors. of 84 h serotype 10 isolates, 83 were identified as the h serotype 10a: 10b (serovar darmstadiensis) and only one isolate was assigned to the h serotype 10a: 10c (serovar londrina). among five isolates belonging to the h serotype 18, three were allocated to the h serotype 18a: 18b (serovar kumamotoensis), while two isolates did not react to ... | 1996 | 8987706 |
| characterization of novel non-toxic bacillus thuringiensis isolates from korea. | four bacillus thuringiensis isolates from soil samples produced parasporal inclusions which were non-toxic to insects. the isolates were named b. thuringiensis ntb-1, ntb-2, ntb-3 and ntb-4. the parasporal inclusions were shown to be ovoid by phase contrast and scanning electron microscopy. the serotypes of the four isolates were determined by agglutination using 33 antisera; ntb-1 and ntb-4 seemed to be subsp. israelensis, and ntb-2 seemed to be subsp. pondicheriensis. ntb-3 did not react with ... | 1996 | 8987698 |
| expression of 135-kda insecticidal protein gene from bacillus thuringiensis in the yeast saccharomyces cerevisiae. | bacillus thuringiensis subsp. aizawai produces 130-kda and 135-kda (cryia(a)) insecticidal proteins. when saccharomyces cerevisiae was transformed by the vector carrying a cryia(a) gene, the gene expression could not be observed. when the 5'-upstream region from the initiation codon was removed using a synthetic oligonucleotide, the cryia(a) protein was successfully synthesized in yeast. the yeast extract containing cryia(a) protein had insecticidal activity against plutella xylostella larvae. | 1996 | 8987598 |
| a synthetic cryic gene, encoding a bacillus thuringiensis delta-endotoxin, confers spodoptera resistance in alfalfa and tobacco. | spodoptera species, representing widespread polyphagous insect pests, are resistant to bacillus thuringiensis delta-endotoxins used thus far as insecticides in transgenic plants. here we describe the chemical synthesis of a cryic gene by a novel template directed ligation-pcr method. this simple and economical method to construct large synthetic genes can be used when routine resynthesis of genes is required. chemically phosphorylated adjacent oligonucleotides of the gene to be synthesized are a ... | 1996 | 8986755 |
| isolation of cry1ab protein mutants of bacillus thuringiensis by a highly efficient pcr site-directed mutagenesis system. | a site-directed mutagenesis method was designed and used to create cry1ab mutant proteins in two of the five highly conserved blocks present in the cry protein family. region 1 comprises the central alpha-helix 5 of domain i and has been implicated in the pore formation activity of the toxin. substitution of arginine by serine at position 173 (r173s) affects neither structural integrity nor toxicity. region 2 comprises the major part of the domain i/domain ii interface, characterized by the pres ... | 1996 | 8978087 |
| effects of bacillus thuringiensis subsp. israelensis (b.t.i.) applications on invertebrates from two streams on prince edward island. | 1997 | 8975807 | |
| inactivation of the pete gene for plastocyanin lowers photosynthetic capacity and exacerbates chilling-induced photoinhibition in the cyanobacterium synechococcus. | we describe the identification and expression of a pete gene in synechococcus sp. pcc 7942, a cyanobacterium previously thought to lack plastocyanin. the pete gene is a 420-bp open reading frame that encodes a protein 70 to 75% similar to plastocyanins from other cyanobacteria. synechococcus possesses a single genomic copy of pete located immediately upstream of the clpb gene. it is transcribed as a single mrna (550 bases) and, in contrast to most other photobionts, the level of pete expression ... | 1996 | 8972599 |
| a carbon-limited medium for growth and sporulation of bacillus thuringiensis var. kurstaki. | a culture medium for batch production of d-endotoxin by bacillus thuringiensis (b., t.) has been modified. through batch and continuous cultivation studies, the original medium was diagnosed to be limited in organic nitrogen. corn steep liquor was found to be an excellent source for the organic nitrogen and its addition resulted in a carbon limited medium and in a significant increase in the amount of spore-toxin complex formed in shake flasks. results of bioassay, conducted on trichoplusia ni, ... | 1995 | 8972135 |
