Specificity limits of L-leucine transport in chicken small intestine

Zusammenfassung Die Darmabsorption von Leucin wurde bei Hühnern in vitro im 5-Sekunden-Versuch untersucht und ein Absorptionssystem für Leucin beschrieben.     

Effects of acetaldehyde and/or ethanol on neutral amino acid transport systems in microvillous brush border membrane vesicles prepared from human placenta

Summary At 20 mM of acetaldehyde, the activities of three transport systems of L-alanine distinguished by the difference in their cation dependence, namely 1) Na⁺-specific, 2) Li⁺-dependent, and 3) Na⁺-independent systems, were significantly reduced in a similar manner. Only the Li⁺-dependent system was selectively inhibited at toxic concentrations of acetaldehyde and ethanol.     

d-Xylose,a substrate for the process of sugar active transport by the small intestine

Résumé Dans les cellules épithéliales de l'intestin grêle du Hamster, l'absorption de xylose comprend deux étapes: (1) uneentrée sensible à la phlorizine, et (2) une étape sensible au dinitrophénol, probablement équivalente à l'étape d'accumulation dépendant de l'énergie et typique des sucres actifs.

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A preliminary account was presented at the VII Giornate Biochimiche Latine, S. Margherita Ligure (Genova 1963), p. 87.     

Effect of a growth-promoting factor on protein synthesis and amino acid transport in vitro

Zusammenfassung Es wird nachgewiesen, dass sich in der Muskulatur ein Faktor befindet, der eine Anreicherung der -Amino-isobuttersäure in den Zellen hervorruft und der auch in vitro den Einbau von Leucin und damit die Proteinsynthese fördern kann. Ob dieser Faktor als Übermittler für Wachstumshormon wirkt, ist noch nicht abgeklärt.     

On the origin of small adrenergic storage vesicles: Evidence for local formation in nerve endings after chronic reserpine treatment

Zusammenfassung Die adrenergen Nervenendigungen der von Ratten, die während 6 Tagen Reserpin Iris erhalten haben, enthalten eine höhere Anzahl von länglichen synaptischen Vesikeln und Tubuli als diejenigen unbehandelter Kontrolltiere. Die Möglichkeit, dass die adrenergen Bläschen unter gewissen Umständen in den Nervenendigungen gebildet werden könnten, wird diskutiert.     

Evidence for a neuronal release of isotopically labelled γ-amino-n-butyric acid (GABA) from the rat dorsal medulla in vivo

Summary High potassium and electrical stimulation consistently increase efflux of labelled GABA from the in vivo superfused rat dorsal medulla in a calcium-dependent fashion. The depolarizing alkaloid, veratridine, also evokes a large increase in efflux of labelled GABA. These data strongly suggest release from a neurotransmitter pool in this region.Supported by grants from the Science Research Council to N.D. and C.G.D., FAPESP and CNPq (Brazil) to J.A.A. and CAPES and FAPESP (Brazil) to N.B.     

Juvenile hormone: Evidence for a role in the feeding rhythm ofOncopeltus fasciatus (Dallas)

Summary The diurnal feeding rhythm of female milkweed bugs was damped when fed nonhost seeds. Juvenoid treatment partially restored the normal rhythm. Precocene II-treated milkweed seed-fed females fed arrhythmicly during the light phase without reduced total feeding activity. This effect was largely prevented by simultaneous treatment with JH III.I thank Dr Judith H. Willis, Univ. of Illinois, for providing facilities, Meyer Schwartz of ARS, USDA, Beltsville, MD, USA, for providing the precocene II, and Dr W. S. Bowers, formerly of ARS, USDA, Beltsville, MD, for supplying the juvenoid. This work was supported in part by grant AG-00248 from the National Institutes of Health to J. H. Willis.     

Sensitivity of follicular melanoblasts in newborn mouse skin to tritiated thymidine: Evidence for a long term retention of label

Summary Injection of tritiated thymidine into newborn mice results in a progressive greying of hair that does not begin until after the first hair coat is grown. After a year the depigmentation is appreciable (about 60% of the hair are white). The effect cannot be simulated by external irradiation of newborn mice or by the administration of radioactive uridine or methionine. The effect can best be explained by a long-term retention of radioactivity in the DNA of melanocyte stem cells (melanoblasts) in spite of several rounds of cell division. This could be achieved by labelling the strands of DNA destined to act as templates throughout life by being selectively retained in the stem line as described in Cairns' hypothesis.Acknowledgments. This work was supported by grants from the Cancer Research Campaign. I am indebted to Joan Bullock for her careful, patient help with these experiments. CSP is a fellow of the Cancer Research Campaign.     

Evidence for a Na+/NH4+ exchange in the gill of trout adapted to sea water: adrenergic control]

A Na+/NH4+ exchange similar to that characterizing the fish gill in fresh water was shown to function in the trout adapted to sea water with the help of the head perfusion technique. This exchange stimulated by adrenaline through beta adrenoreceptors and inhibited by amiloride added to the external medium.