TY  - JOUR
A1  - Franke, Werner W.
A1  - Scheer, Ulrich
T1  - The ultrastructure of the nuclear envelope of amphibian oocytes: a reinvestigation. I. The mature oocyte
N2  - 1 n order to review the contradictory statements on the ultrast ructure of the nuclear envelope, a study was undertaken combining section and negat ive stai ning electron microscopy on manually isolated oocyte nuclei and nuclear envelopes from six amphibian species including Anura as well as Urodela. The a ppeara nce of the negatively stained iso lated nuclear envelopes is described in deta il and the dependence on the preparation co nditions used is emphas ized . Pore complex structures such as pore perimeter, central granule, an nul ar components, interna l fibrils, and annu lus-attached fibrils could be identified by both techniques, negat ive staining and sect ions. Comparative studies show that no marked diffe rences ex ist in the structural data of the nuclear envelope among the investigated amphibians and the significance of the structural components is discussed. A model of the nuclea r pore complex based on the findings of the present investigation is prese nted.
Y1  - 1970
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32098
ER  - 
TY  - THES
A1  - Schmit, Fabienne
T1  - LINC, a novel protein complex involved in the regulation of G2/M genes
T1  - LINC, ein neuer Proteinkomplex, der G2/M Gene reguliert
N2  - Regulated progression through the cell cycle is essential for ordered cell proliferation. One of the best characterized tumor suppressors is the retinoblastoma protein pRB, which together with the E2F transcription factors regulates cell cycle progression. In the model organisms Drosophila melanogaster and Caenorhabditis elegans, RB/E2F containing multiprotein complexes have been described as transcriptional regulators of gene expression. This work first describes a homologous complex in human cells named LINC (for LIN complex). It consists of a stable core complex containing LIN-9, LIN-37, LIN-52, LIN-54 and RbAp48. This core complex interacts cell cycle-dependently with different pocket proteins and transcription factors. In quiescent cells, LINC associates with p130 and E2F4. In S-phase cells these interactions are lost and LINC binds to B-MYB and p107. The transient knock-down of LIN-54 in primary fibroblasts, as the depletion of LIN-9, leads to cell cycle defects. The cells are delayed before the entry into mitosis. This effect is due to the fact that the knock-down of LINC components leads to the downregulation of cell cycle genes responsible for the entry into and exit from mitosis as well as for checkpoints during mitosis. These LINC target genes are known E2F G2/M target genes, which are expressed later than the classical G1/S E2F target genes. The transcriptional regulation by LINC is a direct effect as LINC binds to the promoters of its target genes throughout the cell cycle. LINC contains three DNA-binding proteins. E2F4 and B-MYB, which cell cycle-dependently bind to LINC, are known DNA-binding transcription factors. Additionally, it is show here that the LINC core complex member LIN-54 also directly binds to the promoter of a LINC target gene. Although the exact molecular mechanism of LINC function needs to be analyzed further, data in this work provide a model for the delayed activation of G2/M target genes. B-MYB, a G1/S E2F target gene, binds to LINC upon its expression in S-phase. Then only LINC is a transcriptional activator that induces the expression of the G2/M genes. This provides an explanation for the delayed expression of these E2F G2/M target genes.
N2  - Die Regulation des Zellzyklus ist unerlässlich für die fehlerfreie Zellteilung. Einer der am Besten charakterisierten Tumorsuppressoren ist das Retinoblastom-Protein pRB, welches zusammen mit den E2F Transkriptionsfaktoren den Zellzyklus reguliert. In den Modellorganismen Drosophila melanogaster und Caenorhabditis elegans wurden Multiproteinkomplexe beschrieben, die pRB und E2F Homologe enthalten und transkriptionell die Expression von Zielgenen regulieren. Diese Arbeit beschreibt erstmals LINC, einen homologen Komplex in humanen Zellen. Der LIN-Kernkomplex besteht aus LIN-9, LIN-37, LIN-52, LIN-54 and RbAp48 und assoziiert zellzyklus-abhängig mit Pocket Proteinen und Transkriptionsfaktoren. In ruhenden Zellen (G0) assoziiert LINC mit p130 und E2F4. In der S-Phase verlassen p130 und E2F4 den Komplex und B-MYB und p107 interagieren mit LINC. Die transiente Depletion von LIN-54, ebenso wie die Depletion von LIN-9, führt zu Defekten im Zellzyklus. Die „knock-down“-Zellen treten verzögert in die Mitose ein. Dies konnte darauf zurückgeführt werden, dass die Depletion von LINC Mitgliedern Gene herunterreguliert, die für den Eintritt in und den Austritt aus der Mitose, sowie für Regulationsprozesse während der Mitose verantwortlich sind. Diese LINC Zielgene wurden bisher als G2/M E2F Zielgene beschrieben, welche verglichen mit klassischen E2F Zielgenen verzögert exprimiert werden. Die transkriptionelle Regulation durch LINC ist ein direkter Effekt, da LINC in G0 und in der S-Phase an die Promotoren seiner Zielgene bindet. LINC enthält drei DNA-bindende Proteine. Die zellzyklus-abhängigen Komponenten von LINC E2F4 und BMYB sind bekannte DNA-bindende Transkriptionsfaktoren. Zusätzlich konnte in dieser Arbeit gezeigt werden, dass das LINC Kernprotein LIN-54 direkt an den Promoter eines LINC Zielgens, cdc2, bindet. Obwohl der genaue molekulare Mechanismus für die Funktion von LINC noch genauer untersucht werden muss, liefern Daten in dieser Arbeit ein Modell für die verzögerte Expression von G2/M Genen. B-MYB ist selbst ein E2F Zielgen und bindet an LINC sobald es exprimiert wird. Erst die Assoziation von B-MYB an LINC in der S-Phase macht LINC zu einem transkriptionellen Aktivator G2/M-spezifischer Gene. Dies erklärt die verzögerte Expression dieser E2F G2/M Zielgene.
KW  - Zellzyklus
KW  - Transkription
KW  - LINC
KW  - LIN-54
KW  - G2/M Übergang
KW  - LINC
KW  - LIN-54
KW  - cell cycle
KW  - G2/M transition
KW  - transcription
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-29336
ER  - 
TY  - THES
A1  - Bertolucci, Franco
T1  - Operant and classical learning in Drosophila melanogaster: the ignorant gene (ign)
T1  - Operantes und klassisches Lernen in Drosophila melanogaster: das ignorant Gen (ign)
N2  - One of the major challenges in neuroscience is to understand the neuronal processes that underlie learning and memory. For example, what biochemical pathways underlie the coincidence detection between stimuli during classical conditioning, or between an action and its consequences during operant conditioning? In which neural substructures is this information stored? How similar are the pathways mediating these two types of associative learning and at which level do they diverge? The fly Drosophila melanogaster is an appropriate model organism to address these questions due to the availability of suitable learning paradigms and neurogenetic tools. It permits an extensive study of the functional role of the gene S6KII which in Drosophila had been found to be differentially involved in classical and operant conditioning (Bertolucci, 2002; Putz et al., 2004). Genomic rescue experiments showed that olfactory conditioning in the Tully machine, a paradigm for Pavlovian olfactory conditioning, depends on the presence of an intact S6KII gene. This rescue was successfully performed on both the null mutant and a partial deletion, suggesting that the removal of the phosphorylating unit of the kinase was the main cause of the functional defect. The GAL4/UAS system was used to achieve temporal and spatial control of S6KII expression. It was shown that expression of the kinase during the adult stage was essential for the rescue. This finding ruled out a developmental origin of the mutant learning phenotype. Furthermore, targeted spatial rescue of S6KII revealed a requirement in the mushroom bodies and excluded other brain structures like the median bundle, the antennal lobes and the central complex. This pattern is very similar to the one previously identified with the rutabaga mutant (Zars et al., 2000). Experiments with the double mutant rut, ign58-1 suggest that both rutabaga and S6KII operate in the same signalling pathway. Previous studies had already shown that deviating results from operant and classical conditioning point to different roles for S6KII in the two types of learning (Bertolucci, 2002; Putz, 2002). This conclusion was further strengthened by the defective performance of the transgenic lines in place learning and their normal behavior in olfactory conditioning. A novel type of learning experiment, called “idle experiment”, was designed. It is based on the conditioning of the walking activity and represents a purely operant task, overcoming some of the limitations of the “standard” heat-box experiment, a place learning paradigm. The novel nature of the idle experiment allowed exploring “learned helplessness” in flies, unveiling astonishing similarities to more complex organisms such as rats, mice and humans. Learned helplessness in Drosophila is found only in females and is sensitive to antidepressants.
