In vitro-Verfahren zur Bestimmung der DNS-Synthese-Dauer einzelner Zellen Biochemische Voraussetzungen und Ergebnisse

Zusammenfassung Nach Hemmung der de novo-Synthese von TMP durch 5-F-UdR läuft die DNS-Synthese in vitro in Anwesenheit von 10^–5 M/l mit unveränderter Geschwindigkeit ab. Dadurch ist die DNS-Synthese-Dauer über die quantitative autoradiographische Messung des ¹⁴C-TdR-Einbaus bestimmbar. Diese in vitro-Methode wird an Rattenknochenmark und Zellen einer CML geprüft. Erste Ergebnisse zeigen eine gute Übereinstimmung mit in vivo-Messungen durch andere Methoden.

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In vitro determination of the duration of DNA synthesis of individual cells

Summary Suspended haemopoietic cells are incubated in the presence of 5-fluoro-deoxyuridine (5-F-UdR) as an inhibitor of the de novo synthesis of thymidine monophosphate (TMP). The DNA synthesis rate remains undisturbed, if 10^–5 M/l thymidine (TdR) is added. Thus, the DNA synthesis rate of individual cells can be determined by means of a quantitative autoradiographic method in measuring the incorporation rate of ¹⁴C-TdR into the DNA of the cells. DNA synthesis rates are then converted into DNA synthesis times. This in vitro method has been checked in cells of rat bone marrow and of peripheral blood in a case of chronic myelocytic leukaemia (CML). Preliminary results correlate well with in vivo estimations obtained by other methods.

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Studie im Rahmen des Assoziationsvertrages EURATOM-GSF für Hämatologie Nr. 031 641 BIAD

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Unterstützt durch die Deutsche Forschungsgemeinschaft: SFB 51/5     

Von der Entwickelung einzelner Ascidienblastomeren

Ohne Zusammenfassung     

Quantitative 125-I-autoradiography of individual cells (author's transl)]

Iodine 125, an emitter of beta-radiation with an energy lying between that of tritium and carbon-14, is investigated for its applicability in quantitative autoradiography. Absorption and geometric factors of radiation are elucidated. From this, appropriate measuring conditions are derived. The simultaneous exposure of radioactive standard sources permits the evaluation of absolute amounts of radioactivity. Standard cells with labelled membranes are a suitable source of reference taking into account the physical properties of the isotope. Sheep red blood cells are examined for their suitability as standard cells after enzymatic radioiodination. The absolute number of antigenic substances on the surface of single cells is obtained by determining the specific activity of the labelled antibody molecules, and by measuring the silver grain densities of the cells under investigation and of the standard cells. The radioactivity per standard cell can be assessed by conventional procedures. The new method is applied to the quantification of membrane-bound immunoglobulin molecules of the IgG-type on single human lymphocytes. The determination of an immunologic saturation of the labelled antibody is essential for this purpose. On the lymphocytes of a normal person and of a patient with chronic lymphatic leukaemia quite different amounts of immunoglobulins have been evaluated.     

Sexchromatin in polyploiden Zellen

Ohne Zusammenfassung

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Sexchromatin in polyploiden Zellen

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Herrn Professor H. v. Hayek zum 65. Geburtstag gewidmet.

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Nach einem Referat, gehalten auf der gemeinsamen 9. Tagung der Deutschen Gesellschaft für Anthropologie und der Gesellschaft für Konstitutionsforschung.     

Studien an zerschnittenen Zellen

Ohne Zusammenfassung     

Quantitative Binding of 125I-Concanavalin A to Normal and Transformed Cells

We have measured the quantitative binding of the radioactively labeled agglutinin (125)I-concanavalin A to normal mammalian cells and simian virus 40- and polyoma virus-transformed cells from tissue culture. Parallel measurements of the amount of (125)I-concanavalin A necessary to cause agglutination of the cells in suspension were carried out. The transformed and nontransformed cells used for these experiments show large differences in their ability to be agglutinated by (125)I-concanavalin A. However, these cell lines have the same number of specific binding sites and similar affinities for the agglutinin whether transformed, trypsinized, or nontransformed. We conclude that the differential capacity of concanavalin A to agglutinate transformed cells relative to normal cells does not result from differences in the number of binding sites between the two types of cells.     

