Meeting Abstract

P2.19  Saturday, Jan. 5  Tests on the organization of lipids in the avian stratum corneum CHAMPAGNE, AM*; ALLEN, HC; WILLIAMS, JB; Ohio State University; Ohio State University; Ohio State University champagne.7@osu.edu

Cutaneous water loss (CWL) accounts for over half of all evaporative water loss in birds. The barrier to water loss through the skin is the stratum corneum (SC), the outermost layer of the epidermis, composed of corneocytes embedded in a lipid matrix of cholesterol esters, fatty acid methyl esters, triacylglycerides, free fatty acids, cholesterol, ceramides, and cerebrosides. The relative abundance of these lipid classes may affect the barrier properties of the lipid matrix by affecting the ability of the lipid molecules to pack together or interact with water molecules to prevent CWL. In this study, we acclimated House Sparrows (Passer domesticus) to different temperature and humidity regimes and measured their CWL at different ambient temperatures. We then used infrared (IR) spectroscopy to measure lipid-lipid and lipid-water interactions in extracted SC of these birds at different temperatures and hydration levels. We found that in all groups, CWL increased at higher temperatures, and these changes were associated with a disordering of lipid hydrocarbon chains. Furthermore, as the SC was hydrated, lipid chain order did not change, suggesting that hygroscopic lipid moieties lie outside of lipid lamellae, rather than inside as has previously been suggested.