N2  - Eine der größten Herausforderungen in der Neurobiologie ist es, die neuronalen Prozesse zu verstehen, die Lernen und Gedächtnis zugrundeliegen. Welche biochemischen Pfade liegen z.B. der Koinzidenzdetektion von Reizen (klassische Konditionierung) oder einer Handlung und ihren Konsequenzen (operante Konditionierung) zugrunde? In welchen neuronalen Unterstrukturen werden diese Informationen gespeichert? Wie ähnlich sind die Stoffwechselwege, die diese beiden Arten des assoziativen Lernens vermitteln und auf welchem Niveau divergieren sie? Drosophila melanogaster ist wegen der Verfügbarkeit von Lern-Paradigmen und neurogenetischen Werkzeugen ein geeigneter Modell-Organismus, zum diese Fragen zu adressieren. Er ermöglicht eine umfangreiche Studie der Funktion des Gens S6KII, das in der Taufliege in klassischer und operanter Konditionierung unterschiedlich involviert ist (Bertolucci, 2002; Putz et al., 2004). Rettungsexperimenten zeigen, dass die olfaktorische Konditionierung in der Tully Maschine (ein klassisches, Pawlow’sches Konditionierungsparadigma) von dem Vorhandensein eines intakten S6KII Gens abhängt. Die Rettung war sowohl mit einer vollständigen, als auch einer partiellen Deletion erfolgreich und dies zeigt, dass der Verlust der phosphorylierenden Untereinheit der Kinase die Hauptursache des Funktionsdefektes war. Das GAL4/UAS System wurde benutzt, um die S6KII Expression zeitlich und räumlich zu steuern. Es wurde gezeigt, dass die Expression der Kinase während des adulten Stadiums für die Rettung hinreichend war. Dieser Befund schließt eine Entwicklungsstörung als Ursache für den mutanten Phänotyp aus. Außerdem zeigte die gezielte räumliche Rettung von S6KII die Notwendigkeit der Pilzkörper und schloss Strukturen wie das mediane Bündel, die Antennalloben und den Zentralkomplex aus. Dieses Muster ist dem vorher mit der rutabaga Mutation identifizierten sehr ähnlich (Zars et al., 2000). Experimente mit der Doppelmutante rut, ign58-1 deuten an, dass rutabaga und S6KII im gleichen Signalweg aktiv sind. Vorhergehende Studien hatten bereits gezeigt, dass die unterschiedlichen Ergebnisse bei operanter und klassischer Konditionierung auf verschiedenen Rollen für S6KII in den zwei Arten des Lernens hindeuten (Bertolucci, 2002; Putz, 2002). Diese Schlussfolgerung wurde durch den mutanten Phänotyp der transgenen Linien in der Positionskonditionierung und ihr wildtypisches Verhalten in der klassischen Konditionierung zusätzlich bekräftigt. Eine neue Art von Lern-Experiment, genannt „Idle Experiment“, wurde entworfen. Es basiert auf der Konditionierung der Laufaktivität, stellt eine operante Aufgabenstellung dar und überwindet einige der Limitationen des „Standard“ Heat-Box Experimentes. Die neue Art des Idle Experimentes erlaubt es, „gelernte Hilflosigkeit“ in Fliegen zu erforschen, dabei zeigte sich eine erstaunliche Ähnlichkeit zu den Vorgängen in komplizierteren Organismen wie Ratten, Mäusen oder Menschen. Gelernte Hilflosigkeit in der Taufliege wurde nur in den Weibchen beobachtet und wird von Antidepressiva beeinflusst.
KW  - Klassische Konditionierung
KW  - Instrumentelle Konditionierung
KW  - Konditionierung
KW  - Operante Konditionierung
KW  - Lernen
KW  - Räumliches Gedächtnis
KW  - Assoziatives Gedächtnis
KW  - Gedächtnis
KW  - MAP-Kinase
KW  - Drosophila
KW  - Taufliege
KW  - Gelernte Hilflosigkeit
KW  - CREB
KW  - S6KII
KW  - p90RSK
KW  - RSK
KW  - p90 ribosomal S6 kinase
KW  - ribosomal S6 kinase II
KW  - operant conditioning
KW  - classical conditioning
KW  - associative learning
KW  - learned helplessness
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33984
ER  - 
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  - Sommerville, John
A1  - Scheer, Ulrich
T1  - Transcription of complementary repeat sequences in amphibian oocytes
N2  - Repeat sequences are transcribed in the germinal vesicles of amphibian oocytes. In the hnRNA population both complements of the repeats are found and can be readily detected because they form intermolecular duplex structures. The structure and formation of duplex regions have been studied in the hnRNA of Xenopus laevis, Triturus cristatus, Amphiuma means and Necturus maculosus, a series of amphibians of increasing genome size (C-value). In T. cristatus, the duplex structures are mostly 600- 1200 bp in length, whereas in X. laevis they are shorter and in N. maculosus they tend to be longer. Although the proportion of RNA sequence capable of rapidly forming duplex structures is different in different organisms, this property bears no relationship to C-value. However the sequence complexity of complementary repeats, as estimated from the rate of duplex formation, does show an increasing trend with C-value. The complementary repeats found in oocyte hnRNA are transcribed from families of DNA sequence that are each represented in the genome by thousands of copies. The extent of cross-species hybridization is low, indicating that the repeat sequences transcribed in different amphibian genera are not the same. In situ hybridization experiments indicate that the repeat sequences are spread throughout the genome. The evolution and possible function of complementary repeats are considered.
Y1  - 1982
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33915
ER  - 
TY  - JOUR
A1  - Benavente, Ricardo
A1  - Rose, Kathleen M.
A1  - Reimer, Georg
A1  - Hügle-Dörr, Barbara
A1  - Scheer, Ulrich
T1  - Inhibition of nucleolar reformation after microinjection of antibodies to RNA polymerase I into mitotic cells
N2  - The formation of daughter nuclei and the reformation of nucleolar structures was studied after microinjection of antibodies to RNA polymerase I into dividing cultured cells (PtK2). The fate of several nucleolar proteins representing the three main structural subcomponents of the nucleolus was examined by immunofluorescence and electron microscopy. The results show that the RNA polymerase I antibodies do not interfere with normal mitotic progression or the early steps of nucleologenesis, i.e. , the aggregation of nucleolar material into prenucleolar bodies. However,they inhibit the telophasic coalescence of the prenucleolar bodies into the chromosomal nucleolar organizer regions, thus preventing the formation of new nucleoli. These prenucleolar bodies show a fibrillar organization that also compositionally resembles the dense fibrillar component of interphase nucleoli . We conclude that during normal nucleologenesis the dense fibrillar component forms from preformed entities around nucleolar organizer regions, and that this association seems to be dependent on the presence of an active form of RNA polymerase I.
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33247
ER  - 
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  - JOUR
A1  - Scheer, Ulrich
T1  - Nuclear pore flow rate of ribosomal RNA and chain growth rate of its precursor during oogenesis of Xenopus laevis
N2  - The number of ribosomal RNA molecules which are transferred through an average nuclear pore complex per minute into the cytoplasm (nuclear pore flow rate, NPFR) during oocyte growth of Xenopus laevis is estimated. The NPFR calculations are based on determinations of the increase of cytoplasmic rRNA content during defined time intervals and of the total number of pore complexes in the respective oogenesis stages. In the mid-la mpbrush stage (500:"700 I'm oocyte diameter) the NPFR is maximal with 2.62 rRNA molecules/ pore/ minute. Then it decreases to zero at the end of oogenesis. The nucleocytoplasmic RNA f10w rates determined are compared with corresponding values of other cell types. The molecular weight of the rRNA precursor transcribed in the extrachromosomal nucleoli of Xenopus lampbrush stage oocytes is determined by acrylamide gel electrophoresis to be 2.5 x 10· daltons. From the temporal increase of cytoplasmic rRNA (3.8 I'g per oocyte in 38 days) and the known number of simultaneously growing precursor molecules in the nucleus the chain growth rate of the 40 S precursor RNA is estimated to be 34 nucleotides per second.
Y1  - 1973
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32178
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
T1  - Negative staining and adenosine triphosphatase activity of annulate lamellae of newt oocytes
N2  - Semi -iso la ted annul a te lamellae were prepared from single newt oocy tes (Triturus alpestris) by a modified Call a n-T omlin technique. Such preparations were examined with the electron mi croscope, and the negative sta ining a ppearance of th e a nnulate lamellae is described . The annul a te lamellae can be de tected either adhering to the nuclear envelope or being detached from it. Sometimes they a re obse rved to be connected with slender tubular-like structures interpreted as pa rts of the endoplasmic reti culum. The results obta ined from negativ e sta ining a re combined with those from sections. Especially, the structural data on th e a nnula te lamellae and the nuclear envelope of the very same cell were compa red . Evidence is presented th a t in the oocytes studied the two kinds of porous cisternae, n amely a nnul a te lamellae and nuclear envelope, a re markedly distinguished in that the annul a te lamellae ex hibit a much higher pore frequency (generally about twice tha t found for the corresponding nuclear envelope) and have al so a rela tive pore area occupying as much as 32 % to 55 % of th e cistern al surface (compa red with 13 % to 22 % in the nuclear envelopes). T he pore di ame ter a nd all other ultras tructural details of the pore complexes, however, a re equi valent in both kinds of porous cisternae. Like the annuli of the nuclear pore complexes of various a nimal and pl ant cells, the a nnuli of the a nnula te lamellae pores reveal al so an eightfold symmetry of their subunits in negatively stained as well as in ectioned ma teria l. Furthermore, th e a nnul a te lamellae a re shown to be a site of activity of the Mg-Na-Kstimul a ted ATPase.
