J. -L. Schwartz

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The combined effects of ionic strength, divalent cations, pH and toxin concentration on the pore-forming activity of Cry1Ac and Cry1Ca were studied using membrane potential measurements in isolated midguts of Manduca sexta and a brush border membrane vesicle osmotic swelling assay. The effects of ionic strength and divalent cations were more pronounced at(More)
A potential-sensitive fluorescent probe, 3,3′-dipropylthiadicarbocyanine iodide, was used to analyze, at pH 7.5 and 10.5, the effects of Bacillus thuringiensis toxins on the membrane potential generated by the efflux of K+ ions from brush border membrane vesicles purified from the midgut of the tobacco hornworm, Manduca sexta. Fluorescence levels were(More)
A professionally designed telephone survey was conducted, for the first time in any country, to determine the perception of Canadians to the use of biocontrol as a means of pest management. While only 55% of those contacted considered themselves well versed in biological control, over 80% were interested in the environment and nutrition. Women expressed(More)
The effect of Bacillus thuringiensis insecticidal toxins on the monovalent cation content and intracellular pH (pH i ) 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(More)
The apical brush border membrane, the main target site of Bacillus thuringiensis toxins, was isolated from gypsy moth (Lymantria dispar) larval midguts and fused to artificial planar lipid bilayer membranes. Under asymmetrical N-methyl-d-glucamine-HCl conditions (450 mm cis/150 mm trans, pH 9.0), which significantly reduce endogenous channel activity,(More)
A sensitive immunoradiometric assay for recombinant alpha-2 interferon (IFN-alpha 2; SCH 30500) was developed by using the monoclonal antibody NK2. A polystyrene bead with polyclonal sheep anti-human IFN-alpha (Hu IFN-alpha) antibody adsorbed to it formed the solid phase of the assay. The monoclonal antibody, labeled with 125I, reacted with the IFN-alpha 2(More)
The high larvicidal effect of Bacillus sphaericus (Bs), a mosquito control agent, originates from the presence of a binary toxin (Bs Bin) composed of two proteins (BinA and BinB) that work together to lyse gut cells of susceptible larvae. We demonstrate for the first time that the binary toxin and its individual components permeabilize receptor-free large(More)
The cytotoxic responses of midgut epithelial cells (MEC) from spruce budworm (SBW), gypsy moth (GM) and silkworm (SW) larvae were compared with the cytotoxic response of lepidopteran cell lines (SF-9, SE-1a, and CF-1) to CryIA toxins from Bacillus thuringiensis. The MEC from SBW, SW and GM had binding proteins for CryIA(a,b,c) toxins, whereas the(More)
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