Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| a field survey of bacteriophage contamination of mosquito breeding places, inhibiting bacterial insecticide. | twelve geographically different mosquito breeding places were described and sampled for the detection of naturally existed bacteriophage viruses which could transduct and lysate 5 entomopathogenic bacteria. the surveyed places are classified into seepage, sewage, and irrigation breeding water. bacterial free filtrates of the collected samples were assayed against the tested bacteria in vitro and against 3rd instar culex pipiens larvae as well. nine out of the twelve places could demonstrate the ... | 1993 | 8376856 |
| characterization of tn1546, a tn3-related transposon conferring glycopeptide resistance by synthesis of depsipeptide peptidoglycan precursors in enterococcus faecium bm4147. | sequence determination of the flanking regions of the vancomycin resistance van gene cluster carried by pip816 in enterococcus faecium bm4147 revealed similarity to transposons of the tn3 family. imperfect inverted repeats (36 of 38 bp) delineated a 10,851-bp element designated tn1546. the 4-kb region located upstream from the vanr gene contained two open reading frames (orf) transcribed in opposite directions. the deduced amino acid sequence of orf1 (988 residues) displayed, respectively, 56 an ... | 1993 | 8380148 |
| identification and partial purification of a bacillus thuringiensis cryic delta-endotoxin binding protein from spodoptera littoralis gut membranes. | immunoblotting experiments were performed using cryic and cryia(c) bacillus thuringiensis delta-endotoxins to detect the presence of specific toxin binding proteins on spodoptera littoralis brush border membrane vesicles. the cryic toxin binds two proteins of 40 and 65 kda and the cryia(c) binds a protein of 40 kda. the cryia(c) toxin also binds faintly to a 120 kda protein on s. littoralis brush border membrane vesicles as does a polyclonal antiserum raised against a putative cryia(c) 120 kda b ... | 1993 | 8380781 |
| suppression of protein structure destabilizing mutations in bacillus thuringiensis delta-endotoxins by second site mutations. | reciprocal exchange of a small region (residues 428-450) within the specificity determining region of two bacillus thuringiensis delta-endotoxins, cryiaa and cryiac, resulted in two recombinant proteins that possess a decreased insecticidal activity to bombyx mori and manduca sexta. site-directed mutations introduced in this region of one of the recombinant proteins, with the intent of restoring insecticidal activity, resulted in further reduction of toxicity. we determined that the loss of inse ... | 1993 | 8381022 |
| immunologically unrelated heliothis sp. and spodoptera sp. midgut membrane-proteins bind bacillus thuringiensis cryia(b) delta-endotoxin. | the bacillus thuringiensis toxins, cryia(a), cryia(b), cryia(c) and cryic were used in a ligand-blot assay to detect specific toxin-binding proteins in the brush-border membranes of heliothis virescens, helicoverpa zea, spodoptera littoralis, spodoptera exigua and spodoptera litura. while cryia(a) and cryia(b) always recognize the same protein(s) in a given species, cryia(c) and cryic were found to bind to other proteins. polyclonal antibodies directed against the cryia(b) binding protein of h. ... | 1993 | 8383036 |
| identification of two expressed flagellin genes in the insect pathogen bacillus thuringiensis subsp. alesti. | flagellin from bacillus thuringiensis subspecies alesti strain bt75 was isolated both from the culture medium and from flagella. two protein forms with molecular masses close to 32 kda were obtained from flagella; one form was identical to the flagellin purified from the culture medium. the n-terminal amino acid sequences were identical for both forms. two genes coding for flagellin have been identified in b. thuringiensis subsp. alesti. the flab gene was cloned and sequenced in its entire lengt ... | 1993 | 8383729 |
| respective role of the 42- and 51-kda components of the bacillus sphaericus toxin overexpressed in bacillus thuringiensis. | the 42- and 51-kda protein genes of bacillus sphaericus 1593 have been subcloned independently downstream from the cyta gene promoter of bacillus thuringiensis serovar israelensis and introduced into a non-mosquitocidal strain of bacillus thuringiensis. consequently, each protein was overproduced and accumulated as inclusion bodies which were purified. for the first time, the 42-kda protein inclusions alone were found to be toxic to culex pipiens larvae (lc50 at 48 h 300 ng ml-1); in contrast, t ... | 1993 | 8384140 |
| the two faces of bacillus thuringiensis: insecticidal proteins and post-exponential survival. | post-exponential bacillus thuringiensis cells produce both an endospore and a variety of intracellular inclusions. the latter are comprised of protoxins, each being specific for the larvae of certain species from at least three orders of insects. following ingestion of spores and inclusions, toxicity results in the spores gaining access to haemolymph, a source of nutrients suitable for germination and growth. most b. thuringiensis subspecies contain multiple, plasmid-encoded protoxin genes, ofte ... | 1993 | 8384686 |
| structural and functional characterization of the alpha 5 segment of bacillus thuringiensis delta-endotoxin. | one of the most conserved sequences in various delta-endotoxins is the 30 amino acid long block i. block i of cryiiia delta-endotoxin contains a 23 amino acid amphiphilic alpha-helix termed alpha 5. the potential involvement of this alpha 5 helix in the toxic mechanism of delta-endotoxin was examined. for this purpose, a peptide corresponding to the alpha 5 segment and its proline incorporated analogue (p-alpha 5) were synthesized and characterized. the alpha-helical content of the peptides, ass ... | 1993 | 8384882 |
| a rapid and sensitive in vitro assay for the activity of bacillus thuringiensis delta-endotoxins. | 1. activated delta-endotoxins from bacillus thuringiensis strains toxic to lepidopteran larvae inhibit k(+)-dependent accumulation of amino acids into brush border membrane vesicles (bbmv) from the midgut of the susceptible species bombyx mori. 2. the activated toxins interfere with the k(+)-dependent uptake of histidine into bbmv only if they are effectively active in vivo. 3. to calculate ic50 values (the toxin concentration which determines 50% of the effect), dose-response curves were perfor ... | 1993 | 8384964 |
