The insect exoskeleton is primarily composed of two structural polymers, protein and the polysaccharide chitin. At each stage of development an insect must produce an exoskeleton with the proper combination of mechanical properties (strength, hardness, flexibility) that affords structural support, protection and mobility. This is accomplished in part by chemical modifications of the structural polymers in a process known as tanning or sclerotization. This interdisciplinary project will make use of genetics, genomics, proteomics, biochemistry, molecular biology, and materials science to investigate the sclerotization process in the red flour beetle, Tribolium castaneum. The collaborative research team will test the hypothesis that differences in physical properties of cuticle from distinct regions of an exoskeleton are promoted by the occurrence of different sets of proteins and cross-linking agents expressed by the underlying epidermis, which become organized into different nanostructures. This hypothesis will be tested in part by the use of RNA interference to selectively suppress expression of genes of structural proteins and enzymes postulated to be involved in sclerotization. Resulting phenotypes will be evaluated qualitatively by insect viability and optical and scanning electron microscopy and quantitatively by dynamic mechanical analysis and atomic force microscopy. Broader impacts resulting from the research will include education and training for undergraduate, graduate, and postdoctoral students. Specific efforts at broadening opportunities for participation in science will include involvement of undergraduate students from Haskell Indian Nations University in the research at KU and outreach to middle school and high school girls through programs of the Women in Engineering and Science Program at KSU. The results from this project will lead to a better fundamental understanding of insect cuticle sclerotization, a plausible target for design of novel biorational methods for selective control of insect pests and a template for design of novel nanostructured materials.
