Estimation of RNA Content of the Nucleolus and Nucleolus-derived Structures in <italic>Vicia faba</italic> Mitotic Cells Embedded in Lowicryl Resin Using RNase-gold Labeling

Abstract

RNase-gold labeling was applied to Vicia faba meristematic cells embedded in hydrophilic Lowicryl K4M resin, and the label was examined over various cell structures with special focus on the nucleolus and nucleolus-derived structures. RNA-containing structures or regions like the nucleolus and cytoplasm were most heavily labeled whereas the vacuoles, mitochondria, and cell walls almost entirely lacked gold particles. The gold labeling ratio of the nucleolus to condensed chromatin reached about 5.4. Treatment with RNase-gold labeling remarkably reduced the presence of gold particles in the nucleolus and cytoplasm. During prophase, nucleolar remnants were specifically labeled, while the space between chromosomes was covered with very few gold particles. Prenucleolar material accumulated on late anaphase chromosomes possessed far fewer gold particles than the nucleolus. Interestingly, the prenucleolar material remained poorly labeled, while the nucleoli constructed from it contained large amounts of gold particles