| transcriptional regulation of bacillus thuringiensis subsp. israelensis mosquito larvicidal crystal protein gene cryiva. | the cryiva gene encodes a component of the delta-endotoxin of bacillus thuringiensis subsp. israelensis. by s1 nuclease mapping and primer extension analysis, we have identified the transcriptional initiation site of cryiva. the transcriptional activity from the promoter was detected only for the sporulating cells more than 3 h after onset of the stationary phase. upstream from the cryiva transcriptional initiation site was found a nucleotide sequence partially homologous to the promoter consens ... | 1993 | 8386726 |
| evidence that the putative cooh-terminal signal transamidase involved in glycosylphosphatidylinositol protein synthesis is present in the endoplasmic reticulum. | nascent proteins destined to be processed to a glycosylphosphatidylinositol (gpi)-anchored membrane form contain nh2-terminal and cooh-terminal signal peptides. the first directs a nascent protein into the endoplasmic reticulum; the second peptide targets the protein to a putative cooh-terminal signal transamidase where cleavage of the peptide and addition of the gpi anchor occur. we recently showed that atp hydrolysis is required for maturation of gpi proteins at a stage prior to transamidation ... | 1993 | 8387204 |
| [study of the nature of determinants for synthesis of delta-endotoxin and beta-exotoxin in bacillus thuringiensis subsp. thuringiensis strains--bitoxybacillin producers]. | the growth of bacillus thuringiensis subsp. thuringiensis strains (bt) 202, 1140, 98 producing bitoxybacillin in the presence of novobiocin, mitomycin c and at high temperature 43 degrees c resulted in obtaining of the mutants for the synthesis of crystalline protein (cry) and exotoxin (exo). analysis of the plasmid content of the mutants has shown the cry exo phenotyre to correlate with the loss of 55 md plasmid in the strain bt202 and the loss of 60md plasmid in bt1140. the transfer of these p ... | 1993 | 8389984 |
| proof of alkaline phosphodiesterase i as a phosphatidylinositol-anchor enzyme. | 1. ectoenzyme release from kidney brush border membranes of rattus norvegicus and sus scrofa domesticus by phosphatidylinositol-specific phospholipase c (piplc) of bacillus thuringiensis was studied. 2. the levels of specific activities of ectoenzymes in r. norvegicus kidney brush border membranes were higher than those in s. scrofa domesticus. about 10-fold higher values were found for specific activities of alkaline phosphatase and gamma-glutamyl transpeptidase in r. norvegicus. 3. alkaline ph ... | 1993 | 8394252 |
| [site-specific restriction endonuclease from the strain of bacillus thuringiensis var. kumantoensis]. | 1993 | 8394507 | |
| substrate requirements of bacterial phosphatidylinositol-specific phospholipase c. | a series of symmetric short-chain phosphatidylinositols (pi), including dihexanoyl-pi, diheptanoyl-pi (racemic as well as d and l forms), and 2-methoxy inositol-substituted diheptanoyl-pi, have been synthesized, characterized, and used to investigate key mechanistic questions about phosphatidylinositol-specific phospholipase c (pi-plc) from bacillus thuringiensis. key results include the following: (i) bacterial pi-plc exhibits a 5-6-fold "interfacial activation" when its substrate is present in ... | 1993 | 8395883 |
| insertion sequence elements in bacillus thuringiensis subsp. darmstadiensis. | two variants of insertion sequence is231, named is231g and h, were isolated from bacillus thuringiensis subsp. darmstadiensis 73-e-10-2 (btd2), an isolate toxic to dipteran insects, and characterized by dna sequence analysis. they are encoded consecutively as direct repeats on an ecori fragment of 5.6 kilo base pairs. direct tandem repeats of is231 elements have not been previously reported. both elements are closely related to other members of the is231 family that have been isolated from b. th ... | 1993 | 8395964 |
| effects on toxicity of eliminating a cleavage site in a predicted interhelical loop in bacillus thuringiensis cryivb delta-endotoxin. | when activated by treatment with mosquito (aedes aegypti) gut extract, the bacillus thuringiensis cryivb delta-endotoxin lysed a. aegypti cells in vitro. sds-page and n-terminal sequence determination showed that in addition to removal of the c-terminal half of the molecule, the activated toxin had undergone proteolytic cleavage at two internal regions producing 47-48-kda and 16-18-kda polypeptides. aligning the cryivb protein sequence with the crystallographic structure of the cryiiia toxin sug ... | 1993 | 8405934 |
| mobilization of small plasmids in bacillus thuringiensis subsp. israelensis is accompanied by specific aggregation. | mobilizations of pbc16 and pand006, containing the replicon of the bacillus thuringiensis subsp. israelensis plasmid ptx14-3, between strains of b. thuringiensis subsp. israelensis were examined. transconjugants appeared after a few minutes and reached a maximum frequency after approximately 2 h. plasmid pbc16 was mobilized at a frequency approximately 200 times that of pand006. however, pand006 was consistently transferred, suggesting that the replicon of ptx14-3 is sufficient to sustain mobili ... | 1993 | 8407829 |
| site-directed mutations in a highly conserved region of bacillus thuringiensis delta-endotoxin affect inhibition of short circuit current across bombyx mori midguts. | bacillus thuringiensis delta-endotoxins (cry toxins) are insecticidal proteins of approximately 65 kda in the proteolytically processed and active form. the structure of one of these toxins, cryiiia, has been determined by li et al. [li, j., carroll, j. & ellar, d. j. (1991) nature (london) 353, 815-821] and contains three domains. it is believed that other delta-endotoxins adopt similar three-dimensional structure. li et al. proposed that the first domain is the membrane pore-forming domain. pr ... | 1993 | 8415651 |
| cloning and characterization of a novel bacillus thuringiensis cytolytic delta-endotoxin. | a gene encoding a major entomocidal polypeptide from bacillus thuringiensis subspecies kyushuensis delta-endotoxin crystals (cytb) was cloned into escherichia coli and sequenced. the deduced amino acid sequence gave a predicted molecular mass of 29,236 da and showed 39% identity and 70% similarity with the 27,371 da cyta protein from bacillus thuringiensis subspecies israelensis. the larger size of cytb compared to cyta appears to be due to additional sequence in cytb after the cyta c-terminus. ... | 1993 | 8429550 |
