Meeting Abstract
The outermost layer of skin, the stratum corneum (SC), protects the body from mechanical abrasion, pathogens, and excessive water loss. The SC is 10-20 µm thick and is composed of corneocytes embedded in a lipid matrix. These lipids help maintain the barrier function of the skin, and in most mammals consist of ceramides, free fatty acids, and cholesterol. However, bat SC contains a more diverse group of lipids including cerebrosides, ceramides with a sugar moiety attached to the headgroup. This lipid composition resembles avian stratum corneum, and may indicate convergent evolution between bats and birds. We used infrared spectroscopy to investigate the conformation of lipid chains in the SC of the big brown bat (Eptesicus fuscus) at 5° intervals from 15-50° C. Additionally, we exposed the SC to different vapor pressures and measured changes in hydrogen bonding properties as a function of hydration. We found that lipid chains in bat SC respond to temperature in a manner more similar to lipids in avian SC than lipids in the SC of most mammals. Furthermore, the presence of cerebrosides may affect hydrogen bonding interactions between lipids and water in the SC. The similarities between bird and bat SC may be a result of selection to maintain barrier function while simultaneously meeting the mechanical demands of flight.