| luminal proteinases from plodia interpunctella and the hydrolysis of bacillus thuringiensis cryia(c) protoxin. | the ability of proteinases in gut extracts of the indianmeal moth, plodia interpunctella, to hydrolyze bacillus thuringiensis (bt) protoxin, casein, and rho-nitroanilide substrates was investigated. a polyclonal antiserum to protoxin cryia(c) was used in western blots to demonstrate slower protoxin processing by gut enzymes from bt subspecies entomocidus-resistant larvae than enzymes from susceptible or kurstaki-resistant strains. enzymes from all three strains hydrolyzed n-alpha-benzoyl-l-argin ... | 1996 | 8969468 |
| protein engineering of bacillus thuringiensis delta-endotoxin: mutations at domain ii of cryiab enhance receptor affinity and toxicity toward gypsy moth larvae. | substitutions or deletions of domain ii loop residues of bacillus thuringiensis delta-endotoxin cryiab were constructed using site-directed mutagenesis techniques to investigate their functional roles in receptor binding and toxicity toward gypsy moth (lymantria dispar). substitution of loop 2 residue n372 with ala or gly (n372a, n372g) increased the toxicity against gypsy moth larvae 8-fold and enhanced binding affinity to gypsy moth midgut brush border membrane vesicles (bbmv) approximately 4- ... | 1996 | 8962052 |
| expression of chitinase-encoding genes from aeromonas hydrophila and pseudomonas maltophilia in bacillus thuringiensis subsp. israelensis. | fifty isolates of chitinase (cts)-producing bacteria were collected from soil samples and tested for their ability to degrade chitin using colloidal chitin agar as the primary plating medium. the results indicated that three isolates could degrade chitin at high ph. further studies also demonstrated that crude cts preparations from bacillus circulans (bc) no. 4.1 could enhance the toxicity of bacillus thuringiensis subsp. kurstaki (bt-k) toward diamondback moth larvae. thus, it might be useful t ... | 1996 | 8955637 |
| probing the mechanism of action of bacillus thuringiensis insecticidal proteins by site-directed mutagenesis--a minireview. | the current model of the mechanism of action of several bacillus thuringiensis insecticidal crystal proteins (cry) is reviewed and tested by site-directed mutagenesis experiments. amino acid (aa) residues were substituted in each of the three domains of cry toxins and the effects on toxin stability, binding to receptors, irreversible insertion into the membrane, and ion channel activity were examined. mutant proteins with aa altered on the putative membrane-proximal surface of domain i are affec ... | 1996 | 8955636 |
| mobilization of "nonmobilizable" plasmids by the aggregation-mediated conjugation system of bacillus thuringiensis. | the aggregation-mediated conjugation system of bacillus thuringiensis subsp, israelensis (bti), encoded by the 200-kb plasmid pxo16, is highly potent in transferring itself and efficient in mobilizing other nonconjugative plasmids. in the present study we have analyzed the native bacillus cereus plasmid pbc16. this plasmid has previously been shown to harbor a mob gene (orf beta) and a locus functioning as an orit site in plasmid pls20-mediated conjugation in bacillus subtilis. however, in the c ... | 1996 | 8954879 |
| restricted ingestion of bacteria by fire ants | fire ant queens and workers from colonies fed to repletion on serratia marcescens, bacillus thuringiensis, or bacillus sphaericus were aseptically dissected, and homogenates of their thoracic and gastric guts were plated on appropriate media to determine whether bacteria were ingested. all three species of bacteria were effectively excluded from the gut of both queens and workers. a small, slow-growing, gram-negative bacterium, noted in some of the test queens, was subsequently isolated from the ... | 1996 | 8954815 |