Das Sehfeld einzelner Sehzellen: Eine Richtigstellung

Ohne Zusammenfassung     

Die spektrale Empfindlichkeit einzelner Sehzellen des Bienenauges

Zusammenfassung In einzelne Sehzellen der Fazettenaugen von Bienenarbeiterinnen und Drohnen werden Mikroelektroden eingestochen; die bei Belichtung mit quantengleichen monochromatischen Lichtern im Bereich von 318–650 nm auftretenden intrazellulär abgeleiteten Rezeptorpotentiale werden gemessen.Die relativen spektralen Empfindlichkeitskurven einzelner Sehzellen werden bestimmt.Bei Drohnen finden sich drei Arten von Sehzellen mit verschiedener spektraler Empfindlichkeit; die Maxima liegen bei 340, 450 und 530 nm. Sehzellen mit dem Maximum der Empfindlichkeit bei 530 nm wurden bisher nur im äußersten ventralen Augenbezirk gefunden. Es ist möglich, aber nicht sicher, daß bei Drohnen Sehzellen mit einem Maximum der Empfindlichkeit bei oder unterhalb 318 nm vorkommen.Bei Bienenarbeiterinnen liegen die Maxima der Empfindlichkeit bei 340, 430, 460, 530 nm.Empfindlichkeitskurven mit mehr als einem Maximum werden als Artefakte gedeutet, da sie keine reproduzierbare Form haben.Die gemessenen Empfindlichkeitskurven stimmen mit den Absorptionskurven von Retinin-haltigen Sehfarbstoffen entsprechender Maxima überein.Der Verlauf der gemessenen Empfindlichkeitskurven entspricht dem Farbunterscheidungsvermögen der Bienen, wie es aus Verhaltensversuchen bekannt ist.

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Summary Microelectrodes were inserted in single visual cells of the compound eyes of honey-bee workers and drones. The eyes were exposed to monochromatic lights of equal quanta between 318 and 650 nm and intracellular receptor potentials were recorded.The relative spectral sensitivity curves of single visual cells were determined.In drones three types of visual cells with different spectral sensitivity were found, with the maxima at about 340, 450 and 530 nm. Visual cells with maximum sensitivity at 530 nm were found to date only in the extreme ventral region of the eye. It is possible, though not certain, that in drones there are visual cells with a maximum sensitivity at or below 318 nm.In honey-bee workers the sensitivity maxima lie at about 340, 430, 460 and 530 nm.Sensitivity curves with more than one maximum are interpreted as artefacts since their forms are not reproducible.The sensitivity curves reflect quite accurately the absorption curves of corresponding maxima for visual pigments containing retinene.The course of the sensitivity curves agrees well with the colour discrimination of honey-bees as has been shown in behavioural experiments.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

H3-Thymidin-Markierung einzelner Chromatiden in Riesenchromosomen

Summary Tritiated thymidine was administered to fertilized eggs of Chironomus tentans at the time of oviposition. Larvae hatching from these eggs were raised until the end of the 4th instar when they were dissected and their salivary glands squashed for autoradiography of the giant chromosomes. Good autoradiographs were obtained after 2 years exposure from preparations stored in plastic boxes.Three principal patterns of labelling were found: (1) single-strand labelling, where one or two chromosome pairs per nucleus show one single helical track of silver grains typically running from one end of the chromosome to the other; (2) two or four-strand labelling, where all chromosome pairs of a nucleus show 2 or 4 densely labelled tracks; and, (3), diffuse strand labelling where the level of labelling is generally low and the number of labelled strands per chromosome pair seems to be higher than 8. Approximately one half of all nuclei were found unlabelled. In 9 out of 70 chromosome pairs with single strand labelling the labelled strand begins at one end of the chromosome but ends interstitially.The labelled single strands must be intact mitotic half-chromatids (or crossover products of these) which received their label during DNA synthesis early in embryonic development, probably before blastoderm formation. A model of cell lineage involving selection against labelled nuclei accounts for the observed distribution of labelled single strands in our material. The occurrence of 2- and 4-strand labelling points to a smaller number of mitotic divisions preceding the formation of some portions of the salivary glands as contrasted with others. Cells showing this type of labelling have either not divided at all, or they are descendants of just one division, after the supply of tritiated thymidine was exhausted in early development. Our findings confirm the classical concept of polyteny.