Y1  - 1969
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32087
ER  - 
TY  - JOUR
A1  - Rose, Kathleen M.
A1  - Szopa, Jan
A1  - Han, Fu-Sheng
A1  - Cheng, Yung-Chi
A1  - Richter, Arndt
A1  - Scheer, Ulrich
T1  - Association of DNA topoisomerase I and RNA polymerase I: A possible role for topoisomerase I in ribosomal gene transcription
N2  - RNA polymerase I preparations purified from a rat hepatoma contained DNA topoisomerase activity. The DNA topoisomerase associated with the polymerase had an Mr of 110000, required Mg2+ but not ATP, and was recognized by anti-topoisomerase I antibodies. When added to RNA polymerase I preparations containing topoisomerase activity, anti-topoisomerase I antibodies were able to inhibit the DNA relaxing activity of the preparation as well as RNA synthesis in vitro. RNA polymerase II prepared by analogous procedures did not contain topoisomerase activity and was not recognized by the antibodies. The topoisomerase I: polymerase I complex was reversibly dissociated by column chromatography on Sephacryl S200 in the presence of 0.25 M (NH4hS04. Topoisomerase I was immunolocalized in the transcriptionally active ribosomal gene complex containing RNA polymerase I in situ. These data indicate that topoisomerase I and RNA polymerase I are tightly complexed both in vivo and in vitro, and suggest a role for DNA topoisomerase I in the transcription of ribosomal genes.
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33901
ER  - 
TY  - JOUR
A1  - Röder, G.
A1  - Steinlein, C.
A1  - Schmid, M.
A1  - Linsenmair, Karl Eduard
T1  - Karyotype and chromosome banding in the Turkish desert woodlouse Desertellio elongatus (Crustacea, Isopoda, Oniscidea)
N2  - The karyotype of D. elongatus was investigated by means of C-banding, silver staining, and mithramycinand quinacrine fluorescent staining. The diploid chromosome number is 2n = 50. C-banding shows pericentromerically localized constitutive heterochromatin in every chromosome. Two of the chromosome pairs carry two telomeric nucleolus organizer regions each. No heteromorphic sex chromosomes were found.
KW  - Karyotype; chromosome banding; Desertellio elongatus; Crustacea; Isopoda; Oniscidea
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30989
ER  - 
TY  - JOUR
A1  - Linsenmair, Karl Eduard
T1  - Comparative studies on the social behaviour of the desert isopod Hemilepistus reaumuri and of a Porcellio species
N2  - Behavioural adaptations have made the desert isopod Hemilepistus reaumuri the most successful herbivore and detritivore of the macrofauna of many arid areas in North Africa and Asia Minor. For survival and reproduction Hemilepistus is dependent on burrows. New burrows can only be dug during spring. With the time-consuming digging of a burrow, Hemilepistus has only made the first step towards solving its ecological problems. The burrows are vital and have to be continuously defended against competitors. This requirement is met by co-operation of individuals within the framework of a highly developed social behaviour. In spring adults form monogamous pairs in which partners recognize each other individually and later form, with their progeny, strictly closed family communities. Hemilepistus is compared with a Porcellio' sp. which has developed, convergently, a social behaviour which resembles that of Hemilepistus in many respects, but differs essentially in some aspects, partly reflecting differences in ecological requirements. This and a few other Porcellio species demonstrate some possible steps in the evolution of the social behaviour of Hemilepistus. The female Hemilepistus is-in contrast to Porcellio sp. - semelparous and the selective advantages of monogamy in its environment are not difficult to recognize. This chapter discusses how this mating system could have evolved and especially why monogamous behaviour is also the best method for the Hemilepistus male to maximize its reproductive success. The cohesion of pairs and of family communities in Hemilepistus is based on a highly developed chemical communication system. Individual- and family-specific badges owe their specificity to genetically determined discriminating substances. The nature of the badges raises a series of questions: e.g. since alien badges release aggression, how do parents avoid cannibalizing their young? Similar problems arise from the fact that family badges are mixtures of chemical compounds of very low volatility with the consequence that they can only be transferred by direct contact and that during moulting all substances are lost which an individual does not produce itself. It is shown that in solving these problems inhibiting properties (presumably substances) and learning play a dominant role.
Y1  - 1984
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30846
ER  - 
TY  - JOUR
A1  - Linsenmair, Karl Eduard
T1  - Individual and family recognition in subsocial arthropods, in particular in the desert isopod Hemilepistus reaumuri
N2  - Individual recogmtlon in the non-eusocial arthropods is, according to our present knowledge, predominantly found in the frame of permanent or temporary monogamy. In some cases, e. g. in stomatopods and possibly other marine crustaceans too, individual recognition may serve to allow identification of (i) individuals within dominance hierarchies or (ii) neighbours in territorial species thus helping to avoid the repetition of unnecessary and costly fights. Kin recognition is experimentally proven only in some isopod species (genera Hemilepistus and Porcel/io) and in the primitive cockroach (termite?) Cryptocercus. The «signatures» or «discriminators» used in the arthropods are chemical. It is assumed that the identifying substances are mainly genetically determined and in this paper I shall discuss possible evolutionary origins. The main part of this account is devoted to the presentation of some aspects of the highly developed individual and kin identification and recognition system in the desert isopod Hemilepistus reaumuri - a pure monogamous species in which pairs together with their progeny form strictly exclusive family units. Amongst other things problems of (i) mate choice, (ii) learning to recognize a partner, (iii) avoiding the un adaptive familiarization with aliens are treated. Monogamy under present conditions is for both sexes the only suitable way of maximizing reproductive success; an extremely strong selection pressure must act against every attempt to abandon monogamy under the given ecological conditions. The family «badges» which are certainly always blends of different discriminator substances are extremely variable. This variability is mainly due to genetical differences and is not environmentally caused. It is to be expected that intra-family variabiliry exists in respect of the production of discriminator substances. Since the common badge of a family is the result of exchanging and mixing individual substances, and since the chemical nature of these discriminators requires direct body contacts in order to acquire those substances which an individual does not produce itself, problems must arise with molting. These difficulties do indeed exist and they are aggravated by the fact that individuals may produce substances which do not show up in the common family badge. An efficient learning capability on the one hand and the use of inhibiting properties of newly molted isopods help to solve these problems. In the final discussion three questions are posed and - partly at least - answered; (i) why are families so strictly exclusive, (ii) how many discriminator substances have to be produced to provide a variability allowing families to remain exclusive under extreme conditions of very high population densities, (iii) what is the structure of the family badge and what does an individual have to learn apart from the badge in order not to mistake a family member for an alien or vice versa.
Y1  - 1985
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33957
ER  - 
TY  - JOUR
A1  - Linsenmair, Karl Eduard
A1  - Linsenmair, Christa
T1  - Paarbildung und Paarzusammenhalt bei der monogamen Wüstenassel Hemilepistus reaumuri (Crustacea, Isopoda, Oniscoidea)
N2  - No abstract available
Y1  - 1971
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33937
ER  - 
TY  - JOUR
A1  - Grafe, U.
A1  - Linsenmair, Karl Eduard
T1  - Protogynous sex change in the Reed Frog: Hyperolius viridiflavus
N2  - Observations on captive reed frogs Hyperolius viridijlavus ommatostictus showed that seven out of 24 females changed into males. Sex change occurred without any hormone treatment and resulted in completely functional males. The adaptive value is discussed in terms of maximizing life-time reproductive success. Hyperolius r. ommatostictus is the first amphibian known to show functional sex reversal.
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30990
ER  - 
TY  - JOUR
A1  - Schmuck, R.
A1  - Geise, W.
A1  - Linsenmair, Karl Eduard
T1  - Life cycle strategies and physiological adjustments of Reedfrog Tadpoles (Amphibia, Anura, Hyperoliidae) in relation to environmental conditions.
