Meeting Abstract

P3-166  Saturday, Jan. 7 15:30 – 17:30  Effects of ambient temperature on the organization of lipids of the avian stratum corneum PIGG, VA*; CHAMPAGNE, AM; ALLEN, HC; WILLIAMS, JB; University of Southern Indiana; University of Southern Indiana; The Ohio State University; The Ohio State University vapigg@eagles.usi.edu

The stratum corneum (SC) is the outermost layer of skin in birds, and is composed of corneocytes embedded in a matrix of lipids. These lipids are arranged in phase states ranging from highly ordered orthorhombic phase to a more disordered liquid phase. The specific phase state of lipids in the SC may determine the rate of cutaneous water loss (CWL), with the orthorhombic phase providing the greatest barrier to water loss, whereas more disordered phases allow for higher rates of water permeation. In this study, we captured House Sparrows (Passer domesticus) in winter and summer in central Ohio. After isolating the SC, we used infrared (IR) spectroscopy to assess the phase state of SC lipids from 25 to 50°C. Analysis of the CH₂ scissoring region revealed that lipids in the SC of birds exist predominantly in the orthorhombic phase at these temperatures and only a subset of lipids change phase as temperature increases. This minor phase change corresponds with the minor increase in CWL observed in passerines as temperature rises. Additionally, our results imply that lipids in the skin of some birds are more robust to temperature changes than lipids in mammalian SC, suggesting a fundamental difference in lipid organization.