| involvement of two amino acid residues in the loop region of bacillus thuringiensis cry1ab toxin in toxicity and binding to lymantria dispar. | two amino acids, gly and ser, at positions 282 and 283 in the loop region of domain ii of cry1ab2 toxin are substituted with ala and leu in the cry1ab9-033 toxin. cry1ab2 exhibited about a 10-fold increase in toxicity and a 9-fold increase in binding affinity to lymantria dispar compared to cry1ab9-033. however, these toxins showed similar toxicity and binding affinity to manduca sexta and spodoptera exigua. heterologous competition assays and brush border membrane vesicle (bbmv) ligand blotting ... | 1996 | 8954096 |
| engineering bacillus thuringiensis bioinsecticides with an indigenous site-specific recombination system. | the cry genes of bacillus thuringiensis encode a diverse group of crystal-forming proteins that exhibit insecticidal activity, particularly against the larvae of lepidopteran, coleopteran, and dipteran insects. the efficacy of b. thuringiensis-based biopesticides may be improved through the genetic manipulation of these genes. a gene transfer system has been developed for the introduction and maintenance of cloned insecticidal cry genes on small plasmids in b. thuringiensis. this vector system c ... | 1996 | 8953709 |
| high-level expression of bacillus thuringiensis phosphatidylinositol-specific phospholipase c by the bacillus brevis host-vector system. | we succeeded in hyperproduction of bacillus thuringiensis phosphatidylinositol-specific phospholipase c (piplc), using a bacillus brevis 47 expression system. the recombinant b. thuringiensis piplc was expressed under the control of the middle wall protein gene promoter in b. brevis expression vector pnu211. a large amount of recombinant piplc (0.4 g per liter culture) was secreted into the medium as a mature enzyme, and the enzymatic properties of purified recombinant piplc were similar to thos ... | 1996 | 8950642 |
| a micromethod for serotyping bacillus thuringiensis. | serotyping of bacillus thuringiensis is possible using 96-well microplates instead of tubes. the advantages are a reduction on the incubation time from 120 to 75 min and the amounts of antisera and bacterial suspensions needed 10-fold. | 1996 | 8934782 |
| regulatory sequences of two flagellin genes in bacillus thuringiensis subsp. alesti. | two highly homologous flagellin genes, flaa and flab, are expressed in bacillus thuringiensis subsp. alesti. both genes were found to be transcribed during vegetative growth. after the onset of sporulation, transcripts could not be detected. both flaa and flab were found to be transcribed from sigma70-like promoters. in addition, the 3'-terminal half of flaa was cloned and sequenced, completing the sequence of flaa. | 1996 | 8932705 |
| interactions of bacillus thuringiensis crystal proteins with the midgut epithelial cells of spodoptera frugiperda (lepidoptera: noctuidae). | binding of different bacillus thuringiensis insecticidal crystal proteins (icps) to the midgut epithelium of spodoptera frugiperda larvae was characterized by binding experiments with midgut tissue sections and isolated brush border membrane vesicles. our results show that icps interact with the microvilli of epithelial cells of s. frugiperda in two different ways. the first is typical of highly toxic proteins (like cryic and cryid); this interaction is saturable and specific. in contrast, some ... | 1996 | 8931361 |
| identification of novel cry-type genes from bacillus thuringiensis strains on the basis of restriction fragment length polymorphism of the pcr-amplified dna. | two pairs of universal oligonucleotide primers were designed to probe the most conserved regions of all known cryi-type gene sequences so that the amplified pcr fragments of the dna template from bacillus thuringiensis strains may contain all possible cryi-type gene sequences. the restriction fragment length polymorphism (rflp) patterns of the pcr-amplified fragments revealed that 14 distinct cry-type genes have been identified from 20 b. thuringiensis strains. those cry-type genes included cryi ... | 1996 | 8919799 |
