Milligan R A, Brisson A, Unwin P N
Ultramicroscopy. 1984;13(1-2):1-9. doi: 10.1016/0304-3991(84)90051-2.
Images were obtained of eukaryotic ribosome crystals, bladder membranes and gap junctions preserved in frozen aqueous solutions under conditions where either amorphous or crystalline ice is formed. Evaluation of these images by optical diffraction showed that specimens containing the largest open spaces were sensitive to ice crystal damage during freezing, whereas those containing the smallest open spaces were not. Projection maps were calculated from the images and compared to maps obtained from the same specimens at the same resolution in negative stain. Significant differences were apparent between each pair of maps. These were attributed to details being revealed of the RNA and protein (ribosomes) or the complete protein (membranes) when using frozen solutions, compared to just the hydrophilic surfaces when using stain. Thus the freezing method appears to provide the most complete and accurate descriptions of these structures.
获取了在形成非晶态或结晶态冰的条件下保存在冷冻水溶液中的真核核糖体晶体、膀胱膜和间隙连接的图像。通过光学衍射对这些图像进行评估表明，含有最大开放空间的标本在冷冻过程中对冰晶损伤敏感，而含有最小开放空间的标本则不敏感。从图像计算出投影图，并与在相同分辨率下用负染色法从相同标本获得的图进行比较。每对图之间都有明显的差异。这些差异归因于使用冷冻溶液时能揭示RNA和蛋白质（核糖体）或完整蛋白质（膜）的细节，而使用染色时只能揭示亲水表面。因此，冷冻方法似乎能提供对这些结构最完整和准确的描述。
