Rhodanese activity and total sulfur content in frog and mouse liver

The activity of rhodanese was histochemically tested in cryostat sections of the frog (Rana temporaria) and mouse liver. The activity levels were evaluated in sections, and the results were expressed as the ratio of the area of all granules, products of the enzymatic test, to the total analyzed area (area fraction). The present study confirmed the biochemically detected activity of rhodanese, and showed a large pool of endogenous sulfane sulfur donors, substrates for rhodanese, in the frog liver. The area of a single granule corresponded to the size of the mitochondrium, what suggests enzyme localization in this organelle. In view of this it should be considered whether the rhodanese activity, biochemically detected in the cytosolic fraction of the frog liver, results from the enzyme action. The total content of sulfur in cryostat sections of the mouse and frog liver was calculated and compared on the basis of the Energy Dispersion Spectrum (EDS) obtained by a scanning microscope. These studies showed higher total sulfur content in the frog liver than in the mouse liver. The high total content of sulfur in the frog liver in autumn might be associated with sulfur storing for protein biosynthesis during the period of hibernation.