N2  - The relationship between different degrees of intraspecific crowding of reedfrog tadpoles and their physiological responses to a deterioration of the natal pond water quality was examined under laboratory conditions. Tadpoles that were reared at a lower density metamorphosed significantly earlier than those raised at a higher density. As density increases, the average body length at metamorphosis decreases. However, at low tadpole density, a significantly higher diversity of body size classes among freshly metamorphosed froglets was observed than under more crowded conditions. Mortality increased during metamorphic climax and was inversely correlated with the tadpole density. In ephemeral ponds, an accumulation of nitrogenous wastes from metabolic processes and/or a concentration by evaporation in prolonged rainless periods can pose a considerable chemical stress to reedfrog tadpoles. Hyperolius viridiflavus ommatostictus responded to an increasing ammonia concentration with an activity increase of the ornithine cycle (intensified urea synthesis). hi contrast, Hyperolius marmoratus taeniatus exhibited a strong tolerance against high ammonia levels. A deterioration of the natal pond water quality caused H. v. ommatostictus and H. v. nitidulus tadpoles to adjust to harsher climatic conditions at the time of metamorphosis. This physiological preadjustment enabled the froglets to start feeding and growing immediately after metamorphosis even at low air humidity and rare precipitation events. In contrast, froglets that were raised in daily refreshed water exhibited high mortality rates if subjected to identical conditions. As one possible indicator of the actual climatic conditions prevailing in the surrounding terrestrial habitat, fluctuations in the water ammonia level are discussed.
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31009
ER  - 
TY  - JOUR
A1  - Reimer, Georg
A1  - Scheer, Ulrich
A1  - Peters, Jan-Michael
A1  - Tan, Eng M.
T1  - Immunolocalization and partial characterization of a nucleolar autoantigen (PM-Scl) associated with polymyositis / scleroderma overlap syndromes.
N2  - Precipitating anti-PM-Sel antibodies are present in sera from patients with polymyositis. scleroderma. and polymyositis/scleroderma overlap syndromes. By indirect immunofluorescence microscopy. anti-PM-Scl antibodies stained the nucleolus in cells of different tissues and species. suggesting that the antigen is highly conserved. By electron microscopy, anti-PM-Scl antibodies reacted primarily with the granular component of the nuc1eolus. Drugs that inhibit rRNA synthesis had a marked effect on the expression of PM-Scl antigen. In actinomycin D-treated cells, immunofluorescence staining by anti-PM-Scl was signüicantly reduced with residual staining restricted to the granular regions of nuc1eoli. Treatment with 5,6-dichloro-beta-D- ribofuranosylbenzimidazole (DRB) also selectively reduced nuc1eolar staining. On a molecular level, anti-PM-Sel antibodies precipitated 11 polypeptides with molecular weights (Mr) ranging from 110,000 to 20,000. The Mr 80,000 and 20.000 polypeptides were phosphorylated. Evidence suggests that the PM-Scl antigen complex may be related to a prerlbosomal particle.
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33191
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Sommerville, John
A1  - Bustin, M.
T1  - Injected histone antibodies interfere with transcription of lampbrush chromosome loops in oocytes of Pleurodeles
N2  - Antibodies to calf thymus histone H2B were purified by chromatography on DEAE-cellulose and injected into oocyte nuclei of Pleurodeles waltlii. As shown by indirect immunofluorescence these antibodies cross-reacted strongly with corresponding histones associated with lampbrush chromosomes. Shortly after injection the lateral loops of the chromosomes retracted into the chromomeres and by 3 h postinjection the 'lampbrush' appearance was completely lost and the chromosomes appeared in light-microscopic preparations as rod-like structures consisting of 10ngitudina11y coalesced chromomeres. In control oocytes injected with non-immune immunoglobulins or antibodies against a ubiquitous transcript-associated protein no morphological alterations of the lampbrush chromosomes could be observed. Electron microscopic spreads of chromosomes prepared at various times after injection of anti-H2B revealed a progressive loss of transcriptional complexes from the loop axes. Finally, higher-order chromatin configurations, like supranuc1eosomal globules (' superbeads ') or cable-like chromatin strands 50- 60 nm thick predominated, indicating complete transcriptional inactivation of a11 chromosomal regions. The results indicate that H2B antibodies react specifically with his tones associated with the transcribed DNA of lateral loops in their native state. The resulting antigenantibody complexes seem to inhibit progression of the R A polymerases along the template, thus causing the premature release of transcripts, a process analogous to the stripping effect of actinomycin D. The demonstration of histones associated with heavily transcribed regions, which are not compacted into nucleosomes but largely extended, supports the current concept that unfolding of nucleosomes to a110w transcription of the DNA does not involve dissociation of histones. In contrast, amplified ribosomal RNA genes are unaffected by injected HzB antibodies. This does not necessarily indicate absence of his tones from nucleolar chromatin, since we do not know whether it is accessible in vivo to antibodies or whether the histone antigenie determinants are masked by the presence of other proteins. The technique of injecting specific antibodies should be widely applicable when analysing the in vivo distribution of chromosomal components at the electron-microscopic level and when studying complex metabolie processes, like the cleavage and modification of RNA, by selective inhibition of defined enzymic steps.
Y1  - 1979
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33166
ER  - 
TY  - JOUR
A1  - Reimer, Georg
A1  - Rose, Kathleen M.
A1  - Scheer, Ulrich
A1  - Tan, Eng M.
T1  - Autoantibody to RNA polymerase I in scleroderma sera
N2  - Autoantibodies to components of the nucleolus are a unique serological feature of patients with scleroderma. There are autoantibodies of several specificities; one type produces a speckled pattern of nucleolar staining in immunofluorescence. In actinomycin D and 5,6-dichloro-{j-D-ribofuranosylbenzimidazoletreated Vero cells, staining was restricted to the fibrillar and not the granular regions. By double immunofluorescence, specific rabbit anti-RNA polymerase I antibodies stained the same fibrillar structures in drug-segregated nucleoli as scleroderma sera. Scleroderma sera immunoprecipitated 13 polypeptides from (35S)methionine-labeled HeLa cell extract with molecular weights ranging from 210,000 to 14,000. Similar polypeptides were precipitated by rabbit anti-RNA polymerase I antibodies, and their common identities were confirmed in immunoabsorption experiments. Microinjection of purified IgG from a patient with speckled nucleolar staining effectively inhibited ribosomal RNA transcription. Autoantibodies to RNA polymerase I were restricted to certain patients with scleroderma and were not found in other autoimmune diseases.
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34294
ER  - 
TY  - JOUR
A1  - Reinhard, Matthias
A1  - Halbrügge, Maria
A1  - Scheer, Ulrich
A1  - Wiegand, Christiane
A1  - Jockusch, Brigitte M.
A1  - Walter, Ulrich
T1  - The 46/50 kDa phosphoprotein VASP purified from human platelets is a novel protein associated with actin filaments and focal contacts
N2  - Vasoactive agents which elevate either cGMP or cAMP inhibit platelet activation by pathways sharing at least one component, the 46/50 kDa vasodilator-stimulated phosphoprotein (V ASP). V ASP is stoichiometrically phosphorylated by both cGMP-dependent and cAMPdependent protein kinases in intact human platelets, and its phosphorylation correlates very well with platelet inhibition caused by cGMP- and cAMP-elevating agents. Here we report that in human platelets spread on glass, V ASP is associated predominantly with the distal parts of radial micro filament bundles and with microfilaments outlining the periphery, whereas less V ASP is associated with a central microfilamentous ring. V ASP is also detectable in a variety of different cell types including fibroblasts and epithelial cells. In fibroblasts, V ASP is concentrated at focal contact areas, along microfilament bundles (stress fibres) in a punctate pattern, in the periphery of protruding lamellae, and is phosphorylated by cGMP- and cAMP-dependent protein kinases in response to appropriate stimuli. Evidence for the direct binding of V ASP to F -actin is also presented. The data demonstrate that V ASP is a novel phosphoprotein associated with actin filaments and focal contact areas, i.e. transmembrane junctions between microfilaments and the extracellular matrix.
KW  - cAMP / cGMP / cytoskeleton / phosphorylation / protein kinase
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34246
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Dabauvalle, Marie-Christine
A1  - Merkert, Hilde
A1  - Benavente, Ricardo
T1  - The nuclear envelope and the organization of the pore complexes
N2  - No abstract available
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34275
ER  - 
TY  - JOUR
A1  - Bell, Peter
A1  - Dabauvalle, Marie-Christine
A1  - Scheer, Ulrich
T1  - In vitro assembly of prenucleolar bodies in Xenopus egg extract
N2  - Nuclei assembled in Xenopus egg extract from purified DNA or chromatin resemble their natural counterparts in a number of structural and functional features. However, the most obvious structural element of normal interphase nuclei, the nucleolus, is absent from the in vitro reconstituted nuclei. By EM, cytological silver staining, and immunofluorescence microscopy employing antibodies directed against various nucleolar components we show that nuclei assembled in vitro contain numerous distinct aggregates that resemble prenucleolar bodies (PNBs) by several criteria. Formation of these PNB-like structures requires pore complex-mediated nuclear transport of proteins but is independent of the genetic content of the in vitro nuclei as well as transcriptional and translational events. Our data indicate that nuclei assembled in vitro are capable of initiating early steps of nucleologenesis but that the resulting PNBs are unable to fuse with each other, probably due to the absence of a functional nucleolus organizer. With appropriate modifications, this experimental system should be useful to define and analyze conditions promoting the site-specific assembly of PNBs into a coherent nucleolar body.