| a complete physical map of a bacillus thuringiensis chromosome. | bacillus thuringiensis is the source of the most widely used biological pesticide, through its production of insecticidal toxins. the toxin genes are often localized on plasmids. we have constructed a physical map of a bacillus thuringiensis chromosome by aligning 16 fragments obtained by digestion with the restriction enzyme noti. the fragments ranged from 15 to 1,350 kb. the size of the chromosome was 5.4 mb. the noti dna fingerprint patterns of 12 different b. thuringiensis strains showed mar ... | 1993 | 8432698 |
| multiplex polymerase chain reaction for detection and differentiation of the microbial insecticide bacillus thuringiensis. | a rapid identification of bacillus thuringiensis strains was established by using multiplex polymerase chain reaction (pcr). primers of high homology specific to regions within genes encoding three major classes of b. thuringiensis crystal proteins were used to generate a pcr product profile characteristic of each strain of b. thuringiensis subsp. kurstaki. differentiation among these strains was made on the basis of the electrophoretic pattern of the pcr products. known b. thuringiensis subsp. ... | 1993 | 8434916 |
| arbitrary primer polymerase chain reaction, a powerful method to identify bacillus thuringiensis serovars and strains. | arbitrary primer polymerase chain reaction technology has been applied to the identification of commercial strains of bacillus thuringiensis by using total dnas extracted from single bacterial colonies as templates. characteristic dna banding patterns can be readily and reproducibly obtained by agarose gel electrophoresis. this method has been used to distinguish commercial products containing b. thuringiensis serovar kurstaki (3a3b). when a single primer was used this method was capable of prod ... | 1993 | 8439143 |
| analysis of features contributing to activity of the single-stranded origin of bacillus plasmid pbaa1. | the features which contribute to the activity of the single-stranded origin of the bacillus plasmid pbaa1 were investigated. this origin is contained on a dna fragment greater than 116 but less than 191 bases in size. there is the potential to form three stem-loop structures within this fragment. comparison of the sequence of this origin from pbaa1 with the sequence of a homologous fragment from the bacillus thuringiensis plasmid pgi2 indicates that both the structure and the relative positionin ... | 1993 | 8458841 |
| evidence that the cryia crystal protein from bacillus thuringiensis is associated with dna. | toxin generated by activation of the bacillus thuringiensis cryia(c) crystal protein (protoxin) with bovine trypsin was separated into two components by anion-exchange chromatography. one component (t2) was dna-associated toxin, and the other was the dna-free toxin (t1). only one major protoxin component was observed, and it was found to be associated with dna. the dna from the t2 toxin varied in size from 100 to 300 base pairs, whereas the crystal and the solubilized protoxin contained 20-kilob ... | 1993 | 8463332 |
| membrane-bound choline-o-acetyltransferase in rat hippocampal tissue is anchored by glycosyl-phosphatidylinositol. | in an earlier study, we presented evidence to suggest that some of the particulate choline-o-acetyltransferase (chat) in rat hippocampal tissue might be linked to membranes by a glycosyl-phosphatidylinositol (gpi) anchor. in the present report, we attempted to determine if any of this gpi-anchored chat might be intracellular. internalization of phosphatidylinositol-specific phospholipase c (pi-plc) from bacillus thuringiensis into rat hippocampal synaptosomes by the dmso (dimethyl sulfoxide) fre ... | 1993 | 8467384 |
| analysis of common antigen of flagella in bacillus cereus and bacillus thuringiensis. | flagellar antigen of bacillus cereus h.1 was purified and tested for serodiagnostic antigen by elisa. the antibody against the flagellar antigen of b. cereus h.1 reacted not only with the homologous specific antigen but also reacted with the flagellar antigens of 23 strains of b. cereus. this common flagellar antigen of b. cereus was found to be due to 61-kda protein by sds-page and immunoblot assay. monoclonal antibody h15a5 against common antigenic epitope of b. cereus also reacted with flagel ... | 1993 | 8472901 |
| cloning of a novel cryic-type gene from a strain of bacillus thuringiensis subsp. galleriae. | a novel cryic-type gene was isolated from a strain of bacillus thuringiensis subsp. galleriae. a new polymerase chain reaction (pcr) technique with a set of several oligonucleotide primer pairs specific to the cryic gene was used to screen a number of b. thuringiensis strains. pcr amplified several dna fragments ranging from 100 bp to 1 kb for b. thuringiensis strains containing a cryic gene. pcr fragments amplified from the bacillus thuringiensis subsp. galleriae hd29 dna differed from the frag ... | 1993 | 8476286 |
| high-level cryivd and cyta gene expression in bacillus thuringiensis does not require the 20-kilodalton protein, and the coexpressed gene products are synergistic in their toxicity to mosquitoes. | interactions among the 20-kda protein gene and the cyta and cryivd genes located in a 9.4-kb hindiii fragment were studied. a series of plasmids containing a combination of these different genes was constructed by using the escherichia coli/bacillus thuringiensis shuttle vector pht3101. the plasmids were then used to transform an acrystalliferous strain, cryb, derived from b. thuringiensis subsp. kurstaki. the results from sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot ... | 1993 | 8481007 |
| effect of bacteriophage lysogeny on the efficacy of two bacterial larvicide formulations under field conditions. | two types of man-made ditches were selected for carrying out this experiment; one polluted with nitrogenous matters (sewage water) and second filled with accumulated irrigated clear non-chlorinated water. no phages were detected in samples collected from both types of ditches. however, phage(s) specific to only b. sphaericus was (were) detected after spraying the two types with both b. thuringiensis h-14 and b. sphaericus commercial formulations. the detection of phage(s) was observed after 3 da ... | 1993 | 8482880 |
