Development of an Insect Gut-Specific DNA Microarray to Assess
Genomic Responses to Bt Toxins

Kun Yan Zhu, Entomology
Lawrent L. Buschman, Entomology
Ming-Shun Chen, Entomology
Subbaratnam Muthukrishnan, Department of Biochemistry

Project Summary
Transgenic Bacillus thuringiensis (Bt) corn hybrids have been successfully used to control the
European corn borer (ECB, Ostrinia nubilalis) in the U.S. and many other countries. However,
the development of Bt resistance in ECB under the laboratory selection raised serious concerns
about the long-term durability of Bt protein toxins. Although many enzymes, receptors, and other
proteins involved in Bt protoxin activation, toxin binding, and protoxin/toxin degradations can
affect Bt efficacy and lead to the development of Bt resistance in insects, we know surprisingly
little about physiological responses of target insects to Bt toxins upon Bt ingestion. Application
of DNA microarray technology for gene expression profiling promises a significant advance in
understanding basic physiology of Bt toxin-insect gut interactions and the mechanisms of Bt
resistance in insects. Our long-term goal is to analyze the global change of gene expression in
response to Bt toxins as well as the genetic difference between Bt-resistant and -susceptible
strains of ECB. Our specific aims of this pilot project are to: 1) sequence 6,000 more cDNA
clones from our ECB gut cDNA library; and 2) develop an ECB gut-specific spotted microarray
using the cDNA sequences. The project will allow us to generate preliminary gene expression
data in Bt-susceptible and -resistant strains of ECB for attracting extramural funding. The power
of our future projects will lie in: 1) the application of novel research tools (ECB gut-specific
cDNA microarray) developed in this project; 2) our new research collaborations established
through this pilot project; and 3) our nationally recognized research in Bt-resistance of ECB
established during the last decade. If this project is funded, we will become the first research
team to address this important problem using an insect gut-specific DNA microarray. All these
will put our research team in a significant advantage to attract extramural funding (e.g., USDANRI).