TY  - JOUR
A1  - Franke, Werner W.
A1  - Berger, S.
A1  - Falk, Heinz
A1  - Spring, H.
A1  - Scheer, Ulrich
A1  - Trendelenburg, Michael F.
A1  - Schweiger, H. G.
A1  - Herth, W.
T1  - Morphology of the nucleo-cytoplasmic interactions during the development of Acetabularia cells. I. The vegetative phase
N2  - The ultrastructure of th e growin g and ma turing primary nucleus of Acetabularia medite rranea and Acetabularia major has been studied with the use of various fi xation procedures. Particular interest has been focused on the deta ils of the nuclear periphery and the perinuclear region. It is demonstrated that early in nuclear grow th a characteristic perinucl ear structura l complex is formed which is, among the eukaryotic cells, unique to Acetabularia and re lated genera. This perinuclear system consists essentially of a) the nuclear envelope with a very hi gh pore frequency and various pore complex assoc iat ion s w ith granular and/or threadlike structures some of which are continuous with the nucleolus; b) an approx imate ly 100 nm thick intermediate zone densely filled with a filam entOus material and occasional sma ll membraneous structures from which the typical cytOplasmic and nuclear organe lles and particles are excl ud ed ; c) an adjacent Iacunar labyrinthum which is interrupted by many plasmatic junction channels between the intermed iate zone and the free cytOplasm; d) numerous dense perinuclear bodies in the juxtanuclear cytOplasm which a re especia lly frequent at the junction channels and reveal a composition of aggregated fibrillar and granul ar structures; e) very dense exclusively fibrill ar agg regates which occur either in assoc iation with t he perinuclear region of the lacunar labyrinthum or, somewhat further out, in the cytOplasmic strands between the bra nches of the lacun ar labyrinthum in the form of slender, characteristic rods or "sausages".
Y1  - 1974
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32363
ER  - 
TY  - CHAP
A1  - Trendelenburg, M. F.
A1  - Franke, Werner W.
A1  - Spring, H.
A1  - Scheer, Ulrich
T1  - Ultrastructure of transcription in the nucleoli of the green algae Acetabularia major and A. mediterranea
N2  - No abstract available
Y1  - 1975
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33779
ER  - 
TY  - CHAP
A1  - Franke, Werner W.
A1  - Scheer, Ulrich
A1  - Zentgraf, Hanswalter
A1  - Trendelenburg, Michael F.
A1  - Müller, U.
A1  - Krohne, G.
A1  - Spring, H.
T1  - Organization of transcribed and nontranscribed chromatin
N2  - No abstract available
KW  - Tumor / Zellteilung
Y1  - 1980
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-40656
ER  - 
TY  - CHAP
A1  - Franke, Werner W.
A1  - Scheer, Ulrich
A1  - Trendelenburg, Michael F.
A1  - Zentgraf, H.
A1  - Spring, H.
T1  - Morphology of transcriptionally active chromatin
N2  - Some decades ago it was noted by cytologists that within the interphase nucleus large portions of the transcriptionally ("genetically," in their terms) inactive chromosomal material are contained in aggregates of condensed chromatin, the "chromocenters," whereas transcriptionally active regions of chromosomes appear in a more dispersed form and are less intensely stained with DNA-directed staining procedures (Heitz 1929, 1932, 1956; Bauer 1933). The hypothesis that condensed chromatin is usually characterized by very low or no transcriptional activity, and that transcription occurs in loosely packed forms of chromatin (including, in most cells, the nucleolar chromatin) has received support from studies of ultrathin sections in the electron microscope and from the numerous attempts to separate transcriptionally active from inactive chromatin biochemically (for references, see Anderson et al. 1975; Berkowitz and Doty 1975; Krieg and Wells 1976; Rickwood and Birnie 1976; Gottesfeld 1977). Electron microscopic autoradiography has revealed that sites of RNA synthesis are enriched in dispersed chromatin regions located at the margins of condensed chromatin (Fakan and Bernhard 1971, 1973; Bouteille et al. 1974; Bachellerie et al. 1975) and are characterized by the occurrence of distinct granular and fibrillar ribonucleoprotein (RNP) structures, such as perichromatin granules and fibrils. The discovery that, in most eukaryotic nuclei, major parts of the chromatin are organized in the form of nucleosomes (Olins and Olins 1974; Kornberg 1974; Baldwin et al. 1975) has raised the question whether the same nucleosomal packing of DNA is also present in transcriptionally active chromatin strands. Recent detailed examination of the morphology of active and inactive chromatin involving a diversity of electron microscopic methods, particularly the spreading technique by Miller and coworkers (Miller and Beatty 1969; Miller and Bakken 1972), has indicated that the DNA of some actively transcribed regions is not packed into nucleosomal particles but is present in a rather extended form within a relatively thin (4-7 nm) chromatin fiber.
Y1  - 1978
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-41097
ER  -