| in vitro and in vivo proteolysis of the bacillus thuringiensis subsp. israelensis cryivd protein by culex quinquefasciatus larval midgut proteases. | proteases with trypsin-, chymotrypsin- and thermolysin-like specificity were detected in culex quinquefasciatus larval midguts. their activities were monitored by n-terminal amino acid sequence analysis of the bacillus thuringiensis subsp. israelensis cryivd toxin proteolytic fragments. these proteases are located in the larval midgut and in different fractions obtained during the preparation of brush border membrane vesicles. the activity of the midgut proteases increased with an increase in ph ... | 1993 | 8485524 |
| the reconstruction and expression of a bacillus thuringiensis cryiiia gene in protoplasts and potato plants. | a bacillus thuringiensis (b.t.) cryiiia delta-endotoxin gene was designed for optimal expression in plants. the modified cry gene has the codon usage pattern of an average dicot gene and does not contain at-rich nucleotide sequences typical of native b.t. cry genes. we assembled the 1.8 kb cryiiia gene in nine blocks of three oligonucleotide pairs. for two dna blocks, the polymerase chain reaction was used to enrich for correctly ligated pairs. we compared modified cryiiia gene with native gene ... | 1993 | 8490132 |
| full expression of the cryiiia toxin gene of bacillus thuringiensis requires a distant upstream dna sequence affecting transcription. | the cryiiia gene encoding a coleopteran-specific toxin is poorly expressed in bacillus thuringiensis when cloned in a low-copy-number plasmid. this weak expression is observed when the gene is cloned only with its promoter and its putative terminator. cryiiia gene expression was analyzed by using deletion derivatives of a larger dna fragment carrying the toxin gene and additional adjacent sequences. the results indicate that a 1-kb dna fragment located 400 bp upstream of the promoter strongly en ... | 1993 | 8491716 |
| [studies on insecticidal ingredients from culture supernatant of bacillus thuringiensis]. | studies on the insecticidal activity of culture supernatant of bacillus thuringiensis var. kurstaki hd-1, by centrifugation, column chromatography, protein sequence determination, bioassay and other methods. found that insecticidal activity of culture supernatant appeared on synchronism with cells lysis. main insecticidal ingredients of culture supernatant is toxin protein of 60 kilodaltons (kda). analyse hat purified the toxin protein, we find that its amino acid composition was similar with 13 ... | 1993 | 8503203 |
| genetically improved potatoes: protection from damage by colorado potato beetles. | russet burbank potato plants have been genetically improved to resist insect attack and damage by colorado potato beetles (leptinotarsa decemlineata (say)) by the insertion of a cryiiia gene encoding the insect control protein of bacillus thuringiensis var. tenebrionis. a modified gene that dramatically improved plant expression of this protein was utilized. its expression in russet burbank potato plants resulted in protection from damage by all insect stages in the laboratory and in dramatic le ... | 1993 | 8507832 |
| a specific binding protein from manduca sexta for the insecticidal toxin of bacillus thuringiensis subsp. berliner. | biopesticides based on the bacterium bacillus thuringiensis have attracted wide attention as safe alternatives to chemical pesticides. in this paper, we report, for the first time, the identification and purification of a single binding protein from a lepidopteran insect, manduca sexta, that is specific for a cryia toxin of b. thuringiensis. the purified protein appeared as a single band of 210 kda on a two-dimensional gel, had a pi of approximately 5.5, and stained with schiff's reagent. the ba ... | 1993 | 8509372 |
| [structural and molecular-biological characteristics of a new transducing phage from bacillus thuringiensis tt 91]. | a new bacteriophage tt91 of larger size and broad lytical spectrum has been isolated from soil to widen the possibility to study new bacillus thuringiensis strains. the tt91 bacteriophage was shown to perform the intravariant transduction and, thus, can be used for genetic mapping. the ultrastructural analysis made it possible to refer bacteriophage tt91 to morphotype a1 and showed similarity of tt91 morphological structure to the one of cp-group bacteriophages. the performed comparative analysi ... | 1993 | 8510683 |
| screening by polymerase chain reaction of bacillus thuringiensis serotypes for the presence of cryv-like insecticidal protein genes and characterization of a cryv gene cloned from b. thuringiensis subsp. kurstaki. | polymerase chain reaction screening using cryv-specific oligonucleotides, designed to amplify the 5' half of cryv-type genes, revealed the presence of such genes in 7 of 21 bacillus thuringiensis serotypes examined. restriction analysis and hybridization studies indicated that these putative genes fall into at least three subclasses. the nucleotide sequence of the cryv-type gene cloned from b. thuringiensis subsp. kurstaki dsir732 revealed an open reading frame coding for a protein of 719 amino ... | 1993 | 8517758 |
| bacillus thuringiensis growth and toxicity. basic and applied considerations. | despite the known importance of the composition of culture media and culture conditions on bacillus thuringiensis growth and toxicity, very few reviews are concerned with this subject. this article reviews some aspects of the microbiology of bacillus thuringiensis, and how toxicity is affected by the composition of growth media and bioreactor operation. | 1995 | 8521040 |
| [examination of toxin production from environmental bacillus cereus and bacillus thuringiensis]. | emetic toxin- and entero toxin-producing activities were examined for 524 strains of bacillus cereus and 90 strains of bacillus thuringiensis to determine the distribution and contamination in natural environment, including foods, vegetable, soil and etc. emetic toxin was assayed by the production of acid from hep-2 cells induced by the culture supernatants of bacillus, which was developed as an improved method for the detection of b. cereus heat-stable emetic-toxin by us. in the 524 strains of ... | 1995 | 8523268 |
| some environmental and biological factors influencing the activity of entomopathogenic bacillus on mosquito larvae in brazil. | the influence of environmental and biological factors on the efficacy of bacillus thuringiensis serovar israelensis and b. sphaericus as mosquito larvicides are reviewed. the importance of strain dependence, cultivating media/methods, mosquito species/specificity, formulations and their relation to mosquito feeding habits, as well as temperature, solar exposure, larval density and concomitant presence of other aquatic organisms are addressed with reference to the present status of knowledge in b ... | 1995 | 8524073 |
