Showing papers by "University of Tübingen published in 1971"

Stoffwechselprodukte von Mikroorganismen

Abstract: Candida lipolytica synthetisiert das Antibioticum Tryptanthrin aus 1 Mol Tryptophan und 1 Mol Anthranilsaure. Bei Verfutterung von Tryptophan und substituierter Anthranilsaure, bzw. substituiertem Tryptophan und Anthranilsaure, konnten die zu erwartenden Tryptanthrinderivate isoliert und identifiziert werden. Die Enzyme der Tryptanthrinbiosynthese wiesen in bezug auf diese Substrate, mit Ausnahme von Bromtryptophan, keine Spezifitat auf. Parallel zu diesen Versuchen wurden durch chemische Synthese substituierte Tryptanthrine hergestellt. Die Dierivate wurden auf ihre antibiotische Wirksamkeit gepruft; als besonders wirksam erwiesen sich die halogenierten Verbindungen.

Morphology and development of the macronuclei of the ciliates Stylonychia mytilus and Euplotes aediculatus.

Abstract: Some stages of macronuclear anlagen development, known from earlier investigations (see Fig. 1), were studied in detail. The results are: a) The giant chromosomes of Stylonychia mytilus are not somatically paired, but are connected end-to-end to form one or a few composite chromosomes. When they later disintegrate, the bands become isolated granules. b) Spectrophotometric measurements show that during the DNA-poor stage which follows the disintegration of the chromosomes, the macronuclear anlagen of Euplotes have a DNA content of 21 c, while the syncaryotic (deriving from syncarya) and hemicaryotic (deriving from haploid hemicarya) anlagen of Stylonychia have the DNA content of diploid micronuclei (2c). Nevertheless the syncaryotic anlagen of Stylonychia and Euplotes initially develop two nucleoli at the end of this stage, the hemicaryotic anlagen of Stylonychia only one. From this it is concluded that the genes of one giant chromosome band stay together in one granule, c) Labeled DNA from the giant chromosomes which remains in the anlagen during the DNA-poor stage is distributed approximately equally to the daughter nuclei during the first few fissions of the exconjugants.-Autoradiographic experiments showed that the DNA of the macronuclei of Stylonychia that is duplicated at one time in a replication band is not duplicated simultaneously during the next DNA-duplication. The DNA duplications during the second polyploidization stage of the macronuclear anlagen development are exceptions, because the mixing of the macronuclear DNA which occurs before every fission does not occur during the second polyploidization stage.—The pseudomicronuclei which sometimes are formed from the macronuclei in emicronucleated strains of Stylonychia contain numerous elements which are much smaller than the chromosomes.—The macronucleus of Stylonychia is very insensitive to irradiation with X-rays.—The results lead to the following hypothesis: The macronuclei of the two hypotrich ciliates contain unconnected chromomeres or small aggregates which are distributed at random to the two daughter nuclei during the divisions.

[Glutathione peroxidase: enzymology and biological aspects].

Abstract: Die Literatur zur Glutathionperoxidase (Glutathion: H2O2-Oxidoreduktase, EC 1.11.1.9) wird diskutiert.

Die Geschmacksknospen des Zwergwelses Amiurus nebulosus (Lesueur)

Abstract: Die auf den Barteln von Amiurus nebulosus liegenden Geschmacksknospen wurden morphologisch und histochemisch untersucht.

Changes in the interstitial pH of dog myocardium in response to local ischemia, hypoxia, hyper- and hypocapnia, measured continuously by means of glass microelectrodes

Abstract: In open-chest dogs the pH changes of the myocardial interstitium were measured during local ischemia, hypoxia, hyper- and hypocapnia. Microglasselectrodes (Corning 0150) were inserted into the wall of the left ventricle. Simultaneously we recorded the local myocardial blood flow, the arterial blood pressure, the heart rate and the expiratory CO2 concentration. Local ischemia was produced by transient occlusion of the left descending coronary artery. In the ischemic region a decrease in pH occurred after 15–30 sec, the magnitude of which depended on the occlusion time, and on the extent of the ischemic region. When the occlusion time was short, the maximum decrease in pH was found after the release of blood flow. Mean values varied from about 0.1 pH (1 min occlusion) to 0.65 pH (30 min occlusion). After fibrillation the pH fell by 1.2 units (mean value) below the initial level. Hypoxia (10% for 5–13 min) was accompanied by an increase in pH by 0.05–0.1 units. After 2–3 min the pH reached a steady state or decreased again. After ventilation with sufficient O2 concentration an acidotic overshoot occurred (0.03-0.1 pH). When shifts in the interstitial pH similar to those during ischemia and hypoxia were produced by varying the arterialpCO2, no comparable changes in local blood flow and in the other parameters could be observed.

Na K stimulated adenosinetriphosphatase: intracellular localisation within the proximal tubule of the rat nephron.

Abstract: With refinements of quantitative histochemistry, i.e. oilwell technique, enzymaticP ianalysis and NADP/NADPH cycling an enzymatic polarization of the tubular epithelial cell from the rat nephron to NaKATPase can be established. NaKATPase activity is limited to the basal area of the epithelial cell. Brush border fragments lack NaKATPase activity.

