Hill R S, Myring W J, Clarke D T, Veltkamp C J
Department of Genetics, University of Liverpool.
J Microsc. 1988 Feb;149(Pt 2):127-34. doi: 10.1111/j.1365-2818.1988.tb04569.x.
Contact images (CI) of dehydrated, nucleolar chromatin from amphibian oocytes have been produced by soft X-rays from a synchrotron radiation source. These CI have been compared with the morphology of the original chromatin as seen in scanning and transmission electron microscopes. The quality and informational content of the CI depend very much on certain preparative procedures. The following factors have a marked effect on image quality and need to be carefully controlled: the total X-ray dose, the time and nature of development and the distance of the specimen from the photoresist. The preparation of the chromatin itself, providing that it is critically point dried, is less important. By following a regime of high X-ray dose, sufficient for penetration of the rather thick chromatin rings, and gentle development so that fine detail is not dissolved from the resist surface, it has been possible to obtain images which closely resemble the original chromatin, although the detailed resolution of the CI is not as clear. The smallest biological structures clearly resolved in the CI are ribonucleoprotein granules, which vary in size from 200 to 800 nm. However, by further refinement of preparative conditions it should be possible to improve on the informational content of these images.
利用同步辐射源产生的软X射线，获得了两栖类卵母细胞脱水核仁染色质的接触成像（CI）。这些CI已与扫描电子显微镜和透射电子显微镜下观察到的原始染色质形态进行了比较。CI的质量和信息含量在很大程度上取决于某些制备程序。以下因素对图像质量有显著影响，需要仔细控制：总X射线剂量、显影时间和性质以及标本与光刻胶的距离。染色质本身的制备，只要进行临界点干燥，就不那么重要了。通过采用高X射线剂量方案（足以穿透相当厚的染色质环）和温和显影，使精细细节不会从抗蚀剂表面溶解，就有可能获得与原始染色质非常相似的图像，尽管CI的详细分辨率并不清晰。CI中清晰分辨出的最小生物结构是核糖核蛋白颗粒，其大小从200到800纳米不等。然而，通过进一步优化制备条件，应该有可能提高这些图像的信息含量。