| biological control program against simuliids in the state of são paulo, brazil. | in brazil, the use of biological vector-control methods has been largely confined to experimental research, with little or no application of such techniques by public institutions responsible for implementing control programs. the notable exceptions have been the black fly control program carried out by the health secretariat in the state of são paulo. since the 1980s, são paulo's "superintendência de controle de endemias" has been conducting studies on the viability of using bacillus thuringien ... | 1995 | 8524076 |
| bacillus thuringiensis: fermentation process and risk assessment. a short review. | several factors make the local production of bacillus thuringiensis (bt) highly appropriate for pest control in developing nations. bt can be cheaply produced on a wide variety of low cost, organic substrates. local production results in considerable savings in hard currency which otherwise would be spent on importation of chemical and biological insecticides. the use of bt in brazil has been limited in comparison with chemical insecticides. although bt is imported, some brazilian researchers ha ... | 1995 | 8524077 |
| cloning of a fragment of the gene cryivb from bacillus thuringiensis var. israelensis coding for the aminoterminal segment of a 130 kda larvicidal endotoxin. | 1995 | 8524078 | |
| bacillus thuringiensis subsp. oswaldocruzi and bacillus thuringiensis subsp. brasiliensis, two novel brazilian strains which determine new serotype h38 and h39, respectively. | 1995 | 8524081 | |
| mechanism of action of bacillus thuringiensis toxins. | the selectivity of bacillus thuringiensis toxins is determined both by the toxin structure and by factors inherent to the insect. these toxins contain distinct domains that appear to be functionally important in toxin binding to protein receptors in the midgut of susceptible insects, and the subsequent formation of a pore in the insect midgut epithelium. in this article features necessary for the insecticidal activity of these toxins are discussed. these include toxin structure, toxin processing ... | 1995 | 8524088 |
| exploration of receptor binding of bacillus thuringiensis toxins. | wild type and mutant toxins of bacillus thuringiensis delta-endotoxins were examined for their binding to midgut brush border membrane vesicles (bbmv). cryiaa, cryiab, and cryiac were examined for their binding to gypsy moth (lymantria dispar) bbmv. the binding of cryiaa and cryiac was directly correlated with their toxicity, while cryiab was observed to have lower binding than expected from its toxicity. the latter observation confirms the observation of wolfersberger (1990). the "rule" of reci ... | 1995 | 8524089 |
| transfer of toxin genes to alternate bacterial hosts for mosquito control. | mosquitoes are vector of serious human and animal diseases, such as malaria, dengue, yellow fever, among others. the use of biological control agents has provide an environmentally safe and highly specific alternative to the use of chemical insecticides in the control of vector borne diseases. bacillus thuringiensis and b. sphaericus produce toxic proteins to mosquito larvae. great progress has been made on the biochemical and molecular characterization of such proteins and the genes encoding th ... | 1995 | 8524091 |
| specific pcr primers directed to identify cryi and cryiii genes within a bacillus thuringiensis strain collection. | in this paper we describe a pcr strategy that can be used to rapidly identify bacillus thuringiensis strains that harbor any of the known cryi or cryiii genes. four general pcr primers which amplify dna fragments from the known cryi or cryiii genes were selected from conserved regions. once a strain was identified as an organism that contains a particular type of cry gene, it could be easily characterized by performing additional pcr with specific cryi and cryiii primers selected from variable r ... | 1995 | 8526493 |
| resistance to bacillus thuringiensis cryia delta-endotoxins in a laboratory-selected heliothis virescens strain is related to receptor alteration. | the bacillus thuringiensis toxin-binding properties of midgut epithelial cells from two strains of heliothis virescens were compared. one h. virescens strains (yhd2) which was selected against cryiac toxin had over 10,000-fold resistance to cryiac toxin relative to the susceptible strain and was cross-resistant to cryiaa and cryiab. the second h. virescens strain (ydk) was susceptible to these toxins in the order cryiac > cryiab > cryiaa. receptor-binding properties of cryiaa, cryiab, and cryiac ... | 1995 | 8526494 |
| the protoxin composition of bacillus thuringiensis insecticidal inclusions affects solubility and toxicity. | most bacillus thuringiensis strains producing toxins active on lepidoptera contain several plasmid-encoded delta-endotoxin genes and package related protoxins into a single inclusion. it was previously found that in b. thuringiensis subsp. aizawai hd133, which produces an inclusion comprising the cryiab, cryic, and cryid protoxins, there is a spontaneous loss in about 1% of the cells of a 45-mda plasmid containing the cryiab gene. as a result, inclusions produced by the cured strain were less re ... | 1995 | 8526519 |
| cloning and expression of a novel toxin gene from bacillus thuringiensis subsp. jegathesan encoding a highly mosquitocidal protein. | a gene, designated cry11b, encoding a 81,293-da crystal protein of bacillus thuringiensis subsp. jegathesan was cloned by using a gene-specific oligonucleotide probe. the sequence of the cry11b protein, as deduced from the sequence of the cry11b gene, contains large regions of similarity with the cry11a toxin (previously cryivd) from b. thuringiensis subsp. israelensis. the cry11b protein was immunologically related to both cry11a and cry4a proteins. the cry11b gene was expressed in a nontoxic s ... | 1995 | 8534090 |
