Degree Type

Dissertation

Date of Award

2015

Degree Name

Doctor of Philosophy

Department

Entomology

Major

Toxicology

First Advisor

Joel R. Coats

Second Advisor

Richard L. Hellmich

Abstract

The widespread use of Cry proteins in insecticide formulations and transgenic crops for insect control has led to an increased interest in the environmental fate of these proteins. Several detection methods are available to monitor the fate of Cry proteins in the environment, but enzyme-linked immunosorbent assays (ELISAs) have emerged as the preferred detection method, because they are cost-effective, easy to use, and provide rapid results. Validation methodology, which is essential to ensure accurate measurement of Cry proteins in environmental matrices, has been researched extensively, but most of this research has overlooked biological validation of ELISA results. This oversight has led to concerns that environmental studies utilizing ELISAs may be overestimating the concentrations of Cry proteins in the environment, which may affect the risk assessments for these proteins. A literature review discusses the history and usage of Cry proteins for insect pest control and discusses the use and validation of ELISAs for detection of Cry proteins in environmental samples. The concept of biologically validating ELISA results is introduced, and a critical review of published literature examines the state of ELISA usage and validation, including identifying areas for improvement. Eight different types of model systems were screened for their ability to produce fragments of Cry1Ab protein, and five of these model systems prove capable of generating Cry1Ab fragments. The fragments from these five model systems are then analyzed with ELISAs and bioassays to determine if the fragments are detectable or retain bioactivity. Fragments from four of the model systems are not detectable by ELISA and do not retain bioactivity. Fragments from the fifth model system are detectable by ELISA and do retain bioactivity. These results indicate that the use of ELISAs in environmental fate studies are providing an accurate determination of the concentrations of Cry proteins in the environment and are not overestimating the concentrations. However, further work is needed utilizing additional model systems, including microbe-based model systems, in order to fully understand the fate of Cry proteins in the environment.

Copyright Owner

Vurtice Carroll Albright III

Language

en

File Format

application/pdf

File Size

214 pages

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