Adeyeye 9727813 The success of arthropods as terrestrial animals is attributable partly to their cuticle, a versatile structure that acts as a covering and skeleton. Ticks belonging to the genus Ornithodoros can live for many years even when starved. Moreover, the relapsing fever tick, Ornithodoros tuncaln, shows remarkable resistance to desiccation. This project will investigate whether and how the cuticle of 0. Turicata is biochemically modified in order to cope with starvation and/or desiccation. Comprehensive biochemical analyses of fed and starved 0. turicata cuticle will be conducted. In particular, proteins of interest will be purified and characterized using various techniques. Also cuticular lipids of sequentially starved ticks will be analyzed. The cuticular permeability will be determined and its possible correlation with changes in cuticular lipids and proteins will be ascertained. Two other ticks that differ in cuticular permeability and in starvation/desiccation hardiness shall be studied to permit broader generalization about the role of cuticular proteins and lipids in the of 0. turicata resisting desiccation. Because so little is known about the chemistry of the cuticle of soft ticks, the proposed studies will expand existing knowledge vis-a-vis the structure and functions of tick cuticle.