@article{SpringTrendelenbrugScheeretal.1974,
  author    = {Spring, Herbert and Trendelenbrug, Michael F. and Scheer, Ulrich and Franke, Werner W. and Herth, Werner},
  title     = {Structural and biochemical studies of the primary nucleus of two green algal species, Acetabularia mediterranea and Acetabularia major},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-40600},
  year      = {1974},
  abstract  = {Primary (giant) nuclei of the green algae Acetabularia mediterranea and A. major were studied by light and electron microscopy using in situ fixed material as well as manually isolated nuclear components. In addition, cytochemical reactions of nuclear structures and biochemical determinations of nuclear and cytoplasmic RNA and of genome DNA content were performed. The data obtained and the structures observed are interpreted as demonstralions of transcriptional activities of different gene classes. The most prominent class is the nucleolar cistrons of precursors of ribosomal RNA which occur highly repeated in clusters in the form of regularly alternating intercepts on deoxyribonucleoprotein axes of transcribed rDNA, the fibril-covered matrix units, and the fibril-free "spacer" segments. A description and a classification of the various structural complexes which seem to represent transcriptional activities is given. Quantitative evaluations of these arrangements are presented. The morphology and the dimensions of such structures are compared with the RNA molecular weight determinations and with the corresponding data reported from various animal cell systems. It is suggested that the formation of the giant nucleus is correlated with, and probably due to, an enormous amplification of transcriptionally active rDNA and packing of the extrachromosomal copies into the large nucleolar aggregate bodies.},
  subject      = {Cytologie},
  language  = {en}
}
@inproceedings{TrendelenburgSpringScheeretal.1974,
  author    = {Trendelenburg, Michael F. and Spring, Herbert and Scheer, Ulrich and Franke, Werner W.},
  title     = {Morphology of nucleolar cistrons in a plant cell, Acetabularia mediterranea},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-32213},
  year      = {1974},
  abstract  = {The structural organization of transcriptionally active DNA that contains cistrons for precursor molecules of ribosomal RNA is described in positively stained spread preparations from nuclei and nucleoli isolated from the green alga, Acetabularia mediterranea Lmx. These nuclei contain large aggregates of nucleolar subunits in which fibril-covered regions, the putative active cistrons for precursors of ribosomal RNA, alternate with fibril-free intercepts, the "spacers". The length distribution of the different intercepts of this DNA is given, and the pattern is compared with those shown in animal cell systems. The data are discussed in relation to problems of transcription and of amplification of ribosomal RNA genes.},
  language  = {en}
}