Absence of Ribonucleic Acid Methylase in the Avian Myeloblastosis Virus Core

N(2)-guanine-ribonucleic acid-methyltransferase, which is associated with avian myeloblastosis virus, is not a component of the viral core.     

Characteristics of rat normal mammary epithelial cells and dimethylbenzanthracene-induced mammary adenocarcinoma cells grown in monolayer culture

Summary The characteristics of normal mammary epithelial and 7,12-dimethylbenz[a]anthracene (DMBA)-induced adenocarcinoma cells derived from rats and grown in monolayer culture were compared. Normal mammary epithelial cells exhibited different morphology and agglutinability by plant lectins, slower growth rate, and lower saturation density and cloning efficiency. In addition, the normal cells were sensitive to the toxic effect of DMBA, and were unable to grow in soft agar or to form tumors, when inoculated into newborn Sparague-Dawley rats. The converse was true in each case for the adenocarcinoma cells. Supported by Public Health Service Research Grant CA 01237603 from the National Cancer Institute Portions of this paper were presented at the 65th Annual Meeting of the American Association for Cancer Research at Houston, Texas, 1974.     

Volume Production of Reference Seed Virus and Immune Ascitic Fluids for Six Arboviruses

SEED VIRUS REAGENT AND CONTROL AND IMMUNE ASCITIC FLUIDS WERE PREPARED FOR SIX ARBOVIRUSES: buttonwillow, epizootic hemorrhagic disease of deer, Turlock, anopheles B, Kern Canyon, and Semliki Forest. Pilot studies were initiated for each reagent to determine a satisfactory method for their production. Results of homologous and heterologous tests are reported.     

Düngeversuche an der Riveristalsperre

Zusammenfassung In der Riveristalsperre bei Trier wurden von März 1967 bis Oktober 1968 Düngeversuche mit Phosphat und Nitrat durchgeführt. Plastiksäcke wurden mit jeweils 70 1 Talsperrenwasser gefüllt und nach Nitrat- und Phosphatzugabe im See exponiert.Bei reiner Nitrat-Düngung konnte keine Vermehrung des Phytoplanktons gegenüber dem ungedüngten Wasser festgestellt werden. Dagegen vermehrte sich das Phytoplankton in den mit Phosphat gedüngten Säcken, und zwar konnte meist eine Abhängigkeit von der Stärke der Düngung festgestellt werden. Eine zur Phosphat-Düngung zusätzliche Nitrat-Düngung hatte nur in einigen Fällen eine Planktonvermehrung zur Folge.Diese Ergebnisse zeigen, daß in der Riveristalsperre das Phosphat Minimumfaktor für das Phytoplankton ist.

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Summary From March 1967 to October 1968 enrichment experiments with phosphate and nitrate were carried out in the Riveris reservoir near Trier (Fed. Rep. Germany). Plastic bags were filled with 70 liters of the reservoir water and placed into the lake after nitrate and phosphate was added.When only nitrate was added no propagation of the phytoplankton compared to the original water could be established. On the other hand the phytoplankton propagated in those bags to which phosphate was added; in most cases an increase according to the amount of phosphate could be noticed. Only in a few cases an increase of plankton could be seen when nitrate and phosphate were added.These results show that in the Riveris reservoir phosphate is a minimumfactor for the phytoplankton.

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Die Arbeit wurde durch ein Promotionsstipendium der Stiftung Volkswagenwerk gefördert.

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Aus dem Zoologischen Institut der Universität Bonn (Hydrobiologische Arbeitsgruppe Prof. Dr. H. Bick).     

The operation of the γ-aminobutyrate bypath of the tricarboxylic acid cycle in brain tissue in vitro

