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Summary: Many roads to resistance: how
invertebrates adapt to Bt toxins
Joel S. Griffitts and Raffi V. Aroian*
Summary
The Cry family of Bacillus thuringiensis insecticidal and
nematicidal proteins constitutes a valuable source of
environmentally benign compounds for the control of
insect pests and disease agents. An understanding of Cry
toxin resistance at a molecular level will be critical to the
long-term utility of this technology; it may also shed light
on basic mechanisms used by other bacterial toxins that
target specific organisms or cell types. Selection and
cross-resistance studies have confirmed that genetic
adaptation can elicit varying patterns of Cry toxin resis-
tance, which has been associated with deficient protoxin
activation by host proteases, and defective Cry toxin-
binding cell surface molecules, such as cadherins,
aminopeptidases and glycolipids. Recent work also
suggests Cry toxin resistance may be induced in inverte-
brates as an active immune response. The use of model
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