Adenyl cyclase activity in non-nucleated red blood cells: Evidence for its localization in the reticulocytes

Zusammenfassung Die durch Natriumfluorid und Isoproterenol stimulierbare Adenylcyclase-Aktivität in Erythrocyten-Schatten von 30–240 g schweren Ratten ist direkt proportional dem prozentualen Retikulocytengehalt des Blutes. Hinweise darauf, dass die Adenylcyclase-Aktivität kernloser Erythrocyten nahezu ausschliesslich in den Retikulocyten lokalisiert ist, konnten auch an menschlichem Blut erhalten werden.

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This work was supported by a grant from the Deutsche Forschungsgemeinschaft.

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The authors are indebted to Prof. Dr.Hj. Becker for support and helpful discussions.     

Magnetic enhancement of superconductivity from electron spin domains

Since the discovery of superconductivity, there has been a drive to understand the mechanisms by which it occurs. The BCS (Bardeen-Cooper-Schrieffer) model successfully treats the electrons in conventional superconductors as pairs coupled by phonons (vibrational modes of oscillation) moving through the material, but there is as yet no accepted model for high-transition-temperature, organic or 'heavy fermion' superconductivity. Experiments that reveal unusual properties of those superconductors could therefore point the way to a deeper understanding of the underlying physics. In particular, the response of a material to a magnetic field can be revealing, because this usually reduces or quenches superconductivity. Here we report measurements of the heat capacity and magnetization that show that, for particular orientations of an external magnetic field, superconductivity in the heavy-fermion material CeCoIn(5) is enhanced through the magnetic moments (spins) of individual electrons. This enhancement occurs by fundamentally altering how the superconducting state forms, resulting in regions of superconductivity alternating with walls of spin-polarized unpaired electrons; this configuration lowers the free energy and allows superconductivity to remain stable. The large magnetic susceptibility of this material leads to an unusually strong coupling of the field to the electron spins, which dominates over the coupling to the electron orbits.     

Reserpin und Glykogengehalt der Organe

Summary In fasted white mice, 1–18 h after the injection of 5 mg/kg Reserpine the glycogen content of brain, heart, skeletal muscle and liver is significantly increased (about 100%, in liver nearly 300%). It is suggested that this is due to an enhanced synthesis of glycogen from non-carbohydrate material.Concerning the underlying mechanism, it is pointed out that after reserpine there occurs a release of catecholamines from the adrenal medulla and-by stimulation of the anterior pituitary-an enhanced production of corticoids.Simultaneously with the increase of the brain glycogen, the level of lactic acid is decreased, whereas the ATP-, ADP- and AMP-content of the brain remains practically unaffected.

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Ausgeführt mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Simple methods for observing cortical granules in living mammalian eggs

Summary Simple light microscopic methods for routine observation and checking cortical granules of vital mammalian eggs will be described. By using interference contrast and dark field techniques, even small cortical granules can easily be examined. These methods are time-saving compared to the usual ones using an electron microscope. They make distribution studies possible without difficulties.     

Sequence and analysis of chromosome 1 of the plant Arabidopsis thaliana

The genome of the flowering plant Arabidopsis thaliana has five chromosomes. Here we report the sequence of the largest, chromosome 1, in two contigs of around 14.2 and 14.6 megabases. The contigs extend from the telomeres to the centromeric borders, regions rich in transposons, retrotransposons and repetitive elements such as the 180-base-pair repeat. The chromosome represents 25% of the genome and contains about 6,850 open reading frames, 236 transfer RNAs (tRNAs) and 12 small nuclear RNAs. There are two clusters of tRNA genes at different places on the chromosome. One consists of 27 tRNA(Pro) genes and the other contains 27 tandem repeats of tRNA(Tyr)-tRNA(Tyr)-tRNA(Ser) genes. Chromosome 1 contains about 300 gene families with clustered duplications. There are also many repeat elements, representing 8% of the sequence.     

Inversal relationship between basal adenylcyclase activity and maximal degree of stimulation in membranes of red blood cells from rats

Summary The degree of stimulation of adenylcyclase activity, in membranes from immature red blood cells from rats, brought about by isoprenaline, guanylyl-imidodiphosphate and sodium fluoride is strongly dependent on the basal activity of the enzyme. The inversal relationship between basal activity and the maximal degree of stimulation by (–) isoprenaline, shows an apparent seasonal dependence.This work was supported by a grant from the Deutsche Forschungsgemeinschaft.     

Alterations ofβ-adrenoceptor-density and cAMP-synthesis in rat-erythrocytes after stress erythropoiesis

Summary During the maturation of red blood cells from rats after stress erythropoiesis, adenyl cyclase activity and -adrenoceptor density (pmoles/mg protein) decrease at distinctly different rates suggesting a different turnover of these membrane units.Acknowledgments. This work was supported by the Deutsche Forschungsgemeinschaft. The skillful technical assistance of Mrs I. Groth and Mrs C. Kiele is gratefully acknowledged. The liquid scintillation spectrometer was a gift from the Dr Robert-Pfleger-Stiftung.