1. Cerebral-cortex slices prelabelled with gamma-amino[1-(14)C]butyrate (GABA) were incubated in a glucose-saline medium. After the initial rapid uptake there was no appreciable re-entry of (14)C into the GABA pool, either from the medium or from labelled metabolites formed in the tissue. The kinetic constants of GABA metabolism were determined by computer simulation of the experimental results by using mathematical procedures. The GABA flux was estimated to be 0.03mumol per min/g, or about 8% of the total flux through the tricarboxylic acid cycle. It was found that the assumption of compartmentation did not greatly affect the estimates of the GABA flux. 2. The time-course of incorporation of (14)C into amino acids associated with the tricarboxylic acid cycle was followed with [1-(14)C]GABA and [U-(14)C]-glucose as labelled substrates. The results were consistent with the utilization of GABA via succinate. This was confirmed by determining the position of (14)C in the carbon skeletons of aspartate and glutamate formed after the oxidation of [1-(14)C]GABA. These results also indicated that under the experimental conditions the reversal of reactions catalysed by alpha-oxoglutarate dehydrogenase and glutamate decarboxylase respectively was negligible. The conversion of [(14)C]GABA into gamma-hydroxybutyrate was probably also of minor importance, but decarboxylation of oxaloacetate did occur at a relatively slow rate. 3. When [1-(14)C]GABA was the labelled substrate there was evidence of a metabolic compartmentation of glutamate since, even before the peak of the incorporation of (14)C into glutamate had been reached, the glutamine/glutamate specific-radioactivity ratio was greater than unity. When [U-(14)C]glucose was oxidized this ratio was less than unity. The heterogeneity of the glutamate pool was indicated also by the relatively high specific radioactivity of GABA, which was comparable with that of aspartate during the whole incubation time (40min). The rates of equilibration of labelled amino acids between slice and medium gave evidence that the permeability properties of the glutamate compartments labelled as a result of oxidation of [1-(14)C]GABA were different from those labelled by the metabolism of [(14)C]glucose. The results showed therefore that in brain tissue incubated under the conditions used, the organization underlying metabolic compartmentation was preserved. The observed concentration ratios of amino acids between tissue and medium were also similar to those obtaining in vivo. These ratios decreased in the order: GABA>acidic acids>neutral amino acids>glutamine. 4. The approximate pool sizes of the amino acids in the different metabolic compartments were calculated. The glutamate content of the pool responsible for most of the labelling of glutamine during oxidation of [1-(14)C]GABA was estimated to be not more than 30% of the total tissue glutamate. The GABA content of the ;transmitter pool' was estimated to be 25-30% of the total GABA in the tissue. The structural correlates of metabolic compartmentation were considered.     

Elektronenmikroskopische untersuchung der milchröhren vonFicus elastica

Zusammenfassung Die Kautschukkügelchen vonFicus elastica entstehen entgegen den Literaturangaben im Zytoplasma und nicht in den Piastiden der Milchröhren. Sie sind von einer mehr oder weniger ausgeprÄgten Hülle umgeben. Es kommen nur wenige Piastiden in den Milchröhren vor, diese erzeugen StÄrke. Nur in geringer Entfernung von der Milchröhrenspitze findet man Dictyosomen. In Älteren Milchröhren befinden sich Filamente, die Ähnlich aussehen wie die Plasmafilamente der Siebröhren.

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Electron microscope observations in the latex vessels ofFicus elastica

Summary In contrast to the view hold in literature that rubber particles originate in plastids, inFicus elastica rubber particles are synthetized in the cytoplasm of the latex vessels. The globules are surrounded by a more or less distinct envelope. In the latex vessels only a few plastids occur, they produce starch. Dictyosomes are to be found but in a small distance from the tip of the vessel. The mitotic activity of the nuclei in latex vessels seems to be confined to apical zones as well. In latex vessels filaments occur similar to those in sieve elements.

     

Intraspezifische Aggression und räumliche Verteilung bei der Libelle Onychogomphus forcipatus (Odonata)

Zusammenfassung Die paarungsbereiten Männchen der Libelle Onychogomphus forcipatus sitzen auf Steinen am Ufer von Bächen, wo sie Weibchen erwarten. Gegen männliche Artgenossen sind sie aggressiv. Von Zeit zu Zeit fliegen sie auf, meistens, um mit anderen Männchen zu kämpfen. Danach kehren sie oft nicht zum bisherigen Sitzplatz zurück, sondern setzen sich-besondern an einförmigen Ufern — an eine offensichtlich zufällig gewählte Stelle. Eine statistische Analyse ergab eine zufällige Verteilung der Sitzplätze entlang der Uferlinie. Die Männchen dieser Libellenart grenzen also keine Territorien ab, sondern sind aggressiv, ohne gleichzeitig ortsgebunden zu sein. Dieses Verhalten ist als phylogenetisch ursprünglich bei Großlibellen anzusehen.

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Summary Sexually mature male specimens of Onychogomphus forcipatus perch on stones along the shoreline of rivulets waiting for mates. They react aggressively towards conspecific males. From time to time they fly around, mostly fighting other males. At uniform shorelines they often do not return to perch on the same site, but apparently choose perches at random. This is confirmed by a statistical analysis of the distribution of perching sites along the shoreline. It is concluded that males of O. forcipatus do not defend distinct territories but are aggressive without site attachment. This type of behaviour is considered as phylogenetically primitive in dragonflies.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.