| increased susceptibility to bacillus thuringiensis associated with pyrethroid resistance in bovicola (damalinia) ovis (phthiraptera mallophaga: possible role of monooxygenases. | a comparison of the toxicity of bacillus thuringiensis (berliner) to pyrethroid-susceptible and -resistant strains of bovicola (damalinia) ovis showed that b. thuringiensis and pyrethroid toxicity were inversely related. the b. ovis strain with an apparent monooxygenase-mediated pyrethroid resistance mechanism was significantly more susceptible to b. thuringiensis. susceptibility to b. thuringiensis in both the pyrethroid-susceptible and -resistant strains was significantly reduced after adminis ... | 1995 | 8537542 |
| control of mosquito larvae by encapsulated pathogen bacillus thuringiensis var. israelensis. | bacillus thuringiensis var. israelensis (b.t.i.) containing alginate microcapsules were prepared in order to maintain durable formulations which could resist several effects causing reduced efficiency during applications. b.t.i. spores were harvested through nysm agar plates and encapsulated in ca-alginate (0.5-2.0% w/v) gels without any significant loss of sporal or larvicidal activity. the effect of acidic ph on the larvicidal toxin was tested using culex sp. larvae in the laboratory. the algi ... | 1995 | 8544095 |
| [comparative characteristics of mutants of bacillus thuringiensis subsp. kurstaki]. | a study of physiological and biochemical properties of 12 strains of bacillus thuringiensis subsp. kurstaki was performed. the strains studied included natural isolates similar to the type strain in their properties, a cry-spo+ mutant, and also mutants assigned to c-1 or c-73 crystovar according to the properties of their parasporal crystals and the ability to hydrolyze esculin, generate acid from salicin, and exert urease activity. the crystals produced by c-1 crystovar cultures were three time ... | 1995 | 8544785 |
| the potential for malaria control with the biological larvicide bacillus thuringiensis israelensis (bti) in peru and ecuador. | a study on the efficacy of bti spraying in mosquito breeding places was undertaken in the pacific coast of peru and ecuador and in the amazon area of peru. it was shown that bti is a powerful larvicide for anopheles larvae, although it sinks quickly, whereas anopheles larvae feed at the water surface. the duration of its effect was less than 7 days with the exception of the amazon area of peru, where it was approximately 10 days. in two study areas, bti was sprayed weekly over periods of 10 and ... | 1995 | 8546038 |
| the structure of bacterial cell cycle and age structure of bacterial populations. | study of synchronous and asynchronous cultures of bacillus megaterium, bacillus thuringiensis and bacillus licheniformis has shown that the duration of chromosomal dna replication (period c) is proportional to the generation time, and time between two cycles of the dna replication (known as period i). the duration of period c is nearly constant and makes up from 0.5 to 1.0 hour at the variations of the generation time from 1.5 to 2.75 hours. the duration of period b (the time between the termina ... | 1995 | 8548068 |
| establishment and characterization of three cell lines from aedes triseriatus (diptera: culicidae). | three cell lines (a.t. grip-1, 2, and 3) were established from aedes triseriatus (say) embryonated eggs or neonate larvae and their morphology, growth, karyotype, and isozyme pattern were studied. the isozyme alleles observed in the 3 cell lines also were found in adults of the original mosquito colony. each cell line differed in enzymatic, morphological, and karyotypical patterns. la crosse encephalitis (lac) and snowshoe hare (ssh) viruses, members of the california encephalitis virus group, w ... | 1995 | 8551501 |
| [laboratory examination of the effectiveness of new biological preparations for reducing populations of cockroaches (blattella germanica l.)]. | the usefulness of new commercial products of biological origin (biobit, novo skeetal and novodor) was tested in cockroaches (blattella germanica l.) control. biobit proved to be the most effective in reduction of cockroaches population. its higher activity against cockroaches was observed in all concentrations tested. females were more sensitive for all tested products than males. | 1995 | 8552970 |
| 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 |
| ionic permeabilities induced by bacillus thuringiensis in sf9 cells. | the effect of bacillus thuringiensis insecticidal toxins on the monovalent cation content and intracellular ph (phi) of individual sf9 cells of the lepidopteran species spodoptera frugiperda (fall armyworm) was monitored with the fluorescent indicators potassium-binding benzofuran isophthalate (pbfi) and 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (bcecf). the sequential removal of k+ and na+ from the medium, in the presence of cryic, a toxin which is highly active against sf9 cells, caused s ... | 1995 | 8558602 |
| analysis of double-stranded polymerase chain reaction products from the bacillus cereus group by electrospray ionization fourier transform ion cyclotron resonance mass spectrometry. | the analysis of polymerase chain reaction (pcr) products by electrospray ionization-fourier transform ion cyclotron resonance mass spectrometry (esi-fticr) has been achieved. specifically, a 105 base-pair nucleotide portion of the ribosomal spacer region was amplified in two members of the b. cereus group (i.e. b. thuringiensis and b. cereus) using pcr. these amplified regions were then analyzed by gel electrophoresis and esi-fticr. based on the predicted sequence of the pcr products for each or ... | 1996 | 8563015 |
| effect of two commercial formulations of bacillus thuringiensis subsp. kurstaki (dipel 8l and dipel 8af) on the collembolan species folsomia candida in a soil microcosm study. | 1995 | 8563213 | |
| comparative larvicidal activities of the four bacillus thuringiensis serovars against a chironomid midge, paratanytarsus grimmii (diptera: chironomidae). | the four reference strains of bacillus thuringiensis, known to be pathogenic for mosquito larvae of the family culicidae (diptera), were examined for their larvicidal activities against a chironomid species, paratanytarsus grimmii (diptera: chironomidae). of the four, the type strain of b. thuringiensis serovar israelensis (h14) exhibited the highest activity against both early- and late-instar larvae, while the type strain of serovar kyushuensis (h11ac) and the strain 73-e-10-2 (h10, serovar da ... | 1995 | 8564369 |
