Neurosécrétion et régulation hydroélectrolytique chezArtemia salina

Summary The activity ofArtemia protocerebral median neurosecretory cells is stimulated when animals are grown in media whose tonicity is lower than that of sea weater. The substance liberated by these cells could regulate the tonicity of the internal medium.

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Neurosécrétion et régulation hydroélectrolytique chezArtemia salina

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Travail réalisé avec l'appui financier du FRFC (programme No 2.9010.75).     

Two related butterfly species avoid oviposition near each other's eggs

Summary Some butterfly species avoid egg-laying on plants which already bear conspecific eggs, and thus reduce food competition between their offspring. In twoPieris species the females produce in their accessory glands an oviposition-deterring pheromone (ODP), which is combined with the egg during oviposition. The ODP collected from eggs or accessory glands ofP. brassicae inhibits oviposition byP. rapae and vice versa. The ODP of either species stimulates tarsal receptors in both species. The antennae of the two pierids respond to the volatiles of their own and each other's eggs. Thus the ODPs of the two species may reduce not only intraspecific, but also interspecific food competition between their larvae.     

Estimation of the methylating capacity of the pineal gland. With special reference to indole metabolism

Summary In order to obtain more information on the methylating capacity of the pineal gland, a method determining the formation of different 5-methoxyindoles in the pineal gland was developed. The method depends on measuring the incorporation of labelled methyl groups into the various hydroxyindoles present in the pineal gland, after incorporation of pineal tissue with labelled S-adenosyl methionine. Hydroxyindoles were not added to the incubation medium. After incubation thin-layer chromatography was performed with pineal tissue together with the incubation medium; the spots were scraped and counted.The authors wish to express their gratitude to Prof. Dr. J.C. van de Kamer and Dr F.C.G. van de Veerdonk for their stimulating interest in these studies.     

Activity increases quantal size at the frog neuromuscular junction

Two h of nerve stimulation at 10 Hz or of elevated spontaneous release in hypertonic solution increased the size of miniature end-plate potentials (m.e.p.p.'s) and currents at the frog neuromuscular junction, probably by increasing the amount of acetylcholine in a quantum. Increases in quantal size may modulate synaptic transmission.     

Antagonistic activity of galanthamine on constant infusion of pancuronium in rats

Summary The effect of galanthamine, an anticholinesterase having a tertiary ammonium group, on a constant infusion of pancuronium was studied in the rat tibialis anterior-sciatic nerve preparation. The results were compared with those previously obtained with neostigmine, pyridostigmine, and 4-aminopyridine. The antagonizing activity of galanthamine is similar to that of 4-aminopyridine and less than that of the other 2 anticholinesterases. The duration of galanthamine antagonism is similar to that of neostigmine and pyridostigmine but less than that of 4-aminopyridine.