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34233
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
T1  - Identification of a novel class of tandemly repeated genes transcribed on lampbrush chromosomes of Pleurodeles waltlii
N2  - Electron microscope preparations of lampbrush chromosomes from oocytes of Pleurodeles waltl;; have revealed a new class of tandemly repeated genes. These genes are highly active, as judged by the close spacing of nascent transcripts. They occur in clusters of >100 copies and are transcribed in units containing roughly 940 base pairs of DNA that are separated by nontranscribed spacers of an estimated DNA content of 2,410 base pairs. The size and the pattern of arrangement of these transcription units can not be correlated with any of the repetitious genes so far described.
Y1  - 1981
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33153
ER  - 
TY  - JOUR
A1  - Franke, Werner W.
A1  - Kleinschmidt, Jürgen A.
A1  - Spring, Herbert
A1  - Krohne, Georg
A1  - Grund, Christine
A1  - Trendelenburg, Michael F.
A1  - Stöhr, Michael
A1  - Scheer, Ulrich
T1  - A nucleolar skeleton of protein filaments demonstrated in amplified nucleoli of Xenopus laevis
N2  - The amplified, extrachromosomal nucleoli of Xenopus oocytes contain a meshwork of -4-nm-thick filaments, which are densely coiled into higher-order fibrils of diameter 30-40 nm and are resistant to treatment with high- and low-salt concentrations, nucleases (DNase I, pancreatic RNase, micrococcal nuclease), sulfhydryl agents, and various nonionic detergents. This filamentous "skeleton" has been prepared from manually isolated nuclear contents and nucleoli as weil as from nucleoli isolated by fluorescence-activated particle sorting. The nucleolar skeletons are observed in light and electron microscopy and are characterized by ravels of filaments that are especially densely packed in the nucleolar cortex. DNA as weil as RNA are not constituents of this structure, and precursors to ribosomal RNAs are completely removed from the extraction-resistant filaments by treatment with high-salt buffer or RN ase. Fractions of isolated nucleolar skeletons show specific enrichment of an acidic major protein of 145,000 mol wt and an apparent pi value of -6.15, accompanied in some preparations by various amounts of minor proteins. The demonstration of this skeletal structure in "free" extrachromosomal nucleoli excludes the problem of contaminations by nonnucleolar material such as perinucleolar heterochromatin normally encountered in studies of nucleoli from somatic cells. It is suggested that this insoluble protein filament complex forms a skeleton specific to the nucleolus proper that is different from other extraction-resistant components of the nucleus such as matrix and lamina and is involved in the spatial organization of the nucleolar chromatin and its transcriptional products. In studies of the organization of the interphase nucleus, considerable progress has been made in the elucidation of the arrangement of chromatin components and transcriptional products. However, relatively little is known about the composition and function of another category of nuclear structures, the nonnucleoproteinaceous architectural components that are insoluble in solutions of low and high ionic strength, despite numerous studies dedicated to this problem. Such structures include (a) the nuclear envelope and its pore complexes (I, 15, 18, 23, 37, 41), (b) a peripheral layer of insoluble protein ("lamina"; I, 15, 22, 23, 59), (e) certain skeletal proteins related to the chromosome "scaffold" described by Laemmli and coworkers (see references 2 and 3), and (d) ill-defined tangles of fibrillar structures of the nuclear interior that are collectively described as residual "matrix" (6, 21 ; for reviews, see references THE JOURNAL OF CEll BrOlOGY . VOlUME 90 AUGUST 1981 289-299 © The RockefeIler University Press · 0021 -9525/ 81 / 08/ 0289/ 11 $1 .00 4 and 12). The latter, preparatively
Y1  - 1981
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33130
ER  - 
TY  - JOUR
A1  - Franke, Werner W.
A1  - Scheer, Ulrich
A1  - Krohne, Georg
A1  - Jarasch, Ernst-Dieter
T1  - The nuclear envelope and the architecture of the nuclear periphery
N2  - No abstract available
Y1  - 1981
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33108
ER  - 
TY  - JOUR
A1  - Bona, Marion
A1  - Scheer, Ulrich
A1  - Bautz, Ekkehard K. F.
T1  - Antibodies to RNA polymerase II (B) inhibit transcription in lampbrush chromosomes after microinjection into living amphibian oocytes
N2  - Antibodies directed against RNA polymerase II (B) from Drosophila melanogaster were obtained from rabbit sera and, as monoclonal immunoglobulins, from mouse hybridomas and shown to cross-react with the amphibian enzyme protein. Localization by indirect immunofluorescence microscopy revealed the association of this enzyme with chromatin of interphase nuclei of amphibian cells and its absence in nucleoli. Purified immunoglobulins were microinjected in to nuclei ofliving vitellogenic oocytes of Ple1lrodeles waltlii and X enopus laevis and their effects on transcriptional processes were monitored by biochemical and light and electron microscopic stud ies. RNA polymerase II antibodies from rabbit sera caused a rapid and almost complete release of nascent transcripts from the chromatin axis of the loops of lampbrush chromosomes, followed by collapse of the loops and their retraction on the main chromosome axis. Monoclonal murine antibodies to the Iarge RNA polymerase II subunits also inhibited transcription in chromosome Ioops but appeared to inhibit initiation rather than elongation events. Activities of class land III RNA polymerases were not significantly affected by injection of antibodies to polymerase II, indicating immunological differences between the three RNA polymerases. The potential value of the in vitro test system described , as a very sensitive assay for detecting proteins involved in transcription in living cells, is discussed. 1
Y1  - 1981
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33128
ER  - 
TY  - JOUR
A1  - Trendelenburg, Michael F.
A1  - Scheer, Ulrich
A1  - Zentgraf, Hanswalter
A1  - Franke, Werner W.
T1  - Heterogeneity of spacer lengths in circles of amplified ribosomal DNA of two insect species, Dytiscus marginalis and Acheta domesticus
N2  - No abstract available
Y1  - 1976
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33055
ER  - 
TY  - JOUR
A1  - Fiala, Brigitte
A1  - Grunsky, Harald
A1  - Maschwitz, Ulrich
A1  - Linsenmair, Karl Eduard
T1  - Diversity of ant-plant interactions: Protective efficacy in Macaranga species with different degrees of ant-association.
N2  - The pioneer tree Macaranga in SE Asia has developed manyfold associations with ants. The genus comprises all stages of interaction with ants, from facultative relationships to obligate myrmecophytes. Only myrmecophytic Macaranga offer nesting space for ants and are associated with a specific ant partner. The nonmyrmecophytic species are visited by a variety of different ant species which are attracted by extrafloral nectaries (EFN) and food bodies. Transitional Macaranga species like M. hosei are colonized later in their development due to their stem structure. Before the colonization by their specific Crematogaster partner the young plants are visited by different ant species attracted by EFN. These nectaries are reduced and food body production starts as soon as colonization becomes possible. We demonstrated earlier that obligate ant partners can protect their Macaranga plants against herbivore damage and vine cover. In this study we focused on nonspecific interactions and studied M. tanarius and M. hosei, representing a non-myrmecophyte and a transitional species respectively. In ant exclusion experiments both M. tanarius and M. hosei suffered significantly higher mean leaf damage than controls, 37% versus 6% in M. hosei, 16% versus 7% in M. tanarius. M. tanarius offers both EFN and food bodies so that tests for different effects of these two food rewards could be conducted. Plants with food bodies removed but with EFN remaining had the lowest mean increase of herbivore damage of all experimental groups. Main herbivores on M. hosei were mites and caterpillars. Many M. tanarius plants were infested by a shootborer. Both Macaranga species were visited by various ant species. Crematogaster spp. being the most abundant. We found no evidence for any specific relationships. The results of this study strongly support the hypothesis that non-specific, facultative associations with ants can be advantageous for Macaranga plants. Food bodies appear to have lower attractive value for opportunistic ants than EFN and may require a specific dietary adaptation. This is also indicated by the fact that food body production in the transitional M. hosei does not start before stem structure allows a colonization by the obligate Crematogaster species. M. hosei thus benefits from facultative association with a variety of ants until it produces its first domatia and can be colonized by its obligate mutualist.
KW  - Ant-plant interactions ; Herbivory Macaranga ; Mutualism ; Myrmecophytes
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32905
ER  - 
TY  - JOUR
A1  - Fiala, Brigitte
A1  - Maschwitz, Ulrich
T1  - Studies on the south east asian ant-plant association Crematogaster borneensis / Macaranga: adaptations of the ant partner.
