title: Nucleic acid cytochemistry of the nucleus and microtubule-organizing centers in dictyostelium discoideum.
abstract: We used fluorescence microscopy with DAPI, Hoechst 33258, acridine orange, and ethidium bromide, as well as ultracytochemical regressive staining, the Feulgen-type reaction with osmium-ammine, and the enzyme-gold method to investigate the presence and distribution of DNA and RNA in the nucleoplasm, nucleolus, nucleus-associated body, and spindle pole bodies. We found that the nucleoplasm of interphase nuclei contains mostly DNA dispersed in a fibrillar meshwork, with which some RNA is probably associated as perichromatin granules or fibers. With DNase-gold and RNase-gold the nucleolus, which consists of interspersed fibrillar and granular components, was the most heavily labelled of five cellular compartments analyzed. Accordingly, its fluorescence with acridine orange and ethidium bromide was brightest. In mitotic nuclei the nucleolus was dispersed, filling most of the nuclear volume. Chromosomes were brightly stained by DNA-specific fluorochromes and the osmium-ammine reaction revealed that only the innermost layer of the trilaminar kinetochores contains DNA. Neither the nucleus-associated body of interphase cells nor the spindle pole bodies of mitotic cells contain DNA or RNA.
authors.affiliation: Institut für Pflanzenbiologie, Universität Zürich, Zürich, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Bottini
authors.forename: U P
authors.initials: UP
authors.lastname: Roos