Pulse Fourier Transform 13C‐NMR Spectroscopy, Principles and Applications

Abstract: As a result of the development of pulse Fourier transform NMR spectroscopy 13C resonance has become accepted as a means of elucidating the structures of organic compounds having the natural 13C abundance. Assignment of the signals is facilitated by broad-band and off resonance proton decoupling and by knowledge of longitudinal relaxation times. The pulse Fourier technique, which is more sensitive and faster than conventional NMR spectroscopy because of multi-channel excitation, allows 13C measurements within a short time even on dilute samples of high molecular weight compounds without prior enrichment in 13C.

Impuls‐Fourier‐Transform‐13C‐NMR‐Spektroskopie, Grundlagen und Anwendungen

Abstract: Durch die Entwicklung der Impuls-Fourier-Transform-NMR-Spektroskopie hat sich die 13C-Resonanz als Methode zur Strukturaufklarung organischer Verbindungen mit naturlichem 13C-Gehalt durchgesetzt Breitband- und Off-Resonance-Protonen-Entkopplung sowie die Kenntnis longitudinaler Relaxationszeiten erleichtern die Signalzuordnung Die im Vergleich zur konventionellen NMR-Spektroskopie infolge Vielkanalanregung empfindlichere und schnellere Impuls-Fourier-Technik gestattet es, innerhalb kurzer Zeit 13C-Messungen selbst an verdunnten Proben hochmolekularer Verbindungen ohne vorherige 13C-Anreicherung durchzufuhren

Die Ortung von Wasserwellen durch Oberflächenfische

Abstract: 1. Die Ortung von Oberflachenwellen wurde bei 11 Arten aus 4 verschiedenen Knochenfischfamilien: Pantodontidae, Hemirhamphidae, Cyprinodontidae und Gasteropelecidae untersucht. Samtliche Tiere reagierten spontan auf einen Wellenreiz innerhalb von 40–50 msec. 2. Das Lokalisationsvermogen ist generell im Bereich vor dem Fisch starker ausgepragt als hinter ihm. Zwischen Richtungs- und Ortslokalisationsdiagrammen ergeben sich bis zu 30% Unterschied (Abb.1). Bei Gasteropelecus und Pachypanchax ist das Ortungsvermogen nur schwach ausgebildet. 3. Die Lokalisation einer Reizquelle erfolgt im optimalen Bereich bei Pantodon und E. sexfasciatus auf mindestens ±0,5 cm genau. Die Lokalisationsgrenze bei einmaligem Wellenreiz liegt fur Pantodon bei ca. 30 cm, fur die Epiplatys-Arten, Dermogenys und Carnegiella zwischen 13 und 21 cm. Der Lokalisationsbereich ist demnach fur alle Arten auf 3–3,5 Korperlangen beschrankt. 4. Die Schwellenamplituden bei Einzelreizen liegen fur Pantodon bei 4 μm, gefolgt von E. sexfasciatus, A. lineatus, D. pusillus, A. dayi und C. strigata mit Werten zwischen 4,9 und 9 μm. Die frequenzabhangige Empfindlichkeitskurve weist eine typische U-Form auf mit den geringsten Schwellenamplituden im Bereich von 10–40 Hz. Fur Pantodon wurden dabei 2 μm, fur E. sexfasciatus 4 μm und fur D. pusillus 5,5 μm gemessen. Der Frequenzbereich reicht bis maximal 160 Hz bei Pantodon.

New determination of the air-earth current over the ocean and measurements of ionosphere potentials

Abstract: The electrode effect could be detected in full magnitude on the Atlantic during the expedition of the research vessel ‘Meteor’. The average value of the electric field over the sea surface is about 125 V/m, in about 10 to 100 m over the surface only about 60 V/m. This phenomenon as well as the results of small ion records lead to a value of the air earth current density on the sea of only 0.9×10−12 A/m2, a quarter of the value accepted up to now. With these values the total current of the global air electric circuit will be about 665 A instead of 1500 to 1800 A. The ionosphere potentials over two places in a distance of 8000 km at 15 dates are nearly identical and in the average 280 kV.

On- and off-responses in the inferior colliculus of the Greater Horseshoe bat to pure tones

Abstract: 1. The auditory threshold curve of averaged evoked potentials of the colliculus inferior in Rhinolophus ferrum equinum to pure tone stimulation from 1 to 100 kHz is presented (Fig. 1). For pure tone frequencies lower than 14 kHz thresholds steeply rise from 20 to 110 db. The steepness of the acoustical filter for 83.3 kHz signals and the frequency of the echoes heard by Greater Horseshoe Bats is accentuated by averaging methods. Because of averaging, evoked potentials thresholds are lowered by about 20 db compared to those obtained by non-averaging methods. 2. Prominent off-responses in evoked potentials appear for three stimulus frequency ranges: 3–10 kHz with a peak at 5 kHz, 20–40 kHz with a peak at 20 kHz and 80.0–82.6 kHz with a peak at 81.5 kHz (Fig. 2). 3. It is unlikely that beat note frequencies play any role for echolocation. 4. The relevance of these results to echolocation in Horseshoe Bats is discussed, especially as to Doppler shift information contained in the constant frequency part of echoes.