N2  - C. borneensis (Myrmicinae) lives in dose association with several myrmecophytic species of the South East Asian pioneer tree genus Macaranga (Euphorbiaceae). The ants are adapted to the plants so dosely that they do not survive away from it. The only food they utilize is provided as food bodies by the plant and honeydew from specific scale insects kept inside the hollow internodes. The anatomy of the digestive tract is also adapted to life on the host plant: the crop is very sm all and can store only minute food quantities. C. borneensis exdusively colonizes certain Macaranga species. Queens as weIl as workers are able to recognize their host plant species, probably by chemical cues. Colony founding queens swarm throughout the year, mostly during darkness. There is strong competition among queens for host plants. Queens do not carry scale insects on their nuptial flight. Worker ants are active day and night. Most of them patrol and collect food bodies on the younger parts of the host plant. An important characteristic is their deaning behaviour, which results in removal of aIl foreign objects. Even though they are rather smalI, workers respond very aggressively to certain kinds of disturbance of the host plant. The ants attack most phytophagous insects and are especially effective in killing and removing smalI, softbodied herbivores (e.g. caterpillars). They do not possess a functional sting, but apply defensive secretion and-once biting an intruder-will not let go. Their effective alarm system results in a mass attack, which provides adequate defence for the colony and the host plant. A comparison with another Crematogaster species further illustrated the special adaptations of C. borneensis to its host plant.
N2  - Untersuchungen über die südostasiatische Ameisen·Pflanzen-Vergesellschaftung Cremattogaster borneensis Maoaranga : Anpassungen des Ameisenpartners 213 C. borneensis (Myrmicinae) lebt in enger Gemeinschaft mit myrmekophytischen Arten der südostasiatischen Pionierbaumgattung Macaranga (Euphorbiaceae) . Die Ameise ist so eng an die Pflanze adaptiert, daß sie getrennt von ihr nicht lebensfähig ist. Die Nahrung bezieht C. borneensis in Form von Nährkörperchen ausschließlich von der Pflanze. Im Sproßachseninnern gehaltene spezifische Schildläuse bieten eine weitere Nahrungsquelle. Die Adaptationen erstrecken sich bis auf die Anatomie des Verdauungstraktes : Der Kropf ist sehr klein und kann nur geringe Nahrungsmengen speichern. C. borneensis besiedelt spezifisch nur Macaranga-Pflanzen. Sowohl Königinnen als auch Arbeiterinnen sind in der Lage, die Wirtspflanze zu erkennen, wobei offenbar chemische Reize eine Rolle spielen. Die koloniegründenden Königinnen schwärmen das gesamte Jahr über, das Schwärmen erfolgt überwiegend während der Dunkelheit. Um die besiedlungsfähigen Macaranga-Pflanzen herrscht ein starker Konkurrenzdruck. Die beteiligten Schildlausarten sind spezifisch für die Assoziation. Sie werden nicht von der Königin beim Hochzeitsflug mitgenommen. Die Arbeiterinnen sind tag- und nachtaktiv. Die meisten Tiere halten sich im jüngsten Drittel der Pflanze auf, wo sie patrouillieren und Nährkörperchen sammeln. Mittels eines spezifischen Säuberungsverhaltens entfernen die Arbeiterinnen alle Fremdobjekte von der Pflanze. Trotz ihrer geringen Größe attackieren die Ameisen eine Vielzahl phytophager Insekten und sind dabei besonders effektiv in der Abwehr kleiner, wenig sklerotisierter Tiere wie z.B. Raupen. Sie verfügen zwar nicht ' über einen funktionsfähigen Stachel, setzen aber Wehrsekrete ein und beißen sich hartnäckig fest . Mit Hilfe eines effektiven Alarmierungssystems, das einen Massenangriff ermöglicht, gewährleisten sie eine Verteidigung ihrer Kolonien und damit gleichzeitig ihrer Wirtspflanze. Eine Vergleich mit einer anderen Crematogaster-Art demonstriert die besonderen Adaptationen von C. borneensis an ihre Wirtspflanze.
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32689
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Zentgraf, Hanswalter
A1  - Sauer, Helmut W.
T1  - Different chromatin structures in Physarum polycephalum: a special form of transcriptionally active chromatin devoid of nucleosomal particles
N2  - Nonnucleolar chromatin from interphase nuclei of Physarum polycephalum plasmodia occurs in two different structural configurations as seen in electron microscopic spread preparations. While the majority of the chromatin is devoid of nascent ribonucleoprotein (RNP) fibrils and compacted into nucleosomal particles, a minor proportion (10- 20%) is organized differently and reveals a smooth contour. It is this form of smooth chromatin which is rich in transcription units (mean length: 1.36±0.21 11m). Only occasionally are solitary nascent RNP fibrils observed which are associated with beaded strands of chromatin. In transcribed smooth chromatin nucleosomal particles are not only absent from the transcription units but also from their nontranscribed flan king regions, indicating that this special structural aspect is not merely a direct consequence of the transcriptional process. The existence of ca. 10- 20% of Physarum chromatin in the smoothly contoured form is discussed in relation to reports of a preferential digestibility of a similar proportion of Physarum chromatin by DNAse I (Jalouzot et al. , 1980) and to the altered configuration of "peak A" chromatin subunits after micrococcal nuclease digestion (Johnson et al., 1978a, b).
Y1  - 1981
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33148
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Zentgraf, Hanswalter
T1  - Nucleosomal and supranucleosomal organization of transcriptionally inactive rDNA circles in Dytiscus oocytes
N2  - Oocytes of the water beetle, Dytiscus marginalis, contain large amounts of rDNA most of which is present in the form of rings containing one or several pre-rRNA genes. Electron microscopy of spread preparations of vitellogenic oocytes has shown that the rDNA is extended in chromatin rings with transcribed pre- rRNA genes and is not packed into nucleosomes (Trendelenburg eta!. , 1976). When similar preparations are made from previtellogenic ooytes in which a large proportion of the nuc1eolar chromatin is transcriptionally inactive, a different morphological form of this chromatin is recognized. In contrast to the transcribed chromatin rings the inactive nucleolar chromatin circles show the characteristic beaded configuration, indicative of nucleosomal packing. Nuc1eosomal packing is also indicated by the comparison of the lengths of these chromatin rings with both iso lated rDNA circ1es and transcribed chromatin rings. In addition, these inactive nuc1eofilaments often appear to be compacted into globular higher order structures of diameters from 21 to 34nm, each composed of an aggregate of 6-9 nuc1eosomes. While the estimated reduction of the overall length of rDNA, as seen in our preparations, is, on the average, only 2.2 - 2.4 fold in the nuc1eosomal state it is 10- 13 fold when supranuc1eosomal globules are present. These data show that the extrachromosomal rDNA of these oocytes goes through a cycle of condensation and extensio n, as a function of the specific transcriptional activity, and that the beaded state described here is exc1usively found in the non-transcribed state.
Y1  - 1978
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33188
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Trendelenburg, Michael F.
A1  - Krohne, Georg
A1  - Franke, Werner W.
T1  - Lengths and patterns of transcriptional units in the amplified nucleoli of oocytes of Xenopus laevis
N2  - Transcriptionally active chromatin from peripheral amplified nuc1eoli of lampbrush-chromosome stage oocytes of Xenopus laevis was dispersed and spread in various solutions of low salt concentrations (incIuding some with additions of detergents) and examined by electron microscopy. Nucleolar material from oocytes of animals with normal (2-nu) and mutant (I-nu) genetical constitution of nucleolus organizers was compared. Histograms showing the distributions of the lengths of matrix units, apparent spacer intercepts, and the total repeating units of the rDNA containing chromatin axes revealed a significant degree of heterogeneity, with indications of subclasses and predominant repeat unit size c1asses of 3.3 and 3.8 11m length. The correspondence of matrix unit length to the molecular weight of the first stable product of rDNA transcription was studied using gel electrophoresis of labelIed pre-rRNA under non-denaturing and denaturing conditions. Evaluations of individual strands of nucleolar chromatin furt her demonstrated the existence of both (i) strands with obviously homogeneous repeating units and (ii) strands with intra-axial heterogeneity of rDNA subunits. " Preludecomplexes ", i.e. groups of transcriptional complexes in apparent spacer intercepts, were not infrequently noted. The data are compared with the measurements of lengths of repeating units in fragments of rDNA obtained by digestion with EcoRI endonuclease as described by Morrow et al. (1974) and Wellauer et al. (1974, 1976a, b). The results are discussed in relation to problems of variations in the modes of arrangement of the pre-rRNA genes, the state of packing of rDNA during transcription, and possible mechanisms of the amplification process.
Y1  - 1977
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33069
ER  - 
TY  - JOUR
A1  - Zentgraf, H.
A1  - Müller, U.
A1  - Scheer, Ulrich
A1  - Franke, W. W.