| altered binding of the cry1ac toxin to larval membranes but not to the toxin-binding protein in plodia interpunctella selected for resistance to different bacillus thuringiensis isolates. | immunoblotting and cytochemical procedures were used to determine whether toxin binding was altered in strains of the indianmeal moth, plodia interpunctella, selected for resistance to various strains of bacillus thuringiensis. each of these b. thuringiensis subspecies produces a mixture of protoxins, primarily cry1 types, and the greatest insect resistance is to the cry1a protoxins. in several cases, however, there was also resistance to toxins not present in the b. thuringiensis strains used f ... | 1996 | 8900008 |
| effects of three larvicides on the production of aedes albopictus based on removal of pupal exuviae. | the production of adult aedes albopictus from tires in northcentral florida was monitored for 169 days by the daily removal of pupal exuviae. more than twice as many adults emerged from tires located in the shade (1.74 adults/tire/day) compared to tires in the sun (0.64 adults/tire/day). the effect of 3 larvicides on the production of adult ae albopictus was evaluated. the fungal pathogen lagenidium giganteum was ineffective. a liquid formulation of bacillus thuringiensis israelensis (acrobe) pr ... | 1996 | 8887234 |
| investigation of bacterial resistance to hatchery disinfectants. | three commercial chicken hatcheries were sampled for environmental bacteria. isolated bacteria were tested for resistance to commercial preparations of quaternary ammonia, phenolic, and glutaraldehyde liquid disinfectants. bacterial isolates were exposed to several disinfectant dilutions bracketing the dilutions recommended by the manufacturer for 5-, 10-, and 15-min exposure periods before subculturing to broth medium. approximately 8% of the isolates from two of three hatcheries were resistant ... | 1996 | 8883778 |
| studies on the transfer techniques of three maize genes. | maize transformation has been carried out through microprojectile bombardment, ultrasonication in a dna buffer, and ovary-injection with a self-made microinjector. the plasmid pb48.415, which carries a 3'-truncated bt-toxin protein gene and a hygromycin phosphotransferase (hpt) gene, was used in the transformation. transgenic maize plants were obtained from immature embryos and embryogenic calli bombarded with a particle gun, embryogenic calli ultrasonicated under different conditions of ovaries ... | 1996 | 8877115 |
| mechanism and structure based inhibitors of phospholipase c enzymes. | pi-specific plc enzymes are a key component of phosphatidylinositol-mediated signaling pathways since the hydrophobic product, diacylglycerol, activates protein kinase c and the water-soluble product, inositol trisphosphate, is involved in ca2+ mobilization. nonspecific, or pc-plc, enzymes can generate diacylglycerol without ca2+ mobilization. a series of inhibitors, both lipophilic and water-soluble, have been synthesized to target each of these two classes of plc enzymes. design of the inhibit ... | 1996 | 8869740 |
| insecticidal activity of the protein encoded by the cryv gene of bacillus thuringiensis kurstaki ina-02. | a new host specificity was discovered with the insecticidal protein encoded by the cryv gene. the cryv gene was cloned from the bacillus thuringiensis kurstaki ina-02 strain, which was selected among a number of b. thuringiensis isolates because of its high activity against spodoptera litura. analyses by polymerase chain reaction (pcr) revealed that ina-02 contained the cryia(a) and cryv genes. since no spodoptera activity was observed with b. thuringiensis sotto, which contained only cryia(a), ... | 1996 | 8867460 |
| the insecticidal proteins of bacillus thuringiensis. | 1996 | 8865583 | |
| enterotoxin-producing strains of bacillus thuringiensis isolated from food. | strains of bacillus thuringiensis were isolated from various food items (pasta, pitta bread and milk) and were found to belong to either h-serotype kurstaki or neoleonensis. the strains were bioassayed against pieris brassicae and insecticidal activity of strains was found to correspond to the presence of the cry1a-gene. all strains, except one, were found to express cytotoxic effects on vero cells as an indicator of enterotoxin activity. further, the b. thuringiensis strains hd-1 (serotype kurs ... | 1996 | 8862018 |
