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 feather-precursors, apparently enduring the specific cell death during developmental feather cornification.

中文翻译：

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检测鸡毛中不同于瘿腺成分的内源性脂质

鸟羽脂质通常归因于尾尾（preen）腺的油性分泌产物。然而，我们观察到羽毛与四氧化锇 (OsO4) 发生强烈反应，即使在用洗涤剂处理后也是如此。这使我们假设存在不同于绦虫腺脂质的内源性羽毛脂质。为了证实我们的假设，我们调查了一只 1 日龄鸡的羽绒，因为它们的泌尿腺功能不活跃。结果证实了嗜锇反应，它集中在倒钩的中心，在脂质提取后强烈减少。在这些脂质提取物中，我们使用薄层色谱法鉴定了胆固醇、各种神经酰胺、糖脂、磷脂和脂肪酸，这与鸡角化表皮包膜中水屏障的脂质组成非常相似。该组合物明显不同于已知由作为脂肪族单酯蜡的一部分的脂肪醇和游离的、主要是饱和的脂肪酸组成的鸡尿尾腺分泌物(UGS)。过滤试验显示 OsO4 与脂肪酸 C18:1 和 C18:2 以及羽毛脂质提取物之间有很强的反应性，但与 UGS 没有反应。这些观察结果通过气相色谱检测不饱和脂肪酸（包括 C18:1 和 C18:2）以及仅存在于鸡羽毛中的胆固醇得到证实。