Electron Microscope Tomography: Transcription in Three Dimensions

作者：Donald E. Olins, Ada L. Olins, Henri A. Lévy, Richard C. Durfee, Stephen M. Margle, Ed P. Tinnel, S. David Dover · 发表于：Science · 年份：1983 · DOI：10.1126/science.6836293 · 被引用次数：133 · 研究领域：Magnetic and Electromagnetic Effects、Physiological and biochemical adaptations、RNA and protein synthesis mechanisms

Three-dimensional reconstruction of an asymmetric biological ultrastructure has been achieved by tomographic analysis of electron micrographs of sections tilted on a goniometer specimen stage. Aligned micrographs could be displayed as red-green three-dimensional movies. The techniques have been applied to portions of in situ transcription units of a Balbiani ring in the polytene chromosomes of the midge Chironomus tentans. Current data suggest a DNA compaction of about 8 to 1 in a transcription unit. Nascent ribonucleoprotein granules display an imperfect sixfold helical arrangement around the chromatin axis.