T1  - Evidence for the existence of globular units in the supranucleosomal organization of chromatin
N2  - No abstract available
Y1  - 1981
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34123
ER  - 
TY  - JOUR
A1  - Fiala, Brigitte
A1  - Maschwitz, Ulrich
T1  - Domatia as most important adaptations in the evolution of myrmecophytes in the paleotropical tree genus Macaranga (Euphorbiacae)
N2  - The paleotropical tree genus Macaranga (Euphorbiaceae) comprises all stages of interaction with ants, from facultative associations to obligate myrmecophytes. In SE.-Asia food availability does not seem to be the limiting factor for the development of a close relationship since all species provide food for ants in form of extrafloral nectar and/or food bodies. Only myrmecophytic Macaranga species offer nesting space for ants (domatia) inside intern odes which become hollow due to degeneration of the pith. Non-myrmecophytic species have a solid stem with a compact and wet pith and many resin ducts. The stem interior of some transitional species remains solid, but the soft pith can be excavated. The role of different ant-attracting attributes for the development of obligate ant-plant interactions is discussed. In the genus Macaranga, the provision of nesting space seems to be the most important factor for the evolution of obligate myrmecophytism.
KW  - Angiosperms ; Ant-plant interactions ; domatia ; Flora of Malaysia
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32935
ER  - 
TY  - JOUR
A1  - Krohne, Georg
A1  - Franke, Werner W.
A1  - Scheer, Ulrich
T1  - The major polypeptides of the nuclear pore complex
N2  - Nuclear envelopes of maturing oocytes of various amphibia contain an unusually high number of pore complexes in very close packing. Consequently, nuclear envelopes , which can be manually isolated in great purity, provide a remarkable enrichment of nuclear pore complex material, relative to membranous and other interporous structures. When the polypeptides of nuclear envelopes isolated from oocytes of Xenopl/s la evis and Triturus alpestris are examined by gel electrophoresis, visualized either by staining with Coomassie blue or by radiotluorography after in vitro reaction with [3H]dansyl chloride , a characteristic pattern is obtained (10 major and 15 minor bands). This polypeptide pattern is radically different from that of the nuclear contents isolated from the same cell. Extraction of the nuclear envelope with high salt concentrations and moderateIy ac tive detergents such as Triton X- 100 results in the removal of membrane material but leaves most of the non-membranous structure of the pore complexes. The dry weight of the pore complex (about 0.2 femtograms) remains essentially unchanged during such extractions as measured by quantitative electron microscopy . The extracted preparations which are highly enriched in nuclear pore complex material contain only two major polypeptide components with apparent molecular weights of 150000 and 73000. Components of such an electrophoretic mobility are not present as major bands , if at all , in nuclear contents extracted in the same way. lt is concluded that these two polypeptides are the major constituent protein(s) of the oocyte nuclear pore complex and are specific for this structure. When nuclear envelopes are isolated from rat liver and extracted with high salt buffers and Triton X- 100 similar bands are predominant, but two additional major components of molecular weights of 78000 and 66000 are also recognized. When the rat liver nuclear membranes are further subfractionated material enriched in the 66000 molecular weight component can be separated from the membrane material, indicating that this is relatively loosely associated material , probably a part of the nuclear matrix . The results suggest that the nuclear pore complex is not only a characteristic ubiquitous structure but also contains similar, if not identical , skeletal proteins that are remarkably re sistant to drastic changes of ionic strength as weil as to treatments with detergents and thiol reagents.
Y1  - 1978
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33078
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Sommerville, John
T1  - Sizes of chromosome loops and hnRNA molecules in oocytes of amphibia of different genome sizes
N2  - The lengths of lampbrush chromosome loops and their tran scription units show a positive correlation with genome size in oocytes of amphibia with different C values. However, there is no such correlation with contour lengths of hnRNA molecu les isolated from these oocytes. These results indi cate th at more ON A sequences are transcribed in amphibia of higher C value , but that processing of RNA transc ripts occurs while they are still attached to the chromosomes as nascent ribonucleoprotein fibrils.
Y1  - 1982
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33094
ER  - 
TY  - JOUR
A1  - Rungger, M.
A1  - Crippa, M.
A1  - Trendelenburg, M. F.
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
T1  - Visualization of rDNA spacer transcription in Xenopus oocytes treated with fluorouridine
N2  - Under the intluence of 5-tluoro-uridine, the ultrastructure of the rDNA transcription units in Xenopus oocytes is altered. Whereas part of the matrix units maintains anormal aspect or shows various degrees of inhibition, in a strong proportion of the transcription units the alternating pattern of matrix units and fibril-free spacer regions is no longer recognized. Transcriptional complexes are found along the entire DNP axis, including the regions of the spacers. These observations support biochemical data on transcription in rDNA spacer region.
Y1  - 1978
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33082
ER  - 
TY  - JOUR
A1  - Dabauvalle, Marie-Christine
A1  - Schulz, Barbara
A1  - Scheer, Ulrich
A1  - Peters, Reiner
T1  - Inhibition of nuclear accumulation of karyophilic proteins in living cells by microinjection of the lectin wheat germ agglutinin
N2  - No abstract available
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34288
ER  - 
TY  - CHAP
A1  - Scheer, Ulrich
A1  - Trendelenburg, M. F.
A1  - Franke, Werner W.
T1  - Regulation of transcription of ribosomal RNA genes during amphibian oogenesis
N2  - No abstract available
Y1  - 1976
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33700
ER  - 
TY  - CHAP
A1  - Franke, Werner W.
A1  - Scheer, Ulrich
T1  - Biochemical and structural aspects of nucleocytoplasmic transfer of ribonucleoproteins at the nuclear envelope level: facts and theses
N2  - No abstract available
Y1  - 1975
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33766
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
T1  - Pathways of nucleocytoplasmic translocation of ribonucleoproteins
N2  - No abstract available
Y1  - 1974
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33832
ER  - 
TY  - CHAP
A1  - Zentgraf, Hanswalter
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
T1  - On the existence of arrested transcriptional machinery in late stages of avian erythropoiesis
N2  - No abstract available
Y1  - 1976
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33696
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Lanfranchi, Gerolamo
A1  - Rose, Kathleen M.
A1  - Franke, Werner W.
A1  - Ringertz, Nils R.
T1  - Migration of rat RNA polymerase I into chick erythrocyte nuclei undergoing reactivation in chick-rat heterokaryons
N2  - Transcriptionally inactive chick erythrocyte nudei were reactivated by Sendai virusinduced fusion of erythrocytes with rat L6j1 myoblasts. We used antibodies to trace the appearance of a specific protein engaged in transcription of a defined dass of genes, those coding for rRNA, during reactivation. Using immunofluorescence microscopy, we found increasing amounts of rat RNA polymerase I to appear, during a certain period of time after fusion, in the reforming nudeoli of the chick nudei. Amounts of rat RNA polymerase I sufficient to be detected by immunofluorescence microscopy had accumulated in the newly developed chick nudeoli 72- 190 h after fusion was initiated. This time interval coincides with the time when chick rRNA synthesis can first be detected. The results raise the possibility that during these stages of the reactivation process chick rRNA genes are transcribed by heterologous RNA polymerase I moleeules of rat origin.
Y1  - 1983
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33232
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Hügle, Barbara
A1  - Hazan, Rachel
A1  - Rose, Kathleen M.
T1  - Drug-induced dispersal of transcribed rRNA genes and transcriptional products: Immunolocalization and silver staining of different nucleolar components in rat cells treated with 5,6-dichloro-1-Beta-D-ribofuranosylbenzimidazole
N2  - Upon incubation of cultured rat cells with the adenosine analogue 5,6-dichloro-l-β- D-ribofuranosylbenzimidazole (DRB), nucleoli reversibly dissociate into their substructures, disperse throughout the nuclear interior, and form nucleolar "necklaces". We have used this experimental system, which does not inhibit transcription of the rRNA genes, to study by immunocytochemistry the distribution of active rRNA genes and their transcriptional products during nucleolar dispersal and recovery to normal morphology. Antibodies to RNA polymerase I allow detection of template-engaged polymerase, and monoclonal antibodies to a ribosomal protein (S 1) of the small ribosomal subunit permit localization of nucleolar preribosomal particles. The results show that, under the action of DRB transcribed rRNA, genes spread throughout the nucleoplasm and finally appear in the form of several rows, each containing several (up to 30) granules positive for RNA polymerase land argyrophilic proteins. Nucleolar material containing preribosomal particles also appears in granular structures spread over the nucleoplasm but its distribution is distinct from that of rRNA gene-containing granules. We conclude that, although transcriptional units and preribosomal particles are both redistributed in response to DRB, these entities retain their individuality as functionally defined subunits. We further propose that each RNA polymerase-positive granular unit represents a single transcription unit and that each continuous array of granules ("string of nucleolar beads") reflects the linear distribution of rRNA genes along a nucleolar organizer region. Based on the total number of polymerase I-positive granules we estimate that a minimum of 60 rRNA genes are active during interphase of DRB-treated rat cells.