Der Einfluß der Durchblutung auf die Resorption von Harnstoff, Methanol und Äthanol aus dem Jejunum der Ratte

Abstract: 1 Jejunal loops in anaesthetized rats were perfused with14C-labelled urea, methanol, and ethanol in buffered isotonic saline solutions at pH 7 The blood flow, the disappearance rate from the intestinal lumen and the appearance rate in the intestinal venous blood were determined simultaneously 2 A decrease of the blood flow from about 18 to 02 ml min−1 g−1 wet tissue diminished the disappearance and appearance rate of the substances and eventually their metabolites An increase of the blood flow caused the reverse results The dependence on blood flow was greater for the appearance than for the disappearance rate The two transfer rates and their dependence on blood flow were smaller for urea than for methanol and ethanol 3 The experimental data are discussed by means of one three- and two four-compartment models Blood flow independent permeability coefficients for the intestinal epithelium were derived: urea 0062±0015, methanol 023±006, ethanol 024±009 ml min−1 g−1 The permeability coefficients for the subepithelial tissue were also calculated: urea 005±002, methanol 0066±0007, ethanol 0081±0015 ml min−1 g−1

Anisotropy of solar hard X-radiation during flares

Abstract: The angular distribution of solar flare associated hard X-rays (≳ 10 keV) is calculated on the assumption that they originate as bremsstrahlung emission of energetic electrons with a power law spectrum. For the cross section the relativistic Sauter formula was used. Supposing the electrons to move in a fixed direction, the X-radiation is considerably anisotropic, especially at high photon energies. Taking into account a magnetic field, the anisotropy decreases with increasing pitch angles of the electrons. The anisotropic angular distribution of solar X-radiation seems to be connected with the centre-to-limb variation of hard X-ray bursts and with the correlation of shortwave fadeouts and geomagnetic crochets to Hα flares.

Synchronization of Dunaliella cultures

Abstract: Dunaliella cells exhibit different temperature optima for photosynthesis and cell division. Using this observation a combined light-dark and highlow temperature treatment is given to synchronize cell suspensions.

Struktur und funktion des sekundären kopulationsapparates der Odonaten (Insecta, Palaeoptera), ihre wandlung in der stammesgeschichte und bedeutung für die adaptive entfaltung der ordnung

Abstract: Three non-homologous structures act as intromittent organs: ligula (Zygoptera), hamuli posteriores (Anisozygoptera, ), vesica spermalis (Anisoptera). Ligula and vesica spermalis are anchored by means of hydraulically working “gland”-structures, Ligula-Schwellkorper and Vesica spermalis-Schwellkorper respectively. A sperm-pump (Ausspritzkammer) extends the function of Vesica spermalis-Schwellkorper in non-aeschnoid Anisoptera, a group found to be monophyletic. The study includes a depiction of the peripheral abdominal nerves of larva and imago.

Nachweis innermolekularer Beweglichkeit durch NMR‐Spektroskopie, XXIII. Mechanismus der syn‐anti‐Isomerisierung in Iminen. Diastereotopie und Enantiotopie

Abstract: In o.o′-diisopropyl-substituierten Anilen des Typs X2C N-Aryl (1–4) wird temperaturabhangige magnetische Nichtaquivalenz der geminalen Methylgruppen im Isopropylrest gefunden. Die Energiebarriere des Verschwindens der magnetischen Nichtaquivalenz (Enantiotopomerisierung) ist derjenigen der syn-anti-Topomerisierung vergleichbar. In unsymmetrischen Anilen (XX′CN-Aryl; X = X′) ist die Barriere groser als diejenige der syn-anti-Isomerisierung. Daraus last sich abschatzen, das auf 108 Inversionsvorgange am doppelt gebundenen Stickstoff in 8 weniger als eine Rotation um die CN-Doppelbindung kommt. Der Mechanismus der planaren Inversion wird ausfuhrlich diskutiert. Eine Nomenklatur zur Unterscheidung von Molekulen, die durch Austausch chemisch gleicher Molekulgruppen entstehen (manchmal „entartete Isomere” genannt), wird vorgeschlagen und kurz erlautert. Detection of Intramolecular Mobility by N.M.R. Spectroscopy, XXIII. Mechanism of the syn-anti-Isomerization in Imines. Diastereotopy and Enantiotopy A temperature-dependent magnetic nonequivalence of the-geminal CH3 groups of o,o′-diisopropyl substituted anils (X2CNAryl) has been found. This phenomenon („enantiotopomerization”) requires the same energy as the syn-anti-topomerization. In unsymmetrical anils (XX′CNAryl, X ≠ X′) the barrier of enantiotopomerization is much higher than the one of the syn-anti-isomerization. This leads to the conclusion that during 108 inversion processes in 8 less than one rotation occurs. The mechanism of planar inversion is discussed in detail. A nomenclature for description of molecules that are formed by exchange of chemically identical groups (degenerate isomers) is proposed and briefly discussed.