| cell targeting of a pore-forming toxin, cyta delta-endotoxin from bacillus thuringiensis subspecies israelensis, by conjugating cyta with anti-thy 1 monoclonal antibodies and insulin. | the cytolytic protein toxin cyta was linked to two monoclonal antibodies (mab) directed against the mouse or the rat thy 1 antigen. the purified cyta-mab conjugates were not toxic to either target or nontarget cells. the conjugates did bind specifically to target cells since they agglutinated the target cells but not nontarget cells. when the conjugates were treated with dithiothreitol, the released cyta was toxic to all cells tested. these results suggested that the attachment of cyta to a mole ... | 1996 | 8853459 |
| [comparative study of 3 heterologous expression systems for obtaining recombinant bacillus thuringiensis delta-endotoxins]. | cryia(b) and cryia(c) genes encoding active fragments of bacillus thuringiensis delta-endotoxins were cloned downstream of the pr and pt7 promoters from the lambda and t7 bacteriophages, respectively. cryia(b) gene was also fused with the gene encoding protein a from staphylococcus aureus cloned under the control of the pr promoter. there were no remarkable differences in the expression levels of the cloned genes in e. coli, but the western blot analysis allowed distinct protein quality for the ... | 1995 | 8850342 |
| the beta-prism: a new folding motif. | a new protein fold with internal symmetry has been observed in two proteins: vitelline membrane outer layer protein i (vmo-i) and delta-endotoxin. despite lacking any discernible sequence similarity, both proteins have similar three-dimensional structures as well as a carbohydrate-binding site in the top region of the common fold. | 1996 | 8848836 |
| development of an immunoradiometric assay for quantitative determination of cryla(b) protein in transgenic sugarcane plants. | an immunoradiometric assay (irma) system was performed to quantify the recombinant cryla(b) protein produced by transgenic sugarcane lines. the method allowed detection of 0.1-1 ng cryla(b) per 25 micrograms of soluble protein in leaf extracts from plants transformed with an expression vector containing a truncated version of the cryla(b) gene from bacillus thuringiensis. the technique was based upon the use of radioiodinated immunopurified antibodies specific to natural cryla proteins in a one- ... | 1996 | 8841441 |
| synergistic activity of a bacillus thuringiensis delta-endotoxin and a bacterial endochitinase against spodoptera littoralis larvae. | in an attempt to increase the insecticidal effect of the delta-endotoxin crystal protein cryic on the relatively cry-insensitive larvae of spodoptera littoralis, a combination of cryic and endochitinase was used. cryic comprising the first 756 amino acids from bacillus thuringiensis k26-21 and endochitinase chiaii encoded by serratia marcescens were separately produced in escherichia coli carrying the genes in overexpression vectors. the endochitinase on its own, even at very low concentrations ... | 1996 | 8837413 |
| introduction and expression of an anti-dipteran toxin gene from b. thuringiensis in nodulating rhizobia. | rhizobium-based inoculants are widely used in leguminous crops. improved strains with dual functions (i.e, nitrogen fixing and insecticidal) could be successfully applied to organic pest management. these could also be used as seed protectants, reducing the use of chemical insecticides. the cryivb gene from b. thuringiensis israelensis coding for an anti-dipteran toxin was used as a model for expression. a highly stable plasmid vector (ptr101) was chosen in order to carry out nodulation experime ... | 1996 | 8832105 |
