Search results for "Bacillus"
showing 10 items of 774 documents
Lack of Cry1Fa binding to the midgut brush border membrane in a resistant colony of Plutella xylostella moths with a mutaton in the ABCC2 locus
2012
ABSTRACT Previous studies reported “mode 1” Bacillus thuringiensis resistance in a colony of diamondback moths (NO-QA), and recently, this resistance has been mapped to an ABC transporter ( ABCC2 ) locus. We report the lack of binding of Cry1Fa to insects derived from this colony and compare our data with those from other insects with ABCC2 -associated resistance.
Interaction of Bacillus thuringiensis Cry1 and Vip3A Proteins with Spodoptera frugiperda Midgut Binding Sites
2009
ABSTRACT Vip3Aa, Vip3Af, Cry1Ab, and Cry1Fa were tested for their toxicities and binding interactions. Vip3A proteins were more toxic than Cry1 proteins. Binding assays showed independent specific binding sites for Cry1 and Vip3A proteins. Cry1Ab and Cry1Fa competed for the same binding sites, whereas Vip3Aa competed for those of Vip3Af.
Specific binding of radiolabeled Cry1Fa insecticidal protein from Bacillus thuringiensis to midgut sites in lepidopteran species
2012
ABSTRACT Cry1Fa insecticidal protein was successfully radiolabeled with 125 I-Na. Specific binding to brush border membrane vesicles was shown for the lepidopteran species Ostrinia nubilalis , Spodoptera frugiperda , Spodoptera exigua , Helicoverpa armigera , Heliothis virescens , and Plutella xylostella . Homologous competition assays were performed to obtain equilibrium binding parameters ( K d [dissociation constant] and R t [concentration of binding sites]) for these six insect species.
Isolation and toxicity of Bacillus thuringiensis from potato-growing areas in Bolivia
2004
Bacillus thuringiensis was isolated from 116 samples collected in high altitude potato-growing areas in Bolivia. In these regions, main potato pests are the potato tuberworm Phthorimaea operculella, and the Andean weevils Premnotrypes latithorax and Rhigopsidius tucumanus. B. thuringiensis was found in 60% of the samples. The main percentage of samples with B. thuringiensis was found in larvae of R. tucumanus (78%). Bioassays were performed with 112 isolates. None resulted toxic to either larvae or adults of the two Andean weevils. However, 18 isolates from this study showed more toxicity against the beet armyworm Spodoptera exigua than the standard strain var. kurstaki isolated from DELFIN…
Probiotic characterization of Lactobacillus strains isolated from breast milk and employment for the elaboration of a fermented milk product
2021
Abstract A total of seven strains of lactic acid bacteria (LAB) isolated from breast milk, were investigated for their probiotic properties. Lactobacillus plantarum 5H1 and 5L1 were selected for their beneficial properties and used for probiotic fermented milk manufacture. The fermentation parameters (pH and lactic acid) and LAB viability during fermented milk processing and storage were evaluated. The results showed that the strains had a broad spectrum of antimicrobial activity against pathogenic bacteria and toxigenic fungi. These also evidenced capacity of adhesion and reduction of Salmonella adhesion to Caco-2 cells. During milk fermentation process, an increase in lactic acid content,…
Shared Binding Sites for the Bacillus thuringiensis Proteins Cry3Bb, Cry3Ca, and Cry7Aa in the African Sweet Potato Pest Cylas puncticollis (Brentida…
2014
ABSTRACT Bacillus thuringiensis Cry3Bb, Cry3Ca, and Cry7Aa have been reported to be toxic against larvae of the genus Cylas , which are important pests of sweet potato worldwide and particularly in sub-Saharan Africa. However, relatively little is known about the processing and binding interactions of these coleopteran-specific Cry proteins. The aim of the present study was to determine whether Cry3Bb, Cry3Ca, and Cry7Aa proteins have shared binding sites in Cylas puncticollis to orient the pest resistance strategy by genetic transformation. Interestingly, processing of the 129-kDa Cry7Aa protoxin using commercial trypsin or chymotrypsin rendered two fragments of about 70 kDa and 65 kDa. N-…
Lyophilization of lepidopteran midguts: a preserving method for Bacillus thuringiensis toxin binding studies
2004
Binding assays with brush border membrane vesicles (BBMV) from insect midguts are commonly used in the study of the interactions between Bacillus thuringiensis Cry toxins and their receptors. Collaboration between laboratories often require that frozen insect samples are sent in dry ice. Because of customs restrictions and delays, sample thawing is always a risk and often the biological material becomes ruined during shipping. We have tested lyophilization as an alternative method for preserving insect midguts for binding studies with B. thuringiensis Cry toxins. For this purpose, BBMV were prepared from both frozen and lyophilized midguts from three lepidopteran species: Spodoptera exigua,…
Immunohistochemical Detection of Binding of Cryia Crystal Proteins of Bacillus thuringiensis in Highly Resistant Strains of Plutella xylostella (L.) …
1995
We detected binding of insecticidal crystal proteins from Bacillus thuringiensis in one susceptible strain and six resistant strains of diamondback moth, Plutella xylostella, from Hawaii. Immunohistochemical tests with tissue sections from larval midguts showed specific binding of CryIA(a), CryIA(b), and CryIA(c) to brush border membranes. CryIE, which is not toxic to P. xylostella, did not bind to midgut tissues. Larvae from one of the resistant strains ingested extremely high concentrations of a commercial formulation containing the three CryIA proteins without suffering midgut cell damage or mortality. This same resistant strain had previously been found to have greatly reduced binding o…
Selective inhibition of binding of Bacillus thuringiensis Cry1Ab toxin to cadherin-like and aminopeptidase proteins in brush-border membranes and dis…
2007
Binding analyses with denatured epithelial membrane proteins from Bt (Bacillus thuringiensis) demonstrated at least two kinds of proteins, APNs (aminopeptidases N) and cadherin-like proteins, as possible receptors for the Cry1A class of Bt toxins. Two alternative models have been proposed, both based on initial toxin binding to a cadherin-like protein, but one involving APN and the other not. We have used two Bombyx mori strains (J65 and Kin), which are highly susceptible to Cry1Ab, to study the role of these two types of receptors on Cry1Ab toxin binding and cytotoxicity by means of the inhibitory effect of antibodies. BBMVs (brush-border membrane vesicles) of strain J65 incubated with lab…
Binding of Bacillus thuringiensis toxins in resistant and susceptible strains of pink bollworm (Pectinophora gossypiella)
2003
Abstract Evolution of resistance by pests could cut short the success of transgenic plants producing toxins from Bacillus thuringiensis, such as Bt cotton. The most common mechanism of insect resistance to B. thuringiensis is reduced binding of toxins to target sites in the brush border membrane of the larval midgut. We compared toxin binding in resistant and susceptible strains of Pectinophora gossypiella, a major pest of cotton worldwide. Using Cry1Ab and Cry1Ac labeled with 125I and brush border membrane vesicles (BBMV), competition experiments were performed with unlabeled Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba, Cry1Ca, Cry1Ja, Cry2Aa, and Cry9Ca. In the susceptible strain, Cry1Aa, Cry1Ab, Cry1…