| characterization of baculovirus insecticides expressing tailored bacillus thuringiensis cryia(b) crystal proteins. | full-length, truncated, and mature forms of the cryia(b) insecticidal crystal protein gene of bacillus thuringiensis were engineered into the p10 locus of autographa californica nuclear polyhdrosis virus (acnpv). a signal sequence of heliothis virescens juvenile hormone esterase was introduced at the n-terminus of these constructs to induce secretion. all recombinants, except those containing the mature toxin, produced high levels of cryia(b) icps in insect cells. thirty percent of the intracell ... | 1995 | 8568280 |
| 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 |
| a protein complex from choristoneura fumiferana gut-juice involved in the precipitation of delta-endotoxin from bacillus thuringiensis subsp. sotto. | a 75 kda protein from spruce budworm (choristoneura fumiferana) gut-juice has been isolated and shown to cause a specific precipitation of the delta-endotoxin from bacillus thuringiensis subsp. sotto. this 75 kda protein, separated by either column chromatography or sds-page, caused precipitation of the sotto toxin in both agarose diffusion gels and the page gels. the precipitation event leads to limited proteolysis of the toxin and loss of larval toxicity. sds-page analysis of the precipitated ... | 1995 | 8580910 |
| brush border membrane aminopeptidase-n in the midgut of the gypsy moth serves as the receptor for the cryia(c) delta-endotoxin of bacillus thuringiensis. | aminopeptidase-n (ap-n) was purified from gypsy moth (lymantria dispar, l.) brush border membrane vesicles (bbmv) proteins by mono-q chromatography and superdex-75 gel filtration in the presence of the zwitterionic detergent, chaps, using fplc. the purified ap-n, identified by its enzymatic activity, had an apparent size of 100 kda, and was identified as the unique bacillus thuringiensis insecticidal toxin, cryia(c), binding protein. ap-n clearly displayed strong binding to cryia(c), exhibiting ... | 1995 | 8580914 |
| phage typing of bacillus subtilis and b. thuringiensis. | phage typing schemes for bacillus subtilis and b. thuringiensis were constructed using 98 phages and 743 bacterial strains. most phages were host-species-specific. phages were classified by electron microscopy. the b. subtilis scheme includes 10 phages and 29 phage types. the b. thuringiensis scheme comprises 8 phages and 25 phage types and can be applied to b. cereus. there is no correlation between h antigen serotypes and phagovars in b. thuringiensis. characteristics of typing phages are desc ... | 1995 | 8584788 |
| cloning of a novel crystal protein gene cry1k from bacillus thuringiensis subsp. morrisoni. | a novel crystal protein gene cry1k has been cloned and sequenced from a bacillus thuringiensis subsp. morrisoni bf190 isolated from phylloplane. the upstream promoter region of cry1k was almost identical with that of cry1b. the deduced amino acid sequence of cry1k contains 1215 amino acid residues with an estimated molecular mass of 137 kda. comparison of the amino acid sequence of the cry1k with that of cry proteins revealed that cry1k is most closely related to cry1b and cry1i. cry1k has a hig ... | 1995 | 8586263 |
| 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 |
| a 28,000 mol. wt toxin from bacillus thuringiensis israelensis induces cation transport in rat muscle cultures. | the mechanism by which the bacillus thuringiensis israelensis (bti) 28,000 mol. wt toxin exerts its effect on mature muscle cultures was examined. the toxin inhibited na+/k(+)-atpase activity as revealed by 86rb influx. a 50% inhibition of na+/k(+)-atpase activity was obtained with 0.2 microgram/ml of the toxin. the inhibition was time and dose dependent, and it was reversible with low doses of the toxin (up to 0.2 microgram/ml. a considerable release of 86rb was obtained by doses greater than 0 ... | 1995 | 8588218 |
| crystallization of a membrane pore-forming protein with mosquitocidal activity from bacillus thuringiensis subspecies kyushuensis. | cytb, a membrane pore-forming toxin from bacillus thuringiensis subspecies kyushuensis, is specifically toxic to dipteran insect larvae but broadly cytolytic in vitro. it has been purified in the protoxin form from a recombinant escherichia coli source and crystals have been obtained which diffract x-rays to at least 2.6 a resolution. the tendency for cytb to aggregate in solution was overcome by including 50 mm of urea or 8 mm of ethanolamine during crystallization. mutants designed to add or s ... | 1995 | 8592711 |
| 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 |
| regulation of insecticidal crystal protein production in bacillus thuringiensis. | the production of insecticidal crystal proteins (icps) in bacillus thuringiensis normally coincides with sporulation, resulting in the appearance of parasporal crystalline inclusions within the mother cell. in most instances, the temporal and spatial regulation of icp gene expression is determined at the transcriptional level by mother-cell-specific sigma factors that share homology with sigma e and sigma k from bacillus subtilis. the cryiii icp genes are a notable exception; these genes are tra ... | 1995 | 8596449 |
| 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 |
| resistance and the control of sheep ectoparasites. | for about 100 years australian woolgrowers have used a variety of chemicals to control blowflies, lice and other ectoparasites of sheep. while the chemicals have changed considerably the application technology has not changed very much at all. chemicals registered for use on sheep have paralleled the evolution of synthetic insecticides with the unfortunate consequence of the development of resistance in the australian sheep blowfly, lucilia cuprina, following closely behind. organochlorine (diel ... | 1995 | 8635885 |
| vip3a, a novel bacillus thuringiensis vegetative insecticidal protein with a wide spectrum of activities against lepidopteran insects. | a novel vegetative insecticidal gene, vip3a(a), whose gene product shows activity against lepidopteran insect larvae including black cutworm (agrotis ipsilon), fall armyworm (spodoptera frugiperda), beet armyworm (spodoptera exigua), tobacco budworm (heliothis virescens), and corn earworm (helicoverpa zea) has been isolated from bacillus thuringiensis strain ab88. vip3-insecticidal gene homologues have been detected in approximately 15% of bacillus strains analyzed. the sequence of the vip3a(b) ... | 1996 | 8643585 |