| use of stream width for determining the dosage rates of bacillus thuringiensis var. israelensis for larval black fly (diptera: simuliidae) control. | data from several operational black fly abatement programs using bacillus thuringiensis var. israelensis (b.t.i.) in new york state's adirondack mountains were analyzed to determine what the concentration of formulation in the stream might have been if application rates were determined by a stream's width rather than its discharge. there was a high correlation (magnitude of r = 0.87) between discharge and width measured at 315 treatment sites. had the applications been based upon the stream widt ... | 1996 | 8827611 |
| cross-resistance to bacillus sphaericus strains in culex quinquefasciatus. | laboratory and field-collected strains of culex quinquefasciatus that were selected with bacillus sphaericus strain 2362 in the laboratory for about 100 generations and attained 37- and 31-fold resistance, respectively, did not show marked cross-resistance to bacillus thuringiensis spp. israelensis; only 2-3-fold tolerance was noted. however, they showed significant levels of cross-resistance to strains 1593 (6-22-fold) and 2297 (4-12-fold) of b. sphaericus. possible mechanisms and management im ... | 1996 | 8827600 |
| community based dengue control in columbia: people's knowledge and practice and the potential contribution of the biological larvicide bti (bacillus thuringiensis israelensis). | a study on dengue control was undertaken in a poor urban area in cúcuta, colombia. the first objective was to describe people's knowledge, attitudes and practices regarding dengue fever, the transmission of the disease and possible preventive measures. the second objective was to analyse the infestation of the community with aedes aegypti larvae, and the third objective to test the efficacy of bti (bacillus thuringiensis israelensis) with respect to the level and duration of reduction of ae. aeg ... | 1995 | 8826104 |
| efficacy of ground ultra-low volume larvicidal treatments using temephos and bacillus thuringiensis var. israelensis against culex pipiens larvae. | spray drift determinations of truck-mounted ulv applications of temephos and bacillus thuringiensis var. israelensis (b.t.i.) in simulated field trials were conducted in the baix llobregat area near barcelona, spain, using larval culex pipiens as bioindicators. a 50:50 temephos:oil mixture applied at 350 ml/min, while traveling 9 kph, resulted in 100% control of larvae 10-50 m from the point of application (with the exception of 82% mortality at 30 m); control decreased rapidly to 50% at 55 m. m ... | 1995 | 8825518 |
| evaluation of entomopathogenic bacteria against aedes polynesiensis, the vector of lymphatic filariasis in french polynesia. | thirteen strains among 3 species of entomopathogenic bacteria were tested against 3 medically important mosquito species in french polynesia. two strains of bacillus thuringiensis were highly toxic to aedes polynesiensis, aedes aegypti, and culex quinquefasciatus. six of 7 strains of bacillus sphaericus tested were highly toxic to cx. quinquefasciatus but not to the aedes spp. clostridium bifermentans serovar. malaysia was more toxic to ae. polynesiensis than to the other 2 species. entomopathog ... | 1995 | 8825516 |
| a new serovar of bacillus thuringiensis possessing 28a28c flagellar antigenic structure: bacillus thuringiensis serovar jegathesan, selectively toxic against mosquito larvae. | a novel bacillus thuringiensis strain highly toxic to mosquitoes was isolated from soil samples in malaysia. this strain was shown to display a new subfraction of the h-28 flagellar antigen determining a new serovar h28a28c, which was designated serovar jegathesan. bioassays indicated that culex quinquefasciatus larvae are the most susceptible to this new isolate, whereas toxicity to anopheles maculatus and aedes aegypti larvae was 10 times lower. the potency of this new serotype is also compara ... | 1995 | 8825511 |
| field trials with methoprene, temephos, and bacillus thuringiensis serovar israelensis for the control of larval culiseta melanura. | in 1992, altosid (methoprene) pellets, abate (temephos) 5 cg, and bactimos (bacillus thuringiensis serovar israelensis) granules were applied aerially to small field plots within a culiseta breeding swamp. aspects measured included the deposition and diffusion of larvicides into larval crypts and effects on larval culiseta melanura and nontarget aquatic organisms. formulations were deposited at approximately 50% of application rates. the presence of methoprene in 8 crypt water samples indicated ... | 1995 | 8825501 |
