Due to the shear forces involved in the digestive process, the intestinal epithelium has one of the highest rates of cell renewal, and epithelial integrity is preserved by tissue healing mechanisms controlled by stem cell proliferation and differentiation. In the insect midgut epithelium, this healing process is only active during molting or following injury and has been hypothesized that it is a mechanism of resistance to biological insecticides. The main goal of this project is the identification of the specific growth factors activating the midgut epithelium healing response and the characterization of alterations in this process that result in resistance to toxins. The study will be focused on the regenerative response elicited in midguts from Heliothis virescens caterpillar (tobacco budworm) after being challenged with Cry toxins from the bacterium, Bacillus thuringiensis. Primary midgut cell cultures will be used as the experimental model and the factors activating their differentiation to mature cells upon Cry toxin treatment will be identified using a combination of liquid chromatography, stem cell differentiation assays, and gel-based differential proteomics. Following this approach, alterations in the midgut regenerative response in Cry-resistant tobacco budworms will also be characterized. Identification of the factors activating midgut regeneration will provide relevant information on control of epithelial healing by stem cells and greatly benefit the scientific community by providing tools to control cell culture renewal for developing stable midgut cell lines. The broader impacts of this project also include the identification of crucial healing pathways for the development of novel biocontrol methods and insecticides. A minority graduate student will be trained in state-of-the-art proteomic and cell culturing technologies and this training will provide a solid core of tools to pursue future research opportunities in biological and medical research fields. Both the principal investigator and the student will present the results of this project during community outreach events at local educational institutions serving underrepresented groups in order to foster an interest in participating in scientific research.
