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Theses/Dissertations

Graduate Theses and Dissertations

2014

Iowa State University

Pharmacology, Toxicology and Environmental Health

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Full-Text Articles in Molecular Biology

Modification Of The Bt Toxin Cry4aa For Improved Toxin Processing In The Gut Of The Pea Aphid (Acyrthosiphon Pisum), Michael Allen Rausch Jan 2014

Modification Of The Bt Toxin Cry4aa For Improved Toxin Processing In The Gut Of The Pea Aphid (Acyrthosiphon Pisum), Michael Allen Rausch

Graduate Theses and Dissertations

Aphids are sap-sucking insects (order: Hemiptera) that cause extensive damage to a wide range of agricultural crops. Our goal is to produce a "designer" toxin based on naturally occurring insecticidal crystalline (Cry) toxins produced by the soil-dwelling bacterium Bacillus thuringiensis for use against the pea aphid, Acyrthosiphon pisum. On the basis that activation of the Cry4Aa protoxin could be a rate-limiting factor contributing to the relatively low aphicidal activity of this toxin, we introduced cathepsin L and cathepsin B cleavage sites into Cry4Aa for rapid activation and generation of the active toxin in the aphid gut environment. Incubation of modified ...