| the aggregation-mediated conjugation system of bacillus thuringiensis subsp. israelensis: host range and kinetics of transfer. | the aggregation-mediated conjugation system in bacillus thuringiensis subsp. israelensis encoded on the plasmid pxo16 is characterized by the formation of aggregates when agr+ and agr- cells are socialized in exponential growth. using the aggregation phenotypes, we have identified potential recipients of the aggregation-plasmid pxo16 among bacillus cereus, bacillus subtilis, bacillus megaterium, bacillus sphaericus, and 24 subspecies of b. thuringiensis. we found 14 agr- strains, i.e., potential ... | 1996 | 8824168 |
| genetic transformation, recovery, and characterization of fertile soybean transgenic for a synthetic bacillus thuringiensis cryiac gene. | somatic embryos of jack, a glycine max (l.) merrill cultivar, were transformed using microprojectile bombardment with a synthetic bacillus thuringiensis insecticidal crystal protein gene (bt cryiac) driven by the 35s promoter and linked to the hph gene. approximately 10 g of tissue was bombarded, and three transgenic lines were selected on hygromycin-containing media and converted into plants. the recovered lines contained the hph gene, but the bt gene was lost in one line. the plasmid was rearr ... | 1996 | 8819322 |
| construction of new insecticidal bacillus thuringiensis recombinant strains by using the sporulation non-dependent expression system of cryiiia and a site specific recombination vector. | bacillus thuringiensis (bt) delta-endotoxins are safe biological insecticidal proteins whose usefulness has long been recognized. the first commercialized bt insecticidal formulations were composed of spore-crystal preparations derived from wild-type strains. these products generally have a limited insecticidal host range and several genetically modified strains have, therefore, been constructed using transformation procedures. however, addition of a new delta-endotoxin gene to strains already h ... | 1996 | 8818275 |
| larvicidal activity of bacillus thuringiensis natural isolates; indigenous to japan, against two nematoceran insect pests occurring in urban sewage environments. | a total of 1449 bacillus thuringiensis strains, indigenous to japan, were screened for larvicidal activity against two nematoceran insect pests, the mosquito, culex pipiens molestus (culicidae), and the moth-fly, telmatoscopus albipunctatus (psychodidae). mosquito specific strains were abundant in h serotypes 3abc (serovar kurstaki), 3ade (fukuokaensis), 4ac (kenyae), 7 (aizawai), 11ac (kyushuensis) and 29 (amagiensis), while moth-fly specific strains were predominantly found in h serotype 17 (t ... | 1996 | 8817917 |
| digestion of delta-endotoxin by gut proteases may explain reduced sensitivity of advanced instar larvae of spodoptera littoralis to cryic. | the present study describes the correlation between gut protease activity of lepidopteran larvae of different instars, the inactivation of bacillus thuringiensis delta-endotoxins in crystalline and noncrystalline forms, and the reduced susceptibility of advanced larval instars of spodoptera littoralis to the toxin. the original assembly of delta-endotoxins in a crystal structure is essential for causing efficient larval mortality. denaturation and renaturation (d/r) of delta-endotoxin crystals i ... | 1996 | 8814783 |
| functional comparison of conjugative transposons tn916 and tn925. | during interspecies matings between bacillus subtilis and bacillus thuringiensis subsp. israelensis, transfer of conjugative transposon tn916 was detected at a frequency of 1.1 x 10(-4) transconjugants per donor. tn916-dependent transfer of plasmids pc194 and pe194 was detected at frequencies of 1.4 x 10(-5) and 3.2 x 10(-7) transconjugants per donor, respectively. similar frequencies were obtained during parallel matings with otherwise isogenic strains that contain tn925 instead of tn916. tn916 ... | 1996 | 8812783 |
