Meeting Abstract
108.7 Tuesday, Jan. 7 09:45 Seasonal differences in the organization of lipids and water through the stratum corneum of birds CHAMPAGNE, AM*; ALLEN, HC; WILLIAMS, JB; Ohio State University; Ohio State University; Ohio State University champagne.7@osu.edu
Accounting for over half of total water loss in birds, cutaneous water loss is regulated by lipids in the stratum corneum (SC), the outermost layer of the epidermis. The SC is composed of layers of corneocytes each embedded in a lipid matrix. The relative abundance of lipid classes within this matrix may affect the barrier properties of the SC. Because most studies of the SC assume that lipid composition remains constant through the entire thickness of the SC, little is known about how differences in lipid composition between different layers of the SC affect CWL. We tested the hypothesis that CWL differs between seasons, and that these differences are associated with variation in lipid organization within different layers of the SC. We captured House Sparrows (Passer domesticus) in the summer and winter in Ohio and measured their CWL. We then used attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to measure water content and water and lipid organization in the SC for 10 layers of approximately 1 μm each, thus obtaining a depth profile of the full thickness of the SC. We found that birds captured in the winter had lower rates of CWL than birds captured in the summer. Our ATR-FTIR studies revealed that although both groups retained more water and had greater lipid disorder in deeper layers of the SC than in superficial layers, birds captured in the winter retained less water overall and the decrease in water and lipid disorder from deeper to more superficial layers was reduced compared with summer-caught birds. These data indicate that birds can alter the lipid composition of different layers of the stratum corneum to reduce water content and lipid disorder during the winter, when the ambient vapor pressure is low.
