Pan Yanhong, Zheng Wenxia, Moyer Alison E, O'Connor Jingmai K, Wang Min, Zheng Xiaoting, Wang Xiaoli, Schroeter Elena R, Zhou Zhonghe, Schweitzer Mary H
Key Laboratory of Economic Stratigraphy and Palaeogeography of the Chinese Academy of Sciences, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing 210008, China;
Department of Biological Science, North Carolina State University, Raleigh, NC 27695.
Proc Natl Acad Sci U S A. 2016 Dec 6;113(49):E7900-E7907. doi: 10.1073/pnas.1617168113. Epub 2016 Nov 21.
Microbodies associated with feathers of both nonavian dinosaurs and early birds were first identified as bacteria but have been reinterpreted as melanosomes. Whereas melanosomes in modern feathers are always surrounded by and embedded in keratin, melanosomes embedded in keratin in fossils has not been demonstrated. Here we provide multiple independent molecular analyses of both microbodies and the associated matrix recovered from feathers of a new specimen of the basal bird Eoconfuciusornis from the Early Cretaceous Jehol Biota of China. Our work represents the oldest ultrastructural and immunological recognition of avian beta-keratin from an Early Cretaceous (∼130-Ma) bird. We apply immunogold to identify protein epitopes at high resolution, by localizing antibody-antigen complexes to specific fossil ultrastructures. Retention of original keratinous proteins in the matrix surrounding electron-opaque microbodies supports their assignment as melanosomes and adds to the criteria employable to distinguish melanosomes from microbial bodies. Our work sheds new light on molecular preservation within normally labile tissues preserved in fossils.
与非鸟类恐龙和早期鸟类羽毛相关的微体最初被鉴定为细菌，但现在已被重新解释为黑素体。现代羽毛中的黑素体总是被角蛋白包围并嵌入其中，而化石中嵌入角蛋白的黑素体尚未得到证实。在这里，我们对从中国早白垩世热河生物群的基础鸟类孔子鸟新标本的羽毛中回收的微体和相关基质进行了多项独立的分子分析。我们的工作代表了对白垩纪早期（约1.3亿年前）鸟类的鸟类β-角蛋白的最古老的超微结构和免疫学识别。我们应用免疫金通过将抗体-抗原复合物定位到特定的化石超微结构来高分辨率地识别蛋白质表位。在电子不透明微体周围的基质中保留原始角蛋白表明它们是黑素体，并增加了可用于区分黑素体和微生物体的标准。我们的工作为化石中保存的通常不稳定组织内的分子保存提供了新的线索。
