TY  - JOUR
A1  - Reimer, Georg
A1  - Raska, Ivan
A1  - Scheer, Ulrich
A1  - Tan, Eng M.
T1  - Immunolocalization of 7-2-ribonucleoprotein in the granular component of the nucleolus
N2  - Certain autoimmune sera contain antibodies against a nucleolar ribonucleoprotein particle associated with 7-2-RNA (R. Reddy et al. (1983) J. Bioi. Chem . 258, 1383; C. Hashimoto and J. A. Steitz (1983) J. Bioi. Chem. 258, 1379). In this study, we showed by immunofluorescence microscopy that antibodies reactive with 7-2-ribonucleoprotein immunolocalized in the granular regions of actinomycin D and 5,6-dichloro-I-j3-D-ribofuranosylbenzimidazole (DRB)-segregated nucleoli from Vero cells. By electron microscopic immunocytochemistry, antigen-antibody complexes were located in the granular component of transcriptionally active nucleoli from rat liver hepatocytes and HeLa cells. Anti-7- 2-RNP antibodies from two autoimmune sera immunoprecipitated a major protein of Mr 40,000 from e5S] methionine-Iabeled HeLa cell extract. The immunolocalization data suggest that 7-2-ribonucleoprotein may be involved in stages of ribosome biogenesis which take place in the granular component of the nucleolus, i.e., assembly, maturation, and/or transport of preribosomes
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33890
ER  - 
TY  - JOUR
A1  - Benavente, Ricardo
A1  - Reimer, Georg
A1  - Rose, Kathleen M.
A1  - Hügle-Dörr, Barbara
A1  - Scheer, Ulrich
T1  - Nucleolar changes after microinjection of antibodies to RNA polymerase I into the nucleus of mammalian cells
N2  - After microinjection of antibodies against RNA polymerase I into the nuclei of cultured rat kangaroo (PtKz) and rat (RVF-SMC) cells alterations in nucleolar structure and composition were observed. These were detected by electron microscopy and double-label immunofluorescence microscopy using antibodies to proteins representative of the three major components of the nucleolus. The microinjected antibodies produced a progressive loss of the material of the dense fibrillar component (DFC) from the nucleoli which, at 4 h after injection, were transformed into bodies with purely granular component (GC) structure with attached fibrillar centers (FCs). Concomitantly, numerous extranucleolar aggregates appeared in the nucleoplasm which morphologically resembled fragments of the DFC and contained a protein (fibrillarin) diagnostic for this nucleolar structure. These observations indicate that the topological distribution of the material constituting the DFC can be experimentally influenced in interphase cells, apparently by modulating the transcriptional activity of the rRNA genes. These effects are different from nucleolar lesions induced by inhibitory drugs such as actinomycin D-dependent "nucleolar segregation". The structural alterations induced by antibodies to RNA polymerase I resemble, however, the initial events of nucleolar disintegration during mitotic prophase.
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-40666
ER  -