Interaction of two Bacillus thuringiensis delta-endotoxins with the digestive system of Lygus hesperus

The active-toxin form of Cry1Ac (65 kDa) or Cry2Ab was fed to a non-susceptible insect, Lygus hesperus, in an artificial diet. Biochemical and immunocytochemical methods were used to determine the distribution of ingested toxin. The toxins did not elicit a feeding deterrent response. Cry1Ac and Cry2...

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Bibliographic Details
Published in:Current microbiology 2004, Vol.48 (1), p.1-9
Main Authors: Brandt, Sandra L, Coudron, Thomas A, Habibi, Javad, Brown, Gregory R, Ilagan, Oliver M, Wagner, Renee M, Wright, Maureen K, Backus, Elaine A, Huesing, Joseph E
Format: Article
Language:English
Subjects:
Animals
Bacillus thuringiensis
Bacillus thuringiensis - metabolism
Bacterial Proteins - pharmacokinetics
Bacterial Toxins
Blotting, Western
delta-endotoxins
digestive system
Digestive System - drug effects
Digestive System - metabolism
Electrophoresis, Polyacrylamide Gel
Endotoxins - pharmacokinetics
Female
Hemolymph - metabolism
Hemolysin Proteins
immunocytochemistry
Immunohistochemistry
ingestion
Lepidoptera - growth & development
Lepidoptera - metabolism
Lygus hesperus
Microscopy, Fluorescence
nontarget organisms
Pest Control, Biological
protein degradation
proteolysis
Tissue Distribution
toxin susceptibility
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Summary:The active-toxin form of Cry1Ac (65 kDa) or Cry2Ab was fed to a non-susceptible insect, Lygus hesperus, in an artificial diet. Biochemical and immunocytochemical methods were used to determine the distribution of ingested toxin. The toxins did not elicit a feeding deterrent response. Cry1Ac and Cry2Ab were ingested; small amounts were absorbed into the hemolymph as holoproteins, but most was excreted. SDS-PAGE analysis of Cry1Ac and Cry2Ab incubations with salivary gland homogenate showed a small decrease in the molecular weight of the active toxins. Proteolytic processing of the toxins also occurred in vivo, within the digestive system of L. hesperus. Excreted Cry1Ac and Cry2Ab retained activity toward lepidopteran larvae. Immunocytochemical in vivo localization studies showed negligible association of Cry1Ac with L. hesperus tissues. In contrast, strong extracellular association of Cry2Ab was observed with L. hesperus midgut brush border microvilli and basement membrane, as well as with cellular outlines within the hemolymph and fat body.
ISSN:0343-8651
1432-0991
DOI:10.1007/s00284-003-4056-y