Collaborative Research: Sclerotization Mechanisms that Control Physical Properties of Insect Cuticle

昆虫外骨骼主要由蛋白质和多糖几丁质两种结构聚合物组成。在发育的每个阶段，昆虫都必须产生具有适当机械性能（强度、硬度、柔韧性）的外骨骼，以提供结构支撑、保护和移动能力。这部分是通过在鞣制或硬化过程中对结构聚合物进行化学修饰来完成的。本项目将综合运用遗传学、基因组学、蛋白质组学、生物化学、分子生物学和材料科学等多种学科，研究红粉甲虫（Tribolium castaneum）的硬化过程。该合作研究团队将测试这样一种假设，即外骨骼不同区域角质层的物理特性差异是由下层表皮表达的不同蛋白质和交联剂的出现所促进的，这些蛋白质和交联剂被组织成不同的纳米结构。这一假设将在一定程度上通过使用RNA干扰来选择性地抑制被认为与硬化有关的结构蛋白和酶的基因表达来验证。由此产生的表型将通过昆虫活力和光学和扫描电子显微镜进行定性评估，并通过动态力学分析和原子力显微镜进行定量评估。这项研究产生的更广泛的影响将包括对本科生、研究生和博士后的教育和培训。扩大科学参与机会的具体努力将包括让哈斯克尔印第安民族大学的本科生参与堪萨斯大学的研究，并通过堪萨斯大学工程与科学项目的妇女项目向初高中女生伸出援手。该项目的结果将有助于更好地了解昆虫角质层硬化，为设计新的生物方法来选择性控制害虫和设计新型纳米结构材料提供一个可行的目标。

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.