The contribution of aromatic components in Katsuobushi to preference formation and reinforcement effect

Katsuodashi, a dried bonito broth, is very basic and indispensable in Japanese cuisine and contains taste-exhibiting components and unique aroma. We previously reported that its unique aroma contributes to the preference and reinforcement effect associated with dried bonito. This study aims to elucidate the contribution of aromatic components in Katsuobushi to preference formation and reinforcement effect. Volatile components obtained from dried bonito were fractionated and the fractions were subjected to two-bottle choice test. The fractionation test suggested that the component responsible for the preference is not one but comprises multiple components. In the GC–MS analysis/reconstruction test, solution with aromatic flavor narrowed down to 125 compounds had preference, and also had reinforcement effect. Moreover, GC–MS–olfactometry analysis narrowed down the candidate components to 28 out of 125. Mice showed preference for the test solution with aromatic flavor reconstructed with 28 components but did not show reinforcement behavior.     

Studies of Interaction between Chloroplast Coupling Factor 1 and Nucleotides by Circular Dichroism and Ultra-Violet Spectroscopies

When ADP, CDP, GDP, IDP or UDP was mixed with chloroplast couplingfactor 1 (CF₁) in the presence of MgCl₂, changes were inducedin the ultraviolet absorption spectrum as well as the circulardichroism spectrum. These changes were about 70% complete inone minute. Also, these two changes were similar in the concentrationcurves of nucleotides, the competition between ADP with CDP,the inhibition by PP₁, and the requirement for divalent cations.A minor difference was also noted in the requirement for divalentcations by some of the nucleotides. The order of the affinitiesof these nucleotides for CF₁ was: ADP>CDP>UDP>IDP>GDP.The UV spectral changes induced by these nucleotides are interpretedas shifts of the absorption spectra of bound nucleotides bysome 10 nm to longer wavelengths accompanied by decrease inabsorbance. In difference CD spectra, negative peaks were foundat about the same wavelengths of the absorption peaks of therespective nucleotides. Ca²⁺ was as effective as Mg²⁺ to these changes induced by ADPor GDP, but less effective than Mg²⁺ for those induced by CDP,UDP or IDP. In the presence of EDTA, the changes induced byADP were somewhat lower and those induced by CDP, UDP or IDPbecame almost zero. However, the UV absorbance change inducedby GDP was larger in the presence of EDTA than in the presenceof Mg²⁺ or Ca²⁺. (Received October 27, 1980; Accepted February 27, 1981)     

Temporal variation of the static electric field inside an animal cage

The temporal variation of a static electric field inside an animal cage was investigated with a newly developed small, simple field meter. The field inside the cage was found to be highly dependent on the surface conductivity of the dielectric material. As the surface of the cage became dirty because of animal occupancy, the static electric field inside it became considerably smaller from the moment the field was turned on. Clean cages also modified the static electric field inside them, the field decaying from an initial to a much lower value over several hours. The mechanism of field attenuation for both cases is surface leakage. Surface leakage for a clean cage takes place much more slowly than for a dirty cage. This was confirmed by measuring DC insulation resistance. To examine this phenomenon further, the field in a metal cage with high electrical conductivity was measured. The static electric field inside the metal cage was also found to be reduced. An improved cage design that avoids these problems, is suggested for the study of the biologic effects of static electric fields.