The effects of caffeine on salt chemotaxis learning were investigated using the nematode Caenorhabditis elegans. To estimate the degree of salt chemotaxis learning, nematodes were placed in a mixed solution of NaCl and caffeine, and then the chemotaxis index of NaCl was obtained from the nematodes placed on agar medium after pre-exposure to caffeine concentrations of 0.01, 0.1, 0.3, and 1.0%. Locomotor activity and preference behavior for caffeine were also estimated under these caffeine conditions. Nematodes pre-exposed to 0.3% caffeine showed inhibition of salt chemotaxis learning. Additional experiments indicated that nematodes showed a preference response to the middle concentration of caffeine (0.1%), with preference behavior declining in the 0.3% caffeine condition. Stable locomotor activity was observed under 0.01-0.3% caffeine conditions. These results suggest that salt chemotaxis learning with 0.3% caffeine is useful for investigating the effects of caffeine on learning in nematodes.

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Die Oxidation von Benzoin (III) mit Pyridin‐N‐oxid ergibt in Gegenwart eines platinierten Palladiumkohle‐Katalysators quantitativ das Diketon (IV).

Beim Erhitzen von Pyridinen (I) mit Pyridin‐N‐oxiden (II) in Gegenwart von Palladium‐Platin‐Kohlenstoff werden asymmetrische (III) und symmetrische Dimere (IV) und (V) sowie Trimere (VI) gebildet.

Die Tetrahydroiso‐ chinoIin‐N‐oxide (I) cyclisieren in Gegenwart des Eisenkomplexes (II) zu den Alkaloiden (III), wobei die Isochinolinderivate (IV) und (V) als Nebenprodukte gebildet werden.