Y1  - 1984
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33216
ER  - 
TY  - JOUR
A1  - Zentgraf, Hanswalter
A1  - Trendelenburg, Michael F.
A1  - Spring, Herbert
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
A1  - Müller, Ulrike
A1  - Drury, Kenneth C.
A1  - Rungger, Duri
T1  - Mitochondrial DNA arranged into chromatin-like structures after injection into amphibian oocyte nuclei
N2  - Purified mitochondrial DNA (mitDNA) from ovaries ofXenopus lae vis was injected into the nuclei (germinal vesicles) of large viteUogenic oocytes of the same organism and examined by electron microscopy ofthe spread nuclear contents. Normally located nuclei of untreated oocytes as weil as peripherally translocated nuclei of centrifuged oocytes were used. In addition, oocyte nuclei isolated and incubated under liquid paraffin oil were injected with DNA. The integrity oftranscriptional structures of endogenous chromosomal (Iampbrush chromosomes) and extrachromosomal (nucleoli) genes of the injected nuclei was demonstrated. Microinjected mitDN A was identified as circles of chromatin exhibiting polynucleosome-like organization and a me an contour length of 2.6 J.Lm, corresponding to a compaction ratio of the mitDN A of about 2 : I. This DNA packing ratio is similar to that observed after preparation of various kinds of native chromatin in low salt buffers. The chromatin circles formed from injected mitDNA only very rarely exhibited lateral fibrils suggestive of transcriptional activity. These results suggest that purified mitDNA can be transformed to normally structured chromatin when exposed to oocyte nuclear contents but is rarely , if at all , transcribed in this form and in this environment.
Y1  - 1979
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33174
ER  - 
TY  - CHAP
A1  - Scheer, Ulrich
A1  - Rose, Kathleen M.
T1  - Localization of RNA polymerase I in interphase cells and mitotic chromosomes by light and electron microscopic immunocytochemistry
N2  - Rabbit antibodies to RNA polymerase I from a rat hepatoma have been used to localize the enzyme in a variety of cells at the light and electron microscopic level. In interphase cells the immunofluorescence pattern indicated that polymerase I is contained exclusively within the nucleolus. That this fluorescence, which appeared punctated rather than uniform, represented transcriptional complexes of RNA polymerase I and rRNA genes was suggested by the observation that it was enhanced in regenerating liver and in a hepatoma and was markedly diminished in cells treated with actinomycin D. Electron microscopic immunolocalization using gold-coupled second antibodies showed that transcribed rRNA genes are located in, and probably confined to, the fibrillar centers of the nucleolus. In contrast, the surrounding dense fibrillar component, previously thought to be the site of nascent prerRNA, did not contain detectable amounts of polymerase I. During mitosis, polymerase I molecules were detected by immunofluorescence microscopy at the chromosomal nucleolus organizer region, indicating that a considerable quantity of the enzyme remains bound to the rRNA genes. From this we conclude that rRNA genes loaded with polymerase I molecules are transmitted from one cell generation to the next one and that factors other than the polymerase itself are involved in the modulation of transcription of DNA containing rRNA genes during the cell cycle.
KW  - nucleolus
KW  - nucleolus organizer
KW  - fibrillar centers
KW  - rRNA genes
KW  - anti-RNA polymerase I antibodies
Y1  - 1984
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-33223
ER  - 
TY  - THES
A1  - Höhn, Katharina
T1  - Genotyp-Phänotyp Korrelation bei Fanconi Anämie
T1  - Genotype-Phenotype Correlation of Fanconi Anemia
N2  - Die Fanconi Anämie (FA) stellt eine sowohl genetisch als auch phänotypisch äußerst heterogene, autosomal rezessiv und X-chromosomal vererbte Erkrankung dar. Sie ist gekennzeichnet durch chromosomale Instabilität, ein chronisch progredientes Knochenmarkversagen, multiple kongenitale Fehlbildungen und eine Prädisposition zu diversen Neoplasien. Auf zellulärer Ebene ist die FA durch eine erhöhte spontane Chromosomenbrüchigkeit sowie einer Hypersensitivität gegenüber DNA-schädigenden Agenzien charakterisiert. Bislang konnten 13 Komplementations-gruppen (FA-A bis FA-N) und ihre jeweiligen Gene identifiziert werden. Die FA-Proteine spielen eine wichtige Rolle bei der Reparatur von DNA-Doppelstrang-brüchen. Die breite genetische Heterogenität der Fanconi Anämie und die große Anzahl privater Mutationen, aufgrund derer kaum interindividuelle Vergleiche möglich sind, erschweren eine Genotyp-Phänotyp Korrelation ebenso wie der compound-heterozygote Mutationsstatus vieler FA-Patienten. Bisherige Untersuchungen weisen darauf hin, dass die Art der jeweiligen Mutation einen größeren Einfluß auf die phänotypische Ausprägung der Erkrankung hat als die Art des betroffenen Gens. Zusätzlich zeichnet die Fanconi Anämie eine große phänotypische Variabilität aus, die sich in höchst unterschiedlichen Krankheitsausprägungen und –verläufen äußert. Um aussagekräftige Genotyp-Phänotyp Korrelationen etablieren zu können, bedarf es einer ausreichenden Anzahl von FA-Patienten, bei denen sowohl die Komplementationsgruppe als auch die zugrunde liegende Mutation eindeutig definiert wurden. In der vorliegenden Arbeit wurden exemplarisch die Krankheitsverläufe einiger Patienten (4 x FA-A, 1 x FA-B, 3 x FA-C, 1 x FA-D2 und 2 x FA-G) analysiert und mit den jeweiligen molekulargenetischen Befunden korreliert. Im Anschluss daran wurden in der Literatur beschriebene Genotyp-Phänotyp Korrelationen erläutert, verschiedene Mechanismen der phänotypischen Variabilität dargestellt und abschließend prägnante Kasuistiken nochmals hervorgehoben.
N2  - Fanconi anemia (FA) is an autosomal recessive disorder that is defined by cellular hypersensitivity to DNA crosslinking agents, and is characterized by the variable presence of congenital malformations, progressive bone-marrow failure, and predisposition to leukemia and solid tumors. There are at least different 13 complementation groups. FA genes are thought to play an important role in the removal of DNA interstrand crosslinks. Genotype-phenotype correlations are further complicated by the obvious heterogeneity of the mutational spectrum within each FA gene, the private character of mutations and the high prevalence of compound heterozygosity. Studies so far indicate that the nature of the underlying mutation is more important than the underlying complementation group. Furthermore there is a wide variation of phenotypes. Clinical course and severity of FA vary strongly between and even within families. Any definite conclusion about genotype-phenotype correlation needs a sufficient number of FA patients whose underlying complementation group and mutation has been identified and whose clinical course has been analysed equally. The present dissertation represents a first step in this direction.
KW  - Fanconi-Anämie
KW  - Genetische Variabilität
KW  - Phänotypische Heterogenität
KW  - Genotyp-Phänotyp Korrelation
KW  - Fallbeispiele
KW  - Fanconi anemia
KW  - genetic heterogeneity
KW  - phenotypic heterogeneity
KW  - genotype-phenotype correlation
KW  - case reports
Y1  - 2009
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-37542
ER  - 
TY  - RPRT
A1  - Gessler, Manfred
A1  - Simola, Kalle O.
A1  - Bruns, Gail A. P.
T1  - Cloning of breakpoints of a chromosome translocation identifies the AN2 locus
N2  - Chromosome translocations involving llpl3 have been associated with familial aniridia in two kindreds highlighting the chromosomal localization of the AN2 locus. This locus is also part of the WAGR complex (Wilros tumor, aniridia, genitourinary abnormalities, and mental retardation). In one kindred, the translocation is associated with a deletion, and probes for this region were used to identify and clone the breakpoints of the translocation in the second kindred. Comparison of phage restriction maps exclude the presence of any sizable deletion in this case. Sequences at the chromosome 11 breakpoint are conserved in multiple species, suggesting that the translocation falls within the AN2 gene.
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30177
ER  - 
TY  - JOUR
A1  - Vortkamp, Andrea
A1  - Gessler, Manfred
A1  - Paslier, D. Le
A1  - Elaswarapu, R.
A1  - Smith, S.
A1  - Grzeschik, Karl-Heinz
T1  - Isolation of a yeast artificial chromosome contig spanning the Greig cephalopolysyndactyly syndrome (GCPS) gene region
N2  - Disruption of the zinc finger gene GLI3 has been shown to be the cause of Greig cephalopolysyndactyly syndrome (GCPS), at least in some GCPS translocation patients. To characterize this genomic region on human chromosome 7p13, we have isolated a VAC contig of more than 1000 kb including the GLI3 gene. In this contig the gene itself spans at least 200-250 kb. A CpG island is located in the vicinity of the 5' region of the known GLI3 cDNA, implying a potential promoter region.
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30182
ER  -