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Herrn Professor Dr. Hans Bauer zum 60. Geburtstag.     

Probleme der Charakterisierung einzelner Chromosomen durch DNS-Messungen

Zusammenfassung Es wird eine Übersicht über die verschiedenen Methoden zur DNS-Messung an Chromosomen gegeben. Die Methoden werden kurz beschrieben und die wichtigsten Ergebnisse der verschiedenen Autoren diskutiert.

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Problems of characterizing individual chromosomes by measuring the DNA content

Summary A review of the different methods of determining the DNA content of individual chromosomes is given. The methods are described briefly, and the results of the different authors are discussed.

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Nach einem Referat anläßlich der 11. Tagung der Gesellschaft für Anthropologie und Humangenetik, Mainz, 7. 10. 1969.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft, AZ Mu 258/3.     

Untersuchungen zur Synchronisierbarkeit einzelner Pigmentmangel-Mutanten von Chlorella

Zusammenfassung Verschiedene Chlorella-Mutanten, die Chlorophyll a und b (Mutanten 10 und 11), je nach Kulturbedingungen nur Chlorophyll a oder Chlorophyll a und b (Mutante 41) oder nur Spuren von Chlorophyllen (Mutante 31) enthielten, wurden auf ihr Verhalten unter synchronisierenden Kulturbedingungen untersucht.Eine optimale Synchronisation war in einem Licht-Dunkel-Wechsel von 10 Licht- zu 14-Dunkelstunden zu erzielen.Die Synchronisationsschärfe war relativ gering. Unter keiner der angewendeten Kulturbedingungen ließ sich eine Vollsynchronisation erzielen; der Synchronisationstyp war am besten mit einer Gruppen-synchronisation zu vergleichen, bei der laufend Zellen von der einen in die andere Gruppe überwechseln.Unabhängig vom Vorhandensein von Chlorophyll a oder b und vom Ausmaß organischer Zusätze zu den Nährlösungen zeigten alle untersuchten Chlorella-Mutanten den gleichen Synchronisationstyp.Da die untersuchten Mutanten trotz verschiedener Pigmentzusammensetzung bis hin zum praktischen Chlorophyllverlust in gleicher Weise synchronisierbar sind, ist eine Beteiligung der Chlorophylle am Zeitgeber-Mechanismus als sehr unwahrscheinlich anzusehen.

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Studies on synchronization of some pigment-deficient Chlorella mutants

Summary Four different mutant strains of Chlorella pyrenoidosa were studied under conditions giving rise to synchronized mass cultures. The mutants contained either both chlorophyll a and b, only chlorophyll a or only traces of green pigments.Optimal synchronization was found to occur under a light-dark-regiment of 10:14 hours. It was impossible to achieve a complete synchronization; most of the cells developed autospores only every second cycle. This behavior was independent from the pigmentation of the strain; this was taken as evidence for the assumption, that the chlorophylls are not engaged in the timing process.

     

Rezeptorpotential und Nervenimpulse einzelner olfaktorischer Sensillen der Insektenantenne

Summary Using glass-capillary microelectrodes, receptor potentials and nerve impulses were recorded from single olfactory units on the antennae of some coleoptera and lepidoptera. These units proved to be the receptor cell endings of sensilla basiconica. Qualitative as well as quantitative differences of responses from single olfactory units might be sufficient for the central-nervous-system to discriminate a rather large number of different odors.