| cloning and expression of the first anaerobic toxin gene from clostridium bifermentans subsp. malaysia, encoding a new mosquitocidal protein with homologies to bacillus thuringiensis delta-endotoxins. | a gene (cbm71) encoding a 71,128-da mosquitocidal protein (cbm71) was obtained by screening a size-fractionated xbai digest of total genomic dna from clostridium bifermentans subsp. malaysia ch18 with two gene-specific oligonucleotide probes. the sequence of the cbm71 protein, as deduced from the sequence of cbm71, corresponds to that of the 66-kda protein previously described as one of the mosquitocidal components of c. bifermentans subsp. malaysia. cbm71 shows limited similarities with bacillu ... | 1996 | 8655486 |
| 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 |
| semiautomated quantification of cytotoxic damage induced in cultured insect cells exposed to commercial bacillus thuringiensis biopesticides. | a convenient in vitro bioassay based on semiautomated quantification of live-cell reduction of tetrazolium dyes--3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (mtt) and 2,3-bis(2-methoxy-4-nitro-5-sulphophenyl)-2h-tetrazolium-5-corb oxanilide sodium salt (xtt)--to formazan was developed and used to evaluate cytotoxic effects of two commercial insecticides (bt) derived from bacillus thuringiensis subsp. kurstaki (btk). comparison of two target insect cell lines mg1 (trichoplusia ... | 1995 | 8666719 |
| simulation of voltage-dependent insertion of alpha-helical peptides into lipid bilayers. | 1996 | 8674627 | |
| simulation of voltage-dependent interactions of alpha-helical peptides with lipid bilayers. | pore formation in lipid bilayers by channel-forming peptides and toxins is thought to follow voltage-dependent insertion of amphipathic alpha-helices into lipid bilayers. we have developed an approximate potential for use within the charmm molecular mechanics program which enables one to simulate voltage-dependent interaction of such helices with a lipid bilayer. two classes of helical peptides which interact with lipid bilayers have been studied: (a) delta-toxin, a 26 residue channel-forming pe ... | 1996 | 8679929 |
| [interspecific protoplast fusion between bacillus thuringensis bt-3701 and bacillus megaterium bm-107]. | the results of the interspecific protoplast fusion between b. thuringensis sub. kurstaki bt-3701 which has pesticide ability, and b. megaterium var. phosphaticum bm-107 which has decomposing phosphate activity, were reported. high frequency of protoplast formation and regeneration was obtained with 4h activated bm-107 treated by 100 micrograms/ml lysozyme, and with 2h activated bt-3701 treated by 3% glycin and mild temperature. using 40% peg and 5% nascent ca2+ to treat the parential protoplast ... | 1995 | 8701582 |
| different domains of bacillus thuringiensis delta-endotoxins can bind to insect midgut membrane proteins on ligand blots. | we investigated the role of the constituent domains of the cryia(b) and cryia(c) delta-endotoxins in binding to midgut epithelial cell membrane proteins of spodoptera exigua and manduca sexta on ligand blots. a collection of wild-type and cryic-cryia hybrid toxins was used for this purpose. as demonstrated elsewhere (r. a. de maagd, m. s. g. kwa, h. van der klei, t. yamamoto, b. schipper, j. m. vlak, w. j. stiekema, and d. bosch, appl. environ. microbiol. 62:1537-1543, 1996), cryia(b) domain iii ... | 1996 | 8702267 |
| cross-resistance of the diamondback moth indicates altered interactions with domain ii of bacillus thuringiensis toxins. | we compared responses to six insecticidal crystal proteins from bacillus thuringiensis by a cry1a-resistant strain (no-qa) and a susceptible strain (lab-p) of the diamondback moth, plutella xylostella. the resistant strain showed > 100-fold cross-resistance to cry1j and to h04, a hybrid with domains i and ii of cry1ab and domain iii or cry1c. cross-resistance was sixfold to cry1bb and threefold to cry1d. the potency of cry1i did not differ significantly between the resistant and susceptible stra ... | 1996 | 8702276 |
| aminopeptidase n purified from gypsy moth brush border membrane vesicles is a specific receptor for bacillus thuringiensis cryiac toxin. | we have evaluated the binding of bacillus thuringiensis cry toxins to aminopeptidase n (apn) purified from lymantria dispar (gypsy moth) brush border membrane vesicle (bbmv). cryiac toxin bound strongly to apn, while either the structurally related cryiaa and cryiab toxins or cryic, cryiia, and cryiiia toxins showed weak binding to apn. an in vitro competition binding study demonstrated that the binding of cryiac to l. dispar bbmv was inhibited by apn. inhibition of short circuit current for cry ... | 1996 | 8702277 |
| the bacillus thuringiensis insecticidal toxin binds biotin-containing proteins. | brush border membrane vesicles from larvae of the tobacco hornworm, manduca sexta, contain protein bands of 85 and 120 kda which react directly with streptavidin conjugated to alkaline phosphatase. the binding could be prevented either by including 10 microm biotin in the reaction mixture or by prior incubation of the brush border membrane vesicles with an activated 60- to 65-kda toxin from bacillus thuringiensis hd-73. the ability of b. thuringiensis toxins to recognize biotin-containing protei ... | 1996 | 8702286 |
| bacillus thuringiensis crystal proteins cry1ab and cry1fa share a high affinity binding site in plutella xylostella (l.). | the future success of bacillus thuringiensis based insecticides depends in part on our ability to prevent insects from developing resistance against their insecticidal crystal proteins. two recent papers indicated cross-resistance between cry1a proteins and cry1fa in two different insect species (tabashnik et al., 1994, appl. environ. microbiol. 60, 4627-4629; gould et al., 1995, j. econ. entomol. 88, 1545-1559). brush border membrane vesicles were prepared from plutella xylostella and used in b ... | 1996 | 8713122 |
| effect of tadpole shrimp, triops longicaudatus, (notostraca: triopsidae), on the efficacy of the microbial control agent bacillus thuringiensis var. israelensis in experimental microcosms. | laboratory bioassays using culex quinquefasciatus larvae evaluated the effect of tadpole shrimp on the persistence of bacillus thuringiensis var. israelensis (b.t.i.) in water collected from the surface of field microcosms. time elapsed since b.t.i. treatment, as well as presence or absence of soil and tadpole shrimp, affected b.t.i. persistence at the water surface in 15- and 30-cm total depths. the presence of tadpole shrimp slowed the natural decline in b.t.i. effectiveness over time, but thi ... | 1996 | 8723255 |