| evaluation of bacillus thuringiensis and bacillus sphaericus strains from chinese soils toxic to mosquito larvae | during our research to isolate and screen microbial agents, eight bacillus thuringiensis isolates and five bacillus sphaericus isolates were shown to have high toxicity to mosquito larvae. comparing the lc50 values, four b. sphaericus isolates with lc50 values ranging from 0.50 to 1.47 ng/ml were about two to six times more toxic than strain 1593 (lc50 3.00 ng/ml) against larvae of culex quinquefasciatus. four b. thuringiensis isolates (lc50 values ranging from 3.80 to 7.54 ng/ml) and four b. sp ... | 1996 | 8812574 |
| the effect of bacillus thuringiensis m-exotoxin on trematode cercariae | the effect of bacillus thuringiensis israelensis eluate containing water-soluble exotoxin (m-exotoxin) was observed by its use on cercariae of seven trematode species. to the most sensitive species to the toxic effect of the mentioned toxin belonged schistosome furcocercariae (human species schistosoma mansoni and avian parasite trichobilharzia szidati). under the influence of the toxin, surface syncytial structure (tegument) was separated from underlying tissues, with subsequent disintegration ... | 1996 | 8812565 |
| mutations at domain ii, loop 3, of bacillus thuringiensis cryiaa and cryiab delta-endotoxins suggest loop 3 is involved in initial binding to lepidopteran midguts. | alanine substitutions of loop 3 residues, 438sgfsns443, of cryiab toxin were constructed to study the functional role of these residues in receptor binding and toxicity to manduca sexta and heliothis virescens. experiments with trypsin and insect gut juice enzyme digestions of mutant toxins showed that these mutations did not produce any gross structural changes to the toxin molecule. bioassay data showed that mutant g439a (alanine substitution of residue gly439) and f440a significantly reduced ... | 1996 | 8810282 |
| effect of inactivation by sunlight on the larvicidal activities of mosquitocidal bacillus thuringiensis h-14 isolates from nigerian soils. | bacillus thuringiensis h-14 is a well recognized bioinsecticide against mosquitoes. this study investigates the inactivation effect of sunlight on the larvicidal activities of four nigerian isolates of b. thuringiensis h-14, code-named obg1, obg8, gsc3 and gna13 as compared with a standard mosquito larvicide, b. thuringiensis var. israelensis (bti). a 0.125 mg/1 suspension of spore-delta-endotoxin powder of each isolate was exposed to direct sunlight for 7 h on a concrete roof (ca. 13 m high). a ... | 1996 | 8810143 |
| substitution of residues on the proximal side of cry1a bacillus thuringiensis delta-endotoxins affects irreversible binding to manduca sexta midgut membrane. | substitution of a positively charged residue (r93f) or addition of a negatively charged residue (a92d) at the n-terminal of alpha 3 helix of domain i of the cry1ac delta-endotoxin resulted in a substantial reduction in toxicity against manduca sexta. the n-terminal residues of helix 3 are considered to be on the same (proximal) surface of the toxin as the loops in domain ii which are involved in the binding of the toxin to the receptor. the loss of toxicity was not caused by a decrease in the in ... | 1996 | 8806584 |
| restriction map of the 125-kilobase plasmid of bacillus thuringiensis subsp. israelensis carrying the genes that encode delta-endotoxins active against mosquito larvae. | a large plasmid containing all delta-endotoxin genes was isolated from bacillus thuringiensis subsp. israelensis; restricted by bamhi, ecori, hindiii, kpni, psti, saci, and sali; and cloned as appropriate libraries in escherichia coli. the libraries were screened for inserts containing recognition sites for bamhi, saci, and sali. each was labeled with 32p and hybridized to southern blots of gels with fragments generated by cleaving the plasmid with several restriction endonucleases, to align at ... | 1996 | 8795201 |
| problems that can limit the expression of foreign genes in plants: lessons to be learned from b.t. toxin genes. | 1996 | 8785128 |