Cytological demonstration of female heterogamety in isopods

Résumé Des chromosomes sexuels, inconnus jusqu'à présent chez les Isopodes, ont été trouvés dans 4 espèces de la superespèceJaera marina (Janiridae, Asellota). Il s'agit d'un système multiple de chromosomes sexuels, ce qui aboutit à la formation d'un trivalent sexuel dans la méiose femelle. Les femelles — hétérogamétiques — ont la constitution XY₁Y₂, les mâles étant XX. D'après les données chromosomiques présentées par les 4 espèces étudiées, la formation du système multiple sexuel est due à des processus cytologiques évolutifs d'ordre Robertsonien.

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Aided by a grant from the Janggen Pöhn Foundation (St. Gallen, Switzerland) and supported by the Swiss Commission for the Biological Station of Roscoff.     

Photoreceptor damage following exposure to excess riboflavin

Flavins generate oxidants during metabolism and when exposed to light. Here we report that the photoreceptor layer of retinas from black-eyed rats is reduced in size by a dietary regime containing excess riboflavin. The effect of excess riboflavin was dose-dependent and was manifested by a decrease in photoreceptor length. This decrease was due in part to a reduction in the thickness of the outer nuclear layer, a structure formed from stacked photoreceptor nuclei. These changes were accompanied by an increase in photoreceptor outer segment autofluorescence following illumination at 328 nm, a wavelength that corresponds to the excitation maxima of oxidized lipopigments of the retinal pigment epithelium.     

Bilateral lesions of suprachiasmatic nucleus eliminate circadian rhythms of oxygen consumption and the respiratory quotient in rats

Summary Bilateral lesions of the suprachiasmatic nucleus of the hypothalamus of rats abolished circadian rhythms of oxygen consumption and of the respiratory quotient (RQ). The RQ remained constant at a level intermediate between the maximum (about 1.0) and minimum (about 0.9) values in control animals.     

Bovine pituitary intraglandular colloid fraction F5 localized in the rat endocrine pancreas

Bovine pituitary intraglandular colloid thought to be a waste product, is the holocrine secretion of intermediate lobe cells. It is housed in the intraglandular lumen (residual lumen) and is extruded into the venous circulation of the cavernous sinuses via clefts in the capsule of the gland aligned with the intraglandular lumen. Intraglandular colloid, fraction F5 (mol.wt 34,000), radiolabeled with (125I)Na and injected (0.15 ml) into the right internal jugular vein of male Wistar rats, accumulated in the endocrine pancreas. Autoradiographs showed that the material had specifically localized in the capillary network of the endocrine pancreas. Since the intermediate lobe is poorly vascularized, intraglandular colloid is considered to be the transport medium for intermediate lobe materials.     

A medium to demonstrate the ligninolytic activity of some fungi

Zusammenfassung Es wird hier eine neue Methode angeführt, um die holzauflösende Fähigkeit einiger Pilze zu bestimmen. Ein milchiges, homogenes Agarmedium wird hergestellt, indem man kugelgemahlenes Buchensägemehl als hauptsächliche Kohlenstoffquelle benutzt. Wenn man in dieses Medium bestimmte holzzerstörende Pilze einpflanzt, wird sowohl ihre holzspaltende als auch ihre zellulosezerstörende Wirkung dadurch gezeigt, dass das Medium unter dem Wurzelgeflecht sich aufklärt.     

Der Einfluss von adrenergen Rezeptoren-Blockern auf die Wirksamkeit von Strahlenschutzsubstanzen

Summary The effect of -adrenergic receptor-inhibitors was examined in relation to the effectiveness of radioprotective agents. The results, when mice were irradiated, show that the receptor-inhibitors significantly reduced the effect of the applied protectors.     

Reserpine-induced depletion of gastric vitamin B12-binding proteins in the rat

Zusammenfassung Reserpin mobilisiert Histamin und den «Intrinsic factor» aus dem Rattenmagen. Eine trunkuläre Vagotomie hebt diese Wirkung von Reserpin auf. Reserpin hat keinen Effekt auf den «Intrinsic factor» des Magens von Maus, Hamster, Meerschweinchen und Kaninchen.

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Supported by grants from the Swedish Medical Research Council (No. B71-14X-1007-05C and No. B71-19X-766-05C), the Medical Faculty of Lund, and Albert Pahlson's Foundation.