Freezing induced change in ligand orientation in oxycobalt-myoglobin

Single crystals of oxycobalt-myoglobin were examined by electron paramagnetic resonance (EPR) spectroscopy at ambient and cryogenic temperatures. The principal values and eigenvectors of the g-tensor and the hyperfine coupling tensor were determined. The Co--O--O bond angle was estimated to be 125 degrees at ambient temperature. The single crystal EPR dats of oxycobalt myoglobin at 77K showed two sets of the principal values for g and hyperfine coupling tensors and eigenvectors, indication that the bound oxygen molecule takes two distinct orientations. The result has demonstrated for the first time that the well defined change in the molecular orientation is induced upon freezing the biological macromolecule.     

The influence of 6-OHDA on hypothermia produced by intrahypothalamically-injected carbachol in the pigeon

Summary The involvement of the noradrenergic system in hypothermia induced by intrahypothalamically-injected carbachol (CCh) was studied by depleting hypothalamic noradrenaline (NA) with the catecholamine neurotoxin 6-hydroxydopamine (6-OHDA) and repeating the CCh injections after 6-OHDA treatment. The results suggest that noradrenergic neurons may be involved in hypothermia produced by CCh in the pigeon.     

Vesicles carrying nuclear material in matureCyprinus carpio erythrocytes

Zusammenfassung Chromatinhaltige feulgenpositive Bläschen wurden im Cytoplasma der Erythrocyten vonCyprinus carpio gefunden. Sie haben ihren Ursprung in den unmittelbar an der Kernmembran anliegenden Mitochondrien, die während der Chromatinaufnahme allmählich ihre Struktur verlieren.

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The authors wish to thank Mrs.Vera Mondin Weisz and Mr.C. A. Gonçalves Silva for their technical assistance and Mrs.Sibylle Heller for her editorial aid and translation. This research has been supported by the Conselho Nacional de Pesquisas (Proc. No. 10112/71) and Fundo Especial de Despesas do Instituto Butantan.     

Skeletal muscle capillary densities during reactive hyperemia

Summary Reactive hyperemia was induced in hindlimbs of rats by occlusion of the femoral artery. Using fluorescein dye as a peripheral vascular marker, we observed that there was an increase in the number of flowing capillaries supplying the muscle fibres following release of the occlusion. The results indicate that the number of flowing capillaries is not dependent on the duration of occlusion (2–10 min).     

A template for the rapid measurement of Rf-values in thin-layer chromatography

Zusammenfassung Eine Schablone zur direkten Messung von Rf-Werten auf Dünnschichtplatten wird beschrieben, deren Ausführung den Besonderheiten der Dünnschichtchromatographie angepasst ist. Mit Hilfe dieser Schablone konnte die Auswertung von Chromatogrammen vereinfacht und wesentlich beschleunigt werden.