Untersuchungen zur Bestimmung des Geschlechts

Ohne Zusammenfassung     

Untersuchungen zur Bestimmung des Geschlechts

Ohne ZusammenfassungDie experimentellen Untersuchungen zu dieser Arbeit wurden an den zoologischen Stationen in Neapel und Rovigno mit pekuniärer Unterstützung der Kaiser Wilhelm-Gesellschaft zur Förderung der Wissenschaften ausgeführt. Dieser wie den Leitern der beiden Institute ProfessorReinhard Dohrn in Neapel und ProfessorSteuer undSella in Rovigno sowie ihren Mitarbeitern, ProfessorRanzi und Dr.Kramer in ersterem und Dr.Roch in letzterem Orte, sei mein herzlichster Dank abgestattet.     

Untersuchungen zur Bestimmung des Geschlechts

Ohne Zusammenfassung     

Untersuchungen zur Bestimmung des Geschlechts

Ohne Zusammenfassung     

Untersuchungen zur Bestimmung des Geschlechts

Ohne Zusammenfassung Jakob Baron v.Üxküll zu seinem 70. Geburtstag gewidmet.     

Untersuchungen zur Bestimmung des Geschlechts.

Ohne ZusammenfassungDer Kaiser Wilhelm-Gesellschaft zur Förderung der Wissenschaften sei für die mir gewährte Unterstützung mein ergebenster Dank abgestattet.     

Untersuchungen zur Entwicklung des PhycomycetenAllomyces arbuscula

InAllomyces arbuscula formation of gametes occurs within 80 min in isolated gametangia. Gametogenesis shows to be sensitive to cycloheximide at 50 and 100 g/ml, while actinomycin D at 25 and 50 g/ml fails to inhibit gametogenesis. Synthesis ofrRNA can be profoundly inhibited by 3×10^-3 M 5-fluorouracil prior to gametogenesis, without any effect on differentiation of gametes. It is shown by polyacrylamide-gel electrophoresis that during gametogenesis radioactive phosphate is incorporated intotRNA, but not intorRNA. The results indicate that formation of gametes is dependent uponmRNA already present in the gametangia before induction of gametogenesis. It is concluded further that protein synthesis on cytoplasmic ribosomes is finished 20–30 min after induction and thatrRNA synthesis seems not to be a prerequisite for the differentiation of gametes.

     

Untersuchungen zur kenntnis der hummelfauna des pamir-hochlandes

Ohne Zusammenfassung     

Untersuchungen zur Entwicklung des Phycomyceten Allomyces arbuscula

Polysomes were isolated both from growing gametophytes of Allomyces arbuscula and from gametangia prepared from mycelia at different periods during gametogenesis. Analysis of polysomes by sucrose gradients showed that ribosomes present in the gametangia monosome pool were shifted into polysomes. This shift was found to be correlated with gametangia differentiation. The ribosome distribution remained virtually unchanged during the early stage of gamete formation. In mature gametes and swarming zygotes a low level of polysomes was detected. Labeling of rRNA by ³²PO₄ demonstrated a de novo synthesis of monosomes throughout the period of gametangia differentiation. No incorporation of ³²PO₄ was found to be present in ribosomes prepared from gametangia after onset of gamete formation. On the basis of these labeling experiments it is concluded that radioactivity in polysomes extracted from mature gametes and swarming zygotes can be attributed in part to conserved mRNA.Synchronous formation of gametangia was induced by transferring the vegetative mycelia from growth medium into a low salt buffer. Under these conditions the incorporation of either ³²PO₄ or ³H-uridine into RNA, particularly into rRNA, was found to be markedly decreased. This obviously indicates a shutdown of RNA synthesis. rRNA from induced mycelia examined by polyacrylamide gel electrophoresis was found to be severely degraded. In contrast to this, rRNA isolated from ribosomes of developing gametangia and from gametes exhibited no degradation products. It is suggested that endonucleases cause rRNA hydrolysis in the hyphal cytoplasm during gametangia differentiation. Ribosomes compartmentalized in gametangia seem to be inaccessible to nucleases during the later process of gametogenesis.

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Abkürzungen MAK Methyl-Albumin-Kieselgur - PAA Polyacrylamid - stains all 4,5,4,5-Dibenzo-3,3-diäthyl-9-methylthiacarbocyaninbromid (Serva, Heidelberg)     

Polarisationsoptisch-histochemische Untersuchungen zur Kongorotfärbung des Amyloid

Zusammenfassung Um den Färbemechanismus des Kongorot zu analysieren, wurden am Amyloid in Verbindung mit histochemischen Reaktionen polarisationsmikroskopisch das optische Vorzeichen der Doppelbrechung, der Farbstoffdichroismus und das Vorhandensein der anomalen grünen Polarisationsfarbe geprüft. Außer dem Dipolmoment der Amyloidfibrille ist ein orientiertes fibrillennahes Raumgitter zur Erzeugung des typischen polarisationsoptischen Farbeffektes notwendig. Zusätzlich hängt die Farbstoffakkumulation von der Fibrillendichte ab. Färbungen in wässerigen Kongorot-Lösungen unterscheiden sich von der Modifikation nach Puchtler durch eine initiale Bindung zwischen basischen Gruppen am Substrat und Sulfonsäureresten des Farbstoffes. Das Endergebnis, die parallel angelagerte Kongorotmizelle, ist in beiden Fällen gleich. Konsequenzen für die praktische Anwendung der Färbemethoden werden diskutiert.

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Polarization microscopic and histochemical investigations on the congo red-staining of amyloid

Summary For analysis of the staining mechanism of congo red the optical sign of birefringence, the stain dichroism and the occurrence of a green anomalous polarization colour were examined in amyloid utilizing a combination of histochemical reactions and polarization microscopy. In addition to the dipole moment of the statistically oriented amyloid fibrils there is necessary an oriented fibril-near spheric lattice to produce the specific polarization colour effect. Moreover the accumulation of dyes is depending on fibrillar density. Stainings in aqueous solutions of congo red are differing from the Puchtler-modification by an initial binding of basic groups of the substrate to sulphuric acid residues of the dye. In both cases unanimously the final result was found to be the parallel deposited congo red micelle at the amyloid fibril. The consequences for the use of staining techniques in practice are discussed.