Detection of endogenous lipids in chicken feathers distinct from preen gland constituents
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ORIGINAL ARTICLE
Detection of endogenous lipids in chicken feathers distinct from preen gland constituents Viktoria Zeisler-Diehl 3 & Eshrak Ali Ali Al-Khutabi 2 & Gregor Kirfel 1 & Lukas Schreiber 3 & Gerhild van Echten-Deckert 2 & Volker Herzog 1 Received: 11 June 2020 / Accepted: 6 August 2020 # The Author(s) 2020
Abstract Bird feather lipids are usually attributed to the oily secretion product of the uropygial (preen) gland. We have observed, however, that feathers exhibit a strong reaction with osmium tetroxide (OsO4), even after treatment with detergents. This leads us to postulate the existence of endogenous feather lipids distinct from preen gland lipids. In order to substantiate our hypothesis, we investigated down feathers from a 1-day-old chicken as their uropgygial gland is not functionally active. The results confirmed the osmiophilic reaction, which was concentrated in the center of barbs and strongly reduced after lipid extraction. In these lipid extracts, we identified using thin layer chromatography, cholesterol, various ceramides, glycolipids, phospholipids, and fatty acids, which closely resembled the lipid composition of the water barrier in the chicken-cornified epidermal envelope. This composition is clearly distinct from chicken uropygeal gland secretion (UGS) known to consist of fatty alcohols as part of aliphatic monoester waxes and of free, predominantly saturated, fatty acids. A filter assay showed a strong reactivity between OsO4 and the fatty acids C18:1 and C18:2 and with feather lipid extracts, but not with UGS. These observations were confirmed by gas chromatography detecting unsaturated fatty acids including C18:1 and C18:2 as well as cholesterol exclusively in chicken feathers. Our results indicate that (1) endogenous lipids are detectable in chicken feathers and distinct from UGS and (2) in analogy to the morphogenesis of the cornified envelope of chicken feather lipids that may have derived from cellular featherprecursors, apparently enduring the specific cell death during developmental feather cornification. Keywords Feather lipids . Osmium tetroxide . Thin layer chromatography . Gas chromatography . Cholesterol . Unsatured fatty acids
Introduction Feathers are part of the defining traits of modern birds and structurally as well as compositionally unique integumentary Handling Editor: Georg Krohne Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00709-020-01544-7) contains supplementary material, which is available to authorized users. * Volker Herzog [email protected] 1
Institut für Zellbiologie, Ulrich-Haberland-Str. 61A, D-53121 Bonn, Germany
2
LIMES-Institut für Membranbiologie und Lipidbiochemie, Universität Bonn, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany
3
Ökophysiologie der Pflanzen, Institut für Zelluläre und Molekulare Botanik, Universität Bonn, Kirschallee 1, D-53115 Bonn, Germany
appendages which serve a variety of distinct functions: they protect birds as well as their eggs and fledglings from cold temperatur
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