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 performed for each toxin. The values obtained correlate well with the LD50 determined by bioassay. 4. This amino acid inhibition test could represent a rapid (3-6 hr, compared to 3-4 days for bioassay) and sensitive method for the screening of larvicidal activity of known or new recombinant delta-endotoxins.
Department of General Physiology and Biochemistry, University of Milan, Italy.
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D000818:Animals; D001413:Bacillus thuringiensis; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D001681:Biological Assay; D012831:Bombyx; D004731:Endotoxins / Q000032:analysis* / Q000633:toxicity; D006460:Hemolysin Proteins; D006639:Histidine / Q000378:metabolism; D007814:Larva; D007928:Lethal Dose 50; D008871:Microvilli / Q000187:drug effects* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D013861:Thiocyanates / Q000494:pharmacology; D014634:Valinomycin / Q000494:pharmacology
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D013861:Thiocyanates; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D014634:Valinomycin; D006639:Histidine; D011188:Potassium; C009941:potassium thiocyanate