Effects of the Bacillus thuringiensis Toxin Cry1Ab on Membrane Currents of Isolated Cells of the Ruminal Epithelium

Effects of the Bacillus thuringiensis Toxin Cry1Ab on Membrane Currents of Isolated Cells of the... A previous study has shown that Cry1Ab, a lepidopteran-specific toxin derived from Bacillus thuringiensis, does not affect the vitality of cultured cells of the ruminal epithelium of the sheep. While this may be due to lack of specific receptors for toxin action, other mechanisms of resistance should also be considered. In order to directly assess the pore-forming potential of Cry1Ab, we studied the interaction of this toxin with isolated, perfused cells of the ruminal epithelium using the whole-cell and single-channel configurations of the patch-clamp technique. At concentrations found in vivo in the rumen of cows (<10 ng/ml) and at a temperature of 37°C, no significant effects of Cry1Ab could be observed. At 100 ng/ml, exposure of ruminal cells to Cry1Ab induced a significant rise in outward current in 16 of 34 cells, with a fourfold increase in the conductance for potassium. The cell membrane remained selective for potassium over sodium (p[K]/p[Na] = 1.8 ± 0.3), with a considerable additional chloride conductance. In outside-out patches, exposure to high Cry1Ab concentrations induced channel-like events that reached levels of over 500 pS. We conclude that the unchanged vitality of intact ruminal epithelial cells exposed to Cry1Ab in vitro at high concentrations may be related to other factors besides the proposed absence of a specific receptor for the membrane insertion of this toxin. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Effects of the Bacillus thuringiensis Toxin Cry1Ab on Membrane Currents of Isolated Cells of the Ruminal Epithelium

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Publisher
Springer-Verlag
Copyright
Copyright © 2007 by Springer Science+Business Media, LLC
Subject
Life Sciences; Human Physiology ; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-007-9059-3
Publisher site
See Article on Publisher Site

Abstract

A previous study has shown that Cry1Ab, a lepidopteran-specific toxin derived from Bacillus thuringiensis, does not affect the vitality of cultured cells of the ruminal epithelium of the sheep. While this may be due to lack of specific receptors for toxin action, other mechanisms of resistance should also be considered. In order to directly assess the pore-forming potential of Cry1Ab, we studied the interaction of this toxin with isolated, perfused cells of the ruminal epithelium using the whole-cell and single-channel configurations of the patch-clamp technique. At concentrations found in vivo in the rumen of cows (<10 ng/ml) and at a temperature of 37°C, no significant effects of Cry1Ab could be observed. At 100 ng/ml, exposure of ruminal cells to Cry1Ab induced a significant rise in outward current in 16 of 34 cells, with a fourfold increase in the conductance for potassium. The cell membrane remained selective for potassium over sodium (p[K]/p[Na] = 1.8 ± 0.3), with a considerable additional chloride conductance. In outside-out patches, exposure to high Cry1Ab concentrations induced channel-like events that reached levels of over 500 pS. We conclude that the unchanged vitality of intact ruminal epithelial cells exposed to Cry1Ab in vitro at high concentrations may be related to other factors besides the proposed absence of a specific receptor for the membrane insertion of this toxin.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Aug 5, 2007

References

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