Electron microscopic visualization of transcribed genes in the nucleus of Amoeba proteus

An electron microscopic examination by Miller's technique of nuclei of Amoeba proteus has revealed two types of transcriptionally active genes. The putative nucleolar genes have an average length of 6.07 μm and are transcribed throughout their entire length. On occasion a second type of active gene is observed as discrete regions on long chromatin fibers. These regions measure 3.21 μm and are not tandemly repeated. We have used Miller's technique [1–3, 13] to observe the transcriptionally active genes in the nucleus of the unicellular protozoan, Amoeba proteus. We report here preliminary observations on the morphology of two types of structures that are interpreted as transcriptionally active genes.