Margaret E. Bisher and Soyeon Im
Department of Molecular Biology
The “fairies” in the image above occurred unexpectedly in a sample of protein filaments. They were visible in addition to the expected rope-like structures. The “fairies” showed up again a few weeks later, in other protein filament samples. They are likely staining artifacts: a result of the stain precipitating on the carbon film that supports the sample. These odd structures form randomly and very intermittently.
The original protein filament sample itself was in a solution or buffer that was absorbed onto a grid (a mesh-like structure 3mm in diameter) with a carbon support film across it, approximately 50 Angstroms thick. The sample was washed with water and then stained with 1% uranyl acetate. It was then viewed at 80kV on a Zeiss 912AB transmission electron microscope equipped with an Omega energy filter.